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1/ 13: Arthritis
Rheum 2002 Sep;46(9):2436-44 OBJECTIVE: Mortality and complication rates after total hip replacement (THR) are inversely associated with the volume of THRs performed at hospitals and by individual surgeons. It is not clear, however, why a higher volume of such procedures is associated with better outcomes. We evaluated the contribution of hospital structural characteristics to the volume-outcome relationship in THR by examining the rates and predictors of postoperative complications. METHODS: We analyzed data pertaining to 5,211 Medicare patients who underwent primary THR in 1995 or 1996 at 167 hospitals in Colorado, Pennsylvania, and Ohio. Data were derived from several sources, including Medicare Part A and Part B claims, the American Board of Medical Specialties, a hospital survey regarding institution-specific characteristics and structural aspects of the care setting, and the American Hospital Association 1995 Annual Survey. Multivariate models were constructed to determine whether hospital structure or surgeon-associated factors may underlie the relationship between volume of THRs and the occurrence of perioperative orthopedic adverse events, defined as deep wound infection or hip dislocation within 90 days of surgery. RESULTS: Of the patients studied, 2.6% experienced an orthopedic adverse event after THR. Sixty-nine percent fewer events occurred in hospitals where >100 THRs in Medicare patients were performed annually, compared with hospitals where </=25 THRs were performed. In univariate analyses, several hospital-level factors were associated with a reduced (approximately 50%) risk of adverse events, including private (versus public) ownership, membership in the Council of Teaching Hospitals, presence of any residency training program, availability of a dedicated orthopedic nursing unit, and existence of operating rooms with laminar flow exhaust systems. However, the only hospital-level factor associated with adverse events in multivariate models was the use of laminar flow exhaust systems. When surgeon volume was added to the models, it was the strongest predictor of adverse events, with hospital volume and hospital-level factors having no appreciable association with adverse events. CONCLUSION: Hospital-level factors were not independent predictors of the association between hospital volume and orthopedic adverse events. The volume of THRs performed by individual surgeons is the most important determinant of orthopedic complications and should be considered in efforts to improve THR outcomes. 2/ 14: Arthritis
Rheum 2002 Sep;46(9):2429-35 OBJECTIVE: Joint replacement therapy is an effective treatment option for end-stage osteoarthritis (OA) of the knee and/or hip. There are marked racial/ethnic disparities in the utilization of this procedure. The reasons for these disparities are not known. We sought to determine whether African American patients differ from white patients in their "willingness" to consider joint replacement and to determine the factors that influence this relationship. METHODS: We performed a cross-sectional survey of 596 elderly, male, African American or white patients with moderate-to-severe symptomatic knee or hip OA who were receiving primary care at the Department of Veterans Affairs outpatient clinics. RESULTS: The groups were similar with respect to age, severity of arthritis measured by the Lequesne Scale and the Western Ontario and McMaster Universities Osteoarthritis Index, and scores on the Charlson Comorbidity Index and Geriatric Depression Scale. Compared with whites, African Americans were less likely to be employed or married or to have attained a high school education, but were more likely to report a median annual household income of <$10,000. They were also less likely than whites to be familiar with joint replacement and more likely to expect a longer duration of hospital course, pain, and functional disability following replacement surgery. African American patients were less "willing" than white patients to consider joint replacement (odds ratio 0.50, 95% confidence interval 0.30-0.84). However, this difference was explained by the between-group differences in expectations. CONCLUSION: African American patients were less likely than white patients to express "willingness" to consider joint replacement if the procedure was needed and recommended. This difference was explained by differences between the groups in their expectations of hospital course, pain, and function following replacement surgery. 3/ 15: Radiology
