Comparision of blood loss between computer assisted and conventional total knee arthroplasty

Background:

Bleeding during total knee arthroplasty (TKA) can cause significant morbidity and mortality. One proposed benefit of computer assisted TKA is decreased bleeding as the femoral canal is not invaded. This study assessed blood loss between computer assisted surgery (CAS) and conventional TKA.

Materials and Methods:

73 consecutive patients (37 males, 36 females) underwent primary TKA between 2006 and 2009. Thirty eight patients underwent navigated TKA and 35 underwent conventional TKA for symptomatic osteoarthritis of the knee. These patients were matched for age, gender, and body mass index (BMI). Average age was 70.3 years (range 47-91 years). Mean BMI was 30 (range 17-49). Average preoperative hemoglobin was 13.26 g/dL (range 8.7-18.4 g/dL) in the navigated group and 13.47 g/dL (range 9.6-15.8 g/dL) in the conventional group (P = 0.9). Average tourniquet time was 110 min (range 90-150 min) in the navigated group and 96.7 min (range 60-145 min) in the conventional group (P = 0.77).

Results:

Average postoperative hemoglobin in the navigated group was 10.34 g/dL (range 7.5-14.8 g/dL) and in the conventional group was 10.03 g/dL (range 7.5-12.2 g/dL) (P = 0.17). Six patients in both groups required blood transfusions. The mean drain collection was 599 mL (range 150-1370 mL) in the navigated group and 562 mL (range 750-1000 mL) in the conventional group (P = 0.1724). These results suggest that there is no significant reduction in blood loss in CAS TKA.

Conclusion:

These results suggest that there is no significant difference in blood loss in CAS TKA and conventional TKA. This study also highlights the heterogeneity of methods used in studies related to CAS TKA. We believe that there is a need for a large multicenter prospective randomized controlled trial to be performed before a consensus can be reached on the influence of CAS techniques on blood loss during primary TKA.     

Type IIB Tampa: a variant of von Willebrand disease with chronic thrombocytopenia, circulating platelet aggregates, and spontaneous platelet aggregation

Type IIB von Willebrand disease is characterized by enhanced ristocetin- induced platelet aggregation and absence of large von Willebrand factor multimers from plasma. An alteration of the von Willebrand factor molecule resulting in increased reactivity with platelets appears to be the basis for these abnormalities. We have now identified a new variant of type IIB von Willebrand disease in a family in which the four affected members also have chronic thrombocytopenia, in vivo platelet aggregate formation, and spontaneous platelet aggregation in vitro. In spite of repeatedly prolonged bleeding times and persistent thrombocytopenia, their bleeding diathesis is only moderate.     

Splanchnic artery aneurysms and pseudoaneurysms: transcatheter embolization

Over the past 7 years, eight patients with splanchnic artery aneurysms and pseudoaneurysms were studied and treated. Transcatheter embolization resulted in occlusion of the lesions in all eight patients. Potentially risky and difficult surgery was avoided completely in four patients. Three patients had elective surgery at a later date when their condition was more stable. The remaining patient had definitive surgery after embolization. Transcatheter embolization should be the initial treatment of choice in splanchnic artery aneurysms and pseudoaneurysms.     

Neural and Behavioral Correlates of Aberrant Salience in Individuals at Risk for Psychosis

The “aberrant salience” model proposes that psychotic symptoms first emerge when chaotic brain dopamine transmission leads to the attribution of significance to stimuli that would normally be considered irrelevant. This is thought to occur during the prodromal phase of psychotic disorders, but this prediction has not been tested previously. In the present study, we tested this model in 18 healthy volunteers and 18 unmedicated individuals at ultra-high risk of psychosis. Subjects performed the Salience Attribution Test, which provides behavioral measures of adaptive and aberrant motivational salience, during functional magnetic resonance imaging to assess neural responses to relevant and irrelevant stimulus features. On a separate occasion, the same subjects were also studied with [¹⁸F]fluorodopa positron emission tomography to measure dopamine synthesis capacity. Individuals at ultra-high risk of psychosis were more likely to attribute motivational salience to irrelevant stimulus features (t(26.7) = 2.8, P = .008), and this bias was related to the severity of their delusion-like symptoms (r = .62, P = .008). Ventral striatal responses to irrelevant stimulus features were also correlated with delusion-like symptoms in the ultra-high risk group (r = .59, P = .017). Striatal dopamine synthesis capacity correlated negatively with hippocampal responses to irrelevant stimulus features in ultra-high risk individuals, but this relationship was positive in controls. These data are consistent with the hypothesis that aberrant salience processing underlies psychotic symptoms and involves functional alterations in the striatum, hippocampus, and the subcortical dopamine system.Key words: psychosis, aberrant salience, salience attribution test, functional magnetic resonance imaging, positron emission tomography, dopamine