Long-term outcome follow-up of Oxford unicompartmental knee arthroplasty for medial compartment osteoarthropathy:a single center's experience for 10 years

Abstract

Objective: To investigate the long-term outcomes of minimally invasive Oxford phase Ⅲ unicompartmental knee arthroplasty (UKA) for patients with medial compartment osteoarthropathy. Methods: The clinical data of 594 patients (701 knees) who underwent minimally invasive UKA with Oxford phase Ⅲ unicompartmental prosthesis at Department of Orthopedics,the Affiliated Hospital of Qingdao University from January 2007 to January 2016 were retrospectively analyzed.There were 155 males and 439 females,aged (62.6±10.9) years (range: 44 to 81 years),with a body mass index of (26.9±3.8) kg/m2 (range: 21.1 to 36.2 kg/m2).There were 359 left knees and 342 right knees,676 knees with osteoarthritis and 25 knees with idiopathic osteonecrosis of the medial femoral condyle.There were 487 cases underwent UKA (66 cases underwent UKA on one side and total knee arthroplasty on the other) and 107 cases underwent bilateral UKA.Patients' prosthetic survival,complications,range of motion(ROM) of the knee,visual analogue score (VAS),Western Ontario and McMaster University (WOMAC) osteoarthritis index,and American knee society score (KSS) were collected to assess clinical outcomes.Paired sample t test was used to compare the data before and after operation. Results: All patients completed the surgery successfully.There was no intraoperative fractures,postoperative infections or symptomatic vascular embolic disease occurred.The postoperative complications,including mobile bearing dislocation,prosthesis loosening,tibial plateau collapse,the lateral compartment degeneration and postoperative pain were occurred in 18 cases (3.0%,18/594).Thirteen patients suffered complications were transferred to total knee arthroplasty,4 underwent partial revision,if this was used as the endpoint of the study,the surgical success rate was 97.1% (577/594) and the prosthetic revision rate was 2.9%.The ROM was improved from(105.9±11.8)°preoperatively to (114.0±13.3)° at the last follow-up (t=10.796,P<0.01);the KSS clinical score was increased from 54.3±3.6 to 90.1±6.0 (P<0.01) and the functional score was increased from 55.9±3.9 to 87.5±5.7(t=124.325,P<0.01;t=110.985,P<0.01).The WOMAC osteoarthritis index was decreased from 54.8±6.7 to 9.2±3.1 at the last follow-up(t=150.860,P<0.01) and the VAS was decreased from 6.1±1.1 to 1.5±1.0 at the last follow-up(t=74.941,P<0.01). Conclusions: Minimally invasive Oxford phase Ⅲ UKA for medial compartment knee osteoarthritis has a favorable prosthesis survival rate,low revision rate,and few complications at long-term follow-up.Patients have significant improvement in knee function with satisfactory clinical outcomes.