Mid-term results of cemented hip arthroplasties through the direct anterior approach in the lateral decubitus position: a retrospective cohort study.

BACKGROUND: Reports show a high complication rate when starting with the Direct Anterior Approach (DAA) in a supine position for hip arthroplasty. The DAA with the patient in lateral decubitus position may avoid this problem because it supposedly provides better visibility, especially on the femoral side. However, this approach did show a rather high complication rate during the adoption of the approach at 1 year follow up in our previous report. We were interested what the overall 7 year survival estimate would be and whether improvement could be seen with growing experience. METHODS: A cohort of patients undergoing total hip arthroplasty right from the start of applying the DAA in lateral decubitus position was analysed. RESULTS: In total 175 hip prostheses (162 patients) were evaluated. The 7-year survival estimate was 95.1%, 95 CI: 91.8-98.4%. In 6 of 8 revisions there was aseptic loosening of the stem. By dividing the cohort into 3 consecutive groups in time we did not see a significantly improving revision rate. CONCLUSIONS: In our experience, the adoption of the direct anterior approach in lateral decubitus position caused a relatively low 7-year survival estimate without an apparent decrease with growing experience, however given the low number of cases further research is needed to investigate the long-term risk of adopting a new approach.

Low revision rate throughout the adoption of the direct superior approach in primary total hip arthroplasty: an analysis based on 1551 total hip arthroplasties from the Dutch Arthroplasty Register.

BACKGROUND: Recently, surgeons introduced a minimally invasive modification on the classic posterolateral approach (PLA) in total hip arthroplasty (THA): the direct superior approach (DSA). We investigated the association between surgeon's experience and the risk of early revision of the DSA in primary THA, using data from the Dutch Arthroplasty Register (LROI). METHODS: We retrieved all primary THAs performed using the DSA in 4 hospitals between 2016 and 2022 (n = 1551). Procedures were sorted in 5 groups using the date of operation and number of previous procedures per surgeon: 1-25; 26-50; 51-75; 76-100; >100. Subsequently, data from different surgeons were pooled together and the risk of revision was calculated via a multilevel time-to-event analysis. RESULTS: The overall revision rate was 1.5% after a mean follow-up of 2 years. Patients from the 1-25 group had comparable risks of revision compared to patients in the >100 group (hazard ratio [HR] 1.0 [CI, 0.3-3.2]). The risk for patients in groups 26-50, 51-75 and 75-100 was also not statistically different from the >100 group (resp. HR 1.5 [CI, 0.5-5.0], 1.8 [CI, 0.5-6.4] and 0.5 [CI, 0.1-4.0]). Main reasons of revision were dislocation (0.5%) and infection (0.4%). CONCLUSIONS: We did not identify an association between the surgeon's experience and the early risk of revision for the DSA in primary THA in the Netherlands. The DSA seems safe in the early adoption phases with a low risk of revision due to dislocation and revision for all other causes.

Comparison of osteolysis around 3 different cement restrictors in total hip arthroplasty.

BACKGROUND AND AIM: Several studies reported osteolysis around polyethylene glycol/polybutylene terephthalate (PEG/PBT) based femoral cement restrictors. Our goal was to evaluate and compare osteolysis around 3 different plug designs: the slow biodegradable PEG/PBT cement restrictor; the fast biodegradable gelatin cement restrictor; and the non-biodegradable polyethylene plug. PATIENTS AND METHODS: In a retrospective multicentre cohort study chart data were extracted of patients who received a total hip arthroplasty between 2008 and 2012. A total of 961 hips were included. Cortical ratio between inner and outer cortices at the centre of the plug was measured on routine postoperative follow-up moments. Median follow up of all 3 hospitals was 3.5 years (1.4-7.3). The primary outcome was evidence of osteolysis (i.e. the difference in cortical ratio [CR]) on anteroposterior (AP) radiographs at final follow-up. RESULTS: Progressive osteolysis was found around the PEG/PBT cement restrictor represented by a significantly increasing cortical ratio (ΔCR 0.067 (95% CI, 0.063-0.071). Distance from tip prosthesis to plug and size of the plug were found to be independent factors in predicting increased cortical ratio. CONCLUSIONS: Our multicentre cohort shows increase of cortical ratio around the PEG/PBT cement restrictor which progresses over time. Physicians should be aware of this fact and are advised to intensify follow-up of patients who received this cement restrictor.

