【Abstract】 Objective To establ ish a stable animal model for glucocorticoid-induced avascular necrosis of femoral head in rabbits. Methods Thirty-six adult New Zealand rabbits were randomly divided into four groups:ten were injected twice with l i popolysaccharide (group A), ten were treated with a combination of l i popolysaccharideand methylprednisolone (group B), ten were injected three times with methylprednisolone (group C), and six wereinjected normal sal ine as a control (group D). MR imaging was performed in the rabbits before the first injection ofl i popolysaccharide or methylprednisolone, and at 2, 4, and 6 weeks after the last injection of l i popolysaccharide ormethylprednisolone. Histopathological changes in the femoral heads were observed by l ight microscope and transmission electron microscope at the end of six weeks after the injection. Vascular infusion with Chinese ink was made to evaluate the morphological changes of blood vessels in the femoral head. The percentage of trabecular bone area and empty lacunae and microvascular density were measured. According to the histological and MR imaging appearance of the femoral heads in all groups, the incidence of osteonecrosis of every group was calculated. Results Listlessness, blepharal hyperemia,less activity and reduced diet were found in the rabbits of groups A and B after injected with l ipopolysaccharide. At 3 weeks after the final injection, the body weight of groups B and C was decreased. At 4 weeks after the final injection, the body weight of groups A and D was increased. No abnormal signal could be detected on MR images in rabbits of all groupsbefore injection and at 2 weeks after the injection. At 4 weeks and 6 weeks after the last injection, irregular low signal on T1-weighted images and irregular low or high signal on T2-weighted images could be detected on MR images in rabbits of groups B and C, no abnormal signal could be detected on MR images in rabbits of groups A and D. At 6 weeks after the last injection,the trabecular bone of group B became thin and sparse, some were broken. The percentages of empty lacunae were 11.8% ± 4.7%, 34.4% ± 6.2%, 20.0% ± 4.7% and 9.3% ± 4.6%; the percentages of trabecular bone area were 59.2% ± 6.8%, 40.1% ± 6.0%, 51.5% ± 5.6% and 63.2% ± 8.3%; and the microvascular densities were 14.3% ± 2.7%, 4.5% ± 2.1%, 10.2% ± 3.1% and 15.4% ± 4.1% in groups A, B, C and D respectively. There were statistically significant differences between group B and groups A, C, D (P lt;0.01). The fatty tamponade accumulated in the medullary cavity and intramedullary vascular sinusoids were pressed by the l ipocytes and became narrow. Limposomes were found in osteocytes and vascular endothel ia of group B and group C. Osteocytes of group B crimpled and pyknosis or karyolysis of chromatin were observed in these osteocytes, nuclearmembrane of the osteocytes was discontinous. Vascular endothel ia became swollen and the cell junctions widened or were destroyed in groups A and B. The incidence of osteonecrosis in group B (88.9%) was higher than that in group C (22.2%, P lt; 0.05). There was no osteonecrosis occurred in groups A and D . Conclusion Methylprednisolone combined with l ipopolysaccharide can induce typical rabbit model for early avascular necrosis of femoral head.
To evaluate the cl inical results of less invasive stabil ization system (LISS) for femur supercondylar and intercondylar fractures. Methods From March 2004 to November 2005, 47 patients with 49 intercondylar and supercondylar fractures were treated. Of all the patients, there were 34 males and 13 females with an average of 39.7 years (range 19-56 years). The locations were left side in 21 cases and right side in 28 cases. Fracture was caused by traffic accident in 31 cases, fall ing in 8 cases, violence in 6 cases and others in 2 cases. Forty-nine fractures included 14 intercondylar fractures, 21supercondylar fractures and 14 intercondylar and supercondylar fractures; 32 closed fractures and 17 open fractures. According to the AO typing, there were 6 type 33-A1, 8 type 33-A2 , 10 type 33-A3, 7 type 33-C1, 3 type 33-C2 and 15 type 33-C3. The disease course was 30 minutes to 6 days. Articular surface reduction was first performed, then the LISS plate was inserted via two incisions and locking screws were used later. Results The average operation time was 126 minutes (range 48-248 minutes). The blood loss was 180 mL(range 60-1 200 mL). The average follow-up time was 18.6 months (range 12-23 months). There were 4 patients with AP angular deformity and 5 patients with lateral angular deformity (range 2-5°). External rotation deformity was presented in 2 patients. There were no plate breakage, screw loosen and fixation failure. Average bone union time was 5.6 months (range 3-8 months) without infection case. Six cases were treated with il iac bone transplantation for delayed union. Conclusion LISS is one kind of effective treatment to femoral intercondylar and supercondylar fractures.
