Fracture healing after reamed and unreamed intramedullary nailing in sheep tibia

Intramedullary nailing is a well-established method for stabilisation of long-bone shaft fractures. It is still a controversy as to whether the procedure should be done by an unreamed or reamed technique.In the present animal study, 24 sheep were treated with intramedullary nailing. Midshaft fractures (Arbeitsgemeinschaft für Osteosynthese (AO) type 42-A2/3) were created. Eight sheep were treated with an unreamed nailing technique (UN), a further eight sheep underwent tibia nailing by the reamed technique using the conventional AO reaming system (RC) and in a further eight sheep, reamed nailing was performed using an experimental reaming system (RE). Intra-operatively, the intramedullary pressure was measured and, during a healing time of 10 weeks, the growth of callus formation was labelled with fluorescence markers after 4 and 6 weeks. After 10 weeks, the animals were euthanised and the quality of fracture healing was determined by recording stiffness in torsion, antero-posterior and mediolateral bending and the load at yield. In addition, the callus formation at the fracture zone was evaluated by fluorescence microscopy and macroradiographs.The results showed a decrease of intramedullary pressure when reamed nailing was performed with the RE (72.5 mmHg) system compared with the conventional AO reaming system (227 mmHg). Mechanical testing did not reveal any significant differences either for torsional or bending stiffness or for load at yield for any of the three procedures. Histological evaluation showed a similar callus formation for the UN group and the RE group. Callus formation in the UN (65 mm²) and RE (63 mm²) groups showed a higher increase during the first 6 weeks than those treated with the conventional AO reaming system (27 mm²). This means that, especially during the first weeks of fracture healing, damage to the bone by the reaming process can be reduced by reaming with a reaming device with lowered cutting flutes and smaller drive-shaft diameter.Intramedullary pressure can be significantly reduced by using reaming systems with reduced drive-shaft diameters and deepened cutting flutes. In the early phase of fracture healing, callus formation can be influenced positively when using the RE system.     

Similar central hemodynamics and oxygenation in reamed and unreamed intramedullary nailing of tibial fractures

BACKGROUND: Reamed intramedullary nailing of a long bone fracture is considered to be of crucial importance in the genesis of pulmonary disturbances. Use of unreamed nailing technique has been encouraged to avoid temporary deterioration in lung functions. METHODS: Central hemodynamic changes were recorded in 20 healthy adults with a unilateral simple tibial fracture undergoing reamed or unreamed intramedullary nailing. The patients were cannulated with a pulmonary artery catheter. Intramedullary nailing was performed during general anesthesia. Pre- and immediate postoperative hemodynamic variables were compared. RESULTS: Unchanged cardiac performance but pathologically altered pulmonary vascular tone were unrelated to the type of nailing technique. Increased oxygen consumption was observed as well. CONCLUSION: Changes in cardiac and pulmonary hemodynamics are already present after the trauma and before the intramedullary nailing procedure.     

Fat extravasation due to unreamed and experimentally reamed intramedullary nailing of the sheep femur

Aim

To compare systemic fat extravasation in unreamed and experimentally reamed nailing.

Methods

An osteotomy was created in the proximal third of the femoral shaft in 16 sheep, and intramedullary pressure increase and fat extravasation were monitored for the two nailing techniques.

Results

The highest intramedullary pressures, median 2700 mmHg, and highest percentages of fat extravasation, peaking at almost 90% of fat, were found for the unreamed nailing technique. The values for the reamed group were significantly lower.

Conclusions

The extravasation of intramedullary fat can be attributed to the great increase in intramedullary pressure that occurs during unreamed nailing. Correctly performed intramedullary reaming with the new reaming system produces lower pressures and much less systemic fat extravasation, reducing the risk for fat embolism.     

Effects of reamed or unreamed intramedullary nailing under non-damaged conditions on pulmonary function in sheep

BACKGROUND: Pulmonary damage after reamed or unreamed femoral nailing has been controversial in clinical and experimental studies. We investigated changes in pulmonary function and coagulatory response in normal lungs of sheep after reamed or unreamed intramedullary nailing of an unfractured femur. METHODS: We used three groups of sheep (each group, n = 6): reamed femoral nailing (RFN); unreamed femoral nailing (UFN); and sham control group. Femoral osteotomies and lung contusions were not made. Hemodynamic monitoring data and blood gas data (BGD) were recorded, and blood samples for biochemistry (antithrombin III, lipid peroxidase and fibrinogen) were collected 0 to 6 hours after nailing. Bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in pulmonary tissue were analyzed 6 hours after nailing. RESULTS: There were no significant differences in time course of hemodynamic monitoring data, BGD, or biochemical data among the three groups. In BALF analysis, the lipid-laden cell count in the RFN group was higher than those of the other groups, and MPO activity was highest in the RFN group. CONCLUSION: RFN did not affect pulmonary function at the physiologic level or affect the coagulatory system at the acute stage, but RFN under non-damaged conditions could lead to leukocyte activation in lung tissue without worse alteration of alveolar permeability in the acute post-operative course.     

