Background/Purpose: Range of motion (ROM) is an important component of the assessment of total knee replacement (TKR) outcome. Traditionally, ROM is measured by a clinician or trained researcher, making ROM less practical than self-report measures that can be obtained by phone or mail. Recently, Gioe et al. developed a method that presents patients a set of lateral knee photographs depicting varying levels of flexion and extension and asks the patients to select the photographs that most closely resemble their motion. We aimed to compare this self-reported method of assessing flexion and extension with clinical measurement before and after TKR.

Methods: As part of a prospective cohort study of consecutive patients undergoing TKR, patients were asked to self report flexion and extension on their operated knee using the method of Gioe et al. In addition, flexion and extension were measured using a goniometer by a trained research assistant. These measures were obtained preoperatively and at three and six months postoperatively. We compared self-reported ROM category with measured ROM for both flexion and extension using ANOVA. We dichotomized flexion at 90 degrees and determined the sensitivity and specificity of the self-report flexion categories for identifying patients with poor ROM. 

Results: : One hundred and one patients provided both self-report and RA-measured ROM at baseline. There was a significant association between self-report ROM category and ROM measurement for both flexion and extension (P<0.001). The Spearman correlation coefficient was 0.51 for extension and 0.45 for flexion, indicating moderate correlation. We combined all 3 visits to assess sensitivity and specificity of self-report flexion categories. Overall 15 of 25 patients with poor measured flexion (≤90°) also self-reported poor flexion (to 90° or lower) for a sensitivity of 60% and 177 of 190 patients without poor flexion (>90°) did not self-report poor flexion (to 100° or higher) for a specificity of 93%. The negative predictive value for self-report was 95%, indicating that the vast majority of patients self-reporting adequate flexion do not have poor flexion.

Conclusion: Patient self-reported ROM may be a useful outcome measurement for TKR when clinical ROM measurement is not possible. These findings are based on a small sample in one center and should be confirmed. Self-report is particularly effective (>90% specificity) in confirming adequate ROM.

Table 1. Performance of self-report flexion categories for identifying patients with poor ROM 

		Measured Flexion
		≤90°	>90°
Self Report – How well can you bend your knee?	To 90° or lower	15	13
	To 100° or higher	10	177
	Total	25	190
	Sensitivity	60.0%
	Specificity	93.2%
	Predictive Value+	53.6%
	Predictive Value-	94.7%

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-comparison-of-patient-reported-and-measured-range-of-motion-in-a-cohort-of-total-knee-replacement-patients/