Nonvascularized Cartilage Grafts Versus Vascularized Cartilage Flaps: Comparison of Cartilage Quality 6 Months After Transfer

Purpose: Subchondral perfusion of osteochondral grafts has been shown to be important in preventing long-term cartilage degeneration. In carpal reconstruction, subchondral perfusion from the graft bed is limited. This study's purpose was to compare the histological characteristics of cartilage in osteochondral grafts supported by synovial imbibition alone to cartilage of vascularized osteochondral flaps that have both synovial and vascular pedicle perfusion. Methods: Two adjacent osteochondral segments were harvested on the medial femoral trochlea in domestic 6- to 8-month-old pigs. Each segment measured approximately 12 mm × 15 mm × 17 mm. One segment was maintained on the descending geniculate artery vascular pedicle. The adjacent segment was separated from the pedicle to serve as a nonvascularized graft. A thin layer of methylmethacrylate cement was used to line the harvest site defect to prevent vascular ingrowth to the subsequently replaced specimens. The pigs were maintained on a high-calorie feed and returned to ambulation and full weight-bearing on the surgical legs. The animals were sacrificed after 6 months and the specimens were reharvested, sectioned, and examined. The cartilage was graded by 2 pathologists blinded to the origin of specimens as vascularized flaps or nonvascularized grafts. Results: All specimens were assigned scores utilizing the International Cartilage Repair Society grading system. Scoring for chondrocyte viability, cartilage surface morphology, and cell and matrix appearance was significantly higher in the vascularized osteochondral group than in the graft group. Conclusions: When deprived of subchondral perfusion from underlying bone, osteochondral vascularized flaps in an intrasynovial environment demonstrate superior cartilage quality and survival compared with nonvascularized grafts. Clinical relevance: In locations in which perfusion from surrounding bone may be limited (ie, proximal scaphoid or proximal lunate reconstruction), articular reconstruction using vascularized osteochondral flaps will yield superior cartilage organization and architecture than nonvascularized osteochondral grafts. The clinical and functional relevance of this finding requires further study.