Andrew G. Urquhart

Total hip arthroplasty modular neck failure.

The use of modular components in total hip arthroplasty has increased in popularity. The advantages of modularity in hip arthroplasty include improved visualization during acetabular revision and restoration of proper hip biomechanics. Disadvantages include disassociation of components, failure at modular junctions, corrosion, and the generation of metal ions and debris. We present 2 cases that demonstrate the potential for modular neck fracture, requiring subsequent revision of well-fixed components.

Sonographic elasticity imaging of acute and chronic deep venous thrombosis in humans.

Objective. The purpose of this study was to assess the ability of sonographic elasticity imaging to distinguish acute from chronic deep venous thrombosis (DVT). Methods. Fifty‐four patients, 26 with acute DVT and 28 with chronic DVT, were studied, and we analyzed the data in 46 patients, 23 with acute (mean age, 5.7 days) and 23 with chronic (>8 months) DVT. Scanning was performed with a 5‐MHz linear array transducer during continuous freehand external deformation of each thrombus using the ultrasound scan head. The strains in the thrombi were normalized to the average strain between the skin surface and the back wall of the vein. Relative thrombus echogenicity was measured by comparing the echogenicity of the thrombus with that of the adjacent arterial lumen. Statistical analyses were performed with the Mann‐Whitney U test and receiver operating characteristic analysis. Results. The median normalized strain magnitude for the acute cases was 2.75, with an interquartile range of 2.4 to 3.71, whereas the median normalized strain magnitude for the chronic cases was 0.94, with interquartile range of 0.48 to 1.36. The difference was highly significant (P < 10−7). The area under the receiver operating characteristic curve (Az) was 0.97 ± 0.02 (SE). The echogenicity difference between the populations was highly significant (P < 10−5), with Az of 0.92 ± 0.04. The difference between the Az values was not significant (P > .05). Conclusions. In this population, sonographic elasticity imaging performs at least as well as thrombus echogenicity. Thrombus aging using elasticity imaging would be particularly helpful in evaluating symptoms in patients with post‐thrombotic syndrome.

Characteristics of fibromyalgia independently predict poorer long-term analgesic outcomes following total knee and hip arthroplasty

While psychosocial factors have been associated with poorer outcomes after knee and hip arthroplasty, we hypothesized that augmented pain perception, as occurs in conditions such as fibromyalgia, may account for decreased responsiveness to primary knee and hip arthroplasty.

Interactions of T Cells with Fibroblast-Like Synoviocytes: Role of the B7 Family Costimulatory Ligand B7-H3

Fibroblast-like synoviocytes (FLS) and T cells can activate each other in vitro, and in vivo interactions between these cells may be important in rheumatoid arthritis (RA), yet FLS lack significant expression of CD28 ligands. We sought to identify molecules homologous to CD28 ligands that are strongly expressed by FLS, and documented strong B7-H3 expression on FLS and by fibroblasts of other tissues, which was unaffected by a variety of cytokines. Western blot analysis of FLS lysates showed predominant expression of the larger, four Ig-like domain isoform of B7-H3. Immunohistological sections of RA synovial tissue showed strong staining for B7-H3 on FLS. Cells expressing B7-H3 were distinct from but in close proximity to cells that expressed CD45, CD20, and CD3. Confocal microscopy of FLS and T cell cocultures showed localization of B7-H3 in the region of the T cell-FLS contact point, but distinct from the localization of T cell CD11a/CD18 (LFA-1) and FLS CD54 (ICAM-1). Reduction of B7-H3 expression on FLS by RNA interference affected interactions of FLS with resting T cells or cytokine-activated T cells. Resting T cells showed increased production of TNF-α, IFN-γ, and IL-2, whereas cytokine-activated T cells showed reduced cytokine production relative to control. However, cytokine production by T cells activated through their TCR was not notably altered by knock down of B7-H3. These observations suggest that B7-H3 may be important for the interactions between FLS and T cells in RA, as well as other diseases, and the outcome of such interactions depends on the activation state of the T cell.

Management and Prevention of Prosthetic Joint Infection

Prosthetic joint infection (PJI) is a serious complication of total joint arthroplasty (TJA) that can negatively affect functional status and quality of life. This article examines the epidemiology of PJI and reviews current diagnostic, treatment, and management strategies. Diagnosis can be challenging because presenting symptoms are often nonspecific and there is no simple gold standard diagnostic test. Successful treatment of PJI requires a combination of medical and surgical strategies. Given the devastating nature of PJI and the increasing numbers of TJAs performed, prevention efforts remain critical.

