Abstract: Background: Precise pre- and postoperative measurements of limb alignment are necessary to plan and evaluate the success of TKA. There is a wealth of published literature attesting to the precision of intraoperative navigation systems over radiographic measurement as ― gold standard for TKA alignment.
Aims and Objectives: (1) To evaluate the strength of the association between standard pre- and postoperative radiographic and intraoperative navigation alignment measurements; (2) To determine the potential sources of error inherent to the process of radiographic and navigated alignment assessment; and (3) To examine the subtle differences that exist between desired alignment (anteroposterior [AP] mechanical axis and clinically accepted alignment (final alignment after the bone cuts were made and implants placed) as assessed through an intraoperative navigation system.
Material and Methods: The study was conducted from April 2015 to May 2017. Data from a total of 60 consecutive total knee arthroplasties were included. Clinical measurement, radiographic measurement, computer navigation system measurement were carried out. BrainLab IV navigator was used in all cases.
Results: Prior to surgery: The mean varus deformity as assessed on navigation was significantly lower in the navigation in comparison to the clinical assessment as well as by x-ray (p<0.05), while varus deformity assessment done clinically and by x-ray was found to be comparable (p>0.05).
After surgery: The mean deformity was significantly higher on clinical assessment and X-ray (valgus) in comparison to the navigation (varus) (p<0.05). Mean valgus deformity clinically was more in comparison to the X-ray (p<0.05).
Conclusion: Advantages include improved restoration of joint line, reduction in peri-operative blood loss, better results with extra-articular deformities. Complications associated with navigation are rare. Better alignment improves functional outcome and long-term survival of prosthesis.
