Femoral Morphology Differs Between Deficient and Excessive Acetabular Coverage

107

Background The iliocapsularis muscle is an anterior hip structure that appears to function as a stabilizer in normal hips. Previous studies have shown that the iliocapsularis is hypertrophied in developmental dysplasia of the hip (DDH). An easy MR-based measurement of the ratio of the size of the iliocapsularis to that of adjacent anatomical structures such as the rectus femoris muscle might be helpful in everyday clinical use. Questions/purposes We asked (1) whether the iliocapsularis-to-rectus-femoris ratio for cross-sectional area, thickness, width, and circumference is increased in DDH when compared with hips with acetabular overcoverage or normal hips; and (2) what is the diagnostic performance of these ratios to distinguish dysplastic from pincer hips? Methods We retrospectively compared the anatomy of the iliocapsularis muscle between two study groups with symptomatic hips with different acetabular coverage and a control group with asymptomatic hips. The study groups were selected from a series of patients seen at the outpatient clinic for DDH or femoroacetabular impingement. The allocation to a study group was based on conventional radiographs: the dysplasia group was defined by a lateral center-edge (LCE) angle of \ 25°with a minimal acetabular index of 14°and consisted of 45 patients (45 hips); the pincer group was defined by an LCE angle exceeding 39°and consisted of 37 patients (40 hips). The control group consisted of 30 asymptomatic hips (26 patients) with MRIs performed for nonorthopaedic reasons. The anatomy of the iliocapsularis and rectus femoris muscle was evaluated using MR arthrography of the hip and the following parameters: crosssectional area, thickness, width, and circumference. The iliocapsularis-to-rectus-femoris ratio of these four anatomical parameters was then compared between the two study groups and the control group. The diagnostic performance of these ratios to distinguish dysplasia from protrusio was evaluated by calculating receiver operating characteristic (ROC) curves and the positive predictive value (PPV) for a ratio [ 1. Presence and absence of DDH (ground truth) were determined on plain radiographs using the previously mentioned radiographic parameters. Evaluation of radiographs and MRIs was performed in a blinded fashion. The PPV was chosen because it indicates how likely a hip is dysplastic if the iliocapsularis-to-rectus-femoris ratio was [ 1.Results The iliocapsularis-to-rectus-femoris ratio for cross-sectional area, thickness, width, and circumference was increased in hips with radiographic evidence of DDH (ratios ranging from 1.31 to 1.35) compared with pincer (ratios ranging from 0.71 to 0.90; p \ 0.001) and compared with the control group, the ratio of cross-sectional area, thickness, width, and circumference was increased (ratios ranging from 1.10 to 1.15; p ranging from 0.002 to 0.039). The area under the ROC curve ranged from 0.781 to 0.852. For a one-to-one iliocapsularis-to-rectus-femoris ratio, the PPV was 89% (95% confidence interval [CI], 73%-96%)...

Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 95%

An Increased Iliocapsularis-to-rectus-femoris Ratio Is Suggestive for Instability in Borderline Hips

Haefeli

Steppacher

Babst

et al. 2015

107

“…3); however, care was needed to ensure that the resected central segment was not oversized, resulting in a too small femoral head and possible joint instability. Femoral head sphericity was evaluated with the head sphericity index [22], which was defined as the ratio of the minor to the major axis of the ellipse drawn to best fit the femoral head articular surface on the conventional AP pelvic radiograph. A femoral head was considered spherical if the head sphericity exceeded 80%.…”

Section: Methodsmentioning

confidence: 99%

Head Reduction Osteotomy With Additional Containment Surgery Improves Sphericity and Containment and Reduces Pain in Legg-Calvé-Perthes Disease

