[The influence of the C-leg knee-shin system from the Otto Bock Company in the care of above-knee amputees. A clinical-biomechanical study to define indications].

The C-Leg microprocessor-controlled knee-shin system for the above-knee amputees is introduced as a dramatic improvement over all other prosthetic knees. This is due to its combination of on-board microprocessor and the hydraulic controls acting both on the swing and stance phase. A more secure, natural and efficient gait is expected. Following the recommendations of Otto Bock the indications for the prescription of the C-leg are: Amputees with mobility level "able to walk outdoors without limitations" (AK3) and "able to walk outdoors without limitations plus engage in high performance activities" (AK4) if they face at least one extra obstacle as listed in the Otto Bock catalogue of indications. In this article it is aimed to critically review the indications for the C-leg. In particular the question is posed, whether a different or sophisticated indication of mobility levels might be suggested. Therefore this study does not concentrate on the 3C-100 C-Leg((R)) component but on the system patient + C-leg. So the testing is done by comparing the C-Leg against the regular knee, which is assumed to be an adequate choice for this patient and to which he is accustomed. So far 25 patients with activity levels AK 2 (5), AK 3 (13) and AK 4 (7) have participated in the study. 23 patients, i.e. all patients except one AK 2 and one AK 3 exhibit functional improvement at least according to one criterion. On the other side, only three patients (2 AK 4), fulfill all criteria of functional improvement, which have been defined for this test. It is concluded, that multi-handicapped patients of all activity levels generally experience substantial improvement due to this system. AK 2 patients may show significant functional improvement. As a prerequisite, however, they must not exhibit deficiencies regarding stump movement, muscular status or cognitive abilities. Active patients (AK 3 and AK 4) benefit in the majority of cases. However, some highly active patients of AK 4 complain about interferences between their intended movement and the microprocessor control of knee movements.