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty: analysis of 37,976 primary hip arthroplasties in the Dutch Arthroplasty Registry.

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). PATIENTS AND METHODS: In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were measured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the association between surgical approach and PROMs over time. RESULTS: From baseline to 3 and 12 months, improvements for NRS pain scores, EQ-5D, and OHS were comparable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (-0.2, 95% confidence interval [CI] -2.4 to 1.9) and between DSA and DAA (-1.7, CI -3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved -2.8 points (CI -4.9 to -0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (-1.0, CI -3.2 to 1.1). CONCLUSION: Our study showed no clinically meaningful differences between the DSA and either PLA or DAA.

Revision risk by using the direct superior approach (DSA) for total hip arthroplasty compared with postero-lateral approach: early nationwide results from the Dutch Arthroplasty Register (LROI).

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the classic posterolateral approach (PLA) for total hip arthroplasty (THA), in which the iliotibial band and short external rotators are spared. The revision rate of the DSA has not been investigated previously using arthroplasty registry data. We examined the reasons and risk of revision of the DSA, compared with the direct anterior approach (DAA) and PLA. PATIENTS AND METHODS: In this population-based cohort study we included 175,543 primary THAs performed between 2014 and 2020 (PLA, n = 117,576; DAA, n = 56,626; DSA, n = 1,341). Competing risk survival analysis and multivariable Cox proportional hazard analyses, adjusted for potential confounders, were performed. RESULTS: After 3 years, crude revision rates due to any reason were 2.1% (95% confidence interval [CI] 1.3-3.3) for DSA, and 2.9% (CI 2.8-3.0) for PLA. Crude dislocation revision rates were 0.3% (CI 0.1-0.8) for DSA, versus 1.0% (CI 0.9-1.0) for PLA. Dislocation revision rate for DSA did not differ from DAA (0.3% [CI 0.2-0.3]). Multivariable Cox regression analysis demonstrated no overall difference in revision rates for the DSA (HR 0.6 [CI 0.4-1.09) compared with the PLA. Lower risk of revision due to dislocation was found in patients operated on through the DSA (HR 0.3 [0.1-0.9]) compared with the PLA. CONCLUSION: Early nationwide results suggest that the DSA for total hip arthroplasty seems to show a tendency towards a lower risk of revision for dislocation but no overall reduced revision risk compared with the PLA.

Ten-year results of a prospective cohort of large-head metal-on-metal total hip arthroplasty : a concise follow-up of a previous report.

AIMS: Large-diameter metal-on-metal (MoM) total hip arthroplasty (THA) has demonstrated unexpected high failure rates and pseudotumour formation. The purpose of this prospective cohort study is to report ten-year results in order to establish revision rate, prevalence of pseudotumour formation, and relation with whole blood cobalt levels. METHODS: All patients were recalled according to the guidelines of the Dutch Orthopaedic Association. They underwent clinical and radiographical assessments (x-ray and CT scan) of the hip prosthesis and whole blood cobalt ion measurements. Overall, 94 patients (95 hips) fulfilled our requirements for a minimum ten-year follow-up. RESULTS: Mean follow-up was 10.9 years (10 to 12), with a cumulative survival rate of 82.4%. Reason for revision was predominantly pseudotumour formation (68%), apart from loosening, pain, infection, and osteolysis. The prevalence of pseudotumour formation around the prostheses was 41%, while our previous report of this cohort (with a mean follow-up of 3.6 years) revealed a 39% prevalence. The ten-year revision-free survival with pseudotumour was 66.7% and without pseudotumour 92.4% (p < 0.05). There was poor discriminatory ability for cobalt for pseudotumour formation. CONCLUSION: This prospective study reports a minimum ten-year follow-up of large-head MoM THA. Revision rates are high, with the main reason being the sequelae of pseudotumour formation, which were rarely observed after five years of implantation. Blood ion measurements show limited discriminatory capacity in diagnosing pseudotumour formation. Our results evidence that an early comprehensive follow-up strategy is essential for MoM THA to promptly identify and manage early complications and revise on time. After ten years follow-up, we do not recommend continuing routine CT scanning or whole cobalt blood measurements, but instead enrolling these patients in routine follow-up protocols for THA. Cite this article: Bone Jt Open 2022;3(1):61-67.

Symptomatic venous thromboembolism after trauma surgery : a study on 56.884 procedures.

