Retrieval Analysis of Polyethylene Components in Rotating Hinge Knee Arthroplasty Implants.

BACKGROUND: This study examined a cohort of retrieved rotating hinge (RH) total knee arthroplasty implants of four different designs with emphasis on the surface damage observed on the polyethylene components. Our purpose was to determine if differences in polyethylene damage existed among the designs, and if those differences could be explained by differences in design characteristics. MATERIALS AND METHODS: Seventy-two RH implants from four manufacturers (DePuy LPS/SROM, Zimmer NexGen, Stryker Howmedica MRH, and Biomet Finn-OSS) removed at the time of revision performed between 2002 and 2017 were identified in our institutional retrieval registry. Damage to the surfaces of the polyethylene was assessed using a subjective grading system and evaluated in multiple zones. Design characteristics that were evaluated included the following: location of the dwell point on the polyethylene component, posterior position of the axle, and amount of hyperextension and rotation allowed by the implant. RESULTS: There were no differences in total damage scores between the four implant groups (P = .45). The Stryker Howmedica MRH group showed the least backside wear of all implants but significantly more articular-sided wear compared with two of the other three groups. All implants except NexGen showed increased total damage scores in implants revised for mechanical (vs nonmechanical) reasons and in implants with a longer duration of implantation. CONCLUSION: No single implant design emerged as superior in terms of minimizing polyethylene wear damage. Polyethylene damage existed in various locations but was not different in severity across designs, suggesting that there is no clear superior RH design that minimizes overall articular surface wear compared with other designs.

Multicenter Evaluation of a Modular Dual Mobility Construct for Revision Total Hip Arthroplasty.

INTRODUCTION: Modular Dual Mobility (MDM) constructs in total hip arthroplasty (THA) offer increased hip stability compared with constrained liners, without compromising hip range of motion. The purpose of this study was to evaluate outcomes of revision THA using MDM. METHODS: The study was a multiinstitutional retrospective cohort study of 315 hips that underwent revision THA using MDM between 2011 and 2017. Clinical outcomes and reasons for failure were collected. RESULTS: Three hundred fifteen patients met 1-year minimum follow-up (mean 3.3 years). Nine hips had instability postoperatively (2.9%), and 30 hips required reoperation (9.5%). Seven had recurrent instability (6.5%) which was associated with liner-only exchange (P = .021) and liner outer diameter of ≤ 38 mm (P = .016). CONCLUSION: Revision THA with MDM provided a low rate of instability and reoperation in a revision cohort. Recurrent instability following use of MDM in revision THA was associated with retention of the acetabular component and polyethylene outer diameter ≤ 38 mm. LEVEL OF EVIDENCE: Therapeutic Level III.

One- and two-stage surgical revision of peri-prosthetic joint infection of the hip: a pooled individual participant data analysis of 44 cohort studies.

One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

Reduction Loss After Distal Radius Fracture Fixation With Locked Volar Plates.

Distal radius fractures are among the most common injuries in the upper extremity. While many studies have looked at the maintenance of reduction with volar locking plates, there is a paucity of literature comparing the ability of different plates to maintain reduction over time. This study reviews the ability of various plates to maintain radiographic reduction at union after distal radius fracture treatment. Loss of some aspect of fracture reduction was routinely observed following locked volar plating regardless of implant. However, choice of implant did have a significant impact on final radiographic alignment, particularly with respect to volar tilt and ulnar variance. Yet, selecting between a fixed angle versus a variable angle was not found to make a difference in maintaining reduction. The authors recommend that surgeons take these findings into consideration when selecting a volar locking plate. (Journal of Surgical Orthopaedic Advances.

Individualized Risk Model for Venous Thromboembolism After Total Joint Arthroplasty.

