The American Journal of Sports Medicine http://ajs.sagepub.com/
Medial Opening Wedge High Tibial Osteotomy for Medial Compartment Overload/Arthritis in the Varus Knee: Prognostic Factors Davide Edoardo Bonasia, Federico Dettoni, Gabriele Sito, Davide Blonna, Antongiulio Marmotti, Matteo Bruzzone, Filippo Castoldi and Roberto Rossi Am J Sports Med published online January 21, 2014 DOI: 10.1177/0363546513516577 The online version of this article can be found at: http://ajs.sagepub.com/content/early/2014/01/17/0363546513516577 A more recent version of this article was published on - Feb 28, 2014
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Medial Opening Wedge High Tibial Osteotomy for Medial Compartment Overload/Arthritis in the Varus Knee Prognostic Factors Davide Edoardo Bonasia,*y MD, Federico Dettoni,z MD, Gabriele Sito,z MD, Davide Blonna,z MD, Antongiulio Marmotti,z MD, Matteo Bruzzone,z MD, Filippo Castoldi,z MD, and Roberto Rossi,z MD Investigation performed at the University of Torino, Torino, Italy Background: Medial opening wedge high tibial osteotomy (OWHTO) is a widely accepted procedure for the treatment of medial compartment arthritis of the knee. Compared with closing wedge HTO, however, the outcomes of OWHTO reported in the literature are incomplete. Purpose: To identify the positive and negative prognostic factors related to the outcomes of OWHTO through an evaluation of midterm study results and survivorship analysis. Study Design: Case series; Level of evidence, 4. Methods: From January 2001 to December 2009, a total of 141 consecutive OWHTOs were performed in 123 patients. Only patients with symptomatic medial knee overload/arthritis were included. The patients were evaluated preoperatively and at every follow-up visit with (1) the Knee Society score, (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) another self-evaluation scale, (4) long-leg radiographs, and (5) plain radiographs. Preoperative, intraoperative, and postoperative variables were investigated to find an association with the outcomes. Results: Of the 123 patients, 15 were lost to follow-up, and 24 were excluded from the study, leaving 84 patients (99 OWHTOs) for the present study. The mean age of the patients at the time of surgery was 54.5 6 9.2 years. The mean follow-up was 51.5 6 23.8 months. The Knee Society and WOMAC scores significantly improved after surgery (P \ .001). The variables significantly related to a poor outcome were (1) age .56 years (P = .008) and (2) postoperative knee flexion \120° (P \ .001); the variables significantly related to a good outcome were (1) Ahlba¨ck grade 0 arthritis of the medial compartment (P \ .001) and (2) excellent preoperative Knee Society score (P \ .001). The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years. Conclusion: With correct indications, OWHTO is a reliable procedure for medial knee arthritis/overload. The outcomes reported are similar to those from other studies, although the variables related to outcomes are slightly different. Keywords: knee; arthritis; HTO; high tibial osteotomy; opening wedge; OWHTO
Unicompartmental medial knee arthritis is a very common condition and can represent a challenge for the orthopaedic
surgeon, mostly in young and active patients. In these patients, high tibial osteotomy (HTO) is a widely accepted procedure that can rely on good outcomes with correct indications. Clinical indications for HTO include varus alignment of the knee associated with medial compartment arthrosis, knee instability, medial compartment overload (ie, after medial meniscectomy), and osteochondral lesions requiring resurfacing procedures.24 Many techniques have been described for HTO, whether alone or in combination with other procedures. These include closing wedge HTO (CWHTO), opening wedge HTO (OWHTO), dome, and ‘‘en chevron’’ osteotomies, with CWHTO and OWHTO being the most commonly used.5 Opening wedge HTO has recently risen in popularity because of its easy technique (without the need for proximal tibiofibular joint
*Address correspondence to Davide Edoardo Bonasia, MD, Azienda Ospedaliera Citta` della Salute e della Scienza, Centro Traumatologico Ortopedico Hospital, University of Torino, Via Lamarmora 26, 10128, Torino, Italy (e-mail: [email protected]). y Azienda Ospedaliera Citta` della Salute e della Scienza, Centro Traumatologico Ortopedico Hospital, University of Torino, Torino, Italy. z Mauriziano Umberto I Hospital, University of Torino, Torino, Italy. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546513516577 Ó 2014 The Author(s)
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Figure 1. Preoperative anteroposterior radiographs showing initial medial compartment arthritis. (A) Weightbearing full extension and (B) Rosenberg view. disruption, fibular osteotomy, or common peroneal nerve dissection), the possibility of multiplanar correction (both sagittal and coronal planes can be modified), and the theoretical, easier subsequent total knee replacement (TKR) compared with CWHTO. It is accepted that the results of HTO deteriorate over time.5 However, early failure rates ranging from 10% to 50% have been described,32 and understanding the indicators for poor outcomes is essential in identifying the ideal candidates for HTO. A vast literature is available regarding the long-term outcomes and positive/negative prognostic factors of CWHTO. On the other hand, the literature regarding OWHTO is incomplete, most of all regarding prognostic factors. The goal of this study was to identify the positive and negative prognostic factors related to the outcomes of OWHTO. Evaluation of the midterm results and survivorship analysis have been performed. The correlation of preoperative, intraoperative, and postoperative variables with the outcomes has been evaluated.
MATERIALS AND METHODS A total of 141 consecutive OWHTOs were performed at our institution from January 2001 to December 2009. The indications of OWHTO for medial compartment overload/arthritis included patients younger than 65 years, medial arthritic changes less than grade III (Ahlba¨ck classification), and varus alignment (Figure 1). Absolute contraindications included symptomatic degenerative changes of the patellofemoral and lateral compartments, neutral or valgus alignment, active infection, and severe reduction of knee range of motion (ROM) (flexion contracture .5°, flexion \100°). Only patients undergoing OWHTO for symptomatic medial knee overload or arthritis were included in the study. We excluded OWHTOs performed for other conditions (ie, instability, instability 1 overload/arthritis,
Figure 2. Preoperative planning on anteroposterior long-leg radiographs. Slight valgus overcorrection (3°-5° of valgus, 62.5% of the lateral tibial plateau) was generally planned.
asymptomatic severe varus in young patients, focal osteochondral lesions in malaligned knees, overload in meniscectomized knees requiring meniscus transplant, malalignment after intra- and extra-articular fractures). Generally, 3° to 5° of valgus overcorrection was planned preoperatively, as described by Dugdale et al10 (Figure 2). In the case of young patients with minimal degeneration of the medial compartment, correction to a neutral mechanical axis was planned.
