Objective To study the changes of blood flow of the already-compressed cauda equina under dynamic burden, high frequency stimulation (HFS) and increased additional compression, and to clarify the mechanism of neurogenic intermittent claudication. Methods Thirty SD rats were divided into 5 groups, 6 in each. All groups were operated with laminectomy of the fifth lumbar verfebra. One hour after the measurement of blood flow,in 4experimental groups, the silicon sheets were inserted into the spinal canal of L4 and L6 to cause double level compression of cauda equina by 30%. Two hours after onset of compression, no dynamic burden was introduced to the subjects of the experimental group 1. Only HFS was introduced to the subjects of the experimental group 2 for 6 minutes. Both HFS and increased additional compression were introduced to the subjects of the experimental group 3 for 6 minutes. While only increased additional compression was introduced to the subjects of the experimental group 4 for 6 minutes. The subjects of control group only underwent laminectomy of the fifth lumbar vertebra and HFS 6 minutes. The blood flow of cauda equina was measured with laser Doppler flowmeter. Results In the first 2 hours, there was no significant change of cauda equina blood flow in the control group. During the time of HFS, the blood flow increased significantly to 186.4%±31.5% of initial value (Plt;0.05). In the experimental group 1, there was no blood flow change during the period of dynamic burden（110.4％±7.5％，Pgt;0.05）. After introduction of dynamic burden, there was no blood flow changes in the experimental group 2 (111.6％±17.6％，Pgt;0.05). The blood flow in the experimental group 3 decreased to 65.3%±10.7% of initial value (Plt;0.05); and the blood flow in the experimental group 4 decreased to 60.1%±9.2% of initial value (Plt;0.01). There was no significant difference between the experimental groups 3 and 4 (Pgt;0.05). Conclusion The results above show that during the period of increased impulse transmission, double level compression of cauda equina may limit the increase of blood flow, which maycause relative ischemia. If there is increased additional compression along with increased impulse transmission, the blood flow will decrease significantly, which will cause absolute ischemia.
ObjectiveTo evaluate the mid-term clinical and radiological results of dynamic cervical implant (DCI) arthroplasty for degenerative cervical disc disease in Chinese population.MethodsBetween April 2010 and June 2011, 25 patients with single-segmental degenerative cervical disc disease underwent DCI replacement. Visual Analogue Scale (VAS), Japanese Orthopaedic Association (JOA) scores, Neck Disability Index (NDI) and 36-Item Short Form Health Survey Questionnaires (SF-36) were used for evaluation of neurological function and pain severity, before and after operation, and during follow-up period. Radiographic evaluation included range of motion (ROM) of C2–7, surgical segments and adjacent level, intervertebral height of the surgical segments, migration, subsidence of the implant and heterotopic ossification (HO).ResultsThe mean follow-up period was 72.3 months (ranged from 68 to 78 months). The VAS, JOA, NDI, and SF-36 mental and physical component summaries improved significantly after surgery (P<0.05) and remained stable over the whole observation period. The ROM (flexion/extension) and intervertebral height at the level treated with DCI remained at the first 2 years and partly reduced at the final follow-up. ROM for C2–7 and adjacent levels maintained during the follow-up period. DCI subsidence was observed in 11 segements, and 9 segements appeared heterotopic ossification.ConclusionsClinical efficacy of DCI arthroplasty improves and maintaines during the mid-to-long period of follow-up. HO formation is a common phenomenon, leading a dramatic decrease of ROM at index level and recurrence of neurological symptoms. Rate of implant subsidence and migration is relatively high, leaving a potential risk of symptom at index level and adjacent segment degeneration. It suggests that for patients with degenerative cervical disc disease, total disc replacement or anterior cervical discectomy and fusion is still the first choice instead of DCI arthroplasty.
Objective To compare the effectiveness of the proximal femoral nail antirotation (PFNA) and dynamic hip screw (DHS) in the treatment of elderly patients with intertrochanteric fractures. Methods Between May 2007 and May 2010, 63 elderly patients with intertrochanteric fractures were treated, and fractures were fixed with PFNA in 31 patients (PFNA group) and with DHS in 32 patients (DHS group). There was no significant difference in gender, age, injury cause, disease duration, and fracture type between 2 groups (P gt; 0.05). Results All incisions healed by first intention. The incision length, operation time, and blood loss in PFNA group were significantly less than those in DHS group (P lt; 0.05). The averagefollow-up time was 13.6 months in PFNA group and was 13.8 months in DHS group. The fracture heal ing time was (11.80 ± 1.32) weeks in PFNA group and was (12.21 ± 1.26) weeks in DHS group, showing no significant difference (t=1.23, P=0.29). The complication rate was 0 in PFNA group and was 12.5% (4/32) in DHS group, showing no significant difference (P=0.06). After 1 year, Harris hip score of PFNA group (86.55 ± 10.32) was higher than that of DHS group (80.36 ±11.18) (t=2.28, P=0.03). Conclusion There are two surgical methods to treat intertrochanteric fractures in the elderly patient: PFNA and DHS, and each has advantages; for unstable intertrochanteric fractures, PFNA treatment is the first choice.
