Association between body mass index and pressure biofeedback assessed core muscle function in patients with knee osteoarthritis: A registry-based pilot study
Abstract
Background: Knee osteoarthritis (OA) is a major cause of pain and disability, and excess body weight and muscle dysfunction are potentially modifiable contributors to disease burden. Trunk muscle function may influence lumbopelvic control and lower-limb mechanics, but the relationship between body mass index (BMI) and deep abdominal muscle function in knee OA remains uncertain.
Objective: To examine the association between BMI and pressure biofeedback-assessed core muscle function in patients with knee osteoarthritis.
Methods: This pilot cross-sectional registry-based study included 15 adults with clinically and/or radiologically diagnosed knee OA selected by purposive sampling from the VIMS Knee Osteoarthritis Registry. BMI was calculated from recorded height and weight. Deep abdominal muscle function was assessed using a Pressure Biofeedback Unit (PBU) during an abdominal hollowing manoeuvre. Descriptive statistics were summarized as mean ± standard deviation or frequency (%). Because the data did not satisfy assumptions for parametric correlation, Spearman's rank correlation was used. Statistical significance was set at p < 0.05.
Results: The sample comprised 8 men (53.3%) and 7 women (46.7%), with a mean age of 64.87 ± 7.54 years. Mean BMI was 25.14 ± 4.29 kg/m² and the mean PBU reading was 34.0 ± 2.0 mmHg. Eight participants (53.3%) had a BMI in the normal range, six (40.0%) were overweight, and one (6.7%) was obese. BMI showed a very weak positive correlation with the PBU measure (Spearman's ρ = 0.152), which was not statistically significant (p = 0.588; approximate 95% CI, -0.39 to 0.62).
Conclusion: In this small pilot sample, BMI was not significantly associated with PBU-assessed deep abdominal muscle function. The wide confidence interval and restricted distribution of BMI, including only one participant with obesity, preclude a definitive conclusion regarding the absence of an association. Weight status and core motor control should therefore be assessed as related but distinct clinical domains in knee OA. Larger multicentre studies using comprehensive measures of trunk muscle performance are warranted.
Keywords:
Body mass index; core stability; Knee osteoarthritis; Obesity; Pressure biofeedback unit; Transversus abdominisDownloads
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Copyright (c) 2026 Vanshika Matra, Deepak Anap (Author)
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