Thromboxane--co-factor of pulmonary disturbances in intramedullary nailing

Quantitative Evaluation of Embolic Load in Femoral and Tibial Shaft Fractures Treated With Reamed Intramedullary Fixation

OBJECTIVES

To compare the volume of embolic load during intramedullary fixation of femoral and tibial shaft fractures. Our hypothesis was that tibial intramedullary nails (IMNs) would be associated with less volume of intravasation of marrow than IM nailing of femur fractures.

DESIGN

Prospective observational study.

SETTING

Urban Level I trauma center.

PATIENTS/PARTICIPANTS

Twenty-three patients consented for the study: 14 with femoral shaft fractures and 9 with tibial shaft fractures.

INTERVENTION

All patients underwent continuous transesophageal echocardiography, and volume of embolic load was evaluated during 5 distinct stages: postinduction, initial guide wire, reaming (REAM), nail insertion, and postoperative.

MAIN OUTCOME MEASUREMENTS

Volume of embolic load was measured based on previously described luminosity scores. The embolic load based on fracture location and procedure stage was evaluated using a mixed effects model.

RESULTS

The IMN procedure increased the embolic load by 215% (-12% to 442%, P = 0.07) in femur patients relative to tibia patients after adjusting for baseline levels. Of the 5 steps measured, REAM was associated with the greatest increase in embolic load relative to the guide wire placement and controlling for fracture location (421%, 95% confidence interval: 169%-673%, P < 0.01).

CONCLUSIONS

Femoral shaft IMN fixation was associated with a 215% increase in embolic load in comparison with tibial shaft IMN fixation, with the greatest quantitative load during the REAM stage; however, both procedures produce embolic load.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Pulmonary fat embolism after reamed and unreamed nailing of femoral fractures

BACKGROUND

To determine whether reamed or unreamed intramedullary nailing of femoral fractures results in higher incidence of pulmonary fat embolism, three different methods of intramedullary nailing were compared in sheep. To analyze the presence of bone marrow fat embolism in pulmonary arteries, histological evaluation was undertaken using a quantitative computer-assisted measurement system.

METHODS

In this experimental model of 27 female Swiss alpine sheep, an osteotomy of the proximal femur was conducted in each animal. Then, the animals were divided into three groups according to the method of treatment: two different reamed intramedullary nailing techniques and an unreamed nailing technique were used. In the first group "ER" (experimental reamer; n=9), the nail was inserted after reaming with an experimental reamer; in the second group "CR" (conventional reamer; n=7), the intramedullary nail was inserted after reaming with the conventional AO-reamer. In the third group "UN" (unreamed; n=8) unreamed nailing was performed. During the operation procedure intramedullary pressure was measured in the distal fragment. After sacrificing the animals, quantitative histological analyses of bone marrow fat embolism in pulmonary arteries were done using osmium tetroxide fixation and staining of the fat.

RESULTS

The measurement of intramedullary pressure showed significantly lower values for reamed nailing than for the unreamed technique. The quantitative histological evaluation of lung vessels concerning bone marrow fat embolism revealed a statistically significant difference between reamed and unreamed insertion of the nail: 7.77%±6.93 (ER) and 6.66%±5.61 (CR) vs. 16.25%±10.05 (UN) (p<0.05) of the assessed lung vessels were filled with fat emboli. However, no difference was found between the traditional and experimental reamer.

CONCLUSIONS

Intramedullary nailing after reaming is a safe procedure with low systemic embolisation when compared to the unreamed insertion of the nail.

Physical and technical aspects of intramedullary reaming

Intramedullary pressure during reaming is influenced by various factors, including those of the patient, such as bone morphology and location and type of fracture, and those related to reaming technique and instruments. Through intensive research, technical developments and the use of modern materials, intramedullary pressure caused by modern reaming systems can be reduced to a minimum and, perhaps, completely avoided through use of the reaming-irrigation-aspiration system.

