Pseudotumor formation and serum ions after large head metal-on-metal stemmed total hip replacement. Risk factors, time course and revisions in 706 hips.

INTRODUCTION: The incidence and natural course of pseudotumors in metal-on-metal total hip arthroplasties is largely unknown. The objective of this study was to identify the true incidence and risk factors of pseudotumor formation in large head metal-on-metal total hip arthroplasties. MATERIALS AND METHODS: Incidence, time course and risk factors for pseudotumor formation were analysed after large femoral head MoM-THA. We defined a pseudotumor as a (semi-)solid or cystic peri-prosthetic soft-tissue mass with a diameter ≥2 cm that could not be attributed to infection, malignancy, bursa or scar tissue. All patients treated in our clinic with MoM-THA's were contacted. CT scan, metal ions and X-rays were obtained. Symptoms were recorded. RESULTS: After median follow-up of 3 years, 706 hips were screened in 626 patients. There were 228 pseudotumors (32.3 %) in 219 patients (35.0 %). Pseudotumor formation significantly increased after prolonged follow-up. Seventy-six hips (10.8 %) were revised in 73 patients (11.7 %), independent risk factors were identified. Best cutoff point for cobalt and chromium was 4 µg/l (68 and 77 nmol/l). CONCLUSIONS: This study confirms a high incidence of pseudotumors, dramatically increasing after prolonged follow-up. Risk factors for pseudotumors are of limited importance. Pain was the strongest predictor for pseudotumor presence; cobalt chromium and swelling were considered poor predictors. Cross-sectional imaging is the main screening tool during follow-up.

Ten-year follow-up on Dutch orthopaedic blood management (DATA III survey).

INTRODUCTION: Hip and knee arthroplasties are frequently complicated by the need for allogeneic blood transfusions. This survey was conducted to assess the current use of perioperative blood-saving measures and to compare it with prior results. MATERIALS AND METHODS: All departments of orthopaedic surgery at Dutch hospitals were sent a follow-up survey on perioperative blood-saving measures, and data were compared to the results of two surveys conducted 5 and 10 years earlier. RESULTS: The response rate was 94 out of 108 departments (87%). Most departments used erythropoietin prior to hip and knee replacements at the expense of preoperative autologous blood donation. The use of intraoperative autologous retransfusion in revision hip (56 vs. 54%) as well as revision knee arthroplasty (26 vs. 24%), was virtually unchanged. Postoperative autologous retransfusion is still used by the majority of departments after both primary arthroplasty and revision of hip (58/53%) and knee (65/61%). CONCLUSIONS: Currently, just as in 2007, the majority of Dutch orthopaedic departments uses erythropoietin, normothermia and postoperative autologous retransfusion with hip and knee arthroplasty. Intraoperative retransfusion is used mainly with hip revision arthroplasty. Other effective blood management modalities such as tranexamic acid have not been widely implemented.

A protocol for periprosthetic joint infections from the Northern Infection Network for Joint Arthroplasty (NINJA) in the Netherlands.

Periprosthetic joint infection (PJI) is a devastating complication of joint arthroplasty surgery. Treatment success depends on accurate diagnostics, adequate surgical experience and interdisciplinary consultation between orthopedic surgeons, plastic surgeons, infectious disease specialists and medical microbiologists. For this purpose, we initiated the Northern Infection Network for Joint Arthroplasty (NINJA) in the Netherlands in 2014. The establishment of a mutual diagnostic and treatment protocol for PJI in our region has enabled mutual understanding, has supported agreement on how to treat specific patients, and has led to clarity for smaller hospitals in our region for when to refer patients without jeopardizing important initial treatment locally. Furthermore, a mutual PJI patient database has enabled the improvement of our protocol, based on medicine-based evidence from our scientific data. In this paper we describe our NINJA protocol.Level of evidence: III.

Acetabular augmentation ring for recurrent dislocation of total hip arthroplasty: 60% stability rate after an average follow-up of 74 months.

