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Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients With Borderline Hip Dysplasia Danyal H. Nawabi, Ryan M. Degen, Kara G. Fields, Alexander McLawhorn, Anil S. Ranawat, Ernest L. Sink and Bryan T. Kelly Am J Sports Med published online February 1, 2016 DOI: 10.1177/0363546515624682 The online version of this article can be found at: http://ajs.sagepub.com/content/early/2016/01/29/0363546515624682

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Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients With Borderline Hip Dysplasia Danyal H. Nawabi,* MD, FRCS(Orth), Ryan M. Degen,*y MD, MSc, FRCSC, Kara G. Fields,* MS, Alexander McLawhorn,* MD, Anil S. Ranawat,* MD, Ernest L. Sink,* MD, and Bryan T. Kelly,* MD Investigation performed at the Hospital for Special Surgery, New York, New York, USA Background: The outcomes of hip arthroscopy in the treatment of dysplasia are variable. Historically, arthroscopic treatment of severe dysplasia (lateral center-edge angle [LCEA] \18°) resulted in poor outcomes and iatrogenic instability. However, in milder forms of dysplasia, favorable outcomes have been reported. Purpose: To compare outcomes after hip arthroscopy for femoroacetabular impingement (FAI) in borderline dysplastic (BD) patients compared with a control group of nondysplastic patients. Study Design: Cohort study; Level of evidence, 3 Methods: Between March 2009 and July 2012, a BD group (LCEA, 18°-25°) of 46 patients (55 hips) was identified. An age- and sex-matched control group of 131 patients (152 hips) was also identified (LCEA, 25°-40°). Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), the Hip Outcome Score–Activities of Daily Living (HOS-ADL) and Sport-Specific Subscale (HOS-SSS), and the International Hip Outcome Tool (iHOT-33), were collected preoperatively and at 1 and 2 years postoperatively. Results: The mean LCEA was 22.4° 6 2.0° (range, 18.4°-24.9°) in the BD group and 31.0° 6 3.1° (range, 25.4°-38.7°) in the control group (P \ .001). The mean preoperative alpha angle was 66.3° 6 9.9° in the BD group and 61.7° 6 13.0° in the control group (P = .151). Cam decompression was performed in 98.2% and 99.3% of cases in the BD and control groups, respectively; labral repair was performed in 69.1% and 75.3% of the BD and control groups, respectively, with 100% of patients having a complete capsular closure performed in both groups. At a mean follow-up of 31.3 6 7.6 months (range, 23.1-67.3 months) in unrevised patients and 21.6 6 13.3 months (range, 4.7-40.6 months) in revised patients, there was significant improvement (P \ .001) in all patient-reported outcome scores in both groups. Multiple regression analysis did not identify any significant differences between groups. Importantly, female sex did not appear to be a predictor for inferior outcomes. Two patients (4.3%) in the BD group and 6 patients (4.6%) in the control group required revision arthroscopy during the study period. Conclusion: Favorable outcomes can be expected after the treatment of impingement in patients with borderline dysplasia when labral refixation and capsular closure are performed, with comparable outcomes to nondysplastic patients. Further follow-up in larger cohorts is necessary to prove the durability and safety of hip arthroscopy in this challenging group and to further explore potential sex-related differences in outcome. Keywords: hip arthroscopy; dysplasia; femoroacetabular impingement; outcomes

The use of hip arthroscopy in the treatment of nonarthritic hip pain has increased significantly in recent years. Along

with this has come an improved understanding of the pathomechanical processes of femoroacetabular impingement (FAI) that contributes to intra-articular hip injury.2,26,28 Numerous studies have demonstrated positive results after hip arthroscopy for the treatment of FAI and associated labral lesions, with improved patient-reported outcomes and the purported benefit of preventing further joint degeneration and secondary osteoarthritis.1,17,24 However, the utility of hip arthroscopy in the treatment of FAI and associated intra-articular lesions among those with concomitant hip dysplasia is less clear. Hip dysplasia is largely defined by radiographic parameters, including an elevated To¨nnis angle (or acetabular inclination) .10°, increased femoral anteversion, a decreased anterior center-edge angle (ACEA) \20°, and a decreased

y Address correspondence to Ryan M. Degen, MD, MSc, FRCSC, Hospital for Special Surgery, 525 East 70th Street, New York, NY 10021, USA (email: [email protected]). *Center for Hip Preservation, Hospital for Special Surgery, New York, New York, USA. Presented at the 41st annual meeting of the AOSSM, Orlando, Florida, July 2015. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.

