Management of Periprosthetic Joint Infection: The More We Learn, the Less We Know.

BACKGROUND: Despite the tremendous and long-standing success of total hip arthroplasty and total knee arthroplasty as treatments for end-stage arthritis, periprosthetic joint infection (PJI) remains a rare but feared complication of these procedures. METHODS: This review highlights some of the difficulties inherent to studying PJI. These include the difficulty in powering studies to capture this relatively uncommon complication, as well as the heterogeneity in clinical presentation and manifestations associated with the diagnosis and treatment of PJI. CONCLUSION: We suggest an algorithm for moving forward with new research in an attempt to answer the challenging questions facing the arthroplasty community regarding PJI.

Fractional flow reserve versus angiography in guiding management to optimize outcomes in non-ST-elevation myocardial infarction (FAMOUS-NSTEMI): rationale and design of a randomized controlled clinical trial.

BACKGROUND: In patients with acute non-ST-elevation myocardial infarction (NSTEMI), coronary arteriography is usually recommended; but visual interpretation of the angiogram is subjective. We hypothesized that functional assessment of coronary stenosis severity with a pressure-sensitive guide wire (fractional flow reserve [FFR]) would have additive diagnostic, clinical, and health economic utility as compared with angiography-guided standard care. METHODS AND DESIGN: A prospective multicenter parallel-group 1:1 randomized controlled superiority trial in 350 NSTEMI patients with ≥1 coronary stenosis ≥30% severity (threshold for FFR measurement) will be conducted. Patients will be randomized immediately after coronary angiography to the FFR-guided group or angiography-guided group. All patients will then undergo FFR measurement in all vessels with a coronary stenosis ≥30% severity including culprit and nonculprit lesions. Fractional flow reserve will be disclosed to guide treatment in the FFR-guided group but not disclosed in the "angiography-guided" group. In the FFR-guided group, an FFR ≤0.80 will be an indication for revascularization by percutaneous coronary intervention or coronary artery bypass surgery, as appropriate. The primary outcome is the between-group difference in the proportion of patients allocated to medical management only compared with revascularization. Secondary outcomes include the occurrence of cardiac death or hospitalization for myocardial infarction or heart failure, quality of life, and health care costs. The minimum and average follow-up periods for the primary analysis are 6 and 18 months, respectively. CONCLUSIONS: Our developmental clinical trial will address the feasibility of FFR measurement in NSTEMI and the influence of FFR disclosure on treatment decisions and health and economic outcomes.

Patient-specific instruments for total knee arthroplasty.

The use of patient-specific instruments for total knee arthroplasty shifts computer navigation for bone landmark registration and implant positioning from the intraoperative to the preoperative setting. Each system requires preoperative MRI or CT, with specifications determined by the instrument manufacturer. The marketed advantages of patient-specific instruments include greater accuracy in coronal alignment with fewer outliers, no need for instrumentation of the intramedullary canal, reduced surgical time, lower hospital costs, and improved clinical outcomes. The few published results of these instruments suggest minimal gains obtained in hospital logistics variables and minimal evidence of improvement in either alignment or patient outcomes. Disadvantages of patient-specific instruments include increased costs for imaging and instrument fabrication as well as increased preoperative time required for surgical planning and reviewing the instrument plans, and the learning curve for the surgeon to work with the engineers and use these instruments intraoperatively. It is also necessary to have a set of standard instruments available in case the patient-specific instruments do not work properly. Additional data are required before deciding whether these instruments should be recommended.

Can tantalum cones provide fixation in complex revision knee arthroplasty?

