BackgroundCompared to the posterior approach, the anterior approach to total hip arthroplasty (THA) offers the potential for an accelerated recovery secondary to less dissection and therefore less pain in the immediate postoperative period. This offers potential financial benefit through a reduction in length of stay. This study retrospectively reviewed 98 anterior approach and 69 posterior approach THA cases (N = 167) to compare perioperative outcomes and cost-effectiveness.MethodsPatients who underwent anterior approach THA were discharged sooner than those who underwent posterior approach THA.ResultsThe anterior approach was also less expensive per patient than the posterior approach. Overall, differences in perioperative outcomes between these approaches to THA are less robust than previously reported. There is a significant difference in operative cost between these surgical approaches.ConclusionsAlthough there are many sources for this difference in cost, the predominant contributor is surgeon implant preference.

MRI utilization by orthopaedic surgeons results in more appropriate interventions for patients with symptoms and findings most amenable to surgical intervention.

Platelets release a soluble factor into blood and conditioned medium (PCM) that decreases vascular endothelial permeability. The objective of this study was to determine the signal-transduction pathway that elicits this decrease in permeability. Permeability-decreasing activity of PCM was assessed by the real-time measurement of electrical resistance across cell monolayers derived from bovine pulmonary arteries and microvessels. Using a desensitization protocol with cAMP/protein kinase A (PKA)-enhancing agents and pharmacological inhibitors, we determined that the activity of PCM is independent of PKA and PKG. Genistein, an inhibitor of tyrosine kinases, prevented the increase in endothelial electrical resistance. Because lysophosphatidic acid (LPA) has been proposed to be responsible for this activity of PCM and is known to activate the G(i) protein, inhibitors of the G protein pertussis toxin and of the associated phosphatidylinositol 3-kinase (PI3K) wortmannin were used. Pertussis toxin and wortmannin caused a 10- to 15-min delay in the characteristic rise in electrical resistance induced by PCM. Inhibition of phosphorylation of extracellular signal-regulated kinase with the mitogen-activated kinase kinase inhibitors PD-98059 and U-0126 did not prevent the activity of PCM. Similar findings with regard to the cAMP protocols and inhibition of G(i) and PI3K were obtained for 1-oleoyl-LPA. These results demonstrate that PCM increases endothelial electrical resistance in vitro via a novel, signal transduction pathway independent of cAMP/PKA and cGMP/PKG. Furthermore, PCM rapidly activates a signaling pathway involving tyrosine phosphorylation, the G(i) protein, and PI3K.

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Introduction: There is paucity of literature evaluating anterior acetabular retractor proximity to the femoral nerve and external iliac vessels during total hip arthroplasty through the direct anterior approach. In this cadaveric study, we evaluated three retractor locations to identify optimal positioning of anterior retractors. Methods: A direct anterior approach was performed in 22 hips of 15 cadavers. Anterior acetabular retractors were placed over the anterior acetabular wall in-line with the femoral neck (12-o'clock or middle position). The anterior neurovascular structures were identified through the ilioinguinal approach. Retractors were reinserted at 10-o'clock (right hip; superior) and 2-o'clock (right hip; inferior) locations marked using K-wires. Horizontal and vertical distances from retractor tip positions to neurovascular structures were measured with a digital caliper. Results: Retractor tips moved significantly from lateral to the femoral nerve when placed in the superior position (mean, 2.8 mm) to medial to the femoral nerve in the middle (mean, −2.3 mm) and inferior (mean, −4.8 mm) locations. Retractor tips moved significantly medial toward the external iliac artery when retractors were moved from superior (mean, 15.3 mm) to inferior (mean, 6.6 mm) positions placing the retractor tip closer to the vessels. Conclusion: As retractor placements moved inferior, retractor tips moved medial to neurovascular structures. Inferior retractor positioning placed the femoral nerve and external iliac artery at the risk of injury during the initial retractor placement or adjustment. Retractors should be placed in a relative safe zone superior to the 12-o'clock position to avoid damage to neurovascular structures. Level of Evidence: IV

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Abstract:Total knee arthroplasty is a common orthopaedic procedure conducted in the United States with approximately 700,000 surgeries performed annually. A common complication following total knee arthroplasty is anterior knee pain which affects tens to hundreds of thousands of people each year. The exact mechanism that leads to anterior knee pain remains unknown, but improper component selection may cause pathologic loading of the knee which leads to pain. Measuring loads in the knee to elucidate the mechanisms underlying anterior knee pain remains a challenge because the joints are so small. Using novel wireless sensor technology, we have developed and validated the first "smart" patellar implant capable of measuring force magnitude and force distribution in the knee. Implantable force sensors were calibrated and tested through the range of physiologic loading. Three sensors were then interfaced with a Zimmer patellar implant and placed into a custom loading apparatus. The smart patellar implant was then incrementally loaded from 0-500 N. Sensor signals were all recorded simultaneously in real time to measure the load across the patellofemoral joint. Results demonstrated that the smart patellar implant was able to accurately measure the load being transmitted across the simulated patellofemoral joint.

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