Experimental background--review of animal studies

Most of the research on the physiological effects of intramedullary nailing is technically difficult or ethically impossible to perform in humans. A substantial range of factors apply in clinical cases, which means that the data obtained from this source may lack the control needed to reveal the basic mechanisms of pathophysiology associated with this surgical procedure. Consequently, animal studies have been relied upon to provide answers that would otherwise be unavailable. This review manuscript summarizes the available literature on animal studies dealing with the local and systemic effects of intramedullary nailing. It focuses on whether these studies have contributed to our clinical knowledge of the procedure's impact on perfusion and fracture healing, as well as the medical relevance of coincident systemic effects.

DATA SOURCES

Medline, personal library of the first author and of the Department of Trauma Surgery, University of Pittsburgh Medical Center.

STUDY SELECTION

All animal studies on intramedullary stabilization published in English, German, and French.

CONCLUSIONS

The relevance of animal studies investigating the impact of a surgical procedure and its influence on concomitant injuries depends on the design and the type of the animal model. If this fact is considered, and if a model is selected that simulates a systemic impact comparable with the clinical situation, then animal studies may provide a valuable source of otherwise unobtainable information. Such an example is the study of fat embolization associated with intramedullary nailing. Animal subjects enable assessment of the intervention's additive surgical impact, measurement of side effects that may have adverse results, and influence of cofactors (eg, thoracic trauma, severe shock, polytrauma) that predispose the individual to postoperative complications.

Fat embolism: the reaming controversy

Intramedullary nailing is the preferred treatment method for stabilizing femoral diaphyseal fractures. Despite its superior biomechanical advantages over other implants, its use, particularly in selected groups of patients, has been questioned because of the possible harmful systemic effects of intramedullary reaming. The increase in intramedullary canal pressure during intramedullary nailing can result in intravasation of bone marrow and fat into the venous blood system. The subsequent consequences can be fat embolism syndrome (FES), adult respiratory distress syndrome (ARDS), and multiple organ failure. The lung seems to be the primary target for fat embolization and for the mediated effects primed by inflammatory reactions. In laboratory studies, both reamed and unreamed intramedullary nailing has been shown to alter selected pulmonary variables. Although transient, this effect appears to be more prominent with reamed than unreamed techniques. Additional studies are required to determine whether a subgroup of trauma patients is adversely affected by intramedullary reaming, thus necessitating other fixation techniques.

Evaluation of criteria for temporary external fixation in risk-adapted damage control orthopedic surgery of femur shaft fractures in multiple trauma patients: "evidence-based medicine" versus "reality" in the trauma registry of the German Trauma Society

BACKGROUND

Femur-shaft fracture treatment (FSFT) follows controversial management concepts after multiple trauma: primary-definitive osteosynthesis, secondary-definitive osteosynthesis after temporary external fixation (EF) in all patients, or individualized primary- or secondary-definitive osteosynthesis ("risk-adapted damage control orthopedics"). This study compares the concepts by analyzing literature evidence and a prospective multicenter database.

METHODS

A systematic literature analysis was performed. The German Trauma Society trauma registry was used to assess variables predictive of treatment concept.

RESULTS

Contradictory results in 63 controlled trials failed to support a "generalized management strategy." In all, 1,465 FSFTs in 8,057 trauma registry patients (age 39 +/- 19.5 years; Injury Severity Score [ISS] 23.5 +/- 14.9; 17.3% mortality) were treated initially (<24 hour) by EF, nail, or plate in 47.0%, 41.1%, and 11.9%, respectively. Despite large interhospital variability, EF was more likely with increasing severity of ISS, Glasgow Coma Score, thorax trauma, base excess, coagulation abnormalities, and initial probability of death.

CONCLUSIONS

Clinical "reality" reflects the controversies of "scientific evidence" for FSFT after multiple trauma in Germany. Although decision making is currently based on unvalidated criteria, anatomic and physiologic injury severity appears to influence the choice of management concept.

