Kontinuierliche Dehnung einer Muskel-Sehneneinheit unter pharmakologischer Muskelstimulation mit Anabolika und IGF zur Behandlung struktureller Muskelveränderungen nach Sehnenriss

In dieser Studie wurde ein etabliertes Schafmodell zur Untersuchung chronischer Rotatorenmanschettenrupturen des Menschen genutzt, um die Wirkung eines Androgens und IGF-I auf den chronisch retrahierten Muskulus infraspinatus zu testen. Durch deren Applikation während einer Phase kontinuierlicher Muskeldehnung sollten Retraktion, Atrophie sowie degenerative Prozesse gestoppt und reversibel gemacht werden. Hierzu wurde zunächst die Sehne des M. infraspinatus einer Vordergliedmaße der Versuchstiere vom Humerus gelöst. Nach 16 Wochen Muskelretraktion wurde die Implantation eines speziellen Dehnungsapparates vorgenommen. In den folgenden 6 Wochen wurde der M. infraspinatus mittels des Apparates kontinuierlich wieder auf seine ursprüngliche Länge gedehnt. Während dieser Zeit wurden zwei Schafgruppen mit dem Androgen oder aber IGF-I behandelt. Eine dritte Gruppe blieb unbehandelt. Nach der Dehnungsphase erfolgte die Refixation der Sehne. 12 Wochen später wurden die Tiere euthanasiert. Anhand verschiedener Untersuchungsmethoden konnten Veränderungen des Muskels und seiner Sehne evaluiert werden. Die Resultate zeigten, dass Muskelretraktion und Muskelatrophie aufgehalten und zum Teil reversibel gemacht werden konnten. Auch eine Erholung der Muskelarchitektur war erkennbar. Weder das Androgen noch IGF-I zeigten nach lokaler Applikation Auswrikungen auf diese Parameter, sodass die Regeneration der Muskelarchitektur vor allem auf die kontinuierliche Muskeldehnung zurückzuführen war. Summary In this experimental study a well established sheep shoulder model for rotator cuff disease was used to evaluate the effect of an anabolic steroid and IGF-I, applied directly to a chronically retracted infraspinatus muscle. It was expected that muscle function, atrophy and degeneration would recover under continuous traction and would be improved furthermore by the anabolic steroid and IGF-I, respectively. The infraspinatus tendon of the right forelimb was released and allowed to retract over a period of 16 weeks. Thereafter a specially developed traction device was implanted and fixed upon the scapular spine. Afterwards the retracted muscle was streched stepwise over a six week period. In group one no further pharmalogical stimulation was applied. An anabolic steroid and IGF-I were applied during that period in group two and three, respectively. Subsequently the reattachment of the infraspinatus tendon was performed. After another 12 weeks the sheep were subjected to euthanasia. Physiological, radiological and histological examinations were performed to evaluate muscle and tendon changes thoroughly. The results showed that muscle retraction and muscle atrophy were stopped and partially reversed. The pennation angle of the muscle fibres and thereby a normal muscle architecture was almost restored in full. But neither Nandrolon Decanoas nor IGF-I seemed to have a positive effect on the outcome rendering the tension device as the main effect for restoring normal musclearchitecture

Tendon response to pharmaco-mechanical stimulation of the chronically retracted rotator cuff in sheep

PURPOSE: Chronic tearing of tendons is associated with molecular and structural alterations causing biomechanical changes, which compromise musculotendinous function and become limiting factors for tendon repair. This study investigated the histological response of chronically retracted sheep rotator cuff tendons to mechanical and pharmacological stimulation in view of tendon repair. METHODS: Sixteen weeks after experimental release of the infraspinatus tendon in 20 sheep, the retracted musculotendinous unit was subjected to continuous traction either with [anabolic steroids (nandrolone) group/insulin-like growth factor (IGF) group] or without (control group) additional pharmacological treatment during 6 weeks. A new degeneration score for tendinous tissues (DSTT), based on established knowledge on histological changes associated with tendon degeneration, was used for histological analysis at the time of tendon release, at the beginning of continuous re-lengthening and at repair in all animals. RESULTS: The DSTT score (inter-observer correlation: r = 0.83), quantifiably representing tendon degeneration, improved from 15.5 (SD 1.3) points before to 9.8 (SD 3.8) points after re-lengthening. It improved in a qualitatively and quantitatively similar fashion if pharmacological stimulation was added. The nandrolone group improved from 13.7 (SD 1.6) to 9.8 (SD 1.9) and the IGF group from 13.3 (SD 3.6) to 8.8 (SD 1.8) points. CONCLUSION: Mechanical stimulation significantly reduced tissue degeneration. However, the addition of a pharmacological stimulation with anabolic steroids or IGF had neither a measurable positive nor negative effect on the degenerative process. Therefore, this investigation does neither support the additional pharmacological use of the anabolic steroid nandrolone or of IGF decanoate for restoration of tendon degeneration, nor otherwise provide evidence for additional tendon damage, if those substances are used to alter the muscular metabolism

