Abstract
Objectives:
The objective of this study was to assess medial meniscal root architecture and structural integrity and determine if the addition of a centralization suture to a transtibial medial meniscus root repair (MMRR) can decrease meniscal extrusion in the early postoperative timeframe via high field MRI.
Methods:
This was an IRB approved and NIH-funded prospective Level I study performed for patients with an isolated type II medial meniscal root tear. Patients undergoing a MMRR were randomly selected to undergo a transtibial repair with or without a centralization stitch. A power analysis determined that 24 patients were necessary for the study. Preoperative and 6-month postoperative imaging were performed using an FDA approved 7T MRI scanner. For morphological evaluation, the MRI protocol included T1- and T2-weighted turbo-spin echo sequences, along with a T2-weighted 3D SPACE with and without fat suppression. For quantitative meniscal assessment, a 3D multi-echo gradient recalled echo sequence was acquired for T2* relaxation time mapping. Manual 3D segmentation was performed on T2*-weighted images to capture the medial meniscus 3D structure. Medial meniscus extrusion was measured pre- and 6 months postoperatively on coronal T2-weighted images using two vertical lines at the peripheral margins of the medial tibial plateau and the outermost edge of the meniscal body.
Results:
Twenty-four patients, mean age: 52 years; age range: 34-62 years; mean body mass index: 27.8 kg/m2; 21 females) were included. All MMRRs were found to have healed on MRI. Comparing the volumes, the medial meniscus was significantly larger in post-MMRR patients. There was a strong correlation between quantitative MRI mapping and meniscal extrusion; extrusion measurements taken from post-MMRR patients were significantly correlated with quantitative MRI mapping values comparing pre-MMRR (r=0.826; p<0.001) to post-MMRR (r=0.732; p=0.002) patients (Figure 1).
Postoperative extrusion increased in 22/24 (91.7%) patients. The centralization group had an average increase of 0.7 mm (18% increase) of extrusion postoperatively compared to preoperatively (p=0.017) (Figure 2). The no centralization group reported an average increase of 1.6 mm (48% increase) of extrusion postoperatively compared to preoperatively (p=0.002) (Figure 3). There was so significant difference between the centralization stitch and no centralization stitch groups (p = 0.068) Additionally, there was significantly less variance in extrusion in the centralization group compared to the no centralization group, 0.67 mm versus 2.11 mm, respectively (p=0.039) (Table 1).
Conclusions:
Elevated quantitative MRI values in the posterior horn of the medial meniscus reflected a disrupted collagen fiber network due to increased tissue hydration, proteoglycan breakdown, and enlargement of the menisci in post-MMRR patients. The use of a centralization stitch did not significantly decrease postoperative medial meniscus extrusion. Increased extrusion after a MMRR was due to degenerative intrameniscal biochemical changes. The use of a centralization stitch can help in reducing this extrusion, but more research is required to determine the proper number, placement, and technique of centralization sutures to minimize postoperative medial meniscus extrusion.
