Outcomes of posterior cervical fusion and decompression: a systematic review and meta-analysis.

Background Context: Posterior cervical fusion (PCF) with decompression is a treatment option for patients with conditions such as spondylosis, spinal stenosis, and degenerative disc disorders that result in myelopathy or radiculopathy. The annual rate, number, and cost of PCF in the United States has increased. Far fewer studies have been published on PCF outcomes than on anterior cervical fusion (ACF) outcomes, most likely because far fewer PCFs than ACFs are performed.

Prolonged Conservative Management in Total Joint Arthroplasty: Harming the Patient?

Background: It is important to understand the long-term consequences of postponing total joint arthroplasty until the onset of severe functional impairment. Therefore, the purpose of this investigation was to determine and compare the midterm to long-term postoperative outcomes of patients who underwent total joint arthroplasty with severe vs less severe preoperative functional impairment.

Methods: A total of 105 primary unilateral total hip/knee arthroplasty patients were studied.

Preoperative Glycemic Control on Total Joint Arthroplasty Patient-Perceived Outcomes and Hospital Costs.

Background: The purpose of this study was to determine the influence of preoperative glycemic control in diabetic patients undergoing a primary total hip or knee arthroplasty. We wanted to study patient-perceived outcomes in the medium term, the length of stay, hospital costs, and rate of short-term postoperative complications.

Methods: One hundred twenty consecutive primary total joint arthroplasties (TJAs) performed in type 2 diabetic patients were stratified into 2 groups representing optimal and suboptimal preoperative glycemic control, based on serum levels of glycated hemoglobin (HbA), and those groups compared.

Protrusio After Medial Acetabular Wall Breach in Total Hip Arthroplasty.

Background: Medial protrusio is a recognized complication of total hip arthroplasty, but it is not known if a medial wall breach during cup implantation increases the risk. We thus investigated the effect of up to a 2 cm defect in the medial acetabular wall in a cadaveric model. Separately, we investigated the ability of acetabular screws to rescue the construct.

Bearing-Foreign Material Deposition on Retrieved Co-Cr Femoral Heads: Composition and Morphology.

Bearing-foreign material deposition onto a femoral head can occur from contact with an acetabular shell due to dislocation, reduction, or subluxation. The purpose of this study was to comprehensively characterize deposit regions on retrieved cobalt-chrome femoral heads from metal-on-polyethylene total hip arthroplasties that had experienced such adverse events. The morphology, topography, and composition of deposition regions were characterized using macrophotography, optical profilometry, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy.

THA Retrievals: The Need to Mark the Anatomic Orientation of the Femoral Head.

The hypothesis of this study was that the rotational orientation of femoral head damage would greatly affect the volumetric wear rate of the opposing polyethylene (PE) liner. Damage on twenty retrieved cobalt-chromium femoral heads was simulated in a validated damage-feature-based finite element model. For each individual retrieval, the anatomic orientation of the femoral head about the femoral neck axis was systematically varied, in 30° increments.

Distinctive damage patterns on THA metal bearing surfaces: case studies.

Retrieval analysis of total joint arthroplasty components has primarily focused on assessing wear or other damage to polyethylene components. As damage to the opposing bearing surface can accelerate polyethylene wear and damage, and especially with the use of hard-on-hard articulations, retrieval analysis benefits from incorporating evaluation of hard bearing surfaces as well. The purpose of this study is to report six case studies of metal bearing surfaces with distinctive damage patterns, to interpret them in the context of adverse events plausibly responsible for their creation, and to suggest their likely clinical or scientific significance.

Fracture of a BIOLOX Delta Ceramic Femoral Head Articulating Against a Polyethylene Liner: A Case Report.

Case: A forty-five-year-old woman underwent primary total hip arthroplasty with a 36-mm BIOLOX delta ceramic femoral head articulating against a polyethylene liner. She presented with hip pain at eighteen months postoperatively, two months after being in a bicycle accident; fracture of the femoral head was diagnosed.

Conclusion: The possibility of a ceramic femoral head fracture should be decreased with use of the latest generation of ceramic material, a ceramic-on-polyethylene articulation rather than a ceramic-on-ceramic articulation, and a larger head size, all of which applied to this case.

Modeling polyethylene wear acceleration due to femoral head dislocation damage.

