Analysis of free cisplatin in microdialysates and plasma ultrafiltrate by liquid chromatography-tandem mass spectrometry.

Cisplatin is a potent cytotoxic agent used in the treatment of various malignancies and exerts its antitumor effect through malignant cell DNA damage and apoptosis induction. Evaluation of systemic delivery of cisplatin is important in optimization of cisplatin treatment. However, accurate quantification of systemic cisplatin is challenging due to its various forms in circulation. This study aimed to develop a sensitive (LOQ < 0.1 µg/mL) and precise Ultra Performance Liquid Chromatography (UPLC) - Tandem Mass Spectrometry (MS/MS) method for quantifying free cisplatin in microdialysates and plasma. Furthermore the aim was to compare free cisplatin concentrations measured in standard plasma samples with those obtained from intravenous microdialysis catheters in a porcine model. The method developed utilizes dichloro(ethylenediamine)platinum(II) as an internal standard that co-elutes with cisplatin, ensuring precise correction for ion suppression/enhancement effects. The method was validated, demonstrating linearity up to 100 µg/mL and good intermediate precision (CV% < 6 %) in the range of 1.0-100 µg/mL, with an LOQ of 0.03 µg/mL. The pharmacokinetic parameters (AUC0-last, Cmax, T1/2, and Tmax) showed no significant differences between the two sampling methods. This validated LC-MS/MS method provides a reliable tool for quantifying systemic free cisplatin concentrations, facilitating future systemic and local pharmacokinetic evaluations for optimization of cisplatin-based cancer treatments.

Patients with knee osteoarthritis can be divided into subgroups based on tibiofemoral joint kinematics of gait - an exploratory and dynamic radiostereometric study.

OBJECTIVE: Patients with advanced knee osteoarthritis (KOA) frequently alter their gait patterns in an attempt to alleviate symptoms. Understanding the underlying pathomechanics and identifying KOA phenotypes are essential to improve treatments. We investigated kinematics in patients with KOA to identify subgroups of homogeneous knee joint kinematics. METHOD: A total of 66 patients with symptomatic KOA scheduled for total knee arthroplasty and 15 age-matched healthy volunteers with asymptomatic, non-arthritic knees were included. We used k-means clustering to divide patients into subgroups based on dynamic radiostereometry-assessed tibiofemoral joint kinematics. Clinical characteristics such as knee ligament lesions and KOA scores were graded by magnetic resonance imaging and radiographs, respectively. RESULTS: We identified four clusters that were supported by clinical characteristics. The flexion group (n = 20) consisted primarily of patients with medial KOA. The abduction group (n = 17) consisted primarily of patients with lateral KOA. The anterior draw group (n = 10) was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the highest KOA score. The external rotation group (n = 19) primarily included patients with medial collateral and posterior cruciate ligament lesions. CONCLUSION: Based on tibiofemoral gait patterns, patients with advanced KOA can be divided into four subgroups with specific clinical characteristics and different KOA-affected compartments. The findings add to our understanding of how knee kinematics may affect the patient's development of different types of KOA. This may inspire improved and more patient-specific treatment strategies in the future.

Double-dose cefuroxime concentrations in bone, synovial fluid of the knee joint and subcutaneous adipose tissue-A randomised porcine microdialysis study.

This study evaluated target tissue concentrations of double dose cefuroxime administered intravenously as either one 15 min infusion of 3000 mg (Group 1) or two single 15 min infusions of 1500 mg administered 4 h apart (Group 2). Sixteen pigs were randomised into two groups of eight. Cortical and cancellous bone, synovial fluid of the knee joint and subcutaneous adipose tissue concentrations were measured based on sampling via microdialysis. Plasma samples were collected as a reference. Comparison of the groups was based on time with concentrations above relevant minimal inhibitory concentrations (fT>MIC) of 4 µg/mL. The mean time fT>MIC (4 µg/mL) across compartments was longer for Group 2 (280-394 min) than for Group 1 (207-253 min) (p<0.01). Cortical bone showed a tendency towards longer fT>MIC (4 µg/mL) in Group 2 (280 min) than in Group 1 (207 min) (p = 0.053). Within 50 min after administration, the mean concentration of 4 µg/mL was reached in all compartments for both groups. The mean concentrations decreased below 4 µg/mL after approximately 4 h (Group 1) and 3 h (Group 2) from initiation of administration (time zero). During an 8 h interval, double-dose cefuroxime administered as 2 × 1500 mg with a 4 h interval provides longer time above MIC breakpoint for Staphylococcus aureus (4 µg/mL) than a single bolus of 3000 mg cefuroxime. To maintain sufficient tissue concentrations during longer surgeries, re-administration of cefuroxime (1500 mg) should be considered 3 h after the first administration.

