Primary constrained condylar knee arthroplasty in severe varus deformity: a prospective 5-year functional follow-up...

The outcomes of the constrained condylar knee (CCK) implant used during primary total knee arthroplasty (TKA) in knees with severe varus in patients from low- and middle-income countries (LMICs) such as Iraq are not known. Hence, this study aimed to analyze and report the functional outcome of CCK TKA in patients with severe varus deformities at the end of 5 years in Iraqi patients.

In this prospective study, pre- and post-operative (at the end of 5 years) clinical outcome using Knee Society Score (KSS) and radiological deformity using hip-knee-ankle (HKA) angle was analyzed in 76 CCK TKAs (20 bilateral and 36 unilateral TKAs) performed in 56 patients with severe varus deformity (> 15°).

At a mean follow-up of 60.3 months (range 60-68 months), the mean preoperative KSS knee score of 6.6 ± 4.5 improved significantly (p < 0.0001) to 87.2 ± 6.6 and the mean preoperative KSS function score of 7.1 ± 6.4 improved significantly (p < 0.0001) to 70.4 ± 7.8. The function score was good to excellent in 64.3% (36 patients), fair in 28.5% (16 patients), and poor in 7.1% (4 patients) at the end of 5 years. The mean preoperative HKA angle significantly improved (p < 0.001) from 25.5° ± 6° varus (range 17°-37°) to 3° ± 2.5° varus (range 0°-7.5°) at final follow-up.

The CCK implant significantly improved pain and function in patients with severe varus deformity at the end of 5 years. The CCK implant is a good option during primary TKA in severe varus knees in patients from LMICs and can help achieve clinical outcomes similar to patients from high-income countries.