Gait analysis with an angle diagram technique: application in healthy persons and in studies of Marmor knee arthroplasties.

Normal step dimension data were obtained from six healthy subjects by recording step length and step frequency at different walking speeds. In addition, an externally applied goniometer system was used to measure the sagittal knee and hip joint movements in eleven persons with healthy joints. The movements were recorded on an oscilloscope in the form of a so-called angle diagram during walking. In seven patients undergoing Marmor knee arthroplasty the same gait analysis as in the healthy subjects was performed before and after operation. The results were compared by a clinical scoring system for pain and walking ability and by measurement of passive knee mobility and passive extension deficit. The angle diagram permitted recording of functional sagittal mobility and functional extension deficit during walking. The functional knee mobility during walking was found to be pain-dependent; thus increasing pain is accompanied by a gradual decrease in functional mobility despite good passive knee joint motion. In several patients the functional extension deficit during walking was increased compared with the extension deficit on passive movement. The clinical improvements after knee arthroplasty corresponded very well to the increased functional knee mobility during walking measured on the angle diagram.