Biomechanical considerations in the pathogenesis of osteoarthritis of the knee

Osteoarthritis is the most common joint disease and a major cause of disability. The knee is the large joint most affected. While chronological age is the single most important risk factor of osteoarthritis, the pathogenesis of knee osteoarthritis in the young patient is predominantly related to an unfavorable biomechanical environment at the joint. This results in mechanical demand that exceeds the ability of a joint to repair and maintain itself, predisposing the articular cartilage to premature degeneration. This review examines the available basic science, preclinical and clinical evidence regarding several such unfavorable biomechanical conditions about the knee: malalignment, loss of meniscal tissue, cartilage defects and joint instability or laxity

Radiocapitellar prosthetic arthroplasty: a report of 6 cases and review of the literature

Radiocapitellar prosthetic arthroplasty has recently been introduced to treat isolated degenerative arthritis of the radiocapitellar joint. Although this procedure is conceptually attractive and sound in situations in which radial head resection is inadequate, clinical experience is still limited. Its role in the treatment of isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow and forearm is not yet defined. Our purpose was to report the short-term results of 6 patients who were treated by radiocapitellar prosthetic arthroplasty for isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow, as well as to provide a review of the literature. Six patients were treated by radiocapitellar prosthetic arthroplasty for isolated degenerative arthritis of the radiocapitellar joint in the ligamentous-intact elbow. Their medical records were reviewed, and each patient was seen in the office. The mean follow-up period was 50 months (range, 30-64 months). The implant survival rate was 100%. Pain improved in all patients and all patients were satisfied. The mean flexion-extension arc increased from 98° (range, 75°-115°) to 110° (range, 105°-120°) (P = .17), and the mean pronation-supination arc increased from 133° (range, 75°-115°) to 143° (range, 120°-170°) (P = .34). The mean Disabilities of the Arm, Shoulder and Hand score was 24.3 (range, 6.7-52.5). According to the Mayo Elbow Performance Score, there were 3 excellent and 3 good results. The short-term follow-up results of radiocapitellar prosthetic arthroplasty for isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow and forearm seem favorable. Level IV, case series, treatment stud

Are Anidulafungin or Voriconazole Released from Polymethylmethacrylate In Vitro?

Depot delivery of antimicrobial agents is used for treatment and prevention of bacterial orthopaedic infections; there is little information regarding newer antifungal agents and their potential use in polymethylmethacrylate (PMMA) depot delivery. We determined the percent of anidulafungin or voriconazole present after polymerization in PMMA beads loaded with anidulafungin or voriconazole, and we assessed elution of anidulafungin or voriconazole from beads loaded with anidulafungin or voriconazole. Beads containing 7.5% anidulafungin or voriconazole were pulverized and incubated in Kreb's ringer buffer for 48 hours; the buffer was assayed for anidulafungin or voriconazole concentration. The in vitro release of anidulafungin and voriconazole from PMMA beads loaded with 7.5% anidulafungin or voriconazole was determined in triplicate in a continuous flow chamber. 0.7% of anidulafungin and 5.6% of voriconazole loaded in the beads were detected after polymerization. No anidulafungin was detected in the elution studies. The mean peak voriconazole concentration in the elution studies was 0.9 μg/mL. Anidulafungin may not be suitable for depot delivery in PMM

Distal humerus prosthetic hemiarthroplasty: midterm results

Treatment of comminuted distal humeral fractures remains challenging. Open reduction-internal fixation remains the preferred treatment, but is not always feasible. In selected cases with non-reconstructable or highly comminuted fractures, total elbow arthroplasty has been used, however, also with relatively high complication and failure rates. Distal humerus prosthetic hemiarthroplasty (DHA) may be an alternative in these cases. The purpose of this study was to report the midterm results of six patients that were treated by DHA for acute and salvage treatment of non-reconstructable fractures of the distal humerus. All six patients were treated by DHA for acute and salvage treatment of non-reconstructable fractures of the distal humerus. Medical records were reviewed, and each patient was seen in the office. Mean follow-up was 54 months (range 21-76 months). Implant survival was 100 %. Three were pain free and three had mild or moderate residual pain. Average flexion-extension arc was 95.8 degrees (range 70 degrees-115 degrees) and average pronation-supination arc was 165 degrees (range 150 degrees-180 degrees). In three, there was some degree of instability, which was symptomatic in one. One had motoric and sensory sequelae of a partially recovered traumatic ulnar nerve lesion. According to the Mayo Elbow Performance Score, there were three excellent, one good and two poor results. Four were satisfied with the final result, and two were not. In this case series of six patients with DHA for non-reconstructable distal humerus fractures, favorable midterm follow-up results were seen; however, complications were also observe

