Motor learning changes the axon initial segment of the spinal motoneuron.

We are studying the mechanisms of H-reflex operant conditioning, a simple form of learning. Modelling studies in the literature and our previous data suggested that changes in the axon initial segment (AIS) might contribute. To explore this, we used blinded quantitative histological and immunohistochemical methods to study in adult rats the impact of H-reflex conditioning on the AIS of the spinal motoneuron that produces the reflex. Successful, but not unsuccessful, H-reflex up-conditioning was associated with greater AIS length and distance from soma; greater length correlated with greater H-reflex increase. Modelling studies in the literature suggest that these increases may increase motoneuron excitability, supporting the hypothesis that they may contribute to H-reflex increase. Up-conditioning did not affect AIS ankyrin G (AnkG) immunoreactivity (IR), p-p38 protein kinase IR, or GABAergic terminals. Successful, but not unsuccessful, H-reflex down-conditioning was associated with more GABAergic terminals on the AIS, weaker AnkG-IR, and stronger p-p38-IR. More GABAergic terminals and weaker AnkG-IR correlated with greater H-reflex decrease. These changes might potentially contribute to the positive shift in motoneuron firing threshold underlying H-reflex decrease; they are consistent with modelling suggesting that sodium channel change may be responsible. H-reflex down-conditioning did not affect AIS dimensions. This evidence that AIS plasticity is associated with and might contribute to H-reflex conditioning adds to evidence that motor learning involves both spinal and brain plasticity, and both neuronal and synaptic plasticity. AIS properties of spinal motoneurons are likely to reflect the combined influence of all the motor skills that share these motoneurons. KEY POINTS: Neuronal action potentials normally begin in the axon initial segment (AIS). AIS plasticity affects neuronal excitability in development and disease. Whether it does so in learning is unknown. Operant conditioning of a spinal reflex, a simple learning model, changes the rat spinal motoneuron AIS. Successful, but not unsuccessful, H-reflex up-conditioning is associated with greater AIS length and distance from soma. Successful, but not unsuccessful, down-conditioning is associated with more AIS GABAergic terminals, less ankyrin G, and more p-p38 protein kinase. The associations between AIS plasticity and successful H-reflex conditioning are consistent with those between AIS plasticity and functional changes in development and disease, and with those predicted by modelling studies in the literature. Motor learning changes neurons and synapses in spinal cord and brain. Because spinal motoneurons are the final common pathway for behaviour, their AIS properties probably reflect the combined impact of all the behaviours that use these motoneurons.

The influence of patellar morphology on clinical outcomes after unicompartmental knee arthroplasty.

PURPOSE: To evaluate the influence of patellar morphology on functional outcomes and patellofemoral joint alignment after unicompartmental knee arthroplasty (UKA). METHODS: This study retrospectively analyzed the clinical and imaging data of 207 patients with osteoarthritis of the unicompartment of the knee who underwent UKA between September 2020 and April 2023. Patients were divided into three groups according to the Wiberg classification: group W1 (I, n = 47), group W2 (II, n = 117), and group W3 (III, n = 43). Knee function was assessed using the Hospital for Specialty Surgery (HSS) knee score and Feller patellar score, and the incidence of anterior knee pain after surgery was recorded and compared. Imaging parameters such as patellar tilt angle (PTA), lateral patellofemoral angle (LPA) and Insall-Salvati ratio (ISR) were measured to assess patellofemoral joint alignment. RESULTS: The HSS scores of the three groups were not statistically different; the postoperative Feller scores of the group W3 differed significantly from those of the other two groups. The incidence of early postoperative anterior knee pain was higher in the group W3 than in the other two groups. The difference between preoperative PTA, postoperative PTA and preoperative LPA in the group W3 and the other two groups was statistically significant. CONCLUSION: Patients with Wiberg III patellae exhibited worse patellar scores, as well as more anterior knee pain and patellar tilt postoperatively. This finding highlights the need for individualized treatment to the Wiberg III patella during UKA to enhance surgical outcomes.

Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?

