Intra-Articular Injection of Parathyroid Hormone (1-34) Enhances Meniscal Healing at the Site of a Radial Tear in the...

In this study, we assessed the efficacy of a single intra-articular injection of parathyroid hormone (PTH) (1-34) to enhance the meniscal healing of a medial meniscal radial tear. A radial tear involving two-thirds of the meniscal width was created in the anterior medial meniscus of the bilateral knees in 30 Japanese white rabbits that were injected with either PTH (1-34) or phosphate-buffered saline. Macroscopic, biomechanical, and histological assessments of the meniscus were performed at 4, 8, and 12 weeks post-surgery. PTH injection resulted in an improved meniscal healing rate at 4 and 8 weeks compared with phosphate-buffered saline (p = 0.05 and p < 0.05, respectively). After 4 weeks, PTH injection led to a higher circumferential strength in biomechanical testing. The meniscal healing score exhibited a trend toward improvement, reaching borderline statistical significance at 4 weeks with PTH injection (1.6 ± 1.3) than with phosphate-buffered saline (0.5 ± 0.8) (p = 0.05). In the outer two-thirds of the meniscal width, picrosirius red staining revealed greater type I collagen content following PTH injection. A single injection of PTH (1-34) into the knee joint improved meniscal healing in a rabbit medial meniscus radial tear model at 4 and 8 weeks, which was accompanied by increased type I collagen content around the healing site.