Nail over nail technique for distal locking of femoral intramedullary nails

The free hand technique remains the most popular method for distal locking; however, radiation exposure is a major concern. In an endeavour to overcome this concern, distal locking with the nail over nail technique is evaluated. Seventy patients with femoral diaphyseal fractures treated by intramedullary nailing were divided in two groups for distal locking: either using the free hand technique (group I) or with the nail over nail technique (group II). The average number of images taken to achieve nail insertion without locking, for distal locking, and for the complete procedure in group I was 25.8, 24.2, and 50.08, respectively, compared with 24.8, 4.1, and 28.9, respectively, in group II (statistically extremely significant decrease in radiation). The nail over nail technique appears to be a reliable solution for decreasing radiation exposure during closed femoral intramedullary nailing. However, over-reaming of 1.5 mm is the key to the success of the technique.     

Exposure of surgeons-in-training to radiation during intramedullary fixation of femoral shaft fractures.

Owing to the continuous turnover of registrars and radiographers, most of the trauma-related orthopaedic surgery in this academic hospital is done by inexperienced surgeons-in-training and the fluoroscopy by junior radiographers. This could result in excessive radiation doses. Calibrated lithium fluoride thermoluminescent chips were secured to various parts of the primary surgeon's body to quantify the radiation dose received during the insertion of an intramedullary nail. Closed intramedullary fixation of 15 fractures of the femur was done with interlocking as necessary. The total average exposure time was 14 minutes 45 seconds per procedure. Distal locking took up 31% of this time. The mean radiation dose to the surgeon's eyes and thyroid was 0.13 mGy and to the dominant hand 2.10 mGy. This would allow the performance of about 350 such procedures per year before the maximum permissible dose level was reached. Recommendations to decrease irradiation dosage are made.     

A mechanical distal aiming device for distal locking in femoral nails.

Although the free hand technique remains the most popular method for distal interlocking screw insertion, proximally mounted radiation independent devices that compensate for implant deformation recently have been developed for the femur. However, the benefits of such systems have not been determined. This study prospectively compared the duration of the nailing procedure, the length of radiation time, and the accuracy of interlocking screw placement when using a radiation independent distal aiming system with those using the free hand technique. In 20 paired intact anatomic specimen femurs, one surgeon experienced only in the free hand technique performed statically locked intramedullary nailing using the two methods. For the aiming system and free hand technique, respectively, the total operation time was 19.1 +/- 8.4 minutes versus 20.9 +/- 11.3 minutes, the distal locking time was 6.6 +/- 2.4 minutes versus 4.8 +/- 1.5 minutes, the total fluoroscopy time was 23 +/- 17 seconds versus 69 +/- 34 seconds, and the distal locking fluoroscopy time was 0 versus 37 +/- 15.5 seconds. There were no failures in either group. Drill nail contact and distal screw damage were greater with the free hand technique. This study suggests that the main advantages of the aiming arm compared with the free hand technique include the elimination of radiation during distal interlocking and more precise screw placement with decreased insertion related hardware damage.     

