Faculty Bibliography

Background/UNASSIGNED:Failure of cementless acetabular osseointegration is rare in total hip arthroplasty. Nevertheless, new fixation surfaces continue to be introduced. Novel implants may lack large diameter, constrained bearings, or dual mobility (DM) bearings to address instability. We compared clinical and radiographic outcomes for acetabular components with differing fixation surfaces and bearing options, focusing on the relationship between fixation surface and osseointegration and the relationship between bearing options and dislocation rate. Methods/UNASSIGNED:We retrospectively reviewed 463 total hip arthroplasties implanted with 3 different acetabular components between 2012 and 2016. Records were reviewed for demographics, clinical scores, and complications. Radiographs were examined for evidence of acetabular osteointegration. Analysis of variance and chi-square tests were used to compare cohorts. Results/UNASSIGNED:All cohorts had 100% survivorship free of acetabular fixation failure with no differences in clinical scores. Dislocation occurred in 1.3% of cases (n = 6). Analysis of the "transition" sizes, for which brand determined the maximum bearing diameter, revealed a significantly higher dislocation rate (3/50, 6%) in implants with limited bearing options. All 4 revisions for recurrent dislocation involved well-positioned components that did not accept large diameter, constrained bearings, or DM bearings, resulting in 3 shell revisions to expand bearing options. Femoral revisions were associated with dislocation risk but did not vary between cohorts. Conclusion/UNASSIGNED:Dislocation was the primary mechanical cause for acetabular revision, while acetabular fixation failure was not encountered. We caution against selecting "new and improved" acetabular components without options for large diameter, constrained bearings, or DM bearings, even when enabling technology makes component positioning reliable.

A 60-year-old woman underwent revision total hip arthroplasty with a modular dual-mobility articulation for recurrent dislocation. At 1-year follow-up, the patient reported no dislocations but had occasional clicking and discomfort with extreme motion. A Dunn radiograph identified notching of the femoral stem, attributed to impingement. Metal ions were elevated without adverse local-tissue reaction. After 4.5 years of observation, the notch size remained stable. She denied pain. Neither stem fracture nor prosthetic dislocation occurred. Impingement against cobalt-chromium acetabular bearing surfaces can result in notching of titanium femoral components after total hip arthroplasty. Increased anteversion intended to protect against posterior dislocation may be a risk factor. Posterior notching is best visualized on Dunn views, so incidence may be underestimated. No associated femoral implant fractures were identified on literature review.

Robotic-assisted surgery was introduced to make various mechanical aspects of a total hip arthroplasty more reproducible. When paired with sophisticated three-dimensional preoperative planning, robotic surgery offers the promise that a surgeon might select and reliably achieve targets for component position to optimize hip center-of-rotation, acetabular anteversion and inclination, femoral offset, as well as limb length. This paper describes a patient-specific step-by-step approach to performing these procedures including taking into account pelvic tilt. It is hoped that these described techniques will further optimize robotic-assisted hip arthroplasty procedures.

BACKGROUND:Bundled payment initiatives were introduced to reduce costs and improve quality of care. Cemented vs cementless femoral fixation is a modifiable variable that may influence the cost and quality of care. New bundled payment data from the Centers for Medicare and Medicaid Services allowed us to study the influence of femoral fixation strategy on (1) 90-day costs; (2) readmission rates; (3) reoperation rates; (4) length of stay (LOS); and (5) discharge disposition for Medicare patients undergoing total hip arthroplasty. METHODS:We retrospectively studied 1671 primary total hip arthroplasty Medicare cases, comparing 359 patients who received cemented femoral fixation to 1312 patients who received cementless fixation. Centers for Medicare and Medicaid Services cost data as well as clinical data were reviewed. Demographic differences were present between the 2 cohorts. Statistical analyses were performed, including multiple regression models to adjust for baseline differences. RESULTS:Controlling for cohort differences, cemented patients were significantly more likely to be discharged home compared to cementless patients. Cemented patients also demonstrated trends toward lower costs, lower readmission rates, and shorter LOS compared to cementless patients. All reoperations within the early postoperative period occurred in patients managed with cementless femoral fixation. CONCLUSION:Among Medicare patients, cemented femoral fixation outperformed cementless fixation with respect to discharge disposition and also trended toward superiority with regards to LOS, readmission, cost of care, and reoperation. Cemented femoral fixation remains relevant and useful despite the rising popularity of cementless fixation.

