Infection of orthopaedic implants is a significant problem, with increased antibiotic resistance of adherent ‘biofilm’ bacteria causing difficulties in treatment. We have investigated the in vitro effect of a pulsed electromagnetic field (PEMF) on the efficacy of antibiotics in the treatment of infection of implants. Five-day biofilms of Staphylococcus epidermidis were grown on the tips of stainless-steel pegs. They were exposed for 12 hours to varying concentrations of gentamicin or vancomycin in microtitre trays at 37°C and 5% CO. 2. The test group were exposed to a PEMF. The control tray was not exposed to a PEMF. After exposure to antibiotic the pegs were incubated overnight, before standard plating onto blood agar for colony counting. Exposure to a PEMF increased the effectiveness of gentamicin against the five-day biofilms of Staphylococcus epidermidis. In three of five experiments there was reduction of at least 50% in the minimum biofilm inhibitory concentration. In a fourth experiment there was a two-log difference in colony count at 160 mg/l of gentamicin. Analysis of variance (ANOVA) confirmed an effect by a PEMF on the efficacy of gentamicin which was significant at p < 0.05. There was no significant effect with vancomycin

We report two cases of epicondylitis of the elbow occurring after treatment with fluoroquinolone antibiotics. Both patients had intense pain which appeared very shortly after the first dose of the drug and was not relieved by conservative treatment. Ultrasonography revealed extensive inflammatory lesions with pseudonecrotic areas. MRI confirmed the lesions and also showed a subclinical abnormality of the adjoining tendons. The persistent nature of the pain was the indication for surgical release of the extensor mechanism. After operation pain disappeared completely and the patients were able to return to their normal activities. Lesions of the tendo Achillis are a well-known side-effect of treatment with fluoroquinolone. Our two cases show that such lesions may occur elsewhere. They also indicate the need for caution when prescribing these antibiotics to patients at risk of tendon lesions, such as top-level sportsmen or patients on dialysis or steroid treatment

Antibiotic impregnated articulating spacers are used in two-stage revision total knee arthroplasty to deliver local antibiotic therapy while preserving function. We have observed infection control in greater than 95% of cases with functional outcomes approaching those seen in revision for aseptic loosening. Higher failure has been observed with methicillin resistant organisms.

Two-stage revision surgery for infected total knee replacement offers the highest rate of success for the elimination of infection. The use of articulating antibiotic-laden cement spacers during the first stage to eradicate infection also allows protection of the soft tissues against excessive scarring and stiffness. We have investigated the effect of cyclical loading of cement spacers on the elution of antibiotics. Femoral and tibial spacers containing vancomycin at a constant concentration and tobramycin of varying concentrations were studied in vitro. The specimens were immersed and loaded cyclically to 250 N, with a flexion excursion of 45°, for 35 000 cycles. The buffered solution was sampled at set intervals and the antibiotic concentration was established so that the elution could be calculated. Unloaded samples were used as a control group for statistical comparison. The elution of tobramycin increased proportionately with its concentration in cement and was significantly higher at all sampling times from five minutes to 1680 minutes in loaded components compared with the control group (p = 0.021 and p = 0.003, respectively). A similar trend was observed with elution of vancomycin, but this failed to reach statistical significance at five, 1320 and 1560 minutes (p = 0.0508, p = 0.067 and p = 0.347, respectively). However, cyclically loaded and control components showed an increased elution of vancomycin with increasing tobramycin concentration in the specimens, despite all components having the same vancomycin concentration. The concentration of tobramycin influences both tobramycin and vancomycin elution from bone cement. Cyclical loading of the cement spacers enhanced the elution of vancomycin and tobramycin

