Assessment of the cross-sectional areas of the psoas major in patients with adolescent idiopathic scoliosis before skeletal maturity.

BACKGROUND: The psoas major (PM) can support the lumbar spine and plays an important role in lumbar movement and maintaining lumbar curvature. PURPOSE: To analyze morphological changes of PM and its relation with the severity of adolescent idiopathic scoliosis (AIS). MATERIAL AND METHODS: The study was conducted on patients with AIS (age range = 10-18 years) with primary lumbar scoliosis. The cross-sectional area (CSA) of the PM at the L1-L5 levels were measured. The CSA of the PM in patients with AIS was compared with the average CSA of the PM in age-matched controls. The difference in PM at the apical vertebrae level was compared with the Cobb angle to determine the association between PM imbalance and severity of scoliosis. RESULTS: The CSA of the PM was larger on the concave side than the convex side at the apical vertebrae level and other lumber levels. Patients with a larger Cobb angle had statistically higher PM imbalance at the apical vertebrae level. The CSA of the PM on both the concave and convex sides of patients with AIS were larger than the average CSA of controls aged 16-18 years; however, there was no significant difference between patients with AIS and controls aged 10-15 years. CONCLUSION: There is a significant PM imbalance in patients with AIS before skeletal maturity, and the imbalance is related to the severity of scoliosis. The morphology of PM changed with the progression of scoliosis.

An assessment of morphological and pathological changes in paravertebral muscle degeneration using imaging and histological analysis: a cross-sectional study.

BACKGROUND: The high signal of paravertebral muscle (PVM) on T2-weighted image (T2WI) is usually considered to be fatty degeneration. However, it is difficult to distinguish inflammatory edema from fatty degeneration on T2WI. The purpose of this study was to identify different types of PVM high signal in patients with low back pain (LBP) through magnetic resonance imaging (MRI) and histology. METHODS: Seventy patients with LBP underwent MRI. The signal change of multifidus both on T2WI and fat suppression image (FSI) was quantified by Image J. Furthermore, 25 of the 70 patients underwent surgery for degenerative lumbar disease and their multifidus were obtained during the operation. Histological analysis of the samples was performed by HE staining. RESULT: Three types of PVM signal changes were identified from the MRI. Type 1 (n = 36) indicated fatty degeneration characterized by a high signal on T2WI and low signal on FSI. High signal on both T2WI and FSI, signifying type 2 meant inflammatory edema (n = 9). Type 3 (n = 25) showed high signal on T2WI and partial signal suppression on FSI, which meant a combination of fatty degeneration and inflammatory edema. Histological results were consistent with MRI. Among the 25 patients who underwent surgery, type 1 (n = 14) showed adipocytes infiltration, type 2 (n = 3) showed inflammatory cells infiltration and type 3 (n = 8) showed adipocytes and inflammatory cells infiltration. CONCLUSION: From our results, there are three types of pathological changes in patients with PVM degeneration, which may help to decide on targeted treatments for LBP.

Inhibition of Rac1 activity by NSC23766 prevents cartilage endplate degeneration via Wnt/ß-catenin pathway.

Cartilage endplate (CEP) degeneration has been considered as one of important factors related to intervertebral disc degeneration (IVDD). Previous researches have showed that Rac1 played a pivotal role in chondrocyte differentiation. However, the effect of Rac1 during the process of CEP degeneration remains unclear. Herein, we explored the effect of Rac1 on CEP degeneration and elucidated the underlying molecular mechanism. We found expression of Rac1-GTP increased in human-degenerated CEP tissue and IL-1ß-stimulated rat endplate chondrocytes (EPCs). Our study revealed that Rac1 inhibitor NSC23766 treatment promoted the expression of collagen II, aggrecan and Sox-9, and decreased the expression of ADTAMTS5 and MMP13 in IL-1ß-stimulated rat EPCs. Moreover, we also found that NSC23766 could suppress the activation of Wnt/ß-catenin pathway, suggesting that the beneficial effects of Rac1 inhibition in EPCs are mediated through the Wnt/ß-catenin signalling. Besides, puncture-induced rats models showed that NSC23766 played a protective role on CEP and disc degeneration. Collectively, these findings demonstrated that Rac1 inhibition delayed the EPCs degeneration and its potential mechanism may be associated with Wnt/ß-catenin pathway regulation, which may help us better understand the association between Rac1 and CEP degeneration and provide a promising strategy for delaying the progression of IVDD.

