Patient-Centered Outcomes After Hip Arthroscopy for Femoroacetabular Impingement and Labral Tears Are Not Different in Patients With Normal, High, or Low Femoral Version Fernando P. Ferro, M.D., Charles P. Ho, M.D., Ph.D., Karen K. Briggs, M.P.H., and Marc J. Philippon, M.D.
Purpose: The purpose of this study was to determine whether outcomes after hip arthroscopy were different based on femoral version. Methods: The inclusion criteria were diagnosis of femoroacetabular impingement (FAI) based on clinical examination and/or imaging findings and preoperative measurement of femoral version by magnetic resonance imaging. For this study, the definition of FAI was a positive impingement sign, a positive flexioneabductioneexternal rotation examination finding, or radiographic signs of impingement. A query of a prospective data registry identified 180 patients who matched the inclusion and exclusion criteria. Group 1 had version of less than 5 (n ¼ 48), group 2 had version of 5 to 15 (n ¼ 84), and group 3 had version greater than 15 (n ¼ 48). The mean age of the patients was 35 years (range, 18 to 61 years). Results: On radiographic examination, the mean alpha angle for all patients’ injured hips was 63 (range, 42 to 88 ). The mean center-edge angle was 30 (range, 20 to 43 ), and mean femoral version was 9.9 (range, 16 to 29 ). There was no significant difference in age, alpha angle, or center-edge angle among the 3 version groups. A significant difference in psoas release procedures (psoas impingement) was seen with increasing femoral version. The mean follow-up period was 30 months (range, 18 to 47 months). Patient-reported functional outcomes were not statistically different among the groups. Conclusions: Patient-reported functional outcomes after hip arthroscopy for labral tears and FAI were not different based on femoral version in this population. Although some differences were observed regarding intraoperative findings, these also did not result in differences in patient outcomes reported at a mean follow-up of 2 years. Level of Evidence: Level IV, therapeutic case series.
F
emoroacetabular impingement (FAI) is recognized as a significant cause of hip pain and is the most common indication for hip arthroscopic procedures.1 Recently, there has been increased interest in proximal femur and acetabular anatomic variations and their contributions to FAI. Although cam- and pincer-type deformities are widely described as the From the Steadman Philippon Research Institute, Vail, Colorado, U.S.A. The authors report the following potential conflict of interest or source of funding: F.P.F., C.P.H., and K.K.B. receive research support from Smith & Nephew, Össur, Siemens. M.J.P. receives support from Smith & Nephew, MIS, Össur Americas, Siemens, Arthrosurface, DonJoy, Linvatec, HIPCO. Received February 25, 2014; accepted October 3, 2014. Address correspondence to Marc J. Philippon, M.D., Attn: Center for Outcomes-based Orthopaedic Research, Steadman Philippon Research Institute, 181 W Meadow Dr, Ste 1000, Vail, CO 81657, U.S.A. E-mail: [email protected] Ó 2015 by the Arthroscopy Association of North America 0749-8063/14161/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.10.008
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fundamental precipitators, there is limited information on the potential role of other anatomic variations in FAI.2,3 Historically, alterations in femoral version have been associated with a wide range of hip pathology. Increased and decreased femoral version has been associated with osteoarthritis of the hip. Hip dysplasia has been correlated with increased version, whereas decreased version has been linked to slipped capital femoral epiphysis.4-7 It has been postulated over the past 15 years that decreased or increased femoral version may be a key precipitator of FAI. Several studies have shown that increased and decreased femoral version contributes to FAI. Decreased femoral version has been reported as a predisposing factor in impingement pathomechanics leading to FAI.8,9 Ejnisman et al.3 found that patients with high femoral anteversion (>15 ) are at increased risk of having more anterior labral tears (beyond the 3-o’clock position).
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 31, No 3 (March), 2015: pp 454-459
HIP ARTHROSCOPY OUTCOMES AND FEMORAL VERSION
The soft tissues surrounding the hip joint also influence the development of FAI and affect clinical outcomes of hip arthroscopy. Anatomically, the distal portion of the iliopsoas is in proximity to the acetabular labrum and anterior capsule. The iliopsoas can be a source of impingement without any bony abnormality and is a known cause of labral tears.10 Fabricant et al.11 studied the effect of excessive femoral version in psoas release procedures and reported that increased version (>25 ) correlates with inferior clinical outcomes after arthroscopic psoas lengthening. Specific hip pathology patterns have become evident with cam- and pincer-type impingement. Damage to the anterosuperior area of the acetabular rim is seen with cam impingement. Cam impingement cartilage damage initially presents in a fraying manner, leading to eventual separation from the subchondral bone in a linear fashion at the chondrolabral junction. Pincer impingement results in more pronounced labral degeneration and tearing in a global or circumferential pattern. “Contre-coup” cartilaginous lesions on either the femoral head or the posteroinferior acetabulum are also seen with pincer impingement due to repetitive posterior subluxation of the femoral head.2,3 However, there is limited information regarding whether certain patterns of pathology can be predicted with either excessive or diminished femoral version values. The purpose of this study was to determine whether outcomes after hip arthroscopy were different based on femoral version. Our hypothesis was that excessive femoral version would correlate with poorer clinical outcomes after hip arthroscopy.