2002 Oct;225(1):225-31 PURPOSE: To correlate power Doppler ultrasonographic (US) findings of the vascularity of synovial tissue of the hip joint with the results of histopathologic examination of the same tissue to assess the value of power Doppler US in the visualization of synovitis. MATERIALS AND METHODS: The hip joints of 24 patients with osteoarthritis (n = 15) or rheumatoid arthritis (n = 9) of the hip joint were examined with US before arthroplasty. The vascularity of the synovial membrane was classified qualitatively by using power Doppler US. During surgery, a section of the synovial tissue examined at power Doppler US preoperatively was resected. The vascularity of the tissue specimen was investigated and graded qualitatively by a pathologist who was not aware of the US findings. Visual qualitative grading was controlled by means of analysis of the US images and histopathologic specimens with a digital image evaluation system. Correlations between power Doppler US and histopathologic examination findings were calculated by using Spearman rank correlation and Pearson correlation tests. RESULTS: The correlation between the qualitative power Doppler US results and the qualitative vascularity grades was 0.92 (P <.01, Spearman rho). The correlation between quantitative and qualitative results was 0.93 (P <.01, Spearman rho) for US imaging and 0.97 (P <.01, Spearman rho) for histopathologic examination. CONCLUSION: Study results showed power Doppler US to be reliable for qualitative grading of the vascularity of synovial tissue of the hip. Copyright RSNA, 2002. 4/17:
J Orthop Trauma 2002 Sep;16(8):535-42 OBJECTIVE Analyze the prevalence and severity of surgical complications encountered with a modified extended iliofemoral approach, the "T extensile" approach, in the treatment of complex acetabular fracturesSTUDY DESIGN Prospective. METHODS During a sixteen-month study period, forty-three
patients with complex acetabular fractures were treated via the
T extensile approach. Perioperative antibiotics were used to prevent
infection, and prophylaxis for heterotopic ossification was done
with postoperative irradiation. Complications and clinical results
were recorded. RESULTS Acceptable reductions were obtained in forty patients. Poor reductions were obtained in three patients. There were no infections or iatrogenic nerve injuries. Brooker Grade 1 heterotopic ossification was seen in nineteen patients, eight had Grade 2, two had Grade 3, and no heterotopic ossification was seen in the other fourteen patients. No patient who received radiation developed heterotopic ossification beyond Brooker Grade 2. Seven patients went on to require total hip arthroplasty. The remaining thirty-six patients had an average Harris Hip Score of 86 CONCLUSIONS: Extensile exposures to the acetabulum can be safely carried out with limited morbidity, as long as appropriate steps are taken to limit predictable complications. 5/ 18:
Am J Orthop 2002 Sep;31(9 Suppl):4-11 Although deep vein thrombosis has consistently been a serious postsurgical complication of total hip arthroplasty, the risk of thromboembolic disease has declined substantially in the past 3 decades. From the late 1980s through the early 1990s, the reported rate of nonfatal pulmonary embolism following total hip arthroplasty ranged from 1.0% to 1.2%, and the rate of fatal pulmonary embolism was 0.4% or lower. Even lower rates have been observed more recently. The decreasing risk of postsurgical complications reflects considerable advances in our understanding of the pathophysiology of deep vein thrombosis related to total hip arthroplasty and improvements in regional anesthesia, surgical technique, and perioperative prophylaxis. Among the factors that reduce the risk of thromboembolism discussed in this article are: preoperative autologous blood donation; hypotensive epidural anesthesia with epinephrine infusion; administration of unfractionated heparin during surgery, before femoral preparation, when the thrombogenesis is maximally stimulated; expeditious surgery, minimizing femoral vein occlusion and blood loss; pneumatic compression and patient mobilization with foot exercises immediately after surgery; and early ambulation.
6/ 28:
Acta Biomed Ateneo Parmense 2001;72(5-6):97-103 From 1999, at the Orthopaedic Clinic of the University of Siena, 56 patients were treated with the compression hip nail-plate system, a new synthesis device for the treatment of peritrochanteric fractures. The system consists in a new dynamic cephalic screw that could be combined with a plate or a femoral nail. The dynamic cephalic screw of the BCM system has a limited sliding method, impeding excursion greater than 10 mm and preventing excessive collapse of the fracture fragments that can evolve into a shortening of the limb. The canulated nail has a diameter of only 9 mm, which permits insertion into the shaft canal without reaming. The possibility of the double combination of the screw with a plate or with an intramedullary nail permits the surgeon to have a double solution with a single instrument at hand, and offers the opportunity of changing the choice of synthesis method to implant even during surgery.
