Hip Damage Occurs at the Zone of Femoroacetabular Impingement

Background Surgical treatment for pincer femoroacetabular impingement (FAI) of the hip remains controversial, between trimming the prominent acetabular rim and reverse periacetabular osteotomy (PAO) that reorients the acetabulum. However, rim trimming may decrease articular surface size to a critical threshold where increased joint contact forces lead to joint degeneration. Therefore, knowledge of how much acetabular articular cartilage is available for resection is important when evaluating between the two surgical options. In addition, it remains unclear whether the acetabulum rim in pincer FAI is a prominent rim because of increased cartilage size or increased fossa size. Questions/purposes We used reformatted MR and CT data to establish linear length dimensions of the lunate cartilage and cotyloid fossa in normal, dysplastic, and deep acetabula. Methods We reviewed the last 200 hips undergoing PAO, reverse PAO, and surgical dislocation for acetabular rim trimming at one institution. We compared MR images of symptomatic hips with acetabular dysplasia (20 hips), pincer FAI (29 hips), and CT scans of asymptomatic hips from patients who underwent CT scans for reasons other than hip pain (20 hips). These hips were chosen sequentially from the underlying pool of 200 potential subjects to identify the first 10 male and the first 10 female hips in each group that met inclusion criteria. As a result of low numbers, we included all hips that had undergone reverse PAO and met inclusion criteria. Cartilage width was measured medially from the cotyloid fossa to the lateral labrochondral junction. Cotyloid fossa linear height was measured from superior to inferior and cotyloid fossa width was measured from anterior to posterior. Superior lunate cartilage width (SLCW) and cotyloid fossa height (CFH) were measured on MR and CT oblique coronal reformats; anterior lunate cartilage width (ALCW), posterior lunate cartilage width (PLCW), and cotyloid fossa width (CFW) were measured on MR and CT oblique axial reformats. Cohorts were compared using multivariate analysis of variance with Bonferroni's adjustment for multiple comparisons.Results Compared with control acetabula, dysplastic acetabula had smaller SLCW (2.08 ± 0.29 mm versus 2.63 Clinical Orthopaedics and Related Research ®A Publication of The Association of Bone and Joint Surgeons® ± 0.42 mm, mean difference = À0.55 mm; 95% confidence interval [CI] = À0.83 to À0.27; p \ 0.01), ALCW (1.20 ± 0.34 mm versus 1.64 ± 0.21 mm, mean difference = À0.44 mm; 95% CI = À0.70 to À0.18; p = 0.00), CFH (2.84 ± 0.37 mm versus 3.42 ± 0.57 mm, mean difference = À0.59 mm; 95% CI = À0.96 to À0.21; p \ 0.01), and CFW (1.98 ± 0.50 mm versus 2.77 ± 0.33 mm, mean difference = À0.80 mm; 95% CI = À1.16 to À0.42; p \ 0.0001). Based on the results, we identified two subtypes of deep acetabula. Compared with controls, deep subtype 1 had normal CFH and CFW but increased ALCW (2.09 ± 0.42 mm versus 1.64 ± 0.21 mm; p \ 0.001) and PLCW (2.32 ± 0.36 mm versus 2.00 ± 0.32 mm; p = 0.04). Compared ...

Section: Discussionmentioning

confidence: 99%

Is Increased Acetabular Cartilage or Fossa Size Associated With Pincer Femoroacetabular Impingement?

Pun

Hingsammer

Millis

et al. 2017

“…The highest degree of both labral and cartilage damage was assessed using the classification according to Beck et al [2]. To describe the location of labral and cartilage damage, the clock system was used with the acetabulum divided into 12 sectors corresponding to a clock face [39]. Six o'clock was defined as the middle of the incision of the acetabular notch.…”

Section: Methodsmentioning

confidence: 99%

Surgical Hip Dislocation for Treatment of Femoroacetabular Impingement: Factors Predicting 5-year Survivorship

