Faculty Bibliography

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.

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.

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.

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.

CASE/METHODS:We report the failure of a routine arthrotomy repair following knee arthroplasty. Five additional cases of arthrotomy failure occurred within a 14-month period during which a specific unidirectional knotless barbed suture device had been used for arthrotomy closure. CONCLUSION/CONCLUSIONS:Additional study on larger cohorts may be useful to understand the effectiveness of barbed suture for arthrotomy closure in knee arthroplasty.

BACKGROUND:Symptomatic instability following total knee arthroplasty (TKA) is a leading cause of early failure. Most reports recommend component revision as the preferred treatment because of poor outcomes and high failure rates with isolated tibial polyethylene insert exchange (ITPIE). However, these ideas have not been tested in modern implant systems that allow insert constraint to be increased. METHODS:We retrospectively reviewed 90 consecutive patients with minimum 2-year (mean 3.7 years) follow-up who underwent revision TKA for instability at a single institution. Mean age was 62.0 years (range, 41 to 83 years), and 73% of patients were women. Forty percent of patients were treated with ITPIE when standardized preoperative and intraoperative criteria were met; 60% underwent revision of one or both components when these criteria were not met. RESULTS:Patients experienced significant improvements in Knee Society (KS) knee (48.4 to 82.6; P < .001) and function (49.0 to 81.0; P < .001) scores. There were no significant differences in improvements in KS knee scores (38.1 vs 33.1; P = .18), KS function scores (36.0 vs 34.0; P = .63), or arc of motion (5° vs 6°; P = .88) between those treated with ITPIE and component revision. Failure rates were 19.4% in the ITPIE group vs 18.5% in the component revision group (odds ratio, 1.06; P = .91). Re-revision rates were significantly lower (6.3% vs 30.8%; odds ratio, 0.15; P = .004) when polyethylene insert constraint was increased. CONCLUSION:In selected patients, ITPIE is not inferior to component revision at addressing symptomatic instability following TKA. Degree of constraint should be increased whenever possible during revision surgery for instability.

BACKGROUND:We evaluated which treatment decisions in the management of displaced femoral neck fractures (FNFs) may associate with measures of resource utilization relevant to a value-based episode-of-care model. METHODS:A total of 1139 FNFs treated with hip arthroplasty at 7 hospitals were retrospectively reviewed. Treatment choices were procedure (hemiarthroplasty vs total hip arthroplasty [THA]), surgeon training status, admitting service, and time to surgery. Dependent variables were length of stay, discharge disposition, 30-day readmission, and in-hospital mortality. Variation across hospitals was evaluated with analysis of variance and chi-square tests. Treatment choices were evaluated for the dependent variables of interest with univariable and multivariable regression. RESULTS:There was significant variation between hospitals regarding proportion of cases treated with THA (range = 3.0%-73.2%, P < .001), proportion treated by arthroplasty fellowship-trained surgeons (range = 0%-74.9%, P < .001), proportion admitted to the orthopedic service (range = 2.8%-91.3%, P < .001), mean time to surgery (range = 0.9-2.1 days, P < .001), and proportion of discharge home (range = 63.9%-97.8%, P < .001). Multivariable analysis adjusting for age, gender, and Charlson Comorbidity Index demonstrated correlations between (1) decreased length of stay and admission to orthopedics (B = -1.256, P < .001); (2) lower 30-day readmission and THA (odds ratio [OR] = .376, P = .004), and (3) decreased discharge to a care facility and admission to orthopedics (OR = 0.402, P = <.001), THA (OR = 0.435, P = .002), and treatment by an arthroplasty fellowship-trained surgeon (OR = 0.572, P = .016). None of the treatment variables tested associated with in-hospital mortality. CONCLUSION:We observed significant variation in the treatment of displaced FNF patients across 7 hospitals and identified treatment choices that associated with resource utilization within the episode of care. Future, prospective study is necessary to understand whether care pathways that adapt some combination of these characteristics may result in more value-based care.

BACKGROUND:There is mounting evidence that treatment of periprosthetic joint infection of the knee with an antibiotic cement spacer (ACS) may increase risk for acute kidney injury (AKI). We sought to determine the incidence, as well as potential risk factors, of in-hospital AKI in this cohort. METHODS:We retrospectively identified 75 patients that received either a static or articulating ACS at a single institution. In-hospital AKI was defined by a more than 50% rise in serum creatinine from preoperative baseline to at least 1.4 mg/dL. Our secondary outcome was percent change in creatinine from preoperative to peak postoperative value. Variables were analyzed for the outcome of AKI with univariate logistic regression. A final multivariate model for percent change in creatinine was formed while controlling for age, gender, body mass index, and baseline creatinine. RESULTS:The incidence of AKI was 14.6%, occurring at a mean of 6.3 days (2-8 days). A lower preoperative hemoglobin (odds ratio = 1.82, P = .015) significantly increased risk for AKI on univariate analysis. Diagnosis of either hypertension or diabetes also showed a strong statistical trend (P = .056). On multivariate regression, lower preoperative hemoglobin significantly correlated with a greater percent rise in creatinine postoperatively (β = 0.30, P = .015). CONCLUSION:The incidence of AKI in patients who receive ACS is relatively high, raising clinical concern in the care of periprosthetic joint infection patients. Our results suggest that a lower baseline hemoglobin may be involved in the etiology of AKI in this population. Therefore, it may be clinically appropriate to monitor anemic patients for AKI when implanting an ACS.