Search

Background Spinal epidural lipomatosis (SEL) is characterized by symptomatic neurogenic compression from adipose tissue in the spinal canal. The question arises whether patients with morbid obesity have higher volumes of epidural adipose tissue (EAT) in their lumbar spinal canal compared to patients with a normal weight and to which extent this decreases after bariatric surgery. Methods In this explorative study the lumbar EAT volume was assessed in 25 patients with morbid obesity (Body Mass Index (BMI)>40) using available lumbar magnetic resonance imaging (MRI) prior to their bariatric surgery. An age and gender matched control group (n=25) of patients with a normal weight (BMI 20-25) was used for comparison. Participants from the obesity group underwent a post-operative control MRI. Results The mean volume of EAT per MRI-slice of the group of patients with obesity was significantly higher than for the group of patients with normal weight (mean 83.3 mm3 ± 30.7 versus mean 56.5 mm3 ± 25; p Conclusions Patients with obesity have significantly larger volumes of EAT in comparison to patients with normal weight. After bariatric surgery, a significant weight loss coincided with a significant volumetric reduction of this adipose tissue in the spinal canal. Future prospective studies in patients with symptomatic SEL may elucidate whether decreases in EAT volume influence concurrent neurogenic claudication symptoms.

Contains fulltext : 290748.pdf (Publisher’s version ) (Open Access) Although several models for the prediction of surgical complications after primary total hip or total knee replacement (THA and TKA, respectively) are available, only a few models have been externally validated. The aim of this study was to externally validate four previously developed models for the prediction of surgical complications in people considering primary THA or TKA. We included 2614 patients who underwent primary THA or TKA in secondary care between 2017 and 2020. Individual predicted probabilities of the risk for surgical complication per outcome (i.e., surgical site infection, postoperative bleeding, delirium, and nerve damage) were calculated for each model. The discriminative performance of patients with and without the outcome was assessed with the area under the receiver operating characteristic curve (AUC), and predictive performance was assessed with calibration plots. The predicted risk for all models varied between

This paper presents a large publicly available multi-center lumbar spine magnetic resonance imaging (MRI) dataset with reference segmentations of vertebrae, intervertebral discs (IVDs), and spinal canal. The dataset includes 447 sagittal T1 and T2 MRI series from 218 patients with a history of low back pain. It was collected from four different hospitals and was divided into a training (179 patients) and validation (39 patients) set. An iterative data annotation approach was used by training a segmentation algorithm on a small part of the dataset, enabling semi-automatic segmentation of the remaining images. The algorithm provided an initial segmentation, which was subsequently reviewed, manually corrected, and added to the training data. We provide reference performance values for this baseline algorithm and nnU-Net, which performed comparably. We set up a continuous segmentation challenge to allow for a fair comparison of different segmentation algorithms. This study may encourage wider collaboration in the field of spine segmentation, and improve the diagnostic value of lumbar spine MRI.

Periprosthetic joint infection (PJI) is a devastating complication following total knee or total hip arthroplasty (TKA/THA). Appropriate empiric antibiotic treatment, initiated directly after debridement and implant retention (DAIR), is suggested to contribute to treatment success. The aim of this study was to describe the microbiology and the antibiotic susceptibility in early PJI to guide future empiric treatment in a region with a low incidence of methicillin-resistant Staphylococcus aureus (MRSA). Consecutive patients who underwent DAIR within 3 months after primary unilateral TKA or THA between January 2011 and December 2018 were retrospectively identified from the hospital electronic health records. Data on causative pathogens, antimicrobial susceptibility and the number of post-operative days until cultures demonstrated bacterial growth were collected. One hundred and eleven early PJIs were identified of which 65 (59%) were monomicrobial and 46 (41%) polymicrobial. Among all isolated pathogens, Staphylococcus aureus (n = 53; 29%) was the most commonly identified pathogen in early PJI without any involvement of MRSA. 72% of PJIs were susceptible to vancomycin which could be increased to around 90% by adding gram-negative coverage. On the 5th postoperative day, bacterial growth was observed in 98% of cases. All gram-negative bacteria demonstrated positive tissue cultures on the 4th postoperative day. Vancomycin combined with ciprofloxacin or a third generation cephalosporin provided the highest antimicrobial coverage of all responsible pathogens identified in early PJI. Empiric treatment of gram-negative treatment can be safely terminated in the absence of gram-negative pathogens after 4 days of culturing in cases without preoperative antibiotic treatment.

Aims Preoperative nasal Staphylococcus aureus screening and eradication reduces surgical site infections (SSIs) but its impact on reducing early prosthetic joint infection (PJI) remains controversial. This study aims to assess the effect of preoperative nasal S. aureus screening and eradication on the incidence of early PJI in general and S. aureus-induced early PJI. Methods All primary total hip arthroplasties (THA) and total knee arthroplasties (TKA) performed from January 2006 to April 2018 were retrospectively reviewed for the incidence of early PJI. Demographic parameters, risk factors for PJI (American Society of Anaesthesiologists classification, body mass index, smoking status, and diabetes mellitus) and implant types were collected. A preoperative screening and eradication protocol for nasal colonization of S. aureus was introduced in October 2010. The incidence of early PJI was compared before and after the implementation of the protocol. Missing data were imputed via multiple imputation by chained equations. Inverse probability weighting was used to account for differences between patients in both groups. Weighted univariate logistic regression was used to evaluate the incidence of early PJI for both groups. Results In total, 10,486 THAs and TKAs were performed in the research period. After exclusion, a cohort of 5,499 screened cases and 3,563 non-screened cases were available for analysis. Overall, no significant reduction in early PJI was found in the screened group (odds ratio (OR) 0.78, 95% confidence interval (CI) 0.55 to 1.11; p = 0.173). However, the incidence of S. aureus-induced PJI was significantly reduced (OR 0.58, 95% CI 0.36 to 0.92; p = 0.027) in the screened group. Conclusion A preoperative nasal S. aureus screening and eradication protocol did not significantly reduce the overall incidence of early PJI after THA or TKA. However, a decreased incidence of S. aureus-induced early PJI was established. These findings can help to establish better consensus around the value of these screening protocols. Cite this article: Bone Joint J 2020;102-B(10):1341–1348.

Contains fulltext : 248615.pdf (Publisher’s version ) (Open Access) Background and purpose - Trochanteric fractures are often treated using intramedullary fixation. In our institution, the TFN-Advanced Proximal Femoral Nailing System (TFNA) was introduced as replacement for the Gamma Trochanteric Nail (GTN3) for the treatment of these fractures as a result of a hospital-driven change of trauma implant supplier. We compared trochanteric fracture fixation failure rate between these 2 intramedullary nails. Patients and methods - All trochanteric fractures treated surgically from 2011 to 2019 were retrospectively reviewed for fixation failure. From 2016 only the TFNA was used. Fixation failure was defined as implant cut-out, implant breakage, non-union, malpositioning of the screw/blade requiring reoperation, new fracture around the nail, or miscellaneous. Propensity score matching was used to balance distribution of covariates and to compare failure rates between TFNA and GTN3 groups. Learning curve analyses were performed. Results - After exclusion, 797 GTN3s (779 patients) and 542 (536 patients) TFNAs were available for analysis. A higher risk of fixation failure was found in the TFNA group (14%) compared with the GTN3 group (7.0%) (hazard ratio [HR] 2.0, 95% confidence interval [CI] 1.2-3.5). This was mainly attributed to a higher risk of cut-out (HR 2.2; CI 0.9-5.7), malpositioning (HR 4.7; CI 0.7-34), and new fracture around the nail (HR 4.0; CI 1.0-16). Learning curve analyses indicated no clear learning curve effect. Interpretation - Failure of fixation increased after a switch from the GTN3 to the TFNA proximal femoral nail for the treatment of trochanteric fractures. Cut-out and malpositioning of the calcar screw or blade appeared to be the most dominant failure mechanisms. Modifications in implant design may have played a role in this increased risk of failure of fixation. In our institution a new implant device was introduced without solid clinical evidence behind it. This study may help to underline the need for medical doctors with a critical and scientific background to be involved in implant choices.

