Abstract
Accurate measurement of knee range of motion (ROM) is critical to predict the outcomes
of knee surgery and prognosis. We investigated the reliability of knee ROM measurements
by goniometer compared with robotic system. Fifty-three patients with medial osteoarthritis
who were planning to undergo unicompartmental knee arthroplasty (UKA) with robotic
UKA were prospectively enrolled. During the operation, knee ROM measurement was performed
in both flexion and extension before and after insertion of the implant using both
a goniometer and robotic system. The intraclass correlation coefficient (ICC) of extension
measured by the goniometer and robotic system showed good agreement; however, the
ICC of flexion did not show good agreement. During passive flexion, the mean values
measured before insertion of the implant were significantly lower by goniometer (134.6 ± 6.43)
than by robot (145.4 ± 6.80; p = 0.017); likewise, the mean values after insertion of the implant were significantly
lower by goniometer (138.6 ± 6.07) than by robotic system (147.0 ± 6.60; p = 0.045). A goniometer can underestimate knee ROM measurements compared with robotic
system, especially in flexion. Orthopaedic surgeons should be cautious when measuring
the flexion angle with a goniometer.
Keywords
knee range of motion - goniometer - unicompartmental knee arthroplasty - robot - reliability