Methods A query of a prospective data registry identified all patients who underwent a primary hip arthroscopy between July 2010 and July 2012 at our institution. The study was approved by our institutional review board. The inclusion criteria comprised a diagnosis of FAI based on clinical examination and/or imaging findings and preoperative measurement of femoral version by magnetic resonance imaging. For this study, the definition of FAI was a positive impingement sign, a positive flexioneabductioneexternal rotation examination finding, or radiographic signs of impingement. Patients were included if they had cam impingement, pincer impingement, or mixed impingement. We excluded patients who had a prior hip arthroscopy, were aged younger than 18 years, and had hip dysplasia as defined by a center-edge angle of less than 20 . Patients were divided into 3 groups according to femoral version values. For our study purposes, we designated 5 to 15 as normal femoral version because this is consistent with the majority of the published
455
Fig 1. Oblique sagittal cut of femoral neck. A line is drawn at the center of the femoral neck (line A), and the angle between this line and the horizontal line (line B) is measured (angle 1).
literature.2,7,12,13 Group 1 had version of less than 5 , group 2 had version of 5 to 15 , and group 3 had version greater than 15 . All patients underwent a standard clinical examination. This examination included range-of-motion measurements and provocative tests such as the anterior impingement test (flexioneadductioneinternal rotation), flexioneabductioneexternal rotation test, and hip dial test. Radiographs included an anteroposterior pelvic view, a cross-table lateral view, and a false-profile view. Cam FAI was defined as an anterior femoral head-neck offset (alpha) angle greater than 55 as measured on the cross-table lateral view. Pincer FAI was noted if the medial aspect of the femoral head was medial to the ilioischial line (protrusio acetabuli), if the floor of the acetabulum crossed the ilioischial line (coxa profunda), or if the anterior rim of the acetabulum projected more laterally than the posterior rim proximally (crossover sign) as shown on an anteroposterior pelvic view. A magnetic resonance imaging study was obtained for all patients with a 3-T unit (Magneto Verio 3T; Siemens, Erlangen, Germany). Images were systematically reviewed by an experienced musculoskeletal radiologist (C.P.H.) for the presence of labral tears, chondral lesions, ligamentum teres pathology, and other soft-tissue disorders. Femoral version was measured as described by Tomczak et al.14 The true femoral neck axis was visualized using an oblique axial-sagittal section. The angle between this line and the horizontal reference was called angle 1. At the knee level, angle 2 was then determined between the same horizontal reference and a line that was posteriorly tangential to both femoral condyles. The difference between angles 1 and 2 determined the femoral version (Figs 1 and 2).
456
F. P. FERRO ET AL. Table 1. Preoperative Findings by Version Group Age, yr Center-edge angle, Alpha angle, Internal rotation, External rotation, Positive hip dial test, %
Group 1 33 12 30 5 62 12 26 45 33
Group 2 35 12 30.9 5 64 10 32 45 38
Group 3 35 13 31 6 62 10 38 36 38
P Value NS NS NS .005 .031 NS
NOTE. Data are presented as mean or mean SD unless otherwise indicated. NS, not significant.
of the case, the capsule was closed at the level of the capsulotomy.
Fig 2. Axial cut of knee. A line is drawn tangential to the posterior aspect of the femoral condyles (line C), and the angle between this line and the horizontal line (line B) is measured (angle 2). The difference between angles 1 and 2 equals the femoral version.
This was a retrospective review of data collected prospectively and stored in a data registry. Clinical outcomes were assessed by patient questionnaires administered postoperatively by in person, by mail, or by e-mail and consisted of the Short Form 12, Western Ontario and McMaster Universities Arthritis Index, and modified Harris Hip Score (mHHS). The Short Form 12 is a general physical and mental health status score, whereas the Western Ontario and McMaster Universities Arthritis Index and mHHS are designed specifically for the hip joint and include questions regarding range of motion, pain, and ability to perform different daily activities. Surgical Technique All hip arthroscopies were performed by a single surgeon (M.J.P.) with patients in the modified supine position on a fracture table using anterolateral and midanterior portals, as previously described.15,16 At the time of hip arthroscopy, data were collected on hip pathology and surgical treatment procedures. Information included labral tears with specific emphasis on tear size and location; chondral damage; loose bodies; adhesions; and the condition of the ligamentum teres, capsule, femoral neck, acetabular rim, and iliopsoas. Femoral head-neck osteoplasty was performed for camtype FAI decompression, whereas acetabular rim trimming was executed for pincer-type FAI decompression. Loose bodies and adhesions were removed. At the end
Statistical Analysis The outcome scores used were not normally distributed (P < .05, Kolmogorov-Smirnov test). Scores were compared among groups using the Kruskal-Wallis test. Comparison between normally distributed values (labral tear size, alpha angle, center-edge angle, age, range of motion) was performed with 1-way analysis of variance. Statistical analyses were performed with PASW Statistics software (version 18.0; IBM SPSS, Armonk, NY). With an SD of 15 points for the mHHS, comparing 3 groups with Bonferroni correction, a total of 180 patients would be required to detect a difference of 9 points among groups with 80% power.