Cardiovascular events in patients undergoing hip fracture surgery treated with remote ischaemic preconditioning: 1-year follow-up of a randomised clinical trial.

Remote ischaemic preconditioning reduces the risk of myocardial injury within 4 days of hip fracture surgery. We aimed to investigate the effect of remote ischaemic preconditioning on the incidence of major adverse cardiovascular events 1 year after hip fracture surgery. We performed a phase-2, multicentre, randomised, observer-blinded, clinical trial between February 2015 and September 2017. We studied patients aged ≥ 45 years with a hip fracture and a minimum of one cardiovascular risk factor. Patients were allocated randomly to remote ischaemic preconditioning applied just before surgery or no treatment (control group). Remote ischaemic preconditioning was performed on the upper arm with a tourniquet in four cycles of 5 min ischaemia and 5 min reperfusion. Primary outcome was the occurrence of major adverse cardiovascular events within 1 year of surgery. A total of 316 patients were allocated randomly to the remote ischaemic preconditioning group and 309 patients to the control group. Major adverse cardiovascular events occurred in 43 patients (13.6%) in the remote ischaemic preconditioning group compared with 51 patients (16.5%) in the control group (adjusted hazard ratio (95%CI) 0.83 (0.55-1.25); p = 0.37). Fewer patients in the remote ischaemic preconditioning group had a myocardial infarction (11 (3.5%) vs. 22 (7.1%); hazard ratio (95%CI) 0.48 (CI 0.23-1.00); p = 0.04). Remote ischaemic preconditioning did not reduce the occurrence of major adverse cardiovascular events within 1 year of hip fracture surgery. The effect of remote ischaemic preconditioning on clinical cardiovascular outcomes in non-cardiac surgery needs confirmation in appropriately powered randomised clinical trials.

Similar patient positioning: A key factor in follow-up studies when using model-based radiostereometric analysis of the hip.

INTRODUCTION: Despite protocols, patients are not positioned exactly alike at radiostereometric (RSA) follow-up examinations, and it is unknown how much variation is tolerable. We report precision for optimal and extreme position differences from a phantom hip-study, and clinical precision of hip-RSA. METHODS: A femoral stem with 3 bead-towers was fixed in a saw bone with bone-markers (phantom), and series of RSA examinations within optimal (5 × 5 cm and 5°) and extreme (20 × 30 cm and 30°) phantom positions were obtained. Double-examination RSA of 12 patients with the same femoral stem type were analyzed. Both model-based (CAD) and marker-based (MM) analysis was used. Precision was reported as standard deviation of differences. RESULTS: Precision for translations in the optimal and extreme phantom position were below 0.06 mm and 0.02 mm for MM analysis, and below 0.05 mm and 0.18 mm for CAD analysis, respectively. Precision for rotations in the optimal and extreme phantom rotation were below 0.18° and 0.26° for MM analysis, and below 0.34° and 0.52° for CAD analysis, respectively. Clinical precision was 0.29 mm and 0.44° for MM analysis, and 0.40 mm and 1.59° for CAD analysis. CONCLUSION: Extreme differences in patient position during RSA examination negatively affects precision, and CAD model-analysis was more sensitive than MM analysis. Longitudinal translation and rotation about the long stem-axis are the effect parameters which are most affected by position and rotation changes, and also the best indicators of implant loosening. IMPLICATIONS FOR PRACTICE: Based on our research, we recommend that similar patient positioning between follow-up RSA examinations is debated and prioritized.

