ObjectiveTo design and produce a lesser trochanteric reduction fixation system and verify its value and effectiveness. MethodsA lesser trochanteric reduction fixation system was designed and produced according to the anatomical features of the lesser trochanteric fractures. Sixty-six patients with intertrochanteric fractures of Evans type Ⅲ were included between January 2010 and July 2012. Of 66 patients, 32 were treated with dynamic hip screw (DHS) assisted with the lesser trochanteric reduction fixation system (study group), and 34 cases were treated with DHS only (control group). The 2 groups were comparable with no significant difference in gender, age, the reasons, and the types of the fractures (P>0.05). The operation time, intraoperative blood loss, neck-shaft angle, bone healing time, ratio of successful fixations, and the functional evaluation of the hip joint after operation were compared between 2 groups. ResultsThe study group had shorter operation time [(58.4±5.3) minutes] and less intraoperative blood loss [(186.3±6.6) mL] than the control group[(78.5±6.2)minutes and (246.2±8.7) mL], showing significant differences (t=-14.040, P=0.000; t=-31.145, P=0.000). There was no significant difference in neck-shaft angle between study group [(138.6±3.0)°] and control group [(139.4±2.9)°] (t=-1.044, P=0.301). The wounds healed by first intention in both groups. The 30 and 31 patients were followed up 12 to 24 months (mean, 15 months) in the study group, and 13 to 25 months (mean, 16 months) in the control group, respectively. All fractures healed well in 2 groups. The study group had significantly shorter healing time [(8.8±2.0) weeks] than the control group [(10.7±3.4) weeks] (t=-2.871, P=0.006). At 12 months after operation, coxa vara happened in 2 cases of the study group with a successful fixation ratio of 93.3% and in 10 cases of the control group with a successful fixation ratio of 67.7%, showing significant difference (χ2=6.319, P=0.022). According to Harris hip score, the excellent and good rate was 83.3% in the study group (25/30) and was 58.1% in the control group (18/31), showing significant difference (χ2=4.680, P=0.049). ConclusionThe application of the lesser trochanteric reduction fixation system can reduce stripping of the soft tissue around the fracture fragments, shorten the operation time and the healing time, and preserve the function of the hip joint maximumly.
ObjectiveTo determine the entry point and screw implant technique in posterior pedicle screw fixation by anatomical measurement of adult dry samples of the axis so as to provide a accurate anatomic foundation for clinical application. MethodsA total of 60 dry adult axis specimens were selected for pedicle screws fixation. The entry point was 1-2 mm lateral to the crossing point of two lines: a vertical line through the midpoint of distance from the junction of pedicle medial and lateral border to lateral mass, and a horizontal line through the junction between the lateral border of inferior articular process and the posterior branch of transverse process. The pedicle screw was inserted at the entry point. The measurement of the anatomic parameters included the height and width of pedicle, the maximum length of the screw path, the minimum distance from screw path to spinal canal and transverse foramen, and the angle of pedicle screw. The data above were provided to determine the surgical feasibility and screw safety. ResultsThe width of upper, middle, and lower parts of the pedicle was (7.35±0.89), (5.50±1.48), and (3.97±1.01) mm respectively. The pedicle height was (9.94±1.16) mm and maximum length of the screw path was (25.91±1.15) mm. The angle between pedicle screw and coronal plane was (26.95±1.88)° and the angle between pedicle screw and transverse plane was (22.81±1.61)°. The minimum distance from screw path to spinal canal and transverse foramen was (2.72±0.83) mm and (1.98±0.26) mm respectively. ConclusionAccording to the anatomic research, a safe entry point for C2 pedicle screw fixation is determined according to the midpoint of distance from the junction of pedicle medial and lateral border to lateral mass, as well as the junction between the lateral border of inferior articular process and the posterior branch of transverse process, which is confirmed to be effectively and safely performed using the entry point and screw angle of the present study.
