Observational prospective unblinded case-control study to evaluate the effect of the Gamma3® distal targeting system for long nails on radiation exposure and time for distal screw placement

PurposeTo determine if the DTS decreases radiation exposure (primary outcome measure), fluoroscopy time (secondary outcome measure), and time to distal screw placement (secondary outcome measure) compared to the freehand “perfect circles” method when used for locking of cephalomedullary nails in the treatment of femur fracturesMethodsFifty-eight patients with hip or femoral shaft fractures that were treated with a long cephalomedullary nail were enrolled in this study. Cohorts were determined based on the method of distal interlocking screw placement into either the “Perfect Circles” or “Distal Targeting” cohort. Time from cephalad screw placement to placement of final distal interlocking screw (seconds), radiation exposure (mGy), and fluoroscopy time (seconds) were compared between groups. Hospital quality measures were compared between cohorts.ResultsUse of the DTS resulted in 77% (4.3x) lower radiation exposure (p < 0.001), 64% (2.7x) lower fluoroscopy time (p < 0.001), and 60% (1.7x) lower intraoperative time from end of cephalad screw placement to end of distal interlocking screw placement (p < 0.001) compared to the freehand “perfect circles” method. There was no difference in 30-day or 90-day complication rates between cohorts.ConclusionThe Stryker Gamma3® Distal Targeting System is a safe, effective and efficient alternative to the freehand “perfect circles” method.     

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     

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.     

A simplified technique of distal femoral screw insertion for the Grosse-Kempf interlocking nail

Failure accurately to determine distal femoral screw hole position can sometimes prolong operating time for placing an interlocking Grosse-Kempf rod. The described technique allows the distal femoral screw holes to be localized accurately with minimal radiation exposure. This technique utilizes readily available instruments and is not technically demanding.     

A simple, rapid and economical method of distal interlocking nailing in upper and lower leg intramedullary nailing

Distal interlocking of intramedullary nails is associated with a relatively high radiation exposure. For the reduction of fluoroscopy time and surgeon's hands irradiation, many devices have been developed so far. In this paper, a simple free-hand-technique is presented. The mean fluoroscopy time in 30 femur and 10 tibia interlocking intramedullary nailing procedures was one minute. The technique avoid the central beam of the fluoroscope and does not require specific instruments. The technique is based on the axial placement of a 2 mm K-wire in the interlocking screw holes. A centrally perforated 4.5 mm drill is placed over the K-wire. Therefore in this technique a perfect centrally placement of the K-wire is not necessary. The drill is guided by the K-wire thereby avoiding complications such as drill failure or deviation of the drill direction.     

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.     

Treatment of femoral shaft fractures with a titanium intramedullary nail

Ninety-nine femoral shaft fractures were treated with locked intramedullary nails made from titanium alloy. One of the distal interlocking screws failed in six fractures (6%) and both screws failed in two fractures (2%). Delayed union was associated with all of the eight fractures that had locking screw failure. Young, heavier patients who had nails of small diameter had an increased risk of screw failure. Additional surgery was needed when both screws failed. The authors still use this nail, but currently prefer to ream the medullary canal more so that larger nails can be inserted. Decisions concerning weightbearing are made on an individual basis for each patient, and currently full weightbearing is delayed for young, active, and heavy patients. Two distal interlocking screws should be inserted for treatment of femoral shaft fracture when a Ti locked intramedullary nail is used.     

Stress analysis of the distal locking screws for femoral interlocking nailing.

