Extreme Serum Titanium Concentration Induced by Acetabular Cup Failure: Unveiling a Unique Scenario of Titanium Alloy Debris Accumulation.

The majority of contemporary total hip arthroplasty (THA) implants are constructed from Ti alloys, which are generally believed to generate fewer adverse local tissue reactions (ALTRs) compared to CoCr alloys. This study presents a case of unusual primary THA failure where a substantial release of Ti alloy debris was observed. A 52-year-old active male underwent THA after post-traumatic aseptic necrosis of the femoral head in 2006. Seventeen years after the procedure, the patient presented with groin pain and a restricted range of motion. X-rays revealed the protrusion of the alumina ceramic head through the Ti6Al4V acetabular cup. Trace element analysis indicated significantly elevated levels of serum Ti, Al, and V. CT and MRI confirmed Ti alloy cup failure and a severe ALTR. During revision surgery, it was found that the worn-out ceramic head was in direct contact with the acetabular cup, having protruded through a central hole it had created over time. No acetabular liner was found. Histological analysis of his tissue samples showed wear-induced synovitis with areas of multinucleated foreign body giant cells and the accumulation of numerous metal particles but no acute inflammatory response. Six months after the revision THA, the patient has experienced favourable outcomes. This case provides an instructive illustration for studying the consequences of the substantial release of Ti alloy debris from orthopedic implants.

Bimodular femoral stems in primary total hip arthroplasty.

INTRODUCTION: This review critically examines the efficacy of dual-modular stems in primary total hip arthroplasty. Given the variability and non-comparability of certain femoral stem designs and stem-neck couplings, with some even being withdrawn from the market, this review offers an in-depth analysis of predominant implant performances. AREAS COVERED: The paper explores a brief historical summary related to dual-modular stems, including the complications associated with their use, diagnostic tools for evaluation, analysis of both recalled and currently available models, as well as alternative therapeutic options. This information is pertinent for both clinical and research domains. EXPERT OPINION: While dual-modular systems were initially touted to offer several advantages, the evidence substantiating these benefits has been ambiguous. Further, these systems introduce the risk of alternative complications. In specific cases involving patients with developmental hip dysplasia and certain proximal femoral deformities requiring complex reconstructions, dual-modular systems might be relevant. Nonetheless, the use of long interchangeable necks in patients with a body mass index above 30 kg/m2 is discouraged, and pairing a long varus-oriented neck with an extra-long femoral head should be avoided in all patients.

Total hip arthroplasty (THA) is a surgical procedure where the hip joint is replaced with an artificial one. This research paper dives deep into the use of dual-modular stems in THA. These stems were designed to provide surgeons with more control over certain aspects of the surgery, like leg length and hip stability. However, there's been some debate about their effectiveness and safety compared to single-modular stems. Going back in history, single-modular stems were the standard in THA procedures. These types of stems are simple in design, with the neck and stem made of one piece of metal. After inserting the stem in the femoral canal, a separate head or ball is attached intraoperatively thus completing the femoral part of the THA. In 1987, dual-modular stems, also called bimodular stems, were introduced. These had two parts and offered theoretical benefits such as better hip biomechanics, which could potentially lead to longer-lasting implants. But studies have shown mixed results, with some suggesting that dual-modular stems didn't offer clear benefits over the simpler, single-modular stems. This research review looks at both the history of dual-modular stems and the complications associated with them. Some of these stems even had to be recalled from the market. Diagnostic tools to evaluate these stems, the models available in the market, and alternative treatments are also discussed. The authors noted that while dual-modular systems were believed to offer benefits, the evidence isn't clear-cut. Moreover, these systems come with their own set of potential complications. One of the challenges faced with dual-modular stems is their potential for mechanical complications, which could complicate recovery after surgery. The use of cobalt-chromium necks in these titanium alloy stems introduced another challenge: enhanced corrosion at the point where the neck meets the stem. Despite these challenges, dual-modular stems may still be useful in specific cases, like when patients have severe hip dysplasia or deformities. But it's crucial to consider patient factors like weight, activity level, and hip offset when deciding to use these stems. The primary goal of using modular designs in THA is to better restore hip biomechanics, adjust leg length, and improve stability. Single-modular designs have shown consistent success, but dual-modular stems have faced challenges. For example, titanium alloy necks in these stems faced issues like fatigue breakage from mechanically assisted corrosion (tribocorrosion), which led to the introduction of cobalt-chromium necks. But even this solution had its problems, introducing a different type of corrosion when coupled with the original stem. As a result, these dual-modular stems should be used cautiously and in specific cases. In those instances, the newest designs, combined with titanium alloy necks, are recommended. However, surgeons are advised against using long necks in overweight patients, and certain design combinations should be avoided. There are alternatives to these stems, such as single-modular THA stems with different proximal shape and personalized implants. These alternatives are still being studied, and we need more data on their long-term performance. In conclusion, while THA has seen many advancements, it remains a field with potential for improvement. Modular designs, particularly dual-modular stems, have both benefits and challenges. The future of THA might focus more on personalized treatments, utilizing advances in imaging, materials, and manufacturing. We might soon see implants custom-made for individual patients, tailored to their anatomy and lifestyle. But before we get there, the current designs need improvement, and we need a better understanding of their failure modes. The goal is to continue innovating to provide the best outcomes for patients, keeping their safety and well-being at the forefront of all developments.

