Is gluteus medius injured in patients treated with a trochanter tip entry intramedullary nail? Clinical, electrophysiological and functional outcomes

OBJECTIVES: This study aims to assess the functional outcomes, static-dynamic postural stability of patients and evaluate electromyographic activity of gluteus medius (GMed) muscle during gait and spatiotemporal parameters of gait in patients after antegrade intramedullary nailing (IMN) of femoral shaft fractures with trochanter tip entry. PATIENTS AND METHODS: Sixteen patients (15 males, 1 female; mean age 34.8±15.2 years; range, 18 to 58 years) who were treated with an antegrade trochanteric IMN between January 2009 and July 2013 and eight healthy male controls (mean age 39.3±9.8 years; range, 27 to 57 years) were included in this retrospective study. Muscle strength, static and dynamic postural stability and fall risk were evaluated. In addition, spatiotemporal parameters of gait were assessed using a validated wireless inertial sensing device and a wireless electromyography (EMG) device was used to measure electromyographic activity of GMed muscle in both groups. RESULTS: There were significant differences in muscle strength, functional and dynamic balance test scores between operated and intact sides (one-leg hop test score p=0.009, balance test scores p<0.001-0.033). There were significant differences in functional and quality of life physical function test scores between groups (one-leg hop test score p=0.014). However, no significant differences were found in EMG results, dynamics balance, and statics postural stability test scores between groups (p>0.05). CONCLUSION: After isolated femur fracture, patients treated with antegrade trochanteric IMN demonstrated good static and dynamic stability and poor functional outcomes compared to controls. In conclusion, patients with antegrade trochanteric IMN have good balance but poor functional performance; however, further studies are needed to find out the primary reason for these results.