In femoral locked nailing, the distal locking screws are vulnerable to mechanical failure. Biomechanical studies have shown that the stress on these screws is substantially affected by the fit of the nail in the medullary canal. In this study, a "closed form" mathematical model based on elastic beam-column theory was developed to investigate how the nail-cortical contact, which was simulated by a linear elastic foundation, affected the stress on the distal locking screws. Providing data for the model was a construct of a fractured femur with an intramedullary locked nail loaded by an eccentric vertical load. The stress on the locking screw was analyzed as a function of the distance from the fracture to the locking screw in the distal fragment under two situations: with and without nail-cortical contact in the distal fragment. With nail-cortical contact, the screw stress decreased as the length of nail-cortical contact and the distance between the distal locking screw and the fracture site increased, but this stress contrarily increased when the nail reached the femoral region at which the screw length increased. The screw stress was much higher without nail-cortical contact than with contact and continued to increase as the nail was inserted further. The mathematical model developed here can be a convenient means of rapid stress evaluation and parametric analysis for locked femoral nailing. It may be used to improve the design of interlocking nails and surgical technique.     

An intramedullary nail with multifunctional interlocking for all types of fracture in both femurs

Objective: A femoral compound interlocking intramedullary nail (FCIIN) was designed to treat all types of fractures between the trochanter and epicondyle of both femurs. It could substitute for femoral interlocking intramedullary nails (FIIN) at five points. Methods: According to the morphological characteristics of the femoral medullary canal, the nail is designed to accommodate a 1250 mm radius of radian and a 135° neck‐shaft angle. Three interlocking holes of 6.5 mm diameter are located at the proximal end of the FCIIN, making crossing of the screws possible. The hole is designed to be vertical (90°) or oblique (45° upper or lower). At the tip of the proximal interlocking screws, whose root diameter gradually increases from 3.5 mm to 6.5 mm, a self‐tapping cancellous screw is placed. There are two types of distal interlocking screws. One is a fine thread and the other a bolt screw. Two interlocking holes and a recess 4.5 mm in diameter are located at the distal end of the FCIIN. Under biomechanical destructive testing, the proximal interlocking screw device has satisfactory strength and reasonable structure. A total of 47 patients (31 males and 16 females, with an average age of 39.83 years) with femoral fractures were assessed in this study. Fourteen cases were diagnosed as intertrochanteric, 7 as subtrochanteric, 18 as femoral shaft, and 8 as supracondylar fractures. All 47 patients were treated with the FCIIN. Results: Of the 47 patients, anatomic reduction was achieved in 34, good reduction in 11, and forced line reduction in 2 cases. Reduction was excellent or good in 95.87% of the fractures. The removal time of the FCIIN was 12 to 21 months (average, 16.9 months). One patient with an intertrochanteric fracture who had a fixation failure combined with non‐union achieved healing with an external fixator at 18 months. Failure to insert the distal interlocking screws occurred in 5 patients but did not affect bone healing. Conclusion: The FCIIN is a useful device in the treatment of a variety of femoral fractures.     

Fluoroscopic guidance versus surgical navigation for distal locking of intramedullary implants. A prospective, controlled clinical study

A prospective controlled clinical study was performed to compare fluoroscopic guidance with fluoroscopy-based surgical navigation for distal locking of intramedullary implants. Forty-two patients with fractures of the lower extremity treated by intramedullary nailing were divided in two groups: distal locking either with fluoroscopic guidance (group I) or with surgical navigation (group II). The average fluoroscopic time to insert one interlocking screw with fluoroscopic guidance was 108 s compared with 7.3s in the navigation group. The average procedure time to insert one interlocking screw in group I was 13.7 min compared with 17.9 min in group II. The drill bit failed to pass through the interlocking hole in one patient from group II. There was no significant difference in the technical reliability between both groups. Fluoroscopic times to achieve equivalent precision are reduced with fluoroscopy-based surgical navigation compared with fluoroscopic guidance. Fluoroscopy-based surgical navigation is recommended for intraoperative guidance in situations where reduction of exposure to radiation is considered advantageous over the increase of procedure time.     