BACKGROUND: Venous thromboembolism (VTE) after total joint arthroplasty (TJA) is a potentially fatal complication. Currently, a standard protocol for postoperative VTE prophylaxis is used that makes little distinction between patients at varying risks of VTE. We sought to develop a simple scoring system identifying patients at higher risk for VTE in whom more potent anticoagulation may need to be administered. METHODS: Utilizing the National Inpatient Sample data, 1,721,806 patients undergoing TJA were identified, among whom 15,775 (0.9%) developed VTE after index arthroplasty. Among the cohort, all known potential risk factors for VTE were assessed. An initial logistic regression model using potential predictors for VTE was performed. Predictors with little contribution or poor predictive power were pruned from the data, and the model was refit. RESULTS: After pruning of variables that had little to no contribution to VTE risk, using the logistic regression, all independent predictors of VTE after TJA were identified in the data. Relative weights for each factor were determined. Hypercoagulability, metastatic cancer, stroke, sepsis, and chronic obstructive pulmonary disease had some of the highest points. Patients with any of these conditions had risk for postoperative VTE that exceeded the 3% rate. Based on the model, an iOS (iPhone operating system) application was developed (VTEstimator) that could be used to assign patients into low or high risk for VTE after TJA. CONCLUSION: We believe individualization of VTE prophylaxis after TJA can improve the efficacy of preventing VTE while minimizing untoward risks associated with the administration of anticoagulation.

Development and Validation of a Risk Stratification System for Pulmonary Embolism After Elective Primary Total Joint Arthroplasty.

INTRODUCTION: Stratification of patients into different risk categories for pulmonary embolism (PE) after total joint arthroplasty (TJA) may allow clinicians to individualize venous thromboembolism prophylaxis based on an appropriate risk-benefit scale. METHODS: Patients undergoing primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) as part of the American College of Surgeons National Surgical Quality Improvement Program were identified. Independent risk factors for PE within 30 days of surgery were identified and used to develop a point-scoring system to estimate the relative risk for PE. For validation, the system was tested on patients undergoing TJA at a single institution. RESULTS: A total of 118,473 patients were identified, including 72,673 (61.3%) undergoing TKA and 45,800 (38.7%) undergoing THA. The incidence of PE within 30 days of the index arthroplasty was 0.50%. The risk factors associated with PE were age ≥70, female gender, higher body mass index (25-30 kg/m(2) and ≥30 kg/m(2)), and TKA (vs THA); anemia was protective. The point scores derived for each of these factors were as follows: anemia: -2; female: +1; body mass index 25-30 kg/m(2): +2; body mass index ≥30 kg/m(2): +3; age ≥70 years: +3; TKA: +5. The point-scoring system was then applied to 17,384 patients from a single institution. Single-institution patients categorized as low risk using the point-scoring system had a 0.44% 90-day risk for PE (95% CI = 0.29%-0.58%); medium risk, 1.51% (95% CI = 1.18%-1.84%); and high risk, 2.60% (95% CI = 2.09%-3.10%). CONCLUSION: This point-scoring system predicts risk for PE after TJA and may help surgeons to optimize selection of chemical prophylaxis.

Aspirin Is as Effective as and Safer Than Warfarin for Patients at Higher Risk of Venous Thromboembolism Undergoing Total Joint Arthroplasty.

BACKGROUND: There is continued controversy regarding the optimal venous thromboembolism (VTE) prophylaxis, particularly for total joint arthroplasty (TJA) patients at higher risk. The purpose of this study was to compare the efficacy of aspirin (ASA) to warfarin in patients with higher risk of VTE. METHODS: This retrospective study examined 30,270 patients who received ASA or warfarin for VTE prophylaxis after TJA. Using a previously developed risk stratification model, patients were classified into low or high VTE risk categories. Postoperative 90-day VTE, periprosthetic joint infection (PJI), gastrointestinal complications, and mortality were recorded. RESULTS: The incidences of VTE, PJI, and mortality were higher in patients receiving warfarin compared to ASA. In multivariate analysis, warfarin was an independent risk factor for VTE, PJI, and mortality in the higher risk VTE patients (P < .001). There was no significant difference in gastrointestinal complications between groups. CONCLUSION: Our study demonstrates that ASA is as effective as and safer than warfarin for VTE prophylaxis after TJA, even in patients at higher risk of VTE.

Administration of Aspirin as a Prophylaxis Agent Against Venous Thromboembolism Results in Lower Incidence of Periprosthetic Joint Infection.

