Faculty Bibliography

Heterotopic ossification (HO), the development of bone outside its normal location in the skeleton, can compromise outcomes of total hip arthroplasty (THA). The etiopathogenesis of HO, though incompletely understood, involves genetic abnormalities, neurologic injury, and musculoskeletal trauma. Several systems are used to classify severity of HO after THA. Numerous risk factors for HO, including patient factors and surgical techniques, have been described. Prophylaxis against HO traditionally has involved radiation therapy or use of nonsteroidal anti-inflammatory drugs. Once formed, heterotopic bone can be managed only with surgical excision

Splash basins are used in arthroplasty cases to wash instruments. Several studies in the literature have shown these basins being a potential source of bacterial infection. This study assesses the risk of contamination of intraoperative splash basins used to wash and store instruments. A total of 46 random clean primary arthroplasty cases (32 hips, 13 knees, and 1 unicondylar knee) were studied by taking cultures of sterile splash basins as soon as they are opened (controls) and again at wound closure after instruments and debris have come into contact with the sterile water. All cultures were taken with sterile culture swabs and sent to the laboratory for aerobic, anaerobic, and fungal culture. Outcome measured was any positive culture. A total of 92 cultures from 46 cases were tested. Only 1 (2.17%) control culture, which grew Streptococcus viridans, was positive for bacterial growth. One of 46 samples (2.17%) taken at wound closure was positive for coagulase-negative Staphylococcus. Mean time between basin opening and wound closure was 180+/-45 minutes. For the 1 infected sample taken at the conclusion of the case, it was 240 minutes. Previous studies show contamination rates as high as 74% for splash basins used intraoperatively. Our study contradicts the belief that splash basins are a high source of infection, with only 2.17% of basins showing contamination. Splash basins can be a potential source of contamination, but the risk is not as high as previously cited in the orthopedic literature

There has been a steady increase in the number of revision total knee arthroplasties being performed in the United States. Hinge knee prostheses are used predominantly in complex primary or revision arthroplasties, often as salvage procedures. Significant improvement of the articulation between the rotating hinge mechanism and tibial component has decreased the stresses that contributed to earlier failures in previous generation designs. Two cases of fracture of the tibial metal post in the rotating hinge of a revision total knee arthroplasty were evaluated and treated at our institution within a 1-month period. We present our experience with this construct failure and subsequent patient management

Different acoustic frequencies have been used to diagnose progression of osteoarthritis, gross pathology, and wear in knee prostheses. It is possible that detailed analysis of higher frequencies could detect and quantify the smaller geometric changes (asperities) that develop in articular prosthetic wear. In this study we evaluated the feasibility of using ultrasonic emission to determine total knee arthroplasty (TKA) type and time from implantation using a simple, handheld measurement system. We examined the ultrasound emission generated by similar designs of posterior stabilized (PS) and cruciate retaining (CR) total knee prostheses and native knees of 58 patients and 10 controls. The subjects were asked to sit, rise, sit again, and take five steps while recording the acoustic data from both knees. Acoustic emission analysis examined frequency distributions and power spectrums of the recorded signals, and their relations to prosthesis type and time from implantation. We screened 44 CR and 48 PS TKAs, as well as 24 native knees. Analysis of this data suggested a possibility of differentiating between type of implants, and a relation to time since implantation. Our data suggest that we might be able to assess the status and time from implantation of a TKA by acoustic emission signals. Further in vitro analysis of the relationship of wear to ultrasonic emission data are needed for accurate quantification of arthroplasty wear. A simple, in-office screening tool for TKA patients could indicate which patients require closer follow-up and monitoring due to risk of potential problems

The purpose of this study was to compare fixation stability and lag screw sliding characteristics between 2 different hip-nail lag screw designs, a telescoping screwbarrel and a solid helical blade. Simulated, unstable, 4-part intertrochanteric hip fractures were created in 6 pairs of cadaveric femurs. Each nail type was randomly assigned within each femur pair. Lag screw sliding and inferior and lateral head displacements were measured following an applied static load of 750 N. Measurements were obtained before, during, and after cyclical loading with 750 N for 105 cycles. Ultimate failure strength was determined. After considering inferior head displacements, no significant differences between the 2 screw designs were found. Mean head displacement for the helical screw was 2.18 mm, compared with 1.87 mm for the telescoping screw (P = .731). A significant difference in the amount of lateral movement of the lag screws was found, however. The helical lag screws had mean lateral sliding of 2.68 mm, compared with 0.25 mm for the telescoping screws (P = .007). Neither of the lag screw constructs failed by screw cutout from the head. Both screw designs provide similar fixation strength for stabilization of 4-part intertrochanteric fractures. Both the telescoping lag screw and the helical blade facilitate fracture collapse, but the telescoping lag screw also minimizes lateral projection of the screw from the nail. This advantage may help minimize postoperative lateral soft-tissue impingement

