Biomechanical Analysis of Posterior Segmental Medial Meniscal Transplantation in a Human Cadaveric Model

Background: Partial meniscectomy provides short-term symptom relief but may accelerate the development of knee arthritis due to meniscal deficiency and altered joint biomechanics. While meniscal allograft transplantation (MAT) addresses complete meniscal loss, segmental meniscal transplantation may be an option for segmental loss. Purpose: To evaluate the biomechanical effect of segmental posterior medial meniscal transplantation on knee joint loading characteristics and compare it with the states of both intact meniscus and full MAT. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human cadaveric knees (mean age, 54.3 years) were tested under 4 conditions: intact meniscus, segmental medial meniscal loss, segmental posterior horn MAT, and full MAT. The knees were subjected to a 500-N compressive load at 0°, 30°, 60°, and 90° of knee flexion. Medial meniscal extrusion, contact area, mean contact pressure, and peak contact pressure were measured. Statistical analyses included 2-way repeated measures analysis of variance to assess the effects of meniscal state and knee flexion on biomechanical outcomes. Results: Segmental medial meniscal deficiency significantly increased extrusion (+1.32 mm at 0°; +1.45 mm at 30°; +1.42 mm at 60°; and +1.67 mm at 90°) and mean pressure compared with the intact meniscus across all flexion angles. Both segmental transplantation and full transplantation restored extrusion to intact levels, with full transplantation demonstrating superior improvement in peak pressure at flexion angles >60° compared with segmental transplantation. Both segmental and full transplantation restored peak pressure to levels comparable with the intact meniscus at flexion angles ≥30°. Conclusion: Both segmental and full meniscal transplantation tested at the time of surgery restored meniscal extrusion and contact pressure to the intact state. Clinical Relevance: Segmental transplantation may offer a promising approach for managing posterior medial meniscal deficiencies by restoring knee joint function and reducing meniscal extrusion.