12-Year clinical and radiological results of a double-blind randomized controlled trial comparing posterior cruciate-retaining versus posterior-stabilized total knee arthroplasty.

BACKGROUND: A subject of ongoing debate among orthopedic surgeons is the importance of preserving the posterior cruciate ligament in total knee arthroplasty (TKA), but long-term survival studies are scarce. The aim of this study was to compare long-term survival rates, and clinical and radiological follow up of a double-blind randomized controlled trial comparing posterior cruciate-retaining (PCR) versus posterior-stabilizing (PS) implant design of an AGC TKA. METHODS: A total of 114 patients were included in the survival analysis (PCR n = 61; PS n = 53). Forty-five patients (PCR n = 25; PS n = 20) participated in the long-term follow up using patient-reported outcome measures (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short-Form Health Survey (SF-36) and Kujala score (measuring anterior knee pain)). Thirty-one patients were assessed with a physical test (Knee Society Score (KSS)) and radiographs. RESULTS: Overall survival rate was 95.6% (PCR 98.4% vs. PS 92.5%), with five patients having a major revision (PCR n = 1 vs. PS n = 4, respectively). Satisfying outcome scores for both groups were described at on average 12-year follow up with no significant differences in KSS knee and function scores, WOMAC, SF-36, or Kujala scores between groups. Radiographically, there were no findings of femoral or tibial loosening or polyethylene wear in either group. CONCLUSIONS: Good long-term survival rates were described for the PCR and the PS design of an AGC TKA. There were no significant differences in clinical and radiological outcomes between a PCR and a PS design 12 years postoperatively.

Clinical impact of 99mTc-HDP SPECT/CT imaging as standard workup for foot and ankle osteoarthritis.

Objective: The primary aim of this study was to assess to what extent 99mTc-HDP Single photon emission computed tomography/computed tomography (SPECT/CT) will lead to change of diagnosis and treatment, in patients with suspected foot and ankle osteoarthritis (OA). Secondary aim was to assess the intraobserver variability. Methods: Retrospectively 107 patients, with suspected foot and/or ankle OA of which a SPECT/CT was made, were included for analysis. All the clinical and radiological data were randomized and blinded before being scored by one experienced orthopaedic surgeon. Firstly, based on the clinical data and conventional radiographs, a diagnosis and treatment plan was scored. Secondly, the observer accessed the SPECT/CT and could change the diagnosis and treatment plan. Additionally, the intraobserver reliability was determined by data of 18 patients that were added in twofold to the dataset, without awareness of the observer and by calculating the κ values. Results: The diagnosis changed in 53% (57/107) and treatment plans changed in 26% (28/107) of the patients. Intraobserver reliability for the conventional workup was k = 0.54 (moderate strength of agreement), compared to k = 0.66 (substantial strength of agreement) when SPECT/CT data were added. Conclusions: This study describes the influence of SPECT/CT on diagnosis and treatment plans in patients with suspected symptomatic OA. Also, it shows SPECT/CT leads to a higher intraobserver variability. We believe SPECT/CT has a promising role in the workup for foot and ankle OA. Advances in knowledge: In addition to what was found in complex foot and ankle cases, this study shows that in patients with non-complex foot and ankle problems, SPECT/CT has a substantial influence on the diagnosis (and subsequent treatment plan).

MRI signal intensity of anterior cruciate ligament graft after transtibial versus anteromedial portal technique (TRANSIG): A randomised controlled clinical trial.

BACKGROUND: Two primary surgical femoral drilling techniques are used to reconstruct the anterior cruciate ligament (ACL): the transtibial (TT) technique and the anteromedial portal (AMP) technique. Currently there is no consensus on which surgical technique elicits the best clinical and functional outcomes. MRI-derived measures of the signal intensity (SI) of the ACL graft have been described as an independent predictor of graft properties. The purpose of this study was to assess MRI-derived SI measurements of the ACL graft one year after ACL reconstruction, in order to compare graft maturation of both AMP and TT ACL reconstruction techniques. METHODS: This randomised controlled trial included 33 patients admitted for primary unilateral ACL reconstruction. Primary outcome was MRI Signal intensity ratio (SIR) of the ACL graft one year after ACL reconstruction. Differences in MRI SIR were assessed on two MRI sequencies: sagittal Proton Density Turbo Spin Echo weighted images (PDTSE) and 3D T2 Gradient Echo (T2*) weighted images. Analysis of interobserver and intraobserver variability was conducted for the SIR measurements. RESULTS: No difference in signal intensity of the graft was found between the TT and AMP techniques one year after ACL reconstruction (PDTSE p = 0.665, T2* p = 0.957). Both interobserver and intraobserver variability showed strong agreement (ICC 0.64-0.94). CONCLUSION: No differences in signal intensity of the graft on MRI were seen between the femoral drilling techniques one year after ACL reconstruction, suggesting similar graft maturation at that time. Follow-up studies are needed to determine whether graft intensity changes in the long term. LEVEL OF EVIDENCE: Therapeutic study with level of evidence I.

