An Analysis of the Correlation Between Component Placement and Functional Outcomes by Using Orthoscanogram in Primary Total Knee Arthroplasty

Introduction Total knee arthroplasty (TKA) is a well-established surgical treatment for advanced knee osteoarthritis, with the goals of relieving pain, restoring function, and improving the patient’s quality of life. Accurate alignment and optimal component placement are key determinants of implant longevity and postoperative functional outcomes following TKA. Restoration of the neutral mechanical axis of the lower limb is thought to minimize abnormal stresses on the prosthesis and surrounding bone. An orthoscanogram provides an accurate and reliable method for assessing the mechanical axis and overall axial alignment of the lower extremity. This study aimed to evaluate the correlation between component placement, assessed using orthoscanogram, and functional outcomes following primary TKA. Methodology This was a hospital-based comparative study conducted at Vydehi Institute of Medical Sciences and Research Centre, Bengaluru. A total of 60 patients with primary knee osteoarthritis who underwent primary TKA were included based on predefined inclusion and exclusion criteria. Full-length standing orthoscanograms were obtained preoperatively and postoperatively to assess mechanical axis alignment and component positioning using tibial zone classification. Functional outcomes were evaluated using the Knee Society Clinical Score (KSCS) and Knee Society Functional Score (KSFS) at a minimum follow-up of six months. Statistical analysis was performed to assess the association between mechanical axis alignment and functional outcomes. Results Postoperative orthoscanogram analysis demonstrated that patients in whom the mechanical axis passed through Zone 2 and the central (Zone C) of the tibial plateau showed significantly superior functional outcomes. According to the KSCS, the majority of patients achieved excellent to good results. Similarly, KSFS showed marked improvement postoperatively, particularly in patients with near-neutral mechanical alignment. A positive correlation was observed between optimal component placement, restoration of the mechanical axis, and improved functional outcome. Conclusions Accurate restoration of the mechanical axis and optimal component placement in primary TKA significantly influence postoperative functional outcomes. Orthoscanogram is a valuable and reliable tool for assessing lower limb alignment and component positioning. Postoperative mechanical axis passing through Zone 2 and the central zone is associated with excellent functional results. Emphasis on precise alignment during TKA can enhance patient satisfaction and potentially improve implant longevity.