Objective To ascertain whether augmentation pedicle screw fixation with polymethylmethacrylate (PMMA) can enhance the stability of unstable thoracolumbar burst fractures of osteoporotic spine. Methods Six fresh frozen female osteoporotic spines (T10-L5) were harvested and an anterior and posterior columnunstable model of L1 was made. Each specimen was fixated with plate and the stability test were performed by flexion, extension, axial rotation and lateral bending. The test of fatigue was done with MTS 858.The tests were repeated after screws were augmented with PMMA. To compare the biomechanical stability of 6 different conditions:○anormal specimens(control), ○bdefectmodel fixed with plate, not augmented and not fatigued, ○cafter fatigued, not augmented, ○dscrews augmented with PMMA, not fatigued, ○e after augmented and fatigued. ResultsIn ○b,○d and ○e conditions, the ranges of motion(ROM) were 6.23±1.56，4.49±1.00，4.46±1.83 inflexion and 6.60±1.80，4.41±0.82，4.46±1.83 in extension. There was no significant difference (Pgt;0.05), they were significantly smaller than those in ○a and ○c conditions (8.75±1.88，1.47±2.25 and 8.92±2.97，12.24±3.08) (Plt;0.01).Conclusion The results demonstrated that augmentation pedicle screws fixation with PMMA can increase the stability of osteoporotic spine.
Objective To evaluate the clinical results of bioabsorbable interference screw in knee ligament reconstruction. Methods From April 2002 to August 2004, 39 patients with knee ligament injury were treated, including 33 males and6 females with a median age of 25 years (15 to 65 years). The involved ligament included 29 anterior cruciate ligament of knee(ACL), 6 posterior cruciate ligament of knee(PCL)，4 combined ACL and PCL, 3 medial collateral or lateral collateral ligaments of knee point and 1 posterolateral complex injury of knee. All of patients underwent anatomic ligament reconstructions under arthroscopy or open surgery by autografts and fixation with bioabsorbable interference screw. Results All 34 patients were followed up 6 to 28 months (mean 13.7months). The patients were evaluated by Lysholm knee functional scales, the knee scores were 43.6±13.4 before operation and 85.4±16.3 after operation, showing significant difference (Plt;0.05). There was no limitation of rangeof motion and loosening of the screw. However, one case suffered from infection, and 3 cases suffered from effusion and synovitis after surgery and recovered after management. Conclusion Bioabsorbable interference screw fixation is a reliable method in knee ligament reconstruction and is effective to restore knee joint stability.
Objective To explore the effect of blocking screws on the breakage of interlocking intramedullary nails. Methods From January 2003to August 2005, 56 patients with fresh and close fracture of long shafts were treated by interlocking intramedullary nails. Among them, there were 32 males and 24 females, including 26 femoral fracture and 30 tibial fracture. Fracture of femoral and tibialshaft was fixed with interlocking intramedullary nails normally in group Ⅰ(n=32). And long oblique, spiral, proximal or distal fracture of bone shaft was fixed with interlocking intramedullary nails and blocking screws in group Ⅱ(n=24). Results All cases were followed up 12 to 21 months(16 months on average). In group Ⅰ, fracture healing failed and the intramedullary nails broke in 3 cases, breakage site was the middle femoral fracture area in 1 case and the first distal interlocking nail hole in 2 cases of distal 1/3 tibial fracture. Fractures healed 6 to 12 months after operations in the other cases, but more bony callus occurred in fracture area. In group Ⅱ, fractures healing and good alignment were achieved, and no breakage was found in all 24cases. Conclusion The use of blocking screws added to interlocking intramedullary nails could improve the stability of fracture areas distinctively, and hence reduce the breakage of intramedullary nails.
ObjectiveTo compare the safety and accuracy of pedicle screw placement assisted by robot system with freehand pedicle screw placement in upper thoracic surgery.MethodsBetween December 2017 and December 2019, 39 cases with upper thoracic pedicle screw internal fixation were included in the study, including 19 cases in robot group (group A, robot assisted pedicle screw placement) and 20 cases in freehand group (group B, freehand pedicle screw placement). There were 104 screws implanted in group A and 108 screws in group B. There was no significant difference in age, gender composition, body mass index, disease type, number of screws implanted, and segmental distribution between the two groups (P>0.05). The operation time, intraoperative blood loss, and postoperative drainage were recorded and compared between the two groups. CT scan was performed in all patients at 2 days after operation to evaluate the screw accuracy based on the Gertzbein-Robbins grading standard.ResultsThe operation time of group A was significantly longer than that in group B (t=2.759, P=0.009). There was no significant difference in intraoperative blood loss and postoperative drainage between the two groups (t=?0.796, P=0.431; t=?0.814, P=0.421). At 2 days after operation, according to Gertzbein-Robbins grading standard, the accuracy of pedicle screw implantation in group A were grade A in 94 screws, grade B in 9 screws, and grade C in 1 screw; and in group B were grade A in 72 screws, grade B in 26 screws, grade C in 9 screws, and grade D in 1 screw; the difference between the two groups was significant (Z=4.257, P=0.000). The accuracy rate of group A was 99.04%, and that of group B was 90.74%, showing significant difference (χ2=7.415, P=0.006).ConclusionCompared with traditional freehand pedicle screw placement, robot-assisted pedicle screw placement significantly improves the accuracy and safety of screw placement without increasing the bleeding and postoperative drainage.
