Faculty Bibliography

AIM: To investigate whether normal thickness cartilage in osteoarthritic knees demonstrate depletion of proteoglycan or collagen content compared to healthy knees. METHODS: Magnetic resonance (MR) images were acquired from 5 subjects scheduled for total knee arthroplasty (TKA) (mean age 70 years) and 20 young healthy control subjects without knee pain (mean age 28.9 years). MR images of T1rho mapping, T2 mapping, and fat suppressed proton-density weighted sequences were obtained. Following TKA each condyle was divided into 4 parts (distal medial, posterior medial, distal lateral, posterior lateral) for cartilage analysis. Twenty specimens (bone and cartilage blocks) were examined. For each joint, the degree and extent of cartilage destruction was determined using the Osteoarthritis Research Society International cartilage histopathology assessment system. In magnetic resonance imaging (MRI) analysis, 2 readers performed cartilage segmentation for T1rho/T2 values and cartilage thickness measurement. RESULTS: Eleven areas in MRI including normal or near normal cartilage thickness were selected. The corresponding histopathological sections demonstrated mild to moderate osteoarthritis (OA). There was no significant difference in cartilage thickness in MRI between control and advanced OA samples [medial distal condyle, P = 0.461; medial posterior condyle (MPC), P = 0.352; lateral distal condyle, P = 0.654; lateral posterior condyle, P = 0.550], suggesting arthritic specimens were morphologically similar to normal or early staged degenerative cartilage. Cartilage T2 and T1rho values from the MPC were significantly higher among the patients with advanced OA (P = 0.043). For remaining condylar samples there was no statistical difference in T2 and T1rho values between cases and controls but there was a trend towards higher values in advanced OA patients. CONCLUSION: Though cartilage is morphologically normal or near normal, degenerative changes exist in advanced OA patients. These changes can be detected with T2 and T1rho MRI techniques.

BACKGROUND: Alternative payment models aim to improve quality and decrease costs associated with total joint replacement. Postoperative readmissions within 90 days are of interest to clinicians and administrators as there is no additional reimbursement beyond the episode bundled payment target price. The aim of this study is to improve the understanding of the patterns of readmission which would better guide perioperative patient management affecting readmissions. We hypothesize that readmissions have different timing, location, and patient health profile patterns based on whether the readmission is related to a medical or surgical diagnosis. METHODS: A retrospective cohort of 80 readmissions out of 1412 total joint replacement patients reimbursed through a bundled payment plan was analyzed. Patients were grouped by readmission diagnosis (surgical or medical) and the main variables analyzed were time to readmission, location of readmission, and baseline Perioperative Orthopaedic Surgical Home and American Society of Anesthesiologists scores capturing pre-existing state of health. Nonparametric tests and multivariable regressions were used to test associations. RESULTS: Surgical readmissions occurred earlier than medical readmissions (mean 18 vs 33 days, P = .011), and were more likely to occur at the hospital where the surgery was performed (P = .035). Perioperative Orthopaedic Surgical Home and American Society of Anesthesiologists scores did not predict medical vs surgical readmissions (P = .466 and .879) after adjusting for confounding variables. CONCLUSION: Readmissions appear to follow different patterns depending on whether they are surgical or medical. Surgical readmissions occur earlier than medical readmissions, and more often at the hospital where the surgery was performed. The results of this study suggest that these 2 types of readmissions have different patterns with different implications toward perioperative care and follow-up after total joint replacement.

Femoral fractures between a total hip arthroplasty prosthesis and total knee arthroplasty prosthesis, also called interprosthetic fractures, are challenging clinical problems. The number of patients who have undergone ipsilateral primary or revision joint arthroplasty procedures in both the hip and the knee continues to rise, and the number of interprosthetic fractures is increasing, as well. The growing body of biomechanical and clinical literature on interprosthetic fractures reflects the increased frequency of and interest in these injuries. Similar to the management of periprosthetic fractures, the management of interprosthetic fractures depends on the location of the fracture, the stability of the implant, and the ability to achieve stable fracture fixation. These factors are the basis of recently described classification systems and treatment strategies. In patients with stable implants, fracture fixation alone is performed. When the implant is loose, both revision arthroplasty and fracture fixation may be required to provide stability of the limb.