Mechanische Einflussfaktoren der Marknagelung auf die femorale Antetorsion

INTRODUCTION: Antegrade or retrograde intramedullary nailing is a common and well established procedure for the treatment of femoral shaft fractures. One drawback of this technique is the high incidence of clinically relevant malalignment. Despite intra-operative and radiological improvements this problem has not yet been solved efficiently. The aim of this study was the evaluation of the mechanical influence on the antetorsion angle of intramedullary nails during and after interlocking in femoral shaft fractures. MATERIAL AND METHODS: A mechanical instrument was developed allowing a defined torque to be administered to the distal femur fragment. As an optical measurement system for the assessment of the antetorsion angle, a navigation system was applied. Initially the influence of the interlocking mechanism of the nail on the antetorsion deviation was investigated. The distal interlocking hole was fixed free handed or by using a navigation system. The multidirectional movement of the distal femur fragment was documented. Furthermore, the influence of the rotational stability on the antetorsion angle after mechanical stress of 4 NM was investigated by measuring the remaining rotational capacity of the distal femur fragment. RESULTS: The average remaining rotational capacity of the distal femur fragment was 5.8 degrees after locking the nail by hand. The navigated locking resulted in a deviation of only 2 degrees , a significant difference compared to the free-hand procedure. The rotational stability under stress showed an average of 15.4 degrees deviation of the distal fragment. Even after complete interlocking of the intramedullary nail a 14.2 degrees rotational deviation was observed. DISCUSSION: It could be shown that mechanical stability as well as the interlocking itself of femoral nails have a relevant impact on the antetorsional angle of the femur. Potential sources of error of the femoral antetorsion angle can be caused by the interlocking process as well as by forced rotation of the femur after interlocking. Clinical studies are needed to improve our findings, while the observed effects might have an essential influence on the incidence of femoral malalignment after osteosynthesis by intramedullary nailing of the femur.     

Surgical navigation based on fluoroscopy--clinical application for computer-assisted distal locking of intramedullary implants.

OBJECTIVE: Fluoroscopy is used to guide surgical instruments during orthopedic procedures. Radiation exposure and lack of spatial information are drawbacks of this method. Improvements are expected when fluoroscopy-based surgical navigation is used for intraoperative guidance, e.g., in computer-assisted distal locking of intramedullary implants. PATIENTS AND METHODS : The method was applied to 42 interlocking procedures during implantation of the short proximal femoral nail in 27 patients with pertrochanteric femoral fractures. Precision of interlocking, exposure time, operating time, and number of personnel required for computer-assisted distal locking were recorded. RESULTS: One misplaced interlocking screw was observed (2.3%), and contact between the drill bit and the nail during drilling was noticed in 8 cases (19%). The average exposure time was 16 seconds (range 4-42 seconds), and the procedure took an average of 43 min (range 20-70 min). The number of persons required for computer-assisted distal locking was reduced from three to one within the course of the study. CONCLUSIONS: Fluoroscopy-based surgical navigation provided precise intraoperative guidance for computer-assisted distal locking with minimal use of fluoroscopy. The complex system and related procedure times may be drawbacks in this application. Clinical studies are underway to define implants and surgical procedures where intraoperative guidance by fluoroscopy-based surgical navigation is beneficial for the patient and/or surgeon.     

Deformation of femoral nails with intramedullary insertion

Current methods of distal interlocking of intramedullary femoral nails are dependent on image intensification. However, radiation exposure to the patient, the operating room staff, and the surgeon remains a concern. Proximally mounted, radiation-free aiming systems for distal interlocking of femoral nails have reportedly failed because of nail deformation with insertion. To better understand this deformation, a threedimensional magnetic motion tracking system was used to determine the position of the distal interlocking hole following nail insertion. The amount and direction of deformation of commercially available smalldiameter implants (unslotted 9-mm nails inserted without reaming) and large-diameter implants (slotted 13-mm nails inserted with reaming) from a single manufacturer were analyzed. Measurements of deformation (three translations and three angles), based on the center of the distal transverse locking hole, were performed on 10 paired intact human cadaveric femora before and after insertion. The technique produced the following results for the small and large-diameter nails, respectively: lateral translations of 18.1 ± 10.0 mm (mean ± SD, range: 47.8 mm) and 21.5 ± 7.9 mm (range: 26.4 mm), dorsal translations of -3.1 ± 4.3 mm (range: 15.2 mm) and 0.4 ± 9.8 mm (range: 30.1 mm), and rotation about the longitudinal axes of ?0.1 ± 0.2° (range: 0.7°) and 10.0 ±3.1° (range: 7.8°). This technique is useful for measuring insertion-related femoral nail deformation. The data for the nails tested suggest that a simple aiming arm, mounted on the proximal end of the femoral nail alone, will not sufficiently provide accurate distal aiming.     