BACKGROUND: The best method for managing large bone defects during revision knee arthroplasty is unknown. Metaphyseal fixation using porous tantalum cones has been proposed for severe bone loss. Whether this approach achieves osseointegration with low complication rates is unclear. QUESTIONS/PURPOSES: We therefore asked: (1) What is the risk of infection in revision knee arthroplasty with large bone defects reconstructed with porous tantalum cones? (2) What is the rate of osseointegration with these cones? (3) What is the rate of loosening and reoperation? (4) Is knee function restored? METHODS: We retrospectively reviewed 27 patients who had 33 tantalum cones (nine femoral, 24 tibial) implanted during 27 revision knee arthroplasties. There were 14 women and 13 men with a mean age of 64.6 years. Preoperative diagnosis was reimplantation for infection in 13 knees, aseptic loosening in 10, and wear-osteolysis in four. Patients were evaluated clinically and radiographically using the score systems of the Knee Society and followed for a minimum of 2 years (mean, 3.3 years; range, 2-5.7 years). RESULTS: One knee with two cones was removed for infection. All but one cone showed osseointegration. One knee was revised for femoral cone and component loosening. There was one reoperation for femoral shaft fracture and one for superficial dehiscence. The mean Knee Society pain score improved from 40 points preoperatively to 79 points postoperatively. The mean function score improved from 19 points to 47 points. CONCLUSIONS: Our observations suggest metaphyseal fixation with tantalum cones can be achieved. Longer-term followup is required to determine whether the fixation is durable.

Aspirin to target arterial events in chronic kidney disease (ATTACK): study protocol for a multicentre, prospective, randomised, open-label, blinded endpoint, parallel group trial of low-dose aspirin vs. standard care for the primary prevention of cardiovascular disease in people with chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is a very common long-term condition and powerful risk factor for cardiovascular disease (CVD). Low-dose aspirin is of proven benefit in the secondary prevention of myocardial infarction (MI) and stroke in people with pre-existing CVD. However, in people without CVD, the rates of MI and stroke are much lower, and the benefits of aspirin in the primary prevention of CVD are largely balanced by an increased risk of bleeding. People with CKD are at greatly increased risk of CVD and so the absolute benefits of aspirin are likely to be greater than in lower-risk groups, even if the relative benefits are the same. Post hoc evidence suggests the relative benefits may be greater in the CKD population but the risk of bleeding may also be higher. A definitive study of aspirin for primary prevention in this high-risk group, recommended by the National Institute for Health and Care Excellence (NICE) in 2014, has never been conducted. The question has global significance given the rising burden of CKD worldwide and the low cost of aspirin. METHODS: ATTACK is a pragmatic multicentre, prospective, randomised, open-label, blinded endpoint adjudication superiority trial of aspirin 75 mg daily vs. standard care for the primary prevention of CVD in 25,210 people aged 18 years and over with CKD recruited from UK Primary Care. Participants aged 18 years and over with CKD (GFR category G1-G4) will be identified in Primary Care and followed up using routinely collected data and annual questionnaires for an average of 5 years. The primary outcome is the time to first major vascular event (composite of non-fatal MI, non-fatal stroke and cardiovascular death [excluding confirmed intracranial haemorrhage and other fatal cardiovascular haemorrhage]). Deaths from other causes (including fatal bleeding) will be treated as competing events. The study will continue until 1827 major vascular events have occurred. The principal safety outcome is major intracranial and extracranial bleeding; this is hypothesised to be increased in those randomised to take aspirin. The key consideration is then whether and to what extent the benefits of aspirin from the expected reduction in CVD events exceed the risks of major bleeding. DISCUSSION: This will be the first definitive trial of aspirin for primary CVD prevention in CKD patients. The research will be of great interest to clinicians, guideline groups and policy-makers, in the UK and globally, particularly given the high and rising prevalence of CKD that is driven by population ageing and epidemics of obesity and diabetes. The low cost of aspirin means that a positive result would be of relevance to low- and middle-income countries and the impact in the developed world less diluted by any inequalities in health care access. TRIAL REGISTRATION: ISRCTN: ISRCTN40920200 . EudraCT: 2018-000644-26 . CLINICALTRIALS: gov: NCT03796156.

Randomized trial of simple versus complex drug-eluting stenting for bifurcation lesions: the British Bifurcation Coronary Study: old, new, and evolving strategies.

