Method for anchoring biomechanical implants to muscle tendon and chest wall.

Reliable tissue fixation is of fundamental importance to the successful development of muscle powered motor prostheses. This report describes a series of canine implant trials used to develop stable tissue-device interface mechanisms. Muscle pumps were fitted with prototype tendon and chest wall anchoring schemes and secured to the ribs and humeral insertion of latissimus dorsi (LD) muscles. LD stimulation was initiated 1 week postimplantation and continued throughout the implant period to stress these fixation sites. Design modification and implant testing were continued until both muscle and chest wall attachment points were found to be stable. Chest wall fixation was best achieved using perforated metallic plates wired to the ribs, as opposed to bone screws or wire mesh, which were subject to degradation. Direct attachment of the native tendon by means of spiked clamping plates proved ineffective. Stable muscle attachment was ultimately achieved by replacing the humeral tendon with an artificial substitute formed from fine polyester fibers gathered into 6-8 bundles and sewn into the LD insertion. Braided into a single cord, these fibers were fixed to the device by means of spiked clamping plates. Based on these findings, we conclude that perforated anchor plates and multifibrous artificial tendons can function as effective tissue-device interface mechanisms.