We have investigated the contaminating bacteria in primary hip arthroplasty and their sensitivity to the prophylactic antibiotics currently in use. Impressions (627) of the gloved hands of the surgical team in 50 total hip arthroplasties were obtained on blood agar. The gloves were changed after draping, at intervals of 20 minutes thereafter, and before using cement. Changes were also undertaken whenever a visible puncture was detected. The culture plates were incubated at 37°C for 48 hours. Isolates were identified and tested for sensitivity to flucloxacillin, which is a recognised indicator of sensitivity to cefuroxime. They were also tested against other agents depending upon their appearance on Gram staining. We found contamination in 57 (9%) impressions and 106 bacterial isolates. Coagulase-negative staphylococci were seen most frequently (68.9%), but we also isolated Micrococcus (12.3%), diphtheroids (9.4%), Staphylococcus aureus (6.6%) and Escherichia coli (0.9%). Of the coagulase-negative staphylococci, only 52.1% were sensitive to flucloxacillin and therefore to cefuroxime. We believe that it is now appropriate to review the relevance of prophylaxis with cefuroxime and to consider the use of other agents

Cephamandole levels in serum and drain fluid were measured in 32 knee replacement operations to determine the benefit of an intravenous dose of antibiotic at the time of tourniquet deflation. Concentrations of cephamandole in drain fluid were directly proportional to the serum concentration at the time of tourniquet release. A 'tourniquet-release' dose of antibiotic increased drain fluid concentration threefold

The diffusion of Fucidin, gentamicin, and clindamycin from acrylic cement was tested in an in vitro system. The activity of Fucidin was very short-lived and only against gram-positive organisms; gentamicin inhibited gram-positive and gram-negative organisms for twenty-two and eleven days respectively; clindamycin had significant action only against gram-positive organisms and retained some activity for fifty-six days. We suggest that the destruction of organisms in the tissues is more likely to be achieved by topical and intravenous administration of antibiotics during the operation than by incorporation of antibiotic in the cement

Discitis after discography is due to bacterial penetration into the intervertebral disc by a contaminated needle and has an incidence of 1% to 4%. We have examined the prophylactic role of cephazolin administered at the time of discography. An experimental study in sheep using radiographic contrast containing Staphylococcus epidermidis showed that either adding the antibiotic to the intradiscal suspension or giving it intravenously 30 minutes before intradiscal inoculation of bacteria prevented any radiographic, macroscopic or histological signs of discitis; all the intervertebral disc cultures were negative. In a prospective clinical study of 127 consecutive patients having lumbar discography, the injected contrast contained cephazolin 1 mg per ml. None of the patients developed clinical or radiographic signs of discitis. We recommend the use of a suitable broad spectrum antibiotic in a single prophylactic dose whenever the intervertebral disc is entered

We present a series of 48 patients with infected total knee replacements managed by the use of articulating cement spacers and short-term parenteral antibiotic therapy in the postoperative period. All patients had microbiological and/or histological confirmation of infection at the first stage of their revision. They all underwent re-implantation and had a mean follow-up of 48.5 months (26 to 85). Infection was successfully eradicated in 42 of the 48 patients (88%). Six had persistent infection which led to recurrence of symptoms and further surgery was successful in eliminating infection in four patients. These rates of success are similar to those of other comparable series. We conclude that protracted courses of intravenous antibiotic treatment may not be necessary in the management of the infected total knee replacement. In addition, we analysed the microbiological, histological and serological results obtained at the time of re-implantation of the definitive prosthesis, but could not identify a single test which alone would accurately predict a successful outcome

Infection of a total hip replacement (THR) requires component removal and thorough local debridement. Usually, long-term antibiotic treatment in conjunction with a two-stage revision is required. This may take several months. One-stage revision using antibiotic-loaded cement has not gained widespread use, although the clinical and economic advantages are obvious. Allograft bone may be impregnated with high levels of antibiotics, and in revision of infected THR, act as a carrier providing a sustained high local concentration. We performed 37 one-stage revision of infected THRs, without the use of cement. There were three hips which required further revision because of recurrent infection, the remaining 34 hips (92%) stayed free from infection and stable at a mean follow-up of 4.4 years (2 to 8). No adverse effects were identified. Incorporation of bone graft was comparable with unimpregnated grafts. Antibiotic-impregnated allograft bone may enable reconstruction of bone stock, insertion of an uncemented implant and control of infection in a single operation in revision THR for infection

