Total knee arthroplasty: does ultra-early physical therapy improve functional outcomes and reduce length of stay? A retrospective cohort study

Background: The Enhanced Recovery After Surgery (ERAS) Society recommends that after total knee arthroplasty (TKA), patients should be mobilized early. However, there is no consensus on how early physical therapy should be commenced. We aim to investigate whether ultra-early physical therapy (< 12 h postoperatively) leads to better outcomes.

Methods: This is a retrospective cohort study of 569 patients who underwent primary TKA from August 2017 to December 2019 at our institution. We compared patients who had undergone physical therapy either within 24 h or 24-48 h after TKA. Further subgroup analysis was performed on the < 24 h group, comparing those who had undergone PT within 12 h and within 12-24 h. The outcomes analyzed include the Oxford Knee Scoring System score, Knee Society Scores, range of motion (ROM), length of stay (LOS) and ambulatory distance on discharge. A student's t test, chi-squared test or Fisher's exact test was used where appropriate, to determine statistical significance of our findings.

Results: LOS in the < 24 h group was shorter compared to the 24-48 h group (4.87 vs. 5.34 days, p = 0.002). Subgroup analysis showed that LOS was shorter in the ultra-early PT (< 12 h) group compared to the early PT (12-24 h) group (4.75 vs. 4.96 days, p = 0.009). At 3 months postoperatively, there was no significant difference in ROM, ambulatory distance or functional scores between the < 24 h group and 24-48 h group, or on subgroup analysis of the < 24 h group.

Conclusion: Patients who underwent physical therapy within 24 h had a shorter length of stay compared to the 24-48 h group. On subgroup analysis, ultra-early (< 12 h) physical therapy correlated with a shorter length of stay compared to the 12-24 h group (4.75 vs. 4.96 days, p = 0.009) - however, the difference is small and unlikely to be clinically significant. Ultra-early (< 12 h) physical therapy does not confer additional benefit in terms of functional scores, ROM or ambulatory distance. These findings reinforce the importance of early physical therapy after TKA in facilitating earlier patient discharge.