PURPOSE: How changes in the surgical team's culture can potentially reduce operating room (OR) traffic. INTRODUCTION: Excessive OR traffic during surgical procedures can present a risk to the patient's safety and recovery. Data suggest that limiting the number of OR personnel during the intraoperative period can reduce excessive OR traffic. However, it is unclear whether the surgeon's verbal intervention can also successfully reduce intraoperative OR traffic. This study compares traffic rates in hip and knee arthroplasty cases against traffic rates during nonarthroplasty cases to examine the effects of verbal interventions implemented by the surgeon to reduce intraoperative traffic. METHOD: The study consisted of 16 orthopedic surgeons in a noninterventional group and 1 orthopedic surgeon in the interventional group. The surgeon in the interventional group implemented verbal protocols to OR staff to limit excessive intraoperative traffic. Operating room traffic was monitored for 3 consecutive months (January-March 2015) with the use of infrared automated door counters that tracked door openings when someone entered or left the OR. RESULTS: A total of 50 hip and knee arthroplasties cases and 157 nonarthroplasty cases were tracked during the study period. A total of 134 hours and 4482 movements were collected for the hip and knee arthroplasty cases. A total of 498 hours and 22 902 movements were collected for the nonarthroplasty cases. Comparing the 2 groups, the interventional group averaged 33 movements per hour while the noninterventional group averaged 46 movements per hour (P < .001). CONCLUSIONS: These results suggest that operative room traffic can be reduced through simple verbal protocols established by the surgical team.

Objective: To investigate indications for and outcomes of total hip and knee arthroplasty in patients with multiple sclerosis (MS). Background: MS patients may need joint replacement due to MS-related factors, such as falls or avascular necrosis, or for unrelated indications (eg primary/secondary osteoarthritis). Literature on outcomes of total joint replacement in MS patients is limited to case reports that highlight surgical complications or unusual presentations. There are no systematic reviews of indications for and short- and long-term outcomes of hip and knee arthroplasty in MS patients. Design/Methods: Retrospective chart review of NYU MS Center patients who underwent hip or knee arthroplasty after MS onset. Results: 13 MS patients followed at NYU MS Care Center underwent hip (N=8) or knee (N=5) replacement at NYU. Average age at surgery was 56+/-11 years (range 35-69 years) and MS duration was 16+/-9 years; 10/13 were female. 3 patients had prior joint trauma and 1 had avascular necrosis of the hip presumably from steroid use; the remainder suffered from osteoarthritis. Ambulatory status before surgery was: 4-walking unassisted, 7 - cane, 2 - bilateral assistance. Ambulatory status after surgery at last follow up was: 8 walking unassisted, 3 using a cane, and 2 using a walker. Perioperative complications included acute blood loss in 4, pneumonia in 2, DVT in 1, and urinary retention in 1. Reoperation was required in 1 patient for recurrent hip dislocation. Conclusions: Orthopaedic literature focuses on perioperative complications after total joint arthroplasty in MS patients, but our data on unselected patients show that the surgery appears to benefit most of them, though (mostly) non-neurologic complications were seen in approximately half of the cases. These data can help optimize selection and surgical management of MS patients who are considering knee or hip replacement. We intend to present additional data on our patients that will include patient-reported outcomes