BACKGROUND: The purpose of this study was to measure the femoral prosthesis flexion angle (FPFA) in total knee arthroplasty (TKA) using three-dimensional reconstruction, and to assess the differences in early clinical efficacy between patients with different degrees of flexion. METHODS: We conducted a prospective cohort study. From June 2019 to May 2021, 113 patients admitted for TKA due to osteoarthritis of the knee were selected. The patients' postoperative knee joints were reconstructed in three dimensions according to postoperative three-dimensional computed tomography (CT) scans. The FPFA was measured, and the patients were divided into 4 groups: anterior extension group (FPFA < 0°), mildly flexed group (0° ≤ FPFA < 3°), moderately flexed group (3° ≤ FPFA < 6°) and excessively flexed group (6° ≤ FPFA). The differences in the Knee Society Score (KSS), knee Range of Motion (ROM), and visual analogue scale (VAS) scores were measured and compared between the four groups at each postoperative time point. RESULTS: Postoperative KSS, ROM, and VAS were significantly improved in all groups compared to the preoperative period. At 1 year postoperatively, the ROM was significantly greater in the mildly flexed group (123.46 ± 6.51°) than in the anterior extension group (116.93 ± 8.05°) and the excessively flexed group (118.76 ± 8.20°) (P < 0.05). The KSS was significantly higher in the mildly flexed group (162.68 ± 12.79) than in the other groups at 6 months postoperatively (P < 0.05). The higher KSS (174.17 ± 11.84) in the mildly flexed group was maintained until 1 year postoperatively, with a statistically significant difference (P < 0.05). No significant difference in VAS scores was observed between groups at each time point. CONCLUSIONS: A femoral prosthesis flexion angle of 0-3° significantly improved postoperative knee mobility, and patients could obtain better Knee Society Scores after surgery, which facilitated the postoperative recovery of knee function. TRIAL REGISTRATION: ChiCTR2100051502, 2021/09/24.

[Ontologies Applied in Clinical Decision Support Systems for Diabetes].

A clinical decision support system (CDSS) integrated with electronic health records helps physicians at the grassroots make patient-appropriate and evidence-based treatment decisions and improves the efficiency of diagnosis and treatment. Furthermore, using ontologies to build up the medical knowledge base and patient data for CDSS enhances the automation and transparency of the reasoning process of CDSS and helps generate interpretable and accurate treatment recommendations. Herein, we reviewed the relevant ontologies in the field of diabetes treatment and the progress and challenges concerning ontology-based CDSSs. Firstly, we elaborated on the current status and challenges of diabetes treatment in China, highlighting the urgent need to improve the efficiency and quality of medical services. Then, we presented background information about ontologies and gave an overview of the framework, methodology, and features of using ontologies to construct CDSS. After that, we reviewed the ontologies and instances of ontology-based CDSS in the field of diabetes treatment in China and abroad and summarized their construction methods and features. Last but not the least, we discussed the future prospects of the field, suggesting that integrating evidence-based medicine with ontologies to build a reliable clinical recommendation system should be the current focus of CDSS development.

Different tibial rotational axes can be applied in combination according to the tibial tuberosity-posterior cruciate ligament distance in total knee arthroplasty.