Study design in the rest of the article written as patient- and observer-blinded, multicenter, randomized, intrapatient controlled, noninferiority trial. Objective The aim of this study was to determine noninferiority of a biphasic calcium-phosphate (AttraX® Putty) as a bone graft substitute for autograft in instrumented posterolateral fusion (PLF). Summary of background data Spinal fusion with autologous bone graft is a frequently performed surgical treatment. Several drawbacks of autografting have driven the development of numerous alternatives including synthetic ceramics. However, clinical evidence for the standalone use of these materials is limited. Methods This study included 100 nontraumatic adults who underwent a primary, single- or multilevel, thoracolumbar, instrumented PLF. After instrumentation and preparation for grafting, the randomized allocation side of AttraX® Putty was disclosed. Autograft was applied to the contralateral side of the fusion trajectory, so each patient served as his/her own control. For the primary efficacy outcome, PLF was assessed at 1-year follow-up on computed tomography scans. Each segment and side was scored as fused, doubtful fusion, or nonunion. After correction for multilevel fusions, resulting in a single score per side, the fusion performance of AttraX Putty was tested with a noninferiority margin of 15% using a 90% confidence interval (CI). Results There were 49 males and 51 females with a mean age of 55.4 ± 12.0 (range 27-79) years. Two-third of the patients underwent a single-level fusion and 62% an additional interbody fusion procedure. The primary analysis was based on 87 patients, including 146 instrumented segments. The fusion rate of AttraX Putty was 55% versus 52% at the autograft side, with an overall fusion rate of 71%. The 90% CI around the difference in fusion performance excluded the noninferiority margin (difference = 2.3%, 90% CI = -9.1% to +13.7%). Conclusion The results of this noninferiority trial support the use of AttraX Putty as a standalone bone graft substitute for autograft in instrumented thoracolumbar PLF. Level of evidence 1.

Background: Treatment and rehabilitation protocol for hip arthroplasty differs between Germany and the Netherlands. The Dutch system promotes fast-track surgery whereas in Germany conventional care is provided with a longer hospital stay including rehabilitation. Clinical outcome, patient satisfaction and costs in both treatment protocols were compared in a prospective setup. Material and methods: This prospective cohort study included patients allocated for primary THA in 3 German and 1 Dutch hospital in the border region. Patient-reported outcome scores (PROMS) were measured pre- and postoperatively at 6 and 12 months including the Oxford Hip Score, SF12 survey, visual analogue scale for satisfaction and pain. Length of hospitalisation and availability of postoperative rehabilitation were recorded. In addition, a total cost estimation was calculated using health insurers data. Results: A total of 360 consecutive patients were included; 175 THA in Germany compared to 185 THA in the Netherlands. No cross-border healthcare was encountered in both cohorts. Mean length of hospitalisation was 11.3 (range 6–23) days in Germany, compared to 4.4 (range 3–25) days in the Netherlands. In Germany 92% of the patients was discharged with inpatient (72%) or outpatient (20%) rehabilitation, compared to 21% with only inpatient rehabilitation in the Netherlands. No significant differences were measured regarding the PROMS and patient satisfaction between both countries. Due to profound differences in health care financing only a global cost estimation could be made and no major differences were encountered. Conclusion: Germany and the Netherlands both offer highly protocolled care for THA with comparable functional outcome and patient satisfaction with treatment after 12 months. Despite the length of hospitalisation in Germany is significantly longer including a more intensive rehabilitation programme, no significant differences were recorded regarding functional outcome nor patient satisfaction compared to fast-track surgery performed in the Netherlands.

Study design A multicenter, randomized, intrapatient controlled trial. Objective This study investigated whether lumbar fusion patients blinded to the harvest site (A) can identify the iliac crest used for bone harvesting and (B) whether this iliac crest is more painful than the contralateral side. Summary of background data Spinal fusion with iliac crest autograft is a frequently performed surgical procedure. A widely reported disadvantage of the harvesting procedure is potential donor site morbidity. This has driven the development of many bone graft substitutes. However, more recently the incidence and severity of donor site pain is debated, especially in lumbar fusion surgery. Methods Ninety-two nontraumatic adult patients underwent a posterolateral (thoraco)lumbar fusion. Iliac crest bone graft was harvested unilaterally through the primary midline incision. At 6 weeks, 3 months, 6 months, and 1 year follow-up, patients were asked to identify the donor site and to rate pain in their back, left iliac crest and right iliac crest on a Visual Analogue Scale (VAS). Results Ninety patients, 44 males and 46 females with a mean age of 54 years, were analyzed. The left/right distribution of the iliac crest donor site was 50/50 and 89% of the patients underwent a lumbar fusion below L3. Only 24% patients identified the harvest site correctly. Moreover, the VAS pain scores for the donor site and contralateral iliac crest did not differ and were at each timepoint lower than the scores for back pain. Conclusion This study showed that, during the first year after lumbar fusion surgery via a single midline incision approach, patients could not reliably identify the iliac crest used for bone graft harvesting and this iliac crest was not more painful than the untouched contralateral iliac crest. Therefore, donor site pain should not be the main reason to use bone graft alternatives for lumbar spinal fusion. Level of evidence 2.

Contains fulltext : 208127.pdf (Publisher’s version ) (Open Access) Background and purpose - Gait analysis performed under increased physical demand may detect differences in gait between total (THA) versus resurfacing hip arthroplasty (RHA), which are not measured at normal walking speed. We hypothesized that patients after RHA would reach higher walking speeds and inclines compared with THA. Additionally, an RHA would enable a more natural gait when comparing the operated with the healthy contralateral hip. Patients and methods - From a randomized controlled trial comparing THA with RHA with at least 5 years' follow-up patients with a UCLA score of more than 3 points (n = 34) were included for an instrumented treadmill gait analysis. 25 patients with a unilateral implant (primary analysis-16 THA versus 9 RHA) and 9 patients with a bilateral implant (sub-analysis-n = 5 RHA + THA; n = 4 THA + THA). Spatiotemporal parameters, ground reaction forces, and range of motion were recorded at increasing walking speeds and inclines. Functional outcome scores were obtained. Results - At a normal walking speed of 1.1 m/s and at increasing inclines no differences were recorded in gait between the 2 groups with a unilateral hip implant. With increasing walking speed the RHA group reached a higher top walking speed (TWS) (adjusted difference 0.07 m/s, 95% CI -0.11 to 0.25) compared with THA. Additionally, RHA patients tolerated more weight on the operated side at TWS (155 N, CI 49-261) and as such weight-bearing approached the unaffected contralateral side. For the RHA group a "between leg difference" of 8 N (CI 3-245) was measured versus -129 N (CI -138 to -29) for THA (adjusted difference 144 N, CI 20-261). Hip flexion of the operated side at TWS was higher after RHA compared with THA (adjusted difference 8 degrees , CI 1.7-14). Interpretation - In this study RHA patients reached a higher walking speed, and preserved a more normal weight acceptance and a greater range of hip flexion against their contralateral healthy leg as compared with patients with a THA.

Oropharyngeal dysphagia (OD) is commonly encountered in elderly patients with hip fracture. It is easily overlooked and predisposes patients to life-threatening postoperative pneumonia. The aim of this study was to evaluate whether OD screening by nurses results in a better recognition of patients at risk for OD. After the introduction of the Standardized Swallowing Assessment by nurses, the incidence of increased risk for OD and the prevention of OD complications were monitored (intervention group; N = 92) and compared with a historical control group (N = 81). The risk for OD was diagnosed in 27 patients (29%) in the intervention group in comparison with 12 patients (15%) in the control group (p.05). The number of diet modifications increased from 12 (15%) in the control group to 25 (27%) in the intervention group (p.05). A simple screening test results in better recognition of increased OD risk and, in turn, the early initiation of measures to avoid aspiration.

