[Mid-Term Results of Unicompartmental Knee Replacement Using Oxford Phase III System]

PURPOSE OF THE STUDY Partial knee replacement appears to be an appropriate surgical solution of unicompartmental knee joint osteoarthritis in correctly indicated cases. The purpose of our study was to evaluate the mid-term outcomes of unicondylar knee replacement using the Oxford Phase III system in the group of patients treated by the First Department of Orthopaedic Surgery, St. Anne s University Hospital Brno. MATERIAL AND METHODS The prospective study evaluated 47 patients (in 4 patients bilaterally) after the Oxford unicompartmental knee replacement performed between 2011 and 2016. The patients were evaluated using the Knee Society Score (KSS), Oxford Knee Score (OKS) and radiological examination performed at 7.3 years after surgery on average. All the patients were operated on by the same surgeon. RESULTS Based on the questionnaires and the clinical examination, the clinical and functional status was assessed, using the Knee Society Score (KSS). The mean preoperative KSS and FS values were 59.8 and 56.5, respectively. The postoperative KSS and FS values were 91.2 and 83.4. The mean preoperative value of the Oxford Knee Score (OKS) was 27.3. Postoperatively the values reached 40.7 on average. Based on the radiological examination, the lower limb correction of axis in the frontal plane was assessed. The mean axis correction was 3.1°. The mean tibial component slope measured on lateral radiograph was 82.7°. The basic analysis of X-rays did not reveal any component malposition. The implant survival rate was calculated using the Kaplan-Meier cumulative survival curve. In our group of patients, the mean survival rate of Oxford Phase III unicondylar knee replacement at 7.3 years postoperatively is 98.0%. DISCUSSION Many studies have reported excellent results of unicondylar knee replacement and a long survival rate of over 90%. Still debated, however, are the indication criteria and also the importance of the surgeon s experience and mastery of the surgical technique. CONCLUSIONS The results of the study confirm our excellent clinical experience and the survival rate of 98% at the mean follow up of 7.3 years after surgery shows great promise for quality long-term results. Overall, crucial for the success of UKR continues to be the compliance with the indication criteria for surgery. The choice of the type of implant and, last but not least, the correct surgical technique and postoperative rehabilitation programme are also important. Key words: unicompartmental knee replacement, Oxford Phase III, osteoarthritis of the knee.