The efficacy and safety of aspirin (ASA) for prevention of venous thromboembolism (VTE) following total joint arthroplasty (TJA) have been demonstrated. Our hypothesis was that postoperative ASA compared to warfarin lowers the incidence of periprosthetic joint infection (PJI). Between January 2006 and December 2012, 1456 patients received ASA and 1700 patients received warfarin following primary TJA as standard VTE prophylaxis. Logistic regression was utilized to identify independent risk factors of PJI. Incidence of PJI was significantly lower at 0.4% in patients receiving ASA vs. 1.5% in patients receiving warfarin (P<0.001). Warfarin and elevated BMI were independent risk factors for PJI following TJA (P<0.05). Our research suggests that the use of ASA compared to warfarin for VTE prophylaxis reduces the risk of PJI following TJA.

Total joint arthroplasty in cancer patients.

Increasing numbers of total joint arthroplasty (TJA) patients have a history, or an active diagnosis, of cancer. We aimed to evaluate the risk of early postoperative complications in these patients. In our series, a history of malignancy was associated with an elevated risk of ischemic cardiac events and postoperative deep vein thrombosis (DVT), while active malignancy was associated with increased respiratory and renal complications, hematoma/seroma formation and early postoperative mortality. Both groups presented increased rates of overall in-hospital complications. Patients with bone metastasis to the hip demonstrated increased DVT and 90-day mortality rates. Cancer patients have increased morbidity and mortality after TJA and should undergo comprehensive medical optimization and adapted thromboprophylaxis.

Timing of Symptomatic Pulmonary Embolism with Warfarin Following Arthroplasty.

The purpose is to determine the incidence and timing of pulmonary embolism for patients receiving warfarin for thrombo-prophylaxis following total joint arthroplasty (TJA). Current guidelines for duration of prophylaxis are nonspecific. Chemical prophylaxis carries the risk of bleeding and associated periprosthetic joint infection. We retrospectively studied 26,415 primary and revision TJA cases performed at our institution between 2000 and 2010. The overall 90-day rate of symptomatic PE was 1.07%. Fatal PE rate was 0.02%. Out of 283 documented symptomatic PE cases, 81% occurred within three postoperative days, 89% within one postoperative week, and 94% within two postoperative weeks. The risk of symptomatic PE appears to be highest during the first week after TJA. Efforts must be made to minimize risk during this period.

Symptomatic pulmonary embolus after joint arthroplasty: stratification of risk factors.

BACKGROUND: Prophylaxis for pulmonary embolism (PE) after total joint arthroplasty (TJA) presents the clinical dilemma of balancing the risk of postoperative thrombotic risk and anticoagulation-related complications such as bleeding, hematoma formation, and infection. Risk stratification of patients undergoing TJA is needed to tailor prophylaxis based on thrombotic and bleeding risk. QUESTIONS/PURPOSES: The purpose of this study was to identify the preoperative comorbidities that were associated with an increased risk of symptomatic PE after joint arthroplasty in a large group of patients who had TJAs and who were treated with either aspirin or warfarin. METHODS: We conducted a retrospective study of 26,391 primary and revision TJAs performed at our institution between January 2000 and April 2011. A total of 24,567 patients received warfarin prophylaxis for 6 weeks (targeted international normalized ratio of 1.5-2.0) and 1824 patients received 325 mg aspirin twice daily. Symptomatic patients with decreased oxygen saturation were evaluated for PE using either a ventilation/perfusion scan or multidetector CT scan. Symptomatic PEs occurring in patients within 90 days postoperatively identified with CT or ventilation/perfusion scans were considered complications related to surgery, and fatal PEs were those that occurred in patients who died during the hospital admission owing to cardiopulmonary failure after PE. Using a logistic regression analysis, a nomogram was created to predict postoperative symptomatic PE risk. RESULTS: Risk of postoperative symptomatic PE after primary and revision TJAs was 1.1%. Risk of postoperative fatal PE was 0.02%. Elevated BMI (p < 0.035), procedures on the knee (p < 0.006), higher Charlson Comorbidity Index (p < 0.015), chronic obstructive pulmonary disorder (p = 0.006), atrial fibrillation (p < 0.001), anemia (p < 0.001), presence of deep vein thrombosis (p < 0.001), and depression (p = 0.012) were independent risk factors for symptomatic PE. Based on these risk factors and derived scoring criteria, patients can be classified into low- (0.35%), medium- (1.4%), and high- (9.3%) risk categories. CONCLUSIONS: Patients who are obese, undergo knee procedures, have an elevated Charlson Comorbidity Index, chronic obstructive pulmonary disease, atrial fibrillation, anemia, depression, or postoperative deep vein thrombosis are at greater risk of having a postoperative PE develop. These risk factors should be considered when deciding on postoperative anticoagulation prophylaxis. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Aspirin: an alternative for pulmonary embolism prophylaxis after arthroplasty?