Between 1988 and 2002, 47 patients (50 hips) were treated with acetabular shell augmentation arthroplasty for recurrent idiopathic dislocation of their total hip arthroplasty. Apparent causes for dislocation such as deep infection, component malposition, or polyethylene wear were excluded. Follow-up averaged 74 months (range, 12-178 months), and clinically, 30 hips (60%) did not present a subsequent dislocation at most recent follow-up. In five hips (10%), deep infection after the augmentation procedure necessitated removal of the entire prosthesis. In our opinion, this technique cannot be recommended as it has an unacceptable failure and high infection rate.

[How many steps does a doctor take in the hospital? No difference between internists and general surgeons, but a relationship with age and BMI]. / Hoeveel stappen zet een dokter in het ziekenhuis? Geen verschil tussen internisten en algemeen chirurgen, maar wel samenhang met leeftijd en BMI.

OBJECTIVE: To determine the number of steps taken during working days in the hospital by both internists and general surgeons and whether there is a difference between housemen, registrars and members of the staff. DESIGN: Comparative analysis. METHOD: A validated pedometer was used to count the number of steps taken by housemen, registrars and staff members in the departments of internal medicine and general surgery. The 2 groups of doctors comprised 131 subjects from 13 training hospitals. Possible factors likely to affect the number of steps, such as age, sex, weight and height, were recorded. RESULTS: The average number of steps taken per day was 5325 (range: 1105-10,250) and the average number per hour was 548 (range: 143-1105), with an average working day of 9.8 hours and 8.4 measured days. When corrected for age, sex and hierarchic status, no significant difference was observed between surgeons and internists (p = 0.097). There were also no differences within the hierarchic structure after correction (p = 0.936). Age and BMI seemed to be the most important factors predicting the number of steps in this population. Each additional year of age corresponded with an average decrease of 5 steps per hour on the job (p = 0.001), while each point rise in BMI (+1 kg/m) coincided with an average decrease of 20 steps per hour (p = 0.001). CONCLUSION: After correcting for confounding factors, no differences were observed in the number of steps taken in the hospital by general surgeons and internists. There was also no difference between hierarchic levels. Age and BMI were the most important variables that predicted the number of steps taken per hour in this research population.

[Deep venous thrombosis in an amputation stump]. / Diepveneuze trombose in een amputatiestomp.

A 34-year-old patient underwent a knee exarticulation amputation and developed symptoms of pain, redness and swelling of the stump in combination with a feeling of tightness in the chest. These symptoms were first attributed to muscle pain and exertion but further examination revealed deep venous thrombosis (DVT) of the stump and a pulmonary embolism for which he was treated with nadroparine and acenocoumarol. Shortly after treatment he could resume the use of the prosthesis. A DVT in the amputation stump is not frequently encountered, but is a serious complication that can, together with a pulmonary embolism, be life threatening. The literature mentions an incidence ranging from 0-12%. Physical examination is often not conclusive and further examination of the patient with duplex scanning is necessary, with a ventilation-perfusion scan if a pulmonary embolism is suspected. Patients with a lower extremity amputation have a higher risk of developing a DVT because of immobility and increased venous pooling in the residual limb. Symptoms of a red, swollen, warm and painful stump should trigger the physician to suspect a DVT.

[Thrombosis prophylaxis in orthopaedic surgery: considerations and uncertainties]. / Tromboseprofylaxe in de orthopedische chirurgie: inzichten en onzekerheden.

As it is not always possible to identify patients at extra risk of deep-venous thrombosis after major orthopaedic surgery, it is considered advisable to prescribe prophylactic treatment. Prophylaxis with a low dose of unfractionated heparin is more effective than no prophylaxis at all but less effective than low molecular-weight heparin or cumarine derivatives. Acetylsalicylic acid does not appear to have a place in the prevention of venous thromboemboli in elective total-hip and total-knee surgery. Its usefulness in the operative treatment of hip fractures has not been established. Starting prophylaxis postoperatively has not been shown to be less safe or effective than starting it preoperatively. The incidence of thrombosis is lower if the course of prophylactic treatment is lengthened to 4-6 weeks following arthroplasty of the hip or knee. The optimal period of medicinal prophylaxis has yet to be ascertained. Intermittent pneumatic compression appears to be effective after total-knee arthroplasty but in practice is difficult to deliver. Support stockings, a foot pump and rapid mobilization have little effect on the incidence of proximal deep-venous thrombosis. There are insufficient data regarding the use of thrombosis prophylaxis in day surgery.

