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Hans K Uhthoff

Publications and source records attributed to Hans K Uhthoff.

At least 19 recordsLinked to original sources
PubMed2007

Primary frozen shoulder: global capsular stiffness versus localized contracture.

Stiffness in primary (idiopathic) frozen shoulders has been attributed to a global fibroplasia of the capsule despite the fact surgical release of the capsule at the rotator interval and of the coracohumeral ligament restores motion in almost all patients. Occurrence of vimentin, a cytocontractile protein known to be present in Dupuytren's contracture and in club-feet, has been reported in resection specimens of anterior capsular structures. We hypothesized vimentin would occur only in the anterior structures but fibroplasia would occur throughout the capsule. Tissues removed from four patients were stained with antibodies against vimentin, allowing us to confirm its presence in only in anterior capsular structures, supporting our first hypothesis contracture is due to a selective involvement of the anterior capsule. Staining the sections against types I and III collagen permitted the detection of both collagens in the anterior and the posterior capsular structures and thus confirmed our second hypothesis that fibroplasia involves the entire joint capsule. Therefore it seems, in patients with primary frozen shoulder, fibroplasia and contracture are two distinct processes.

Aged↗
PubMed2007

Genetic influences on joint contractures secondary to immobilization.

The primary research question of this study queries whether, beyond environmental conditions, genetic factors affect the development of joint contractures. We hypothesized that intrinsic genetic factors influence the severity of joint contractures developing secondary to joint immobilization. Forty rats from four inbred rat strains had one leg immobilized in knee flexion for 4 weeks. The contracture was measured mechanically as the lack of range of motion to a standardized torque. Using the contralateral leg as a control, the average severity of the contracture could be calculated and compared between strains. All immobilized legs presented knee contractures after 4 weeks of immobilization. Two strains (Dark Agouti and Fisher 344) showed a larger mean knee contracture than those of the two other rat strains (Augustus Copenhagen Irish and Brown Norway). Environmental factors, such as immobility, are usually identified as a cause of a joint contracture. These results demonstrate that, in addition to mechanical factors in the environment of a joint, intrinsic genetic factors participate in the process leading to joint contracture. This demonstration has important consequences for directing future research and may lead to interventions to help patients at risk of developing joint contractures.

Animals↗
PubMed2006

Delay of supraspinatus repair by up to 12 weeks does not impair enthesis formation: a quantitative histologic study in rabbits.

The purpose of this study was to find out whether supraspinatus repair delayed by up to12 weeks affects the formation of a new enthesis when compared to an immediate repair. In 67 rabbits, the supraspinatus fibrocartilaginous enthesis of one shoulder was resected. The tendon was attached to the greater tuberosity either immediately, after a 6-week, or after a 12-week delay. Five histologic variables were used to assess enthesis formation: number of non-chondrocytes, number of chondrocytes, alignment of chondrocytes in rows, area of metachromasia on toluidine blue (TB)-stained sections indicating proteoglycan content, and area of diffracted polarized light indicating spatial alignment of collagen fibers. For every variable, progressive enthesis formation was observed. Again, for every variable and at every time point studied, no statistically significant difference was observed between tendons repaired immediately, after 6, or after 12 weeks (all p>0.05). Supraspinatus tendon repairs delayed by 6 and 12 weeks constituted an enthesis which proceeded identically to one immediately repaired. Formation of a fibrocartilaginous enthesis depended on the elapsed time after repair and not on the duration between detachment and repair. Despite stated limitations, these results support both a trial of conservative treatment after a rotator cuff tear and a positive outcome of rotator cuff repair even if delayed by up to 12 weeks.

Animals↗
PubMed2006

Internal plate fixation of fractures: short history and recent developments.

