Background: It is important to restore the normal anatomy of the native meniscus in meniscal allograft transplantation (MAT) for successful surgical results.
Purpose/hypothesis: The purpose of this study was to compare the anatomic positions of the anterior horn (AH) and posterior horn (PH) between the preoperative lateral meniscus and postoperative meniscal allograft after lateral MAT using the keyhole technique. We hypothesized that the keyhole technique could restore the preoperative anatomy of the native lateral meniscus.
Study design: Case series; Level of evidence, 4.
Methods: Between December 2012 and December 2014, a total of 70 patients underwent lateral MAT using the keyhole technique. The anatomic positions of both horns of the native lateral meniscus and the meniscal allograft were measured on magnetic resonance imaging (MRI). Preoperative MRI was performed 1 day before lateral MAT, while postoperative MRI was performed 2 days after lateral MAT. A percentage reference method was used to measure the location of both horns.
Results: For the AH, the mean delta value of the absolute position was 0.7 ± 1.8 mm (95% CI, 0.3-1.1 mm) in the coronal plane and 0.5 ± 1.6 mm (95% CI, 0.2-0.9 mm) in the sagittal plane, and the mean delta value of the relative position was 1.0% ± 2.3% (95% CI, 0.5%-1.6%) in the coronal plane and 1.1% ± 3.3% (95% CI, 0.2%-1.8%) in the sagittal plane. For the PH, the mean delta value of the absolute position was 2.4 ± 2.6 mm (95% CI, 1.8 to 3.1 mm) in the coronal plane and -0.1 ± 2.1 mm (95% CI, -0.6 to 0.4 mm) in the sagittal plane, and the mean delta value of the relative position was 3.3% ± 3.5% (95% CI, 2.5% to 4.2%) in the coronal plane and -0.3% ± 4.4% (95% CI, -1.3% to 0.8%) in the sagittal plane. Therefore, the AH moved by a mean of 0.7 mm laterally and 0.5 mm anteriorly (absolute values) and 1.0% laterally and 1.1% anteriorly (relative values) compared with the preoperative position. The PH moved by a mean of 2.4 mm laterally and 0.1 mm posteriorly (absolute values) and 3.3% laterally and 0.3% posteriorly (relative values) compared with the preoperative position. For the AH, the proportion of patients with an absolute delta value of ≥5 mm was 4.3% in the coronal plane and 2.9% in the sagittal plane. For the PH, the proportion of patients with an absolute delta value of ≥5 mm was 18.6% in the coronal plane and 4.3% in the sagittal plane.
Conclusion: When comparing the position of the horns preoperatively and postoperatively, both horns showed mean relative postoperative positional changes of <5% of relative values and <5 mm of absolute values in both the coronal and sagittal planes. The keyhole technique in lateral MAT can reconstruct the lateral meniscus close to its native anatomic position by avoiding displacement of >5 mm in both the coronal and sagittal planes.
Keywords: anterior horn; lateral meniscus; meniscal allograft transplantation; posterior horn.
© 2016 The Author(s).