Background Postoperative follow-up after hemiarthroplasty is part of routine based practice. However, these visits appear to be a significant burden since it concerns a frail population. The aim of this study was to confirm the current common practice regarding postoperative visits of patients treated with hemiarthroplasty and to evaluate the complication detection rate at these visits. Methods A national short survey was conducted among orthopedic surgeons working in 26 large Dutch teaching hospitals to test the hypothesis that postoperative follow-up is indeed common practice. Furthermore, a retrospective patient review was performed in all hemiarthroplasties implanted between January 2014 and December 2019. Results The response of the national survey was complete and showed that postoperative follow-up in patients treated with hemiarthroplasty is part of standard care according to 89% of respondents. A total of 1055 hips (1026 patients) were implanted with hemiarthroplasty during the studied period. Implant-related complications were identified in 68 hemiarthroplasties, with 31 of these hips going on to reoperation. Only 2 of these complications were picked up at standard planned follow-up leading to a complication detection rate of 0.3%. In contrast, complication detection rates of 47% and 16% were found at unplanned visits at the Emergency Department and the outpatient department, respectively. Conclusions Postoperative follow-up in patients treated with hemiarthroplasty is still the standard of care. However, this study revealed that the majority of implant-related complications are detected at unplanned visits and almost no at standard follow-up visits. Postoperative follow-up of patients treated with hemiarthroplasty could be abandoned in this frail population.

Preoperative nasalAll primary total hip arthroplasties (THA) and total knee arthroplasties (TKA) performed from January 2006 to April 2018 were retrospectively reviewed for the incidence of early PJI. Demographic parameters, risk factors for PJI (American Society of Anaesthesiologists classification, body mass index, smoking status, and diabetes mellitus) and implant types were collected. A preoperative screening and eradication protocol for nasal colonization ofIn total, 10,486 THAs and TKAs were performed in the research period. After exclusion, a cohort of 5,499 screened cases and 3,563 non-screened cases were available for analysis. Overall, no significant reduction in early PJI was found in the screened group (odds ratio (OR) 0.78, 95% confidence interval (CI) 0.55 to 1.11; p = 0.173). However, the incidence ofA preoperative nasal

This study reports on the incidence of intraoperative calcar fractures with the cementless Spotorno (CLS) stem, and the potential role of a learning curve and implant positioning is investigated. After introduction of the CLS stem, 800 consecutive cementless total hip arthroplasties (THA) were analyzed. The incidence of calcar fracture in the first 400 THA was compared with the second 400 THA, in order to study a potential learning curve effect. According to the instruction for users, varus positioning of the stem was avoided and a femoral neck osteotomy was aimed relatively close to the lesser trochanter since these are assumed to be correlated with calcar fractures. Implant positioning (neck-shaft angle, femoral offset and osteotomy-lesser trochanter distance) was measured on postoperative pelvic radiographs of all THA with calcar fractures and 100 randomly selected uncomplicated control cases. Seventeen (2.1%) intraoperative calcar fractures were recorded. The incidence of calcar fracture differed between the first 400 THA (n = 11) and the second 400 THA (n = 6). This difference was not statistically significant (p = 0.220); however, these numbers indicate a trend toward a learning effect. No significant difference in stem positioning nor the height of the femoral neck osteotomy was measured between THA with a calcar fracture (n = 17) and the control cases (n = 100). We report on a high incidence of intraoperative calcar fractures with the use of a CLS stem. The risk for calcar fractures remains clinically significant even after adequate implant positioning in the hands of experienced hip surgeons. Surgeons should be aware of this implant related phenomenon and be alert on this phenomenon intraoperatively.

Background and purpose — Impaction bone grafting (IBG) is an established method in hip revision surgery to reconstruct loss of bone stock. There is limited knowledge concerning the actual bone remodelling process within the allograft. We investigated with repeated bone mineral density (BMD) measurements the biological process of bone remodelling in the allograft in vivo. We hypothesized that an initial decrease in BMD would be followed by an increase towards baseline values. Patients and methods — Dual-energy X-ray absorptiometry (DXA) was used to measure BMD values in 3 regions of interest (ROI) in 20 patients (average age at surgery 70 years, 11 males) after an acetabular reconstruction with IBG and a cemented cup. A postoperative DXA was used as baseline and DXA was repeated at 3 and 6 months and at 1 and 2 years. The Oxford Hip Score (OHS), the 12-Item Short Form Health Survey (SF12), and a 0 to 100 mm visual analogue scale (VAS) for pain and satisfaction were obtained simultaneously. Results — The overall mean BMD in the IBG regions increased significantly by 9% (95% CI 2–15) at 2 years’ follow-up. In the cranial ROI BMD increased 14% (CI 6–22), whereas the BMD in the medial and caudal ROI showed an increase of 10% (CI 1–18) and 4% (CI –6–16), respectively. The OHS, SF12-mental, and VAS for pain all improved statistically significantly 2 years after surgery, with a mean VAS for satisfaction of 77 (CI 63–90) out of 100 points. The SF12-physical showed non-significant improvement. Interpretation — The BMD in the allograft gradually increased after IBG for acetabular reconstruction arthroplasties, particularly in the cranial ROI. An initial decrease in the BMD was not encountered. These BMD changes, as proxy measurements for bone remodeling, may indicate progressive apposition of vital new host bone in the grafted area.

Catalytic N-H bond activation and breaking by well-defined molecular complexes is a challenge in chemical science. Metal nanoparticles catalytically decompose NH3; they are, however, ill-defined and contain a range of sites with varying coordination numbers and catalytic properties. So far, no well-defined molecular complexes have been demonstrated to catalytically break strong N-H bonds in NH3. Recently, non-catalytic activation of NH3 with liberation of molecular H2 on the organometallic molybdenum complex was demonstrated. Herein, we show catalytic activation and breaking of N-H bonds on a well-defined, highly thermally-resistant (even under reducing environments) Co(II)1O4 site of a heterogeneous catalyst for organic (ethylamine) and inorganic (NH3, with the formation of N2 and H2) molecules. We directly compare the activity of isolated cationic cobalt sites with ultra small (2.7 nm and less) silica-supported cobalt nanoparticles. DFT calculations suggest a mechanism that involves breaking of N-H bond in NH3 and N-N coupling steps taking place on a Co1O4 site. In contrast, Co1N4 sites are not catalytically active, implying that the ligand environment around a single atom of a heterogeneous catalyst largely controls reactivity in NH3 activation. This may open a new chapter for the design of well-defined heterogeneous materials for N-H bond activation reactions.

The spatial organization of microbial communities arises from a complex interplay of biotic and abiotic interactions, and is a major determinant of ecosystem functions. Here we design a microfluidic platform to investigate how the spatial arrangement of microbes impacts gene expression and growth. We elucidate key biochemical parameters that dictate the mapping between spatial positioning and gene expression patterns. We show that distance can establish a low-pass filter to periodic inputs and can enhance the fidelity of information processing. Positive and negative feedback can play disparate roles in the synchronization and robustness of a genetic oscillator distributed between two strains to spatial separation. Quantification of growth and metabolite release in an amino-acid auxotroph community demonstrates that the interaction network and stability of the community are highly sensitive to temporal perturbations and spatial arrangements. In sum, our microfluidic platform can quantify spatiotemporal parameters influencing diffusion-mediated interactions in microbial consortia., The spatial organisation of microbial communities is caused by the interplay of biotic and abiotic factors. Here the authors design a microfluidic platform to quantify the spatiotemporal parameters influencing diffusion-mediated interactions, and use this device to investigate information transmission and metabolic cross-feeding in synthetic microbial consortia.

Purpose Bone preservation is an important advantage of the resurfacing hip arthroplasty (RHA) concept. We hypothesised that patients’ increase in physical activity level after RHA would positively relate with periprosthetic bone mineral density (BMD) changes and thus facilitate bone preservation. Methods BMD-changes were prospectively recorded in 38 patients after RHA. Dual-energy absorptiometry was used to quantify BMD-changes in 6 periprosthetic regions of interest preoperatively, at 6 months, 1, 2 and 3 years postoperative. The effect estimates of patients’ physical activity, according to their Harris Hip Score (HHS) and University of California at Los Angeles (UCLA) Activity Score, on these BMD changes were assessed in linear mixed models. Results The UCLA (coefficient = 0.02 (95% CI, 0.010-0.034); pConclusions The increase in activity scores after RHA was indeed associated with an increase in BMD in the calcar region, however unexpectedly also with a BMD decrease on the acetabular side. Stress shielding from the implant is the most likely causative factor.

