Original Article
145
Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee in Adolescent Patients J. Richard Steadman, MD1 Karen K. Briggs, MPH1 Chad M. Hanson, MD2 S. Clifton Willimon, MD3 1 Center for Outcomes-Based Orthopaedic Research, Steadman
Philippon Research Institute, Vail, Colorado 2 Desert Orthopaedic Center, Henderson, Nevada 3 Children’s Orthopaedics of Atlanta, Atlanta, Georgia
Lauren M. Matheny, BA1
Alyson Guillet, MD1
Address for correspondence J. Richard Steadman, MD, Center for Outcomes-Based Orthopaedic Research, Steadman Philippon Research Institute, 181 W. Meadow Drive, Suite 1000, Vail, CO 81657 (e-mail: [email protected]).
Abstract
Keywords
► ► ► ►
microfracture articular cartilage knee adolescent
The purpose of this study was to document outcomes following microfracture for fullthickness cartilage defects of the knee in adolescents. Our hypothesis was that patients aged 18 years or less would have excellent outcomes and function following microfracture of full-thickness knee articular cartilage defects. This study was approved by the Institutional Review Board. Patients < 19 years old with full-thickness knee articular cartilage defects treated with microfracture between January 1992 and June 2008 were identified. Surgical, demographic data, Lysholm score, Tegner activity scale, and patient satisfaction were collected prospectively. A total of 26 patients (14 females, 12 males) met inclusion criteria. Average age was 16.6 years (range: 12–18.9 years). Ninety-six percent of lesions were patellar (37%) or femoral condyle defects (medial 26%, lateral 33%). Minimum 2-year follow-up was obtained in 22/26 patients (85%) with average follow-up of 5.8 years (range: 2.0–13.3 years). Average postoperative Lysholm score was 90 (range: 50–100). Median Tegner scale was 6 (range: 2–10). Median patient satisfaction with outcome was 10 (range: 1–10). Lysholm correlated with Tegner scale (rho ¼ 0.586; p ¼ 0.011) and patient satisfaction (rho ¼ 0.70; p ¼ 0.001). Average postoperative Lysholm score in males was 93 and 86 in females (p ¼ 0.22). One patient underwent revision microfracture. This study showed that adolescent patients who underwent microfracture for treatment of full-thickness knee chondral defects demonstrated increased activity levels and excellent function following surgery.
Sports participation in adolescents has grown greatly over recent years. Due to this increased level of play, knee injuries in this population are on the rise.1 Although athletic participation has numerous advantages, sport-related injury is a potential negative consequence, and one that is also increasing.2 Among these injuries are lesions of the articular cartilage. Injuries to articular cartilage of the knee present a
challenge to the orthopedic surgeon treating this younger population.3 Since articular cartilage lacks the capacity to heal spontaneously,4 many patients experience pain, deficits in function and will develop knee osteoarthritis over time if left untreated.5 Surgical intervention is recommended to reduce the symptoms associated with articular cartilage.6 However, the orthopedic surgeon treating pediatric patients
received September 6, 2013 accepted after revision February 11, 2014 published online April 24, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1373737. ISSN 1538-8506.
Downloaded by: The University of Hong Kong. Copyrighted material.
J Knee Surg 2015;28:145–150.
Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee face the dilemma of balancing intervention for the damaged cartilage and maintaining the knee’s integrity to avoid future degeneration.6 Several surgical interventions to address chondral defects of the knee exist including arthroscopic debridement, mosaicplasty, autologous chondrocyte implantation (ACI), osteochondral allograft, and microfracture. Arthroscopic debridement alone has shown suboptimal results when compared with other treatments for full-thickness chondral defects of the knee.7 Mosaicplasty is another cartilage repair treatment8; however, disadvantages of use include donor site morbidity, failure of chondral integration,9 limited availability of graft from the patellofemoral joint, multiple surgeries, and mechanical differences in donor and recipient cartilage.5,10 Subchondral bone integrity may become compromised with this procedure as well.11 ACI is another treatment option,12–14 but limitations include high cost, patients undergoing two surgeries and increased rate of graft hypertrophies with periosteum.15 Multiple studies have documented improvements in pain, function, and activity level following microfracture of the knee in the adult population.16–23 Advantages of microfracture include a single surgery, low surgical morbidity, relatively low cost, technical simplicity, and decreased operative time.4,16 Although outcomes following these various treatments for cartilage defects of the knee have been extensively documented, controversy regarding the optimal treatment still exists and there is little literature documenting outcomes following treatment of cartilage defects in adolescent patients.24,25 The purpose of this study was to document outcomes of microfracture for full-thickness cartilage defects of the knee in the adolescent population. Our hypothesis was that patients aged 18 years and younger will have good outcomes and function following microfracture of full-thickness knee articular cartilage defects.
