Abstract
Background
Standard implants (PCL retaining or posterior stabilized types) can be used if soft tissue balancing techniques allow the implant to tension and stabilize the joint in flexion and extension. In severe varus, Greater constraint implant may be used. The indications for the use of these components were inability to balance the knee in both flexion and extension because of severe deformities or intraoperative incompetence of the medial collateral ligament after aggressive release.
Material and methods
Fourteen patients with twenty knees had severe varus deformity with average preoperative tibio-femoral angle 25°. The average age was 56 years (from 48 to 64). There was nine males and five females. The pre-operative diagnosis was primary osteoarthritis in 90% of patients and rheumatoid arthritis in 10% (two knees out of twenty). The average follow up was 39 month (from 27 to 57 month). Legacy Constrained Condylar Prosthesis (modular constrained knee of Zimmer) was used in all cases with stemmed both tibial and femoral components.
Results
At the final follow up with average 39 month, the average KSSS was improved from 31 to 89.5. The function knee score was improved from 40 to 80. The tibio-femoral angle improved from average 26° To 8° postoperative. All patients (100%) achieved medio-lateral stability with less than 5° varus-valgus laxity.
Conclusion
Constrained condylar knees function well in patients with severely deformed knees requiring primary TKA especially in elderly and low demanding patients. This study does not recommend and against the use of constrained implants in younger active patients with high physical demands.
