[Virtual preoperative planning and 3D-printed templates for pre-contoured plates in treatment of acetabular posterior wall fractures].

OBJECTIVE: To evaluate the feasibility and accuracy of virtual preoperative planning and 3D-printed templates for pre-contoured plates for the treatment of posterior wall fractures of the acetabulum. METHODS: A retrospective analysis of 29 patients with posterior acetabular wall fractures treated between August 2017 and March 2021 were divided into 2 groups based on whether to use preoperative virtual planning and 3D printed template. In 3D-printing group, there were 14 patients, including 10 males and 4 females； aged from 21 to 53 years old；CT-based virtual surgical planning was done using Mimics and 3-Matic software and 3D-printed templates for pre-contoured plates were adopted. In conventional group, there were 15 patients, including 10 males and 5 females；aged from 19 to 55 years old；conventional method of intra-operative contouring to adapt the plate to the fracture region was adopted. Blood loss, surgical time, radiographic quality of reduction, and hip function were compared between groups. RESULTS: The difference in operation time and intraoperative blood loss was significant（P<0.05）. Twenty-three patients were followed up from 12 to 30 months, and the fractures in both groups healed with a healing time of 3 to 6 months. At the last follow-up, the Merle d'Aubign-Postel score of the 3D printed group was lower than that of the conventional group（P<0.05）, with no significant differences in walking ability, hip mobility and total score（P>0.05）. In 3D printing group, 6 cases were excellent, 5 cases were good, 3 cases were fair；in conventional group, 5 cases were excellent, 5 cases were good, 4 cases were fair, 1 case was worse；no significant difference between two groups（P>0.05）. CONCLUSION: Virtual preoperative planning and 3D-printed templates for pre-contoured plates can reduce operative time and the blood loss of surgery, improve the quality of reduction. This method is efficient, accurate and reliable to treat acetabular posterior wall fractures.

Cross-cultural translation of the Western Ontario Cuff Index in Chinese and its validation in patients with rotator cuff disorders.

BACKGROUND: The Western Ontario Rotator Cuff Index (WORC) is a scale designed to evaluate the impact of rotator cuff (RC) disorders on patients' general quality of life. Our study aims to adapt the WORC for Chinese patients and to assess its reliability, validity, and responsiveness in Chinese patients with RC disorders. METHODS: First, we developed the Chinese version of the WORC (C-WORC) in a five-step procedure of translation and cross-cultural adaptation. Next, the recruiting patients finished all three rounds of scales of the C-WORC, the Medical Outcomes Study Short-Form 36 (SF-36), and the Oxford Shoulder score (OSS). Then we calculated Cronbach's alpha, the intra-class correlation coefficient (ICC), Pearson's or Spearman's correlation coefficient (r or r s), the effect size (ES), and the standardized response mean (SRM) to evaluate the reliability, validity and responsiveness of the C-WORC, respectively. RESULTS: Overall, 124 patients with RC disorders successfully completed the first two rounds of the scales, and 108 patients completed the last round of the scales. Good or excellent internal consistency (Cronbach's alpha = 0.872-0.954) was found in the overall scale and subscales of C-WORC, as well as good or excellent test-retest reliability (ICC = 0.828-0.961). Moderate or good correlations (r/r s = 0.472-0.787) were obtained between the physical subscales of the C-WORC and the OSS and the physical subscales of SF-36; the results were also obtained for the emotions subscale of the C-WORC and the mental subscales of SF-36 (r/r s = 0.520-0.713), which, adequately illustrated that good validity was included in the C-WORC. In addition, good responsiveness was also observed in the overall scale and subscales of the C-WORC (ES = 1.57-2.27, SRM = 1.52-2.28). CONCLUSIONS: The C-WORC scale is reliable, valid and responsible for the evaluation of Chinese-speaking patients with RC disorders and would be an effective instrument.

Biomechanical comparison of pedicle screw augmented with different volumes of polymethylmethacrylate in osteoporotic and severely osteoporotic cadaveric lumbar vertebrae: an experimental study.