Siebenrock

Anwander

Zurmühle

et al. 2015

Background Severe femoral head deformities in the frontal plane such as hips with Legg-Calvé-Perthes disease (LCPD) are not contained by the acetabulum and result in hinged abduction and impingement. These rare deformities cannot be addressed by resection, which would endanger head vascularity. Femoral head reduction osteotomy allows for reshaping of the femoral head with the goal of improving head sphericity, containment, and hip function. Questions/purposes Among hips with severe asphericity of the femoral head, does femoral head reduction osteotomy result in (1) improved head sphericity and containment; (2) pain relief and improved hip function; and (3) subsequent reoperations or complications? Methods Over a 10-year period, we performed femoral head reduction osteotomies in 11 patients (11 hips) with severe head asphericities resulting from LCPD (10 hips) or disturbance of epiphyseal perfusion after conservative treatment of developmental dysplasia (one hip). Five of 11 hips had concomitant acetabular containment surgery including two triple osteotomies, two periacetabular osteotomies (PAOs), and one Colonna procedure. Patients were reviewed at a mean of 5 years (range, 1-10 years), and none was lost to followup. Mean patient age at the time of head reduction osteotomy was 13 years (range, 7-23 years). We obtained the sphericity index (defined as the ratio of the minor to the major axis of the ellipse drawn to best fit the femoral head articular surface on conventional anteroposterior pelvic radiographs) to assess head sphericity. Containment was assessed evaluating the proportion of patients with an intact Shenton's line, the extrusion index, and the lateral center-edge (LCE) angle. Merle d'Aubigné-Postel score and range of motion (flexion, internal/external rotation in 90°of flexion) were assessed to measure pain and function. Complications and reoperations were identified by chart review. Results At latest followup, femoral head sphericity (72%; range, 64%-81% preoperatively versus 85%; range, 73%-96% postoperatively; p = 0.004), extrusion index (47%; range, 25%-60% versus 20%; range, 3%-58%; p = 0.006), and LCE angle (1°; range, À10°to 16°versus 26°; range, 4°-40°; p = 0.0064) were improved compared with preoperatively. With the limited number of hips available, the proportion of an intact Shenton's line (64% versus 100%; p = 0.087) and the overall Merle d'Aubigné-Postel score (14.5; range, 12-16 versus 15.7; range, 12-18;

“…Peters et al [45] concluded that recognition of the true preoperative acetabular version and reorientation of the acetabulum into an appropriately anteverted position have become important factors in surgical decisionmaking. Steppacher et al [52] found a nonspherical shape of the femoral head and acetabulum in dysplastic hips could potentially induce a painful FAI or influence the result of a reorientation procedure. Fujii et al [10] and Yasunaga et al [66] observed no difference in the prevalence of a crossover sign between hips with and without progression of osteoarthritis.…”

Section: Discussionmentioning

confidence: 99%

Patient Selection Criteria for Periacetabular Osteotomy or Rotational Acetabular Osteotomy

Yasunaga

Yamasaki

Ochi

2012

Background Hip dysplasia is the most common cause of secondary osteoarthritis (OA). Periacetabular osteotomy (PAO) or rotational acetabular osteotomy (RAO) has been used as a joint-preserving procedure. However, the patient selection criteria are not clearly defined. Questions/purposes Based on a systematic review, we identified reported patient selection criteria for PAO or RAO. Methods We performed a systematic review of RAO and 18 studies met our inclusion criteria. For the PAO, the systemic review performed by Clohisy et al. was used. Where Are We Now? For patients with symptomatic hip dysplasia, lateral center-edge angle less than 10°to 30°, radiographic pre-or early OA, mean age at the time of surgery of 18 to 45 years, and improvement in joint congruency on AP radiograph with hip abduction, radiographic deformity correction consistently improved hip function in all studies. Radiographic OA progression was noted in 5% to 33% at 3.2 to 20 years postoperatively. Clinical score and prevention of radiographic OA progression of patients 50 years or older or with advanced stage were worse in younger patients or those with early stage. Where Do We Need to Go? The key challenges are (1) preoperative evaluation of articular cartilage; (2) indication for older patients; (3) prevention of secondary femoroacetabular impingement; and (4) intraarticular treatment combined with PAO or RAO. How Do We Get There? Future prospective, longitudinal cohort studies need to determine optimal patient selection criteria, risk factors for clinical failure, optimal deformity correction parameters, and the role of adjunctive surgical procedures.