BACKGROUND: The most effective agent for prophylaxis against venous thromboembolic disease after total joint arthroplasty (TJA) remains unknown. The paucity of literature comparing different methods of pulmonary embolism (PE) prophylaxis and fear of litigation make it difficult for surgeons to abandon the use of aggressive chemical prophylaxis. QUESTIONS/PURPOSES: We compared the (1) overall frequency of symptomatic PE, (2) risk of symptomatic PE after propensity matching that adjusted for potentially confounding variables, and (3) other complications and length of stay before and after propensity matching in patients undergoing TJA at our institution who received either aspirin or warfarin prophylaxis. METHODS: A total of 28,923 patients underwent TJA between January 2000 and June 2012 at our institution, had either aspirin (325 mg twice daily; 2800 patients) or warfarin prophylaxis (26,123 patients), and were registered in our institutional electronic database. The incidence of symptomatic PE, symptomatic deep vein thrombosis (DVT), hematoma formation, infection, wound complications, and mortality up to 90 days postoperatively was collected from the database. We performed multivariate analysis and 3:1 and 5:1 propensity score matching for comorbid and demographic variables. RESULTS: The overall symptomatic PE rate was lower (p < 0.001) in patients receiving aspirin (0.14%) than in the patients receiving warfarin (1.07%). This difference did not change after matching. The aspirin group also had significantly fewer symptomatic DVTs and wound-related problems and shorter hospital stays, which did not change after matching. CONCLUSIONS: After publication of the American Academy of Orthopaedic Surgeons' guidelines, some surgeons have utilized aspirin as thromboprophylaxis after TJA. Based on our findings from a large institutional database, aspirin offers suitable prophylaxis against symptomatic PE in selected patients.

The impact of patellar resurfacing in two-stage revision of the infected total knee arthroplasty.

Evidence for optimal management of the patellofemoral joint in revision surgery for the infected TKA is limited. We reviewed 69 infected TKAs undergoing two-stage revision. Fifty four patellae were resurfaced, 11 had patelloplasty performed, two were augmented with trabecular metal, one had impaction grafting, and one knee underwent patellectomy. Average follow-up was 4.5 years. The patients that received patellar resurfacing at re-implantation experienced statistically significant improvements in KSS pain score, functional KSS, and patellar score (P < 0.03). One further patient treated with impaction grafting improved significantly in terms of pain and function. Patients treated with patelloplasty, trabecular metal augmentation, or patellectomy did not have significant improvements in clinical or functional outcome. Patient age, use of dynamic vs. static spacer, use of extensor mechanism release, and differences in Charlson index did not seem to statistically affect outcome. We recommend that every effort should be made to minimize patellar bone loss in first stage resection, as inability to resurface the patella at time of reimplantation may adversely affect patient outcome.

Total joint arthroplasty: should patients have preoperative dental clearance?

Obtaining dental clearance prior to elective total joint arthroplasty is a common practice; however, little published data exist to justify this requirement. Dental clearance data for 365 elective total knee and total hip arthroplasty patients were gathered prospectively. Of these patients, 358 (average age of 62.4 years; 157 men and 201 women; 152 primary total knee arthroplasties (TKAs), 16 revision TKA arthroplasties, one conversion TKA, 168 primary total hip (THAs) arthroplasties and 21 revision THA arthroplasties) proceeded to surgery and follow-up data were available for 355. A comparison group of 218 hip fracture patients (average age of 78.7 years; 52 men and 109 women; 137 THA and 81 hemiarthroplasties) with no preoperative dental clearance who were treated with hip arthroplasty was extracted retrospectively from an institutional database. Follow-up data were available for 161 of these patients. The incidence of dental pathology in the elective arthroplasty group was 8.8%. Early postoperative infection requiring surgical treatment occurred in six patients (1.7%) in the dental clearance elective arthroplasty group and in four patients (2.5%) in the hip fracture arthroplasty group. No statistical difference was found between the two groups. This suggests that the perceived need for routine preoperative dental screening for all hip and knee arthroplasty patients should be reassessed.