PURPOSE: The purpose of this study was to investigate whether tibial tuberosity-posterior cruciate ligament (TT-PCL) distance is representative of the true lateralization of tibial tuberosity in isolation and its influence on the accuracy of the Akagi line and medial third of the tibial tuberosity (MTTT). METHODS: A total of 135 osteoarthritis patients with varus knees who undergoing computed tomography scans were enrolled to establish three-dimension models of the knees. Tibial width (TW), tibial tuberosity lateralization (TTL), posterior cruciate ligament lateralization (PCLL), knee rotation angle (KRA) and tibial rotational axes were measured and investigated their correlations with TT-PCL distance. Based on the analysis of receiver operating characteristic (ROC) curve, the influence of TT-PCL distance on the distributions of mismatch angles of tibial rotational axes was investigated with a safe zone (-5° to 10°). RESULTS: TT-PCL distance was in significantly positive correlation with TW (r = 0.493; P < 0.001) and TTL (r = 0.378; P < 0.001) which was different with PCLL (r = 0.147; P = 0.009) and KRA (r = -0.166; P = 0.054). All tibial rotational axes were significantly positively correlated with TT-PCL distance (P < 0.001). The mismatch angles between the vertical line of the surgical epicondylar axis (SEA) and the Akagi line and MTTT were -1.7° ± 5.3° and 7.6° ± 5.6° respectively. In terms of the optimal cut-off value of 19 mm for TT-PCL distance, the Akagi line applied as tibial rotational axis ensures 87.3% of the positions of tibial components within the safe zone when TT-PCL distance > 19 mm, and MTTT ensures 83.3% when TT-PCL distance ≤ 19 mm. CONCLUSION: TT-PCL distances cannot reflect the true lateralization of tibial tuberosity in isolation but can aid in the combination of the Akagi line and MTTT in varus knees. The patients with TT-PCL distance > 19 mm are recommended to reference the Akagi line for tibial rotational alignment. MTTT is recommended to the patients with TT-PCL distance ≤ 19 mm. The study will aid surgeons in deciding which reference may be used by measuring TT-PCL distance using a preoperative CT.

Stress distribution patterns during the gait cycle in patients with anterior femoral notching following total knee replacement.

BACKGROUND: Anterior femoral notching (AFN) is a severe complication of total knee replacement (TKR), which in a percentage of patients may lead to fractures after surgery. The purpose of this study was to investigate the stress distribution in patients with AFN and the safety depth of AFN during the gait cycle. METHODS: We performed a finite element (FE) analysis to analyse the mechanics around the femur during the gait cycle in patients with AFN. An adult volunteer was selected as the basis of the model. The TKR models were established in the 3D reconstruction software to simulate the AFN model during the TKR process, and the 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm AFN models were established, after which the prosthesis was assembled. Three key points of the gait cycle (0°, 22°, and 48°) were selected for the analysis. RESULTS: The stress on each osteotomy surface was stable in the 0° phase. In the 22° phase, the maximum equivalent stress at 3 mm was observed. In the 48° phase, with the increase in notch depth, each osteotomy surface showed an overall increasing trend, the stress range was more extended, and the stress was more concentrated. Moreover, the maximum equivalent force value (158.3 MPa) exceeded the yield strength (115.1 MPa) of the femur when the depth of the notch was ≥ 3 mm. CONCLUSIONS: During the gait cycle, if there is an anterior femoral cortical notch ≥ 3 mm, the stress will be significantly increased, especially at 22° and 48°. The maximum equivalent stress exceeded the femoral yield strength and may increase the risk of periprosthetic fractures.

Cognitive behavioral therapy cannot relieve postoperative pain and improve joint function after total knee arthroplasty in patients aged 70 years and older.

PURPOSE: A randomized controlled trial was conducted to investigate whether cognitive behavioral therapy (CBT) can improve postoperative pain, knee function, and negative emotion in patients aged 70 years and older who underwent total knee arthroplasty (TKA). METHODS: This study used randomized, parallel group, controlled trial to divide the included 90 patients into CBT group and usual care group. The primary outcome measure of the study was the Visual Analogue Scale (VAS) at activity. The secondary outcome measures included the Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS), Knee Range of Motion (ROM), Oxford Knee Score (OKS), Hospital for Special Surgery Knee Rating Scale (HSS), analgesics dose, and postoperative complications. RESULTS: 83 patients who met the criteria were randomized into CBT group and usual care group. In the SAS, score of the CBT group decreased by 4.3 points at 7th day and 8.2 at 14th day after surgery with respect to preoperative SAS score, the usual care group increased by 1.5 at 7th day and decreased 1.1 at 14th day, and tended to be similar at 3rd month after surgery. There were no significant differences at 7th and 14th day in SDS, however, score of the CBT group was 5.8 and the usual care group was 1.9 at 3rd month after surgery. No statistically significant differences in VAS at activity, ROM, OKS, HSS, analgesics frequency, and postoperative complications between two groups. CONCLUSIONS: CBT was superior to usual care group in relieving anxiety at 7th day and 14th day, and depression at 3rd month, however, CBT cannot relieve postoperative pain and improve joint function after TKA in patients aged 70 years and older.

