Objective To evaluate the biomechanicalproperties and structuralcharacteristics of various composites of partially decalcified allogenic bone matrix gelatin and bone cement at different ratios. Methods According to Urist method, partially decalcified allogenic bone matrix gelatin was prepared and mixedwith bone cement at different ratios of 0, 400, 500, and 600mg/g. Then the comparisons of these composites were performed in microstructure, ultimate compression strength and ultimate bending strength properties. Results The electronic microscope showed that the bone particles and bone cement were distributed evenly in the composite, irregularly connecting by multiple points; with the increase ofbone particles and decrease of bone cement in the composite, there were more and more natural crevices, varying from 100 μm to 400 μm in width, in the biomaterials. Of all the composites with the ratios of 0, 400,500, and 600 mg/g, the measurements of ultimate compression strength were (71.7±2.0) MPa, (46.9±3.3) MPa, (39.8±4.1) MPa, and (32.2±3.4) MPa, respectively; and the measurements ofultimate bending strength were (65.0±3.4) MPa, (38.2±4.0) MPa, (33.1±4.3) MPa and (25.3±4.6) MPa, respectively. Conclusion The compositeof partially decalcified allogenic bone matrix gelatin and bone cement has a good biomechanical property and could be easily fabricated and re-shaped, which make it available to be used clinically as an idea bone graft biomaterial.
To discuss the effect of dexamethasone in preventing fat embol ism syndrome (FES) in cemented hi p arthroplasty patients. Methods Forty patients scheduled for unilateral cemented hi p arthroplasty between January 2008 and December 2009 were randomly divided into trial group (n=20) and control group (n=20). In trial group, there were 6 males and 14 females with an average age of 73.2 years (range, 54-95 years), including 4 cases of osteoarthritis, 3 cases ofavascular necrosis of femoral head, and 13 cases of femoral neck fracture; the disease duration was 4 days to 6 years (median, 0.8 year). In control group, there were 10 males and 10 females with an average age of 71.9 years (range, 59-91 years), including 2 cases of osteoarthritis, 3 cases of avascular necrosis of femoral head, and 15 cases of femoral neck fracture; the disease duration was 3 days to 5 years (median, 0.6 year). There was no significant difference in gender, age, or disease duration (P gt; 0.05) between 2 groups. Cemented total or bipolar hip arthroplasty (with the same brand of cement and prosthesis) in 2 groups were performed by a group of surgeons. The patients were given intravenously injected with dexamethasone (20 mg) in trial group before 1 hour of cement injection and intravenously injected with normal sal ine (2 mL) in control group. Amount of 5 mL vein blood were withdrawn before surgery, after 4, 8, and 24 hours of cement injection to test the number and average diameter of fat droplets. According to Gurd diagnosis standard, related FES symptoms and signs were inspected. Results Primary heal ing of incision was achieved in all cases of 2 groups. According to Gurd standard of diagnosis, no FES occurred in each group at 2 weeks postoperatively; deep venous thrombosis occurred in 2 cases (10%) of trial group and in 5 cases (25%) of control group, showing significant difference (P lt; 0.05). The number and diameter of fat droplets in trial group were significantly lower than those in control group at 4, 8, and 24 hours of cement injection (P lt; 0.01). All cases were followed up 7.4 months on average (range, 3-13 months). The postoperative Harris score was 89.5 ± 6.1 in trial group and 87.9 ± 8.3 in control group, showing no significant difference (P gt; 0.05). No loosening occurred during follow-up period. Conclusion Intravenous injection withdexamethasone can effectively reduce the number and diameter of venous fat droplets in cemented hip arthroplasty, which can decrease the risk of postoperative FES.
Objective To evaluate the effect of polymethylmethacrylate (PMMA) augmentation on cervical stabil ity after anterior cervical interbody fusion (ACIF) before and after fatigue. Methods Twelve porcine cervical spines (C3-7) were subjected to testing angular displacement parameters, including the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ), in nondestructive flexion and extension, right/left lateral bending, and left/right rotation on Motion Analysis motion capture system and MTS-858 servo-hydraul ic testing machine. Intact cervical spines served as control group (group A); oneleveldiscectomy and fusion was performed with anterior plate fixation based on group A as group B; flexion and extension,left/right lateral bending (5 000 cycles) fatigue testing based on group B as group C; the augmentation screw channel was used based on group C as group D; and flexion and extension, left/right lateral bending fatigue testing were performed based on group D as group E. Results The ROM, NZ, and EZ in group A were significantly different from those in other groups (P lt; 0.05) at flexion/extension, left/right bending, and left/right rotation. The ROM, NZ, and EZ in group B were significantly smaller than those in group C (P lt; 0.05) in flexion/extension, left/right bending, and left/right rotation, but there was no significant difference when compared with group D (P gt; 0.05). The ROM and NZ in flexion/extension and the EZ in flexion in group B were significant smaller than those in group E (P lt; 0.05), but there was no significant difference in the other indexes (P gt; 0.05). The ROM, NZ, and EZ in group C in flexion and extension, left/right lateral bending, and left/right rotation were significantly higher than those in groups D and E (P lt; 0.05). The ROM and NZ in flexion and extension and left/right lateral bending, and the ROM in left/right rotation, and the EZ in flexion and extension, right bending, and left/right rotation in group D were significantly smaller than those in group E (P lt; 0.05), but there was no significant difference in the other indexes (P gt; 0.05). Conclusion PMMA augmentation can significantly increase the instant cervical stabil ity and provide a biomechanics basis in cervical anterior plate fixation.