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, delayed bridging, and refractures after plate removal. These unwarranted effects were said to be caused by bone-plate contact interfering with cortical perfusion. Consequently, further plate modifications aimed to reduce this contact area to minimize necrosis and subsequent porosis. The advocates of limited-contact plates have not published measurements of the contact area or proof of the temporary nature of the porosis. Moreover, clinical studies of newer plate types have failed to show a superior outcome. Histomor-phometric measurements of the cortex showed no difference in the extent of necrosis under plates having different contact areas. Necrosis was predominant in the periosteal cortical half, whereas porosis occurred mostly in the endosteal cortical half. No positive correlation was found between either. The scientific evidence to date strongly suggests that bone loss is caused by stress shielding and not interference with cortical perfusion secondary to bone-plate contact. Consequently, an axially compressible plate (ACP) incorporating polylactide (PLA) inserts press-fit around screw holes was designed. The bioresorbable inserts should allow for (1) increased micromotion in the axial plane to promote healing during the union phase and (2) gradual degradation over time to decrease stress shielding during the remodeling phase. Results of ongoing experimental results are encouraging. Only plates allowing dynamic compression in the axial plane can lead to a revolution in fracture fixation.

Animals↗
PubMed2006

Comparative anatomy of rabbit and human achilles tendons with magnetic resonance and ultrasound imaging.

We sought to describe the comparative anatomy of the Achilles tendon in rabbits and humans by using macroscopic observation, magnetic resonance imaging, and ultrasonography. The calcaneus-Achilles tendon-gastrocnemius-soleus complexes from 18 New Zealand white rabbits underwent ultrasound (US) and magnetic resonance (MR) imaging and gross anatomic sectioning; these results were compared with those from a cadaveric gastrocnemius-soleus-Achilles tendon-calcaneus specimen from a 68-y-old human male. The medial and lateral gastrocnemius muscle tendons merged 5.2 +/- 0.6 mm proximal to the calcaneal insertion macroscopically, at 93% of their course, different from the gastrocnemius human tendons, which merged at 23% of their overall course. The rabbit flexor digitorum superficialis tendon, corresponding to the flexor digitorum longus tendon in human and comparable in size with the gastrocnemius tendons, was located medial and anterior to the medial gastrocnemius tendon proximally and rotated dorsally and laterally to run posterior to the Achilles tendon-calcaneus insertion. In humans, the flexor digitorum longus tendon tracks posteriorly to the medial malleolus. The soleus muscle and tendon are negligible in the rabbit; these particular comparative anatomic features in the rabbit were confirmed on the MR images. Therefore the rabbit Achilles tendon shows distinctive gross anatomical and MR imaging features that must be considered when using the rabbit as a research model, especially for mechanical testing, or when generalizing results from rabbits to humans.

Achilles Tendon↗
PubMed2005

Thawing of frozen calcaneus bone specimens has no effect on the bone mineral density using dual energy x-ray absorptiometry: a study in rabbits and humans.

The purpose of this paper is to study whether the deep freezing of bone and later thawing affects the bone mineral density (BMD) measurement. We used 56 calcanei from 28 adult female New Zealand white rabbits and 102 human calcanei from 51 donors post-mortem (27 men and 24 women, age 30-89). Dual energy x-ray absorptiometry evaluated BMD of the frozen specimen and of the thawed specimen. A main analysis compared BMD of each specimen in the frozen and thawed states. The mean BMD of 224 areas of frozen rabbits' calcanei was 0.31 +/- 0.08 g cm(-2) (95% confidence interval (CI) from 0.30 to 0.32 g cm(-2)) while the mean BMD of thawed rabbits' calcanei was 0.31 +/- 0.08 g cm(-2) (95% CI from 0.30 to 0.32 g cm(-2); paired t-test p > 0.01). The mean BMD of 306 areas of frozen human calcaneus was 0.73 +/- 0.22 g cm(-2) (95% CI from 0.70 to 0.76 g cm(-2)) while the mean BMD of thawed human calcaneus was 0.73 +/- 0.22 g cm(-2) (95% CI from 0.70 to 0.76 g cm(-2); p > 0.01). For both the rabbit and the human calcanei, a Bland-Altman analysis showed a mean difference between the BMD in the frozen and thawed states of 0.00 (limits of agreement, rabbit: -0.07 to 0.08 g cm(-2), human: -0.16 to 0.21 g cm(-2)). A high correlation was observed between calcaneus BMD in the frozen and thawed states (r = 0.94, 0.97, 0.92 and 0.99 respectively in all rabbit calcanei, all human calcanei, immobilized rabbit calcanei and osteopenic human calcanei, all p < 0.01). Bone mineral density is not affected by deep freezing and later thawing of the specimen. Therefore, the specimens need not be thawed to obtain valid and precise BMD measurement. These results are relevant to general musculoskeletal as well as osteoporosis research where the specimens undergo multiple tests in series.