Marker free model-based radiostereometric analysis for evaluation of hip joint kinematics: A validation study.

OBJECTIVES: To validate the precision of digitally reconstructed radiograph (DRR) radiostereometric analysis (RSA) and the model-based method (MBM) RSA with respect to benchmark marker-based (MM) RSA for evaluation of kinematics in the native hip joint. METHODS: Seven human cadaveric hemipelves were CT scanned and bone models were segmented. Tantalum beads were placed in the pelvis and proximal femoral bone. RSA recordings of the hips were performed during flexion, adduction and internal rotation. Stereoradiographic recordings were all analyzed with DRR, MBM and MM. Migration results for the MBM and DRR with respect to MM were compared. Precision was assessed as systematic bias (mean difference) and random variation (Pitman's test for equal variance). RESULTS: A total of 288 dynamic RSA images were analyzed. Systematic bias for DRR and MBM with respect to MM in translations (p < 0.018 mm) and rotations (p < 0.009°) were approximately 0. Pitman's test showed lower random variation in all degrees of freedom for DRR compared with MBM (p < 0.001). CONCLUSION: Systematic error was approximately 0 for both DRR or MBM. However, precision of DRR was statistically significantly better than MBM. Since DRR does not require marker insertion it can be used for investigation of preoperative hip kinematics in comparison with the postoperative results after joint preserving hip surgery. Cite this article: L. Hansen, S. De Raedt, P. B. Jørgensen, B. Mygind-Klavsen, B. Kaptein, M. Stilling. Marker free model-based radiostereometric analysis for evaluation of hip joint kinematics: A validation study. Bone Joint Res 2018;7:379-387. DOI: 10.1302/2046-3758.76.BJR-2017-0268.R1.

Validation of static and dynamic radiostereometric analysis of the knee joint using bone models from CT data.

OBJECTIVES: Static radiostereometric analysis (RSA) using implanted markers is considered the most accurate system for the evaluation of prosthesis migration. By using CT bone models instead of markers, combined with a dynamic RSA system, a non-invasive measurement of joint movement is enabled. This method is more accurate than current 3D skin marker-based tracking systems. The purpose of this study was to evaluate the accuracy of the CT model method for measuring knee joint kinematics in static and dynamic RSA using the marker method as the benchmark. METHODS: Bone models were created from CT scans, and tantalum beads were implanted into the tibia and femur of eight human cadaver knees. Each specimen was secured in a fixture, static and dynamic stereoradiographs were recorded, and the bone models and marker models were fitted to the stereoradiographs. RESULTS: Results showed a mean difference between the two methods in all six degrees of freedom for static RSA to be within -0.10 mm/° and 0.08 mm/° with a 95% limit of agreement (LoA) ranging from ± 0.49 to 1.26. Dynamic RSA had a slightly larger range in mean difference of -0.23 mm/° to 0.16 mm/° with LoA ranging from ± 0.75 to 1.50. CONCLUSIONS: In a laboratory-controlled setting, the CT model method combined with dynamic RSA may be an alternative to previous marker-based methods for kinematic analyses.Cite this article: K. Stentz-Olesen, E. T. Nielsen, S. De Raedt, P. B. Jørgensen, O. G. Sørensen, B. L. Kaptein, M. S. Andersen, M. Stilling. Validation of static and dynamic radiostereometric analysis of the knee joint using bone models from CT data. Bone Joint Res 2017;6:376-384. DOI: 10.1302/2046-3758.66.BJR-2016-0113.R3.

Is structural hydroxyapatite tricalcium-phosphate graft or tricortical iliac crest autograft better for calcaneal lengthening osteotomy in childhood? interim results from a randomised, controlled non-inferiority study.

