Surgical periosteal resection changes bone geometry and strength in New Zealand white rabbits

Multiple pediatric neuromuscular conditions can result in thin and gracile long bone formation with increased risk of pathologic fracture. Following previous observations, we sought to characterize structural changes after periosteal resection to determine its potential as a novel strategy to increase bone diameter and strength as an adjunct to prevent pathologic fractures. Fifty-three 7-wk-old New Zealand white rabbits underwent unilateral proximal tibial periosteal resection. Assessments up to 8 wk following the procedure included growth rates, growth plate thickness, periosteal collagen alignment, micro-CT trabecular patterns, BMD and BMC, shape modeling, and mechanical testing to failure. We found differential growth acceleration at the proximal and distal tibia over the study period. Physeal thickness decreased with age; however, the reserve/proliferative zone increased during the periods of accelerated growth. At 8 wk postoperative, juxta-physeal trabecular structural model index was greater, indicating a more rod-like trabecular architecture, while distal tibial diaphysis demonstrated increased cortical porosity in the experimental limbs. Tibial length and mid-point circumference were greater in the experimental limbs, indicating they were larger, and 2D BMD and BMC were also increased in these tibiae. Statistical shape analysis demonstrated that the operative tibiae had more procurvatum (proximal bend) than the shams, presumably from the effect of accelerated tibial growth in the presence of an intact fibula. These 3D changes in shape and increased cortical porosity likely explain why the experimental tibia was weaker in torsion than the shams despite being geometrically larger with greater mineral content. This study demonstrates that localized perturbation in the proximal periosteum can alter multiple characteristics within the bone, leading to changes throughout its entire structure. While the increased geometric size, bone density, and mineral content were encouraging for the translational purposes of this work, the inferior mechanical properties, limit its potential as a bone strengthening adjunct without additional study.