Dual-Modular Versus Single-Modular Stems for Primary Total Hip Arthroplasty: A Long-Term Survival Analysis.

Background and Objectives: Increased revision rate of dual-modular (DM) femoral stems in primary total hip arthroplasty (THA) because of modular-neck breakage and adverse local tissue reactions (ALTRs) to additional junction damage products is well established and some designs have been recalled from the market. However, some long-term studies of specific DM stems did not confirm the inferiority of these stems compared to standard single-modular (SM) stems, and a head-to-head comparison THA is missing. The objectives of this multicentre study were to determine the survivorship and complication rates of a common DM stem design compared to a similar SM stem. Materials and Methods: In a time frame from January 2012 to November 2015, a cohort of 807 patients (882 hips) consecutively underwent primary cementless THAs at two orthopaedic centres. 377 hips were treated with a Zweimüller-type DM stem THA system and 505 hips with a similar SM stem THA system, both including a modern press-fit acetabulum. Kaplan-Meier survivorship and complication rates were compared between both groups in a median follow-up of 9.0 years (maximum, 9.9 years). Results: The 9-year survivorship of the DM stem THA system (92.6%, 95% CI 89.9-95.3) was significantly lower than that of the SM stem THA system (97.0%, 95% CI 95.2-98.8). There were no differences in revision rates for septic loosening, dislocation, and periprosthetic fractures between the two groups. One ceramic inlay and one Ti-alloy modular neck breakage occurred in the DM stem THA system group, but the main reason for revision in this group was aseptic loosening of components. Conclusions: The survivorship of the DM stem THA system was lower than the similar SM stem THA system in a comparable clinical environment with long-term follow-up. Our results confirmed that no rationale for stem modularity exists in primary THAs.

Tissue Integration of Calcium Phosphate Compound after Subchondroplasty: 4-Year Follow-Up in a 76-Year-Old Female Patient.

Subchondroplasty is a new minimally invasive surgical technique developed to treat bone marrow lesions (BML) and early osteoarthritis (OA). During the procedure, engineered calcium phosphate compound (CPC) is injected. It is claimed by the manufacturer that during the healing process, the CPC is replaced with new bone. The purpose of this study was to verify the replacement of CPC with new bone after subchondroplasty for the first time in humans. A 76-year old woman was referred for resistant medial knee pain. Standing radiographs showed varus knee OA and magnetic resonance imaging (MRI) revealed BML. She was treated with subchondroplasty of medial femoral condyle. Excellent relief of pain was achieved after procedure. Afterwards, the pain worsened, the radiographs confirmed the OA progression and the patient was treated with a total knee arthroplasty (TKA) 4 years after primary procedure. The resected bone was examined histologically and with micro-computed tomography (CT). Histologically, bone trabeculae of subcortical bone were embedded in the amorphous mass. However, no signs of CPC resorption and/or bone replacement have been found with micro-CT. In short term, excellent pain relief could be expected after the subchondroplasty procedure. However, there was no replacement of CPC with bone and the technique probably did not influence the natural process of knee OA.

Total Knee Replacement with an Uncemented Porous Tantalum Tibia Component: A Failure Analysis.

