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Abstracts Presented at the 8th Biennial Congress of the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine| Volume 27, ISSUE 10, SUPPLEMENT , e124-e125, October 01, 2011

Paper # 88: The Effects of Platelet Rich Plasma (PRP) on Tendon-To-Bone Tunnel Healing in a Rabbit Model

      Summary

      The purpose of this study was to investigate whether PRP would enhance the tendon-bone attachment because platelets contains growth factors. We demonstrated that PRP had a positive effect when compared to control group on the tendon-to-bone healing at both time points (6 and 12 weeks in a rabbit model). The presence of growth factors in PRP may be the possible mechanism for enhanced healing.

      Abstract

      During the early healing period, the site of tendon graft attachment to bone is the weakest point and graft integration is required for successful reconstruction of the anterior cruciate ligament. Improvement in graft healing to bone is critical to start earlier and more aggressive rehabilitation and an earlier return to work or other activities. Therefore, adequate healing of a tendon graft within the bone tunnel is a major concern.
      The purpose of this study was to investigate whether Platelet Rich Plasma (PRP) injection would reconstitute more favorable tendon anchorage morphology with improved tensile strength in a bone tunnel model. We hypothesized that PRP can enhance the tendon-bone attachment because platelets contains growth factors.
      Thirty-one skeletally mature New Zealand white rabbits were utilized. For the tendon graft healing in a bone tunnel model, the extensor digitorum longus tendon was detached from its femoral insertion and transplanted through a bone tunnel into the proximal tibia. Two groups were compared. For the group P, PRP was injected into the tunnel and the tendon graft that would sit inside the tunnel. For the group C (Control), the limb underwent a similar operation with sham injecting the tendon. Three rabbits for each time points (at 6 and 12 weeks after surgery) were used for microscopic examinations, and 12 and 13 rabbits were used for biomechanical tests in each timepoints. For statistical analysis, Kolmogorov Smirnov and Student's T test were used.
      The interface tissue between bone and tendon was thicker and less organized in group C compared to groups P at 6 weeks. Bone ingrowth into tendon was more obvious in groups P, compared to group C. A well-defined fibrocartilage zone was noted only in group P at the interface at week 12.
      Biomechanical findings: (1) at 6 weeks, the average ultimate load to failure (ULF) and stiffness of group P were significantly higher than group C (P = 0.001). At same time point, in terms of energy absorption, group P was not significantly higher than group C (P = 0.1); (2) at 12 weeks, the average ultimate load to failure (ULF), stiffness and energy absorption of group P were significantly higher than group C (P = 0.002, P < 0.001, and P = 0.001).
      Based on the histological and biomechanical findings, the present study demonstrated that PRP had a positive effect when compared to control group on the tendon-to-bone healing at both time points in an extra-articular bone tunnel in rabbits. The presence of growth factors in PRP may be the possible mechanism for enhanced healing.