Mid-term results of a new cementless hydroxyapatite coated anatomic unicompartmental knee arthroplasty

Introduction

We report the mid term results of a cement less HA coated unicompartmental knee prosthesis.

Material and methods

One hundred and fifty-nine Unicompartmental knee arthroplasties were done between 1995 and 2000 with ALPINA^® UNI, a cementless HA coated anatomic prosthesis. One hundred and twenty knees were available for the mid-term follow-up at a mean of 6.5 years.

Results

The mean IKS improved from 87.1 ± 22.1 points preoperatively to 168.2 ± 26.1 at the latest follow-up (P < 0.001). Ninety-four percent of the knees were rated good and excellent. The mean knee flexion has significantly improved from 120° preoperatively to 126° at the latest follow-up (P < 0.001). Ten knees were revised: three for degeneration of osteoarthritis in the opposite compartment of the knee, four for polyethylene insert fracture, one for severe polyethylene wear and two for tibial component loosening. When revision for any reason was defined as the end point, the 5-year Kaplan–Meier survival rate was 95.7% (95% confidence interval, 90.1–98.2%) and when revision due to implant mechanical failure (excluding degeneration of osteoarthritis in the opposite compartment of the knee) was defined as the end point, the 5-year survival rate was 96.6% (95% confidence interval, 91.2–98.7%).

Conclusion

This study confirms the reliability of HA coated unicompartimental knee replacement. With careful indications it seems to be a good alternative to osteotomy of total arthroplasty.