7/ 33:
Med Biol Eng Comput 2002 Jul;40(4):369-75 A mathematical model was developed to study the effect of the Chiari osteotomy on the distribution of contact hip stress over the weight-bearing area. It was shown that Chiari osteotomy can increase the weight-bearing area directly (on the lateral side), owing to the additional area formed by the ala ossis ilii segment, and indirectly (on the medial side), owing to the shift of the stress pole in the medial direction. As a consequence, the contact hip stress is reduced after Chiari osteotomy. The indirect effect is important and often larger than the direct one. Using the proposed mathematical model and standard anteroposterior roentgenographs from archives, the average peak stress on the weight-bearing area, normalised with respect to the body weight (pmax/ W(B)), was determined before and after Chiari osteotomy (8,310m(-2) and 4,480 m(-2), respectively) on a population of 29 dysplastic hips. The difference was statistically significant (p < 0.005). Based on the results presented, it can be concluded that the hip joint contact stress in dysplastic hips considerably decreases after Chiari osteotomy, indicating a favourable biomechanical effect of this operation.
8/
4: Clin Orthop 2002 Oct;403:16-22 A previously reported staging system for prosthetic joint infection was evaluated in 26 consecutive patients with an infected hip arthroplasty. Six patients were treated by a definitive resection arthroplasty whereas the remaining 20 patients received delayed insertion of another hip arthroplasty. Four of the 20 patients (20%) receiving a new prosthesis had reinfection develop. The only variable in common among the patients who had reinfection was the use of a massive femoral structural allograft at reconstruction. Because of the small number of patients in this study, the power of statistical analysis did not allow definitive determination of the effect of the staging system score with respect to recurrent infection. Based on this study, recommendations can be suggested for addition and deletion of certain variables within the existing staging system. Although the concept of a staging system for treatment of an infected hip arthroplasty is promising, the number of patients required to evaluate the use of a staging system will require a multicenter collaborative study.
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Acta Orthop Scand 2002 Aug;73(4):416-24 In a rabbit model of a weight bearing, articulating prosthetic joint we repeatedly injected submicron particles of Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) produced in a hip simulator. The contralateral knee with the same prosthesis was injected with carrier (NaCl) without UHMWPE. Histomorphometrical studies on undecalcified cut and ground sections at 26 and 42 weeks involved quantifications of the entire bone to metal contact and the bone area around each implant. We found no statistically significant differences between test and control groups, and the UHMWPE debris did not induce any significant osteolysis, indicating that an osseointegrated implant with a sealed interface may not be affected by UHMWPE debris or progress to aseptic loosening.
10/ 8:
Acta Orthop Scand 2002 Aug;73(4):392-9 Patients in the Norwegian Arthroplasty Register with a total hip replacement (THR) have a lower long-term mortality than the age- and gender-matched Norwegian population. We analyzed the early postoperative mortality after 67,548 THR operations in 68 hospitals reported to the Norwegian Arthroplasty Register between 1987 and 1999. Data on deaths and causes of death were obtained from Statistics Norway, and on thromboprophylaxis from a separate questionnaire sent to all hospitals. During the years 1987-2000 the 68 hospitals reported use of 6 thromboprophylaxis drugs and 24 different combinations of drugs and stockings. In 1988, only 3 of 29 hospitals reported use of low molecular weight heparin (LMWH), but in 1999, 67 of the 68 hospitals used LMWH. In the first postoperative week, the daily mortality was about 2.5 deaths per 10,000 THR patients. By the 70th postoperative day, the daily mortality had declined to about 0.57 deaths per 10,000 patients. The daily mortality of the age- and gender-matched Norwegian population was 0.95 deaths per 10,000 individuals. Early postoperative mortality increased with age, was higher in men than women, and was usually due to vascular disease. We found only a slight reduction in the 60-day postoperative mortality during the period 1987-1999. All underlying diagnoses for a prosthesis operation had a higher 60-day postoperative mortality than primary osteoarthrosis.
11/ Preliminary
experience with a new osteosynthesis device for intertrochanteric
fractures. From 1999, at the Orthopaedic Clinic of the University of Siena, 56 patients were treated with the compression hip nail-plate system, a new synthesis device for the treatment of peritrochanteric fractures. The system consists in a new dynamic cephalic screw that could be combined with a plate or a femoral nail. The dynamic cephalic screw of the BCM system has a limited sliding method, impeding excursion greater than 10 mm and preventing excessive collapse of the fracture fragments that can evolve into a shortening of the limb. The canulated nail has a diameter of only 9 mm, which permits insertion into the shaft canal without reaming. The possibility of the double combination of the screw with a plate or with an intramedullary nail permits the surgeon to have a double solution with a single instrument at hand, and offers the opportunity of changing the choice of synthesis method to implant even during surgery.