Cardiopulmonary complications of intramedullary fixation of long bone metastases

Intramedullary fixation of long bone metastases is an effective method of treating or preventing pathologic fractures. An important complication of this technique is the development of pulmonary embolism, which may occur at any number of steps during bone manipulation. Passage of normal marrow contents or tumor into the pulmonary circulation is thought to cause various biochemical, hemodynamic, or physical responses that lead to hypotension, arrythmia, and O2 desaturation. Death is a known risk of this procedure. Numerous surgical and anesthetic strategies have been developed to prevent or treat pulmonary embolic phenomena; however, the most important prophylaxis may be a heightened awareness of this possibility during any procedure that involves intramedullary manipulation of tumor containing bone.

Impact of intramedullary instrumentation versus damage control for femoral fractures on immunoinflammatory parameters: prospective randomized analysis by the EPOFF Study Group

BACKGROUND

Damage control orthopedic surgery has recently been advocated for the management of femoral shaft fractures in severely injured patients because surgical procedures were found to represent a second-hit phenomenon regarding the operative burden. It has been attempted to determine the operative burden by means of proinflammatory cytokines. In this study in clinically stable patients with multiple injuries, the effects induced by different types of primary fracture stabilization on the systemic release of proinflammatory cytokines were evaluated.

METHODS

This was a prospective, randomized, multicenter intervention study. Inclusion criteria were long bone shaft fracture of the lower extremity; age 18 to 65 years; Injury Severity Score > 16 or more than three extremity injuries (Abbreviated Injury Scale [AIS] score of 2 or more) in association with another injury (AIS score of 2 or more); and thoracic AIS score < 4. After informed consent, randomization for the treatment of the femoral shaft fracture was performed at admission. Groups were as follows: group I degrees FN (primary, < 24 hours) intramedullary nailing, and group DCO (DCO, I degrees ex.fix.) damage control orthopedic surgery and external fixation. In DCO patients, measurements were also performed at the time of conversion to the intramedullary procedure (DCO II degrees FN). Parameters included clinical parameters and complications (acute respiratory distress syndrome, multiple organ failure, sepsis). From serially sampled central venous blood, the perioperative concentrations of interleukin IL-1, IL-6, and IL-8 were determined. RESULTS Thirty-five patients were included (I degrees FN, n = 17; DCO, n = 18). In I degrees FN-patients, a perioperative increase of IL-6 levels was measured (preoperatively, 55 +/- 33 pg/dL; 24 hours postoperatively, +254 +/- 55 pg/dL; p = 0.03), which was not found in subgroup DCO I degrees Ex.fix.: preoperatively, 71 +/- 42 pg/dL; 24 hours postoperatively, 68 +/- 34 pg/dL; not significant [NS] or in group DCO II degrees FN: preoperatively, 36 +/- 21 pg/dL; 24 hours postoperatively, +39 +/- 25 pg/dL; NS. Likewise, in I degrees FN patients, a perioperative increase of IL-8 levels was measured only at the 7-hour time point (preoperatively, 35 +/- 29 pg/dL; 7 hours postoperatively, 95 +/- 23 pg/dL; p < 0.05), which was not found in group DCO I degrees Ex.fix.: preoperatively, 43 +/- 38 pg/dL; 24 hours postoperatively, 69 +/- 39 pg/dL; NS or in group DCO II degrees FN: preoperatively, 25 +/- 20 pg/dL; 24 hours postoperatively, 36 +/- 29 pg/dL; NS. There were no differences in the complication rate in terms of acute respiratory distress syndrome, sepsis, or multiple organ failure.

CONCLUSION

In this prospective, randomized, multicenter study, a sustained inflammatory response was measured after primary (<24 hours) intramedullary femoral instrumentation, but not after initial external fixation or after secondary conversion to an intramedullary implant. These findings may become clinically relevant in patients at high risk of developing complications. It confirms previous studies in that damage control orthopedic surgery appears to minimize the additional surgical impact induced by acute stabilization of the femur.