AIMS: To compare the structural durability of hydroxyapatite-tricalcium phosphate (HATCP) to autologous iliac crest bone graft in calcaneal lengthening osteotomy (CLO) for pes planovalgus in childhood. PATIENTS AND METHODS: We present the interim results of ten patients (HATCP, n = 6 and autograft, n = 5) with a mean age of 11.5 years (8.2 to 14.2) from a randomised controlled non-inferiority trial with six months follow-up. The primary outcome was the stability of the osteotomy as measured by radiostereometric analysis. A non-inferiority margin of ≤ 2 mm osteotomy compression was set. RESULTS: At six months the data showed that the osteotomy had been compressed by a mean 1.97 mm (99.8% confidence interval -1.65 to 5.60) more in the HATCP group than in the autograft group. Migration of the CLO grafted with HATCP stabilised at six months rather than at six weeks with autograft. CONCLUSION: This is the first randomised trial to compare the efficacy of HATCP graft with autograft in terms of stability of CLO in children. Because of problems with the HATCP the trial was stopped. We do not recommend HATCP graft in its current structure for use in unfixed CLOs. Cite this article: Bone Joint J 2016;98-B:1554-62.

Does a titanium sleeve reduce the frequency of pseudotumors in metal-on-metal total hip arthroplasty at 5-7years follow-up?

INTRODUCTION: Little is known about pseudotumor frequency and risk factors for pseudotumor formation among different types of metal-on-metal (MoM) hip arthroplasties. A lower release of chromium and cobalt have been reported in MoM hip arthroplasties with a titanium sleeve compared to MoM designs without a titanium sleeve, but yet it is unknown whether a titanium sleeve reduces the pseudotumor frequency. We conducted a cross-sectional study to investigate: 1) pseudotumor frequency, 2) risk factors of pseudotumor formation 3) and correlations between pseudotumors, serum metal-ions, implant position, and clinical symptoms. HYPOTHESIS: We expected a lower pseudotumor frequency in MoM hip articulation with a titanium sleeve than reported in MoM hip articulation designs using chromium-cobalt sleeve. MATERIALS AND METHOD: A consecutive series of 41 patients/49 hips (31 males), mean age 52 (28-68) years, participated in a 5.5±0.5 (4-6.5) year follow-up study of their M2a_Magnum hip articulation (Biomet Inc., Warsaw, Indiana, USA). Patients were evaluated with magnetic resonance imaging (MRI), measurements of serum metal-ions, plain radiographs, and clinical outcome measures of Harris Hip Score (HHS) and Oxford Hip Score (OHS). RESULTS: Eighteen of 47 hips (38%) had MRI-verified pseudotumors, all cystic, with a mean dimension of 10.6×25.6×41mm. Digital measurements on plain radiographs revealed a higher cup anteversion in patients with a pseudotumor of mean 28.4°±5.05° compared to mean 23.5°±6.5° in patients without a pseudotumor (P=0.009). Serum metal-ion concentrations, acetabular cup inclination and measures of HHS and OHS were similar between patients with and without a pseudotumor (P>0.46). CONCLUSION: At 5.5±0.5years after surgery, MRI-verified cystic pseudotumors were frequently observed in M2a_Magnum hip articulations despite the use of titanium sleeves. The pseudotumors were related to high cup anteversion angles but not related to high serum metal-ions or clinical symptoms. LEVEL OF EVIDENCE: IV: cross-sectional study.

Precise and feasible measurements of lateral calcaneal lengthening osteotomies by radiostereometric analysis in cadaver feet.

OBJECTIVES: Lengthening osteotomies of the calcaneus in children are in general grafted with bone from the iliac crest. Artificial bone grafts have been introduced, however, their structural and clinical durability has not been documented. Radiostereometric analysis (RSA) is a very accurate and precise method for measurements of rigid body movements including the evaluation of joint implant and fracture stability, however, RSA has not previously been used in clinical studies of calcaneal osteotomies. We assessed the precision of RSA as a measurement tool in a lateral calcaneal lengthening osteotomy (LCLO). METHODS: LCLO was performed in six fixed adult cadaver feet. Tantalum markers were inserted on each side of the osteotomy and in the cuboideum. Lengthening was done with a plexiglas wedge. A total of 24 radiological double examinations were obtained. Two feet were excluded due to loose and poorly dispersed markers. Precision was assessed as systematic bias and 95% repeatability limits. RESULTS: Systematic bias was generally below 0.10 mm for translations. Precision of migration measurements was below 0.2 mm for translations in the osteotomy. CONCLUSION: RSA is a precise tool for the evaluation of stability in LCLO. Cite this article: Bone Joint Res 2015;4:78-83.