Objective To evaluate the strength of polyethylene l inercement interface when cementing a new linerinto a fixed acetabular cup in revision. Methods Twenty-five pairs of metal acetabular cups with polyethylene l iners were randomly divided into 5 groups: 1 group with standard locking device as control group (group A), other l iners were cemented into acetabular cups as 4 experimental groups. According to different intersection angles of metal acetabular cups with polyethylene liners and the polyethylene l iners with or without metal ball, the 4 experimental groups were no ball 0° group (group B), 0° group (group C), 10° group (group D), and 20° group (group E), metal acetabular cups intersected with polyethylene liners without metal ball in group B, with metal ball in groups C, D, and E, respectively. The lever-out biomechanical test reproduced in vivo failure mechanism was then performed to evaluate the lever-out failure strength of l iner-cement-metalcup interface. Results The values of l iver-out failure force were (626.68 ± 206.12), (915.04 ± 197.49), (449.02 ± 119.78),(814.68 ± 53.89), and (1 033.05 ± 226.44) N in groups A, B, C, D, and E, respectively, showing significant differences forcomparison among groups (F=8.989，P=0.000). The values of l iver-out failure force in groups B and E were significantlyhigher than that in group A (P lt; 0.05), but no significant difference was found between groups C, D and group A (P gt; 0.05).Conclusion Cementation of polyethylene l iner into a malposition shell meeting within 20° can provide enough fixed strength.
Objective To biomechanically compare the maximum pull-out strengths among two pedicle screws and three salvage techniques using poly methylmethacrylate (PMMA) augmentation in osteoporotic sacrum, and to determine which PMMA augmentation technique could serve as the salvage fixation for loosening sacral pedicle screws. Methods Eleven sacra were harvested from fresh adult donated cadavers, aged from 66 to 83 years (average 74.4 years) and included 5 men and 6 women. Radiography was used to exclude sacra that showed tumor or inflammatory or any other anatomic abnormal ities. Following the measurement of bone mineral density, five sacral screw fixations were sequentially establ ished on the same sacrum as follows: unicortical pedicle screw (group A), bicortical pedicle screw (group B), unicortical pedicle screw with the traditional PMMA augmentation (group C), ala screw with the traditional PMMA augmentation (group D), and ala screw with a kyphoplasty-assisted PMMA augmentation technique (group E). According to the sequence above, the axial pull-out test of each screw was conducted on a MTS-858 material testing machine. The maximum pull-out forces were measured and compared. The morphologies of PMMA augmented screws after being pulled-out were also inspected. Results The average bone mineral density of 11 osteoporotic specimens was (0.71 ± 0.08) g/cm2 . By observation of the pull-out screws, groups C, D, E showed perfect bonding with PMMA, and group E bonded more PMMA than groups C and D. The maximum pull-out forces of groups A, B, C, D, and E were (508 ± 128), (685 ± 126), (846 ± 230), (543 ± 121), and (702 ± 144) N, respectively. The maximum pull-out strength was significantly higher in groups B, C, and E than in groups A and D (P lt; 0.05), and in group C than in groups B and E (P lt; 0.05). There was no significant difference in pull-out strength between groups A and D, and between groups B and E (P gt; 0.05). Conclusion For sacral screw fixation of osteoporotic patients with bone mineral density more than 0.7 g/cm2, bicortical pedicle screw could acquire significantly higher fixation strength than the unicortical. Once the loosening of pedicle screw occurs, the traditional PMMA augmentation or ala screw with kyphoplasty-assisted PMMA augmentation may serve as a suitable salvage technique.