Patients undergoing trauma surgery are at significant risk for developing thromboembolism. Venous thromboembolism rates, especially after less common surgical procedures are unknown. The purpose of this study is to establish data on the incidence of venous thromboembolism in trauma practice following a surgical procedure. All surgical trauma procedures between 2006 and 2011 were identified within the Achmea Health Database. This database records medical care to persons insured at the Achmea health insurance company. This is the largest health insurance company in the Netherlands. In the year following the surgical procedure we analyzed if a claim was filed concerning a deep venous thrombosis or pulmonary embolism. 56.884 surgical trauma procedures were included in the analysis and followed for one year thereafter. Venous thromboembolism development was raised most markedly until 100 days after the surgical procedure. Relatively high incidences of venous thromboembolism were found after surgical lower extremity and pelvic procedures. The present large database study provides a comprehensive view on the epidemiology of venous thromboembolism after different traumatic injuries requiring a surgical procedure.

CT radiation dose reduction in patients with total hip arthroplasties using model-based iterative reconstruction and orthopaedic metal artefact reduction.

OBJECTIVE: To evaluate the impact of radiation dose reduction on image quality in patients with metal-on-metal total hip arthroplasties (THAs) using model-based iterative reconstruction (MBIR) combined with orthopaedic metal artefact reduction (O-MAR). MATERIALS AND METHODS: Patients with metal-on-metal THAs received a pelvic CT with a full (FD) and a reduced radiation dose (RD) with -20%, -40%, -57%, or -80% CT radiation dose respectively, when assigned to group 1, 2, 3, or 4 respectively. FD acquisitions were reconstructed with iterative reconstruction, iDose4. RD acquisitions were additionally reconstructed with iterative model-based reconstruction (IMR) levels 1-3 with different levels of noise suppression. CT numbers, noise and contrast-to-noise ratios were measured in muscle, fat and bladder. Subjective image quality was evaluated on seven aspects including artefacts, osseous structures, prosthetic components and soft tissues. RESULTS: Seventy-six patients were randomly assigned to one of the four groups. While reducing radiation dose by 20%, 40%, 57%, or 80% in combination with IMR, CT numbers remained constant. Compared with iDose4, the noise decreased (p < 0.001) and contrast-to-noise ratios increased (p < 0.001) with IMR. O-MAR improved CT number accuracy in the bladder and reduced noise in the bladder, muscle and fat (p < 0.01). Subjective image quality was rated lower on RD IMR images than FD iDose4 images on all seven aspects (p < 0.05) and was not related to the applied radiation dose reduction. CONCLUSION: In RD IMR with O-MAR images, CT numbers remained constant, noise decreased and contrast-to-noise ratios between muscle and fat increased compared with FD iDose4 with O-MAR images in patients with metal-on-metal THAs. Subjective image quality reduced, regardless of the degree of radiation dose reduction.

Similar Superior Patient-Reported Outcome Measures for Anterior and Posterolateral Approaches After Total Hip Arthroplasty: Postoperative Patient-Reported Outcome Measure Improvement After 3 months in 12,774 Primary Total Hip Arthroplasties Using the Anterior, Anterolateral, Straight Lateral, or Posterolateral Approach.

BACKGROUND: Patient-reported outcome measures (PROMs) are used to evaluate the outcome of total hip arthroplasty (THA). We determined the effect of surgical approach on PROMs after primary THA. METHODS: All primary THAs, with registered preoperative and 3 months postoperative PROMs were selected from the Dutch Arthroplasty Register. Based on surgical approach, 4 groups were discerned: (direct) anterior, anterolateral, direct lateral, and posterolateral approaches. The following PROMs were recorded: Hip disability and Osteoarthritis Outcome Score Physical function Short form (HOOS-PS); Oxford Hip Score; EQ-5D index score; EQ-5D thermometer; and Numeric Rating Scale measuring pain, both active and in rest. The difference between preoperative and postoperative scores was calculated (delta-PROM) and used as primary outcome measure. Multivariable linear regression analysis was performed for comparisons. Cohen's d was calculated as measure of effect size. RESULTS: All examined 4 approaches resulted in a significant increase of PROMs after primary THA in the Netherlands (n = 12,274). The anterior and posterolateral approaches were associated with significantly more improvement in HOOS-PS scores compared with the anterolateral and direct lateral approaches. Furthermore, the posterolateral and anterior approaches showed greater improvement on Numeric Rating Scale pain scores compared with the anterolateral approach. No relevant differences in delta-PROM were seen between the anterior and posterolateral surgical approaches. CONCLUSION: Anterior and posterolateral surgical approaches showed more improvement in self-reported physical functioning (HOOS-PS) compared with anterolateral and direct lateral approaches in patients receiving a primary THA. However, clinical differences were only small.

