Faculty Bibliography

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.

INTRODUCTION/BACKGROUND:A variety of highly porous materials have been used to obtain biological acetabular fixation after total hip arthroplasty (THA). Due to their improved surface-coated properties, new highly porous titanium metal implants have shown potential to promote prosthesis osseointegration. Therefore, the purpose of this multicenter study was to evaluate: 1) overall acetabular cup survivorship; 2) postoperative complications; and 3) radiographic signs of loosening and radiolucencies in patients who received a new highly porous titanium metal cup. MATERIALS AND METHODS/METHODS:A total of 81 patients who underwent primary THA and received a new porous acetabular cup between May 16, 2013 and January 27, 2016 at three academic centers were included for analysis. There were 40 women (49%) and 41 men (51%) who had a mean age of 65 years (range, 38 to 95 years) and a mean body mass index (BMI) of 28 kg/m2 (range, 16 to 43 kg/m2). The minimum follow up time was two years and seven months (range, 2 to 4 years). The cup was engineered with fully interconnected porosity designed for potential long-term biologic fixation. Medical records were reviewed to assess for any revision surgeries and postoperative complications, and the most recent radiographs were reviewed for signs of loosening or radiolucencies. RESULTS:Overall, acetabular component survivorship, free of fixation failure or aseptic loosening, was 100%. Two patients underwent revision due to dislocations; however, revisions were performed because no constrained or dual mobility liners were available for the shell at the time. Both patients had successful outcomes and were doing well at final follow up with no further episodes of dislocation. There was one open reduction internal fixation for a periprosthetic femoral fracture, and three polyethylene revisions were performed for instability. In all of these cases, the acetabular cup was retained. On radiographic evaluation of antero-posterior pelvis radiographs, there was one patient who had radiolucencies of <1mm in Zone 1 and Zone 2 at 15 months after surgery, and another patient demonstrated radiolucencies of <1mm in Zone 2 and 3 at one-year follow up. At a minimum of two-year follow up, both patients had non-progressive and stable findings. CONCLUSION/CONCLUSIONS:The results of this study demonstrated excellent survivorship, and there were no radiographic failures of this acetabular cup in primary total hip arthroplasty patients. Although two patients were found to have minimal (<1mm) radiolucencies, these were not progressive. Longer follow-up studies are needed to further assess the survivorship and outcomes of this new acetabular cup; however, based on the results of this study, these are expected to be favorable.

INTRODUCTION/BACKGROUND:Tibial or femoral extra-articular deformities complicate the goal achieving optimal mechanical axis alignment for successful total knee arthroplasty (TKA) outcomes. In the presence of these extra-articular deformities, standard operative techniques and instruments may not be reliable. Robotic-arm assisted technology was developed to help achieve a well-aligned and balanced knee in a variety of clinical scenarios. Although prior case series have reported on the use of robotic-arm assisted devices for cases with severe angular deformity, there is a lack of data concerning the use of the robotic device for patients with other potentially complex surgical factors. Therefore, the purpose of this series was to present cases in which the robotic-arm assisted TKA application was used in the setting of extra-articular deformities to educate the surgeon community on this potentially useful method to address these complex cases. MATERIALS AND METHODS/METHODS:Three cases of patients who underwent robotic-arm assisted TKA in the setting of preoperative extra-articular deformities were identified. These included one with femoral and tibial fracture malunion, another with a proximal tibial fracture nonunion, and another with a healed tibial plateau fracture. Patient clinical histories, intraoperative surgical techniques, and postoperative outcomes were obtained. Specific focus was placed on the surgical management of the patient's pre-existing deformity. RESULTS:These three case reports are discussed in detail, with emphasis on preoperative planning and intraoperative techniques. The robotic software was able to appropriately consider the extra-articular deformity in the preoperative and real-time updated intraoperative plans. Doing so, the surgeon was able to achieve balanced and aligned TKA in each case. All three patients underwent robotic-assisted total knee arthroplasty with no intraoperative or postoperative complications. For all patients, their anteroposterior and lateral radiographs demonstrated well fixed and aligned femoral and tibial components with no signs of loosening or osteolysis. On physical exam, all patients had excellent range-of-motion with mean flexion of 122° (range: 120 to 125° of flexion) at final follow up. DISCUSSION/CONCLUSIONS:The decision on how to best approach TKA in patients with extra-articular deformity should be based on an extensive patient history, physical examination, and thorough evaluation of the magnitude and proximity of the deformity to the knee joint. Utilizing preoperative CT-scans with a 3D plan for robotic-arm assisted surgery allowed for appropriate assessment of the deformity preoperatively and execution of a plan for a balanced and aligned total knee arthroplasty. We have demonstrated excellent results utilizing robotic-arm assisted TKA in these complex cases.

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.

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.

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.

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:The purpose of this study is to track the 30-day postoperative annual rates and trends of (1) overall, (2) deep, and (3) superficial surgical site infections (SSIs) following total hip arthroplasty (THA) using a large nationwide database. METHODS:The National Surgical Quality Improvement Program database was queried for all THA cases performed between 2012 and 2016. After an overall 5-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with the preceding 4 years. Correlation coefficients and chi-squared tests were used to determine correlation and statistical significance. RESULTS:The lowest incidence of SSIs was in the most recent year, 2016 (0.81%), while the greatest incidence was in the earliest year, 2012 (1.12%), marking a 31% decrease (P < .01). The lowest rate was in the most recent year, 2016 (0.23%), marking a 26% decrease from 2012. The lowest superficial SSI incidence occurred in the most recent year, 2016 (0.58%), while greatest incidence was in 2012 (0.83%), marking a 31% decrease over time (P < .05). There was an inverse correlation among overall, deep, and superficial SSI rates with operative year. CONCLUSION/CONCLUSIONS:The findings from this study suggest a decreasing trend in SSIs within 30 days following THA. Furthermore, deep SSIs, which can pose substantial threats to implant survivorship, have also decreased throughout the years. These results highlight that potentially through improved medical and surgical techniques, we are winning the fight against short-term infections, but that more can still be done.