ObjectiveTo compare the fixation strength of optimum placed pedicle screw (OS) with re-directionally correctly placed pedicle screw (RS) following a violation of lateral pedicle. MethodsThirty fresh lumbar vertebrae (L1-5) were obtained from 6 pigs weighing 95-105 kg, male or female. Each vertebra was instrumented with a monoaxial pedicle screw into each pedicle using two different techniques. On one side, a perfect screw path was created using direct visualization and fluoroscopy. A pedicle screw of 5 mm in diameter and 35 mm in length was placed with a digital torque driver (OS). On the other side, a lateral pedicle wall violation was created at the pedicle-vertebral body junction with a guide wire, a cannulated tap, and a pedicle probe. This path was then redirected into a correct position, developed, and instrumented with a 5-mm-diameter by 35-mm-long pedicle screw (RS). For each pedicle screw, the maximal torque, seating torque, screw loosening force, and post-loosening axial pullout were measured. Screw loosening and axial pullout were assessed using an MTS machine. ResultsMaximal insertion torque was (111.4±8.2) N·cm and (78.9±6.4) N·cm for OS and RS respectively, showing significant difference (Z=3.038, P=0.002). The seating torque was (86.3±7.7) N·cm and (59.7±5.3) N·cm for OS and RS respectively, showing significant difference (Z=2.802, P=0.005). The screw loosening force was (76.3±6.2) N and (53.0±5.8) N for OS and RS respectively, showing significant difference (Z=2.861, P=0.004). The post-loosening axial pullout force was (343.0±12.6) N and (287.0±10.5) N for OS and RS respectively, showing significant difference (Z=2.964, P=0.003). ConclusionCompared with OS, RS placement after a lateral wall violation shows significantly decreased maximal insertion torque, seating torque, screw loosening force, and post-loosening axial pullout. On this occasion, RS augmentation is a probable option for remediation.
Objective To investigate the feasibility and effectiveness of absorbable screws for the treatment of tibiofibular syndesmotic disruptions by comparing with metallic screws. Methods Between July 2007 and May 2012, 69 patients with tibiofibular syndesmotic disruptions associated with ankle fractures were treated; absorbable screw fixation was used in 38 cases (group A) and metallic screw fixation was used in 31 cases (group B). There was no significant difference in gender, age, injury causes, the type of fracture, the side of fracture, and disease duration between 2 groups (P gt; 0.05). The fracture healing time, weight bearing time, and complications were recorded and compared between 2 groups. According to Baird-Jackson scoring system, the function of the ankle was assessed after 6 months. Results Infection of incision occurred in 3 cases (7.9%) of group A and 2 cases (6.5%) of group B, and skin necrosis of incision in 1 case (2.6%) of group A and 5 cases (16.1%) of group B, showing no significant difference in the incidences of infection and necrosis of incisions between 2 groups (P gt; 0.05); primary healing of incision was obtained in the other patients. The 69 cases were followed up 12-26 months (mean, 18.6 months). The weight bearing time was (2.97 ± 0.59) months in group A and was (3.16 ± 0.74 ) months in group B, showing no significant difference (t=1.175, P=0.244). X-ray films showed that fractures and tibiofibular syndesmotic disruptions healed in 2 groups; the healing time was (5.71 ± 1.01) months in group A and was (5.81 ± 1.08) months in group B, showing no significant difference (t=0.381, P=0.705). No fixation failure, breakage, or loosening occurred in 2 groups. According to Baird-Jackson scoring system, the results were excellent in 29 cases, good in 5 cases, and fair in 4 cases with an excellent and good rate of 89.5% in group A at 6 months after operation; the results were excellent in 20 cases, good in 7 cases, and fair in 4 cases with an excellent and good rate of 87.1% in group B; no significant difference was found in the excellent and good rate between 2 groups (Z= — 0.991, P=0.321). Conclusion Treatment of tibiofibular syndesmotic disruptions with absorbable screws can get good effectiveness and replace metallic screws because of avoiding additional operation for removing the screw.