Cardiopulmonary, histological, and inflammatory alterations after lung contusion in a novel mouse model of blunt chest trauma

Severe blunt chest trauma remains an important injury with high morbidity and mortality. However, the associated immunological alterations are poorly understood. Existing big animal models require large-scale settings, are often too expensive, and research products for immunological studies are limited. In this study we aimed to establish a new model of blunt, isolated and bilateral chest trauma in mice and to characterize its effects on physiological and inflammatory variables. Male C3H/HeN mice (n = 9-10/group) were anesthetized and a femoral artery was catheterized. The animals were subjected to trauma or sham procedure and monitored for 180 min. Blunt chest trauma was induced by a blast wave focused on the thorax. Trauma intensity was optimized by varying the exposure distance. Blood pressure, heart rate, respiratory rate, arterial blood gases and plasma cytokine levels were measured. Macroscopic and microscopic examinations were performed. In addition, outcome was evaluated in a 10-day survival study. Chest trauma caused a drop (P < 0.05) in blood pressure and heart rate, which partly recovered. Blood gases revealed hypoxemia and hypercarbia (P < 0.05) 180 min after trauma. There was marked damage to the lungs but none to abdominal organs. Histologically, the characteristic signs of a bilateral lung contusion with alveolar and intrabronchial hemorrhage were found. Plasma interleukin-6 and tumor necrosis factor alpha were considerably increased after 180 min. Blunt chest trauma resulted in an early mortality of 10% without subsequent death. On the basis of these findings, this novel mouse model of blunt chest trauma appears suitable for detailed studies on immunological effects of lung contusion.

Biochemical changes after trauma and skeletal surgery of the lower extremity: quantification of the operative burden

OBJECTIVE

To quantify changes in variables of inflammation, coagulation, and fibrinolysis in blunt trauma patients with lower extremity fractures who underwent different types of surgical procedures.

DESIGN

Prospective, cohort study.

SETTING

Level I university trauma center.

PATIENTS

We allocated 83 blunt trauma patients in stable condition and 22 patients eligible for elective hip replacement to four treatment groups.

INTERVENTIONS

In 34 multiply traumatized patients with femoral fracture (group PTFF) and in 28 patients with an isolated femoral fracture (group IFF), primary unreamed intramedullary nailing for stabilization of the femoral shaft fracture was performed. In 22 patients, an elective uncemented total hip arthroplasty (group THA) was inserted for osteoarthritis, and in 21 control patients, an isolated ankle fracture (group AF) was acutely stabilized.

MEASUREMENTS AND MAIN RESULTS

From serially sampled central venous blood, the perioperative concentrations of interleukin (IL)-6, of tumor necrosis factor-alpha, of prothrombin fragments 1 + 2, and of D-dimer cross-linked fibrin degradation products were evaluated. Intramedullary instrumentation for an isolated femur fracture caused a significant perioperative increase in the concentrations of IL-6 (preoperative IL-6, 52 +/- 12 pg/mL; IL-6 30 mins postinsertion, 78 +/- 14 pg/mL; p = .02). This increase was comparable with group THA (preoperative IL-6, 46 +/- 16 pg/mL; IL-6 30 mins postinsertion, 67 +/- 11 pg/mL; p = .03). A positive correlation occurred between both groups (r = .83, p < .0004). Multiple trauma patients demonstrated significantly (p = .0002) higher IL-6 concentrations than all other groups throughout the study period and showed a significant increase after femoral nailing (preoperative IL-6, 570 +/- 21 pg/mL; IL-6 30 mins postinsertion, 690 +/- 24 pg/mL; p = .003), whereas no perioperative change was seen in group AF. The highest IL-6 increases were associated with a longer ventilation time (group PTFF) and a longer period of positive fluid balances (groups PTFF, IFF, THA). The coagulatory variables demonstrated similar perioperative increases in groups IFF and THA, but not in groups PTFF and AF. The IL-6 concentrations and the prothrombin fragments 1 + 2 concentrations correlated between groups THA and IFF at 30 mins and at 1 hr after surgery (r2 = .64, p < .02). In all patients the clinical variables were stable perioperatively.

CONCLUSIONS

Major surgery of the lower extremity causes changes to the inflammatory, fibrinolytic, and coagulatory cascades in patients with stable cardiopulmonary function. The inflammatory response induced by femoral nailing is biochemically comparable to that induced by uncemented total hip arthroplasty. In multiple trauma patients, increases, which occurred in addition to those induced by the initial trauma, were measured. Definitive primary femoral stabilization by intramedullary nailing imposes an additional burden to the patient with blunt trauma. A careful preoperative investigation is required to evaluate whether primary definitive stabilization can be performed safely.

