Coleman CM, Scheremeta BH, Boyce AT, Mauck RL, Tuan RS. Delayed fracture healing in growth differentiation factor 5-deficient mice: a pilot study.
Clin Orthop Relat Res 2011;
469:2915-24. [PMID:
21590487 PMCID:
PMC3171561 DOI:
10.1007/s11999-011-1912-0]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 04/29/2011] [Indexed: 01/31/2023]
Abstract
BACKGROUND
Growth differentiation factor-5 (GDF-5) is a key regulator of skeletogenesis and bone repair and induces bone formation in spinal fusions and nonunion applications by enhancing chondrocytic and osteocytic differentiation and stimulating angiogenesis. Elucidating the contribution of GDF-5 to fracture repair may support its clinical application in complex fractures.
QUESTIONS/PURPOSE
We therefore asked whether the absence of GDF-5 during fracture repair impaired bone healing as assessed radiographically, histologically, and mechanically.
METHODS
In this pilot study, we performed tibial osteotomies on 10-week-old male mice, stabilized by intramedullary and extramedullary nailing. Healing was assessed radiographically and histologically on Days 1 (n = 1 wild-type; n = 5 bp [brachopodism]), 5 (n = 3 wild-type; n = 3 bp), 10 (n = 6 wild-type; n = 3 bp), 14 (n = 6 wild-type; n = 6 bp), 21 (n = 6 wild-type; n = 6 bp), 28 (n = 7 wild-type; n = 6 bp), and 56 (n = 6 wild-type; n = 6 bp) after fracture. After 10 (n = 7 wild-type; n = 7 bp contralateral and n = 3 bp fractured tibiae), 14 (n = 6 wild-type; n = 6 bp), 21 (n = 6 wild-type; n = 6 bp), 28 (n = 6 wild-type; n = 3 bp), and 56 (n = 8 wild-type; n = 6 bp) days, the callus cross-sectional area was calculated. We characterized the mechanical integrity of the healing fracture by yield stress and Young's modulus at 28 (n = 6 wild-type; n = 3 bp) and 56 (n = 8 wild-type; n = 6 bp) days postfracture.
RESULTS
The absence of GDF-5 impaired cartilaginous matrix deposition in the callus and reduced callus cross-sectional area. After 56 days, the repaired bp fracture was mechanically comparable to that of controls.
CONCLUSIONS
Although GDF-5 deficiency did not compromise long-term fracture healing, a delay in cartilage formation and remodeling supports roles for GDF-5 in the early phase of bone repair.
CLINICAL RELEVANCE
Local delivery of GDF-5 to clinically difficult fractures may simulate cartilage formation in the callus and support subsequent remodeling.
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