Absorptiometry, Photon↗
PubMed2005

[Primary Ilizarov ankle fusion for nonreconstructable tibial plafond fractures].

OBJECTIVE: Ankle arthrodesis in a plantigrade position. In high-energy open injuries with segmental bone loss: proximal tibial metaphyseal corticotomy with distal Ilizarov bone transport for compensation of leg length discrepancy. INDICATIONS: Posttraumatic loss of the tibial plafond, usually resulting from open fracture type IIIC. CONTRAINDICATIONS: Ipsilateral foot injuries impairing ambulation after fusion. Severe injury to the posterior tibial nerve with absent plantar sensation. Soft-tissue injury not manageable surgically. Inadequate patient compliance. Advanced age. Severe osteoporosis. Acute infection. SURGICAL TECHNIQUE: Standard technique: anteromedial longitudinal incision. Removal of remaining articular cartilage. Passing of Ilizarov wires through the distal fibula, talar neck and body. Placement of 5-mm half-pins through stab incisions, perpendicular to the medial face of the tibial shaft. A lateral to medial 1.8-mm Ilizarov wire in the proximal tibial metaphysis is optional. Callus distraction/Ilizarov bone transport: exposure through an anteromedial incision or transverse traumatic wound. Removal of small residual segment of tibial plafond blocking transport. Retain small vascularized bone fragments not blocking transport. For Ilizarov external fixation, two rings in the proximal tibial region. Drill osteoclasis of the tibial metaphysis 1 cm distal to the tibial tuberosity and complete with Ilizarov osteotome. Secure the Ilizarov threaded rods or clickers. Weight bearing as tolerated. Begin distraction 14 days after corticotomy at a rate of 0.5-1 mm per day depending on patient's age. After docking: Ilizarov ankle arthrodesis. RESULTS: Between January 1993 and September 1996, four patients (two men, two women) with severe, nonreconstructable fractures of the tibial plafond were treated. Callus distraction and Ilizarov bone transport in three patients. Age range 19-68 years (average age 45.7 years). Mean follow-up 6.6 years (4 years 9 months to 7 years 4 months). Average duration of the entire treatment in external fixation 54.4 days/cm for the three bone distraction patients. Mean transport 6 cm (4.5-8.5 cm). One patient required repeat ankle arthrodesis.

Adult↗
PubMed2005

Contrasting alterations of apposed and unapposed articular cartilage during joint contracture formation.

OBJECTIVE: To quantify histologic articular cartilage alterations after immobilization, distinguishing between apposed and unapposed sites in an animal model of joint contracture. DESIGN: Experimental controlled trial. SETTING: Laboratory, in vivo study. ANIMALS: Adult male Sprague-Dawley rats (N=128). INTERVENTIONS: One hundred seventeen animals had 1 knee internally immobilized or sham-operated for 2, 4, 8, 16, or 32 weeks. One knee in 11 nonoperated animals served as controls. Main outcome measures On standardized sections, we identified femur and tibia cartilage sites that were apposed or that were unapposed. We quantified 4 characteristics: number of chondrocytes in the superficial and deep cartilage; matrix staining intensity to toluidine blue; surface irregularity of articular cartilage; and thickness of cartilage. RESULTS: Immobilized knees harbored fewer chondrocytes in the superficial cartilage at apposed sites and in the deep cartilage at unapposed sites. Matrix staining decreased only at unapposed sites. Cartilage surface became significantly more irregular at both sites but cartilage thickness remained unchanged. Noncartilaginous tissues appeared only at unapposed sites in the superficial and deep cartilage. CONCLUSIONS: Immobilization led to contrasting patterns of cartilage degeneration at apposed sites compared with unapposed sites. These results suggest distinct pathogenetic pathways for cartilage alterations, possibly through absence of mechanical forces (negative mechanotransduction) at unapposed sites and cyclic pressure at apposed sites. Considering the limited potential for cartilage self-repair, these results support the need for early diagnosis and aggressive mobilization of joints that are developing contractures.