No Difference in Dislocation Seen in Anterior Vs Posterior Approach Total Hip Arthroplasty

BACKGROUND The direct anterior approach (DAA) for total hip arthroplasty (THA) has rapidly become popular, but there is little consensus regarding the risks and benefits of this approach in comparison with a modern posterior approach (PA). METHODS A total of 2147 patients who underwent DAA THA were propensity score matched with patients undergoing PA THA on the basis of age, gender, body mass index, and American Society of Anesthesia classification using data from a state joint replacement registry. Mean age of the matched cohort was 64.8 years, mean body mass index was 29.1 kg/m(2), and 53% were female. Multilevel logistic regression models using generalized estimating equations to control for grouping at the hospital level were used to identify differences in various outcomes. RESULTS There was no difference in the dislocation rate between patients undergoing DAA (0.84%) and PA (0.79%) THA. Trends indicating a slightly longer length of stay with the PA and a slightly greater risk of fracture, increased blood loss, and hematoma with the DAA are consistent with previous studies. CONCLUSION On the basis of short-term outcome and complication data, neither approach has a compelling advantage over each other, including no difference in the dislocation risk.

Conflict of Interest in the Assessment of Hyaluronic Acid Injections for Osteoarthritis of the Knee: An Updated Systematic Review

The search results of a recent systematic review of prospective, randomized, placebo-controlled trials on hyaluronic acid injections for knee arthritis were updated and reviewed for funding source and qualitative conclusions. Forty-eight studies were identified; 30 (62.5%) were industry funded, and 3 (6.25%) were not. Fifteen (31.3%) studies did not identify a funding source. An association was observed between a reported potential financial conflict of interest of the author and the qualitative conclusion (P=0.018). None of the studies with a reported financial conflict of interest of at least one author had an unfavorable conclusion; 11 (35%) of the 31 studies with no industry-affiliated authors indicated that hyaluronic acid injection for knee osteoarthritis was no more effective than a placebo injection.

The reproducibility of a kinematically-derived axis of the knee versus digitized anatomical landmarks using a knee navigation system.

Component position is critical to longevity of knee arthroplasties. Femoral component rotation is typically referenced from the transepicondylar axis (TEA), the anterior-posterior (AP) axis or the posterior condylar axis. Other studies have shown high variability in locating the TEA while proposing digitization of other landmarks such as the AP axis as a less-variable reference. This study uses a navigation system to compare the reproducibility of computing a kinematically-derived, navigated knee axis (NKA) to digitizing the TEA and AP axis. Twelve knees from unembalmed cadavers were tested. Four arthroplasty surgeons digitized the femoral epicondyles and the AP axis direction as well as flexed and extended the knee repeatedly to allow for NKA determination. The variance of the NKA axis determined under neutral loading conditions was smaller than the variance of the TEA axis when the kinematics were measured in the closed surgical condition (P<0.001). However, varus, valgus, and internal loading of the leg increased the variability of the NKA. Distraction of the leg during knee flexion and extension preserved the low variability of the NKA. In conclusion, a kinematically-derived NKA under neutral or distraction loading is more reproducible than the TEA and AP axis determined by digitization.

Expression and Function of Aminopeptidase N/CD13 Produced by Fibroblast Like Synoviocytes in Rheumatoid Arthritis: Role of CD13 in Chemotaxis of Cytokine Activated T cells Independent of Enzymatic Activity

Aminopeptidase N/CD13 (EC 3.4.11.2) is a metalloproteinase expressed by fibroblast‐like synoviocytes (FLS). It has been suggested that CD13 can act chemotactically for T cells in rheumatoid arthritis (RA). We undertook this study to measure CD13 in vivo and in vitro in RA samples and to determine whether CD13 could play a role in the homing of T cells to the RA joint.

Musculoskeletal care of the hemophiliac patient.

Abstract Hemophilia is caused by a deficiency of clotting factor VIII or IX and is inherited by a sex‐linked recessive pattern. von Willebrand disease, a common, moderate bleeding disorder, is caused by a quantitative or qualitative protein deficiency of von Willebrand factor and is inherited in an autosomal dominant or recessive manner. The most important clinical strategy for the management of patients with hemophilia is the avoidance of recurrent hemarthrosis by continuous, intravenous hematologic prophylaxis. Early hemarthrosis should be aggressively managed with aspiration and clotting factor concentrate until the joint examination is normal. Starting prophylactic factor replacement in infancy may prevent chronic synovitis and arthropathy. The natural history of poorly controlled disease is polyarticular hemophilic arthropathy; functional prognosis is poor. Patients with chronic synovitis may be treated effectively with radiosynovectomy; those who develop joint surface erosions may require realignment osteotomies, joint arthroplasty, and treatment of pseudotumors. Reconstructive surgery for hemophilic arthropathy, especially in patients with factor inhibitor, requires careful hematologic management by an experienced, multidisciplinary team.