The clinical application of a novel method of internal fixation for femoral neck fractures—dynamic locking compression system

The clinical application of a novel method of internal fixation for femoral neck... Background: Femoral neck fractures are the commonly encountered injury in orthopedic practice and result in significant morbidity and mortality. Currently, how to treat femoral neck fractures safely and effectively is still a challenge. The objective of this study is to evaluate the efficiency of dynamic compression locking system for femoral neck fractures. Methods: This is a retrospective study conducted from May 2015 to October 2016. The study included 36 patients suffering from femoral neck fractures who underwent closed reduction and were fixed using dynamic compression locking system. All surgeries were performed by the same surgeon. The study was conducted by telephone and on-site follow-up. The Garden classification and anatomical site classification were categorized for all patients. We assessed radiographic outcomes of union, femoral neck shortening, screw back-out, and femoral head avascular necrosis. We also evaluated functional outcome using the Harris hip score. Other outcomes included the length of surgery, duration of hospital stay, injury to surgery time, intraoperative hemorrhage, time to clinical bone union, and other fracture complications. Results: All patients were followed up 12 to 29 months with an average of 21.58 ± 5.41 months. All cases were caused by falls including 17 males and 19 females with an average age of 65.33 ± 9.30 years old ranging from 53 to 82 years old. Among them, injury to surgery time ranged between 1 and 4 days with an average of 2.58 ± 1.05 days. Duration of hospital stay was 8 to 21 days with an average of 15.33 ± 3.71 days. Intraoperative hemorrhage was 40 to 80 ml with an average of 61.67 ± 12.31 ml. Operation time was from 35 to 80 min with average of 50.25 ± 11.77 min. According to Garden classification, 9 cases (25%) were type II and 27 cases (75%) were type III. According to the anatomical site classification, 8 cases (22.2%) were subcapital femoral neck fractures, 19 cases (52.8%) trans-cervical, and 9 cases (25%) basi-cervical. At present, the follow-up has not found the fracture complications of femoral head avascular necrosis, fracture nonunion, and re-fracture. All patients achieved solid bone union. The mean time of clinical bone union was 3 to 4 months. Among all patients, there were only 3 cases of femoral neck shortening < 5 mm and 1 case of screw back-out = 4 mm. For Harris scoring, average Harris scale at the end of the follow-up was 93.42 ± 3.95 ranging from 85 to 98. There were 32 cases of excellent function scores on the Harris scale and 4 cases of good function scores on the Harris scale. Therefore, the excellent and good rate of Harris hip scores was 100%. (Continued on next page) * Correspondence: Lsg66128@sina.com; 1310439232@qq.com Department of Orthopedic Surgery, China Resources & WISCO General Hospital, No. 209 Yejin Road, Wuhan, Hubei Province, China Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 2 of 8 (Continued from previous page) Conclusions: Femoral neck dynamic compression locking system for femoral neck fractures in elderly patients can provide effective stability and reduce complications and revision rates. Keywords: Femoral neck fractures, Internal fixation, Aged, Surgery, Locking compression plate, Background Resources & WISCO General Hospital approved this Hip fractures are the most common fragility fractures with retrospective study, and informed consents were taken the significantly reduced limb function and the markedly de- from all the patients. This study assessed patients with creased quality of life after injuries. The number of hip frac- femoral neck fractures who underwent fixation with dy- tures per annual worldwide is expected to rise to 2.6 million namic compression locking system (Suzhou Orthopaedics by 2025 and 4.5 million by 2050 [1]. Use of the Garden Instrument CO. Ltd., Suzhou, China) from May 2015 to and anatomical site classification systems has remained the October 2016. In total, all patients were included and clinical mainstay of femoral neck fracture characterization anteroposterior and axial femoral beck radiographs were which help demonstrate appropriate treatment. Operative obtained on first admission following falls. All fracture options include in situ fixation, closed or open reduction patterns were recorded according to the Garden and ana- with internal fixation, and hip arthroplasty [2]. tomical site classification systems. As a matter of fact, femoral neck fractures are the most All surgeries were performed by the first surgeon. The common hip fractures, accounting for approximately 57% study was conducted by telephone and on-site follow- of all hip fractures [3]. At present, three hollow screws are up. We assessed radiographic outcomes of union, fem- often used for the internal fixation of femoral neck fractures oral neck shortening, screw back-out, and femoral head [4]. It can compress fracture ends, but three hollow screws avascular necrosis. Regarding the outcome of femoral are not interrelated to form a framework structure. More- neck avascular necrosis, we only assessed the radio- over, the positions of three hollow screws are subjectively graphic outcomes of the patients having at least 18 or influenced by the surgeons. The rotational resistance and 24 months postoperatively. We also evaluated functional vertical shear resistance were poor in some studies [5–7]. outcome using the Harris hip scores. Other outcomes Moreover, loosening of internal fixation, displacement of included the length of surgery, duration of hospital stay, femoral head, and femoral neck nonunion usually happened injury to surgery time, intraoperative hemorrhage, time [8]. During the healing process, lack of effective continuous to clinical bone union, and other fracture complications. locking support can lead to the shortening of the femoral The inclusion criteria were as follows: (1) neck of neck [5–7]. Femoral neck dynamic compression locking sys- femur fracture, (2) > 50 years old, (3) closed fractures, tem is a new type of internal fixation for femoral neck frac- (4) the type II and III fractures of the Garden classifica- tures and was designed based on the three-dimensional tion, and (5) fractures caused by falling down. Patients anatomical structure of femoral neck. According to the fem- who met the above criteria were included in this study. oral neck scalene triangle juga structure, the three parallel The exclusion criteria were as follows: (1) concomitant screws are located on the three jugas, respectively, which ipsilateral femoral shaft fractures, (2) pathological frac- are close to the bone cortex [9]. Then, three parallel screws tures, (3) stress fractures, (4) the type I and IV of the and a lateral pressure locking plate through three locking Garden classification, and (5) < 50 years old. tail caps integrate into a whole, which forms the stable In this study, 36 cases with femoral neck fractures structure of framework and can precisely and uniformly were caused by falls including 17 males and 19 females, compress and lock fracture ends with the favorable rota- with an average age of 65.33 ± 9.30 years old ranging tional stability and rigid fixation [10]. This implant was between 53 and 82 years old (Fig. 1). Among them, pproved by China medical device regulations (Chinese injury to surgery time was 1 to 4 days with an average of patent no.: ZL201410458654.9). 