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find Author "YANGChen" 5 results
  • Study on Steady State Visual Evoked Potential Target Detection Based on Two-dimensional Ensemble Empirical Mode Decomposition

    Brain computer interface is a control system between brain and outside devices by transforming electroencephalogram (EEG) signal. The brain computer interface system does not depend on the normal output pathways, such as peripheral nerve and muscle tissue, so it can provide a new way of the communication control for paralysis or nerve muscle damaged disabled persons. Steady state visual evoked potential (SSVEP) is one of non-invasive EEG signals, and it has been widely used in research in recent years. SSVEP is a kind of rhythmic brain activity simulated by continuous visual stimuli. SSVEP frequency is composed of a fixed visual stimulation frequency and its harmonic frequencies. The two-dimensional ensemble empirical mode decomposition (2D-EEMD) is an improved algorithm of the classical empirical mode decomposition (EMD) algorithm which extended the decomposition to two-dimensional direction. 2D-EEMD has been widely used in ocean hurricane, nuclear magnetic resonance imaging (MRI), Lena image and other related image processing fields. The present study shown in this paper initiatively applies 2D-EEMD to SSVEP. The decomposition, the 2-D picture of intrinsic mode function (IMF), can show the SSVEP frequency clearly. The SSVEP IMFs which had filtered noise and artifacts were mapped into the head picture to reflect the time changing trend of brain responding visual stimuli, and to reflect responding intension based on different brain regions. The results showed that the occipital region had the strongest response. Finally, this study used short-time Fourier transform (STFT) to detect SSVEP frequency of the 2D-EEMD reconstructed signal, and the accuracy rate increased by 16%.

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  • COMPARISON OF PROSTHESIS WITH DIFFERENT NECK-SHAFT ANGLES FOR RECONSTRUCTION OF FEMORAL PROXIMAL ANATOMY AFTER TOTAL HIP ARTHROPLASTY

    ObjectiveTo compare the short-term effectiveness of femoral prosthesis with different neck-shaft angles for the reconstruction of proximal femoral anatomy after total hip arthroplasty (THA). MethodsBetween January 2012 and December 2013, 101 patients undergoing unilateral THA who accorded with selection criteria were selected for a retrospective study. The patients were divided into 2 groups:during THA, femoral prosthesis with 135° neck-shaft angle was used in 52 patients (group A) and femoral prosthesis with 127° neck-shaft angle was used in 49 patients (group B). There was no significant difference in gender, age, weight, body masss index, pathogeny, disease duration, preoperative neck-shaft angle, leg discrepancy, and preoperative Harris score between 2 groups (P>0.05). The postoperative Harris score was recorded to evaluate the effectiveness. And the femoral offset of the operated and contralateral sides, the change value of the femoral offset (xFO), the ratio of xFO to the offset of contralateral side (sdFO), the number of patients whose sdFO was more than 15% or less than -15% (outlier), the global offset, the height of femoral head rotation center, and leg discrepancy were measured at postoperation. ResultsOperative incision healed by first intension in 2 groups; no complication of infection, dislocation, or revision was found. All patients were followed up 12-32 months (mean, 23 months). The Harris score at last follow-up were significantly improved when compared with preoperative score in 2 groups (P<0.05), but there was no signficant difference between 2 groups (t=1.267, P=0.832). The xFO and sdFO of group B were significantly larger than those of group A (P<0.05); the number of outlier was 20 in group A and was 33 in group B, showing significant difference (P=0.005). The height of femoral head rotating center and global offset at 3 months after operation showed no signficant difference between 2 groups (P>0.05). And significant improvement in leg discrepancy was found at 3 months in 2 groups (P<0.05), but there was no significant difference between 2 groups (t=0.403, P=0.689). ConclusionBoth of the two femoral prosthesis with different neck-shaft angles can restore the proximal femoral anatomy well and gain similar early effectiveness after THA. However, the Stryker Trident femoral prosthesis with 127° neck-shaft angle may have the tendency to enlarge the femoral offset.

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  • Effectiveness of Biceps Tendon Tenotomy and Fixation versus Biceps Tendon Repair through Arthroscopy for Shoulder Superior Labrum Anterior Posterior Lesions: A Meta-analysis

