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.     

Fluoroscopy-Based Surgical Navigation versus Fluoroscopic Guidance to Control Guide Wire Insertion for Osteosynthesis of Femoral Neck Fractures

AbstractBackground and Purpose: Long fluoroscopic times and related radiation exposure are a universal concern when C-arm fluoroscopy is used to guide percutaneous procedures. Fluoroscopy-based surgical navigation has been proposed as an alternative guidance method requiring limited fluoroscopic times to achieve precision. The purpose of this experimental study was to compare fluoroscopy-based surgical navigation with C-arm fluoroscopy for guidance with respect to the precision achieved, the fluoroscopic time, and the resources needed.Material and Methods: 114 guide wires were placed in 38 synthetic bone models using either C-arm fluoroscopy (group A) or fluoroscopy-based surgical navigation (group B) for guidance. Precision of guide wire placement was rated on the basis of an individual CT scan on all fracture models of both groups. The fluoroscopic time, the procedure time, and the number of attempts required to place the guide wires were documented as well.Results: An average fluoroscopic time of 26 s was needed with C-arm fluoroscopy to place three guide wires compared with an average fluoroscopic time of 2 s that was needed when fluoroscopy-based surgical navigation was used for guidance (p < 0.0001). Precision of guide wire placement and procedure times required to place the guide wires did not differ significantly between both groups. The number of attempts required for correct placement was found significantly reduced with fluoroscopy-based surgical navigation when compared with fluoroscopic guidance (p = 0.04).Conclusion: Fluoroscopic times to achieve precision are reduced with fluoroscopy-based surgical navigation compared with C-arm fluoroscopy. The impact of this new technique on minimally invasive, percutaneous procedures has to be evaluated in controlled prospective clinical studies.     

医用机器人及计算机辅助导航手术系统在胫骨髓内钉手术中的设计与应用

目的以胫骨骨折闭合复位、带锁髓内钉手术为研究对象，开发医用机器人及计算机辅助导航手术系统，总结该系统的临床应用经验，优化系统的结构设计，评价系统的临床应用效果。方法应用机器人双目视觉空间定位技术，进行医用机器人的模块化、小型化、实用化结构设计，开发医用机器人及计算机辅助导航手术系统；对胫骨骨折进行机器人辅助复位、计算机辅助导航定位髓内钉置入；临床应用于30例闭合胫、腓骨骨折（胫骨中1／3骨折8例、胫骨中下1／3骨折17例、胫骨远1／3骨折5例；其中斜螺旋骨折16例，蝶形骨折5例，粉碎、多段骨折9例）。受伤至手术的平均时间为36h。记录总手术时间、系统连接建立时间、骨折闭合复位所需X线透视时间（C型臂透视次数）、每个远端锁定螺钉置入所需要的透视时间（C型臂透视次数）。髓内钉型号大小8／310～11／330。结果30例手术均按照机器人及计算机导航系统的预定程序，规划完成，但关键的操作（髓内钉入点置入、远端锁钉锁孔）是在机械臂精确定位的辅助下，由术者亲自完成。总手术时间平均为77min（46～110min）；系统连接建立时间5min（3～7min）；骨折闭合复位所需X线透视时间10．1s（7．0～18．0s），C型臂透视次数12次（9～21次）；每个远端锁定螺钉置入所需的透视时间2．9s（2．2～6．9s），C型臂透视次数7次（5～16次），并且所有远端锁孔均一次锁定成功。结论医用机器人及计算机辅助导航手术系统设计合理，系统的基本功能可满足胫骨带锁髓内钉手术中骨折闭合复位、锁钉准确置人、患肢牢靠固定的要求；系统结构安装简便、易于掌握，人机接口方便、安全，对于未来在创伤骨科发展智能化、微创化、数字化手术具有重要意义。     