12/ 19:
Z Orthop Ihre Grenzgeb 2002 Sep-Oct;140(5):527-32
AIM: Dysplastic hips or dislocated hips lead to loss of muscle strength claudication, and finally to coxarthrosis. This study analytically compares the hip joint forces in normal, dysplastic hips and hips after implantation of a hip prosthesis for several positions. METHOD: The results of 173 total hip replacements in 153 cases of either severe congenital dysplasia or dislocation were analyzed. A 2 dimensional mathematical model of the hip was developed to evaluate the effects of surgically achievable mechanical alterations such as acetabular placement, femoral shaft-prosthetic neck angle, and neck length of the femoral prosthesis. RESULTS: 63 % of the hip prosthesis were implanted on the right, 72 % on theleft. Before implantation, the femoral shaft-prosthetic
neck angle in mean was 146 degrees +/- 10 degrees, after implantation
it was 135 degrees. The hip centre was displaced onin average 10
mm distally. Postoperatively hip joint force was increased 21 %.
CONCLUSION: Minimum joint contact forces occurred when the femoral
shaftprosthetic neck angles were small. The loads on the hip were
lowered significantly by placing the centre of the acetabulum as
far inferiorly and medially as possible. Another important finding
is that displacement of the hip centre distally has a great effect
on muscle performance and hip joint force.
13/
23: Proc Inst Mech Eng [H] 2002;216(4):237-45 A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated.
The highest cancellous bone strain levels were found at mid-stance,
not heel-strike. Remote from the acetabulum there was little effect
of prosthesis material and fixation upon the von Mises stresses
and maximum principal strains. Implant material appeared to have
little effect upon cancellous bone strain failure with both bended
and unbonded bone-implant interfaces. The unbonded implants increased
stresses in the subchondral bone at the centre of the acetabulum
and increased cancellous bone loading, resembling behaviour obtained
previously for the intact acetabulum.
14/
6: Arthritis Rheum 2002 Sep;46(9):2436-44 OBJECTIVE: Mortality and complication rates after total hip replacement (THR) are inversely associated with the volume of THRs performed at hospitals and by individual surgeons. It is not clear, however, why a higher volume of such procedures is associated with better outcomes. We evaluated the contribution of hospital structural characteristics to the volume-outcome relationship in THR by examining the rates and predictors of postoperative complications. METHODS: We analyzed data pertaining to 5,211 Medicare patients who underwent primary THR in 1995 or 1996 at 167 hospitals in Colorado, Pennsylvania, and Ohio. Data were derived from several sources, including Medicare Part A and Part B claims, the American Board of Medical Specialties, a hospital survey regarding institution-specific characteristics and structural aspects of the care setting, and the American Hospital Association 1995 Annual Survey. Multivariate models were constructed to determine whether hospital structure or surgeon-associated factors may underlie the relationship between volume of THRs and the occurrence of perioperative orthopedic adverse events, defined as deep wound infection or hip dislocation within 90 days of surgery. RESULTS: Of the patients studied, 2.6% experienced an orthopedic adverse event after THR. Sixty-nine percent fewer events occurred in hospitals where >100 THRs in Medicare patients were performed annually, compared with hospitals where </=25 THRs were performed. In univariate analyses, several hospital-level factors were associated with a reduced ( approximately 50%) risk of adverse events, including private (versus public) ownership, membership in the Council of Teaching Hospitals, presence of any residency training program, availability of a dedicated orthopedic nursing unit, and existence of operating rooms with laminar flow exhaust systems. However, the only hospital-level factor associated with adverse events in multivariate models was the use of laminar flow exhaust systems. When surgeon volume was added to the models, it was the strongest predictor of adverse events, with hospital volume and hospital-level factors having no appreciable association with adverse events. CONCLUSION: Hospital-level factors were not independent predictors of the association between hospital volume and orthopedic adverse events. The volume of THRs performed by individual surgeons is the most important determinant of orthopedic complications and should be considered in efforts to improve THR outcomes.
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