INTRODUCTION

We wanted to assess the possible correlation between the intra-operative kinematics of the knee and the clinical results after total knee replacement (TKR).

We wanted to assess the possible correlation between the intra-operative kinematics of the knee and the clinical results after total knee replacement (TKR).

187 cases of TKR implanted with help of a navigation system for end-stage osteoarthritis have been prospectively analyzed. There were 127 women and 60 men, with a mean age of 71 years. Indication for TKR was osteoarthritis in 161 cases and inflammatory arthritis in 26 cases.

A floating platform, PCL preserving, cemented TKR was implanted in all cases. A non-image based navigation system was used in all cases to help for accuracy of bone resections and ligamentous balancing. The standard navigation system was modified to allow recording the three-dimensional tibio-femoral movement during passive knee flexion during the surgical procedure. Two sets of records have been performed: before any intra-articular procedure and after final implantation. Only antero-posterior femoral translation (in mm) and internal-external femoral rotation (in degrees) have been recorded. Kinematic data have been analyzed in a quantitative manner (total amount of displacement) and in a qualitative manner (restoration of the physiological posterior femoral translation and femoral external rotation during knee flexion). Clinical and functional results have been analysed according to the Knee Society scoring system with a minimal follow-up of one year. Statistical links between kinematic data and Knee Society scores have been analysed with an ANOVA test and a Spearman correlation test at a 0.05 level of significance.

101 knees had a posterior femoral translation during flexion before and after TKR. 18 knees had a paradoxical anterior femoral translation during flexion before and after TKR. 51 knees had the pre-TKR paradoxical anterior femoral translation corrected to posterior femoral translation after TKR. 14 knees had the pre-TKR posterior femoral translation modified to a paradoxical anterior femoral translation after TKR. 91 knees had a femoral external rotation during flexion before and after TKR. 34 knees had a paradoxical femoral internal rotation during flexion before and after TKR. 50 knees had the pre-TKR paradoxical femoral internal rotation corrected to a femoral external rotation after TKR. Nine knees had the pre-TKR femoral external rotation modified to a paradoxical femoral internal rotation after TKR. There was a moderate statistical link between the reconstruction of a physiological kinematics after TKR and the Knee Society scores, with higher scores in the group of physiological kinematics after reconstruction. There was no correlation between the quantitative data and the Knee Society scores.

To record the knee kinematics during TKR is feasible. This information might help the surgeon choosing the optimal reconstruction compromise. However, it is not well defined how to influence final kinematics during knee replacement. The exact influence of the quality of the kinematic reconstruction measured during surgery on the clinical and functional results has to be investigated more extensively.

Purpose of the study: For symptomatic discoid meniscus, the treatment of choice in children is arthroscopic meniscoplasty. The treatment of associated meniscal lesions remains a subject of debate. The purpose of our work was to evaluate our results with arthroscopic meniscoplasty associated with meniscal repair as needed and the findings of the systematic postoperative MRI.

Material and methods: This was a retrospective series of patients treated by one operator. There were 23 discoid menisci (21 patients) treated from 2004 to 2007 with arthroscopic meniscoplasty followed by a complementary procedure depending on the residual meniscus: abstention if there was no associated lesion, suture or reinsertion for reparable lesions, partial meniscectomy for non-reparable lesions. The Lysholm and Tegner scores, plain x-rays, and MRI were obtained systematically.

Results: Mean age at surgery was 9.8 years. The Watanabe classification was I:9, II:9, III:5. Arthroscopy revealed 15 lesions, including 11 longitudinal tears. Meniscoplasty was performed in 9 cases alone, associated with partial meniscectomy in 6 and with repair in 8 (5 cases of disinsertion and 3 tears). Mean follow-up was 37.1 months. The mean postoperative Lysholm was 87.9, the Tegner 5.9. Outcome was considered satisfactory or very satisfactory by 90% of patients. MRI failed to reveal any signs of chondral degeneration or meniscal tear. There were however four cases of high intensity intra-meniscal signals and one meniscal cyst. Mean measurements of the residual meniscus were: anterior segment 8.6 mm thickness and 2.6 mm height; middle segment 5.5 and 2.3 mm; posterior segment 5.8 and 3.0 mm. One case of osteochondritis of the lateral condyle was noted postoperatively.

Discussion: To our knowledge, there is no other study evaluating the outcome of discoid meniscus surgery with postoperative MRI. There have been few reports concerning meniscoplasty then repair. This approach spares meniscal tissue, essential for children. We obtained good clinical results and patient satisfaction. At the MRI, the residual meniscus had a morphology close to normal. There were no signs of tears. The high intensity signals occurred in patients with good outcome.

Conclusion: Arthroscopic meniscoplasty associated with repair or partial meniscectomy as needed appears to be a good therapeutic solution for discoid meniscus in children.