BACKGROUND: The optimal strategy for treating coronary bifurcation lesions remains a subject of debate. With bare-metal stents, single-stent approaches appear to be superior to systematic 2-stent strategies. Drug-eluting stents, however, have low rates of restenosis and might offer improved outcomes with complex stenting techniques. METHODS AND RESULTS: Patients with significant coronary bifurcation lesions were randomized to either a simple or complex stenting strategy with drug-eluting stents. In the simple strategy, the main vessel was stented, followed by optional kissing balloon dilatation/T-stent. In the complex strategy, both vessels were systematically stented (culotte or crush techniques) with mandatory kissing balloon dilatation. Five hundred patients 64+/-10 years old were randomized; 77% were male. Eighty-two percent of lesions were true bifurcations (>50% narrowing in both vessels). In the simple group (n=250), 66 patients (26%) had kissing balloons in addition to main-vessel stenting, and 7 (3%) had T stenting. In the complex group (n=250), 89% of culotte (n=75) and 72% of crush (n=169) cases were completed successfully with final kissing balloon inflations. The primary end point (a composite at 9 months of death, myocardial infarction, and target-vessel failure) occurred in 8.0% of the simple group versus 15.2% of the complex group (hazard ratio 2.02, 95% confidence interval 1.17 to 3.47, P=0.009). Myocardial infarction occurred in 3.6% versus 11.2%, respectively (P=0.001), and in-hospital major adverse cardiovascular events occurred in 2.0% versus 8.0% (P=0.002), respectively. Procedure duration and x-ray dose favored the simple approach. CONCLUSIONS: When coronary bifurcation lesions are treated, a systematic 2-stent technique results in higher rates of in-hospital and 9-month major adverse cardiovascular events. This difference is largely driven by periprocedural myocardial infarction. Procedure duration is longer, and x-ray dose is higher. The provisional technique should remain the preferred strategy in the majority of cases. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00351260.

Pseudoaneurysm of the left ventricle following apical approach TAVI.

Symptomatic severe aortic stenosis carries a two year survival of only 50%. However many patients are unsuitable for conventional aortic valve replacement as they are considered too high risk due to significant co-morbidities. Transcatheter Aortic Valve Implantation (TAVI) offers a viable alternative for this high risk patient group, either by the femoral or apical route. This article reports a case of a pseudoaneurysm of the left ventricle following an apical approach TAVI in an elderly lady with severe aortic stenosis. To our knowledge pseduoaneuryms of the left ventricle have been reported infrequently in the literature and has yet to be established as a recognised complication of TAVI.

A comparison of perioperative outcomes in patients with and without rheumatoid arthritis after receiving a total shoulder replacement arthroplasty.

HYPOTHESIS: The long-term survival rate of total shoulder arthroplasty (TSA) is comparable to hip and knee arthroplasty. Although TSA is considered a safe and effective procedure with low complications in patients with osteoarthritis and rheumatoid arthritis (RA), data are lacking on perioperative complications. Complication rates and hospital disposition differences between patients with and without RA who underwent TSA were investigated. We hypothesized that RA patients would have poorer perioperative outcomes after TSA. MATERIALS AND METHODS: Data from the Nationwide Inpatient Sample was used to capture 25,398 patients between 1988 and 2005 who underwent TSA. Of these, 1,186 patients had a primary diagnosis of RA and were compared with 24,212 patients without RA. Analyses addressed perioperative complications and hospital disposition factors using bivariate and logistic regression models. RESULTS: Overall complication rates were exceptionally low in both groups. Hospital disposition factors were significantly different between the 2 groups. The RA cohort had shorter average lengths of stay, higher likelihood of routine discharge, and lower inflation-adjusted cost before and after adjustment for covariates. DISCUSSION: The occurrence of complications in the perioperative setting was less than 1% for both study groups in most variables investigated, and there were only minimal differences in perioperative complications between the groups. The significant differences in hospital disposition factors suggest that patients with RA may have less complex hospital stays and may be more comfortable being discharged under their own care. Recent studies describing the overall improvement in the management of patients with RA may also help explain these findings. CONCLUSIONS: The findings suggest that the perioperative complications of a total shoulder replacement for patients with and without RA are similar. Contrary to our expectations, TSA patients with RA had shorter and less costly hospital stays and were more likely to have routine discharge. Complications are likely more long-term in nature than detected in this study and require longer follow-up beyond perioperative periods for fruition.

A predictive model of shoulder instability after a first-time anterior shoulder dislocation.