Animals↗
PubMed2005

Formation of a new enthesis after attachment of the supraspinatus tendon: A quantitative histologic study in rabbits.

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 contralateral shoulders were processed for histologic sections. Number of non-chondrocytes, chondrocytes and alignment of chondrocytes in rows were assessed histologically. Extracellular matrix restoration was measured based on (1) area of toluidine blue metachromasia indicating proteoglycan content and (2) on area of diffracted polarized light indicating spatial collagen fiber alignment. RESULTS: In the attached tendon, the number of non-chondrocytic cells sharply increased at 2 weeks, progressively decreased thereafter but remained higher than controls at all time points. Chondrocytes appeared at 2 weeks and their number reached control levels by 6 weeks (136+/-14 vs 144+/-15 controls, p>.05). The percentage of chondrocytes aligned in rows increased from 19+/-4% at 2 weeks to reach near normal values at 24 weeks (71+/-3% vs 78+/-2% controls, p>.05). Area of metachromasia increased from 0.1+/-0.1 mm(2) at 2 weeks to 3.8+/-0.3 mm(2) at 24 weeks, still below contralateral enthesis levels (4.6+/-0.1 mm(2), p<.05). Area of diffracted polarized light enlarged from 12+/-2 x 10(3) microm(2) at 2 weeks to 151+/-19 x 10(3) microm(2) at 24 weeks, still significantly smaller than contralateral levels (177+/-13 x 10(3) microm(2), p<.05). Neither chondrocytes nor metachromasia were observed in the non-attached tendons. CONCLUSION: A new enthesis was formed after attachment of the supraspinatus tendon into bony trough. Histomorphometry allowed to document extensive non-chondrocytic proliferation that was followed by appearance of chondrocytes and their spatial organization, a process was complete by 24 weeks. Extracellular matrix formation as well as spatial alignment of collagen fibers were delayed and not complete by 24 weeks. This first longitudinal investigation on the formation of the supraspinatus enthesis using quantitative outcome measures cautions against too early and too aggressive a rehabilitation program.

Animals↗
PubMed2005

Dual cryogenic fixation for mechanical testing of soft musculoskeletal tissues.

Mechanical testing of soft musculoskeletal structures like tendons and ligaments are essential to medical advances. A long-standing limitation for testing these structures in isolation has been the ability to solidly fix both ends of the tendon. Cryogenic fixation technology was leveraged into the development of a dual cryogenic fixation (DCF) device. Results of the study show that the DCF allows tendons to be tested in isolation, at physiologic temperatures, with excellent reproducibility.

Animals↗
PubMed2005

Prothrombin gene expression in articular cartilage with a putative role in cartilage degeneration secondary to joint immobility.

OBJECTIVE: To test the hypothesis that thrombin is expressed by chondrocytes from human and animal articular cartilage and to monitor its levels of expression during cartilage degeneration induced by joint immobility in a rat model. METHODS: Rat knees were immobilized for periods of 2 or 4 weeks, after which the articular cartilage was harvested, total RNA extracted, and the differential display (ddPCR) protocol applied to identify differentially expressed genes. One differentially expressed fragment showed 100% homology with the prothrombin gene. Results were verified by RT-PCR, Northern and Western blot analysis, and immunohistochemistry in human, rat, and rabbit articular cartilage. RESULTS: In our rat model of cartilage degeneration induced by joint immobilization, increases in the levels of prothrombin mRNA, thrombin protein, and fibrin deposition were observed. Expression of the prothrombin gene by chondrocytes was confirmed by ddPCR (rat), RT-PCR (rat and human), and by Northern blot analysis (rabbit). In addition, thrombin-like immunoreactivity was increased in chondrocytes after a 4 week immobilization period compared with rat knees receiving sham surgery. Thrombin activity was reflected by the presence of fibrin immunoreactivity in operated rat knee joints. CONCLUSION: Articular chondrocytes express the prothrombin gene and its local expression in joints is translated into thrombin protein. Prothrombin expression is increased in response to joint immobility. Our results support generation of thrombin locally in joints and an upregulation of thrombin expression in cartilage degeneration secondary to immobility. These results may provide information on the source of increased thrombin activity in various animal models and in clinical forms of arthritis.