Surgical Technique All surgeries were performed according to the technique previously described by Rossi et al.24 The patient was positioned supine on a radiolucent operating table, with a tourniquet around the proximal thigh. When necessary, arthroscopic surgery was performed first to treat associated injuries. Then, a 5-cm longitudinal incision was
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Figure 3. Surgical technique. (A) Guide wire insertion and bone cut distal to it, (B) osteotomes used to open the osteotomy, (C) opening of the osteotomy with graduated wedges, and (D) plating of the osteotomy. made, extending from 1 cm below the medial joint line midway between the medial border of the tibial tubercle and the posteromedial border of the tibia. The sartorius fascia was incised and the pes anserinus retracted distally with a blunt retractor, exposing the superficial medial collateral ligament (sMCL). The sMCL was partially detached with a Cobb elevator. A blunt retractor was passed deep to the MCL to protect the posterior neurovascular structures. Next, the medial border of the patellar tendon was identified, retracted, and protected throughout the whole procedure. A guide wire was inserted, beginning at the anteromedial tibia at the level of the superior border of the tibial tubercle (approximately 4 cm distal from the joint line) and aiming the tip of the fibular head (approximately 1 cm below the lateral articular surface). Positioning of the guide wire was assessed under fluoroscopy. The tibial osteotomy was performed immediately distal to the guide wire to avoid proximal migration of the osteotomy into the joint (Figure 3A). In the sagittal plane, the osteotomy was performed parallel to the posterior tibial slope. A small oscillating saw was used to cut the tibial cortex from the tibial tubercle around to the posteromedial corner under direct visualization. Using intermittent fluoroscopy, graduated, thin flexible osteotomes were used to advance the osteotomy to within 1 cm of the lateral tibial cortex (Figure 3B). The mobility of the osteotomy was checked by gentle manipulation of the leg with valgus force. Calibrated wedges were then inserted into the osteotomy and advanced slowly until the desired opening was achieved (Figure 3C). A long alignment rod was used to assess the
accuracy of the calculated preoperative wedge size. Maintenance of the anatomic tibial slope was assessed fluoroscopically and by direct visualization. Once the desired correction had been achieved, plating was performed, and the wedges were removed (Figure 3D). Fixation was performed in all cases with a first-generation Puddu plate (Arthrex Inc, Naples, Florida, USA) with a rectangular spacer. For openings greater than 10 mm, the osteotomy gap was filled with bone substitutes (HATriC, Arthrex Inc) or autologous iliac crest bone grafting. For a smaller correction, the gap was left untreated. Postoperatively, the knee was placed in a hinged brace set at 0° to 90°, and the patient was restricted to touch weightbearing (20 kg) for 1 month. At 1 month after surgery, if knee radiographs showed maintenance of the correction, weightbearing progressed to 50% of the body weight, and the brace was unlocked. At 2 months, after radiographic control, the patient progressed to full weightbearing and the brace was discontinued. In the case of combined HTO and microfracture, the patient was prescribed nonweightbearing for 1 month and then progressed as per isolated HTO. Patients were evaluated preoperatively and at every follow-up visit with (1) the Knee Society score, (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) other self-evaluation tests including the visual analog scale (VAS) for pain experienced in the previous week and patient responses to whether they would undergo the surgery again, (4) longleg radiographs, and (5) plain radiographs with anteroposterior, lateral, and skyline views (Figure 4). The patients’
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Figure 4. Postoperative radiographs. (A) Anteroposterior (AP) view, (B) lateral view, and (C) AP view of long-leg radiograph. evaluations and data collection were performed by 2 independent investigators trained in knee surgery (D.E.B. and F.D.). Numerous variables were investigated to find an association with the outcomes, including preoperative (age, sex, body mass index [BMI], amount of varus malalignment, ROM, Knee Society score, WOMAC score, previous knee surgeries, amount of arthritic changes in the medial, lateral, and patellofemoral compartments), intraoperative (associated arthroscopic procedures, size of the plate), and postoperative (ROM, alignment, residual medial instability consequent to the sMCL detachment) variables. Medial arthritis of the knee was graded according to the Ahlba¨ck classification,2 while patellofemoral degenerative changes were graded with a modified Altman classification (grades 0-3).4 The size of the plate depended basically on 2 factors: the required correction angle and the size of the patient’s tibia. The postoperative medial opening was clinically evaluated (at both 0° and 30° of flexion) by 2 independent investigators trained in knee surgery. When both investigators identified a medial opening greater than 2 mm in the affected side, compared with the unaffected side, the datum was considered significant. A paired t test was used to compare Knee Society and WOMAC scores before and after surgery. The Pearson x2 test was used for categorical variables, while simple logistic regression was performed for nominal variables. All variables that were statistically significant (P \ .05) or close to significance with simple logistic regression were then inserted in a multiple regression model. In addition, Kaplan-Meier survival analysis was performed. For the survival analysis, revision to TKR or indication for TKR because of the recurrence of symptoms was considered as end points.
RESULTS Of 123 patients, 15 were lost to follow-up, and 24 were excluded from the study because they did not match the
TABLE 1 Intra-articular Procedures Associated With Opening Wedge High Tibial Osteotomy Concomitant Intra-articular Procedure
n
Diagnostic arthroscopic surgery Partial medial meniscectomy Partial lateral meniscectomy Microfracture Partial medial meniscectomy 1 microfracture Partial medial meniscectomy 1 abrasion arthroplasty Abrasion arthroplasty Total
18 18 2 13 6 1 2 60
inclusion criteria. Therefore, 84 patients (99 knees) were included in the present study. The mean age of the patients at the time of surgery was 54.5 6 9.2 years, and the mean BMI was 27.6 6 3.7 kg/m2. The mean follow-up was 51.5 6 23.8 months. Simultaneous arthroscopic surgery was performed in 60 (61%) patients, with or without concomitant treatment of intra-articular injuries, as summarized in Table 1. An iliac crest autologous bone graft was used in 1 case, while bone substitute wedges (HATriC) were implanted in 60 cases. In the remaining 38 cases, the osteotomy gap was left untreated. Full weightbearing was allowed at a mean of 63.2 6 17.3 days after surgery. A delay (.60 days) in osteotomy healing was observed radiographically in 9 (9%) patients. However, in these patients, full weightbearing was allowed between 90 and 120 days after surgery, and no loss of correction was observed on follow-up radiographs. Intraoperative complications included 2 nondisplaced intra-articular fractures and 10 lateral hinge disruptions (Figure 5). The intra-articular fractures were recognized intraoperatively with the fluoroscope and fixed with a 6.5-mm cannulated cancellous screw and washer inserted from lateral to medial (Figure 5). Lateral hinge disruption was recognized intraoperatively in 4 cases and fixed with
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Figure 5. Complications. (A) Anteroposterior (AP) view showing an intra-articular fracture fixed with a cannulated screw inserted from lateral to medial; (B) AP view of a long-leg radiograph of the knee in A, showing no loss of correction; and (C) AP view showing lateral hinge disruption fixed with a cannulated screw inserted from lateral to medial and distal to proximal.