Methods Patient Selection This study was approved by the Institutional Review Board. All patients younger than 19 years of age, with full-thickness articular cartilage defects of the knee treated with microfracture, between January 1992 and June 2008 were identified. Patients were excluded from this study if they were older than 18 years or had axial malalignment as evidenced by clinical presentation and weight-bearing long leg films. All patients were a minimum of 2 years status post-microfracture. Surgical and demographic data were collected prospectively and reviewed retrospectively.
Outcomes Evaluation Patients were administered subjective questionnaires preoperatively and at a minimum of 2 years following microfracture surgery. Patients completed these questionnaires for evaluation of pain, symptoms of giving way, function, return to sports, activities of daily living, and their satisfaction with the outcome. Lysholm scores and Tegner activity scale were also documented.26–28 Patient satisfaction was graded on a The Journal of Knee Surgery
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10-point ordinal scale with 10 being very satisfied and 1 being very dissatisfied.
Statistical Analysis The paired t-test was used to determine if there was a significant improvement in Lysholm scores. Comparison of Lysholm improvement for binary categorical variables was performed using the independent samples t-test. Comparison of Lysholm with continuous variables was performed using Pearson correlation coefficient. Comparisons between categorical variables were performed using Fisher exact test. Data were tested for normal distribution using Kolmogorov–Smirnov Z-test. Distribution of the patient satisfaction and Tegner activity level were significantly different from a normal distribution (p < 0.001). Nonparametric statistical techniques were employed to analyze these variables. Comparisons between continuous variables were evaluated using Spearman rho. The Mann–Whitney test was used to compare continuous variables between the two groups. Statistical analysis was performed using SPSS (version 11.0, SPSS Inc., Chicago, IL) software package. All reported p values are twotailed, with an α level of 0.05 indicating statistical significance.
Operative Technique Patients underwent knee arthroscopy and microfracture using a well-established technique that has been previously described.29–31 A standard knee arthroscopy was performed to confirm the presence of an articular cartilage defect. When the full-thickness chondral defect was identified, the unstable cartilage was circumferentially debrided from the underlying exposed bone and the surrounding rim of articular cartilage to unearth a healthy circumference of cartilage around the lesion.29–31 Microfracture holes were placed 3 to 4 mm in depth using an awl, as close together as possible without breaking into adjacent holes, resulting in 10 to 12 holes per cm2. In contrast to microfracture performed in the adult population, only hand pressure is used to make the microfracture awl holes. If microfracture was performed on the patella, a 90-degree awl was used, but it should only be advanced manually with no use of a mallet. In addition, in a younger population, care should be taken to avoid the growth plates.29 Once arthroscopic pressure was reduced, marrow elements were visualized, and then instruments were removed. No intra-articular drains are placed because the goal is for surgically induced marrow bodies to form in the lesion.
Rehabilitation Protocol The postoperative program is designed to promote the ideal physical environment in which the newly recruited mesenchymal stem cells from the marrow can differentiate into the appropriate articular cartilage-like cell lines.29–31
Rehabilitation Protocol for Patients with Lesions on the Femoral Condyle or Tibial Plateau After microfracture of lesions on the weight-bearing surfaces of the femoral condyles or tibial plateaus, a continuous
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Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee
Rehabilitation Protocol for Patients with Patellofemoral Lesions All patients treated by microfracture for patellofemoral lesions must use a brace set at 0 to 20 degrees for at least 8 weeks. This brace limits compression of the regenerating surfaces of the trochlea or patella, or both. Passive motion with the brace removed is allowed, but otherwise the brace must be worn at all times. Patients are placed into a CPM machine immediately postoperatively. Cold therapy is also prescribed as previously described. Joint angles are carefully observed at the time of arthroscopy to determine whether the defect comes into contact with the patellar facet or the trochlear groove. We avoid these areas during strength training for approximately 4 months. This avoidance allows for training in the 0 to 20 degrees range immediately postoperatively because there is minimal compression of these chondral surfaces with such limited motion. Patients are allowed weight-bearing as tolerated in their brace 2 weeks after surgery. It is essential for patients to use a brace that prevents placing excessive shear force on the maturing marrow clot in the early postoperative period. We routinely lock the brace between 0 and 20 degrees ROM to prevent flexion past the point where the median ridge of the patella engages the trochlear groove. After 8 weeks, we gradually open the knee brace before it is discontinued. When the brace is discontinued, patients are allowed to advance their training progressively. Stationary biking is allowed 2 weeks postoperatively, with increased resistance added at 8 weeks after microfracture. Starting 12 weeks after microfracture, the exercise program is the same one used for femorotibial lesions.
