Faculty Bibliography

Anterior cruciate ligament (ACL) rupture is a common injury that mostly affects young adults. The mechanisms of injury and surgical treatment have been extensively studied in both the laboratory and clinical arenas; however, great controversy still exists in regards to the best surgical technique, graft choice, and graft fixation device. In the area graft fixation, multiple breakthroughs have occurred in terms of fixation devices. These devices generally fall within the broad categories of interference screw, cross-pins, or cortical-based devices. Furthermore, some of these devices are available in either metal or bioabsorbable materials, which adds to the already great variety of options. Although biomechanically these devices have been shown to be able to withstand the typical forces experienced by the ACL graft during the early phases of rehabilitation before the graft has fully incorporated into the bone, little is known about the clinical outcomes. It is well recognized that graft fixation is the weakest link in the early postoperative period after ACL reconstruction. This review of the outcomes of ACL fixation devices explores some of the evidence available for the different devices.

BACKGROUND: In 2011 Medicare initiated a Bundled Payment for Care Improvement (BPCI) program with the goal of introducing a payment model that would "lead to higher quality, more coordinated care at a lower cost to Medicare." METHODS: A Model 2 bundled payment initiative for Total Joint Replacement (TJR) was implemented at a large, tertiary, urban academic medical center. The episode of care includes all costs through 90 days following discharge. After one year, data on 721 Medicare primary TJR patients were available for analysis. RESULTS: Average length of stay (LOS) was decreased from 4.27 days to 3.58 days (Median LOS 3 days). Discharges to inpatient facilities decreased from 71% to 44%. Readmissions occurred in 80 patients (11%), which is slightly lower than before implementation. The hospital has seen cost reduction in the inpatient component over baseline. CONCLUSION: Early results from the implementation of a Medicare BPCI Model 2 primary TJR program at this medical center demonstrate cost-savings. LEVEL OF EVIDENCE: IV economic and decision analyses-developing an economic or decision model.

STUDY DESIGN: A retrospective review of an administrative database. OBJECTIVE: The purpose of this study is to determine the current extent of regionalization by mapping lumbar spine procedures according to hospital and patient zip code, as well as examine the rate of growth of lumbar spine procedures performed at high-, medium-, and low-volume institutions in New York State. SUMMARY OF BACKGROUND DATA: The association between hospital and spine surgeon volume and improved patient outcomes is well established. There is no study investigating the actual process of patient migration to high-volume hospitals. METHODS: New York Statewide Planning and Research Cooperative System (SPARCS) administrative data were used to identify 228,695 lumbar spine surgery patients from 2005 to 2014. The data included the patients' zip code, hospital of operation, and year of discharge. The volume of lumbar spine surgery in New York State was mapped according to patient and hospital 3-digit zip code. New York State hospitals were categorized as low, medium, and high volume and descriptive statistics were used to determine trends in changes in hospital volume. RESULTS: Lumbar spine surgery recipients are widely distributed throughout the state. Procedures are regionalized on a select few metropolitan centers. The total number of procedures grew 2.5% over the entire 10-year-period. High-volume hospital caseload increased 50%, from 7253 procedures in 2005 to 10,915 procedures in 2014. The number of procedures at medium and low-volume hospitals decreased 30% and 13%, respectively. CONCLUSIONS: Despite any concerted effort aimed at moving orthopedic patients to high-volume hospitals, migration to high-volume centers occurred. Public interest in quality outcomes and cost, as well as financial incentives among medical centers to increase market share, potentially influence the migration of patients to high-volume centers. Further regionalization has the potential to exacerbate the current level of disparities among patient populations at low and high-volume hospitals. LEVEL OF EVIDENCE: 3.

