The diagnosis of periprosthetic joint infection may be difficult with patients presenting months or years after initial surgery with surgery-associated or haematogenously spread bacteria. Synovasure™ is a new point of care assay that measures alpha defensin produced by activated leucocytes in joints; it is licensed for the diagnosis of periprosthetic joint infections. We sought to include alpha defensin testing in a testing algorithm to improve the diagnosis of periprosthetic joint infection. An algorithm for testing patients with suspected periprosthetic joint infection was developed and agreed among knee surgeons in Gloucestershire, UK. Data was prospectively collected on all tests performed along with information on how the results of the alpha defensin test altered patient management. A sample of joint fluid was taken using aseptic technique in theatre and tested for alpha defensin production at the point of care. Samples were then referred for standard culture and selected samples for 16SrRNA PCR. 12 patients were assayed for alpha defensin in periprosthetic joint fluid during 2015. 7 patients were female, 5 male and ages ranged 64–86 years. 10 patients had a negative point of care alpha defensin test. Only 2 of these patients also had a leukeocyte esterase (LE) test performed and these were negative. The culture results from all samples were negative for both direct and enrichment cultures. 3 samples also had 16SrRNA PCR performed and these were negative. 2 patient samples tested positive for alpha defensin. LE tests were not performed. Both samples were culture negative on direct and enrichment culture however both samples were also referred for 16SrRNA PCR which detected DNA compatible with Staphylococcus caprae/capitis/ saccharolyticus/epidermidis from 1 patient and DNA with homology to Streptococcus gallolyticus/equinusI for the other. Alpha defensin testing improved the diagnosis of prosthetic joint infection. A positive alpha defensin test may be used to select patients for whom 16SrRNA PCR testing is useful in order to maximise the potential for pre-revision infection diagnosis and the planning of appropriate adjuncts such as antibiotic laden cement or calcium sulphate beads. Negative alpha defensin tests on aspirated joint fluid may avoid the need for arthroscopy and biopsy and allow planning for single stage revision surgery without concern for infection.
The purpose of this study was to assess the clinical and radiological outcome following spring plate fixation of posterior wall fractures. Spring plates are fashioned from a one third tubular plate cutting through one of the holes in the plate and bending the sharp edges through 90 degrees allowing screw fixation of small acetabular margin fragments well away from the joint reducing the risk of joint penetration. From July 1993 to August 2004, 89 patients with displaced posterior wall fractures underwent posterior wall fixation with one or more spring plates. Patients were assessed post-operatively with a CT scan and annually for up to 5 years for a clinical and radiological assessment. Clinically patients were graded according to the Epstein modification of Merle d'Aubigné/Postel Hip Score. The radiographs were graded using the Roentographic Grade criteria used by Matta. Patients were reviewed at a mean 55 month follow-up. There were 12 post-operative complications. Clinically excellent or good results were seen in 70% and radiologically in 70%. There were 15 revisions for osteonecrosis, infection and osteoarthritis. 91% (20/22) of fractures had excellent/good clinical results if reduced anatomically compared with 66% (24/36) of those reduced to within 2mm as assessed by the post-operative CT scan. Only 44% (8/18) of those reduced leaving a gap of greater than 2mm had an excellent/good clinical result. Posterior wall fractures can be treated successfully by the use of spring plates. Clinical results correspond closely with radiological appearance. The accuracy of reduction correlates highly with the subsequent prognosis and we recommend routine post-operative CT scanning to identify misplaced metalwork and the accuracy of reduction to help predict prognosis.