147
Results A total of 26 patients (14 females, 12 males) met the inclusion criteria. Average age was 16.6 years (range: 12.0–18.9 years). Location of the cartilage defects are listed in ►Table 1. The vast majority of lesions (96%) were either patellar (37%) or femoral condyle defects (medial 26%, lateral 33%). The mean size of medial femoral condyle defects was 177 mm2 (range: 10–400 mm2). The mean size of lateral femoral condyle defects was 188 mm2 (range: 25–600 mm2). The mean size of patella-femoral condyle defects was 209 mm2 (range: 4– 572 mm2). Two patients underwent microfracture of both the medial femoral condyle and patella. No major complications were reported. Eleven patients underwent microfracture within 6 months from time of injury, while 15 patients underwent microfracture 6 months or longer from initial injury.
Concomitant Pathology Ten patients underwent anterior cruciate ligament surgery at the time of microfracture, of which six patients underwent reconstruction, three underwent primary repair, and one underwent thermal treatment. Also, three patients underwent partial meniscectomy and three patients underwent meniscus repair at the time of index procedure.
Outcomes Minimum 2-year follow-up was obtained in 22 of 26 patients (85%) at an average follow-up of 5.8 years (range: 2.0–13.3 years). Average postoperative Lysholm score was 90 (range: 50–100). Median Tegner activity scale was 6 (range: 2–10). Median patient satisfaction with outcome was 10 (range: 1– 10). Age did not correlate with outcomes scores. Lysholm correlated with Tegner activity scale (rho ¼ 0.586; p ¼ 0.011) and patient satisfaction (rho ¼ 0.70; p ¼ 0.001). There was no significant difference in Lysholm score for gender. Males had an average Lysholm score of 93 and females had an average Lysholm score of 86 (p ¼ 0.22). There was also no significant difference in Tegner activity scale for gender (p ¼ 0.33) or patient satisfaction (p ¼ 0.51). Three patients had Lysholm scores less than 80. All three were females and 18 years old. Two underwent microfracture
Table 1 Traumatic full-thickness chondral defects in pediatric knees Defect location Patella
Number of knees
a
10
Lateral femoral condyle Medial femoral condyle Trochlear groove
a
9
a
8 1
Medial tibial plateau
0
Lateral tibial plateau
0
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passive motion (CPM) machine is used immediately in the recovery room. The initial range of motion (ROM) is typically 30 to 70 degrees, and it can be increased as tolerated by the patient. The goal is to have the patient in the CPM machine for 6 to 8 hours every 24 hours. Cold therapy is usually used for 1 to 7 days postoperatively. Crutch-assisted touch-down weight-bearing ambulation for 6 to 8 weeks is prescribed, depending on lesion size. Mobilization begins immediately after surgery, with an emphasis on ROM of the knee, patellar, and patellar tendon motion. Patients are touch-down weight-bearing, placing 10% of body weight on the injured leg during weight-bearing. One to 2 weeks after microfracture, patients begin stationary biking without resistance and a deep-water exercise program. Patients progress to full weight-bearing after about 8 weeks, and begin more vigorous biking with increasing resistance. They also begin knee flexion exercises at approximately the same time. An elastic resistance cord is added to the exercise regimen at about 12 weeks. The decision to return to sport is based on several factors, including clinical examination, size of the patient, sport, and size of the lesion. We usually recommend that patients do not return to sports that involve pivoting, cutting, and jumping until at least 4 to 9 months after microfracture.
Steadman et al.
Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee of the patella and one underwent microfracture of the trochlear groove. The patient who underwent the trochlear groove microfracture had a revision microfracture 1 year following the initial microfracture procedure. No other patient required revision microfracture.