The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546515624682 Ó 2016 The Author(s)

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lateral center-edge angle (LCEA) \25°.6,16,21 The LCEA is frequently used to screen for dysplasia when reviewing standard anteroposterior (AP) radiographs. This measurement has been further substratified, with severe dysplasia represented by an LCEA \18° and borderline dysplasia (BD) represented with an LCEA .18° but \25°. As a result of the deficient bony coverage of the femoral head, increased load is transmitted to the surrounding soft tissues, including the labrum and capsule, leading to hypertrophy of these structures as they are recruited as secondary stabilizers of the hip. Biomechanical studies have demonstrated increased loads in the labrum, with up to 4% to 11% of body weight transmitted to the labrum during simulated weightbearing, compared with only 1% to 2% in a congruent hip.10 This increased load, combined with the resultant shearing force of the femoral head produced by the increased acetabular index and deficient superolateral coverage, results in increased stress on the capsulolabral complex and the development of subsequent labral tears, present in up to 70% to 90% of patients with acetabular dysplasia.9,26,32 In addition, the presence of a cam lesion, resulting in femoroacetabular impingement, may also contribute to the development of labral tears in these dysplastic patients. Severe dysplasia (LCEA \18°) has been primarily managed with acetabular reorientation surgeries, including the periacetabular osteotomy (PAO).7 With increasing awareness of the associated intra-articular injuries contributing to symptomatology, as well as the occurrence of surgical overcorrection resulting in secondary impingement, PAO has often been combined with hip arthroscopy for management of these injuries with good success.13,22,23,28 For patients with borderline dysplasia, a PAO has been less favorable due to the invasiveness of the procedure and the potential for associated complications.8,33 However, early results for treating symptomatic borderline dysplasia with arthroscopy to manage labral pathologic changes were discouraging, with failure rates as high as 71% and reported cases of iatrogenic instability and accelerated osteoarthritis.18,19,26 As a result, the procedure was abandoned by some and used sparingly by others in those with borderline dysplasia. Most of these preliminary studies focused on the management of symptomatic, degenerative labral tears secondary to acetabular dysplasia. Treatment primarily involved labral debridement as labral repair techniques were inadequately developed at that stage.5,26 As surgical techniques have improved in recent years with improved methods of labral repair, this topic was revisited with more recent studies demonstrating favorable results, particularly when labral repair and capsular closure were routinely performed, although these results have continued to focus primarily on patients with instability or pain secondary to degenerative labral lesions.4,8,14 At present, there is a paucity of data on the outcomes of patients with radiographic features of borderline dysplasia who have symptomatic hip impingement. The purpose of this study was to review outcomes after hip arthroscopy in a cohort of borderline dysplastic patients for the treatment of symptomatic femoroacetabular impingement. These results were compared with those of a control

cohort of nondysplastic patients who also underwent arthroscopy for FAI, with a focus on patient-reported outcome measures and reoperation rates.

METHODS All patients undergoing hip arthroscopy at our institution are prospectively enrolled in an institutional review board– approved hip preservation registry after informed consent. Within the registry, patient demographic variables and accompanying surgical and clinical data are collected. Patient-reported outcome scores are also collected at each major follow-up appointment, including the modified Harris Hip Score (mHHS), the Hip Outcome Score–Activities of Daily Living (HOS-ADL) and the Sport-Specific Subscale (HOS-SSS), and the International Hip Outcome Tool (iHOT-33). Between March 2009 and July 2012, all patients undergoing primary hip arthroscopy for femoroacetabular impingement with BD with an LCEA 18° and 25° (46 patients, 55 hips) were identified and included in this study. No patients meeting these criteria were excluded. An age- and sex-matched control group was identified from our hip arthroscopy registry over the same time period, ensuring control patients had normal acetabular structure, with an LCEA .25° and 40° (131 patients, 152 hips).

