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Collagen Membranes for Host-Graft Integration: An Animal Study

Purpose. To evaluate the biocompatibility of collagen membranes for host-graft integration. Methods. 18 Achilles tendons in 9 rats were used. Five tendons were controls and repaired with prolene 3–0 sutures only. The remaining 13 tendons were cases, and a 10-mm section was excised. A 15×5 mm bovine pericardial collagen membrane (Tutomesh; Tutogen Medical, Germany) was laid circumferentially around the tendon and secured with prolene 3–0 sutures. Tendons were harvested after 4 and 6 weeks. Only the repair interfaces (i.e. cut ends and immediate surrounding tissue) were evaluated. Integration of the membranes to the tendons was evaluated using a semi-quantitative wound maturation scale (1–4) based on the presence of inflammatory cells, vascularisation, fibroblasts, and the amount and alignment of collagen fibrils. The presence of fibroblasts and vascularisation were positive parameters, whereas inflammatory cell ratios were regarded as negative parameters. Immunohistochemical study was also performed. Results. There was no host-graft reaction or wound complication (infection, abscess or seroma). Histological and immunohistochemical assessment confirmed re-approximation of the cut tendon ends and incorporation of the membrane onto the tendon as early as week 4. At week 4, the mean maturation scale scores were 2.7 for controls and 3.3 for cases (p=0.11). At week 6, the corresponding values were 3.8 and 3.0 (p=0.004). A reparative process involving formation of blood vessels and invasion by fibroblasts was noted in both control and case tendons. In controls, T- and B-lymphocytes were present. In cases, inflammatory cells were noted at the junction of the host and membrane without invasion of the graft material. There was no lymphocytic infiltration on the graft. The foreign body reaction was localised and minimal. Conclusion. The collagen membrane achieved favourable host-graft integration as early as week 4, with a minimal foreign body reaction.