Increasing levels of energy consumption, dwindling resources, and environmental considerations have served as compelling motivations to explore renewable alternatives to petroleum-based fuels, including enzymatic routes for hydrocarbon synthesis. Phylogenetically diverse species have long been recognized to produce hydrocarbons, but many of the enzymes responsible have been identified within the past decade. The enzymatic conversion of Cn chain length fatty aldehydes (or acids) to Cn-1 hydrocarbons, alkanes or alkenes, involves a C-C scission reaction. Surprisingly, the enzymes involved in hydrocarbon synthesis utilize non-heme mononuclear iron, dinuclear iron, and thiolate-ligated heme cofactors that are most often associated with monooxygenation reactions. In this review, we examine the mechanisms of several enzymes involved in hydrocarbon biosynthesis, with specific emphasis on the structural and electronic changes that enable this functional switch.

Contains fulltext : 215625.pdf (Publisher’s version ) (Open Access) Background and purpose - Periprosthetic joint infection (PJI) remains a devastating complication following total knee or total hip arthroplasty (TKA/THA). Nowadays, many studies focus on preventive strategies regarding PJI; however, the potential role of anesthesia in the development of PJI remains unclear.Patients and methods - All consecutive patients undergoing elective primary unilateral TKA or THA from January 2014 through December 2017 were included. Exclusion criteria included femoral fractures as the indication for surgery and previously performed osteosynthesis or hardware removal on the affected joint. Age, sex, BMI, ASA classification, type of arthroplasty surgery, type of anesthesia, duration of surgery, smoking status, and intraoperative hypothermia were recorded. Propensity score-matched univariable logistic regression analysis was used to control for allocation bias.Results - 3,909 procedures consisting of 54% THAs and 46% TKAs were available for analysis. 42% arthroplasties were performed under general anesthesia and 58% under spinal anesthesia. Early PJIs were observed in 1.7% of the general anesthesia group and in 0.8% in the spinal anesthesia group. The multivariable logistic regression model demonstrated an odds ratio for PJI of 2.0 (95% CI 1.0-3.7) after general anesthesia relative to the propensity score-matched patients who received spinal anesthesia.Interpretation - These results suggest a potential association between general anesthesia and early PJI. Future research using large-scale data is required to further elucidate this clinically relevant association.

Hardware removal preceding total hip arthroplasty may increase the risk of prosthetic joint infection (PJI). Whether hardware removal and total hip arthroplasty (THA) should be performed in a single- or two-stage procedure remains controversial. In this comparative retrospective study, the incidence of PJI following either single- or two-stage THA with hardware removal was assessed in a consecutive series. All patients that underwent THA preceded by hardware removal from January 2006 until March 2018 were retrospectively reviewed and checked for the occurrence of early PJI. Recognized risk factors for PJI at the time of surgery were evaluated and the incidence of early PJI was compared between one- and two-stage THA regarding hardware removal. 145 patients underwent THA and hardware removal (52 two-stage surgery and 93 single-stage surgery). There were no significant differences between both groups regarding pre-operative hemoglobulin levels, time interval between internal fixation and THA, antibiotic-loaded-cement use, BMI and ASA classification. Overall the incidence of early PJI was 6.9%. The incidence of PJI was 8.6% in the single-stage group versus 3.8% in the two-stage group (P = 0.234). Irrespective of single- or two-stage procedures, a high incidence of PJI was encountered. Despite non-significance, a trend towards a higher proportion of patients developing PJI after single-stage surgery was encountered. We recommend a two-stage surgical procedure regarding hardware removal and THA in patients that are expected to tolerate this surgical strategy. When considering a one-stage procedure, it should be preceded by a thorough pre-operative workup including joint aspiration and serum determination of inflammatory parameters. Multiple tissue samples should be obtained during hardware removal in either one- or two-stage procedures since the risk for development of PJI is relevant.

Background and purpose - Impaction bone grafting (IBG) is an established method in hip revision surgery to reconstruct loss of bone stock. There is limited knowledge concerning the actual bone remodelling process within the allograft. We investigated with repeated bone mineral density (BMD) measurements the biological process of bone remodelling in the allograft in vivo. We hypothesized that an initial decrease in BMD would be followed by an increase towards baseline values. Patients and methods - Dual-energy X-ray absorptiometry (DXA) was used to measure BMD values in 3 regions of interest (ROI) in 20 patients (average age at surgery 70 years, 11 males) after an acetabular reconstruction with IBG and a cemented cup. A postoperative DXA was used as baseline and DXA was repeated at 3 and 6 months and at 1 and 2 years. The Oxford Hip Score (OHS), the 12-Item Short Form Health Survey (SF12), and a 0 to 100 mm visual analogue scale (VAS) for pain and satisfaction were obtained simultaneously. Results - The overall mean BMD in the IBG regions increased significantly by 9% (95% CI 2-15) at 2 years' follow-up. In the cranial ROI BMD increased 14% (CI 6-22), whereas the BMD in the medial and caudal ROI showed an increase of 10% (CI 1-18) and 4% (CI -6-16), respectively. The OHS, SF12-mental, and VAS for pain all improved statistically significantly 2 years after surgery, with a mean VAS for satisfaction of 77 (CI 63-90) out of 100 points. The SF12-physical showed non-significant improvement. Interpretation - The BMD in the allograft gradually increased after IBG for acetabular reconstruction arthroplasties, particularly in the cranial ROI. An initial decrease in the BMD was not encountered. These BMD changes, as proxy measurements for bone remodeling, may indicate progressive apposition of vital new host bone in the grafted area.

Background and purpose — Impaction bone grafting (IBG) is an established method in hip revision surgery to reconstruct loss of bone stock. There is limited knowledge concerning the actual bone remodelling process within the allograft. We investigated with repeated bone mineral density (BMD) measurements the biological process of bone remodelling in the allograft in vivo. We hypothesized that an initial decrease in BMD would be followed by an increase towards baseline values. Patients and methods — Dual-energy X-ray absorptiometry (DXA) was used to measure BMD values in 3 regions of interest (ROI) in 20 patients (average age at surgery 70 years, 11 males) after an acetabular reconstruction with IBG and a cemented cup. A postoperative DXA was used as baseline and DXA was repeated at 3 and 6 months and at 1 and 2 years. The Oxford Hip Score (OHS), the 12-Item Short Form Health Survey (SF12), and a 0 to 100 mm visual analogue scale (VAS) for pain and satisfaction were obtained simultaneously. Results — The overall mean BMD in the IBG regions increased significantly by 9% (95% CI 2–15) at 2 years’ follow-up. In the cranial ROI BMD increased 14% (CI 6–22), whereas the BMD in the medial and caudal ROI showed an increase of 10% (CI 1–18) and 4% (CI –6–16), respectively. The OHS, SF12-mental, and VAS for pain all improved statistically significantly 2 years after surgery, with a mean VAS for satisfaction of 77 (CI 63–90) out of 100 points. The SF12-physical showed non-significant improvement. Interpretation — The BMD in the allograft gradually increased after IBG for acetabular reconstruction arthroplasties, particularly in the cranial ROI. An initial decrease in the BMD was not encountered. These BMD changes, as proxy measurements for bone remodeling, may indicate progressive apposition of vital new host bone in the grafted area.

The cytochromes P450 (P450s or CYPs) constitute a large heme enzyme superfamily, members of which catalyze the oxidative transformation of a wide range of organic substrates, and whose functions are crucial to xenobiotic metabolism and steroid transformation in humans and other organisms. The P450 peroxygenases are a subgroup of the P450s that have evolved in microbes to catalyze the oxidative metabolism of fatty acids, using hydrogen peroxide as an oxidant rather than NAD(P)H-driven redox partner systems typical of the vast majority of other characterized P450 enzymes. Early members of the peroxygenase (CYP152) family were shown to catalyze hydroxylation at the α and β carbons of medium-to-long-chain fatty acids. However, more recent studies on other CYP152 family P450s revealed the ability to oxidatively decarboxylate fatty acids, generating terminal alkenes with potential applications as drop-in biofuels. Other research has revealed their capacity to decarboxylate and to desaturate hydroxylated fatty acids to form novel products. Structural data have revealed a common active site motif for the binding of the substrate carboxylate group in the peroxygenases, and mechanistic and transient kinetic analyses have demonstrated the formation of reactive iron-oxo species (compounds I and II) that are ultimately responsible for hydroxylation and decarboxylation of fatty acids, respectively. This short review will focus on the biochemical properties of the P450 peroxygenases and on their biotechnological applications with respect to production of volatile alkenes as biofuels, as well as other fine chemicals.