2.58 ± 1.05 days. Duration of hospital stay was 8 to Therefore, we retrospectively analyzed patients with 21 days with an average of 15.33 ± 3.71 days. Intraopera- femoral neck fractures who were treated with dynamic tive hemorrhage was 40 to 80 ml with an average of compression locking system between May 2015 to October 61.67 ± 12.31 ml. Operation time was 35 to 80 min with 2016 to evaluate the effectiveness, stability, and complica- an average of 50.25 ± 11.77 min. According to the Garden tions of the dynamic compression locking system. classification standards, type II fractures were seen in 9 cases and type III 27 cases. According to the anatom- Methods ical site classification, subcapital femoral neck fractures The methodology of our study is a single-center, retro- were found in 8 cases, trans-cervical fractures of femur spective study. The institutional review board of China 19 cases, and femoral neck basal fractures 9 cases. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 3 of 8 Fig. 1 A 54-year-old man with a displaced left femoral neck fracture fixed with dynamic compression locking system. a Preoperative X-ray. b Postoperative X-ray review at 2 days after operation. c Postoperative X-ray review at 1 month after operation. d Postoperative X-ray review at 4.5 months after operation. e Postoperative X-ray review at 18.5 months after operation Of the patients, 16.7% had diabetes mellitus, 44.4% extorsion of axial traction were conducted and until had hypertension, 33.3% had ischemic heart disease or a closed reduction of the fracture ends was satisfied with previous cerebrovascular event, 22.2% had pulmonary the dynamic monitoring of anteroposterior and axial diseases, and 27.8% had hyperlipidemia. radiographs. Then, surgeon can roll the three parallel guide needles into femoral head within 5 mm of the Surgical procedure subchondral bone of the femoral head. The required After anesthesia involving a continuous epidural or lengths of the needles were measured to guarantee the lumbar anesthesia, the patients were supine with the satisfying location of the screw placement. All three contralateral leg flexed at 90° to enable visualization of screws were positioned within 5 mm of the subchon- the fracture. Then, routine disinfection and sterile dral bone of the femoral head. Finally, surgeon rolled draping of the hip and lower extremities was carried three parallel hollow locking compression screws out. The lateral minimal incision over the greater tro- through the direction of the three guide needles chanter of the femur was performed with a 4–5-cm in- respectively into the neck of femur. At the end of tight- cision length, then the superficial and deep fascial ening screws, three parallel screws(7 mm) should be layers and muscles were isolated sequentially, and the uniformly and accurately compressed. When the intra- lateral cortex of the large tuberosity of the femur was operative radiographs suggested that compression fix- exposed to 6–7 cm length. One or two extracorporeal ation of the fracture ends was satisfying, the tail caps guide needles were placed on the hip. The position of were tightened into the end of the three screws. In the the extracorporeal guide needle was adjusted until the end, sealing the incision layer-by-layer should be pru- needle was parallel to the longitudinal axis of the fem- dentially conducted (Fig. 2). oral neck. According to the direction of the extracor- poreal guide needle, surgeon can insert the top guide Postoperative management needle into the anterior and superior position of the Postoperatively, patients were discharged 1–3 week after greater trochanter of the femur with the continuing surgery. Patients with ischemic heart disease or a previ- monitor of C-arm radiographs. And then along the top ous cerebrovascular event were treated with anticoagu- guide needle, surgeon can install locking plate that had lants for 14 days. A wound check was observed by 2- to installed guide needle sleeve in the greater trochanter 3-day intervals till the removing of the suture 2 weeks of the femur. In the direction of the guide sleeve, sur- after surgery. Follow-up by X-ray is done at 1 week after geon can place the other two parallel guide needles surgery and monthly intervals till complete union was along the direction of the top guide needle into distal achieved, then at 6 months’ intervals till final follow-up. fracture end, and finally the three parallel guide needles Hip range was encouraged as soon as tolerated by the construct an scalene triangle. A closed reduction of patient (usually few days after surgery); partial weight femoral neck fracture was observed with the monitor of bearing was started when tolerated by patients. Full C-arm fluoroscopy. To the Garden III fractures [11], weight bearing was allowed only when full union was ahead of adduction and internal rotation, outreach and achieved. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 4 of 8 Fig. 2 Surgical procedure of the dynamic compression locking system for femoral neck fracture was conducted by the same surgeon. a Placement of extracorporal guide needles. b Insert the top guide needle into the femoral neck along the direction of the extracorporal guide needles. c Install the guide sleeve and insert two other guide needles along the direction of the top guide needle. d After the fracture reduction by closed reduction, the top guide needle was transferred to the femoral head to maintain the repositioned position. e Insert three hollow parallel compression screws along the direction of the guide needles. f Pressure screws evenly and accurately All patients were followed up for at least 1 years post- complications including deep vein thrombosis, pulmonary operatively. Close follow-up at our outpatient depart- embolism, urinary tract infection, wound hematoma, and ment included radiographs of the femoral neck to assess bleeding gastrointestinal tract probably due to the effect fracture healing and the recording of functional out- of early straight leg raising training on postoperative re- comes using the Harris hip scores. All outcomes of habilitation of patients (usually 2 to 3 days after surgery). patients were assessed by two blinded observers. Discussion Results After femoral neck fractures, no matter what type of No patients had died within the last follow-up. All treatment is chosen, it will have a significant impact on patients were followed up about 12 to 29 months with the quality of patients’ life and bring a great economic an average of 21.58 ± 5.41 months. At present, the burden to the society [4]. Compared with hip joint follow-up has not found the fracture complications of replacement, internal fixation surgery, because of its femoral head avascular necrosis, fracture nonunion, and smaller trauma, shorter operation time, less bleeding, re-fracture. There were no reoperation and hip joint lower incidence of postoperative complications and early contracture and difficulty within the final follow-up. All mortality, and lower cost, has become the main treat- patients achieved solid bone union. The time to bone ment of femoral neck fractures clinically [4]. However, union was 3 to 4 months. Among all patients, we used there is still lack of a consistent view of what methods of the method adopted by Zlowodzki [12] to evaluate femoral internal fixation can better maintain the stability of frac- neck shortening and we found that only 3 cases (8.3%) had ture ends, promote fracture healing, and avoid or reduce shortening < 5 mm and were considered as non/mild. Only the complications such as postoperative femoral head 1 case screw back-out distance was 4 mm. For Harris scor- avascular necrosis and internal fixation failures [14]. ing [13], average Harris scale at the final follow-up was In our study, longer duration of hospital stay was