Prophylactic Tibial Stem Fixation in the Obese: Comparative Early Results in Primary Total Knee Arthroplasty.

Purpose: Obesity is a risk factor for aseptic loosening after total knee arthroplasty (TKA). Prophylactic use of tibial stems may enhance tibial fixation in obese patients. The aim of this study was to determine whether a tibial stem extension decreases rates of early failure in obese patients.

Form and functional repair of long bone using 3D-printed bioactive scaffolds.

Injuries to the extremities often require resection of necrotic hard tissue. For large-bone defects, autogenous bone grafting is ideal but, similar to all grafting procedures, is subject to limitations. Synthetic biomaterial-driven engineered healing offers an alternative approach.

Ultra-High-Molecular-Weight Polyethylene (UHMWPE) in Total Joint Arthroplasty.

Total joint arthroplasty of the hip and knee are successful orthopedic procedures that reduce pain and improve mobility in patients. As the implanted materials used in these procedures have improved, the lifetime of the implants has now reached more than 20 years. Younger patients are undergoing total joint arthroplasty at increasing rates, which has increased the need for improvements in materials for extended implant longevity.

Staphylococcus lugdunensis Septic Arthritis of a Native Knee A Case Report.

A 67-year-old man presented to orthopaedic care with a painful knee. Workup was consistent with septic arthritis of a native knee, and the patient underwent operative treatment. Cultures from the operating room were speciated to Staphylococcus lugdunensis.

Functional assessment of the ex vivo vocal folds through biomechanical testing: A review.

The human vocal folds are complex structures made up of distinct layers that vary in cellular and extracellular composition. The mechanical properties of vocal fold tissue are fundamental to the study of both the acoustics and biomechanics of voice production. To date, quantitative methods have been applied to characterize the vocal fold tissue in both normal and pathologic conditions.

Preliminary investigation of a novel technique for the quantification of the ex vivo biomechanical properties of the vocal folds.

The human vocal fold is a complex structure made up of distinct layers that vary in cellular and extracellular matrix composition. Elucidating the mechanical properties of vocal fold tissues is critical for the study of both acoustics and biomechanics of voice production, and essential in the context of vocal fold injury and repair. Both quasistatic and dynamic behavior in the 10-300 Hz range was explored in this preliminary investigation.

Periprosthetic Joint Infection in Patients Receiving TNFα Antagonists.

Tumor necrosis factor-α antagonists (anti-TNFα) have become increasingly more common as a treatment for rheumatoid arthritis (RA). However, there has been an increased incidence of severe infections in patients taking anti-TNFα therapy. We present a case series of RA patients treated with anti-TNFα therapy that had previously underwent TJA and subsequently developed periprosthetic infections.

The effects of loading conditions and specimen environment on the nanomechanical response of canine cortical bone.

Bone is a viscoelastic connective tissue composed primarily of mineral and type I collagen, which interacts with water, affecting its mechanical properties. Therefore, both the level of hydration and the loading rate are expected to influence the measured nanomechanical response of bone. In this study, we investigated the influence of three distinct hydration conditions, peak loads and loading/unloading rates on the elastic modulus and hardness of canine femoral cortical bone via nanoindentation.

Monotonic and fatigue behavior of five clinically relevant conventional and highly crosslinked UHMWPEs in the presence of stress concentrations.

Five formulations of clinically relevant UHMWPE (conventional, moderately crosslinked annealed and remelted, and highly crosslinked annealed and remelted) were investigated in a physiologically relevant environment. Their monotonic stress-strain behavior in the presence of notches of two different severities and at two different displacement rates was examined using a custom developed video based system. It was found that both an elevation of yield stress and a truncation of orientation hardening took place under monotonic loading and that these changes were found to be material and elastic stress concentration factor dependent.

Notch sensitivity of PEEK in monotonic tension.

Poly(ether-ether-ketone) (PEEK) has been used as a load bearing orthopaedic implant material with clinical success. All of the orthopaedic applications contain stress concentrations (notches) in their design; however, little work has been done to examine the stress-strain behavior of PEEK in the presence of a notch. This work examines both the stress-strain behavior and the fracture behavior of neat PEEK in a uniaxial loaded condition, and in circumferentially grooved round bar specimens with different elastic stress concentration factors.

Notched stress-strain behavior of a conventional and a sequentially annealed highly crosslinked UHMWPE.

Contemporary total joint replacement designs contain stress-risers such as fillets, grooves, and undercuts; therefore, it is of interest to analyze the behavior of UHMWPEs in the presence of such design-related stress-risers. This study examined the engineering and true axial stress-strain behavior of smooth cylindrical and notched cylindrical test specimens, under applied axial tensile loading (2 displacement rates, 37 degrees C) for a conventional and a highly crosslinked second generation UHMWPE. Both materials were prepared from ram extruded GUR 1050.

Large deformation compression induced crystallinity degradation of conventional and highly crosslinked UHMWPEs.

The effect of a large compressive plastic deformation on the melt temperature (Tm), lamellar thickness, crystallinity, and density of four UHMWPEs (two conventional and two highly crosslinked) was examined. The materials were prepared from a single batch of medical grade GUR 1050 resin (Ticona, Bayport, TX, USA). The two conventional UHMWPEs were as-received (virgin) and gamma radiation sterilized at 30 kGy in a nitrogen atmosphere (radiation sterilized).