Unicondylar knee replacement versus total knee replacement for the treatment of medial knee osteoarthritis: a systematic review and meta-analysis

Background Since the optimal surgery for isolated medial knee osteoarthritis (OA) is unclear, this study aimed at comparing the effectiveness of unicondylar knee replacement (UKR) with total knee replacement (TKR) for simple medial knee OA. Methods Literature searches of PubMed, Embase, Web of Science, and the Cochrane Library were searched up to 1th April 2020. Only studies comparing UKR with TKR for isolated medial knee OA were included. Data collection and extraction, quality assessment, and data analyses were performed according to the Cochrane standards. Results A total of 13 articles with 1888 patients were included, among which, 944 and 944 underwent UKR and TKR, respectively. The analyzed postoperative outcomes were mostly within 5 years of follow-up. The meta-analysis showed that UKR improved knee general function (P < 0.00001) and health (P = 0.02), moreover, reduced post-operative pain (P = 0.01) and complications (P < 0.05) more than TKR. There were no significant differences in postoperative revision (P = 0.252), high-activity arthroplasty score (HAAS) (P = 0.307) and Oxford knee score (OKS) (P = 0.15) between the two techniques. Conclusions The patients of UKR could achieve better clinical results than that of TKR, moreover, there were negligible differences between the two techniques in postoperative revision in the early and mid-term follow-up and surgeons should be aware of the important reasons for revision of UKR. Thus, UKR instead of TKR should be performed in patients with late-stage isolated medial knee OA.

A Technical Tip to Avert Meniscal Rotation and Dislocation in a Mobile Bearing Unicompartmental Knee Arthroplasty

The Oxford (Oxford® partial knee; Biomet) mobile bearing medial unicondylar knee replacement (OUKR) is a preferred choice by surgeons due to minimal blood loss, reduced pain, and better range of motion. Commonly observed complications include aseptic loosening, polyethylene wear, bearing dislocation, and periprosthetic fractures. A bearing dislocation can be prevented by ensuring that there is correct tracking of bearing during the trial reduction as well as no loss of entrapment. We present a case report in a 50-year-old patient undergoing bilateral OUKR wherein it was observed that the meniscal bearing upon the flexion of the knee joint had the tendency to dislocate. Upon revising the vertical tibial recut according to the anterior superior iliac spine, the meniscus was found to have a normal excursion. Mobile bearing dislocation is a unique complication of mobile bearing OUKR. Surgical technique is of paramount importance in ensuring a successful OUKR. The vertical tibial cut is made to accommodate the vertical wall of the tibial component. Meniscal displacement is quite a common complication and can occur due to multiple causes. Inaccurate vertical tibial cut may be one such reason leading to tibial dislocation.

Comparison of gait kinematics in total and unicondylar knee replacement surgery

Introduction This study is aimed to compare kinematic gait data of patients who have undergone total and unicondylar knee replacement. Materials and methods This single-surgeon retrospective cohort study evaluated 13 patients with unilateral total knee arthroplasty (TKA) and 14 unicondylar knee arthroplasty (UKA). Gait analysis was carried out using a Vicon motion analysis system. The limits of knee flexion during stance phase, at heel strike and at loading response were measured. Results The total range of motion of the UKA knees was significantly greater than the TKA knees. UKA knees exhibited significantly greater knee extension during the stance phase than the TKA knees. Unlike TKA, UKA knees demonstrated improved knee flexion during the gait cycle when compared to the contralateral non-operated knee. The hips also demonstrated near normal hip flexion in UKA patients. Predictably, UKA knees had significantly greater varus compared with TKA in the coronal plane. Spatiotemporal variables demonstrated similar walking speed and step length to aid a fair comparison between knee replacement groups. Conclusions The UKA knees moved more physiologically in the sagittal plane with a greater range of motion during gait. Despite having a stiff gait pattern, the patients undergoing TKA demonstrated a more neutral alignment in the coronal plane. Neither type of knee arthroplasty restored knee kinematics to those of the non-operated side.