Discussion This current study demonstrated improved function, increased activity levels, and excellent patient satisfaction in patients aged 18 years or younger who underwent microfracture for full-thickness articular cartilage lesions of the knee. These findings are consistent with previous studies involving microfracture of chondral defects.32 In a study on microfracture of isolated traumatic chondral defects demonstrated good to excellent results in patients 45 years or younger. Lysholm scores improved from 59 preoperatively to 89 postoperatively and activity level, as indicated by Tegner activity scale, also improved from a 3 preoperatively to a 6 postoperatively. This study showed improvement in function and satisfaction in 95% of patients at a minimum of 7 years postoperatively.4 In a study by Kreuz et al, similar findings with respect to microfracture and age were revealed.33 Their prospective study, which used the modified Cincinnati knee and International Cartilage Repair Society (ICRS) scores, showed that there was significant improvement in all groups, but that patients aged 40 years or younger had markedly better scores. Furthermore, patients younger than 40 years old did not experience any regression in scores throughout the 36month study period, while those older than 40 reported deterioration between 18 and 36 months. Magnetic resonance images taken 36 months after surgery also showed better fill in younger patients.4 These findings are analogous to the improvement in function, pain, and high satisfaction we observed in this adolescent patient population. There are limited data on outcomes in adolescent patients undergoing microfracture for articular cartilage repair. However, outcomes following ACI in a pediatric population have been shown to be similar to those of adolescent microfracture.34 Macmull et al documented results of ACI in patients aged 14 to 18 years old (mean age of 16.6 years). At an average of 5.5 years following treatment, pain and function significantly improved according to Modified Cincinnati and ICRS scores; one patient required a subsequent debridement due to hypertrophy of the periosteal graft.34 Furthermore, while multiple studies have documented microfracture outcomes in general, few have addressed these outcomes in athletes.19,20,35 The athletic population and the adolescent population are similar in that both groups tend to be more active as evidenced by Tegner activity scales. In a study by Mithoefer et al,19 microfracture was found to be an effective primary treatment of articular cartilage defects in patients who participated in sports. Sixty-six percent of patients reported having good or excellent results following surgery, and 44% reported being able to return to regular participation in high-impact sports. Their study also found that younger age correlated to better outcomes.19 The Journal of Knee Surgery
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Limitations Limitations of this present study include the retrospective nature and lack of a control group. There was also a patient selection bias due to the fact that the study was conducted at one referral center. This study also lacks long-term clinical follow-up, which was difficult to obtain; however, validated outcomes measures were used. No patients underwent a “second look” arthroscopy to determine repair tissue quality and percentage of defect fill. It was also difficult to determine predictors of failure due to the limited number of failures with which to compare the successes. Also, longer follow-up is necessary to determine the longevity of continued favorable patient-reported outcomes after microfracture in the pediatric adolescent population.
Conclusion In summary, we found that arthroscopically performed microfracture for full-thickness chondral defects in patients 18 years of age or younger led to significant improvement as measured by the Lysholm score and Tegner activity scale. Patients also reported a high level of satisfaction. This present study showed that adolescent patients who undergo microfracture for treatment for full-thickness chondral defects of the knee can demonstrate increased activity levels and symptom improvement.
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TIG/ACT/01/2000&EXT Study Group. Five-year outcome of characterized chondrocyte implantation versus microfracture for symptomatic cartilage defects of the knee: early treatment matters. Am J Sports Med 2011;39(12):2566–2574 Salzmann GM, Sah BR, Schmal H, Niemeyer P, Sudkamp NP. Microfracture for treatment of knee cartilage defects in children and adolescents. Pediatr Rep 2012;4(2):e21 Negrin LL, Vécsei V. Do meta-analyses reveal time-dependent differences between the clinical outcomes achieved by microfracture and autologous chondrocyte implantation in the treatment of cartilage defects of the knee? J Orthop Sci 2013;18(6): 940–948 Kocher MS, Steadman JR, Briggs KK, Sterett WI, Hawkins RJ. Reliability, validity, and responsiveness of the Lysholm knee scale for various chondral disorders of the knee. J Bone Joint Surg Am 2004;86-A(6):1139–1145 Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am J Sports Med 1982;10(3):150–154 Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res 1985;(198):43–49 Steadman JR. Microfracture. In: Feagin JA, Steadman JR, eds. The Crucial Principles in Care of the Knee. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:129–151 Steadman JR, Rodkey WG, Briggs KK. Microfracture to treat fullthickness chondral defects: surgical technique, rehabilitation, and outcomes. J Knee Surg 2002;15(3):170–176 Steadman JR, Rodkey WG, Rodrigo JJ. Microfracture: surgical technique and rehabilitation to treat chondral defects. Clin Orthop Relat Res 2001(391, Suppl):S362–S369 Kreuz PC, Steinwachs MR, Erggelet C, et al. Results after microfracture of full-thickness chondral defects in different compartments in the knee. Osteoarthritis Cartilage 2006;14(11): 1119–1125 Kreuz PC, Erggelet C, Steinwachs MR, et al. Is microfracture of chondral defects in the knee associated with different results in patients aged 40 years or younger? Arthroscopy 2006;22(11): 1180–1186 Macmull S, Parratt MT, Bentley G, et al. Autologous chondrocyte implantation in the adolescent knee. Am J Sports Med 2011;39(8): 1723–1730 Harris JD, Brophy RH, Siston RA, Flanigan DC. Treatment of chondral defects in the athlete’s knee. Arthroscopy 2010;26(6): 841–852
