Immobilization-induced osteolysis and recovery in neuropathic foot impairments

- Before immobilization, foot temperature in Charcot neuroarthropathy subjects were higher than plantar ulcer subjects.
- Before immobilization, calcaneal BMD in NPU feet averaged 486 ± 136 mg/cm2 and CNA feet averaged 456 ± 138 mg/cm2, p > 0.05).
- After 14-16 weeks of cast immobilization, NPU feet lost 3 mg/cm2; CNA feet lost 48 mg/cm2 of BMD, p < 0.05.
- After 33-53 weeks of recovery, calcaneal BMD is blunted in CNA feet compared to NPU feet.
- After recovery, 61% of NPU index feet and 84% of CNA index feet were classified as osteopenic or osteoporotic, p < 0.05.

BackgroundNeuropathic foot impairments treated with immobilization and off-loading result in osteolysis. In order to prescribe and optimize rehabilitation programs after immobilization we need to understand the magnitude of pedal osteolysis after immobilization and the time course for recovery.ObjectiveTo determine differences in a) foot skin temperature; b) calcaneal bone mineral density (BMD) after immobilization; c) calcaneal BMD after 33-53 weeks of recovery; and d) percent of feet classified as osteopenic or osteoporotic after recovery in participants with neuropathic plantar ulcers (NPU) compared to Charcot neuroarthropathy (CNA).MethodsFifty-five participants with peripheral neuropathy were studied. Twenty-eight participants had NPU and 27 participants had CNA. Bilateral foot skin temperature was assessed before immobilization and bilateral calcaneal BMD was assessed before immobilization, after immobilization and after recovery using quantitative ultrasonometry.ResultsBefore immobilization, skin temperature differences in CNA between their index and contralateral foot were markedly higher than NPU feet (3.0 degree C versus 0.7 degree C, respectively, p < 0.01); BMD in NPU immobilized feet averaged 486 ± 136 mg/cm2, and CNA immobilized feet averaged 456 ± 138 mg/cm2, p > 0.05). After immobilization, index NPU feet lost 27 mg/cm2; CNA feet lost 47 mg/cm2 of BMD, p < 0.05. After recovery, 61% of NPU index feet and 84% of CNA index feet were classified as osteopenic or osteoporotic.ConclusionsThere was a greater osteolysis after immobilization with an attenuated recovery in CNA feet compared to NPU feet. The attenuated recovery of pedal BMD in CNA feet resulted in a greater percentage of feet classified as osteoporotic and osteopenic.