Objective To investigate the treatment method of senile patients with femoral intertrochanteric fractures and its cl inical outcomes. Methods From January 2005 to December 2007, 192 senile patients with femoral intertrochanteric fractures were treated, including 85 males and 107 females aged 65-92 years old (average 75 years old). The injury was causedby fall on walking in 106 cases, fall when riding a bicycle in 55 cases, and traffic accidents in 31 cases. According to Evans classification, there were 12 cases of type I A, 43 cases of type I B, 29 cases of type II, 24 cases of type III A, 23 cases of type III B, 26 cases of type IV, and 35 cases of type V. One hundred and fifty patients were associated with cardio-cerebrovascular diseases, 120 patients were compl icated with chronicle hypertension, 90 cases were associated with bronchitis, and 75 cases were compl icated with diabetes. The time from injury to hospital admission was 1 hour to 14 days. Among those patients, 108 were treated with conservative treatment, 68 received dynamic hip screw (DHS) fixation, and 16 underwent proximal femoral Gamma nail fixation. Results All the patients were followed up for 12-36 months (average 18 months). The fracture all reached bone union without occurrence of nonunion and delayed union. Patients could take care of themselves, and there were no occurrences of serious pains and dysfunctions. The therapeutic effect was satisfactory. The conservative treatment group: the average hospital stay length was 48 days; the average bone heal ing time was 14 weeks; 23 cases had different degrees of coxa adducta; Harris score system was adopted to evaluate hip joint function, 45 cases were graded as excellent, 31 as good, 10 as fair, and 22 as poor, and the excellent and good rate was 70.4%. DHS internal fixation group: the average operation time was 60 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 24 days; the average bone heal ing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 38 cases were graded as excellent, 21 as good, 8 as fair, and 1 as poor, and the excellent and good rate was 86.8%. Gamma nailfixation group: the average operation time was 70 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 14 days; the average bone heal ing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 11 cases were graded as excellent, 4 as good, 1 as fair, and the excellent and good rate was 93.8%. Conclusion For geriatric femoral intertrochanteric fractures, operative treatment should be performed, the preoperative preparation should be sufficient, and individual-oriented treatment method should be selected on the basis of physical conditions of patients and the types of fractures.
Objective To compare the curative effect of dynamic hi p screw (DHS) combined with anti-rotation screw and cannulated screw in treating patients with Pauwels type II or III femoral neck fracture and to provide the basis for the choice of surgical procedure. Methods Between March 2008 and September 2009, 51 patients with fresh Pauwels type II or III femoral neck fracture were treated with DHS combined with anti-rotation screw (DHS group) and three cannulated screws (cannulated screw group). The DHS group included 23 patients, 13 males and 10 females, aging 27-59 years (mean, 43.2 years); fracture was caused by fall ing in 1 case, by traffic accident in 17, by fall ing from height in 5 with a mean time of 27 hoursfrom injury to hospital ization (range, 12-70 hours); and 23 fractures included 9 Pauwels type II and 14 Pauwels type III femoral neck fracture. The cannulated screw group included 28 patients, 12 males and 16 females, aging 20-60 years (mean, 40.7 years); fracture was caused by fall ing in 1 case, by traffic accident in 22, by fall ing from height in 5 with a mean time of 25 hours from injury to hospital ization (range, 9-38 hours); and 28 fractures included 12 Pauwels type II and 16 Pauwels type III femoral neck fracture. There was no significant difference in the basel ine characteristics between 2 groups (P gt; 0.05). Results The incision heal ing of both groups by first intention was achieved. There were significant differences in operation time, incision size, operation blood loss, the cases of blood transfusion, the amount of blood transfusion, C reaction protein level on the 2nd postoperative day, and hospital ization days between 2 groups (P lt; 0.05). In DHS group, anatomic reduction was observed in 20 cases (86.96%) and satisfactory reduction in 3 cases (13.04%), while in cannulated screw group, anatomic reduction was observed in 25 cases (89.29%) and satisfactory reduction in 3 cases (10.71%) ; there was no significant difference (χ2=0.660, P=1.000). The patients were followed up 12-30 months with an average of 14.8 months. There was no significant difference (P gt; 0.05) in the rate of nonunion (10.71% vs. 0), the implant failure (3.57% vs. 0), and avascular necrosis of the femoral head (10.71% vs. 0) between the DHS group and the cannulated screw group. The union time was (94.5 ± 2.0) days in the DHS group and (106.0 ± 33.5) days in the cannulated screw group, showing no significant difference (t=—1.641, P=0.107). The re-opereation rates and the overall success rates were 25% and 75% in the cannulated group and were 0 and 100% in the DHS group, showing significant differences (χ2=6.650, P=0.012). At last follow-up, there was no significant difference in Harris hip score and visualanalogue scale (VAS) score between DHS group and cannulated screw group (P gt; 0.05). Conclusion The optimal treatment of young adults Pauwels type II or III femoral neck fracture is DHS combined with anti-rotation screw with an high overall success and less compl ications.