Porous tantalum implant for treatment of early-stage osteonecrosis of the femoral head: a minimum 5-year follow-up study.

BACKGROUND: To evaluate the survival rate of porous tantalum rod implantation in the treatment of osteonecrosis of the femoral head (ONFH), evaluate its clinical effect and imaging results. METHODS: From January 2008 to December 2013, porous tantalum rod implantation for ONFH was performed in two institutions. Statistical analysis of operation data, including operation time, blood loss and blood transfusion were recorded. RESULTS: 52 hips received complete follow-up, the average follow-up time was 85.7 months (60-132 months). 24 hips turned to THA at the end of follow-up (46.2%), the average time was 44.3 ± 32.8 months, and the average Harris hip score before THA was 57.1 ± 7.6. Cox proportional-hazards model revealed that Association Research Circulation Osseous (ARCO) stage (P = 0.017), bone marrow edema (P = 0.006) and age > 40 years (P = 0.043) were independent risk factors for conversion to THA. CONCLUSION: ARCO stage, age and bone marrow edema were risk factors for the failure of porous tantalum rod implantation to convert to THA.

[Construction of "2R network pharmacology" research method for effective components of traditional Chinese medicine based on "prediction of dominant components-screening of potential targets"].

Chinese traditional medicine compound is the main form of Chinese medicine clinical application. The elucidation of the effective components of traditional Chinese medicine is one of the key scientific issues to promote the modernization of traditional Chinese medicine. At present, there are many research ideas on the effective components of traditional Chinese medicine compounds. By analyzing the current status and existing problems of existing research ideas, the author proposes a "double reduction network pharmacology"(2 R network pharmacology) research method based on "prediction of dominant components-potential target selection". Chemical components with good properties were selected by ADMET property prediction technology, and compared with the blood components and target organ components to determine the dominant components with potential therapeutic effect, that is "reducing constituents"; the potential core regulatory pathway of traditional Chinese medicine compound was enriched by RNA-Seq technology combined with network database, and then the target of traditional Chinese medicine compound was mined based on the signal pathway, that is "reducing targets". To improve the efficiency and accuracy of effective component screening, the network relationship of "component target" was established by the related technology of network pharmacology. The purpose of this study is to provide practical research ideas and methods for clarifying the effective components of traditional Chinese medicine, revealing the law of compatibility of traditional Chinese medicine and clarifying the target of drug action.

Are There Lower Complication Rates with Bidirectional Barbed Suture in Total Knee Arthroplasty Incision Closure? A Randomized Clinical Trial.

BACKGROUND The use of barbed suture in total knee arthroplasty (TKA) remains controversial. We performed a prospective study to investigate the clinical outcomes of bidirectional barbed suture for incision closure in TKA. MATERIAL AND METHODS We conducted a single-center, randomized controlled trial to determine the efficiency and safety of barbed suture in TKA at our institution between December 2017 and April 2019. Eligible patients were randomly assigned to different suture methods for skin closure. Randomization was conducted via computerized randomization list. Our primary endpoint was the incidence of wound complications within 3 months of surgery. This trial was registered at ClinicalTrials.gov, number ChiCTR-IPR-17013677. RESULTS A total of 582 patients were enrolled, consisting of 193 who received full-layer barbed suture (group A), 195 who received barbed suturing of the joint capsule (group B), and 194 who received suturing of the joint capsule by traditional absorbable suture (group C). The incidence of incision complications in group A (19.7%) was significantly higher than that in group B (7.2%) and C (9.3%) (P<0.0125). The incidence rate for incision complications in group B was similar to that in group C (P>0.0125). The time for incision closure in groups A (13.5±2.0 min) and B (16.1±1.9 min) was significantly shorter than that in group C (25.0±2.0 min) (P<0.001). CONCLUSIONS The use of full-thickness bidirectional barbed suture for incision closure after TKA may increase postoperative incision complications, and therefore is not recommended. However, the use of barbed suture for the joint capsule has shown effectiveness, reducing suture time with no increase in incision complications.