The projection of the thoracic nerve roots and their connection with intervertebral discs: a cadaver and radiological study.

BACKGROUND: The anatomical features of the thoracic nerve roots in connection with intervertebral discs may prevent surgery-related complications and improve patients' neurological functional status during thoracic spine surgery. There is limited literature evidence regarding this concept using cadavers. PURPOSE: To elucidate the qualitative anatomical features of the thoracic nerve roots in connection with intervertebral discs. MATERIAL AND METHODS: Fifteen formalin-preserved spine specimens were used in this study. Small pieces of stainless-steel wires were placed along the root sleeves from their points of origin, after exposing the dural sac and bilateral nerve roots. The standard anteroposterior and lateral radiographs were taken after the placement of the wires. Measurements were done on radiographs using the picture archiving communication system. RESULTS: Take-off angles of the nerve roots at the coronal plane gradually increased from the level of T2 (36.1°±2.72°) to T9 (84.1°±1.84°) and from T9, it decreased to T12 (46.3° ± 2.67°). Similar variation tendency was discovered in take-off angles of the nerve roots at the sagittal plane. No consistent tendency was found both in the distance from the origin of the root sleeve to its superior and inferior vertebral endplate. Distance from the origin of the root sleeve to the posterior midline (DM) exponentially decreased from T1 (8.2 ± 0.87 mm) to T4 (6.0 ± 0.93 mm). It slowly increased from T5 (5.5 ± 0.68 mm) to T12 (10.9 ± 1.79 mm), with T5 having the smallest DM. Distance between the origins of neighboring nerve roots showed an obvious increase from the T1-T2 interval (23.1 ± 2.22 mm) to T7-T8 interval (30.9 ± 2.68 mm). However, it progressively decreased at the T10-T11 interval (26.0 ± 2.40 mm). CONCLUSION: The dimensions of the thoracic nerve roots vary greatly from T1 to T12 intervertebral discs. Sound knowledge of these anatomical features of the thoracic nerve is mandatory for the thoracic spine surgery, especially in the posterolateral approach and transforaminal endoscopic surgery.

Hidden blood loss and the influential factors after percutaneous kyphoplasty surgery.

PURPOSE: Percutaneous kyphoplasty (PKP) is a minimally invasive procedure for the treatment of osteoporotic vertebral compression fractures (OVCFs). It is generally considered that there is little blood loss during the surgery. However, a significant perioperative hidden blood loss (HBL) is neglected. This study was to examine the amount of HBL and determine the influential factors during PKP. METHODS: From January 2015 to January 2016, 115 patients with OVCFs who were scheduled to have a PKP were enrolled in this study. The factors analyzed included gender, age, body mass index (BMI), percentage of vertebral height loss, percentage of vertebral height restoration, number of fracture levels, bone mineral density (BMD), duration of symptom, cement leakage, and other internal diseases (hypertension, diabetes mellitus). According to Gross's formula, each patient's height, weight, and pre-operative and post-operative hematocrit were recorded and used for calculating the blood loss. Influential factors were further analyzed by multivariate linear regression analysis and t test. RESULTS: The mean HBL was 282 ± 162 mL (mL) and the post-operative Hb loss was 8.7 ± 5.4 g per liter (g/L). According to multivariate linear regression analysis, patients with severe vertebral height loss (P = 0.016), better vertebral height restoration (P = 0.038), and multi-segmental vertebral fractures (P = 0.000) had a higher amount of HBL. Fresh fractures (P = 0.008) and cement leakage (P = 0.004) were also important factors to increase HBL, whereas gender (P = 0.642), age (P = 0.203), BMI (P = 0.075), hypertension (P = 0.099), diabetes mellitus (P = 0.905), and BMD (P = 0.521) were not correlate with HBL. When we compared the incidence of anemia between pre-operative and post-operative, we found that the incidence of anemia was significantly associated with HBL (P = 0.000). CONCLUSIONS: HBL cannot be ignored in perioperative period, especially for poor physical condition and multiple fractures patients. Having a correct understanding of HBL can help improve clinical assessment capabilities, ensuring patients' safety.

