Literature studies showed a very wide range of pedicle screw loosening rates after thoracolumbar stabilization, ranging from less than 1 to 15 % in non-osteoporotic patients treated with rigid systems and even higher in osteoporotic subjects or patients treated with dynamic systems. Firstly, this paper aims to investigate how much this complication is affecting the success rate of pedicle screw fixation, in both non-osteoporotic and osteoporotic patients, and to discuss the biomechanical reasons which may be related to the variability of the rates found in the literature. The secondary aim was to summarize and discuss the published definitions and conventions about screw loosening from a clinical and radiological point of view. Narrative literature review. Screw loosening appears to be a minor problem for fixation and fusion of healthy, non-osteoporotic bone. Pedicle screw fixation in osteoporotic bone is believed to be at risk of loosening, but clinical data are actually scarce. Both expandable and augmented screws may be a viable option to reduce the risk of loosening, but clinical evidence is missing. Posterior motion-preserving implants seems to have a significant risk of screw loosening. Standardization appears to be lacking regarding the radiological assessment. Marked differences in the loosening rates found based either on planar radiography or on CT scanning were observed. Reported loosening rates primarily depended on the protocol used for the clinical examination during follow-up and on the conventions used for the radiological assessment. Aiming to a better comparability of published data, we recommend the authors of clinical studies to describe which criteria were used to assess a loosened screw, as well as the protocol of the clinical follow-up examination. Low-dose CT should be used for the assessment of screw loosening whenever possible.

Pedicle screw loosening: a clinically relevant complication?

BACKGROUND Minimally invasive transforaminal lumbar interbody fusion (TLIF)-or MI-TLIF-has been increasing in prevalence compared with open TLIF (O-TLIF) procedures. The use of MI-TLIF is an evolving technique with conflicting reports in the literature about outcomes. OBJECTIVE To investigate the impact of MI-TLIF in comparison with O-TLIF for early and late outcomes by using the Visual Analog Scale for back pain (VAS-back) and the Oswestry Disability Index (ODI). Secondary end points include blood loss, operative time, radiation exposure, length of stay, fusion rates, and complications between the 2 procedures. METHODS During August 2014, a systematic literature search was performed identifying 987 articles. Of these, 30 met inclusion criteria. A random-effects meta-analysis was performed by using both pooled and subset analyses based on study type. RESULTS Our meta-analysis demonstrated that MI-TLIF reduced blood loss (P < .001), length of stay (P < .001), and complications (P = .001) but increased radiation exposure (P < .001). No differences were found in fusion rate (P = .61) and operative time (P = .34). A decrease in late VAS-back scores was demonstrated for MI TLIF (P < .001), but no differences were found in early VAS-back, early ODI, and late ODI. CONCLUSION MI-TLIF is associated with reduced blood loss, decreased length of stay, decreased complication rates, and increased radiation exposure. The rates of fusion and operative time are similar between MI-TLIF and O-TLIF. Differences in long-term outcomes in MI-TLIF vs O-TLIF are inconclusive and require more research, particularly in the form of large, multi-institutional prospective randomized controlled trials. ABBREVIATIONS CI, confidence intervalMCID, minimal clinically important differenceMI-TLIF, minimally invasive transforaminal lumbar interbody fusionODI, Oswestry Disability IndexO-TLIF, open transforaminal lumbar interbody fusionVAS, Visual Analog Scale.

Surgical Outcomes for Minimally Invasive vs Open Transforaminal Lumbar Interbody Fusion: An Updated Systematic Review and Meta-analysis.

Purpose. This study was to report the clinical use of biomimetic nanohydroxyapatite/polyamide 66 (n-HA/PA 66) mesh cages in anterior cervical corpectomy and fusion (ACCF) surgery. Method. 95 patients who underwent single level anterior cervical corpectomy and fusion for cervical spondylosis myelopathy (CSM) in our hospital were reviewed and divided into 2 groups according to using nanohydroxyapatite/polyamide mesh cage and titanium mesh cage (TMC). Demographic data of patients and surgical, clinical, and radiological data before operation and at last follow-up were collected and compared. Result. The operation time, surgical blood loss, complications, and Japanese Orthopaedic Association scores (JOA scores) of two groups were similar. At the last follow-up both the two groups obtained 100% solid bone fusion, but the TMC group had higher rate of severe cage subsidence than the n-HA/PA 66 group (27% versus 2%). Conclusion. Nanohydroxyapatite/polyamide 66 mesh cage is safe and effective in ACCF and can be a substitution to titanium mesh cage.

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Clinical use of the nanohydroxyapatite/polyamide mesh cage in anterior cervical corpectomy and fusion surgery

The relationships between low back pain and lumbar lordosis: a systematic review and meta-analysis.