asso- 93.42 ± 3.95 ranging from 85 to 98.According to the func- ciated with the presence of ischemic heart disease, cere- tion score of Harris hip, the score of 90–100 is divided into brovascular accident, and pulmonary disease, as these excellent, 80–89 is divided into good, 70–79 is fair, and 70 patients needed to be optimized before discharge. None- points below is poor. There were 32 cases of excellent func- theless, advanced age did not significantly affect the tion score of Harris hip and 4 cases of good function score. duration of hospital stay. In other studies, duration of Of the latter, 3 cases had femoral neck shortening < 5 mm. hospital stay was affected by the number of comor- Therefore, the excellent and good rate of the Harris bidities but not advanced age [15]. The lateral min- hip scores was 100%. There were no perioperative imal incision over the greater trochanter of the femur Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 5 of 8 was performed with a 4–5-cm incision length. Therefore, system (Fig. 3). This system can not only improve the smaller trauma with a smaller amount of blood loss precision and uniform pressure of fracture ends, but can effectively reduce soft tissue exposure and ultim- also have a stable framework structure to lock fracture ately benefits fracture healing. Surgery was performed ends. Moreover, the system is capable of compressing early (an average of 2.58 ± 1.05 days after injury) in fracture ends dynamically [10]. And ultimately, the ends our hospital to reduce the complications associated of the fracture can obtain good short- and long-term with post-fracture bedridden, thereby increasing the fixation, and the rigid fixation ultimately is conducive to surgical tolerability. Moreover, early hip joint function fracture healing. Early biomechanical studies have found exercise after operation effectively reduced postoperative that the finite element analysis of this system in the complications. As a result, perioperative complications did cadaver model was close to the biomechanical conduc- not occur in this study. Our study shows lesser incidence tion of the normal femoral neck with no stress occlusion of perioperative complications compared with other [10], so this system is conducive to the growth and heal- studies [16]. ing of bone scabs in the fracture area. Currently, the Our researchers used computed tomography tech- follow-up has not found the fracture complications of nique to study the anatomical features of femoral neck. femoral head avascular necrosis, fracture nonunion, and The analysis of femoral neck structure using 3D imaging re-fracture. There were no reoperation and hip joint and the cross-section computer software revealed that contracture and difficulty at the final follow-up. All the cross-section of femur neck was an scalene triangle patients achieved solid bone union. But, 3 cases (8.3%) configuration [9]. “Femoral neck safety cross section” had femoral neck shortening < 5 mm and 1 case had was obtained by the cross-section computer software, screw back-out distance = 4 mm, which was associated so the scalene triangular distribution of three screws with severe osteoporosis or sequela of cerebral infarction. in femur neck was developed. The three parallel screws In our study, all patients with femoral neck fractures were are located in the three jugas of the scalene triangle con- caused by falls with good preoperative mobility. So no figuration and are close to the bony cortex, which are patients had died within the final follow-up. Other excellent in biological stability [10]. A lateral locking plate studies reported that the mortality rate was associated and three interlocking tail caps are used to interlink three with preoperative mobility, and preoperative mobility hollow compression screws into a whole to provide rigid was considered the most significant determinant for fixation, which constitutes a dynamic compression locking postoperative survival [16]. Fig. 3 The composition of the dynamic compression locking system and the inverted triangular structure or triangle juga structure of femoral neck obtained by the cadaver model or the cross-section computer software Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 6 of 8 The most commonly internal fixation for fixing femoral similar to these of the Targon FN implant, both of which neck fractures is three cancellous screws [4, 7, 8, 16]. Re- provide an angular and rotator stable construct and offer cent studies described different techniques for divergent a unique sliding mechanism, allowing for controlled screw fixation of neck of femur fractures with the different fracture impaction. However, the Targon FN implant is distribution and direction of the screws in femoral neck combined with two distal locking screws, which can [4, 7, 8, 16]. The rotation stability of the three cancellous improve rotational and angular stability, but weaken screws was relatively variable, and ultimately, the instabil- the ability of sliding compressive mechanism [21]. ity of fracture ends in some studies often adversely influ- Nishiyama et al. [22] indicated that a sliding mechanism enced the fracture healing [17–19]. However, the allowing linear intraoperative and postoperative com- distribution of the three interlocking compression screws pression on the treatment of femoral neck fractures facil- of this system in femoral head position was according to itated fracture healing. The Targon FN is designed to the principle of anatomy and biomechanics of the femoral give a better rotational and angular stability than other neck. One is located in the anterior and inferior part of contemporary internal fixation devices used for femoral the femoral neck with longitudinal pressure, another one neck fractures [21]. Osarumwense et al. [23] showed that sits in the anterior superior tension side of the femoral the results of the Targon FN system for the management neck, and the last one is in the rear and slightly inferior of intracapsular neck of femur fractures in a study with position of the femoral neck. The fixed positions of the minimum 2-year experience and outcome were superior screws are the position in femoral neck with the highest to those then found in the literature for the more trad- bone density [9]. This system provides rigid fixation so itional fixation methods. Nonunion rates are reported to that the anti-rotation resistance is significantly enhanced. range between 2.2 and 2.7% after undisplaced fractures The finite element mechanics analysis of this system and and even 2.2 and 15.4% after displaced fractures [24–26]. the three cannulated screws for femoral neck fractures in Several studies reported a rate of 4–5.5% of avascular the cadaver model suggested that the maximum stress of necrosis after Targon FN fixation of undisplaced frac- the three screws was greater in the three cannulated tures and 4–13.8% after displaced fractures [21, 27]. screws than in this system (138.9 vs. 57.49 MPa) [9, 10]. Parker and Takigawa et al. [21, 27] reported elective The contact pressure of fracture surface was higher in the implant removal in 10.9% after undisplaced fractures three cannulated screw model than in this system model and in 6.4–48.3% after displaced fractures, also mainly (46.9 vs. 22.58 MPa) [9, 10]. Moreover, the three screws in due to discomfort. Besides, Biber et al. [24]reported the femur were more stressed in the three cannulated that hematomarate of the internal fixation for femoral screw model than in this system model. The greater the neck fracture fixed by Targon FN was 4.4% (95% CI, stress value, the greater the damage to the screws, which 0.9–8.0) and cutout rate was 9.6% (95% CI, 4.6–14.7). can