Bone tendon junction (BTJ) healing after injury is often slow, without restoration of fibrocartilage transition zone. Fibrocartilage formation has been observed near articular cartilage. It was hypothesised that articular cartilage interposition could stimulate fibrocartilage transition zone regeneration and improve BTJ healing.

Partial patellectomy repair was performed in goat. Articular cartilage harvested from excised patella segment was interposed between the patella and patellar tendon during repair. No cartilage interposition was used in control group. Samples were harvested at six, 12, and 24 weeks for histological examination (n=6 each). The histological images were digitised and analyzed using an image analysis system. Healing progress was assessed by the amount of new bone formation and fibrocartilage transition zone regeneration. Quantitative data were analyzed using SPSS version 14.0. Statistic al significance level was set at p < 0.05.

There was progressive increase in maximum new bone length and area of new bone formed with time (p< 0.05, Kruskal-Wallis test). No difference was observed between treatment groups. Articular cartilage interposition resulted in more fibrocartilage regeneration and higher proteoglycan uptake at all time points. At 24 weeks, length of fibrocartilage formed measured 7760 ± 629 μm with articular cartilage interposition, compared with 787± 274 μm in control (p = 0.002, Mann-Whitney test). Safranin O length measured 3301 ± 1236 μm with articular cartilage interposition, compared with 277 ± 187 μm in control (p = 0.03, Mann-Whitney test).

Autologous articular cartilage interposition stimulates fibrocartilage transition zone regeneration in BTJ repair without affecting bone formation.