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microfracture technique: a blinded, randomized, controlled, longterm follow-up trial in 88 knees. Knee Surg Sports Traumatol Arthrosc 2012;20(2):197–209 Bhosale AM, Kuiper JH, Johnson WE, Harrison PE, Richardson JB. Midterm to long-term longitudinal outcome of autologous chondrocyte implantation in the knee joint: a multilevel analysis. Am J Sports Med 2009;37(Suppl 1):131S–138S Filardo G, Kon E, Di Martino A, Iacono F, Marcacci M. Arthroscopic second-generation autologous chondrocyte implantation: a prospective 7-year follow-up study. Am J Sports Med 2011;39(10): 2153–2160 Vasiliadis HS, Wasiak J, Salanti G. Autologous chondrocyte implantation for the treatment of cartilage lesions of the knee: a systematic review of randomized studies. Knee Surg Sports Traumatol Arthrosc 2010;18(12):1645–1655 Van Assche D, Van Caspel D, Vanlauwe J, et al. Physical activity levels after characterized chondrocyte implantation versus microfracture in the knee and the relationship to objective functional outcome with 2-year follow-up. Am J Sports Med 2009;37 (Suppl 1):42S–49S Asik M, Ciftci F, Sen C, Erdil M, Atalar A. The microfracture technique for the treatment of full-thickness articular cartilage lesions of the knee: midterm results. Arthroscopy 2008;24(11):1214–1220 Knutsen G, Drogset JO, Engebretsen L, et al. A randomized trial comparing autologous chondrocyte implantation with microfracture. Findings at five years. J Bone Joint Surg Am 2007;89(10): 2105–2112 Mithoefer K, McAdams T, Williams RJ, Kreuz PC, Mandelbaum BR. Clinical efficacy of the microfracture technique for articular cartilage repair in the knee: an evidence-based systematic analysis. Am J Sports Med 2009;37(10):2053–2063 Mithoefer K, Williams RJ III, Warren RF, Wickiewicz TL, Marx RG. High-impact athletics after knee articular cartilage repair: a prospective evaluation of the microfracture technique. Am J Sports Med 2006;34(9):1413–1418 Riyami M, Rolf C. Evaluation of microfracture of traumatic chondral injuries to the knee in professional football and rugby players. J Orthop Surg 2009;4:13 Solheim E, Øyen J, Hegna J, Austgulen OK, Harlem T, Strand T. Microfracture treatment of single or multiple articular cartilage defects of the knee: a 5-year median follow-up of 110 patients. Knee Surg Sports Traumatol Arthrosc 2010;18(4):504–508 Spahn G, Mückley T, Kahl E, Hofmann GO. Factors affecting the outcome of arthroscopy in medial-compartment osteoarthritis of the knee. Arthroscopy 2006;22(11):1233–1240
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Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee in Adolescent Patients J. Richard Steadman, MD1 Karen K. Briggs, MPH1 Chad M. Hanson, MD2 S. Clifton Willimon, MD3 1 Center for Outcomes-Based Orthopaedic Research, Steadman
Philippon Research Institute, Vail, Colorado 2 Desert Orthopaedic Center, Henderson, Nevada 3 Children’s Orthopaedics of Atlanta, Atlanta, Georgia
Lauren M. Matheny, BA1
Alyson Guillet, MD1
Address for correspondence J. Richard Steadman, MD, Center for Outcomes-Based Orthopaedic Research, Steadman Philippon Research Institute, 181 W. Meadow Drive, Suite 1000, Vail, CO 81657 (e-mail: [email protected]).
Abstract
Keywords
► ► ► ►
microfracture articular cartilage knee adolescent
The purpose of this study was to document outcomes following microfracture for fullthickness cartilage defects of the knee in adolescents. Our hypothesis was that patients aged 18 years or less would have excellent outcomes and function following microfracture of full-thickness knee articular cartilage defects. This study was approved by the Institutional Review Board. Patients < 19 years old with full-thickness knee articular cartilage defects treated with microfracture between January 1992 and June 2008 were identified. Surgical, demographic data, Lysholm score, Tegner activity scale, and patient satisfaction were collected prospectively. A total of 26 patients (14 females, 12 males) met inclusion criteria. Average age was 16.6 years (range: 12–18.9 years). Ninety-six percent of lesions were patellar (37%) or femoral condyle defects (medial 26%, lateral 33%). Minimum 2-year follow-up was obtained in 22/26 patients (85%) with average follow-up of 5.8 years (range: 2.0–13.3 years). Average postoperative Lysholm score was 90 (range: 50–100). Median Tegner scale was 6 (range: 2–10). Median patient satisfaction with outcome was 10 (range: 1–10). Lysholm correlated with Tegner scale (rho ¼ 0.586; p ¼ 0.011) and patient satisfaction (rho ¼ 0.70; p ¼ 0.001). Average postoperative Lysholm score in males was 93 and 86 in females (p ¼ 0.22). One patient underwent revision microfracture. This study showed that adolescent patients who underwent microfracture for treatment of full-thickness knee chondral defects demonstrated increased activity levels and excellent function following surgery.