Minimally invasive cortical bone trajectory screws placement via pedicle or pedicle rib unit in the lower thoracic spine: a cadaveric and radiographic study.

PURPOSE: To evaluate the feasibility of cortical bone trajectory (CBT) screws fixation via pedicle or pedicle rib unit in the cadaveric thoracic spine (T9-T12). METHODS: Computed tomography (CT) images of 100 patients are analyzed by multiplanar reconstruction. Ten cadaveric thoracic spines are used to insert 4.5 × 35.0 mm CBT screws at all levels from T9 to T12. RESULTS: Maximal screw length obtained by CT has a tendency to gradually increase from T9 (29.64 mm) to T12 (32.84 mm), and the difference reaches significant level at all levels except T9 versus T10 (P < 0.01). Maximal screw diameter increases from T9 (4.92 mm) to T12 (7.47 mm) and the difference reaches significant level among all levels (P < 0.01). Lateral angle increases from T9 (7.37°) to T12 (10.47°), and the difference reaches significant level among all levels except T11 versus T12. Cephalad angle from T9 to T12 are 19.03°, 22.10°, 25.62° and 27.50° (P < 0.01), respectively. The percentage of the inner and outer pedicle breakage are 2.5 and 22.5 %, respectively. The violation of lateral pedicle wall occurs at T9 and T10, especially for women at T9. CONCLUSIONS: Both radiographic and cadaveric studies establish the feasibility of CBT screws placement via pedicle or pedicle rib unit in the lower thoracic spine (T9-T12). Furthermore, our measurements are also useful for application of this technique.

Comparison of transforaminal lumbar interbody fusion performed with unilateral pedicle screw fixation or unilateral pedicle screw-contralateral percutaneous transfacet screw fixation.

PURPOSE: To determine whether unilateral pedicle screw fixation is comparable with unilateral pedicle screw and contralateral percutaneous transfacet screw fixation in single-level lumbar spinal fusion. METHODS: Fifty-eight patients were divided into either unilateral (n = 32) or unilateral pedicle screw and contralateral percutaneous transfacet screw fixation (n = 26) instrumentation groups. The operating time, blood loss, length of hospital stay, clinical outcomes, total lumbar scoliotic changes, and fusion and complication rates were compared between the two groups. RESULTS: There were no significant differences between the two groups in blood loss, length of hospital stay, clinical results, total lumbar scoliotic changes, and fusion and complication rates. There were significant differences in duration of operating time between 2 groups. CONCLUSIONS: Unilateral pedicle screw fixation may be as effective as unilateral PS with contralateral percutaneous transfacet screw fixation for the treatment of lumbar degenerative disorders.

A comparative study of two closed reduction methods for pediatric supracondylar humeral fractures.

BACKGROUND: No randomized controlled studies have confirmed the advantages of the joystick technique over the traditional manual traction. The objective of this study was to compare the results of the joystick technique and the traditional manual traction for facilitating closed reduction of pediatric supracondylar humeral fractures. METHODS: From February 2009 to December 2012, sixty eight children were included in this study. Group A included 34 fractures reduced by the joystick technique. Group B consisted of 34 fractures reduced by the traditional manual traction. Preoperative demographic data were comparable between the two groups. The operative time, fluoroscopy time, hospitalization time, time to bone union, complications were recorded in both groups. Radiologic and functional results were assessed using the Flynn scoring system. RESULTS: Closed reduction was successfully done in all the fractures of Group A while traditional closed manipulation was successfully done in 25 fractures of Group B and 9 fractures failed. There was a significant difference between the two groups in the rate of failed closed reduction (P = 0.004). The mean operative time was 30.5 ± 9.0 and 48.2 ± 16.4 min, and the mean fluoroscopy time was 25.4 ± 10.5 s and 55.0 ± 21.2 s in Group A and Group B, respectively. Both the operative time and fluoroscopy time were significantly longer in Group B (P < 0.001 and 0.001, respectively). However, there was no significant difference in terms of the mean hospitalization time, mean union time, total complications, the Flynn scores between the two groups (P > 0.05). CONCLUSIONS: The joystick technique should be chosen to facilitate closed reduction if traditional manual traction failed to yield an acceptable reduction.