BACKGROUND CONTEXT: Polymethylmethacrylate (PMMA) is widely used for pedicle screw augmentation in osteoporosis. Intriguingly, there have been no biomechanical comparisons of the stability of pedicle screws augmented with different volumes of PMMA or studies of the relationship between screw stability and volume of PMMA, especially in different degrees of osteoporosis. PURPOSE: The purposes of the study reported here were to compare screw stability by different volumes of PMMA augmentation, to analyze the relationship between screw stability and PMMA volume, and to make a preliminary determination of the optimum volume of PMMA augmentation for different degrees of osteoporosis. STUDY DESIGN: This study is a biomechanical comparison of pedicle screws augmented with various volumes of PMMA in cadaveric lumbar vertebrae. METHODS: Thirty-six pedicles from 18 osteoporotic lumbar vertebrae were randomly divided into groups A0 through A5, and 36 pedicles from 18 severely osteoporotic lumbar vertebrae were randomly divided into groups B0 through B5. A different volume of PMMA was injected into each one of groups A0 through A5 (0, 0.5, 1.0, 1.5, 2.0, and 2.5 mL, respectively) and into each one of groups B0 through B5 (0, 1.0, 1.5, 2.0, 2.5, and 3.0 mL, respectively), and then pedicle screws were inserted in all vertebrae. After complete solidification of the PMMA, we examined pedicle X-rays, performed axial pullout tests, and determined the maximum axial pullout strength (Fmax) for all samples. RESULTS: No PMMA was found around the screws in groups A0 and B0. In groups A1 to A5 and B1 to B5, screws were wrapped by gradually increasing amounts of PMMA. There was no PMMA leakage or screw malpositioning in any samples. The Fmax in groups A1 through A5 increased by 32.40%, 64.42%, 116.02%, 174.07%, and 207.42%, respectively, compared with that in group A0. There were no significant differences in Fmax between groups A0 and A1, A1 and A2, A2 and A3, A3 and A4, and A4 and A5 (p>.05), but there were significant differences in Fmax between any other two groups (p<.05). The Fmax in groups B1 through B5 increased by 23.48%, 48.40%, 106.60%, 134.73%, and 210.04%, respectively, compared with that in group B0. There were no significant differences in Fmax between groups B0 and B1, B0 and B2, B1 and B2, B2 and B3, B3 and B4 (p>.05), but there were significant differences in Fmax between any other two groups (p<.05). There was a significant positive correlation between Fmax and volume of PMMA in both osteoporotic and severely osteoporotic lumbar vertebrae (p<.05). CONCLUSIONS: Polymethylmethacrylate can significantly enhance stability of pedicle screws in both osteoporotic and severely osteoporotic lumbar vertebrae. There is a significant positive correlation between screw stability and volume of PMMA. Within a certain range, nevertheless, increasing the volume of PMMA does not significantly improve screw stability. We suggest that 1.5 and 3 mL, respectively, are the volumes of injected PMMA that will optimize pedicle screw stability in osteoporotic and severely osteoporotic lumbar vertebrae.

Biomechanical Comparison of Pedicle Screw Augmented with Different Volumes of Polymethylmethacrylate in Osteoporotic and Severely Osteoporotic Synthetic Bone Blocks in Primary Implantation: An Experimental Study.

This study was designed to compare screw stabilities augmented with different volumes of PMMA and analyze relationship between screw stability and volume of PMMA and optimum volume of PMMA in different bone condition. Osteoporotic and severely osteoporotic synthetic bone blocks were divided into groups A0-A5 and B0-B5, respectively. Different volumes of PMMA were injected in groups A0 to A5 and B0 to B5. Axial pullout tests were performed and F max was measured. F max in groups A1-A5 were all significantly higher than group A0. Except between groups A1 and A2, A3 and A4, and A4 and A5, there were significant differences on F max between any other two groups. F max in groups B1-B5 were all significantly higher than group B0. Except between groups B1 and B2, B2 and B3, and B4 and B5, there were significant differences on F max between any other two groups. There was significantly positive correlation between F max and volume of PMMA in osteoporotic and severely osteoporotic blocks. PMMA can significantly enhance pedicle screw stability in osteoporosis and severe osteoporosis. There were positive correlations between screw stability and volume of PMMA. In this study, injection of 3 mL and 4 mL PMMA was preferred in osteoporotic and severely osteoporotic blocks, respectively.

Local Treatment of Osteoporotic Sheep Vertebral Body With Calcium Sulfate for Decreasing the Potential Fracture Risk: Microstructural and Biomechanical Evaluations.

STUDY DESIGN: In this study, calcium sulfate (CS) was injected through pedicle into the osteoporotic vertebral body in vivo in sheep, and micro-computed tomography analysis, histologic observation, and biomechanical test were performed. OBJECTIVE: To investigate the improvement on microstructure and biomechanical performance of lumbar vertebrae augmented with CS in osteoporotic sheep. SUMMARY OF BACKGROUND DATA: The present treatments for osteoporosis relies on systemic medications intended to increase the bone mineral density (BMD). Although effective, these time-consuming medications provide little protection from fracture in the "early period" after initiation of therapy. In this regard, the strategy of local treatment is to target specific areas of the skeletal system that are prone to osteoporotic fractures. However, there is little or no research focused on local treatment of osteoporotic vertebrae with CS. METHODS: Eight female sheep were induced to osteoporosis with bilateral ovariectomy and methylprednisolone administration for 12 months. After successful establishment of an osteoporotic model, lumbar vertebrae (L1-L4) in every sheep were randomly divided into 2 groups: CS group and control group (2 vertebrae in each group in every sheep). CS was injected into the vertebral body transpedicularly in the CS group and no treatments were performed in the control group. Three months later, all sheep were killed and all L1-L4 vertebrae were harvested. Thereafter, microstructure and biomechanical performance of the cancellous bone of the vertebral body were assessed through micro-computed tomography analysis, histologic observation, and biomechanical test, respectively. RESULTS: After a 12-month induction with ovariectomy and methylprednisolone administration, the mean BMD of the sheep lumbar vertebrae significantly decreased (>25%) compared with the value before induction, which demonstrated successful establishment of osteoporosis. Three months after injection of CS, CS was completely degraded without any remains in bone tissue and the quality of bone tissue (amount and density of the bone tissue) in the CS group was significantly higher than that in the control group. The ultimate load, stiffness, and energy absorption in the CS group were all significantly higher than those in the control group. CONCLUSIONS: The preliminary data suggest that local injection of CS can significantly improve the amount, density, and biomechanical performance of the bone trabeculae in osteoporotic vertebra. The local injection of CS could also be used as a new method to improve the physical microstructure and augment the mechanical properties in "high-risk" vertebral bodies, decreasing the potential fracture risk of patients with osteoporosis. The strict inclusion and exclusion criteria should be performed before treatment.

