Biomechanical specimen assessment by low dose biplanar X-ray study of fusion constructions using a posterior lumbar cage with integrated anchors and posterior adjunctive fixators.

The objective was to compare L4/5 range of motions of fusion constructs using anchored cages. Twelve human cadaveric spine were tested in intact condition, and divided into TLIF and PLIF groups. Testing consisted in applying pure moments in flexion-extension, lateral bending and axial rotation. The computation of intersegmental motion was assessed using 3 D biplanar radiographs. In TLIF group, the addition of contralateral transfacet decreased flexion-extension motion (39%; p = 0.036) but without difference with the ipsilateral pedicle screw construction (53%; p = 0.2). In PLIF group, the addition of interspinous anchor reduced flexion-extension motion (12%; p = 0.036) but without difference with the bilateral pedicle screw construction (17%; p = 0.8).

Anterior dislocation of a total hip replacement. Radiographic and CT-scan assessment. Behavior following conservative management.

BACKGROUND: Hip dislocation is one of the most frequent complications of total hip replacement. The direction of dislocation matters. Most dislocations are posterior; anterior dislocation remains rare and its treatment is controversial. STUDY OBJECTIVES: To clinically and radiologically evaluate the outcomes of the conservative (orthopaedic without revision surgery) treatment of anterior hip dislocations after total hip replacement by immobilisation of the hip in 45 degrees flexion, 10 to 20 degrees abduction and neutral rotation (deck chair position). MATERIALS AND METHODS: Between 1997 and 2007, 19 patients (11 women, 7 men), aged between 36 and 89 years old (average age 64.6 years), operated on for hip osteoarthritis using a posterolateral approach, presented with anterior dislocation of their cemented total hip arthroplasty. Instability during extension associated with external rotation was noted at surgery in eight cases. Ten dislocations occurred in the immediate postoperative period (within 48 hours) and nine within an average postoperative delay of 39 days (6-82). After reduction of the dislocation by closed manipulation, the patients were treated by immobilisation in the deck chair position for an average of 2 weeks (10-21 days). Radiological and functional assessment (based on the Merle d'Aubigné score [PMA]) was performed on average at 4 years after surgery. The inclination of the cup in the frontal plane and any lengthening of the operated extremity were measured on an AP pelvic plain film with the patient in the standing position. Cup and femoral stem anteversion were calculated by CT-scan in 16 cases. RESULTS: At the last follow-up, four patients had had recurrent anterior dislocations (one patient had had two dislocations). They were again treated with immobilisation in the deck chair position for two weeks without further recurrence. None of the patients underwent revision surgery on the temporarily unstable operated hip. Thirteen patients had no pain and eleven had an unlimited walking perimeter. The final average PMA score was 16 (12-18). The patients who presented with one or two recurrences had a PMA of 18 in the final follow-up. Six patients presented with at least 5 mm of shortening (average: 10 mm, maximum 25 mm) with one case of 10 mm of lengthening. The average cup inclination angle in frontal plane views was 48 degrees (40-57 degrees). It was more than 50 degrees in seven cases. The average cup anteversion in CT-scan was 30 degrees (14-60 degrees). The average femoral anteversion in CT-scan was 24 degrees (3-52 degrees). A total of 12 implants (eight cups and four femoral stems) had at least 25 degrees excessive anteversion on CT-scan assessment. DISCUSSION, CONCLUSION: Anterior dislocation after total hip replacement is associated with approximately 10 degrees of excessive femoral and acetabular anteversion respectively. Nevertheless, correction of these architectural anomalies is not necessary because immobilisation in the deck chair position for 2 weeks effectively prevents recurrence and results in satisfactory medium-term functional results.

Genomic screening for blood-borne viruses in transfusion settings.

The residual risk of post-transfusion human immunodeficiency virus (HIV) infection is low but slightly higher for hepatitis B virus (HBV) and hepatitis C virus (HCV), the main reason being viraemia during the window period preceding antibody or antigen detection by enzyme immunoassays. Immunosilent-infected individuals and carriers of distant viral variants also play an unquantifiable role. Multiple techniques, e.g. reverse transcription-polymerase chain reaction (RT-PCR), PCR, ligase-chain reaction, nucleic acid sequence-based amplification (NASBA) and transcription-mediated amplification (TMA) have been developed to amplify and detect viral genomes as single or multiplex assays. Equipment providing various degrees of automation has been adapted to these techniques. Applying nucleic acid amplification techniques (NAT) to blood screening, two main approaches have been advocated: plasma pool and single-donation testing. Pool testing presents the advantage of lower cost and readily available equipment although it is prone to false negative and positive reactions. The time required to identify infected donations is incompatible with blood component release, and may lead to product waste. Single-unit testing, although appealing, is not yet fully automated and potentially very costly unless a systematic multiplex approach is taken. Although technically feasible, NAT applied to the blood supply needs to be clinically evaluated and its cost efficiency assessed in the general public health context. However, pool NAT is currently implemented in continental Europe and the USA.

Feasibility and usefulness of an efficient anti-HBc screening programme in blood donors.

Post-transfusion hepatitis B remains a risk for recipients of hepatitis B surface antigen (HBsAg) screened blood. Anti-hepatitis B core antibody (anti-HBc) screening may help reduce this risk. To evaluate its usefulness, 9,238 East Anglian blood donors were screened for anti-HBc. Those with isolated anti-HBc were identified with two confirmatory anti-HBc and anti-HB surface antibody (anti-HBs) assays. The prevalence of anti-HBc reactions in screening and confirmatory assays was 1.29% and 0.35%, respectively. The level of reactivity was significantly higher when two anti-HBc assays gave concordant results or, being concordant, were anti-HBs positive. All isolated anti-HBc-positive units (0.04%) were negative for additional HBV markers including DNA tested with nested polymerase chain reaction (PCR). A 0.31% prevalence of past HBV infection was found in this population, all carrying both anti-HBc and anti-HBs antibody, most above the protective level (0.1 IU/ml). The proposed screening schemes would limit the number of deferred donors and discarded units and keep the testing time within the remit of routine blood banking practices for an additional cost of approximately 1 pound per unit. However, no evidence was found in this donor population to suggest that anti-HBc screening would significantly reduce the incidence of post-transfusion hepatitis B.

Assessment by gene amplification and serological markers of transmission of HIV-1 from hemophiliacs to their sexual partners and secondarily to their children.

The transmission of HIV-1 infection from men with hemophilia A to their female sex partners and secondarily to their children was studied by serological markers including antibody, antigen, and HIV genome as detected by the polymerase chain reaction (PCR). Among 27 sex partners of 26 seropositive hemophiliacs, 5 were seropositive-PCR positive (active), 11 were seronegative-PCR positive (latent), and 11 were negative for both. These results were confirmed by testing serial serum samples and paired samples of DNA from peripheral blood mononuclear cells (PBMCs) and serum from seronegative women. PCR negativity in exposed women was correlated with the use of condoms (p less than 0.01). Eight children from five couples were seronegative. However, HIV-1 infection as detected by PCR was transmitted to 60% of exposed children, including one from a seronegative-PCR positive mother.