Infection is a rare, serious complication after total joint arthroplasty and constitutes a considerable emotional and financial burden for patients, surgeons, and healthcare systems. Prevention of surgical site and periprosthetic joint infections is crucial. This requires knowledge of the microorganisms that commonly cause these infections, including Staphylococcus species. Selection of the appropriate antibiotic regimen to treat infection remains controversial, but cefazolin and cefuroxime are the most commonly recommended antibiotics for prophylaxis. Appropriate timing of administration before surgery, with redosing performed as needed, can help to ensure optimal antibiotic concentration during surgery. Given the increasing evidence that S aureus colonization is a risk factor for periprosthetic joint infection, an exploration of the potential benefits of preoperative S aureus carrier screening and decolonization protocols is warranted. The use of antibiotic-loaded bone cement in primary total joint arthroplasty and antibiotic powder at wound closure are other controversial topics that require additional research.

Although the Bundled Payments for Care Improvement (BPCI) Initiative began generating data in January 2013, it may be years before the data can determine if the BPCI Initiative enhances value without decreasing quality. Private insurers have implemented other bundled payment arrangements for the delivery of total joint arthroplasty in a variety of practice settings. It is important for surgeons to review the early results of the BPCI Initiative and other bundled payment arrangements to understand the challenges and benefits of healthcare delivery systems with respect to total joint arthroplasty. In addition, surgeons should understand methods of cost control and quality improvement to determine the effect of the BPCI Initiative on the value-quality equation with respect to total joint arthroplasty.

INTRODUCTION: The most frequent areas of cartilage loss in early-moderate knee OA are on a central band of the distal femur, and the center of the tibial surface with the anterior and medial areas being frequently involved as well (Wirth 2010; Bae 2010). It is therefore logical to design implants that resurface only these areas so that overall joint shape and structures will be preserved, component design will be simpler, and the surgery will be quick and accurate. Symmetric components for right and left knees would be an advantage. An additional factor in such a design is to avoid an 8-10mm resection of the dense bone of the proximal tibia. The purposes of this study were to devise a method for component design based on these criteria and to evaluate the accuracy of fit. METHODS: Average femur and tibia shapes including the cartilage were synthesized from 20 normal male knees using an algorithm in a reverse engineering software (Geomagic). The accuracy of the averaging method was verified. For the average femur, a sagittal section was taken through the major diameter of the medial femoral condyle Frontal sections were also taken normal to the sagittal section around the distal end of the femur. For the average tibia, sagittal and frontal plane sections were taken. Surfaces were defined from the sections. Five implant sizes were designed to match a male-female range. For the tests, the closest size was selected for each of the 20 knees. The accuracy of surface fit was quantified from a deviation analysis between the implant and the actual cartilage surface. RESULTS: The femoral bearing surface was accurately described by a toroid angled at 8 degrees to the sagittal plane (Fig. 1). The arc extended from 28degree anteriorly to 42degree posteriorly on the femoral condyle. The outer edges of the component were made parallel to the curved sides of the condyle. It was shown that this surface could be used for right and left knees. A toroid also closely fit the central region of the tibial bearing surface with blending radii connecting to the outer periphery comprising the D-shape around anterior-medial-posterior, and the tibial spine. A tibial component thickness of only 4mm at the center was achieved by specifying a metal component. This transferred the polyethylene to the femoral component with a thickness of 6mm, reinforced by a 3mm metal backing. In the fitting tests, both the femoral and tibial surfaces were a close match to the 20 knee samples (Fig. 2). The mean error for the femur was only 0.3mm with maximum error points reaching 0.8mm; the mean tibial errors were 0.5-0.7mm with peaks of up to 2mm error, but the errors were mainly in the peripheral regions especially around the tibial spine. DISCUSSION: The implants were designed to transmit the forces across the knee over an arc up to 42 degrees flexion, covering the most frequent activities. This is consistent with studies showing the regions of cartilage wear, with the relative absence of wear of the posterior femoral condyles in most cases. The closeness of fit of the implants to the bearing surfaces was due largely to the relatively small areas being resurfaced. This would contrast to a total knee which requires matching 3 large bearing surfaces simultaneously. Although in our evaluation, the femoral implant surface was matched to the normal cartilage, in practice, the size would be chosen with a slight projection from the condyle to ensure weight-bearing. On the tibial side, the contact location is normally around 5mm posterior of the center in an AP direction. This would be accomplished in a symmetric design due to the posterior sagittal slope. Reducing the tibial resection would be an advantage for fixation and in cases of a revision. The extra bone resection on the distal femur would not be a major disadvantage since 8-10mm of resection is performed routinely for a total knee. The reverse materials concept, originated by Charnley in the early 1970's (Purbach 2004), would need verification of comparable wear compared with the standard metal femur-plastic tibia format. Component fixation would also be another aspect requiring analysis. Overall, the goals of the project were accomplished, and it is expected that the implant described here could have a useful application for mild-moderate medial arthritis, contributing to the 'joint preservation' concept prior to requiring a total knee replacement. SIGNIFICANCE: Devising treatments for symptomatic OA of the knee in its early stages is extremely important especially for younger active patients, Moreover, the cost of such a procedure would be relatively low, a major factor in today's environment. This novel reverse materials concept can make a worthwhile contribution in providing a pain-free joint which will allow for normal function