Skin depigmentation along lymph vessels of the lower leg following local corticosteroid injection for interdigital neuroma.

Steroid injection is frequently used in the treatment of interdigital neuroma and has a high rate of success. We report the case of a patient who develops skin depigmentation at the injection site and linear streaks of depigmentation over the foot, the ankle and half way up to the knee after a steroid injection for interdigital neuroma. Minor disadvantages such as subcutaneous fat atrophy and depigmentation of the skin at the injection site are well known problems following steroid injection. Depigmentation of the skin with a lymphatic distribution in the foot after steroid injection for interdigital neuroma however, has not yet been reported before. This complication is a serious aesthetic problem and clinicians should be aware of this complication when treating patients with steroid injections for interdigital neuroma.

Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study.

PURPOSE: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. BACKGROUND: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose due to different metal artefacts. The O-MAR algorithm deploys an iterative loop where the metal sinogram is identified, extracted, and subsequently serves as a mask to correct the measured sinogram. Main goal of this study is to quantify the ability of the O-MAR technique to correct deviation in medullary bone attenuation caused by streak artefacts from the large-head MoM THA embedded in a phantom. Secondary goal is to evaluate the influence of O-MAR on CNR. METHODS: The phantom was designed as a Perspex box (PMMA) containing water and a supplementary MOM THA surrounded by Perspex columns comprising calibrated calcium pellets. Each column contains 200 mg of hydroxyapatite/calcium carbonate to simulate healthy bone tissue. Scans were obtained with and without a MoM THA at different dose levels. Different reconstructions were made with filter A, iDose(4) level 5 and with and without O-MAR. The scans without the prosthesis were used as the baseline. Information about the attenuation in Hounsfield units, image noise in standard deviation within the ROI's were extracted and the CNR was calculated. RESULTS: Pellet L0 and R0 (proximal of the MoM THA) were defined as reference, lacking any disturbance by metal artefacts; L5, L6 and L8 were respectively visually categorized as 'light' 'medium' and 'heavy disturbance'. Significant improvements in attenuation deviation caused by metal artefact were 43, 68 and 32 %, for respectively pellet L5, L6 and L8 (p < 0.001). Significant CNR improvements were present for L5 and L6 and were respectively 72 and 52 % (p < 0.001). O-MAR showed no improvement on CNR for L8. CONCLUSION: This phantom study significantly increases image quality by the use of O-MAR in the presence of metal artefacts by significantly reducing metal artefacts subsequently and increasing CNR on a 64 slice CT system in light and medium disturbance of the image.

Long-term outcomes of the Bi-Metric proximally hydroxyapatite-coated femoral stem.

PURPOSE: Promising clinical results and survival rates have been reported for the Bi-Metric proximally hydroxyapatite (HA)-coated femoral stem in short- and mid-term studies. In this study we evaluated the long-term survival as well as clinical and radiological results of this stem. METHODS: From 1992 to 1998 we prospectively included 112 consecutive patients who received a total hip arthroplasty (THA) with an uncemented proximally HA-coated Bi-Metric femoral component (Biomet).At 3 months, 1 year and thereafter every 2 to 3 years, patients were clinically and radiologically monitored. Primary endpoint was revision of the stem for any reason. Secondary endpoints were survival of the cup and THA, radiological characteristics and clinical scores (HHS, HOOS, SF-36 and VAS). RESULTS: Median follow-up was 20 (16-22.25) years. Median age at surgery was 52 (22-63) years. At final follow-up, survival analysis showed an all-cause stem survival of 96.8% (95% CI, 93.3-100). Median HHS scores improved from 57 preoperatively to 94 at final follow-up (p<0.001). At final follow-up the median HOOS score was 80 (9-100); median SF-36 score 71 (18-100); median VAS pain score at rest 0 (0-6) and during activity 0 (0-10). CONCLUSIONS: In this prospective cohort study the 20-year survival rate of the Bi-Metric proximally HA-coated femoral stem was excellent.