Background The maintenance of horizontal gaze is an essential function of upright posture and global sagittal spinal alignment. Horizontal gaze is classically measured by the chin-brow vertical angle (CBVA), which is not readily measured on most lateral spine radiographs. Objective To evaluate relations between CBVA and the slope of the line of sight, the slope of McGregor's line (McGS), and Oswestry Disability Index. Methods Patients were identified from a single center database of 531 spine patients who underwent full-body EOS x-rays. Correlations between CBVA, the slope of the line of sight, and McGS were assessed. Using a quadratic regression with Oswestry Disability Index and CBVA, windows of low disability were identified. Comparison of sagittal spinopelvic parameters was carried out between patients with "ascending gaze" and "neutral position." Results Three hundred three patients were included (74% female, mean age 54.8 years, body mass index 26.6 ± 6.0 kg/m). CBVA strongly correlated with the slope of the line of sight (r = 0.996) and McGS (r = 0.862). Regression studies between Oswestry Disability Index and CBVA yielded a range of values corresponding to low disability (-4.7 degrees to 17.7 degrees). Similarly, a low disability range for the slope of the line of sight (-5.1 degrees to 18.5 degrees) and McGS (-5.7 degrees to 14.3 degrees) was computed. Patients with "ascending gaze" had a worse spinopelvic alignment than "neutral position" patients. Conclusion The slope of the line of sight and McGS correlated strongly with CBVA and can be used as surrogate measures. The range of values for these measures corresponding to low disability was identified. These values can be used as a general guideline to assess alignment for diagnostic purposes. Cervical compensatory mechanism may modify the natural head position in sagittally misaligned patients. Abbreviations CBVA, chin-brow vertical angleHRQoL, health-related quality of lifeMcGS, slope of McGregor's lineODI, Oswestry Disability IndexSLs, slope of the line of sight.

Natural Head Posture in the Setting of Sagittal Spinal Deformity: Validation of Chin-Brow Vertical Angle, Slope of Line of Sight, and McGregor's Slope With Health-Related Quality of Life

Purpose
A comparative study of the spinopelvic sagittal alignment in patients with lumbar disc degeneration or herniation (LDD/LDH) in normal population was designed to analyse the role of sagittal anatomical parameter (pelvic incidence, PI) and positional parameters in the pathogenesis and development of the disease. Several comparative studies of these patients with asymptomatic controls have been done. However, in previous studies without lumbar MRI, a certain number of asymptomatic LDD patients should have been included in the control group and then impacted on the results.

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The characteristics of spinopelvic sagittal alignment in patients with lumbar disc degenerative diseases

Purpose
The titanium mesh cage (TMC) is a typical metal cage device which has been widely used in cervical reconstruction for decades. Nano-hydroxyapatite/polyamide-66 (n-HA/PA66) cage is a novel biomimetic non-metal cage device growing in popularity in many medical centres in recent years. There has been no comparison of the efficacy between these two anterior reconstructing cages. The purpose of this study was to compare the radiographic and clinical outcomes of these two different devices.

Comparison of anterior cervical fusion by titanium mesh cage versus nano-hydroxyapatite/polyamide cage following single-level corpectomy

A spatiotemporal release platform based on pH/ROS stimuli-responsive hydrogel in wound repairing.

A spatiotemporal release platform based on pH/ROS stimuli-responsive hydrogel in wound repairing

Background The new surgical procedure of full-endoscopic interlaminar lumbar discectomy (FILD) has achieved favorable effects in the treatment of lumbar disc herniation (LDH). Along with the wide range of applications of FILD, a series of complications related to the operation has gradually emerged. Objective To describe the types, incidences, and characteristics of complications following FILD and to explore preventative and treatment measures. Study design Retrospective, observational study. Setting A spine center affiliated with a large general hospital. Method In total, 479 patients with LDH underwent FILDs that were performed by a single experienced spine surgeon between January 2010 and April 2013. Data concerning the complications were recorded. Results All 479 cases successfully underwent the procedure. A total of 482 procedures were completed. The mean follow-up time was 44.3 months with a range of 24 to 60 months. The average patient age was 47.8 years with a range of 16 to 76 years. Twenty-nine (6.0%) related complications emerged, including 3 cases (0.6%) of incomplete decompression in which the symptoms gradually decreased following 3 - 6 weeks of conservative treatment, 2 cases (0.4%) of nerve root injury in which the patients recovered well following 1 - 3 months of neurotrophic drug and functional exercise treatment, 15 cases (3.1%) of paresthesia that gradually improved following 1 - 8 weeks of rehabilitation exercises and treatment with mecobalamin and pregabalin, and 9 cases of recurrent herniation (1.9%). The latter condition was controlled in 4 cases with a conservative method, and 5 of these cases underwent reoperations that included 3 traditional open surgeries and 2 FILDs. Furthermore, the complication rate for the first 100 cases was 18%. This rate decreased to 2.9% for cases 101 - 479. The incidence of L4-5 herniation (8.2%) was significantly greater than that of L5-S1 (4.5%). Limitations This is a retrospective study, and some bias exists due to the single-center study design. Conclusion FILD is a surgical approach that has a low complication rate. Incomplete decompression, nerve root injury, paresthesia, and recurrent herniation were observed in our study. Some effective measures can prevent and reduce the incidence of the complications including strict indications for surgery, a thorough action plan, and a high level of surgical skill. Key words: Complication, lumbar disc herniation, lumbar discectomy, endoscopic, inter-laminar discectomy, minimally invasive spine surgery.

Qingquan Kong

Papers

The characteristics of spinopelvic sagittal alignment in patients with lumbar disc degenerative diseases

Comparison of anterior cervical fusion by titanium mesh cage versus nano-hydroxyapatite/polyamide cage following single-level corpectomy

A spatiotemporal release platform based on pH/ROS stimuli-responsive hydrogel in wound repairing.

A spatiotemporal release platform based on pH/ROS stimuli-responsive hydrogel in wound repairing

Complications of Lumbar Disc Herniation Following Full-endoscopic Interlaminar Lumbar Discectomy: A Large, Single-Center, Retrospective Study