Results One hundred eighty patients met the inclusion criteria for this study. There were 48 patients in group 1 (femoral version 15 ). On radiographic examination, the mean alpha angle for all patients’ injured hips was 63 (range, 42 to 88 ). The mean center-edge angle was 30 (range, 20 to 43 ), and mean femoral version was 9.9 (range, 16 to 29 ). There was no significant difference in age, alpha angle, or center-edge angle among the 3 version groups (Table 1). Initial physical examination findings showed a significant difference among the groups for internal rotation. No significant differences were found for external rotation or a positive dial test (Table 1). All hips had labral tears identified at arthroscopy (Table 2). The only intraoperative findings that were different among groups were the location of the labral tear (Fig 3). The prevalence of labral tears beyond the 3-o’clock position (Fig 3B) was significantly greater in group 3 compared with the other groups. There were no differences in procedures performed at arthroscopy except for psoas release. A significant difference in psoas release procedures was seen with increasing femoral version (Table 3).
457
HIP ARTHROSCOPY OUTCOMES AND FEMORAL VERSION Table 2. Arthroscopic Findings by Version Group Capsular laxity Chondral lesions Labral tear size, mean SD, mm Anterior/superior labral tears Labral tear beyond 3-o’clock position Ligamentum teres hypertrophy Ligamentum teres partial tear
Table 3. Arthroscopic Treatments by Version Group
Group 1 46% (22) 56% (27) 28 10
Group 2 36% (30) 46% (36) 30 12
Group 3 46% (22) 50% (24) 27 12
P Value NS NS NS
73% (35)
71% (60)
65% (31)
NS
2% (1)
6% (3)
21% (10)
.005
31% (15)
33% (28)
37% (18)
NS
40% (19)
43% (36)
44% (21)
NS
NOTE. Data are presented as percent (number) unless otherwise indicated. NS, not significant.
The mean follow-up period was 30 months (range, 18 to 47 months). No complications were reported at final follow-up. Patient-reported functional outcomes were not statistically different among the groups. Outcome scores are shown in Table 4. For all patients, there was also no difference in outcomes between the patients with and without tears beyond the 3-o’clock position and those with and without psoas release.
Discussion This study showed that patient-centered functional outcomes were not different based on femoral version. Historically, abnormal femoral version has been noted to be a key contributor to prominent hip conditions such as osteoarthritis, hip dysplasia, and slipped capital femoral epiphysis.4-7 With FAI being a relatively new diagnosis, there is corresponding paucity in the literature as to the influence that femoral version has on FAI hip pathology and subsequent hip arthroscopy clinical outcomes. Ganz et al.8 reported that significantly decreased femoral anteversion was seen in patients presenting with FAI. Ejnisman et al.3 reported that hips with femoral version greater than 15 were 2.2 times more likely to have anterior labral tears. They also noted that hips in which a psoas release was performed had higher version angles (8 v 11 , P ¼ .023). Poorer Fig 3. (A) Right hip viewed from anterolateral portal. A labral repair is performed around the 2-o’clock position. (Numbers indicate clock position.) (B) Right hip viewed from anterolateral portal. A labral repair is performed beyond the 3-o’clock position. (Numbers indicate clock position.) Labral tears at this location are often associated with increased femoral version.
Acetabular rim trimming Osteoplasty Rim trim and osteoplasty Acetabular microfracture Femoral head microfracture Labral repair Labral reconstruction Psoas release Ligamentum teres debridement
Group 1 Group 2 Group 3 P Value 2% (1) 5% (4) 4% (2) NS 4% (2) 4% (3) 6% (3) NS 94% (45) 91% (77) 90% (43) NS 27% (13) 19% (16) 6% (10) NS 23% (11) 15% (13) 13% (6) NS 83% 17% 19% 96%
(40) (8) (9) (46)
87% 13% 56% 94%
(73) (11) (27) (79)
86% 14% 50% 96%
(41) (7) (24) (46)
NS NS .005 NS
NOTE. Data are presented as percent (number). NS, not significant.
clinical outcomes were documented by Fabricant et al.11 after an arthroscopic psoas lengthening procedure with increased femoral version values (>25 ). Patients with excessive femoral version reported an mHHS of 76.9 points compared with 86.1 points in patients with femoral version below 25 . Our study looked at patients with femoral version ranging from 16 to 29 , with only 3 patients with version greater than 25 and only 7 patients with version greater than 20 . We were unable to include patients with excessive femoral version because the senior surgeon (M.J.P.) considers this a relative contraindication. In addition, we did not find that those patients with a psoas release had poorer outcomes, but again, we did not have the high version levels that were shown in the study of Fabricant et al. Most previous studies have concentrated on the morphologic differences, biomechanical changes, and pathology patterns due to the femoral version in hip diseases. Studies correlating femoral version with differences in clinical outcomes are minimal. In a recent study, Jackson et al.17 showed that outcomes did not correlate with version. They did, however, show a trend toward higher scores in patients with retroversion (version of 2 or less). Although the results are similar to those of our study, the classification of version was different, with lower degrees of version in the retroversion group and higher degrees of version in the
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F. P. FERRO ET AL.