The role of computer-assisted cryotherapy in the postoperative treatment after total knee arthroplasty: positive effects on pain and opioid consumption.

PURPOSE: The aim of this study was to investigate whether computer-assisted cryotherapy is effective in reducing postoperative pain and analgesics consumption, next to improving functional outcome and patient satisfaction after total knee arthroplasty (TKA). The hypothesis is that computer-assisted cryotherapy has positive effects on postoperative pain after TKA. METHODS: A single-centre non-blinded randomised controlled trial was designed to study the early (first postoperative week) and late (2 and 6 weeks postoperatively) additive effect of computer-assisted cooling after TKA. Participants scheduled for a TKA were randomly allocated to a cold (cryotherapy) C-group or a regular (control) R-group. Next to usual postoperative care for both groups, the C-group received computer-assisted cryotherapy during the first seven postoperative days. Primary outcome was pain, monitored with the numerical rating scale for pain and use of opioid escape medication. Secondary outcomes were function and swelling, monitored by active range of motion, timed up and go test and circumference measurements; patient-reported outcome measurements (KOOS and WORQ questionnaires); and patient satisfaction, monitored by the numerical rating scale for satisfaction. RESULTS: 102 patients participated in this study, both groups contained 51 patients. On most days during the first week, patients in the C-group scored significantly lower NRS pain scores and registered significantly less use of opioid escape medication. In a sub-analysis of 57 patients using the same standard pain protocol, patients in the C-group (n = 28) used less oxycodone during the first postoperative week. There were no significant differences between both groups in active range of motion, timed up and go, or circumference measurements. For the WORQ questionnaire, there was a significant difference between the two groups 6 weeks postoperatively in favour of the C-group. This could be however due to a reduced validity of this questionnaire shortly after TKA. The satisfaction score was not significantly different between both groups. CONCLUSION: Computer-assisted cryotherapy following TKA can be beneficial during the first postoperative week in terms of pain reduction and diminished opioid consumption. No clear differences in knee function or swelling were seen. LEVEL OF EVIDENCE: Therapeutic study with level of evidence I.

Accelerometer Measured Sedentary and Physical Activity Behaviors of Working Patients after Total Knee Arthroplasty, and their Compensation Between Occupational and Leisure Time.

Purpose Objective measurements of sedentary and physical activity (PA) behavior are scarce among working-age patients who undergo total knee arthroplasty (TKA). Aim was to assess sedentary and PA behaviors using accelerometers and to identify compensation effects between occupational and leisure time of sedentary and PA behavior. Methods One year post-TKA, 51 patients wore an ActiGraph(GT3x) accelerometer for 7 days. Sedentary time, prolonged sedentary bouts (≥ 30 min) and PA (light-intensity and moderate-to-vigorous PA) were examined. Compliance with the guideline of > 150 min moderate-to-vigorous PA per week was calculated. Compensation effects were analyzed using multilevel models, splitting effects into routine and within-day compensation, stratifying by physical and non-physical jobs. The routine compensation effects are the ones of interest, representing habitual compensation during a week. Results Participants spent 60% of time in sedentary bouts and 17% in prolonged sedentary bouts, with 37% of PA spent in light-intensity and 3% in moderate-to-vigorous activity. About 70% of patients met the PA guideline. Routine compensation effects were found for workers in physical jobs, who compensated for their occupational light-intensity PA with less light-intensity PA during leisure time. Workers in non-physical jobs did not compensate for their occupational prolonged sedentary bouts, as these continued during leisure time. Conclusion This study showed that working TKA patients are highly sedentary 1 year after surgery, but most met the PA guideline. Especially those with non-physical jobs do not compensate for their occupational prolonged sedentary bouts. This stresses the need to stimulate PA among TKA patients not complying with the guidelines and those with non-physical jobs.

