The clinical outcome of total knee arthroplasty is compromised by a previously implanted medial unicondylar knee arthroplasty.

OBJECTIVE: To investigate the clinical outcome of patients that underwent conversion of a medial unicondylar knee arthroplasty (UKA) to a total knee arthroplasty (TKA) and to compare that outcome to patients that underwent primary TKA. It was hypothesized that those groups would significantly differ in terms of knee score outcome and implant survival. METHODS: A retrospective-comparative study was conducted utilizing data from the Federal state's arthroplasty registry. Included were patients from our department that undergone a conversion of a medial UKA to a TKA (UKA-TKA group). The Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) from preoperative and 1-year postoperative was used. Moreover, the implant survival was analyzed. RESULTS: In the UKA-TKA group, there were 51 cases (age 67 ± 10, 74% women), and in the TKA group, there were 2247 cases (age 69 ± 9, 66% women). The one-year postoperative WOMAC total score was 33 in the UKA-TKA group und 21 in the TKA group (p < 0.001). Similarly, the WOMAC pain, WOMAC stiffness, and WOMAC function scores were significantly worse in the UKA-TKA. After 5 years, the survival rates were 82% and 95% (p = 0.001). The 10-years prosthesis survival was 74% and 91% in the UKA-TKA and TKA groups, respectively (p < 0.001). CONCLUSIONS: Based on our findings it is concluded that patients who received a TKA after UKA have inferior results than those that directly receive a TKA. This is true for both patient-reported knee outcome and prosthesis survival. Converting UKA to TKA should not be seen as an easy operation, but should rather be done by surgeons with considerable experience in both primary and revision knee arthroplasty.

[Revision arthroplasty of the hip : Direct anterior approach]. / Revisionsendoprothetik des Hüftgelenks : Der anteriore Zugang.

The direct anterior approach to the hip allows good exposure of acetabulum and periacetabular bones. For simple acetabular revisions it can be chosen to be small (minimally invasive); in the case of extensive periacetabular bone loss exposure of the entire ilium cranial of the acetabulum may be achieved, and the pubic bone as well as inner-pelvic structures adjacent to the acetabulum can be exposed. The internerval plane of the approach between muscles innervated by the femoral nerve and the gluteal nerves allows exposure of the ilium without endangering the nerve supply of gluteal muscles.

Mini-midvastus total knee arthroplasty does not result in superior gait pattern.

PURPOSE: Previous studies dealing with gait after minimally invasive surgery (MIS) total knee arthroplasty (TKA) are rare and insufficient. It was the purpose of the study to determine in a prospective, comparative setting whether MIS influences the outcome of TKA in terms of typical 3D gait parameters. METHODS: Patients scheduled for TKA or MIS TKA were invited to participate. MIS TKA was defined as TKA with shorter skin incision, mini-midvastus arthrotomy, special instruments, and avoidance of tibiofemoral dislocation and patella eversion. All other intra- and perioperative aspects were identical for both groups. A 3D gait analysis was performed with a VICON system 1 month preoperative and 8 weeks post-operative. A multivariate analysis of variance was conducted including the main effects time (pre- and post-surgery) and surgical group and the group-by-time interaction effect. RESULTS: Seventeen MIS TKA patients and 20 TKA patients were eligible for the final analysis. We determined neither inter-group differences nor time × group interactions for any gait variables (temporospatial, ground reaction forces, joint angles and joint moments)­except for the varus-valgus knee kinematics. In pre- to post-operative comparison, the maximum valgus sway increased in the MIS group, whereas it decreased in the conventional group (p = 0.001). CONCLUSION: From our findings, it was concluded that MIS TKA does not result in a superior walking pattern 8 weeks post-operative. Because we previously also observed mini-midvastus MIS TKA to have equal or slightly inferior results with regard to knee scores, knee torque, radiographic outcome and tourniquet/operating time, we discontinued the procedure. LEVEL OF EVIDENCE: Prospective comparative study, Therapy, Level II.

Brake response time returns to the pre-surgical level 6 weeks after unicompartmental knee arthroplasty.