Scratching, scraping, and metal transfer to femoral heads commonly accompany acetabular shell contact during dislocation and closed reduction maneuvers. While head damage conceptually leads to accelerated wear, reports on this subject are mainly anecdotal, and differ widely on the potency of such effect. Towards better understanding this relationship, a physically validated finite element (FE) model was used to compute polyethylene wear acceleration propensity of specific head damage patterns on thirteen retrievals.

FREQUENCY CONTENT OF CARTILAGE IMPACT FORCE SIGNAL REFLECTS ACUTE HISTOLOGIC STRUCTURAL DAMAGE.

Objective: The objective of this study was to determine if acute cartilage impact damage could be predicted by a quantification of the frequency content of the impact force signal.

Design: Osteochondral specimens excised from bovine lateral tibial plateaus were impacted with one of six impact energies. Each impact force signal underwent frequency analysis, with the amount of higher-frequency content (percent of frequency spectrum above 1 KHz) being registered.

Replication of chronic abnormal cartilage loading by medial meniscus destabilization for modeling osteoarthritis in the rabbit knee in vivo.

Medial meniscus destabilization (MMD) is a surgical insult technique for modeling osteoarthritis (OA) by replicating chronic abnormal cartilage loading in animal joints in vivo. The present study aimed to characterize the immediate biomechanical effects (ex vivo) and short-term histological consequences (in vivo) of MMD in the rabbit knee. In a compressive loading test, contact stress distribution in the medial compartment was measured in eight cadaver rabbit knees, initially with all major joint structures uninjured (Baseline), after MMD, and finally after total medial meniscectomy (TMM).

Encoding scratch and scrape features for wear modeling of total joint replacements.

Damage to hard bearing surfaces of total joint replacement components typically includes both thin discrete scratches and broader areas of more diffuse scraping. Traditional surface metrology parameters such as average roughness (R a) or peak asperity height (R p) are not well suited to quantifying those counterface damage features in a manner allowing their incorporation into models predictive of polyethylene wear. A diffused lighting technique, which had been previously developed to visualize these microscopic damage features on a global implant level, also allows damaged regions to be automatically segmented.

Cartilage-on-cartilage versus metal-on-cartilage impact characteristics and responses.

A common in vitro model for studying acute mechanical damage in cartilage is to impact an isolated osteochondral or cartilage specimen with a metallic impactor. The mechanics of a cartilage-on-cartilage (COC) impact, as encountered in vivo, are likely different than those of a metal-on-cartilage (MOC) impact. The hypothesis of this study was that impacted in vitro COC and MOC specimens would differ in their impact behavior, mechanical properties, chondrocyte viability, cell metabolism, and histologic structural damage.

Enhancing damage visibility on metallic bearing surfaces: a simple technique for photography and viewing.

Damage to metallic bearing surfaces typically involves scratches, scrapes, metal transfer, and organic deposits. This damage can cause accelerated wear of the opposing surface and subsequent implant failure. Photography and viewing of metallic bearing surfaces, for documenting this damage, are hindered by optical reflectivity.

A novel formulation for scratch-based wear modelling in total hip arthroplasty.

Damage to the femoral head in total hip arthroplasty often takes the form of discrete scratches, which can lead to dramatic wear acceleration of the polyethylene (PE) liner. Here, a novel formulation is reported for finite element (FE) analysis of wear acceleration due to scratch damage. A diffused-light photography technique was used to globally locate areas of damage, providing guidance for usage of high-magnification optical profilometry to determine individual scratch morphology.

Cementing acetabular liners into secure cementless shells for polyethylene wear provides durable mid-term fixation.

Background: In a previous experiment studying cementation of liners into cementless acetabular shells, placing grooves in the liner in a spider-web configuration created the greatest construct strength. Scoring shells without screw holes or other texturing helped prevent failure at the shell-cement interface. However, it was unclear whether these practices caused durable constructs in patients.

Biomechanical study of 16-mm threaded, 32-mm threaded, and fully threaded SCFE screw fixation.

Background: The initial goals of the treatment of slipped capital femoral epiphysis (SCFE) are to stabilize the epiphysis, prevent slip progression, and avoid complications. In situ fixation with a single screw is the most accepted procedure to provide an optimal fixation, but fixation failure and slip progression suggest that the procedure might be improved. The aim of the present study was to biomechanically compare partially threaded screws (16 mm and 32 mm) and fully threaded screws in an in vitro porcine model.