Comparison of 2 kinds of pedicle screws in primary spinal instrumentation: biomechanical and interfacial evaluations in sheep vertebrae in vitro.

STUDY DESIGN: Expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) were inserted in sheep vertebrae in vitro and were evaluated by performing biomechanical tests, radiographic examinations and histological observations. OBJECTIVE: The objective of the study was to compare the biomechanical and interfacial performances of EPS and PMMA-PS in sheep lumbar vertebrae in vitro. SUMMARY OF BACKGROUND DATA: It is a great challenge for orthopedic surgeons performing transpedicular fixation in the osteoporotic spine. It was reported that either the EPS or PMMA-PS could increase the screw stability. However, there are no studies comparing the 2 kinds of screws especially in primary spinal instrumentation. METHODS: A total of 60 sheep lumbar vertebrae were randomly divided into 3 groups. A pilot hole was made in advance in all samples using the same method. Thereafter, the conventional pedicle screw (CPS) was inserted directly into the pilot hole in the CPS group; the hole in PMMA-PS group was first filled with polymethylmethacrylate (PMMA; 1.0 mL) and then inserted with CPS; and the EPS was inserted directly into the vertebrae in EPS group. After a period of 24 hours, biomechanical tests were performed to evaluate screw stability, and x-ray examination, micro-computerized tomography analysis, and histologic observation were performed to evaluate the interface between screw and bone. RESULTS: Compared with the stability of CPS, those of EPS and PMMA-PS were significantly enhanced. However, no significant differences were detected between the stabilities of EPS and PMMA-PS. The PMMA surrounding the screw blocked direct contact between bone and screw and formed a "screw-PMMA-bone" interface in the PMMA-PS group. There was a "screw-bone" interface in both CPS and EPS groups. Nevertheless, the expanded anterior part of EPS formed a claw-like structure pressing the surrounding bone trabeculae, which made the local bone tissue more compacted and denser than that in the CPS group. CONCLUSIONS: EPS can enhance the screw stability as markedly as the traditional PMMA-PS in primary surgery, and EPS can form a better immediate interface between screw and bone compared with PMMA-PS. EPS also can effectively avoid thermal injury, leakage, and compression caused by PMMA. A great feasibility was proved in this study to perform comparisons between the 2 kinds of pedicle screws in osteoporotic sheep vertebrae in vivo in the further research. In conclusion, we propose that EPS has a great application potential in augmentation of screw stability in the clinic.

Comparison of expansive pedicle screw and polymethylmethacrylate-augmented pedicle screw in osteoporotic sheep lumbar vertebrae: biomechanical and interfacial evaluations.

BACKGROUND: It was reported that expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. METHODOLOGY/PRINCIPAL FINDINGS: After successful induction of osteoporotic sheep, lumbar vertebrae in each sheep were randomly divided into three groups. The conventional pedicle screw (CPS) was inserted directly into vertebrae in CPS group; PMMA was injected prior to insertion of CPS in PMMA-PS group; and the EPS was inserted in EPS group. Sheep were killed and biomechanical tests, micro-CT analysis and histological observation were performed at both 6 and 12 weeks post-operation. At 6-week and 12-week, screw stabilities in EPS and PMMA-PS groups were significantly higher than that in CPS group, but there were no significant differences between EPS and PMMA-PS groups at two study periods. The screw stability in EPS group at 12-week was significantly higher than that at 6-week. The bone trabeculae around the expanding anterior part of EPS were more and denser than that in CPS group at 6-week and 12-week. PMMA was found without any degradation and absorption forming non-biological "screw-PMMA-bone" interface in PMMA-PS group, however, more and more bone trabeculae surrounded anterior part of EPS improving local bone quality and formed biological "screw-bone" interface. CONCLUSIONS/SIGNIFICANCE: EPS can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in initial surgery in osteoporosis. EPS can form better biological interface between screw and bone than PMMA-PS. In addition, EPS have no risk of thermal injury, leakage and compression caused by PMMA. We propose EPS has a great application potential in augmentation of screw stability in osteoporosis in clinic.