Objective To investigate the effect of the penetration of mini-plate mass screws into facet joint on axial symptoms in cervical laminoplasty. Methods A retrospective analysis was made on the clinical data of 52 patients who underwent unilateral open-door cervical expansive laminoplasty fixed with Centerpiece mini-plate between September 2009 and December 2011. There were 42 males and 10 females, with a mean age of 61.2 years (range, 34-83 years). Seventeen patients exhibited simple degeneration cervical canal stenosis, 25 patients had multilevel cervical disc protrusion, and 10 patients had ossification of posterior longitudinal ligaments. Disease duration ranged 1-120 months (median, 11 months). The Japanese Orthopedic Association (JOA) score was used to assess neurological function, and JOA recovery rates were calculated. The visual analogue score (VAS) and the neck disability index (NDI) were used to evaluate the axial pain and neck daily activities. The axial symptoms and other complications were recorded. The cervical canal diameter, cervical curvature, cervical canal cross area, and open angle were measured according to the X-ray films, CT scans, and MRI scans. The postoperative CT three dimensional (3-D) reconstruction images were used to identify whether the screws penetrated into the facet joints. All the patients were divided into 3 groups according to involved facet joints: no joint penetrating group (no penetrated facet joint), oligo-joint penetrating group (one or two penetrated facet joints), and multi-joint penetrating group (three or more penetrated facet joints). Results Five patients suffered from C5 nerve palsy, and 2 patients had cerebrospinal fluid leakage. The follow-up time ranged 3-35 months (mean, 15.7 months). At the final follow-up, the JOA scores, NDI, cervical canal diameter, and cervical canal cross area were significantly improved when compared with preoperative ones (P lt; 0.05). At 1 week after operation, CT 3-D reconstruction showed that 16 patients had no penetrated facet joint, 23 patients had one or two penetrated facet joints, and 13 patients had three or more penetrated facet joints. There was no significant difference in age, gender, disease duration, operation time, intraoperative blood loss, and follow-up time among 3 groups (P gt; 0.05). And at the final follow-up, there was no significant difference in JOA score, VAS score, cervical curvature, cervical canal diameter, cervical canal cross area, the JOA recovery rates, and lamiae open angle among 3 groups (P gt; 0.05). The NDI of the multi-joint penetrated group was significantly higher than that of other 2 groups (P lt; 0.05). Axial pain occurred in 1 case of no penetrating group, in 4 cases of oligo-joint penetrating group, and in 5 cases of multi-joint penetrating group, showing no significant difference among 3 groups (χ2=4.881, P=0.087). Conclusion The penetrations of lateral mass screws into articular surface of facet joint may contribute to the axial symptoms after cervical laminoplasty. The risk of axial symptom raises accompany with increased penetrated facet joints.
Objective To review the progress of the pedicle screw augmentation technique by bone cement. Methods Recent literature about the pedicle screw augmentation technique by bone cement was reviewed and analysed. The characters were summarized. Results Pedicle augmentation technique includes the augmentation of ordinary solid pedicle screw and hollow pedicle screw. Both types could increase the fixation strength and gain satisfactory clinical results. Bone cement leakage had a certain incidence rate, but most of cases were asymptom. Conclusion Bone cement augmentation of pedicle screw is an effective and safe internal fixation for poor bone condition.
