Clinical relevance of active straight leg raising, standing up, and walking after total knee arthroplasty in a cross-sectional study

Background: Active straight leg raising (ASLR) is used to assess restoration of the quadriceps muscle immediately after total knee arthroplasty (TKA). This study aimed to (1) compare the times required to accomplish ASLR, standing up, and walking after TKA, and (2) evaluate the correlation between the time required to accomplish ASLR and perioperative patient-related factors.

Methods: This cross-sectional study included 271 patients (335 primary TKAs performed using the conventional medial parapatellar approach). Postoperative times required until each activity was accomplished were confirmed. Various factors that might impact ASLR, including prosthetic design, were also evaluated.

Results: Post-TKA, it took 1.5 ± 0.5 days to accomplish ASLR, 1.3 ± 0.6 days to accomplish standing up, and 1.4 ± 0.7 days to accomplish walking. There were no significant correlations between any factor and ASLR. Strong correlations were found between the times required to accomplish standing up and walking (p < 0.0001, r = 0.804). There were no significant correlations between the times required to accomplish ASLR and standing up/walking. A longer time was necessary for ASLR accomplishment than for standing up (p < 0.001) and walking (p < 0.001). Standing up was accomplished earlier than walking (p = 0.008).

Conclusions: There was no delay in post-TKA ASLR accomplishment compared with previous reports. No factors affecting ASLR during the perioperative period suggested that ASLR was controlled by factors other than knee joint-related factors. ASLR was not correlated with standing up/walking; hence, the clinical significance of ASLR immediately after TKA for early ambulation is unclear.

Level of evidence: Prognostic study, Level II.