BACKGROUND: The incidence of hip fractures is growing with the increasing elderly population. Typically, hip fractures are treated with open reduction internal fixation, hemiarthroplasty, or total hip arthroplasty (THA). Failed hip fracture fixation is often salvaged by conversion THA. The total number of conversion THA procedures is also supplemented by its use in treating different failed surgical hip treatments such as acetabular fracture fixation, Perthes disease, slipped capital femoral epiphysis, and developmental dysplasia of the hip. As the incidence of conversion THA rises, it is important to understand the perioperative characteristics of conversion THA. Some studies have demonstrated higher complication rates in conversion THAs than primary THAs, but research distinguishing the 2 groups is still limited. METHODS: Perioperative data for 119 conversion THAs and 251 primary THAs were collected at 2 centers. Multivariable linear regression was performed for continuous variables, multivariable logistic regression for dichotomous variables, and chi-square test for categorical variables. RESULTS: Outcomes for conversion THAs were significantly different (P < .05) compared to primary THA and had longer hospital length of stay (average 3.8 days for conversion THA, average 2.8 days for primary THA), longer operative time (168 minutes conversion THA, 129 minutes primary THA), greater likelihood of requiring metaphysis/diaphysis fixation, and greater likelihood of requiring revision type implant components. CONCLUSION: Our findings suggest that conversion THAs require more resources than primary THAs, as well as advanced revision type components. Based on these findings, conversion THAs should be reclassified to reflect the greater burden borne by treatment centers.

BACKGROUND: To curb the unsustainable rise in health care expenses, health care payers are developing programs to incentivize hospitals and physicians to improve the value of care delivered to patients. Payers are utilizing various metrics, such as length of stay (LOS) and unplanned readmissions, to track progression of quality metrics. Relevant to orthopedic surgeons, the Centers for Medicare and Medicaid Services announced in 2015 the Comprehensive Care for Joint Replacement Payment Model-a program aimed at improving the quality of health care delivered to patients by shifting more of the financial risk of patient care onto providers. METHODS: We analyzed the medical records of 1329 consecutive lower extremity total joint patients enrolled in Centers for Medicare and Medicaid Services' Bundled Program for Care Improvement treated over a 21-month period. The goal of this study was to ascertain if hospital LOS is associated with unplanned readmissions within 90 days of admission for a total hip or knee arthroplasty. RESULTS: After controlling for multiple demographic variables including sex, age, comorbidities and discharge location, we found that hospital LOS greater than 4 days is a significant risk factor for unplanned readmission within 90 days (odd ratio = 1.928, P = .010). Total knee arthroplasty (TKA) and discharge to a location other than home are also independent risk factors for 90-day readmission. CONCLUSION: Our results demonstrate that increased LOS is a significant risk factor for readmission within 90 days of admission for a hip or knee arthroplasty in the Medicare population.

BACKGROUND: We describe the features of modern and historical bicruciate-retaining (BCR) total knee arthroplasty (TKA) implants compared with other TKA implant designs, reviewing kinematics, proprioception, operative technique, and clinical results. METHODS: We performed a review based on PubMed, Embase, CINAHL Plus, and Cochrane databases from January 1990 to April 2016 using combinations of the following keywords: "bicruciate-retaining arthroplasty," "bicruciate-retaining total knee arthroplasty," "bicruciate-retaining TKA," "kinematics," "knee kinematics," and "TKA kinematics." RESULTS: Four studies have supported the notion that preservation of both cruciate ligaments in TKA preserves more "normal" knee kinematics. BCR implants provide greater proprioceptive performance when compared with posterior cruciate-retaining (CR) TKA implants. However, the operative implantation is more challenging with BCR TKAs, requiring the surgeon to take additional precautions. Overall, there did not seem to be a significant difference in short-term clinical outcomes between the BCR and CR implants. CONCLUSIONS: The utility of BCR TKA is still debatable. The literature has not shown clear indications and guidelines for the value and use of this implant. Although kinematics have been shown to mirror the native knee more closely, the clinical outcomes of BCR vs CR TKAs do not differ significantly. Moreover, additional care must be taken when inserting a BCR implant. The anterior cruciate ligament exploration and preservation is more challenging and certain preparation and precautions must take place. Overall, we have not found that BCR implants are significantly superior to CR implants with regards to short term clinical outcomes despite the BCR TKA having improved kinematics and proprioception.