磁力导航交锁髓内钉治疗胫骨干骨折

目的评价磁力导航交锁髓内钉治疗胫骨干骨折的疗效,并与普通交锁髓内钉疗效进行比较。方法将60例胫骨干骨折患者随机分为两组：A组30例,使用磁力导航交锁髓内钉治疗;B组30例,使用普通交锁髓内钉治疗。记录两组远端2枚锁钉锁定成功时间,一次性锁定成功率。对两组分别就其平均手术时间、骨折平均愈合时间、HSSkneeratingscore法评定功能的各项指标进行比较分析。结果远端2枚锁钉锁定成功时间：A组（7．9±3．7）min,B组（18．1±4．8）rain,两组差异有统计学意义（t=15．78,P〈0．05）;一次性锁定成功率：A组97％,B组78％．两组差异有统计学意义（t=10．01,P〈0．05）;A组骨折延迟愈合1例,骨折短缩移位1例;B组断钉1例,伤口浅表感染l例,骨折延迟愈合3例。两组手术时间、术中出血量、并发症及HSSkneeratingscore法评定功能恢复优良率比较,差异有统计学意义（t=17．32,14．75,7．46,P〈0．05）。结论磁力导航交锁髓内钉治疗胫骨干骨折疗效满意,与普通交锁髓内钉比较有定位准确、手术时间短、创伤小的优势。     

A cadaveric study comparing standard fluoroscopy with fluoroscopy-based computer navigation for screw fixation of the odontoid

Although direct osteosynthesis of certain types of odontoid fractures may increase union and decrease the need for prolonged immobilization, screw fixation remains a technically demanding procedure. This study compares radiation exposure, surgical time, and accuracy of hardware placement using standard fluoroscopy versus computer-assisted fluoroscopy-based navigation ("virtual fluoroscopy") to assist with the placement of odontoid screws. Twenty-two cadavers were divided into two groups and underwent placement of a single odontoid screw using either standard fluoroscopic or virtual fluoroscopic guidance. Following screw placement, dissection of the C1-C2 segments was performed to assess accuracy. A significant reduction in fluoroscopy time was noted with the computer-based fluoroscopy technique, whereas the surgical time was not found to differ significantly between the techniques. No critical breaches (those risking neurovascular injury) were noted in either group, and the rate of noncritical breaches did not differ. The authors conclude that fluoroscopy-based virtual navigation appears to have a safety profile similar to standard fluoroscopy while allowing a reduction in radiation exposure.     

Minimally invasive fluoro-navigation screw fixation for the treatment of pelvic ring injuries

Intensive use of intraoperative fluoroscopy is mandatory to achieve good accuracy and avoid neural or vascular injury and may prolong surgical time and increase exposure-related hazards. New methods of percutaneous treatment in conjunction with innovative fluoroscopy-based computerized navigation have evolved in an attempt to overcome the existing difficulties. This report described our experience in applying fluoroscopic surgical navigation technique and evaluated its clinical application to pelvic ring injuries, including its feasibility, merits and limitations. Twenty-two patients with pelvic ring injuries were treated with percutaneous pubic ramus screw and sacroiliac screw techniques under the guidance of a fluoroscopy-based navigation system. A total of forty-four screws were inserted, including twenty-seven pubic ramus screws and seventeen sacroiliac screws. The average operation time and the average fluoroscopy time per screw were 23.6 minutes and 22.2 seconds respectively. Compared to the final position of the screw, the average deviated distance of wire tip was 2.8 mm and the average trajectory difference was 2.6°. A ventral cortex perforation of the sacrum was found in one sacroiliac screw without any clinical symptoms. No superficial or deep infection occurred. No patient sustained recognized neurologic, vascular, or urologic injury as a result of percutaneous screw fixation of pubic ramus fractures, sacroiliac disruptions, or sacral fractures. Our results showed that fluoroscopy-based navigation technique for the pelvic ring injuries could become a safe and effective alterative method for the treatment of pelvic ring injuries in some selected patients.     