To investigate the effects of augmentation with bone cement on the biomechanics of the dynamic hip screw (DHS) fixation in the intertrochanteric fracture specimen that has a normal bone density.MethodsTwentyfour matched pairs of the embalmed male upper femora (48sides) were used to make the specimens of the intertrochanteric fracture of Type A2. All the specimens were fixed with DHS. The right femur specimen from each pair was fixed by augmentation with DHS (the augmentation group) and the left femur specimen was fixed with the conventional fixation (the control group). Thebiomechanical tests on the bending stiffness and the torsional stiffness were performed with the servohydraulic testing machine in the two groups.ResultsThe maximum load and the maximum torque were 3 852.160 2±143.603 1 N and 15.5±2.6 Nm in the augmentation group and 3 702.966 7±133.860 1 N and 14.7±3.4 Nm in the control group. There was no significant difference in the biomechanical effects between the two groups (P＞0.05). Conclusion The augmenting fixation with bone cement in the intertrochanteric fracture specimen with a normal bone density has no significant effect on the strength of the DHS augmentation or on the overall stability of the fractured bone.
Objective To investigate the physicochemicalproperties of the calcium phosphate cement (CPC) containing Danshen composite injection and its drug release rate. Methods This experiment included 4 groups and each group contained 6 specimens. CPC (2 g) was mixed with the setting solution that served as thecontrol group; 0.1,0.5 and 1.0 ml of Danshen composites injection (concentration, 1 000 mg/ml; pH, 7.35) were respectively added to CPC (2 g), which were used as the experimental groups 1, 2 and 3. The resulting specimens were investigated by the X-ray diffraction (XRD), the fourier transformed infrared spectroscopy(FTIR), and the scanning electron microscope (SEM).ResultsThe XRD analysis showed that the control group had a typical diffraction pattern of the hydroxypatite (HAP), which was consistent with the standard patternof HAP. When more Danshen was added in the experimental groups, the diffractionpeaks of HAP gradually decreased; when the diffraction angle 2θ was about 25.92°, the HAP peaks disappeared. Based on the FTIR analysis, with an increase of the drug concentration, the absorption peak of the hydroxy groups decreased. The SEM showed that the size of the CPC particle was related to the drug concentration; with an increase of the drug concentration, the CPC particle increased in number, resulting in an increasing trend of coacervation. The elution test showed that the drugrelease rate and capacity varied with the different concentrationsof Danshen. The initial release rate was relatively great, but after 96 hours the rate slowed down, lasting for a long time. Conclusion The physicochemical properties of CPC do not change when a proper dose (0.1 ml/2 g) of Danshen isadded to CPC. The Danshen composite can be effectively released from CPC, and so CPCcan be used as an ideal drugdelivery carrier for Danshen composite.
Open reduction and internal fixation with plate and screw is one of the most widely used surgical methods in the treatment of proximal humeral fractures in the elderly. In recent years, more and more studies have shown that it is very important to strengthen the medial column support of the proximal humerus during the surgery. At present, orthopedists often use bone graft, bone cement, medial support screw and medial support plate to strengthen the support of the medial column of the proximal humerus when applying open reduction and internal fixation with plate and screw to treat proximal humeral fractures. Therefore, the methods of strengthening medial column support for proximal humerus fractures and their effects on maintaining fracture reduction, reducing postoperative complications and improving functional activities of shoulder joints after operation are reviewed in this paper. It aims to provide a certain reference for the individualized selection of medial support methods according to the fracture situation in the treatment of proximal humeral fractures.
