Faculty Bibliography

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: Significant attempts have been made to adopt practices to minimize blood transfusion after total joint arthroplasty (TJA) because of transfusion cost and potential negative clinical consequences including allergic reactions, transfusion-related lung injuries, and immunomodulatory effects. We aimed to evaluate risk factors for blood transfusion in a large cohort of TJA patients. METHODS: We used the all-payer California Healthcare Cost and Utilization Project data from 2006 to 2011 to examine the trends in utilization of blood transfusion among arthroplasty patients (n = 320,746). We performed descriptive analyses and multivariate logistic regression clustered by hospital, controlling for Deyo-Charlson comorbidity index, age, insurance type (Medicaid vs others), gender, procedure year, and race/ethnicity. RESULTS: Eighteen percent (n = 59,038) of TJA patients underwent blood transfusion during their surgery, from 15% with single knee to 45% for bilateral hip arthroplasty. Multivariate analysis indicated that compared with the referent category of single knee arthroplasty, single hip had a significantly higher odds of blood transfusion (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.68-1.83), as did bilateral knee (OR, 3.57; 95% CI, 3.20-3.98) and bilateral hip arthroplasty (OR, 6.17; 95% CI, 4.85-7.85). Increasing age (eg, age >/=80 years; OR, 2.99; 95% CI, 2.82-3.17), Medicaid insurance (OR, 1.36; 95% CI, 1.27-1.45), higher comorbidity index (eg, score of >/=3; OR, 2.33; 95% CI, 2.22-2.45), and females (OR, 1.75; 95% CI, 1.70-1.80) all had significantly higher odds of blood transfusion after TJA. CONCLUSION: Primary hip arthroplasties have significantly greater risk of transfusion than knee arthroplasties, and bilateral procedures have even greater risk, especially for hips. These factors should be considered when evaluating the risk for blood transfusions.

BACKGROUND: Accurate cup positioning is one of the most challenging aspects of total hip arthroplasty (THA). Undetected movement of the patient during THA surgery can lead to inaccuracies in cup anteversion and inclination, increasing the potential for dislocation and revision surgery. Investigations into the magnitude of patient motion during THA are not well represented in the literature. METHODS: We analyzed intraoperative pelvic motion using a novel navigation device used to assist surgeons with cup position, leg length, and offset during THA. This device uses an integrated accelerometer to measure motion in 2 orthogonal degrees of freedom. We reviewed the data from 99 cases completed between February and September 2016. RESULTS: The mean amount of pitch recorded per patient was 2.7 degrees (standard deviation, 2.2; range, 0.1 degrees -9.9 degrees ), whereas mean roll per patient was 7.3 degrees (standard deviation, 5.5; range, 0.3 degrees -31.3 degrees ). Twenty-one percent (21 of 99) of patients demonstrated pitch of >4 degrees . Sixty-nine percent (68 of 99) of patients demonstrated >4 degrees of roll, and 25% (25 of 99) of patients demonstrated roll of >/=10 degrees . CONCLUSION: Our findings indicate that while the majority of intraoperative motion is <4 degrees , many patients experience significant roll, with a large proportion rolling >10 degrees . This degree of movement has implications for acetabular cup position, as failure to compensate for this motion can result in placement of the cup outside the planned safe zone, thus, increasing the potential for dislocation. Further study is warranted to determine the effect of this motion on cup position, leg length, and offset.

BACKGROUND: Accurate measurement of acetabular cup position (CP), changes in leg length (LL), and offset (OS) are paramount in ensuring proper sizing and implantation of components during total hip arthroplasty (THA). LL/OS inaccuracies can cause low back pain, neurological deficits, and patient dissatisfaction, while inaccurate positioning of the acetabular cup can lead to instability, dislocation, and, ultimately, revision surgery. The objective of this study was to evaluate the accuracy of a mini-navigation tool in measuring CP and LL/OS differential during THA. MATERIALS AND METHODS: Three board-certified orthopedic surgeons each performed four THA procedures via the posterior approach on six cadavers (12 hips) utilizing a novel mini-navigation tool. Imaging included pre- and post-operative radiographs and post-operative CT scans. Image analysis was performed by two radiologists not involved in the surgical procedures. System accuracy regarding measurement of cup position (anteversion and inclination) was determined by comparing the CT measurement of cup orientation with data gathered intraoperatively by probing the face of the implanted cup with the navigation tool and recording the coordinates. RESULTS: The mean absolute difference between CT and device measurements of cup position was 0.74 masculine (SD: 0.47, range: 0.19-1.48) for anteversion and 0.97 masculine (SD: 0.67, range: 0.27-2.57) for inclination. The mean difference between device and radiograph measurements of LL changes was 0.27 mm (SD: 3.61, range: -5.20-7.78) (absolute mean: 2.71+/-2.25 mm), while the mean difference in OS was 1.75 mm (SD: 3.00, range: -2.47-6.65) (absolute mean: 2.37+/-2.44 mm). CONCLUSIONS: This novel mini-navigation tool measured CP, LL, and OS accurately when compared with implant position measured on imaging.

