Faculty Bibliography

Periprosthetic osteolysis poses a significant clinical problem for patients who have undergone total joint arthroplastic surgeries. It has been widely recognized that there is a strong correlation between wear particles from orthopedic implants and osteolysis. However, the molecular mechanism underlying osteolysis still remains unclear. Although wear particles interact with a mixed cellular environment, namely macrophages and immune cells, osteoblasts compose the majority of the cell population surrounding orthopedic implants. Osteoblasts are also one of the major sources of receptor activator of nuclear factor-kappa beta (NF-kappaB) ligand (RANKL), a factor necessary for osteoclastogenesis. However, macrophage colony-stimulating factor (M-CSF), another cytokine responsible for preosteoclast proliferation, must also be present with RANKL for osteoclastogenesis to occur. The purpose of our study is to determine the signal transduction pathway by which titanium (Ti) particles, a metallic component of many orthopedic implants, induce M-CSF expression in MC3T3.E1 murine calvarial preosteoblastic cells. Using reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme- linked immunosorbent assay (ELISA), our study demonstrated that submicron-sized Ti particles induce M-CSF expression via the extracellular signal-regulated kinase (ERK) pathway in a dose-dependent manner. Moreover, inhibition studies showed that a specific ERK inhibitor, PD98059, significantly downregulated M-CSF production. Our results support the hypothesis that submicron-sized Ti particles can induce M-CSF expression in osteoblasts and thus may have a significant role in contributing to the onset of periprosthetic osteolysis.

BACKGROUND: There is currently no standardized protocol for evaluating and treating osteonecrosis of the femoral head in adults in the United States. We sought to understand current treatment practices of a group of surgeons who commonly treat this disease to determine if there was agreement on some aspects of care. METHODS: We designed a two-staged mixed-mode (mailed and faxed) sixteen-question self-administered descriptive survey questionnaire to be sent to all 753 active members of the American Association of Hip and Knee Surgeons (AAHKS). The survey design was based on Dillman's survey research methodology, and the questionnaire included hypothetical clinical scenarios based on the Steinberg classification system. The responses elucidated the opinions and treatment preferences of high-volume arthroplasty surgeons who treat adult patients with osteonecrosis of the femoral head. RESULTS: Of the 753 active members of the AAHKS, 403 (54%) responded to the questionnaire. Total hip replacement was reported to be the most frequent intervention for treatment of postcollapse (Steinberg stage-IIIB, IVB, V, and VI) osteonecrosis; core decompression was reported to be the most commonly offered intervention for symptomatic, precollapse (Steinberg stage-IB and IIB) osteonecrosis. Less frequently offered treatments included nonoperative management, osteotomy, vascularized and non-vascularized bone-grafting, hemiarthroplasty, and arthrodesis. CONCLUSIONS: The care of adults with osteonecrosis of the femoral head varies among American orthopaedic surgeons specializing in hip and knee surgery. A consensus may evolve with a continued concerted effort on the part of interested surgeons, but it will require randomized, controlled, prospective studies of treatment of each stage of the disease and collaborative multicenter studies. LEVEL OF EVIDENCE: Therapeutic Level V.

A web-based survey was developed to evaluate joint arthroplasty surgeon's preferences for the return to sporting activities after total hip arthroplasty. This survey listed 30 groups of activities (37 specific sports) and was sent to all members of the Hip Society and American Association of Hip and Knee Surgeons. All surgeons were asked to grade each activity as follows: allow, allow with experience, not allowed, or undecided. Results were computed using a power analysis, Z test, and chi(2) test to determine statistical significance. There were a total of 549 responses giving an overall response rate of 72%, with 93% (92/99) of the Hip Society members and 72% (522/727) of American Association of Hip and Knee Surgeons members responding to the survey. Consensus guidelines and postoperative timing for the return to specific activities are presented

Osteoporosis is a major public health problem in the United States of America and around the world, largely due to the morbidity and mortality associated with osteoporotic fractures. In the past decade, large epidemiologic studies have contributed greatly to our understanding of patients who fracture. However, most studies are limited to postmenopausal white women. In this retrospective review, we analyze data from 185 men and women with acute fragility fractures who received osteoporosis consultations during admission to a single urban hospital between 2001 and 2003. Men and women differed in terms of risk factors for falls and osteoporosis but had areal bone mineral density (BMD) measurements remarkably similar, except at the total hip. Black and Hispanic subjects with fractures were significantly younger than whites yet were much more likely to have serious co-morbidities, such as diabetes mellitus and hypertension. In spite of significantly higher BMD measurements, black patients had the highest rates of vitamin D deficiency and secondary hyperparathyroidism. Patients admitted with hip fractures differed from those with non-hip fractures on a number of important variables. Based on these data, we conclude that elderly subjects admitted to an urban hospital with osteoporotic fractures are a heterogeneous group, with features that vary according to fracture type, gender and ethnicity. Future studies of patients with clinical fragility fractures should include ample numbers of men and ethnic minorities, since differences in underlying risk factors may suggest alternative strategies for fracture prevention.