Management of hangman's fracture with percutaneous transpedicular screw fixation.

PURPOSE: This study describes a percutaneous technique for C2 transpedicular screw fixation and evaluates its safety and efficacy in the treatment of patients with hangman's fracture. METHODS: Ten patients with hangman's fracture were treated by percutaneous C2 transpedicular screw fixation. There are six males and four females, who were, based on the classification of Levine and Edwards, sorted as follows: type I fracture, three cases; type II, five cases; type IIa, two cases. The causes of injury were road traffic accident in six patients and falling injury in four patients. Other associated lesions included rib fractures (7 patients), head injuries (4 patients), and fractures of extremities (6 patients). RESULTS: The new technique was performed successfully in all cases. The average operation time was 98 min (range 60-130 min) and the estimated blood loss was 25 ml (range 15-40 ml). No complications such as vascular or neural structures injuries were found intraoperatively. Postoperative CT scans demonstrated that 17 (85 %) of 20 screws were placed satisfactorily, and 3 (15 %) screws showed perforations of the pedicle wall (<2 mm). These patients were asymptomatic and no further intervention was required postoperatively. After 8-25 months follow-up (mean 15.3 months), solid fusion was demonstrated by computed tomography. All cases got well-sagittal alignment and no angulation or dislocation was found at the segment of C2-C3. There was no loss of fixation. Clinical examination showed a full range of motion in the neck in all patients. CONCLUSIONS: The fluoroscopically assisted percutaneous C2 transpedicular screw fixation method is a technically feasible and minimally invasive technique for hangman's fracture.

Minimally invasive versus open transforaminal lumbar interbody fusion: a meta-analysis based on the current evidence.

PURPOSE: This is a meta-analysis of randomized and non-randomized studies comparing the clinical and radiological efficacy of minimally invasive (MI) and conventional open transforaminal lumbar interbody fusion (open-TLIF) for degenerative lumbar diseases. METHODS: A literature search of the MEDLINE database identified 11 studies that met our inclusion criteria. A total of 785 patients were examined. Pooled estimates of clinical and radiological outcomes, and corresponding 95% confidence intervals were calculated. RESULTS: The pooled data revealed that MI-TLIF was associated with less blood loss, shorter hospital stay, and a trend of better functional outcomes when compared with open-TLIF. However, MI-TLIF significantly increased the intraoperative X-ray exposure. Both techniques had similar operative time, complication rate, and re-operation rate. CONCLUSIONS: Based on the available evidence, MI-TLIF for degenerative lumbar diseases might lead to better patient-based outcomes. MI-TLIF would be a promising procedure, but extra efforts are needed to reduce its intraoperative radiation exposure. More randomized controlled trials are needed to compare these two surgical options.

Incidence of heterotopic ossification after implantation of interspinous process devices.

OBJECT: This study aimed to investigate the incidence rate of heterotopic ossification (HO) after implantation of Coflex interspinous devices. Possible risk factors associated with HO were evaluated. METHODS: The authors retrospectively analyzed patients who had undergone single-level (L4-5) implantation of a Coflex device for the treatment of lumbar spinal stenosis. Patient data recorded were age, sex, height, weight, body mass index, smoking habits, and surgical time. Heterotopic ossification was identified through lumbar anteroposterior and lateral view radiographs. The authors developed a simple classification for defining HO and compared HO-positive and HO-negative cases to identify possible risk factors. RESULTS: Among 32 patients with follow-up times of 24-57 months, HO was detectable in 26 (81.2%). Among these 26 patients, HO was in the lateral space of the spinous process but not in the interspinous space in 8, HO was in the interspinous space but did not bridge the adjacent spinous process in 16, and interspinous fusion occurred at the level of the device in 2. Occurrence of HO was not associated with patient age, sex, height, weight, body mass index, smoking habits, or surgical time. CONCLUSIONS: A high incidence of HO has been detected after implantation of Coflex devices. Clinicians should be aware of this possible outcome, and more studies should be conducted to clarify the clinical effects of HO.

