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.     

Novel computer-assisted fluoroscopy system for intraoperative guidance: feasibility study for distal locking of femoral nails

OBJECTIVES: Orthopaedic procedures that use fluoroscopy require intraoperative mental navigation of the surgical tools in a three-dimensional space. Moreover, because of their reliance on real-time monitoring, such procedures are frequently associated with increased x-ray exposure. The goal of this study was to develop a computer-guided surgical navigation system based on fluoroscopic images that not only facilitates direction of surgical tools within anatomy, but also provides constant feedback without the need for radiologic updates. To evaluate the feasibility of the new technology, the authors used it on cases requiring distal locking of femoral nails. METHODS: The hardware components of the system include an instrumented C-arm, optoelectronic position sensor, stereotactic tools, and custom-made software. Computer integration of these devices permitted C-arm alignment assistance and real-time navigation control without constant x-ray exposure. The nails were locked in a variety of media, including plastic femurs, dry human femoral specimens, human cadavers, and one clinical case. Unreamed femoral nail sizes ranged from 9/340 to 12/400. Radiographs were taken to confirm that screws were positioned correctly, and fluoroscopic time associated with the locking procedure was recorded. RESULTS: All distal holes were locked successfully. In eight (11 percent) of seventy-six holes, the drill bit touched the canal of the locking hole, albeit with no damage to the nail and no clinical consequences. The fluoroscopy time per pair of screws was 1.67 seconds. CONCLUSIONS: The developed system enables the physician to precisely navigate surgical instruments throughout the anatomy using just a few computer-calibrated radiographic images. The total radiation time per procedure can be significantly reduced because additional x-ray exposure is not required for tool navigation.     

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。     

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.     

Fluoroscopic navigation system for hip surface replacement.

Metal-on-metal hip resurfacing arthroplasties represent an alternative to total hip arthroplasties for young and active patients, enabling the preservation of intact femoral bone and therefore improving the prognosis for future hip joint replacements. Follow-up studies have shown that the main reasons for early implant failure are mal-orientation of the implant stem in relation to the femoral neck axis, and notching of the femoral neck during femoral head preparation, as well as by exposed cancellous bone after implantation. A computer-assisted planning and navigation system for the implantation of femoral hip resurfacing implants has been developed which supports the surgeon during intraoperative fluoroscopy-based planning and navigation of implant positioning. This paper presents the results of a cadaver study performed to evaluate the system's functionality and accuracy.     

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.     

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.     

Osteosynthese von Schenkelhalsfrakturen

The aim of this review is to summarise the current status of the advantages and disadvantages of computer-assisted, fluoroscopy-based 2-D navigation of femoral neck fractures. An electronic database search using PubMed, Medline, the Cochrane Library, Google and databases of the Deutsches Institut für Medizinische Dokumentation und Information (DIMDI) was performed and selected studies were assessed. We found six reports about computer-assisted, fluoroscopy-based navigation of femoral neck fractures. Advantages are the reduction in fluoroscopic radiation exposure. Disadvantages are just marginally improved precision compared to the conventional procedure, prolonged operative time and increased costs. There is no evidence for benefits of computer-assisted, fluoroscopy-based 2-D navigation in the treatment of femoral neck fractures. Improvement of accuracy and precision is essential to enable experimental and prospective studies in order to define the value of 2-D navigation. Organisational and time expense in contrast to conservative treatment needs to be justified.     

瞄准器引导股骨交锁髓内钉远端锁钉的再认识

[目的]分析瞄准器引导下股骨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]用配备远端瞄准器的股骨交锁髓内钉治疗股骨干骨折297例（301侧股骨），髓内钉301枚，国产钉216枚，进口钉85枚；粉碎性骨折108例，非粉碎性骨折189例；其中4例双侧股骨干骨折；均采取静力型固定，远近端各2枚锁钉。[结果]301枚股骨交锁髓内钉有288枚远端锁钉一次成功，有13枚初次锁钉未成功，一次锁钉成功率为95．7％。[结论]股骨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，必须重视包括术前准备在内的各个环节。     

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.     

Femurschaftfraktur

Femoral malrotation is a frequent malpositioning problem following femoral nail osteosynthesis (17%–34%). The only valid objective monitoring method is computer tomography-assisted torsion measurement between the proximal and distal femur; however, this can only be carried out postoperatively, thereby possibly necessitating a second surgical intervention. A discrepancy of 15° compared to the opposite side is seen as requiring revision. In recent years, navigation-assisted modules have been developed, which make intraoperative assessment and correction of femoral rotation discrepancies possible. These modules also make navigation-assisted definition of the optimal incision, navigation-assisted intramedullary opening, navigation of the femoral nail and navigation-assisted interlocking possible. The main problem lies in the extra workflow, which currently involves an unacceptably extended operating time. In addition to ergonomic advances and individualisation of procedures, the operator should reconsider the use of“hybrid navigation”, whereby only those navigation-assisted tasks deemed necessary by the individual operator are carried out.     

