Eighteen studies were included (1,028 participants). PEDro scores ranged between 3 and 8 with 13 studies rated as being good. Participant and therapist blinding was not possible. One study used a quasi-randomisation method.
In participants awaiting hip replacement surgery, there was a significant difference between groups favouring exercise intervention for pain (SMD 0.45, 95% CI 0.15 to 0.75; five studies; Ι²=0%) and self-reported function (SMD 0.46, 95% CI 0.20 to 0.72; six studies; Ι²=0%) but no significant differences for lower limb strength (three studies; Ι²=76%) or walking speed (three studies; Ι²=0%).
In participants awaiting knee replacement surgery, there were no significant differences between groups for pain (10 studies; Ι²=79%), self-reported function (six studies; Ι²=0%), walking speed (seven studies; Ι²=82%) and lower limb strength (seven studies; Ι²=76%).
The authors stated that statistical heterogeneity was not apparent when data from one study were removed from the analyses (results remained non-significant).
Five studies reported post-exercise soreness as an adverse event. No other adverse events were reported as being caused by the interventions.