【Abstract】 Objective To evaluate the effectiveness of percutaneous fixation with il iosacral screw in the management of unstable pelvic fractures. Methods From March 2003 to January 2007, 15 patients with unstable pelvic fractures were treated by percutaneous fixation with il iosacral screws. There were 6 males and 9 females, aged 21-56 years. Fractures were caused by traffic accident in 8 cases, high fall ing in 6 cases and crushing injury in 1 case. The disease course ranged from 4 hours to 3 days. Of 15 patients, 7 had fractures of pubium and sacrum; 2 had fractures of il ium and sacrum; 4 had dislocation of sacroil iac joint with fractures of pubic rami; and 2 had dislocation sacroil iac joint with fracture of sacrum of pubium. Anterior fixation was performed by means of plating in 3 cases, by external fixation in 7 cases, and by both in 5 cases. Results The blood loss was from 1 000 to 1 500 mL in 4 patients with acetabular fracture and about 50 mL in the others. The average operative time was 153.6 minutes (range, 60-305 minutes). Fifteen patients were followed up 6 months to 3 years with an average of 18months. According to Matta criterion for fracture reduction, the results were excellent in 14 cases and good in 1 case. After a follow-up of 28.8 months, fracture union was achieved in all patients. Screw loosening occurred in 1 case, pain of lumbosacral region in 3 cases after tiredness and mild claudication in 2 cases. Nine patients returned to their occupation, three patients changed occupation, and 3 patients could not work at last follow-up. According to Majeed functional scoring, the results were excellent in 11 cases and good in 4 cases. Conclusion Percutaneous il iosacral screw fixation is a useful method in treatment of unstable pelvic fracture.
ObjectiveTo explore the effectiveness of hollow screw for the treatment of basilar part fracture of hamate hook.MethodsFive patients with basilar part fracture of hamate hook, aged 24-47 years (mean, 31 years) were treated with open reduction and hollow screw fixation between June 2015 and February 2019. There were 4 males and 1 female. The causes of injury were athletic injury in 3 cases, falling injury in 1 case, and crushing injury in 1 case. Among them, 1 case was combined with sensory disturbance of one and a half fingers on the ulnar side of the palm. The grip strength of the affected side was significantly decreased when compared with that of the healthy side in all patients. The intervals between injury and surgery were 3-8 days (mean, 4.2 days). Postoperative follow-up was conducted regularly to measure the grip strength of the affected and healthy fingers and the total motion of ring and little fingers of the affected side. Darrow criteria was used to evaluate the effectiveness.ResultsAll the incisions healed by primary intention. All the patients were followed up 6-32 months (mean, 16 months). X-ray films showed that the basilar part fracture of hamate hook reached bony union, and the healing time was 2.0-3.5 months (mean, 2.2 months). At last follow-up, the grip strength of the affected side was (35.80±3.76) kg, showing no significant difference when compared with healthy side [(36.00±4.94) kg] (t=0.094, P=0.930); and the total motion of ring and little fingers of the affected side was (529.0±8.9)°, which was significantly different from that before operation [(232.0±34.7)°] (t=18.108, P=0.000). In 1 patient with ulnar nerve injury, the two-point discrimination of the innervation area was 4 mm, and the pain sensation and temperature sensation returned to normal. Assessed by Darrow criteria, the results were excellent in 4 cases and good in 1 case.ConclusionFor the basilar part fracture of hamate hook, hollow screw fixation can obtain secure reduction and fixation and provide sustained compression and counter-rotation for the broken end of fracture, thus allowing early joint motion and promoting fracture healing and recovery of wrist function. It is a relatively good method for the treatment of basilar part fracture of hamate hook.