The relation between titanium taper corrosion and cobalt-chromium bearing wear in large-head metal-on-metal total hip prostheses: a retrieval study.

BACKGROUND: Revision of hip implants due to adverse tissue reactions to metal debris has been associated with wear and corrosion of the metal-on-metal bearing articulation and the modular taper interface. Bearing articulation wear is increased in conditions of poor lubrication, which can also lead to high friction moments that may cause corrosion at the taper interface. This suggests that wear of the bearing and increased corrosion of the taper interface should occur simultaneously, which was investigated in this study. METHODS: Forty-three large-diameter cobalt-chromium bearings of the same design, implanted with a titanium stem using a titanium adapter, were retrieved at revision at a single center. Retrievals were grouped according to visual inspection of the female taper surface of the adapter into slight and severe corrosion groups. Volume change of bearing and taper surfaces was assessed using a coordinate measurement machine. Serum ion concentrations were determined for forty-three patients, whereas tissue metal concentration was measured for twelve patients. RESULTS: Severe taper corrosion was observed in 30% of the retrievals. Corrosion was observed either as material deposition or wear. The overall bearing wear rate was significantly higher in the group with severe taper corrosion than in the group with slight corrosion (7.2 ± 9.0 mm(3)/yr versus 3.1 ± 6.8 mm(3)/yr, respectively; p = 0.023) as were the serum cobalt (40.5 ± 44.9 µg/L versus 15.2 ± 23.9 µg/L, respectively; p = 0.024) and chromium ion concentrations (32.7 ± 32.7 µg/L versus 12.0 ± 15.1 µg/L, respectively; p = 0.019). Serum metal ion concentrations were more consistent indicators of wear than tissue metal concentrations. CONCLUSIONS: The increased bearing articulation wear and serum metal ion concentrations in cases with taper interface corrosion support the hypothesis that increased friction in the joint articulation is one of the factors responsible for simultaneous articulation and taper damage. However, independent taper or bearing damage was also observed, suggesting that other factors are involved in the process.

Venous thromboembolism during hip plaster cast immobilisation: review of the literature.

INTRODUCTION: There is a paucity of data regarding the risk of deep vein thrombosis during hip plaster cast immobilisation. The purpose of this article was to review the available evidence regarding the incidence of symptomatic venous thromboembolism (VTE) during hip plaster cast immobilisation. METHODS AND MATERIALS: All papers describing hip plaster cast immobilisation published in the English literature retrieved from PubMed, EMBASE and the Cochrane database were reviewed. Articles regarding children, hip dysplasia, congenital hip dislocation and Legg-Calvé-Perthes were excluded. A total of three papers were available for analysis. We also describe a case of pulmonary embolism during hip cast immobilisation. RESULTS: The overall incidence of symptomatic VTE during hip plaster cast immobilisation was 0% in 343 patients. The incidence of symptomatic VTE in hip cast brace was 2.3% (range 0-3%). DISCUSSION: Our systematic review of the literature showed a paucity of data regarding the incidence of VTE during hip plaster cast immobilisation. We describe the first case of pulmonary embolism during hip plaster cast immobilisation. We recommend that patients who are fitted with a hip plaster cast should be routinely screened for additional risk factors. When risk factors are present, patients should be considered for pharmacological thromboprophylaxis.

European multidisciplinary consensus statement on the use and monitoring of metal-on-metal bearings for total hip replacement and hip resurfacing.

