Radiographic Evaluation of Bone Adaptation Adjacent to Percutaneous Osseointegrated Prostheses in a Sheep Model

Abstract

Background Percutaneous osseointegrated prostheses (POPs) are being investigated as an alternative to conventional socket suspension and require a radiographic followup in translational studies to confirm that design objectives are being met. Questions/purposes In this 12-month animal study, we determined (1) radiographic signs of osseointegration and (2) radiographic signs of periprosthetic bone hypertrophy and resorption (adaptation) and (3) confirmed them with the histologic evidence of host bone osseointegration and adaptation around a novel, distally porous-coated titanium POP with a collar. Methods A POP device was designed to fit the right metacarpal bone of sheep. Amputation and implantation surgeries (n = 14) were performed, and plane-film radiographs were collected quarterly for 12 months. Radiographs were assessed for osseointegration (fixation) and bone adaptation (resorption and hypertrophy). The cortical wall and medullary canal widths were used to compute the cortical index and expressed as a percentage. Based on the cortical index changes and histologic evaluations, bone adaptation was quantified. Results Radiographic data showed signs of osseointegration including those with incomplete seating against the collar attachment. Cortical index data indicated distal cortical wall thinning if the collar was not seated distally. When implants were bound proximally, bone resorbed distally and the diaphyseal cortex hypertrophied. Conclusions Histopathologic evidence and cortical index measurements confirmed the radiographic indications of adaptation and osseointegration. Distal bone loading,

Biomechanical Characterisation of Bone-anchored Implant Systems for Amputation Limb Prostheses: A Systematic Review

“…Geometrical fit between the implant and the bone appears to be crucial for a successful outcome as observed by loosening and failure of undersized implants, 5 , 8 or fracture at the insertion of oversized implants. 44 Bone ingrowth is dependent on the implant material, the implant design, and the geometrical fit in the bone. 9 In all of the studied implant systems except the ILP, the bulk material of the implant is the titanium alloy Ti6Al4 V. In the ILP, a cobalt-chrome-molybdenum alloy is used instead.…”

Upper extremity prosthetic selection influences loading of transhumeral osseointegrated systems

“…Osseointegrated implant research has been conducted in animal models looking at the bone [6][7][8][9][10] and soft tissue response [11][12][13]. Post-operative outcomes have been published for transhumeral OI implanted patients implanted abroad [14][15][16].…”

Variation in bone response to the placement of percutaneous osseointegrated endoprostheses: A 24-month follow-up in sheep

“…In order to circumvent these outcomes, an end-loading endoprosthesis was designed. Research conducted jointly at the VA Salt Lake City Health Care System and at the University of Utah Orthopaedic Center has shown that a porous commercially pure titanium coating provided a stable integration of bone with a titanium-alloy endoprosthesis [12–16]. The design consisted of a line-to-line endoprosthesis that fit the surgically prepared medullary canal of the transmetaphyseal-amputated, fused 3–4 metacarpal of the sheep forelimb [12, 16].…”

“…Research conducted jointly at the VA Salt Lake City Health Care System and at the University of Utah Orthopaedic Center has shown that a porous commercially pure titanium coating provided a stable integration of bone with a titanium-alloy endoprosthesis [12–16]. The design consisted of a line-to-line endoprosthesis that fit the surgically prepared medullary canal of the transmetaphyseal-amputated, fused 3–4 metacarpal of the sheep forelimb [12, 16]. Sheep were chosen for the investigation [12, 16], because they provided a translational large animal model with both body weight and bone remodeling rate comparable to those of an adult human [17].…”

“…The design consisted of a line-to-line endoprosthesis that fit the surgically prepared medullary canal of the transmetaphyseal-amputated, fused 3–4 metacarpal of the sheep forelimb [12, 16]. Sheep were chosen for the investigation [12, 16], because they provided a translational large animal model with both body weight and bone remodeling rate comparable to those of an adult human [17]. The forelimb was chosen as the site for implantation because the standing orientation of the forelimb is more vertical than that of the hind-limb [18].…”