Fat embolism and related effects during reamed and unreamed intramedullary nailing in a pig model

OBJECTIVES: To determine whether reamed or unreamed femoral intramedullary nailing is more adverse to pulmonary function, the authors compared three populations of healthy pigs, analyzing the biochemical and hemodynamic effects related to fat embolism. Likewise, the authors histologically evaluated the presence of bone marrow fat embolism in lungs, heart, kidney, brain, and retina. DESIGN: Randomized, experimental model. SETTING: Laboratory. PARTICIPANTS: Twenty-five male Duroc Jersey adult healthy pigs divided in three groups. INTERVENTION: Reamed and unreamed intramedullary nailing. OUTCOME MEASUREMENTS: Biochemical, hemodinamical, and histologic analysis. METHODS: In the first group of ten pigs, a reamed nail was inserted; in the second group of ten specimens, the authors placed an unreamed nail; and in the third group of five animals (control), only the surgical approach was made without opening the medullary cavity. RESULTS: The authors did not find statistically significant differences in pulmonary function between the reamed and unreamed group in the hemodynamic, biochemical, and histopathologic parameters evaluated. The histologic analysis of the lung tissue revealed a statistically significant difference between the nailed groups and the control (P < 0.04). CONCLUSIONS: In this animal model, the results indicate that pulmonary changes and fat embolization during intramedullary nailing occur to the same degree in reamed and in unreamed femurs.     

交锁髓内钉扩髓与不扩髓的比较

髓内钉技术的进步和交锁髓内钉概念的提出使得髓内钉应用范围越来越广泛,交锁髓内钉已成为治疗长管状骨骨干骨折的标准治疗方法.扩髓型交锁髓内钉可提高固定的稳定性和机械强度,不扩髓型可有效降低对骨内膜血供的干扰,两者孰优孰劣存在很大争议.该文就两种方法对股骨骨折愈合、胫骨骨折愈合、肺功能、发生感染机会的影响进行比较.     

Prospective randomized study of reamed versus unreamed femoral intramedullary nailing: an assessment of procedures

OBJECTIVE: To determine whether the procedure of unreamed femoral nailing is simpler, faster, and safer than reamed femoral intramedullary nailing. DESIGN: Prospective randomized. SETTING/PARTICIPANTS: One hundred femoral shaft fractures without significant concomitant injuries admitted to an academic Level 1 urban trauma center. INTERVENTION: Stabilization of the femoral shaft fracture using a reamed or unreamed technique. OUTCOME MEASUREMENTS: The surgical time, estimated blood loss, fluoroscopy time, and perioperative complications were prospectively recorded. RESULTS: One hundred patients with 100 femoral shaft fractures were correctly prospectively randomized to the study. Thirty-seven patients received reamed and sixty-three patients received unreamed nails. All nails were interlocked proximally and distally. The average surgical time for the reamed nail group was 138 minutes and for unreamed nail group was 108 minutes (p = 0.012). The estimated blood loss for the reamed nail group was 278 milliliters and for the unreamed nail group 186 milliliters (p = 0.034). Reamed intramedullary nailing required an average of 4.72 minutes, whereas unreamed nailing required 4.29 minutes of fluoroscopy time. Seven perioperative complications occurred in the reamed nail group and eighteen in the unreamed nail group. Two patients in the unreamed group required an early secondary procedure. Iatrogenic comminution of the fracture site occurred during three reamed and six unreamed intramedullary nailings. Reaming of the canal was required before the successful placement of three nails in the unreamed group because of canal/nail diameter mismatch. CONCLUSIONS: Unreamed femoral intramedullary nailing involves fewer steps and is significantly faster with less intraoperative blood loss than reamed intramedullary nailing. The unreamed technique, however, was associated with a higher incidence of perioperative complications, although the difference was not statistically significant (p = 0.5).     

Intramedullary pressure and bone marrow fat extravasation in reamed and unreamed femoral nailing.

