Summary

We report the clinical results and survival rates at midterm follow up (2 to 10 years) of a novel personalized focal arthroplasty implant used to treat cartilage lesions of the knee

Abstract

Introduction

The treatment of cartilage lesions of the knee can be challenging in middle-aged patients that often present larger and deeper lesions involving the subchondral bone. Personalized focal arthroplasty implants are particularly useful in a population (around 50 years) in which biological repair is no longer considered optimal or when previous biological surgery has failed. Those cobalt-chrome implants, and their associated patient-specific instrumentations, are designed on the specific MRI anatomy of each patient in order to remove only the damaged tissue and to restore the area with a perfectly fitting implant. We report the midterm results (2 to 10 years) of a novel personalized focal arthroplasty implant used to treat cartilage lesions of the knee.

MATHERIAL AND METHODS
Thirty-four patients (13 women, 21 men), with a mean age of 50 years (± 6.9; 24-63) underwent surgery and were followed for at least 2 years after the implantation (mean follow up= 49.4 months, range 24-120 months). In 33 out of 34 patients a single plug was used (23 MFC, 4 LFC, 6 trochlea), while in one case multiple plugs were implanted (trochlea + MFC). Two patients underwent concomitant surgeries (high tibial osteotomy in both). In most of the cases (61.7%) the implantation represented a revision surgery of a failed prior cartilage procedure. For all patients clinical scores (VAS, KOOS and IKDC) were registered at baseline, two years after surgery and at the final follow up. Analysis of the change of clinical scores over time was performed by means of a paired sample Student’s t-test with significance set at p <0.05. Clinical survival rate was determined with failure defined as the removal of the implant an evaluated through a Kaplan Meier analysis.

Results

Statistically significant improvements for all clinical scores (VAS, IKDC, all KOOS subscales) were registered between baseline and the two years follow up. Then those clinical scores remained stable between two years and the final follow up. Specifically, VAS decreased from 6.5 (±2) points to 3(± 2) at 2 years and 2.9 points (±3) at final follow-up, KOOS for Symptoms score increased from 57.3 (±21.5) to 77.8 (±21.9) and 75.5 (±21.8) while IKDC increased from 34.9 (±14.2) at pre-op to 57.8 (±22.9) at two years and 59.5 (±25.7) at final follow-up. Three cases were defined as failures since the implants were removed respectively 0, 24 and 36 months after implantation. Revision consisted in total knee replacement surgery in two cases and unicompartimental replacement in one. Kaplan Meier cumulative survival rate was 91.2%.

Conclusions

This study is the first to report the clinical outcome and survival results up to ten years after the implantation of this personalized focal arthroplasty implant. The presented results depict the safety of this implant, an excellent survival rate of 91.2% at the latest follow up and significant clinical improvements at 2 years after implantation that then remain stable up to the latest follow up.