[Feasibility analysis and nail planning ofS2 iliac crest screw placement in children].

OBJECTIVE: To evaluate the feasibility of S2 alar iliac screw insertion in Chinese children using computerized three-dimension reconstruction and simulated screw placement technique, and to optimize the measurement of screw parameters. METHODS: A total of 83 pelvic CT data of children who underwent pelvic CT scan December 2018 to December 2020 were retrospectively analyzed, excluding fractures, deformities, and tumors. There were 44 boys and 39 girls, with an average age of (10.66±3.52) years, and were divided into 4 groups based on age (group A:5 to 7 years old;group B:8 to 10 years old;group C:11-13 years old;group D:14 to 16 years old). The original CT data obtained were imported into Mimics software, and the bony structure of the pelvis was reconstructed, and the maximum and minimum cranial angles of the screws were simulated in the three-dimensional view with the placement of 6.5 mm diameter S2 alar iliac screws. Subsequently, the coronal angle, sagittal angle, transverse angle, total length of the screw, length of the screw in the sacrum, width of the iliac, and distance of the entry point from the skin were measured in 3-Matic software at the maximum and minimum head tilt angles, respectively. The differences among the screw parameters of S2 alar iliac screws in children of different ages and the differences between gender and side were compared and analyzed. RESULTS: In all 83 children, 6.5 mm diameter S2 iliac screws could be placed. There was no significant difference between the side of each screw placement parameter. The 5 to 7 years old children had a significantly smaller screw coronal angle than other age groups, but in the screw sagittal angle, the difference was more mixed. The 5 to 7 years old children could obtain a larger angle at the maximum head tilt angle of the screw, but at the minimum cranial angle, the larger angle was obtained in the age group of 11 to 13 years old. There were no significant differences among the age groups. The coronal angle and sagittal angle under maximum cephalic angle and minimum cranial angle of 5 to 7 years old male were (40.91±2.91)° and (51.85±3.75)° respectively, which were significantly greater than in female. The coronal angle under minimum cranial angle was significantly greater in girls aged 8-10 years old than in boys. For the remaining screw placement angle parameters, there were no significant differences between gender. The differences in the minimum iliac width, the screw length, and the length of the sacral screws showed an increasing trend with age in all age groups. The distance from the screw entry point to the skin in boys were significantly smaller than that of girls. The minimum width of the iliac in boys at 14 to 16 years of age were significantly wider than that in girls at the same stage. In contrast, in girls aged 5 to 7 years and 11 to 13 years, the screw length was significantly longer than that of boys at the same stage. CONCLUSION: The pelvis of children aged 5 to 16 years can safely accommodate the placement of 6.5 mm diameter S2 alar iliac screws, but the bony structures of the pelvis are developing and growing in children, precise assessment is needed to plan a reasonable screw trajectory and select the appropriate screw length.

Effect of RTS versus percutaneous conventional pedicle screw fixation on type A thoracolumbar fractures: a retrospective cohort study.

PURPOSE: This study aims at evaluating the effects of RTS (rotation softened trauma fixation system) compared with PCPSF (percutaneous conventional pedicle screw fixation) on type A thoracolumbar fractures. METHODS: In this retrospective cohort study, 116 patients with type A thoracolumbar fractures from March 2014 to June 2018 were enrolled. PCPSF was performed in 60 patients, meanwhile the other 56 patients accepted RTS. VAS scores, Cobb angle, anterior vertebral height (AVH) and perioperative data were compared between the two groups. RESULTS: Both groups were consistent with baseline on demographic and clinical characteristics. No significant difference was observed in VAS score between-group before and after operation. One year after surgery, the VAS score of RTS group was lower than that of PCPSF group (0.7 ± 0.3 vs. 1.5 ± 0.4). The postoperative AVH (%) in PCPSF was 82.3% (95%CI, 81.7-84.6), and 91.78% (95% CI, 91.1-92.4) in RTS. The postoperative improvement rate of AVH (%) in RTS was higher than that in PCPSF (30.6 ± 5.0 [95% CI, 29.2-32.0] vs. 22.0 ± 7.3 [95% CI, 20.2-24.2]). The postoperative Cobb angle (°) in PCPSF was 2.6 ± 3.4 (95%CI,11.7-13.5), and 7.5 ± 2.0 (95%CI,7.0-8.0) in RTS. The postoperative correction of Cobb angle (°) in RTS was higher than that in PCPSF (16.1 ± 3.8 95%CI,15.1-17.1] vs. 11.6 ± 5.2 95%CI,10.3-13.1]). CONCLUSIONS: Compared with PCPSF, RTS has advantages in restoring the anterior vertebral height and reducing local kyphosis.