Radiocapitellar prosthetic arthroplasty: short-term to midterm results of 19 elbows

Few studies have discussed the short-term results of radiocapitellar (RC) prosthetic arthroplasty (PA). In this study, we assessed the short-term to midterm functional and radiographic results of elbows after RC PA. Our secondary aim was to assess the survival of the RC PA. We included 19 elbows in 18 patients with a mean follow-up of 35 months (range, 12-88 months). Patients were examined for instability and range of motion and were assessed using Mayo Elbow Performance Index and Oxford Elbow Score at any subsequent visits. RC PA was the primary treatment in 16 elbows, and 3 were revision radial head arthroplasty with concomitant capitellar resurfacing. Range of motion, pain, and functional scores improved significantly from the preoperative to the final follow-up visit. Categoric grouping of the final Mayo Elbow Performance Index outcome scores showed 9 excellent, 5 good, 3 fair, 0 poor, and 2 missing data. However, stability of the elbow remained unchanged. There was no pain in 11 patients, mild pain in 5, and moderate pain in 3. Radiographic assessment showed no significant progress in ulnohumeral arthritis, although 3 elbows showed osteoarthritis progression to a higher grade. There were no major complications, including infection, revision, disassembly of the components, or conversion to total elbow arthroplasty. Survival of the RC PA was 100%. Elbow arthritis seems to become stationary after RC PA. Symptomatic RC osteoarthritis would probably benefit from RC PA regardless of the etiolog

House Dust Mite-Promoted Epithelial-to-Mesenchymal Transition in Human Bronchial Epithelium

The molecular basis of airway remodeling and loss of epithelial integrity in asthma is still undefined. We aimed to establish if exposure of human bronchial epithelium (16HBE cells) to asthma-related stimuli can induce epithelial-to-mesenchymal transition (EMT), a key process in tissue repair and remodeling associated with loss of intercellular contacts. We studied the effects of fibrogenic cytokine TGF-beta and protease-containing aeroallergen house dust mite (HDM) on mesenchymal and epithelial markers, cytoskeleton organization, and activation of beta-catenin-driven reporter Top-FLASH. TGF-beta alone up-regulated vimentin and fibronectin, modestly down-regulated E-cadherin, but did not affect cytokeratin. HDM alone did not affect these markers, but promoted stress fibers. Importantly, when added to TGF-beta-primed epithelium, HDM induced E-cadherin internalization, enhanced beta-catenin-dependent transcription, and down-regulated cytokeratin. Regarding the underlying mechanisms, the stimuli together induced sustained myosin light chain phosphorylation, which was crucial for E-cadherin internalization and beta-catenin-dependent transcription. Previously, we showed that HIDM signals through the epidermal growth factor receptor (EGFR). Accordingly, inhibition of EGFR prevented TGF-beta/HDM-induced mesenchymalization. TGF-beta facilitated uncoupling of EGFR from E-cadherin, its negative regulator, and prolonged EGFR signaling. Thus, we show that HIDM promotes EMT in TGF-beta-primed epithelium. Analysis of primary epithelium appears consistent with this phenotypic change. We propose that TGF-beta secretion and dysregulated EGFR signaling may increase epithelial vulnerability to allergens and trigger the induction of EMT, a hitherto unrecognized contributor to airway remodeling in asthma

Cemented bipolar radial head arthroplasty: midterm follow-up results

Theoretical advantages of bipolar over monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-to-cement and cement-to-implant interfaces. Our purpose was to report the midterm results of cemented bipolar radial head arthroplasty. Twenty-five patients were treated by cemented bipolar radial head arthroplasty for acute fracture of the radial head, earlier treatment that had failed, or posttraumatic sequelae. One patient refused follow-up after surgery. Results are presented for the remaining 24 patients. At a mean follow-up of 50 months (range, 24-72 months), 1 prosthesis (4%) had been removed 2 years after implantation for dissociation of the prosthesis due to failure of the snap-on mechanism. There were 2 (8%) additional radiologic failures in the subluxated position: 1 prosthesis due to malalignment of the radius onto the capitellum and another due to ulnohumeral erosion. The average flexion-extension arc was 129° (range, 80°-140°), and the average pronation-supination arc was 131° (range, 40°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 83%. In 8 patients, the bipolar design compensated for radiocapitellar malalignment. The overall midterm outcome of this series of 25 cemented bipolar radial head arthroplasties can be considered favorable. There was 1 (4%) revision and 2 (8%) additional radiologic failures. The bipolar design was able to compensate for radiocapitellar malalignment. We suggest considering a cemented bipolar radial head prosthesis in case of concerns about radiocapitellar alignmen

