Abstract
Background:
Previous studies have shown that the anterior-posterior diameter of the lateral meniscus, measured on sagittal MRI images, is significantly smaller in patients with discoid lateral meniscus (DLM) compared to those with a normal lateral meniscus.
Hypothesis:
The anterior-posterior diameter of the discoid lateral meniscus increases following surgical treatment. The purpose of this study was to evaluate changes in the anterior-posterior diameter before and after surgery in patients with DLM.
Methods:
We retrospectively reviewed 64 knees from 57 patients (32 males, 32 females; mean age, 17.3 years) who underwent arthroscopic surgery for DLM between 2011 and 2020 and had both preoperative and postoperative MRI scans available. The anterior-posterior lateral-to-medial meniscal diameter ratio (ap-LMR) was calculated using sagittal MRI images to assess the anterior-posterior diameter of the meniscus. Comparisons were made between pre- and postoperative values, as well as between complete and incomplete types of DLM, and between patients undergoing partial meniscectomy alone versus partial meniscectomy combined with meniscal repair.
Results:
The ap-LMR significantly increased from 69.5±8.2% preoperatively to 76.0±7.6% postoperatively (p < 0.01). There was no significant preoperative difference in ap-LMR between complete and incomplete DLM (complete: 69.1±7.1%; incomplete: 69.6±9.0%; p = 0.53); however, postoperatively, the complete DLM group exhibited a significantly higher ap-LMR (complete: 79.0±7.6%; incomplete: 73.8±6.9%; p = 0.03). Similarly, no significant difference was found preoperatively between the partial meniscectomy group and the partial meniscectomy with repair group (71.4±9.2% vs. 68.7±7.7%; p = 0.19), whereas postoperatively, the partial meniscectomy with repair group had a significantly higher ap-LMR (80.0±7.9%) compared to the partial meniscectomy group (74.6±7.0%; p = 0.04).
Conclusion:
The observed postoperative increase in ap-LMR in patients with DLM suggests morphological changes that may reflect alteration of hoop function and load distribution following surgical intervention. These findings may provide new insights into the development of new treatment strategies for DLM.