Position of Coracoid Button Predicts Loss of Reduction in Acromioclavicular Joint Dislocation Patients Treated With the Suture-Button.

BACKGROUND: Loss of reduction is the most common complication after acromioclavicular (AC) joint dislocation treated with the suture-button. Some predictors of it are known, but finding new predictors is an ongoing process. In this study, we evaluate the importance of the position of the coracoid button. MATERIALS AND METHODS: Between April 2010 and February 2017, 186 patients with AC joint dislocation were identified. All patients were managed with the same surgical technique and postoperative protocol. The position of the coracoid button was determined immediately after surgery by anterior-posterior views of the operated shoulder and was classified as medial (Group A, 42 cases), central (Group B, 85 cases) and lateral (Group C, 59 cases) positions. The main outcome measurement was loss of reduction. The main analysis was the association between the coracoid button position and loss of reduction. RESULTS: No significant difference was found in the baseline characteristics among 3 groups. During follow-up, there were 15 cases (35.7%) developing loss of reduction in Group A, 5 cases (5.9%) in Group B and 26 cases (44.1%) in Group C. The rate of loss of reduction in Groups A and C were higher than that in Group B (p < .05). Moreover, there was no significant difference in the rate of reduction loss between lateral and medial positions of the coracoid buttons (p > .05). CONCLUSION: Our results indicated that both lateral and medial positions of the coracoid buttons could predict loss of reduction in AC joint dislocation patients treated with the suture-button.

The Effect of Medial Branch Block on Postoperative Residual Pain Relieve After Percutaneous Kyphoplasty: A Randomized Controlled Trial With 12-Month Follow-up.

BACKGROUND: Percutaneous kyphoplasty (PKP) is a minimally invasive technique, and effective treatment, for an osteoporotic vertebral compression fracture (OVCF). Residual back pain is the most common complication of PKP. Medial branch block (MBB) is a treatment option for painful OVCF, it can break the vicious cycle to release short- or long-term pain. OBJECTIVES: We aimed to determine the effects of MBB on postoperative residual back pain in OVCF patients after PKP surgery. STUDY DESIGN: A randomized, controlled, single-center trial. SETTING: Medical university center and local hospitals. METHODS: A total of 198 patients were recruited and randomly assigned to either the MBB or Non-MBB group. In the MBB group, patients received MBB during PKP surgery, the injection contained a mixture of lidocaine and budesonide. The Non-MBB group was injected with normal saline in the target nerve area during PKP surgery. The primary outcome was back pain assessed by the Visual Analog Scale (VAS), and residual back pain was defined as a VAS score greater than or equal to 4. The secondary outcomes included physical function assessed by Patient-Reported Outcome Measurement Information System Physical Function (PROMIS PF) and satisfaction with surgery was assessed using the S6 satisfaction scale. All parameters were measured at baseline, 1 day, 1 week, 1 month, 3, 6, and 12 months after the intervention. RESULTS: A total of 179 patients, including 91 patients in the MBB group and 88 patients in the Non-MBB group, were included for a comprehensive assessment. The VAS score in the MBB group was significantly lower than in the Non-MBB group within a one-month follow-up. PROMIS PF score in the MBB group was significantly higher than in the Non-MBB group within a one-month follow-up. The incidence of residual back pain in the MBB group was lower than the Non-MBB group within a one-month follow-up. The MBB group had a significantly higher satisfaction rate compared with the Non-MBB group at final follow-up. LIMITATIONS: Firstly, patients are from a single institution and the sample size is small. Secondly, some of the potential factors which may lead to back pain, such as infection, new symptomatic compression fracture, and serious cement leakage, did not occur. Thirdly, the conservative treatment group is not included. Finally, we were unable to determine individual differences in pain tolerance. CONCLUSIONS: MBB can effectively relieve back pain and reduce the incidence of residual back pain in OVCF patients after PKP surgery. Besides, it can also significantly improve postoperative physical function and patients' satisfaction with treatment.