CT-based quantification of bone stock in large head metal-on-metal unilateral total hip replacements.

PURPOSE: To explore ipsilateral and contralateral acetabular roof bone stock density in unilateral large head MoM THA whether there is a significant lower acetabular bone stock in the hip with a metal-on-metal (MoM) total hip replacement compared to the contralateral side. Second part of this study is to examine if there are any associates with regard to potential bone stock density difference. MATERIALS & METHODS: A database of 317 patients with unilateral metal-on-metal (MoM) total hip replacements was set up retrospectively for this study. On computed tomography scans, conducted after a relative short in situ time period averaging 2.8 years, regions-of-interests were drawn in the trabecular bone of the acetabulum to measure average Hounsfield Units (HU). HU differences were calculated and tested by Wilcoxon signed-rank test. Univariate analysis was conducted to examine associates of potential bone loss. RESULTS: In a population of 317 patients (156 male, 161 female) with an average age of 61.9 ± 7.8, the median HU on the side of the MoM replacement was 123.3 (7.6-375.4). On the contralateral side, median HU was 144.7 (-0.4 to 332.8). The median HU difference was 21.4 after a mean post-operative in situ time of 2.8 years. The Wilcoxon signed-rank test proved a significant difference (p<0.001). Univariate analyses show that the in situ time of the MoM THA has a significant correlation with the bone density difference. CONCLUSION: Results show a significant lower bone density at the acetabular roof at the side of the prosthesis compared with the contralateral side after short in situ time of the MoM THA in patients with unilateral MoM total hip replacements. In our patient population, the in situ time showed a significant association with the acetabular bone density difference. As acetabular roof bone stock measurements are feasible and show temporal decline this could become an important parameter to be used in orthopedic decision making for revision surgery.

Sequelae of large-head metal-on-metal hip arthroplasties: Current status and future prospects.

Large-head metal-on-metal (MoM) bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing (HR), followed closely by large metal head total hip arthroplasty (THA). A worldwide increase in the use of MoM hip arthroplasty subsequently saw a sharp decline, due to serious complications.MoM was rapidly adopted in the early 2000s until medical device alerts were issued by government regulatory agencies and national and international organisations, leading to post-marketing surveillance and discontinuation of these implants.Guidelines for MoM hip implant follow-up differ considerably between regulatory authorities worldwide; this can in part be attributed to missing or conflicting evidence.The authors consider that the use of large-head MoM THA should be discontinued. MoM HR should be approached with caution and, when considered, should be used only in patients who meet all of the recommended selection criteria, which limits its indications considerably.The phased introduction of new prostheses should be mandatory in future. Close monitoring of outcomes and long-term follow-up is also necessary for the introduction of new prostheses. Cite this article: van Lingen CP, Zagra LM, Ettema HB, Verheyen CC. Sequelae of large-head metal-on-metal hip arthroplasties: current status and future prospects. EFORT Open Rev 2016;1:345-353. DOI: 10.1302/2058-5241.1.160014.

Development and first validation of a simplified CT-based classification system of soft tissue changes in large-head metal-on-metal total hip replacement: intra- and interrater reliability and association with revision rates in a uniform cohort of 664 arthroplasties.

