Alex J Drew1, Carolyn E Taylor1, Robert Z Tashjian2, Peter N Chalmers3, Heath B Henninger1, Kent N Bachus4. 1. Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States of America; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America. 2. SLC VA Medical Center, Salt Lake City, UT, United States of America; Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States of America. 3. Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States of America. 4. SLC VA Medical Center, Salt Lake City, UT, United States of America; Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States of America; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America. Electronic address: kent.bachus@hsc.utah.edu.
Abstract
BACKGROUND: Percutaneous osseointegrated devices for skeletal fixation of prosthetic limbs have the potential to improve clinical outcomes in the transhumeral amputee population. Initial endoprosthesis stability is paramount for long-term osseointegration and safe clinical introduction of this technology. We evaluated an endoprosthetic design featuring a distally porous coated titanium stem with proximal slots for placement of bicortical interlocking screws. METHODS: Yield load, ultimate failure load, and construct stiffness were measured in 18 pairs of fresh-frozen and thawed cadaver humeri, at distal and proximal amputation levels, without and with screws, under axial pull-out, torsion, and bending loads. Paired statistical comparisons were performed without screws at the two resection levels, and at distal and proximal levels with and without screws. FINDINGS: Without screws, the location of the amputation influenced the stability only in torsional yield (p = 0.032) and torsional ultimate failure (p = 0.033). Proximally, the torsional yield and the torsional ultimate failure were 44% and 47% of that distally. Screws improved stability. In axial pull-out, screws increased the distal ultimate failure 3.2 times (p = 0.003). In torsion, screws increased the yield at the proximal level 1.9 times (p = 0.035), distal ultimate failure load 3.3 times (p = 0.016) and proximal ultimate failure 6.4 times (p = 0.013). In bending, screws increased ultimate failure at the proximal level 1.6 times (p = 0.026). INTERPRETATION: Proximal slots and bicortical interlocking screws may find application in percutaneous osseointegrated devices for patients with amputations, especially in the less stable proximal bone of a short residual limb.
BACKGROUND: Percutaneous osseointegrated devices for skeletal fixation of prosthetic limbs have the potential to improve clinical outcomes in the transhumeral amputee population. Initial endoprosthesis stability is paramount for long-term osseointegration and safe clinical introduction of this technology. We evaluated an endoprosthetic design featuring a distally porous coated titanium stem with proximal slots for placement of bicortical interlocking screws. METHODS: Yield load, ultimate failure load, and construct stiffness were measured in 18 pairs of fresh-frozen and thawed cadaver humeri, at distal and proximal amputation levels, without and with screws, under axial pull-out, torsion, and bending loads. Paired statistical comparisons were performed without screws at the two resection levels, and at distal and proximal levels with and without screws. FINDINGS: Without screws, the location of the amputation influenced the stability only in torsional yield (p = 0.032) and torsional ultimate failure (p = 0.033). Proximally, the torsional yield and the torsional ultimate failure were 44% and 47% of that distally. Screws improved stability. In axial pull-out, screws increased the distal ultimate failure 3.2 times (p = 0.003). In torsion, screws increased the yield at the proximal level 1.9 times (p = 0.035), distal ultimate failure load 3.3 times (p = 0.016) and proximal ultimate failure 6.4 times (p = 0.013). In bending, screws increased ultimate failure at the proximal level 1.6 times (p = 0.026). INTERPRETATION: Proximal slots and bicortical interlocking screws may find application in percutaneous osseointegrated devices for patients with amputations, especially in the less stable proximal bone of a short residual limb.
Authors: Carolyn E Taylor; Alex J Drew; Yue Zhang; Yuqing Qiu; Kent N Bachus; K Bo Foreman; Heath B Henninger Journal: PLoS One Date: 2020-08-06 Impact factor: 3.752
Authors: Alison M Karczewski; Weifeng Zeng; Lindsay M Stratchko; Kent N Bachus; Samuel O Poore; Aaron M Dingle Journal: Front Neurosci Date: 2022-04-12 Impact factor: 5.152