Previous studies have shown improved outcome following surgery for spinal cord compression due to metastatic disease. Further papers have shown that many patients with metastatic disease are not referred for orthopaedic opinion. The aims of this paper are to study the survival and morbidity of patients with spinal metastatic disease who receive radiotherapy. Do patients develop instability and progressive neurological compromise? Can we predict which patients will benefit from surgery?

Retrospective review of patients receiving radiotherapy for pain relief or cord compression as a result of metastatic disease. Patients were scored with regards to Tomita and Tokuhashi, survival and for deterioration in neurology or spinal instability.

94 patients reviewed. All patients were followed up for a minimum of 1 year or until deceased. Majority of patients had a primary diagnosis of lung, prostate or breast carcinoma.

Mean Tomita score of 6, Tokuhashi score 7, and mean survival following radiotherapy of 8 months. 11:94 patients referred for surgical opinion. Poor correlation with Tomita scores (-0.25) & Tokuhashi scores (0.24) to predict survival. Four patients developed progressive neurology on follow-up. One patient developed spinal instability. The remainder of the patients did not deteriorate in neurology and did not develop spinal instability. All patients with normal neurology at time of radiotherapy did not develop spinal cord compression or cauda equina at a later date.

This study suggests that the vast majority of patients with spinal metastatic disease do not progress to spinal instability or cord compression, and that prophylactic surgery would not be of benefit. The predictive scoring systems remain unreliable making it difficult to select those patients who would benefit. The referral rate to spinal surgeons remains low as few patients under the care of the oncologists develop spinal complications.

Introduction

Following the publication of our original survey in 2000 (Eur. Sp. J. 11(6):515-8 2002) we have sought to re-evaluate the perceptions and attitudes towards spinal surgery of the current UK orthopaedic Specialist Registrars (SpRs), and to identify factors influencing an interest in spinal surgery. At that time 175 orthopaedic spinal surgeons in the UK needed to increase by 25% to satisfy parity with other European countries.

Introduction

This study investigates the effect of somatisation on results of lumbar surgery.

It is thought that metal ions from metal on metal bearing hip replacements cause DNA damage and immune dysfunction in the form of T cell mediated hypersensitivity. To explore the hypothesis that there is a relationship between metal ion levels and DNA damage and immune dysfunction in matched patient groups of hip resurfacings and standard hip replacements reflected in the levels of lymphocyte subtypes (CD3+ T cells, CD4+ T helper cells, CD8 +T cytotoxic/suppressor cells, CD16 +Natural Killer and CD19+ B cells) in peripheral blood samples, we analysed peripheral blood samples from 68 patients: 34 in the hip resurfacing group and 34 in the standard hip arthroplasty group. Samples were analysed for counts of each sub-group of lymphocyte and cytokine production. Whole blood cobalt and chromium ion levels were measured using inductively-coupled mass spectrometry. All hip components were well fixed.

Cobalt and chromium levels were significantly elevated in the resurfacing group compared to the hybrid group (p<0.001). There was a statistically significant decrease in the resurfacing group's level of CD8+ cells (T cytotoxic/suppressor) (p=0.010). No other subgroup of lymphocytes was significantly affected. Gamma interferon levels post antigen challenge were severely depressed in the hip resurfacing group.

A threshold level of blood cobalt and chromium ions for depression of CD8+ T cells was observed. Hip resurfacing patients have levels above this threshold whilst standard hip replacements fall below it. The patients all had normal levels of CD16 +Natural Killer and CD19+ B cells suggesting that this is not a bone marrow toxic effect. Cytokine analysis confirmed that some aspects of T cell function in hip resurfacing patients are severely depressed.

Objective

To assess the effectiveness of dynamic stabilisation as a treatment for discogenic pain compared to standard treatment of interbody fusion.

Study Design & Subjects

All patients were referred for a 2 year back-pain management programme. Patients with continued pain following conservative treatment underwent discography & MRI. Patients with painful degenerate discs on the above investigations were selected.