cause the screw to break. Therefore, the impact on Peri-implant fracture was 1.2% [21]. In our study, the the normal femoral stress conduction and stress shelter follow-up currently has not found the fracture com- are smaller in this system compared with the three cannu- plications of femoral head avascular necrosis, fracture lated screws. In the case of a tenfold amplification of the nonunion, hematomarate, and re-fracture. Among all fissure of contact surface, the three cannulated screws had patients, there was one case of screw back-out = 4 mm the larger fissure than this system had [9, 10]. The wider without the irritation of the soft tissue around the fissure with the relatively terrible contact surface of frac- plate (Fig. 4). Our results compare favorably with the ture causes serious damage to the healing of fracture. results of the Targon FN, which warrants further prospec- Consequently, the more stable fracture ends in this system tive evaluation of multicenter, large sample randomized compared with the three cannulated screws is conducive controlled clinical study. to fracture healing. Weil et al. [20] assessed femoral neck shortening after internal fixation of femoral neck fractures Limitations in 41 patients fixed with three cannulated screws in This study had several limitations involving its retro- inverted triangle configuration. He found that femoral spective nature and small sample size. Postoperative neck shortening (> 5 mm) occurred in 56% of the patients radiographs and Harris hip scores of patients were eval- and severe shortening (> 10 mm) in 22% of patients. Screw uated at different timelines. In addition, there was a lack backing out (> 5 mm) occurred in 17 (41%) patients. Seven of a control group of patients treated with three cannu- patients required late (> 6 months after primary internal lated screws. fixation) arthroplasty. In our study, only 3 cases (8.3%) had shortening < 5 mm and 1 case had screw back-out Conclusion distance = 4 mm. Dynamic compression locking system represents a reli- The design and mechanism of dynamic compression able method of fixation for femoral neck fractures. The locking system for fixing femoral neck fractures are very main prerequisite for the proper healing of femoral neck Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 7 of 8 Fig. 4 Radiograph showing slight screw back-out. A 67-year-old man fixed with dynamic compression locking system without the irritation of the soft tissue around the plate. a Preoperative X-ray. b Postoperative X-ray review at 1 day after operation. c Postoperative X-ray review at 2 months after operation. d Postoperative X-ray review at 8 months after operation. e Postoperative X-ray review at 20 months after operation fractures with this method is stable and rigid fixation. Publisher’sNote Springer Nature remains neutral with regard to jurisdictional claims in Besides, this method offers a unique sliding mechanism, published maps and institutional affiliations. allowing for controlled fracture impaction. So this way of fixation allows operated limb to have the early hip Author details Department of Orthopedic Surgery, China Resources & WISCO General functional training in optimal time. At present, dynamic Hospital, No. 209 Yejin Road, Wuhan, Hubei Province, China. Department of compression locking system is in the preliminary stage Orthopedic Surgery, Hebei Medical University, Shijiazhuang, China. of clinical application, and the follow-up effect is satis- Department of Orthopedic Surgery, Wuhan Puai Hospital affiliated to Huazhong University of Science and Technology, Wuhan, China. factory. It is worth promoting its use in clinical practice and continuing to study its clinical effect in the second Received: 31 January 2018 Accepted: 2 May 2018 stage. Acknowledgements References We thank Suzhou Orthopaedics Instrument CO. Ltd. (Suzhou, China) for 1. Rosell PA, Parker MJ. Functional outcome after hip fracture. A 1-year supporting our study in the finite element mechanics study and clinical prospective outcome study of 275 patients. Injury. 2003;34(7):529–32. study. 2. Florschutz AV, Langford JR, Haidukewych GJ, et al. Femoral neck fractures: current management. J Orthop Trauma. 2015;29(3):121–9. 3. Gjertsen JE, Engesaeter LB, Furnes O, et al. The Norwegian Hip Fracture Funding Register: experiences after the first 2 years and 15,576 reported operations. L SG receives research support from Wuhan municipal health and family Acta Orthop. 2008;79(5):583–93. planning research fund (Grant No: WX17A14). B MJ receives research support 4. Xia X, Liu Z. Advances on internal fixation treatment for femoral neck from the National Natural Science Foundation of China (Grant No: 31171136). fracture in elderly patients. Zhongguo Gu Shang. 2014;27(8):706–8. 5. Parker MJ. Results of internal fixation of Pauwels type-3 vertical femoral Availability of data and materials neck fractures. J Bone Joint Surg Am. 2009;91(2):490–1. author reply 491 The data has been entirely included in the manuscript. 6. Saglam N, Kucukdurmaz F, Kivilcim H, et al. Biomechanical comparison of antirotator compression hip screw and cannulated screw fixations in the Authors’ contributions femoral neck fractures. Acta Orthop Traumatol Turc. 2014;48(2):196–201. All authors made substantive intellectual contributions to this study to 7. Basso T. Internal fixation of fragility fractures of the femoral neck. Acta qualify as authors. XYP, SDP, LSG, and JT designed the study. An initial draft Orthop Suppl. 2015;86(361):1–36. of the manuscript was written by XYP. BMJ and KWS re-drafted parts of the 8. Zhang GZ, Wang MY, Jiang XY. Three nonparallel screws for the treatment manuscript and provided helpful advice on the final revision. All authors of femoral neck fractures. Zhongguo Gu Shang. 2012;25(12):1002–4. were involved in writing the manuscript. All authors read and approved the 9. Yang RR, Tan JF, Liu Y, et al. Biomechanical research of hollow screws and final manuscript. static locking plate with hollow lag screws for femoral neck fracture. BME Clin Med. 2016;03:225–8. 10. Yang RR. A biomechanical research of hollow screws and static locking Ethics approval and consent to participate plate with hollow screws for femoral neck fracture: Master, Hubei University The institutional review board of China Resources & WISCO General Hospital of Traditional Chinese Medicine; 2016. approved this study. 11. Aggarwal A, Singh M, Aggarwal AN, et al. Assessment of interobserver variation in Garden classification and management of fresh intracapsular Consent for publication femoral neck fracture in adults. Chin J Traumatol. 2014;17(2):99–102. Informed consents for image publication were taken from all the patients. 12. Zlowodzki M, Brink O, Switzer J, et al. The effect of shortening and varus collapse of the femoral neck on function after fixation of intracapsular Competing interests fracture of the hip: a multi-centre cohort study. J Bone Joint Surg Br. 2008; The authors declare that they have no competing interests. 90(11):1487–94. Xiao et al. 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The clinical application of a novel method of internal fixation for femoral neck fractures—dynamic locking compression system

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Abstract

