title: Healing compared between bone to tendon and cartilage to tendon in a partial inferior patellectomy model in rabbits.
abstract: OBJECTIVE
  Sports injuries around bone-tendon junctions are not uncommon. This study was designed to perform a quantitative evaluation on healing characteristics at the cartilage-to-tendon (C-T) and the bone-to-tendon (B-T) healing junction in a temporal and spatial manner.
  
  
  METHODS
  Basic science study.
  
  
  METHODS
  University medical school.
  
  
  METHODS
  Thirty-two 18-week-old New Zealand white rabbits.
  
  
  METHODS
  All rabbits underwent partial inferior patellectomy. The operated patella-patellar tendon (PPT) complex was harvested at 2, 4, 8, and 16 weeks postoperatively (n = 8 for each time point).
  
  
  METHODS
  The fusion ratio (ie, the ratio of tissue integration calculated along the length of the healing junction interface at both C-T and B-T junction of sagittal plane of PPT complex).
  
  
  RESULTS
  The fusion ratio at the C-T interface was 69.5% and 85.9%, which was significantly greater as compared with 45.9% and 60.1% at the B-T interface at week 2 and week 4, respectively (P < 0.01 for both). Under polarized light microscope, a small amount of collagen fibers crossing the C-T junction was seen, but none were found at the B-T interface at week 2. At 4 weeks, there was a distinct fibrocartilage zone regenerated at the C-T junction, but there were only limited collagen fibers at the B-T junction. The difference in the fusion ratio, however, was diminished with healing over time between the C-T and B-T junctions at both week 8 (90.2% vs. 80.1%) and week 16 (93.1% vs. 85.3%) (both, P > 0.05).
  
  
  CONCLUSIONS
  These findings demonstrated that the C-T junction might have an earlier and faster healing potential as compared with that of the B-T repair. The earlier fusion of the C-T junction might provide earlier stability along the entire PPT healing interface that would form a basis for improved postoperative prognosis of PPT healing complex.
authors.affiliation: Department of Orthopaedics & Traumatology, Musculoskeletal Research Laboratory, The Chinese University of Hong Kong, Shatin, N.T. Hong Kong.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Lu
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Kwongman
authors.initials: K
authors.lastname: Lee
authors.forename: Wannar
authors.initials: W
authors.lastname: Wong
authors.forename: Kaiming
authors.initials: K
authors.lastname: Chan
authors.forename: Kwoksui
authors.initials: K
authors.lastname: Leung
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000601:surgery*; D002356:Cartilage / Q000601:surgery*; D006723:Hong Kong; D023421:Models, Animal; D017847:Patellar Ligament / Q000601:surgery*; D011817:Rabbits; D014945:Wound Healing / Q000502:physiology*