Maltol inhibits the progression of osteoarthritis via the nuclear factor-erythroid 2-related factor-2/heme oxygenase-1 signal pathway in vitro and in vivo.

Osteoarthritis (OA) is a common degenerative joint disease characterized by articular cartilage degeneration and inflammation. Currently, there is hardly any effective treatment for OA due to its complicated pathology and the severe side effects of the treatment drugs used. It has been reported that maltol, a Maillard reaction product derived from ginseng, inhibits inflammation and oxidative stress in several animal models. However, the potential anti-inflammatory effects of maltol in OA treatment are unknown. This study aimed to evaluate the anti-inflammatory effects of maltol on interleukin (IL)-1ß-induced mouse chondrocytes and protective effects of maltol on these chondrocytes in medial meniscus destabilization (DMM) OA mouse models. Mice, randomly divided into maltol (n = 15), vehicle (n = 15) and control (n = 15) groups were treated with the same dose of maltol or saline, respectively. The cartilage tissues were extracted for histological analysis 8 weeks postoperative. For the in vitro studies, chondrocytes were treated with 10 ng mL-1 IL-1ß combined with maltol at different concentrations. In vitro assays showed that the maltol pre-treatment significantly inhibited the expressions of multiple inflammatory factors induced by IL-1ß, such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor (TNF-α). In addition, maltol alleviated the degradation of the extracellular matrix (ECM) by inhibiting the expressions of matrix metalloproteinase-13 (MMP13) and thrombospondin motif 5 (ADAMTS5), as well as reversing the degradation of aggrecan and collagen II. Moreover, maltol suppressed nuclear factor kappa B (NF-κB) signaling by activating the nuclear factor-erythroid 2-related factor-2 (Nrf2) in in vitro and in vivo studies. These findings indicate that maltol reduces the inflammation induced by IL-1ß in chondrocytes. Therefore, the results of this study indicated that maltol may be a potential drug for the effective treatment of OA.

Microendoscopic anterior approach for irreducible atlantoaxial dislocation: surgical techniques and preliminary results.

STUDY DESIGN: Surgical techniques and preliminary results. OBJECTIVE: To describe and evaluate the safety and efficacy of a new minimal invasive technique for the irreducible atlantoaxial dislocation (IADD). SUMMARY OF BACKGROUND DATA: Endoscope has been widely used in minimal invasive spinal surgery. However, there are no clinical reports regarding anterior approach for IADD in the literature. METHODS: Ten consecutive patients with IADD were treated by anterior release with microendoscopic aide and subsequently reduction, anterior transarticular screw fixation and morselized autologous bone grafts. There were 3 cases of odontoid dysplasia, 4, chronic odontoid fracture, 1, odontoid absence, 1 fasilar impression, and 1 malunion of odontoid fracture. According to Symon and Lavender's classification of disability, 6 cases were moderate disability, 3 severe nonbedbound, and 1 severe bedridden. The procedure was performed by the same surgeon (Yong-Long Chi). RESULTS: The new technique was performed successfully in all cases. All the patients underwent transarticular screw fixation and anterior morselized autograft fusion. The average operation time was 120 min (range, 90 to 150 min) and the mean estimated blood loss was 150 mL (range, 100 to 250 mL). Postoperative radiographs demonstrated that 9 cases restored anatomic position and 1 had partial reduction. According to the postoperative computed tomography all the screws were appropriately placed. Follow-up after surgery, longest is 16 months and minimal 8 months with a mean of 12 months, neurologic status was improved in all patients. There was no loss of fixation and solid fusion was achieved in all cases. CONCLUSIONS: Surgical technique of microendoscopic anterior release, reduction, fixation, and fusion is safe and reliable minimally invasive for treating IADD.

Detection of dorsal screw penetration during volar plating of the distal radius fractures: A comparison of different fluoroscopic views and screw sizes.