Background: Femoral neck fractures are the commonly encountered injury in orthopedic practice and result in significant morbidity and mortality. Currently, how to treat femoral neck fractures safely and effectively is still a challenge. The objective of this study is to evaluate the efficiency of dynamic compression locking system for femoral neck fractures. Methods: This is a retrospective study conducted from May 2015 to October 2016. The study included 36 patients suffering from femoral neck fractures who underwent closed reduction and were fixed using dynamic compression locking system. All surgeries were performed by the same surgeon. The study was conducted by telephone and on-site follow-up. The Garden classification and anatomical site classification were categorized for all patients. We assessed radiographic outcomes of union, femoral neck shortening, screw back-out, and femoral head avascular necrosis. We also evaluated functional outcome using the Harris hip score. Other outcomes included the length of surgery, duration of hospital stay, injury to surgery time, intraoperative hemorrhage, time to clinical bone union, and other fracture complications. Results: All patients were followed up 12 to 29 months with an average of 21.58 ± 5.41 months. All cases were caused by falls including 17 males and 19 females with an average age of 65.33 ± 9.30 years old ranging from 53 to 82 years old. Among them, injury to surgery time ranged between 1 and 4 days with an average of 2.58 ± 1.05 days. Duration of hospital stay was 8 to 21 days with an average of 15.33 ± 3.71 days. Intraoperative hemorrhage was 40 to 80 ml with an average of 61.67 ± 12.31 ml. Operation time was from 35 to 80 min with average of 50.25 ± 11.77 min. According to Garden classification, 9 cases (25%) were type II and 27 cases (75%) were type III. According to the anatomical site classification, 8 cases (22.2%) were subcapital femoral neck fractures, 19 cases (52.8%) trans-cervical, and 9 cases (25%) basi-cervical. At present, the follow-up has not found the fracture complications of femoral head avascular necrosis, fracture nonunion, and re-fracture. All patients achieved solid bone union. The mean time of clinical bone union was 3 to 4 months. Among all patients, there were only 3 cases of femoral neck shortening < 5 mm and 1 case of screw back-out = 4 mm. For Harris scoring, average Harris scale at the end of the follow-up was 93.42 ± 3.95 ranging from 85 to 98. There were 32 cases of excellent function scores on the Harris scale and 4 cases of good function scores on the Harris scale. Therefore, the excellent and good rate of Harris hip scores was 100%. (Continued on next page) * Correspondence: Lsg66128@sina.com; 1310439232@qq.com Department of Orthopedic Surgery, China Resources & WISCO General Hospital, No. 209 Yejin Road, Wuhan, Hubei Province, China Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 2 of 8 (Continued from previous page) Conclusions: Femoral neck dynamic compression locking system for femoral neck fractures in elderly patients can provide effective stability and reduce complications and revision rates. Keywords: Femoral neck fractures, Internal fixation, Aged, Surgery, Locking compression plate, Background Resources & WISCO General Hospital approved this Hip fractures are the most common fragility fractures with retrospective study, and informed consents were taken the significantly reduced limb function and the markedly de- from all the patients. This study assessed patients with creased quality of life after injuries. The number of hip frac- femoral neck fractures who underwent fixation with dy- tures per annual worldwide is expected to rise to 2.6 million namic compression locking system (Suzhou Orthopaedics by 2025 and 4.5 million by 2050 [1]. Use of the Garden Instrument CO. Ltd., Suzhou, China) from May 2015 to and anatomical site classification systems has remained the October 2016. In total, all patients were included and clinical mainstay of femoral neck fracture characterization anteroposterior and axial femoral beck radiographs were which help demonstrate appropriate treatment. Operative obtained on first admission following falls. All fracture options include in situ fixation, closed or open reduction patterns were recorded according to the Garden and ana- with internal fixation, and hip arthroplasty [2]. tomical site classification systems. As a matter of fact, femoral neck fractures are the most All surgeries were performed by the first surgeon. The common hip fractures, accounting for approximately 57% study was conducted by telephone and on-site follow- of all hip fractures [3]. At present, three hollow screws are up. We assessed radiographic outcomes of union, fem- often used for the internal fixation of femoral neck fractures oral neck shortening, screw back-out, and femoral head [4]. It can compress fracture ends, but three hollow screws avascular necrosis. Regarding the outcome of femoral are not interrelated to form a framework structure. More- neck avascular necrosis, we only assessed the radio- over, the positions of three hollow screws are subjectively graphic outcomes of the patients having at least 18 or influenced by the surgeons. The rotational resistance and 24 months postoperatively. We also evaluated functional vertical shear resistance were poor in some studies [5–7]. outcome using the Harris hip scores. Other outcomes Moreover, loosening of internal fixation, displacement of included the length of surgery, duration of hospital stay, femoral head, and femoral neck nonunion usually happened injury to surgery time, intraoperative hemorrhage, time [8]. During the healing process, lack of effective continuous to clinical bone union, and other fracture complications. locking support can lead to the shortening of the femoral The inclusion criteria were as follows: (1) neck of neck [5–7]. Femoral neck dynamic compression locking sys- femur fracture, (2) > 50 years old, (3) closed fractures, tem is a new type of internal fixation for femoral neck frac- (4) the type II and III fractures of the Garden classifica- tures and was designed based on the three-dimensional tion, and (5) fractures caused by falling down. Patients anatomical structure of femoral neck. According to the fem- who met the above criteria were included in this study. oral neck scalene triangle juga structure, the three parallel The exclusion criteria were as follows: (1) concomitant screws are located on the three jugas, respectively, which ipsilateral femoral shaft fractures, (2) pathological frac- are close to the bone cortex [9]. Then, three parallel screws tures, (3) stress fractures, (4) the type I and IV of the and a lateral pressure locking plate through three locking Garden classification, and (5) < 50 years old. tail caps integrate into a whole, which forms the stable In this study, 36 cases with femoral neck fractures structure of framework and can precisely and uniformly were caused by falls including 17 males and 19 females, compress and lock fracture ends with the favorable rota- with an average age of 65.33 ± 9.30 years old ranging tional stability and rigid fixation [10]. This implant was between 53 and 82 years old (Fig. 1). Among them, pproved by China medical device regulations (Chinese injury to surgery time was 1 to 4 days with an average of patent no.: ZL201410458654.9). 2.58 ± 1.05 days. Duration of hospital stay was 8 to Therefore, we retrospectively analyzed patients with 21 days with an average of 15.33 ± 3.71 days. Intraopera- femoral neck fractures who were treated with dynamic tive hemorrhage was 40 to 80 ml with an average of compression locking system between May 2015 to October 61.67 ± 12.31 ml. Operation time was 35 to 80 min with 2016 to evaluate the effectiveness, stability, and complica- an average of 50.25 ± 11.77 min. According to the Garden tions of the dynamic compression locking system. classification standards, type II fractures were seen in 9 cases and type III 27 cases. According to the anatom- Methods ical site classification, subcapital femoral neck fractures The methodology of our study is a single-center, retro- were found in 8 cases, trans-cervical fractures of femur spective study. The institutional review board of China 19 cases, and femoral neck basal fractures 9 cases. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 3 of 8 Fig. 1 A 54-year-old man with a displaced left femoral neck fracture fixed with dynamic compression locking system. a Preoperative X-ray. b Postoperative X-ray review at 2 days after operation. c Postoperative X-ray review at 1 month after operation. d Postoperative X-ray review at 4.5 months after operation. e Postoperative X-ray review at 18.5 months after operation Of the patients, 16.7% had diabetes mellitus, 44.4% extorsion of axial traction were conducted and until had hypertension, 33.3% had ischemic heart disease or a closed reduction of the fracture ends was satisfied with previous cerebrovascular event, 22.2% had pulmonary the dynamic monitoring of anteroposterior and axial diseases, and 27.8% had hyperlipidemia. radiographs. Then, surgeon can roll the three parallel guide needles into femoral head within 5 mm of the Surgical procedure subchondral bone of the femoral head. The required After anesthesia involving a continuous epidural or lengths of the needles were measured to guarantee the lumbar anesthesia, the patients were supine with the satisfying location of the screw placement. All three contralateral leg flexed at 90° to enable visualization of screws were positioned within 5 mm of the subchon- the fracture. Then, routine disinfection and sterile dral bone of the femoral head. Finally, surgeon rolled draping of the hip and lower extremities was carried three parallel hollow locking compression screws out. The lateral minimal incision over the greater tro- through the direction of the three guide needles chanter of the femur was performed with a 4–5-cm in- respectively into the neck of femur. At the end of tight- cision length, then the superficial and deep fascial ening screws, three parallel screws(7 mm) should be layers and muscles were isolated sequentially, and the uniformly and accurately compressed. When the intra- lateral cortex of the large tuberosity of the femur was operative radiographs suggested that compression fix- exposed to 6–7 cm length. One or two extracorporeal ation of the fracture ends was satisfying, the tail caps guide needles were placed on the hip. The position of were tightened into the end of the three screws. In the the extracorporeal guide needle was adjusted until the end, sealing the incision layer-by-layer should be pru- needle was parallel to the longitudinal axis of the fem- dentially conducted (Fig. 2). oral neck. According to the direction of the extracor- poreal guide needle, surgeon can insert the top guide Postoperative management needle into the anterior and superior position of the Postoperatively, patients were discharged 1–3 week after greater trochanter of the femur with the continuing surgery. Patients with ischemic heart disease or a previ- monitor of C-arm radiographs. And then along the top ous cerebrovascular event were treated with anticoagu- guide needle, surgeon can install locking plate that had lants for 14 days. A wound check was observed by 2- to installed guide needle sleeve in the greater trochanter 3-day intervals till the removing of the suture 2 weeks of the femur. In the direction of the guide sleeve, sur- after surgery. Follow-up by X-ray is done at 1 week after geon can place the other two parallel guide needles surgery and monthly intervals till complete union was along the direction of the top guide needle into distal achieved, then at 6 months’ intervals till final follow-up. fracture end, and finally the three parallel guide needles Hip range was encouraged as soon as tolerated by the construct an scalene triangle. A closed reduction of patient (usually few days after surgery); partial weight femoral neck fracture was observed with the monitor of bearing was started when tolerated by patients. Full C-arm fluoroscopy. To the Garden III fractures [11], weight bearing was allowed only when full union was ahead of adduction and internal rotation, outreach and achieved. Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 4 of 8 Fig. 2 Surgical procedure of the dynamic compression locking system for femoral neck fracture was conducted by the same surgeon. a Placement of extracorporal guide needles. b Insert the top guide needle into the femoral neck along the direction of the extracorporal guide needles. c Install the guide sleeve and insert two other guide needles along the direction of the top guide needle. d After the fracture reduction by closed reduction, the top guide needle was transferred to the femoral head to maintain the repositioned position. e Insert three hollow parallel compression screws along the direction of the guide needles. f Pressure screws evenly and accurately All patients were followed up for at least 1 years post- complications including deep vein thrombosis, pulmonary operatively. Close follow-up at our outpatient depart- embolism, urinary tract infection, wound hematoma, and ment included radiographs of the femoral neck to assess bleeding gastrointestinal tract probably due to the effect fracture healing and the recording of functional out- of early straight leg raising training on postoperative re- comes using the Harris hip scores. All outcomes of habilitation of patients (usually 2 to 3 days after surgery). patients were assessed by two blinded observers. Discussion Results After femoral neck fractures, no matter what type of No patients had died within the last follow-up. All treatment is chosen, it will have a significant impact on patients were followed up about 12 to 29 months with the quality of patients’ life and bring a great economic an average of 21.58 ± 5.41 months. At present, the burden to the society [4]. Compared with hip joint follow-up has not found the fracture complications of replacement, internal fixation surgery, because of its femoral head avascular necrosis, fracture nonunion, and smaller trauma, shorter operation time, less bleeding, re-fracture. There were no reoperation and hip joint lower incidence of postoperative complications and early contracture and difficulty within the final follow-up. All mortality, and lower cost, has become the main treat- patients achieved solid bone union. The time to bone ment of femoral neck fractures clinically [4]. However, union was 3 to 4 months. Among all patients, we used there is still lack of a consistent view of what methods of the method adopted by Zlowodzki [12] to evaluate femoral internal fixation can better maintain the stability of frac- neck shortening and we found that only 3 cases (8.3%) had ture ends, promote fracture healing, and avoid or reduce shortening < 5 mm and were considered as non/mild. Only the complications such as postoperative femoral head 1 case screw back-out distance was 4 mm. For Harris scor- avascular necrosis and internal fixation failures [14]. ing [13], average Harris scale at the final follow-up was In our study, longer duration of hospital stay was asso- 93.42 ± 3.95 ranging from 85 to 98.According to the func- ciated with the presence of ischemic heart disease, cere- tion score of Harris hip, the score of 90–100 is divided into brovascular accident, and pulmonary disease, as these excellent, 80–89 is divided into good, 70–79 is fair, and 70 patients needed to be optimized before discharge. None- points below is poor. There were 32 cases of excellent func- theless, advanced age did not significantly affect the tion score of Harris hip and 4 cases of good function score. duration of hospital stay. In other studies, duration of Of the latter, 3 cases had femoral neck shortening < 5 mm. hospital stay was affected by the number of comor- Therefore, the excellent and good rate of the Harris bidities but not advanced age [15]. The lateral min- hip scores was 100%. There were no perioperative imal incision over the greater trochanter of the femur Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 5 of 8 was performed with a 4–5-cm incision length. Therefore, system (Fig. 3). This system can not only improve the smaller trauma with a smaller amount of blood loss precision and uniform pressure of fracture ends, but can effectively reduce soft tissue exposure and ultim- also have a stable framework structure to lock fracture ately benefits fracture healing. Surgery was performed ends. Moreover, the system is capable of compressing early (an average of 2.58 ± 1.05 days after injury) in fracture ends dynamically [10]. And ultimately, the ends our hospital to reduce the complications associated of the fracture can obtain good short- and long-term with post-fracture bedridden, thereby increasing the fixation, and the rigid fixation ultimately is conducive to surgical tolerability. Moreover, early hip joint function fracture healing. Early biomechanical studies have found exercise after operation effectively reduced postoperative that the finite element analysis of this system in the complications. As a result, perioperative complications did cadaver model was close to the biomechanical conduc- not occur in this study. Our study shows lesser incidence tion of the normal femoral neck with no stress occlusion of perioperative complications compared with other [10], so this system is conducive to the growth and heal- studies [16]. ing of bone scabs in the fracture area. Currently, the Our researchers used computed tomography tech- follow-up has not found the fracture complications of nique to study the anatomical features of femoral neck. femoral head avascular necrosis, fracture nonunion, and The analysis of femoral neck structure using 3D imaging re-fracture. There were no reoperation and hip joint and the cross-section computer software revealed that contracture and difficulty at the final follow-up. All the cross-section of femur neck was an scalene triangle patients achieved solid bone union. But, 3 cases (8.3%) configuration [9]. “Femoral neck safety cross section” had femoral neck shortening < 5 mm and 1 case had was obtained by the cross-section computer software, screw back-out distance = 4 mm, which was associated so the scalene triangular distribution of three screws with severe osteoporosis or sequela of cerebral infarction. in femur neck was developed. The three parallel screws In our study, all patients with femoral neck fractures were are located in the three jugas of the scalene triangle con- caused by falls with good preoperative mobility. So no figuration and are close to the bony cortex, which are patients had died within the final follow-up. Other excellent in biological stability [10]. A lateral locking plate studies reported that the mortality rate was associated and three interlocking tail caps are used to interlink three with preoperative mobility, and preoperative mobility hollow compression screws into a whole to provide rigid was considered the most significant determinant for fixation, which constitutes a dynamic compression locking postoperative survival [16]. Fig. 3 The composition of the dynamic compression locking system and the inverted triangular structure or triangle juga structure of femoral neck obtained by the cadaver model or the cross-section computer software Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 6 of 8 The most commonly internal fixation for fixing femoral similar to these of the Targon FN implant, both of which neck fractures is three cancellous screws [4, 7, 8, 16]. Re- provide an angular and rotator stable construct and offer cent studies described different techniques for divergent a unique sliding mechanism, allowing for controlled screw fixation of neck of femur fractures with the different fracture impaction. However, the Targon FN implant is distribution and direction of the screws in femoral neck combined with two distal locking screws, which can [4, 7, 8, 16]. The rotation stability of the three cancellous improve rotational and angular stability, but weaken screws was relatively variable, and ultimately, the instabil- the ability of sliding compressive mechanism [21]. ity of fracture ends in some studies often adversely influ- Nishiyama et al. [22] indicated that a sliding mechanism enced the fracture healing [17–19]. However, the allowing linear intraoperative and postoperative com- distribution of the three interlocking compression screws pression on the treatment of femoral neck fractures facil- of this system in femoral head position was according to itated fracture healing. The Targon FN is designed to the principle of anatomy and biomechanics of the femoral give a better rotational and angular stability than other neck. One is located in the anterior and inferior part of contemporary internal fixation devices used for femoral the femoral neck with longitudinal pressure, another one neck fractures [21]. Osarumwense et al. [23] showed that sits in the anterior superior tension side of the femoral the results of the Targon FN system for the management neck, and the last one is in the rear and slightly inferior of intracapsular neck of femur fractures in a study with position of the femoral neck. The fixed positions of the minimum 2-year experience and outcome were superior screws are the position in femoral neck with the highest to those then found in the literature for the more trad- bone density [9]. This system provides rigid fixation so itional fixation methods. Nonunion rates are reported to that the anti-rotation resistance is significantly enhanced. range between 2.2 and 2.7% after undisplaced fractures The finite element mechanics analysis of this system and and even 2.2 and 15.4% after displaced fractures [24–26]. the three cannulated screws for femoral neck fractures in Several studies reported a rate of 4–5.5% of avascular the cadaver model suggested that the maximum stress of necrosis after Targon FN fixation of undisplaced frac- the three screws was greater in the three cannulated tures and 4–13.8% after displaced fractures [21, 27]. screws than in this system (138.9 vs. 57.49 MPa) [9, 10]. Parker and Takigawa et al. [21, 27] reported elective The contact pressure of fracture surface was higher in the implant removal in 10.9% after undisplaced fractures three cannulated screw model than in this system model and in 6.4–48.3% after displaced fractures, also mainly (46.9 vs. 22.58 MPa) [9, 10]. Moreover, the three screws in due to discomfort. Besides, Biber et al. [24]reported the femur were more stressed in the three cannulated that hematomarate of the internal fixation for femoral screw model than in this system model. The greater the neck fracture fixed by Targon FN was 4.4% (95% CI, stress value, the greater the damage to the screws, which 0.9–8.0) and cutout rate was 9.6% (95% CI, 4.6–14.7). can cause the screw to break. Therefore, the impact on Peri-implant fracture was 1.2% [21]. In our study, the the normal femoral stress conduction and stress shelter follow-up currently has not found the fracture com- are smaller in this system compared with the three cannu- plications of femoral head avascular necrosis, fracture lated screws. In the case of a tenfold amplification of the nonunion, hematomarate, and re-fracture. Among all fissure of contact surface, the three cannulated screws had patients, there was one case of screw back-out = 4 mm the larger fissure than this system had [9, 10]. The wider without the irritation of the soft tissue around the fissure with the relatively terrible contact surface of frac- plate (Fig. 4). Our results compare favorably with the ture causes serious damage to the healing of fracture. results of the Targon FN, which warrants further prospec- Consequently, the more stable fracture ends in this system tive evaluation of multicenter, large sample randomized compared with the three cannulated screws is conducive controlled clinical study. to fracture healing. Weil et al. [20] assessed femoral neck shortening after internal fixation of femoral neck fractures Limitations in 41 patients fixed with three cannulated screws in This study had several limitations involving its retro- inverted triangle configuration. He found that femoral spective nature and small sample size. Postoperative neck shortening (> 5 mm) occurred in 56% of the patients radiographs and Harris hip scores of patients were eval- and severe shortening (> 10 mm) in 22% of patients. Screw uated at different timelines. In addition, there was a lack backing out (> 5 mm) occurred in 17 (41%) patients. Seven of a control group of patients treated with three cannu- patients required late (> 6 months after primary internal lated screws. fixation) arthroplasty. In our study, only 3 cases (8.3%) had shortening < 5 mm and 1 case had screw back-out Conclusion distance = 4 mm. Dynamic compression locking system represents a reli- The design and mechanism of dynamic compression able method of fixation for femoral neck fractures. The locking system for fixing femoral neck fractures are very main prerequisite for the proper healing of femoral neck Xiao et al. Journal of Orthopaedic Surgery and Research (2018) 13:131 Page 7 of 8 Fig. 4 Radiograph showing slight screw back-out. A 67-year-old man fixed with dynamic compression locking system without the irritation of the soft tissue around the plate. a Preoperative X-ray. b Postoperative X-ray review at 1 day after operation. c Postoperative X-ray review at 2 months after operation. d Postoperative X-ray review at 8 months after operation. e Postoperative X-ray review at 20 months after operation fractures with this method is stable and rigid fixation. Publisher’sNote Springer Nature remains neutral with regard to jurisdictional claims in Besides, this method offers a unique sliding mechanism, published maps and institutional affiliations. allowing for controlled fracture impaction. So this way of fixation allows operated limb to have the early hip Author details Department of Orthopedic Surgery, China Resources & WISCO General functional training in optimal time. At present, dynamic Hospital, No. 209 Yejin Road, Wuhan, Hubei Province, China. Department of compression locking system is in the preliminary stage Orthopedic Surgery, Hebei Medical University, Shijiazhuang, China. of clinical application, and the follow-up effect is satis- Department of Orthopedic Surgery, Wuhan Puai Hospital affiliated to Huazhong University of Science and Technology, Wuhan, China. factory. It is worth promoting its use in clinical practice and continuing to study its clinical effect in the second Received: 31 January 2018 Accepted: 2 May 2018 stage. Acknowledgements References We thank Suzhou Orthopaedics Instrument CO. Ltd. (Suzhou, China) for 1. Rosell PA, Parker MJ. Functional outcome after hip fracture. A 1-year supporting our study in the finite element mechanics study and clinical prospective outcome study of 275 patients. Injury. 2003;34(7):529–32. study. 2. Florschutz AV, Langford JR, Haidukewych GJ, et al. Femoral neck fractures: current management. J Orthop Trauma. 2015;29(3):121–9. 3. Gjertsen JE, Engesaeter LB, Furnes O, et al. The Norwegian Hip Fracture Funding Register: experiences after the first 2 years and 15,576 reported operations. L SG receives research support from Wuhan municipal health and family Acta Orthop. 2008;79(5):583–93. planning research fund (Grant No: WX17A14). B MJ receives research support 4. Xia X, Liu Z. Advances on internal fixation treatment for femoral neck from the National Natural Science Foundation of China (Grant No: 31171136). fracture in elderly patients. Zhongguo Gu Shang. 2014;27(8):706–8. 5. Parker MJ. Results of internal fixation of Pauwels type-3 vertical femoral Availability of data and materials neck fractures. J Bone Joint Surg Am. 2009;91(2):490–1. author reply 491 The data has been entirely included in the manuscript. 6. Saglam N, Kucukdurmaz F, Kivilcim H, et al. Biomechanical comparison of antirotator compression hip screw and cannulated screw fixations in the Authors’ contributions femoral neck fractures. Acta Orthop Traumatol Turc. 2014;48(2):196–201. All authors made substantive intellectual contributions to this study to 7. Basso T. Internal fixation of fragility fractures of the femoral neck. Acta qualify as authors. XYP, SDP, LSG, and JT designed the study. An initial draft Orthop Suppl. 2015;86(361):1–36. of the manuscript was written by XYP. BMJ and KWS re-drafted parts of the 8. Zhang GZ, Wang MY, Jiang XY. Three nonparallel screws for the treatment manuscript and provided helpful advice on the final revision. All authors of femoral neck fractures. Zhongguo Gu Shang. 2012;25(12):1002–4. were involved in writing the manuscript. All authors read and approved the 9. Yang RR, Tan JF, Liu Y, et al. Biomechanical research of hollow screws and final manuscript. static locking plate with hollow lag screws for femoral neck fracture. BME Clin Med. 2016;03:225–8. 10. Yang RR. A biomechanical research of hollow screws and static locking Ethics approval and consent to participate plate with hollow screws for femoral neck fracture: Master, Hubei University The institutional review board of China Resources & WISCO General Hospital of Traditional Chinese Medicine; 2016. approved this study. 11. Aggarwal A, Singh M, Aggarwal AN, et al. Assessment of interobserver variation in Garden classification and management of fresh intracapsular Consent for publication femoral neck fracture in adults. Chin J Traumatol. 2014;17(2):99–102. Informed consents for image publication were taken from all the patients. 12. Zlowodzki M, Brink O, Switzer J, et al. The effect of shortening and varus collapse of the femoral neck on function after fixation of intracapsular Competing interests fracture of the hip: a multi-centre cohort study. J Bone Joint Surg Br. 2008; The authors declare that they have no competing interests. 90(11):1487–94. Xiao et al. 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Osarumwense D, Tissingh E, Wartenberg K, et al. The Targon FN system for the management of intracapsular neck of femur fractures: minimum 2-year experience and outcome in an independent hospital. Clin Orthop Surg. 2015;7(1):22–8. 24. Biber R, Brem M, Bail HJ. Targon Femoral Neck for femoral-neck fracture fixation: lessons learnt from a series of one hundred and thirty five consecutive cases. Int Orthop. 2014;38(3):595–9. 25. Akcay S, Satoglu IS, Kazimoglu C. Osteosynthesis of unstable intracapsular femoral neck fracture by dynamic locking plate or screw fixation: early results. J Orthop Trauma. 2014;28(8):e208–9. 26. Brandt E, Verdonschot N. Biomechanical analysis of the sliding hip screw, cannulated screws and Targon1 FN in intracapsular hip fractures in cadaver femora. Injury. 2011;42(2):183–7. 27. Parker MJ, Blundell C. Choice of implant for internal fixation of femoral neck fractures. Meta-analysis of 25 randomised trials including 4,925 patients. Acta Orthop Scand. 1998;69(2):138–43.

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Journal of Orthopaedic Surgery and ResearchSpringer Journals

Published: May 31, 2018

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