OBJECTIVE: After implantation of a metal-on-metal total hip arthroplasty (MoM THA), a large incidence of pseudotumor formation has been described recently. Several centers have invited patients for follow-up in order to screen for pseudotumor formation. The spectrum of abnormalities found by CT in MoM THA patients can be unfamiliar to radiologists and orthopedic surgeons. Previously, a CT five-point grading scale has been published. In this paper, a simplification into a three-point classification system gives insight in the morphological distinction of abnormalities of the postoperative hip capsule in MoM implants in relation to the decision for revision. The reliability of this simplified classification regarding intra- and interrater reliability and its association with revision rate is investigated and discussed. MATERIALS AND METHODS: All patients who underwent MoM THA in our hospital were invited for screening. Various clinical measures and CT scan were obtained in a cross-sectional fashion. A decision on revision surgery was made shortly after screening. CT scans were read in 582 patients, of which 82 patients were treated bilaterally. CT scans were independently single read by two board-certified radiologists and classified into categories I-V. In a second meeting, consensus was obtained. Categories were subsequently rubricated in class A (categories I and II), B (category III), and C (categories IV and V). Intra- and inter-radiologist agreement on MoM pathology was assessed by means of the weighted Cohen's kappa. Categorical data were presented as n (%), and tested by means of Fisher's exact test. Continuous data were presented as median (min-max) and tested by means of Mann-Whitney U test (two group comparison) or Kruskal-Wallis test (three group comparison). Logistic regression analysis was performed in order to study independence of CT class for association with revision surgery. Univariate statistically significant variables were entered in a multiple model. All statistical analysis was performed two-tailed using alpha 5% as the significance level. RESULTS: In total, 664 scores from 664 MoM hips obtained by two observers were available for analyses. Interobserver reliability for the non-simplified version (I-V) was κw = 0.71 (95% CI: 0.62-0.79), which indicates good agreement between the two musculoskeletal radiologists. Intra- and interobserver reliability for the simplified version (A-C) were respectively κw 0.78 (95% CI: 0.68-0.87), and κw = 0.71 (95% CI: 0.65-0.76). This indicates good agreement within and between the two observers. The simplified A-C version is significantly associated with revision exclusively due to MoM pathology, in both patients with unilateral MoM THA (p < 0.001) and patients with bilateral MoM THA (p < 0.044). The simplified A-C version is associated with several clinical measures. In patients with unilateral MoM THA, with or without contralateral THA, in situ time (p < 0.008), cobalt and chromium (p < 0.001) were statistically significant. In patients with bilateral MoM, cobalt (p < 0.001) and chromium (p < 0.027) were statistically significant. Revision is significantly associated with cup size (p < 0.001), anteversion of the cup (p < 0.004), serum ion levels of cobalt and chromium (p < 0.001) and the adapted classification system (p < 0.001). In univariate logistic regression analysis on revision, cup, anteversion of the cup, cobalt-chromium ion serum levels, and the simplified (A-C) CT category system were statistically significant. The simplified (A-C) CT category system was an independent associate of revision, in several multiple logistic regression models. CONCLUSIONS: The presented simplified CT grading system (A-C) in its first clinical validation on 48- and 64-multislice systems is reliable, showing good intra- and interrater reliability and is independently associated with revision surgery.

Revision of a single type of large metal head metal-on-metal hip prosthesis.

Large-head metal-on-metal (MoM) total hip arthroplasties were introduced because of their purported advantages. Inflammatory pseudotumours occasionally occur after MoM hip arthroplasty and often lead to revision. The purpose of this study was to assess the outcome of revision of large-head MoM total hip arthroplasties after an extensive screening protocol for all MoM articulations with a minimum 2 year follow-up. We identified 50 hips that had undergone large-head MoM total hip arthoplasty and required revision at a mean of 44 months after index operation. Of these, 38 were revised for pseudotumours, 7 for loosening, 2 for infection and 3 for instability. There was bone loss in 44 hips. The majority were revised to a 28 mm metal or ceramic head on a polyethylene-cemented cup. In 12 patients there was a complication. There was a decrease of whole blood cobalt from 20.8 µg/L preoperatively to 1.8 µg/L 1 year after revision. We found 6 residual masses on routine postoperative CT scans. The indication for revision of this cohort is inevitable but the clinical outcome 2 years after revision for pseudotumour is disappointing. Revising a MoM hip arthroplasty to a conventional cemented polyethylene or dual-mobility cup with bone impaction grafting and a 28 mm head can adequately treat the high ion levels and probably the disease of ARMD.

Basic principles and uniform terminology for the head-neck junction in hip replacement.

Recent problems with large head metal on metal hip replacements have spiked renewed interest in the head-neck junction. A thorough knowledge of the principles of the locking mechanism, the assembly technique and affecting factors on the strength of this junction is needed. Currently a confusing variability in terms is used to describe this junction. This overcomplicates an already complex issue. The purpose of this literature review is to collect and list the different terms used and to propose a uniform terminology. Two authors independently searched the electronic databases of PubMed, CINAHL and MEDLINE with specific key words and combinations according to the PRISMA guidelines. The initial search yielded a total of 518 articles with ultimately 53 articles included in the present analysis. No consensus for a uniform term for the 2 sides of the head-stem junction was found. Since there is already pronounced variability in taper designs between different manufacturers (even so similarly named, e.g. "12/14"), a uniform terminology could be the first step to simplify the situation. "Male" and "female taper" is proposed as the appropriate terminology for the stem and head junction in hip replacement, respectively. The importance of the assembly technique understanding the principles of the locking mechanism is emphasised.