The incidence of acute cardiorespiratory and vascular dysfunction following intramedullary nail fixation of femoral metastasis

Intramedullary nail fixation is a common treatment for metastatic tumors of the femur with overt or impending femoral fracture. This procedure sometimes causes severe cardiorespiratory and vascular dysfunction. The clinical relevance of this is not dear. We reviewed 45 operations in 43 patients, where intramedullary nail fixation was used to treat metastatic femoral fractures and impending fractures. We studied the incidence of intraoperative oxygen desaturation and hypotension associated with intramedullary manipulation as markers of cardiorespiratory and vascular dysfunction. Acute oxygen desaturation and hypotension occurred in 11 of our 45 patients. Of these, 3 died, 2 required intensive care postoperatively and 6 made uneventful recoveries. We hope to highlight a serious complication in this patient group.

Reamed versus nonreamed anterograde femoral nailing

OBJECTIVE

To compare reamed femoral nailing with unreamed femoral nailing.

DESIGN

Prospective, randomized.

SETTING

Two Level One trauma centers.

PATIENTS

One hundred seventy patients with 172 femur fractures were randomized to an unreamed or reamed group. MAIN OOUTCOME MEASURES: Data included demographics, Injury Severity Score (ISS), operative time, blood loss, blood and fluid requirements, technical complications, time to callus formation, time to union, and complications.

RESULTS

There was no statistical difference in operative time, transfusion requirements, or hypoxic episodes between the groups. Intraoperative blood loss was greater in the reamed group. The time to union was 80 +/- 35 days for the reamed group and 109 +/- 62 days for the unreamed group (p = 0.002). This difference was most dramatic in the distal femur, with union in the reamed group occurring in 80 days compared with 158 days in the unreamed group (p = 0.012). There were more technical complications and delayed unions in the unreamed group.

CONCLUSIONS

There is no advantage to the routine use of nailing without reamed insertion. Fractures treated with reamed nails heal faster than those treated with unreamed nails, especially distal fractures.

Comparison of mechanical loads produced by current intramedullary reamer systems

OBJECTIVE

This study evaluated the mechanical loading experienced by four clinically used intramedullary reamer cutter designs to evaluate the effects of variations in speed and feed rate on reamer system performance.

DESIGN

Biomechanical laboratory study.

SETTING

Research laboratory.

MAIN OUTCOME MEASURE

Four clinically used reamer systems with detachable cutters were tested using a computer-controlled machining system at representative reaming and drilling speeds of 250 and 750 revolutions per minute (RPM), respectively. Hard oak blocks with mechanical properties similar to cortical bone were reamed using cutter heads with diameters from nine to fourteen millimeters (in 0.5-millimeter increments) at feed rates of 1.0 and 7.6 centimeters per second. Reactive axial loads and torques were recorded and analyzed.

RESULTS

All systems demonstrated reduced maximal loads/torques for small reamer sizes (9 to 10.5 millimeters) at drilling speeds rather than reaming speeds. Individual systems demonstrated measurable differences in sensitivity to alterations in operating speed, indicating that some designs are not amenable to operation at increased speeds. In tests where reamer head cutting characteristics were isolated by using identical solid drive shafts, the deeply fluted design with a long lead taper and a rounded, burrlike body consistently produced significantly lower mechanical loading at all speeds and feed rates. In addition, two of the four systems tested use a larger flex shaft diameter for reamer head sizes of thirteen millimeters or greater. There was no indication of a need to use larger flex shafts for the larger reamers, based on mechanical load/torque data for those systems.

CONCLUSIONS

The tests performed demonstrate that appropriate control of reaming speeds (RPM) can be used to minimize mechanical loading for all systems. Caution should be exercised, however, so that any operational changes that reduce resistive loads and torques do not lead the surgeon to increased feed rates. Additional study is required to investigate the variable effects of increasing the operating speed of each system on localized thermal changes.

