Abstract
INTRODUCTION
In gap balancing technique, we decided the femoral component rotation according to the ligament balance in flexion. Component and limb alignment are important considerations during TKA. Three-dimensional positioning of TKA implants and exact mechanical axis has an effect on implant loosening, polyethylene stresses, and gait.
According to the recent report, the navigation system made it possible to achieve aligned implants more than conventional TKA. Hybrid Navigation technique which is our procedure is combination of navigation system and modified gap technique. In other words, exact mechanical axis is gained by navigation system, stable stability of knee joint is gained by modified gap technique.
PURPOSE
The purpose of this study is to carry out clinical evaluation and image evaluation of the patients who underwent hybrid navigation technique TKA.
METHODS
We performed TKA using the hybrid navigation technique in 100 knees from April 2012 to April 2015. We evaluated hybrid navigation TKA which we were able to follow up more than five years.
33 knees were available for follow up. We investigated the mid-term results of TKA after a mean follow up period of 5 years and 8 months. We evaluated range of motion(ROM), Japan Orthopaedic Association (JOA)score, complications, revision rate as clinical evaluations. And we evaluated radiolucent line(RLL), loosening in X-ray, implantation accuracy in computed tomography(CT) as image evaluations.
Surgical technique was that the knees were exposed using a medial parapatellar approach without patella turnover, and the anterior and posterior cruciate ligaments were resected. And next osteotomy distal femur and proximal tibia using CT-free Navigation, step-wise medial soft tissue release was performed to make the rectangular extension joint gap using gap tensor space (off set balancer) at 40 pounds of distraction force. Flextion gap was made at the same distraction force, thereby we determined external rotation angle of femur osteotomy in a patella reduction position.
CT of the whole leg was taken preoperation and postoperation the first postoperative week in all cases. RESULTS
In CT evaluation, coronal and sagittal alignments of femoral componet were mean 90.92° and mean flex 3.02°. These alignment of tibial componet were 90.54° and mean posterior slope 3.0°. Outliers(>3°)of coronal aligment were 6% (2 knees)in femoral componet, and 6%(2 knees) in tibial componet.
In clinical evaluation, mean preoperative ROM(flex) was 105 degrees which improved 122 degrees at final follow up. Mean preoperative JOA score was 46.3 which improved 85.8 at final follow up.
In image evaluation, there were no incidence of component loosening(RLL>2mm).
We experienced two complications(1 deep infection and 1 intraoperative fracture), but there were no postoperative fracture and DVT/PE. The revision arte was 3%(1 knee) due to deep infection.
DISCUSSION AND CONCLUSION
Mid-term postoperative results has shown a good prognosis. We will not understand that we do not observe long-term results in future, neverthless we believe that this technique should be considered as an alternative means of conducting TKA.
