[Locking plate fixation with fibular strut allograft versus locking plate fixation alone for the treatment of proximal humeral fractures in adults:a Meta-analysis].

OBJECTIVE: To compare the clinical efficacy of locking plate fixation with a fibular strut allograft (FA group) and locking plate fixation alone (LP group) in the treatment of proximal humeral fractures in adults by Meta-analysis. METHODS: Databases including PubMed, The Cochrane Library, Embase, Chinese BioMedical Literature Database(CBM), China National Knowledge Infrastructure(CNKI), WanFang Data, and China Science and Technology Journal Database (cpvip Database) were searched by computer from establishing to March 2020 to collect studies about locking plate fixation with fibular strut allograft versus locking plate fixation alone for proximal humeral fractures in adults. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. The postoperative humeral head height changes, neck-shaft angle changes, Constant-Murley score, American Shoulder and Elbow Surgeons(ASES)score, visual analogue scale(VAS), varus malunion rate, and screw penetration rate were compared by RevMan 5.3 software for Meta-analysis. RESULTS: Ten cohort studies were enrolled in a total of 749 patients, 300 patients in the FA group and 449 patients in the LP group. The results of Meta-analysis showed that locking plate with fibular strut allograft was superior to locking plate fixation alone in the changes in humeral head height [MD=-2.69, 95%CI(-3.24, -2.13), P<0.000 01], the changes in neck-shaft angle [MD=-5.65, 95%CI(-7.18, -4.12), P<0.000 01], Constant-Murley score [MD=9.00, 95%CI(4.26, 13.73), P=0.000 2], the ASES score [MD=5.56, 95%CI(4.29, 6.84), P=0.000 01], VAS score [MD=-0.23, 95%CI(-0.37, -0.09), P=0.001], the varus malunion rate [RR=0.22, 95%CI(0.09, 0.53), P=0.000 7] and the screw penetration rate [RR=0.26, 95%CI(0.13, 0.55), P=0.000 3], respectively.While there was no significant difference in the rate of osteonecrosis of the humeral head [RR=1.18, 95%CI(0.57, 2.45), P=0.65]. CONCLUSION: For proximal humeral fractures in adults, current evidence shows that locking plate fixation with fibular strut allograft is superior to single locking plate fixation in improving postoperative radiological outcomes and shoulder function, relieving postoperative pain, reducing varus malunion rate and screw penetration rate. However, the efficacy in decreasing the osteonecrosis rate is not clear. Due to limited quality and quantity of the included studies, more high-quality studies are required to verify the above conclusion.

Novel unilateral C1 double screw and ipsilateral C2 pedicle screw placement combined with contralateral laminar screw-rod fixation for atlantoaxial instability.

PURPOSE: To investigate the anatomical and biomechanical feasibility of the unilateral C1 double screw [pedicle screw (PS) + lateral mass screw (LMS)] and ipsilateral C2 PS combined with contralateral C2 laminar screw (LS)-rod fixation for atlantoaxial instability by comparison with traditional posterior fixation methods. METHODS: Fifteen sets of complete dry bony specimens of atlas were used for morphometric analysis. The working length, width and thickness of the C1 PSs and LMSs were manually measured. Ten fresh-frozen cervical spines (C0-C7) were used to complete the range of motion (ROM) testing in their intact condition, under destabilization and after stabilization by the following procedures: unilateral C1-C2 PS rod fixation (Group A), bilateral C1-C2 PS rod fixation (Group B), and unilateral C1 double screw and ipsilateral C2 PS combined with contralateral C2 LS rod fixation (Group C). RESULTS: The working thickness of the C1 PS was ≤ 3.5 mm in only one (1/15 = 6.7%) specimen. The other parameters were > 3.5 mm in all specimens. In the ROM test, all fixation groups showed significantly reduced flexibility in all directions compared with both the intact and destabilization groups. Further, Groups B and C showed better stability in all directions than Group A. However, no significant differences were observed between Groups B and C. CONCLUSION: The C1 unilateral lateral mass could mostly contain two screws(PS + LMS) with diameters ≤ 3.5 mm. The novel technique of unilateral C1 double screw and ipsilateral C2 PS combined with contralateral C2 LS rod fixation provided better stability than unilateral PS rod fixation and similar as bilateral PS rod fixation. Therefore, it is a feasible salvage method that provides a new insight into atlantoaxial instability. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical Influences of Transcorporeal Tunnels on C4 Vertebra Under Physical Compressive Load Under Flexion Movement: A Finite Element Analysis.

BACKGROUND: Anterior percutaneous endoscopic transcorporeal cervical discectomy is an alternative operation for cervical disc herniation. However, few reports have evaluated the biomechanical influence of tunnels on vertebrae. We compared biomechanical distinctions between intact and tunneled models of vertebrae to analyze the safety of anterior percutaneous endoscopic transcorporeal cervical discectomy based on a C2-T1 finite element (FE) model. METHODS: Groups of C2-T1 FE models were simulated with C4 tunneled by 2 methods (group A: with partial superior endplate excision; group B: without partial superior endplate excision) and various tunnel diameters (6, 8, and 10 mm). All FE models were loaded under a 1-Nm flexion moment. RESULTS: The area and maximum of stress concentrations were correlated with tunnel diameter. The distribution of stress on C4 superior endplates showed no significant difference between B6 and the intact model (P > 0.05), but significant differences with other tunneled models (P < 0.001). Maximum stress on the lateral wall of tunnels was positively correlated with tunnel diameter and induced high risks of cancellous bone fracture for diameters reaching 10 mm in group B and 8 mm in group A. CONCLUSIONS: Transcorporeal tunnel in C4 vertebrae without endplate excision should be limited with diameter of 6 mm, and a tunnel diameter >10 mm, excision of the endplate >8 mm, and excision of the center side of the endplate should also be avoided.

Adenovirus-mediated expression of vascular endothelial growth factor-a potentiates bone morphogenetic protein9-induced osteogenic differentiation and bone formation.

Mesenchymal stem cells (MSCs) are suitable seed cells for bone tissue engineering because they can self-renew and undergo differentiation into osteogenic, adipogenic, chondrogenic, or myogenic lineages. Vascular endothelial growth factor-a (VEGF-a), an angiogenic factor, is also involved in osteogenesis and bone repair. However, the effects of VEGF-a on osteogenic MSCs differentiation remain unknown. It was previously reported that bone morphogenetic protein9 (BMP9) is one of the most important osteogenic BMPs. Here, we investigated the effects of VEGF-a on BMP9-induced osteogenesis with mouse embryo fibroblasts (MEFs). We found that endogenous VEGF-a expression was undetectable in MSCs. Adenovirus-mediated expression of VEGF-a in MEFs potentiated BMP9-induced early and late osteogenic markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In stem cell implantation assays, VEGF-a augmented BMP9-induced ectopic bone formation. VEGF-a in combination with BMP9 effectively increased the bone volume and osteogenic activity. However, the synergistic effect was efficiently abolished by the phosphoinositide 3-kinase (PI3K)/AKT inhibitor LY294002. These results demonstrated that BMP9 may crosstalk with VEGF-a through the PI3K/AKT signaling pathway to induce osteogenic differentiation in MEFs. Thus, our findings demonstrate the effects of VEGF-a on BMP9-induced bone formation and provide a new potential strategy for treating nonunion fractures, large segmental bony defects, and/or osteoporotic fractures.