Objective To evaluate the effecof bilateral ovariectomy combined with hormone injection on the bone mineral density and biomechanical property of sheep proximal femu.Method16 healthy adulsheep were divided into the sham operation group (n=8) and the experimengroup (n=8) randomly .Bilateral ovariewere only exposed in the sham operation group .The ex-perimengroup waperformed bilateral ovariectomy (OVX) and began to conducthe intramusculainjection of methylprednisolone (0 .45 mg · kg -1 · d-1 ) aftepostoperative 1 month fo10 month.The bone density (BD) of all sheep proximal femuwameas-ured before OVX and in postoperative 1 yea.The compression tesand the axial pullouteswere performed to evaluate biome-chanical property of postoperative 1 yeaproximal femu.ResultBD of proximal femubefore surgery had no statistically signifi-candifference between the two group,and which in the sham operation group had no statistically significandifference between before and aftesurgery (P＞0 .05) .BD of proximal femuin postoperative 1 yeain the experimengroup wasignificantly de-creased and significantly lowethan thain the sham operation group (P＜0 .05) .The maximal compression stresand the energy absorption value in the experimengroup were significantly lowethan those in the sham operation group with statistically signifi-candifferences(P＜0 .05);the maximal axial pulling force and the energy absorption value in the experimengroup were signifi-cantly lowethan those in the sham operation group with statistically significandifference (P>0 .05) .Conclusion The method of bilateral ovariectomy combined with hormone injection can significantly decrease BD and biomechanical intensity of sheep proximal femu.

The purpose of this study was to assess the factors affecting caudal screw loosening after spinopelvic fixation for adult patients with spinal deformity. This meta-analysis calculated the weighted mean difference (WMD) and odds ratio (OR) using Review Manager ver. 5.3 (RevMan; Cochrane, London, UK). The loosening group was older than the control group (WMD, 2.17; 95% confidence interval [CI], 0.48–3.87; p=0.01). The S2 alar-iliac (S2AI) could prevent the caudal screw from loosening (OR, 0.43; 95% CI, 0.20–0.94; p=0.03). However, gender distribution (p=0.36), the number of fusion segments (p=0.24), rod breakage (p=0.97), T-score (p=0.10), and proximal junctional kyphosis (p=0.75) demonstrated no difference. Preoperatively, only pelvic incidence (PI) in the loosening group was higher (WMD, 5.08; 95% CI, 2.71–7.45; p<0.01), while thoracic kyphosis (p=0.09), lumbar lordosis (LL) (p=0.69), pelvic tilt (PT) (p=0.31), pelvic incidence minus lumbar lordosis (PI–LL) (p=0.35), sagittal vertical axis (SVA) (p=0.27), and T1 pelvic angle (TPA) demonstrated no difference (p=0.10). PI–LL (WMD, 6.05; 95% CI, 0.96–11.14; p=0.02), PT (WMD, 4.12; 95% CI, 0.99–7.26; p=0.01), TPA (WMD, 4.72; 95% CI, 2.35–7.09; p<0.01), and SVA (WMD, 13.35; 95% CI, 2.83–3.87; p=0.001) were higher in the screw loosening group immediately postoperatively. However, TK (p=0.24) and LL (p=0.44) demonstrated no difference. TPA (WMD, 8.38; 95% CI, 3.30–13.47; p<0.01), PT (WMD, 6.01; 95% CI, 1.47–10.55; p=0.01), and SVA (WMD, 23.13; 95% CI, 12.06–34.21; p<0.01) were higher in the screw loosening group at the final follow-up. However, PI–LL (p=0.17) demonstrated no significant difference. Elderly individuals were more susceptible to the caudal screw loosening, and the S2AI screw might better reduce the caudal screw loosening rate than the iliac screws. The lumbar lordosis and sagittal alignment should be reconstructed properly to prevent the caudal screw from loosening. Measures to block sagittal alignment deterioration could also prevent the caudal screw from loosening.

The purpose of this research was to compare the therapeutic efficacy of multiple-rod constructs vis-a-vis 2-rod constructs in the treatment of adult spinal deformity. A systematic review and meta-analysis were performed to determine whether the multiple-rod construct outperformed the 2-rod construct. We initially retrieved 357 papers, but only 12 were chosen for further meta-analysis. The rod breakage rates in the multiple-rod and the 2-rod groups were 10.66% and 29.87%, respectively. The multiple-rod construct inhibited rod breakage (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.19–0.41; p<0.001), pseudarthrosis (OR, 0.30; 95% CI, 0.18–0.50; p<0.001) and rod fracture at the osteotomy site (OR, 0.34; 95% CI, 0.13–0.89; p=0.03). Furthermore, the multiple-rod construct reduces the risk of revision surgery (OR, 0.38; 95% CI, 0.20–0.73; p=0.04) as well as the revision risk of pseudarthrosis/rod fracture in the multiple- rod group (OR, 0.31; 95% CI, 0.18–0.52; p<0.001), but increases the risk of caudal screw loosening (OR, 4.99; 95% CI, 1.87–13.30; p=0.001). There was no statistically significant difference in proximal junctional kyphosis (PJK) parameters (p=0.85), cerebrospinal fluid leakage (p=0.09), wound infection (p =0.71), age at surgery (p=0.62), gender distribution (p=0.93), body mass index (p =0.86), smoking status (p=0.05), hospital stay (p=0.09), osteoporosis (p=0.95), CoCr rod material (p=0.15), bone morphogenetic protein-2 (p=0.58), L5/S1 interbody fusion (p=0.07), high-grade osteotomies (p=0.07), the number of fusion levels (p=0.11), operation time (p=0.30), and blood loss volume (p=0.34). Regarding radiographic parameters, only preoperative sagittal vertical axis was found to be higher (weight means difference [WMD], 25.60; 95% CI, 15.43–35.77; p<0.001) in the multiple-rod group. There was no difference in preoperative Oswestry Disability Index (ODI) (WMD, −3.32; 95% CI, −7.38 to 0.73; p=0.11), but the multiple-rod group had a lower ODI at follow-up (WMD, −7.71; 95% CI, −11.62 to −3.86; p<0.001). Multiple-rod constructs could prevent rod breakage and pseudarthrosis while also lowering the revision rate, resulting in a better clinical outcome than the 2-rod construct. Nonetheless, due consideration should be given to PJK and screw loosening in multiple-rod constructs, possibly due to the increased stiffness caused by the multiple-rod structure.