Dislocation is a common complication of total hip arthroplasty, but exact effect of surgical approach on dislocation rates remains unclear. Because little randomized prospective data exist in this context, we performed a meta-analysis comparing dislocation rates using the posterior approach with and without soft tissue repair. A systematic literature review resulted in five studies which directly compared the posterior approach with and without soft tissue repair. The dislocation rates with and without repair were 0.49% and 4.46%, respectively. The relative risk for dislocation was determined using a fixed effects model with chi square test for interstudy heterogeneity. The posterior approach without soft tissue repair was found to have an 8.21 times greater relative risk of dislocation than with soft tissue repair (95% confidence interval, 4.05-16.67). A separate systematic review of 11 studies revealed comparable dislocation rates associated with the anterolateral, direct lateral, and posterior approaches with soft tissue repair (0.70%, 0.43%, and 1.01%, respectively). These data demonstrate that adequate soft tissue repair greatly reduces the relative risk of dislocation using the posterior approach, and that the dislocation rates for the three most prevalent approaches are similar. Further prospective randomized trials examining dislocation rates and other clinical parameters are needed.

A survey was distributed to the American Association of Hip and Knee Surgeons (AAHKS) membership to evaluate surgical treatment preferences for displaced femoral neck fractures (DFNFXs). Of 718 members, 381 (54%) responded to the 16-question survey that was an adjunct to a multicenter, randomized study (funded by AAHKS/OREF) designed to prospectively evaluate efficacy of hemiarthroplasty vs total hip for treatment of DFNFXs. Hemiarthroplasty (85%) was the most preferred treatment option for DFNFXs (reduction with internal fixation 2%, total hip arthroplasty 13%). Prefracture hip pain/osteoarthritis, poor bone quality, and fracture comminution were the main reasons why arthroplasty was chosen over reduction with internal fixation. Ambulatory status and dislocation risk after arthroplasty were the main factors in choosing between unipolar (48%) and bipolar (52%) hemiarthroplasty. Total hip arthroplasty is used by 88% of responders. Dislocation risk and ambulatory status were influential factors against performing total hip arthroplasty. Arthroplasty is the preferred method of surgical intervention for the treatment of DFNFXs for AAHKS members.

National orthopedic subspecialty meetings are a research forum where volumes of investigations are presented after a peer-reviewed selection process. The objective of this investigation was to determine the publication rate of recent scientific presentations presented at the American Association of Hip and Knee Surgeons (AAHKS) annual meetings. From 1996 to 2001, 168 (58%) of 292 podium abstracts presented at meetings were published. The average time to publication was 21.7 +/- 14.7 months. Three major orthopedic journals constituted 89% of the publications. The 58% publication rate for AAHKS ranks as one of the higher rates for orthopedic specialty meetings and validates the selection process for abstracts presented. In addition, AAHKS meetings are an excellent source for a wide array of quality research and scientific information.

The incidence of femoral neck fracture among the elderly in the United States is expected to increase dramatically because of the anticipated explosion in the population aged 65 years and older, increased life expectancy, and the rising incidence of osteoporosis. The resulting public health implications may be significant, with annual hospital admissions resulting from hip fracture projected to increase to 700,000 by 2050, and with annual spending on hip fracture care expected to exceed 15 billion dollars within a few years. The decision to perform internal fixation, unipolar hemiarthroplasty, bipolar hemiarthroplasty, or THA must be based on patient mental status, living arrangement, level of independence and activity, and bone and joint quality.

Extensor mechanism disruption after total knee arthroplasty is a challenging complication for orthopaedic surgeons. The treatment options for repair include observation, direct primary repair, direct primary repair with synthetic ligament or autogenous tissue augmentation, or reconstruction with allograft tissue. A computerized systemic review and literature search was performed to identify the relevant literature on extensor mechanism disruptions associated with total knee arthroplasty. A comprehensive review of the literature and description of relevant treatment options and outcomes were performed using the information gained with the literature review. A multi-center prospective study on a consecutive series of patients recruited from the North American Knee Arthroplasty Revision (NAKAR) study was performed and data collected pre-operatively, intra-operatively, and post-operatively on patients that had a failed total knee arthroplasty using validated health related quality of life measures was analyzed. Six out of 290 patients in the study had extensor mechanism disruption and this group of patients had overall worse functional outcomes. The results of the study have solidified our knowledge that patients with extensor mechanism disruptions have worse functional outcomes and will need intensive management and rehabilitation. Level of Evidence: Economic and decision analyses, level III (systematic review of level III studies). See Guide for Authors for a complete description of levels of evidence.