New Failure Mechanism of Acetabular Constrained Liner: A Case Report.

Implant dislocation following total hip arthroplasty, particularly revision arthroplasty, remains a common postoperative complication. Constrained acetabular liners provide surgeons with an implant option that provides resistance to dislocation forces. These added forces, however, are transmitted to the implant materials and to the bone\endash implant interface, resulting in unique failure mechanisms. This case report presents two cases highlighting a previously unreported mechanism of failure of the Depuy Pinnacle ES constrained liner encountered during intraoperative implantation of the components (Journal of Surgical Orthopaedic Advances 28(1):68-73, 2019).

Treatment of primary hip osteoarthritis for the primary care physician and the indications for total hip arthroplasty.

Osteoarthritis is a degenerative condition that commonly affects knees and hips with an annual incidence of 88 in 100,000 people in the United States. The purpose of this study was to review the clinical presentation of osteoarthritis of the hip as well as the available management options. We reviewed the recent literature in regard to epidemiology, presentation, and treatment options available to patients. Nonoperative treatments include weight loss and low-impact, aerobic exercises. Along with weight loss and exercise, nonsteroidal anti-inflammatory drugs (NSAIDS), narcotics, and intra-articular steroid injections have been used to improve patient's symptoms. Surgical intervention is a viable option; however, indications such as severe pain that is refractory to nonsurgical management, osteophytes, or joint space narrowing on radiographic films, or impairment of function should be present. The most common surgical option, total hip arthroplasty, has been shown to improve a patient's physical and psychological well-being. However, inherent risks are present with surgery and these should be addressed with the patient so a sound decision can be made. Osteoarthritis of the hip can be bothersome to patients, but physicians can begin management with lifestyle changes or pharmaceuticals. In the event nonoperative measures fail to markedly improve quality of life, total hip arthroplasty remains a viable option.

Total knee arthroplasty in a patient with skeletal fluorosis.

Published reports on patients with skeletal fluorosis undergoing total knee arthroplasty are rare. Skeletal fluorosis is a chronic condition that occurs secondary to the ingestion of food and water that contain high levels of fluoride. Although fluorosis may be described as osteosclerotic and marble-like in appearance, features may also include characteristics of osteomalacia and osteoporosis. This article describes the case of a 67-year-old man with skeletal fluorosis who underwent total knee arthroplasty complicated by fracture. An intramedullary guide was used for the proximal tibia and distal femoral bone cuts intraoperatively. Following the completion of the femoral bone cuts, it was noted that the drill used to open the femoral canal had breached the medial femoral cortex. Multiple fractures were seen in both femoral condyles. A revision femoral stem was chosen to complete the total knee arthroplasty but, after further manipulation of the femur, it appeared that the fracture had displaced. A LISS plate (Synthes, West Chester, Pennsylvania) was used to ensure fracture reduction and implant stability. The remainder of the procedure was completed without complication. One year postoperatively, functional knee range of motion was limited to 70° of flexion. Radiographs showed signs of healing and satisfactory implant position. This case highlights the importance of the preoperative examination and the need to fully appreciate the bone quality of patients prior to undertaking an orthopedic procedure. Variation from the use of intramedullary guides should be considered in patients with questionable bone quality undergoing total knee arthroplasty.

HEMODYNAMICS OF LEFT VENTRICULAR APEX-AORTIC VALVED CONDUITS.

A flow model for analyzing the fluid mechanics of left ventricular-aortic valved conduits has been established. The model is based on a parallel flow circuit analogy of Ohm's law, the classic analysis of Gorlin and Gorlin(1) for the determination of valvular areas, and an empirical constant, introduced by Gentle,(2) that is descriptive of prosthetic heart valve performance. Favorable comparisons with clinical data indicate that the flow model is capable of predicting volumetric rates of flow through the valved conduit and through the aorta. Applications of the model are discussed in terms of altering the design of the valved conduit to improve its performance. The effect of valvular efficiency on conduit performance is investigated, and it is concluded that the Starr-Edwards ball valve and the Hancock 250 valve offer attractive alternatives if the objective is to increase the volumetric rate of flow through the valved conduit, or to decrease the volumetric rate of flow through the stenotic aortic valve, or both.