Proper shoe size is an important element of foot health, especially in the elderly and diabetic populations. An improper fit can lead to pain, functional limitations, and falls. The aim of the present study was to determine the proportion of adults who are unaware of their own shoe size in 3 different New York City populations: a foot specialist private practice, an academic diabetic foot and ankle clinic, and a charity care center, the Bowery clinic, serving the homeless. A shoe size mismatch was defined as a difference of at least 0.5 in size between the measured foot and the shoe size. Demographic data were collected during the examination and retrospectively by chart review. A total of 235 volunteers participated in our study. A significant difference in the prevalence of the measured foot and shoe size mismatch was found between the cohort from the private practice compared with both the diabetic foot and ankle clinic and the Bowery clinic (P < .01 and P < .01, respectively). A significant difference was also detected (P < .05) between the private practice and the Bowery mission cohort when a difference of at least 1.5 sizes was present between the measured foot and the shoe size. Of those with a foot to shoe size mismatch, 60% had a difference of more than 0.5 in the shoe size between their right and left foot. In conclusion, our findings suggest that proper footwear sizing is lacking among a large proportion of our patients and that an adequate shoe size can be achieved with proper counseling

Postoperative development of heterotopic ossification can compromise the success of total hip arthroplasty (THA). Heterotopic ossification has been associated with decreased postoperative hip range of motion (ROM), potentially leading to poor patient satisfaction with outcome. Many risk factors predisposing to heterotopic ossification have been discussed in the literature, including sex, age, operative time, surgical approach, and preoperative function. The goal of this study was to examine if preoperative ROM is a risk factor for the development of severe heterotopic ossification after THA, and the impact of severe heterotopic ossification formation on the gain in ROM following THA. In a retrospective study of a single surgeon's 20-year experience, all patients who developed type III heterotopic ossification after THA were evaluated for hip ROM preoperatively and at 1-year follow-up. Total ROM was classified according to the modified Merle d'Aubigne score, and Harris Hip Scores were calculated. A statistically significant difference was found in preoperative external rotation in the study group compared to the control group (P<.001). At 1 year postoperatively, hip ROM differences were significant in external rotation (P<.001), internal rotation (P<.001), and abduction (P<.05). The modified Merle d'Aubigne score was significantly different between the groups (P<.001). Although many factors have been shown to influence the development of heterotopic ossification following THA, we found that a decrease in preoperative external rotation may point to an increased risk. Surgeons should consider this data when considering the use of prophylactic treatment to avoid the development of heterotopic ossification

Hip arthroplasty has become the standard treatment of end-stage osteoarthritis. However, postoperative complications are the risks associated with joint arthroplasty, which most significantly impact patient results and the total cost of care. Currently, no predictive system has been developed for categorizing levels of risk for the development of postoperative complications in patients undergoing total hip arthroplasty. We examined the association between the medical clearance risk rating by the physician performing the preoperative clearance examination and postoperative complications after total hip arthroplasty. We have demonstrated a significant association between the medical clearance risk rating and postoperative urinary track infection, and the American Society of Anesthesiologist score but no significant association to other complications. This study presents a predictive patient characteristic that may help us identify among our patients the ones that may benefit from a personally tailored preoperative planning and evaluation but demonstrates further work is necessary to better predict the risk of complications after total hip arthroplasty

Stem cell application is a burgeoning field of medicine that is likely to influence the future of orthopaedic surgery. Stem cells are associated with great promise and great controversy. For the orthopaedic surgeon, stem cells may change the way that orthopaedic surgery is practiced and the overall approach of the treatment of musculoskeletal disease. Stem cells may change the field of orthopaedics from a field dominated by surgical replacements and reconstructions to a field of regeneration and prevention. This review will introduce the basic concepts of stem cells pertinent to the orthopaedic surgeon and proceed with a more in depth discussion of current developments in the study of stem cells in fracture healing

Soft tissue balancing during total knee arthroplasty (TKA) has a direct affect on patello-femoral tracking and knee range of motion, which are necessary for a well functioning TKA postoperatively. We report on the use of an electronic pressure sensing instrument for soft tissue balancing of the knee before completion of all intraoperative bone cuts, as a way to improve patellar tracking. In a retrospective study of 99 consecutive TKAs, with intraoperative electronic instrument guided soft tissue balancing performed, a reduction in the incidence of lateral patellar retinacular release was found, as compared with the 100 consecutive TKAs prior to its use (5.5% v 12%, respectively). Electronic measurement of soft tissue balancing during TKA reduced the need for lateral patellar retinacular release.