Sports participation in adolescents has grown greatly over recent years. Due to this increased level of play, knee injuries in this population are on the rise.1 Although athletic participation has numerous advantages, sport-related injury is a potential negative consequence, and one that is also increasing.2 Among these injuries are lesions of the articular cartilage. Injuries to articular cartilage of the knee present a
challenge to the orthopedic surgeon treating this younger population.3 Since articular cartilage lacks the capacity to heal spontaneously,4 many patients experience pain, deficits in function and will develop knee osteoarthritis over time if left untreated.5 Surgical intervention is recommended to reduce the symptoms associated with articular cartilage.6 However, the orthopedic surgeon treating pediatric patients
received September 6, 2013 accepted after revision February 11, 2014 published online April 24, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1373737. ISSN 1538-8506.
Downloaded by: The University of Hong Kong. Copyrighted material.
J Knee Surg 2015;28:145–150.
Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee face the dilemma of balancing intervention for the damaged cartilage and maintaining the knee’s integrity to avoid future degeneration.6 Several surgical interventions to address chondral defects of the knee exist including arthroscopic debridement, mosaicplasty, autologous chondrocyte implantation (ACI), osteochondral allograft, and microfracture. Arthroscopic debridement alone has shown suboptimal results when compared with other treatments for full-thickness chondral defects of the knee.7 Mosaicplasty is another cartilage repair treatment8; however, disadvantages of use include donor site morbidity, failure of chondral integration,9 limited availability of graft from the patellofemoral joint, multiple surgeries, and mechanical differences in donor and recipient cartilage.5,10 Subchondral bone integrity may become compromised with this procedure as well.11 ACI is another treatment option,12–14 but limitations include high cost, patients undergoing two surgeries and increased rate of graft hypertrophies with periosteum.15 Multiple studies have documented improvements in pain, function, and activity level following microfracture of the knee in the adult population.16–23 Advantages of microfracture include a single surgery, low surgical morbidity, relatively low cost, technical simplicity, and decreased operative time.4,16 Although outcomes following these various treatments for cartilage defects of the knee have been extensively documented, controversy regarding the optimal treatment still exists and there is little literature documenting outcomes following treatment of cartilage defects in adolescent patients.24,25 The purpose of this study was to document outcomes of microfracture for full-thickness cartilage defects of the knee in the adolescent population. Our hypothesis was that patients aged 18 years and younger will have good outcomes and function following microfracture of full-thickness knee articular cartilage defects.
Methods Patient Selection This study was approved by the Institutional Review Board. All patients younger than 19 years of age, with full-thickness articular cartilage defects of the knee treated with microfracture, between January 1992 and June 2008 were identified. Patients were excluded from this study if they were older than 18 years or had axial malalignment as evidenced by clinical presentation and weight-bearing long leg films. All patients were a minimum of 2 years status post-microfracture. Surgical and demographic data were collected prospectively and reviewed retrospectively.
Outcomes Evaluation Patients were administered subjective questionnaires preoperatively and at a minimum of 2 years following microfracture surgery. Patients completed these questionnaires for evaluation of pain, symptoms of giving way, function, return to sports, activities of daily living, and their satisfaction with the outcome. Lysholm scores and Tegner activity scale were also documented.26–28 Patient satisfaction was graded on a The Journal of Knee Surgery
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10-point ordinal scale with 10 being very satisfied and 1 being very dissatisfied.
Statistical Analysis The paired t-test was used to determine if there was a significant improvement in Lysholm scores. Comparison of Lysholm improvement for binary categorical variables was performed using the independent samples t-test. Comparison of Lysholm with continuous variables was performed using Pearson correlation coefficient. Comparisons between categorical variables were performed using Fisher exact test. Data were tested for normal distribution using Kolmogorov–Smirnov Z-test. Distribution of the patient satisfaction and Tegner activity level were significantly different from a normal distribution (p < 0.001). Nonparametric statistical techniques were employed to analyze these variables. Comparisons between continuous variables were evaluated using Spearman rho. The Mann–Whitney test was used to compare continuous variables between the two groups. Statistical analysis was performed using SPSS (version 11.0, SPSS Inc., Chicago, IL) software package. All reported p values are twotailed, with an α level of 0.05 indicating statistical significance.
