Hip fracture is a leading cause of abrupt functional impairment in individuals aged 65 years and older. Skeletal muscle involvement seems to be a key factor in the functional recovery of older patients with hip fractures. However, it has been minimally studied under this specific situation.
The aim was to evaluate and compare muscle function in older adults without hip fractures (e.g., those undergoing hip arthroplasty) with muscle function in individuals with hip fractures.
Muscle biopsies were collected from the gluteus maximus derived from patients over 65 years (mean age: 77.92±6.62 years; 83.33% female) during elective orthopedic interventions for hip arthroplasty (coxarthrosis, N=7) or urgent interventions for hip fractures (N=5). Muscle function was assessed using DMT 820M muscle myograph chambers. Frequency–response curves were generated at stimulation frequencies of 10, 25, 50, 75, and 100 Hz, measuring the maximum contraction force for each 5-second stimulus. Additionally, contractile responses to increasing caffeine concentrations (0.3 mM–30 mM) were evaluated. Complete stimulation- and concentration response-curves were analyzed by using two-factor ANOVA.
No significant differences were observed between the two groups in terms of age (mean age: 76.86± 7.33 for coxarthrosis vs. 79.40±5.94 for hip fracture; p>0.05). Muscle strips from the gluteus maximus of patients undergoing hip fracture surgery exhibited significantly lower neurogenic contraction in response to electrical stimulation compared to those from patients undergoing coxarthrosis surgery (p= 0.0104). However, the contractile response to increasing caffeine concentrations showed no significant differences between the two patient groups (p= 0.1775). Elderly patients with hip fractures experience substantial skeletal muscle function impairments compared to those with coxarthrosis. This muscle dysfunction appears to be more closely related to the deterioration in neuromuscular function rather than damage to muscle receptors. These findings may help explain in part the poor functional recovery observed in older adults following hip fractures.
