Shaowen Zhu

A methodological, systematic review of evidence-based independent risk factors for surgical site infections after spinal surgery

ObjectiveTo identify the independent risk factors, based on available evidence in the literature, for patients developing surgical site infections (SSI) after spinal surgery.MethodsNon-interventional studies evaluating the independent risk factors for patients developing SSI following spinal surgery were searched in Medline, Embase, Sciencedirect and OVID. The quality of the included studies was assessed by a modified quality assessment tool that had been previously designed for observational studies. The effects of studies were combined with the study quality score using a best-evidence synthesis model.ResultsThirty-six observational studies involving 2,439 patients with SSI after spinal surgery were identified. The included studies covered a wide range of indications and surgical procedures. These articles were published between 1998 and 2012. According to the quality assessment criteria for included studies, 15 studies were deemed to be high-quality studies, 5 were moderate-quality studies, and 16 were low-quality studies. A total of 46 independent factors were evaluated for risk of SSI. There was strong evidence for six factors, including obesity/BMI, longer operation times, diabetes, smoking, history of previous SSI and type of surgical procedure. We also identified 8 moderate-evidence, 31 limited-evidence and 1 conflicting-evidence factors.ConclusionAlthough there is no conclusive evidence for why postoperative SSI occurs, these data provide evidence to guide clinicians in admitting patients who will have spinal operations and to choose an optimal prophylactic strategy. Further research is still required to evaluate the effects of these above risk factors.

Risk factors for new vertebral compression fractures after percutaneous vertebroplasty: qualitative evidence synthesized from a systematic review.

Study Design. Methodological systematic review. Objective. To identify the risk factors for new vertebral compression fractures (VCFs) in patients after percutaneous vertebroplasty (PVP) and to grade the evidence according to the quality of included studies. Summary of Background Data. PVP is an effective procedure for the treatment of VCFs. A major concern after PVP in patients with osteoporosis is the occurrence of new VCFs in the untreated vertebrae. The risk factors for new VCFs after PVP reported thus far remain controversial. These risk factors have neither been well identified or summarized. This systematic review was performed to identify the risk factors for new VCFs after PVP. Methods. Noninterventional studies evaluating the risk factors for new VCFs of patients with osteoporosis after PVP were searched in MEDLINE, EMBASE, ScienceDirect, and OVID databases (all up to November 2012). Only observational studies with eligible data were included. Quality of included studies was assessed by a modified quality assessment tool, which was previously designed for observational study. The effects of studies were combined with the study quality score using a model of best-evidence synthesis. Results. Twenty-four observational studies involving 3789 patients were included. These articles were published between 2004 and 2012. According to the quality assessment criteria for included studies, 8 studies were deemed as high-quality studies, 6 as moderate-quality studies, and 10 as low-quality studies. There were strong evidences of 3 risk factors, including lower bone mineral density, lower body mass index, intradiscal cement leakage, and vertebral height restoration. We also identified 6 moderate-evidence factors including lower body mass index, number of pre-existing vertebral fractures, thoracolumbar junction in initial VCFs, cement distraction, older age, and number of treated vertebrae. Thirteen factors were classified into the limited-evidence risk factors. Conclusion. Although there is no conclusive evidence for new VCFs of patients with osteoporosis after PVP procedure, these data provide evidence to guide the surgeon and develop optimal preventions for new VCFs after PVP. Special attention should be paid to the 3 strong-evidence risk factors. Further studies were still required to evaluate the effects of the earlier mentioned risk factors. Level of Evidence: 2

Evaluation of the stress distribution change at the adjacent facet joints after lumbar fusion surgery: a biomechanical study.