INTRODUCTION: Management of a first-time anterior shoulder dislocation (FTASD) involves important clinical and policy decisions. Predictive disease modeling can improve the quality of information disseminated in treatment discussions. In this paper, we describe a general-purpose, publicly available model and illustrate its potential as a tool for management of a FTASD. METHODS: A Markov decision model of the natural history of a FTASD was constructed. Outcome probabilities and effectiveness were derived from the literature or estimated by expert opinion where necessary. Outcomes were the Western Ontario Shoulder Instability index (WOSI) and the probability of a patient experiencing recurrent instability, undergoing surgical stabilization, and having a stable shoulder at 10 years. The model was both internally and externally validated. Outcomes were examined for specific cases. RESULTS: The model was effectively externally validated against two studies, a Swedish prospective cohort of Hovelius et al and Botonni et al's military cohort. It can produce detailed outcome predictions for individuals; eg, an 18-year-old man has a 77% risk of dislocation in year 1 and a 32% chance of having a stable shoulder in 10 years. CONCLUSION: Detailed and specific information about prognosis is critical in the management of a FTASD. Disease modeling lends itself well to these needs and allows improved shared decision-making. Our model was externally validated and can predict specific outcomes. As a publically available resource, it will allow physicians to accurately predict the expected outcome of treatment based on covariates, patient demographics, and their own surgical success rates.

Citrobacter koseri as a cause of early periprosthetic infection after primary total hip arthroplasty.

Periprosthetic joint infection in the acute setting is usually caused by gram-positive species and remains a major problem facing total joint surgeons. We report a case of a 53-year-old male who presented with drainage 3 weeks after primary total hip arthroplasty. Citrobacter koseri was cultured from an infected hematoma in his deep tissues. Surgical treatment included irrigation and debridement with femoral head and liner exchange. He received a 6-week course of ertapenem and is currently asymptomatic. We present C. koseri as a rare cause of acute periprosthetic infection and offer an effective treatment protocol.

Pulsatile sterile abscess in the left breast following transapical transcatheter aortic valve implantation: a case report.

BACKGROUND: Over the last decade, transcatheter treatment of degenerative aortic valve stenosis has been established as an alternative to surgical aortic valve replacement. Late complications of transcatheter treatment of aortic stenosis (AS) are infrequent. CASE SUMMARY: We report an 87-year-old woman treated successfully with 23 mm Sapien 3 transapical transcatheter aortic valve implantation for severe AS. She presented 4 months later with a pulsatile mass in the left breast. After exclusion of other diagnoses, the mass was attributed to a sterile abscess communicating with the pericardial cavity due to post-operative chest infection and pleural effusion. Multimodality imaging helped to define the anatomy of the abscess and the mechanism of the pulsation. DISCUSSION: This is the first report of a pulsatile sterile abscess occurring as a complication of transapical aortic valve implantation. Multimodality imaging confirmed that the pulsation was due to extension of the abscess into the pericardial cavity, excluded direct communication with the left ventricle, and facilitated successful non-surgical management.

Report of the European Society of Cardiology Cardiovascular Round Table regulatory workshop update of the evaluation of new agents for the treatment of acute coronary syndrome: Executive summary.

Regulatory authorities interpret the results of randomized controlled trials according to published principles. The European Medicines Agency (EMA) is planning a revision of the 2000 and 2003 guidance documents on clinical investigation of new medicinal products for the treatment of acute coronary syndrome (ACS) to achieve consistency with current knowledge in the field. This manuscript summarizes the key output from a collaborative workshop, organized by the Cardiovascular Round Table and the European Affairs Committee of the European Society of Cardiology, involving clinicians, academic researchers, trialists, European and US regulators, and pharmaceutical industry researchers. Specific questions in four key areas were selected as priorities for changes in regulatory guidance: patient selection, endpoints, methodologic issues and issues related to the research for novel agents. Patients with ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) should be studied separately for therapies aimed at the specific pathophysiology of either condition, particularly for treatment of the acute phase, but can be studied together for other treatments, especially long-term therapy. Unstable angina patients should be excluded from acute phase ACS trials. In general, cardiovascular death and reinfarction are recommended for primary efficacy endpoints; other endpoints may be considered if specifically relevant for the therapy under study. New agents or interventions should be tested against a background of evidence-based therapy with expanded follow-up for safety assessment. In conclusion, new guidance documents for randomized controlled trials in ACS should consider changes regarding patient and endpoint selection and definitions, and trial designs. Specific requirements for the evaluation of novel pharmacological therapies need further clarification.

Rescue angioplasty after failed thrombolytic therapy for acute myocardial infarction.