Block-step asymmetry 5 years after large-head metal-on-metal total hip arthroplasty is related to lower muscle mass and leg power on the implant side.

BACKGROUND: Metal-on-metal articulations mimic the human hip anatomy, presumably lower dislocation rates and increase the range-of-motion. This study aims to measure the muscle mass and power of both legs in patients with unilateral metal-on-metal total hip arthroplasty, and to investigate their effect on block-step test, spatio-temporal gait parameters and self-reported function. METHODS: Twenty-eight patients (7 women), mean age 50 (28-68) years, participated in a 5-7 year follow-up. Patients had received one type unilateral large-head metal-on-metal total hip articulation, all of which were well-functioning at follow-up. Mean muscle mass was measured by the total-body Dual energy X-ray Absorption scans, and muscle power was measured in a leg extensor power rig. Block-step test and spatio-temporal gait parameters were measured with an inertial measurement unit. Self-reported function was assessed by the Hip Disability and Osteoarthritis Outcome Score. FINDINGS: We found a significant difference between the mean muscle mass of the implant-side leg and the non-implant-side leg in hip, thigh and calf areas (P<0.008) and in mean muscle power (P=0.025). Correlations between mean muscle mass and mean muscle power were significant for both the implant-side leg (r=0.45, P=0.018) and the non-implant-side leg (r=0.51, P=0.007). The difference in mean muscle power between legs correlated with block-step test asymmetry during ascending (r=0.40, P=0.047) and descending (r=0.53, P=0.006). Correlations between self-reported function and power of the implant-side leg were not significant. INTERPRETATIONS: Young patients have not fully regained muscle mass, muscle power and function 5-7 years after metal-on-metal total hip arthroplasty.

Patients with metal-on-metal articulation in trapeziometacarpal total joint arthroplasty may have elevated serum chrome and cobalt.

Serum chrome and cobalt was measured in 50 patients with trapeziometacarpal total joint replacement with metal-on-metal articulation and compared with serum chrome and cobalt values in 23 patients with trapeziometacarpal total joint replacement with metal-on-polyethylene articulation. In 10 of 50 (20%) patients with metal-on-metal articulation, slightly elevated serum chrome or cobalt values were found compared with only one in 23 (4%) patients with metal-on-polyethylene articulation. All metal values were lower than accepted 'normal values' for metal-on-metal hip arthroplasty and so considered not to be a general health risk. However, the mean disabilities of the arm, shoulder and hand (DASH) score was 24 in patients with elevated serum chrome or cobalt compared with 10 in patients with normal metal values (p < 0.05) suggesting a local clinical effect of the elevated serum chrome or cobalt values. We recommend that patients with trapeziometacarpal total joint replacement with metal-on-metal articulation are followed with DASH score and radiological examination every 3-5 years and serum chrome and cobalt should be analysed in symptomatic cases to learn more about possible local complications leading to, or arising from, metal debris.

Bone mineral density of the trapezium in osteoarthritic trapeziometacarpal joints.

The aim of this study was to test the precision and reliability of measurements of the bone mineral density (BMD) of the trapezium in patients with osteoarthritic trapeziometacarpal joints using dual-energy X-ray absorptiometry scans and to assess whether there is an acceptable correlation between the BMD of the trapezium and that of the distal radius, for which normative data exist. We included 66 patients (52 women, 14 men) diagnosed with Eaton-Glickel stage II-IV osteoarthritis and a mean age of 59 years (range 40-77) in a prospective study. We found good intra- and inter-observer agreement of BMD measurements. Reliability was also good in repeated measurements. There was an indication of an increase in BMD with progression in the Eaton-Glickel stage. There was only a moderate correlation between the BMD of the trapezium and that of the radius.

