| Objective:As a common clinical fracture, there are quite many internal fixation methods for distal femoral fracture. With the rapid development and application of new biological fracture fixation techniques and specific implants in the distal femur fracture surgery, retrograde intramedullary nailing has gained wide clinical application and continuous improvement with its unparalleled advantages in anatomical reduction, stability, early weight bearing and shortening of hospital stay. Since intramedullary nailing generally adopts closed reduction and minimally invasive procedures, incision is required to be as small as possible intraoperatively. Moreover, there are abundant soft tissues around the knee joints, so the position and direction of distal femoral nail entrance are often difficult to be determined intraoperatively. Quite many complications occur during clinical applications because the position and orientation of distal femoral nail entrance are difficult to be determined accurately during surgery due to distal femoral swelling and thick medullary cavity. Conventional approaches empirically determine the entry point, which are largely affected by subjective factors, and prone to error, resulting in disorders of biomechanical relationship between the distal femur and femoral shaft; over time, limb deformities, fixation failure or even fixation breakage will be highly possible, affecting the everyday life of patients. The aim of this study is to precisely determine the nail entry point based on the anatomical structure of distal femur, in order to more effectively guide clinical surgical procedures. To be specific, the entry point of retrograde intramedullary nail is determined by assessing the femoral longitudinal axis, femoral intercondylar notch tangent line and relationship between the two lines and distal femoral articular surface intersection point under fluoroscopy.Methods:30 standard frontal and lateral distal femoral fracture x-ray images of normal adults of different genders and ages are selected, the longitudinal axis of femur, tangent line of femoral intercondylar notch and distance between the two lines and distal femoral articular surface intersection point are measured using x-ray image measurement software. Each case is measured five times and averaged, and standard value is calculated to be x. Then,30 cases of distal femoral fractures treated by intramedullary nail fixation using traditional experience and improved closed reduction at Cangzhou Hospital of Integrated Traditional and Western Medicine in Hebei between May 2012 to February 2014 are selected, these 30 patients are divided into two groups. Group 1 consists of 15 patients who underwent intramedullary nail fixation using conventional approach. They are 11 males 4 females, who aged 17-60 years, with a mean age of (38.5±14.0) years.12 cases are traffic accidents,2 cases are fall down injuries, and 1 case is falling injury. AO/OTA classification:11 cases of type A fractures, including 5 cases of type A1,2 cases of type A2, and 2 cases of type A3 fractures.3 cases of type C’fractures, including 2 cases of type C1, and 1 case of type C2 fractures. 1 case of open fracture. Group 2 underwent intramedullary nail fixation after angle measurement using improved approach. They are 9 males 6 females, who aged 19-63 years, with a mean age of (40.0±13.9) years.11 cases are traffic accidents,3 cases are fall down injuries, and 1 case is falling injury. AO/OTA classification:12 cases of type A fractures, including 6 cases of type Al,2 cases of type A2, and 2 cases of type A3 fractures.3 cases of type C fractures, including 2 cases of type C1, and 1 case of type C2 fractures.Lateral distal femoral images of different ages are taken with a "C" arm X-ray system intraoperatively. The length of connecting line (C line) between the two and articular surface intersection point is determined based on the femoral longitudinal axis and femoral intercondylar notch tangent line (blumensaat line), and the length of connecting line (c line) between the lines and distal femoral articular surface intersection point is statistically analyzed. That is, opening position is determined within x range in front of blumensaat line (not exceeding femoral lateral axis) during lateral femoral fluoroscopy. Frontal opening uses traditional opening position, i.e. femoral intercondyle.Result:The length of connecting line (c line) between femoral longitudinal axis and distal femoral articular surface intersection point, and between blumensaat line and distal femoral articular surface intersection point are measured to be 11.96 mm±2.30 mm in normal adults. That is, opening position does not exceed femoral axis within an 11.96 mm ±2.30 mm range in front of blumensaat line during lateral femoral fluoroscopy (Table 4). Localization of retrograde femoral nail opening position is guided using this data during surgery.30 patients are followed up for 6-21 months postoperatively, with a mean of 13.4 months. In the conventional retrograde interlocking intramedullary nailing group, operative time is 95-130 min, with a mean of (111.6 ± 10.6) min. Intraoperative blood loss is 300-600 ml, with a mean of (450 ± 91.6) ml. Intraoperative fluoroscopy times is 8-16 times, with a mean of (12.5±2.6) times. Postoperative limb shortening is 6-16 mm, with a mean of (8.7±4.5) mm; and knee flexion is 80-130°, with a mean of (99.7± 13.4)°. Fracture healing time is 12-32. weeks, with a mean of (25.5±6.7) weeks. According to Kolment rating system,7 cases are excellent,4 cases are good,3 cases are average and 1 case poor; excellent and good rate is 73%. No infection, bone nonunion, deep vein thrombosis of lower limbs or other complications is found. In the improved retrograde interlocking intramedullary nailing group, operative time is 70-110 min, with a mean of (81.3±12.1) min. Intraoperative blood loss is 240-610 ml, with a mean of (355.3±103.1) ml. Intraoperative fluoroscopy times is 5-12 times, with a mean of (7.8±2.0) times. Postoperative limb shortening is 6-16 mm, with a mean of (7.7±4.3) mm; and knee flexion is 90-140°, with a mean of (120±13.8)°. Fracture healing time is 12-31 weeks, with a mean of (21.4±7.2) weeks.Conclusion:1 Before surgery, the accuracy of x-ray imaging localization of bone landmark line is improved by measuring distal femoral anatomical data of normal individuals of different ages and genders, and full utilization of this data, in order to provide reference for clinical practice.2 During surgical procedure, the area between the femoral longitudinal axis and distal femoral articular surface intersection point and the blumensaat line and distal femoral articular surface intersection point is determined as the marker using the above statistical data. And the opening position of femoral retrograde intramedullary nailing is determined using this marker. Compared with the conventional approach group, this approach significantly shortens operative time, reduces intraoperative blood loss and fluoroscopy times, and improves postoperative knee flexion angle, fully illustrating its important significance to the alleviation of suffering of patients and reduction of radiation harm to surgeons and patients. Besides, it also has certain clinical guiding significance and value.3 Compared with conventional surgical approach, fracture healing time and limb shortening deformity are improved for patients underwent the above improved surgery although no significant differences are found. Moreover, as the improved approach is closer to the physiological and biomechanical characteristics of human, it can firmly and effectively control the rearward and rotational displacements of fracture distal ends, thereby better restoring and maintaining the axis of the femur, laying a solid foundation for prognostic functional recovery, which is worthy of widespread clinical application.4 Limitation of this study is small sample size. Further large-sample prospective study in clinical applications is needed to verify its effectiveness. |
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