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Published on: March 31, 2023
Tendon response to pharmaco-mechanical stimulation of the chronically retracted rotator cuff in sheep
Karl Wieser1, Mazda Farshad, Dominik C Meyer
1Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland, karl.wieser@balgrist.ch.
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.
Insights
Mechanical stimulation improved tendon degeneration in sheep rotator cuff tendons. Adding anabolic steroids (nandrolone) or insulin-like growth factor (IGF) did not enhance these positive effects for tendon repair.
Area of Science:
- Orthopedics
- Regenerative Medicine
- Biotechnology
Background:
- Chronic tendon tears cause molecular and structural changes, impairing function and hindering repair.
- Understanding these changes is crucial for developing effective tendon repair strategies.
Purpose of the Study:
- To investigate the histological response of chronically retracted sheep rotator cuff tendons to mechanical and pharmacological stimulation.
- To evaluate the potential of mechanical and pharmacological interventions for tendon repair.
Main Methods:
- Retracted infraspinatus tendons in sheep were subjected to continuous traction for 6 weeks, with or without nandrolone or IGF.
- A novel degeneration score for tendinous tissues (DSTT) was used for histological analysis at multiple time points.
Main Results:
- Mechanical stimulation significantly reduced tendon degeneration, as indicated by DSTT scores.
- The addition of nandrolone or IGF did not yield significant improvements compared to mechanical stimulation alone.
- DSTT scores improved from 15.5 to 9.8 with mechanical stimulation, with or without pharmacological agents.
Conclusions:
- Mechanical stimulation is effective in reducing tendon degeneration in chronic rotator cuff tears.
- Pharmacological stimulation with nandrolone or IGF does not provide additional benefits for tendon degeneration.
- Current evidence does not support the use of nandrolone or IGF for enhancing tendon repair in this model.