A three-dimensional analysis of osteoarthritic changes in the thumb carpometacarpal joint.

The purpose of this study is to gain a better understanding of the changes due to osteoarthritis (OA) occurring in the thumb carpometacarpal (CMC) joint by comparing quantitative geometrical measurements in computed tomography scans of healthy and pathological joints in various stages of OA. The measurements were (1) the subluxation of the metacarpal on the trapezium, (2) distance from the scaphoid centre to the metacarpal base, and (3) distance from the metacarpal base to the articulating surface of the trapezium. The three-dimensional position of three characteristic points on the metacarpal, trapezium, and scaphoid were detected in each of the 90 wrists we scanned. The distances between the points were compared by statistical analysis. With high accuracy, we have been able to confirm and quantify that subluxation occurs in the dorso-radial direction. A significant difference in trapezium height and joint space width was found between the OA and control groups. The results indicate how to restore the centre of rotation in surgical treatment of OA with total joint arthroplasty, but the clinical relevance of these findings has to be tested in further clinical studies.

Superior accuracy of model-based radiostereometric analysis for measurement of polyethylene wear: A phantom study.

OBJECTIVES: The accuracy and precision of two new methods of model-based radiostereometric analysis (RSA) were hypothesised to be superior to a plain radiograph method in the assessment of polyethylene (PE) wear. METHODS: A phantom device was constructed to simulate three-dimensional (3D) PE wear. Images were obtained consecutively for each simulated wear position for each modality. Three commercially available packages were evaluated: model-based RSA using laser-scanned cup models (MB-RSA), model-based RSA using computer-generated elementary geometrical shape models (EGS-RSA), and PolyWare. Precision (95% repeatability limits) and accuracy (Root Mean Square Errors) for two-dimensional (2D) and 3D wear measurements were assessed. RESULTS: The precision for 2D wear measures was 0.078 mm, 0.102 mm, and 0.076 mm for EGS-RSA, MB-RSA, and PolyWare, respectively. For the 3D wear measures the precision was 0.185 mm, 0.189 mm, and 0.244 mm for EGS-RSA, MB-RSA, and PolyWare respectively. Repeatability was similar for all methods within the same dimension, when compared between 2D and 3D (all p > 0.28). For the 2D RSA methods, accuracy was below 0.055 mm and at least 0.335 mm for PolyWare. For 3D measurements, accuracy was 0.1 mm, 0.2 mm, and 0.3 mm for EGS-RSA, MB-RSA and PolyWare respectively. PolyWare was less accurate compared with RSA methods (p = 0.036). No difference was observed between the RSA methods (p = 0.10). CONCLUSIONS: For all methods, precision and accuracy were better in 2D, with RSA methods being superior in accuracy. Although less accurate and precise, 3D RSA defines the clinically relevant wear pattern (multidirectional). PolyWare is a good and low-cost alternative to RSA, despite being less accurate and requiring a larger sample size.

Primary cup fixation with different designs of trapeziometacarpal total joint trapezium components: a radiostereometric analysis in a pig bone model.

High loosening rates of the trapezium components of trapeziometacarpal total joint prostheses have been reported. The purpose of this study was to compare the primary press fit fixation of two different, uncemented cup designs (MOTEC and Elektra) with the primary fixation of a cemented polyethylene cup (DLC) in a pig bone model. We did a push out test to measure the maximal load strength of the implants and a low-pressure cyclic loading test combined with radiostereometric analysis to measure the micromotion of the implants. There was no significant difference in fixation strength between the two uncemented screw cup designs or between the two uncemented screw cups and the cemented polyethylene cup. However, we found that threading of the bone before insertion of the Electra screw cup weakens the primary fixation strength of the implant. The results indicate that focus should be on the insertion technique as well as on the cup design of uncemented trapezium cup implants. Further studies of trapezium implant migration in a clinical setting are needed.

