; and Summa Health Systems, Akron, Ohio (IG) S U M M A R Y To test the hypothesis that a perturbation of endoplasmic reticulum (ER) function is involved in the pathogenesis of osteoarthritis (OA), articular cartilage was isolated from non-OA patients secondary to resection of osteo-or chondrosarcomas. Intra-joint samples of minimal and advanced osteoarthritic cartilage were isolated from patients undergoing total knee arthroplasty and scored for disease severity. Glucose-regulated protein-78 (grp78) and bcl-2-associated athanogene-1 (bag-1) were detected via immunofluorescence as markers of non-homeostatic ER function. Additionally, the expression of type VI collagen and its integrin receptor, NG2, was determined to examine cartilage matrix health and turnover. There was an upregulation of grp78 in advanced OA, and variable expression in minimal OA. Non-OA cartilage was consistently grp78 negative. The downstream regulator bag-1 was also upregulated in OA compared with normal cartilage. Collagen VI was mainly cellassociated in non-OA cartilage, with a more widespread distribution observed in OA cartilage along with increased intracellular staining intensity. The collagen VI integral membrane proteoglycan receptor NG2 was downregulated in advanced OA compared with its patientmatched minimally involved cartilage sample. These results suggest that chondrocytes exhibit ER stress during OA, in association with upregulation of a large secreted molecule, type VI collagen. (J Histochem Cytochem 57:923-931, 2009) K E Y W O R D S osteoarthritis cartilage ER stress bag-1 grp78 collagen VI NG2 OSTEOARTHRITIS (OA) IS A PROGRESSIVE DISEASE, with changes in chondrocyte gene expression and extracellular matrix (ECM) composition occurring before macroscopic structural damage is observed (Hamerman 1989). Articular chondrocytes in OA exhibit a hypermetabolic phenotype, with studies describing highly proliferative clonal chondrocytes, along with the upand downregulation of ECM molecules such as aggrecan

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A three-dimensional computer model of a total hip replacement was used to examine the relationship between the position of the components, the range of motion and the prosthetic joint contact area. Horizontal acetabular positions with small amounts of acetabular and femoral anteversion provide the largest contact areas, but result in limited joint movement. These data will allow surgeons to select implant positions that will provide the largest possible joint contact area for a given joint range of motion although these are conflicting goals. In some component positions a truncated spherical prosthetic head resulted in smaller contact areas than a completely spherical head.

Low back pain is one of the most common reasons for physician visits in the United States and is a chief complaint frequently seen by orthopedic surgeons. Patients with chronic low back pain can experience recurring debilitating pain and disability, decreasing their quality of life. A commercially available software platform, Explorys (Explorys, Inc, Cleveland, Ohio), was used to mine a pooled electronic health care database consisting of the medical records of more than 26 million patients. According to the available medical history data, 1.2 million patients had a diagnosis of low back pain (4.54%). The information was used to determine the incidence of low back pain in patients with a history of nicotine dependence, obesity (body mass index, >30 kg/m(2)), depressive disorders, and alcohol abuse. Relative risk was then calculated for the defined modifiable risk factors. Patients with nicotine dependence, obesity, depressive disorders, and alcohol abuse had a relative risk of 4.489, 6.007, 5.511, and 3.326 for low back pain, respectively, compared with patients without the defined risk factor. A statistically significant difference was found in the incidence of low back pain between all 4 groups with the risk factors evaluated and the general population (P<.05). By determining treatable patient risk factors for low back pain, physicians can monitor at-risk patients and focus on prevention and control of debilitating disease. These approaches can decrease the number of patients with isolated low back pain who are seen by orthopedic surgeons. [Orthopedics. 2016; 39(3):e413-e416.].