Supracondylar periprosthetic femoral fractures following total knee arthroplasty: treatment with a retrograde intramedullary nail.

Total knee replacement surgery is occasionally complicated by a supracondylar periprosthetic fracture, and this presents a challenging problem in an often frail population. Multiple nonoperative and operative treatments have been described which have the aim of restoring the patient to their pre-injury status. This study retrospectively reviews the results of the largest series to date of 14 such fractures treated by retrograde intramedullary supracondylar nailing and is supportive of its continued use with good functional outcomes, low complication rates, and 100% fracture union.

Three Tesla MRI for the diagnosis of meniscal and anterior cruciate ligament pathology: a comparison to arthroscopic findings.

AIM: To assess the accuracy of 3T magnetic resonance imaging (MRI) in the evaluation of meniscal and anterior cruciate ligament (ACL) injury. MATERIALS AND METHODS: Sixty-one consecutive patients were identified who were referred for evaluation of suspected intra-articular pathology with a 3T MRI and who, subsequently, underwent an arthroscopic procedure of the knee were included for the study. Two musculoskeletal radiologists interpreted the images. The sensitivity, specificity, positive predictive value, and negative predictive value were then calculated for the MRI versus the arthroscopic findings as a reference standard. RESULTS: The sensitivity and specificity for the overall detection of meniscal tears in this study was 84 and 93%, respectively. The results for the medial meniscus separately were 91 and 93% and for the lateral 77 and 93%. The evaluation of ACL integrity was 100% sensitive and specific. The meniscal tear type was correctly identified in 75% of cases and its location in 94%. CONCLUSION: This study demonstrates good results of 3T MRI in the evaluation of the injured knee. Caution should still be given to the interpretation on MRI of a lateral meniscus tear, and it is suggested that the standard diagnostic criteria of high signal reaching the articular surface on two consecutive image sections be adhered to even at these higher field strengths.

A high flow turbine CPAP system.

A continuous high flow CPAP system incorporating a turbine blower is described. The system achieves inspiratory flow rates of 150 l/min or more by means of reticulated gas flow and inspired oxygen fractions of 0.21-0.95. Positive airway pressure is provided by weighted disc valves and a modified aviation-type CPAP face mask provides electronic communication with the patient. The mobility of the system also enables its use as an intermittent physiotherapy aid. Work of breathing of the system, as assessed by total pressure fluctuations is at a minimum.

Extraversion, neuroticism, and date of birth: a Southern hemisphere study.

The aim of this study was to determine whether variations in Eysenck Personality Inventory (EPI) scoring among zodiacal birth groups follow a similar pattern for Ss born in the Southern hemisphere to that which has been reported for Northern hemisphere Ss. EPI and birth data were obtained from 450 adult Ss, of whom 338 were New Zealand born. Results for Extraversion significantly matched British findings (p less than .01). Results for Neuroticism were ambiguous. It is concluded that seasonal and climatic influences are unlikely to explain the Extraversion differences between birth groups.

The role of patient factors and implant position in squeaking of ceramic-on-ceramic total hip replacements.

We investigated factors that were thought to be associated with an increased incidence of squeaking of ceramic-on-ceramic total hip replacements. Between June 1997 and December 2008 the three senior authors implanted 2406 primary total hip replacements with a ceramic-on-ceramic bearing surface. The mean follow-up was 10.6 years. The diagnosis was primary osteoarthritis in each case, and no patient had undergone previous surgery to the hip. We identified 74 squeaking hips (73 patients) giving an incidence of 3.1% at a mean follow-up of 9.5 years (4.1 to 13.3). Taller, heavier and younger patients were significantly more likely to have hips that squeaked. Squeaking hips had a significantly higher range of post-operative internal (p = 0.001) and external rotation (p = 0.003) compared with silent hips. Patients with squeaking hips had significantly higher activity levels (p = 0.009). A squeaking hip was not associated with a significant difference in patient satisfaction (p = 0.24) or Harris hip score (p = 0.34). Four implant position factors enabled good prediction of squeaking. These were high acetabular component inclination, high femoral offset, lateralisation of the hip centre and either high or low acetabular component anteversion. This is the largest study to date to examine patient factors and implant position factors that predispose to squeaking of a ceramic-on-ceramic hip. The results suggest that factors which increase the mechanical forces across the hip joint and factors which increase the risk of neck-to-rim impingement, and therefore edge-loading, are those that predispose to squeaking.

Timing of reconstruction of the anterior cruciate ligament in athletes and the incidence of secondary pathology within the knee.