BACKGROUND: The appropriate treatment for patients in whom reperfusion fails to occur after thrombolytic therapy for acute myocardial infarction remains unclear. There are few data comparing emergency percutaneous coronary intervention (rescue PCI) with conservative care in such patients, and none comparing rescue PCI with repeated thrombolysis. METHODS: We conducted a multicenter trial in the United Kingdom involving 427 patients with ST-segment elevation myocardial infarction in whom reperfusion failed to occur (less than 50 percent ST-segment resolution) within 90 minutes after thrombolytic treatment. The patients were randomly assigned to repeated thrombolysis (142 patients), conservative treatment (141 patients), or rescue PCI (144 patients). The primary end point was a composite of death, reinfarction, stroke, or severe heart failure within six months. RESULTS: The rate of event-free survival among patients treated with rescue PCI was 84.6 percent, as compared with 70.1 percent among those receiving conservative therapy and 68.7 percent among those undergoing repeated thrombolysis (overall P=0.004). The adjusted hazard ratio for the occurrence of the primary end point for repeated thrombolysis versus conservative therapy was 1.09 (95 percent confidence interval, 0.71 to 1.67; P=0.69), as compared with adjusted hazard ratios of 0.43 (95 percent confidence interval, 0.26 to 0.72; P=0.001) for rescue PCI versus repeated thrombolysis and 0.47 (95 percent confidence interval, 0.28 to 0.79; P=0.004) for rescue PCI versus conservative therapy. There were no significant differences in mortality from all causes. Nonfatal bleeding, mostly at the sheath-insertion site, was more common with rescue PCI. At six months, 86.2 percent of the rescue-PCI group were free from revascularization, as compared with 77.6 percent of the conservative-therapy group and 74.4 percent of the repeated-thrombolysis group (overall P=0.05). CONCLUSIONS: Event-free survival after failed thrombolytic therapy was significantly higher with rescue PCI than with repeated thrombolysis or conservative treatment. Rescue PCI should be considered for patients in whom reperfusion fails to occur after thrombolytic therapy.

Adoptively transferred human lung tumor specific cytotoxic T cells can control autologous tumor growth and shape tumor phenotype in a SCID mouse xenograft model.

BACKGROUND: The anti-tumor efficacy of human immune effector cells, such as cytolytic T lymphocytes (CTLs), has been difficult to study in lung cancer patients in the clinical setting. Improved experimental models for the study of lung tumor-immune cell interaction as well as for evaluating the efficacy of adoptive transfer of immune effector cells are needed. METHODS: To address questions related to the in vivo interaction of human lung tumor cells and immune effector cells, we obtained an HLA class I (+) lung tumor cell line from a fresh surgical specimen, and using the infiltrating immune cells, isolated and characterized tumor antigen-specific, CD8(+) CTLs. We then established a SCID mouse-human tumor xenograft model with the tumor cell line and used it to study the function of the autologous CTLs provided via adoptive transfer. RESULTS: The tumor antigen specific CTLs isolated from the tumor were found to have an activated memory phenotype and able to kill tumor cells in an antigen specific manner in vitro. Additionally, the tumor antigen-specific CTLs were fully capable of homing to and killing autologous tumors in vivo, and expressing IFN-gamma, each in an antigen-dependent manner. A single injection of these CTLs was able to provide significant but temporary control of the growth of autologous tumors in vivo without the need for IL-2. The timing of injection of CTLs played an essential role in the outcome of tumor growth control. Moreover, immunohistochemical analysis of surviving tumor cells following CTL treatment indicated that the surviving tumor cells expressed reduced MHC class I antigens on their surface. CONCLUSION: These studies confirm and extend previous studies and provide additional information regarding the characteristics of CTLs which can be found within a patient's tumor. Moreover, the in vivo model described here provides a unique window for observing events that may also occur in patients undergoing adoptive cellular immunotherapy as effector cells seek and destroy areas of tumor growth and for testing strategies to improve clinical effectiveness.

Impact of call-to-balloon time on 30-day mortality in contemporary practice.