Clinical Evaluation All patients were carefully evaluated, including a detailed history of provocative and painful activities to determine if their presentation was consistent with symptoms of impingement rather than symptoms of instability. They were subsequently examined, including a detailed range of motion and strength evaluation. Further special tests were conducted to confirm the presence of symptoms of impingement, while ruling out any concomitant findings of instability. Impingement was confirmed with pain provocation in flexion/adduction/internal rotation (anterior impingement) or in terminal flexion beyond 90° (subspine impingement11). Instability was ruled out with an absence of anterior groin pain with abduction, extension, and external rotation, as well as with an absence of excessive external rotation range of motion.31 No patients in the control group demonstrated findings of instability, corroborated with intraoperative data as there were no capsular plications performed in this group. Radiographic evaluation included a standing AP pelvis and 90° Dunn lateral radiographs. The AP radiographs were evaluated for the LCEA and To¨nnis angle, while the Dunn lateral was used to determine the alpha angle and maximal head-neck offset. Magnetic resonance imaging (MRI) scans were obtained to assess for potential labral pathologic abnormalities and chondral delamination. Computed tomography (CT) scans, along with 3-dimensional (3D) reformatted images, were obtained to better quantify and localize the regions of bony impingement, specifically focusing on cam location, acetabular version, and femoral version.

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Surgical Technique All patients underwent hip arthroscopy in the modified supine position on a traction table using regional anesthesia. With use of fluoroscopic guidance, access to the joint was obtained via the anterolateral and midanterior portals. An interportal capsulotomy was created between these portals using an arthroscopic scalpel. Pathologic abnormalities were addressed in a sequential manner, starting in the central compartment and moving to the peripheral compartment based on preoperative imaging and on the results of the diagnostic arthroscopy. Rim lesions, including subspine impingement, were carefully resected under fluoroscopic guidance to avoid further reduction in acetabular coverage. The labrum was assessed and an additional distal anterolateral portal was added for percutaneous anchor insertion along the acetabular rim in cases requiring labral repair or refixation using suture anchors (NanoTack; Pivot Medical, Inc). Most patients in both the BD and control groups had cam lesions (98.2% vs 99.3%), for which a T-capsulotomy was performed to access the peripheral compartment to perform the femoral osteoplasty. After lesions in the central and peripheral compartment were addressed, complete capsular closure of both the T-cut and interportal cut was performed in all cases using a suture-passing device (Nanopass; Pivot Medical, Inc) with approximately 5 to 6 high-strength sutures (Orthocord; Mitek Sports Medicine).

Statistical Analysis Continuous variables were compared between BD and control patients using independent-samples t tests, and categorical variables were compared between groups using chi-square or Fisher exact tests, as appropriate. Exploratory subgroup analyses compared measurements between female and male patients separately within the BD and control groups using the same methods. The statistical significance of changes in patient-reported outcome scores pre- to at least 24 months postoperatively was assessed via paired t tests. Change in outcome scores pre- to at least 24 months postoperatively, as well as the odds of experiencing a poor outcome (defined as the minimal important change [MIC] not achieved and/or last score \70 and/or hip revised), was compared between BD and control patients after adjustment for age, sex, preoperative alpha angle, bilateral surgery, and preoperative score using multiple linear and logistic regression, respectively.

RESULTS Between March 2009 and July 2012, a total of 1107 patients (1319 hips) undergoing primary unilateral or bilateral hip arthroscopy for symptomatic intra-articular hip disorders were prospectively enrolled into a hip preservation registry. From this cohort, a BD group composed of 46 patients (55 hips) with an LCEA 18° and 25° and a minimum of 24 months of follow-up was identified. Overall, this BD cohort comprised 4.1% of the patients enrolled