PURPOSE: The objective of the study was to clarify whether driving abstinence should be recommended when patients are discharged from hospital after unicompartmental knee arthroplasty (UKA). We tested the hypotheses that there are differences in the peri-operative course of brake response time in patients undergoing right-sided (1) or left-sided (2) UKA. Additionally, we tested whether brake response time is significantly influenced by pain (3), driving experience (4) or age (5). METHODS: In 43 patients undergoing UKA, brake response time was measured with a custom-made driving simulator pre-operatively and 1 and 6 weeks after UKA. Patients' visual analogue scales for knee pain and their self-reported driving experience were also assessed. RESULTS: In patients with right-sided UKA, brake response time changed from 786 (261) ms pre-operatively to 900 (430) ms 1 week post-operatively (p = 0.029). At 6 weeks post-operatively, brake response time had returned to 712 (139) ms, which was deemed to be an insignificant change from the pre-operative reference benchmark. When surgery was performed on the contralateral left side, no effect was found onto the right side's brake response time. Knee pain and driving experience were significantly correlated with brake response time. No such correlations were found between brake response time and age. CONCLUSIONS: On the basis of the current findings, it is concluded that brake response time returns to pre-operative levels 6 weeks after UKA surgery. Therefore, it is proposed that driving be abstained from for that period.

[The direct anterior approach to the hip revision]. / Der direkte anteriore Zugang in der Revisionshüftendoprothetik.

OBJECTIVE: The objective of this paper is to describe a minimally invasive approach to revision total hip arthroplasty. INDICATIONS: Indications for revision hip arthroplasty are septic or aseptic loosening of one or both components of a hip arthroplasty. In revisions the direct anterior approach (DAA) allows for a small incision if only the cup has to be revised or in cases of stem revision; the femoral preparation can be performed strictly endofemorally from the proximal direction. The gluteal muscles can be preserved whether the approach is limited to the original interval between the musculus tensor fasciae latae and the rectus, or has to be extended. CONTRAINDICATIONS: If preservation of the gluteal muscles is desired, the DAA and its extension are the method of choice. For endofemoral revision other than detachment of the musculus tensor fasciae latae, hyperextension and adduction of the operated leg are important. If these cannot be achieved, an alternative operative strategy or a different approach should be considered. As this approach allows for extensions proximally and distally along the femur, it competes with lateral approaches to the hip joint and femur, and does not have additional specific contraindications. The availability of specific curved, angulated, or offset instruments is mandatory. SURGICAL TECHNIQUE: The starting point of the incision is found two fingerbreadths lateral and two finger breadths distal to the anterior superior iliac spine. The fascia of the musculus tensor fasciae latae is incised sharply at its midpoint. The interval is prepared strictly subfacially and medially to the musculus tensor fasciae latae to expose the hip joint. POSTOPERATIVE MANAGEMENT: For this approach we don't have any specific recommendations. Postoperative management depends mostly on the extension of the approach and the type of reconstruction performed. If the approach can be limited to the minimally invasive direct anterior portal, reduced muscle damage should result in faster rehabilitation. RESULTS: The retrospective analysis was performed on the data obtained from 48 revision operations with the minimally invasive direct anterior approach to total hip arthroplasty. The median cut-suture time was 108 min (42-282 min); patients spent a median time of 10 days (4-33 days) in the hospital from the day of the operation. The most common revision operations were cup replacement with an augmentation ring (13 out of 48), stem revision (11 out of 48), cup replacement (9 out of 48), H-TEP complete (3 out of 48), removing of ossifications (2 out of 48), cap revision (2 out of 48) and H-TEP removal with insertion of a spacer (2 out of 48). Complications attributed to the procedure were reported in 9 of the 48 cases: 1 wound-healing disorder, 1 late infection, 1 hematoma, 1 deep vein thrombosis, 1 perforation (by the spacer) and 1 ossification. Two patients were diagnosed with trochanteric pain syndrome. In one case an implant loosening was diagnosed 12 months after the revision.

Cost-effectiveness of universal ultrasound screening compared with clinical examination alone in the diagnosis and treatment of neonatal hip dysplasia in Austria.

