Development of a clinical prediction rule for mobility status at discharge in patients with total knee arthroplasty: Using a decision tree model.

BACKGROUND: Total knee arthroplasty (TKA) is an effective treatment to improve mobility in patients with severe knee osteoarthritis. However, some patients continue to have poor mobility after surgery. The preoperative identification of patients with poor mobility after TKA allows for better treatment selection and appropriate goal setting. The purpose of this study was to develop a clinical prediction rule (CPR) to predict mobility after TKA. METHODS: This study included patients undergoing primary TKA. Predictors of outcome included patient characteristics, physical function, and psychological factors, which were measured preoperatively. The outcome measure was the Timed Up and Go test, which was measured at discharge. Patients with a score of ≥11 s were considered having a low-level of mobility. The classification and regression tree methodology of decision tree analysis was used for developing a CPR. RESULTS: Of the 101 cases (mean age, 72.2 years; 71.3 % female), 26 (25.7 %) were classified as low-mobility. Predictors were the modified Gait Efficacy Scale, age, knee pain on the operated side, knee extension range of motion on the non-operated side, and Somatic Focus, a subscale of the Tampa Scale for Kinesiophobia (short version). The model had a sensitivity of 50.0 %, a specificity of 98.7 %, a positive predictive value of 92.9 %, a positive likelihood ratio of 37.5, and an area under the receiver operating characteristic curve of 0.853. CONCLUSION: We have developed a CPR that, with some accuracy, predicts the mobility outcomes of patients after TKA. This CPR may be useful for predicting postoperative mobility and clinical goal setting.

Locomotor activity and histological changes observed in a mouse model of knee osteoarthritis.

[Purpose] This study aimed to elucidate the changes in locomotor activity in a mouse model of knee osteoarthritis (OA). [Materials and Methods] Fourteen 20-week-old mice were divided into control and OA groups. Knee OA was surgically induced under anesthesia by destabilizing the meniscus. The OA group was reared normally for 8 weeks following surgery, during which OA was induced. Locomotor activity was measured every hour for 8 weeks using an infrared locomotor activity measurement device. Histological changes were evaluated according to the classification-system of Glasson. [Results] Locomotor activity in the OA group significantly decreased up to 2 weeks after surgery. Histological findings in the control group revealed an irregular cartilage surface in a portion of the tibia with no other abnormalities. Contrastingly, those in the OA group had eburnation of the medial femoral condyle, as well as fibrillation and fissures in the medial tibial plateau. Histological scores in the OA group were significantly higher than the control group. [Conclusion] Locomotor activity evaluations, in addition to histological scores and findings, are imperative for studies aiming to clarify the disease state and effect of interventions using mice models.

Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system.

Bone homeostasis is regulated by mechanical stimulation (MS). The sensory mechanism of bone tissue for MS remains unknown in the maintenance of bone homeostasis. We aimed to investigate the sensory mechanism from osteoblasts to sensory neurons in a coculture system by MS of osteoblasts. Primary sensory neurons isolated from dorsal root ganglia (DRG) of neonatal, juvenile, and adult mice and osteoblasts isolated from calvaria of neonatal mice were cocultured for 24 h. The responses in DRG neurons elicited by MS of osteoblasts with a glass micropipette were detected by increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) with fluo 3-AM. In all developmental stages mice, [Ca(2+)](i)-increasing responses in osteoblasts were promptly elicited by MS. After a short delay, [Ca(2+)](i)-increasing responses were observed in neurites of DRG neurons. The osteoblastic response to second MS was largely attenuated by a stretch-activated Ca(2+) channel blocker, gadolinium. The increases of [Ca(2+)](i) in DRG neurons were abolished by a P2 receptor antagonist; suramin, a P2X receptor antagonist, pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate; and an ATP-hydrolyzing enzyme, apyrase. Satellite cells were found around DRG neurons in cocultured cells of only neonatal and juvenile mice. After satellite cells were removed, excessive abnormal responses to MS of osteoblasts were observed in neonatal neurites with unchanged osteoblast responses. The present study indicated that MS of bone tissue elicited afferent P2X receptor-mediated purinergic transmission to sensory neurons in all stages mice. This transmission is modulated by satellite cells, which may have protective actions on sensory neurons.

A cardioprotective agent of a novel calpain inhibitor, SNJ-1945, exerts beta1 actions on left ventricular mechanical work and energetics.

We have previously shown that a newly developed calpain inhibitor, SNJ-1945 (SNJ), with good aqueous solubility prevents the heart from KCl arrest-reperfusion injury associated with the impairment of total Ca(2+) handling by inhibiting the proteolysis of alpha-fodrin as a cardioplegia. The aim of the present study was to investigate certain actions of this calpain inhibitor, SNJ, on left ventricular (LV) mechanical work and energetics in cross-circulated excised rat hearts undergoing blood perfusion with 40 microM SNJ. Mean end-systolic pressure at midrange LV volume and systolic pressure-volume area (PVA) at mLVV (a total mechanical energy/beat) were significantly increased by SNJ perfusion (P < 0.01). Mean myocardial oxygen consumption per beat (Vo(2)) intercepts (Vo(2) for the total Ca(2+) handling in excitation-contraction coupling and basal metabolism) of Vo(2)-PVA linear relations were significantly increased (P < 0.01) with unchanged mean slopes of Vo(2)-PVA linear relations. Pretreatment with the selective beta(1)-blocker landiolol (10 microM) blocked these effects of SNJ perfusion. There were no significant differences in mean basal metabolic oxygen consumption among normal, 40 microM SNJ, and 10 microM landiolol + 40 microM SNJ groups. Our results indicate that water-soluble SNJ exerted positive actions on mechanical work and energetics mediated via beta(1)-adrenergic receptors associated with the enhancement of total Ca(2+) handling in excitation-contraction coupling and with unchanged contractile efficiency. In clinical settings, this pharmacological action of SNJ is beneficial as an additive agent for cardioplegia.