In 2009, a 62-year-old woman with rheumatoid arthritis and a total hip arthroplasty (THA) on the right (uncemented Ti-6AL-7Nb stem combined with a Ti threaded cup, polyethylene inlay, and a 28-mm ceramic head; Zweymuller Alloclassic; Zimmer Orthopaedics, Warsaw, IN) implanted in 2006 presented with a left femoral neck fracture. A THA with a double-mobility acetabular system (Avantage Double-Mobility Acetabular System; Biomet, Warsaw, IN) was implanted. An uncemented titanium-niobium (Ti-6Al-7Nb) stem was used (Zweymuller Alloclassic; Zimmer) with a 12/14 mm trunnion combined with an XXL (+10.5 mm) 28-mm cobalt-chromium head with a 12/14 mm tapered bore (Biomet). The femoral head was introduced into the highly cross-linked, vitamin E-stabilized polyethylene bearing using a bearing press. An uncemented Ti HA-coated 52-mm acetabular shell was press-fitted in the socket and the large polyethylene femoral head was reduced into the metal articular surface. Postoperative recovery was uneventful, with normal wound healing. 2 years after implantation, the patient was referred to our center by her rheumatologist, since a soft tissue mass adjacent to the left THA had been diagnosed by ultrasound. A standard AP pelvic radiograph revealed adequate positioning of both hip implants without any signs of wear or osteolysis. Subsequent MARS-MRI scanning confirmed the presence of a 6 × 9 cm soft tissue mass at the posterolateral aspect of the left greater trochanter (Figure 1). There were no signs of any soft tissue reaction around the contralateral THA. Figure 1. Standard AP radiograph (panel A) and MARS-MRI scan (panel B) 2 years after implantation of the left THA with a double-mobility acetabular component. Note the adequate implant positioning and fixation (A) and a 6 × 9 cm soft tissue mass (B) at ... CRP was 68 mg/L and ESR was 53 mm/h; both were elevated, but this was possibly related to her rheumatoid arthritis. An inductively-coupled plasma mass spectrometer (ICP-MS) was used for evaluation of metal ion levels. Serum levels of chromium were below the detection level of 0.5µg/L, whereas cobalt serum levels were 5.7 µg/L. An aspirate of the hip joint was negative for bacterial or fungal growth. The patient was diagnosed as having a severe and early “adverse local tissue reaction” (ALTR) after a metal-on-polyethylene bearing THA with the taper as the potential source of the metal ion release. 2.5 years after implantation, a debulking procedure of the pseudotumor in combination with a 1-stage revision of the femoral component was performed. Perioperatively, extensive tissue necrosis and partial destruction of the abductor mechanism were found in the absence of any macroscopic signs of infection. The acetabular component was well fixed. Both the femoral trunnion and bore of the head showed signs of black debris (Figure 2). The femoral component was revised to a cemented polished straight stem (Exeter; Stryker, Allendale, NJ) with a ceramic 28-mm head (also Stryker) and a new double-mobility liner (Avantage Double-Mobility Acetabular System; Biomet). At the revision operation, 6 tissue samples were taken for bacterial culture according to our protocol. All 6 samples were negative for bacterial growth. Figure 2. A. Extensive necrosis at the greater trochanter area and destruction of the abductor mechanism. B. Debulking of large amounts of necrotic and fibrotic tissue from the periprosthetic region. C and D. Macroscopic signs of corrosion products at the bore ... The revision procedure was complicated by a deep infection that was unresponsive to lavage and prolonged antibiotic treatment. 2 months after revision, all components had to be removed, resulting in a (temporary) Girdlestone situation. The components were sent for retrieval analysis. Multiple samples of the periprosthetic tissues were processed in paraffin for routine histology. The histopathology of tissue samples revealed extensively necrotic material with only a focal cellular area of inflammatory cells containing macrophages, plasma cells, occasional foci of eosinophils, and several small perivascular lymphocytic aggregates (Figure 3). No polarizable materials or metallic debris were present in several tissue samples. The ALVAL score (Campbell et al. 2010) was 3 + 3 + 2 (= 8/10, moderate). Overall, the histological profile was consistent with an adverse immunological reaction in the absence of visible wear debris. Figure 3. A. Histological view of the soft tissue mass at the interface between the necrotic material (on the joint side) and inflammatory cells. Hematoxylin and eosin (HE), 40×. B. Enlargement of A with inflammatory cells consisting mainly of macrophages ... The profile of the ball taper was measured using a coordinate measuring machine (Legex 322; Mitotoyo, Aurora, IL). The dimensions of a perfect taper based on 6726 CMM points with a point spacing of 0.3 mm were determined using a least-squares method. The taper had an angle of 5 degrees, 47 min, and 34 s. A contour map was generated using the deviations of the CMM points from the fitting taper (Figure 4). The CMM results indicated uneven areas of contact, but the amount of material that had been removed through wear or corrosion could not be determined without knowing the initial form of the parts. However, in combination with the microanalysis described below, it appears that the small degree of texture and color changes was consistent with mild corrosion Figure 4. A. 2-dimensional graphical representation of the same profile. The outer diameter of the CMM map is the portion of the taper closest to the stem (labeled Rim) and the inner diameter of the CMM image corresponds to the inner surface (labeled Bottom). Areas ... The area of the stem trunnion that appeared discolored was examined by scanning electron microscopy (SEM) and energy-dispersive analysis of X-rays (EDAX) to identify the elements present. Organic material containing chromium and/or molybdenum consistent with corrosion products was identified within the machined grooves and in the deposited dark material outside the trunnion (Figure 5). Similar analysis performed on deparaffinized soft tissue sections failed to demonstrate any wear or corrosion products. Figure 5. Material present on the trunnion of the femoral component (panel A) was investigated by EDAX, revealing chromium (Cr), molybdenum (Mo), and oxygen (O) peaks consistent with corrosion products (panel B). The organic material within the grooves containing ...

STUDY DESIGN Prospective cohort. OBJECTIVE The purpose of this study was to evaluate changes in bone mineral density (BMD) in the intertransverse fusion mass as representative for the process of bone remodeling after spinal fusion. SUMMARY OF BACKGROUND DATA Intertransverse bone graft is frequently applied to facilitate bony fusion between 2 spinal levels. The biological process of bone graft remodeling leading to eventual fusion is, however, poorly understood. METHODS In 20 patients with a single-level instrumented posterolateral lumbar fusion for low-grade spondylolisthesis, radiographs, and clinical outcome scores (visual analogue scale for back and leg pain, Oswestry Disability Index, Short Form-36) were obtained. Locally harvested laminectomy bone was used as intertransverse bone graft. The BMD in selected "regions of interest" at both intertransverse fusion areas was assessed on days 4 and 3, after a period of 6 and 12 months after surgery using dual-energy x-ray absorptiometry scans. Eventual fusion status was assessed on computed tomographic scan at 12 months. RESULTS All clinical outcome scores significantly improved at the final follow-up (P < 0.05). Baseline BMD in both paraspinal fusion areas was expressed as 100%, which significantly decreased from 81% to 75% and 77% to 70% at 3 and 6 months, for regions of interest 1 and 2, respectively (P < 0.001). From 6 to 12 months, there was an increase in BMD from 90% to 80%, for regions of interest 1 and 2 (P = 0.296). On computed tomography scan a complete fusion was noticed in 70% of the patients. CONCLUSION Repeated dual-energy x-ray absorptiometry was able to elucidate the biological process of bone graft remodeling in the intertransverse fusion mass. An active bone remodeling process was quantified with profound resorption or demineralization of the graft during the first 6 months, followed by subsequent bone apposition and restoration of BMD at the final follow-up. No difference in trend in BMD change between patients with and without fusion could be established; however, no firm conclusions can be drawn from small patient numbers.

Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both g...