INTRODUCTION/BACKGROUND:Imaging studies for preoperative planning of total hip arthroplasty (THA) are typically obtained by two-dimensional (2D) anteroposterior radiographs. However, CT imaging has proven to be a valuable tool that may be more accurate than standard radiographs. The purpose of this review was to report on the current literature to assess the utility of CT imaging for preoperative planning of THA. Specifically, we assessed its utility in the evaluation of: 1) hip arthritis; 2) femoral head osteonecrosis; 3) implant size prediction; 4) component alignment; 5) limb length evaluation; and 6) radiation exposure. MATERIALS AND METHODS/METHODS:A literature search was performed using search terms "computed tomography", "radiograph", "joint" "alignment", "hip," and "arthroplasty". Our initial search returned a total of 562 results. After applying our criteria, 26 studies were included. RESULTS:CT scans were found to be more accurate than radiographs in predicting implant size and alignment preoperatively and provide improved visualization of extraarticular deformities that may be essential to consider when planning a THA. Although radiation is a potential concern, newer imaging protocols have minimized the radiation to levels comparable to x-ray. CONCLUSION/CONCLUSIONS:The current literature suggests that CT has several advantages over radiographs for preoperative planning of THA including more accurate planning of implant size, component alignment, and postoperative leg length. It is also superior to x-ray in identifying extraarticular hip deformities using the minimum effective dose for CT and the minimum scan length required by templating software. The radiation can be reduced to values similar to radiography.

The potential added costs of managing fibromyalgia patients after total knee arthroplasty (TKA) have not been assessed. Therefore, the purpose of this study was to perform a cost analysis of fibromyalgia versus nonfibromyalgia patients who underwent TKA. Specifically, we evaluated the following episodes of care: (1) readmission rates, (2) total costs, (3) total reimbursements, and (4) net losses for surgical and medical complications. Patients who underwent TKAs between 2005 and 2014 from the Medicare Standard Analytical Files of the PearlDiver supercomputer were propensity score matched by patients with and without fibromyalgia in a 1:1 ratio based on age, sex, and the Charlson Comorbidity Index, yielding a total of 305,510 patients distributed equally between the cohorts for analysis. Odds ratios (ORs), 95% confidence intervals (CIs), and p-values were calculated. Mean costs, total costs, and total reimbursements were assessed as along with total net losses, which were defined as total costs minus total reimbursements. Fibromyalgia patients had similar 90-day readmission rates compared with nonfibromyalgia patients (OR: 1.03; 95% CI: 1.00-1.06; p = 0.06) but incurred lower readmission costs (US$2,318,384,295 vs. US$2,534,482,404; p < 0.001). Although fibromyalgia patients had higher total reimbursements for medical complications ($27,758,057 vs. US$18,780,610; p < 0.001), the increased management costs (US$106,049,870 vs. US$66,080,469; p < 0.001) led to greater net losses (US$78,291,813 vs. US$47,299,859; p < 0.001). Similarly, although fibromyalgia patients had higher total reimbursements for surgical complications (US$94,192,334 vs. US$73,969,026; p < 0.001), the increased surgical costs (US$382,122,613 vs. US$306,359,910; p < 0.001) led to greater net losses (US$287,930,279 vs. US$232,390,884; p < 0.001). This study highlights some of the potential financial discrepancies of managing patients with fibromyalgia. Our findings suggest medical and surgical complication costs to be greater than reimbursement, resulting in overall net financial losses. These findings need to be considered in the light of health care reform and cost structuring.