Table 4. Outcome Scores by Version Group Follow-up, mo SF-12 PCS, points SF-12 MCS, points WOMAC, points mHHS, points
Group 1 30.8 6 50.1 9 54.9 6 12.5 13 80 15
Group 2 28.9 5 49.8 10 55.4 8 15.4 16 82 15
Group 3 30.3 7 48.8 10 54.8 9 15.8 16 78 16
P Value NS NS NS NS NS
NOTE. Data are presented as mean SD. MCS, mental component summary; mHHS, modified Harris Hip Score; NS, not significant; PCS, physical component summary; SF-12, Short Form 12; WOMAC, Western Ontario and McMaster Universities Arthritis Index.
excessive anteversion group.17 This grouping makes it difficult to compare the 2 studies. In an analysis of revision hip arthroscopy cases, Ricciardi et al.18 found that abnormal version was not more common in revision cases compared with primary hip arthroscopy cases. Their study used computed tomography to measure femoral version and considered retroversion as less than 5 and increased anteversion as greater than 20 . The study did not correlate femoral version with outcome.18 The lack of notable clinical outcome differences associated with increased femoral version values was not expected in our study, especially given the previously established role of abnormal femoral version in other hip conditions such as osteoarthritis. It is still not known whether these differences in femoral version can be implicated in different incidences of arthritis in the long-term, and we acknowledge that further research and a longer follow-up period are necessary to clarify this question. An additional interest of this study was to establish hip pathology patterns that correlate with higher and/ or lower femoral version values. Patients with increased femoral version did exhibit a higher incidence of anterior labral tears. Only 4% of patients with femoral version of less than 5 presented with a labral tear beyond the 3-o’clock position, whereas 21% of patients with femoral version greater than 15 had an anterior labral tear. A significant association between femoral version and internal rotation range of motion was also identified. A decrease in femoral version equated to a decrease in internal rotation. Kelly et al.19 reported a similar correlation between femoral version and internal rotation. This relation highlights the importance of a thorough physical examination because increased internal rotation found during clinical assessment may be a signal of abnormal femoral version. In addition, psoas release procedures were performed at a higher rate in patients with increased femoral version compared with patients with normal or decreased version (27% for group 1 patients v 68% for group 3 patients). We hypothesize that increased femoral version creates a biomechanical condition in which the hip relies more on the psoas tendon for
dynamic anterior stability. This possibly causes this tendon to become tighter, thus conflicting with the anterior labrum, explaining why anterior labral tears are more common in patients with higher version.3,11 Even so, this additional hip pathology did not result in meaningful postoperative clinical outcome differences. Limitations The limitations of this study include the lack of information on acetabular morphology. Because we did not collect these data prospectively, we did not want to add the bias of measuring these data at the final data analysis. Given the null results, the possibility of a type II error is a risk. The primary determinant of this type of risk is the sample size. The sample size of this study may not have been large enough to account for the risk, and this is a limitation. Although we did meet the numbers of our power analysis, we did not have equal distribution among the groups. The lack of difference may also be because of the sensitivity of the outcome measures. We defined the minimum detectable difference as 9 points, which limits the ability to show change using the mHHS. To obtain an overall picture of the patients’ results, we included a general health score, a common disease-specific score, and a hip-specific score. None of the outcome scores were different. Data were limited to a minimum follow-up of 18 months. Longer follow-up is needed to determine whether hip arthroscopy can result in improvement over time regardless of femoral version. The study included no patients with femoral anteversion above 30 . Though not an exclusion criterion for this study, the senior surgeon does consider this a relative contraindication for hip arthroscopy, so data for such patients were not available for the study.
Conclusions Patient-reported functional outcomes after hip arthroscopy for labral tears and FAI were not different based on femoral version in this population. Although some differences were observed regarding intraoperative findings, these also did not result in differences in patient outcomes reported at a mean follow-up of 2 years.
References 1. Boykin RE, Patterson D, Briggs KK, Dee A, Philippon MJ. Results of arthroscopic labral reconstruction of the hip in elite athletes. Am J Sports Med 2013;41:2296-2301. 2. Philippon MJ, Maxwell RB, Johnston TL, Schenker M, Briggs KK. Clinical presentation of femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc 2007;15: 1041-1047. 3. Ejnisman L, Philippon MJ, Lertwanich P, et al. Relationship between femoral anteversion and findings in hips with femoroacetabular impingement. Orthopedics 2013;36: e293-e300.
HIP ARTHROSCOPY OUTCOMES AND FEMORAL VERSION 4. Tönnis D, Heinecke A. Acetabular and femoral anteversion: Relationship with osteoarthritis of the hip. J Bone Joint Surg Am 1999;81:1747-1770. 5. Byrd JW, Jones KS. Hip Arthroscopy in the presence of dysplasia. Arthroscopy 2003;19:1055-1060. 6. Jayakumar P, Ramachandran M, Youm T, Achan P. Arthroscopy of the hip for pediatric and adolescent disorders: Current concepts. J Bone Joint Surg Br 2012;94:290-296. 7. Reikeras O, Bjerkreim I, Kolbenstvedt A. Anteversion of the acetabulum and femoral neck in normal and in patients with osteoarthritis of the hip. Acta Orthop Scand 1983;54:18-23. 8. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: A cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003;417:112-120. 9. Ito K, Minka MA, Leunig M, Werlen S, Ganz R. Femoroacetabular impingement and the cam-effect. A MRIbased quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br 2001;83:171-176. 10. Domb BG, Shindle MK, McArthur B, Voos JE, Magennis EM, Kelly BT. Iliopsoas impingement: A newly identified cause of labral pathology in the hip. HSS J 2011;7:145-150. 11. Fabricant PD, Bedi A, De La Torre K, Kelly BT. Clinical outcomes after arthroscopic psoas lengthening: The effect of femoral version. Arthroscopy 2012;28:965-971. 12. Kingsley P, Olmsted K. A study to determine the angle of anteversion of the neck of the femur. J Bone Joint Surg Am 1948;30:745-751.