Press-fit bipolar radial head arthroplasty, midterm results

Theoretical advantages of bipolar compared with monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-implant interfaces. Our purpose was to report the midterm results of press-fit bipolar radial head arthroplasty. Thirty patients were treated by press-fit bipolar radial head arthroplasty for acute fracture of the radial head, failed earlier treatment, or post-traumatic sequelae. Three patients were lost to follow-up. Results are presented for the remaining 27 patients. At mean follow-up of 48 months (range, 28-73), there had been 3 (11%) revisions. Two involved conversion to prosthetic radiocapitellar hemiarthroplasty for symptomatic capitellar abrasion; a third involved exchange of the articular component (ie, head) for instability. In all, the stems appeared well fixed. A prosthesis in a subluxed position accounted for the 1 (4%) additional radiologic failure. The average flexion-extension arc was 136° (range, 120°-145°), and the average pronation-supination arc was 138° (range, 70°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 70%. The overall midterm outcome of this series of 30 press-fit bipolar radial head arthroplasties can be considered favorable. Although the revision rate was 11%, the stems were well fixed in all. There was 1 (4%) additional radiologic failure. We suggest considering a press-fit bipolar radial head prosthesis for acute comminuted radial head fractures with limited bone loss of the proximal radiu

Why does radial head arthroplasty fail today? A systematic review of recent literature

Since the introduction of the radial head prosthesis (RHP) in 1941, many designs have been introduced. It is not clear whether prosthesis design parameters are related to early failure. The aim of this systematic review is to report on failure modes and to explore the association between implant design and early failure. A search was conducted to identify studies reporting on failed primary RHP. The results are clustered per type of RHP based on: material, fixation technique, modularity, and polarity. Chi-square tests are used to compare reasons for failure between the groups. Thirty-four articles are included involving 152 failed radial head arthroplasties (RHAs) in 152 patients. Eighteen different types of RHPs have been used. The most frequent reasons for revision surgery after RHA are (aseptic) loosening (30%), elbow stiffness (20%) and/or persisting pain (17%). Failure occurs after an average of 34 months (range, 0-348 months; median, 14 months). Press-fit prostheses fail at a higher ratio because of symptomatic loosening than intentionally loose-fit prostheses and prostheses that are fixed with an expandable stem (p < 0.01). Because of the many different types of RHP used to date and the limited numbers and evidence on early failure of RHA, the current data provide no evidence for a specific RHP design

Radial Head Arthroplasty: A Systematic Review

Despite the expanding body of literature on radial head arthroplasty, the increasing understanding of elbow anatomy, biomechanics, and kinetics, and the evolution of surgical techniques and prosthesis designs, there is currently no evidence to support one type of radial head prosthesis over another. The purposes of the present report were to review the literature and to explore the association between prosthesis design variables and the timing of surgery and the outcome of modern radial head arthroplasty. The literature search was limited to studies involving skeletally mature patients. Major databases were searched from January 1940 to May 2015 to identify studies relating to functional and subjective outcomes and radiographic results after radial head arthroplasty. Thirty articles involving 727 patients were included. Seventy percent of the implants were made of cobalt-chromium, 15% were made of pyrocarbon, 9% were made of titanium, and 6% were made of Vitallium. Seventy percent were monopolar, and 30% were bipolar. Twenty-one percent were cemented in place, 32% were press-fit, 32% were intentionally loose-fit, and 15% were fixed with an expandable stem. The weighted average duration of follow-up was 45 months. The rate of revision ranged from 0% to 29% among studies. The incidence of revision was 8% during 2,714 person-years of follow-up across all 727 patients, yielding a crude overall revision rate of 2.06 per 100 person-years of follow-up. The revision rate was not significantly affected by prosthesis polarity, material, or fixation technique, nor was it significantly affected by the delay of treatment. There was also no significant effect of prosthesis polarity, material, or fixation technique on postoperative range of motion. The Mayo Elbow Performance Score was only reported for half of the overall patient population, but, among those patients, the combined rate of excellent and good results was 85%. Seven percent of the overall patient population underwent secondary surgery about the elbow other than revision surgery. Twenty-three percent were reported to have 1 or more complications. On the basis of our analysis of the peer-reviewed English-language literature on radial head arthroplasty from January 1940 to May 2015, there seems to be no evidence to support one type of radial head prosthesis over another. The only exception is that silicone prostheses have been shown to be biologically and biomechanically insufficient. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidenc