Comparative study on treatment of midshaft tibial fracture with expandable and interlocking intramedullary nails

Objective ： To evaluate the clinical results of treatment of midshaft tibial fracture with expandable intramedullary nails compared with interlocking intramednilary nails. Methods： From June 2003 to August 2005, 46 patients （27 males and 19 females, aged 20-74 years, mean =38.4 years ） with midshaft tibial fracture were treated surgically in our department. The causes of fractures were traffic injury in 21 patients, fall injury in 6, tumbling injury in 11 and crushing injury in 8. According to AO/ ASIF classification, Type A fracture was found in 16 patients, Type B in 11, Type C1 in 5, and Type C2 in 2. Open fractures were found in 12 patients, according to Gustilo classification, Type Ⅰ in 9 patients and Type Ⅱin 3 patients. Based on the patients＇consent, 24 patients were treated with expandable intramedullary nails （Group A ） and 22 with interlocking intramedullary nails （Group B ）. The operation time, blood loss during operation, X-ray fluoroscopic times, hospitalization time, weight bearing time after operation, healing time of fracture and complications of all the patients were recorded. The clinical effects of all the cases were evaluated according to the criteria of Johner-Wruhs. Results： All the patients were followed up for 12,34 months （ mean = 16.2 months）. The time of operation, the blood loss, X-ray fluoroscopic times, hospitalization time and healing time of fracture of Group A significantly decreased （P 〈 0.05 ） compared with those of Group B, but the time for weight bearing after operation, the Johner- Wruhs degree of clinical effects and complications had no significant difference between Group A and Group B （P〉0.05）. Conclusions： Expandable intramedullary nail can shorten operation time, decrease blood loss and reduce invasion, which is a safe and effective treatment method for tibial midshaft fracture.     

Closed reduction and intramedullary nailing versus open reduction and locking plate fixation in treatment of middle and upper humeral fractures北大核心CSCD

Objective To compare closed reduction and intramedullary nailing versus open reduction and locking plate fixation in the treatment of middle and upper humeral fractures. Methods A retrospective case-control study was conducted to analyze the clinical data of 62 patients with middle and upper humeral fracture who had been treated at Department of Orthopaedics, The First People's Hospital of Jinmen and at Department of Orthopedics, General Hospital of PLA Central Theater from October 2017 to February 2021. There were 35 males and 27 females, aged from 27 to 86 years. The left side was affected in 24 cases and the right side in 38 cases. All fractures were fresh. According to the AO classification, 16 cases were type A, 32 type B, and 14 type C. Of the patients, 29 were treated with closed reduction and intramedullary nailing (intramedullary nail group) and 33 with open reduction and locking plate fixation (locking plate group). The length of incision, operation time, intraoperative blood loss, hospital stay, fracture healing and complications were recorded and compared between the 2 groups. The pain degree was evaluated by visual analogue scale (VAS) at one week and one month after operation, and the functional recovery of the shoulder was evaluated by Constant-Murley score at one month and 12 months after operation. Results There was no significant difference in the preoperative general data between the 2 groups, showing comparability (P>0.05). The intramedullary nail group was followed up for 12 to 29 months and the locking plate group for 15 to 50 months. In the intramedullary nail group, the length of incision [(4.1±0.7) cm], operation time [(58.3±7.7) min], intraoperative blood loss [(52.7±6.5) mL], and hospital stay [(7.3±1.5) d] were significantly less than those in the locking plate group [(21.7±2.3) cm, (95.8±11.7) min, (237.4±14.9) ml, and (12.3±1.7) d] (P<0.05). The fracture healing time in the intramedullary nail group was (5.0±1.9) months, significantly longer than that in the locking plate group [(3.5±1.7) months] (P<0.05). The VAS scores at one week and one month after operation in the intramedullary nail group [(2.8±0.3) points and (1.2±0.5) points] were significantly lower than those in the locking plate group [(4.3±0.4) points and (1.6±0.5) points], and the Constant-Murley score at one month after operation in the intramedullary nail group [(63.5±7.4) points] was significantly higher than that in the locking plate group [(54.3±6.9) points] (P<0.05). However, at 12 months after operation, there was no significant difference in the Constant-Murley score between the 2 groups (P>0.05). In both groups, the VAS score at one month after operation was significantly lower than that at one week after operation while the Constant-Murley score at 12 months after operation was significantly higher than that at one week after operation (P<0.05). In the intramedullary nail group, intraoperative distal refracture happened in one case; in the locking plate group, incision infection occurred in one case and postoperative radial nerve injury in another. There was no significant difference in the incidence of complications between the 2 groups [3.4% (1/29) versus 6.1% (2/33)] (P>0.05). Conclusion In the treatment of middle and upper humeral fractures, compared with open reduction and locking plate fixation, closed reduction and intramedullary nailing shows advantages of a smaller surgical incision, shorter operation time, less intraoperative blood loss, shorter hospital stay and faster functional recovery. © The Author(s) 2022.     