The effectiveness of the external distal aiming device in intramedullary fixation of tibial shaft fractures

Introduction

Intramedullary nailing has become a popular and effective procedure for the treatment of most fractures of the tibial diaphysis. However, distal interlocking screw placement under fluoroscopic control is responsible for the majority of the radiation exposure and a significant loss of surgical time in the entire nailing procedure. To limit fluoroscopy use, during distal interlocking screw placement, Orthofix^® has developed a distal targeting device which compensates for the inevitable deformation of the nail in the sagittal plane during its insertion. This prospective clinical study evaluates the efficacy of this distal targeting device for distal locking.

Materials and methods

One hundred and fifteen fresh tibial fractures in the same number of patients with a mean age of 37.5 years (17–85 years) were treated with operative stabilization using the Orthofix tibial nailing system.

Results

The mean duration of the operation was 38 min (20–55 min). A mean of four intra-operative plain X-rays (2–6 X-rays) were used in 103 cases to confirm guide wire placement, final nail insertion and accuracy of screws placement. The mean duration of the use of the image intensifier utilized in the remaining 12 fractures was 5 s (3–8 s). The distal targeting device failed in 12 (5.2%) distal locking screws.

Conclusion

This study demonstrates that distal locking can be performed easily and successfully with minimal exposure to radiation, once the surgeon develops a reasonable experience with the use of this distal targeting device.

     

股骨复合型带锁髓内钉的设计及临床应用

目的 阐述股骨复合型带锁髓内钉(femoral compound interloeking intramedullary nail,FCIIN)的设计原理,探讨其临床疗效.方法 根据股骨髓腔形态学特点,没计FCIIN的主钉弧度半径为1250 mm,近端斜形交锁角度(钉的颈干角)为135°.主钉近端有三个直径6.5 mm的锁钉孔,使锁钉可以横穿,也可以向左上或下、右上或下45°斜穿.主钉远端有两个直径4.5 mm的锁钉孔和一个相同直径的凹槽.近端锁钉尖部有长30～40 mm自攻松质骨螺纹,螺纹直径由3.5 mm逐渐增大至6.5 mm.远端锁钉有两种:一种是螺纹锁钉,另一种是螺栓锁钉.2000年1月至2004年12月,用FCIIN治疗股骨骨折患者47例,男31例,女16例;年龄18～74岁,平均39.83岁;转子间骨折14例,转子下骨折7例,股骨干骨折18例,髁上骨折8例.其中不扩髓顺行打钉30例.结果 所有患者均获得随访,随访时问21～36个月,平均25.9个月.骨愈合时间6～18个月,平均8.4个月.解剖复位34例,良好复位11例,力线复位2例,复位优良率95.74%.取钉时问12～21个月,平均16.9个月.1例转子间骨折固定失败并骨不愈合患者,采用辅助外固定支架治疗,18个月后骨折愈合.远端锁钉安装失败5例,未做任何处理骨折均愈合.结论 FCIIN 临床应用效果理想,可用于治疗各类股骨骨折.     

A biomechanical evaluation of the Gamma nail.

We examined the effect of the Gamma nail on strain distribution in the proximal femur, using ten cadaver femora instrumented with six unidirectional strain gauges along the medial and lateral cortices. The femora were loaded to 1800 N and strains were determined with or without distal interlocking screws before and after experimentally created two-part and four-part fractures. Motion of the sliding screw and the nail was also determined. Strain patterns and screw motion were compared with previously obtained values for a sliding hip screw device (SHS). The Gamma nail was shown to transmit decreasing load to the calcar with decreasing fracture stability, such that virtually no strain on the bone was seen in four-part fractures with the posteromedial fragment removed; increasing compression was noted, however, at the proximal lateral cortex. Conversely, the SHS showed increased calcar compression with decreasing fracture stability. The insertion of distal interlocking screws did not change the pattern of proximal femoral strain. The Gamma nail imparts non-physiological strains to the proximal femur, probably because of its inherent stiffness. These strains may alter bone remodelling and interfere with healing. Distal interlocking screws may not be necessary for stable intertrochanteric fractures.     

