Meniscal Injury Does Not Significantly Affect the Dimensions of the Intact Meniscus in the Opposite Compartment of the Knee

BACKGROUND: Meniscal allograft transplant requires precise matching of the size of the allograft with the dimensions of the recipient knee. Estimation of contralateral meniscal size on magnetic resonance imaging (MRI) has been considered the ideal method to measure menisci before transplant. We questioned whether a contralateral intact meniscus with meniscal injury in the opposite compartment could be used as a reference to determine allograft size. Our question was derived from knowledge of meniscal injury influencing structures of the opposite compartment of the knee, including the meniscus. PURPOSE: To compare meniscal dimensions between intact meniscus with meniscal injury in the opposite compartment and normal meniscus with a normal opposite compartment. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This observational, cross-sectional study was performed between 2016 and 2017. The control group consisted of 200 knees with normal medial and lateral menisci. The medial intact group consisted of 150 cases of medial intact meniscus with injured lateral meniscus, and the lateral intact group consisted of 150 cases of lateral intact meniscus with injured medial meniscus. All patients were male. Mean age, height, and weight did not differ among groups. We investigated meniscal dimensions on MRI, including anteroposterior and mediolateral lengths, distance between the anterior and posterior horns (AHPH distance), and widths and heights of the anterior and posterior horns and midbody. RESULTS: Most medial meniscal dimensions were similar between the control and medial intact groups, but the AHPH distance was smaller in the medial intact group (P < .001). Likewise, most lateral meniscal dimensions were similar between the control and lateral intact groups, but the AHPH distance was smaller in the lateral intact group (P < .001). CONCLUSION: Most dimensions of the intact meniscus with meniscal injury in the opposite compartment were similar to those of the normal meniscus with normal opposite compartment. Measuring the dimensions of the contralateral intact meniscus with meniscal injury in the opposite compartment on MRI can be an appropriate method to determine meniscal allograft size.