Three-Year Outcomes of a Highly Porous Acetabular Shell in Primary Total Hip Arthroplasty.

This multicenter study evaluated survivorship, functional outcomes, complications, and radiographic outcomes for patients who underwent total hip arthroplasty using a newly developed highly porous 3-dimensional titanium implant. Excellent aseptic (99.6%) and all-cause (98%) survivorship and functional outcomes were found at 3-year follow-up.

Damage in total knee replacements from mechanical overload.

The mechanical loads acting across the knee joint following total knee replacements (TKR) during activities of daily living have recently been measured using instrumented TKRs. Using a series of postmortem retrieved TKR constructs we investigated whether these mechanical loads could result in damage to the implant bone interface or supporting bone in the tibia. Eighteen cemented en bloc tibial components (0 to 22 years in service) were loaded under axial compression in increments from 1 to 10 times body weight and digital image correlation was used to measure bone strain and interface micromotion during loading and unloading.

Increased initial cement-bone interlock correlates with reduced total knee arthroplasty micro-motion following in vivo service.

Aseptic loosening of cemented tibial components in total knee arthroplasty (TKA) has been related to inadequate cement penetration into the trabecular bone bed during implantation. Recent postmortem retrieval work has also shown there is loss of interlock between cement and bone by resorption of trabeculae at the interface. The goal of this study was to determine if TKAs with more initial interlock between cement and bone would maintain more interlock with in vivo service (in the face of resorbing trabeculae) and have less micro-motion at the cement-bone interface.

Peri-implant bone strains and micro-motion following in vivo service: a postmortem retrieval study of 22 tibial components from total knee replacements.

Biological adaptation following placement of a total knee replacements (TKRs) affects peri-implant bone mineral density (BMD) and implant fixation. We quantified the proximal tibial bone strain and implant-bone micro-motion for functioning postmortem retrieved TKRs and assessed the strain/micro-motion relationships with chronological (donor age and time in service) and patient (body weight and BMD) factors. Twenty-two tibial constructs were functionally loaded to one body weight (60% medial/40% lateral), and the bone strains and tray/bone micro-motions were measured using a digital image correlation system.

Loss of cement-bone interlock in retrieved tibial components from total knee arthroplasties.

Background: Aseptic loosening continues to be a short- and long-term complication for patients with cemented TKAs. Most studies to this point have evaluated tibial component fixation via radiographic changes at the implant-bone interface and quantification of component migration; direct assessment of morphologic features of the interface from functioning TKAs may provide new information regarding how TKAs function and are fixed to bone.

Questions/purposes: In a postmortem retrieval study, we asked: (1) What are the morphologic features at the cement-trabecular bone interface in retrieved tibial components? (2) Do constructs with greater time in service have less cement-trabecular bone interlock? (3) Do constructs with more estimated initial interlock sustain more interlock with in vivo service?

Methods: Fourteen postmortem retrieved tibial components with time in service from 0 to 20 years were sectioned and imaged at high resolution, and the current contact fraction, estimated initial interdigitation depth, current interdigitation depth, and loss of interdigitation depth were quantified at the cement-bone interface.

Interface micromotion of uncemented femoral components from postmortem retrieved total hip replacements.

Axial torsional loads representative of gait and stair climbing conditions were applied to transverse sections of 8 uncemented postmortem retrievals and a high-resolution imaging system with digital image correlation was used to measure local micromotion along the bone-implant interface. For 7 components that were radiographically stable, there was limited micromotion for gait loading (1.42 ± 1.

A wax barrier to simulate bone resorption for pre-clinical laboratory models of cemented total hip replacements.

Pre-clinical tests are often performed to screen new implant designs, surgical techniques, and cement formulations. In this work, we developed a technique to simulate the cement-bone morphology found with postmortem retrieved cemented hip replacements. With this technique, a soy wax barrier is created along the endosteal surface of the bone, prior to cementing of the femoral component.

Functional interface micromechanics of 11 en-bloc retrieved cemented femoral hip replacements.

Background And Purpose: Despite the longstanding use of micromotion as a measure of implant stability, direct measurement of the micromechanics of implant/bone interfaces from en bloc human retrievals has not been performed. The purpose of this study was to determine the stem-cement and cement-bone micromechanics of functionally loaded, en-bloc retrieved, cemented femoral hip components.

Methods: 11 fresh frozen proximal femurs with cemented implants were retrieved at autopsy.