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Few researchers have verified the clinical efficacy and safety of the modified unilateral extrapedicular approach (mUEP) applied to the percutaneous kyphoplasty (PKP) in comparative studies with other puncture techniques. Compared with the bilateral transpedicular approach (BTP), whether mUEP PKP is a preferred treatment for lumbar osteoporotic vertebral compression fracture (OVCF) remains unclear.Patients treated by PKP for single-level lumbar OVCF in our institution from September 2019 to December 2020 were retrospectively enrolled. Patients were grouped according to the puncture techniques. Clinical and radiologic outcomes were evaluated preoperatively, postoperatively, and at follow-up. The clinical evaluation was performed by using visual analog scale for pain relief and Oswestry Disability Index for health status. Radiologic measurements contained anterior vertebral height, kyphotic angle, and bone cement distribution.In total, 76 patients with a mean follow-up duration of 16.6 months were enrolled, including 34 patients in the mUEP PK group and 42 patients in the BTP PKP group. In the mUEP group, operation time, fluoroscopy times, and injected cement volume were significantly less than that in the BTP group (P0.01). Both visual analog scale and Oswestry Disability Index scores of all patients decreased significantly after surgery (P0.01), with no significant differences between the 2 groups at each follow-up. Both mUEP PKP and BTP PKP showed significant anterior height restoration and kyphotic angle correction (P0.01), with no significant differences between the 2 groups at each follow-up. Meanwhile, the mUEP PKP reduced the incidence of intraspinal cement leakage (P0.05), and no facet joint violation was found in mUEP PKP.mUEP PKP could be clinically and radiographically equivalent to BTP PKP. However, it has advantages in reducing operation time and fluoroscopy times, lowering the risk of intraspinal cement leakage, and preventing the presence of facet joint violation. Compared with BTP PKP, the mUEP PKP seems to be an effective and alternative puncture technique for the treatment of lumbar OVCF after appropriate patient selection.

Objective This meta-analysis was conducted to evaluate the therapeutic effects in clinical and radiologic outcomes of a self-locking stand-alone cage (SSC) and cage-with-plate (CP) for multilevel anterior cervical discectomy and fusion (ACDF). Methods A systematic search was performed for all comparative studies reported up to August 2018. Operative time, hospital stay, intraoperative blood loss, Japanese Orthopedic Association score, Neck Disability Index (NDI), cervical and segmental Cobb angle, intervertebral height, fusion rate, incidence of subsidence, dysphagia, and adjacent segment degeneration were analyzed with the RevMan 5.3.3 software. Results A total of 15 studies were included. There was no difference regarding preoperative or postoperative Japanese Orthopedic Association score, Neck Disability Index, segmental Cobb angle and intervertebral height, preoperative cervical Cobb angle, fusion rate, incidence of subsidence, and adjacent segment degeneration between the SSC and CP group (P > 0.05). However, the SSC group had shorter operative time (mean difference [MD], −11.35; 95% confidence interval [CI], −16.24 to −3.66) and hospital stay (MD, −0.64; 95% CI, −1.21 to −0.06), less intraoperative blood loss (MD, −13.22; 95% CI, −19.03 to −7.41) and postoperative cervical Cobb angle (MD, −0.70; 95% CI, −1.35 to −0.06), and lower incidence of dysphagia significantly (odds ratio, −0.57; 95% CI, 0.40–0.82) (P Conclusions ACDF with SSC and CP in multilevel cervical spondylosis achieved similar clinical relief. Although CP maintained better cervical lordosis, SSC contributed to less surgical pain and fewer complications. ACDF with SSC is safe and efficient in treating multilevel cervical spondylosis.

