Lateral Center-Edge Angle Is Not Predictive of Acetabular Articular Cartilage Surface Area: Anatomic Variation of the Lunate Fossa.

BACKGROUND: Surgical treatment of symptomatic femoroacetabular impingement (FAI) and dysplasia requires careful characterization of acetabular morphology. The lateral center-edge angle (LCEA) is often used to assess lateral acetabular anatomy. Previous work has questioned the LCEA as a surrogate for acetabular contact/articular cartilage surface area because of the variable morphology of the lunate fossa. HYPOTHESIS: We hypothesized that weightbearing articular cartilage of the acetabulum would poorly correlate with LCEA secondary to significant variation in the size of the lunate fossa. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 3. METHODS: Patients with 3D CT imaging undergoing either hip arthroscopy or periacetabular osteotomy for FAI or symptomatic hip instability were retrospectively identified. The LCEA and femoral head diameter were measured on an anteroposterior pelvis radiograph. Patients were grouped according to their lateral acetabular coverage as undercoverage (LCEA, <25°), normal coverage (LCEA, 25°-40°), or overcoverage (LCEA, >40°). Patients were randomly identified until each group contained 20 patients. The articular surface area was measured from preoperative 3D CT data. Linear regression analysis was performed to examine the relationship between articular surface area and LCEA. Continuous and categorical data were analyzed utilizing analysis of variance and chi-square analysis. Statistical significance was set at P < .05. RESULTS: No difference in age (P = .52), body mass index (BMI) (P = .75), or femoral head diameter (P = .66) was noted between groups. A significant difference in articular surface area was observed between patients with undercoverage and those with overcoverage (20.4 cm2 vs 24.5 cm2; P = .01). No significant difference was identified between the undercoverage and normal groups (20.4 cm2 vs 23.3 cm2; P = .09) or the normal and overcoverage groups (23.3 cm2 vs 24.5 cm2; P = .63). A moderate positive correlation was observed between LCEA and articular surface area across all patients (r = 0.38; P = .002) but not when patients with undercoverage were excluded (r = 0.02; P = .88). Significant variation in surface area was observed within each group such that no patient in any group was outside of 2 SDs of the means of the other groups. When patients were categorized into quartiles established by the articular surface area for the entire population, 40% of patients with overcoverage were observed in the first or second quartile (lower area). CONCLUSION: Lateral acetabular undercoverage based on the LCEA (<25°) correlates with decreased acetabular surface area. Normal or increased acetabular coverage (LCEA, >25°), however, is not predictive of increased, normal, or decreased acetabular surface area.

Does Severity of Acetabular Dysplasia Influence Clinical Outcomes After Periacetabular Osteotomy?-A Case-Control Study.

BACKGROUND: Detailed characterization of factors influencing post-periacetabular osteotomy (PAO) outcome could guide treatment offered. METHODS: Using a prospective, multicenter database of PAOs, 61 hips/patients (51 females) with lesser dysplasia (acetabular index < 15° and lateral center-edge angle > 15°) were case-control matched for age, gender, body mass index, Tönnis grade, and joint congruency (P = .6-.9) with a "comparison group" of pronounced dysplasia (n = 183), aiming to assess whether severity of acetabular dysplasia has an effect on outcome following PAO and/or the ability to achieve desired acetabular correction. RESULTS: At 4 ± 1.5 years, no differences in complication or reoperation rates were detected between the groups (P = .29). Lesser dysplastic hips had inferior Hip Disability and Osteoarthritis Outcome Score, both preoperatively (52 vs 59) and postoperatively (73 vs 78); however, similar improvements were seen. Among the lesser dysplastic hips, those that required a femoral osteochondroplasty at PAO had significantly inferior preoperative Hip Disability and Osteoarthritis Outcome Score (48 ± 18). Increased ability to achieve optimum correction was seen (80% vs 59%, P = .4) in lesser dysplasia. CONCLUSION: A PAO is safe and efficacious in the treatment of lesser dysplasia. Further study on the identification of the optimum treatment modality for the mildly dysplastic hips with cam deformity is required.

Previous failed hip arthroscopy negatively impacts early patient-reported outcomes of the periacetabular osteotomy: an ANCHOR Matched Cohort Study.

Surgical treatment of hip dysplasia by arthroscopic procedures remains controversial. The aim of this study was to compare outcomes of periacetabular osteotomy (PAO) after failed hip arthroscopy to a matched-control group without previous arthroscopy. Fifty-two patients who underwent PAO after failed hip arthroscopy were matched to two subjects without arthroscopy based on age, sex, BMI and radiographic severity. Pre- and post-operative patient self-reported outcomes and radiographic parameters were compared at minimum 1-year follow-up. Prior to PAO the failed hip arthroscopy group exhibited lower modified Harris hip scores (mHHS; 57 versus 62; P = 0.04), WOMAC (59.9 versus 66.3; P = 0.08), UCLA activity (5 versus 7; P = 0.001) and SF12 physical scores (34 versus 40; P = 0.001) compared with the non-arthroscopy group. At minimum 1-year follow-up, the failed hip arthroscopy group had lower mHHS (78 versus 87; P = 0.003); worse WOMAC (84.1 versus 90.8; P = 0.02) and SF-12 physical component (46 versus 50; P = 0.02) with similar UCLA (7 versus 8; P = 0.21) compared with the non-arthroscopy group. No differences were detected regarding radiographic parameters or in patient-reported outcomes from preoperative to follow up. PAO achieved the desired radiographic correction and significant improvement in pain and function after a failed previous hip arthroscopy, however, the patient-reported outcomes were inferior to those of PAO without previous failed arthroscopy.