Patients underwent interbody fusion (PLIF/TLIF) or dynamic stabilisation.

Mean follow-up was 24 months with a minimum follow-up of 12 months.

Introduction: Surgical fixation of intra-articular distal femoral fractures has been associated with nonunion & varus collapse. The soft tissuestripping associated with this fracture andthe surgical exposure have been factors associated with delayed union & infection. The limited soft tissue exposure has been lauded the as a solution to this fracture. However, it has occurred with the new fixation as well.(Locked Plate)

Aims: This study is an attempt to look at the fixation. Does the LISS system improve the results of this difficult fracture? Is there truly a difference in the outcome of this fracture utilizing the Locked plate system or is the percieved difference due to the surgical mini invasive approach.

Patients & Methods: One hunderd & forty patients were screened, only 53 were randomized and fixed in six academic centers over 5 years. All C3 fractures were excluded as they were felt not to be treatable by the DCS device, but they were treated appropiately. 35 females and 18 males were included in the study and randomized appropiatley.

Results: Fifty-three patients were randomized, 28 had the LISS implant and 25 had the DCS utilized. There were 3 nonunions in the LISS group plus two patients with early loss of reduction that required reoperation in the early post operative period. One patient developed arthrofibrosis requiring arthroscopic release and subsequently the implant failed necessitating refixation. In the DCS group, only one nonunion reported & required second surgery. This translated to a reoperation rate of 21% in the LISS group compared to 4% with DCS.

Conclusion: This prospective randomized multicentre trial showed a difference when comparing the LISS to the DCS in the supracondylar distal femur fractures.

The recent NICE guidelines on management of osteoarthritis outline weight loss as first line treatment in degenerative joint disease in the obese. There is little data surrounding the effects of obesity on the outcomes in spinal surgical interventions. Intervertebral discectomy is one treatment for prolapse of a lumbar vertebral disc. We aim to investigate the effect of obesity on outcomes for discectomy.

Demographic details including age, sex, weight and BMI were recording with a pre-operative Oswestry Disability Index (ODI). The fat thickness was measured at L5/S1 using calibrated MRI scans. Outcome measures included complications, length of surgery and change in ODI at 1 year following surgery. Obesity was defined as a body mass index of over 30. The units Serial patients undergoing discectomy were recruited into the study. Patients with bony decompression, instrumentation, revision surgery or multilevel disease were excluded.

Fifty patients with a single level uncomplicated disc prolapse were entered into the study. Sixteen patients had a BMI over 30 and so were obese, whilst 34 had a BMI of less than 30. The mean pre-operative ODI was 46.5 in the obese group and 52 in the normal group this difference was not significant (p> 0.05). The mean post operative ODI was statistically improved in the high BMI group at 28 (18.5 point improvement) and 25.2 (29.1 point improvement) in the normal group. The ODI improvement was significantly better in the low BMI group (p=0.036). There was no significant difference in operative time (p=0.24). Only a single patient had a complication (dural leak), so no valid comparison could be made.

The outcomes of spinal surgery in the obese are mixed.

We found no increase in the complication rate or intra-operative time associated with an increased BMI. However, the improvement in ODI was significantly better in the normal BMI group.

Aims: There are concerns over the physiological effects of intramedullary femoral fracture stabilisation in patients with pulmonary injury. This large animal study used invasive monitoring to obtain sensitive cardiopulmonary measurements and compared the responses of ‘Early Total Care’ (intramedullary fracture fixation) and ‘Damage Control’ (external fixation), after the induction of lung injury.

Methods: Acute lung injury (PaO2/FiO2 < 200 mmHg) was induced in 12 invasively monitored and terminally anaesthetised sheep via oleic acid infusion into the right atrium. Each animal underwent surgical femoral osteotomy and fixation with either reamed intramedullary (n=6) or external fixation (n=6). Haemodynamic and arterial blood-gas measurements were recorded at baseline, 5, 30 and 60 minutes after fracture stabilisation.