Objective To compare the effectiveness and radiological changes of posterior decompression combined with Coflex interspinous dynamic reconstruction or lumbar 360° fusion for degenerative lumbar spinal disorders at L4, 5. MethodsBetween October 2008 and November 2010, a comparative study was carried out on patients with degenerative lumbar spinal disorders at L4, 5. In group A, 29 patients underwent posterior decompression combined with Coflex interspinous dynamic reconstruction; there were 20 males and 9 females with an average age of 45.1 years (range, 21-67 years); and the disease duration was 2 months to 4 years. In group B, 31 patients underwent posterior decompression combined with lumbar 360° fusion treatment; there were 16 males and 15 females with an average age of 56.2 years (range, 32-86 years); and the disease duration was 3 months to 6 years. Except the age, there was no significant difference in gender, disease duration, and etiology etc. between 2 groups (P gt; 0.05). The results were assessed by Japanese Orthopaedic Association (JOA), visual analogue scale (VAS) scores, and Oswestry disabil ity index (ODI). The range of motion (ROM) and intervertebral height of affected and adjacent segments, and the ROM of lumbar were measured before operation and last follow-up. Results Significant differences were found in the operative time and blood loss between 2 groups (P lt; 0.05). Intraoperative dural tear occurred in 1 case of group B, spinal canal venous plexus hemorrhage in 1 case of group B, and postoperative cerebrospinal fluid leakage in 2 cases of group A and B respectively, showing no significant difference (χ2=0.119, P =0.731). The follow-up was 12-21 months in group A and was 12-23 months in group B. At the last follow-up, the JOA, VAS scores, and ODI of groups A and B were significantly improvedwhen compared with the preoperative values (P lt; 0.05). The VAS score of group A was significantly higher than that of group B (P lt; 0.05). There was no significant difference in the intervertebral height of L4, 5 and L5, S1 of groups A and B between pre- and post-operation (P gt; 0.05). In group B, the intervertebral height of L3, 4 was significantly reduced (P lt; 0.05) compared with the preoperative one. There was no significant difference in the ROM of L5, S1 and ROM of lumbar in groups A and B between preand post-operation (P gt; 0.05). At last follow-up, the ROM of L4, 5 was significantly reduced in group A (P lt; 0.05), and the ROM of L3, 4 was significantly increased in group B (P lt; 0.05). Except significant differences in the intervertebral height and ROM of L3, 4 between 2 groups (P lt; 0.05), no significant difference was found in other parameters (P gt; 0.05). Conclusion Posterior decompression combined with Coflex interspinous dynamic reconstruction has the same effectiveness as lumbar 360° fusion in treating degenerative lumbar spinal disorders at L4, 5, but the former has a protective effect on the adjacent segments of fusion and is recommended for initial treatment of young adults and the elderly and frail patients with recurrent.
Objective To study the technique and effect of adjunctive cancellous screw in treatment of intertrochanteric fractures with dynamic hi p screw (DHS) fixation. Methods Between April 2004 and August 2007, 33 patients with intertrochanteric fracture were treated with DHS fixation and adjunctive cancellous screw. There were 13 males and 20 females, aging 43-82 years with an average age of 67 years. Fractures were caused by traffic accident in 7 patients, by fall ing from height in 11 patients, by sprain in 15 patients. All fractures were closed. The patients were operated 3-12 days after injury. According to Evans classification, there were 12 cases of type II, 15 cases of type III, and 6 cases of type IV. Twenty-twocases had osteoporosis. Weight bear time and compl ication were recorded. Fracture heal ing and neck-shaft angle were observed on radiogram. Hip functions were evaluated using Radford criterion. Results Thirty-three patients had no intraoperative compl ications with incision heal ing by first intension. All patients were followed up from 14 months to 38 months, with an average of 21 months. Fracture heal ing was achieved within 14 weeks to 21 weeks, with an average of 17 weeks after operations. The neck-shaft angles were (134.2 ± 13.7)° 3 days after operation, (128.6 ± 8.9)° 8 weeks after operation, and (128.5 ± 9.3)° after fracture heal ing, showing no significant difference when compared with that of the third day after operation (P gt; 0.05). According to the Radford criterion at last follow-up, the excellent and good rate of hi p function was 93.9% (excellent in 21 cases, good in 10 cases, and poor in 2 cases). Compl ications such as loosening, breakage, or grievous migration of hardware were not observed. Conclusion The adjunctive cancellous screw in treatment of intertrochanteric fractures with DHS fixation can provide counteraction of tension and rotation, promote fixation stabil ity, enhance fracture heal ing and decrease compl ication.
