Background The study aimed to (1) create a series of pedicle injectors with different number of holes on the sheath especially for the Chinese elderly patients and (2) further investigate the effects of the injectors on the augmentation of pedicle screw among osteoporotic lumbar pedicle channel. Methods This study used the biomechanical test module of polyurethane (Pacific Research Laboratory Corp, USA) to simulate the mechanical properties of human osteoporotic cancellous bone. The bone cement injectors were invented based on anatomical parameters of lumbar pedicle in Chinese elderly patients. Mechanical test experiments were performed on the bone cement injectors according to the three groups, namely, a local augmentation group, a full-length augmentation group, and a control group. The local augmentation group included three subgroups including 4-hole group, 6-hole group, and 8-hole group. All holes were laterally placed. The full-length augmentation group was a straight-hole injector. The control group was defined that pedicle screws were inserted without any cement augmentation. Six screws were inserted in each group and the maximum insertion torque was recorded. After 24 h of injecting acrylic bone cement, routine X-ray and CT examinations were performed to evaluate the distribution of bone cement. The axial pull-out force of screws was tested with the help of the material testing system 858 (MTS-858) mechanical tester. Results The bone cement injectors were consisted of the sheaths and the steel rods and the sheaths had different number of lateral holes. The control group had the lowest maximum insertion torque as compared with the 4-hole, 6-hole, 8-hole, and straight pore groups (P < 0.01), but the differences between the 4-hole, 6-hole, 8-hole, and straight pore groups were no statistical significance. The control group had the lowest maximum axial pull-out force as compared with the other four groups (P < 0.01). Subgroup analysis showed the 8-hole group (161.35 ± 27.17 N) had the lower maximum axial pull-out force as compared with the 4-hole group (217.29 ± 49.68 N), 6-hole group (228.39 ± 57.83 N), and straight pore group (237.55 ± 35.96 N) (P < 0.01). Bone cement was mainly distributed in 1/3 of the distal end of the screw among the 4-hole group, in the middle 1/3 and distal end of the screw among the 6-hole group, in the proximal 1/3 of the screw among the 8-hole group, and along the long axis of the whole screw body in the straight pore group. It might indicate that the 8-hole and straight-hole groups were more vulnerable to spinal canal cement leakage. After pullout, bone cement was also closely connected with the screw without any looseness or fragmentation. Conclusions The bone cement injectors with different number of holes can be used to augment the pedicle screw channel. The pedicle screw augmented by the 4-hole or 6-hole sheath may have similar effects to the straight pore injector. However, the 8-hole injector may result in relatively lower pull-out strength and the straight pore injector has the risks of cement leakage as well as cement solidarization near the screw head.
Objective: Ankle arthroscope is the preferred tool for ankle surgeons to treat ankle impingement. However, there is no relevant report on how to improve the accuracy of arthroscopic osteotomy through preoperative planning. The aims of this study were to investigate a novel method to obtain the bone morphology in anterior and posterior ankle bony impingement through computed tomography (CT) calculation model, use this method to guide surgical decisionmaking, and compare the postoperative efficacy and actual bone cutting volume with conventional surgery.Methods: This retrospective cohort study includes 32 consecutive cases with anterior and posterior ankle bony impingement by arthroscopy from January 2017 to December 2019. Mimics software was utilized to calculate the bony morphology and measure the volume of the osteophytes by two trained software engineers. The patients were divided into the precise group (n = 15) and the conventional group (n = 17) according to whether obtain and quantify the osteophytes' morphology with CT based calculation model preoperative. All patients were evaluated clinically using visual analog scale (VAS) score, American Orthopaedic Foot and Ankle Society (AOFAS) score, active dorsiflexion and plantarflexion angle before and after surgery at both 3 months and 12 months postoperatively. We obtained the shape and volume of bone cutting through Boolean calculation. Clinical outcomes and radiological data were compared between the two groups. Results:The VAS score, AOFAS score, active dorsiflexion angle and plantarflexion angle were significantly improved in both groups postoperatively. In comparison of the VAS score, AOFAS score, and active dorsiflexion angle, the precise group were higher than the conventional group in the follow-up at 3 and 12 months postoperatively with statistical difference. The difference between the virtual bone cutting volume and the actual bone cutting volume of the anterior edge of distal tibia in the conventional group and precise group were 244.20 AE 147.66 mm 3 and 76.53 AE 168.51 mm 3 , respectively, there was statistical difference between the two groups (t = À2.927, p = 0.011). Conclusion:Using a novel method of obtaining and quantifying the bony morphology with CT-based calculation model for anterior and posterior ankle bony impingement can help guide surgical decision-making preoperatively and assist precise bone cutting during the operation, which can improve the efficacy and evaluate the accuracy of osteotomy postoperatively.
Study Design. Retrospective cohort study. Objective. To verify the clinical efficacy of a novel transoral stepwise release technique (TSRT) for the treatment of irreducible atlantoaxial dislocations (IAAD). Summary of Background Data. Anterior release for IAAD remains challenging, with a 3.2 times higher complication rate than posterior release. However, there are some patients who cannot achieve successful reduction from a posterior approach and require the higher-risk anterior release. Our work presents a novel anterior release technique that aims to minimize iatrogenic injury and associated complications from an anterior release. Materials and Methods. IAAD cases who were treated with TSRT were retrospectively studied. Primary outcomes included fusion rate, complications, and neurological function over the course of a minimum 1-year follow-up. Radiographic differences between preoperative and postoperative imaging were also considered. A preoperative prediction model for the actual release grade was developed using multivariate logistic regression based on demographic factors and the craniovertebral abnormalities identified on preoperative images, evaluating the need for higher-grade TSRT release. Results. We included 201 IAAD cases, with 42% (84/201) demonstrating degeneration of the atlantoaxial joint or anterior–hook-like dens. The reduction was achieved in all cases, with 80% (160/201) of cases only requiring relatively low-grade or grade I types TSRT release. Degeneration of the atlantoaxial joint was significantly associated with the need for higher-grade TSRT release (odds ratio:16.68, CI: 2.91–94.54, P = 0.002). The overall complication rate was 4.5% (9/201). Over the course of follow-up, the fusion rate reached 98.5%, and the American Spinal Injury Association and Japanese Orthopedic Association scores were significantly improved to 97.28 and 16.25 (P < 0.01 and P < 0.01), respectively. Conclusion. This study demonstrated that our novel TSRT anterior release technique demonstrated complication rates similar to those published in the literature for posterior release. TSRT can be used as an alternative to posterior release techniques for refractory cases or when a posterior approach is not considered viable.
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