Figure 6. Total knee replacement after high tibial osteotomy. (A) Anteroposterior view and (B) lateral view. an additional 6.5-mm cannulated cancellous screw and washer inserted from lateral to medial and from distal to proximal (Figure 5). In the other 6 cases, lateral hinge disruption was detected with postoperative radiographs or at 1-month follow-up. No secondary displacement or loss of correction was recorded in the case of intra-articular fractures or lateral hinge disruptions (Figure 5). Major complications included 1 case of deep venous thrombosis and 1 case of deep infection, which required hardware removal after bone healing and intravenous antibiotics. Minor complications included painful proximal tibial hematoma (3 cases), delayed surgical wound healing (3 cases), and superficial infection (2 cases) treated with oral antibiotics. All minor complications completely resolved within 6 weeks from surgery. Hardware removal was performed in 22 patients. At the last follow-up visit, 3 patients previously underwent TKR, and 3 were indicated for TKR because of a recurrence of symptoms (Figure 6). The mean preoperative alignment was 7.6° 6 3.3°, while the mean alignment at the last follow-up visit was 1.1° 6
2.8° of valgus. Preoperatively, the mechanical axis passed, on average, through a point located at 19.6% 6 11.3% of the tibial plateau (as measured from medial to lateral) and postoperatively at 51.0% 6 12.8%. Regarding the 6 cases that ultimately failed, 2 returned toward varus (from 1° of varus postoperatively to 4° of varus at last follow-up and from 4° of valgus postoperatively to 1° of varus at last follow-up), 1 went into further valgus (from 4° of valgus postoperatively to 9° of valgus at last follow-up), and 3 maintained postoperative correction (0°, 3°, 4°, and 6° of valgus). No correlation was found between postoperative alignment and failure. The mean Knee Society and WOMAC scores preoperatively were 135.6 6 33.9 and 50.7 6 20.8, respectively, and the mean postoperative scores at the last follow-up visit were 160.5 6 26.3 and 76.1 6 18.5, respectively. Both Knee Society and WOMAC scores significantly improved after surgery (P \ .001). A quite strong positive linear correlation (Pearson r = 0.71) was found between the Knee Society score and the WOMAC score. This correlation between these 2 categorical variables (Knee Society
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score and WOMAC score) was also demonstrated using the Pearson x2 test (P \ .001), indicating that most patients with high Knee Society scores also had high WOMAC scores and vice versa. Sometimes, patients with a relatively high Knee Society score showed a medium WOMAC score, and more rarely, patients with a relatively low Knee Society score showed a high WOMAC score. The mean score on the VAS for pain experienced in the previous week was 7.4 6 2.5 preoperatively and 3.5 6 3.0 postoperatively. Regarding the question ‘‘Would you undergo the surgery again?’’ there were 78 positive answers, 19 negative, and 2 undecided. The Pearson x2 test showed a high correlation (P \ .001) between a positive answer and good or excellent Knee Society/WOMAC scores. On the other hand, no correlation (P = .218) was found between a negative answer and poor or fair Knee Society/WOMAC scores. This could be explained by considering that the dissatisfaction of the patients was not only because of unsuccessful surgeries but also other described complications (deep venous thrombosis, infection) or other conditions not related to the surgical procedure (higher expectations, allergic reactions, diabetic peripheral neuropathy, ulcers). At the last follow-up clinical examination, an increased opening compared with the contralateral side (.2 mm) was noted in 15% of the patients with valgus stress at 0° of knee flexion and in 52% of the patients at 30° of flexion. According to simple and multiple logistic regression analyses, residual medial laxity did not affect the outcome. The preoperative variables significantly related to a poor outcome after simple logistic regression were (1) BMI .30 kg/m2 (P = .038), (2) age .56 years (P = .008), and (3) preoperative knee flexion \120° (P = .033). The risk of unsuccessful surgery was 10 times higher when the BMI was .30 kg/m2 (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.13-88.49), 5 times higher with age .56 years (OR, 4.9; 95% CI, 1.50-15.70), and almost 4 times higher when preoperative knee flexion was \120° (OR, 3.8; 95% CI, 1.10-12.68). When inserted in a multiple logistic regression model, BMI .30 kg/m2 (P = .12) and preoperative knee flexion \120° (P = .16) were not significant. Some preoperative variables were significantly related to a good outcome both in single and multiple logistic regression models: (1) Ahlba¨ck grade 0 arthritis of the medial compartment (P \ .001) and (2) excellent preoperative (.80 points) Knee Society score (P \ .001). The other preoperative variables (patient sex, amount of varus malalignment, WOMAC score, previous surgeries, as well as amount of arthritic changes in the medial, lateral, and patellofemoral compartments) did not affect the outcomes, although the presence of patellofemoral arthritic changes was close to significance (P = .08). No intraoperative variables (associated arthroscopic procedures, size of the plate, type of graft) significantly affected the outcomes. Between the postoperative variables, only postoperative knee flexion of less than 120° (observed in 18 patients) was associated with poor outcomes (P \ .001) both in single and multiple logistic regression models. Of these 18 patients, 12 developed a limited range after surgery (4 in the early postoperative period because of poor physical therapy
Figure 7. The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years. The line ends abruptly because the high tibial osteotomy of the patient with a longer follow-up (114 months) did not survive and was revised to total knee replacement. There were no patients defined as ‘‘long-term survivors,’’ usually represented in the graph as a long and flat end of the line. The curve has a step-like shape because there were only 6 failures. Each step represents an end point of survivorship (revision/indication for total knee replacement). and 8 over the years). The other variables apparently did not affect the outcomes (alignment, residual medial instability). The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years (Figure 7).
DISCUSSION High tibial osteotomy is a widely accepted treatment option for medial compartment arthritis of the knee, particularly in the young and active patient. A vast literature is available regarding the outcomes of CWHTO. Closing wedge HTO generally produces good outcomes with precise indications and surgical technique.5 However, results deteriorate over time, with survivorship rates of 75% to 94% at 5 years, 51% to 95% at 10 years, and 39% to 90% at 15 years.5 In addition, indicators influencing the outcome have been described for CWHTO, with the goal of identifying ideal candidates for the procedure. The conditions that correlated with poor outcomes after CWHTO include severe articular degeneration (grade III according to the Ahlba¨ck classification),1,11,16 advanced age,11,12,22 patellofemoral arthrosis,25 markedly decreased ROM,22 previous arthroscopic debridements,22 joint instability,25 lateral tibial thrust,22 undercorrection1,20,22,33 or overcorrection,20 and loss of correction.29 On the other hand, a slight valgus overcorrection seems to be associated with the best results.16,22,29 However, the exact leg alignment that leads to the best survival rate has not been determined yet.27 The recommended postoperative alignment ranges from 1° to 8° of valgus, according to different authors.1,3,8,15,16,25
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TABLE 2 OWHTO Results Reported in the Literaturea Author (Year)
Study Design
Hernigou et al13 Case series (1987)
No. of Knees
Follow-up
Technique
93
11.5 y
OWHTO (no internal fixation, no cast)
45% good/excellent results
2y
OWHTO with hemicallotasis with external fixator
Comparable results between the 2 groups (HSS, Lysholm, and Wallgren-Tegner scores) Negative prognostic factors: pain for .2 years, preoperative KOOS\50 points, obesity, smoking, medial tibial exophytes, joint space \5 mm, and grade IV cartilage defects 67.5% good/excellent results, 86% reported clinical improvement (Lysholm and subjective IKDC score) Clinically important improvements in malalignment, medial compartment load during gait, and all KOOS domain scores 52% good/excellent 70% at 8 y results
Magyar et al19 (1999)
Randomized 25 OWHTOs vs controlled trial 25 CWHTOs
Spahn et al32 (2006)
Case series
84
46 mo
Niemeyer et al23 (2008)
Case series
43
2y
OWHTO with locking plate fixation
Birmingham et al7 (2009)
Observational cohort study
126
2y
OWHTO with nonlocking Puddu plate fixation
DeMeo et al9 (2010)
Case series
20
8.3 y
Schro¨ter et al27 (2011)
Case series
35
1y
LaPrade et al17 (2012)
Case series
47 (patient age \55 y)
3.6 y
OWHTO with nonlocking Puddu plate fixation OWHTO with POSITION HTO plate (Aesculap, Tuttlingen, Germany) OWHTO with nonlocking Puddu plate fixation
OWHTO with nonlocking Puddu plate fixation
Outcomes
Survivorship 90% at 5 y and 45% at 10 y with recurrence of pain as an end point, 82% at 10 y with revision as an end point
34% overall complication rate, 23% plate-related complication rate 44 good results (modified Cincinnati knee score)
94% at 3.6-y follow-up
a
CWHTO, closing wedge high tibial osteotomy; HSS, Hospital for Special Surgery; IKDC, International Knee Documentation Committee; KOOS, Knee injury and Osteoarthritis Outcome Score; OWHTO, opening wedge high tibial osteotomy.
Body mass index is a controversial factor. Some studies reported higher failure rates in lighter weight patients,3,22 while other studies8,20 found the opposite. In contrast to lateral CWHTO, the literature regarding medial OWHTO is sparse.9,13,19,26,32,34 The most relevant articles reporting the results of OWHTO have been summarized in Table 2. Short follow-ups or small case series are the main limitations of the studies regarding this topic.