Risk factors for patellar tendinopathy in volleyball and basketball players: A survey-based prospective cohort study.

Patellar tendinopathy (PT) is a common overuse injury of the patellar tendon in jumping athletes. In a recent large cross-sectional study from 2008 several factors were identified that may be associated with the etiology of PT. However, because of the study design no conclusions could be drawn about causal relations. The primary aim of the current study is to investigate whether the factors identified in the previous 2008 study can also be prospectively recognized as predictors of symptomatic PT in 2011. Nine hundred twenty-six Dutch elite and non-elite basketball and volleyball players from the previous study were invited again to complete an online survey about knee complaints and risk factors for PT in 2011. The logistic regression included 385 athletes of which 51 (13%) developed PT since 2008. Male gender [odds ratio (OR) 2.0, 95% confidence interval (CI) 1.1-3.5] was found to be a risk factor for developing PT. No sports-related variables could be identified to increase the risk of developing PT, but some evidence was found for performing heavy physically demanding work, like being a nurse or a physical education teacher (OR 2.3, 95% CI 0.9-6.3). These findings indicate that, when considering preventive measures, it is important to take into account the total tendon load.

[When the end is near: an ICU patient who died at home]. / Als het einde gekomen is: een IC-patiënt die thuis sterft.

We describe the process of transferring a 64-year-old male from a Dutch intensive care unit to his home so that he could die there. He was a respirator-dependent cardiac surgical patient; his intensive care treatment had been withdrawn. We describe the requirements regarding the transfer of care, the role of the nursing staff and documentation of the process. We discuss the natural cause of death and subsequent administrative steps. Based on the positive reactions of the patient and his family, we propose to incorporate this process into Dutch intensive care practice guidelines.

Leucocyte filtration of residual heart-lung machine blood in children undergoing congenital heart surgery.

Cardiopulmonary bypass (CPB) leads to a generalized inflammatory reaction, resulting in increased postoperative leucocyte counts and decreased pulmonary function. In adults, removal of leucocytes from the residual heart-lung machine blood after CPB improved postoperative oxygenation. In children, however, the clinical effects of leucocyte filtration of the residual heart-lung machine blood are unknown. Therefore, we measured postoperative leucocyte counts and arterial blood oxygenation in children undergoing congenital cardiac surgery in a randomized prospective study. Anaesthesia and CPB were standardized. After CPB, the residual heart-lung machine blood was collected as usual. In a group of 25 children, this blood was filtered with a leucocyte depletion filter before transfusion. A control group of 25 children received this blood unfiltered. We found that the postoperative leucocyte counts were significantly lower in the filter group than in the control group (p = 0.02, repeated measurements ANOVA). This difference reached a maximum on the second postoperative day (12.9 x 10(9)/L filter versus 15.9 x 10(9)/L control, p = 0.02, Student's t-test). Values for the arterial blood oxygenation on the first postoperative day were not different between the two groups (15.5 +/- 1 kPa filter versus 14.6 +/- 1.3 kPa control, p = 0.57, Student's t-test). We conclude that leucocyte filtration of the residual heart-lung machine blood reduced systemic leucocyte counts, but did not improve arterial blood oxygenation in children after congenital heart surgery.

Determination of cannabinoids in cannabis products using liquid chromatography-ion trap mass spectrometry.

A method was developed and validated for the simultaneous determination of five cannabinoids, viz. cannabidiol (CBD), cannabidiol acid (CBD-COOH), cannabinol (CBN), delta9-tetrahydrocannabinol (THC), and 3'-carboxy-delta9-all-trans-tetrahydrocannabinol (THC-COOH) in cannabis products. The cannabinoids were extracted from the grinded cannabis samples with a mixture of methanol-chloroform and analysed using liquid chromatography with ion-trap-mass-spectrometry (LC-IT-MSn). For quantification the two most abundant diagnostic MS-MS ions of the analyte in the sample and external standard were monitored. For confirmation purposes the EU criteria as described in Commission Decision 2002/657/EC were followed. Fully satisfactory results were obtained, that is, unequivocal confirmation according to the most stringent EU criteria was possible. The limits of quantification were 0.1 g/kg for CBD, 0.04 g/kg for CBD-COOH, 0.03 g/kg for CBN, 0.28 g/kg for THC and 9.9 g/kg for THC-COOH. The repeatabilities, defined by R.S.D., were 2% for CBN, THC and THC-COOH at the concentration levels of respectively 0.023, 3.3 and 113 g/kg and 5% for CBD-COOH at the level of 0.34 g/kg (n = 6).

