[Mechanics as a basic physical discipline in orthopedics and traumatology]. / Die Mechanik als physikalische Grundlagendisziplin der Orthopädie und Traumatologie.

Among the various relationships between fields of the clinical medicine and fields of physics, the relationship between orthopaedics and traumatology and mechanics is of a particularly close and manifold nature. We try to present in this contribution a description of the physical principles of mechanics and to give a survey of its various fields of application in orthopaedic and traumatologic basic research.

[Use of a computer-controlled kinematic-electromyographic motion analysis system to investigate gait patterns of healthy subjects on the level walkway and the treadmill (author's transl)]. / Anwendung eines computergesteuerten kinematisch- elektromyographischen Bewegungsanalysesystems zur Untersuchung des Gehverhaltens gesunder Probanden auf der Laufstrecke und auf der Rollgehbahn.

In an attempt to clarify the question if the level walkway and the treadmill present comparable conditions for analytic examinations of the human gait we investigated in either situation with a computer-controlled motion analysis system some kinematic and electromyographic aspects of the gait pattern of 20 healthy subjects. The results show that on the treadmill certain kinematic events in the time pattern of the gait cycle are shifted towards the beginning of the full stride. Moreover, in the treadmill walk the amplitude of the angular motion of the thigh is diminished in the forward and enhanced in the backward direction, while the angular amplitude of the shank is diminished in either direction. As to the electromyographic results, we found in the treadmill walk a prolonged activity of the gluteus maximus, and adductor magnus, the semitendinosus, and the gastrocnemius muscle. These results show that there may exist significant kinematic and electromyographic differences between the treadmill and the normal level walk. This fact has to be considered whenever a treadmill is considered for gait analytical investigations.

A kinesiologic electromyography system for the computer-controlled analog and digital recording and processing of muscle action potentials of walking subjects.

A computer-controlled electromyography (EMG) System has been developed for the kinesiologic examination of orthopedic patients. A major objective in the design of the system was its convenient operation in the daily clinical routine. The EMG signals are transduced by specially constructed electrode-preamplifier units and filtered and further amplified in a cable distribution box fixed to the subject's belt or back. The amplified signals are transmitted to the stationary signal conditioning, display, and recording units by an easily tractable trailing cable guided in a ceiling rail. The test gait sequence is performed on a level walkway 14 m in length. A functional partition into periodically recurring gait is achieved either by foot-floor contact sensors or by optional goniometric measurements in the lower extremity. Patient safety is provided by an opto-coupling interface. The EMG signals are displayed on specially constructed large screen oscilloscopes for convenient real-time monitoring by the examiner. An analog recording is carried out by a multi-channel strip chart recorder. The digital recording and processing of the EMG signals and the control of the analog recording unit are implemented by an on-line system. This paper describes the main constructional features of the system and its components, discusses the basic problems involved in the digital recording and processing of EMG signals, and gives an outline of the digital processing mode employed so far in our electromyographical examination of orthopedic patients with various gait disorders.

A test-subject-tracking measuring carriage with optoelectronic position-feedback control for the kinematic analysis of the gait of orthopedic patients.

A measuring carriage system has been developed in our biomedical motion-analysis laboratory for the continuous optoelectronic measurement of angular coordinates or point coordinates in the sagittal plane of a walking patient. The carriage is automatically driven on a guide rail in parallel with the advancing test subject along a level walkway 14 m in length. The carriage propulsion is effected by a servomotor which is controlled by an object-tracking optoelectronic position-feedback control system. The paper describes the constructional principles of the system and gives a basic analysis of its feedback-control behavior.

[A contribution to the differential indication of endoprosthetic knee-joint substitution (author's transl)]. / Beitrag zur Differentialindikation des endoprothetischen Kniegelenkersatzes.

The article describes a few guiding points for indicating the need for a knee-joint endoprosthesis, basing on experience with 253 cases, followed up for 2--48 months. Following the application of prostheses according to Walldius-Debeyre and Guepar, several complications were seen which we tried to reduce by introducing four prostheses of different sizes, since the choice of the implantates could be adapted to the prevailing anatomical conditions. A hinged-joint prosthesis of the St. George type is indicated in cases of most severe axial deviation, severe flexion contraction, extensive loss of bone substance, and instability of the ligaments. Sheeban's prosthesis is indicated in severe damage involving both compartments, limited frontal axial deviation, and flexion contraction of not more than 25 degrees with intact lateral ligaments. In younger patients with rheumatoid arthritis we implant the Geomedic prosthesis. If only one knee-joint compartment is involved, and after the possibility of readjustment osteotomy has been excluded, we consider a sliding prosthesis to be the prosthesis of choice.

[Indications for reoperation in radicular syndromes following surgical removal of lumbar disk hernias (author's transl)]. / Indikationen zur Reoperation bei radikulären Syndromen nach operativer lumbaler Diskushernienentfernung.

In case ischias-type pain persists or recurs following surgical removal of lumbar disk prolapses, it will be necessary to carefully weigh against one another as possible causes: disk prolapse recidivation, epidural or intradural cicatrization, and pseudoradicular pain in myotendinoses. Postoperative diskitis or spondylitis must also be considered as a possible cause.

Selective changes in size and distribution of fibre types in vastus muscle from cases of different knee joint affections.

Different knee joint affections are apt to initiate different specific atrophy forms in quadriceps muscle. By a biopsy-technique using the histochemical demonstration of ATPase and succinate dehydrogenase fast twitch fibre atrophy can be correlated with increasing age and a moderate impairment but still ambulatory condition. Fast twitch and slow twitch fibres together show atrophy in those cases which are severely impaired and nearly immobilized. An isolated atrophy of slow twitch fibres was found in three patients suffering from frequent sudden short-lasting pain in the knee joint, although this condition may not be alone the cause for slow twitch fibre atrophy. The mechanisms leading to a selective atrophy of muscle fibre types are not fully understood. Nevertheless, a more clear understanding of the nature of skeletal muscle atrophy brought about by joint affections should be of benefit for a better concept of physiotherapeutical approaches: In fast twitch fibre atrophy maximal short lasting contractions followed by rather long periods of recovery should be performed (30). Slow twitch fibre atrophy should be influenced beneficially by chronic submaximal activity (46), whereas both fibre type atrophy should be treated by a combination of isometric techniques and chronic submaximal activities.

[Incomplete spinal cord syndrome in Paget's disease of the spine (author's transl)]. / Beitrag zum partiellen Querschnittssyndrom beim Morbus Paget der Wirbelsäule

Report on a case, wrongly interpreted for a long time. The diagnostic difficulties in a slowly developing spinal cord syndrome in Paget's disease are discussed. The cord may be damaged in this disease in various ways. Here it was increasing mechanical compression by bone bulging into the spinal canal. Decompression laminectomy gives usually good results provided it is done early enough.