The outcomes and survival analysis reported in the present study are comparable with those described in the literature (Table 2). Loss of correction with or without hardware failure has been described as a complication of OWHTO.27,31 Similarly to other studies regarding OWHTO with nonlocking Puddu plates9 or newer generation plates,18 we did not find this complication. This can also be caused by the cautious postoperative regimen adopted by the patients in the
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present study. The other complications recorded in this study are similar to those in previous reports.31 Similarly to the present study, Spahn et al32 analyzed the prognostic factors in a case series of 94 patients after OWHTO (Puddu plate or c-plate [Ko¨nigsee Implantate, Allendorf, Germany]) at a follow-up of 45.9 6 7.6 months. The authors found that factors associated with a poor outcome were (1) patient history of symptoms for .24 months, (2) a preoperative Knee injury and Osteoarthritis Outcome Score (KOOS) \50 points, (3) obesity, (4) smoking, (5) medial tibial exophytes, (6) medial joint space width \5 mm, and (7) intra-articular damage such as a grade IV cartilage defect of the tibia. Women tended to have a slightly higher rate of poor results. Patient age and prior surgeries did not influence the outcome.32 In the present article, the variables significantly related to a poor outcome were (1) age .56 years and (2) postoperative knee flexion \120°. The variables significantly related to a good outcome were (1) Ahlba¨ck grade 0 arthritis of the medial compartment and (2) excellent preoperative Knee Society score. Although obesity was found to be a negative prognostic factor only on the simple logistic regression model, the authors believe that overweight patients put excessive stress on the knee joint, which may accelerate degenerative changes. For these reasons, obesity should be regarded as a risk factor for early failure after HTO. As mentioned for CWHTO, the ideal correction to achieve with OWHTO is still controversial. In this case series, we did not find any correlation between the postoperative mechanical axis and midterm outcomes, also as in the case of undercorrection, because of technical errors. Similar findings were described by Akizuki et al3 and Insall et al15 regarding longterm results of CWHTO. According to our results at midterm follow-up, a quite wide range of the postoperative mechanical axis can be acceptable, from slight undercorrection to slight overcorrection. However, we do not know the long-term results, mostly in young patients. Therefore, we recommend a slight valgus (3°-6°) overcorrection in older patients to better unload the medial compartment. On the other hand, we cautiously recommend a neutral correction in young patients to avoid lateral compartment wear in the long run. In this article, reduced postoperative ROM was identified as a negative prognostic factor. As described in the results section, this was not only a consequence of reduced preoperative ROM or the progression of degenerative joint disease. In a few cases, reduced ROM was noticed in the early postoperative period. Therefore, the importance of early mobilization and adequate postoperative rehabilitation is emphasized to avoid premature failure of OWHTO. Residual medial instability is a common finding after OWHTO because of the partial release of the sMCL during exposure of the anteromedial tibia. Hernigou et al13 noticed that all pain-free knees were stable and that all unstable knees were painful. Although the surgical procedure performed by Hernigou et al13 was significantly different compared with the one described in this study, we did not find any correlation between residual medial instability and outcomes. Although none of the patients in our case series complained about instability, a valgus overcorrection associated with medial laxity can hypothetically result in further
valgus deviation over the years. The difficulties in obtaining standardized measurements for medial stability leave an open debate regarding the role of residual medial laxity as a prognostic factor for OWHTO. Patellofemoral degeneration has been identified as a possible negative prognostic factor for HTO.25 Opposite findings have been described by DeMeo et al9 and Hernigou et al.13 In the present study, no correlation was observed between patellofemoral changes and outcomes. However, severe symptomatic arthritis of the patellofemoral compartment was considered a contraindication for OWHTO, and only patients with initial asymptomatic patellofemoral degeneration were available in this case series. In addition, McDonnell et al21 described a poor correlation between intraoperative findings and the grade of patellofemoral arthritis on skyline views, which were used in the present study. In light of these considerations, the authors believe that the absence of correlation between patellofemoral arthritis and poor outcomes described in this study should be taken with caution. As for the limitations of this study, changes in patellar height and posterior tibial slope were not investigated. Although the biomechanical importance of the posterior tibial slope is well known, the measurements on lateral radiographs do not seem to be reliable14 and for this reason were not performed. Several studies as reviewed in the literature showed decreased patellar height after OWHTO.28 Although measurements of patellar height have been shown to be reliable on lateral radiographs independently of knee flexion,6,30 some indices (ie, Blackburne-Peel and Caton-Deschamps) may be affected by slope changes after HTO, and no clinical implications have been described for changes in patellar height.28 Another limitation of the present study is the relatively short follow-up. However, as previously stated, the goal of the study was to identify the factors correlated with early failure. Longer follow-up studies are certainly required regarding OWHTO. In conclusion, correct indications are essential in obtaining good outcomes and in avoiding early failure with OWHTO. Although more studies are required to better identify the ideal candidates for this procedure, the increasing experience of the surgeons over the years and a more accurate patient selection led to improved outcomes with OWHTO. Based on previous studies,5 severe articular destruction (grade III according to the Ahlba¨ck classification), patellofemoral arthrosis, and markedly decreased ROM are contraindications for OWHTO. According to the results of this study, the surgeon must know that advanced age, and possibly obesity and failure to regain adequate postoperative motion, may predispose to early failure after OWHTO. On the other hand, younger patients with good knee function and only mild degenerative joint disease appear to be ideal candidates for this procedure.
ACKNOWLEDGMENT The authors acknowledge Elena Farina, PhD, for the statistical analysis.
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REFERENCES 1. Aglietti P, Rinonapoli E, Stringa G, Taviani A. Tibial osteotomy for the varus osteoarthritic knee. Clin Orthop Relat Res. 1983;176:239-251. 2. Ahlba¨ck S. Osteoarthrosis of the knee: a radiographic investigation. Acta Radiol Diagn (Stockh). 1968;277:7-72. 3. Akizuki S, Shibakawa A, Takizawa T, Yamazaki I, Horiuchi H. The long-term outcome of high tibial osteotomy: a ten- to 20-year follow-up. J Bone Joint Surg Br. 2008;90(5):592-596. 4. Altman RD, Gold GE. Atlas of individual radiographic features in osteoarthritis, revised. Osteoarthritis Cartilage. 2007;15 Suppl A:A1A56. 5. Amendola A, Bonasia DE. Results of high tibial osteotomy: review of the literature. Int Orthop. 2010;34(2):155-160. 6. Berg EE, Mason SL, Lucas MJ. Patellar height ratios: a comparison of four measurement methods. Am J Sports Med. 1996;24(2):218221. 7. Birmingham TB, Giffin JR, Chesworth BM, et al. Medial opening wedge high tibial osteotomy: a prospective cohort study of gait, radiographic, and patient-reported outcomes. Arthritis Rheum. 2009;61(5):648-657. 8. Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy: a critical long-term study of eighty-seven cases. J Bone Joint Surg Am. 1993;75(2):196-201. 9. DeMeo PJ, Johnson EM, Chiang PP, Flamm AM, Miller MC. Midterm follow-up of opening-wedge high tibial osteotomy. Am J Sports Med. 2010;38(10):2077-2084. 10. Dugdale TW, Noyes FR, Styer D. Preoperative planning for high tibial osteotomy: the effect of lateral tibiofemoral separation and tibiofemoral length. Clin Orthop Relat Res. 1992;274:248-264. 11. Flecher X, Parratte S, Aubaniac JM, Argenson JN. A 12–28-year followup study of closing wedge high tibial osteotomy. Clin Orthop Relat Res. 2006;452:91-96. 12. Gsto¨ttner M, Pedross F, Liebensteiner M, Bach C. Longterm outcome after high tibial osteotomy. Arch Orthop Trauma Surg. 2008;128(1):111-115. 13. Hernigou P, Medevielle D, Debeyre J, Goutallier D. Proximal tibial osteotomy for osteoarthritis with varus deformity: a ten to thirteen year followup study. J Bone Joint Surg Am. 1987;69(3):332-354. 14. Hudek R, Schmutz S, Regenfelder F, Fuchs B, Koch PP. Novel measurement technique of the tibial slope on conventional MRI. Clin Orthop Relat Res. 2009;467(8):2066-2072. 15. Insall JN, Joseph DM, Msika C. High tibial osteotomy for varus gonarthrosis: a long-term follow-up study. J Bone Joint Surg Am. 1984;66:1040-1048. 16. Ivarsson I, Myrnerts R, Gillquist J. High tibial osteotomy for medial osteoarthritis of the knee: a 5 to 7 and 11 year followup. J Bone Joint Surg Br. 1990;72:238-244. 17. LaPrade RF, Spiridonov SI, Nystrom LM, Jansson KS. Prospective outcomes of young and middle-aged adults with medial compartment osteoarthritis treated with a proximal tibial opening wedge osteotomy. Arthroscopy. 2012;28(3):354-364.
