Efficacy of Hip Strengthening on Pain Intensity, Disability, and Strength in Musculoskeletal Conditions of the Trunk and Lower Limbs: A Systematic Review with Meta-Analysis and Grade Recommendations

Abstract

To investigate the efficacy of hip strengthening on pain, disability, and hip abductor strength in musculoskeletal conditions of the trunk and lower limbs, we searched eight databases for randomized controlled trials up to 8 March 2022 with no date or language restrictions. Random-effect models estimated mean differences (MDs) with 95% confidence intervals (CIs), and the quality of evidence was assessed using the GRADE approach. Very low quality evidence suggested short-term effects (≤3 months) of hip strengthening on pain intensity (MD of 4.1, 95% CI: 2.1 to 6.2; two trials, n = 48 participants) and on hip strength (MD = 3.9 N, 95% CI: 2.8 to 5.1; two trials, n = 48 participants) in patellofemoral pain when compared with no intervention. Uncertain evidence suggested that hip strengthening enhances the short-term effect of the other active interventions on pain intensity and disability in low back pain (MD = -0.6 points, 95% CI: 0.1 to 1.2; five trials, n = 349 participants; MD = 6.2 points, 95% CI: 2.6 to 9.8; six trials, n = 389 participants, respectively). Scarce evidence does not provide reliable evidence of the efficacy of hip strengthening in musculoskeletal conditions of the trunk and lower limbs.

Keywords: disability; hip strength; hip strengthening; musculoskeletal conditions; pain intensity; rehabilitation.

Figure 1

Flow of studies through the review. RCT: randomized clinical trial.

Figure 2

Summary of evidence of effect of hip strengthening on pain. Control: sham, placebo, no intervention, or waiting list. (a) Downgraded owing to imprecision: less than 400 participants included in the meta-analysis (sample of less than 200 was considered serious imprecision, and the evidence was downgraded by two levels); (b) Downgraded owing to inconsistency: I² statistic was higher than 50% or pooling was not possible (poor overlap between the confidence intervals of the effects of the studies included in the meta-analysis was considered serious inconsistency, and the evidence was downgraded by two levels); (c) Downgraded owing to risk of bias: more than 25% of the participants in the meta-analysis were from trials with a high risk of bias (i.e., PEDro score < 6 of 10) [30,31,32,33,35,36,37,38].

Figure 3

Summary of evidence of the effect of hip strengthening on disability. Control: sham, placebo, no intervention, or waiting list. (a) Downgraded owing to imprecision: less than 400 participants included in the meta-analysis (sample of less than 200 was considered serious imprecision, and the evidence was downgraded by two levels); (b) Downgraded owing to inconsistency: I² statistic was higher than 50% or pooling was not possible (poor overlap between the confidence intervals of the effects of the studies included in the meta-analysis was considered serious inconsistency, and the evidence was downgraded by two levels); (c) Downgraded owing to risk of bias: more than 25% of the participants in the meta-analysis were from trials with a high risk of bias (i.e., PEDro score < 6 of 10) [30,31,32,33,34,35,36,37,38].

Figure 4

Summary of evidence of the effect of hip strengthening on strength. Control: sham, placebo, no intervention, or waiting list. (a) Downgraded owing to imprecision: less than 400 participants included in the meta-analysis (sample of less than 200 was considered serious imprecision, and the evidence was downgraded by two levels); (b) Downgraded owing to inconsistency: I² statistic was higher than 50% or pooling was not possible (poor overlap between the confidence intervals of the effects of the studies included in the meta-analysis was considered serious inconsistency, and the evidence was downgraded in two levels); (c) Downgraded owing to risk of bias: more than 25% of the participants in the meta-analysis were from trials with a high risk of bias (i.e., PEDro score < 6 of 10) [31,32,37].