A distal-lock electromagnetic targeting device for intramedullary nailing:Suggestions and clinical experience

Purpose: To describe our clinical experience with a system named SureShot? Distal Targeting (Smith & Nephew, Memphis, USA) based on magnetic field presence and discuss our suggestions on this technique. Methods: We analysed prospectively 47 patients affected by humeral, tibial or femoral fractures, treated in our institution during a 3-year period of time (August 2010 to September 2013). We considered the following parameters: the time to set up, the time to position a single screw, the effectiveness of the system (drilling ad screwing), the irradiation exposure time during distal locking procedure and surgical complications. Results: A total number of 96 screws were inserted. The mean preparation time of the device was 5.1 min ± 2 min (range 3e10 min). The mean time for single screw targeting was 5.8 min ± 2.3 min (range 4e18 min). No major complications occurred. Only a few locking procedures were needed to be practiced in order to obtain the required expertise with this targeting device. Conclusion: According to our results, this device is reliable and valid whenever the correct technique is followed. It is also user friendly, exposes to lower radiation and needs less surgical time compared to relative data from the literature. However, the surgeon should always be aware of how to use the free hand technique in case of malfunctioning of the system.     

Pedicle screw placement in the thoracic spine: a randomized comparison study of computer-assisted navigation and conventional techniques

Objective： To evaluate the accuracy of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation techniques.
Methods： Total 176 thoracic pedicle screws placed in 42 thoracic fracture patients were involved in the study randomly, 20 patients under conventional fluoroscopic control （84 screws） and 22 patients had screw insertion under three dimensional （3D） computer-assisted navigation （92 screws）. The 2 groups were compared for accuracy of screw placement, time for screw insertion by postoperative thincut CT scans and statistical analysis by χ^2 test. The cortical perforations were then graded by 2-mm increments： Grade Ⅰ （good, no cortical perforation）, Grade Ⅱ （screw outside the pedicle 〈2 mm）, Grade Ⅲ （screw outside the pedicle 〉2 mm）.
Results： In computer assisted group, 88 （95.65%） were Grade Ⅰ （good）, 4 （4.35%） were Grade Ⅱ （〈2mm）, no Grade Ⅲ （〉2 mm） violations. In conventional group, there were 14 cortical violations （16.67%）, 70 （83.33%） were Grade Ⅰ （good）, Ⅱ （13.1%） were Grade Ⅱ （〈2 mm）, and 3 （3,57%） were Grade Ⅲ （〉2 mm） violations （P〈0.001）. The number （19.57%） of upper thoracic pedicle screws （ T1-T4 ） inserted under 3D computer-assisted navigation was significantly higher than that （3.57%） by conventional fluoroscopic control （P〈0.001）. Average screw insertion time in conventional group was （4.56 ±1.03） min and （2.54 ± 0.63） min in computer assisted group （P〈0.001）. In the conventional group, one patient had pleura injury and one had a minor dura violation.
Conclusions： This study provides further evidence that 3D computer-assisted navigation placement ofpedicle screws can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly upper thoracic spine.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

