Abstract
Introduction
As intra-operative fluoroscopic identification of the isometric MPFL attachment to the femur can be imprecise and laborious in a surgical setting, we used clinical criteria to identify the isometric point and then studied post-operative radiographs to find out whether it was achieved and compared it with functional outcome.
Materials and Methods
Sixteen patients underwent 17 MPFL reconstructions using autologous semi-tendinosis tendon graft. Clinical judgement was used to identify the optimal point for femoral attachment of the MPFL without fluoroscopy control. Post-operative radiographs at 2 weeks were analysed to confirm whether an isometric point for the reconstructed MPFL was achieved by dividing the distal femur into 4 quadrants by 2 lines on the lateral radiograph. Telephonic interview was conducted to assess functional scores using the Kujala score at a mean follow-up of 13 months.
Results
In only 4 of the 17 cases, the femoral point of attachment lay in the radiographically isometric (antero-proximal) quadrant. In 8 of 17 knees, the point of MPFL attachment lay in the antero-distal quadrant. However, there was an improvement in the functional score in 14 of 16 patients, with none reporting recurrence of patellar instability. The position of the reconstructed MPFL did not correlate with functional score.
Conclusion
Over-reliance on a clinical method alone for identification of the optimal point for MPFL attachment without an intra-operative radiograph leads to radiographically non-isometric positioning in a majority of cases. In the clinical setting, however, this does not correlate with adverse functional outcome, although intra-operative fluoroscopy may improve the anatomical isometry, and we therefore suggest the use of a qualitative clinical method to achieve optimal
