Strengthening of the hip and core versus knee muscles for the treatment of patellofemoral pain: a multicenter randomized controlled trial

Abstract

Context: Patellofemoral pain (PFP) is the most common injury in running and jumping athletes. Randomized controlled trials suggest that incorporating hip and core strengthening (HIP) with knee-focused rehabilitation (KNEE) improves PFP outcomes. However, no randomized controlled trials have, to our knowledge, directly compared HIP and KNEE programs.

Objective: To compare PFP pain, function, hip- and knee-muscle strength, and core endurance between KNEE and HIP protocols after 6 weeks of rehabilitation. We hypothesized greater improvements in (1) pain and function, (2) hip strength and core endurance for patients with PFP involved in the HIP protocol, and (3) knee strength for patients involved in the KNEE protocol.

Design: Randomized controlled clinical trial.

Setting: Four clinical research laboratories in Calgary, Alberta; Chicago, Illinois; Milwaukee, Wisconsin; and Augusta, Georgia.

Patients or other participants: Of 721 patients with PFP screened, 199 (27.6%) met the inclusion criteria (66 men [31.2%], 133 women [66.8%], age = 29.0 ± 7.1 years, height = 170.4 ± 9.4 cm, weight = 67.6 ± 13.5 kg).

Intervention(s): Patients with PFP were randomly assigned to a 6-week KNEE or HIP protocol.

Main outcome measure(s): Primary variables were self-reported visual analog scale and Anterior Knee Pain Scale measures, which were conducted weekly. Secondary variables were muscle strength and core endurance measured at baseline and at 6 weeks.

Results: Compared with baseline, both the visual analog scale and the Anterior Knee Pain Scale improved for patients with PFP in both the HIP and KNEE protocols (P < .001), but the visual analog scale scores for those in the HIP protocol were reduced 1 week earlier than in the KNEE group. Both groups increased in strength (P < .001), but those in the HIP protocol gained more in hip-abductor (P = .01) and -extensor (P = .01) strength and posterior core endurance (P = .05) compared with the KNEE group.

Conclusions: Both the HIP and KNEE rehabilitation protocols produced improvements in PFP, function, and strength over 6 weeks. Although outcomes were similar, the HIP protocol resulted in earlier resolution of pain and greater overall gains in strength compared with the KNEE protocol.

Keywords: anterior knee pain; clinical trial; knee rehabilitation; outcomes assessment; patella.

Figures

Figure 1.

Flow of participants through the study protocol.

Figure 2.

Mean visual analog scores measures for patients with patellofemoral pain each week during the 6-week hip- and core- and knee-focused rehabilitation protocols. a Different than baseline score.

Figure 3.

Mean Anterior Knee Pain Scale measures for patients with patellofemoral pain each week during the 6-week hip- and core- and knee-focused rehabilitation protocols. a Different than baseline score.

Figure 4.

Percentage of change in output of maximum voluntary isometric force from baseline for hip abductors, extensors, external rotators, internal rotators, and knee extensors. a Different than baseline score (P ≤ .05) . b Different than patients with patellofemoral pain who followed the knee-focused protocol (P ≤ .05).

Figure 5.

Percentage of change in timed core-endurance scores from baseline for side-bridge and front-plank exercises and horizontal-extension test to assess lateral, anterior, and posterior core endurance, respectively. a Different than baseline score (P ≤ .05).