Thumb carpometacarpal palmar and radial abduction in adults with thumb carpometacarpal joint pain: Inter-rater reliability and precision of the inter-metacarpal distance method.
Corey McGee, Virginia O'Brien, Jennifer Johnson and 1 others
PMID 33947615WHAT IT FOUND
Using a digital caliper to measure the distance between thumb and index finger metacarpals showed excellent agreement between therapists.
This method is more reliable than goniometry for assessing thumb abduction in patients with carpometacarpal joint pain.
Key findings
01Inter-rater reliability for the inter-metacarpal distance method was excellent for both palmar abduction (ICC 0.85) and radial abduction (ICC 0.76).
02The minimal detectable change was 5.6 mm for palmar abduction and 8.8 mm for radial abduction, indicating acceptable precision.
03Therapists with significantly different levels of experience achieved excellent agreement when using this measurement method.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The sample size was small (28 thumbs), which may limit the generalizability of the precision estimates. Findings apply only to the specific caliper and protocol used, not necessarily to other measurement devices or techniques. Radial abduction measurements were less precise than palmar, potentially due to hand positioning challenges during testing. The method does not allow for direct comparison of abduction measurements between different patients due to hand size variations.
The easy way to misread this
Do not assume this method allows you to compare thumb abduction measurements directly between different patients. The study notes that hand size influences the measurement, so it is suitable for tracking change in one person over time but not for ranking patients against each other.