18. Lobenhoffer P, Agneskirchner JD. Improvements in surgical technique of valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2003;11(3):132-138. 19. Magyar G, Ahl TL, Vibe P, Toksvig-Larsen S, Lindstrand A. Openwedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee: a randomised study of 50 operations. J Bone Joint Surg Br. 1999;81(3):444-448. 20. Matthews LS, Goldstein SA, Malvitz TA, Katz BP, Kaufer H. Proximal tibial osteotomy: factors that influence the duration of satisfactory function. Clin Orthop Relat Res. 1988;229:193-200. 21. McDonnell SM, Thomas G, Rout R, et al. Correlation between skyline radiographs and macroscopic intraoperative assessment of the patellofemoral joint. J Bone Joint Surg Br. 2009;91 Suppl III:426. 22. Naudie D, Bourne RB, Rorabeck CH, Bourne TJ. The Install Award. Survivorship of the high tibial valgus osteotomy: a 10- to 22-year followup study. Clin Orthop Relat Res. 1999;367:18-27. 23. Niemeyer P, Koestler W, Kaehny C, et al. Two-year results of openwedge high tibial osteotomy with fixation by medial plate fixator for medial compartment arthritis with varus malalignment of the knee. Arthroscopy. 2008;24(7):796-804. 24. Rossi R, Bonasia DE, Amendola A. The role of high tibial osteotomy in the varus knee. J Am Acad Orthop Surg. 2011;19(10):590-599. 25. Rudan JF, Simurda MA. High tibial osteotomy: a prospective clinical and roentgenographic review. Clin Orthop Relat Res. 1990;255:251-256. 26. Sangwan SS, Siwach RC, Singh Z, Duhan S. Unicompartmental osteoarthritis of the knee: an innovative osteotomy. Int Orthop. 2000;24(3):148-150. 27. Schro¨ter S, Gonser CE, Konstantinidis L, Helwig P, Albrecht D. High complication rate after biplanar open wedge high tibial osteotomy stabilized with a new spacer plate (position HTO plate) without bone substitute. Arthroscopy. 2011;27(5):644-652. 28. Schro¨ter S, Lobenhoffer P, Mueller J, Ihle C, Sto¨ckle U, Albrecht D. Changes of patella position after closed and open wedge high tibial osteotomy: review of the literature. Orthopade. 2012;41(3):186, 188-194. 29. Segal NA, Buckwalter JA, Amendola A. Other surgical techniques for osteoarthritis. Best Pract Res Clin Rheumatol. 2006;20(1): 155-176. 30. Seil R, Mu¨ller B, Georg T, Kohn D, Rupp S. Reliability and interobserver variability in radiological patellar height ratios. Knee Surg Sports Traumatol Arthrosc. 2000;8(4):231-236. 31. Spahn G. Complications in high tibial (medial opening wedge) osteotomy. Arch Orthop Trauma Surg. 2004;124(10):649-653. 32. Spahn G, Kirschbaum S, Kahl E. Factors that influence high tibial osteotomy results in patients with medial gonarthritis: a score to predict the results. Osteoarthritis Cartilage. 2006;14(2):190-195. 33. Sprenger TR, Doerzbacher JF. Tibial osteotomy for the treatment of varus gonarthrosis: survival and failure analysis to twenty-two years. J Bone Joint Surg Am. 2003;85:469-474. 34. Weale AE, Lee AS, MacEachern AG. High tibial osteotomy using a dynamic axial external fixator. Clin Orthop Relat Res. 2001;382: 154-167.
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Medial Opening Wedge High Tibial Osteotomy for Medial Compartment Overload/Arthritis in the Varus Knee: Prognostic Factors Davide Edoardo Bonasia, Federico Dettoni, Gabriele Sito, Davide Blonna, Antongiulio Marmotti, Matteo Bruzzone, Filippo Castoldi and Roberto Rossi Am J Sports Med published online January 21, 2014 DOI: 10.1177/0363546513516577 The online version of this article can be found at: http://ajs.sagepub.com/content/early/2014/01/17/0363546513516577 A more recent version of this article was published on - Feb 28, 2014
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Medial Opening Wedge High Tibial Osteotomy for Medial Compartment Overload/Arthritis in the Varus Knee Prognostic Factors Davide Edoardo Bonasia,*y MD, Federico Dettoni,z MD, Gabriele Sito,z MD, Davide Blonna,z MD, Antongiulio Marmotti,z MD, Matteo Bruzzone,z MD, Filippo Castoldi,z MD, and Roberto Rossi,z MD Investigation performed at the University of Torino, Torino, Italy Background: Medial opening wedge high tibial osteotomy (OWHTO) is a widely accepted procedure for the treatment of medial compartment arthritis of the knee. Compared with closing wedge HTO, however, the outcomes of OWHTO reported in the literature are incomplete. Purpose: To identify the positive and negative prognostic factors related to the outcomes of OWHTO through an evaluation of midterm study results and survivorship analysis. Study Design: Case series; Level of evidence, 4. Methods: From January 2001 to December 2009, a total of 141 consecutive OWHTOs were performed in 123 patients. Only patients with symptomatic medial knee overload/arthritis were included. The patients were evaluated preoperatively and at every follow-up visit with (1) the Knee Society score, (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) another self-evaluation scale, (4) long-leg radiographs, and (5) plain radiographs. Preoperative, intraoperative, and postoperative variables were investigated to find an association with the outcomes. Results: Of the 123 patients, 15 were lost to follow-up, and 24 were excluded from the study, leaving 84 patients (99 OWHTOs) for the present study. The mean age of the patients at the time of surgery was 54.5 6 9.2 years. The mean follow-up was 51.5 6 23.8 months. The Knee Society and WOMAC scores significantly improved after surgery (P \ .001). The variables significantly related to a poor outcome were (1) age .56 years (P = .008) and (2) postoperative knee flexion \120° (P \ .001); the variables significantly related to a good outcome were (1) Ahlba¨ck grade 0 arthritis of the medial compartment (P \ .001) and (2) excellent preoperative Knee Society score (P \ .001). The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years. Conclusion: With correct indications, OWHTO is a reliable procedure for medial knee arthritis/overload. The outcomes reported are similar to those from other studies, although the variables related to outcomes are slightly different. Keywords: knee; arthritis; HTO; high tibial osteotomy; opening wedge; OWHTO
Unicompartmental medial knee arthritis is a very common condition and can represent a challenge for the orthopaedic
surgeon, mostly in young and active patients. In these patients, high tibial osteotomy (HTO) is a widely accepted procedure that can rely on good outcomes with correct indications. Clinical indications for HTO include varus alignment of the knee associated with medial compartment arthrosis, knee instability, medial compartment overload (ie, after medial meniscectomy), and osteochondral lesions requiring resurfacing procedures.24 Many techniques have been described for HTO, whether alone or in combination with other procedures. These include closing wedge HTO (CWHTO), opening wedge HTO (OWHTO), dome, and ‘‘en chevron’’ osteotomies, with CWHTO and OWHTO being the most commonly used.5 Opening wedge HTO has recently risen in popularity because of its easy technique (without the need for proximal tibiofibular joint
*Address correspondence to Davide Edoardo Bonasia, MD, Azienda Ospedaliera Citta` della Salute e della Scienza, Centro Traumatologico Ortopedico Hospital, University of Torino, Via Lamarmora 26, 10128, Torino, Italy (e-mail: [email protected]). y Azienda Ospedaliera Citta` della Salute e della Scienza, Centro Traumatologico Ortopedico Hospital, University of Torino, Torino, Italy. z Mauriziano Umberto I Hospital, University of Torino, Torino, Italy. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546513516577 Ó 2014 The Author(s)
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Figure 1. Preoperative anteroposterior radiographs showing initial medial compartment arthritis. (A) Weightbearing full extension and (B) Rosenberg view. disruption, fibular osteotomy, or common peroneal nerve dissection), the possibility of multiplanar correction (both sagittal and coronal planes can be modified), and the theoretical, easier subsequent total knee replacement (TKR) compared with CWHTO. It is accepted that the results of HTO deteriorate over time.5 However, early failure rates ranging from 10% to 50% have been described,32 and understanding the indicators for poor outcomes is essential in identifying the ideal candidates for HTO. A vast literature is available regarding the long-term outcomes and positive/negative prognostic factors of CWHTO. On the other hand, the literature regarding OWHTO is incomplete, most of all regarding prognostic factors. The goal of this study was to identify the positive and negative prognostic factors related to the outcomes of OWHTO. Evaluation of the midterm results and survivorship analysis have been performed. The correlation of preoperative, intraoperative, and postoperative variables with the outcomes has been evaluated.
MATERIALS AND METHODS A total of 141 consecutive OWHTOs were performed at our institution from January 2001 to December 2009. The indications of OWHTO for medial compartment overload/arthritis included patients younger than 65 years, medial arthritic changes less than grade III (Ahlba¨ck classification), and varus alignment (Figure 1). Absolute contraindications included symptomatic degenerative changes of the patellofemoral and lateral compartments, neutral or valgus alignment, active infection, and severe reduction of knee range of motion (ROM) (flexion contracture .5°, flexion \100°). Only patients undergoing OWHTO for symptomatic medial knee overload or arthritis were included in the study. We excluded OWHTOs performed for other conditions (ie, instability, instability 1 overload/arthritis,
Figure 2. Preoperative planning on anteroposterior long-leg radiographs. Slight valgus overcorrection (3°-5° of valgus, 62.5% of the lateral tibial plateau) was generally planned.
asymptomatic severe varus in young patients, focal osteochondral lesions in malaligned knees, overload in meniscectomized knees requiring meniscus transplant, malalignment after intra- and extra-articular fractures). Generally, 3° to 5° of valgus overcorrection was planned preoperatively, as described by Dugdale et al10 (Figure 2). In the case of young patients with minimal degeneration of the medial compartment, correction to a neutral mechanical axis was planned.
Surgical Technique All surgeries were performed according to the technique previously described by Rossi et al.24 The patient was positioned supine on a radiolucent operating table, with a tourniquet around the proximal thigh. When necessary, arthroscopic surgery was performed first to treat associated injuries. Then, a 5-cm longitudinal incision was
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Figure 3. Surgical technique. (A) Guide wire insertion and bone cut distal to it, (B) osteotomes used to open the osteotomy, (C) opening of the osteotomy with graduated wedges, and (D) plating of the osteotomy. made, extending from 1 cm below the medial joint line midway between the medial border of the tibial tubercle and the posteromedial border of the tibia. The sartorius fascia was incised and the pes anserinus retracted distally with a blunt retractor, exposing the superficial medial collateral ligament (sMCL). The sMCL was partially detached with a Cobb elevator. A blunt retractor was passed deep to the MCL to protect the posterior neurovascular structures. Next, the medial border of the patellar tendon was identified, retracted, and protected throughout the whole procedure. A guide wire was inserted, beginning at the anteromedial tibia at the level of the superior border of the tibial tubercle (approximately 4 cm distal from the joint line) and aiming the tip of the fibular head (approximately 1 cm below the lateral articular surface). Positioning of the guide wire was assessed under fluoroscopy. The tibial osteotomy was performed immediately distal to the guide wire to avoid proximal migration of the osteotomy into the joint (Figure 3A). In the sagittal plane, the osteotomy was performed parallel to the posterior tibial slope. A small oscillating saw was used to cut the tibial cortex from the tibial tubercle around to the posteromedial corner under direct visualization. Using intermittent fluoroscopy, graduated, thin flexible osteotomes were used to advance the osteotomy to within 1 cm of the lateral tibial cortex (Figure 3B). The mobility of the osteotomy was checked by gentle manipulation of the leg with valgus force. Calibrated wedges were then inserted into the osteotomy and advanced slowly until the desired opening was achieved (Figure 3C). A long alignment rod was used to assess the
accuracy of the calculated preoperative wedge size. Maintenance of the anatomic tibial slope was assessed fluoroscopically and by direct visualization. Once the desired correction had been achieved, plating was performed, and the wedges were removed (Figure 3D). Fixation was performed in all cases with a first-generation Puddu plate (Arthrex Inc, Naples, Florida, USA) with a rectangular spacer. For openings greater than 10 mm, the osteotomy gap was filled with bone substitutes (HATriC, Arthrex Inc) or autologous iliac crest bone grafting. For a smaller correction, the gap was left untreated. Postoperatively, the knee was placed in a hinged brace set at 0° to 90°, and the patient was restricted to touch weightbearing (20 kg) for 1 month. At 1 month after surgery, if knee radiographs showed maintenance of the correction, weightbearing progressed to 50% of the body weight, and the brace was unlocked. At 2 months, after radiographic control, the patient progressed to full weightbearing and the brace was discontinued. In the case of combined HTO and microfracture, the patient was prescribed nonweightbearing for 1 month and then progressed as per isolated HTO. Patients were evaluated preoperatively and at every follow-up visit with (1) the Knee Society score, (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) other self-evaluation tests including the visual analog scale (VAS) for pain experienced in the previous week and patient responses to whether they would undergo the surgery again, (4) longleg radiographs, and (5) plain radiographs with anteroposterior, lateral, and skyline views (Figure 4). The patients’
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Figure 4. Postoperative radiographs. (A) Anteroposterior (AP) view, (B) lateral view, and (C) AP view of long-leg radiograph. evaluations and data collection were performed by 2 independent investigators trained in knee surgery (D.E.B. and F.D.). Numerous variables were investigated to find an association with the outcomes, including preoperative (age, sex, body mass index [BMI], amount of varus malalignment, ROM, Knee Society score, WOMAC score, previous knee surgeries, amount of arthritic changes in the medial, lateral, and patellofemoral compartments), intraoperative (associated arthroscopic procedures, size of the plate), and postoperative (ROM, alignment, residual medial instability consequent to the sMCL detachment) variables. Medial arthritis of the knee was graded according to the Ahlba¨ck classification,2 while patellofemoral degenerative changes were graded with a modified Altman classification (grades 0-3).4 The size of the plate depended basically on 2 factors: the required correction angle and the size of the patient’s tibia. The postoperative medial opening was clinically evaluated (at both 0° and 30° of flexion) by 2 independent investigators trained in knee surgery. When both investigators identified a medial opening greater than 2 mm in the affected side, compared with the unaffected side, the datum was considered significant. A paired t test was used to compare Knee Society and WOMAC scores before and after surgery. The Pearson x2 test was used for categorical variables, while simple logistic regression was performed for nominal variables. All variables that were statistically significant (P \ .05) or close to significance with simple logistic regression were then inserted in a multiple regression model. In addition, Kaplan-Meier survival analysis was performed. For the survival analysis, revision to TKR or indication for TKR because of the recurrence of symptoms was considered as end points.
RESULTS Of 123 patients, 15 were lost to follow-up, and 24 were excluded from the study because they did not match the
TABLE 1 Intra-articular Procedures Associated With Opening Wedge High Tibial Osteotomy Concomitant Intra-articular Procedure
n
Diagnostic arthroscopic surgery Partial medial meniscectomy Partial lateral meniscectomy Microfracture Partial medial meniscectomy 1 microfracture Partial medial meniscectomy 1 abrasion arthroplasty Abrasion arthroplasty Total
18 18 2 13 6 1 2 60
inclusion criteria. Therefore, 84 patients (99 knees) were included in the present study. The mean age of the patients at the time of surgery was 54.5 6 9.2 years, and the mean BMI was 27.6 6 3.7 kg/m2. The mean follow-up was 51.5 6 23.8 months. Simultaneous arthroscopic surgery was performed in 60 (61%) patients, with or without concomitant treatment of intra-articular injuries, as summarized in Table 1. An iliac crest autologous bone graft was used in 1 case, while bone substitute wedges (HATriC) were implanted in 60 cases. In the remaining 38 cases, the osteotomy gap was left untreated. Full weightbearing was allowed at a mean of 63.2 6 17.3 days after surgery. A delay (.60 days) in osteotomy healing was observed radiographically in 9 (9%) patients. However, in these patients, full weightbearing was allowed between 90 and 120 days after surgery, and no loss of correction was observed on follow-up radiographs. Intraoperative complications included 2 nondisplaced intra-articular fractures and 10 lateral hinge disruptions (Figure 5). The intra-articular fractures were recognized intraoperatively with the fluoroscope and fixed with a 6.5-mm cannulated cancellous screw and washer inserted from lateral to medial (Figure 5). Lateral hinge disruption was recognized intraoperatively in 4 cases and fixed with
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Figure 5. Complications. (A) Anteroposterior (AP) view showing an intra-articular fracture fixed with a cannulated screw inserted from lateral to medial; (B) AP view of a long-leg radiograph of the knee in A, showing no loss of correction; and (C) AP view showing lateral hinge disruption fixed with a cannulated screw inserted from lateral to medial and distal to proximal.