Results: The mean (+/− S.E.) PaO2/FiO2 fell significantly (p< 0.05) from 401 (+/− 39) to 103 (+/− 35) and 425 (+/− 27) to 122 (+/− 21) in the externally fixated and intramedullary nailed groups respectively after acute lung injury. The further combined effect of surgical osteotomy and fracture fixation produced a mean (+/− S.E.) PaO2/FiO2 of 98 (+/− 21) and 114 (+/− 18), in the externally fixated and intramedullary nailed groups immediately after surgery. This was not significantly different within or between groups. Similarly the pulmonary vascular resistance (PVR) measured at 5.8 (+/− 0.8) and 4.8 (+/− 0.7) after lung injury in the externally fixated and intramedullary nailed groups changed to 5.7 (+/− 0.5) and 4.0 (+/− 0.7) after surgical osteotomy and fracture fixation (no significant difference within or between groups). The PaO2/FiO2 or PVR was not significantly different at the monitored 5, 30 and 60 minute intervals after fracture stabilisation.

Conclusion: Against a background of standardised acute lung injury, there was no further deterioration produced by the method of isolated femoral fracture fixation in sensitive physiological parameters commonly used during intensive care monitoring.

Introduction: There is little evidence for the long term efficacy of selective nerve root injections (SNRI) in the control of lumbar radiculopathy. We report the 5 year results of a prospective study of SNRI in the lumbar spine.

Methods: All patients considered to be operative candidates by two treating surgeons (JMP and DJS) with unilateral/bilateral radicular leg pain were included. Patients had a mean history of radicular symptoms of 12.8 months (4 months–3 years). All had an SNRI under image intensifier control with local anaesthetic and steroid. Each patient was evaluated pre-operatively, 2 months, 6 months, 1 year, 2 year and 5 years with VAS and ODI scores.

Results: Sixty-two consecutive patients were reviewed. The mean age of patients was 54.5 years (36–80 years). 92 injections were performed. Symptoms were caused by degenerative disease (n=32), disc herniation (n=25), and previous surgery (n=3).

The ‘disc’ group was significantly younger than ‘degenerative’ group (49.4 yrs vs. 58.4 yrs; p=0.004). There were significant improvements in low back pain (LBP), leg pain (LP), and ODI at 2 months in all patients. At 5 years the disc group did better with both leg and back pain; whilst there was only a significant reduction in leg pain in the degenerative group. Over 90% (n=56) of patients had no operative intervention; a subgroup of 8 had further injections. Within the degenerative group, ODI and VAS deteriorate early on indicating that a second injection option in this group may be worthwhile.

Conclusion: At five-years, most patients avoid operative treatment because of improved symptom control with SNRI. Regression analysis showed “duration of symptoms” and “age” is predictive of good outcome at one year post SNRI, but gender and, diagnosis are not.

Previous studies have shown improved outcome following surgery for spinal cord compression due to metastatic disease. Further papers have shown that many patients with metastatic disease are not referred for orthopaedic opinion. The aims of this paper are to study the survival and morbidity of patients with spinal metastatic disease who receive radiotherapy.

Do patients develop instability and progressive neurological compromise?

Do patients require surgery or are the majority adequately treated by oncologists?

Review of patients receiving radiotherapy for pain relief or cord compression as a result of metastatic disease. Patients were scored with regards to Tomita and Tokuhashi, survival and for deterioration in neurology or spinal instability.

94 patients reviewed. All patients were followed up for a minimum of 1 year or until deceased.

Majority of patients had a primary diagnosis of lung, prostate or breast carcinoma.

Mean Tomita score of 6, Tokuhashi score 7, and mean survival following radiotherapy of 8 months.

11:94 patients referred for surgical opinion.

Four patients developed progressive neurology on follow-up.

One patient developed spinal instability. The remainder of the patients did not deteriorate in neurology and did not develop spinal instability.

All patients with normal neurology at time of radiotherapy did not develop spinal cord compression or cauda equina at a later date.