Between 1978 and 1997 all newborns in the Austrian province of Tyrol were reviewed regarding hip dysplasia and related surgery. This involved a mean of 8257 births per year (7766 to 8858). Two observation periods were determined: 1978 to 1982 (clinical examination alone) and 1993 to 1997 (clinical examination and universal ultrasound screening). A retrospective analysis compared the number and cost of interventions due to hip dysplasia in three patient age groups: A, 0 to < 1.5 years; B, ≥ 1.5 to < 15 years; and C, ≥ 15 to < 35 years. In group A, there was a decrease in hip reductions from a mean of 25.2 (SD 2.8) to 7.0 (SD 1.4) cases per year. In group B, operative procedures decreased from a mean of 17.8 (SD 3.5) to 2.6 (SD 1.3) per year. There was a 75.9% decrease in the total number of interventions for groups A and B. An increase of €57,000 in the overall cost per year for the second period (1993 to 1997) was seen, mainly due to the screening programme. However, there was a marked reduction in costs of all surgical and non-surgical treatments for dysplastic hips from €410,000 (1978 to 1982) to €117,000 (1993 to 1997). We believe the small proportional increase in costs of the universal ultrasound screening programme is justifiable as it was associated with a reduction in the number of non-surgical and surgical interventions. We therefore recommend universal hip ultrasound screening for neonates.

Clinical value of the Taylor Spatial Frame: a comparison with the Ilizarov and Orthofix fixators.

PURPOSE: Evaluation of the advantages and limitations of the Taylor Spatial Frame (TSF) with regard to the healing index (HI), distraction-consolidation time (DCT), accuracy of correction complications, and cost of the device. METHODS: Comparison of results with the traditional Ilizarov apparatus and a unilateral Orthofix fixator in a consecutive patient series with 135 bony deformity corrections. RESULTS: The HI did not differ significantly between all three fixators and was 57 days/cm for all patients. The DCT was significantly shorter for the TSF (148 days) compared to the Ilizarov fixator (204 days) and the Orthofix device (213 days). The accuracy of deformity correction was higher for the TSF than the other devices. The mean values of the measured angles after correction did not differ, but the variance of the results was the lowest. Also, the total rate of complications was considerably lower for the TSF. The Orthofix device showed a high rate of angular deformity during treatment, whereas both ring fixators had a relatively higher number of pin-related problems. CONCLUSIONS: The findings in our patient series suggest the use of the Orthofix apparatus for simple lengthening over short to median distances and the Ilizarov device for the correction of simple bony deformities and pure lengthening over long distances. The TSF allows multiplanar corrections and lengthenings without complex modifications of the device. But, due to the remarkably higher costs, it has not yet been established as our routine device. LEVEL OF EVIDENCE: Level IV-case series. Therapeutic Study-Investigating the Results of Treatment.

Migration of hip revision stems into the knee joint: alternative treatment modalities: technical note.

We report two unusual cases of stem penetration of long shaft femoral prosthesis into the knee joint after revision total hip arthroplasty. In both patients, the protruded tip of the stem interfered with the tibial plateau and averted the knee joint from full range of motion. To avoid further extensive surgery, the tips of the femoral stem were excised using a high speed-cutter. Both patients had immediate improvement in range of motion postoperatively, fast and uncomplicated rehabilitation, immediate pain relief, and good radiological results. If this rare complication occurs, we recommend for a primary intervention to cut the tip of the stem because replacement of the prosthesis would be a long lasting and very exhaustive surgery for affected patients.

Correlation between objective gait parameters and subjective score measurements before and after total knee arthroplasty.

The absence of uniformity, the use of different terminologies, and the diversity of methods used to translate numerical data into clinical outcomes have been described as potential problems when dealing with clinical knee scores for total knee arthroplasty (TKA). Gait analysis is believed to provide more objective parameters. The aim of the present study was to obtain information about the correlation between the outcome in terms of locomotion and the clinical knee score after TKA. Thirty consecutive patients awaiting TKA were involved in the study. One day prior to surgery and 3 months postoperatively, data pertaining to the Hospital for Special Surgery Score (HSS) and the Knee Society Score (KSS) (subgroups 'pain', 'knee', 'function' and 'total sum') were analyzed for correlations with kinematic and temporospatial parameters of gait analysis. At a significance-level of p

Frontal plane leg alignment and muscular activity during maximum eccentric contractions in individuals with and without patellofemoral pain syndrome.

