The Impact of Lesser Trochanter Displacement on Hip Flexor Strength Recovery in Patients With Trochanteric Fracture.

Abstract

Trochanteric fractures (TFs) are common in older individuals and are expected to increase with Japan's aging population. These fractures often result in poor long-term outcomes, such as decreased independent walking and reduced hospital discharge rates. A significant aspect of TF involves displacement of the lesser trochanter (LT), which can weaken hip flexor muscles and potentially affect the recovery of activities of daily living (ADLs), including walking. Previous research has shown conflicting results regarding the effect of lesser trochanteric displacement on hip function and walking ability. This study aimed to determine whether displacement of the LT affects the recovery of hip flexor strength and walking ability at discharge in patients with TF. This prospective cohort study included 29 patients with TF admitted to a rehabilitation hospital between April 2023 and June 2024. The patients were classified into two groups: the LTdisplacement and the non-LT (NLT) displacement groups. Muscle strength (hip flexion, abduction, and knee extension) was measured using a handheld dynamometer. Walking ability assessments included gait speed, timed up-and-go test (TUG), 6-minute walk test (6 MWT), and functional ambulation category (FAC). Cognitive function was evaluated using the Hasegawa Dementia Rating Scale-Revised (HDS-R). Statistical analyses included repeated-measures analysis of variance (ANOVA) for muscle strength comparisons over time, with adjustments for violations of sphericity using the Greenhouse-Geisser correction. There were no significant differences between the LT and NLT groups in terms of demographic characteristics such as age, sex, or cognitive function. Repeated-measures ANOVA revealed a significant difference in hip flexor strength on the injured side between the groups, with the LT group showing persistent weakness until discharge. Significant improvements were noted in hip abduction and knee extension strength on the injured side, although no group differences were observed. Post-hoc analysis indicated significant strength improvements over time, particularly between admission and discharge, for most muscle groups, except for hip flexor strength in the LT group. Lesser trochanteric displacement in patients with TF resulted in a specific decline in hip flexor strength on the injured side, which persisted until discharge. However, no significant impact on walking ability was observed, likely because of compensatory mechanisms involving other muscles.