OBJECTIVE: The objective of this study was to compare different screw lengths combined with different fluoroscopic views to detect intraoperative dorsal screw penetration in distal radius fractures treated with volar locked plating. MATERIAL AND METHODS: From April 2014 to October 2018, one hundred and eighty patients were included. We divided the patients into four groups. Intraoperative AP and lateral views were taken and sizes of the screws were chosen based on actual measurement (Group A, 45 patients). AP, lateral and tangential views were taken and sizes of the screws were also chosen based on actual measurement (Group B, 45 patients). Intraoperative AP and lateral views were taken and the selected screws were 2mm shorter than actual measurement (Group C, 45 patients). AP, lateral and tangential views were taken and the selected screws were 2mm shorter than actual measurement (Group D, 45 patients). Prominent screws were changed intraoperatively according to each view. A computed tomography (CT) was taken postoperatively to identify residual prominent screws. RESULTS: The number of dorsally prominent screws exceeding 1mm was 6 of 301 in Group A (2.0%), 15 of 290 (5.2%) in Group B, 2 of 289 in Group C (0.7%), and 2 of 282 (0.7%) in Group D. All these prominent screws (25 screws) were exchanged for shorter screws during surgery. Group A and Group B had significant difference in detecting intraoperative dorsal screw penetration (p<0.05). Group C and Group D had no significant difference in detecting intraoperative dorsal screw penetration (p>0.05). Postoperative CT identified 12 additional prominent screws with≥1mm dorsal penetration in Group A, 2 screws in Group B, 1 screw in Group C and 0 screw in Group B respectively. Significant difference was found between Group A and Group B of CT results (p<0.05) while no statistical difference was found between Group C and Group D of CT results (p>0.05). DISCUSSIONS: Tangential view helped identify screw penetration. If tangential view was not available intraoperatively, screw penetration could also be avoided by downsizing the distal locking screw by 2mm shorter than actual measurement.

Projection of the Most Anterior Line of the Spinal Canal on Lateral Radiograph: An Anatomic Study for Percutaneous Kyphoplasty and Percutaneous Vertebroplasty.

ABSTRACTPurpose: To measure the projection of the most anterior line of the spinal canal on lateral radiographs of the vertebra (C3-L5) and evaluate the efficacy of the safety line (SL) in preventing intraspinal cement leakage in percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). Materials and Methods: Fifteen adult dry-bone spine specimens were analyzed. The projection of the SL was viewed on lateral radiographs. The distance between the SL and the posterior vertebral body line (PVBL) was measured. Two groups of patients were treated by PKP, and cement injection was stopped either before the PBVL (group 1) or before the SL (group 2) under lateral fluoroscopy. The rate of cement leakage was compared between the two groups. Results: The largest distance between the SL and PVBL was at L1 (5.22 ± 0.62 mm). From L1 to L5, the distance decreased progressively to 1.05 ± 0.64 mm. Similar variation was also observed from L1 to T1 (0.19 ± 0.18 mm). The postoperative computed tomography scan was more sensitive and accurate in detecting intraspinal leakage than radiography in group 1 (p = 0.000); however, there was no significant difference in sensitivity or accuracy between methods in group 2 (p = 0.063). The rate of intraspinal cement leakage was significantly higher in group 1 than group 2 (p = 0.000). Conclusions: The operator should frequently check to ensure that cement injection has stopped upon reaching the SL. Surgeons may benefit from this quantitative anatomical study of PKP and PVP.

Vacuum Facet Phenomenon in Computed Tomography Imaging: A Sign of Instability in Degenerative Spondylolisthesis?

