| I . Background:Adhesion after tendon repair is the most important fact which impedes the full functional recovery. For this reason, it is the most challenging subject in hand surgery how to reduce the incidence of the tendon adhesions. The incidence of tendon adhesion after tendon repair is very high. Some reports presented a high adhesion rate up to 23%~76%.Since 50's century, there has been a controversy about the basic mechanism of the tendon healing. The extrinsic healing school held that tendon lacks ability to heal by its own cells, and depend upon migration of cells and blood vessels from the surrounding tissues for heeling process. Thus tendon adhesion is inevitable and essential for tendon healing. On the contrary, the intrinsic healing school claimed that tendons heal mainly by the cell proliferation, migration, differentiation and collagen synthesis of its own. However, the most accepted opinion recently is that the tendon itself and the surrounding tissues all contribute to the tendon healing. Or, the intrinsic and extrinsic mechanism all takes part in tendon healing process. But the intrinsic and the extrinsic play different roles in the tendon healing. Whether intrinsic or extrinsic mechanism is prevailing in the process of the tendon healing depend on the local circumstance. Hence the key to improve the tendon repair results lies in promoting intrinsic tendon healing and inhibiting extrinsic healing process and so as to result in a solid tendon healing without adhesion.Theoretically, inhibiting extrinsic tendon healing process with mechanical barrier is the most effective and direct way to prevent adherence formation. Nevertheless, little material having been tried so far are applicable and effective in clinics though some of them showed good promise in preventing tendon adherence experimentally. The causes of unsatisfied results in clinics way be interpreted as follows: (1) Some jelly like materials such as hyaluronate, chitosan stay around tendons too short duration toprevent the adherence formation. (2) Filmy materials can prevent the ingrowths of the surrounding granulation tissue but they also impeded the process of tendon healing. Thereby the tendon healing cannot accomplish until the barrier material has degraded, and then the tendon adherence occurred consequently. So they cannot act as real adhering-preventing barriers. (3) Tendon sheath repair with autogenous fascial patch, veins, or other autogenous tissues could not achieve good results because of the organization of these tissues and granulation formation around them. On the other hand, tendon sheath repaired with artificial materials such as polytetraflorethylene (PTFE) film, biologic film, poly-lactic-acid film, alumina sheath showed no good outcome may be attributed to the tissue rejection to the foreign substance or the granulation ingrowth to the tendon through the space around the implant.To sum up, an ideal adhering-preventing barrier should possess following properties: (1) Tt can separate the healing tendon from surrounding tissue all around, or it should envelop the tendon anastomosis hermetically so as to prevent any ingrowth of granulation in the surrounding tissue. (2) Tt should not interfere with the intrinsic tendon healing process remarkably. (3) The barrier could also plays part role in connecting the two ends of the lacerated tendon and strengthening temporarily the repair site so as to facilitate early mobilization after tendon surgery. (4) The barrier material should be well compatible with tissue biologically and can be degraded after injured tendon healed up. This study was based on above-mentioned opinions, and observation of the tendon healing process and adherence formation within diffusion casing tube was made. The diffusion casing tubes were made of two different degradable high polymers: poly (2,2 dimethyl trimethylene carbonate- @ -caprolactone) [abbr: P ( DMTC-CL ) ], and poly (2,2 dimethyl trimethylene carbonate- @ -caprolactone lactide) [abbr: P (DMTC-CL-LA)].II. Materials and me...
|
PDF Full Text Request