[Outcome assessment in total knee arthroplasty: is the clinical measurement of range of motion a reliable measurable outcome variable?]

Abstract

Aim: The aim of this clinical study was to investigate the reliability of the clinical assessment (visual and goniometric) of the range of motion of the knee joint.

Method: 30 patients were assessed concerning the range of motion of their knee joints by visual and goniometric measurements. Assessment was performed by three investigators. The obtained data were used to analyse the intra- and interobserver reliability. Statistical analysis was performed using the Spearman coefficient of correlation [r (s)].

Results: Intraobserver agreement was consistent across observers regarding the visual and goniometric assessment of flexion (r (s) > 0.6), whereas reliability was uniformly low for both measurements regarding the assessment of extension (r (s) < 0.6). Interobserver agreement was consistent across all three goniometric and two out of three visual assessments regarding the measurement of flexion (r (s) > 0.6); the interobserver reproducibility of extension, however, was uniformly low both for the visual and goniometric measurements (r (s) < 0.6).

Conclusion: Reliability of clinical assessment of range of motion should be taken critically into consideration whilst performing classical function-related scoring systems when measuring outcome after total joint arthroplasty, since these scoring systems are strongly based on a valid and reliable assessment of range of motion.