Evaluation of the Stryker S2 IM Nail Distal Targeting Device for reduction of radiation exposure: a case series study

Distal locking is one challenging step during intramedullary nailing of femoral shaft fractures that can lead to an increase of radiation exposure. In the present study, the authors describe a technique for the distal locking of femoral nails, implementing a new targeting device in an attempt to reduce radiation exposure and operational time. Over a 2-year period, 127 consecutive cases of femoral shaft fractures were included in the study. All cases were treated with nailing of femoral shaft fractures with an unslotted reamed antegrade femoral nail and distal locking was performed with the use of a proximally mounted aiming device. Mean duration of the procedure was 63.5 ± 18.1 min while the duration for distal locking was 6.6 ± 2.6 min. In all successful cases, exposure from intraoperative fluoroscopy was 17.2 ± 7.4 s for the whole operative procedure, and for distal locking was 2 shots, 1.35 s (range, 0.9–2.2 s) and 1.9 mGy (range, 1.1–2.9 mGy). Five cases (3.9%) were unsuccessful, but overall no intraoperative complications were encountered from the application of this technique. The ability of the device to correspond to the level of nail deformation and to properly identify the distal holes, reduced exposure to radiation compared to other published reports, and should be considered as a valuable tool for distal locking of femoral fractures.     

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.     

Fluoroscopy-based multiplanar image guidance for insertion of sacroiliac screws

A prospective controlled experimental study was done to assess the value of fluoroscopy-based, computer-assisted orthopaedic surgery for the insertion of sacroiliac screws and to compare this new technology with the conventional technique, using image intensification. In a simulated surgical setup, 140 cannulated screws were placed into the S1 and S2 vertebral bodies of 35 pelvic models. The screws were inserted under fluoroscopy-based image guidance or with the conventional technique. Different drills were tested with both techniques, including a 2.8-mm guide wire and a 5-mm solid drill. The 2.8-mm guide wire proved inaccurate with the computer-assisted image guidance system because of guide wire flexibility. Using the more rigid 5-mm drill, the results of computer-assisted image guidance were comparable with the image intensifier technique. The radiation exposure during screw insertion was reduced considerably when using the image guidance system. System-specific requirements warranted adjustment of surgical technique and instruments. The major advantages of this new technology are immediate intraoperative image acquisition and provision of surgical guidance in as much as four planes simultaneously. The results of this experimental study are encouraging and have led to initiation of a clinical trial.     

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.     

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.     

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.     

Intraoperative accuracy evaluation of virtual fluoroscopy--a method for application in computer-assisted distal locking.

Virtual fluoroscopy integrates intraoperative C-arm fluoroscopy as an imaging modality for surgical navigation. In the operating room, the conditions for application of virtual fluoroscopy may be impaired. In such situations, the surgeon is interested in an intraoperative check to decide whether the accuracy available is sufficient to perform the scheduled procedure. The test principle is to include an artificial landmark within the fluoroscopic images acquired for virtual fluoroscopy. As this landmark is fixed outside the patient, it can be touched with the referenced tool prior to performing the procedure. A mismatch between the actual tool position at the landmark and the virtual tool position as visualized on the computer screen allows estimation of the system's accuracy. The principle described was designed for detection of inaccuracies resulting from input of nonoptimal data to the navigation system. The method was successfully applied during computer-assisted distal locking of intramedullary implants, and the test principle might be adapted for other applications of virtual fluoroscopy.     

Computer-assisted spinal navigation versus serial radiography and operative time for posterior spinal fusion at L5-S1

OBJECTIVE: To review the operative time differences between computer-assisted spinal navigation versus serial radiography. SUMMARY OF BACKGROUND DATA: There have been multiple studies describing the use of computer-assisted image guided surgery (IGS) in the application of spinal instrumentation. Techniques have evolved to allow attainment of multilevel visualization intraoperatively both successfully and safely. These have proven to result in low screw misplacement rates, low incidence of radiation exposure and excellent operative field viewing. As a result, image guidance has become an increasingly accepted and practiced form of intraoperative spinal navigation. However, potential limitations to IGS have been described including longer operating times. Many studies have looked at the success of beneficial outcomes; however, none to our knowledge have reviewed such described operative time increments with IGS. METHODS: The authors performed a retrospective database analysis of 105 patients undergoing posterior L5-S1 spine fusion with pedicle screw instrumentation for isthmic spondylolisthesis with and without the use of fluoroscopy-based image guidance. This was followed by a chart review of anesthesia operative time documentation. Subsequent time calculations and statistical analysis were performed for comparison. RESULTS: Computer-assisted image-guided spine surgery has overall demonstrated shorter mean operative times when compared with intraoperative serial radiography technique; an average of 40 minutes less per case (P<0.001). There is also less variation in operative times using image guidance, with 13 of 43 (30%) cases using serial x-ray lasting more than 3.75 hours compared with none of the 57 done via image guidance (P<0.001). The operative duration for both procedures trended downward over time. For both procedural cohorts operating room time continued to decrease as of the most recent year being performed. Lastly, in an attempt to minimize such a confounding factor as a learning curve, the last 20 cases in each group were compared. There was an average difference of about 22 minutes less for the image guidance group but missed being statistically significant (P=0.0503). CONCLUSIONS: Image-guided spinal surgery did not cause an increase in operative time. In the best scenario, image navigation saved a statistically significant (P<0.001) amount of time in the operating room. At its worst, fluoroscopy-based image-guided navigation is not significantly different from standard serial radiography.     

Failure of intramedullary femoral nail with segmental breakage of distal locking bolts: a case report and review of the literature

Breakage of locking bolts is an important cause of interlocking nail failure in femoral fractures. It usually occurs in the form of single breakage in one of the distal bolts of the nail or nail breakage around the distal locking hole. Here we report an unusual case of intramedullary femoral nail failure with segmental breakage of both the distal locking bolts. Such a scenario usually complicates further management. We successfully managed this case with exchange nailing without bone grafting. Here we briefly reviewed the literature regarding such an unusual presentation and discussed in detail the possible etiology of such a presentation and the management options when facing such a complex situation.