Operative Technique Patients underwent knee arthroscopy and microfracture using a well-established technique that has been previously described.29–31 A standard knee arthroscopy was performed to confirm the presence of an articular cartilage defect. When the full-thickness chondral defect was identified, the unstable cartilage was circumferentially debrided from the underlying exposed bone and the surrounding rim of articular cartilage to unearth a healthy circumference of cartilage around the lesion.29–31 Microfracture holes were placed 3 to 4 mm in depth using an awl, as close together as possible without breaking into adjacent holes, resulting in 10 to 12 holes per cm2. In contrast to microfracture performed in the adult population, only hand pressure is used to make the microfracture awl holes. If microfracture was performed on the patella, a 90-degree awl was used, but it should only be advanced manually with no use of a mallet. In addition, in a younger population, care should be taken to avoid the growth plates.29 Once arthroscopic pressure was reduced, marrow elements were visualized, and then instruments were removed. No intra-articular drains are placed because the goal is for surgically induced marrow bodies to form in the lesion.
Rehabilitation Protocol The postoperative program is designed to promote the ideal physical environment in which the newly recruited mesenchymal stem cells from the marrow can differentiate into the appropriate articular cartilage-like cell lines.29–31
Rehabilitation Protocol for Patients with Lesions on the Femoral Condyle or Tibial Plateau After microfracture of lesions on the weight-bearing surfaces of the femoral condyles or tibial plateaus, a continuous
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Rehabilitation Protocol for Patients with Patellofemoral Lesions All patients treated by microfracture for patellofemoral lesions must use a brace set at 0 to 20 degrees for at least 8 weeks. This brace limits compression of the regenerating surfaces of the trochlea or patella, or both. Passive motion with the brace removed is allowed, but otherwise the brace must be worn at all times. Patients are placed into a CPM machine immediately postoperatively. Cold therapy is also prescribed as previously described. Joint angles are carefully observed at the time of arthroscopy to determine whether the defect comes into contact with the patellar facet or the trochlear groove. We avoid these areas during strength training for approximately 4 months. This avoidance allows for training in the 0 to 20 degrees range immediately postoperatively because there is minimal compression of these chondral surfaces with such limited motion. Patients are allowed weight-bearing as tolerated in their brace 2 weeks after surgery. It is essential for patients to use a brace that prevents placing excessive shear force on the maturing marrow clot in the early postoperative period. We routinely lock the brace between 0 and 20 degrees ROM to prevent flexion past the point where the median ridge of the patella engages the trochlear groove. After 8 weeks, we gradually open the knee brace before it is discontinued. When the brace is discontinued, patients are allowed to advance their training progressively. Stationary biking is allowed 2 weeks postoperatively, with increased resistance added at 8 weeks after microfracture. Starting 12 weeks after microfracture, the exercise program is the same one used for femorotibial lesions.
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Results A total of 26 patients (14 females, 12 males) met the inclusion criteria. Average age was 16.6 years (range: 12.0–18.9 years). Location of the cartilage defects are listed in ►Table 1. The vast majority of lesions (96%) were either patellar (37%) or femoral condyle defects (medial 26%, lateral 33%). The mean size of medial femoral condyle defects was 177 mm2 (range: 10–400 mm2). The mean size of lateral femoral condyle defects was 188 mm2 (range: 25–600 mm2). The mean size of patella-femoral condyle defects was 209 mm2 (range: 4– 572 mm2). Two patients underwent microfracture of both the medial femoral condyle and patella. No major complications were reported. Eleven patients underwent microfracture within 6 months from time of injury, while 15 patients underwent microfracture 6 months or longer from initial injury.
Concomitant Pathology Ten patients underwent anterior cruciate ligament surgery at the time of microfracture, of which six patients underwent reconstruction, three underwent primary repair, and one underwent thermal treatment. Also, three patients underwent partial meniscectomy and three patients underwent meniscus repair at the time of index procedure.