BACKGROUND: Preoperative risk stratification and optimization of preoperative care may be helpful in reducing readmission rates after primary total joint arthroplasty. Assessment of the predictive value of individual modifiable risk factors without a tool to assess cumulative risk may not provide proper risk stratification of patients with regard to potential readmissions. As part of a Perioperative Orthopaedic Surgical Home model, we developed a scoring system, the Readmission Risk Assessment Tool (RRAT), which allows for risk stratification in patients undergoing elective primary total joint arthroplasty at our institution. The purpose of this study was to analyze the relationship between the RRAT score and readmission after primary hip or knee arthroplasty. METHODS: The RRAT, which is scored incrementally on the basis of the number and severity of modifiable comorbidities, was used to generate readmission scores for a cohort of 207 readmitted patients and two cohorts (one random and one age-matched) of 234 non-readmitted patients each. Regression analysis was performed to assess the strength of association of individual risk factors and the RRAT score with readmissions. We also calculated the odds and odds ratio (OR) at each RRAT score level to identify patients with relatively higher risk of readmission. RESULTS: There were 207 (2.08%) readmissions among 9930 patients over a six-year period (2008 through 2013). Surgical site infection was the most common cause of readmission (ninety-three cases, 45%). The median RRAT scores were 3 (IQR [interquartile range], 1 to 4) and 1 (IQR, 0 to 2) for readmitted and non-readmitted groups, respectively. An RRAT score of >/=3 was significantly associated with higher odds of readmission. CONCLUSIONS: Population health management, cost-effective care, and optimization of outcomes to maximize value are the new maxims for health-care delivery in the United States. We found that the RRAT score had a significant association with readmission after joint arthroplasty and could potentially be a clinically useful tool for risk mitigation.

Higher PJI rates may be related to identifiable risk factors, which may or may not be modifiable. Identifying risk factors preoperatively provides opportunities for modification and potentially decreasing the incidence of PJI. The purposes of this study were to: (1) retrospectively identify and quantify risk factors for PJI following primary TKA, and (2) to classify those significant risk factors as either non-modifiable or modifiable for intervention prior to surgery. Optimization of modifiable risk factors such as Staphylococcus aureus colonization, and tobacco use prior to primary TKA may decrease the incidence of periprosthetic joint infection after primary TKA, thereby reducing morbidity and the costs associated with treating those infections.

We aimed to examine and quantify the combined association of patient sociodemographic, preoperative comorbidities and intraoperative factors with extended and prolonged length of stay (LOS) following primary total hip arthroplasty. Longer LOS was associated with Age (>/=65years), BMI >/=30kg/m2, ASA score >2, minority race/ethnicity, low SES, general anesthesia, comorbidities of the Circulatory, Genitourinary and Respiratory systems, and operating time. Collectively, being of low SES, advanced age (>/=65years) and minority race/ethnicity was most significantly associated with prolonged LOS (>7days). The combined associations of lower SES, female gender, advanced age, non-Caucasian race/ethnicity and certain comorbidities presented a synergistically elevated risk for longer LOS and may warrant the need to consider sociodemographic status when allocating resources to hospitals serving such patients.