Spinal fusion surgery has been widely applied in clinical treatment, and the spinal fusion rate has improved markedly. However, its postoperative complications, especially adjacent segment degeneration, have increasingly attracted the attention of spinal surgeons. The most common pathological condition at adjacent segments is hypertrophic degenerative arthritis of the facet joint. To study the stress distribution changes at the adjacent facet joint after lumbar fusion with pedicle screw fixation, human cadaver lumbar spines were used in the present study, and electrical resistance strain gauges were attached on L1–L4 articular processes parallel or perpendicular to the articular surface of facet joints. Subsequently, electrical resistance strain gauge data were measured using anYJ-33 static resistance strain indicator with three types of models: the intact model, the laminectomy model, and the fusion model with pedicle screw fixation. The strain changes in the measurement sites indirectly reflect the stress changes. Significant differences in strain were observed between the normal and laminectomy state at all facet joints. Significant differences in strain were observed between the normal and the pedicle screw fixation fusion state at the L1/2 and L3/4 facet joints. The increased stress on the facet joints after lumbar fusion with pedicle screw fixation may be the cause of adjacent segment degeneration.

Biomechanical Analysis of Four Types of Internal Fixation in Subtrochanteric Fracture Models

To compare the biomechanical properties of four types of internal fixation (proximal femoral nail [PFN], dynamic hip screw [DHS], dynamic condylar screw [DCS], and proximal femoral locking plate [PFLP]) for different types of subtrochanteric fractures.

miR-9 Modulates Osteosarcoma Cell Growth by Targeting the GCIP Tumor Suppressor.

Osteosarcoma is the most common primary bone tumor in humans, especially in childhood. However, the genetic etiology for its pathogenesis remains elusive. It is known that microRNAs (miRNAs) are involved in the development of tumor progression. Here we show that microRNA-9 (miR-9) is a potential oncogene upregulated in osteosarcoma cells. Knockdown of miR-9 in osteosarcoma resulted in suppressed colony formation and cell proliferation. Further study identified GCIP, a Grap2 and cyclin D interacting protein, as a direct target of miR- 9. In addition, GCIP overexpression activated retinoblastoma 1 (Rb) and suppressed E2F transcriptional target expression in osteosarcoma cells. Moreover, GCIP depletion reversed miR-9 knockdown induced colony formation and cell proliferation suppression. In sum, these results highlight the importance of miR-9 as an oncogene in regulating the proliferation of osteosarcoma by directly targeting GCIP and may provide new insights into the pathogenesis of osteosarcoma.

A biomechanical study of the recovery in spinal stability of flexion/extension and torsion after the resection of different posterior lumbar structures in a sheep model.

Posterior lumbar structures are vital for spinal stability, and many researchers thought that laminectomy and facetectomy would lead to severe spinal instability. However, because living organisms have compensatory repair capacities, their long-term condition after injuries may change over time. To study the changes in the lumbar biomechanical stability of flexion/extension and torsion at different time points after the resection of various posterior structures, as well as to assess the capacity for self-healing, sheep that had undergone laminectomy or facetectomy were used as an experimental animal model. The injured sheep models included three groups: laminectomy only, laminectomy plus left total facetectomy, and laminectomy plus bilateral facetectomy. Eight nonoperative sheep were used as the control group. At 0, 6, 12, 24, and 36 weeks after injury, the lumbar specimens were harvested for biomechanical testing using the Instron 8874 servohydraulic biomechanical testing system. The changes in the injured lumbar spine were also analyzed through radiological examination. The lumbar stability in flexion/extension and torsion was severely decreased after the three types of surgery. After 6 weeks, the flexion/extension mechanical parameters recovered substantially; each parameter had returned to normal levels by 12 weeks and exceeded the intact group by 24 and 36 weeks. Torsional stiffness also recovered gradually over time. All injury groups demonstrated decreased intervertebral space and degeneration or even fusion in the small joints of the surgical segment or in adjacent segments. These results indicate that the body has the ability to repair the mechanical instability to a certain extent.