OBJECTIVE: Studies reporting an association between treatment delay and outcome for patients with ST segment elevation myocardial infarction (STEMI) have generally not included patients treated by a primary percutaneous coronary intervention (PPCI) service that systematically delivers reperfusion therapy to all eligible patients. We set out to determine the association of call-to-balloon (CTB) time with 30-day mortality after PPCI in a contemporary series of patients treated within a national reperfusion service. METHODS: We analysed data on 16 907 consecutive patients with STEMI treated by PPCI in England and Wales in 2011 with CTB time of ≤6 hours. RESULTS: The median CTB and door-to-balloon times were 111 and 41 min, respectively, with 80.9% of patients treated within 150 min of the call for help. An out-of-hours call time (58.2% of patients) was associated with a 10 min increase in CTB time, whereas inter-hospital transfer for PPCI (18.5% of patients) was associated with a 49 min increase in CTB time. CTB time was independently associated with 30-day mortality (p<0.0001) with a HR of 1.95 (95% CI 1.54 to 2.47) for a CTB time of >180-240 min compared with ≤90 min. The relationship between CTB time and 30-day mortality was influenced by patient risk profile with a greater absolute impact of increasing CTB time on mortality in high-risk patients. CONCLUSION: CTB time is a useful metric to assess the overall performance of a PPCI service. Delays to reperfusion remain important even in the era of organised national PPCI services with rapid treatment times and efforts should continue to minimise treatment delays.

Health-related quality of life after interventional or conservative strategy in patients with unstable angina or non-ST-segment elevation myocardial infarction: one-year results of the third Randomized Intervention Trial of unstable Angina (RITA-3).

OBJECTIVES: We sought to compare the effects of an early interventional strategy (IS) versus a conservative strategy (CS) on health-related quality of life (HRQOL) in patients with non-ST-segment elevation acute coronary syndromes (ACS). BACKGROUND: The third Randomized Intervention Trial of unstable Angina (RITA-3) evaluated early IS (n = 895) versus CS (n = 915). We report one-year results of the RITA-3 trial concerning HRQOL. METHODS: The patients' HRQOL was assessed with the Short Form-36 (SF-36) and Seattle Angina Questionnaire (SAQ) at four-month and one-year follow-up, and the EuroQOL Visual Analogue Scale (EQ-VAS) and EuroQOL 5-Dimensional Classification (EQ-5D) also measured at baseline. Analysis was performed using the two-sample t test and analysis of co-variance. RESULTS: Mean changes from baseline EQ-VAS scores were better for IS than for CS at four months (treatment difference of 3.0, p < 0.001) and one year (2.3, p < 0.01). The EQ-5D utility scores were also higher for IS at four months (treatment difference: 0.036, p < 0.01) and at one year (0.016, p = 0.20). For SF-36, IS scored significantly better at four months for physical function, physical role function, emotional role function, social function, vitality, and general health. The SAQ scores for exertional capacity, anginal stability and frequency, treatment satisfaction, and disease perception were better for IS at four months. These treatment differences were present but attenuated by one-year follow-up. Improvements in HRQOL for IS could be attributed to improvements in anginal symptoms. CONCLUSIONS: In patients with non-ST-segment elevation ACS, an early IS provides greater gains in HRQOL, as compared with CS, mainly due to improvements in angina grade.

Transcatheter Closure of Iatrogenic VSDs after Aortic Valve Replacement Surgery: 2 Case Reports and a Literature Review.

We report 2 new cases of transcatheter closure of iatrogenic ventricular septal defects after aortic valve replacement surgery, together with our finding, in a literature review, of 9 additional patients who had undergone this procedure from 2004 through 2013. In all 11 cases, transcatheter device closure was indicated for a substantial intracardiac shunt with symptomatic heart failure, and such a device was successfully deployed across the iatrogenic ventricular septal defect, with clinical improvement. Our review suggests that transcatheter closure of iatrogenic ventricular septal defects in patients with previous aortic valve replacement surgery is a safe and effective treatment option, providing anatomic defect closure and relief of symptoms in the short-to-medium term.

Fracture of an uncemented tantalum patellar component.

A 62-year-old man presented with the acute, atraumatic onset of pain 3 years after uncemented right total knee arthroplasty. He complained of new mechanical locking with the knee held in extension on examination and unable to flex the knee. On the plain radiographs, the patellar component peg was fractured and the plate was dislocated. The knee was immobilized, and revision to a cemented 3-peg component was performed. Fracture of a single-peg, tantalum-backed uncemented patellar component has not been described. Clinical suspicion for this should be given in the setting of acute locking. We recommend revision with a cemented polyethylene component.