Purpose To determine how center of rotation (COR) changes and what affects changes in COR after cervical arthroplasty. Methods A systematic literature review of in vivo clinical studies comparing the location of the COR before and after cervical arthroplasty with different artificial prostheses was performed. Meta-analysis was performed using a fixed effects model where appropriate. Results A systematic review of the PubMed, EMBASE, and Cochrane Library databases was conducted. We initially identified 267 studies, of which 14 involved in vivo kinematics studies evaluating COR following cervical arthroplasty. We found that at the last follow-up, the COR location shifted anteriorly in patients from 4 studies including 85 segments, superiorly in patients from 4 studies including 98 segments, anterior-superiorly in patients from 4 studies including 290 segments, and anterior-inferiorly in patients from 1 study including 272 segments after cervical arthroplasty. The COR location showed no significant change in patients from 5 studies including 106 segments after cervical arthroplasty. Changes in COR showed a certain trend after cervical arthroplasty with different types of prostheses. Conclusions Prosthesis design affects changes in COR after cervical arthroplasty. If a constrained or semiconstrained prosthesis is chosen (2-piece implant, ball-and-socket, or ball-in-trough design), the COR location tends to shift anteriorly and/or superiorly, whereas if a nonconstrained prosthesis is chosen (3-piece implant, mobile nucleus design), the COR tends to keep the same location as preoperation. In addition, the position of the prosthesis in the intervertebral space also can affect changes in COR after cervical arthroplasty.

Background The center of rotation (COR), instantaneous center of rotation (ICR), instantaneous axis of rotation, instantaneous helical axis, finite helical axis, and helical axis of motion are important kinematic parameters for evaluating the quality of intervertebral motion of the cervical spine (QIMC). These parameters embody different concepts and are calculated using various methods. In this review, the distinctions and connections between these kinematic parameters are analyzed according to the concepts, research, and measurement techniques to provide a theoretic basis for future research and new research directions. Methods The PubMed/MEDLINE databases were searched for studies published in English related to the concepts, research, and calculation of these parameters. The included studies were classified according to the different research or calculation methods, and the proportion of each study type was calculated and analyzed. Results Forty articles were selected. The methods for analyzing the QIMC include in vivo and in vitro studies and finite element analysis. The primary methods for calculating these parameters include the method of perpendicular bisectors and the finite helical axis method. Conclusions COR was the simplest but not the most accurate parameter to evaluate the QIMC. Conversely, instantaneous helical axis/helical axis of motion were the most accurate, but relatively complex parameters to evaluate the QIMC. ICR showed dynamic changes during flexion-extension motion, but not the three-dimensional kinematic motion of the cervical spine. These parameters were equivalent only in certain situations but cannot be substituted for each other in the clinic. A dynamic radiographic in vivo study was the most convenient and frequently used research method to calculate COR, but failed to describe the dynamic movement. The method of perpendicular bisectors was widely used to calculate the COR or ICR. Therefore, a combination of new research and calculation methods to simply and effectively evaluate the QIMC requires further investigation.

To investigate the upper-extremity abduction, and lifting limitations and associated factors after anterior cervical decompression and fusion.A total of 117 patients who underwent anterior cervical decompression and fusion for cervical spondylosis were assessed retrospectively. Their upper-extremity abduction and lifting capacity after operation and manual muscle test grade for deltoid muscle strength and its sensory status were recorded. In addition, spinal cord function (Japanese Orthopaedic Association and Neck Disability Index scores) and C4-5 intervertebral height (radiographs) were assessed. Finally, high signal and ossification of posterior longitudinal ligament were observed by T2 magnetic resonance imaging and computed tomography, respectively.Seven individuals had a decrease in muscle strength, with 2 patients also exhibiting sensory defect. Six individuals had bilateral weakness of deltoid and biceps brachii and 1 of unilateral. After 8-16 months of follow-up, the abduction function and lift capacity were restored. The manual muscle test grade recovered to 5 and 4 degrees, respectively, in 6 and 1 patients. Two patients remained with sensory defect. The mean recovery time 19.7 days on average, and Japanese Orthopaedic Association scores significantly improved. Among the 117 patients, less than 2-level decompression showed upper-extremity function limitations in 1 of 67 (1.5%), whereas more than a 3-level decompression resulted in greater rate in 6 of 50 (12%), a significant difference (P0.05). No significant difference was obtained in C4-5 intervertebral heights, as well as for rates of C3-5 high signal area in magnetic resonance imaging.The rate of upper-extremity abduction and lifting limitation after anterior cervical decompression and fusion is low, indicating a good prognosis after active treatment.