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Hans Klaus Uhthoff†: Influence Statistics

OBJECTIVES: To test the hypotheses that contractures progress at different rates in relation to the time after immobilization, that immobilization in flexion leads to loss of extension range of motion, and that joints of sham-operated animals are better controls than the contralateral joint of experimental animals.

STUDY DESIGN: Experimental, controlled study in which 40 adult rats had one knee joint immobilized at 135 degrees of flexion for up to 32 weeks and 20 animals underwent a sham ...

Immobility in bed and decreased mobility cause adaptations to most human body systems. The effect of immobility on fat accumulation in hemopoietic bone marrow has never been measured prospectively. The reversibility of marrow fat accumulation and the effects on hemopoiesis are not known. In the present study, 24 healthy women (age: 25-40 yr) underwent -6 degrees head-down bed rest for 60 days. We used MRI to noninvasively measure the lumbar vertebral fat fraction at various time points. ...

INTRODUCTION: Reattachment of the supraspinatus (SSP) tendon after spontaneous rupture leads to improved shoulder function. Whether this improvement of function is due to a reversal of muscle atrophy and fat accumulation known to occur after SSP rupture is still debated. Our previous study of late reattachment of SSP (12 weeks) failed to confirm a reversal of muscle atrophy and of fat accumulation.

PURPOSE: To find out whether earlier reattachment (6 weeks) reverses atrophy and fat ...

Muscle atrophy and fat accumulation occur after rotator cuff tearing. Whether these changes are reversible after a successful repair is still unknown. Imaging allows only a semi-quantitative assessment of muscle atrophy and fat deposition. As only experimental studies permit a quantification of both, a unilateral detachment and wrapping in a polyvinylidine fluoride membrane of the supraspinatus was done in 22 rabbits. After 12 weeks, the polyvinylidine fluoride membrane was removed in 10 ...

Joint contractures alter the mechanical properties of articular and muscular structures. Reversibility of a contracture depends on the restoration of the elasticity of both structures. We determined the differential contribution of articular and muscular structures to knee flexion contractures during spontaneous recovery. Rats (250, divided into 24 groups) had one knee joint surgically fixed in flexion for six different durations, from 1 to 32 wk, creating joint contractures of various ...

OBJECTIVES: To measure articular structures' contribution to the limitation of range of motion after joint immobility.

STUDY DESIGN: Experimental, controlled study involving 40 adult rats that had one knee joint immobilized in flexion for durations of 2, 4, 8, 16, and 32 weeks; 20 rats underwent a sham procedure. The angular displacement was measured both in flexion and extension at three different torques. Myotomy of transarticular muscles allowed isolation of the arthrogenic component ...

PURPOSE: To quantify in a longitudinal study non-chondrocytic cells and chondrocytes, tissular architecture as well as extracellular matrix restoration during the formation of an enthesis following supraspinatus tendon attachment to the humerus.

METHODS: In 89 rabbits, one supraspinatus fibrocartilaginous enthesis was resected and the tendon either attached to the greater tuberosity (n=75) or not attached (n=14). The animals were sacrificed after 2, 6, 8, 12 or 24 weeks. The operated and ...

PURPOSE: To quantify the accumulation, progression, and distribution of fat separately in and around the supraspinatus muscle from the onset of tendon detachment and to validate computed tomography (CT) for quantification of fat content by using volumetry and histomorphometry as reference standards.

MATERIALS AND METHODS: Institutional animal care committee approval was obtained. The supraspinatus tendon of 30 adult female rabbits (3.0 kg) was detached. Rabbits were sacrificed in groups ...

The purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty-three fresh cadaveric shoulders (average age: 62 years; range: 39-83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative ...

Metal plates for internal fixation of fractures have been used for more than 100 years. Although initial shortcomings such as corrosion and insufficient strength have been overcome, more recent designs have not solved all problems. Further research is needed to develop a plate that accelerates fracture healing while not interfering with bone physiology. The introduction of rigid plates had by far the greatest impact on plate fixation of fractures. However, it led to cortical porosis, ...

OBJECTIVE: To measure the biomechanical effects of immobilization on the Achilles' tendon.

DESIGN: Experimental, controlled study.

SETTING: Physiatry research laboratory.

ANIMALS: Twenty adult rabbits.

INTERVENTION: One hindlimb immobilized in a cast for 4 weeks (n=10) or 8 weeks (n=10). The contralateral legs (n=20) served as controls.

MAIN OUTCOME MEASURES: Cross-sectional Achilles' tendon area, mode of failure, mean failure load, and tendon stiffness.

RESULTS: The Achilles' tendon ...

Fat accumulates in the bone marrow of lumbar vertebrae with bed rest. Exercise with or without whole body vibration may counter this effect. Our objectives were to measure 1) the vertebral fat fraction (VFF) of men subjected to bed rest who performed resistive exercises with (RVE, n = 7) or without whole body vibration(RE, n = 8) or no exercise (CTR, n = 9) using three MRI techniques; and 2) changes in peripheral blood counts. Twenty-four healthy men (age: 20-45 yr) underwent -6° ...