This study was designed to investigate whether intramedullary pressure and embolization of bone marrow fat are different in unreamed compared with conventional reamed femoral nailing in vivo. In a baboon model, the femoral shaft was stabilized with interlocking nailing after a midshaft osteotomy. Intramedullary pressure was measured in the distal femoral shaft fragment at the supracondylar region. Extravasation of bone marrow fat was determined by the modified Gurd test (range: 0-5) with blood samples from the vena cava inferior. Data were monitored in eight unreamed and eight reamed intramedullary femoral nailing procedures. Intramedullary pressure increased in the unreamed group to 76 +/- 25 mm Hg (10.1 +/- 3.3 kPa) during insertion of 7-mm nails and in the reamed group to 879 +/- 44 mm Hg (117.2 +/- 5.9 kPa) during reaming of the medullary cavity. Insertion of 9-mm nails after the medullary cavity had been reamed to 10 mm produced an intramedullary pressure of 254 +/- 94 mm Hg (33.9 +/- 12.5 kPa) (p < 0.05). Fat extravasation in the unreamed group was recorded with a score of 2.9 +/- 0.4 for the Gurd test during nailing with 7-mm nails, whereas in the reamed group significantly more fat extravasation was noticed during the reaming procedures, with a score of 4.6 +/- 0.1. Liberation of fat during insertion of 9-mm nails after reaming was recorded with a score of 3.5 +/- 0.4. In both groups, a positive correlation of fat extravasation with the rise in intramedullary pressure was found (reamed group: r(s) = 0.868; unreamed group: r(s) = 0.698), resulting in significantly less liberation of bone marrow fat in the unreamed stabilized group than in the reamed control group (p < 0.05). The data indicate that fat embolization during nailing procedures after femoral osteotomy increases with increasing intramedullary pressure and occurs in a lesser degree in unreamed than in reamed intramedullary femoral shaft stabilization.     

Similar central hemodynamics but increased postoperative oxygen consumption in unreamed versus reamed intramedullary nailing of femoral fractures

BACKGROUND: Patients undergoing intramedullary nailing of long bone fractures have pathologically altered pulmonary vascular tone, right heart strain, and transient impairment of pulmonary gas exchange. The purpose of this study was to examine the acute differences in cardiopulmonary variables between reamed and unreamed nailing techniques in 18 (9 + 9) healthy patients with unilateral femoral shaft fractures. METHODS: Intramedullary nailing was performed under general anesthesia within 12 hours after the trauma. For blood sampling, recording, and measurements, the patients were cannulated with radial artery and pulmonary artery catheters. Changes in central hemodynamics and oxygenation were studied pre-, peri-, and postoperatively for 16 to 20 hours. RESULTS: Abnormally high pulmonary shunting (23 +/- 12% in the reamed and 27 +/- 11% in the unreamed group) was observed before the operation. The trends of all variables were very similar in both groups except for the last phase in which the mixed venous oxygen saturation tended to be lower (65 +/- 8 vs. 70 +/- 5%) and the oxygen consumption index was higher (186 +/- 21 vs. 151 +/- 20 mL/min/m) in the unreamed group than in the reamed group (p < 0.05). The timepoints most strenuous to the heart were at the end of operation and in the recovery room. CONCLUSIONS: The unreamed intramedullary nailing technique does not offer any advantage in cardiopulmonary variables over the reamed technique. In both groups, there was considerable deviation in over 10 cardiopulmonary variables from normal reference values during the study. We suggest the use of invasive monitoring on patients with a long bone fracture and poor preoperative oxygenation or a history of cardiopulmonary or cardiac disease.     

Cortical revascularization after reamed and unreamed intramedullary nailing in the rabbit femur: a microangiographic histometric analysis.

BACKGROUND: Intramedullary nailing leads to a reduction in cortical bone blood flow. The relative effect of reamed versus unreamed nailing on the degree of avascularity and on revascularization of the cortex remains controversial. We compared the effects of reamed versus unreamed intramedullary nailing on cortical revascularization and the time course for its recovery in the unfractured rabbit femur. METHODS: A total of 56 New Zealand white rabbits were used as experimental animals. Reamed nailings with Kirschner wire (diameter, 3 mm) were performed in the right femora (group R, n = 49), and unreamed nailings with Kirschner wire (diameter, 2 mm) were performed in the left femora (group UR, n = 49) of the same animals after a standard surgical procedure. Microangiography that used Indian ink was performed for each killed animal at one of seven postoperative time periods: 2 hours, 3 days, and 1, 2, 3, 4, and 5 weeks after surgery. The right femora and the left femora of seven rabbits were used as the postoperative day 0 controls of group R and those of group UR, respectively. We evaluated the vascularization ratio (VR) in cross-sections according to the following formula: VR = the number of enhanced vessels with Indian ink/total cortical vessels. Each cross-section was divided into an inner and outer half, which were in turn divided into quarters, so that the entire cross-sectional are is represented by eight regions. The VR was calculated for each regions and then comparison was made between group R and group UR at various time periods and areas. RESULTS: No statistically significant differences were observed in VR at any time period between group R and group UR in total cortical area and total periosteal side. However, on the total medullary side, the VR of group UR was significantly higher than that of group R at postoperative day 3 (p = 0.04). Statistically significant differences were observed between the VR on the periosteal side and that on the medullary side in both groups at all time periods aside from the 5-week period (p < 0.05). Revascularization of the cortex occurred 4 weeks after intramedullary nailing in both group R and group UR. CONCLUSION: The periosteal circulation was maintained better than the medullary circulation, irrespective of whether the canal was reamed or not. The present study failed to detect any statistically significant differences in cortical revascularization between reamed nailing and unreamed nailing. Thus, we concluded that reamed and unreamed nailing are not differentially advantageous in the unfractured rabbit femur, in terms of impairment of cortical blood supply.     