Objective To evaluate the clinical and radiographic outcomes of headless compression screws for Lisfranc joint injuries. Methods A retrospective analysis was made on clinical data of 34 patients (36 feet) with Lisfranc joint injuries who underwent open reduction and internal fixation with headless compression screws between January 2006 and January 2012. There were 22 males (24 feet) and 12 females (12 feet), aged 21-73 years (mean, 38.9 years). The causes of injury included traffic accident in 16 cases (17 feet), falling from height in 11 cases (12 feet), crushing in 5 cases (5 feet), and sports in 2 cases (2 feet). Of them, there were 19 cases (20 feet) of closed injury and 15 cases (16 feet) of open injury; there were 7 cases (8 feet) of pure dislocations of tarsometatarsal joints and ligamentous Lisfranc injuries (LD), 22 cases (23 feet) of Lisfranc joint fracture dislocations (LFD), 5 cases (5 feet) of combined Chopart-LFD (CLFD). According to Myerson classification, 5 cases (5 feet) were rated as type A, 7 cases (8 feet) as type B1, 14 cases (15 feet) as type B2, 5 cases (5 feet) as type C1, and 3 cases (3 feet) as type C2. Associated fractures included 12 cases (13 feet) of metatarsal shaft fracture, 4 cases (4 feet) of cuboid fracture, 4 cases (4 feet) of navicular bone fracture, 6 cases (7 feet) of coneiform bone fracture/dislocation, 8 cases (10 feet) of ipsilateral lower limb multiple fracture, and 4 cases (4 feet) of contralateral lower limb multiple fracture. The clinical outcomes were evaluated according to American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analogue scale (VAS) score. Postoperative X-ray films were taken to assess the reduction, internal fixation, and the foot arch height. Results All patients were followed up 1 year to 5 years and 2 months (mean, 3.5 years). X-ray films showed anatomical reduction in 31 cases (33 feet, 91.7%). At last follow-up, AOFAS score and VAS score averaged 80.6 (range, 60-100) and 2.3 (range, 0-6), respectively; the AOFAS score was significantly higher in patients having anatomical reduction than the patients having no anatomical reduction, in patients with LD and LFD than in patients with CLFD, and in patients without cuneiform bone fracture/dislocation than in patients with cuneiform bone fracture/dislocation (P lt; 0.05). There was no significant difference in the talus-first metatarsal angle, the distance between the lateral edge of the base of the first metatarsal bone and the medial edge of the base of the second metatarsal bone, and the arch height between the injured foot and normal foot (P gt; 0.05). Reduction loss was observed in 1 case (1 foot) because of early weight bearing; post-traumatic arthritis developed in 9 patients (10 feet). The incidence of post-traumatic osteoarthritis was higher in the patients with non-anatomic reduction, coneiform bone fracture/dislocation, comminuted intra-articular fractures of Lisfranc joints, the injury types (P lt; 0.05). Conclusion Headless compression screws for fixation of Lisfranc joint injuries can provide satisfactory short- and mid-term clinical and radiographic outcomes. During surgery, the precise anatomic reduction and stable fixation should be paid attention to, especially in patients with CLFD, coneiform bone fracture/dislocation, and comminuted intra-articular fractures of Lisfranc joints so as to control the incidence of the post-traumatic osteoarthritis.
Objective To explore the effectiveness of fixation of atlas translaminar screws in the treatment of atlatoaxial instability. Methods A retrospective analysis was made on the clinical data of 32 patients with atlatoaxial instability treated with atlantoaxial trans-pedicle screws between March 2007 and August 2009. Of them, 7 patients underwent atlas translaminar screws combined with axis transpedicle screws fixation because of fracture types, anatomic variation, and intraoperative reason, including 5 males and 2 females with an average age of 48.2 years (range, 35-69 years). A total of 9 translaminar screws were inserted. Injury was caused by traffic accident in 4 cases, falling from height in 2 cases, and crushing in 1 case. Two cases had simple odontoid fracture (Anderson type II), and 5 cases had odontoid fracture combined with other injuries (massa lateralis atlantis fracture in 2, atlantoaxial dislocation in 1, and Hangman fracture in 2). The interval between injury and operation was 4-9 days (mean, 6 days). The preoperative Japanese Orthopaedic Association (JOA) score was 8.29 ± 1.60. Results The X-ray films showed good