[Impact of differences of posterior condyle cartilage wear on rotational positioning of femoral prosthesis in total knee arthroplasty for osteoarthritis patients].

OBJECTIVE

To investigate the impact of difference between the medial and lateral posterior condyle cartilage thickness on osteotomy in total knee arthroplasty (TKA) by measuring the thickness of the medial and lateral femur posterior condylar cartilage and the posterior condylar angle (PCA) in osteoarthritis (OA) patients.

METHODS

Between May and December 2011, 53 OA patients (60 knees) scheduled for TKA met the inclusion criteria (OA group). There were 12 males (14 knees) and 41 females (46 knees), aged 57-82 years (mean, 71.9 years). The tibiofemoral angle was (183.2 +/- 2.6) degrees. Fifteen healthy volunteers (30 knees) were taken as controls (control group); there were 6 males and 9 females, aged 59-68 years (mean, 66.3 years). MRI scan data were imported into Mimics 10.01 medical image control system to measure the thickness of femur posterior condylar cartilage and the PCA with and without femur posterior condylar cartilage.

RESULTS

In the control group, the thickness of the medial and lateral femur posterior condylar cartilage was (1.85 +/- 0.33) mm and (1.92 +/- 0.27) mm respectively, the PCA with and without femur posterior condylar cartilage was (5.0 +/- 0.9) degrees and (5.1 +/- 0.8) degrees respectively, all showing no significant differences (P > 0.05). In OA group, the thickness of the medial and lateral femur posterior condylar medial cartilage was (0.45 +/- 0.40) mm and (1.78 +/- 0.51) mm respectively, the PCA with and without femur posterior condylar cartilage was (3.3 +/- 1.7) degrees and (4.8 +/- 1.8) degrees respectively, all showing significant differences (P < 0.05). In OA group, the difference between lateral and medial cartilage thickness was (1.33 +/- 0.45) mm, and the difference between PCA with and without femur posterior condylar cartilage was (1.5 +/- 1.3) degrees. There was a positive correlation between the difference of cartilage thickness and the difference of PCA (r = 0.75, P = 0.01).

CONCLUSION

There is significant difference between medial and lateral femur posterior condylar cartilage wear, which leads to difference of PCA. The difference will impact knee function and longevity of the prosthesis, so the difference should be considered during osteotomy.