    ObjectiveTo evaluate the clinical therapeutic effect of biceps tendon tenotomy and fixation versus biceps tendon repair for shoulder superior labrum anterior posterior (SLAP) lesions with Meta-analysis. MethodsThe databases such as PubMed, EMbase, the Cochrane Library (Issue 3, 2014), CBM, VIP and CJFD (from the establishment time of databases to December 2014) were searched to collect all randomized controlled trials (RCT) on the clinical effectiveness of biceps tendon tenotomy and fixation versus biceps tendon repair for shoulder SLAP lesions. Two reviewers independently screened the literature according to the inclusive and exclusive criteria, extracted the data, and assessed the methodological quality of included studies. After the data extraction and methodological quality evaluation, meta-analysis was conducted with RevMan 5.0 software. ResultsThree RCT were included. Among the total 137 patients involved, Meta-analysis showed that, compared with the biceps tendon repair group, the biceps tenotomy group had superior amount in the UCLA score [WMD=3.43, 95%CI (2.29, 4.56), P<0.000 01], the shoulder pain [WMD=1.18, 95%CI (0.30, 2.05), P=0.009], function [WMD=0.96, 95%CI (0.51, 1.41), P<0.000 1] and satisfaction [WMD=1.16, 95%CI (0.31, 2.01), P=0.007] with significant differences. But there were no significant differences between the two groups in the shoulder flextion [WMD=0.10, 95%CI (-0.87, 1.06), P=0.84] and strength [WMD=0.13, 95%CI (-0.09, 0.35), P=0.25]. ConclusionBased on the current studies, the biceps tenotomy and fixation is superior to the biceps tendon repair in treating shoulder SLAP lesions. For the quality restrictions and possible publication bias of the included studies, more double blind, high quality RCT are required to further evaluate the effects.

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  • DIAGNOSIS AND MANAGEMENT OF METACARPOPHALANGEAL JOINT LOCKING WITH EXTENSION LAG

    ObjectiveTo investigate the cl inical characteristics, diagnosis, and treatment of metacarpophalangeal (MCP) joint locking with extension lag. MethodsBetween February 2009 and April 2014, 17 patients (17 fingers) with MCP joint locking with extension lag were treated. The patients included 4 males and 13 females, and the average age was 40.7 years (range, 20-72 years). The index finger was locked in 12 cases and the middle finger in 5 cases. All patients could not fully extend the MCP joint at about 30° flexion without flexion limitation of the interphalangeal joint. The range of motion (ROM) of the MCP joint was (41.2±5.1)°. The visual analogue scale (VAS) score was 2.7±0.5. X-ray and CT scanning showed that there was a bony prominence on radial condyle of the metacarpal head in 15 primary patients, and a hook like osteophyte on ulnar condyle in 2 degenerative patients. All patients were treated with close reduction first, and open reduction was conducted when the manipulation failed. ResultsSuccessful close reduction was achieved in 5 cases, and successful open reduction in 8 cases; 4 cases gave up treatment after failure for close reduction. All patients who achieved successful reduction were followed up 2.3 years on average (range, 6 months to 5 years and 2 months). The ROM of the MCP joint was increased to (80.4±6.6)° at last follow-up, showing significant difference when compared with ROM before reduction (t=-19.46, P=0.00). The VAS score decreased to 0.2±0.4 at last follow-up, also showing significant difference when compared with score before reduction (t=13.44, P=0.00). ConclusionAccessory collateral ligament caught at the bony prominence on the radial condyle of the metacarpal head is the most common cause of the MCP joint locking with extension lag. Close reduction is feasible, but recurrence of locking is possible. Surgical treatment is advised in the event of manipulation failure or recurrent locking.

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  • EFFECTIVENESS ANALYSIS OF OLD EXTENSOR TENDON INJURY IN ZONE II

    ObjectiveTo discuss the effectiveness of operative treatments for different kinds of old injury of extensor tendon in zone II so as to choose the best surgical approach based on the classification of injury. MethodsBetween May 2006 and May 2014, 68 cases of old injury of extensor tendon in zone II were treated. Among them, there were 50 males and 18 females with an average age of 36 years (range, 18-52 years). The causes included contusion injury in 50 cases, avulsion injury in 11 cases, and burn injury in 7 cases. The left side was involved in 21 cases and the right side in 47 cases. The injured finger involved the index finger in 18 cases, the middle finger in 21 cases, the ring finger in 24 cases, and the little finger in 5 cases. The disease duration was 1.5 months to 1 year (mean, 6.75 months). The central slip of extensor was repaired directly in 32 patients who had normal passive motion. Side cross stitch (8 cases) or Littler-Eaton (10 cases) method was used in 18 patients who can not extend actively and passively. Tendon graft was performed in 11 patients with tendon defect. Joint release was given in 7 patients with contracture after burn injury. ResultsPrimary healing of incision was obtained in all cases. Sixty-eight cases were followed up 3-12 months (mean, 6.9 months). Three cases had tendon adhesion in varying degrees and suffered from pain, which was treated conservatively by functional exercise. Recurrence was observed in 2 cases, and extensor tendon was repaired again. According to total active motion (TAM) function assessment, the results were excellent in 52 cases, good in 11 cases, fair in 3 cases, and poor in 2 cases with an excellent and good rate of 92.6%. ConclusionAdaptive operation method for old injury of extensor tendon in zone II should be selected based on the type of injury. The results will be satisfactory if correct method is chosen.

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