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13. Toogood PA, Skalak A, Cooperman DR. Proximal femoral anatomy in the normal human population. Clin Orthop Relat Res 2009;467:876-885. 14. Tomczak RJ, Guenther KP, Rieber A, Mergo P, Ros PR, Brambs HJ. MR imaging measurement of the femoral antetorsional angle as a new technique: Comparison with CT in children and adults. AJR Am J Roentgenol 1997;168: 791-794. 15. Philippon MJ, Schenker ML. A new method for acetabular rim trimming and labral repair. Clin Sports Med 2006;25:293-297. 16. Kelly BT, Weiland DE, Schenker ML, Philippon MJ. Arthroscopic labral repair in the hip: Surgical technique and review of the literature. Arthroscopy 2005;21: 1496-1504. 17. Jackson TJ, Lindner D, El-Bitar YF, Domb BG. Effect of femoral anteversion on clinical outcomes after hip arthroscopy. Arthroscopy in press, available online 10 September, 2014. doi:10.1016/j.arthro.2014.07.009. 18. Ricciardi BF, Fields K, Kelly BT, Ranawat AS, Coleman SH, Sink EL. Causes and risk factors for revision hip preservation surgery. Am J Sports Med 2014;42: 2627-2633. 19. Kelly BT, Bedi A, Robertson CM, Dela Torre K, Giveans MR, Larson CM. Alterations in internal rotation and alpha angles are associated with arthroscopic cam decompression in the hip. Am J Sports Med 2012;40: 1107-1112.
Purpose: The purpose of this study was to determine whether outcomes after hip arthroscopy were different based on femoral version. Methods: The inclusion criteria were diagnosis of femoroacetabular impingement (FAI) based on clinical examination and/or imaging findings and preoperative measurement of femoral version by magnetic resonance imaging. For this study, the definition of FAI was a positive impingement sign, a positive flexioneabductioneexternal rotation examination finding, or radiographic signs of impingement. A query of a prospective data registry identified 180 patients who matched the inclusion and exclusion criteria. Group 1 had version of less than 5 (n ¼ 48), group 2 had version of 5 to 15 (n ¼ 84), and group 3 had version greater than 15 (n ¼ 48). The mean age of the patients was 35 years (range, 18 to 61 years). Results: On radiographic examination, the mean alpha angle for all patients’ injured hips was 63 (range, 42 to 88 ). The mean center-edge angle was 30 (range, 20 to 43 ), and mean femoral version was 9.9 (range, 16 to 29 ). There was no significant difference in age, alpha angle, or center-edge angle among the 3 version groups. A significant difference in psoas release procedures (psoas impingement) was seen with increasing femoral version. The mean follow-up period was 30 months (range, 18 to 47 months). Patient-reported functional outcomes were not statistically different among the groups. Conclusions: Patient-reported functional outcomes after hip arthroscopy for labral tears and FAI were not different based on femoral version in this population. Although some differences were observed regarding intraoperative findings, these also did not result in differences in patient outcomes reported at a mean follow-up of 2 years. Level of Evidence: Level IV, therapeutic case series.
F
emoroacetabular impingement (FAI) is recognized as a significant cause of hip pain and is the most common indication for hip arthroscopic procedures.1 Recently, there has been increased interest in proximal femur and acetabular anatomic variations and their contributions to FAI. Although cam- and pincer-type deformities are widely described as the From the Steadman Philippon Research Institute, Vail, Colorado, U.S.A. The authors report the following potential conflict of interest or source of funding: F.P.F., C.P.H., and K.K.B. receive research support from Smith & Nephew, Össur, Siemens. M.J.P. receives support from Smith & Nephew, MIS, Össur Americas, Siemens, Arthrosurface, DonJoy, Linvatec, HIPCO. Received February 25, 2014; accepted October 3, 2014. Address correspondence to Marc J. Philippon, M.D., Attn: Center for Outcomes-based Orthopaedic Research, Steadman Philippon Research Institute, 181 W Meadow Dr, Ste 1000, Vail, CO 81657, U.S.A. E-mail: [email protected] Ó 2015 by the Arthroscopy Association of North America 0749-8063/14161/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.10.008
454
fundamental precipitators, there is limited information on the potential role of other anatomic variations in FAI.2,3 Historically, alterations in femoral version have been associated with a wide range of hip pathology. Increased and decreased femoral version has been associated with osteoarthritis of the hip. Hip dysplasia has been correlated with increased version, whereas decreased version has been linked to slipped capital femoral epiphysis.4-7 It has been postulated over the past 15 years that decreased or increased femoral version may be a key precipitator of FAI. Several studies have shown that increased and decreased femoral version contributes to FAI. Decreased femoral version has been reported as a predisposing factor in impingement pathomechanics leading to FAI.8,9 Ejnisman et al.3 found that patients with high femoral anteversion (>15 ) are at increased risk of having more anterior labral tears (beyond the 3-o’clock position).
