The comparison of macroscopic and histologic healing of side-to-side (SS) tenorrhaphy technique and primer tendon repair in a rabbit model.

Introduction: The side-to-side (SS) tenorrhaphy technique has been used in tendon transfer surgery. The mechanical properties of SS tendon suture have been studied previously. However, the histo-pathological healing of the SS tenorrhaphy of the tendons is unknown. The aim of this study was to assess the gross and histological effects of SS tenorrhaphy in a rabbit model.
Materials and Methods: Twenty New Zealand rabbits were used. The extensor hallucis longus and tibialis anterior tendon were sewed SS at the level distal to the ankle joint. The patellar tendon (PT) at the same side was used as control group. A unilateral midline incision was made and repaired with a single suture. The animals were killed at the 12th week postoperatively. The histological sections were obtained from the side of surgery from each group. Each sample was stained with hematoxylene and eosin (H&E). Gross and microscopic healing was compared between the two groups.
Results: Gross examination of the control group showed complete healing with a thin peri-tendinous sheath formation around the suture site, whereas in the study group, a thick peri-tendinous sheath was formed around the area of the tendon-tendon anastomosis. In the control group, at the 12th week after surgery, the healing was almost completed in all samples. In the study group, a thick fibro vascular sheath has formed around the side of anastomosis. In all specimens few inter-digitations were observed between the tendons;however, the trough was still present.
Conclusion: The result of the current study showed that histological healing and union of SS tenorrhaphy differ from that in primary tendon injury and healing. Further studies are required to clarify the healing stages at the tenorrhaphy site.