Copyright © Taylor & Francis 2004. ISSN 0001–6470. Printed in Sweden – all rights reserved. A 43-year-old man presented with persistent pain on the medial side of his left knee, 1 year after a bone-patellar tendon-bone autograft ACL reconstruction. Besides a dysfunctional ACL, earlier arthroscopy had already revealed a focal full-thickness chondral lesion (25 × 12 mm) of the medial femoral condyle (Figure 1A) and mild degenerative changes in the lateral compartment of the knee. The patient was offered a mosaicplasty of the medial femoral condyle. After a medial arthrotomy of the knee, 3 cylindrical osteochondral plugs (8 mm diameter) were harvested from the lateral throchlea (donor site) and transplanted to the chondral defect in the medial femoral defect (recipient site), using the mosaicplasty technique (Hangody et al. 1998, Bobic 1999, Hangody and Fules 2003, Horas et al. 2003). The donor site defects were each fi lled with a press-fi tted cylindrical osteo-periosteal plug obtained from the proximal tibia. It was hypothesized that these plugs would enhance healing of the subchondral bone and that the covering periosteum would enhance resurfacing of the donor site defects with fi brocartilagenous tissue. Initially, the patient’s symptoms clearly improved and a postoperative MRI showed restoration of the joint surface at the original chondral lesion in the medial condyle 3 months after surgery (Figure 1B). The 3 transplanted osteochondral plugs were still clearly visible in the subchondral bone, with signs of osseous integration. One plug appeared to have been placed rather too deeply, as seen from the step-off in the subchondral bone (Figure 1B, 2A). At the lateral aspect of the trochlea, the 3 donor site defects were also still clearly visible (Figure 1C). The osteo-periosteal plugs from the proximal tibia appeared to have remained in situ and some resurfacing of the defects had occurred. After 3 years the knee became symptomatic again, with pain and swelling. Radiographic evaluation revealed mild degenerative changes (Figure 1D). Conservative treatment was not accepted and a total knee arthroplasty was performed. This procedure eventually provided good-quality retrieval specimens for histological evaluation of a mosaicplasty.

Contains fulltext : 122991.pdf (Publisher’s version ) (Closed access) The physico-chemical properties of collagenous matrices may determine the tissue response after insertion into full-thickness articular cartilage defects. In this study, cross-linked type I and type II collagen matrices, with and without attached chondroitin sulfate, were implanted into full-thickness defects in the femoral trochlea of adolescent rabbits. The tissue response was evaluated 4 and 12 weeks after implantation by general histology and two semi-quantitative histological grading systems. Four weeks after implantation, type I collagenous matrices were completely filled with cartilage-like tissue. By contrast, type II collagenous matrices revealed predominantly cartilaginous tissue only at the superficial zone and at the interface of the matrix with the subchondral bone, leaving large areas of the matrix devoid of tissue. Attachment of chondroitin sulfate appeared to promote cellular ingrowth and cartilaginous tissue formation in both types of collagen matrices. Twelve weeks after implantation, the differences between the matrices were less pronounced. The deep parts of the subchondral defects were largely replaced by new bone with a concomitant degradation of the matrices. The original cartilage contours in defects with type I collagen-based matrices were repaired with fibro-cartilaginous tissue. Defects containing type II matrices showed an increase in the amount of superficial cartilage-like tissue. The original contour, however, was not completely restored in all animals, occasionally leaving a central depression or fissure. It is concluded that different types of collagen matrices induce different tissue responses in full-thickness articular cartilage defects. Type I collagen-based matrices are superior to guide progenitor cells from a subchondral origin into the defect. In type II collagen-based matrices cell migration is less, but invading cells are directed into a chondrocyte phenotype. Based on these observations it is suggested that a composite matrix consisting of a deep layer of type I collagen and a more superficial layer of type II collagen may be the matrix of choice for cartilage regeneration.

We studied whether bone mineral density (BMD) is preserved without significant femoral neck narrowing (FNN) after hip resurfacing (RHA) (n=42) versus small diameter metal-on-metal total hip arthroplasty (MoM THA) (n=40). In this three to five year randomized trial BMD was measured in the calcar with dual energy absorptiometry (DXA) preoperatively, at three and six months, one, two, three and five years postoperatively. Four additional BMD regions of interest (ROIs) and femoral neck narrowing (FNN) were measured after RHA. BMD in the calcar increased to 107% (P

In total hip arthroplasty (THA) the use of a polyethylene (PE) insert with a hooded rim can be considered to reduce dislocation risks. This benefit has to be balanced against the potential introduction of impingement of the femoral component on this rim. We present a case series of early acetabular revisions for excessive PE wear and acetabular bone defects from overuse of such a hooded rim insert. Twenty-eight patients with 34 consecutive early acetabular revisions were evaluated on failure mechanism. One type of implant was used in all cases. Standard pelvic radiographs and pre-operative CT scans were used to quantify PE wear, implant positioning and acetabular bone defects. An acetabular revision with impaction grafting was performed in all cases with a mean cup survival of ten years (range 1.3–19.3). No concurrent stem revisions were necessary. Overall implant positioning was adequate with a mean cup inclination of 45° (range 39–57) and anteversion of 25° (range eight to 45). The mean PE wear was 0.24 mm/year (range 0.00–1.17). The mean acetabular bone defect on pelvic CT scans was calculated as 352 mm² (range zero to 1107) and 369 mm² (range zero to 1300) in the coronal and transversal planes, respectively. A hooded acetabular insert was retrieved in all cases and profound PE wear, typically from the posterior hooded rim, was encountered. The use of hooded acetabular inserts may be considered to improve implant stability intra-operatively. This case series clearly presents that together with these devices, component impingement with concordant complications such as accelerated PE wear may be introduced. Standard use of these stabilizing inserts should thus be avoided.

Contains fulltext : 123012.pdf (Publisher’s version ) (Closed access) An increasing amount of interest is focused on the potential use of tissue-engineered articular cartilage implants, for repair of defects in the joint surface. In this perspective, various biodegradable scaffolds have been evaluated as a vehicle to deliver chondrocytes into a cartilage defect. This cell-matrix implant should eventually promote regeneration of the traumatized articular joint surface with hyaline cartilage. Successful regeneration can only be achieved with such a tissue-engineered cartilage implant if the seeded cells reveal an appropriate proliferation rate in the biodegradable scaffold together with the production of a new cartilage-specific extracellular matrix. These metabolic parameters can be influenced by the biochemical composition of a cell-delivery scaffold. Further elucidation of specific cell-matrix interactions is important to define the optimal biochemical composition of a cell-delivery vehicle for cartilage repair. In this in vitro study, we investigated the effect of the presence of cartilage-specific glycosaminoglycans in a type I collagen scaffold on the metabolic activity of seeded chondrocytes. Isolated bovine chondrocytes were cultured in porous type I collagen matrices in the presence and absence of covalently attached chondroitin sulfate (CS) up to 14 days. CS did indeed influence the bioactivity of the seeded chondrocytes. Cell proliferation and the total amount of proteoglycans retained in the matrix, were significantly higher (p < 0.001) in type I collagen scaffolds with CS. Light microscopy showed the formation of a more dense cartilaginous layer at the matrix periphery. Scanning electron microscopy revealed an almost complete surfacing of the initially porous surface of both matrices. Histology and reverse transcriptase PCR for various proteoglycan subtypes suggested a good preservation of the chondrocytic phenotype of the seeded cells during culture. The stimulatory potential of CS on both the cell-proliferation and matrix retention, turns this GAG into an interesting biochemical component of a cell-delivery scaffold for use in tissue-engineering articular cartilage.

Item does not contain fulltext Forty-eight unilateral hip resurfacing arthroplasty patients were evaluated for cobalt and chromium levels. The metal ion trend of 42 well-functioning patients was compared with six sub-optimal functioning patients. Median metal ion levels were significantly higher for the sub-optimal group. For the well-functioning implants, the percentage of patients with increasing cobalt/chromium levels between two consecutive time-intervals ('risers') gradually decreased from 90/86% (0-3 months) to 22/22% (24-36 months). The percentage of patients with increasing metal ion levels was higher in the sub-optimal group. The median absolute increase of this 'risers' subgroup was significantly lower for the well-functioning group at 12-24 months. Sub-optimal functioning MoM implants have a different metal ion trend than well-functioning implants, a higher chance of 'risers' and a larger absolute increase in time.