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 31, No 3 (March), 2015: pp 454-459
HIP ARTHROSCOPY OUTCOMES AND FEMORAL VERSION
The soft tissues surrounding the hip joint also influence the development of FAI and affect clinical outcomes of hip arthroscopy. Anatomically, the distal portion of the iliopsoas is in proximity to the acetabular labrum and anterior capsule. The iliopsoas can be a source of impingement without any bony abnormality and is a known cause of labral tears.10 Fabricant et al.11 studied the effect of excessive femoral version in psoas release procedures and reported that increased version (>25 ) correlates with inferior clinical outcomes after arthroscopic psoas lengthening. Specific hip pathology patterns have become evident with cam- and pincer-type impingement. Damage to the anterosuperior area of the acetabular rim is seen with cam impingement. Cam impingement cartilage damage initially presents in a fraying manner, leading to eventual separation from the subchondral bone in a linear fashion at the chondrolabral junction. Pincer impingement results in more pronounced labral degeneration and tearing in a global or circumferential pattern. “Contre-coup” cartilaginous lesions on either the femoral head or the posteroinferior acetabulum are also seen with pincer impingement due to repetitive posterior subluxation of the femoral head.2,3 However, there is limited information regarding whether certain patterns of pathology can be predicted with either excessive or diminished femoral version values. The purpose of this study was to determine whether outcomes after hip arthroscopy were different based on femoral version. Our hypothesis was that excessive femoral version would correlate with poorer clinical outcomes after hip arthroscopy.
Methods A query of a prospective data registry identified all patients who underwent a primary hip arthroscopy between July 2010 and July 2012 at our institution. The study was approved by our institutional review board. The inclusion criteria comprised a diagnosis of FAI based on clinical examination and/or imaging findings and preoperative measurement of femoral version by magnetic resonance imaging. For this study, the definition of FAI was a positive impingement sign, a positive flexioneabductioneexternal rotation examination finding, or radiographic signs of impingement. Patients were included if they had cam impingement, pincer impingement, or mixed impingement. We excluded patients who had a prior hip arthroscopy, were aged younger than 18 years, and had hip dysplasia as defined by a center-edge angle of less than 20 . Patients were divided into 3 groups according to femoral version values. For our study purposes, we designated 5 to 15 as normal femoral version because this is consistent with the majority of the published
455
Fig 1. Oblique sagittal cut of femoral neck. A line is drawn at the center of the femoral neck (line A), and the angle between this line and the horizontal line (line B) is measured (angle 1).
literature.2,7,12,13 Group 1 had version of less than 5 , group 2 had version of 5 to 15 , and group 3 had version greater than 15 . All patients underwent a standard clinical examination. This examination included range-of-motion measurements and provocative tests such as the anterior impingement test (flexioneadductioneinternal rotation), flexioneabductioneexternal rotation test, and hip dial test. Radiographs included an anteroposterior pelvic view, a cross-table lateral view, and a false-profile view. Cam FAI was defined as an anterior femoral head-neck offset (alpha) angle greater than 55 as measured on the cross-table lateral view. Pincer FAI was noted if the medial aspect of the femoral head was medial to the ilioischial line (protrusio acetabuli), if the floor of the acetabulum crossed the ilioischial line (coxa profunda), or if the anterior rim of the acetabulum projected more laterally than the posterior rim proximally (crossover sign) as shown on an anteroposterior pelvic view. A magnetic resonance imaging study was obtained for all patients with a 3-T unit (Magneto Verio 3T; Siemens, Erlangen, Germany). Images were systematically reviewed by an experienced musculoskeletal radiologist (C.P.H.) for the presence of labral tears, chondral lesions, ligamentum teres pathology, and other soft-tissue disorders. Femoral version was measured as described by Tomczak et al.14 The true femoral neck axis was visualized using an oblique axial-sagittal section. The angle between this line and the horizontal reference was called angle 1. At the knee level, angle 2 was then determined between the same horizontal reference and a line that was posteriorly tangential to both femoral condyles. The difference between angles 1 and 2 determined the femoral version (Figs 1 and 2).
456
F. P. FERRO ET AL. Table 1. Preoperative Findings by Version Group Age, yr Center-edge angle, Alpha angle, Internal rotation, External rotation, Positive hip dial test, %
Group 1 33 12 30 5 62 12 26 45 33
Group 2 35 12 30.9 5 64 10 32 45 38
Group 3 35 13 31 6 62 10 38 36 38
P Value NS NS NS .005 .031 NS
NOTE. Data are presented as mean or mean SD unless otherwise indicated. NS, not significant.
of the case, the capsule was closed at the level of the capsulotomy.
Fig 2. Axial cut of knee. A line is drawn tangential to the posterior aspect of the femoral condyles (line C), and the angle between this line and the horizontal line (line B) is measured (angle 2). The difference between angles 1 and 2 equals the femoral version.