Comparison of cylindrical and tapered stem designs for femoral revision hip arthroplasty.

BACKGROUND: Both cylindrical and tapered stems are commonly used in revision total hip arthroplasty. However, whether the geometry of prosthesis stem has an effect on patient prognosis is unclear. We assume that the tapered stem results in better clinical outcome than the cylindrical stem. METHODS: A multicenter review of 120 femoral revisions with Paprosky I, II, and III defects using cobalt chrome cylindrical stem (54 hips) or titanium tapered stem (66 hips) was performed with an average follow-up of 6 years. Demographic data were comparable between groups. RESULTS: No significant group differences were found in surgery time, bleeding volume, postoperative Harris Hip Score, level of overall satisfaction, and 8-year cumulative survival. However, intraoperative fractures occurred significantly less in the tapered group (4.5%) than in the cylindrical group (14.8%), and stem subsidence was significantly less in the tapered group (2.17 mm) than in the cylindrical group (4.17 mm). A higher ratio of bone repair and lower bone loss were observed in the tapered group compared with the cylindrical group. The postoperative thigh pain rate was higher in the cylindrical group (12.9%) than in the tapered group (4.5%). CONCLUSION: Both cylindrical stem and tapered stem can achieve satisfactory mid-term clinical results in revision total hip arthroplasty. The tapered stem has better bone restoration of proximal femur, lower incidence of intraoperative fractures, and lower postoperative thigh pain rate compared with the cylindrical stem.

Mid- and long-term efficacy of surgical treatment of Vancouver B2 and B3 periprosthetic femoral fractures.

BACKGROUND: The incidence of fractures around the femoral prosthesis among patients undergoing hip arthroplasty is increasing and has become the third leading cause of hip revision. While numerous methods for the surgical treatment of periprosthetic femoral fractures (PFFs) have been proposed, only few reports have examined the long-term efficacy of surgical treatment. This study aims to examine the mid-and long-term efficacy of surgical treatment among patients with Vancouver B2 and B3 PFFs. METHODS: This retrospective study evaluated the surgical outcomes of patients with Vancouver B2 and B3 PFFs between 2007 and 2011. The minimum follow-up time was eight years. Fracture healing, prosthesis stability, complications, patient quality of life SF-36 score, and survival rate were evaluated during the follow-up assessments. RESULTS: A total of 83 patients were included and had an average follow-up period of 120.3 months. Among these patients, 69 were classified as Vancouver B2 and were treated with a distal fixation stem, whereas 14 cases were classified as Vancouver B3 and were treated with modular femoral prosthesis by using a proximal femoral allograft technique. A total of 15 patients underwent secondary revision surgery, and prosthesis dislocation was identified as the main cause of secondary revision. 80 (96.4%) cases of fractures were clinically healed. The mortality rate in the first year after surgery was 8.4% (7/83). The overall 5-year Kaplan-Meier survival rate for these patients was 75.9%. Meanwhile, the 5-year Kaplan-Meier survival rate for the implants was 86.9%. The final follow-up SF-36 score of the patients was 48.3 ± 9.8. CONCLUSIONS: Patients with Vancouver B2 and B3 PFFs show high mortality in the first year after their surgery, and the Kaplan-Meier analysis results showed that such mortality tends to plateau after 5 years. Prosthesis dislocation was identified as the primary cause of secondary revision.

Does cognitive behavioral education reduce pain and improve joint function in patients after total knee arthroplasty? A randomized controlled trial.

