Application of prosthetics-orthotics principles to treatment of fractures.

1 School of Medicine, University of Miami, Jackson Memorial Hospital, Miami, Fla. 33152. Greater knowledge and understanding of bioengineering by the prosthetics and orthotics industries during the past twenty years have resulted in the development of highly functional and sophisticated appliances. For example, modern prostheses for lowerand upperextremity amputees are now designed with proper attention given to energy expenditures and other physiological factors based on scientific information obtained from laboratory and clinical studies. Close liaison between medical and engineering disciplines has contributed enormously to the revolutionary changes that prosthetics and orthotics have undergone during the past two decades. Experience in the management of amputees has given the authors the opportunity to study the possibilities of utilizing prosthetics principles in the management of orthopaedic conditions. The first of these came as a result of clinical work with below-knee amputees. Prior to the development of the patellar-tendonbearing (PTB) prosthesis in 1957, the belowknee amputee ambulated with an appliance which required a thigh corset to provide stability and to assist in the distribution of weightbearing forces. The PTB prosthesis proved that the below-knee stump could take the pressures necessary for weight-bearing during ordinary activities without assistance from a thigh corset. The snug, total-contact fit and the firm contouring of the tibial flare and patellar tendon make possible weight-bearing ambulation without undue pressure being exerted over small areas or appreciable telescoping of the stump in the prosthesis. The traditional belief in orthopaedic circles has been that fractures of the tibia require the joints above and below the fracture site to be immobilized, the knee joint to be held in flexion to increase rotational stability, and weightbearing to be avoided until fracture healing is complete. Some reports have appeared in the literature where ambulation on the fractured extremity is encouraged while the injured limb is stabilized in a groin-to-toe cast. This method, however, makes motion of the knee and ankle joints impossible (1). Convinced that the patellar-tendon-bearing prosthesis can adequately stabilize the stump without excessive piston action or rotation, the senior author applied the principles of this appliance to the treatment of tibial fractures. Three and a half years ago, he constructed a total-contact, below-knee cast firmly molded over the entire leg and contoured over the proximal tibia in a.manner identical to that of the patellar-tendon-bearing prosthesis (Fig. 1). The results were encouraging, since the fracture united without loss of the reduction originally obtained and without additional shortening, angulation, or rotation of the fragments. Since then we have treated 200 patients with various fractures of the tibia, malleoli, or os calcis (2). The impossibility of providing flexion in the proximal segment of the cast, as in the case of the PTB prosthesis, soon convinced the authors that the patellar tendon was not a major contributor to the distribution of weight-bearing pressures. In most cases, we do provide the patellar-tendon indentation and high condylar wings because they appear to be valuable in enhancing rotational stability, particularly in cases of high tibial fractures. With this short-leg, total-contact PTB-like cast, weight-bearing forces are transmitted