Yarrow et al. (2015) - Bone loss in a new rodent model combining SCI and cast immobilization

Summary of Yarrow et al. (2015) - Bone loss in a new rodent model combining SCI and cast immobilization

Intro/Justification Development of a clinically relevant model of SCI-induced bone loss, that presents sublesional loading (due to spontaneous hindlimb recovering) via hind limb cast immobilization (IMM), subsequent to contusion SCI. Other purposes: 1. better characterise time frame of bone loss after SCI. 2.determine effect of residual muscle activity on skeletal integrity after SCI. 3. determine if treadmill exercise represents a means of improving skeletal integrity after SCI+IMM Hypothesis - SCI + IMM would exacerbate bone loss in comparison to SCI alone, and assisted treadmill exercise would prevent bone loss in SCI+IMM rats.

method overview SCI - Severe contusion Rats - 16 week old (skeletally-matured) Female Sprague-Dawley (280 - 300g) Figure present summary if the experiment design with the different groups of rats used.

CTR (n=6), SCI-7 (n = 5), SCI-21 (n=8), IMM alone (n=9), SCI+IMM (n=6) and SCI+IMM+TM (n =11) (cast removed before and reapplied after weight supported treadmill aectivity.

Method - Analysis Right distal femoral metaphysis, proximal tibial metaphysis and femoral neck were scanned with the SkyScan 1172 mCT scanner. BMD carried out with HA phantom and microarchitecture also assessed. mechanical testing of distal femoral metaphysis via anterior-posterior compression and bending test (23) (since most common fracture site in SCI population). Also indentation testing carried out.

RESults - body mass & Bone Body mass and whole bone characteristics shown in table.

Results - Trab. BMd df

Results - TRab. bmd pt

results - trab. bone morph.

results - Cort. bone morph.