This study suggests that the vast majority of patients with spinal metastatic disease do not progress to spinal instability or cord compression, and that prophylactic surgery would not be of benefit.

The referral rate to spinal surgeons remains low as few patients under the care of the oncologists develop spinal complications.

Introduction and aim: We have previously shown an association between whole blood metal ions and reduced CD8+ T cells in patients with unilateral metal on metal (MOM) hip resurfacings. Our aim was to substantiate this controversial finding with a follow up cohort of larger numbers of patients before further immunological investigation.

Method: We measured lymphocyte subset counts and whole blood Cobalt and Chromium in 2 groups of patients: a Birmingham hip resurfacing group (n=100); and a metal on polyethylene MOP hip arthroplasty group (n=34). Metal ions were measured using inductively-coupled mass spectrometry (ICP-MS) with a Dynamic Reaction Cell (DRC). The detection limit was 10 parts per trillion. All hip components were well fixed, clinically and radiologically.

Results: Cobalt and chromium levels were significantly elevated in the MOM resurfacing group compared to the MOP group (p< 0.0001). There was a statistically significant decrease in the MOM resurfacing groups’ level of CD8+cells (T cytotoxic) (p=0.005) when analysed by a Mann-Whitney U test. There was no significant difference between levels of CD4+ (T helper cells), CD19+ (B cells) and CD16/56+ (Natural Killer cells). A threshold level of blood cobalt and chromium ions for depression of total numbers CD8+ T cells was observed.

Conclusions: This follow up cohort of 100 MOM hip resurfacing patients has replicated the association of reduced CD8+ T cells and raised metal ion levels observed in our founder cohort. This was specific to CD8+ T cells. We are now more certain that this association needs further detailed immunological investigation.

Introduction and aim: We have previously shown suppressed levels of CD8+ T lymphocytes in patients with metal-on-metal (MOM) hip resurfacing compared to patients with metal on polyethylene hip replacements. Functional assessment of T lymphocytes may help to determine the importance of this CD8+ reduction following hip resurfacing.

Method: We isolated peripheral blood mononuclear cells (PBMC) from patients with unilateral MOM hip resurfacing (n=7) and healthy controls without hip replacement (n=8). Patients with hip resurfacing had excellent Harris Hip scores (mean 90) and well fixed components on radiographs. Whole blood and serum levels of Cobalt (Co) and Chromium (Cr) ions were measured with Inductively-Coupled Mass Spectrometry. T cell function was assessed by

cell proliferation assays (3H-thymidine incorporation) and

Results: Co and Cr ion levels were significantly elevated in the MOM hip resurfacing group compared to the control group (p< 0.001). Proliferation rates of T cells were comparable between the two groups over one week, but interferon-gamma (IFN-γ) production in the MOM hip resurfacing group was significantly decreased (p < 0.05), when compared to the control group.

Conclusion: IFN-γ is normally produced by CD8+ (T cytotoxic cells) and CD4+ (T helper 1 cells) in response to viral infection and high levels of IFN-γ is associated with autoimmune disease. Raised levels of metal ions from hip resurfacing reduces the production of IFN-γ following stimulation with PHA. This finding has been patented for potential therapeutic use through MRC technology.

Introduction: This study investigates the effect of somatisation on results of lumbar surgery.

Methods: Pre- and postoperative data of all primary discectomies and posterior lumbar decompressions was prospectively collected. Pain using the Visual Analogue Score (VAS) and disability using the Oswestry Disability Index (ODI) were measured. Psychological assessment used the Distress Risk Assessment Method (DRAM). Follow-up was at 1 year.

Results: There were a total of 320 patients (average age 49.7 years). Preoperatively there were 61 Somatising and 75 psychologically Normal patients. 47 of the pre-operative Somatisers were available for follow-up.

All pre-operative parameters were significantly higher compared with the Normal group (back pain VAS 6.3 and 3.8; leg pain VAS 7 and 4.7; ODI 61 and 34.4 respectively).

