Medial meniscus (MM) posterior root tear (PRT) results in joint overloading and degenerative changes in the knee. MM root repair is recommended to prevent subsequent cartilage degeneration following MMPRT. Favorable clinical outcomes have been reported after transtibial pullout repair of MMPRT. However, it is unclear whether pullout repair can cause compositional change in the MM posterior segment. We examined this question in 14 patients who underwent MMPRT pullout repair. Magnetic resonance imaging examinations were performed preoperatively and 3 months postoperatively at 10° knee flexion. The region-of-interest was marked along the MM posterior segment edge. Intra-meniscal signal intensity (IMSI) was expressed as the signal intensity ratio of the repaired MM to the intact lateral meniscus, which was used as a control. MMPRT pullout repair reduced IMSI from 1 to 0.915±0.096 (range, 0.760-1.074) 3 months postoperatively (p=0.006, power=0.90). Meniscal degeneration causes high proton density-weighted imaging signal intensity of the meniscal body. In our study, MMPRT pullout repair reduced IMSI contrary to other tears. This technique may decrease the MM posterior segment signal intensity by restoring the hoop tension mechanism. Measuring IMSI may be useful to assess the effect of MMPRT pullout repair on meniscal healing.