Scratching vulnerability of conventional vs highly cross-linked polyethylene liners because of large embedded third-body particles.

The hypothesis of this study was that acetabular liner vulnerability to scratching from femoral heads, roughened by third bodies embedded in the liner, is not significantly lower for highly cross-linked polyethylene (HXPE) than for conventional polyethylene (CPE). Six CPE and 6 HXPE acetabular liners were each reproducibly embedded with 5 cobalt-chromium-molybdenum (CoCrMo) beads then run for 10,000 cycles in a joint simulator. By visual rank ordering, there was low association between liner scratch severity and polyethylene type.

Instability dependency of osteoarthritis development in a rabbit model of graded anterior cruciate ligament transection.

Background: Joint instability has long been empirically recognized as a leading risk factor for osteoarthritis. However, formal mechanistic linkage of instability to osteoarthritis development has not been established. This study aimed to support a clinically accepted, but heretofore scientifically unproven, concept that the severity and rapidity of osteoarthritis development in unstable joints is dependent on the degree of instability.

Organ-level histological and biomechanical responses from localized osteoarticular injury in the rabbit knee.

The processes of whole-joint osteoarthritis development following localized joint injuries are not well understood. To demonstrate this local-to-global linkage, we hypothesized that a localized osteoarticular injury in the rabbit knee would not only cause biomechanical and histological abnormalities in the involved compartment but also concurrent histological changes in the noninvolved compartment. Twenty rabbits had an acute osteoarticular injury that involved localized joint incongruity (a 2-mm osteochondral defect created in the weight-bearing area of the medial femoral condyle), while another 20 received control sham surgery.

Volumetric topological analysis: a novel approach for trabecular bone classification on the continuum between plates and rods.

Trabecular bone (TB) is a complex quasi-random network of interconnected plates and rods. TB constantly remodels to adapt to the stresses to which it is subjected (Wolff's Law). In osteoporosis, this dynamic equilibrium between bone formation and resorption is perturbed, leading to bone loss and structural deterioration.

Methodology for measuring the in vitro seating and unseating forces of prefabricated attachment systems used to retain implant overdentures.

Purpose: The purpose of this in vitro investigation was to measure the forces generated during the continuous seating and unseating of prefabricated attachment systems used to retain implant overdentures.

Materials And Methods: An experimental design consisting of interchangeable fixture mounts, a radially indexable fixture holder, and a materials testing systems (MTS) machine was used to measure forces generated during the insertion and removal of spherical stud attachments (Straumann, Inc, Waltham, WA). Three separate experiments were conducted measuring the seating and unseating forces of a vertically aligned patrix/matrix assembly, a 20 degrees angled patrix opposing a vertically positioned matrix, and a vertically positioned patrix opposing a 20 degrees angled matrix.

Structural properties of fourth-generation composite femurs and tibias.

The purpose of this study was to measure the structural properties of the latest design (fourth-generation) of composite femurs and tibias from Pacific Research Laboratories, Inc. Fourth-generation composite bones have the same geometries as the third-generation bones, but the cortical bone analogue material was changed to one with increased fracture and fatigue resistance, tensile and compressive properties, thermal stability, and moisture resistance. The stiffnesses of the femurs and tibias were tested under bending, axial, and torsional loading, and the longitudinal strain distribution along the proximal-medial diaphysis of the femur was also determined.

Effects of episodic subluxation events on third body ingress and embedment in the THA bearing surface.

In total joint arthroplasty, third body particle access to the articulating surfaces results in accelerated wear. Hip joint subluxation is an under-recognized means by which third body particles could potentially enter the otherwise closely conforming articular bearing space. The present study was designed to test the hypothesis that, other factors being equal, even occasional events of femoral head subluxation greatly increase the number of third body particles that enter the bearing space and become embedded in the acetabular liner, as compared to level-walking cycles alone.

Stability differentials for proximal vs distal fusion of total hip arthroplasty femoral impaction grafts.

In impaction grafting for revision joint arthroplasty, the morselized cancellous bone ideally remodels into a new contiguous lattice. However, the use of biologically active factors may sometimes be indicated to enhance fusion. The purpose of this study was to determine the stability of femoral impaction-graft constructs for which either only the proximal or distal half of the morselized cancellous bone volume was modeled as fused.