Clinical outcome is not affected by total knee arthroplasty alignment

Purpose: This study aims to analyse the influence on total knee arthroplasty (TKA) clinical outcomes of biomechanical intra-operative computer-assisted surgery-measured parameters, together with radiographic and demographical data. Methods: Between 2007 and 2009, 227 computer-assisted surgery (CAS) primary TKAs were performed in 219 consecutive patients. Information about gender, age and body mass index (BMI) was collected for each patient. Before knee replacement, all patients underwent a complete radiographic examination and passive flexion–extension range of motion was recorded. All TKAs were implanted using an image-free knee navigation system. Patients included in the study were evaluated at 3, 6 and 12 months of follow-up and then yearly. At each follow-up, subjects were asked to answer the validated Italian version of the Knee Injury and Osteoarthritis Outcome Score. Results: One hundred and eighty patients (187 knees) had data available for analysis. Complications were reported in 13 patients (7.0 %). Intra-operative CAS-measured parameters, together with age, BMI, gender, pre- and post-operative radiographic alignment, did not influence TKA clinical results at a mean 2 years of follow-up. On the other hand, higher post-operative flexion arc of movement was suggestive of better clinical outcomes. Conclusion: TKA clinical outcome is influenced by post-operative knee flexion, other than neutral mechanical limb alignment. Therefore, it is recommended to prefer TKA designs that allow high flexion and to encourage early physical rehabilitation. Level of evidence: IV.