Effect of acute reamed versus unreamed intramedullary nailing on compartment pressure when treating closed tibial shaft fractures: a randomized prospective study

OBJECTIVE: To compare anterior and deep posterior compartment pressures during reamed and unreamed intramedullary nailing of displaced, closed tibial shaft fractures. DESIGN: Randomized prospective study. SETTING: University Hospital/Level I trauma center. PATIENTS: Forty-eight adults with forty-nine fractures treated with intramedullary nailing within three days of injury. INTERVENTION: After intraoperative placement of compartment pressure monitors, the tibia fractures were treated by either unreamed intramedullary nailing or reamed intramedullary nailing. A fracture table and skeletal traction were not used in any of these procedures. MAIN OUTCOME MEASUREMENTS: Compartment pressures and deltaP ([diastolic blood pressure] - [compartment pressure]) were measured immediately preoperatively, intraoperatively, and for twenty-four hours postoperatively. RESULTS: Compartment syndrome did not occur in any patient. Peak average pressures were obtained during reaming in the reamed group (30.0 millimeters of mercury anterior compartment, 34.7 millimeters of mercury deep posterior compartment) and during nail insertion in the unreamed group (33.9 millimeters of mercury anterior compartment, 35.2 millimeters of mercury deep posterior compartment). The average pressures quickly returned to less than thirty millimeters of mercury and remained there for the duration of the study. The deep posterior compartment pressures were lower in the reamed group than in the unreamed group at ten, twelve, fourteen, sixteen, eighteen, twenty, twenty-two, and twenty-four hours postoperatively (p < 0.05 at each of these times. A statistically significant difference between anterior compartment pressures could not be shown with the numbers available. The deltaP values were greater than thirty millimeters of mercury at all times after nail insertion in both the reamed and unreamed groups. CONCLUSION: These data support acute (within three days of injury) reamed intramedullary nailing of closed, displaced tibial shaft fractures without the use of a fracture table.     

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.     

Computational comparison of reamed versus unreamed intramedullary tibial nails.

We compared, via a computational model, the biomechanical performance of reamed versus unreamed intramedullary tibial nails to treat fractures in three different locations: proximal, mid-diaphyseal, and distal. Two finite element models were analyzed for the two nail types and the three kinds of fractures. Several biomechanical variables were determined: interfragmentary strains in the fracture site, von Mises stresses in nails and bolts, and strain distributions in the tibia and fibula. Although good mechanical stabilization was achieved in all the simulated fractures, the best results were obtained in the proximal fracture for the unreamed nail and in the mid-diaphyseal and distal fractures for the reamed nail. The interlocking bolts, in general, were subjected to higher stresses in the unreamed tibial nail than in the reamed one; thus the former stabilization technique is more likely to fail due to fatigue.     

The effect of muscle contusion on cortical bone and muscle perfusion following reamed,intramedullary nailing: a novel canine tibia fracture model

Background  

Management of tibial fractures associated with soft tissue injury remains controversial. Previous studies have assessed perfusion of the fractured tibia and surrounding soft tissues in the setting of a normal soft tissue envelope. The purpose of this study was to determine the effects of muscle contusion on blood flow to the tibial cortex and muscle during reamed, intramedullary nailing of a tibial fracture.     