INTRODUCTION: Cognitive behavioral therapy (CBT) is an effective treatment for reducing the pain of knee osteoarthritis (OA) and improving joint function. However, there are few studies on the effect of CBT on the pain severity after total knee arthroplasty (TKA). This study investigates the effectiveness of a CBT program on pain, knee function, quality of life, and pain catastrophizing in patients after TKA. METHODS: This was a randomized, parallel-group, controlled trial in which 100 patients with knee osteoarthritis (OA) prepared for TKA were randomly assigned to participate in CBT or usual care group. Evaluation outcomes include Visual Analogue Scale (VAS), Pain Catastrophizing Scale (PCS), Oxford Knee Score (OKS), Knee Range of Motion (ROM), EuroQol Five-Dimensional (EQ-5D), and Hospital for Special Surgery (HSS) Knee Rating Scale before and after surgery. RESULTS: We found that patients in the CBT group had a lower pain during activity from the fifth day (p = 0.003) to the third month (p = 0.019) after TKA. At the 12th month, the mean VAS score during activity in the CBT and usual care groups decreased from 4.5 to 0.8 and from 4.6 to 0.9, respectively, and there is no significant difference between the two groups. The PCS scores of patients in the CBT group were lower than those in the usual care group at 1st (p = 0.014) and 3rd months (p = 0.027) after surgery. No statistically significantly differences between the two groups in pain during rest, knee ROM, EQ-5D, OKS, and HSS. CONCLUSIONS: The CBT program was superior to usual care in reducing post-operative pain during activity from the fifth day to the third month and pain catastrophing in the first three months after TKA but has no statistically significantly differences in pain during rest, knee ROM, EQ-5D, OKS, and HSS. TRIAL REGISTRATION: Current Controlled Trials ChiCTR2000032857, date of registration: May, 14, 2020, retrospectively registered.

Comparison of the therapeutic effect between the simultaneous and staged unicompartmental knee arthroplasty (UKA) for bilateral knee medial compartment arthritis.

BACKGROUND: To compare the efficacy and safety of simultaneous vs staged unicompartmental knee arthroplasty (UKA) for bilateral unicompartmental osteoarthritis of the knee. METHODS: We performed a retrospective analysis of prospectively collected data on 93 patients with bilateral knee medial compartment arthritis underwent simultaneous UKA (Group A, 39) or staged UKA (Group B, 54 cases) from January 2008 to December 2015. Group A: 6 males and 33 females aged 64.9 ± 7.7 years; Group B: 5 males and 49 females aged 64.2 ± 6.4 years. There were no statistically significant differences in pre-operative age, sex ratio, or body weight index between the groups (P > 0.05). Groups were compared in terms of total anesthesia time, volume of drainage, blood transfusion rate, hemoglobin level on post-operative day 3, total post-operative inpatient days, treatment expenses, post-operative therapeutic effect (KSS scores), and complications. RESULTS: All patients had follow-up visits post-operatively. The follow-up visit interval was 32-133 months and 41.9 months on average. Total anesthesia time, postoperative length of hospital stay, and hospitalization expenses in Group A were significantly less than those of Group B (P < 0.05). Hemoglobin levels in Group A were significantly lower than those of Group B at post-op day 3 (P < 0.05). However, no significant differences in volume of drainage, the rate of transfusion, complications, and KSS scores were detected between Groups A and B (P > 0.05). CONCLUSIONS: Both simultaneous and staged UKA achieved the desired therapeutic effect in treatment of bilateral knee medial compartment arthritis. However, simultaneous UKA reduced the cost and the postoperative length of hospital stay without increasing post-operative complications.

Why New Spinal Cord Plasticity Does Not Disrupt Old Motor Behaviors.