The rationale for fat filtration during cardiac surgery.

Improved filter technology may enable the removal of specific substances such as lipids from the blood. Lipids form a heterogeneous group of compounds, but during surgery, the main interest is focussed on triglycerides, glycerol and free fatty acids. Fat emboli have been demonstrated in the brain after cardiac surgery and are associated with ischaemic brain injury. Fat emboli have also been demonstrated in lung and kidney tissue. Lung tissue and leucocytes are especially vulnerable to the effects of free fatty acids. The surgical wound suction blood during cardiac surgery contains a considerable quantity of microemboli. Therefore, as a first step to determining the place of fat filtration during cardiac surgery, the use of a fat removal filter for surgical wound suction blood is advocated.

Retinoic acid metabolites in plasma are higher after intake of liver paste compared with a vitamin A supplement in women.

The objectives of the present study were to compare the bioavailability of vitamin A from liver paste and from a vitamin A supplement at three nutritionally relevant levels of intake, and to estimate levels of "safe" intake based on concentrations of retinoic acid and its metabolites in plasma after a single dose of vitamin A from liver paste. Women (n = 35; 19-47 y of age) consumed 3.0, 7.5 or 15 mg vitamin A as liver paste or as a vitamin A supplement with a test meal in a randomized design, with a combined crossover (two sources) and parallel approach (three dosages). Retinyl esters and retinoic acid (RA) metabolites were quantified in blood samples at 2-24 h after dosing. The areas under the time-response curves (AUC) were calculated to evaluate responses in plasma vitamin A after intake of liver paste and the vitamin A supplements. For retinyl esters, the AUC was significantly affected by the dosage, but not by the source. The formation of 13-cis-RA, 13-cis-4-oxo-RA, and to a lesser extent all-trans-RA was significantly higher after consumption of liver paste compared with the supplement, especially at higher dosages. Long-term baseline concentrations of retinol were not affected by a single intake of vitamin A. In conclusion, the bioavailability of vitamin A from single doses of liver paste and a vitamin A supplement does not differ, but the plasma concentrations of RA metabolites are higher after intake of liver paste. Thus, pregnant women should indeed limit the intake of vitamin A from liver products.

Effects of preoperative treatment with diltiazem on diastolic ventricular function after coronary artery bypass graft surgery.

OBJECTIVE: To examine whether preoperative treatment with diltiazem could ameliorate left ventricular (LV) diastolic dysfunction in patients after coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, nonrandomized clinical study. SETTING: University hospital. PARTICIPANTS: Thirty-four patients with preserved LV function undergoing elective CABG surgery. INTERVENTIONS: According to medical history, patients were divided into 2 groups: patients not receiving diltiazem (n = 17) and patients treated with once-daily oral diltiazem for at least 2 weeks (n = 17). All patients received preoperative beta-blockers. MEASUREMENTS AND MAIN RESULTS: After induction of anesthesia, after sternal closure, and 4 hours after cardiopulmonary bypass (CPB), mitral and pulmonary venous flow velocities were measured with pulsed Doppler. LV short-axis end-diastolic area by Doppler transesophageal echocardiography (TEE) and hemodynamic variables were obtained simultaneously at comparable pulmonary capillary wedge pressures. Postoperatively, increased peak E and A velocities were observed in patients with diltiazem and controls and returned to baseline 4 hours post-CPB in controls. Changes in these velocities did not result in a decreased E/A ratio. Peak A velocity, E/A ratio, and E wave deceleration time were significantly dependent on heart rate, not peak E velocity. End-diastolic area at comparable pulmonary capillary wedge pressure remained unchanged. In relation to diltiazem, only peak A velocity and time velocity integral of the A wave (TVI-A) at 4 hours post-CPB differed from controls. CONCLUSION: Diastolic function is preserved after CABG surgery and is not altered by diltiazem in patients with preserved LV systolic function. The persistence of increased peak A velocity and TVI-A into the postoperative period suggests improved atrial systolic function with diltiazem.

Mallory-Weiss tear following cardiac surgery: transoesophageal echoprobe or nasogastric tube?