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in our registry over that time period. A control group of 131 patients (152 hips) with an LCEA .25° and 40° and a minimum of 23 months of follow-up was subsequently identified. Patients with LCEA \18° or reoperation for traumatic injuries were excluded. Outcome scores obtained preoperatively and at 6 months, 1 year, and 2 years postoperatively were reviewed. Demographics were similar between groups in terms of sex and age distribution. Patients in the BD group had a mean LCEA of 22.4° 6 2.0° and To¨nnis angle of 6.3° 6 3.1°, compared with the control group with a mean LCEA of 31.0° 6 3.1° and To¨nnis angle of 2.2° 6 3.4° (P \ .001 for both) (Table 1). Further subgroup analysis revealed a higher alpha angle among male patients in both cohorts (BD: 62.5° 6 9.4° vs 69.8° 6 9.2°, P = .005; control: 56.8° 6 13.3° vs 67.8° 6 9.7°, P \ .001) and greater acetabular retroversion in male patients in the control cohort at 2 o’clock (7.1° 6 9.2° vs 11.0° 6 8.9°; P = .026) and 3 o’clock (13.2° 6 6.4° vs 16.7° 6 6.1°; P = .002). Clinical range of motion both preoperatively and postoperatively did not reveal any statistically significant differences between groups (P  .054) (Table 2). Intraoperative findings were also similar between groups, with equivalent rates of most performed procedures, including cam and rim/subspine decompressions (Table 3). Labral repair was performed in most cases in both groups (BD: 69.1%, control: 75.7%; P = .531), while capsular closure was also performed in all cases in both groups. There was a higher proportion of ligamentum teres debridement in the BD group compared with the control group (23.6% vs 5.9%; P \ .001). There were no associated perioperative complications in either group. At a mean follow-up of 31.3 6 7.6 months (range, 23.167.3 months) in unrevised patients and 21.6 6 13.3 months (range, 4.7-40.6 months) in revised patients, there was significant improvement (P \ .001) in all patient-reported outcome measures (mHSS, HOS-ADL, HOS-SSS, and iHOT-33). There was no evidence of a difference between groups with respect to preoperative and postoperative survey scores. Furthermore, there was no evidence of a difference between groups in preoperative to postoperative score change or odds of experiencing a poor outcome (defined as MIC not achieved and/or last score \70 and/or hip revised), either unadjusted or adjusted for age, sex, alpha angle, bilateral versus unilateral, and preoperative score via multiple linear and logistic regression, respectively (Table 4). A subsequent comparative analysis was performed between patients within the BD group who underwent either labral repair or debridement, revealing no statistically significant differences in preoperative or postoperative clinical outcome scores (Table 5). Revision surgery was required for 2 patients (4.3%) in the BD group at 9.6 and 23.8 months after their index procedures. One of these patients had revision surgery because of painful postoperative adhesions, undergoing revision hip arthroscopy for release of these adhesions. The second patient required revision surgery for a recurrent labral tear with residual impingement, treated with arthroscopic debridement and labral repair. Six patients (4.6%) in the control group also required revision hip arthroscopy 5.8 to

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TABLE 1 Demographics and Radiographic Parametersa Borderline Dysplasia (n = 46)

Control (n = 131)

P Value

29.8 6 9.4

29.6 6 10.3

.876

22 24 9 2 22.4 6.3 66.3 13.9

73 58 21 6 31 2.2 61.7 14.9

.355

Age, y Sex, n Female Male Bilateral cases, n Patients requiring revision surgery, n LCEA (radiograph), deg To¨nnis angle (radiograph), deg Alpha angle (CT), deg Femoral version (CT), deg Acetabular version (CT), deg At 1 o’clock At 2 o’clock At 3 o’clock

6 6 6 6

2 3.1 9.9 9.6

3 6 7.6 10.1 6 7.6 15.7 6 6.5

6 6 6 6

3.1 3.4 13 10.2

0.9 6 8.9 9.2 6 9.2 15.1 6 6.4

.104 .746 \.001b \.001b .151 .557 .145 .594 .575

a

Data are reported as mean 6 SD unless otherwise indicated. CT, computed tomography; LCEA, lateral center-edge angle. Statistically significant difference between groups (P \ .05).

b

TABLE 2 Range of Motion Pre- and Postoperativelya Borderline Dysplasia Hip flexion Preoperative 108.1 6 7.3 Postoperative 105.9 6 5.3 External rotation Preoperative 41.9 6 5.8 Postoperative 42.2 6 3.6 Internal rotation at 90° of flexion Preoperative 14 6 11.6 Postoperative 25.4 6 4.9

Control

P Value

107 6 9.9 104.5 6 5.7

.492 .316

43 6 10.2 44.2 6 6.9

.473 .073

13.5 6 11.9 27.5 6 4.6

.819 .054

a

Data are reported in degrees as mean 6 SD.

37.3 months after their index procedure. Of these 6, 2 underwent revision arthroscopy for heterotopic ossification an additional 2 for recurrent labral tears requiring refixation and removal of loose bodies, one for residual impingement requiring debridement and a gluteus medius tear that was repaired endoscopically and, finally, one for residual impingement with capsular laxity from an unrepaired interportal capsulotomy that was treated with debridement and capsular repair.