Porous tantalum has been extensively used in orthopaedic surgery, including uncemented total knee arthroplasty (TKA). Favourable results were reported with earlier monobloc tibial components and the design evolved to modular implants. We aimed to analyse possible causes for extensive medial tibia bone loss, resulting in modular porous tantalum tibia baseplate fracture after primary TKA. Retrieved tissue samples were scanned with 3 MeV focused proton beam for Proton-Induced X-ray Emission (micro-PIXE) elemental analysis. Fractographic and microstructural analysis were performed by stereomicroscopy. A full 3D finite-element model was made for numerical analysis of stress-strain conditions of the tibial baseplate. Histological examination of tissue underneath the broken part of the tibial baseplate revealed dark-stained metal debris, which was confirmed by micro-PIXE to consist of tantalum and titanium. Fractographic analysis and tensile testing showed that the failure of the tibial baseplate fulfilled the criteria of a typical fatigue fracture. Microstructural analysis of the contact surface revealed signs of bone ingrowth in 22.5% of the surface only and was even less pronounced in the medial half of the tibial baseplate. Further studies are needed to confirm the responsibility of metal debris for an increased bone absorption leading to catastrophic tibial tray failure.

Revealing Inflammatory Indications Induced by Titanium Alloy Wear Debris in Periprosthetic Tissue by Label-Free Correlative High-Resolution Ion, Electron and Optical Microspectroscopy.

The metallic-associated adverse local tissue reactions (ALTR) and events accompanying worn-broken implant materials are still poorly understood on the subcellular and molecular level. Current immunohistochemical techniques lack spatial resolution and chemical sensitivity to investigate causal relations between material and biological response on submicron and even nanoscale. In our study, new insights of titanium alloy debris-tissue interaction were revealed by the implementation of label-free high-resolution correlative microscopy approaches. We have successfully characterized its chemical and biological impact on the periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis. We applied a combination of photon, electron and ion beam micro-spectroscopy techniques, including hybrid optical fluorescence and reflectance micro-spectroscopy, scanning electron microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS), helium ion microscopy (HIM) and micro-particle-induced X-ray emission (micro-PIXE). Micron-sized wear debris were found as the main cause of the tissue oxidative stress exhibited through lipopigments accumulation in the nearby lysosome. This may explain the indications of chronic inflammation from prior histologic examination. Furthermore, insights on extensive fretting and corrosion of the debris on nm scale and a quantitative measure of significant Al and V release into the tissue together with hydroxyapatite-like layer formation particularly bound to the regions with the highest Al content were revealed. The functional and structural information obtained at molecular and subcellular level contributes to a better understanding of the macroscopic inflammatory processes observed in the tissue level. The established label-free correlative microscopy approach can efficiently be adopted to study any other clinical cases related to ALTR.

Bilateral neck fracture in bimodular femoral stem after primary total hip arthroplasty: a case report.

BACKGROUND: Bi-modular stems were introduced in primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. Despite numerous reports on modular femoral neck fractures, some designs are still marketed worldwide. While the risk factors for the sudden failure are multifactorial and mostly known, the timing of this new THA complication is not predictable by any means. CASE PRESENTATION: In this report, the literature regarding one of the most popular bi-modular stems with specific neck-stem coupling (oval Morse taper) is reviewed and illustrated with a case of bilateral modular neck fracture in a patient with idiopathic aseptic necrosis of femoral heads treated with primary bi-modular THA. Because of bilateral modular femoral neck fracture, which occurred 3 years on the left side and 20 years after implantation on the right side, the patient required a total of 6 revisions and 208 days of hospitalized care. CONCLUSION: To our knowledge, this is the first report of bilateral modular neck fracture in a single patient. Even though the same surgeon performed both operations and used the same neck length and orientation, fractures occurred with a 17-year time difference after implantation. This shows that we cannot predict with certainty when a fracture might occur. Orthopaedic surgeons should use bi-modular stem designs for primary THA very cautiously.

Interchangeable neck failures of bi-modular femoral stems in primary total hip arthroplasty cannot be predicted from serum trace element analysis.

INTRODUCTION: Revision of a well-fixed stem due to unexpected modular neck fracture is a catastrophe for the patient and a challenge for the surgeon. This study aimed to test the possibility of predicting interchangeable neck fracture from serum levels of the stem/neck alloy-consisting metals. MATERIALS AND METHODS: Nineteen patients at high risk for interchangeable neck fracture were randomly selected out of a cohort of 680 bimodular stems made from Ti6Al4V alloy. Serum levels of titanium, aluminium and vanadium were determined. Nine age- and gender-matched patients were used as controls. RESULTS: Mean serum levels of Ti were 6.04 ± 2.52 µg/L, of Al 3.89 ± 1.68 µg/L and of V 0.07 ± 0.04 µg/L in the high-risk group, and 8.22 ± 4.74 µg/L, 4.99 ± 3.98 µg/L and 0.27 ± 0.44 µg/L in the low-risk group, respectively. No statistically significant differences were found between the groups. DISCUSSION: Interchangeable neck fracture of bimodular femoral stems cannot be predicted from serum trace element analysis.

