Radiographic analysis of femoroacetabular impingement with Hip 2 norm—reliable and validated

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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.

Section: Methodsmentioning

confidence: 99%

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

Steppacher

Huemmer

Schwab

et al. 2014

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“…One observer (SDS) analyzed the individual acetabular morphologic features using validated computer software, Hip 2 Norm (University of Bern, Switzerland) [24,32]. The descriptive parameters were the LCE angle [30], acetabular [11].…”

Section: Patients and Materialsmentioning

confidence: 99%

“…The width (b) was measured perpendicular to the thickness (a). index [28], extrusion index [19], and femoral head coverage [24,25] (Table 1).…”

Section: Patients and Materialsmentioning

confidence: 99%

The Iliocapsularis Muscle: An Important Stabilizer in the Dysplastic Hip

Babst

Steppacher

Ganz

et al. 2011

111

155

Background The iliocapsularis muscle is a little known muscle overlying the anterior hip capsule postulated to function as a stabilizer of dysplastic hips. Theoretically, this muscle would be hypertrophied in dysplastic hips and, conversely, atrophied in stable and well-constrained hips. However, these observations have not been confirmed and the true function of this muscle remains unknown. Questions/purposes We quantified the anatomic dimensions and degree of fatty infiltration of the iliocapsularis muscle and compared the results for 45 hips with deficient acetabular coverage (Group I) with 40 hips with excessive acetabular coverage (Group II). Patients and Methods We used MR arthrography to evaluate anatomic dimensions (thickness, width, circumference, cross-sectional area [CSA], and partial volume) and the amount of fatty infiltration.

“…Some authors have reported on reliability and agreement of measures used in radiographic evaluation of the adult hip [2,9,16,28]. In these studies, the interobserver reliability was lower than the intraobserver reproducibility, and the ICC/kappa values for the parameters were various.…”

Section: Discussionmentioning

confidence: 99%

New Radiographic Index for Evaluating Acetabular Version

Koyama

Hoshino

Suzuki

et al. 2013

Background Several qualitative radiographic signs have been described to assess acetabular retroversion. However, quantitative assessment of acetabular version would be useful for more rigorous research purposes and perhaps to diagnose and treat hip disorders. Questions/purposes We developed a new quantitative index for acetabular version (p/a ratio). We determined the average p/a, compared it with previous radiographic signs for acetabular retroversion, and evaluated its relationship with anatomic acetabular version. Methods We calculated the p/a ratio by measuring p (distance from acetabular articular surface to posterior wall) and a (distance from acetabular articular surface to anterior wall) on plain hip AP radiographs and dividing p by a. P and a were assessed on the perpendicular bisector of the line between the teardrop and the lateral edge of the acetabulum. Using 185 hip radiographs from patients with suspected idiopathic osteonecrosis, we measured p/a and compared it with previous qualitative signs for acetabular retroversion. Using 62 hip CT images from patients with no osteoarthritis, we measured the anatomic anteversion at the height of the central femoral head and investigated its relationship with p/a. Results The average p/a was 2.05 in 185 hips, and most patients with a p/a greater than 2.05 had a negative qualitative retroversion sign. A correlation was observed between central anteversion and p/a (r = 0.84). Conclusions We believe this ratio can be considered a simple quantitative parameter to assess acetabular version using plain AP radiographs.