Correlation between post-operative knee swelling and pain, maximal voluntary muscle contraction, and function following ACL reconstruction: a longitudinal study

<ns3:p>Background Postoperative knee swelling (PKOS) following anterior cruciate ligament reconstruction (ACLR) is known to contribute to deficits such as pain, swelling, reduced range of motion (ROM), and strength, impeding quadriceps activation, inducing arthrogenic muscle inhibition (AMI), and delaying rehabilitation. This study aimed to explore the association of PKOS with pain, ROM, maximum voluntary contraction (MVC), and functional outcome after ACLR. Methods Thirty-two subjects undergoing ACLR were recruited for this study. PKOS, pain, ROM, and MVC were measured on days 0, 1, 2, 3, 2nd week, and 6th week, while functional outcome was assessed using the Lower Extremity Functional Scale (LEFS) after 2 weeks and 6 weeks. Girth measurement was taken to assess swelling, pain was assessed using a visual analog scale (VAS), and MVC was analyzed using surface electromyography<ns3:sup>®</ns3:sup>. Results Mean values for PKOS, VAS, ROM, MVC, and functional outcome showed overall improvement from day 0 to week 6, except for MVC values, which exhibited fluctuations from day 2 to day 3. However, no significant association (p > 0.05) was found between PKOS and pain, ROM, MVC, and functional outcome. Conclusion While PKOS improved along with other variables over the recovery period, it exhibited no significant correlation with pain, ROM, strength, or functional outcome post-ACLR, warranting further investigation. <ns3:bold>Registration</ns3:bold>: Clinical Trial Registry (CTRI/2022/03/041101).</ns3:p>