The challenge of prosthetic cruciate ligament replacement.

Prosthetic replacement of the anterior cruciate ligament has become very important because of the failure of late reconstruction of anterior cruciate ligament injuries. Models of prostheses have failed, because they have never met the functional, physiologic and biomechanical characteristics of the normal anterior cruciate ligament. Studying the biomechanical characteristics of the normal anterior cruciate ligament, we have found that normal cruciate ligaments have measurable strength, yield points and ultimate tensile strength and show remarkable elasticity. We have also found that cruciate ligaments change their length during normal flexion/extension, and go through a limited elastic non-plastic deformation. We have devised a composite prosthesis, made of a compressible inner core around which a non-elastic fiber is woven in a helical fashion, with a predetermined angle. The construction has the essential characteristics of the normal ligament.