Joseph Fetto

Heterotopic ossification. Incidence and relation to trochanteric osteotomy in 100 total hip arthroplasties.

Heterotopic ossification can impair the functional results of total hip arthroplasty. The causative role of trochanteric osteotomy in heterotopic ossification is uncertain. Postoperative radiographs of 100 total hip arthroplasties were analyzed for incidence of heterotopic ossification. Forty procedures were performed with trochanteric osteotomy and 60 without. There was a 17% overall incidence of clinically significant heterotopic ossification, 22% with osteotomy and 13% without. High- and low-risk categories revealed clinically significant heterotopic ossification in 25% of the high-risk group and in 8% of the low-risk group. In the high-risk group there was a 32% incidence with trochanteric osteotomy and 22% without osteotomy. In the low-risk group there was a 16% incidence without trochanteric osteotomy and a 3% incidence with trochanteric osteotomy. The increase in clinically significant heterotopic ossification in the high-risk group over that of the low-risk group was statistically significant. The present study showed that trochanteric osteotomy tended to increase the incidence and severity of clinically significant heterotopic ossification. These data suggest that trochanteric osteotomy should be avoided, if possible, during total hip arthroplasty to decrease the risk of heterotopic ossification.

Preservation of femoral bone mass after total hip replacements with a lateral flare stem.

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.RésuméLes tiges fémorales poreuses recouvertes comptent sur la réhabitation osseuse pour obtenir une fixation stable et durable. La perte osseuse fémorale proximale autour des tiges a été appelée traditionnellement détournement de contrainte et été lié au transfert de charges du fémur proximal vers la diaphyse. Dix arthroplasties totales avec une tige comportant un évasement latéral proximal pour mettre en jeu les deux corticales au niveau métaphysaire ont été évaluées avec une absorptiomčtrie biphotonique et les changements radiographiques qualitatifs à 3, 12, 24 et 52 semaines aprčs la chirurgie. Toutes les hanches étaient stables radiographiquement. Les examens d’absorptiomčtrie ont révélé une augmentation totale de la DMO à 52 semaines de 3%. Les plus grands gains ont été observés au niveau oů en dessous de l’évasement latéral de la tige dans le fémur métaphysaire.

Comprehensive deep venous thrombosis prevention strategy after total-knee arthroplasty.

Ragucci MV, Leali A, Moroz A, Fetto J: Comprehensive deep venous thrombosis prevention strategy after total-knee arthroplasty. Am J Phys Med Rehabil 2003;82:164–168. 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.

Evaluation of femoral strains with cementless proximal-fill femoral implants of varied stem length

BACKGROUND The design intent of proximally-filling lateral flare femoral stems is to load the endosteal surface of the proximal femur both laterally and medially, to achieve normal bone strains. However, the long stem can contact the femoral cortex and may offload the proximal region to some extent. Therefore, in this study, we sought to determine if reducing the stem length, would result in physiologic strain patterns. METHODS Using the PhotoStress® method we analyzed 13 femurs intact and with three different stem length implants: stemless, ultra-short and short. The test rig loaded the femoral head by simulating the mid-stance single leg support phase of gait with the ilio-tibial band and the hip abductor forces. The strain distribution with each stem length implant was then compared to the intact strain distribution to determine which was most similar. FINDINGS As the stem length increased the femurs exhibited a typical pattern of reduced proximal strain and increased distal strain. However, there was some variation in this pattern indicating that the exact stem position and the location of its interaction with the endosteal surface of bone was not the same in each femur. INTERPRETATION The stemless design provided the best match compared to the native femur and therefore has the greatest potential to address the shortcomings of a stemmed femoral implant. However, the ultra-short implant also exhibited a strain distribution that closely emulated the intact femur, and may represent the best option as there are still several questions pertaining to stability and alignment of a stemless implant.

Favorable midterm results of total hip arthroplasties with a lateral flare uncemented stem.

Uncemented stems have been advocated for primary total hip arthroplasties in the young active population. We evaluated the clinical and radiographic results of total hip arthroplasties with a customized lateral flare cementless femoral stem in a prospective, consecutive series of 35 patients (40 hips) younger than 55 years at the time of surgery and who were followed up for an average of 9.2 years (range, 5.7-12.2 years). The study group comprised 20 men and 15 women with an average age of 45.2 years (range, 30-55 years). One patient had aseptic loosening of the stem and one patient had a deep infection. The mean preoperative Harris hip score was 47 and at the latest followup it was 97. The mean axial migration was 0.51 mm. Femoral osteolysis was found to be circumscribed to the proximal femur in Gruen Zones 1 (15%) and 7 (8%) in patients with accelerated polyethylene wear. Radiographic changes consistent with new bone apposition under the lateral flare of the stem in Zones 2, 6, and 7 were found in 73% of the cases. Our data suggest a custom lateral flare stem for primary arthroplasties in the younger patient population achieves excellent clinical results with a low rate of aseptic loosening.Level of Evidence: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Stress Evaluation of a Short, Medium and Long Stem Proximal Fill Femoral Implants

The femoral stem of a traditional total hip arthroplasty is believed to be essential for fixation and stability. Stems achieve early stability in a non-physiological fashion by a combination of friction and circumferential displacement of bone, similar to that of a nail being impacted into a piece of wood. In contrast, the “Revelation” femoral prosthesis, produced by DJO Surgical Corporation, relies upon a proximal lateral expansion (“Lateral Flare” design concept) to achieve stability.Copyright

Poster 71: Preventing venous thromboembolism after total joint replacement. A multifactorial approach1

Abstract Objective: To investigate the efficacy of a comprehensive protocol encompassing hypotensive epidural anesthesia, aspirin, intermittent compression devices, along with early mobilization and postoperative exercises in patients after noncemented total hip (THR) and knee (TKR) replacements. Design: Prospective observational 2-group study. Setting: University hospital. Participants: 360 consecutive patients after noncemented THR and TKR. Interventions: All patients were allowed full weight bearing on the first postoperative day. Ankle-high pneumatic boots (foot pumps) were used early after surgery. Aspirin (325mg/d every day) was given to all patients as a pharmacologic measure to prevent thromboembolic events. Most patients were transferred to an acute rehabilitation center and received physical therapy sessions on postoperative day 1. Main Outcome Measures: The presence of deep vein thrombosis (DVT) was determined with the use of venous duplex scans on a regular basis from postoperative day 5 to day 10 (mean, 6.8). The duration of follow-up was 3 months. No patients were lost to follow-up. Results: 6 patients (3%) developed DVT in the THR group and 4 patients (2.4%) in the TKR group. None of the patients developed symptomatic pulmonary embolism during the follow-up period. Conclusion: The use of epidural anesthesia, foot pumps, early full weight-bearing ambulation, aspirin, and systematic duplex ultrasonography surveillance constitutes an effective combination to prevent DVT (2%–3%) after total joint replacements.