At 1 year follow-up, 23% of the somatising patients became psychologically Normal; 36% became At Risk; 11% became Distressed Depressed; and 30% remained Distressed Somatisers.

The postoperative VAS for back and leg pain of the 11 patients who had become psychologically Normal was 3.4 (pre-op 6.8) and 3.2 (pre-op 6.6) respectively. In the 14 patients who remained Distressed Somatisers the corresponding figures were 5.6 (pre-op 7.8) and 6.7 (pre-op 7.0).

The postoperative ODI of the 11 patients who had become psychologically Normal was 26.4 (pre-op 55.5). In the 14 patients who remained Distressed Somatisers the corresponding figures were 56.7 (pre-op 61.7).

These differences are statistically significant.

Discussion: Patients with features of somatisation are severely functionally impaired preoperatively. One year following lumbar spine surgery, 60%(28) had improved psychologically, 23%(11) were defined as psychologically normal. This was associated with a significant improvement in function and back and leg pain. The 14(30%) patients who did not improve psychologically and remained somatisers had a poor functional outcome. Our results demonstrate that psychological distress is not an absolute contraindication to lumbar spinal decompressive surgery.

Introduction: This study investigates the effect of soma-tisation on results of lumbar surgery.

Methods: Pre- and postoperative data of all primary discectomies and posterior lumbar decompressions was prospectively collected. Pain using the Visual Analogue Score (VAS) and disability using the Oswestry Disability Index (ODI) were measured. Psychological assessment used the Distress Risk Assessment Method (DRAM). Follow-up was at 1 year.

Results: There were a total of 320 patients (average age 49.7 years). Preoperatively there were 61 Somatising and 75 psychologically Normal patients. 47 of the pre-operative Somatisers were available for follow-up.

All pre-operative parameters were significantly higher compared with the Normal group (back pain VAS 6.3 and 3.8; leg pain VAS 7 and 4.7; ODI 61 and 34.4 respectively).

At 1 year follow-up, 23% of the somatising patients became psychologically Normal; 36% became At Risk; 11% became Distressed Depressed; and 30% remained Distressed Somatisers.

The postoperative VAS for back and leg pain of the 11 patients who had become psychologically Normal was 3.4 (pre-op 6.8) and 3.2 (pre-op 6.6) respectively. In the 14 patients who remained Distressed Somatisers the corresponding figures were 5.6 (pre-op 7.8) and 6.7 (pre-op 7.0).

The postoperative ODI of the 11 patients who had become psychologically Normal was 26.4 (pre-op 55.5).

In the 14 patients who remained Distressed Somatisers the corresponding figures were 56.7 (pre-op 61.7).

These differences are statistically significant.

Discussion: Patients with features of somatisation are severely functionally impaired preoperatively. One year following lumbar spine surgery, 60%(28) had improved psychologically, 23%(11) were defined as psychologically normal. This was associated with a significant improvement in function and back and leg pain. The 14(30%) patients who did not improve psychologically and remained somatisers had a poor functional outcome. Our results demonstrate that psychological distress is not an absolute contraindication to lumbar spinal decompressive surgery.

Introduction: Following the publication of our original survey in 2000 (Eur. Sp. J.11(6):515–8 2002) we have sought to re-evaluate the perceptions and attitudes towards spinal surgery of the current UK orthopaedic Specialist Registrars (SpR’s), and to identify factors influencing an interest in spinal surgery. At that time 175 orthopaedic spinal surgeons in the UK needed to increase by 25% to satisfy parity with other European countries.

Methods: A postal questionnaire was sent to all 950 SpR’s. The questionnaire sought to identify perceptions in spinal surgery, levels of current training and practice, and intentions to pursue a career in spinal surgery.

Results: As before, a 70% response rate has confirmed that 74% of trainees intend to avoid spinal surgery (69% in 2000). However 10% are committed to become a Specialist Spinal Surgeon (9% in 2000). Their perceptions were wide ranging but most concluded that the intellectual challenge and opportunities for research are widely recognised. However enthusiasm is dampened by poor perceptions of outcomes from surgery, negative somatization and depression associations, complications and the fear of litigation. In some areas there is inadequate exposure to spinal surgery during the first 4 years of training.

