Stress shielding by rigid fixation studied in osteotomized rabbit tibiae

Abstract

In 48 rabbits the bone-formation rates and strength in the tibial shaft, osteotomized and treated with rigid internal plate fixation, were compared with contralateral bones, which were treated with plate fixation without osteotomy. The plate fixation alone induced a 35 percent decrease in torsional strength after 12 weeks. The healing of the osteotomy counteracted the decrease in strength induced by stress protection of the rigid plate at 6 weeks, but this effect subsided within 12 weeks. The osteotomy also induced a 2-3-fold increase in the synthesis of bone matrix and mineral accretion of the bone underlying the plate at 6 and 9 weeks when compared with the contralateral side, which was plated but not osteotomized. The bone-formation levels returned to normal within 12 weeks; and the bone underlying the plate became subject to atrophy, resulting in decreased mechanical strength.

Biomechanical characteristics of regenerated cortical bone in the canine mandible

“…Although the MBT device is placed in the buccal side, our results showed that the mechanical integrity of the regenerate cortical bone was lower on the buccal than the lingual side of the mandible. This finding could be due to the effect of three factors that can act either independently or jointly: first, the device could produce a stress‐shielding effect of the regenerate cortical bone on the buccal side, dampening potential mechanical stimulus; this condition should improve after the device is removed (Kennady et al , 1989; Laftman et al , 1989). Second, the relative position of the device within the mouth could affect the mechanical quality of the regenerate cortical bone because of its effect on inflammatory processes due to foreign body reaction after device placement (Anderson, 1988).…”

Orthopedics in Small Mammals

“…Because of the conformation of these species, a fracture of the humerus or femur can be difficult to manage with an external fixator. 26,47 If a plate is used, the animal may require staged plate removal, which is costly and unpopular with owners. If plating is chosen, the implants commonly used are 1.5-and 2.0-mm cuttable plates (Synthes, Ltd., Wayne, PA or Veterinary Instrumentation, Sheffield, UK).…”

Clodronate reduces plate osteopenia in the rabbit

“…To study matrix production in cortical bone, the animals were given 24 $ 3 3H-L-Proline (specific activity 100 Ci/mmol; Amersham, England) intramuscularly 2 days before analysis (LBftman et al 1989). In the analysis, the hydroxyproline was extracted from a cortical bone sample, and the 3H-proline activity was measured.…”