Does lesser trochanter implication affect hip flexion strength in proximal femur fracture?

Abstract

In pertrochanteric and intertrochanteric femoral fractures, the avulsion of the lesser trochanter by the pull of the iliopsoas muscle is not uncommon. This fragment is not commonly fixed because the avulsion of the lesser is tough to not influence the clinical outcome but up to date there is no evidence to support this statement. The aim of this study is to evaluate if lesser trochanter implication affects psoas muscle strength in proximal femur fracture. Patients with a consolidated intertrochanteric or pertrochanteric fracture associated or not with lesser trochanter fracture were enrolled, respectively, in group A and group B. Criteria of inclusion were the achievement of an anatomic reduction with gamma nail and a complete consolidation of the fracture. Criteria of exclusion were a follow-up shorter than 6 months and age over 65 years old at surgery. Patients were retrospectively reviewed for the purpose of this study. Range of motion, modified Harris Hip Score (mHHS), flexion strength with hip in neutral position, at 90° of flexion and in "figure four" position were evaluated on injured and healthy side. On the pre-operative X-rays, the vertical displacement of the lesser trochanter was calculated. Groups A and B showed no significant difference in age and follow-up. No statistical difference between the two groups was found in range of motion, mean mHHS, hip flexion strength at 90° of hip flexion. Lesser trochanter fracture group showed a significantly reduced strength in flexion with hip in neutral flexion (mean difference between two groups was 18.5 kgf). Lesser trochanter displacement showed a significant correlation with strength at 90° of flexion. Our results showed that lesser trochanter implication may result in decreased hip flexion strength. Lesser trochanter displacement is directly correlated with flexion strength. Further studies will be necessary to understand if lesser trochanter fixation may be a good solution for those patients.