Animals↗
PubMed2003

Relevance of pathology and basic research to the surgeon treating rotator cuff disease.

For any physician expecting a successful outcome of a treatment regimen a thorough understanding of the underlying pathogenetic mechanism and the pathology of the disease process is an absolute prerequisite. In addition, the surgeon, obviously wishing to obtain a positive outcome of the procedure, must know the reaction of the body to his or her surgical actions. In particular, he or she must be familiar with the factors guaranteeing an uneventful healing process. For example, with rotator cuff disease it is important to realize that the site of degeneration leading eventually to tearing does not lie in the tendon itself but at its insertion into bone. Moreover, the cells and vessels needed for healing after surgical repair do not originate from the torn tendinous stumps. An important source of cells and vessels is the subacromial bursa overlying the site of tearing. Consequently, the bursa must be preserved at all cost. The subchondral bone trough into which the medial tendon stump is usually anchored during repair represents the other source of healing tissue. Whereas surgeons understandably concentrate their attention on the site of tearing, the fate of the muscle in the torn bone-tendon-muscle unit must not be neglected. In experimental studies we were able to measure muscle atrophy and fat accumulation and could quantify their evolution over time. Finding no reversal of these two parameters after successful repair was disturbing. Shoulder surgeons will benefit from this comprehensive review of updated concepts.

Animals↗
PubMed2003

Mechanical effects of immobilization on the Achilles' tendon.

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 cross-sectional area did not change. Achilles' tendon-calcaneus units failed at insertion at 4 weeks and in controls. Calcaneus fracture was the most prevalent mode of failure at 8 weeks. The mean load to failure of both immobilized groups (4wk: 187.5+/-45.7N; 8wk: 162.6+/-39.3N) was significantly smaller than that of the control group (549.2+/-93.7N, both P<.005). The mean tendon stiffness of both immobilized groups (4wk: 64.6+/-24.8N/mm; 8wk: 53.9+/-19.9N/mm) was significantly lower than that of the control group (125.1+/-26.5N/mm, both P<.005). CONCLUSIONS: Immobility for up to 8 weeks caused decreased stiffness but no atrophy or rupture of the Achilles' tendon, suggesting that immobility does not constitute a risk factor for Achilles' tendon midsubstance rupture. Clinically, graded reloading is required after immobilization to restore the tendon insertion and to reverse calcaneal disuse osteoporosis.

Achilles Tendon↗
PubMed2003

Localized and adaptive synoviocyte proliferation characteristics in rat knee joint contractures secondary to immobility.

OBJECTIVE: To investigate the proliferative activity of synoviocytes in joint contracture. DESIGN: Experimental controlled trial. SETTING: Laboratory in vivo study. ANIMALS: Adult male Sprague-Dawley rats (avg weight, 340g). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We immobilized the knee joints of 24 rats, in 135 degrees of flexion, for up to 32 weeks. Controls were 24 sham-operated and 5 unoperated rats. On sagittal sections, synoviocytes that stained with a proliferating cell nuclear antigen antibody were counted over the anterior and posterior synovial intima. The length of the synovial intima was also measured. RESULTS: The absolute number of proliferating synoviocytes decreased markedly in the posterior capsule of knee joints immobilized for more than 2 weeks (2.4+/-1.0 vs 22.7+/-7.1 at week 16, P<.05), and so did the synovial intima length (1.4+/-0.1mm vs 8.6+/-0.5mm at week 16, P<.05). No change occurred anteriorly. CONCLUSION: A decreased number of proliferating synoviocytes and increased intima adhesion in the posterior capsule characterized joint contractures. The data further suggest that the synovial intima adapted to the new position of the joint. Phenomena of mechanotransduction could explain the fact that adaptations were restricted to the posterior synovial intima.

Animals↗
PubMed2003

Early reattachment does not reverse atrophy and fat accumulation of the supraspinatus--an experimental study in rabbits.

