Measuring Angular Joint Positions. Who is better, hand surgeon or CHT?
Which is better, eyeball or goniometer?
To continue reading from Report on Hands, scroll down to Results showed that for the 9 joint positions (3 each: wrist, MP, PIP), neither visual nor
McVeigh KH et al: Accuracy and Validity of Goniometer and Visual Assessments of Angular Joint Positions of the Hand and Wrist. J Hand Surg Am. 2016 Jan 20. pii: S0363-5023(15)01590-7. doi: 10.1016/j.jhsa.2015.12.014. [Epub ahead of print]
Investigators at the Mayo Clinic in Jacksonville FL fabricated 3 low-profile, custom thermoplastic orthoses that held a volunteer’s wrist and index finger proximal interphalangeal and metacarpophalangeal joints in 3 different positions. Then with each orthosis in place one sequentially, 20 experienced hand surgeons and 20 CHTs assessed the angular positions of these joints first visually and then with a standard goniometer. The examiners used their own preferred technique for goniometer placement.
X-rays of the studied hand with each orthosis in place provided the reference standards against which the clinical measurements were compared. Until data collection was complete, all participants other than the radiologist were blinded to the radiographically derived measurements.
Results showed that for the 9 joint positions (3 each: wrist, MP, PIP), neither visual nor goniometer assessments were consistently within +/- 5 degrees of the radiographic measurements. For the PIP joint measurements, goniometer measurements were more accurate than visual assessments. For wrist and 2 of the 3 MP joint angles, goniometer and visual assessments were equal. There were no significant differences between the surgeons’ and the CHTs’ accuracy.
The authors note that previous studies have shown that the reproducibility of goniometric measurements increases with observer experience, which is why they chose to study experienced hand surgeons and experienced hand therapists. The investigators also cite previous work showing that intra-observer goniometric errors are smaller than inter-observer errors, which the current study did not assess.
The authors conclude that neither visual nor goniometer assessment displayed high levels of accuracy when compared to radiographically derived standards. For the index MP and wrist joints, visual assessments were as accurate as the goniometer measurements. For the index PIP joint, the goniometer provided a more accurate assessment than “eye-balling it.” No one individual’s measurements were consistently accurate.
COMMENT: The results do not surprise me. Our eye is pretty good but not perfect. To accurately follow the progression of a joint through treatment, the most valid comparisons would be measurements taken by the same person using the same technique over time.
Also, consider the folly of other authors who report (and editors who let authors report) their results of a given treatment that provided “an average of 37.24 degrees of improved motion.” Even if the same person using the same technique obtained all of the raw measurements that comprised the average, the reproducibility of the original measurements almost certainly varied by at least 5 degrees. The authors should just report 37 degrees, and even then readers should take 37 with a grain of salt and think probably the result was in the 35-40 degree range.
Watch for photogoniometery, which might take smart phone pictures in maximum extension and flexion and use optical recognition software to determine joint angles. I am 78.98% certain that such is forthcoming!!