This was a retrospective review of data collected prospectively and stored in a data registry. Clinical outcomes were assessed by patient questionnaires administered postoperatively by in person, by mail, or by e-mail and consisted of the Short Form 12, Western Ontario and McMaster Universities Arthritis Index, and modified Harris Hip Score (mHHS). The Short Form 12 is a general physical and mental health status score, whereas the Western Ontario and McMaster Universities Arthritis Index and mHHS are designed specifically for the hip joint and include questions regarding range of motion, pain, and ability to perform different daily activities. Surgical Technique All hip arthroscopies were performed by a single surgeon (M.J.P.) with patients in the modified supine position on a fracture table using anterolateral and midanterior portals, as previously described.15,16 At the time of hip arthroscopy, data were collected on hip pathology and surgical treatment procedures. Information included labral tears with specific emphasis on tear size and location; chondral damage; loose bodies; adhesions; and the condition of the ligamentum teres, capsule, femoral neck, acetabular rim, and iliopsoas. Femoral head-neck osteoplasty was performed for camtype FAI decompression, whereas acetabular rim trimming was executed for pincer-type FAI decompression. Loose bodies and adhesions were removed. At the end
Statistical Analysis The outcome scores used were not normally distributed (P < .05, Kolmogorov-Smirnov test). Scores were compared among groups using the Kruskal-Wallis test. Comparison between normally distributed values (labral tear size, alpha angle, center-edge angle, age, range of motion) was performed with 1-way analysis of variance. Statistical analyses were performed with PASW Statistics software (version 18.0; IBM SPSS, Armonk, NY). With an SD of 15 points for the mHHS, comparing 3 groups with Bonferroni correction, a total of 180 patients would be required to detect a difference of 9 points among groups with 80% power.
Results One hundred eighty patients met the inclusion criteria for this study. There were 48 patients in group 1 (femoral version 15 ). On radiographic examination, the mean alpha angle for all patients’ injured hips was 63 (range, 42 to 88 ). The mean center-edge angle was 30 (range, 20 to 43 ), and mean femoral version was 9.9 (range, 16 to 29 ). There was no significant difference in age, alpha angle, or center-edge angle among the 3 version groups (Table 1). Initial physical examination findings showed a significant difference among the groups for internal rotation. No significant differences were found for external rotation or a positive dial test (Table 1). All hips had labral tears identified at arthroscopy (Table 2). The only intraoperative findings that were different among groups were the location of the labral tear (Fig 3). The prevalence of labral tears beyond the 3-o’clock position (Fig 3B) was significantly greater in group 3 compared with the other groups. There were no differences in procedures performed at arthroscopy except for psoas release. A significant difference in psoas release procedures was seen with increasing femoral version (Table 3).
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HIP ARTHROSCOPY OUTCOMES AND FEMORAL VERSION Table 2. Arthroscopic Findings by Version Group Capsular laxity Chondral lesions Labral tear size, mean SD, mm Anterior/superior labral tears Labral tear beyond 3-o’clock position Ligamentum teres hypertrophy Ligamentum teres partial tear
Table 3. Arthroscopic Treatments by Version Group
Group 1 46% (22) 56% (27) 28 10
Group 2 36% (30) 46% (36) 30 12
Group 3 46% (22) 50% (24) 27 12
P Value NS NS NS
73% (35)
71% (60)
65% (31)
NS
2% (1)
6% (3)
21% (10)
.005
31% (15)
33% (28)
37% (18)
NS
40% (19)
43% (36)
44% (21)
NS
NOTE. Data are presented as percent (number) unless otherwise indicated. NS, not significant.
The mean follow-up period was 30 months (range, 18 to 47 months). No complications were reported at final follow-up. Patient-reported functional outcomes were not statistically different among the groups. Outcome scores are shown in Table 4. For all patients, there was also no difference in outcomes between the patients with and without tears beyond the 3-o’clock position and those with and without psoas release.
Discussion This study showed that patient-centered functional outcomes were not different based on femoral version. Historically, abnormal femoral version has been noted to be a key contributor to prominent hip conditions such as osteoarthritis, hip dysplasia, and slipped capital femoral epiphysis.4-7 With FAI being a relatively new diagnosis, there is corresponding paucity in the literature as to the influence that femoral version has on FAI hip pathology and subsequent hip arthroscopy clinical outcomes. Ganz et al.8 reported that significantly decreased femoral anteversion was seen in patients presenting with FAI. Ejnisman et al.3 reported that hips with femoral version greater than 15 were 2.2 times more likely to have anterior labral tears. They also noted that hips in which a psoas release was performed had higher version angles (8 v 11 , P ¼ .023). Poorer Fig 3. (A) Right hip viewed from anterolateral portal. A labral repair is performed around the 2-o’clock position. (Numbers indicate clock position.) (B) Right hip viewed from anterolateral portal. A labral repair is performed beyond the 3-o’clock position. (Numbers indicate clock position.) Labral tears at this location are often associated with increased femoral version.