We reviewed a single-surgeon series of 300 athletic patients who had undergone reconstruction of the anterior cruciate ligament in order to establish the relationship between the timing of the reconstruction and the incidence of meniscal and chondral pathology. The patients were divided into five groups according to the time from their injury to surgery as follows: less than two months, two to six months, six to 12 months, 12 to 18 months and more than 18 months. The presence of meniscal tears was recorded and chondral pathology was scored according to the system of the French Society of Arthroscopy. There was a significantly higher chance of a medial meniscal tear occurring in patients undergoing reconstruction after one year from their injury (odds ratio (7.99, p = 0.004). The odds of having a lateral meniscal tear did not change significantly with an increasing interval to reconstruction. The chance of patients developing degenerative changes was found to be significantly higher in the groups operated on after six months from injury (odds ratio 4.04, p = 0.005). We advocate that patients with deficiency of the anterior cruciate ligament should be counselled that there is a significant relationship between the duration of the instability of their knee and the subsequent incidence of both chondral changes and meniscal tears. In order to minimise these risks, we recommend that reconstruction be performed within the first year from injury.

Ceramic-on-ceramic bearing surface and risk of revision due to dislocation after primary total hip replacement.

Dislocation is a common reason for revision following total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary total hip replacements with a diagnosis of osteoarthritis collected by the Australian Orthopaedic Association National Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic heads and to have been implanted in younger patients. The size of the head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the head and age. There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (< or = 28 mm) of the head were used in younger patients (< 65 years) (hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (> or = 65 years) (hazard ratio = 1.73, p = 0.016).

The effect of obesity on the mid-term survival and clinical outcome of cementless total hip replacement.

The outcome of total hip replacement (THR) is potentially affected by the body mass index (BMI) of the patient. We studied the outcome of 2026 consecutive primary cementless THRs performed for osteoarthritis. The mean follow-up was 6.3 years (0 to 11.71) and no patient was lost to follow-up for survival analysis. The patients were divided into two groups according to their BMI as follows: non-obese (BMI < 30 kg/m(2)) and obese (BMI > or = 30 kg/m(2)). The obese patient undergoing surgery was found to be significantly younger (p < 0.001). The log-rank test for equality of survival showed no difference in the mid-term survival (p = 0.552) with an estimated survival at 11 years of 95.2% (95% CI 92.5 to 98.0) in the non-obese and 96.7% (95% CI 94.9 to 98.5) in the obese groups. The clinical and radiological outcome was determined in a case-matched study performed on 134 obese individuals closely matched with 134 non-obese controls. The non-obese group was found to have a significantly higher post-operative Harris hip score (p < 0.001) and an increased range of movement, but overall satisfaction with surgery was comparable with that of the obese patients. Radiological analysis of the acetabular and femoral components showed no significant differences with regard to radiolucent lines, osteolysis, ingrowth of the femoral component, the acetabular inclination angle or alignment of the femoral component. Our results suggest that the survival of cementless THR is not adversely affected by obesity. Obese patients can therefore be counselled that despite a lower clinical score, they should expect to be satisfied with the result of their THR with a mid-term survival rate equivalent to that of non-obese patients.

The impact of obesity on the mid-term outcome of cementless total knee replacement.

We evaluated 535 consecutive primary cementless total knee replacements (TKR). The mean follow-up was 9.2 years (0.3 to 12.9) and information on implant survival was available for all patients. Patients were divided into two groups: 153 obese patients (BMI > or = 30) and 382 non-obese (BMI < 30). A case-matched study was performed on the clinical and radiological outcome, comparing 50 knees in each group. We found significantly lower mean improvements in the clinical score (p = 0.044) and lower post-operative total clinical scores in the obese group (p = 0.041). There was no difference in the rate of radiological osteolysis or lucent lines, and no difference in alignment. Log rank test for survival showed no significant differences between the groups (p = 0.167), with a ten-year survival rate of 96.4% (95% confidence interval (CI) 92 to 99) in the obese and 98% (95% CI 96 to 99) in the non-obese. The mid-term survival of TKR in the obese and the non-obese are comparable, but obesity appears to have a negative effect on the clinical outcome. However, good results and high patient satisfaction are still to be expected, and it would seem unreasonable to deny patients a TKR simply on the basis of a BMI indicating obesity.

Identification of Shiga-like toxin type II producing Escherichia coli using the polymerase chain reaction and a digoxigenin labelled DNA probe.