A unilateral facet dislocation noted in a 17-year-old boy after an axial cervical trauma proved to be an incidentally encountered preexisting lesion, most likely originating from a forceps delivery at birth. The surgical treatment initially considered was converted to a conservative approach, with full clinical recovery.

Total hip arthroplasty in young patients is associated with high failure rates and the best option for this demanding group of patients remains controversial. We report the long-term results of 73 consecutive Zweymüller total hip arthroplasties with a titanium threaded cup and a polyethylene insert in 67 patients aged under 50 years at the time of surgery (mean 43 years, range 23–49). Independent assessment was performed clinically and radiographically, and Kaplan-Meier analysis was used to determine survival for different end-points. Three hips were revised for septic loosening, three cups for aseptic loosening and one hip because of a periprosthetic fracture. Three patients (3 hips) died and seven patients (8 hips) were lost to radiographic follow-up without any reoperation. The mean follow-up was 17.5 (15–21) years and the mean HHS was 90 (52–100). Survival with an end-point of revision for any reason was 89% (95% C.I. 85–93) and of revision for aseptic loosening was 94% (C.I. 95–99) at 17 years. Zweymüller total hip arthroplasty with a titanium threaded cup and a polyethylene insert showed good long-term results, even in this group of young patients.

Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both groups at 24 months. Cobalt concentrations were statistically significantly higher for R patients only at 3 and 6 months. Chromium levels remained significantly higher for R patients until 24 months. No pseudotumors were encountered in either group. One R patient was revised for early aseptic loosening and in 2 C patients a cup insert was exchanged for recurrent dislocation. Interpretation R patients scored higher on UCLA, OHS, and satisfaction at some time points; however, as for the UCLA, preoperative levels were already in favor of R. The differences, although statistically significant, were of minor clinical importance. Chromium blood levels were statistically significantly higher for R patients at all follow-up measurements, whereas for cobalt this was only observed up to 6 months. The true value of resurfacing hip arthroplasty over conventional metal-on-metal hip arthroplasty will be determined by longer follow-up and a possible shift of balance between their respective (dis)advantages.

Background and purpose Hip resurfacing arthroplasty (RHA) is done in patients who often have a high preference for the method. This preference can influence the clinical outcome and satisfaction. We evaluated the potential influence of this preference bias. Patients and methods From an ongoing randomized trial comparing RHA with total hip arthroplasty, 28 consecutive patients (28 hips) who had been allocated to an RHA were characterized as the “randomized” group. 22 other patients (24 hips) who had refused participation and had especially requested an RHA were characterized as the “preference” group. Harris hip score (HHS), Oxford hip score (OHS), University of California at Los Angeles activity scale (UCLA), Short Form 12 (SF-12), and visual analog scale satisfaction score (VAS) were assessed in both groups. Results Both groups had a high implant satisfaction score (97/100 for the “preference” group and 93/100 for the “randomized” group) at 12 months. The HHS, OHS, and UCLA were similar at baseline and also revealed a similar improvement up to 12 months (p < 0.001). Regarding the SF-12, the “preference” group scored lower on the mental subscale preoperatively (p = 0.03), and there was a greater increase after 12 months (p = 0.03). Interpretation We could not show that there was any influence of preference on satisfaction with the implant and early clinical outcome in patients who underwent RHA. The difference in mental subscale scores between groups may still indicate a difference in psychological profile.

Clinical practice guidelines are being used in many countries throughout the world to improve the quality of patient care. The Dutch Orthopaedic Association has a long tradition of guideline develo...

Contains fulltext : 95878.pdf (Publisher’s version ) (Open Access) PURPOSE: The aim of this study was to evaluate subsidence tendency, surface congruency, chondrocyte survival and plug incorporation after osteochondral transplantation in an animal model. The potential benefit of precise seating of the transplanted osteochondral plug on the recipient subchondral host bone ('bottoming') on these parameters was assessed in particular. METHODS: In 18 goats, two osteochondral autografts were harvested from the trochlea of the ipsilateral knee joint and inserted press-fit in a standardized articular cartilage defect in the medial femoral condyle. In half of the goats, the transplanted plugs were matched exactly to the depth of the recipient hole (bottomed plugs; n = 9), whereas in the other half of the goats, a gap of 2 mm was left between the plugs and the recipient bottom (unbottomed plugs; n = 9). After 6 weeks, all transplants were evaluated on gross morphology, subsidence, histology, and chondrocyte vitality. RESULTS: The macroscopic morphology scored significantly higher for surface congruency in bottomed plugs as compared to unbottomed reconstructions (P = 0.04). However, no differences in histological subsidence scoring between bottomed and unbottomed plugs were found. The transplanted articular cartilage of both bottomed and unbottomed plugs was vital. Only at the edges some matrix destaining, chondrocyte death and cluster formation was observed. At the subchondral bone level, active remodeling occurred, whereas integration at the cartilaginous surface of the osteochondral plugs failed to occur. Subchondral cysts were found in both groups. CONCLUSIONS: In this animal model, subsidence tendency was significantly lower after 'bottomed' versus 'unbottomed' osteochondral transplants on gross appearance, whereas for histological scoring no significant differences were encountered. Since the clinical outcome may be negatively influenced by subsidence, the use of 'bottomed' grafts is recommended for osteochondral transplantation in patients.

Contains fulltext : 96098.pdf (Publisher’s version ) (Closed access) Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure, and both serum and whole blood measurements are used in clinical practice. This study provides a guideline for interpretation of metal ion analysis in clinical practice. In a prospective trial comparing hip resurfacing (HR) with a conventional metal-on-metal (MoM) total hip arthroplasty (THA) cobalt and chromium levels were determined for whole blood and serum in 343 paired samples at regular intervals up to 24 months postoperatively. Cobalt whole blood and serum levels increased significantly after both procedures. Cobalt concentrations were significantly higher for the HR group compared to the THA group, at 3, 6 and 12 months, for whole blood and serum. At 24 months cobalt levels decreased and differences between HR and THA were no longer significant. In contrast, chromium whole blood levels remained significantly higher for HR until 24 months. Whole blood and serum levels could not be used interchangeably. The mean differences for cobalt and chromium between blood and serum values were +0.13 microg/L and -0.91 microg/L respectively. Regression analysis provided a formula for conversion from serum to blood of 0.34+[0.88*Co serum] for cobalt and 0.14 + [0.58*Cr serum] for chromium, with an acceptable prediction error below +/-1.0 microg/L. Cobalt and chromium levels were significantly higher for HR versus THA, especially during the run-in phase of one year. Overall, the metal ion levels were well below 5 microg/L. We cannot recommend the use of whole blood over serum measurements or vice versa. The provided conversion formula between whole blood and serum in combination with the presented practical guidelines may be useful for clinical practice.

To evaluate the short-term outcome of osteochondritis dissecans (OCD) treated with mosaic osteochondral autograft transplantation (OAT), 7 male patients (mean age 33.4) with 8 OCD lesions on the lateral border of the medial femoral condyle were prospectively followed. Patients were evaluated by the International Knee Documention Committee (IKDC) score and the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaires preoperatively, at 6 months and 1 year after surgery. MRI evaluation using the modified Sanders score was performed at 1-year follow-up. The IKDC subjective score and all subscales of the KOOS improved significantly. MRI evaluation showed good surface congruency, no oedema or protuberance of the osteocartilaginous cylinders, good similarity of cartilage thickness and a non-complete osseous integration. With the small numbers of patients available, no correlation could be found between MRI findings, percentage of defect coverage and patient satisfaction. Mosaic OAT appeared in this study as a valid treatment option in selected cartilage defects. OCD lesions improved significantly following osteochondral transplantation. The limitations of this technique are the number and size of the plugs needed to repair the defect. Future research should focus on identifying the appropriate choice of operative treatment for well defined subtypes of articular cartilage lesions, rather than searching for one superior technique for all.

