Development of a Global Design Education Experience in Bioengineering Through International Partnerships.

The field of engineering is increasingly appreciating the value of diversity for innovative design solutions. Successful engineering depends on our ability to explore constrained parameter spaces for finding the best solutions, and more diverse minds and experiences enable us to explore the entire potential solution space more thoroughly, more quickly, and more creatively. With a goal to expand the diversity of experiences and mindsets in our undergraduate bioengineering curricula, Arusha Technical College (ATC) in Arusha, Tanzania and Clemson University (CU) in Clemson, South Carolina, U.

Design and evaluation of a bioreactor with application to forensic burial environments.

Existing forensic taphonomic methods lack specificity in estimating the postmortem interval (PMI) in the period following active decomposition. New methods, such as the use of citrate concentration in bone, are currently being considered; however, determining the applicability of these methods in differing environmental contexts is challenging. This research aims to design a forensic bioreactor that can account for environmental factors known to impact decomposition, specifically temperature, moisture, physical damage from animals, burial depth, soil pH, and organic matter content.

Open-wedge high tibial osteotomy: incidence of lateral cortex fractures and influence of fixation device on osteotomy healing.

Purpose: Open-wedge high tibial osteotomy (HTO) is an established treatment for young and middle-aged patients with medial compartment knee osteoarthritis and varus malalignment. Although not intended, a lateral cortex fracture might occur during this procedure. Different fixation devices are available to repair such fractures.

Total knee arthroplasty designed to accommodate the presence or absence of the posterior cruciate ligament.

Evidence for selecting the same total knee arthroplasty prosthesis whether the posterior cruciate ligament (PCL) is retained or resected is rarely documented. This study reports prospective midterm clinical, radiographic, and functional outcomes of a fixed-bearing design implanted using two different surgical techniques. The PCL was completely retained in 116 knees and completely resected in 43 knees.

Clinical Outcomes of Tibial Components with Modular Stems Used in Primary TKA.

Due to the known potential for fretting and corrosion at modular junctions in orthopaedic implants, this retrospective study evaluated radiographic and clinical outcomes of 85 primary TKA patients implanted with modular stemmed tibial components and followed up for an average of 82 months. There was low incidence of tibial radiolucent lines, excellent functional outcomes, and no complications associated with stem modularity. The findings were comparable to the historical control study involving 107 TKA with a nonmodular tibial stem design.

Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations.

Background: Clinical consequences of alignment errors in total knee replacement (TKR) have led to the rigorous evaluation of surgical alignment techniques. Rotational alignment in the transverse plane has proven particularly problematic, with errors due to component malalignment relative to bone anatomic landmarks and an overall mismatch between the femoral and tibial components' relative positions. Ranges of nominal rotational alignment are not well defined, especially for the tibial component and for relative rotational mismatch, and some studies advocate the use of mobile-bearing TKR to accommodate the resulting small rotation errors.

Patients with no functional improvement after total knee arthroplasty show different kinematics.

Purpose: As many as 20 % of all patients following total knee arthroplasty are not satisfied with the result. Rotational alignment is one factor thought to affect clinical outcome. The purpose of this study was to assess relationships between prosthesis rotational alignment, function score and knee kinematics after TKA.

Repeatable procedure for evaluating taper damage on femoral stems with modular necks.

Understanding the performance of dual-taper modular femoral stems necessitates detailed quantitative assessment. This study reports a repeatable procedure to identify and measure damage on modular taper surfaces and determines whether damage area is a useful parameter for discerning modular femoral stem performance during in vitro corrosion and endurance tests. Twenty-four dual-taper modular necks representing a range of functional conditions were evaluated, including 15 necks previously subjected to in vitro testing and 9 necks explanted during revision hip arthroplasty.

Use of a deep polyethylene liner for the treatment of recurrent dislocation.

Modular component exchange is one of several viable options for treating instability after total hip arthroplasty (THA). Recently, we reported that polyethylene liners retrieved from stable THAs had significantly deeper cup articular geometry than liners retrieved from dislocated THAs. Modular liner exchange with implantation of a deeper cup articulation for the treatment of THA instability may be an option in certain cases.

