Is constraint implant with metaphyseal sleeve a viable option for revision TKR with preoperative coronal plane instability and bone defect?

Abstract

Metaphyseal sleeves have been used as metaphyseal filling implants to address bone loss during revision total knee replacements (TKRs). This study aims to compare the 2-year clinical and radiological outcomes of constraint implant with bone defect and constraint implant without or minimal bone defect in revisions TKR with preoperative coronal plane instability. Seventeen cases of constraint implants with metaphyseal sleeve matched paired with 34 cases of constrained condylar knee (CCK) prosthesis. Age, gender, body mass index and aetiology for revision surgery were recorded. Clinical outcome measures included Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), Oxford Knee Score (OKS), physical component summary (PCS) and mental component summary (MCS). Radiological outcome measures included joint line changes, hip-knee-ankle angle (HKA), coronal femoral angle (CFA) and coronal tibial angle (CTA). Patients in sleeve group showed significant improvement in KSKS, KSFS and OKS (38 ± 7, 35 ± 6 and 20 ± 2 points, respectively, p < 0.001), while they were 19 ± 3 and 6 ± 2 points for PCS and MCS, respectively (p < 0.001 and p = 0.021). These postoperative scores after surgery were similar between the two groups at 6 months and 2 years. The sleeve provides comparable result in joint line restoration; the postoperative HKA, CFA and CTA were all comparable between the two groups. Metaphyseal sleeve with constraint implant is a viable option for revision TKR with preoperative coronal plane instability and significant bone defect. It is able to achieve similar clinical outcomes and joint line restoration compared to CCK prosthesis at 2-year follow-up.