Reliability and validity of a low-cost luggage scale for hip external rotation strength measurements.
Samuel Galligani, Austin Lopez, Justin Ilejay and 1 others
PMID 41328279WHAT IT FOUND
A low-cost luggage scale measured hip external rotation strength as reliably as a handheld dynamometer when held manually by novice clinicians.
It offers an accessible alternative for objective strength testing in clinics with limited equipment budgets.
Key findings
01Intra-rater reliability for the luggage scale was excellent for both examiners (ICC 0.971 and 0.926), while handheld dynamometer reliability was excellent for one examiner (ICC 0.921) and good for the other (ICC 0.866).
02Inter-rater agreement was excellent for the luggage scale (ICC 0.938) and good for the handheld dynamometer (ICC 0.891).
03The luggage scale showed strong concurrent validity with the handheld dynamometer, with pooled correlation coefficients of 0.822.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study only included healthy physical therapy students, so it is unknown if the luggage scale performs as well in patients with pain, stiffness, or significant weakness. Rest periods between tests varied because of scheduling cancellations, which could have influenced fatigue levels. Both examiners were of similar stature, so the results may not apply if the clinician is much stronger or weaker than the patient. The gait belt used to stabilize the pelvis adds setup time and may not be feasible in all clinical settings.
Declared interests
The authors report no conflicts of interest.
The easy way to misread this
Do not assume the luggage scale is accurate for patients with hip pathology or pain. The study only tested healthy students, so reliability in clinical populations has not been demonstrated.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →