Satisfactory Short‑Term Outcomes of Condylar‑Constrained Knee Implants in Primary Total Knee Arthroplasty

Abstract

Background: This research set out to assess the functional prognosis of constrained condylar knee (CCK) in patients with severe intraoperative instability and/or coronal deformity undergoing primary total knee arthroplasty (TKA). Materials and methods: A prospective cohort study including 25 knees (21 cases) who underwent primary TKA using CCK implants. Senior surgeon operated all patients during 2020/2021 and followed clinically and radiographically at three, six and 12 months and 2 years postoperative. All cases were implanted with a single-design, second-generation CCK implant with a mean follow-up of 2 years. Results: The current research involved 25 knees (21 patients) with mean age 62.8 ± 12.2 years and most of the included patients were females (19; 76%). Preoperatively, valgus was demonstrated in six patients (24%) while varus was reported in 19 patients (76%) with mean preoperative Valgus/Varus angle            24.4 ± 9.9. Mean preoperative Knee Society Score (KSS) was 13.2 ± 2.7, mean preoperative functional KSS was 23.8 ± 19.2 and mean preoperative range of movement (ROM) was 107 ± 19.2. After 6 months, mean values of KSS was 86.2 ± 7.59. After 1 year, 2 years & over 2 years, mean values of KSS were 86.2 ± 7.6, 86.2 ± 7.5, 86.3 ± 7.7 respectively. Degree of change in KSS before and after the operation was 69.1 ± 20.9. Mean values of late functional KSS was 62.5 ± 23.3.  Degree of change in functional KSS before and after the operation was 36.8 ± 19.1. Postoperative ROM mean value was 120 ± 6.9 with degree of change 12.8 ± 6.3. Three cases reported postoperative complications; one cellulitis, one anterior femoral notching and one peroneal nerve injury. KSS increased from baseline to early postoperative with statistically significant variances (p< 0.001) however, no statistically significant changes were discovered in KSS from early postoperatively to 2 years of follow up. Conclusion: Primary TKA utilizing CCK implants in cases with severe coronal abnormalities and/or intraoperative instability had a good short-term survival rate, on par with less limited implants. With positive clinical and radiological results, CCK implants can be thought of as a good alternative in some instances. It is important to exercise caution while utilizing an elevated level of restraint, since less restricted implants should be preferred.