Self-reported neurological clinical manifestations of metal toxicity in metal-on-metal hip arthroplasty.

Adverse reactions to metal particle debris have been increasingly reported as a complication following large head metal-on-metal (MoM) hip arthroplasty. Elevated metal ion levels are a cause for concern. The aim of this study is to evaluate whether exposure to cobalt is associated with patient characteristics and symptoms of neuropathy, representing nervous system dysfunction. A cross-sectional study was conducted comparing patients with a MoM total hip arthroplasty and patients with a conventional hip arthroplasty. They received three questionnaires, one to assess neurotoxic complaints and two standardised self-administered questionnaires to identify symptoms that are suggestive of peripheral neuropathy. Current and historical data were available for whole blood cobalt levels in all patients. We analysed potential predictive factors for cobalt based on five different cut-off levels (0-2, 2-4, 4-10, 10-20, >20 µg/L). We performed 723 MoM total hip arthroplasties in 643 patients in our clinic. The response rate was 89%. Male-female ratio was 236/280, median age 63.6 years (30-72) with a mean follow-up of 50.6 months (20-86). We also sent the questionnaires to 98 patients in the control group. An increase in the incidence of reported symptoms was not consistent with higher serum cobalt levels. Female gender was the only consistent predictive factor for serum cobalt at different cobalt cut-off levels in the multivariate analysis. The study population did not show an increase in reported symptoms with elevated cobalt levels. Neurotoxic symptoms and whole blood cobalt levels did not show a consistent relationship with different dichotomised levels of cobalt exposure.

Excellent results with the cemented Lubinus SP II 130-mm femoral stem at 10 years of follow-up: 932 hips followed for 5-15 years.

BACKGROUND AND PURPOSE: The Lubinus SP II stem is well documented in both orthopedic registries and clinical studies. Worldwide, the most commonly used stem lengths are 150 mm and 170 mm. In 1995, the 130-mm stem was introduced, but no outcome data have been published. We assessed the long-term survival of the Lubinus SP II 130-mm stem in primary total hip arthroplasty. PATIENTS AND METHODS: In a retrospective cohort study, we evaluated 829 patients with a Lubinus SP II primary total hip arthroplasty (932 hips). The hips were implanted between 1996 and 2001. The primary endpoint was revision for any reason. The mean follow-up period was 10 (5-15) years. RESULTS: Survival analysis showed an all-cause 10-year survival rate of the stem of 98.7% (95% CI: 99.7-97.7), and all-cause 10-year survival of the total hip arthroplasty was 98.3% (95% CI: 99.3-97.3). INTERPRETATION: Excellent long-term results can be achieved with the cemented Lubinus SP II with the relatively short 130-mm stem. This stem has potential advantages over its 150-mm and 170-mm siblings such as bone preservation distal to the stem, better proximal filling around the prosthesis, and easier removal.

Clinical manifestations in ten patients with asymptomatic metal-on-metal hip arthroplasty with very high cobalt levels.

Reports of adverse reactions to metal particle debris with metal-on-metal (MoM) hip arthroplasty have increased recently. Apart from the formation of pseudotumours and higher revision rates, another major cause for concern are the systemic effects of metal ions. Several effects of elevated systemic cobalt ions have been reported (e.g., myocardial and neurological effects, hypothyroidism). All 643 patients who underwent a stemmed large head MoM total hip replacement in our clinic were screened with repeated whole blood samples of metal ions (cobalt, chromium). We included ten asymptomatic unrevised patients with the highest cobalt concentrations, determined at a minimum of three years after implantation. These patients were subjected to an extensive neurological and cardiological screening protocol. In addition, blood samples were taken to assess renal and thyroid function. Ten patients with a cobalt level of 18-153 µg/L (mean 46.8 µg/L) were included. Nine patients were female, mean age was 65 years (range 56-75). The mean follow-up period was 4.2 years (range 3.0-6.1). Seven patients had bilateral stemmed MoM hip arthroplasty. No signs or symptoms of neurological dysfunction, cardiomyopathy, or renal or thyroid dysfunction could be identified or attributed to elevated cobalt levels. The clinical relevance of this study is that after short-term follow-up highly elevated blood cobalt levels do not cause systemic effects in our population. Hence in asymptomatic patients metal ions appear not to be a significant factor in the decision of when to revise a MoM large head total hip replacement.