Silver Fir (Abies alba L.) Polyphenolic Extract Shows Beneficial Influence on Chondrogenesis In Vitro under Normal and Inflammatory Conditions.

Several plant polyphenols have been shown to reduce osteoarthritis symptoms due to their antioxidant, anti-inflammatory and immunomodulatory properties. We investigated the effects of two different polyphenolic extracts (Belinal, Pycnogenol) and two different polyphenols (resveratrol, quercetin) on the chondrogenic potential of bone-derived mesenchymal stem/stromal cells (MSCs) from healthy donors and patients with osteoarthritis. Our main aim was to determine whether Belinal, a commercially available polyphenolic extract from silver fir (Abies alba L.) branches, has comparable chondrogenic potential with the other tested extract and the polyphenols under inflammatory and non-inflammatory conditions. In our study, Belinal promoted significantly greater chondrogenesis compared to the untreated (p = 0.0289) and resveratrol-treated (p = 0.0468) MSCs from patients with hip osteoarthritis under non-inflammatory conditions. Under inflammatory conditions, chondrogenesis was significantly enhanced for MSCs treated with Belinal compared to the control (p = 0.0483). The other extract and the polyphenols did not show any significant effects on chondrogenesis under non-inflammatory or inflammatory conditions. None of the tested extracts and polyphenols showed significant effects on chondrogenesis in healthy donors, under either non-inflammatory or inflammatory conditions. Our data show that Belinal can boost the chondrogenesis of MSCs derived from patients with osteoarthritis, under both non-inflammatory and inflammatory conditions.

Modular femoral neck failure after revision of a total hip arthroplasty: a finite element analysis.

The authors report on a case of modular femoral neck fracture which appeared 21 months after revision of acetabular component. The revision surgery was performed 8 years after the primary total hip arthroplasty due to aseptic loosening of the acetabular component. During acetabular revision, the primary implanted short (S, - 3.5 mm) femoral head was also exchanged with extra-long (XL, + 7.0 mm) femoral head fitting the modular femoral neck with a longer lever arm. Numerical analysis has shown that this has resulted in a 19.9% increase in tensile stress at the neck-stem coupling during normal walking cycle. This could result in microcrack initiation and propagation and finally lead to modular neck failure of the otherwise well-fixed stem. Surgeons should avoid excessive loading of the exchangeable neck (dual-modular) femoral stem designs as the stem-neck couplings are subject to corrosion and are not as reliable as monoblock stems.

The best cited articles of the European Journal of Orthopaedic Surgery and Traumatology (EJOST): a bibliometric analysis.

European Journal of Orthopaedic Surgery and Traumatology (EJOST) was founded in 1991. It was initially named as Orthopédie-Traumatologie, and since then it is dedicated in sharing knowledge and new evidence in the field of orthopaedics. Within 28 volumes and 157 issues, it has published 3218 scientific articles. In the early years of its distribution, published articles were in French, while the last two decades EJOST only hosts English articles between its pages. By the very beginning of its launch, it has been publishing high-quality research articles in all orthopaedic subspecialties and has gradually become one of the leading journals in its specific subject area. The aim of this study was to identify, analyse and categorize the most frequently cited articles, published by EJOST since its launch.

Why do some titanium-alloy total hip arthroplasty modular necks fail?

