The impulsive electroencephalograph (EEG) noises in evoked potential (EP) signals is very strong, usually with a heavy tail and infinite variance characteristics like the acceleration noise impact, hypoxia and etc., as shown in other special tests. The noises can be described by α stable distribution model. In this paper, Wigner-Ville distribution (WVD) and pseudo Wigner-Ville distribution (PWVD) time-frequency distribution based on the fractional lower order moment are presented to be improved. We got fractional lower order WVD (FLO-WVD) and fractional lower order PWVD (FLO-PWVD) time-frequency distribution which could be suitable for α stable distribution process. We also proposed the fractional lower order spatial time-frequency distribution matrix (FLO-STFM) concept. Therefore, combining with time-frequency underdetermined blind source separation (TF-UBSS), we proposed a new fractional lower order spatial time-frequency underdetermined blind source separation (FLO-TF-UBSS) which can work in α stable distribution environment. We used the FLO-TF-UBSS algorithm to extract EPs. Simulations showed that the proposed method could effectively extract EPs in EEG noises, and the separated EPs and EEG signals based on FLO-TF-UBSS were almost the same as the original signal, but blind separation based on TF-UBSS had certain deviation. The correlation coefficient of the FLO-TF-UBSS algorithm was higher than the TF-UBSS algorithm when generalized signal-to-noise ratio (GSNR) changed from 10 dB to 30 dB and α varied from 1.06 to 1.94, and was approximately equal to 1. Hence, the proposed FLO-TF-UBSS method might be better than the TF-UBSS algorithm based on second order for extracting EP signal under an EEG noise environment.
ObjectiveTo explore the effectiveness of UC ultra-congruent rotating platform prosthesis in the treatment of knee osteoarthritis by comparing with fixed-bearing implant. MethodsThe clinical data were retrospectively analyzed, from 98 patients (98 knees) with knee osteoarthritis undergoing primary total knee arthroplasty between January 2011 and December 2012. The UC ultra-congruent rotating platform prosthesis was used in 56 cases (mobile-bearing group) and fixed-bearing implant was used in 42 cases (fixed-bearing group). There was no significant difference in gender, age, side, weight, disease duration, grading of arthritis, the number of varus and valgus malformation, preoperative range of motion of the knee, the Knee Society Score (KSS) score, the visual analogue scale (VAS) score, femorotibial angle, tibial angle, and articular surface angle between 2 groups (P>0.05). The operation time (including anesthetic time), intraoperative blood loss, hospitalization time, total hospitalization expenses, postoperative range of motion of the knee, the KSS score, and the VAS score were compared. The femorotibial angle, tibial angle, and articular surface angle were measured on the basis of anteroposterior and lateral X-ray films, and prosthesis loosening was observed. ResultsThere was no significant difference in the operation time, intraoperative blood loss, and hospitalization time between 2 groups (P>0.05), while the total hospitalization expenses of fixed-bearing group were significantly lower than those of the mobile-bearing group (t=8.506, P=0.000). The patients were followed up 16-30 months in the mobile-bearing group, and for 16-38 months in the fixed-bearing group. Postoperative complications occurred in 3 cases (7.14%) of the fixed-bearing group (1 case of fat liquefaction of incision, 1 case of joint stiff, and 1 case of anterior knee pain), and in 3 cases (5.36%) of the mobile-bearing group (1 case of delayed wound healing, and 2 cases of anterior knee pain); there was no significant difference in the complication rate between 2 groups (χ2=0.133, P=0.516). At last follow-up, the KSS score, VAS score, range of motion of the knee, femorotibial angle, tibial angle, and articular surface angle were superior significantly to those before operation in both groups (P<0.05), but no significant difference was found between 2 groups (P>0.05). No radiographic signs of radiolucent line, prosthetic dislocation, patellar dislocation, prosthetic loosening, and fracture was found. ConclusionUC ultra-congruent rotating platform prosthesis in the treatment of knee osteoarthritis can effectively improve the knee joint function and relief pain, which has the same short-term effectiveness to fixed-bearing implant.