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     

Robotic distal locking of intramedullary nailing: Technical description and cadaveric testing

Interlocked intramedullary nailing is the treatment of choice for femoral shaft fractures. However, distal locking is a technically challenging part of the procedure that can result in distal femoral malrotation and high radiation exposure. We have tested a robotic procedure for robotic distal locking based on the computation of a drilling trajectory on two calibrated fluoroscopic images. Twenty distal holes were attempted in ten cadaveric femur specimens. Successful screw hole drilling was achieved at the first attempt in each of the ten specimens (20 drill holes in total). No failures were recorded. The average total number of images needed was 6.5 +/− 3.6. The average computation time was 16.5+/− 16.0 seconds. Robotic distal locking was feasible in this test and can be integrated into a fully robotic intramedullary nailing procedure.     

Computer-assisted auto-frame navigation system for distal locking of tibial intramedullary nails： a preliminary report on clinical application

Objective: To evaluate the clinical feasibility and effect of the computer-assisted auto-frame navigation system for distal locking of tibial intramedullary nails. Methods: The hardware components of the system included a PC computer with a monitor, auto mechanical stereotactical locating cubic frame, foot holder and localization operative apparatus. Special navigation software can be used for registration of X-ray fluoroscopic images and real-tune controlling navigation of tools. Twenty-one cases of close tibial and fibular fractures were treated with closed intramedullary nailing, 6 of which involved in middle third, 12 in middle and lower third, 3 in lower third. C-arm alignment and registration time, fluoroscopic time and drilling time involved in the locking procedure were recorded. The size of unreamed or reamed tibial nails ranged from 8/300-11/330. Results: All distal holes except 1 were locked successfuUy. In 9 of 41 locked holes (21.95%), the drill bit touched the canal of locking hole without damage of the nail and clinical consequences. The fluoroscopy time per pair of screws was 2.23 s±0.31 s . Conclusions: The computer-assisted auto-frame navigation system for distal locking is well designed, easy to operate and do not need additional instruments during the procedure. The developed system enables the physician to precisely navigate surgical instruments throughout the anatomy using just a few computer-calibrated radiographic images. The total time of x-ray exposure per procedure can be significantly reduced.     

计算机导航下交锁髓内钉的远端螺钉交锁

目的报道计算机导航技术应用于交锁髓内钉远端交锁螺钉固定效果。方法6例股骨、4例胫腓骨骨折，交锁髓内钉置入后，只需要一次C臂X线机透视定位，存计算机导航下完成远端交锁螺钉的固定。结果10例全部在导航下完成交锁髓内钉的远端交锁，平均透视时间为10s。结论计算机导航手术用于交锁髓内钉的远端固定十分有效，可避免机械引导器的误差。     

4种内固定方法治疗锁骨中段骨折疗效比较

目的比较不同内固定方法治疗锁骨中段骨折的疗效。方法应用重建锁定钢板、锁定解剖钢板、Herbert中空螺钉和交锁髓内钉4种内固定方法治疗111例锁骨中段骨折患者。比较4种手术方法的手术时间、切口长度、术中出血量、骨折愈合时间及肩关节功能。结果患者均获得随访,时间12~18个月。手术时间:重建锁定钢板组长于锁定解剖钢板组、Herbert中空螺钉组和交锁髓内钉组,差异有统计学意义(P0.05)。术中出血量:重建锁定钢板组和锁定解剖钢板组多于Herbert中空螺钉组和交锁髓内钉组,差异有统计学意义(P0.05)。切口长度:重建锁定钢板组和锁定解剖钢板组长于Herbert中空螺钉组和交锁髓内钉组,差异有统计学意义(P0.05)。骨折愈合时间:重建锁定钢板长于锁定解剖钢板组、Herbert中空螺钉组和交锁髓内钉组,差异有统计学意义(P0.05)。4种手术方法肩关节功能JOA评分比较差异无统计学意义(P0.05)。并发症:重建锁定钢板组、锁定解剖钢板组各有2例钢板断裂,Herbert中空螺钉组2例退钉,交锁髓内钉组无并发症发生。结论 4种固定方法治疗锁骨中段骨折均取得满意疗效,Herbert中空螺钉和交锁髓内钉固定治疗锁骨中段骨折较重建锁定钢板和锁定解剖钢板固定更符合生物力学特性,更具合理性。     

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.     