Conclusions: Spinal surgery remains a career choice for 10% of surgical trainees (up 1% since 2000). With a large SpR expansion (578 to 950 SpRs in the last 5 years) an average of 16 new spinal surgeons annually will be produced over the next six years. This has improved on the figure of 8.6 per year from 2000 and represents a 200% increase in numbers per year. These figures suggest that by 2011 and allowing for retirement, there should be enough spinal surgeons to meet the desired UK/Europe ratio.

Introduction: There have been 70,000 hip resurfacings implanted, predictions are for it to become 12% of the US hip replacement market by 2010 (Goldmann Sachs report Oct 2005). There is concern that the cobalt and chromium ions released from metal on polyethylene hip replacements cause immune dysfunction in the form of T cell mediated hypersensitivity (indicated by increased numbers and stimulation of T cells). If metal ions cause significant effects on white blood cells we might reasonably expect to detect this by simply measuring numbers of white blood cells.

Aim : To examine the possibility that raised metal ions may cause an abnormal number of white blood cells, termed a blood dyscrasia.

Method : Peripheral blood samples were analysed from 68 patients: 34 in the hip resurfacing group and 34 in the standard hip arthroplasty group. Samples were analysed for counts of each sub-group of lymphocyte. Functional assessment was also performed using a activation panel of white cell CD markers. Whole blood cobalt and chromium ion levels were measured using inductively-coupled mass spectrometry. All hip components were well fixed.

Results : Cobalt and chromium levels were significantly elevated in the resurfacing group compared to the hybrid group (p< 0.001). There was a statistically significant decrease in the resurfacing groups’ level of CD8⁺ cells (T cytotoxic/suppressor) (p=0.010). There was a characteristic pattern of immune modulation seen on the activation panel.

Conclusions : We found an immune modulation in patients with metal on metal hip resurfacing. This was not a hypersensitivity reaction. This change in T cell function may be detrimental or beneficial to patients.

The British Orthopaedic Association has endorsed a website, www.orthoconsent.com, allowing surgeons free access to a bank of pre-written consent forms. These are designed to improve the level of information received by the patient and lessen the risk of successful litigation against surgeons and Health Trusts.

Purpose: The purpose of this study is to evaluate the hemodynamic and pulmonary effects of intramedullary nailing with a removable filter placed into the common iliac vein.

Methods: Under general anaesthesia, a collapsible filter was inserted into the left common iliac vein in eight dogs and compared to a control group from a previous study. The left femora and tibiae were then pressurized by injection of bone cement and the insertion of intramedullary rods. Echocardiographic images and hemodynamic measurements including arterial blood gas, cardiac output, left atrial, right atrial, pulmonary arterial, and aortic pressure were recorded as baseline measurements and at 1, 5 and 15 minutes after medullary-canal pressurization. After fifteen minutes of pressurization the filter debris was evacuated, the samples sent for analysis and the filter was collapsed and removed. The dog’s hemodynamics were then monitored for a further fifteen minutes. The animals were killed and the lungs were harvested for histomorphometric analysis.

Results: Full hemodynamic and histomorphometric results of the lung tissue and debris collected from the evacuated filters are still pending at the time of this submission however initial findings indicate that the filter prevented an immediate increase in mean pulmonary artery pressure after canal pressurization. No large embolic event was visualized in any of the filtered dogs. In contrast, all animals in the control group demonstrated moderate-to-severe echogenic response with intense showering of echogenic material, including large embolic masses. Removal of the filter was safe and repeatable.

Conclusions: This experiment has shown that proximal venous blockade by means of a removable filter was able to reduce the size and the quantity of the embolic load on the lungs and the filter could be safely collapsed and removed after suctioning of the debris. High rates of embolization causing increased morbidity and mortality after intramedullary stabilization of pathological fractures and of traumatic fractures with concomitant lung injury have been reported. Prophylactic insertion of a removable temporary filter in this high-risk group prior to reamed intramedullary nailing may be beneficial.