The effect of malnutrition on patients undergoing elective joint arthroplasty.

Malnutrition has been linked to serious complications in patients undergoing elective total joint arthroplasty (TJA). This study prospectively evaluated 2,161 patients undergoing elective TJA for malnutrition as defined by either an abnormal serum albumin or transferrin. The overall incidence of malnutrition was 8.5% (184 of 2,161) and the rate of overall complications in the malnourished group was 12% as compared to 2.9% in patients with normal parameters (P<0.0001). Malnutrition predicted serious complications involving hematoma formation, infection, renal and cardiac complications. Obesity, defined by a body mass index (BMI) of 30kg/m(2) was present in 42.9% of malnourished patients with a significantly higher complication rate in this cohort. Malnutrition remains prevalent in patients >55years-old undergoing TJA and is associated with a significant increase in post-operative complications.

Risk factors for early mortality following modern total hip arthroplasty.

The aim of this study was to evaluate the incidence of early mortality and identify risk factors for early death following modern uncemented THA. Between 2000 and 2006, we identified patients who died within 90days of THA. Demographics, comorbidities, laboratory studies, and complications were analyzed as risk factors for mortality. 38 of 8261 patients undergoing THA (0.46%) died within 90days postoperatively. Of these, 26% were due to myocardial infarction. Multivariate analysis revealed Charlson index >3, peripheral vascular disease, elevated postoperative glucose, and abnormal postoperative cardiac studies as independent predictors of early mortality following THA. Caution should be taken in patients with increased comorbidities, PVD, perioperative hyperglycemia, and impaired renal function in order to reduce mortality following THA.

Culture-negative periprosthetic joint infection does not preclude infection control.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty. Lack of confirmation of an infecting organism poses a challenge with regard to the selection of an appropriate antibiotic agent and surgical treatment. It is unclear whether patients with negative cultures presumed to have infections achieve similar rates of infection-free survival as those with positive cultures. QUESTIONS/PURPOSES: The purposes of this study were (1) to report the infection control rates using irrigation and débridement and two-stage exchange for treatment of culture-negative PJIs; and (2) to compare infection control rates in culture-negative cases with those in culture-positive cases. METHODS: We retrospectively reviewed 55 patients with culture-negative PJI treated between 2000 and 2007. We compared the infection-free survival rate in the culture-negative patients with that of 295 culture-positive cases of PJI. RESULTS: Overall infection control rate in culture-negative cases was 73% at minimum 1-year followup (mean, 47 months; range, 12-119 months). We found similar infection control rates in culture-negative and culture-positive PJI. Infection-free survival rates in both groups were highest after two-stage exchange arthroplasty and postoperative vancomycin therapy. CONCLUSION: Our observations suggest aggressive two-stage exchange arthroplasty and postoperative parenteral vancomycin therapy in patients with culture-negative PJI achieves similar rates of infection-free survival as with patients having culture-positive PJI. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Mini-open femoroacetabular osteoplasty: how do these patients do?

Femoroacetabular impingement, a condition seen in young active patients, is believed to lead to early degeneration of the hip joint if left untreated. We have over the last 5 years utilized a mini-open direct anterior approach to perform femoroacetabular osteoplasty (FAO) for the hip. Between January 2006 and February 2011, 293 hips (265 patients) underwent direct anterior mini-open FAO performed by a single surgeon; 156 hips (149 patients) have reached a minimum 2-year follow-up, with an average follow-up of 2.3 years (range 2.0 to 4.2 years). Preoperative Short Form 36, Western Ontario and McMaster Universities Arthritis Index, University of California Los Angeles, modified Harris Hip, and Super Simple Hip scores improved significantly (P < .001). This study shows promising mid-term results for the mini-open FAO procedure, alleviating pain and allowing return to activity in young patients with femoroacetabular impingement. Further studies need to be performed to determine risk factors for failure of FAO and ideal patient selection.