BACKGROUND: Many cost drivers of total knee arthroplasty (TKA) have been critically evaluated to meet the heightened quality-associated expectations of performance-based care. However, assessing the efficacy of the different modalities of skin closure has been an underappreciated topic. The present study aims to provide further insight by conducting a meta-analysis and systematic review evaluating the rates of common complications and perioperative quality outcomes associated with different suture and staple skin closure techniques after TKA. METHODS: The present study was conducted in accordance with both the Preferred Reporting Items for Systematic Reviews and Meta-analyses Statement and the Cochrane Handbook for meta-analyses and systematic reviews. Primary outcome measures evaluated rates of common complications associated with primary TKA. Secondary outcome measures evaluated wound closure time, direct surgical costs, and cosmetic and knee function outcomes. RESULTS: Our meta-analysis demonstrated that skin sutures had a higher likelihood of superficial and deep infections, abscess formation, and wound dehiscence. Conversely, staples had a higher tendency for prolonged wound discharge. A systematic review of wound closure times and overall resource utilization demonstrated that wound closure was faster and more cost-effective with skin staples than sutures. CONCLUSION: Primary skin incision closure with staples demonstrated lower wound complications, decreased wound closure times, and an overall reduction in resource utilization. Given these outcomes, the use of staples after TKA may have several subtle clinical advantages over sutures.

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.

AIMS: Lumbar fusion is known to reduce the variation in pelvic tilt between standing and sitting. A flexible lumbo-pelvic unit increases the stability of total hip arthroplasty (THA) when seated by increasing anterior clearance and acetabular anteversion, thereby preventing impingement of the prosthesis. Lumbar fusion may eliminate this protective pelvic movement. The effect of lumbar fusion on the stability of total hip arthroplasty has not previously been investigated. PATIENTS AND METHODS: The Medicare database was searched for patients who had undergone THA and spinal fusion between 2005 and 2012. PearlDiver software was used to query the database by the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) procedural code for primary THA and lumbar spinal fusion. Patients who had undergone both lumbar fusion and THA were then divided into three groups: 1 to 2 levels, 3 to 7 levels and 8+ levels of fusion. The rate of dislocation in each group was established using ICD-9-CM codes. Patients who underwent THA without spinal fusion were used as a control group. Statistical significant difference between groups was tested using the chi-squared test, and significance set at p < 0.05. RESULTS: At one-year follow-up, 14 747 patients were found to have had a THA after lumbar spinal fusion (12 079 1 to 2 levels, 2594 3 to 7 levels, 74 8+ levels). The control group consisted of 839 004 patients. The dislocation rate in the control group was 1.55%. A higher rate of dislocation was found in patients with a spinal fusion of 1 to 2 levels (2.96%, p < 0.0001) and 3 to 7 levels (4.12%, p < 0.0001). Patients with 3 to 7 levels of fusion had a higher rate of dislocation than patients with 1 to 2 levels of fusion (odds ratio (OR) = 1.60, p < 0.0001). When groups were matched for age and gender to the unfused cohort, patients with 1 to 2 levels of fusion had an OR of 1.93 (95% confidence interval (CI) 1.42 to 2.32, p < 0.001), and those with 3 to 7 levels of fusion an OR of 2.77 (CI 2.04 to 4.80, p < 0.001) for dislocation. CONCLUSION: Patients with a previous history of lumbar spinal fusion have a significantly higher rate of dislocation of their THA than age- and gender-matched patients without a lumbar spinal fusion. Cite this article: Bone Joint J 2017;99-B:585-91.

BACKGROUND: A large component of the cost of revision total hip arthroplasty (THA) is the cost of the implants. We examined the pricing of revision THA implants to determine the possible savings of different pricing models. METHODS: From our institutional database, all revision THAs done from 9/1/2013 to 8/31/2014 were identified. The cost of the implants was analyzed as a percentage of the total cost of the hospitalization and compared to direct to hospital and fixed implant pricing models. RESULTS: Of 153 revision THAs analyzed, the cost of implants amounted to 36% of the total hospital cost. The direct to hospital cost and fixed implant pricing models would reduce the cost of an all-component revision to $4395 (saving $8962 per case) and $5000 (saving $8357 per case). CONCLUSION: Both fixed implant pricing and the direct to hospital pricing models would result in a decrease in revision implant costs.