Short-term Outcomes of Semi-constrained Implants in Patients With Complex Primary Total Knee Arthroplasty

Semi-constrained implants are developed to reduce the detrimental impact of constrained implants in patients with complex primary total knee arthroplasty (TKA). However, the outcomes of TKA using semi-constrained implants are mainly unknown. 

This study aims to report the short-term outcomes and complications of primary TKA in patients managed with a semi-constrained implant. 

Twenty-three patients (33 knees) who underwent TKA with semi-constrained implants were included in this study. The outcomes of patients were evaluated radiographically and clinically. Clinical evaluation was performed using the knee society score (KSS) and oxford knee score (OKS) at 6 and 12 months. The subjective satisfaction of the patients was also evaluated at 6 and 12 months using yes/no questions. Postoperative complications were inspected through the patient’s medical records.

The study population included six men and 17 women with a mean age of 70.7±7.6 years. The mean follow-up of the patients was 12.5±4.8 months. The average postoperative ‎tibiofemoral alignment was 0.26±1.1º of valgus (ranging from 3º of valgus to 2º of varus). The mean KSS of the patients were 93.8±8.1 and 94.7±8.3 at 6 and 12 months, respectively. The mean OKS of the patients were 43.6±3.7 and 44.1±3.8 at 6 and 12 months, respectively. All patients were satisfied with the surgery at 6 and 12 months. No postoperative complications were recorded during the follow-up period. 

The use of a semi-constrained prosthesis is safe and effective as a primary implant in TKA ‎patients having severe deformity or ligamentous laxity.