OBJECTIVE: The aim of the present study was to investigate the relationship between vacuum facet phenomena and lumbar instability in patients with degenerative spondylolisthesis (DS) in L4-L5. METHODS: Patients with L4-L5 DS who had both lumbosacral flexion-extension radiographs and computed tomography (CT) scans available for review from January 2016 to December 2017 were eligible for the present study. The dynamic motion index (DMI) of each patient was used to represent the percentage of slippage of L-L4 on the L5 vertebral disks on the flexion radiographs minus the percentage on the extension radiographs. The facet vacuum index refers to the average width of the facet vacuum on the left and right sides. RESULTS: A total of 67 patients with L4-L5 DS were included in the present study. Of the 67 patients, 35 had a vacuum facet phenomenon on their CT scan and 32 patients did not. The incidence of lumbar instability in the patients with a vacuum facet phenomenon was significantly greater than that in the patients without a vacuum facet phenomenon (P = 0.015). The mean DMI for the patients with a vacuum facet phenomenon was significantly greater than that for the patients without a vacuum facet phenomenon (P < 0.001). A positive linear correlation was found between the facet vacuum index and DMI for patients with a vacuum facet phenomenon (Pearson correlation coefficient, 0.597; P < 0.001). CONCLUSIONS: A linear correlation was found between the degree of segmental motion and the width of the vacuum facet phenomenon in patients with DS at L4-L5. Our study has shown that vacuum facet phenomena detected on the CT images of patients with DS are highly predictive of segmental instability.

Comparison of Hidden Blood Loss Between Three Different Surgical Approaches for Treatment of Thoracolumbar Fracture.

Purpose: To examine the hidden blood loss (HBL) in treatment of AO type A1-A3 thoracolumbar fractures with three different approaches and to explore the influential factors of HBL among patients after the surgery of internal fixation for thoracolumbar fractures. Methods: We retrospectively studied 85 patients in treatment of thoracolumbar fractures: 25 patients via percutaneous approach (Group A), 33 patients via paraspinal approach (Group B), and 27 patients via conventional open approach (Group C). The demographic information of the patients was collected. Each patient's preoperative and postoperative hematocrit were recorded and used for calculating the blood loss according to the Gross's formula. The difference of blood loss between the three groups was measured by ANOVA. And influential factors were further analyzed by multivariate linear regression analysis in each group. Results: The average HBL was 240.0 ± 65.1 mL in Group A, 313.7 ± 138.1 mL in Group B, and 382 ± 153.8 mL in Group C. There was statistical difference in the HBL between three groups (P = 0.000). However, multivariate linear regression analysis revealed that HBL of three approaches was not associated with age, gender, body mass index (BMI), percentage of height loss, percentage of height restoration, fracture type, or operation time. Conclusion: There was a substantial HBL in the treatment of thoracolumbar fractures, which was neglected by surgeons. Further investigation is necessary to study the risk factors for surgery on HBL in treatment of thoracolumbar fractures.

Factors associated with the decision for operative versus conservative treatment of displaced distal radius fractures in the elderly.

BACKGROUND: The treatment of senile distal radius fractures had not been clearly defined. The objective of this study was to identify the factors associated with the decision for operative treatment of displaced distal radius fractures in patients aged over 55 years. METHODS: Data of 318 patients with displaced distal radius fractures were collected on patient-, fracture- and surgeon-related characteristics that were plausibly related to the decision for operation. Mean comparisons or chi-squared test were used for univariate analysis of the above-mentioned factors, and then multiple logistic regression was used to identify factors associated with the decision for operation. RESULTS: Univariate analysis showed that age, osteoporosis, Charlson score, associated orthopaedic injuries requiring surgery, Orthopaedic Trauma Association (AO) and Fernandez classification, radial height, volar tilt, volar/dorsal comminution, ulnar variance, intra-articular displacement/step-off, associated distal radioulnar joint instability or radiocarpal joint dislocation and subspecialty of treating surgeons had statistically significant association with operative intervention. In the multivariate analysis, the predictors of operative intervention were younger patient age (P = 0.028), associated orthopaedic injuries requiring surgery (P = 0.020), higher AO classification (P = 0.037), higher Fernandez classification (P = 0.041), radial shortening >5 mm (P = 0.020), volar tilt > -10° (P = 0.020), volar/dorsal comminution (P = 0.020), ulnar variance >5 mm (P = 0.023), intra-articular displacement/step-off >2 mm (P = 0.004), associated distal radioulnar joint instability or radiocarpal joint dislocation (P = 0.047) and treatment by an upper extremity specialist (P = 0.038). CONCLUSION: The decision for surgery was predominantly influenced by the characteristics and severity of the fracture. Patients' age and treatment by an upper extremity specialist were also significant factors associated with a higher likelihood of operative intervention.