INTRODUCTION: There is an ongoing debate about the optimal use of metal-on-metal (MoM) bearings in total hip replacement, since there are uncertainties about local and systemic adverse effects due to wear and corrosion of these bearings. Despite various national recommendations, efforts to achieve international harmonization of specific evidence-based recommendations for best practice are still lacking. HYPOTHESIS: An international consensus study group should be able to develop recommendations on the use and monitoring of MoM bearings, preferably at the European level, through a multidisciplinary approach, by integrating the perspectives of various stakeholders. MATERIALS AND METHODS: Twenty-one experts representing three stakeholder groups and eight countries participated in this European consensus study, which consisted of a consensus meeting, subsequent structured discussion, and consensus voting. RESULTS: The current statement defines first of all benefits, local and systemic risks, as well as uncertain issues related to MoM bearings. Safety assessment after implantation of MoM comprises all patients. A closer follow-up is recommended for large head MoM (≥36mm) and resurfacing. In these implants basic follow-up should consist of x-rays and metal ion measurement of cobalt in whole blood, performed with GF-AAS or ICP-MS. Clinical and/or radiographic abnormality as well as elevated ion levels needs additional imaging (ultrasound, CT-scan and/or MARS-MRI). Cobalt values less than 2 µg/L are probably devoid of clinical concern, the threshold value for clinical concern is expected to be within the range of 2-7 µg/L. DISCUSSION: This is the first multinational, interdisciplinary, and multiprofessional approach for developing a recommendation for the use and monitoring of MoM bearings in total hip replacement. The current recommendations are in partial agreement with previous statements regarding the extent of follow-up and imaging techniques. They however differ from previous communications regarding measurement of metal ions and especially the investigated medium, technique, and eventual threshold levels. LEVEL OF EVIDENCE: Level V, expert opinion/agreement conference.

High incidence of pseudotumour formation after large-diameter metal-on-metal total hip replacement: a prospective cohort study.

Peri-articular soft-tissue masses or 'pseudotumours' can occur after large-diameter metal-on-metal (MoM) resurfacing of the hip and conventional total hip replacement (THR). Our aim was to assess the incidence of pseudotumour formation and to identify risk factors for their formation in a prospective cohort study. A total of 119 patients who underwent 120 MoM THRs with large-diameter femoral heads between January 2005 and November 2007 were included in the study. Outcome scores, serum metal ion levels, radiographs and CT scans were obtained. Patients with symptoms or an identified pseudotumour were offered MRI and an ultrasound-guided biopsy. There were 108 patients (109 hips) eligible for evaluation by CT scan at a mean follow-up of 3.6 years (2.5 to 4.5); 42 patients (39%) were diagnosed with a pseudotumour. The hips of 13 patients (12%) were revised to a polyethylene acetabular component with small-diameter metal head. Patients with elevated serum metal ion levels had a four times increased risk of developing a pseudotumour. This study shows a substantially higher incidence of pseudotumour formation and subsequent revisions in patients with MoM THRs than previously reported. Because most revision cases were identified only after an intensive screening protocol, we recommend close monitoring of patients with MoM THR.

Comparing consensus guidelines on thromboprophylaxis in orthopedic surgery.

BACKGROUND: Different guidelines exist regarding the prevention of venous thromboembolism (VTE) in orthopedic surgery. OBJECTIVES: We aimed to compare (inter)national guidelines and analyse differences. METHODS: MEDLINE, the Cochrane Library and the internet were searched for guidelines on the prevention of VTE in orthopedic surgery. From these, we constructed a table comparing the different antithrombotic regimens during different orthopedic surgical and plaster cast treatments. RESULTS: Eleven guidelines from nine different countries and one international guideline were included. Few guidelines advise on thrombosis prophylaxis after plaster cast immobilization, (prolonged) arthroscopic surgery and isolated lower extremity trauma. Different opinions exist on the sole use of aspirin and mechanical prophylaxis and on the use of vitamin K antagonists after major hip and knee surgery. CONCLUSION: Based on the same available literature, different guidelines recommend different thromboprophylactic regimens. Ideally, the grade of recommendation should be based on the same level of evidence world-wide. Whilst there is no agreement on the relevance of different endpoints (e.g. asymptomatic DVT), it is very difficult to reach a consensus. Thromboprophylaxis guidelines should be reviewed and updated on a regular basis, because the evidence is evolving rapidly.