BACKGROUND: Increased modularity in total hip arthroplasty (THA) through extra junction between the neck and the femoral stem is gaining popularity among orthopaedic community. However, the advantage of the additional junction is shadowed by an increased risk of mechanical failure. The aim of this study was to describe the exact mechanism of fracture of the modular femoral neck in an uncemented stem. METHODS: Clinical, metallurgical, and mechanical analysis including finite-element modelling and elemental-sensitive tissue analysis with the micro-PIXE method was performed on two patients treated with fully modular primary THA made from Titanium alloy of the same oval taper-cone design. In patient A revision was performed 7.8 years after the unilateral primary procedure because of modular femoral neck fracture, while patient B was left-side revised 15 years after the bilateral primary procedure because of aseptic loosening of the femoral stem. RESULTS: Body weight was 30% higher and the arm of implanted modular femoral neck was 51% longer in patient A compared to patient B. Therefore, the stress ratio on the modular femoral neck of patient A was calculated to be 2.45 times higher than in patient B, preventing cold welding and producing taper damage and degradation at the neck-stem junction. Large clusters of metallic debris containing Titanium and Vanadium from the alloy were present in the periprosthetic soft tissues of patient A. CONCLUSIONS: Patients with higher body mass index treated with fully modular Ti-alloy THA may be at increased risk to experience catastrophic failure of the device. Orthopaedic surgeons should avoid using long necks whenever possible, as these are especially prone to develop a vicious circle starting with the fretting process and crevice corrosion at the taper-cone connection, leading to crack initiation and crack propagation, accelerated by the increased vulnerability of the Ti-alloy in biologic media, ultimately ending as fracture at the typical site. Serum Ti concentration may represent a rough estimation of taper degradation and patients with elevated levels should be warned and followed accordingly.

Total hip arthroplasty-related osteogenic osteosarcoma: case report and review of the literature.

BACKGROUND: Orthopedic implant-related sarcoma is an exceedingly rare, but a known complication of total hip arthroplasty (THA). CASE PRESENTATION: The authors describe clinical and radiologic features, histologic appearance, and treatment of osteogenic osteosarcoma located in the proximal femoral diaphysis associated with an unstable femoral prosthesis following THA in a 65-year-old male patient. The patient with HLA-B27 positive ankylosing spondylitis underwent arthroplasty 15 years ago. CONCLUSIONS: The neoplastic process may be considered as an extraordinary complication of THA and might just be coincidental or the result of some derangement of the healing process in host tissue with no definitely proven hypothesis that the implants or their by-products are carcinogenic. The soluble chemical substances from the implanted prosthetic material are, at least in animals, suspected to play a vital role in the pathogenesis of the neoplastic transformation of the bone tissue. The presented case shall alert orthopedic surgeons to clinical, radiologic, and macroscopic similarities between a malignant tumor and benign lesions caused by wear debris at THA sites. At the examination of plane X-rays of patients with THA loosening, the differential diagnosis should always include osteogenic sarcoma, as well. To our knowledge, there have been only nine cases of THA-related osteogenic osteosarcomas described in the English-language literature.

Results of total hip arthroplasty using a bionic hip stem.

PURPOSE: The trabecular-orientated bionic hip stem was designed to mimic the natural force transmission through the femur in total hip arthroplasty, resulting in supposedly longer prosthesis survivability. The aim of this study was to compare the second-generation bionic hip stem to a standard uncemented hip stem. METHODS: A group of 18 patients (21 hips) who underwent total hip arthroplasty with a bionic stem (bionic group) was compared with a historic group of 12 patients (12 hips) treated with standard anatomic hip stem (control group). During the first year after the procedure, the densitometric measurements of the bone around the prosthesis were taken. Radiographic and clinical assessments were additionally performed preoperatively and at the three month, six month, one year and three year follow-ups in the bionic group. RESULTS: In the bionic group, one patient was revised for aseptic loosening and 16 patients (19 hips) were available to the final follow-up. A significant decrease of bone mineral density was found in Gruen zones 3, 4 and 5 in the bionic group, and in zone 7 in both groups. The bionic group had a significantly higher bone mineral density in Gruen zone 1 at the one year follow-up. At the final follow-up, all prostheses were radiologically stable in both groups. CONCLUSIONS: Provided that a good implant position is achieved, comparable short-term results can be obtained using a bionic stem. Still, a decrease of bone mineral density in Gruen zone 7 occurred in both groups. Further studies are required to determine survivability of the bionic stem.

Porous tantalum shells and augments for acetabular cup revisions.

