Accuracy of Knee Range of Motion Assessment After Total Knee Arthroplasty

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Abstract

Measurement of knee joint range of motion (ROM) is important to assess after total knee arthroplasty. Our objective was to determine level of agreement and accuracy between observers with different knowledge on total ROM after total knee arthroplasty. Forty-one patients underwent x-ray of active and passive knee ROM (gold standard). Five different raters evaluated observed and measured ROM: orthopedic surgeon, clinical fellow, physician assistant, research fellow, and a physical therapist. A 1-way analysis of variance was used to determine differences in ROM between raters over both conditions. Limit of agreement for each rater for both active and passive total ROM under both conditions was calculated. Analysis of variance indicated a difference between raters for all conditions (range, P = .004 to P ≤.0001). The trend for all raters was to overestimate ROM at higher ranges. Assessment of ROM through direct observation without a goniometer provides inaccurate findings.

Section snippets

Methods

Forty-one consecutive patients (25 females and 16 males), a minimum of 1 year post-TKA, volunteered and gave written consent to participate in this study. All patients gave written informed consent to participate. These patients had primary TKA performed by the senior author and received 8 different combinations of implant design and tibial insert. Fifteen patients received NexGen CR (Zimmer) implants, 13 received NexGen CR-Flex (Zimmer), 5 received anatomic modular knee (AMK, DePuy), 4

Clinician-Specific Average ROM Results

The analysis of variance indicated that there was a difference between raters for all conditions (range, P = .004 to P ≤ .0001) indicating that there were differences in each of the measured values across clinicians. Descriptives for all raters and all conditions are presented in Table 1.

Mean Differences and Limits of Agreement Calculated Using X-Ray Values as the Gold Standard

Using x-ray values as the gold standard, the mean difference for the actively observed ROM ranged from −1.14° for the RF to −9.41° for the PT. Active measured ROM ranged from 2.9° for the RF to −7.4° for the

Discussion

Knee joint ROM is important to assess before and after joint arthroplasty surgery. Range of motion will affect an individual's ability to safely and independently perform activities of daily living such as sitting or negotiating stairs. It also is an extremely important determinant of patient satisfaction. Assessment of joint ROM in knee surgery is a key factor in deciding when to encourage the patients to have the intervention early as well as modifying the postoperative rehabilitation

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    Conflict of interest statement: Financial support has been received by the corresponding author. Institutional support: Mercy Hospital and Mercy Foundation, Miami, Fla; Zimmer, Inc, Warsaw, Ind; and Arthritis Surgery Research Foundation, Inc, Miami, Fla.

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    Copyright © 2008 Published by Elsevier Inc.