A Multicenter Study of Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Beware of the Tönnis Angle

Abstract

Background: Hip arthroscopy has been previously demonstrated to be an effective treatment for adult mild hip dysplasia. There are many radiographic parameters used to classify hip dysplasia, but to date few studies have demonstrated which parameters are of most importance for predicting surgical outcomes. Purpose: To identify preoperative radiographic parameters that are associated with poor outcomes in the arthroscopic treatment of adult mild hip dysplasia. Study Design: Case-control study; Level of evidence, 3. Methods: Radiographic analysis was performed in patients with mild hip dysplasia who underwent arthroscopic surgery between 2009 and 2015. Preoperative radiographic measurements included lateral center edge angle, Tönnis angle, neck shaft angle, anterior center edge angle, alpha angle, femoral head extrusion index, and acetabular depth-to-width ratio. Failure was defined as failure to achieve the minimal clinically important difference (MCID) utilizing the modified Harris Hip Score or as the need for secondary operation. The equal variance t test was used to analyze radiographic parameters. Statistical significance was determined using a P value of .05. Results: A total of 373 hips underwent analysis with an average follow-up of 41 months (range, 24-102 months). Of these, 46 hips (12%) required secondary operation, and 95 (25%) failed to meet the MCID. The overall failure rate was 32.4%. There was no single measurement or combination thereof associated with failure to reach the MCID. Higher preoperative Tönnis angles were associated with secondary operation, with a mean of 6.7° (95% CI, 5.3°-8.1°) in the secondary operation group versus 4.8° (95% CI, 4.4°-5.3°) in the nonsecondary operation group ( P = .006). The odds ratio was 1.12 (95% CI, 1.0-1.2; P = .05) per degree increase in Tönnis angle for secondary operation. In patients with a Tönnis angle >10°, 84% required secondary operation. Conclusion: Higher Tönnis angles portend a higher risk for revision surgery. The probability of secondary operation was increased by a magnitude of 1.12 with each degree increase in the Tönnis angle. In patients with a Tönnis angle >10°, 84% required a secondary operation.

Hip Stability May Influence the Development of Greater Trochanteric Pain Syndrome: A Case-Control Study of Consecutive Patients

“…This may be an issue with statistical power. However, a recent study by McQuivey et al 12 found an association between increased Tönnis angle and failure of hip arthroscopy in patients with borderline hip dysplasia. Interestingly, they found no association between failure rates and lower LCEA, lower anterior center-edge angle, extrusion index, or ADW.…”

Revision Hip Arthroscopy in the Borderline Dysplastic Population: Reporting Outcomes With Minimum 2-Year Follow-up, With a Subanalysis Against a Propensity-Matched Nondysplastic Control Group

“…34 The indications to proceed with revision hip preservation surgery were as follows: no evidence of severe cartilage damage on magnetic resonance imaging or arthrogram, no joint space narrowing, or an unbroken Shenton line. Furthermore, the relative indications to advance to isolated revision hip arthroscopy without a concomitant bony procedure (eg, PAO) were as follows: LCEA between 18° and 25°, Tönnis angle ≤10°, 40 or femoral anteversion <25°, as well as evidence of intra-articular sources of pain, such as residual cam-type morphology, labral retear, or capsular defect. 24 Relative indications for concomitant osteotomy and arthroscopy were bony deformity outside the measures cited, ligamentous laxity with Beighton score ≥4, and ligamentum teres tears indicating gross instability.…”

Femoral Head Chondrocyte Viability at the Cam Deformity in Patients With Femoroacetabular Impingement Syndrome

“…Exclusion criteria for this study were as follows: (1) insufficient or incomplete preoperative radiographs, (2) a history of surgery on the affected hip, (3) other intra-articular pathology (eg, evidence of slipped capital femoral epiphysis, true dysplasia [lateral center-edge angle of <18° or 18°-25° with increased Tönnis angle of >10°], 16 Legg-Calve-Perthes disease), or (4) symptomatic extra-articular impingement.…”

“…The presence of an isolated labral or cartilage tear on magnetic resonance imaging scan without subjective hip pain or aforementioned clinical signs did not constitute an indication for hip arthroscopy given the previously documented high prevalence of asymptomatic labral tears. 12 Exclusion criteria for this study were as follows: (1) insufficient or incomplete preoperative radiographs, (2) a history of surgery on the affected hip, (3) other intraarticular pathology (eg, evidence of slipped capital femoral epiphysis, true dysplasia [lateral center-edge angle of \18°o r 18°-25°with increased Tönnis angle of .10°], 16 Legg-Calve-Perthes disease), or (4) symptomatic extra-articular impingement.…”