Outcomes Minimum 2-year follow-up was obtained in 22 of 26 patients (85%) at an average follow-up of 5.8 years (range: 2.0–13.3 years). Average postoperative Lysholm score was 90 (range: 50–100). Median Tegner activity scale was 6 (range: 2–10). Median patient satisfaction with outcome was 10 (range: 1– 10). Age did not correlate with outcomes scores. Lysholm correlated with Tegner activity scale (rho ¼ 0.586; p ¼ 0.011) and patient satisfaction (rho ¼ 0.70; p ¼ 0.001). There was no significant difference in Lysholm score for gender. Males had an average Lysholm score of 93 and females had an average Lysholm score of 86 (p ¼ 0.22). There was also no significant difference in Tegner activity scale for gender (p ¼ 0.33) or patient satisfaction (p ¼ 0.51). Three patients had Lysholm scores less than 80. All three were females and 18 years old. Two underwent microfracture
Table 1 Traumatic full-thickness chondral defects in pediatric knees Defect location Patella
Number of knees
a
10
Lateral femoral condyle Medial femoral condyle Trochlear groove
a
9
a
8 1
Medial tibial plateau
0
Lateral tibial plateau
0
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passive motion (CPM) machine is used immediately in the recovery room. The initial range of motion (ROM) is typically 30 to 70 degrees, and it can be increased as tolerated by the patient. The goal is to have the patient in the CPM machine for 6 to 8 hours every 24 hours. Cold therapy is usually used for 1 to 7 days postoperatively. Crutch-assisted touch-down weight-bearing ambulation for 6 to 8 weeks is prescribed, depending on lesion size. Mobilization begins immediately after surgery, with an emphasis on ROM of the knee, patellar, and patellar tendon motion. Patients are touch-down weight-bearing, placing 10% of body weight on the injured leg during weight-bearing. One to 2 weeks after microfracture, patients begin stationary biking without resistance and a deep-water exercise program. Patients progress to full weight-bearing after about 8 weeks, and begin more vigorous biking with increasing resistance. They also begin knee flexion exercises at approximately the same time. An elastic resistance cord is added to the exercise regimen at about 12 weeks. The decision to return to sport is based on several factors, including clinical examination, size of the patient, sport, and size of the lesion. We usually recommend that patients do not return to sports that involve pivoting, cutting, and jumping until at least 4 to 9 months after microfracture.
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Outcomes following Microfracture of Full-Thickness Articular Cartilage Lesions of the Knee of the patella and one underwent microfracture of the trochlear groove. The patient who underwent the trochlear groove microfracture had a revision microfracture 1 year following the initial microfracture procedure. No other patient required revision microfracture.
Discussion This current study demonstrated improved function, increased activity levels, and excellent patient satisfaction in patients aged 18 years or younger who underwent microfracture for full-thickness articular cartilage lesions of the knee. These findings are consistent with previous studies involving microfracture of chondral defects.32 In a study on microfracture of isolated traumatic chondral defects demonstrated good to excellent results in patients 45 years or younger. Lysholm scores improved from 59 preoperatively to 89 postoperatively and activity level, as indicated by Tegner activity scale, also improved from a 3 preoperatively to a 6 postoperatively. This study showed improvement in function and satisfaction in 95% of patients at a minimum of 7 years postoperatively.4 In a study by Kreuz et al, similar findings with respect to microfracture and age were revealed.33 Their prospective study, which used the modified Cincinnati knee and International Cartilage Repair Society (ICRS) scores, showed that there was significant improvement in all groups, but that patients aged 40 years or younger had markedly better scores. Furthermore, patients younger than 40 years old did not experience any regression in scores throughout the 36month study period, while those older than 40 reported deterioration between 18 and 36 months. Magnetic resonance images taken 36 months after surgery also showed better fill in younger patients.4 These findings are analogous to the improvement in function, pain, and high satisfaction we observed in this adolescent patient population. There are limited data on outcomes in adolescent patients undergoing microfracture for articular cartilage repair. However, outcomes following ACI in a pediatric population have been shown to be similar to those of adolescent microfracture.34 Macmull et al documented results of ACI in patients aged 14 to 18 years old (mean age of 16.6 years). At an average of 5.5 years following treatment, pain and function significantly improved according to Modified Cincinnati and ICRS scores; one patient required a subsequent debridement due to hypertrophy of the periosteal graft.34 Furthermore, while multiple studies have documented microfracture outcomes in general, few have addressed these outcomes in athletes.19,20,35 The athletic population and the adolescent population are similar in that both groups tend to be more active as evidenced by Tegner activity scales. In a study by Mithoefer et al,19 microfracture was found to be an effective primary treatment of articular cartilage defects in patients who participated in sports. Sixty-six percent of patients reported having good or excellent results following surgery, and 44% reported being able to return to regular participation in high-impact sports. Their study also found that younger age correlated to better outcomes.19 The Journal of Knee Surgery
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Limitations Limitations of this present study include the retrospective nature and lack of a control group. There was also a patient selection bias due to the fact that the study was conducted at one referral center. This study also lacks long-term clinical follow-up, which was difficult to obtain; however, validated outcomes measures were used. No patients underwent a “second look” arthroscopy to determine repair tissue quality and percentage of defect fill. It was also difficult to determine predictors of failure due to the limited number of failures with which to compare the successes. Also, longer follow-up is necessary to determine the longevity of continued favorable patient-reported outcomes after microfracture in the pediatric adolescent population.
Conclusion In summary, we found that arthroscopically performed microfracture for full-thickness chondral defects in patients 18 years of age or younger led to significant improvement as measured by the Lysholm score and Tegner activity scale. Patients also reported a high level of satisfaction. This present study showed that adolescent patients who undergo microfracture for treatment for full-thickness chondral defects of the knee can demonstrate increased activity levels and symptom improvement.
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