Objective To investigate the surgical techniques and the cl inical outcomes of treating severe pronationexternal rotation ankle fractures combined with deltoid l igament injuries. Methods Between July 2005 and April 2007, 17 patients with grade-IV pronation-external rotation ankle fractures combined with deltoid l igament injuries were treated by open reduction and internal fixation with l igament repair by using suture anchors. There were 13 males and 4 femaleswith an average age of 36.5 years (21-56 years). All cases were closed injuries with l imitation of motion after initial physical examination. The X-ray and CT showed that all patients were characterized with lateral and posterior malleolus fractures and significant lateral shift of talus, but without medial malleous fracture before operation. All fractures were classified into grade-IV pronation- external rotation or type C according to Lauge-Hansen criterion and Danis-Weber standard respectively. The disease course was from 4 days to 7 days with an average of 5.6 days. Results All incisions healed by first intention Seventeen patients were followed up 11-24 months (mean 15.6 months). The X-ray films showed that all patients achieved bony heal ing. The heal ing time was 11-16 weeks (mean 14.8 weeks). According to the Baird-Jackson’s scoring system, the results were excellent in 5 cases, good in 9 cases, fair in 2 cases and poor in 1 case, the excellent and good rate was 82.4%. No operation compl ication occurred. Medial clear space was significantly decreased postoperatively compared with that before operation [(3.16 ± 0.37) mm vs. (4.87 ± 0.43) mm] (P lt; 0.01). In gravity stress radiographs, there was no significant difference in medial clear space between collateral ankle and injured ankle after operation [(3.47 ± 0.43) mm vs. (3.55 ± 0.44) mm] (P gt; 0.05). Conclusion It is emphasized that full attention should be given to reconstruction of medial l igament structures as well as open reduction and internal fixation in treating grade-IV pronation-external rotation ankle fractures combined with deltoid l igament injuries.
Objective To discuss the authenticity of reconstructing the anterior cruciate l igament (ACL) threedimensional digital model of normal adult knee joint by use of MRI. Methods The double knee joint specimens were selected from 20 fresh normal adult corpses and double knee joint of 20 normal adult volunteers, and were scanned with MRI; continuous image data of level thick 1.0 mm were acquired, and then these data were imported into Mimics 10.01 software for three-dimensional reconstruction; and full three-dimensional digital models were built, including the corpse specimens (corpsemodel group) and normal adult (normal model group). The relevance anatomy index of ACL were measured with easuring tool of Mimics 10.01 software, and double knee joint specimens of 20 fresh normal adult corpses were dissected, and the relevance data were measured (corpse specimens group). Results There was no significant difference in all indexes between corpse model group and corpse specimen group (P gt; 0.05), and between corpse model group and normal model group (P gt; 0.05). Conclusion The image data gathered by MRI could reconstruct the ACL three-dimensional digital model of normal adult knee joint, which has authenticity.
Objective To summarize the surgical learning curve and preliminary operative experience of dual-robotic navigated minimally invasive treatment on pelvic fractures by TiRobot and Artis Zeego. Methods Between July 2019 and February 2021, 90 patients with pelvic fractures were treated with dual-robotic navigated minimally invasive surgery by TiRobot and Artis Zeego. There were 64 males and 26 females, with an average age of 46.5 years (range, 13-78 years). Body mass index was 14.67-32.66 kg/m2 (mean, 23.61 kg/m2). Causes of injuries included traffic accident in 43 cases, falling from height in 37 cases, low-energy injuries such as flat falls in 10 cases. The interval between injury and surgery was 1-36 days (mean, 7.3 days). According to the location of the implanted screws, the patients were divided into sacroiliac screw group (n=33), acetabular screw group (acetabulum anterior/posterior column, n=24), composite screws group (sacroiliac and acetabulum anterior/posterior column, n=33). According to the screw implantation time and accuracy, the surgical learning curve was plotted, and the differences in the relevant indicators between learning stage and skilled stage were compared. Results All 90 patients successfully completed the operation, the intraoperative bleeding volume was 5-200 mL (median, 20 mL). There was no vascular or nerve injury. All incisions healed by first intention. The screw implantation time ranged from 7.5 to 33.0 minutes (mean, 18.92 minutes), and the screw implantation accuracy ranged from 1.1 to 1.8 mm (mean, 1.56 mm). According to the learning curve, the practice stage of 3 groups was reached after 7, 10, and 11 cases, respectively. With the accumulation of surgical experience, the screw implantation time had a significant downward trend. Compared with the learning stage, the screw implantation time on skilled stage in 3 groups significantly shortened (P<0.05), but the difference in the screw implantation accuracy was not significant (P>0.05). Conclusion TiRobot and Artis Zeego assisted pelvic fracture surgery is safe and efficient, which helps the surgeon to quickly master the pelvic channel screw surgery, and the operation time is significantly shortened on the premise of ensuring the implantation accuracy.