Abstract
Aim: Accurate soft tissue balance in total knee arthroplasty (TKA) is not only technically challenging but also difficult to teach to trainees; we believe that computer navigation provides a very useful tool for objective and reproducible soft tissue balance.
Methods: We studied 52 patients (31 females and 21 males) with knee osteoarthritis and recorded the change of the Medial (MCL) and Lateral Collateral Ligament (LCL) length at full extension and at 90o flexion. Pre- and post-operative results were compared. The assessment was performed by consultant orthopaedic surgeons using trackers and navigation knee replacement software. Data was analysed using the student t-test
Results: The navigation software programme was used to measure the change of the collateral ligament length. Ligament laxity is represented by a negative number and a positive number is used to represent stretching and apparent elongation of the ligament.
The medial collateral (MCL) length at full extension ranged from −9mm to 11mm and post-operatively was reduced to −16mm and 8mm, (p=0.042). At 90o flexion the length ranged from −3mm to 9mm and postoperatively was reduced to −8mm and 10mm (p=0.025).
The lateral collateral (LCL) length at full extension changed from −10mm to 9mm pre-operatively to −13mm and 6mm post-operatively (p=0.011). At 90o flexion the range from −8mm and 9mm pre-operatively changed to − 5mm and 11mm post-operatively (p=0.005).
All the above changes correspond to improvement in the post-operative axial alignment.
Conclusion: Our results demonstrate that computer navigation provides a useful adjunct to the accurate and reproducible soft tissue balance in knee arthroplasty which can be used to evaluate results and for training purposes.
Correspondence should be addressed to Mr T Wilton, c/o BOA, BASK at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.