A case of fatal upper gastrointestinal bleeding from a Mallory-Weiss tear after transoesophageal echocardiography during cardiac surgery is reported. After the echo-cardiographic examination, which is considered a safe procedure, a nasogastric tube was inserted which immediately revealed bright red blood. Eventually the patient lost 9 litres of blood. The role of the echo-probe and the nasogastric tube in causing the Mallory-Weiss tear is discussed. Although this case is not conclusive about the mechanism of oesophageal damage, it is suggested that the safety recommendations for transoesophageal echocardiography also apply for instrumentation of the oesophagus with a nasogastric tube after the transoesophageal echocardiographic examination.

Filtration of activated granulocytes during cardiopulmonary bypass surgery: a morphologic and immunologic study to characterize the trapped leukocytes.

Cardiopulmonary bypass surgery induces an inflammatory reaction among others by activation of granulocytes. Leukocyte filtration has been shown to reduce the postoperative morbidity mediated by activated granulocytes. However, little is known about the mechanism of filter-leukocyte interaction. This study examines whether a leukocyte filter removes activated granulocytes or a general leukocyte population. Eleven patients undergoing cardiopulmonary bypass surgery were included in this study. Leukocyte filtration was achieved before the reperfusion phase with a Pall non-woven polyester filter located at the venous side of the heart-lung machine. After filtration, the trapped granulocytes inside the filter were examined morphologically with light and scanning electron microscopy and immunologically by CD45RO antigen binding to the filter material. Furthermore, leukocyte release markers were measured to determine whether cells were activated during filtration. Microscopic evaluation revealed 84% granulocytes and 14% lymphocytes trapped in the filter, compared with 78% granulocytes and 22% lymphocytes in the blood before filtration. Granulocytes were trapped significantly more in the first blood contact layer of the filter material than in the middle layer and last layer, whereas lymphocytes trapped slightly more in the middle layer. The near maximum level of CD45RO expression was measured on granulocytes trapped inside the filter material, whereas CD2 and CD19 measured on lymphocytes were bound to a minor extent. Beta-glucuronidase concentration did not increase after filtration, suggesting the absence of activation of granulocytes by filtration. A leukocyte filter made of non-woven polyester material removes the activated granulocytes rather than leukocytes at random. This implies that this particular type of leukocyte removal filter is suitable for use in cardiopulmonary bypass patients whose granulocytes in the circulation are activated. Furthermore, measurement of activated granulocytes instead of total leukocyte count is likely preferable for functional assessment of leukocyte removal devices.

Leukocyte depletion during cardiac operation: a new approach through the venous bypass circuit.

BACKGROUND: Leukocyte depletion recently has been introduced for cardiac surgical patients to attenuate leukocyte-mediated inflammation and organ reperfusion injury. We evaluated the feasibility of a new leukocyte depletion method in which systemic leukocyte depletion is achieved through the venous side of the cardiopulmonary bypass circuit under low blood flow. METHODS: Forty cardiac surgical patients undergoing cardiopulmonary bypass were allocated randomly to a leukocyte depletion group (n = 20) and a control group (n = 20). In the depletion group, leukocyte filtration was achieved with two filter sets located between the venous drainage and the venous reservoir. Leukocyte filtration was commenced after the start of rewarming but before the release of the aortic cross-clamp, and it was driven by a spare roller pump of the heart-lung machine. RESULTS: All the episodes of filtration went smoothly within a period of 10 minutes and with a blood flow rate of 400 mL/min. The mean leukocyte removal rate calculated at the end of filtration was 69%. Circulating leukocytes were reduced by 38% in the depletion group compared with the control group at the moment of cross-clamp release (4.3x10(9)/L versus 6.8x10(9)/L, p<0.05). The postoperative inflammatory response also was reduced as indicated by less production of interleukin-8 (p<0.05). Clinically, there was no significant difference between the two groups in postoperative PaO2 or pulmonary hemodynamics. CONCLUSIONS: It is technically feasible to deplete circulating leukocytes through the venous side of the cardiopulmonary bypass circuit with a low blood flow rate. Future studies should focus on the duration and timing of leukocyte depletion to optimize the methodology of leukocyte depletion for cardiac surgical patients.

Efficiency and safety of leukocyte filtration during cardiopulmonary bypass for cardiac surgery.