Death and venous thromboembolism after lower extremity amputation.

BACKGROUND: Lower extremity amputation is often performed in patients with end-stage vascular disease and is considered a high-risk procedure. Uncertainty exists about the rate of venous thromboembolism (VTE) in these patients. OBJECTIVES: To establish the incidence of death and venous thromboembolism after lower extremity amputation. METHODS: A prospective cohort study was performed to establish the incidences of death and VTE after lower extremity amputation, as detected by bilateral complete compression ultrasonography and ventilation-perfusion scintigraphy performed preoperatively and around day 14 postoperatively. Standard low-molecular-weight heparin thromboprophylaxis was given during the study period. A secondary outcome was the incidences of mortality and symptomatic venous thromboembolic complications during 8 weeks of postoperative follow-up. RESULTS: Forty-nine patients (53 amputations) were ultimately included in the intention-to-treat analysis. Five patients died within the 2-week period and an additional seven patients died during the 8 weeks clinical follow-up period. The total mortality rate therefore was 12 of 53 amputations [22.6%; 95% confidence interval (CI), 12.3-36.2%]. Six patients developed pulmonary embolisms (of which two were fatal) and one patient developed an asymptomatic contralateral distal deep venous thrombosis, resulting in a total VTE rate of 7 out of 53 amputations (13.2%; 95% CI, 5.47-25.3%). CONCLUSION: Lower extremity amputation is accompanied by a high mortality rate from sepsis, and respiratory and vascular causes. This study shows that VTE substantially contributes to the morbidity and mortality after lower extremity amputation despite adequate pharmacological thromboprophylaxis in this vulnerable population of patients.

Prevention of venous thromboembolism in patients with immobilization of the lower extremities: a meta-analysis of randomized controlled trials.

BACKGROUND: It is controversial whether the prevention of venous thromboembolism (VTE) in patients with lower-leg immobilization is necessary. OBJECTIVES: To assess the benefits and complications of pharmacological thromboprophylaxis, we performed a meta-analysis of all available randomized controlled trials on this subject. METHODS: We searched the MEDLINE and EMBASE electronic databases. We included English- and non-English language studies, we hand-searched journals, and we contacted manufacturers. We analyzed data from six randomized trials that investigated pharmacological prophylaxis for the prevention of VTE in 1456 patients with lower-leg immobilization in plaster cast or orthosis. Two reviewers independently assessed the trials for inclusion, extracted data, and assessed trial quality. Differences were resolved by consensus or arbitrage. RESULTS: The pooled estimate from all trials revealed a highly significant and clinically relevant reduction in asymptomatic events with low-molecular-weight heparin (LMWH) prophylaxis, compared to placebo or untreated control [risk ratio (RR) 0.58; 95% confidence interval (CI) 0.39-0.86; P = 0.006). The mean rate of VTE decreased from 17.1% to 9.6% with the use of LMWH. Subgroup analysis of methodologically superior trials (RR 0.68; CI 0.50-0.92; P = 0.01), proximal deep vein thrombosis (RR 0.28; CI 0.11-0.72; P = 0.008), tendon ruptures (RR 0.60; CI 0.38-0.97; P = 0.04), and fractures (RR 0.62; CI 0.45-0.86; P = 0.004) confirmed the robustness of the overall result. Frequency of bleeding did not differ between LMWH prophylaxis and control groups (RR 1.22; CI 0.61-2.46; P = 0.57). CONCLUSIONS: Our findings indicate that thromboprophylaxis with LMWH for immobilization of the lower extremities reduces the risk of VTE. This benefit is achieved with no excess bleeding.