Epidemiological studies have demonstrated that enterohaemorrhagic strains of Escherichia coli which cause the haemolytic uremic syndrome in humans and the oedema disease in pigs more frequently produce Shiga-like toxin type II (SLT-II) than any other member of the Shiga-like toxin family. A technique has been developed for the identification of SLT-II producing E. coli using the polymerase chain reaction (PCR) and a digoxigenin (DIG)-labelled DNA probe to facilitate the early detection and epidemiological analysis of these pathogens. Whole cell DNA liberated from isolated colonies during the denaturation step of PCR was amplified using a primer pair which is homologous to the slt-II gene sequences. The amplification products were transferred directly to a nitrocellulose membrane or following agarose gel electrophoresis and DNA denaturation. A chemically labelled DNA probe, prepared using PCR with the incorporation of DIG, was used to identify the PCR products of strains which produced SLT-II or a variant of SLT-II.

Detection of Shiga toxin-producing Shigella dysenteriae type 1 and Escherichia coli by using polymerase chain reaction with incorporation of digoxigenin-11-dUTP.

A technique has been developed for the detection of Shiga toxin- and Shiga-like toxin type I (ShT/SLT-I)-producing Shigella dysenteriae type 1 and Escherichia coli by using the polymerase chain reaction with the incorporation of digoxigenin-11-dUTP. Target DNA liberated from whole cells was amplified, using primer pairs homologous to the A-subunit genes of ShT/SLT-I. The TTP analog digoxigenin-11-dUTP was incorporated into the reaction mixture, permitting nonradioactive labeling of the amplified DNA. The labeled polymerase chain reaction products were hybridized to specific gene sequences immobilized on a nitrocellulose membrane and detected by using an alkaline phosphatase-conjugated antibody to digoxigenin and the enzyme substrates. Toxin-producing strains of E. coli and S. dysenteriae type 1 were identified as colored spots on the membrane. Because this technique does not require DNA purification, gel electrophoresis, or radioactive DNA probes, it is suitable for the clinical detection of ShT/SLT-I-producing strains of S. dysenteriae type 1 and E. coli.

Cloning and expression of the exfoliative toxin B gene from Staphylococcus aureus.

Exfoliative toxin type B is produced by bacteriophage group II strains of Staphylococcus aureus and is a causative agent of staphylococcal scalded-skin syndrome. In addition to exfoliative toxin B, most isolates also produce a bacteriocin and are immune to the action of the bacteriocin. These phenotypes, as well as resistance to cadmium, were lost after elimination of a 37.5-kilobase plasmid, pRW001, from S. aureus UT0007. Transduction and transformation showed that pRW001 carries the structural genes for four phenotypic characteristics of S. aureus UT0007: (i) exfoliative toxin B production, (ii) bacteriocin production, (iii) bacteriocin immunity, and (iv) resistance to Cd(NO3)2. The exfoliative toxin B structural gene (etb), which is located on a 1.7-kilobase HindIII fragment of pRW001, was cloned in the plasmid pDH5060 and transformed into phage group III S. aureus RN4220. Transformant clones produced extracellular exfoliative toxin B that was biologically active in the neonatal mouse assay. In the Escherichia coli genetic background, the exfoliative toxin B gene was expressed only after being cloned into the positive selection-expression vector pSCC31. The structural gene for cadmium resistance was also isolated on an HindIII fragment of pRW001 cloned in pDH5060. The loci for the exfoliative toxin B gene and the cadmium resistance gene(s) were identified on a restriction map of plasmid pRW001.

Identification of a B subunit gene promoter in the Shiga toxin operon of Shigella dysenteriae 1.

The Shiga toxin operon (stx) is composed of A and B subunit genes which are transcribed as a bicistronic mRNA from a promoter which lies 5' to the stxA gene. Northern (RNA) blot and primer extension analyses revealed the existence of a second stxB gene transcript. Recombinant plasmids which carried the stxB gene without the stx operon promoter and with the influence of a vector promoter abrogated produced STX B polypeptides, suggesting that the stxB gene mRNA was transcribed from an independent promoter and was not produced by endoribonucleotic processing of the bicistronic mRNA. Examination of the DNA sequences 5' to the stxB gene transcription initiation site which were carried by the recombinant plasmids revealed a region with high homology to the consensus for Escherichia coli promoters. Deletion and mutation of this region affected StxB and holotoxin production, establishing its role in the regulation of the stxB gene. Comparison of the promoters by using a transcription analysis vector revealed that the stxB gene promoter differed from the stx operon promoter in that was approximately sixfold less efficient and was not repressed by iron. Identification of a second promoter in the stx operon indicates that independent transcription of the stxB gene may regulate overproduction of the STX B polypeptides and may contribute to the 1A:5B subunit stoichiometry of the holotoxin.