Treatment of femoral and tibial diaphyseal nonunions using reamed intramedullary nailing without bone graft

INTRODUCTION: Intramedullary nailing has long been used successfully in the treatment of aseptic nonunions of the femur and tibia. However, recently the efficacy of reamed intramedullary nailing in the treatment of nonunions of the femur has been questioned by some publications reporting unfavourable results. The purpose of this study is to evaluate the treatment results of femoral and tibial diaphyseal nonunions with intramedullary nailing. PATIENTS AND METHODS: We retrospectively reviewed thirty-two patients with femoral or tibial diaphyseal nonunions who were treated with reamed intramedullary nailing between May 2002 and April 2006. Fixation status at the time of treatment were nail in twenty-eight patients (12 femurs, 16 tibiae), plate in three cases (2 femurs, 1 tibia), no implant in one femur. We used a dynamically locked, reamed intramedullary nailing. Only in bone defects greater than 50% of the cortical diameter and more than 2 cm in length was open bone grafting performed. RESULTS: Solid union was achieved in 93% (fourteen of fifteen) of femoral nonunions and 94% (sixteen of seventeen) of tibial nonunions. CONCLUSIONS: Our protocol with a dynamically locked, reamed nailing with the use of an oval hole and no open bone grafting for a defect less than 50% of the diameter and immediate weight bearing was successful in the treatment of femoral and tibial diaphyseal nonunions.     

Disruption of the arteria nutricia tibiae by reamed and unreamed intramedullary nailing. Study of the vascular architecture of the human tibial intramedullary cavity

AIM: By reason of the pseudarthrotic healing of fractures due to vascular complications after reamed and unreamed intramedullary nailing, the intraosseous course and branching of the tibial nutrient artery and its impairment by nailing procedures needs an actual analysis. METHOD: The nutrient vessel of 24 tibiae taken from fresh corpses were prepared by injection of Technovit and lead oxide. After this procedure the medullary cavities of 12 bones were opened by a frontal cut. These specimens were subjected to routine maceration. The other 12 tibiae were naed with the unreamed (6) and the reamed nailing (6) techniques. X-rays were also taken routinely. RESULTS: After penetration of the tibial compact bone the main trunk of the nutrient vessel runs through a perforated osseous tunnel (pars tecta arteriae nutriciae tibiae). At its end the vessel divides into a descending branch (obligate) and two ascending branches (facultative). The descending branch lies near to the centromedial region of the medullary cavity which is termed as the pars liberal arteriae nutriciae tibiae. All branches pass through supporting horizontal osseous lamellas. Due to this topography the reamed nailing technique destroyed the nutrient vessel completely in all specimens. In contrast to this observation the unreamed nailing destroyed the vessel completely only in 1 (16.7%) and partially in 3 (50%) bones; 2 (33.3%) specimens exhibited no destruction of the vessel. CONCLUSION: The unreamed as well as the reamed nailing technique can destroy the intramedullary course of the tibial nutrient artery. Fractures as well as displacement osteotomies or corticotomies are able to diminish the medullary blood supply seriously, if they are localised within the area of the tactic an of the tibial nutrient artery.     

扩髓与非扩髓型股骨髓内针术后免疫因子释放水平的研究

目的通过检测部分免疫介质的释放水平,探讨在应用髓内针治疗股骨干骨折术后早期对机体免疫功能的影响.方法选择股骨干闭合骨折患者59例,男55例,女4例,平均年龄32.1岁,按伤情分为轻伤组(n=43)和中度伤组(n=16),采取闭合复位带锁髓内针固定治疗.轻伤组扩髓23例、非扩髓23例,中度伤组扩髓7例、非扩髓6例,分别于术前24 h和术后1、24、48 h通过ELISA法检测患者血中TNF、IL-6、IL-8、IL-10的水平,通过蛋白分析测定CRP的水平;同时选取22例健康志愿者作为正常对照组.结果轻、中度创伤患者术后各炎症指标均较术前有所上升;IL-6、IL-8、IL-10在术后1 h呈上升趋势,术后24 h达到高峰,术后48 h 三种因子水平均开始下降,但尚未恢复正常;TNF、CRP术后1 h仍较术前有所下降,但在术后24 h均出现明显上升,到术后48 h再次回落;轻伤与中度伤组不同时段的免疫指标均与对照组有明显差异(P《0.05).不同伤情患者扩髓后各免疫指标均高于非扩髓者,但除中度伤组中IL-10在术后24 h有差异显著性意义(P=0.047)外,其它指标差异均无显著性意义(P》0.05). 2例患者术后出现SIRS,观察发现与非SIRS患者相比各项免疫指标并无显著差别.结论对于轻、中度创伤患者,髓内针会造成机体免疫介质再次大量释放,但经机体免疫调节后不会产生严重的影响;不同方式髓内针固定对术后早期机体的免疫系统的影响没有显著的差异,但以IL-10为代表的免疫抑制因子很可能随着伤情的加重在应用髓内针,尤其是扩髓型髓内针时出现短期内大量释放,从而加重机体的免疫抑制.