title: Rotator cuff repair augmentation with local autogenous bone marrow via humeral cannulation in a rat model.
abstract: BACKGROUND
  Growth factors have been shown to improve healing after rotator cuff repair. Bone marrow is a potential vehicle for growth factor augmentation, yet methods of delivering marrow to cuff repair sites are still under-researched. We hypothesized that a cannulated humeral implant would deliver local bone marrow and thereby improve healing in a rat model.
  
  
  METHODS
  Twenty-eight rats underwent bilateral rotator cuff injury and repair. Each rat acted as its own control, randomized to a cannulated humeral implant in one shoulder and a solid implant in the other. Rats were euthanized at 4 and 8 weeks to create 4 time-treatment cohorts. Tendon healing was evaluated by dimensional measurements, biomechanical testing, and histology.
  
  
  RESULTS
  Tendon thickness, all biomechanical measures, and semi-quantitative histologic scores improved over time (P < .05) but not with treatment. The most common site of biomechanical tendon failure was midsubstance in the 8-week cannulated cohort and at the tendon footprint in the other 3 cohorts. Intraluminal bone growth was evident in all cannulated implants.
  
  
  CONCLUSIONS
  Humeral cannulation did not quantifiably improve tendon-to-bone healing in a rat model. The diminutive size of implants in rats, however, may have prevented sufficient delivery of local autogenous bone marrow; hence, further study in a larger animal is recommended.
authors: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 W. 168th St., New York, NY 10032, USA.
authors: David M
authors: DM
authors: Levy
authors: Comron
authors: C
authors: Saifi
authors: Jennifer L
authors: JL
authors: Perri
authors: Renwen
authors: R
authors: Zhang
authors: Thomas R
authors: TR
authors: Gardner
authors: Christopher S
authors: CS
authors: Ahmad
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D002404:Catheterization; D004195:Disease Models, Animal; D006811:Humerus; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D000070636:Rotator Cuff Injuries; D053441:Suture Anchors; D013708:Tendon Injuries / Q000473:pathology / Q000628:therapy*; D014182:Transplantation, Autologous; D014945:Wound Healing
keywords: Basic Science Study; Molecular and Cell Biology; Shoulder; bone marrow; cannulation; enthesis; rat; repair; rotator cuff