A new mechanical aiming device for the placement of distal interlocking screws in femoral nails

Although the free-hand technique remains the most popular method for distal interlocking screw insertion, a proximally mounted “radiation-independent” device which compensates for implant deformation has been developed. In 15 intact human cadaveric femora the same surgeon performed statically locked intramedullary nailing using the distal aiming system. Operation time, distal screw insertion, total radiation time and accuracy of the interlocking screw placement were measured using a radiation-independent distal aiming system. The average total operation time was 21.2 ± 8.6 min, and the average distal locking time (2 screws) was 7.1 ± 2.4 min. The total operation time and the distal locking time declined over the first 10 cases. These times did not significantly improve in the subsequent 5 procedures. The average total fluoroscopy time was 28.1 ± 16.6 s. None of the screw placements using the distal aiming device required the use of fluoroscopy. Drill-nail contact was absent in 5 drillings, mild in 9 drillings, moderate in 16 drillings, and severe in none. Measurement of screw damage showed in 55 of 60 measurements wear of less than 15 μm. There were no failures or major complications. A minor complication related to distal locking was observed in one specimen. This study suggests that distal interlocking screws can be placed successfully using a radiation-independent aiming arm-based system, which accounts for nail deformations. The distal aiming device (DAD) can be learned easily. The main advantages of the aiming arm include the elimination of radiation during distal interlocking and precise screw placement with little insertion-related hardware damage. Received: 23 Juni 1997     

股骨远近段骨折髓内钉置入失误分析及对策

目的根据股骨远近段的解剖特点,分析股骨交锁髓内钉置入操作失误的原因及处理对策,以提高交锁髓内钉置入的成功率。方法自2002年1月～2006年3月,笔者观察210例股骨远近段骨折交锁髓内钉的置入过程,并对股骨远近端松质骨髓腔高度进行测量。结果132例操作顺利,78例出现交锁髓内钉置入失误,采用自制髓腔轴线控制棒校正开口处骨道轴线,取得满意效果。结论开口处骨道轴线与髓腔轴线同轴是交锁髓内钉置入的关键,出现失误时不能使用暴力,需校正开口轴线,重新置入髓内钉。     

Interlocking intramedullary nails. An improved method of screw placement combining image intensification and laser light.

Insertion of distal interlocking screws in femoral nails can be technically demanding and may entail substantial exposure. A method of insertion of femoral interlocking screws that uses a laser guiding system in addition to the standard image intensifier was used in an attempt to improve the accuracy of distal screw placement and to limit radiation exposure. Using this technique, 97% of the distal femoral drill holes attempted were successfully made with the first pass of a drill. Little or no resistance to the drill was met from contacting the femoral nail. Average fluoroscopy time was 0.4 minute. Laser-assisted screw placement requires relatively inexpensive modifications of existing equipment and is easy to master. Compared with the more commonly used freehand method, laser-assisted screw placement appears to offer a reduction in the amount of time and radiation exposure required to insert distal interlocking femoral screws.     

Self-guiding interlocking intramedullary nail

A critical step in closed interlocking intramedullary nailing is the insertion of the proximal and distal screws under fluoroscopic control. An intramedullary nailing system is described that does not require the use of direct fluoroscopic control for distal screw insertion. With the SG interlocking intramedullary nail, the location and fixation of the distal screw is achieved by keying in on a transversely placed guide pin, with imaging required only to confirm the alignment and final placement of the instrumentation.     

Simple method for retrieval of distal segment of the broken interlocking intramedullary nail.

A simple technique for removal of the distal fragment of the broken intramedullary interlocking nail is described. It was successfully used in three patients with a broken nail due to nonunion. The technique requires only cerclage wire, which is available in any operating room, avoiding the difficulties obtaining the custom made hook and of excessive exposure to radiation.     

