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Updated: Aug 8, 2026
Murine Flexor Tendon Injury and Repair Surgery
Published on: September 19, 2016
Differential cellular response within the rabbit tendon unit following tendon injury
S Kakar1, U Khan, D A McGrouther
1Department of Plastic and Reconstructive Surgery, University College, London, UK.
Insights
This study reveals that tendon injuries initially cause fibroblast and macrophage increases in the epitenon and synovial sheath. The endotenon shows delayed cellular response, including apoptosis, before later hypercellular activity.
Area of Science:
- Tendon healing and cellular responses
- Connective tissue biology
- Rabbit models in regenerative medicine
Background:
- Understanding cellular dynamics in tendon repair is crucial for developing effective treatments.
- Partial tendon lacerations trigger complex cellular events influencing healing outcomes.
Purpose of the Study:
- To investigate the cellular changes in the epitenon, endotenon, and synovial sheath following a partial transverse laceration of the flexor digitorum profundus tendon in a rabbit model.
- To quantify the roles of fibroblasts, macrophages, and mast cells in the early and late stages of tendon healing.
Main Methods:
- Partial transverse laceration of the flexor digitorum profundus tendon in rabbits.
- Electron microscopy for cellular counting (fibroblasts, macrophages, mast cells).
- Assessment of apoptosis using P53 staining in the endotenon.
Main Results:
- The epitenon and uninjured synovial sheath showed significant engorgement with fibroblasts and macrophages post-injury.
- Synovial fibroblasts increased most notably within the first week.
- The endotenon displayed delayed cellular response, including initial apoptosis (P53 positive), followed by hypercellular activity at 12 weeks.
Conclusions:
- Tendon injury elicits distinct temporal and spatial cellular responses within different tendon compartments.
- The endotenon's delayed response and initial apoptosis suggest a unique healing cascade compared to the epitenon and synovial sheath.
Abstract:
The cellular changes in the epitenon, endotenon and synovial sheath were investigated in a rabbit model after a partial transverse laceration was made on the plantar aspect of the flexor digitorum profundus proximal to the synovial sheath (which was not injured). Fibroblasts, macrophages and mast cells within the epitenon, endotenon and synovial sheath were counted on electron micrographs. The epitenon and uninjured synovial sheath became engorged with fibroblasts and macrophages following injury. The number of synovial fibroblasts showed the greatest increase during the first week after injury. In comparison, the endotenon exhibited a delay in cellular response with initial apoptosis, as judged by positive P53 staining. However, hypercellular activity was seen within the endotenon at 12 weeks postoperatively.