DISCUSSION As outlined earlier, the treatment of symptomatic impingement among patients with borderline acetabular dysplasia has not been well defined. Unlike severe acetabular dysplasia (LCEA \18°), BD differs since the degree of acetabular deficiency may not warrant a reorienting osteotomy, as instability is often not their primary complaint.15,25 Conversely, patients may have concomitant symptoms and radiographic evidence of femoroacetabular impingement. A reorienting osteotomy in that setting may

exacerbate their impingement, especially given the noted risk of secondary impingement or overcoverage associated with periacetabular osteotomies and the resultantly poor outcomes associated with this.22,23,30 Nevertheless, the relative deficiency in their osseous structures confers similar load transfer to secondary soft tissue stabilizers, frequently resulting in labral lesions.9,20 Often, these labral injuries are responsible for patient presentation and have been the sole focus of treatment among patients with BD, while potentially overlooking concomitant FAI. Arthroscopy was adopted for management of these labral injuries, but early arthroscopic results yielded high failure rates with incomplete pain relief, with additional concerns that the procedure resulted in progressive osteoarthritis or exacerbation of symptoms of instability.3,13,19 Parvizi et al26 reported on a series of 34 patients with symptomatic acetabular dysplasia who underwent hip arthroscopy for management of a labral tear. They had 24 patients go on to failure with inadequate pain relief, with 14 of those patients experiencing accelerated osteoarthritis, suggesting that patients with dysplasia may not benefit from hip arthroscopy and isolated labral treatment. In addition, 16 patients required subsequent procedures. Similarly, Kalore and Jiranek14 also reported on a subgroup of patients within their study who underwent hip arthroscopy for labral pathologic abnormalities with borderline acetabular dysplasia. They, too, found higher rates of failure resulting in reoperation among those with borderline acetabular dysplasia compared with those with adequate acetabular coverage (30% vs 14.2%; P = .04). These studies as well as others19,27 have contributed to concerns regarding the use of hip arthroscopy in the presence of dysplasia. However, in both of these studies, the primary method of managing these labral tears was with labral debridement, which likely introduced a component of iatrogenic instability by disrupting the suction-seal effect that contributed to their mechanism of failure. Studies have demonstrated the importance of the labrum as

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TABLE 3 Number of Procedures Performed During Arthroscopy Borderline Dysplasia (n = 55)

Control (n = 152)

P Value

54 14 15 0 35 5 25 10 40 13 55 3 17 38

151 23 60 0 105 24 68 36 128 9 152 1 34 115

.462 .087 .107 ..999 .46 .220 .927 .4 .079 \.001 ..999 .058 .531 .531

Cam decompression Isolated cam decompression Rim decompression Isolated rim decompression Subspine decompression Cam and rim decompression only Cam and subspine decompression only Cam, rim, and subspine decompression Osteochondroplasty Ligamentum teres debridement Capsular closure Capsular shift Labral debridement Labral repair

TABLE 4 Patient-Reported Outcome Measuresa

mHHS score Preoperative Postoperative HOS-ADL score Preoperative Postoperative HOS-SSS score Preoperative Postoperative iHOT-33 score Preoperative Postoperative

Borderline Dysplasia

Control

P Value

61.7 6 10.9 (n = 42) 86.2 6 14.6

63.3 6 13 (n = 118) 84.7 6 16.5

.479

76 6 14.4 (n = 45) 93.2 6 11.3

74.5 6 17 (n = 125) 90.7 6 13.3

.606

54.6 6 23 (n = 44) 85.4 6 22.1

53.3 6 23.7 (n = 120) 78.78 6 25.2

.751

44.4 6 15.4 (n = 28) 80 6 23.1

40.2 6 17.4 (n = 85) 75.1 6 25.2

.259

.604

.269

.125

.362

a

HOS-ADL, Hip Outcome Score–Activities of Daily Living; HOS-SSS, Hip Outcome Score–Sport-Specific Subscale; iHOT-33, International Hip Outcome Tool; mHHS, modified Harris Hip Score.

