Radiographic Risk Factors and Signs of Abductor Tears in the Hip

OBJECTIVES: There is a known increased prevalence of abductor tears in patients with increased age and female gender. This study’s purpose is to identify radiographic risk factors (RRF) and radiographic signs of abductor tendon tears. METHODS: Patients with intraoperative diagnoses of abductor tear were included in this study and were matched by age ±5 years, gender, and BMI ±5 with patients who had no abductor pathology by clinical exam and MRI. An AP pelvis radiograph was performed on all patients. The radiographs were evaluated for RRF (pelvic width, body weight moment arm, abductor moment arm, abductor angle, pelvic height) and signs of abductor tendon pathology (greater trochanteric excrescence). Femoral version was measured on MRI when images were available. RESULTS: There were 152 patients with abductor tears identified intraoperatively. All were treated with surgical repair. These patients were matched as described previously. The RRF found were an increased tear drop to tear drop distance (14.8 for abductor tears vs. 14.3 for control; p<0.001), body weight moment arm (11.1 vs. 10.9; p<0.001), abductor moment arm (7.8 vs. 7.6; p<0.001), decreased femoral anteversion (7.6 vs. 10.6; p=0.045), and excrescence presence (41% vs. 3%; p<0.001). An excrescence of the greater trochanter had a specificity of 97%, PPV of 94% and a positive likelihood ratio of 12.8 for abductor tears. CONCLUSION: Patients with abductor tears have a wider pelvis, longer abductor moment arm, longer body weight moment arm, less femoral anteversion, and have greater trochanteric excrescence noted on nearly half of patients with an abductor tear. Presence of an excrescence was noted to have a positive predictive value of 94%, specificity of 97%, and positive likelihood ratio of 12.75, suggesting that if noted on radiograph, the care provider should have a very high index of suspicion for abductor tendon tear.