PURPOSE: The role of frontal plane tibiofemoral alignment in subjects with patellofemoral pain syndrome (PFPS) is controversial and rarely discussed in the literature. As well, little research has been done on the effects of the hamstrings muscles on PFPS. The aim of the current study was to determine whether, in individuals with PFPS, frontal plane tibiofemoral alignment or muscular activity of the index knee's crossing muscles is altered during maximum eccentric leg press exercise. METHODS: This cross-sectional study involved 19 patients with PFPS and 19 control subjects who were matched according to gender, age, and physical activity. During eccentric leg press action, frontal plane tibiofemoral alignment was assessed with a motion analysis system based on skin markers. Simultaneously, surface-electromyography was used to assess the activity levels of the relevant knee crossing muscles. To assess the activity under functional conditions, a leg press with a footplate having variable stability was used for barefoot testing. RESULTS: The PFPS subjects did not have significantly different frontal plane leg alignment compared to controls. On electromyography (EMG), PFPS patients had significantly lower levels of hamstring activity during eccentric leg exercise. The differences between the two groups (%; absolute differences normalized EMG) ranged from 20% (semitendinosus; stable footplate; p=0.017) to 21% (biceps femoris; unstable footplate; p=0.019) and 32% (semitendinosus; unstable footplate; p=0.002). CONCLUSIONS: PFPS is not linked to altered frontal plane leg alignment during eccentric leg pressing. However, PFPS is associated with eccentric under-activation of the hamstrings, which may be a compensatory strategy that maintains patellofemoral joint pressure within bearable levels.

Complications and patient satisfaction after periacetabular pelvic osteotomy.

Periacetabular osteotomy (PAO) is a well established method to treat hip dysplasia in the adult. There is, however, a lack of information on the subjective outcome of patients with complications after PAO. The purpose of this study was therefore to assess the influence of complications on the patients' post-operative wellbeing and function: 60 PAOs on 50 patients were investigated retrospectively after a mean follow-up of 7.4 years. The patients' self-reported assessment of health and function was evaluated by the Medical Outcomes Short Form-36 (SF-36) and the Western Ontario and McMaster Universities (WOMAC) questionnaires at last follow-up. Forty healthy persons served as a control group. Of the 60 interventions 13 had no complications. Minor complications occurred in 25 (41%) and in 22 (37%) at least one major complication occurred. SF-36 summary measure was 76.4 for PAO patients and 90.3 for the control group. Mean WOMAC score was 25.1. Patients with major complications had a similar subjective outcome as patients with minor or without complications, but persistent dysaesthesia due to lateral femoral cutaneous nerve dysfunction led to a worse subjective function. Lesions of the lateral femoral cutaneous nerve have much greater influence on patients' self-assessed functional outcome after PAO than previously reported and greater attention has to be given to this supposedly minor complication.

Strategies for prevention and management of musculoskeletal conditions. Low back pain (non-specific).

Low back pain (LBP) is defined as pain localised between the 12th rib and the inferior gluteal folds, with or without leg pain. Most cases are non-specific, but in about 10% of cases a specific cause is identified. Red flags are typical signs or symptoms that are frequently associated with specific LBP. Yellow flags are prognostic factors associated with a more unfavourable and often chronic disabling course of the disease. LBP has a lifetime prevalence of 60-85%. At any one time, about 15% of adults have LBP. LBP poses an economic burden to society, mainly in terms of the large number of work days lost (indirect costs) and less so by direct treatment costs. A substantial proportion of individuals with chronic LBP has been found to have chronic widespread pain. LBP is often associated with other pain manifestations such as headache, abdominal pain and pain in different locations of the extremities. Widespread pain is associated with a worse prognosis compared to localised LBP. Treatment targets are reduction of pain and better activity/participation, including prevention of disability as well as maintainance of work capacity. The evidence from selected and appraised guidelines, systematic reviews and major clinical studies was classified into four levels, level Ia being the best level with evidence from meta-analysis of randomised controlled trials. Key recommendations (level Ia): fitness programmes and advice to stay active can reduce pain, improve function and can prevent LBP becoming chronic. Simple analgesics, NSAIDs and muscle relaxants can reduce pain and can improve and maintain function. Maintaining physical activity, avoiding rest and manual therapy can reduce pain and maintain and restore function in acute LBP. Behavioural treatment can prevent LBP becoming chronic. Aerobic fitness and endurance training, behavioural treatment and multi-disciplinary treatment programmes can reduce pain and can improve/maintain function in chronic LBP.

Uncompromised quality of the cement mantle in Exeter femoral components implanted through a minimally-invasive direct anterior approach. A prospective, randomised cadaver study.

