In vitro characteristics of volume-reduced platelet concentrate stored in syringes

For convenience, small volumes of platelet concentrate (PC) intended for neonatal patients are often dispensed in syringes. The PC, however, may remain in the syringe for up to several hours before the actual transfusion. As there are few data on the effect of such syringe storage on PCs, the in vitro syringe storage properties of small volumes of 1- and 5-day-old units, and volume-reduced units of PC were evaluated. In four separate experiments, PCs were stored in syringes in volumes of 10, 15, or 30 mL for up to 6 hours at 20 to 24 degrees C without agitation. Platelets were evaluated for pH, platelet count, and a variety of biochemical and in vitro functional assays. Results showed that even with the equivalent of a full unit of platelets stored in the syringe for up to 6 hours, the pH did not fall below 6.0. Although there was an increase in lactate production and consumption of glucose, which paralleled the decline in pH, the changes were not greater than those seen in platelets stored up to 5 days in gas-permeable blood bags. Similar results were seen for PCs stored in syringes for 6 hours at 37 degrees C. All of the pH levels recorded at the end of 6 hours of syringe storage were above the minimum required level of pH 6.0. Data from in vitro platelet assays imply that at any time during their shelf life, PCs can be stored in gas-impermeable polypropylene syringes for up to 6 hours and can maintain acceptable storage characteristics; in vivo data are needed to confirm these observations.     

Subrupture tendon fatigue damage

The mechanical and microstructural bases of tendon fatigue, by which damage accumulates and contributes to degradation, are poorly understood. To investigate the tendon fatigue process, rat flexor digitorum longus tendons were cyclically loaded (1–16 N) until reaching one of three levels of fatigue damage, defined as peak clamp‐to‐clamp strain magnitudes representing key intervals in the fatigue life: i) Low (6.0%–7.0%); ii) Moderate (8.5%–9.5%); and iii) High (11.0%–12.0%). Stiffness, hysteresis, and clamp‐to‐clamp strain were assessed diagnostically (by cyclic loading at 1–8 N) before and after fatigue loading and following an unloaded recovery period to identify mechanical parameters as measures of damage. Results showed that tendon clamp‐to‐clamp strain increased from pre‐ to post‐fatigue loading significantly and progressively with the fatigue damage level (p ≤ 0.010). In contrast, changes in both stiffness and hysteresis were significant only at the High fatigue level (p ≤ 0.043). Correlative microstructural analyses showed that Low level of fatigue was characterized by isolated, transverse patterns of kinked fiber deformations. At higher fatigue levels, tendons exhibited fiber dissociation and localized ruptures of the fibers. Histomorphometric analysis showed that damage area fraction increased significantly with fatigue level (p ≤ 0.048). The current findings characterized the sequential, microstructural events that underlie the tendon fatigue process and indicate that tendon deformation can be used to accurately assess the progression of damage accumulation in tendons. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:264–273, 2009     

Interviews for the assessment of long-term incapacity for work: a study on adherence to protocols and principles

Background  

Assessments for long-term incapacity for work are performed by Social Insurance Physicians (SIPs) who rely on interviews with claimants as an important part of the process. These interviews are susceptible to bias. In the Netherlands three protocols have been developed to conduct these interviews. These protocols are expert- and practice-based. We studied to what extent these protocols are adhered to by practitioners.     

Subscapularis function after total shoulder replacement: results with lesser tuberosity osteotomy

Until recently, little consideration was placed on the integrity of the subscapularis tendon after total shoulder arthroplasty. We have noted that several of our patients exhibited loss of internal rotation strength and subscapularis function after total shoulder arthroplasty utilizing an anatomic soft tissue repair of the subscapularis, both with and without bone tunnels. On the basis of those results, we began removing the subscapularis with a small piece of bone by a lesser tuberosity osteotomy in an attempt to achieve improved subscapularis function through bony healing at the repair site. A retrospective review of 28 patients (30 shoulders) was done of patients who had total shoulder arthroplasty performed between 2001 and 2003. The lesser tuberosity and attached subscapularis were repaired through bone tunnels in all cases. The mean follow-up was 1.1 years. Terminal internal rotation was evaluated by the belly-press examination. Subscapularis function was assessed by the patient's ability to tuck in a shirt behind the back, and 25 of 30 patients (83.3%) reported no difficulty. Belly-press examination results were normal in 18 of 30 patients (60%). Removal of the subscapularis through a lesser tuberosity osteotomy results in reliable restoration of internal rotation strength after total shoulder arthroplasty, as measured by the ability to perform a stomach press and to tuck in a shirt. In comparing these results with our earlier cohort of patients with similar demographics and postoperative rehabilitation that had soft tissue repair, improved results were seen in the group that underwent lesser tuberosity osteotomy.