Objective To investigate the treatment method of senile patients with femoral intertrochanteric fractures and its cl inical outcomes. Methods From January 2005 to December 2007, 192 senile patients with femoral intertrochanteric fractures were treated, including 85 males and 107 females aged 65-92 years old (average 75 years old). The injury was causedby fall on walking in 106 cases, fall when riding a bicycle in 55 cases, and traffic accidents in 31 cases. According to Evans classification, there were 12 cases of type I A, 43 cases of type I B, 29 cases of type II, 24 cases of type III A, 23 cases of type III B, 26 cases of type IV, and 35 cases of type V. One hundred and fifty patients were associated with cardio-cerebrovascular diseases, 120 patients were compl icated with chronicle hypertension, 90 cases were associated with bronchitis, and 75 cases were compl icated with diabetes. The time from injury to hospital admission was 1 hour to 14 days. Among those patients, 108 were treated with conservative treatment, 68 received dynamic hip screw (DHS) fixation, and 16 underwent proximal femoral Gamma nail fixation. Results All the patients were followed up for 12-36 months (average 18 months). The fracture all reached bone union without occurrence of nonunion and delayed union. Patients could take care of themselves, and there were no occurrences of serious pains and dysfunctions. The therapeutic effect was satisfactory. The conservative treatment group: the average hospital stay length was 48 days; the average bone heal ing time was 14 weeks; 23 cases had different degrees of coxa adducta; Harris score system was adopted to evaluate hip joint function, 45 cases were graded as excellent, 31 as good, 10 as fair, and 22 as poor, and the excellent and good rate was 70.4%. DHS internal fixation group: the average operation time was 60 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 24 days; the average bone heal ing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 38 cases were graded as excellent, 21 as good, 8 as fair, and 1 as poor, and the excellent and good rate was 86.8%. Gamma nailfixation group: the average operation time was 70 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 14 days; the average bone heal ing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 11 cases were graded as excellent, 4 as good, 1 as fair, and the excellent and good rate was 93.8%. Conclusion For geriatric femoral intertrochanteric fractures, operative treatment should be performed, the preoperative preparation should be sufficient, and individual-oriented treatment method should be selected on the basis of physical conditions of patients and the types of fractures.
Objective To evaluate the biomechanical effect of a self-made iliac screw plate on the stability of lumbo-iliac fixation construct before and after fatigue loading. Methods Twelve fresh lumbo-pelvic specimens from donated adult cadavers with formalin embalm were used in the study. According to whether use the iliac screw plate or not, the specimens were randomly assigned into group A (with iliac screw plate, n=6) and group B (without iliac screw plate, n=6). The bone mineral density (BMD) of L1-4 was measured using dual-energy radiograph absorptiometry. The pedicle screw and iliac screw fixation were given at L3-5, and bilateral facetectomy and diskectomy at L5, S1 level were performed to prepare the model of the intervertebral destabilization. The biomechanical testing was conducted on a material testing machine under 0-600 N compression and — 7-7 N · m torsion loading modes for the initial compressive stiffness and torsional stiffness evaluation. And then 20 000 cyclic compressive loading of 40-400 N was given to the specimen, the stiffness evaluation was repeated. Then the maximum pull-out strength of screws at every level was measured and compared. Gross observation and radiological observation were performed during experiment. Results The BMD values of groups A and B were (1.15 ± 0.13) g/cm2 and (1.12 ± 0.11) g/ cm2 respectively, showing no significant difference between 2 groups (t=0.428, P=0.678). All pedicle screws and iliac screws were inserted in good position; no loosening or breaking of screw was observed during loading. After fatigue loading, the incidence of halo ring around the iliac screws of groups A and B was 16.7% (1/6) and 50.0% (3/6), respectively. The compressive stiffness and torsional stiffness after fatigue loading were significantly lower than those in initial state in groups A and B (P lt; 0.05); there was no significant difference in compressive stiffness and torsional stiffness between groups A and B before fatigue loading (P gt; 0.05). However, group A had higher compressive stiffness than group B (t=2.664, P=0.024) after fatigue loading, and there was no significant difference in torsional stiffness between 2 groups (t=0.410, P=0.690). No significant difference was found in screw pull-out strength of pedicle screws at L3, L4, and L5 levels between groups A and B (P gt; 0.05); however, the pull-out strength of the iliac screws in group A was significantly higher than that in group B (t=3.398, P=0.007). In groups A and B, the pull-out strength of L3 screw was significantly lower than that of L4 and L5 screws (P lt; 0.05). In group A, pull-out strength of the iliac screws was significantly higher than that of L3, L4, and L5 screws (P lt; 0.05); in group B, the pull-out strength of iliac screws was significantly lower than that of L4 and L5 screws (P lt; 0.05). Conclusion In the lumbo-iliac reconstruction, the use of iliac screw plate could resist iliac screw loosening, therefore, it has the potential to increase the stability of lumbo-iliac fixation construct.