a secondary stabilizer of the hip, while also serving as a load-bearing structure in the presence of dysplasia, so it is conceivable that resection may contribute to both instability and degeneration of the joint. As a result, hip arthroscopy may have been unjustly blamed for failure in these dysplastic patients, where labral resection should have rather been the focus. In our study, the same deleterious outcomes were not identified with labral debridement as we used a minimalistic approach, resecting only unstable portions with an emphasis on preservation of labral tissue. In contrast, Byrd and Jones4 reported on a series of 48 patients with either severe (16 patients) or borderline dysplasia (32 patients) who underwent arthroscopy for the management of labral injuries. They reported significant improvements in Harris Hip Score results between

TABLE 5 Patient-Reported Outcome Measures in Patients With Borderline Dysplasia Who Underwent Labral Repair or Debridementa

mHHS score Preoperative Postoperative HOS-ADL score Preoperative Postoperative HOS-SSS score Preoperative Postoperative iHOT-33 score Preoperative Postoperative

Repair

Debridement

P Value

62.4 6 10.8 (n = 29) 87.7 6 13.7

59.7 6 11.1 (n = 13) 84.7 6 14.4

.463

75.7 6 13.8 (n = 30) 93.1 6 12.8

76.1 6 14.8 (n = 14) 94.8 6 7.1

.927

52.8 6 22.3 (n = 29) 85.3 6 24.1

55.8 6 22.3 (n = 14) 86.1 6 18.5

.686

46.4 6 14.9 (n = 17) 80.4 6 24.4

38.6 6 14.3 (n = 8) 77.6 6 22.5

.197

.528

.579

.927

.764

a HOS-ADL, Hip Outcome Score–Activities of Daily Living; HOS-SSS, Hip Outcome Score–Sport-Specific Subscale; iHOT-33, International Hip Outcome Tool; mHHS, modified Harris Hip Score.

preoperative and postoperative assessments for all patients in both the severely dysplastic and borderline dysplastic groups, with 38 patients demonstrating at least a 10-point improvement. Only 2 of their patients required conversion to total hip arthroplasty. They attribute their success rates to careful surgical technique with minimal labral debridement and preservation of all healthy labral tissue. They conclude that dysplasia itself is not a negative prognostic factor but rather that the intra-articular injury and the method of treatment dictate outcome. Similarly, Domb et al8 also investigated the efficacy of hip arthroscopy in the treatment of labral lesions among patients with BD. They treated labral injuries with preservation and repair, while adding a capsular plication during their

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repair of the interportal capsulotomy to reduce potential iatrogenic symptoms of instability. They also identified significant improvements in patient-reported outcome measures (mHHS, NAHS, HOS-SSS, and HOS-ADL) and overall patient satisfaction. Two of their patients underwent revision hip arthroscopy during the course of the study. They concluded that patients with dysplasia may benefit from arthroscopy with an approach that includes labral repair and a capsular shift. These studies highlight the potential utility for hip arthroscopy in the treatment of BD. Similar to these studies, we attempted to further define a role for hip arthroscopy among patients with BD, but we focused on a subgroup within that population of patients with radiographic evidence of dysplasia who have clinical symptoms and concomitant radiographic findings of femoroacetabular impingement, including elevated alpha angles. Prevalence studies among patients with acetabular dysplasia have identified that concomitant FAI is common, with rates of nearly 40%.12 In addition to reviewing the results of these patients, we compared them with an age-matched control cohort with femoroacetabular impingement to determine if BD had any prognostic effect on patient-reported outcomes. Our results demonstrate significant improvement in all patient-reported outcome measures after arthroscopic osteochondroplasty for FAI with associated labral repair and capsular closure in the treatment of symptomatic impingement in patients with BD. These results equated those of nondysplastic patients treated for impingement with similar procedures at a mean follow-up of 33 months. Similar to the reoperation rates of the previously mentioned studies, 2 patients in the BD group required revision hip arthroscopy, and 6 patients in the control cohort required revision hip arthroscopy. The results of this study are unique in that they present outcomes for a presently unrecognized patient population, while also comparing these patients to an FAI control cohort. As there were no significant trends or findings to suggest inferior outcomes among patients with dysplasia, we believe that hip arthroscopy is supported for symptomatic FAI treatment in BD with careful attention to labral refixation, where feasible, and capsular repair after osteochondroplasty. While capsular plication has been demonstrated to have a role in treating instability among patients with dysplasia, we do not believe it is routinely required in all arthroscopic procedures for patients with radiographic features of dysplasia as inferior results were not identified in our cohort.8,29 Without clinical findings of instability, capsular plication performed routinely in hips with BD and impingement may counteract the motion restored by treating their impingement and should be cautiously used. However, routine capsular closure, not plication, is strongly recommended. Limitations of our study include the use of a seemingly small sample size for the dysplasia group treated with arthroscopy. This could potentially limit the results of our regression analysis, specifically looking at the effect that patient sex may have had on outcomes in each group. However, despite this, we believe that this is a relatively uncommon clinical scenario, and this cohort size is consistent with other studies reporting outcomes after arthroscopy in

