Faculty Bibliography

Uncemented, porous-coated femoral stems rely on bone in-growth to achieve stable, long-lasting fixation. The loss of proximal femoral bone mass around hip stems has been traditionally termed 'stress shielding' and has been linked to the transfer of loads to the diaphysis and the relative unloading of the proximal femur. A total of 10 total hip arthroplasties with a proximally coated lateral flare device designed to engage both cortices at the metaphyseal level were evaluated with dual-energy X-ray (DEXA) absorptiometry and qualitative radiographic changes 3 weeks after surgery and at 12, 24 and 52 weeks thereafter. All hips were radiologically stable. The DEXA measurements revealed an overall increase in the bone mineral density (BMD) at 52 weeks of 3%. Greater gains were observed at or below the lateral flare of the stem in the metaphyseal femur

OBJECTIVE: Venous thromboembolism after total-knee arthroplasty represents a common early postoperative complication resulting in significant morbidity. Despite this, the optimal prophylactic regimen is controversial. The prevalence of venous thromboembolism has been cited as high as 35% in patients receiving pharmacologic prevention alone. We investigated the efficacy of a comprehensive prevention protocol encompassing the use of epidural anesthesia, aspirin, venous foot compression pumps, and early mobilization in a series of consecutive total-knee arthroplasties. DESIGN: A series of 100 consecutive total-knee arthroplasty patients were enrolled into the prospective trial. All patients were allowed full weight bearing on the first postoperative day and ambulation as tolerated. Venous foot compression pumps and aspirin were used immediately after surgery in the totality of subjects. Seventy-five percent of the patients were transferred to an acute rehabilitation service during the first postoperative week. The presence of deep-vein thrombosis was subsequently determined with the routine use of venous duplex scans. RESULTS: Three patients (3%) demonstrated evidence of distal deep-vein thrombosis. No patient had symptomatic pulmonary embolism. CONCLUSION: The combination of epidural anesthesia, aspirin, immediate postoperative venous foot compression pumps, and early ambulation together seem to be a more effective approach to prevent the occurrence of thromboembolic events after knee replacements than pharmacologic prevention alone

Thromboembolism following total hip arthroplasty is a common complication that may result in significant morbidity and mortality. Despite this, optimal prophylactic regimen is controversial. We investigated the efficacy of a comprehensive approach encompassing the use of aspirin, intermittent compression devices ('foot pumps'), and early mobilization in a cohort of 200 consecutive patients after non-cemented total hip replacements. The surgical procedures were carried out under epidural anesthesia in most cases (91%). All patients were allowed full weight bearing and received ambulation training starting on the first post-operative day. Ankle-high pneumatic boots ('foot pumps') and aspirin (325 mg p.o./qd) were used immediately after surgery. The presence of deep vein thrombosis was determined with the routine use of venous duplex scans on post-operative day number 5 to 10 (mean 6.8). The duration of the follow-up was 3 months. No patients were lost to follow-up. Four distal DVT's (2%) were detected in three patients. None of the patients developed symptomatic pulmonary embolism during the follow-up period. There were no major wound complications. Venous thromboembolic disease after hip replacement surgery is largely associated with postoperative immobilization and venous stasis. It is the authors' opinion that a prevention strategy should include mechanical as well as pharmacological measures. The concomitant use of epidural anesthesia, 'foot pumps', aspirin and early full weight bearing ambulation may be effective in further reducing the incidence of DVT after surgery

Over the past several decades numerous researchers have revisited the model of the biomechanics of the hip first predicated by John Koch in 1917. The contributions of Blount (1956), Frankel (1960), Pauwels (1976), Toridis (1969), Rybicki (1972), Fetto (1994, 1995), Ling (1996), and Lu (1997, 1998) among others created a more complete picture. The present article briefly reviews the previous biomechanical concept and its clinical inconsistencies and offers a model that includes the dynamic and static input of the soft tissues. The action of the iliotibial band (ITB) and the vastus lateralis-gluteus medius complex (as static and dynamic tension bands lateral to the femur) counterbalance the varus bending torque of the loads acting on the hip, transforming the tensile stresses in the lateral femur (as hypothesized by Koch) into compressive stresses. The inclusion of the soft tissues, extending the previous model, widens our understanding of the forces acting on the hip. Thus, a variety of clinical observations can be better explained in a comprehensive theoretical framework

We reviewed the X-rays of 109 patients with 115 primary total hip replacements utilizing a lateral flare cementless stem to assess axial migration and stability. The average follow-up was 48.6 (24-104) months. The average subsidence at 2 years was 0.32 mm, remaining at a level below 1 mm for the duration of the follow-up. Even though there were ten reoperations involving either the change of a polyethylene liner and the acetabular component, or both, none of the patients required a femoral stem revision. It was concluded that the proximal geometry of the stem provides significant initial stability, which seems to be preserved throughout a long follow-up period

Avascular necrosis of the hip is a common disease that usually affects a young and active patient population. As the disease progresses, the undermined structural integrity of the subchondral bone leads to articular collapse and subsequent osteoarthrosis. The ideal treatment is one that hinders or arrests the progression of the disease, averting articular collapse and joint replacement surgery. A surgical strategy is described that attempts to address the multiple factors involved in the progression of the disease. This is accomplished through a modified core decompression procedure combined with the insertion of two interference screws into the subchondral plate to provide structural support and the use of osteoinductive material (i.e., demineralized bone matrix) in an effort to accelerate the bone healing process