Acetabular rim trimming Osteoplasty Rim trim and osteoplasty Acetabular microfracture Femoral head microfracture Labral repair Labral reconstruction Psoas release Ligamentum teres debridement
Group 1 Group 2 Group 3 P Value 2% (1) 5% (4) 4% (2) NS 4% (2) 4% (3) 6% (3) NS 94% (45) 91% (77) 90% (43) NS 27% (13) 19% (16) 6% (10) NS 23% (11) 15% (13) 13% (6) NS 83% 17% 19% 96%
(40) (8) (9) (46)
87% 13% 56% 94%
(73) (11) (27) (79)
86% 14% 50% 96%
(41) (7) (24) (46)
NS NS .005 NS
NOTE. Data are presented as percent (number). NS, not significant.
clinical outcomes were documented by Fabricant et al.11 after an arthroscopic psoas lengthening procedure with increased femoral version values (>25 ). Patients with excessive femoral version reported an mHHS of 76.9 points compared with 86.1 points in patients with femoral version below 25 . Our study looked at patients with femoral version ranging from 16 to 29 , with only 3 patients with version greater than 25 and only 7 patients with version greater than 20 . We were unable to include patients with excessive femoral version because the senior surgeon (M.J.P.) considers this a relative contraindication. In addition, we did not find that those patients with a psoas release had poorer outcomes, but again, we did not have the high version levels that were shown in the study of Fabricant et al. Most previous studies have concentrated on the morphologic differences, biomechanical changes, and pathology patterns due to the femoral version in hip diseases. Studies correlating femoral version with differences in clinical outcomes are minimal. In a recent study, Jackson et al.17 showed that outcomes did not correlate with version. They did, however, show a trend toward higher scores in patients with retroversion (version of 2 or less). Although the results are similar to those of our study, the classification of version was different, with lower degrees of version in the retroversion group and higher degrees of version in the
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Table 4. Outcome Scores by Version Group Follow-up, mo SF-12 PCS, points SF-12 MCS, points WOMAC, points mHHS, points
Group 1 30.8 6 50.1 9 54.9 6 12.5 13 80 15
Group 2 28.9 5 49.8 10 55.4 8 15.4 16 82 15
Group 3 30.3 7 48.8 10 54.8 9 15.8 16 78 16
P Value NS NS NS NS NS
NOTE. Data are presented as mean SD. MCS, mental component summary; mHHS, modified Harris Hip Score; NS, not significant; PCS, physical component summary; SF-12, Short Form 12; WOMAC, Western Ontario and McMaster Universities Arthritis Index.
excessive anteversion group.17 This grouping makes it difficult to compare the 2 studies. In an analysis of revision hip arthroscopy cases, Ricciardi et al.18 found that abnormal version was not more common in revision cases compared with primary hip arthroscopy cases. Their study used computed tomography to measure femoral version and considered retroversion as less than 5 and increased anteversion as greater than 20 . The study did not correlate femoral version with outcome.18 The lack of notable clinical outcome differences associated with increased femoral version values was not expected in our study, especially given the previously established role of abnormal femoral version in other hip conditions such as osteoarthritis. It is still not known whether these differences in femoral version can be implicated in different incidences of arthritis in the long-term, and we acknowledge that further research and a longer follow-up period are necessary to clarify this question. An additional interest of this study was to establish hip pathology patterns that correlate with higher and/ or lower femoral version values. Patients with increased femoral version did exhibit a higher incidence of anterior labral tears. Only 4% of patients with femoral version of less than 5 presented with a labral tear beyond the 3-o’clock position, whereas 21% of patients with femoral version greater than 15 had an anterior labral tear. A significant association between femoral version and internal rotation range of motion was also identified. A decrease in femoral version equated to a decrease in internal rotation. Kelly et al.19 reported a similar correlation between femoral version and internal rotation. This relation highlights the importance of a thorough physical examination because increased internal rotation found during clinical assessment may be a signal of abnormal femoral version. In addition, psoas release procedures were performed at a higher rate in patients with increased femoral version compared with patients with normal or decreased version (27% for group 1 patients v 68% for group 3 patients). We hypothesize that increased femoral version creates a biomechanical condition in which the hip relies more on the psoas tendon for
dynamic anterior stability. This possibly causes this tendon to become tighter, thus conflicting with the anterior labrum, explaining why anterior labral tears are more common in patients with higher version.3,11 Even so, this additional hip pathology did not result in meaningful postoperative clinical outcome differences. Limitations The limitations of this study include the lack of information on acetabular morphology. Because we did not collect these data prospectively, we did not want to add the bias of measuring these data at the final data analysis. Given the null results, the possibility of a type II error is a risk. The primary determinant of this type of risk is the sample size. The sample size of this study may not have been large enough to account for the risk, and this is a limitation. Although we did meet the numbers of our power analysis, we did not have equal distribution among the groups. The lack of difference may also be because of the sensitivity of the outcome measures. We defined the minimum detectable difference as 9 points, which limits the ability to show change using the mHHS. To obtain an overall picture of the patients’ results, we included a general health score, a common disease-specific score, and a hip-specific score. None of the outcome scores were different. Data were limited to a minimum follow-up of 18 months. Longer follow-up is needed to determine whether hip arthroscopy can result in improvement over time regardless of femoral version. The study included no patients with femoral anteversion above 30 . Though not an exclusion criterion for this study, the senior surgeon does consider this a relative contraindication for hip arthroscopy, so data for such patients were not available for the study.
Conclusions Patient-reported functional outcomes after hip arthroscopy for labral tears and FAI were not different based on femoral version in this population. Although some differences were observed regarding intraoperative findings, these also did not result in differences in patient outcomes reported at a mean follow-up of 2 years.
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