PURPOSE: The purpose of this study was to evaluate early functional results of revision hip arthroplasty with pelvic bone loss revised with porous tantalum (PT) acetabular components. METHODS: Twenty-five consecutive patients (25 hips) with loose acetabular components after total hip arthroplasty with a minimum of Paprosky IIa pelvic bone loss treated with PT cups with and without modular augments were retrospectively reviewed. Clinical outcomes were assessed using Harris hip score, and Western Ontario and McMaster Universities scores. Mean follow-up was 20.5 months and no patient was lost during follow-up. RESULTS: The average Harris hip score, and Western Ontario and McMaster Universities scores improved from 40 and 36 preoperatively to 79 and 73 postoperatively, respectively. No statistically significant differences in functional outcome scores were found between the group with moderate (Paprosky IIa, b) and severe (Paprosky IIc or more) acetabular bone loss. At the most recent radiographic evaluation, 24 cups demonstrated no lucent lines and 1 cup had lucent lines but remained well fixed. One cup was revised for traumatic dislocation but was found well fixed at open reduction. There were no septic or aseptic failures in this series. CONCLUSION: While awaiting longer-term follow-up studies, trabecular metal components show sufficient primary stability and appear suitable for revision hip arthroplasty with acetabular bone loss.

Long term results of operative treatment of knee osteochondritis dissecans.

PURPOSE: This retrospective study was designed to evaluate the hypothesis that open reduction internal fixation (ORIF) of an unstable osteochondritis dissecans (OCD) lesion results in a high percentage of acceptable outcomes at long-term follow-up. METHODS: Eight patients who had been treated with ORIF for unstable knee OCD lesions were identified. Long-term outcomes were assessed with a Subjective Knee Evaluation Form and Knee Examination Form of the International Knee Documentation Committee (IKDC 2000) and an OCD specific Hughston rating scale. RESULTS: All lesions were healed and stable to arthroscopic probing at 3 months. At the average follow-up of 14.8 years (range 12-21 years), the mean IKDC subjective score was 80.9. In IKDC examination form, six patients reached group A (normal) and two patients reached groups B (near normal) and C (abnormal), respectively. According to Hughston criteria, three patients were rated excellent, three good, one fair, and one poor. CONCLUSIONS: We recommend aggressive attempts to preserve articular cartilage in OCD.

Dynamic versus rigid stabilization for the treatment of disc degeneration in the lumbar spine.

STUDY DESIGN: Retrospective cohort study. CLINICAL QUESTION: This study aimed to describe the outcome of stabilization surgery with dynamic instrumentation for degenerative disc disease. The results were compared with age- and gender-matched peers treated with traditional fusion with rigid instrumentation. If necessary, additional nerve elements decompression was undertaken in both groups. METHODS: This study analyzed the success rates of 25 patients aged 47.4 years (mean 95% confidence interval: 43.1-51.7) treated with stabilization of the involved vertebral dynamic unit(s) with either dynamic or rigid instrumentation with or without additional decompression. Clinical outcome was assessed with Oswestry disability index (ODI) and visual analogue scale (VAS) for back pain, leg pain, and activity level. Satisfaction outcome was measured with Stauffer and Coventry overall satisfaction criteria and VAS for satisfaction. Health-related quality of life was estimated with Short Form-36 (SF-36) questionnaires. Fusion rate and adjacent level(s) was checked with x-ray. Complications recorded in patients' files were evaluated and revision surgeries were stated as treatment failures. RESULTS: At the 4-year follow-up (range, 2-5 years) significant improvement was noted on some subjective parameters in both groups. No statistical differences were seen between the groups at final follow-up. Five patients (42%) in the rigid group and two patients (20%) in the dynamic group were rated good or excellent according to the overall Stauffer and Coventry satisfaction criteria. Radiologically, seven patients (58%) in the rigid group were undoubtedly fused and all the involved discs in the dynamic group continued to degenerate. Adjacent segments showed loss of disc height in both groups but only loss of upper adjacent discs in the rigid group was statistically significant. Two patients in the dynamic group and one patient in the rigid group required reoperation because of the pedicle screw misplacement. CONCLUSION: The results of this study indicate no significant difference between dynamic and rigid stabilization of the lumbar spine for patients with degenerative disc disease (DDD). However, the study is underpowered and further studies on larger and homogeneous group of patients should be undertaken. [Table: see text].

Acute gouty arthritis in a patient after total knee arthroplasty.

Symptomatic gout in an artificial joint is exceptionally rare. We present a 68-year-old male patient who developed progressive knee pain and swelling one year after the cemented total arthroplasty of his left knee. The diagnosis was confirmed by crystal identification in the synovial fluid. Beside thorough workout to rule out infection in a painful and inflamed prosthetic knee, specific history of gout should be sought and fluid aspirate examined cytologically and under polarised light for crystal arthropathy.