Knee orthoses for valgus protection. Experiments on 11 designs with related analyses of orthosis length and rigidity.
Recent years have seen the introduction of a great many knee orthosis designs prescribed for protection against ligamentous injury or reinjury of the knee. The configurations and materials incorporated in these designs vary greatly, but all claim to be very effective. A leg model and 11 different commercially available knee orthoses were tested with static loading to obtain objective data on the relative effectiveness of the 11 designs to protect the knee from externally applied valgus moments. From these data, the effectiveness of each orthosis was calculated in terms of the rigidity contributed to the leg/orthosis combination. At a static valgus loading of 78 Nm, there was an eightfold variation in the rigidities contributed by the various knee orthoses, ranging from a low of 0.9 Nm per degree valgus to a maximum of 7.2 Nm per degree. The authors related analyses of two aspects of knee orthosis design (orthosis length and orthosis rigidity) to effectiveness in protecting against knee valgus overload injuries. Correlations were found between design inadequacies noted theoretically and efficacy problems evident from the laboratory tests. Orthosis length and orthosis rigidity must both be adequate, or the orthosis will not be biomechanically effective.
Carlson
J M
JM
Habilitation Technology Laboratories, Gillette Children's Hospital, St. Paul, Minnesota 55101.
French
J
J
D006801:Humans; D007593:Joint Instability / Q000517:prevention & control; D007718:Knee Injuries / Q000517:prevention & control*; D009989:Orthotic Devices; D011474:Prosthesis Design