When new motor learning changes the spinal cord, old behaviors are not impaired; their key features are preserved by additional compensatory plasticity. To explore the mechanisms responsible for this compensatory plasticity, we transected the spinal dorsal ascending tract before or after female rats acquired a new behavior-operantly conditioned increase or decrease in the right soleus H-reflex-and examined an old behavior-locomotion. Neither spinal dorsal ascending tract transection nor H-reflex conditioning alone impaired locomotion. Nevertheless, when spinal dorsal ascending tract transection and H-reflex conditioning were combined, the rats developed a limp and a tilted posture that correlated in direction and magnitude with the H-reflex change. When the right H-reflex was increased by conditioning, the right step lasted longer than the left and the right hip was higher than the left; when the right H-reflex was decreased by conditioning, the opposite occurred. These results indicate that ascending sensory input guides the compensatory plasticity that normally prevents the plasticity underlying H-reflex change from impairing locomotion. They support the concept of the state of the spinal cord as a negotiated equilibrium that reflects the concurrent influences of all the behaviors in an individual's repertoire; and they support the new therapeutic strategies this concept introduces.SIGNIFICANCE STATEMENT The spinal cord provides a reliable final common pathway for motor behaviors throughout life. Until recently, its reliability was explained by the assumption that it is hardwired; but it is now clear that the spinal cord changes continually as new behaviors are acquired. Nevertheless, old behaviors are preserved. This study shows that their preservation depends on sensory feedback from the spinal cord to the brain: if feedback is removed, the acquisition of a new behavior may disrupt an old behavior. In sum, when a new behavior changes the spinal cord, sensory feedback to the brain guides further change that preserves old behaviors. This finding contributes to a new understanding of spinal cord function and to development of new rehabilitation therapies.

Does the grading of chondromalacia patellae influence anterior knee pain following total knee arthroplasty without patellar resurfacing?

OBJECTIVES: The influence of chondromalacia patellae (CMP) on post-operative anterior knee pain (AKP) following total knee arthroplasty (TKA) remains controversial, and few studies have focused on the relationship between them. The purpose of this study was to determine whether different CMP grades affect the incidence of AKP after TKA without patellar resurfacing. METHODS: We performed a retrospective analysis of prospectively collected data on 290 TKAs with the use of the low contact stress mobile-bearing prosthesis, without patellar resurfacing in 290 patients from February 2009 to January 2013. Patients were assessed by the Outerbridge classification for CMP, visual analog scale for AKP, the Knee Society clinical scoring system of knee score (KS), function score (FS), the patellar score (PS) for clinical function, and patients' satisfaction. RESULTS: The intra-operative grading of CMP: grade I in 30 patients, grade II in 68 patients, grade III in 97 patients, and grade IV in 95 patients. The incidence of AKP at 36-month follow-up was 10.3% (30/290). No statistical difference was detected among the different CMP grades in terms of the incidence of AKP (p = 0.995), patients' satisfaction (p = 0.832), KS (p = 0.228), FS (p = 0.713), and PS (p = 0.119) at 36-month follow-up. CONCLUSIONS: The findings may suggest no relevant influence of CMP grading on the incidence of AKP after TKA without patellar resurfacing.

Influence of age on results following surgery for displaced acetabular fractures in the elderly.

BACKGROUND: Elderly patients have more special medical needs when compared with young ones; thus, the results of open reduction and internal fixation (ORIF) for acetabular fractures should be stratified by age in these patients. This study seeks to determine whether the age of the patient influences the results of the ORIF for acetabular fractures. METHODS: We performed a retrospective analysis of prospectively collected data on 53 elderly patients with displaced acetabular fractures who underwent ORIF between May 2004 and May 2011. Patients were divided into two groups by age: young-old group (60-74 years) and old-old group (75-90 years). The number of patients in each group was 28 and 25. The reduction quality and clinical function was evaluated using the Matta criteria and modified Postel Merle D'Aubigne Score, respectively. Operative time, bleeding amount, and complications were recorded. RESULTS: Patients in old-old group had significantly lower anatomical reduction rate (p = 0.024), less operative time (p = 0.021), and less bleeding amount (p = 0.016) than those in the young-old group. The reduction quality in the young-old group was strongly associated with clinical function (p < 0.05). However, no difference in clinical function was detected among the different reduction qualities in the old-old group (p > 0.05). Moreover, no significant difference in clinical functions (p = 0.787) and complications (p = 0.728) was detected between the two groups. CONCLUSIONS: Old-old patients may expect comparable clinical functions and complications with young-old patients. The reduction quality in old-old patients may be not significantly associated with clinical function. Different treatment strategies may be applied for acetabular fractures with ORIF in different age groups.

Ablation of the inferior olive prevents H-reflex down-conditioning in rats.