To investigate the effects of augmentation with bone cement on the biomechanics of the dynamic hip screw (DHS) fixation in the intertrochanteric fracture specimen that has a normal bone density.MethodsTwentyfour matched pairs of the embalmed male upper femora (48sides) were used to make the specimens of the intertrochanteric fracture of Type A2. All the specimens were fixed with DHS. The right femur specimen from each pair was fixed by augmentation with DHS (the augmentation group) and the left femur specimen was fixed with the conventional fixation (the control group). Thebiomechanical tests on the bending stiffness and the torsional stiffness were performed with the servohydraulic testing machine in the two groups.ResultsThe maximum load and the maximum torque were 3 852.160 2±143.603 1 N and 15.5±2.6 Nm in the augmentation group and 3 702.966 7±133.860 1 N and 14.7±3.4 Nm in the control group. There was no significant difference in the biomechanical effects between the two groups (P＞0.05). Conclusion The augmenting fixation with bone cement in the intertrochanteric fracture specimen with a normal bone density has no significant effect on the strength of the DHS augmentation or on the overall stability of the fractured bone.
Objective To evaluate the influence on the estimation of respiratory mechanics with dynamic signal analysis approach during noninvasive positive pressure ventilation (NPPV) under different inspiratory effort conditions. Methods The Respironics V60 ventilator was connected to a ASL5000 lung simulator, which simulate lung mechanics in healthy adults with body weight from 65 to 70 kg, and patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress (ARDS). Each lung models was subjected to 4 different muscle pressures (Pmus): 0, 5.0, 10.0, and 15.0 cm H2O. Inspiratory pressure support level was adjusted to maintain tidal volume (VT) achieving 7.0 mL/kg outputted by ventilator respectively. Positive end expiratory pressure was set at 5.0 cm H2O and back-up rate was 10 beats per minute. Measurements were conducted at system leaks with 25 to 28 L/min. The respiratory system compliance (Crs), inspiratory and expiratory resistance (Rinsp and Rexp) were estimated by special equations, which was derived from the exhaled VT, flow rate and airway pressure. Results The driving pressure (DP) was decreased with Pmus increasing, and was 1.0 cm H2O after Pmus exceeding 10.0 cm H2O and the VT was larger than 7.0 mL/kg in normal adult model. The estimated value of Crs was affected by the changes of Pmus in all three lung models. The significant underestimation of Raw and the overestimation of Crs were observed when Pmus level exceed 10.0 cm H2O. The measured errors of Crs and Rexp were within 10% in COPD and ARDS model when Pmus was at 5.0 cm H2O. The underestimation of Rinsp was always existed in all Pmus level (P<0.01). Conclusions Using dynamic signal analysis approach, the real-time estimation of respiratory mechanics (Crs and Raw) is no need to interrupt the spontaneous breathing during NPPV. Excessive effort will increase the patient’s inspiratory workload, which is not benefit to accurate estimation of respiratory mechanics.
The risk prediction model (RPM) can be used to predict the risks of disease for individuals, playing an extremely important role in decision-making regarding disease prevention, treatment, and prognostic management. Most of the existing RPMs only utilize a single-time cross-section of variable data, so-called static models, which fail to consider the many changes during disease progression and lead to limited prediction accuracy. Dynamic prediction models can incorporate longitudinal data such as repeated measurements of variables during follow-up to capture the longitudinal changes in individual characteristics over time, describe the dynamic trajectory of individual disease risk and improve the prediction accuracy of the models; however, their application in medical research is still relatively small. In this paper, we conducted a systematic literature search to summarize the commonly used dynamic models: joint model, landmark model, and Bayesian dynamic model. By introducing their application scenarios, advantages and disadvantages, and software implementations and conducting comparisons, we aimed to provide methodological references for the future application of dynamic prediction models in medical research.