Steppacher

Huemmer

Schwab

et al. 2014

Background Patients with femoroacetabular impingement (FAI) often develop pain, impaired function, and progression of osteoarthritis (OA); this is commonly treated using surgical hip dislocation, femoral neck and acetabular rim osteoplasty, and labral reattachment. However, results with these approaches, in particular risk factors for OA progression and conversion to THA, have varied. Questions/purposes We asked if patients undergoing surgical hip dislocation with labral reattachment to treat FAI experienced (1) improved hip pain and function; and (2) prevention of OA progression; we then determined (3) the survival of the hip at 5-year followup with the end points defined as the need for conversion to THA, progression of OA by at least one Tönnis grade, and/or a Merle d'Aubigné-Postel score less than 15; and calculated (4) factors predicting these end points. Methods Between July 2001 and March 2003, we performed 146 of these procedures in 121 patients. After excluding 35 patients (37 hips) who had prior open surgery and 11 patients (12 hips) who had a diagnosis of Perthes disease, this study evaluated the 75 patients (97 hips, 66% of the procedures we performed during that time) who had a mean followup of 6 years (range, 5-7 years). We used the anterior impingement test to assess pain, the Merle d'Aubigné-Postel score to assess function, and the Tönnis grade to assess OA. Survival and predictive factors were calculated using the method of Kaplan and Meier and Cox regression, respectively. Results The proportion of patients with anterior impingement decreased from 95% to 17% (p \ 0.001); the Merle d'Aubigné-Postel score improved from a mean of 15 to 17 (p \ 0.001). Seven hips (7%) showed progression of OA and another seven hips (7%) converted to THA Survival free from any end point (THA, progression of OA, or a Merle d'Aubigné-Postel \ 15) of well-functioning joints at 5 years was 91%; and excessive acetabular rim trimming, preoperative OA, increased age at operation, and weight were predictive factors for the end points. Conclusions At 5-year followup, 91% of patients with FAI treated with surgical hip dislocation, osteoplasty, and labral reattachment showed no THA, progression of OA, or an insufficient clinical result, but excessive acetabular trimming, OA, increased age, and weight were associated with early failure. To prevent early deterioration of the joint, excessive rim trimming or trimming of borderline dysplastic hips has to be avoided.

“…There is substantial evidence supporting the hypothesis that FAI is a major etiologic factor in the pathophysiology of secondary osteoarthritis of the hip [1,5,6,13,17,18,25,27,[38][39][40]. Specifically, FAI is associated with a pathomechanical hip environment in which there is abnormal, repetitive abutment between the anterolateral femoral head-neck junction and the anterolateral rim of the acetabulum [17,36].…”

Section: Introductionmentioning

confidence: 99%

“…These deformities initiate a cascade of degenerative, intraarticular events including disruption of the labrochondral junction. Chondromalacia and delamination of the peripheral acetabular rim cartilage with adjacent acetabular labral disease are common characteristics in acetabular rim disease [17,38]. As these focal lesions of the acetabular rim complex progress over time, more extensive, nonfocal degenerative disease ensues [5,14].…”

Section: Introductionmentioning

confidence: 99%

Surgical Treatment of Femoroacetabular Impingement: A Systematic Review of the Literature

Clohisy

John

Schutz

2010

267

203

The surgical treatment of femoroacetabular impingement has become more common, yet the strength of clinical evidence to support this surgery is debated. We performed a systematic review of the literature to (1) define the level of evidence regarding hip impingement surgery; (2) determine whether the surgery relieves pain and improves function; (3) identify the complications; and (4) identify modifiable causes of failure (conversion to total hip arthroplasty). We searched the literature between 1950 and 2009 for all studies reporting on surgical treatment of femoroacetabular impingement. Studies with clinical outcome data and minimum two year followup were analyzed. Eleven studies met our criteria for inclusion. Nine were Level IV and two were Level III. Mean followup was 3.2 years; range (2-5.2 years). Reduced pain and improvement in hip function were reported in all studies. Conversion to THA was reported in 0% to 26% of cases. Major complications occurred in 0% to 18% of the procedures. Current evidence regarding femoroacetabular impingement surgery is primarily Level IV and suggests the various surgical techniques are associated with pain relief and improved function in 68-96% of patients over short-term followup. Long-term followup is needed to determine survivorship and impact on osteoarthritis progression and natural history.