Comminuted femoral-shaft fractures: treatment by roller traction, cerclage wires and an intramedullary nail, or an interlocking intramedullary nail

In a retrospective study, we attempted to assess progress in the treatment of comminuted fractures of the femoral shaft at Parkland Memorial Hospital from 1978 to 1983. Seventy-nine comminuted femoral-shaft fractures were available for follow-up: thirty-two treated by roller traction, twenty-three treated by cerclage wires and an intramedullary nail, and twenty-four treated by an interlocking intramedullary nail. Using the classification of Winquist and Hansen, Grade-III and IV comminuted fractures accounted for 69 per cent of those treated by roller traction, 68 per cent of those treated by nailing and cerclage wires, and 96 per cent of those treated by an interlocking nail. The frequency of multiple injuries was 38 per cent in the patients treated by roller traction, 39 per cent in those treated by nailing and cerclage wires, and 58 per cent in those treated by an interlocking nail. The average hospitalization times were thirty-one days for roller traction, sixteen days for cerclage wires and an intramedullary nail, and 19.5 days for an interlocking nail. The average length of follow-up was 132 weeks after roller traction, 115 weeks after cerclage wiring and an intramedullary nail, and sixty weeks after insertion of an interlocking nail. All fractures were followed until after union; the average times to union were 18.4 weeks after roller traction, thirty-four weeks after open reduction and intramedullary nailing with cerclage wires, and 13.8 weeks after insertion of an interlocking nail. For the purposes of this study, treatment was assumed to have failed if a change in treatment was necessary, an unplanned reoperation was performed, femoral shortening exceeded 2.5 centimeters, angulation was more than 15 degrees, non-union or a deep infection developed, motion of the knee was less than 70 degrees of flexion, or a refracture occurred. By these criteria, the frequency of failure after roller traction was 66 per cent (secondary to malalignment and shortening); after insertion of an intramedullary nail with cerclage wires, 39 per cent (secondary to unplanned surgery, non-union, shortening, and infection); and after use of an interlocking nail, 4 per cent (secondary to shortening). Currently, at our institution, an interlocking intramedullary nail is the treatment of choice for comminuted femoral-shaft fractures because it encourages early union with maintenance of length and alignment and the results are predictable.     

Intramedullary nailing of femoral shaft fractures. Part I: Decision-making errors with interlocking fixation

Dynamic intramedullary fixation depends on the configuration of the fracture for postoperative stability. Unanticipated loss of reduction of the fracture after dynamic intramedullary nailing of the femur may result from errors in surgical decision-making, specifically the failure to insert both proximal and distal interlocking screws. Of 133 dynamic femoral intramedullary nailings that were performed after interlocking techniques became routinely available, fourteen (10.5 per cent) were complicated by loss of postoperative fixation and reduction. Thirteen of the fourteen femora shortened an average of 2.0 centimeters; the remaining femur shortened slightly, with clinical loss of rotational stability. Eight of fourteen patients elected some form of surgical revision, most commonly closed osteoclasis with restoration of femoral length, followed by the insertion of a statically locked nail. Errors in surgical judgment were attributed to inadequate preoperative analysis of the pattern of the fracture; undetected intraoperative comminution during reaming or insertion of the nail, or both; or postoperative failure to recognize an increase in comminution and instability of the fracture. We suggest using high-quality preoperative radiographs to detect non-displaced comminution of the major fracture fragments. Any increase in comminution of the fracture that occurs with reaming of the canal or insertion of the nail is an indication for static interlocking fixation. Radiographs that are made immediately postoperatively should be analyzed while the patient is under anesthesia, and any previously undetected instability of the fracture should be treated by static interlocking fixation. Dynamic intramedullary stabilization of the femur should be reserved for transverse or short oblique fractures at the femoral isthmus that have type-I or type-II comminution.     