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 accumulation of the SSP. MATERIAL AND METHODS: Reattachment group: in seven rabbits unilateral supraspinatus detachment, reattachment after 6 weeks and killing 6 weeks later. Detachment group: in seven rabbits unilateral supraspinatus detachment and killing 12 weeks later. The contralateral shoulders served as controls (n=14). Determination of the supraspinatus constituents: muscle, extra- and intramuscular fat in volume and cross-sectional area. RESULTS: Muscle tissue in the reattachment group (8.6 ml+/-1s.d.=0.6) and in the detachment group (8.9 ml+/-0.9) were less than in control supraspinati (10.2 ml+/-0.9, both p<0.05). Extra- and intramuscular fat in the reattachment group (8.7%+/-3.2) was greater than in both, the detachment group (4.6%+/-3.5), and control supraspinati (2.8%+/-1.7, both p<0.05). CONCLUSION: In the rabbit, reattachment of the SSP at 6 weeks did neither reverse muscle atrophy nor fat accumulation during the ensuing 6 weeks. However, earlier reattachment (6 weeks) when compared with later reattachment (12 weeks) prevented an increase in fat accumulation. On the other hand, the delay before reattaching the tendon did not lead to an increase in muscle atrophy.

Adipose Tissue↗
PubMed2003

Measurement of articular cartilage surface irregularity in rat knee contracture.

OBJECTIVE: To design novel quantitative methods to evaluate the irregularity of articular cartilage surface; and to apply these methods for assessment of surface irregularity in a rat knee contracture model. METHODS: A total of 117 rat knees were either immobilized or sham-operated and harvested after 2, 4, 8, 16, or 32 weeks, and 11 knees were not operated. Standardized histologic sections were digitized and the contours of femoral and tibial cartilage surfaces were delineated. The rates of change in cartilage contour were calculated. Rate of change above a defined threshold constituted surface irregularity. RESULTS: In non-operated knees, cartilage surface irregularity in femur and tibia amounted to 3.1 +/- 0.5%. Immobilized knees showed significantly more irregularities than the sham-operated knees at all time points (2 weeks: 5.3 +/- 0.6% vs 3.1 +/- 0.4%; 4 weeks: 10.5 +/- 0.9% vs 4.4 +/- 0.9%; 8 weeks: 12.0 +/- 1.8% vs 4.9 +/- 0.2%; 16 weeks: 13.7 +/- 2.0% vs 4.9 +/- 0.4%; and 32 weeks: 13.8 +/- 1.4% vs 3.4 +/- 0.6%; all p < 0.05). No difference was observed between sham-operated and non-operated knees. Increasing duration of immobilization in weeks (t) significantly correlated with more surface irregularity, described by the logarithmic formula: % irregularity = 6.6 + 2.1 ln (t), (F = 59.3, p < 0.001). This formula showed that irregularity progressed rapidly after immobilization and plateaued after 8 weeks. CONCLUSION: We designed methods to quantify cartilage surface irregularity and applied them to a contracture model. Cartilage surface irregularities appeared after 2 weeks of immobilization and progressed rapidly to plateau after 8 weeks. Combined with microscopic magnetic resonance imaging, this measurement of cartilage surface irregularity may constitute a sensitive tool to detect cartilage degeneration clinically.

Animals↗
PubMed2002

Delayed tendon reattachment does not reverse atrophy and fat accumulation of the supraspinatus--an experimental study in rabbits.

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 rabbits and the tendon inserted into a bony trough. The opposite shoulder served as control. All rabbits were killed at 24 weeks. Accumulation of fat on the muscle surface as well as between the muscle fascicles and occasionally in the sarcoplasm was increased in both experimental groups when compared to controls (non-reattached 12.8%, reattached 23.5% vs controls 5.4%; all p < 0.005). The muscle atrophy was significant (non-reattached 9.2 ml, reattached 9.1 ml vs controls 10.7 ml; both p < 0.005). Neither atrophy nor fat accumulation were reversed by surgical reattachment of the supraspinatus tendon. On the contrary, the fat accumulation was higher in the reattached group (p < 0.005). The trauma of reattachment, the delay between detachment and reattachment or an insufficient duration of recovery may have contributed to both, the lack of reversibility of supraspinatus atrophy and fat accumulation.

Adipose Tissue↗