Tendon response to pharmaco-mechanical stimulation of the chronically retracted rotator cuff in sheep

Purpose: Chronic tearing of tendons is associated with molecular and structural alterations causing biomechanical changes, which compromise musculotendinous function and become limiting factors for tendon repair. This study investigated the histological response of chronically retracted sheep rotator cuff tendons to mechanical and pharmacological stimulation in view of tendon repair. Methods: Sixteen weeks after experimental release of the infraspinatus tendon in 20 sheep, the retracted musculotendinous unit was subjected to continuous traction either with [anabolic steroids (nandrolone) group/insulin-like growth factor (IGF) group] or without (control group) additional pharmacological treatment during 6weeks. A new degeneration score for tendinous tissues (DSTT), based on established knowledge on histological changes associated with tendon degeneration, was used for histological analysis at the time of tendon release, at the beginning of continuous re-lengthening and at repair in all animals. Results: The DSTT score (inter-observer correlation: r=0.83), quantifiably representing tendon degeneration, improved from 15.5 (SD 1.3) points before to 9.8 (SD 3.8) points after re-lengthening. It improved in a qualitatively and quantitatively similar fashion if pharmacological stimulation was added. The nandrolone group improved from 13.7 (SD 1.6) to 9.8 (SD 1.9) and the IGF group from 13.3 (SD 3.6) to 8.8 (SD 1.8) points. Conclusion: Mechanical stimulation significantly reduced tissue degeneration. However, the addition of a pharmacological stimulation with anabolic steroids or IGF had neither a measurable positive nor negative effect on the degenerative process. Therefore, this investigation does neither support the additional pharmacological use of the anabolic steroid nandrolone or of IGF decanoate for restoration of tendon degeneration, nor otherwise provide evidence for additional tendon damage, if those substances are used to alter the muscular metabolism

Effect of autologous adipose tissue-derived mesenchymal stem cells on neovascularization of artificial equine tendon lesions

AIMS: To investigate whether autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) treatment of tendon lesions increases neovascularization during tendon healing. MATERIALS & METHODS: A standardized surgical model was used to create lesions in both front limb superficial digital flexor tendons (SDFTs) of nine horses. Either AT-MSCs or control substance was injected intralesionally 2 weeks post-surgery. Color Doppler ultrasonography of SDFTs was performed at regular intervals. Horses were euthanized 22 weeks post-treatment and SDFTs were harvested for histology. RESULTS: The color Doppler ultrasonography signal was significantly more extensive at 2 weeks post-treatment and the number of vessels counted on histologic slides was significantly higher at 22 weeks post-treatment in AT-MSC-treated SDFTs. CONCLUSION: Our findings indicate that AT-MSC treatment has a beneficial effect on neovascularization of healing tendons

Effect of autologous adipose tissue-derived mesenchymal stem cells on neovascularization of artificial equine tendon lesions

AIMS: To investigate whether autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) treatment of tendon lesions increases neovascularization during tendon healing. MATERIALS & METHODS: A standardized surgical model was used to create lesions in both front limb superficial digital flexor tendons (SDFTs) of nine horses. Either AT-MSCs or control substance was injected intralesionally 2 weeks post-surgery. Color Doppler ultrasonography of SDFTs was performed at regular intervals. Horses were euthanized 22 weeks post-treatment and SDFTs were harvested for histology. RESULTS: The color Doppler ultrasonography signal was significantly more extensive at 2 weeks post-treatment and the number of vessels counted on histologic slides was significantly higher at 22 weeks post-treatment in AT-MSC-treated SDFTs. CONCLUSION: Our findings indicate that AT-MSC treatment has a beneficial effect on neovascularization of healing tendons