Ultrasound investigation into the relationship between hip adduction and the patellofemoral joint.
Lok Yin Ada Kwan, Alban Killingback, Claire Robertson and 1 others
PMID 34219955WHAT IT FOUND
In 40 healthy adults, moving the hip into 20° adduction consistently reduced the ultrasound gap between patella and femoral condyle by 0.18 cm.
This indicates lateral patellar tilt. It may inform patellofemoral pain rehab, but patients were not tested.
Key findings
01Hip adduction consistently reduced patella-condyle distance by 0.18 cm (p<0.05), indicating lateral patellar tilt.
02The measured change was not significantly different between genders (p=0.87), Tegner activity scores (p=0.68), or BMI (p=0.74).
03Ultrasound measurement variability was 0.5% in neutral position and 1% with hip adduction, and ultrasound was described as reliable for assessing patella tilt.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
All participants were asymptomatic young adults (mean age 21.5 years), so the findings do not show what happens in people with patellofemoral pain or in older patients. Only one participant was used for intra-observer reliability, so reliability across different clinicians or sessions was not established. The study measured a static position, not walking, running, or jumping, and it did not test whether reducing hip adduction changes pain or function. Activity level distribution was uneven, with many participants reporting a Tegner score of 6, which limits interpretation of activity-related findings. The authors' treatment relevance statements are based on the observed patellar position change, not on tested patient outcomes.
Declared interests
This study was funded internally by St George’s, University of London; the authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that hip adduction causes patellofemoral pain or that hip exercises will reduce pain. The study measured only a 0.18 cm mean reduction in patella-condyle distance in 40 healthy adults, not patients, and did not test treatment outcomes.