The Tendon Exteriorization Cineplasty A Preliminary Report

Robert W. Beasley, M.D.

Surgical Consultant, Child Amputee Clinic, Institute of Physical Medicine and Rehabilitation, New York, New York.

For centuries the medical world has pondered ways in which residual muscles in partially amputated limbs could be used as sources of power for prosthetic replacements.

The first attempts to devise surgical techniques for attaching prostheses to muscles appear to have taken place about the time of the Crimean War, chiefly by the Italians, but little progress was made until World War I. At that time the Germans, notably Sauerbruch, developed the skin-tube-muscle-tunnel cineplasty.

Advantages of Cineplasty

The Sauerbruch system for attaching prostheses to residual limb muscles has been submitted to extensive clinical trials in the United States as well as in Germany. These studies have shown that the cineplastic-powered prosthesis is workable and has certain advantages over more conventional, extrinsically powered devices. These advantages are:

  1. For the below-elbow amputee, the transmission of power is unaffected by the position of the prosthesis, e.g., it is equally good when the artificial arm is in front of the body or raised over the head.

  2. Precise control of prehension is provided, utilizing the normal neurological feedback mechanisms of the intact muscles.

  3. A significant reduction in harness and fixation appliances for the prosthesis is usually possible, resulting in the elimination of shoulder straps for the forearm amputee.

  4. The hand replacement with a cineplastic-operated prosthesis can be of the volutary-closing type, thus providing a more normal action than the voluntary-opening types, which have generally proved more satisfactory with conventional shoulder-powered prostheses.

  5. A cineplastic-operated prosthesis should be mechanically less complex, with a resulting reduction in friction, operating noise, time lags in power transmission, and prosthetic weight.

Disadvantages of Muscle-Tunnel Cineplasty

The medical literature dealing with cineplasties indicates that the muscle-tunnel cineplasty is the only one which has proven workable. Almost all papers reporting on the subject are favorable and enthusiastic about the cineplastic application and give little indication of its problems. Yet the conspicuous absence of cine-plastic prostheses from our amputee clinics attests to serious dissatisfaction with the system.

The chief problems of the muscle-tunnel type cineplasty appear to be:

  1. Dermatological complications with repeated infections, scar contractures, and narrowing of the tunnels.

  2. The muscle-tunnel technique has not lent itself to multiple units on the same extremity nor to the use of small muscles.

  3. By ignoring physiological principles such as normal tissue planes, muscle excursion and power are diminished due to adhesions and the fact that the tunnel is not located at the distal extreme of the muscle.

A New Approach

On the premise that cineplasty is the most logical power source for prostheses and that the key to its successful application lies in a satisfactory linkage system between residual muscles and the prosthesis, a laboratory study of this problem was undertaken (supported by a grant from the Mary Duke Biddle Foundation). Several observations influenced our approach to the problem, which represents a basic departure from the muscle-tunnel cineplastic technique. First among these was the infrequency of dermatological problems with the below-knee patellar-tendon-bearing prosthesis, despite the extreme trauma to which skin is subjected by this weight-bearing device. The second observation was the consistent success achieved with tendon transfers when the transplantation was through physiological tissue planes. Working with mongrel dogs in our laboratory, we devised a tendon exteriorization cineplasty and investigated its physiologic characteristics. The resulting system appears to resolve many of the problems of the Sauerbruch muscle-tunnel cineplasty and its various modifications.

Tendon Exteriorization Cineplasty

Essentially, the tendon of the selected muscle (or a tendon graft substituted for it) is brought above the surface of the limb. A tendon loop is formed and enclosed in a proximally based, tubed, bipedicle flap, the design of which results in minimal interference With normal cutaneous innervation, vascularity, and lymphatic drainage (Illustration 1 ).

The tendon exteriorization cine-plasty has many advantages:

  1. No special procedures for cleaning or ventilating the skin are necessary, thus eliminating a major cause of the dermatological complications associated with muscle-tunnel cineplasty.

  2. The skin of the tendon exteriorization cineplasty has normal cutaneous innervation and optimal circulation, as might be anticipated from the design of the skin flap and as demonstrated in our dogs.

  3. The cineplasty motor units are small, and the number of units which can be constructed on a single extremity is essentially limited only by the amount of skin around the circumference of the limb which can be used for formation of innervated skin flaps.

  4. The system permits selection of a single muscle as the cineplastic motor, or a group of muscles can be combined together with a single tendon loop.

  5. Neither muscle excursion nor power is impaired, since dissection occurs only in physiological planes and no significant adhesions result from the surgery.

  6. The cineplasty units are aesthetically acceptable.

Possible Applications

Thus far our investigations have been confined to the animal laboratory, studying the technique and physiology of the system. No clinical application trials of the tendon exteriorization cineplasty have yet been undertaken. Such trials, of course, will provide the real test of the procedure. However, it has many potential applications, some of which are:

  1. Direct powering of prostheses for the low forearm (long below-elbow) amputee. To use forearm muscles successfully, two units will probably be needed--one to provide the main power for prehension and the other to modulate

  2. the length of the tendon of this primary system, much as wrist motion normally does. A third unit could actively open the terminal device.

  3. The pronator teres lies high in the forearm and might be used with this cineplastic technique to provide active rotational positioning (wrist rotation) in the conventional shoulder powered prosthesis.

  4. Tendon cineplastic units might be used to control externally powered prostheses in a less complex and more practical system than the myoelectric control units currently under development and evaluation in several research centers.

  5. A tendon exteriorization cineplasty unit could possibly be used in the lower extremity, perhaps not for primary power but as a modulating unit to eliminate the troublesome snapping of the prosthetic knee joint as it reaches full extension.

  6. Many other possible applications of the system might be investigated, including its use in some circumstances for prosthetic fixation or stabilization.

Future Plans

In collaboration with the Institute of Physical Medicine and Rehabilitation, we hope shortly to initiate clinical applications in order to investigate some of these possibilities.

Robert W. Beasley, M.D. is Chief of Hand Surgical Service Institute of Reconstructive Plastic Surgery New York University Medical Center New York, New York