High knee extension and flexion muscle strength decreased the risk of falls in patients with knee OA and self-reported knee instability. After considering the effect of pain, there was insufficient statistical power to detect an association between muscle strength and falls, which might be because of the low number of subjects who fell (n = 31).

Lower muscle quality, physical inactivity, more severe joint degeneration, and higher pain are reported to be associated with lower strength in the upper leg muscles in knee osteoarthritis. Future research into knee osteoarthritis should focus on other potential determinants of muscle strength, such as muscle quantity, muscle activation, nutrition and vitamins, and inflammation. In hip osteoarthritis, more research is needed into all potential determinants.

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Objectives To assess whether (i) high-intensity resistance training (RT) leads to increased muscle strength compared to low-intensity RT in patients with knee osteoarthritis (OA); and (ii) RT with vitamin D supplementation leads to increased muscle strength compared to placebo in a subgroup with vitamin D deficiency. Design Randomized controlled trial Setting Outpatient rehabilitation centre Subjects Patients with knee OA Interventions 12 weeks of RT at high-intensity RT (70–80% of 1-repetition maximum (1-RM)) or low-intensity RT (40–50% of 1-RM) and 24 weeks of vitamin D (1200 International units vitamin D3 per day) or placebo supplementation. Main measures Primary outcome measure was isokinetic muscle strength. Other outcome measure for muscle strength was the estimated 1-RM. Secondary outcome measures were knee pain and physical functioning. Results 177 participants with a mean age of 67.6 ± 5.8 years were included, of whom 50 had vitamin D deficiency. Isokinetic muscle strength (in Newton metre per kilogram bodyweight) at start, end and 24 weeks after the RT was 0.98 ± 0.40, 1.11 ± 0.40, 1.09 ± 0.42 in the high-intensity group and 1.02 ± 0.41, 1.15 ± 0.42, 1.12 ± 0.40 in the low-intensity group, respectively. No differences were found between the groups, except for the estimated 1-RM in favour of the high-intensity group. In the subgroup with vitamin D deficiency, no difference on isokinetic muscle strength was found between the vitamin D and placebo group. Conclusions High-intensity RT did not result in greater improvements in isokinetic muscle strength, pain and physical functioning compared to low-intensity RT in knee OA, but was well tolerated. Therefore these results suggest that either intensity of resistance training could be utilised in exercise programmes for patients with knee osteoarthritis. No synergistic effect of vitamin D supplementation and RT was found, but this finding was based on underpowered data.

¼ 0.67, p < 0.01). Specifically, less knee pain, stronger plantarflexors, quadriceps and hamstrings, greater knee flexion range of motion, and greater APA velocity were related to better scores on the CB&M. Conclusions: Dynamic balance and mobility were related to a number of modifiable factors as eccentric plantarflexor, quadriceps, and hamstrings strength, knee joint range of motion and APA velocity. Given the considerable personal and economic burden of falls and the strong link to dynamic balance and mobility, interventions targeting such factors need to be developed. FALLS ASSOCIATED WITH KNEE INSTABILITY IN PEOPLE WITH KNEE OSTEOARTHRITIS: BIOMECHANICAL RISK FACTORS AND PAIN