A complete cement mantle is important for the longevity of a total hip replacement. In the minimally-invasive direct anterior approach used at the Innsbruck University hospital, the femoral component has to be inserted into the femoral canal by an angulated movement. In a cadaver study, the quality and the extent of the cement mantle surrounding 13 Exeter femoral components implanted straight through a standard anterolateral transgluteal approach were compared with those of 13 similar femoral components implanted in an angulated fashion through a direct anterior approach. A third-generation cementing technique was used. The inner and outer contours of the cement mantles was traced from CT scans and the thickness and cross-sectional area determined. In no case was the cement mantle incomplete. The total mean thickness of the cement mantle was 3.62 mm (95% confidence interval 3.59 to 3.65). The mean thickness in the group using the minimally-invasive approach was 0.16 mm less than that in the anterolateral group. The distribution of the thickness was similar in the two groups. The mean thickness was less on the anteromedial and anterolateral aspect than on the posterior aspect of the femur. There is no evidence that the angulated introduction of Exeter femoral components in the direct anterior approach in cadavers compromises the quality, extent or thickness of the cement mantle.

Cementless hemiarthroplasty in femoral neck fractures: evaluation of clinical results and measurement of migration by EBRA-FCA.

Aim of the present study was to evaluate migration rates of cementless primary hemiarthroplasty in acute femoral neck fractures. In a longitudinal, prospective study 46 patients were treated by cementless hemiarthroplasty. Clinical follow up was correlated with the EBRA-FCA method. In 30% of all patients stem migration amounted to more than 2 mm; further, these patients were seen to have a high level of activity. A high degree of migration in more than 30% of all patients requires critical scepticism toward further use of the investigated cementless stem as hemiarthroplasty. According to literature, migration of more than 2 mm suggests a high probability of early aseptic loosening. In patients with a low degree of activity good results could be observed; nevertheless, in patients with a high level of activity the combination of the investigated cementless stem with a solid fracture head cannot be recommended.

Reducing the risk of dislocation after total hip arthroplasty: the effect of orientation of the acetabular component.

Malposition of the acetabular component is a risk factor for post-operative dislocation after total hip replacement (THR). We have investigated the influence of the orientation of the acetabular component on the probability of dislocation. Radiological anteversion and abduction of the component of 127 hips which dislocated post-operatively were measured by Einzel-Bild-Röentgen-Analysis and compared with those in a control group of 342 patients. In the control group, the mean value of anteversion was 15 degrees and of abduction 44 degrees. Patients with anterior dislocation after primary THR showed significant differences in the mean angle of anteversion (17 degrees), and abduction (48 degrees) as did patients with posterior dislocation (anteversion 11 degrees, abduction 42 degrees). After revision patients with posterior dislocation showed significant differences in anteversion (12 degrees) and abduction (40 degrees). Our results demonstrate the importance of accurate positioning of the acetabular component in order to reduce the frequency of subsequent dislocations. Radiological anteversion of 15 degrees and abduction of 45 degrees are the lowest at-risk values for dislocation.

EBRA-FCA for measurement of migration of the femoral component in surface arthroplasty of the hip.

Studies on the migration of an implant may be the only way of monitoring the early performance of metal-on-metal prostheses. The Ein Bild Roentgen Analyse--femoral component analysis (EBRA-FCA) method was adapted to measure migration of the femoral component in a metal-on-metal surface arthroplasty of the hip using standard antero-posterior radiographs. In order to determine the accuracy and precision of this method a prosthesis was implanted into cadaver bones. Eleven series of radiographs were used to perform a zero-migration study. After adjustment of the femoral component to simulate migration of 3 mm the radiographs were repeated. All were measured independently by three different observers. The accuracy of the method was found to be +/- 1.6 mm for the x-direction and +/- 2 mm for the y-direction (95% percentile). The method was validated using 28 hips with a minimum follow-up of 3.5 years after arthroplasty. Seventeen were sound, but 11 had failed because of loosening of the femoral component. The normal (control) group had a different pattern of migration compared with that of the loose group. At 29.2 months, the control group showed a mean migration of 1.62 mm and 1.05 mm compared with 4.39 mm and 4.05 mm in the failed group, for the centre of the head and the tip of the stem, respectively (p = 0.001). In the failed group, the mean time to migration greater than 2 mm was earlier than the onset of clinical symptoms or radiological evidence of failure, 19.1 versus 32.2 months (p = 0.001) and 24.8 months (p = 0.012), respectively. EBRA-FCA is a reliable and valid tool for measuring migration of the femoral component after surface arthroplasty and can be used to predict early failure of the implant. It may be of value in determining the long-term performance of surface arthroplasty.

Radiographic evaluation of the Duraloc cup after 4 years.