Although there are many studies on the alignment advantages when using the robotic arm-assisted (RAA) system for total knee arthroplasty (TKA), there have been questions regarding patient-reported outcomes. Therefore, the purpose of this study was to use this index to compare: (1) total, (2) physical function, and (3) pain scores for manual versus RAA patients. We compared 53 consecutive RAA to 53 consecutive manual TKAs. No differences in preoperative scores were found between the cohorts. Patients were administered a modified Western Ontario and McMaster Universities Osteoarthritis Index satisfaction survey preoperatively and at 1-year postoperatively. The results were broken down to: (1) total, (2) physical function, and (3) pain scores. Univariate analysis with independent samples t-tests was used to compare 1-year postoperative scores. Multivariate models with stepwise backward linear regression were utilized to evaluate the associations between scores and surgical technique, age, sex, as well as body mass index (BMI). Statistical analyses were performed with a p < 0.05 to determine significance. The RAA cohort had significantly improved mean total (6 ± 6 vs. 9 ± 8 points, p = 0.03) and physical function scores (4 ± 4 vs. 6 ± 5 points, p = 0.02) when compared with the manual cohort. The mean pain score for the RAA cohort (2 ± 3 points [range, 0-14 points]) was also lower than that for the manual cohort (3 ± 4 points [range, 0-11 points]) (p = 0.06). On backward linear regression analyses, RAA was found to be significantly associated with more improved total (β coefficient [β] -0.208, standard error [SE] 1.401, p < 0.05), function (β = 0.216, SE = 0.829, p < 0.05), and pain scores (β -0.181, SE = 0.623, p = 0.063). The RAA technique was found to have the strongest association with improved scores when compared with age, gender, and BMI. This study suggests that RAA patients may have short-term improvements at minimum 1-year postoperatively. However, longer term follow-up with greater sample sizes is needed to further validate these results.

Femoral component sizing and rotation in total knee arthroplasty (TKA) affects patellofemoral tracking and tibiofemoral mechanics. Posterior referencing is said to optimize restoration of posterior condylar offset. However, it typically allows the surgeon to select 3° to 5° of external rotation to the posterior condylar axis, inevitably changing the offset of one or both condyles. The axis about which external rotation occurs varies between the jigs of various TKA systems. The location of this axis can result in a medial, central, or lateral reference point for posterior offset restoration. Variations in jig design will result in varying posterior offset changes at the same jig setting, with differential effects on balance between the flexion and extension gaps. Using identical Sawbones in a controlled laboratory setting, 9 TKA instrumentation systems were examined. Two systems referenced medially, 1 referenced laterally, and 6 referenced centrally. The authors measured distal and posterior resections in both 3° and 5° of external rotation to the posterior condylar axis. They calculated changes in both distal and posterior joint lines using resection measurements and implant specifications. Posterior resection thicknesses were greatest with instruments that referenced laterally and least with instruments that referenced medially. With increasing external rotation, instruments that referenced off the lateral femoral condyle introduced the greatest mismatch between the distal and posterior joint lines, as compared with instruments that referenced centrally or medially. Surgeons should be aware that laterally referencing systems can differentially restore distal and posterior joint lines at higher settings of femoral external rotation, potentially introducing incongruity between flexion and extension gaps if the posterior slope of the tibia is maintained. This may be particularly problematic if flexion laxity is increased by posterior cruciate ligament sacrifice. [Orthopedics. 201x; xx(x):xx-xx.].

BACKGROUND:Prompt identification and treatment of wound complications is essential after joint arthroplasty, but emergency department and office visits for urgent evaluation of normal incisions are a source of unnecessary cost. The purpose of this study is to evaluate the use of an online image messaging platform for remote monitoring of surgical incision sites. METHODS:We conducted a retrospective review of 1434 hip and knee arthroplasty patients who registered for an online platform in the perioperative period. We reviewed images sent by patients to evaluate potential wound abnormalities. Medical records were reviewed to determine whether assessments based on wound photographs corresponded with subsequent in-person findings and ultimate disposition. RESULTS:Four hundred thirty patients (42%) sent at least one text or image message to their provider. Elimination of redundant images resulted in 104 image encounters, with 76 discrete encounters in 41 patients related to the surgical wound. Most showed normal wound appearance; patients were reassured and urgent visits were avoided. At scheduled in-person follow-up, none of these patients demonstrated unrecognized wound complications. Seventeen image encounters in 7 patients showed possible wound abnormalities. These prompted in-person follow-up on average less than 1 day later for 4 issues deemed urgent (2 patients received surgical treatment) and 5 days later for issues deemed nonurgent. Photos were also used to monitor abnormal wounds over time and to send information unrelated to wounds. CONCLUSION/CONCLUSIONS:Utilization of an online physician-patient messaging platform can prevent unnecessary visits for normal appearing wounds, while facilitating rapid in-person treatment of wound complications.