ObjectiveTo evaluate the effectiveness of orthopedic robot with modified tracer fixation (short for modified orthopedic robot) assisted percutaneous kyphoplasty (PKP) in treatment of single-segment osteoporotic vertebral compression fracture (OVCF). Methods The clinical data of 155 patients with single-segment OVCF who were admitted between December 2017 and January 2021 and met the selection criteria was retrospectively analyzed. According to the operation methods, the patients were divided into robot group (87 cases, PKP assisted by modified orthopedic robot) and C-arm group (68 cases, PKP assisted by C-arm X-ray fluoroscopy). There was no significant difference in gender, age, body mass index, T value of bone mineral density, therapeutic segment, grade of vertebral compression fracture, and preoperative visual analogue scale (VAS) score, midline vertebral height, and Cobb angle between the two groups (P>0.05). The effectiveness evaluation indexes of the two groups were collected and compared. The clinical evaluation indexes included the establishment time of working channel, dose of intraoperative fluoroscopy, the amount of injected cement, VAS score before and after operation, and the occurrence of complications. The imaging evaluation indexes included the degree of puncture deviation, the degree of bone cement diffusion, the leakage of bone cement, the midline vertebral height and the Cobb angle before and after operation. Results The establishment time of working channel in robot group was significantly shorter than that in C-arm group, and the dose of intraoperative fluoroscopy was significantly larger than that in C-arm group (P<0.001). There was no significant difference in the amount of injected cement between the two groups (t=1.149, P=0.252). The patients in two groups were followed up 10-14 months (mean, 12 months). Except that the intraoperative VAS score of the robot group was significantly better than that of the C-arm group (P<0.05), there was no significant difference between the two groups at other time points (P>0.05). No severe complication such as infection, spinal cord or nerve injury, and pulmonary embolism occurred in the two groups. Five cases (5.7%) in robot group and 7 cases (10.2%) in C-arm group had adjacent segment fracture, and the difference in incidence of adjacent segment fracture between the two groups was not significant (χ2=1.105, P=0.293). Compared with C-arm group, the deviation of puncture and the diffusion of bone cement at 1 day after operation, the midline vertebral height and Cobb angle at 1 month after operation and last follow-up were significantly better in robot group (P<0.05). Eight cases (9.1%) in the robot group and 16 cases (23.5%) in the C-arm group had cement leakage, and the incidence of cement leakage in the robot group was significantly lower than that in the C-arm group (χ2=5.993, P=0.014). There was no intraspinal leakage in the two groups. ConclusionCompared with traditional PKP assisted by C-arm X-ray fluoroscopy, modified orthopedic robot-assisted PKP in the treatment of single-segment OVCF can significantly reduce intraoperative pain, shorten the establishment time of working channel, and improve the satisfaction of patients with operation. It has great advantages in reducing the deviation of puncture and improving the diffusion of bone cement.
Objective To investigate the difference of total knee arthroplasty (TKA) with tantalum monoblock tibial component (TMT) and cemented tibial plateau prosthesis in patients of different ages. Methods The clinical data of 248 patients (392 knees) who underwent primary TKA between May 2014 and May 2019 and met the selection criteria were retrospectively analyzed. There were 54 males (98 knees) and 194 females (294 knees). Of the 122 patients (183 knees), less than 65 years old, 52 (75 knees, group A1) were treated with TMT and 70 (108 knees, group B1) were treated with cemented tibial plateau prosthesis; of the 126 patients (209 knees), more than 65 years old, 57 (82 knees, group A2) were treated with TMT and 69 (127 knees, group B2) were treated with cemented tibial plateau prosthesis. The baseline data of patients, perioperative indicators [hemoglobin (Hb), hematocrit (Hct), total blood loss, unilateral operation time], effectiveness evaluation indicators [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, visual analogue scale (VAS) score, Knee Society Scoring System (KSS) score, active flexion and extension range of motion (ROM) of the knee joint], complications, and imaging indicators [tibial prosthesis varus angle (β angle), tibial prosthesis posterior slope angle (δ angle), tibio-femoral angle, occurrence of radiolucent line, prosthesis survival rate] were recorded and compared. Results There was no significant difference in gender, age, height, weight, body mass index, Kellgren-Lawrence grading, the length of hospital stay, and follow-up time between groups A1, B1 and groups A2, B2 (P>0.05). The unilateral operation time in groups A1 and A2 was significantly shorter than that in the corresponding groups B1 and B2 (P<0.05). There was no significant difference in differences of pre- and post-operative Hb and Hct and total blood loss between groups A1, B1 and groups A2, B2 (P>0.05). There was no significant difference in preoperative effectiveness evaluation indicators between groups A1, B1 and groups A2, B2 (P>0.05). There were significant differences in the differences of pre- and post-operative WOMAC activity and pain scores, KSS function and pain scores, and VAS scores between groups A1 and B1 (P<0.05); there was no significant difference in WOMAC stiffness score and ROM (P>0.05). There was no significant difference in the above indicators between groups A2 and B2 (P>0.05). There was no significant difference in the incidence of complications (2.7% vs 6.5%, 3.7% vs 3.1%) and prosthesis survival rate (100% vs 97.2%, 100% vs 99.2%) between groups A1, B1 and groups A2, B2 (P>0.05). During follow-up, there was no significant difference in β angle, δ angle, and tibio-femoral angle between groups A1, B1 and groups A2, B2 (P>0.05). In the evaluation of knee X-ray radiolucent line, 2 knees of group A1 and 2 knees of group A2 had radiolucent line at prosthesis-bone interface immediately after operation, and the radiolucent line was gradually filled by new bone, without new radiolucent line. During follow-up, 1 knee of group B1 and 1 knee of group B2 had prosthesis-bone interface radiolucent line, without radiolucent line widening or prosthesis loosening. Conclusion TMT is recommended in patients less than 65 years old, and the two types of prostheses are available for patients nore than 65 years old. However, the long-term effectiveness of the two types of prosthesis in patients of different ages needs further follow-up.