We implanted 71 metal-backed, porous-coated, hemispheric, press-fit Duraloc-100 cups in 68 consecutive patients. In 61 patients, the femoral stem was a cementless Spotorno and in ten a cemented Lubinus SP II. A 28-mm Biolox ceramic head was used with both stems. After an average follow-up of 4 (3.7-5.9) years, we examined 67 hips. Radiolucencies were described in three zones according to DeLee and Charnley, and migration was measured on serial radiographs using the computer-assisted EBRA method. Total migration of more than 1 mm within the first 2 years occurred in 22/62 cups. Nine cups showed more than 1.5 mm total migration within the first 2 years and more than 2 mm within the whole period. The presence of post-operative radiolucencies correlated significantly with a total migration value of more than 2 mm within the first 2 years (p=0.02). Post-operative radiolucencies in zone 1 correlated with a total migration value of more than 2 mm within the first 2 years (p=0.027) and more than 2.5 mm within the whole period (p=0.051). These correlation values might reflect the quality of operative technique, particularly reaming, and implant selection.

Comparison of conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion.

The purpose of the study was to compare conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion (ALIF). Fifty-six consecutive patients with spondylolisthesis, lumbar instability, or failed back syndrome were treated with ALIF between 1991 and 2001. The patients were retrospectively evaluated and divided in two groups: Group 1, consisting 33 patients, was treated with ALIF using the conventional retroperitoneal approach, and Group 2, consisting of 23 patients, was operated with the minimally invasive muscle-splitting approach for ALIF. The groups were comparable as regards age, indication of fusion, and diagnosis. All patients in both groups had fusion with autologous iliac crest grafts and posterior instrumentation with posterolateral fusion in the same sitting. Clinical evaluation was done by two questionnaires: the North American Spine Society (NASS) Lumbar Spine Outcome Assessment Instrument and the Nottingham Health Profile (NHP). Fusion rate was evaluated radiologically. Mean clinical follow-up was 5.5 years. There was no statistical difference in the occurrence of complications with both approaches nor with the fusion rates of 92% in group 1 and 84% in group 2 respectively. The minimally invasive extraperitoneal approach for ALIF was associated with significantly less intraoperative blood loss, operation time, and length of the skin incision. In addition, this approach showed significant improvement in postoperative back pain in comparison to the conventional approach for ALIF.

Migration of metal-on-metal versus ceramic-on-polyethylene hip prostheses.

In a prospective randomized study, 32 metal-on-metal prostheses and 29 ceramic-on-polyethylene prostheses of similar design were implanted in 59 patients. Radiolucency, cup migration, wear, and function were examined after a minimum of 2 years followup (followup rate, 87%). The purpose of the current study was to evaluate whether higher frictional torque of metal-on-metal will lead to a higher rate of early metal-on-metal cup loosening. A computer-assisted method was used for wear and migration measurements of the acetabular component. Metal-on-metal prostheses migrated in a craniocaudad direction significantly less than ceramic-on-polyethylene prostheses. The mean total migration for both types of prostheses exceeded 1.5 mm at 2 years. Clinically, no difference between the two prostheses regarding activity, pain, or range of motion was found at 2 years. As migration of metal-on-metal prostheses was not higher in comparison with ceramic-on-polyethylene prostheses, the expected higher frictional torque of metal-on-metal prostheses did not increase migration during short-term followup. The different debris produced by both bearings did not influence the short-term results of this study, but might cause different long-term results.

Heat distribution and heat transport in bone during radiofrequency catheter ablation.

BACKGROUND: To assess the feasibility of percutaneous radiofrequency ablation in large bone tumours, the heat distribution in cortical bone and marrow around inserted electrodes was measured. METHODS: Fresh bovine cadaver tibial bones were locally heated through drill holes for a maximum of half an hour using water-cooled single radiofrequency electrodes (Radionics Instruments Inc) by pulsed energy. Temperatures were measured in the marrow canal as well as in cortical bone by thermocouples at various distances from the inserted probes. RESULTS: Perpendicular to the probe, hyperthermia of more than 50 degrees C could be created in bone marrow in a sphere of approximately 3 cm, and of approximately 1 cm in cortical bone. CONCLUSION: As irreversible cellular damage can be expected when increasing the temperature to 50 degrees C for a duration of 6 min, this method may be effective for the minimal invasive ablation of neoplasms within human bone in cigar-shaped regions of approximately 3-cm diameter.