We aimed to assess a simple radiological method of predicting redisplacement of paediatric forearm fractures. The Cast Index (CI) is the ratio of sagittal to coronal width from the inside edges of the cast at the fracture site. CI of 0.7 was used as the benchmark in predicting fracture redisplacement. Case records and radiographs of 1001 children who underwent a manipulation under general anaesthesia for a displaced fracture of the distal forearm were studied. Redisplacement was defined as more than 15 degrees of angulation and/or more than 80 percent of translational displacement on check radiographs at 2 weeks. Angulation (in degrees) and translation displacement (in percentage) were measured on the initial and check radiographs. The Cast index was measured on the check radiographs. Good intra and inter observer reproducibility was observed for both these measurements. The cast index has been previously validated in an experimental study. The adequacy of reduction after manipulation was estimated by the postreduction translation and angulation of the radius and ulna in anteroposterior and lateral plain film radiographs. The 1001 patients who qualified for the study, fracture redisplacement was seen in 107 cases at the all important two week follow up. Seven hundred and fifty-two patients had cast indices of 0.8 or less whilst 249 had casting indices of 0.81 or more. In patients with cast indices of 0.8 or less, the displacement rate was only 5.58%. However, in patients with cast indices of 0.81 or more, the displacement rate was 26%. Initial displacement, angulation and the post manipulation cast index were the three factors which were significantly higher in the redisplacement group. No statistically significant difference was seen for age, sex or ethnicity. Nor were statistical differences noted in initial angular deformity, initial displacement and seniority of the surgeon. There was no statistical difference in patients with cast indices between 0.7 and 0.8. Cast index is a simple reliable radiographic measurement to predict the redisplacement of forearm fractures in children. A plaster with a CI of >
0.81 is prone to redisplacement. A high cast index is associated with redisplacement of fractures and should therefore be considered when moulding casts is distal forearm fractures.
Polyethylene wear and osteolysis continue to be associated with failure of total hip arthroplasty. The advent of highly cross linked polyethylene may potentially reduce such wear. The aim of this study was to compare the rate of wear of acetabular polyethylene using conventional cross linked versus highly cross linked polyethylene. From June 2001 to September 2003, 119 patients were followed prospectively for up to five years on an annual basis in a double blinded, randomised trial. The mean age of patients was 59 years (range 48 to 75 yrs). The radiographs have been analyzed using previously validated measurement software to assess linear, three dimensional and volumetric wear. The five year results show significantly reduced wear rates for highly cross linked polyethylene compared to conventional polyethylene. There was no statistically significant difference between groups with respect to age, sex, operative side, surgeon, cup abduction angle, cup anteversion or size of cup. The reduction in wear shown after five years with the highly cross linked polyethylene is highly encouraging and is consistent with in vitro wear simulator testing. This may reduce failure of total hip arthroplasties due to wear and osteolysis over the medium to long term.
All patients were assessed postoperatively with a CT scan and annually for up to 5 years for a clinical and radiological assessment. Clinically patients were graded according to the Epstein modification of Merle D’Aubigne/ Postel Hip Score. The radiographs were graded using the Roentographic Grade criteria used by Matta.
At the time of operation 40% of fractures were reduced anatomically. There were 12 post operative complications. Clinically excellent or good results were seen in 70% and radiologically in 68%. There were 11 revisions for osteonecrosis, infection and osteoarthritis. There was a high correlation between the accuracy of the reduction and the subsequent prognosis.
The aim of this study was to compare arthroscopy and MRI as methods of assessing cartilage quality in the wrist.
The overall Kappa score was 0.43 which shows ‘moderate’ correlation between the two methods. Individual Kappa scores for the articular surfaces were lunate fossa 0.21, proximal lunate 0.62, distal lunate 0.22, proximal capitate 0.42 and scaphoid fossa 0.56.
The aim of this study was to measure intra-articular gentamicin levels at the 2nd stage revision following the use of an antibiotic impregnated articulating spacer. Infected total knee replacements are a cause of considerable morbidity often requiring revision in two stages. Rings of bone cement, cement moulds and spacer devices are available for use following the initial debridement and removal of infected metalwork. The availability of antibiotic impregnated articulating spacers are potentially attractive to achieve a high local dose of antibiotic and to maintain a good range of movement. Seven patients underwent a two stage revision of their total knee replacements. Following the initial debridement an antibiotic impregnated articulating spacer was cemented in place. At the 2nd stage revision a perioperative joint aspirate and blood sample was taken and gentamicin levels measured. The range of movement was assessed. The average gentamicin levels were 0.72mg/l (0.24 – 2.36mg/l). A good range of movement was maintained in all cases. At these levels the gentamicin would be therapeutic. Antibiotic impregnated articulating spacers possess several potential advantages to the revision knee surgeon by helping maintain the range of movement and provide local release of antibiotics. Their use should be considered in such cases.