Figure 6. Total knee replacement after high tibial osteotomy. (A) Anteroposterior view and (B) lateral view. an additional 6.5-mm cannulated cancellous screw and washer inserted from lateral to medial and from distal to proximal (Figure 5). In the other 6 cases, lateral hinge disruption was detected with postoperative radiographs or at 1-month follow-up. No secondary displacement or loss of correction was recorded in the case of intra-articular fractures or lateral hinge disruptions (Figure 5). Major complications included 1 case of deep venous thrombosis and 1 case of deep infection, which required hardware removal after bone healing and intravenous antibiotics. Minor complications included painful proximal tibial hematoma (3 cases), delayed surgical wound healing (3 cases), and superficial infection (2 cases) treated with oral antibiotics. All minor complications completely resolved within 6 weeks from surgery. Hardware removal was performed in 22 patients. At the last follow-up visit, 3 patients previously underwent TKR, and 3 were indicated for TKR because of a recurrence of symptoms (Figure 6). The mean preoperative alignment was 7.6° 6 3.3°, while the mean alignment at the last follow-up visit was 1.1° 6
2.8° of valgus. Preoperatively, the mechanical axis passed, on average, through a point located at 19.6% 6 11.3% of the tibial plateau (as measured from medial to lateral) and postoperatively at 51.0% 6 12.8%. Regarding the 6 cases that ultimately failed, 2 returned toward varus (from 1° of varus postoperatively to 4° of varus at last follow-up and from 4° of valgus postoperatively to 1° of varus at last follow-up), 1 went into further valgus (from 4° of valgus postoperatively to 9° of valgus at last follow-up), and 3 maintained postoperative correction (0°, 3°, 4°, and 6° of valgus). No correlation was found between postoperative alignment and failure. The mean Knee Society and WOMAC scores preoperatively were 135.6 6 33.9 and 50.7 6 20.8, respectively, and the mean postoperative scores at the last follow-up visit were 160.5 6 26.3 and 76.1 6 18.5, respectively. Both Knee Society and WOMAC scores significantly improved after surgery (P \ .001). A quite strong positive linear correlation (Pearson r = 0.71) was found between the Knee Society score and the WOMAC score. This correlation between these 2 categorical variables (Knee Society
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score and WOMAC score) was also demonstrated using the Pearson x2 test (P \ .001), indicating that most patients with high Knee Society scores also had high WOMAC scores and vice versa. Sometimes, patients with a relatively high Knee Society score showed a medium WOMAC score, and more rarely, patients with a relatively low Knee Society score showed a high WOMAC score. The mean score on the VAS for pain experienced in the previous week was 7.4 6 2.5 preoperatively and 3.5 6 3.0 postoperatively. Regarding the question ‘‘Would you undergo the surgery again?’’ there were 78 positive answers, 19 negative, and 2 undecided. The Pearson x2 test showed a high correlation (P \ .001) between a positive answer and good or excellent Knee Society/WOMAC scores. On the other hand, no correlation (P = .218) was found between a negative answer and poor or fair Knee Society/WOMAC scores. This could be explained by considering that the dissatisfaction of the patients was not only because of unsuccessful surgeries but also other described complications (deep venous thrombosis, infection) or other conditions not related to the surgical procedure (higher expectations, allergic reactions, diabetic peripheral neuropathy, ulcers). At the last follow-up clinical examination, an increased opening compared with the contralateral side (.2 mm) was noted in 15% of the patients with valgus stress at 0° of knee flexion and in 52% of the patients at 30° of flexion. According to simple and multiple logistic regression analyses, residual medial laxity did not affect the outcome. The preoperative variables significantly related to a poor outcome after simple logistic regression were (1) BMI .30 kg/m2 (P = .038), (2) age .56 years (P = .008), and (3) preoperative knee flexion \120° (P = .033). The risk of unsuccessful surgery was 10 times higher when the BMI was .30 kg/m2 (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.13-88.49), 5 times higher with age .56 years (OR, 4.9; 95% CI, 1.50-15.70), and almost 4 times higher when preoperative knee flexion was \120° (OR, 3.8; 95% CI, 1.10-12.68). When inserted in a multiple logistic regression model, BMI .30 kg/m2 (P = .12) and preoperative knee flexion \120° (P = .16) were not significant. Some preoperative variables were significantly related to a good outcome both in single and multiple logistic regression models: (1) Ahlba¨ck grade 0 arthritis of the medial compartment (P \ .001) and (2) excellent preoperative (.80 points) Knee Society score (P \ .001). The other preoperative variables (patient sex, amount of varus malalignment, WOMAC score, previous surgeries, as well as amount of arthritic changes in the medial, lateral, and patellofemoral compartments) did not affect the outcomes, although the presence of patellofemoral arthritic changes was close to significance (P = .08). No intraoperative variables (associated arthroscopic procedures, size of the plate, type of graft) significantly affected the outcomes. Between the postoperative variables, only postoperative knee flexion of less than 120° (observed in 18 patients) was associated with poor outcomes (P \ .001) both in single and multiple logistic regression models. Of these 18 patients, 12 developed a limited range after surgery (4 in the early postoperative period because of poor physical therapy
Figure 7. The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years. The line ends abruptly because the high tibial osteotomy of the patient with a longer follow-up (114 months) did not survive and was revised to total knee replacement. There were no patients defined as ‘‘long-term survivors,’’ usually represented in the graph as a long and flat end of the line. The curve has a step-like shape because there were only 6 failures. Each step represents an end point of survivorship (revision/indication for total knee replacement). and 8 over the years). The other variables apparently did not affect the outcomes (alignment, residual medial instability). The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years (Figure 7).