小切口复位逆行交锁髓内钉治疗股骨远端骨折

目的探讨小切口复位逆行交锁髓内钉治疗股骨远端骨折的临床效果。方法2003年7月至2006年12月，对24例股骨远端骨折患者的手术治疗进行回顾性分析。按股骨远端骨折AO／ASIF分型，A型16例～型8例，治疗采用小切口复位逆行交锁髓内钉内固定。结果本组病例随访时间6～24个月（平均17．4个月），平均愈合时间为4．6个月，无术后感染，1例远端锁钉断裂，经制动后愈合。按Neer等膝关节评分标准进行评价，优15例，良6例，优良率87．5％。结论小切口复位逆行交锁髓内钉治疗股骨远端骨折，手术操作简单，固定可靠，对软组织破坏少，骨折愈合率明显提高，用于治疗股骨远端复杂骨折手术效果好。     

Die Röntgenstrahlenbelastung der Hände der Operateur bei Marknagelosteosynthesen

During 41 procedures of intramedullary nailing of femoral and tibial fractures the primary surgeon and the first assistent wore ring dosimeters on their dominant index fingers. While the average fluoroscopy time per procedure was 4,6 min the average dose of radiation to the dominant hand of the primary surgeon was 1,27 mSv and 1,19 mSv to the first assistent. The dose limit for the extremities is 500 mSv per year recommended by the International Commission on Radiological Protection. Extrapolation of the average dose of the primary surgeon and first assistent per procedure of 1,23 mSv leads to the result, that the recommended dose limit of 500 mSv would only be exceeded if more than 407 intramedullary nailing procedures are carried out per year. The duration of fluoroscopy-time correlated with the radiation dose of the hands of the surgeons, though it was determined by phantom measurements that the majority of radiation exposure occurred during brief exposures of the hands in the direct X-ray beam on the X-ray tube near side of the patient.     

Shielding of the patient's gonads during intramedullary interlocking femoral nailing

Levels of exposure to radiation were recorded at sixty sites in fifteen patients during intramedullary interlocking femoral nailing. Radiation film dosimeters were placed at four gonadal sites on each subject. A standard male-gonad cup or a pelvic drape of 0.5-millimeter-thick lead-equivalent was put in place to shield the gonads. A second set of four dosimeters was placed external to the shield to approximate unprotected exposure. The total duration of the fluoroscopy averaged five minutes (range, thirty seconds to fourteen minutes). The total exposure to radiation external to the shield was 35 +/- 34 millirems at the male gonadal sites and 17 +/- 11 millirems at the female gonadal sites. With use of the gonadal shield, exposure to radiation was not measurable in thirteen of the fifteen patients. The differences between the exposures of the shielded and unshielded sites to radiation were statistically significant (p less than 0.001). The highest level of gonadal exposure was found with the treatment of proximal femoral fractures and with the use of statically locked nails. Regardless of the conditions, and for all types of fractures and locations, our results demonstrated that gonadal shielding is justified.     

关节镜下逆行带锁髓内钉治疗股骨远端A型骨折疗效探讨

目的: 比较两种内固定治疗股骨远端A型骨折的不同疗效。方法: 1999年 6月~2003年 12月本院共收治股骨远端A型骨折患者 46例, 采用关节镜下逆行带锁髓内钉 (GSH钉 ) 内固定 28例, 采用动力髁螺钉 (DCS)内固定 18例。结果: 术后随访 6~54个月, 平均 18个月。两组在手术时间、术中出血、住院时间、骨折完全愈合时间、关节功能恢复时间有显著性差异 (P<0 .01 )。膝关节功能按Kolment评定标准, 其中髓内钉组优良率 89 .2%;动力髁组优良率 72. 2%。结论: 关节镜引导股骨逆行带锁髓内钉手术时间短、出血少, 最大程度地保留了关节部位解剖与功能的完整性, 不仅对膝关节损伤小, 并可同时发现及处理膝关节内的损伤或病变, 治疗结果优于动力髁螺钉, 值得提倡。     

Reducing radiation exposure in intra-medullary nailing procedures: Intra-medullary endo-transilluminating (iMET)