Objective To investigate the antibacterial and osteogenic capabil ities in vivo of hydroxyapatite (HA)/silver (Ag) coating. Methods HA/Ag coating (Ag qual ity percentage was 3%) and HA coating were deposited to external fixator Schanz screws. The tibial fracture model was establ ished in right hindl imb of 18 adult male Beagle dogs (weighing 15-20 kg). Thetibia was stabil ized with an external fixator and 2 Schanz screws of HA coating at proximal tibia (control group, n=18) and HA/Ag coating at distal tibia (experimental group, n=18), and every screw incision was infected with Staphylococcus aureus. Infection in screw holes and the changes of bone-screw interface were observed by wound grading and X-ray films. Results In control group, wounds infection became worse with time (χ2=13.492, P=0.001), while in experimental group, no obvious change was observed (χ2=0.208, P=0.901). The wound grading of experimental group was significantly better than that of the control group at 1, 2, and 3 weeks (P lt; 0.05). Laser scanning confocal microscope showed that there was bacterial adhesion on the surface of screws in 2 groups, viable becteria mainly in control group and non-viable becteria mainly in experimental group. The scanning electron microscope (SEM) observation results of the fractured sclerous tissue section showed that an obvious transparent boundary between screw and bone in control group, but no obvious boundary in experimental group. The osseointegration ratios were 76.23% ± 15.54% in control group and 93.42% ± 5.53% in experimental group, showing significant difference (t=8.843, P=0.000). The SEM observation showed that HA/Ag coating integrated with new bone and the surface of implant was filled with new bone in experimental group; obvious interspace was seen between the HA coating and new bone in control group. Conclusion HA/Ag coating has good antibacterial and osteogenic capabil ities, so it can take effects in preventing infection in screw holes and loosening of implants.
ObjectiveTo analyze the biomechanical properties of the rod-screw prosthesis based on a pelvic three-dimensional finite element model including muscle and ligament, and evaluate the effectiveness of zoneⅠ+Ⅱ+Ⅲ reconstruction of hemipelvis with rod-screw prosthesis in combination with clinical applications. Methods A total of 21 patients who underwent hemipelvic tumor resection (zoneⅠ+Ⅱ+Ⅲ) and rod-screw prosthesis reconstruction between January 2015 and December 2020 were selected as the research subjects. Among them, there were 11 males and 10 females; the age ranged from 16 to 64 years, with an average age of 39.2 years. There were 9 cases of chondrosarcoma, 7 cases of osteosarcoma, 3 cases of Ewing sarcoma, and 2 cases of undifferentiated pleomorphic sarcoma. According to the Musculoskeletal Tumor Society Score (MSTS) staging, there were 19 cases of stage ⅡB and 2 cases of stage Ⅲ. Preoperative Harris Hip Score (HHS) and MSTS score were 54.4±3.1 and 14.1±2.0, respectively. Intraoperative 15 cases underwent extensive resection, 5 cases underwent marginal resection, and 1 case underwent intralesional resection. The CT image of 1 patient after reconstruction was used to establish a three-dimensional solid model of the pelvis via Mimics23Suite and 3-matic softwares. At the same time, a mirror operation was used to obtain a normal pelvis model, then the two solid models were imported into the finite element analysis software Workbench 2020R1 to establish three-dimensional finite element models, and the biomechanical properties of the standing position were analyzed. The operation time, intraoperative blood loss, and operation-related complications were recorded, and the postoperative evaluation was carried out with HHS and MSTS scores. Finally, the local recurrence and metastasis were reviewed. ResultsFinite element analysis showed that the peak stress of the reconstructed pelvis appeared at the fixed S1, 2 rod-screw connections; the peak stress without muscles was higher than that after muscle construction, but much smaller than the yield strength of titanium alloy. The operation time was 250-370 minutes, with an average of 297 minutes; the amount of intraoperative blood loss was 3 200-5 500 mL, with an average of 4 009 mL. All patients were followed up 8-72 months, with an average of 42 months. There were 7 cases of pulmonary metastasis, of which 2 cases were preoperative metastasis; 5 cases died, 16 cases survived, and the 5-year survival rate was 72.1%. There were 3 cases of local recurrence, all of whom did not achieve extensive resection during operation. The function of the affected limbs significantly improved, and the walking function was restored. The HHS and MSTS scores were 75.2±3.0 and 20.4±2.0 at last follow-up, respectively, and the differences were significant when compared with those before operation (t=22.205, P<0.001; t=11.915, P<0.001). During follow-up, 2 cases of delayed incision healing, 2 cases of deep infection, 1 case of screw loosening, and 1 case of prosthesis dislocation occurred, and no other complication such as prosthesis or screw fracture occurred. Conclusion The stress and deformation distribution of the reconstructed pelvis are basically the same as normal pelvis. The rod-screw prosthesis is an effective reconstruction method for pelvic malignant tumors.