DISCUSSION High tibial osteotomy is a widely accepted treatment option for medial compartment arthritis of the knee, particularly in the young and active patient. A vast literature is available regarding the outcomes of CWHTO. Closing wedge HTO generally produces good outcomes with precise indications and surgical technique.5 However, results deteriorate over time, with survivorship rates of 75% to 94% at 5 years, 51% to 95% at 10 years, and 39% to 90% at 15 years.5 In addition, indicators influencing the outcome have been described for CWHTO, with the goal of identifying ideal candidates for the procedure. The conditions that correlated with poor outcomes after CWHTO include severe articular degeneration (grade III according to the Ahlba¨ck classification),1,11,16 advanced age,11,12,22 patellofemoral arthrosis,25 markedly decreased ROM,22 previous arthroscopic debridements,22 joint instability,25 lateral tibial thrust,22 undercorrection1,20,22,33 or overcorrection,20 and loss of correction.29 On the other hand, a slight valgus overcorrection seems to be associated with the best results.16,22,29 However, the exact leg alignment that leads to the best survival rate has not been determined yet.27 The recommended postoperative alignment ranges from 1° to 8° of valgus, according to different authors.1,3,8,15,16,25
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TABLE 2 OWHTO Results Reported in the Literaturea Author (Year)
Study Design
Hernigou et al13 Case series (1987)
No. of Knees
Follow-up
Technique
93
11.5 y
OWHTO (no internal fixation, no cast)
45% good/excellent results
2y
OWHTO with hemicallotasis with external fixator
Comparable results between the 2 groups (HSS, Lysholm, and Wallgren-Tegner scores) Negative prognostic factors: pain for .2 years, preoperative KOOS\50 points, obesity, smoking, medial tibial exophytes, joint space \5 mm, and grade IV cartilage defects 67.5% good/excellent results, 86% reported clinical improvement (Lysholm and subjective IKDC score) Clinically important improvements in malalignment, medial compartment load during gait, and all KOOS domain scores 52% good/excellent 70% at 8 y results
Magyar et al19 (1999)
Randomized 25 OWHTOs vs controlled trial 25 CWHTOs
Spahn et al32 (2006)
Case series
84
46 mo
Niemeyer et al23 (2008)
Case series
43
2y
OWHTO with locking plate fixation
Birmingham et al7 (2009)
Observational cohort study
126
2y
OWHTO with nonlocking Puddu plate fixation
DeMeo et al9 (2010)
Case series
20
8.3 y
Schro¨ter et al27 (2011)
Case series
35
1y
LaPrade et al17 (2012)
Case series
47 (patient age \55 y)
3.6 y
OWHTO with nonlocking Puddu plate fixation OWHTO with POSITION HTO plate (Aesculap, Tuttlingen, Germany) OWHTO with nonlocking Puddu plate fixation
OWHTO with nonlocking Puddu plate fixation
Outcomes
Survivorship 90% at 5 y and 45% at 10 y with recurrence of pain as an end point, 82% at 10 y with revision as an end point
34% overall complication rate, 23% plate-related complication rate 44 good results (modified Cincinnati knee score)
94% at 3.6-y follow-up
a
CWHTO, closing wedge high tibial osteotomy; HSS, Hospital for Special Surgery; IKDC, International Knee Documentation Committee; KOOS, Knee injury and Osteoarthritis Outcome Score; OWHTO, opening wedge high tibial osteotomy.
Body mass index is a controversial factor. Some studies reported higher failure rates in lighter weight patients,3,22 while other studies8,20 found the opposite. In contrast to lateral CWHTO, the literature regarding medial OWHTO is sparse.9,13,19,26,32,34 The most relevant articles reporting the results of OWHTO have been summarized in Table 2. Short follow-ups or small case series are the main limitations of the studies regarding this topic.
The outcomes and survival analysis reported in the present study are comparable with those described in the literature (Table 2). Loss of correction with or without hardware failure has been described as a complication of OWHTO.27,31 Similarly to other studies regarding OWHTO with nonlocking Puddu plates9 or newer generation plates,18 we did not find this complication. This can also be caused by the cautious postoperative regimen adopted by the patients in the
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8
Bonasia et al
The American Journal of Sports Medicine
present study. The other complications recorded in this study are similar to those in previous reports.31 Similarly to the present study, Spahn et al32 analyzed the prognostic factors in a case series of 94 patients after OWHTO (Puddu plate or c-plate [Ko¨nigsee Implantate, Allendorf, Germany]) at a follow-up of 45.9 6 7.6 months. The authors found that factors associated with a poor outcome were (1) patient history of symptoms for .24 months, (2) a preoperative Knee injury and Osteoarthritis Outcome Score (KOOS) \50 points, (3) obesity, (4) smoking, (5) medial tibial exophytes, (6) medial joint space width \5 mm, and (7) intra-articular damage such as a grade IV cartilage defect of the tibia. Women tended to have a slightly higher rate of poor results. Patient age and prior surgeries did not influence the outcome.32 In the present article, the variables significantly related to a poor outcome were (1) age .56 years and (2) postoperative knee flexion \120°. The variables significantly related to a good outcome were (1) Ahlba¨ck grade 0 arthritis of the medial compartment and (2) excellent preoperative Knee Society score. Although obesity was found to be a negative prognostic factor only on the simple logistic regression model, the authors believe that overweight patients put excessive stress on the knee joint, which may accelerate degenerative changes. For these reasons, obesity should be regarded as a risk factor for early failure after HTO. As mentioned for CWHTO, the ideal correction to achieve with OWHTO is still controversial. In this case series, we did not find any correlation between the postoperative mechanical axis and midterm outcomes, also as in the case of undercorrection, because of technical errors. Similar findings were described by Akizuki et al3 and Insall et al15 regarding longterm results of CWHTO. According to our results at midterm follow-up, a quite wide range of the postoperative mechanical axis can be acceptable, from slight undercorrection to slight overcorrection. However, we do not know the long-term results, mostly in young patients. Therefore, we recommend a slight valgus (3°-6°) overcorrection in older patients to better unload the medial compartment. On the other hand, we cautiously recommend a neutral correction in young patients to avoid lateral compartment wear in the long run. In this article, reduced postoperative ROM was identified as a negative prognostic factor. As described in the results section, this was not only a consequence of reduced preoperative ROM or the progression of degenerative joint disease. In a few cases, reduced ROM was noticed in the early postoperative period. Therefore, the importance of early mobilization and adequate postoperative rehabilitation is emphasized to avoid premature failure of OWHTO. Residual medial instability is a common finding after OWHTO because of the partial release of the sMCL during exposure of the anteromedial tibia. Hernigou et al13 noticed that all pain-free knees were stable and that all unstable knees were painful. Although the surgical procedure performed by Hernigou et al13 was significantly different compared with the one described in this study, we did not find any correlation between residual medial instability and outcomes. Although none of the patients in our case series complained about instability, a valgus overcorrection associated with medial laxity can hypothetically result in further
valgus deviation over the years. The difficulties in obtaining standardized measurements for medial stability leave an open debate regarding the role of residual medial laxity as a prognostic factor for OWHTO. Patellofemoral degeneration has been identified as a possible negative prognostic factor for HTO.25 Opposite findings have been described by DeMeo et al9 and Hernigou et al.13 In the present study, no correlation was observed between patellofemoral changes and outcomes. However, severe symptomatic arthritis of the patellofemoral compartment was considered a contraindication for OWHTO, and only patients with initial asymptomatic patellofemoral degeneration were available in this case series. In addition, McDonnell et al21 described a poor correlation between intraoperative findings and the grade of patellofemoral arthritis on skyline views, which were used in the present study. In light of these considerations, the authors believe that the absence of correlation between patellofemoral arthritis and poor outcomes described in this study should be taken with caution. As for the limitations of this study, changes in patellar height and posterior tibial slope were not investigated. Although the biomechanical importance of the posterior tibial slope is well known, the measurements on lateral radiographs do not seem to be reliable14 and for this reason were not performed. Several studies as reviewed in the literature showed decreased patellar height after OWHTO.28 Although measurements of patellar height have been shown to be reliable on lateral radiographs independently of knee flexion,6,30 some indices (ie, Blackburne-Peel and Caton-Deschamps) may be affected by slope changes after HTO, and no clinical implications have been described for changes in patellar height.28 Another limitation of the present study is the relatively short follow-up. However, as previously stated, the goal of the study was to identify the factors correlated with early failure. Longer follow-up studies are certainly required regarding OWHTO. In conclusion, correct indications are essential in obtaining good outcomes and in avoiding early failure with OWHTO. Although more studies are required to better identify the ideal candidates for this procedure, the increasing experience of the surgeons over the years and a more accurate patient selection led to improved outcomes with OWHTO. Based on previous studies,5 severe articular destruction (grade III according to the Ahlba¨ck classification), patellofemoral arthrosis, and markedly decreased ROM are contraindications for OWHTO. According to the results of this study, the surgeon must know that advanced age, and possibly obesity and failure to regain adequate postoperative motion, may predispose to early failure after OWHTO. On the other hand, younger patients with good knee function and only mild degenerative joint disease appear to be ideal candidates for this procedure.
ACKNOWLEDGMENT The authors acknowledge Elena Farina, PhD, for the statistical analysis.
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