Graft extrusion after medial and lateral MAT differs according to surgical technique: a meta-analysis

Introduction: It is unclear whether the incidence and amount of graft extrusion differ between knees undergoing medial and lateral meniscus allograft transplantation (MAT). This meta-analysis, therefore, compared the incidence and amount of transplanted meniscus allograft extrusion following medial and lateral MAT. Materials and methods: All studies comparing absolute or relative extrusions, or proportion of major extrusions (> 3 mm), on magnetic resonance imaging between medial and lateral MATs were included. Results: Eight studies were included in the meta-analysis. Using the arthroscopic-assisted technique, medial MAT had significantly greater absolute (0.99 mm, p = 0.002) and relative (19.4%, p = 0.001) extrusions than lateral MAT. Using the complete arthroscopic technique, lateral MAT had 1.45 mm greater absolute extrusion than medial MAT (p < 0.001), but there was no difference in relative extrusion. Using the arthroscopic-assisted technique, the proportion of knees with major extrusion was greater for medial than lateral MAT (OR 5.32, p < 0.001), but, using the complete arthroscopic procedure, there was no difference in proportions of major extrusions between medial and lateral MAT (OR 0.28, p = 0.08). Conclusion: Graft extrusions after medial and lateral MAT differed according to surgical technique. Graft extrusion was greater after medial than lateral MAT using the arthroscopic-assisted technique, but was greater after lateral than medial MAT using the complete arthroscopic procedure. Level of evidence: Meta-analysis (Level II).