Qualitative evidence from a systematic review of prognostic predictors for surgical outcomes following cervical ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is a pathological ectopic ossification of this ligament that usually occurs in the cervical spine. For patients with cervical OPLL and neurological symptoms, surgical intervention is necessary but not always effective. Various prognostic factors influence the surgical outcome. The results of studies identifying these prognostic predictors are often inconclusive or contradictory. These predictors have not been well identified or summarized. The present study was designed to identify the prognostic predictors for the surgical outcome of cervical OPLL based on the available evidence in the literature. Non-interventional studies were searched in Medline, Embase, Science Direct, OVID and the Cochrane library. Forty-two observational studies involving 2791 patients were included. The quality of the included studies was assessed with a modified quality assessment tool, which was originally designed for use with observational studies. The effects of the studies were combined with the study quality score using a model of best-evidence synthesis. There was strong evidence for five predictors: (i) age, (ii) duration of symptoms, (iii) pre-operative neurological score, (iv) transverse area of the spinal cord, and (v) intramedullary high signal intensity on the T2-weighted MRI. We also identified eight predictors with moderate supporting evidence, seven with limited evidence, four with conflicting evidence and four predictors without supporting evidence. While there is no conclusive evidence regarding the surgical outcomes following cervical OPLL, these data provide evidence to guide the clinician in choosing an optimal therapeutic strategy for patients with cervical OPLL. Further research is necessary to fully evaluate the effects of the predictors described in this study.

A biomechanical comparison of four different fixation methods for midshaft clavicle fractures

Clavicle fractures may occur in all age groups, and 70%–80% of clavicle fractures occur in the midshaft. Many methods for treating midshaft clavicular fractures have been reported and remain controversial. To provide some guidance for clinical treatment, 30 artificial polymethyl methacrylate models of the clavicle were sewn obliquely at the midshaft to simulate the most common type of clavicular fractures, and the fracture models were divided into five groups randomly and were fixed as follows: the reconstruction plates were placed at the superior position of the fracture model (R-S group), the reconstruction plates were placed at the anteroinferior position of the fracture model (R-AI group), the locking plates were placed at the superior position (L-S group), the locking plates were placed at the anteroinferior position (L-AI group); and the control models were unfixed (control group). The strain gauges were attached to the bone surface near the fracture fragments, and then, the biomechanical properties of the specimens were measured using the compression test, torsion test and three-point bending test. The results showed that plate fixation can provide a stable construct to help with fracture healing and is the preferred method in the treatment of clavicle fractures. The locking plate provides the best biomechanical stability when placed at the anteroinferior position, and this surgical method can reduce the operation time and postoperative complications; thus, it would be a better choice in clinical practice.

THE BIOMECHANICAL EFFECTS OF DIFFERENT INTERNAL FIXATIONS IN THE TREATMENT OF FEMORAL NECK FRACTURES

The objective of this study was to contrast the biomechanical effects of standard internal fixations for femoral neck fracture treatment and provide a theoretical basis for the selection of the ideal internal fixation in the clinic. Twelve artificial PMMA femoral models were selected, and the central necks of the specimens were sawn with a electric saw at Pauwels angle of 70° to form an adduction-type femoral neck fracture model. After anatomic reduction, we fixed the specimens respectively with the DHS, three hollow screws, PFN, and dynamic sleeve three-wing screw according to the operative approach. Instron-8874 servo-hydraulic mechanical testing machine was used to fix the specimens which simulated uniped standing. We selected 15 key points on the proximal femur as test points and gave the model gradation loading at the rate of 10 mm/min with linear load 0 ~ 1200 N. The strain of each point under 1200 N load, head sink displacement under different loads, and the strain of eight points on principal pressure side were measured. A peak was observed at the eight resistance strain gages at 1200 N load, with the strain values of the DHS, three hollow screws, PFN, and dynamic sleeve three-wing screw were (-700 ± 35), (-756 ± 14), (-1362 ± 136), and (3024 ± 127) μe, showing statistical significance (P < 0.01). Under the same load, the head sink displacement in the group with the dynamic sleeve three-wing screw was greater than the hollow screws and PFN groups (P < 0.01), but smaller than the DHS group (P < 0.01). The strain values at the eight resistance strain gages in the group with the dynamic sleeve three-wing screw was larger than the other three groups under the same load, showing statistical significance (P < 0.01), and the strain values demonstrated an increasing trend with the increase of load at the same fixation group. The dynamic sleeve three-wing screw has good biomechanical stability for the treatment of femoral neck fractures, which can be applied in clinical practice.