Funding : Other Education Grant

Funding Parties : Synthes Canada

Using an established canine model of fat embolization, the effect of temporary mechanical blockade of embolic load during medullary canal pressurization was studied. Haemodynamic measurements, echocardiography and postmortem histomorphometry were used as outcome measures. There was statistically significant difference between the filter and the control groups, when the pulmonary vascular resistance, the percentage area of lungs occupied by fat and the percentage of pulmonary vasculature occupied by fat were compared. We have shown that mechanical blockade by a filter does stop the adverse effect on the lungs during canal pressurization.

Acute intramedullary stabilization of femoral fractures in multiply injured patients still remains controversial. Intravasation of medullary fat has been suspected to trigger ARDS. This study investigates the effect of a filter placed into the ipsilateral common iliac vein during medullary canal pressurization.

Using an established canine model, twelve mongrel dogs were randomized into two groups. A special filter was inserted percutaneously into the left common iliac vein in half the dogs where as the other half served as controls. In all dogs, the left femora and tibiae were pressurized by injection of bone cement and insertion of intramedullary rods. Hemodynamic measurements and echocardiography images were recorded continuously. After sacrifice, the lungs were harvested for analysis.

The mean pulmonary artery pressure at three minutes of pressurization was 12 mm of Hg in the filter group and 28mm of Hg in the control group. The pulmonary vascular resistance in the control group was increased from the 3^rd minute of pressurization throughout the experiment. This was statistically significant when compared with the baseline. There was no such change seen in the filter group. Transesophageal echocardiography showed less embolic shower in the filter group and histomorphometry demonstrated statistically signifant difference, when the percentage area of lungs and the percentage of pulmonary vasculature occupied by fat in the filter group as compared to the control group.

This canine study has demonstrated that mechanical blockade by a venous filters can significantly reduce the embolic load on the lungs during canal pressurization.

Introduction: Early stabilization of the skeleton in multiply injured patients has shown to reduce mortality and chest morbidity. Reamed intramedullary nailing is the current method of choice for stablizing femoral and tibial shaft fracture. However several investigators have highlighted the adverse effect of early reamed nailing in polytrauma patients. Intravasation of medullary fat during canal pressurizaton has been suspected to produce a ‘second hit’ and trigger pneumonia and ARDS. The objective of this study is to investigate the effect of a filter placed into the ipsilateral common iliac vein during medullary canal pressurization.

Methods: Using an established model of fat embolization, twelve mongrel dogs were randomized into two groups. Under general anaesthesia, cannulations of carotids and jugular veins and transesophageal echo-cardiography were performed in all animals. Under fluoroscopy control, a special filter was inserted percutaneously into the left common iliac vein in half the animals, where as the other half served as controls. In all dogs, the left knee was exposed; the femor and tiiba were sequentially reamed and then pressurized by injection of bone cement and insertion of intramedullary rods. Hemodynamic measurements and trans-esophageal echocardiography images were recorded continuously during the surgical procedure. After 45 minutes from pressurization, the dogs were sacrificed and the lungs and kidneys were harvested and fixed for histological analysis.

Results: There was significant difference noticed in the right-sided pressures and oxygen tension between the filter and the control groups. The mean pulmonary artery pressure at 3 minutes of pressurization was 12mm of Hg in the filter group and 28mm of Hg in the control group. Transesophageal echocardiography showed less embolic shower in the filter group and also lesser dilatation of right ventricles. Histomorphometry with special staining demonstrated much less proportion of lungs to be occupied by fat in the filter group as compared to the control group.

Discussion and Conclusion: This canine study has demonstrated that mechanical blockade by a venous filter can significantly reduce the emobilic load on the lungs in an established model of fat embolization. A suitable filter with suction system is being designed for possible use in high-risk patients.