计算机导航对人工髋关节股骨柄假体置入的精确性验证

Objective To evaluate the accuracy of surgical navigation for localization and orientation of the femoral stem component in total hip arthroplasty, nethods In the hypothesized space, 3-D images of femoral stem were reconstructed. The coronal, sagittal and horizontal axes and scale divisions were established to calculate the displacement and rotation of the stem. Matching between the stem and its 3-D images was performed while the stem was moved in various distances and angles on the digital motion-platform. Then the actual change in the position of the implant and the caleulative data obtained from the navigation system were compared to evaluate the accuracy. Results The mean difference in displacement between the measurements and the actual changes was (1.01 ±0.47) mm, and the mean difference in the measured and actual angles was 1.09°±0.62°. The duplicate test found no significant difference (t = 0.238, P > 0.05). Conclusion Precise placement of the stem in the desired location and orientation can be achieved by the navigation system in the total hip arthroplasty.     

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。     

计算机辅助带锁髓内钉远端锁定瞄准系统的设计与实验研究

目的　测试计算机辅助带锁髓内钉远端锁定瞄准系统应用于下肢模型骨及尸体骨固定中的准确性及安全性。方法　采用 10根塑料模型胫骨 ,2 0根塑料模型股骨 (SynboneAG ,Malans,Switzerland) ,6具青年男性新鲜尸体的双下肢标本 ,随机平均分为两组 ,行胫骨、股骨带锁髓内钉内固定术 (Orthofix带锁髓内钉 ,每根针远端有 2孔 )。在远端锁钉时 ,实验组采用计算机辅助带锁髓内钉远端锁定瞄准系统 ;对照组采用Orthofix带锁髓内钉机械锁定瞄准器。两组以远端锁钉锁定的手术操作时间、在C型臂X线下暴露时间、锁定的成功率三项指标进行比较。结果　实验组锁钉锁定的手术时间、X线下暴露时间、锁定成功率分别为 (4 4 4± 2 99)min、(1 16± 0 38)min ,(10 0± 0 ) % ;对照组手术时间、X线下暴露时间、锁定成功率分别为 (10 4 2± 4 18)min ,(4 71± 3 86 )min ,(94 4 4±0 36 ) % ,两组手术与X线下暴露时间显著减少 (P <0 0 5 )。结论　计算机辅助带锁髓内钉远端瞄准系统设计合理、定位准确、操作简便、成功率高、缩短了手术时间 ,特别是在手术中对C型臂X线的依赖程度降低 ,在X线下暴露时间短 ,减少了医患人员的放射损伤。该系统能够通用于各种类型的髓内针 ,便于推广、普及。     

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.     

导航在长骨干骨折髓内钉固定中的应用

目的阐述透视导航技术在长骨干(股骨和胫骨)骨折,特别是在术中远端交锁髓内钉固定中的应用。探索在导航条件下术中应用髓内钉图像库开展远端交锁固定的可行性。此外,医用机器人的开发旨在被进一步用来改善手术程序的精确性。方法导航手术下,55例行股骨远端交锁钉固定和36例行胫骨远端交锁钉固定。其中13例术中应用图像库开展远端交锁固定。结果远端交锁固定成功率为97%。结论透视导航在长骨干骨折术中,使远端髓内交锁钉固定成功率增高。图像库的应用可以进一步减少患者和手术人员的X线辐射剂量。     

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.     

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.     

