Faculty Bibliography

The effect of obesity on the outcomes of total joint arthroplasties is an ongoing concern. As obesity becomes more endemic, new categories emerge, such as the 'super-obese.' We conducted a retrospective study to determine the difference in outcomes among the super-obese. When categorized according to body mass index (BMI), the overall rate of complications was higher for patients with BMI of 45 or higher. Super-obese patients had an odds ratio (OR) of 8.44 for developing inhospital complications. Most importantly, each incremental 5-U increase in BMI above 45 was associated with an increased risk of inhospital (OR, 1.69) and outpatient complications (OR, 2.71), and readmission (OR, 2.0), compared with patients with BMI of 45 to 50. Length of stay was increased by 13.8% for each 5-U increase in BMI above 45. There is a significant increased risk for complications in the super-obese population, and this continues to increase with BMI increases above 45. These data are important when counseling super-obese patients and should be accounted for in reporting quality outcome measures in this population

The diagnostic value of the vacuum phenomenon between the femoral head and the acetabulum, and time frame of its occurrence after application of traction is an important clinical question. The resulting arthrogram may outline the shape, location, and extent of cartilage lesions prior to arthroscopy of the hip joint. The presence, duration, and diagnostic information of the vacuum phenomenon were evaluated in 24 hips that underwent arthroscopy. The operative diagnosis was compared to the results of imaging studies and to findings obtained during a traction trial prior to arthroscopy. Indications for arthroscopy included avascular necrosis, labral tears, loose bodies, osteoarthrosis, and intractable hip pain. In 22 hips the vacuum phenomenon developed within 30 seconds after application of traction. The most important data obtained from the vacuum phenomenon was the location and extent of femoral head articular cartilage detachment and the presence of nonossified loose bodies. The vacuum phenomenon did not reveal labral or acetabular cartilage pathology in any of these patients. The vacuum phenomenon obtained during the trial of traction can add valuable information prior to hip arthroscopy. Femoral head articular cartilage detachment was best documented by this method. The hip arthroscopist should utilize this diagnostic window routinely prior to hip arthroscopy.

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.

A fracture construct, representing a worst-case model of a comminuted intertrochanteric fracture, was created in order to compare the fixation stability of two different cephalomedullary nails: one where the lag screw can telescope within itself to achieve displacement of the head-neck fragment, and the other where the solid lag screw slides only. After nail fixation, the models were loaded and then cycled, and positions of the head-neck fragment and lag screw were determined. Both nails similarly acted to limit motion of the head-neck fragment by the sliding of their lag screws, causing impingement of the fragment against the nail. Fragment movement was achieved with significantly less force with the telescoping lag screws, which also showed no final lateral projection from the nail. This was in contrast to the solid lag screws that demonstrated lateral projection in all cases.

Hip resurfacing arthroplasty has been developed as an alternative to traditional total hip arthroplasty, in an effort to minimize the loss of native bone in young patients with symptomatic hip osteoarthritis. Femoral neck fracture following hip resurfacing is a unique complication; several risk factors are associated with this complication, including female gender. In the present study, we used finite element models of the proximal femur to simulate stresses across the femoral neck in pelvis models with varying widths. This analysis demonstrated an increase in hip reaction forces as the width of the pelvis increases, a condition that simulates a resurfacing condition in a female pelvis. This difference in peak stress on the femoral neck may explain the increased incidence of femoral neck fractures seen in female patients following hip resurfacing.

Orthopaedic patients with poor nutritional status are at an increased risk of postoperative complications, such as infection and wound healing. Nasal colonization with Staphylococcus aureus, especially with methicillin-resistant Staphylococcus aureus, has been shown to be a risk factor for surgical-site infections. We examined the incidence of nutritional depletion in our arthroplasty population and its correlation with Staphylococcus aureus colonization. We conducted a retrospective review of prospectively collected data of our arthroplasty patient population. Patients with known Staphylococcus aureus colonization or surgical-site infection were compared with a random cohort of patients. Patient demographics, preoperative nasal culture, and two nutritional screening scores were collected. Six hundred and fifty-two patients underwent arthroplasty and completed preoperative nasal cultures and nutritional assessment. A high percentage (27%) of our patients demonstrated some level of nutritional depletion prior to joint replacement. Overall nutritional scores were not significantly associated with surgery-type, preoperative nasal culture, or surgical- site infection in our patient population.

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

We retrospectively analyzed 97 total knee arthroplasty cases with medial osteoarthritis from seven participating surgeons in our teaching hospital to determine the percentage of patients who met the following eligibility criteria for unicompartmental knee arthroplasty (UKA): healthy cartilage in the lateral compartment based on (1) visual analysis, (2) histological analysis and (3) absence of UKA contraindications based on clinical analysis. The cases with healthy lateral cartilage, intact anterior cruciate ligament and posterior cruciate ligament, lack of patello-femoral arthritis, preoperative range of motion (ROM) greater than 90, and genu varum less than 10 degrees represented 21% of the 97 cases studied. This percentage would likely have been higher had the cases been assessed earlier in the disease process. It was concluded that there is the potential to utilize UKA more frequently in the future

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

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