Contains fulltext : 79990.pdf (Publisher’s version ) (Closed access) BACKGROUND: Operation of hip resurfacing prosthesis is a technically demanding procedure accompanied by a learning curve. To our knowledge no objective data on this learning curve are available in the literature. METHODS: For the first 40 resurfacing hip prostheses implanted by a single-surgeon radiographic 'learning curve' analysis was performed. Optimal implant positioning on preoperative digital templating was compared with the eventual implant position postoperatively, measured by six establishes radiographic parameters and compared for four chronological cohorts of patients. RESULTS: A learning curve was clearly present and an optimal result was established in the last cohort. Pitfalls were a relatively steep cup position initially and a stem position in the posterior 1/3 of the collum. Besides marginal medialization a fully anatomic reconstruction of the center of rotation was achieved. CONCLUSION: In total hip resurfacing one should recognize the presence of a learning curve. This learning curve appears to be acceptable and a reproducible optimal implant positioning can be achieved quickly.

Contains fulltext : 70643.pdf (Publisher’s version ) (Open Access) Osteochondral transplantation is a successful treatment for full-thickness cartilage defects, which without treatment would lead to early osteoarthritis. Restoration of surface congruency and stability of the reconstruction may be jeopardized by early mobilization. To investigate the biomechanical effectiveness of osteochondral transplantation, we performed a standardized osteochondral transplantation in eight intact human cadaver knees, using three cylindrical plugs on a full-thickness cartilage defect, bottomed on one condyle, unbottomed on the contralateral condyle. Surface pressure measurements with Tekscan pressure transducers were performed after five conditions. In the presence of a defect the border contact pressure of the articular cartilage defect significantly increased to 192% as compared to the initially intact joint surface. This was partially restored with osteochondral transplantation (mosaicplasty), as the rim stress subsequently decreased to 135% of the preoperative value. Following weight bearing motion two out of eight unbottomed mosaicplasties showed subsidence of the plugs according to Tekscan measurements. This study demonstrates that a three-plug mosaicplasty is effective in restoring the increased border contact pressure of a cartilage defect, which may postpone the development of early osteoarthritis. Unbottomed mosaicplasties may be more susceptible for subsidence below flush level after (unintended) weight bearing motion.

Intraplaque neovascularization is linked to plaque instability and thought to be stimulated by hypoxia. However, hypoxia has not been demonstrated yet in human atherosclerosis. The hypoxia marker pimonidazole was administrated intravenously 2 hours prior to carotid endarterectomy in 6 symptomatic patients to evaluate the presence of hypoxia. Subsequent immunohistochemistry of the operatively removed atherosclerotic plaques demonstrated the presence of hypoxia, especially in the macrophage-rich center of the lesions. Notably, two hypoxic gradients were observed: hypoxia was very strong in the center of the plaque, but almost absent close to the main artery lumen and in the media. hypoxia was most intense in segments with advanced atheroma and almost absent in segments containing only diffuse intimal thickening. Hypoxia strongly correlated with CD68 immunoreactivity (ρ= 0.7, p=0.000), neovascularization (ρ= 0.6, p=0.000) and the presence of a thrombus (ρ= 0.4, p=0.009). In addition, hypoxia co-localized with expression of HIF1α and VEGF . To exclude that pimonidazole immunoreactivity in the atherosclerotic plaque was the result of surgery-induced ischemia, arterial wall segments were collected at two time-points: directly after incision of the carotid artery and directly following excision of the plaque. Pimonidazole immunoreactivity in these two pieces was not different, suggesting that hypoxia and pimonidazole adducts were already present in the plaques before surgery . To show that pimonidazole reactivity was hypoxia-specific and independent of reactive oxygen species, human THP-1 macrophages were exposed to normoxia (20% O 2 ), hypoxia (0.2% O 2 ) and/or H 2 O 2 (100 μM) in the presence of pimonidazole. Indeed, flow cytometry only showed pimonidazole-positive cells after hypoxic exposure. This is the first study proving direct evidence of the existence of hypoxia in advanced human atherosclerotic lesions, most prominently in the macrophage-rich center. Also, hypoxia was associated with the expression of HIF1α, VEGF and intraplaque microvessels, suggesting its involvement in the regulation of human intraplaque neovascularization.

In an attempt to reduce health care expenses, regulated competition between health care providers has been introduced in The Netherlands. As for total hip and knee arthroplasties, health care providers have to publish their prices to make them available for the insurance companies and the public. Eventually, competition between health care providers should result in optimal care for lower prices. The purpose of this study was to define the patients' consciousness of the overall costs and specialist's fee for a total knee arthroplasty. Thirty-nine patients with a recent total knee arthroplasty were asked to estimate the total costs and the surgeon's fee of this procedure. The average overall cost of a total knee arthroplasty in our hospital was Euro 11.500. The orthopaedic surgeon's fee represents a non-negotiable 5% of these total costs. The mean estimate of the overall costs of a total knee arthroplasty by the patients was Euro 10.000 (range: Euro 600 to Euro 55.000). Only 26% of the patients (n = 10) gave an estimate within the accepted "correct" range of Euro 8.500 to Euro 14.500. The surgeon's fee was estimated at 32% (range: 5% to 75%) of the total costs and a majority reckoned the actual fraction of 5% was low. Patients have a poor notion of the overall costs of a total knee arthroplasty and strongly overestimate the specialist's fee. Whether the introduction of budget competition in health care may actually result in a decrease in health care costs remains to be seen.

Contains fulltext : 50123.pdf (Publisher’s version ) (Open Access) BACKGROUND: Osteochondral autologous transplantation is used for the treatment of full-thickness articular cartilage lesions of a joint. Press-fit stability is an important factor for good survival of the transplanted plugs. MATERIAL AND METHODS: 36 plugs of three different lengths were transplanted in fresh-frozen human knees. On one condyle, 3 plugs were exactly matched to the depth of the recipient site ("bottomed" plugs) and on the opposite condyle 3 plugs were 5 mm shorter than the depth of the recipient site ("unbottomed" plugs). Plugs were left protruding and then pushed in until flush, and then to 2 mm below flush level, using a loading apparatus. RESULTS: Longer plugs needed higher forces to begin displacement. At flush level, bottomed plugs needed significantly higher forces than unbottomed plugs to become displaced below flush level (mean forces of 404 N and 131 N, respectively). Shorter bottomed plugs required higher forces than longer bottomed ones. INTERPRETATION: Bottomed plugs generally provide much more stability than unbottomed ones. Short bottomed plugs are more stable than long bottomed plugs. Thus, in clinical practice it is advisable to use short bottomed plugs. If, however, unbottomed plugs are still chosen, the longer the plug the higher the resulting stability will be because of higher frictional forces.

The authors retrospectively evaluated 30 patients with an anterior cervical interbody fusion for cervical spondylosis or disc herniation. Open box carbon fiber cages were used at 45 levels. The visual analogue scales (VAS), respectively for neck and for arm pain, and the neck disability index (NDI) improved significantly (p0.001). Fusion occurred in 87% of the operated levels. Subsidence of the cages into the endplates was observed in 49% of the operated levels, which increased to 54% when more levels were fused. No correlation between subsidence of the cage and clinical outcome or radiographic fusion was established. The authors conclude that cervical discectomy and interbody fusion using an open box carbon fiber cage is a satisfactory treatment option for degenerative cervical disease causing neck pain and radiculopathy, despite the relatively high percentage of subsidence of this cage.

Contains fulltext : 142093.pdf (Publisher’s version ) (Closed access) INTRODUCTION: Autologous osteochondral transplantation is a popular treatment for articular cartilage lesions in the knee joint. The donor defect is commonly left empty and remains a matter of concern. MATERIALS AND METHODS: In 20 knees of 10 goats, we created a standardised donor defect in the knee. In the control group the defects were left empty, whereas in two other groups a bone plug from the proximal tibia was press-fitted into the defect with or without a covering periosteal layer. RESULTS: Histological evaluation after 8 and 16 weeks showed that relatively rapid osteoclastic resorption of the bone plug occurred. Defects were mainly filled with fibrous tissue, and collapse of the adjacent bone and cartilage was visible, especially when the defects were left empty. Occasionally, some consolidation of the graft to the host bone could be detected, and in some samples periosteal chondrogenesis was present. CONCLUSION: Our findings suggest that transplantation of a tibial bone plug with covering periosteum to the donor defect in a cartilage transplantation procedure does not have any additional value in an attempt to minimise the damage at the donor site. The observed resorption of the bone plug and the collapse of the adjacent joint margin remain a matter of concern with this technique.