The purpose of this study was to investigate the effects of VF on the isometric contraction of the knee extensors in various orthopaedic patients.
We studied 12 vertebral fracture patients during conservative treatment (vertebral fracture group, age: 78.8±10.8y), 20 hip fracture patients who had undergone surgical operation (hip fracture group, age: 80.0±10.7y), and 19 knee osteoarthritis patients following total knee arthroplasty (TKA group, age: 73.8±5.8y). The subjects were seated in a treatment bed with 90°hip and knee flexion. The isometric contraction of the knee extensors was measured using hand-held dynamometry in two conditions, with and without VF, twice each in random order. The maximum values for each condition were used for data analysis. The VF was presented in front of the subject’s face by the force values displayed on the dynamometry. Differences of muscle strength between the VF and no-VF test conditions at each patient group were analyzed using paired t test or Wilcoxon signed-rank test. Then, difference in the VF/no-VF ratio of muscle strength among three groups were identified using the analysis of variance (ANOVA). The difference of P0.05 was considered statistically significant.
There were significant effects of VF on knee extensor strength in hip fracture (no-VF: 11.09±3.73kgf, VF: 12.20±4.42kgf, P=0.008) and TKA group (no-VF: 12.95±7.08kgf, VF: 14.79±6.45kgf, P=0.002). No such effect was seen in vertebral fracture group (no-VF: 16.22±6.12kgf, VF: 16.89±6.83kgf, P=0.229). According to ANOVA, there was no significant difference in the VF/no-VF ratio among the three groups (vertebral fracture group: 105.0±15.9%, hip fracture group: 110.2±13.8%, TKA group: 117.5±16.2%, P=0.082).
VF is effective in increasing knee extensor muscle output in orthopedic patients, and the extent of this effect may vary depending on the disease.
The effect of VF on maximum knee extension strength varies depending on the type of orthopedic disease, and understanding these differences is important for correctly interpreting the evaluation results.
maximal voluntary contraction
orthopaedic