Reducing intraoperative duration and ionising radiation exposure during the insertion of distal locking screws of intramedullary nails: a small-scale study comparing the current fluoroscopic method against radiation-free,electromagnetic navigation

Background

Intramedullary nailing is the standard surgical treatment for mid-diaphyseal fractures of long bones; however, it is also a high radiation dose procedure. Distal locking is regularly cited as a demanding element of the procedure, and there remains a reliance on X-ray fluoroscopy to locate the distal holes. A recently developed electromagnetic navigation (EMN) system allows radiation-free distal locking, with a virtual on-screen image.

Objective

To compare operative duration, fluoroscopy time and radiation dose when using EMN over fluoroscopy, for the distal locking of intramedullary nails.

Method

Consecutive patients with mid-diaphyseal fractures of the tibia and femur, treatable with intramedullary nails, were prospectively enrolled during a 9-month period. The sample consisted of 29 individuals, 19 under fluoroscopic guidance and 10 utilising EMN. Participants were allocated depending on the type of intramedullary nail used and surgeon’s preference. These were further divided into tibial and femoral subcategories, relative to the fracture site.

Results

EMN reduced fluoroscopy time by 49 (p = 0.038) and 28 s during tibial and femoral nailings, respectively. Radiation dose was reduced by 18 cGy/cm² (p = 0.046) during tibial and 181 cGy/cm² during femoral nailings when utilising EMN. Operative duration was 11 min slower during tibial nailings using EMN, but 38 min faster in respect of femoral nailings.

Conclusions

This study has evidenced statistically significant reductions in both fluoroscopy time and radiation dose when using EMN for the distal locking of intramedullary nails. It is expected that overall operative duration would also decrease in line with similar studies, with increased usage and a larger sample.

     

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。     

A foolproof technique for lock-check and distal locking in interlock nailing

Interlocked nailing as a treatment modality for long bones' fracture is one of the most widely performed orthopedic surgeries. Closed locked nailing is also the gold standard method of treating femoral and tibial shaft fractures. But the most variable factor in this procedure is distal locking. It may sometimes be time consuming and involve radiation exposure. The freehand technique for distal locking of intramedullary nails is plagued with dependence on an image intensifier which may not be available at all centers especially in developing countries like ours. Also, the radiation and operative time increase with this method.Hence, there is a need to develop a radiation safe and sound method in this green world to decrease carbon emissions to replace/supplement freehand distal locking techniques. “Tak-Tak” method described here decreases our dependence on the image intensifier and in addition improves accuracy when using aiming jigs.     

Tibiotalocalcaneal arthrodesis with a retrograde intramedullary nail: a biomechanical analysis of the effect of nail length

BACKGROUND: Fatigue fractures of the tibia have been observed at the level of the proximal end of the nail after successful tibiocalcaneal arthrodesis with a retrograde intramedullary device. MATERIALS: To study the effect of nail length, five matched pairs of cadaver tibiae were instrumented with strain gauges and potted in methylmethacrylate from a level 3 cm proximal to the distal medial malleolus to simulate a successful tibiocalcaneal arthrodesis. A standard length (15 cm) ankle arthrodesis nail and an identical longer device terminating in the proximal tibial metaphysis were inserted in each paired tibia using appropriate technique. The strain of the posterior cortex of the tibia was recorded under bending moments of up to 50 Nm for each intact specimen after nail insertion and after proximal locking of the nail. The nails were then exchanged between the specimens of the same pairs and the experiment was repeated to insure uniformity. RESULTS: The standard length locked nail increased the principal strain of the posterior cortex of the tibia at the level of the proximal screw holes 5.3 times more than the locked long nail (353 and 67 microstrains), respectively. This stress concentration was not observed when the proximal extent of the nail terminated within the proximal tibial metaphysis. CONCLUSION: A successful tibiocalcaneal arthrodesis with a standard length locked intramedullary nail creates stress concentration around the proximal screw holes that may be responsible for the fractures observed clinically. This study supports the use of a "long" retrograde locked intramedullary nail for tibiocalcaneal arthrodesis in patients with systemic or localized osteopenia.