Clinical results of percutaneous pelvic surgery. Computer assisted surgery using ultrasound compared to standard fluoroscopy.

This study presents early results of clinical experience with the application of Computer Assisted Surgery (CAS) to percutaneous iliosacral screwing, with comparison to a historical series of patients treated using percutaneous fluoroscopy. Four patients were instrumented using a CAS system, with 10 screws being inserted. Thirty patients were treated by percutaneous fluoroscopic screwing, with 51 screws being inserted. The follow-up assessment included the following criteria; operative time, parameters of radiation exposure, neurological examination, screw placement evaluation on CT-scan, antalgic drug consumption, pain, Majeed grading, and loosening of implants. In the CAS group, the average radiation time was 0.35 min per patient and 0.14 min per screw. No trajectories outside the bone and no postoperative neurological deficits were found. In the fluoroscopic group, the average radiation time was 1.03 min per patient and 0.6 min per screw. Twelve screws had outside-bone trajectories, and iatrogenic neurological deficits were found in seven patients. The average operative time was 50 min in the CAS group and 35 min in the fluoroscopic group. The present CAS technique shows better placement of iliosacral screws, with no outside-bone trajectories and lower radiation exposure.     

Placement of the distal locking screws of the femoral intramedullary nail without radiation

An H-shaped device was invented to facilitate placement of the distal interlocking screws during closed femoral nailing. Eleven sound cadaveric femurs were experimentally nailed before the application of the device in 15 patients with a femoral shaft fracture. In all experimental cases the insertion of the distal screws proved to be easy. In 11 of 15 patients with a femoral fracture, distal locking was achieved using the H-device. These primary results should stimulate further clinical application of the device.     

国产带瞄准器交锁髓内钉远端锁钉准确性研究

目的 分析瞄准器引导下交锁髓内钉远端锁钉困难的原因,以提高远端锁钉成功率.方法 自2000年2月至2006年6月拆除有瞄准器的国产股骨交锁髓内钉56根,胫骨交锁髓内钉80根;均采取静力型固定,远近端各2枚锁钉.观察其远端髓内钉钻痕的情况,以分析瞄准器的远端锁钉准确性.结果 本组研究发现瞄准器第一次锁钉的成功率不高,股骨髓内钉瞄准器第一次锁钉的成功率为36%,胫骨髓内钉瞄准器第一次锁钉的成功率为65%.结论 交锁髓内钉远端锁钉困难的原因是多方面的.要提高远端锁钉一次成功率,必须重视瞄准器定位孔偏移问题.     

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.     

Cortical screw support in femoral neck fractures: A radiographic analysis of 87 fractures with a new mensuration technique

In 87 femoral neck fractures, operated on with 2 von Bahr screws and followed for up to 2 years, the positions of the fixating screws were determined with a new mensuration technique which compensates for the variations in hip rotation in routine radiographs. The union rate of the fractures was related to the position of the screws. A posterior placement of the proximal screw and an inferior placement of the distal screw in both the femoral head and neck improved the outcome substantially.     

Distal screw targeting of interlocking nails

Successful placement of the distal interlocking screws into the Grosse-Kempf nail is a demanding procedure due in part to deformation of the nail during insertion and to inaccuracy of the targeting device supplied with the system. The authors suggest an alternative approach. After placement of the nail in a tibia or femur, a Kirschner wire (K-wire) is directed through the distal transfixation hole under fluoroscopic control. A second Grosse-Kempf nail is placed alongside the limb with the K-wire passing through the corresponding distal hole. The more proximal hole on the nail serves as a targeting guide for a more proximal wire. Once correct placement of the wires is confirmed roentgenographically, the near cortex is opened with a cannulated drill passed over the wires. The wires are removed, the opposite cortices are drilled, and the screws are placed. In 25 consecutive distally locked nailings (eight tibiae and 17 femora), the technique was easily mastered, decreasing the roentgenogram exposure when compared to freehand techniques.