title: Enhanced patella-patellar tendon healing using combined magnetic fields in a rabbit model.
abstract: BACKGROUND
  A combined magnetic field (CMF) is a composite of a dynamic sinusoidal magnetic field and a magnetostatic field. Stimuli from CMFs has proved to be an effective tool for healing problem fractures and spinal fusion procedures.
  
  
  OBJECTIVE
  Combined magnetic field technology will enhance healing of bone-tendon junction repair via endochondral ossification for regeneration of the fibrocartilage zone.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Forty-eight mature rabbits were randomly divided into CMF-treated and placebo-treated (control) groups. A partial patellectomy model was created. The CMF-treated group was subjected to CMF stimulation from the third postoperative day for 30 minutes per day up to weeks 8 or 16. At each time point, tissue samples were harvested and evaluated biomechanically and histomorphologically. The area of newly formed bone and the thickness of fibrocartilage were measured in hematoxylin and eosin-stained sections and toluidine blue-stained sections, respectively, while the density of fibrocartilage cells and the amount of proteoglycans were calculated using safranin O-stained sections. A biomechanical analysis was carried out to ascertain tensile strength.
  
  
  RESULTS
  Quantitative histological measurements showed that the newly formed bone and regenerated fibrocartilage zone in the CMF-treated group increased by a respective 99.2% and 41.9% compared with the control group at week 8 and a respective 97.8% and 22.8% at week 16. In the CMF-treated group at postoperative week 16, the amount of proteoglycans was 36.9% more than that of the control group, but the density of fibrocartilage cells was just 71.4% of the control group; there were no significant differences at week 8. Mechanical test results showed that energy to failure was not significantly different between the 2 groups at week 8. Yet, at week 16, load to failure, ultimate strength, and energy to failure in the CMF-treated group (311.0 ± 59.4 N, 8.46 ± 1.41 MPa, and 0.87 ± 0.17 J, respectively) were significantly higher than those in the control group (247.1 ± 65.6 N, 6.84 ± 1.12 MPa, and 0.52 ± 0.15 J, respectively).
  
  
  CONCLUSIONS
  Biophysical stimulation with CMFs enhances healing after bone-tendon junction injuries in a rabbit model.
  
  
  CONCLUSIONS
  These results demonstrate the feasibility of using CMFs for stimulating bone-tendon healing after repair.
authors: Department of Sports Medicine, Research Center of Sports Medicine, Xiangya Hospital, Central South University, Changsha, China.
authors: Daqi
authors: D
authors: Xu
authors: Department of Sports Medicine, Research Center of Sports Medicine, Xiangya Hospital, Central South University, Changsha, China Department of Spine Surgery, Xiangya Hospital, Central South University, Changsha, China.
authors: Tao
authors: T
authors: Zhang
authors: Department of Sports Medicine, Research Center of Sports Medicine, Xiangya Hospital, Central South University, Changsha, China Department of Spine Surgery, Xiangya Hospital, Central South University, Changsha, China.
authors: Jin
authors: J
authors: Qu
authors: Department of Sports Medicine, Research Center of Sports Medicine, Xiangya Hospital, Central South University, Changsha, China Department of Spine Surgery, Xiangya Hospital, Central South University, Changsha, China hongbinlu@hotmail.com jianzhonghu@hotmail.com.
authors: Jianzhong
authors: J
authors: Hu
authors: Department of Sports Medicine, Research Center of Sports Medicine, Xiangya Hospital, Central South University, Changsha, China hongbinlu@hotmail.com jianzhonghu@hotmail.com.
authors: Hongbin
authors: H
authors: Lu
mesh_terms: D000818:Animals; D002452:Cell Count; D005109:Extracellular Matrix / Q000473:pathology; D005260:Female; D051445:Fibrocartilage / Q000166:cytology / Q000502:physiology; D055909:Magnetic Field Therapy; D008853:Microscopy; D023421:Models, Animal; D010012:Osteogenesis / Q000502:physiology; D010027:Osteotomy; D010329:Patella / Q000293:injuries / Q000473:pathology*; D017847:Patellar Ligament / Q000293:injuries / Q000473:pathology*; D011509:Proteoglycans / Q000378:metabolism; D011817:Rabbits; D011897:Random Allocation; D012038:Regeneration; D013718:Tensile Strength / Q000502:physiology; D014945:Wound Healing / Q000502:physiology*
chemical_list: D011509:Proteoglycans
keywords: bone-tendon junction; combined magnetic field; endochondral ossification; fibrocartilage zone