The effect of unreamed and reamed intramedullary nailing on the urinary excretion of prostacyclin and thromboxane A2 metabolites in patients with tibial shaft fractures

OBJECTIVE

To compare the effects of unreamed and reamed intramedullary nailing on the systemic production of prostacyclin and thromboxane A2 as assessed, respectively, by determinations of urinary 2,3-dinor-6-ketoprostaglandin F1alpha and 11-dehydrothromboxane B2 excretion.

METHODS

Ten otherwise healthy patients with closed and simple tibial shaft fractures were treated with unreamed intramedullary nailing, and 10 otherwise healthy patients with closed and simple tibial shaft fractures were treated with reamed intramedullary nailing. Urine was collected preoperatively and during the next 5 postoperative days. The samples were stored at -70 degrees C until assayed at the end of the study.

RESULTS

In the unreamed group, urinary 2,3-dinor-6-ketoprostaglandin F1alpha and 11-dehydrothromboxane B2 excretion remained stable and at a significantly lower levels compared with the reamed group during the entire study period (p < 0.021). In the reamed group, the alteration in urinary 2,3-dinor-6-ketoprostaglandin F1alpha excretion preoperatively and on the first postoperative day was nearly significant (p=0.075), and the increase in urinary 11-dehydrothromboxane B2 excretion was significant (p=0.020). The proportional increase compared with baseline, however, was 1.6 times greater for 11-dehydrothromboxane B2 than for 2,3-dinor-6-ketoprostaglandin F1alpha.

CONCLUSION

Only reamed intramedullary nailing elevates urinary 2,3-dinor-6-ketoprostaglandin F1alpha and 11-dehydrothromboxane B2 concentrations and their ratio (thromboxane A2/prostacyclin production) in patients with simple tibial shaft fractures.

Femur fractures in chest-injured patients: is reaming contraindicated?

OBJECTIVE

To determine if reamed femoral intramedullary nailing increases the pulmonary complications seen in chest-injured patients.

DESIGN

Retrospective review of prospectively collected trauma database data from January 1991 to October 1994.

SETTING

Methodist Hospital, Indianapolis, Indiana, Level I Trauma Center.

PATIENTS

Group I: Chest-injured patients [chest Abbreviated Injury Score (AIS) > or = 2] without femur or tibia fractures. Group II: Chest-injured patients (chest AIS > or = 2) with femoral reamed intramedullary fixation. Group III: Chest-injured patients (chest AIS > or = 2) with femoral shaft fixation using nonreamed fixation (rush rods, plating, or external fixation). Group IV: Non-chest-injured patients (chest AIS < 2) with femoral reamed intramedullary fixation. MAIN OUTCOME MEASUREMENT/HYPOTHESIS: Reamed femoral intramedullary nailing does not alter pulmonary outcomes, even in chest-injured patients.

RESULTS

Groups I and II had a very similar incidence of adult respiratory distress syndrome (ARDS), pneumonia, and number of ventilator days. Group III had a significantly higher incidence of ARDS and number of ventilator days than did Group I or II. Group III did not have a chest AIS score significantly different than Groups I and II. Group II had significantly higher ARDS and more ventilator days than did Group IV when only analyzing raw data. When injury severity was adjusted, there were no significant differences in pulmonary outcomes.

CONCLUSION

Reamed intramedullary femoral fixation did not increase pulmonary morbidity in chest-injured patients.

Thoracic trauma and early intramedullary nailing of femur fractures: are we doing harm?

INTRODUCTION

It has been reported that early intramedullary nailing (IMN) of a femur fracture in the presence of thoracic injury increases morbidity and mortality. The purpose of the present study was to determine if IMN < or = 24 hours after multisystem injury (Injury Severity Score (ISS) > 16) is associated with a poor hospital outcome in the presence of blunt thoracic trauma (Abbreviated Injury Scale (AIS) thorax score > or = 2).

METHODS

Retrospective cohort study at a single adult trauma center.

