Comparison of Different Insertion Techniques for Lumbosacral Fixation Improvement: A Finite Element Study.

OBJECTIVE: We create a new S1 cortical screw trajectory technique using 3D reconstruction and the finite element (FE) method to provide a more reliable theoretical basis for clinical practices and to advance internal fixation technology for treatment of lumbosacral degenerative diseases. METHODS: This retrospective study included patients (aged from 40 to 70 years) who needed intervertebral fusion surgery between August 2016 and August 2017. Data of patients with lumbosacral lesions was scanned and measured by 64-row spiral CT, and were then transmitted to the GE-AW4.3 post-processing system for 3D reconstruction. The trajectories of the three different screws were simulated by FE software and processed by mimics software to simulate the screw path: traditional PS fixation (Model A); traditional cortical screw (Model B); and new cortical screw (Model C). The CT value of the bone around the screw canal was recorded. Biomechanical effects of the three screws were analyzed and compared. RESULTS: The displacement of flexion and extension, the vertebral body stress of right torsion, and the cage stress of flexion showed no significant differences among the three models (P > 0.05). The results demonstrated that cortical screws exceeded pedicle screws in stability and pullout force. Models B and C showed higher vertebral displacement in left bending (0.41 and 0.31 mm) and right bending (0.58 and 0.40 mm), lower vertebral body stress on extension (48.37 and 38.92 MPa), left bending (0.76 and 0.74 mm) and right bending (0.50 and 0.53 mm), and higher cage stress on left bending (162.19 and 160.63 MPa), right bending (150.02 and 150.05 MPa), left torsion (158.45 and 146.27 MPa) and right torsion (167.33 and 171.15 MPa) (all P < 0.05) compared to model A. Compared to Model B, Model C had higher displacement of left and right torsion, lower pressure in extension and flexion, and lower stress on cages in extension (P < 0.05). CONCLUSION: The new cortical screw insertion method has similar effects to traditional cortical screw fixation. However, it demonstrated advantages in promoting lumbosacral interbody fusion, which protects vessels and nerves.

[Early efficacies of total knee arthroplasty for knees with severe lateral instability].

OBJECTIVE: To evaluate the outcomes of primary total knee arthroplasty (TKA) in the treatment of knee with severe lateral instability and summarize the essential points of operation and rehabilitation. METHODS: From February 2005 to August 2010, primary TKA was performed in 27 severe lateral unstable knees (25 cases), including 3 males (3 knees) and 22 females (24 knees). Their mean age was 57.8 (37-71) years. And their primary diseases included rheumatoid arthritis (22 knees in 21 cases) and osteoarthritis (5 knees in 4 cases). Thirteen lateral unstable knees were accompanied with 18.08° ± 5.96°(15-35°) varus deformity; in the rest 14 knees, there was medial instability with 20.71° ± 7.03° (15-35°) valgus deformity. Blood loss volume, operative duration and complications were recorded. During the follow-up period, HSS score, knee stability and varus/valgus status were recorded preoperatively, 1, 3, 6, 12 months and then annually postoperatively. RESULTS: AORI type I bone defect was found at the proximal tibia in 18 knees and distal lateral femoral condyle in 10 knees. All defects were reconstructed with cement or autograft. AORI type II bone defects at proximal tibia in 3 knees were reconstructed with metal augmentation. Blood loss during the first 24 hours were (438.9 ± 109.5) (400-700) ml and operative duration (91.1 ± 11.6) (70-110) min. The mean follow-up period was (41.6 ± 10.9) (27-60) months. At the final follow-up, the HSS score increased from (45.8 ± 5.4) to (85.4 ± 4.5) (t = 30.15, P < 0.01) .Five knees in 5 cases had mild postoperative instability. All cases were allowed to walk with knee orthosis for 4-6 weeks. At the end of follow-up, mild lateral instability of 2 knees persisted. One augmented knee had osteolysis beneath metal block. CONCLUSION: TKA for knees with severe lateral instability requires a deep understanding of causes and a rational treatment. Proper handling of bone defects and careful release of lateral soft tissue are two critical points for postoperative knee stability. Wearing knee orthosis during the early postoperative stage may be helpful or residual mild instability.

[Effects of Tuina and Chinese patent drug Shuxuetong injection on deep venous thrombosis and functional rehabilitation after total knee arthroplasty].

OBJECTIVE: To evaluate the efficacy of Tuina and Chinese patent drug Shuxuetong injection in preventing patients undergoing total knee arthroplasty from deep venous thrombosis and in functional rehabilitation. METHODS: A total of 120 patients with diagnosed rheumatoid arthritis in the Department of Orthopaedic Surgery, Shanghai Guanghua Hospital of Integrated Traditional Chinese and Western Medicine in China were enrolled for this study. The patients underwent total knee arthroplasty and were divided into treatment group (n=60) and control group (n=60) after surgery. Patients in the control group received conventional rehabilitation training, including using a continuous passive motion machine and training of muscle contractions of the lower limb. Patients in the treatment group were administered Shuxuetong injection and Tuina based on the conventional rehabilitation training. The course of treatment lasted for 2 weeks. Hospital for Special Surgery (HSS) knee score, rate of deep venous thrombosis and range of motion of the knee joint were evaluated before and after treatment. RESULTS: There was no significant difference in HSS knee score and range of motion as compared before and after treatment in two group (P>0.05). The rate of deep venous thrombosis of the treatment group was 13.33%, which was lower than 20% of the control group (P<0.05). CONCLUSION: Tuina combined with Shuxuetong injection treatment can prevent deep venous thrombosis in patients with rheumatoid arthritis after total knee arthroplasty.