A preliminary technique development for quantitative analysis of transhumeral bone, post-amputation, using a computed...

Bone anchored prostheses (BAP) provide an alternative to socket prostheses for many amputees. However, progressive loss of bone mineral density (BMD) after amputation can decrease bone strength and prosthesis support around these implants. Loading of bone following implantation has allowed for successful adoption of lower limb BAPs; however, less is known about BAPs in upper limb amputees. Herein, methods are described to analyze BMD in individuals with transhumeral amputation (THA). Seventeen participants with THA received CT scans with a quantitative computed tomography (QCT) phantom. However, due to software constraints that limited the field of view to complete bilateral analysis, only six (N= 6) of the seventeen participants could be included in the final dataset. Volumetric (vBMD) and total area BMD (aBMD) data were generated with QCT Pro and Bone Investigational Toolkit software (Mindways, Austin, TX) for amputated and intact contralateral limbs. Quantitative differences in total and cortical BMD between amputated and contralateral humeri were comparable for six participants, uniformly showing decreased BMD in the amputated limb. These decreases were significant (p< 0.05) in all participants and no significant correlation of cortical BMD with age or time since amputation was detected in this limited cohort. These preliminary results demonstrated that humerus BMD can be successfully analyzed with QCT software using a modified hip and spine protocol. The techniques developed will allow for clinical evaluation of BMD to assess how bone remodeling in the humerus is affected by a BAP.