Midbody of the medial meniscus as a reference of preservation in partial meniscectomy for complete discoid lateral meniscus.
PURPOSE
To evaluate the postoperative size of discoid lateral meniscus using magnetic resonance imaging (MRI) after partial meniscectomy relative to the size of medial meniscus midbody.


METHODS
This study included 48 patients who underwent arthroscopic partial meniscectomy with or without repair for symptomatic complete discoid meniscus. The intraoperative size of midbody of medial meniscus was used as a reference for partial meniscectomy. MRIs were performed pre- and postoperatively. Quantitative evaluations of the height, width, extrusion of the meniscus, and relative percentage of extrusion in the coronal and sagittal planes were completed. Demographic data, preoperative shift, type of shift, and operative technique were analyzed while considering the remaining meniscus. Logistic regression analyses were used.


RESULTS
The mean remaining discoid meniscal width in the coronal plane of MRI was not significantly different from the width of midbody of medial meniscus (9.1 ± 4.2 mm vs. 9.4 ± 1.4 mm, n.s.) Absolute meniscal extrusion and relative percentage of extrusion in the coronal plane and the ratio of t meniscus in sagittal plane of the final MRI were significantly increased as compared with the preoperative MRI. Preoperative shift was a risk factor for the reduction of remaining meniscal width (odds ratio 11.997, p = 0.016, 95% CI 1.586-90.737).


CONCLUSION
The size of midbody of medial meniscus could be a reference for partial meniscectomy in symptomatic complete discoid meniscus. Preoperative shift represents a risk factor for decreased remaining meniscal width. These findings could be helpful in ensuring appropriate surgical planning and explaining poor prognostic factors.


LEVEL OF EVIDENCE
Prospective cohort study, Level II.
['Kim|Seong Hwan|SH|', 'Ahn|JungTae|J|', 'Kim|Tae Wook|TW|', 'Kim|Kang-Il|KI|', 'Lee|Sang Hak|SH|http://orcid.org/0000-0002-6711-6361']
D000328:Adult D015331:Cohort Studies D005260:Female D006801:Humans D008279:Magnetic Resonance Imaging D008297:Male D000074403:Meniscectomy D008592:Menisci, Tibial D011446:Prospective Studies D012016:Reference Values D000070600:Tibial Meniscus Injuries D055815:Young Adult
Medial meniscus Partial meniscectomy Discoid lateral meniscus Magnetic resonance imaging Extrusion