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Research article2020Peer reviewedOpen access

The effect of housing environment on bone healing in a critical radius defect in New Zealand White rabbits

Hedenqvist, Patricia; Trbakovic, Amela; Mellgren, Torbjorn; Ohman-Magi, Caroline; Johansson, Petra Hammarstrom; Manell, Elin; Ekman, Stina; Ley, Cecilia; Jensen-Waern, Marianne; Thor, Andreas


In animal studies on bone healing, the effect of housing space and physical activity are seldom taken into account. Bone formation was evaluated in New Zealand White rabbits (mean +/- SEM BW: 3.9 +/- 0.11 kg) with a critical bone defect after 12 weeks of rehabilitation in pair-housing in 3 m(2) large floor pens (Floor, n = 10) or standard single housing in 0.43 m(2) cages (Cage, n = 10). In the randomised full-factorial study, a bone replica of calcium phosphate cement (CPC, n = 10) or autologous bone (AB, n = 10) was implanted in the unilateral 20 mm radius defect. Post-mortem, the oxidative capacity was measured by citrate synthase (CS) activity in M. quadriceps and the defect filling volume and density evaluated by microcomputer tomography (mu- CT). Histology sections were evaluated by subjective scoring and histomorphometry. Fourteen rabbits remained until the end of the study. Group Floor (n = 7; 3 CPC + 4 AB) had a higher CS activity and a larger bone defect filling volume and lower density by mu- CT measurements than group Cage (n = 7; 3 CPC + 4 AB). Three out of four rabbits in AB-Floor presented fusion of the defect with reorganisation of trabecular bone, whereas three of four in AB-Cage showed areas of incomplete healing. Floor rabbits had a higher score of bony fusion between the radius and ulna than Cage rabbits. There were no differences between groups in histomorphometry. The study found that a larger housing space increased physical activity and promoted bone formation.

Published in

2020, Volume: 15, number: 5, article number: e0233530