The purpose of the study was to reduce the level of radiation exposure during intra-medullary nailing procedures. A visible light source was inserted into the medullary bone cavity in order to detect the distal interlocking screw holes. The light penetrates out of the bone surface, revealing the position of the screw hole, and this allows the subsequent drilling and placing of the interlocking screw to be free of fluoroscopy. Among the 19 consecutive tibia-fracture patients recruited for this study, no repetition of the drilling procedure or insertion of a transverse interlocking screw was needed. The average time to finish the insertion of one distal interlocking screw was 4.1 ± 1.8 min. It was extrapolated that 13–41% of previous radiation exposure levels could be saved. The non-fluoroscopic approach thus decreases the health hazards that the patients are experiencing as well as those of the surgical team who need to perform such intra-medullary nailing operations on a routine basis.     

Die Effektivität des Schilddrüsenbleischutzes zur Reduzierung der Röntgenstrahlenbelastung bei unfallchirurgischen Eingriffen am Unterschenkel

The occupational radiation exposure of trauma surgeons has increased over the last few years as a result of biologic orthopaedic procedures like intramedullary nailing as closed reduction and insertion of distal interlocking screws need fluoroscopic control. In order to assess the surface doses of the primary surgeon with and without lead shield of the thyroid we performed in vitro measurements during operative procedures of the lower extremities simulating different intraoperative situations under fluoroscopic control. The average registered ionizing dosage without thyroid shield was 70 times higher compared to the measurements with thyroid protection. In a previous study we found average fluoroscopy times during intramedullary nailing of tibia and femur of 4.6 min per procedure. Extrapolation of this value leads to the result, that even when 1000 intramedullary nailings were carried out without wearing lead protection, 13% of the dose limit recommended by the International Commission on Radiological Protection for the thyroid of 300 mSv per year would not be exceeded, whereas by wearing the lead protection only 0.2% of the recommended dose would be reached.     

Mechanical comparison of standard interlocking,clawed, and expandable wedge locked nail fixations: An experimental and numerical study

IntroductionIntramedullary nailing has been used as a standard in the treatment of the long bone fractures with its clinical and mechanical advantages. However, using distal locking screws has been associated with longer operative times, higher radiation exposure rates, and complications like breakages of distal screw or nail at the screw hole level. Therefore, attempts to eliminate distal locking screws has been always present for intramedullary nail fixation. With a similar purpose, the present study has been carried out to compare mechanical behaviors of intramedullary nail fixations with different distal locking elements.Materials and MethodsIn this study, mechanical behaviors of standard interlocking and clawed nail fixations were compared experimentally in the first part. Six fourth generation Sawbones femurs, which have a simulated subtrochanteric fracture, were divided equally and were fixed with standard interlocking and clawed nails. During axial compression tests, experimental strain measurements were taken from all fixations. After validation of numerical models with using experimental strains and stiffnesses, mechanical behaviors of standard interlocking, clawed, and wedge locked nail fixations were compared numerically under axial compression loads. In numerical comparison, the stress-strain distributions were evaluated.ResultsExperimental results showed that although that there was no significant difference in stiffnesses, standard nail fixation bore two times higher loads than clawed nail fixations. Under loading, decrease in the distance between fracture surfaces was approximately seven times higher in the clawed nail fixation when compared to standard nail fixations. Numerical results showed that wedge locked nail fixation provided equivalent mechanical behavior to standard interlocking nail.DiscussionIn experiments of clawed nail fixation, the high decrease in the distance between fracture surfaces was evidence of the slippage of nail in the medullary canal. For a safe fixation, claws should be deployed when they are completely in contact with the cortical bone, they should be stuck into the bone in a fair amount, and the deployment in the distal third of the femur should be avoided. According to experimentally validated numerical analyses, wedge locked nail fixation may be an alternative for standard interlocking nail fixation if experimental studies support the present results.