position of the screws. Healing of incision by first intention was obtained, and no patient had injuries of the spinal cord injury, nerve root, and vertebral artery. Seven cases were followed up 9-26 months (mean, 14 months). Good bone fusion was observed at 8 months on average (range, 6-11 months). No loosening, displacement, and breakage of internal fixation, re-dislocation and instability of atlantoaxial joint, or penetrating of pedicle screw into the spinal canal and the spinal cord occurred. The JOA score was significantly improved to 15.29 ± 1.38 at 6 months after operation (t=32.078, P=0.000). Conclusion Atlas translaminar screws fixation has the advantages of firm fixation, simple operating techniques, and relative safety, so it may be a remedial measure of atlatoaxial instability．
Objective To evaluate the effectiveness of using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach to treat thoracolumbar kyphosis caused by old fracture. Methods Between June 2008 and June 2010, 15 cases of thoracolumbar kyphosis caused by old fracture were treated with pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach. There were 9 males and 6 females with a mean age of 54.6 years (range, 39-65 years). The disease duration was 5 months to 3 years with an average of 1.5 years. Fractured segments included T11 in 1 case, T12 in 4 cases, L1 in 5 cases, and L2 in 5 cases. Ten patients had nerve symptom, according to American Spinal Injury Association (ASIA) grading, 3 cases were classified as grade B, 4 cases as grade C, and 3 cases as grade D, of which 3 cases had sexual and sphincter dysfunction. At preoperation, the Cobb angle was (47.4 ± 10.2)°; the Oswestry disability index (ODI) score was 67.9% ± 6.9%; and the visual analogue scale (VSA) was 8.6 ± 1.4. Results The wounds obtained primary healing. The mean follow-up time was 28 months (range, 13-60 months). X-ray films showed intervertebral bone fusion was obtained within 6-11 months (mean, 10.2 months). No fixation loosening or breaking occurred during follow-up. Kyphosis was corrected, and lumbar back pain was relieved. At 1 year after operation, Cobb angle was significantly corrected to (13.3 ± 7.7)° (t=72.80, P=0.00); ODI score was significantly improved to 25.2% ± 4.6% (t=48.04, P=0.00); VAS score was significantly decreased to 2.3 ± 0.6 (t=26.52, P=0.00). According to ASIA grading in 10 patients with spinal cord injury, the spinal cord function was improved by 1 grade in 8 cases (3 cases from grade B to C, 3 cases from grade C to D, and 2 cases from grade D to E); 3 patients with sexual and sphincter dysfunction recovered in different degrees. Conclusion Using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach is an effective method to treat thoracolumbar kyphosis caused by old fracture.
Objective To compare the biomechanical properties of the anterior transpedicular screw-artificial vertebral body (AVB) and conventional anterior screw plate system (AP) in lower cervical spine by finite element study. Methods CT images (C1-T1) were obtained from a 38-year-old female volunteer. The models of intact C3-7 (intact group), AP fixation (AP group), and AVB fixation (AVB group) were established and analyzed by Mimics 14.0, Geomagic Studio 2013, and ANSYS 14.0 softwares. The axial force of 74 N and moment couple of 1 N·m were loaded on the upper surface and upper facet joint surfaces of C3. Under conditions of flexion, extension, lateral bending, and rotation, the Von Mises stress distribution regularity and maximum equivalent stree of AP and AVB groups were recorded, and the range of motion (ROM) was also analyzed of 3 groups. Results The intact model of lower cervical spine (C3-7) was established, consisting of 286 382 elements and 414 522 nodes, and it was successfully validated with the previously reported cadaveric experimental data of Panjabi and Kallemeyn. The stress concentrated on the connection between plate and screw in AP group, while it distributed evenly in AVB group. Between AP and AVB groups, there was significant difference in maximum equivalent stress values under conditions of 74 N axial force, flexion, extension, and rotation. AVB group had smaller ROM of fixed segments and larger ROM of adjacent segments than AP group. Compared with intact group, whole ROM of the lower cervical spine decreased about 3°, but ROM of C3, 4 and C6, 7 segments increased nearly 5° in both AP and AVB groups. Conclusion As a new reconstruction method of lower cervical spine, AVB fixation provides better stability and lower risk of failure than AP fixation.