RESULTS

In a 6-year period, 149 blunt trauma patients had both an ISS > 16 and a femur fracture managed by IMN. These 149 patients were divided into four groups based on thoracic injury (T = AIS thorax score > or = 2; N = AIS thorax score < 2) and the timing of IMN (E = < or = 24 hours; L = > 24 hours). There were 68 TE, 57 NE, 15 TL, and 9 NL patients. The TE and NE groups were similar in age and ISS. TE and NE groups had similar durations of ventilation, critical care, hospital stay, and mortality. Furthermore, TE patients were no more likely to be intubated after IMN than NE patients. TE patients were matched with similar patients without a femur fracture and found to have similar hospital outcomes.

CONCLUSIONS

This study has not demonstrated an increased morbidity or mortality associated with early IMN in the presence of thoracic trauma.

The treatment of femoral shaft fractures using intramedullary interlocked nails with and without intramedullary reaming: a preliminary report

OBJECTIVE

To compare operative and postoperative variables in the treatment of femur fractures using interlocked intramedullary nails with and without reaming.

DESIGN

Prospective and randomized.

METHODS

81 consecutive patients with femur fractures treated with a stainless steel statically locked intramedullary nail. Whether or not reaming was done was randomized. There were 42 nails placed without reaming and 39 placed with reaming. There were no demographic differences between the two groups. Intraoperative and postoperative variables were studied. Interval healing was assessed by one observer on bimonthly radiographs.

RESULTS

There were more intraoperative technical complications in the group without reaming. There was no statistical difference in operative time, transfusion requirement, or time to union between the groups. In the reamed group callus formation occurred faster and there was slightly more blood loss (247 cc vs. 396 cc) (p < 0.05). However, when distal fractures were analyzed separately, the time to union was faster in the reamed group (< 0.05). Two patients in the unreamed group and none in the reamed group developed delayed unions. Pulmonary complications occurred in two patients, one in each group and did not appear to be related to the nailing.

CONCLUSION

Reamed canal preparation led to faster healing of distal fractures treated with statically locked intramedullary nails. Blood loss was greater in the reamed group but this did not translate into increased transfusion requirements. In this series, there was no advantage to nail insertion without reaming.

Effects on pulmonary physiology of reamed femoral intramedullary nailing in an open-chest sheep model

We have recently developed an open-chest sheep model to monitor and study the effects of major orthopedic procedures on pulmonary physiology. In this pilot study, we focused on reamed intramedullary femoral nailing in animals without pulmonary injury. Details of the model are described herein. The control group consisted of sheep that underwent thoracotomy and invasive monitoring only, while the study group also underwent femoral osteotomy, reaming, and intramedullary nailing. Baseline, postthoracotomy, and post-reaming/nailing values were recorded for mean pulmonary arterial pressure, central venous pressure, left arterial pressure, dynamic compliance, arterial blood gas, mixed venous O2, cardiac index, and mean arterial pressure so that hemodynamic and oxygen transport data could be calculated. Postprocedure values were recorded at hourly intervals for 4 h. A physiologically stable, reproducible model was created. No statistically significant differences were found between the control and experimental groups, indicating no adverse effect of femoral reaming/nailing. In one animal, using echocardiography, pulmonary embolization was documented while reaming and inserting the intramedullary nail. Reamed femoral intramedullary nailing is not detrimental to sheep with otherwise normal lungs. This finding suggests that femoral reaming and nailing in trauma patients without associated pulmonary injuries and otherwise normal lungs may be carried out without risk of inducing significant respiratory complications.

The microtip intramedullary probe for intraoperative pressure measurement

The implantation of femoral stem prostheses and intramedullary fracture stabilisation are well-established techniques in traumatology. Although the biomechanical advantages of intramedullary splinting are obvious, impairments of pulmonary circulation and respiratory function are typical and feared complications. These pulmonary disturbances are strikingly correlated with operation-induced intramedullary hypertension. A simple, low-invasive and reliable system for the measurement of intramedullary pressure is presented. At the heart of the system is a microtip probe, transforming changes of pressure into electric impulses, filtered and amplified in a pressure measuring system (PMS).