Safe trajectory for an occipital condyle screw: A computer simulation study.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of posterior occipital condyle screw (OCS) placement analysis of the safe trajectory area for screw insertion. METHODS: Computed tomographic angiography scans of patients (46 males and 27 females) with normal occipitocervical structures were obtained consecutively. Vertebral artery (VA)-occiput distance <4.0 mm was defined as "unfeasible" for OCS fixation, and occipital-atlas angulation was measured to assess the feasibility of screw placement. Next, the placement of 3.5 mm diameter OCS was simulated, the probability of breach of structures surrounding occipital condyles was calculated, and placement parameters were analyzed. RESULTS: OCS placement was feasible in 91.1% (133/146) of occipital condyles, and the feasible probability also presented a significant sex-related difference: The probability was higher for males than for females (95.7% vs. 83.3%, p < 0.05). The incidence of anatomical structures injured under screw placement limitation was 18.8% (VA), 81.2% (hypoglossal canal), 59.4% (occipital-atlas joint), and 40.6% (occiput bone surface). There were no significant differences between the left and right condyles in relation to the measured parameters (p > 0.05). The screw range of motion was significantly smaller in females than in males (p < 0.05). The feasibility of OCS placement and OCS range of motion were significantly greater in the kyphosis group (>5°) than in the other two groups (p < 0.05). CONCLUSION: OCS placement is a feasible technique for occipital-cervical fusion. The male group and occipitocervical region kyphosis group had a wider available space for OCS placement. Tangent angulation may be useful for the accurate and safe placement of an OCS.

Modified Broström Repair With and Without Augmentation Using Suture Tape for Chronic Lateral Ankle Instability.

OBJECTIVE: To compare the clinical and radiological outcome between the modified Broström repair with augmentation using suture tape (MBA) and the modified Broström repair (MB) for patients with chronic lateral ankle instability. METHODS: A retrospective study was performed in Ningbo No. 6 Hospital. The study included 53 patients who underwent surgical treatment from March 2014 to July 2016 and were followed for 2 years. A total of 25 patients underwent modified Broström repair with augmentation using suture tape, and 28 patients were treated with modified Broström repair. Patients were evaluated using the American Orthopedic Foot and Ankle Scale (AOFAS) hindfoot scale, the Foot and Ankle Ability Measure (FAAM) score, range of motion (ROM), and the visual analogue scale (VAS). The talar tilt angle (TTA) and anterior talar translation (ATT) were used to evaluate the mechanical stability. All radiological outcomes were measured by two orthopaedic surgeons, with the measurements repeated 3 days later. RESULTS: The mean age of the patients was 26.6 ± 17.8 years in the MBA group and 28.1 ± 19.4 years in the MB group, and no statistical difference in preoperative data was found between two groups. There were significant differences before and after the operation within the groups. Both groups achieved satisfactory outcomes, and significant improvements (VAS, FAAM, AOFAS, TTA, and ATT) were observed between the 1-year follow-up and final follow-up (P < 0.05). The MBA group showed significant improvement in the FAAM Sport (87.1 ± 5.4 vs 78.2 ± 12.0, P = 0.001) and total scores (93.1 ± 2.3 vs 90.5 ± 5.1, P = 0.027) at the final follow-up compared with the MB group, and for the other outcomes, there were no significant differences between the two groups. CONCLUSION: The modified Broström repair with augmentation using suture tap for chronic lateral ankle instability achieves a better outcome; however, further research is necessary.