Intramedullary nailing of femoral shaft fractures. Part III: Long-term effects of static interlocking fixation.

The results of treatment of fractures of the femoral shaft with static interlocking nailing were reviewed retrospectively to determine the clinical importance of any stress-riser or stress-shielding properties of the nail. These properties, if relevant, would have been manifested by refracture of the femur, either through a hole used for a locking screw or through the original site of fracture after extraction of the device. Two hundred and fourteen fractures that had been treated with static interlocking nailing and that had healed without conversion to dynamic intramedullary fixation were divided into two groups. In Group I, which comprised 111 fractures, the static interlocking-fixation device was retained and in Group II, which comprised 103 fractures, the static interlocking-fixation device was removed during one operative procedure at an average of fourteen months after the injury. The average duration of follow-up was thirty months from the time of the original fixation in both groups. All patients in Group II were followed for a minimum of six months after removal of the nail. No femur in Group I, in which the static interlocked nail remained in situ, refractured. No femur in either group fractured through the proximal or the distal holes used for the locking screws. No locking screws or nails broke. One patient (1 per cent) in Group II had a refracture of the femoral shaft through the site of the original fracture six weeks after removal of the nail.(ABSTRACT TRUNCATED AT 250 WORDS)     

Computerassistierte Verschraubung des hinteren Beckenrings

OBJECTIVE: Computer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation. MATERIALS AND METHODS: Twenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw. RESULTS: All navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures. CONCLUSION: Our data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.     

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.     

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.     

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.     

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.     

闭合复位交锁髓内钉固定治疗股骨干骨折

目的探讨应用闭合复位交锁髓内钉固定治疗股骨干骨折的临床效果。方法回顾性分析2007年2月至2008年1月应用闭合复位交锁髓内钉内固定技术治疗股骨干骨折患者123例,男94例,女29例;年龄24～54岁,平均39岁;开放性骨折27例,闭合性骨折96例。根据AO分型：A型46例,B型38例,C型39例。结果 A型骨折手术时间45～62 min,平均53 min;B型骨折手术时间49～68 min,平均59 min;C型骨折手术时间48～82min,平均67 min。3例股骨近端内侧皮质粉碎骨折或骨折向内成角,其中1例髋内翻;4例骨折远端出现劈裂;1例膝关节外翻;5例术锁钉断裂或退出;1例主钉断裂;8例出现不同程度的神经牵拉伤。无一例出现深静脉血栓、肺栓塞和感染并发症。其中112例获得随访,随访时间为12～20个月,平均16个月。A型和B型骨折78例中39例行静力改动力化锁钉,骨折平均愈合时间为6个月;另39例行持续静力化锁钉,骨折平均愈合时间为8个月。C型骨折平均愈合时间为12个月。无一例患者出现骨折不愈合。术后患者髋膝关节功能优良率为98%。结论闭合复位交锁髓内钉内固定术是治疗股骨干骨折的有效方法之一。     

Retrograde intramedullary nailing of supracondylar femur fractures above total knee arthroplasty: A preliminary report of four cases

Four supracondylar fractures of the femur in three patients with total knee arthroplasties were treated by retrograde intramedullary nailing using an interlocking reamed nail (GSH Nail, Smith and Nephew Richards, Memphis, TN) specifically designed for fractures of the distal femur. Three cases were acute fractures and one was a refracture through a screw hole of a previously plated supracondylar fracture. All fractures healed and there were no complications. The procedure is performed by closed nailing using fluoroscopic guidance with the nail placed through the intercondylar notch of the femoral prosthesis and interlocking to the fracture fragments with a percutaneous targeting device. The advantages are that the procedure is performed by closed techniques that preserve the fracture hematoma and reduce operative blood loss, the fracture is stabilized by a load-sharing nail, and immediate motion with limited weight bearing is possible.