dysplastic patients. In addition, follow-up was limited to a mean of 33 months, and this may limit the ability to assess whether the treatment effect is maintained going forward. Longitudinal follow-up is necessary to determine the durability of the procedure and if reoperation is required. Strengths of our study include that it is the first such study to report on this unique patient population of dysplastic hips with impingement. In addition, to our knowledge, this is the first study to compare arthroscopic outcomes among dysplasia patients with a matched control cohort to better delineate any potential prognostic effects.

CONCLUSION While we recommend caution in treating hip dysplasia using hip arthroscopy, our results indicate that in patients with clinical and radiographic evidence of FAI along with BD, favorable outcomes can be expected after cam or rim decompression when a careful approach of labral refixation and capsular closure is employed. These outcomes are similar to those of nondysplastic patients undergoing hip arthroscopy at a mean 33-month follow-up. Careful clinical examination is paramount to correctly identifying this subset of patients, to avoid the potential catastrophic failures previously reported after arthroscopic treatment in dysplasia. Further follow-up in larger cohorts is necessary to prove the durability and safety of hip arthroscopy in this challenging group and to identify any potential sex-associated differences in outcome. REFERENCES 1. Bedi A, Chen N, Robertson W, Kelly BT. The management of labral tears and femoroacetabular impingement of the hip in the young, active patient. Arthroscopy. 2008;24(10):1135-1145. 2. Bedi A, Kelly BT. Femoroacetabular impingement. J Bone Joint Surg Am. 2013;95(1):82-92. 3. Benali Y, Katthagen BD. Hip subluxation as a complication of arthroscopic debridement. Arthroscopy. 2009;25(4):405-407. 4. Byrd JWT, Jones KS. Hip arthroscopy in the presence of dysplasia. Arthroscopy. 2003;19(10):1055-1060. 5. Byrd JWT, Jones KS. Prospective analysis of hip arthroscopy with 10-year followup. Clin Orthop Relat Res. 2010;468(3):741-746. 6. Clohisy JC, Carlisle JC, Beaule´ PE, et al. A systematic approach to the plain radiographic evaluation of the young adult hip. J Bone Joint Surg Am. 2008;90(suppl 4):47-66. 7. Coobs BR, Xiong A, Clohisy JC. Contemporary concepts in the young adult hip patient: periacetabular osteotomy for hip dysplasia. J Arthroplasty. 2015;30(7):1105-1108. 8. Domb BG, Stake CE, Lindner D, El-Bitar Y, Jackson TJ. Arthroscopic capsular plication and labral preservation in borderline hip dysplasia: two-year clinical outcomes of a surgical approach to a challenging problem. Am J Sports Med. 2013;41(11):2591-2598. 9. Hartig-Andreasen C, Søballe K, Troelsen A. The role of the acetabular labrum in hip dysplasia: a literature overview. Acta Orthop. 2013; 84(1):60-64. 10. Henak CR, Ellis BJ, Harris MD, Anderson AE, Peters CL, Weiss JA. Role of the acetabular labrum in load support across the hip joint. J Biomech. 2011;44(12):2201-2206. 11. Hetsroni I, Larson CM, Dela Torre K, Zbeda RM, Magennis E, Kelly BT. Anterior inferior iliac spine deformity as an extra-articular source for hip impingement: a series of 10 patients treated with arthroscopic decompression. Arthroscopy. 2012;28(11):1644-1653.

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AJSM Vol. XX, No. X, XXXX

Treatment of FAI in Borderline Dysplasia

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Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients With Borderline Hip Dysplasia.

The outcomes of hip arthroscopy in the treatment of dysplasia are variable. Historically, arthroscopic treatment of severe dysplasia (lateral center-e...
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