BACKGROUND: Leukocyte filtration of systemic blood during cardiopulmonary bypass surgery to reduce post-operative morbidity has not yet been established because of the enormous leukocyte release from the third space. This study was designed to examine the efficiency and safety of leukocyte filtration by a new prototype large capacity leukocyte filter. PATIENTS AND METHODS: Patients undergoing cardiopulmonary bypass surgery were prospectively divided into two groups: a leukocyte removal group (n = 11) receiving leukocyte filtration during cardiopulmonary bypass and a control group (n = 20) with no filtration. The filtration efficiency was indicated by electronic leukocyte counts before and after filtration and the clinical efficiency to reduce post-operative morbidity was indicated by PaO2. Safety was indicated by monitoring the filtration pressure and leukocyte release products across the filter, as well as by examining the post-filtration filter by light and electron microscopy. RESULTS: On an average, 75% of all entering leukocytes were removed by the filter. The post-operative PaO2 showed a tendency to improve after filtration. During filtration, the pressure across the filter material increased in five cases, accompanied by an increase in post-filter plasma hemoglobin and beta-glucoronidase. Within these filters accumulations of fibrin network with many trapped leukocytes were discovered microscopically. CONCLUSIONS: The filter was efficient in filtering leukocytes, but the filtration efficiency slowed at the end of filtration. Furthermore, the patients' post-operative parameters showed a tendency to improve after filtration. However, flow obstruction by means of clotting seems to be an important issue of safety involved in the filtration of large numbers of leukocytes for cardiopulmonary surgical patients.

Leukocyte depletion results in improved lung function and reduced inflammatory response after cardiac surgery.

Leukocyte depletion during cardiopulmonary bypass has been demonstrated in animal experiments to improve pulmonary function. Conflicting results have been reported, however, with clinical depletion by arterial line filter of leukocytes at the beginning of cardiopulmonary bypass. In this study, we examined whether leukocyte depletion from the residual heart-lung machine blood at the end of cardiopulmonary bypass would improve lung function and reduce the postoperative inflammatory response. Thirty patients undergoing elective heart operations were randomly allocated to a leukocyte-depletion group or a control group. In the leukocyte-depletion group (n = 20), all residual blood (1.2 to 2.1 L) was filtered by leukocyte-removal filters and reinfused after cardiopulmonary bypass, whereas in the control group an identical amount of residual blood after cardiopulmonary bypass was reinfused without filtration (n = 10). Leukocyte depletion removed more than 97% of leukocytes from the retransfused blood (p < 0.01) and significantly reduced circulating leukocytes (p < 0.05) and granulocytes (p < 0.05) compared with the control group. Levels of the inflammatory mediator thromboxane B2 determined at the end of operation (p < 0.05) were significantly lower in the depletion group than in the control group, whereas no statistical differences in interleukin-6 levels were found between the two groups. After operation, pulmonary gas exchange function (arterial oxygen tension at a fraction of inspired oxygen of 0.4) was significantly higher in the leukocyte-depletion group 1 hour after arrival to the intensive care unit (p < 0.05) and after extubation (p < 0.05). There were no statistical differences between the two groups with respect to postoperative circulating platelet levels and blood loss, and no infections were observed during the whole period of hospitalization. These results suggest that leukocyte depletion of the residual heart-lung machine blood improves postoperative lung gas exchange function and is safe for patients who are expected to have a severe inflammatory response after heart operations.

Quantification of mitoxantrone in bone marrow by high-performance liquid chromatography with electrochemical detection.

An analytical method for the determination of mitoxantrone in bone marrow was developed using high-performance liquid chromatography with electrochemical detection. The extraction procedure was optimized by investigating several factors which potentially could influence the recovery of mitoxantrone from bone marrow cells. The mean recovery of mitoxantrone from rat bone marrow was found to be 81.7% with a coefficient of variation 3.8%. High-performance liquid chromatography was carried out to quantitate mitoxantrone using ametantrone as internal standard. The detection limit of our analytical method amounts to 100 pg on-column, corresponding to 1 ng/ml of cell suspension containing 2 x 10(7) cells and a day-to-day variation of maximally 8%. Storage of bone marrow samples, containing mitoxantrone, for one to fourteen days resulted in a mean recovery of 94%, as compared to freshly analysed samples. Subsequently we studied the pharmacokinetics of mitoxantrone in rat bone marrow. It appeared that after an intravenous bolus injection of mitoxantrone (2.5 mg/kg) in rats, the drug accumulated in the femoral bone marrow for about four days, and thereafter gradually declined.