We evaluated the role of the inferior olive (IO) in acquisition of the spinal cord plasticity that underlies H-reflex down-conditioning, a simple motor skill. The IO was chemically ablated before a 50-day exposure to an operant conditioning protocol that rewarded a smaller soleus H-reflex. In normal rats, down-conditioning succeeds (i.e., H-reflex size decreases at least 20%) in 80% of animals. Down-conditioning failed in every IO-ablated rat (P< 0.001 vs. normal rats). IO ablation itself had no long-term effect on H-reflex size. These results indicate that the IO is essential for acquisition of a down-conditioned H-reflex. With previous data, they support the hypothesis that IO and cortical inputs to cerebellum enable the cerebellum to guide sensorimotor cortex plasticity that produces and maintains the spinal cord plasticity that underlies the down-conditioned H-reflex. They help to further define H-reflex conditioning as a model for understanding motor learning and as a new approach to enhancing functional recovery after trauma or disease.

The inferior olive is essential for long-term maintenance of a simple motor skill.

The inferior olive (IO) is essential for operant down-conditioning of the rat soleus H-reflex, a simple motor skill. To evaluate the role of the IO in long-term maintenance of this skill, the H-reflex was down-conditioned over 50 days, the IO was chemically ablated, and down-conditioning continued for up to 102 more days. H-reflex size just before IO ablation averaged 62(±2 SE)% of its initial value (P < 0.001 vs. initial). After IO ablation, H-reflex size rose to 75-80% over ∼10 days, remained there for ∼30 days, rose over 10 days to above its initial value, and averaged 140(±14)% for the final 10 days of study (P < 0.01 vs. initial). This two-stage loss of down-conditioning maintenance correlated with IO neuronal loss (r = 0.75, P < 0.01) and was similar to the loss of down-conditioning that follows ablation of the cerebellar output nuclei dentate and interpositus. In control (i.e., unconditioned) rats, IO ablation has no long-term effect on H-reflex size. These results indicate that the IO is essential for long-term maintenance of a down-conditioned H-reflex. With previous data, they support the hypothesis that IO and cortical inputs to cerebellum combine to produce cerebellar plasticity that produces sensorimotor cortex plasticity that produces spinal cord plasticity that produces the smaller H-reflex. H-reflex down-conditioning appears to depend on a hierarchy of plasticity that may be guided by the IO and begin in the cerebellum. Similar hierarchies may underlie other motor learning.

Identification and cloning of class II and III chitinases from alkaline floral nectar of Rhododendron irroratum, Ericaceae.

MAIN CONCLUSION: Class II and III chitinases belonging to different glycoside hydrolase families were major nectarins in Rhododendron irroratum floral nectar which showed significant chitinolytic activity. Previous studies have demonstrated antimicrobial activity in plant floral nectar, but the molecular basis for the mechanism is still poorly understood. Two chitinases, class II (Rhchi2) and III (Rhchi3), were characterized from alkaline Rhododendron irroratum nectar by both SDS-PAGE and mass spectrometry. Rhchi2 (27 kDa) and Rhchi3 (29 kDa) are glycoside hydrolases (family 19 and 18) with theoretical pI of 8.19 and 7.04. The expression patterns of Rhchi2 and Rhchi3 were analyzed by semi-quantitative RT-PCR. Rhchi2 is expressed in flowers (corolla nectar pouches) and leaves while Rhchi3 is expressed in flowers. Chitinase in concentrated protein and fresh nectar samples was visualised by SDS-PAGE and chitinolytic activity in fresh nectar was determined spectrophotometrically via chitin-azure. Full length gene sequences were cloned with Tail-PCR and RACE. The amino acid sequence deduced from the coding region for these proteins showed high identity with known chitinases and predicted to be located in extracellular space. Fresh R. irroratum floral nectar showed significant chitinolytic activity. Our results demonstrate that class III chitinase (GH 18 family) also exists in floral nectar. The functional relationship between class II and III chitinases and the role of these pathogenesis-related proteins in antimicrobial activity in nectar is suggested.