The current standard recommendation for antibiotic therapy in the management of chronic osteomyelitis is intravenous treatment for six weeks. We have compared this regime with short-term intravenous therapy followed by oral dosage. A total of 93 patients, with chronic osteomyelitis, underwent single-stage, aggressive surgical debridement and appropriate soft-tissue coverage. Culture-specific intravenous antibiotics were given for five to seven days, followed by oral therapy for six weeks. During surgery, the scar, including the sinus track, was excised en bloc. We used a high-speed, saline-cooled burr to remove necrotic bone, and osseous laser Doppler flowmetry to ensure that the remaining bone was viable. Infected nonunions (Cierny stage-IV osteomyelitis) were stabilised by internal fixation. In 38 patients management of dead space required antibiotic-impregnated polymethylmethacrylate beads, which were exchanged for an autogenous bone graft at six weeks. Free-tissue transfer often facilitated soft-tissue coverage. These 93 patients were compared with 22 consecutive patients treated previously who had the same surgical management, but received culture-specific intravenous antibiotics for six weeks. Of the 93 patients, 80 healed without further intervention. Of the 31 Cierny-IV lesions, 27 healed without another operation, and four fractures required additional bone grafts. No more wound drainage was needed. Treatment was successful in 91% of patients, regardless of the organism involved. There was no difference in outcome in terms of these variables when the series were compared. We conclude that the long-term administration of intravenous antibiotics is not necessary to achieve a high rate of clinical resolution of wound drainage for adult patients with chronic osteomyelitis

The outcome of primary management of acute osteomyelitis in 655 children treated in New Zealand between 1947 and 1976 is examined. Failure occurred in 20 per cent of children, in four-fifths of whom it was manifest by one year, and half of whom experienced one recurrence only. Lower failure rates were associated with use of bactericidal antibiotics, certain favourable sites, and age over 16 years. Surgical intervention was associated with significantly higher failure rates. The place of surgical intervention and the optimal duration of antibiotic treatment can only be determined by prospective clinical trials

Coloured bone cements have been introduced to make the removal of cement debris easier at the time of primary and revision joint replacement. We evaluated the physical, mechanical and pharmacological effects of adding methylene blue to bone cement with or without antibiotics (gentamicin, vancomycin or both). The addition of methylene blue to plain cement significantly decreased its mean setting time (570 seconds (. sd. 4) vs 775 seconds (. sd. 11), p = 0.01), mean compression strength (95.4 MPa (. sd. 3) vs 100.1 MPa (. sd.  6), p = 0.03), and mean bending strength (65.2 MPa (. sd. 5) vs 76.6 MPa (. sd. 4), p < 0.001) as well as its mean elastic modulus (2744 MPa (. sd. 97) vs 3281 MPa (. sd. 110), p < 0.001). The supplementation of the coloured cement with vancomycin and gentamicin decreased its mean bending resistance (55.7 MPa (. sd. 4) vs 65.2 MPa (. sd . 5), p < 0.001).The methylene blue significantly decreased the mean release of gentamicin alone (228.2 µg (. sd. 24) vs 385.5 µg (. sd . 26), p < 0.001) or in combination with vancomycin (498.5 µg (. sd. 70) vs 613 µg (. sd. 25), p = 0.018) from the bone cement. This study demonstrates several theoretical disadvantages of the antibiotic-loaded bone cement coloured with methylene blue

We prepared a composite of D,L-lactic acid oligomer and dideoxykanamycin B for use as a biodegradable antibiotic delivery system with sustained effect. The composite was implanted in the distal portion of the rabbit femur, and the effective concentration of the antibiotic was measured in the cortex, the cancellous bone, and the bone marrow. In all bone tissues around the implant, the concentration of antibiotic exceeded the minimum inhibitory concentration for the common causative organisms of osteomyelitis for six weeks. Most of the implant material had been absorbed and the bone marrow had been repaired to a nearly normal state within nine weeks of implantation. The implant caused no systemic side effects, and it is likely to prove clinically useful as a drug delivery system for treating chronic osteomyelitis

Aims

The burden of revision total hip arthroplasty (rTHA) continues to grow. The surgery is complex and associated with significant costs. Regional rTHA networks have been proposed to improve outcomes and to reduce re-revisions, and therefore costs. The aim of this study was to accurately quantify the cost and reimbursement for a rTHA service, and to assess the financial impact of case complexity at a tertiary referral centre within the NHS.