Subjective and objective outcome measures after total knee replacement: is there a correlation?

BACKGROUND: Although various methods for quantifying outcomes following total knee replacement (TKR) are used, there are few studies of the relationships between patient reported scores and functional tests. This paper aims to assess the relationships between commonly used outcome scores after TKR through a prospective cohort study.

METHODS: Twenty-four patients who had undergone unilateral TKR were assessed using four patient-reported outcome scores as well as objective measurements of knee laxity, quadriceps muscle strength and the Timed Up and Go Test. All scores and measures were correlated using the Pearson product moment correlation coefficient using the lower one-sided 95% confidence interval. A level of significance of P < 0.05 was selected.

RESULTS: The Timed Up and Go Test was the only objective measure to demonstrate a statistically significant correlation (r = -0.557 to -0.770, P = 0.0001-0.005) with patient-reported scores.

CONCLUSION: A comprehensive assessment of outcomes after TKR requires both subjective and objective assessments. Walking ability and speed are important to the TKR patient and are representative of their pain and function.