To determine, in people with knee osteoarthritis (KOA): i) the effectiveness of adding hip strengthening exercises to quadriceps exercises and ii) the type of hip strengthening exercise with the greatest evidence for improving pain, function and quality of life.
Systematic review with meta-analysis.
Medline, Embase, Cochrane, CINAHL and SportDiscus databases were searched from inception to January 2018.
Randomised controlled trials investigating the effect of adding hip exercises to quadriceps exercises in people with KOA on pain, function and/or quality of life were included. 
Eight studies were included. Pooled data provide evidence that combined hip and quadriceps exercise is significantly more effective than quadriceps exercise alone for improving walking function (standardised mean difference -1.06, 95% CI -2.01 to -0.12), but not for outcomes of pain (-0.09, 95% CI -0.96 to 0.79), patient-reported function (-0.74, 95% CI -1.56 to 0.08) or stair function (-0.7, 95% CI -1.67 to 0.26). Subgroup analyses reveal that hip resistance exercises are more effective than functional neuromuscular exercises for improving pain (p<0.0001) and patient-reported function (p<0.0001). Multimodal exercise is no more effective than quadriceps strengthening alone for pain (0.13, 95% CI -0.31 to 0.56), patient-reported function (-0.15, 95% CI -0.58 to 0.29) or stair function (0.13, 95% CI -0.3 to 0.57).
Walking improved after the addition of hip strengthening to quadriceps strengthening in people with KOA. The addition of resistance hip exercises to quadriceps resulted in greater improvements in patient-reported pain and function.