The Effects of Patient Factors on the Functions and Clinical Results of Unicompartmental Knee Arthroplasty Using an Oxford Mobile Bearing Prosthesis

ABSTRACT

PURPOSE: The purpose of this study was to determine whether the functions and longevity of unicompartmental knee arthroplasty (UKA) are influenced by such patient factors as gender, age, height, weight and the body mass index (BMI) based on a comparative study of the cases. MATERIALS AND METHOD: Among the patients who underwent a UKA using an Oxford(R) phase 3 prosthesis, 154 cases (male 13 cases, female 141 cases) were categorized into two groups by their gender, age, height, weight and BMI, and they were followed-up for at least 5 years after operation. Their mean age, height, weight and BMI were 61.6 years, 154.5 cm, 61.9 kg and 25.9 kg/m2, respectively, and the mean follow-up period was 6 years 7 months. Clinical assessments were done using the Knee Society Score rating system. RESULTS: The average knee and function scores improved from 55.9 and 54.9 preoperatively to 87.9 and 82.4 at the last follow-up, respectively, and the mean range of knee motion improved from 129.7degrees to 133.5degrees. The postoperative knee score, function score and range of knee motion improved significantly in all the groups. The group younger than 60 years old had better function scores preoperatively and the group of taller than 155 cm had a larger range of knee motion postoperatively, but there were no other significant difference. The cumulative survival rate of the implant was 93.3%, and there was no significant difference of the survival rate of the implant according to gender, age, height, weight, and BMI. CONCLUSION: The clinical results of UKA were satisfactory in all the groups regardless of gender, age, height, weight and BMI with a mean of 6 years 7 months follow-up, and there were no significant differences on comparison between each group. Therefore, the mid-term clinical results of UKA using an Oxford phase 3 prosthesis are not influenced by these patient factors.