Greater Axial Trough Obliquity Increases the Risk of Graft Extrusion in Lateral Meniscus Allograft Transplantation

Abstract

Background: In lateral meniscus allograft transplantation (MAT) using the keyhole method, precise trough drilling is critical for ensuring the graft is placed at the correct anatomic position to minimize the risk of extrusion. However, no study has focused on the effect of bony trough axial obliquity on graft extrusion. Our purpose was to investigate whether bony trough axial obliquity and bony trough position correlate with graft extrusion in lateral MAT using the keyhole method. Hypothesis: We hypothesized that drilling the tibial bony trough at a greater axial angle would increase the risk of graft extrusion. Study Design: Case series; Level of evidence, 4. Methods: The study involved 49 patients who underwent lateral MAT between 2009 and 2010 following total or subtotal meniscectomy. The mean patient age at the time of surgery was 34 years (range, 19-52 years). Graft extrusion and bony trough parameters (absolute and relative distance at the anterior, center, and posterior cuttings of the bony trough, and axial trough angle [ATA]) were assessed using conventional magnetic resonance imaging (MRI) performed on postoperative day 2. The correlation between graft extrusion and MRI trough parameters was analyzed, and multiple linear regression analysis was performed to identify predictors of graft extrusion. Results: Of the 7 MRI measurement parameters, the ATA (r = .355, P = .012), absolute anterior distance (r = .301, P = .031), and relative anterior distance (r = .307, P = .032) were found to positively correlate with absolute extrusion. The ATA (r = .296, P = .037) and relative anterior distance (r = .296, P = .039) were also found to correlate with relative extrusion. The ATA was found to be a predictor of absolute extrusion (b = .36, P = .012) and relative extrusion (b = .33, P = .019). Conclusion: The risk of graft extrusion increases as the axial plane trough angle increases. The angle can be reduced by ensuring that the bony trough starting point is not created in too lateral a position.