Polyethylene damage and deformation on fixed-bearing, non-conforming unicondylar knee replacements corresponding to progressive changes in alignment and fixation.

Background: Deviations from nominal alignment of unicondylar knee replacements impact knee biomechanics, including the load and stress distribution at the articular contact surfaces. This study characterizes relationships between the biomechanical environment, distinguished by progressive changes in alignment and fixation, and articular damage and deformation in a consecutive series of retrieved unicondylar knee replacements.

Methods: Twenty seven fixed-bearing, non-conforming unicondylar knee replacements of one design were retrieved after 2 to 13 years of in vivo function.

Comparison of polyethylene tibial insert damage from in vivo function and in vitro wear simulation.

Function and wear of total knee arthroplasties were compared by analysis of damage patterns on polyethylene tibial inserts retrieved from patients (Group R) with inserts obtained after in vitro force-controlled knee joint wear simulation. Two simulator input profiles were evaluated, including standard walking (Group W), and combined walking and stair descent (Group W + S), simulating varied activities and a more severe physiological environment. Damage regions on all inserts were quantitatively assessed.

An in vivo model for intraoperative assessment of impingement and dislocation in total hip arthroplasty.

We have developed an intraoperative model to quantify total hip arthroplasty impingement and dislocation mechanics using fluoroscopy and shape-matching techniques. Two patient groups were investigated: group 1 consisted of 12 hips using 28- or 32-mm femoral heads and an anterolateral surgical approach, and group 2 consisted of 17 hips using 22- or 26-mm femoral heads and a posterolateral surgical approach. During intraoperative hip stability testing consisting of extension and external rotation motions, group 1 was more unstable, and prosthetic impingement was the major reason for dislocation.

Patterns of knee osteoarthritis in Arabian and American knees.

This study illustrates differences in the cartilage degeneration in osteoarthritic knees in patients with more frequent hyperflexion activities of daily living compared with Western patients. Proximal tibial articular cartilage wear and cruciate ligament condition were assessed in Saudi Arabian and North American patients with varus osteoarthritis undergoing total knee arthroplasty. In anterior cruciate ligament (ACL) intact knees, there were significant differences in wear location, with a clearly more anterior pattern in Saudi Arabian knees.

Association between dislocation, impingement, and articular geometry in retrieved acetabular polyethylene cups.

We used a novel analysis technique and retrieved acetabular polyethylene liners to investigate relationships between impingement damage, dislocation history, and polyethylene liner geometry. Forty-eight polyethylene liners with neutral rim elevation were visually assessed for peripheral rim damage consistent with impingement between the liner rim and femoral component. Liner articular geometry was measured using a digital stylus, and the geometric relationships between the liner rim and center of the femoral head were characterized by lip height, head center inset, and head penetration into the polyethylene liner.

Backside damage corresponding to articular damage in retrieved tibial polyethylene inserts.

Although motion between the polyethylene insert and tibial baseplate is one probable cause of backside wear, articular contact stresses and kinematic conditions may be additional factors. However, comparisons of articular and backside damage patterns are limited. We report the effect of physiologic loading on the modular capture mechanism and distribution of articular and backside surface damage patterns on retrieved tibial components.

Computational wear prediction of a total knee replacement from in vivo kinematics.

Wear of ultra-high molecular weight polyethylene bearings in total knee replacements remains a major limitation to the longevity of these clinically successful devices. Few design tools are currently available to predict mild wear in implants based on varying kinematics, loads, and material properties. This paper reports the implementation of a computer modeling approach that uses fluoroscopically measured motions as inputs and predicts patient-specific implant damage using computationally efficient dynamic contact and tribological analyses.

Closed reduction of constrained total hip arthroplasty.

Many surgeons use acetabular components with constrained polyethylene liners to improve stability in patients with a history of hip dislocation. Considering that the reported incidence of hip dislocation in patients with constrained components is 4% to 29%, it generally is recognized that open reduction would likely be necessary in cases of redislocation. Recent reports have indicated that closed reduction of constrained total hip arthroplasty is possible in some cases.