Scaphoid kinematics before and after scaphotrapeziotrapezoidal ligament section. Assessment by radiostereometric analysis and computed tomography in a cadaver study.

The purpose of this study was to measure changes in scaphoid kinematics after division of scaphotrapeziotrapezoidal ligaments, with the intention of determining a clinical measure that could be detected by computed tomography. Twelve freshly frozen cadaver upper extremities were marked with tantalum beads and fixed in positions of neutral, 30° extension, and 40° ulnar deviation. Stereoradiographs for bone migration analysis by radiostereometric analysis and computed tomography scans for visible assessment were obtained before and after scaphotrapeziotrapezoidal ligament section. After ligament resection there was a scaphoid supination of 5° and a small (less than 1 mm) radial, distal, and dorsal translation of the distal pole in 30° of wrist extension. In computed tomography reconstructions, the ligament section appeared as a 1 to 2 mm gap in the scaphotrapeziotrapezoidal corner, with loss of articulation between the distal scaphoid pole and the trapezoid bone and increased scaphoid flexion.

Trapeziometacarpal joint implants can be evaluated by roentgen stereophotogrammetric analysis.

Both marker-based roentgen stereophotogrammetric analysis (RSA) and model-based RSA have been helpful evaluation tools in hip and knee arthroplasty. The purpose of this study was to test both model-based and marker-based RSA in the evaluation of total joint prostheses of the trapeziometacarpal joint. In a phantom study, the precision of marker-based RSA was tested with a cemented polyethylene cup and compared with the precision of model-based RSA in an uncemented Elektra screw cup. The precision of model-based RSA of the metacarpal stem was tested using an uncemented Elektra metacarpal stem. In a clinical study 11 patients had double stereo radiographs followed by RSA analysis. The precision of translation in both marker-based and model-based RSA was sufficient for clinical use, but rotation cannot be estimated with sufficient precision.

Subdural intracranial pressure, cerebral perfusion pressure, and degree of cerebral swelling in supra- and infratentorial space-occupying lesions in children.

UNLABELLED: To our knowledge comparative studies of intracranial pressure (ICP) and degree of cerebral swelling during craniotomy for supratentorial or infratentorial space occupying lesion in children are not available. In this prospective study subdural ICP, cerebral perfusion pressure (CPP), dural tension, and the degree of cerebral swelling were analysed in supine and prone positioned children subjected to craniotomy for space occupying lesions. MATERIAL AND METHOD: 48 children with space occupying tumours were subjected to either isoflurane/nitrous oxide 50%/fentanyl (n = 22) or propofol/fentanyl/air/oxygen (n = 26). 25 children were operated supratentorially in supine position, while 23 patients were operated infratentorially in the prone position. Subdural ICP, mean arterial blood pressure (MABP), and CPP were measured just before opening of the dura. Dural tension was estimated before opening of dura, and the degree of cerebral swelling was estimated after opening of dura. RESULTS: The age and weight of children anaesthetised with isoflurane in the prone position were significantly lower than the propofol anaesthetised groups. No significant inter-group differences as regards tumour size, midline shift, rectal temperature, MABP or PaCO2 were found. ICP in prone positioned children averaged 16.9 mm Hg against 9.0 mm Hg in supine positioned children (p < 0.001). In prone positioned children the dura was significantly tenser, and the degree of brain swelling after opening of dura was significantly more pronounced. No significant difference as regard ICP was disclosed when isoflurane/nitrous oxide/fentanyl and propofol/ fentanyl anaesthetized children were compared, but MABP and CPP were significantly lower in isoflurane anaesthetised children. CONCLUSION: In children with cerebral tumours ICP is higher, and the degree of cerebral swelling more pronounced in the prone-compared with supine positioned children. Choice of anaesthesia did not influence ICP, but CPP was significantly lower during isoflurane anaesthesia.

[ECG changes in left-sided pneumothorax]. / Ekg-forandringer ved venstresidig pneumothorax.

We present a case report of a patient with left-sided pneumothorax and electrocardiographic changes suggestive of anterior myocardial infarction. The electrocardiogram was normalised by treating the pneumothorax.