Osteomyelitis: clinical update for practical guidelines

Bone infections represent a diagnostic or therapeutic challenge for the infectivologist, orthopaedic surgeon, radiologist and nuclear medicine physician. Staphylococcus aureus is the major bacterium responsible for bone infections although Mycobacterium tuberculosis is emerging as an infectious agent in Italy because of immigration from Africa and Asia. Osteomyelitis requires long and expensive antibiotic treatment, including rifampicin administered parenterally for several weeks and the use of antimicrobial-impregnated cement in prosthesis substitution. Sometimes it is necessary to carry out surgical debridement of a necrotic bone or the consolidation of compromised bones and joint prosthesis implants. Radiographs and bone cultures are mainstays for the diagnosis of bone infections but are often useless in the lengthy management of these patients. Diagnosis of skeletal infections still includes conventional radiography but magnetic resonance imaging is essential in haematogenous and spinal infections. Bone scans are still useful in acute osteomyelitis whereas scintigraphy using labelled white blood cells is preferred in infections of peripheral bone segments or joint prosthesis. In the axial skeleton a combination of an agent for detecting inflammation ((67)Ga citrate) and a metabolic agent ((99m)Tc-methylene diphosphonate) enables an infection and an area of increased metabolic activity to be distinguished. [(18)F]Fluorodeoxyglucose positron emission tomography, where available, has a significant impact in the study of infections using radionuclides: high-resolution tomographic images represent an effective alternative to gallium in the assessment of inflammation of spine lesions but a comparison with morphological examinations (computed tomography or magnetic resonance imaging) is essential.

The in vitro elution characteristics of vancomycin combined with imipenem-cilastatin in acrylic bone-cements: a pharmacokinetic study

The aim of this in vitro study was to compare the elution characteristics of vancomycin alone and in combination with imipenem-cilastatin from 3 acrylic bone-cements (CMW1 [DePuy International, Blackpool, UK], Palacos R [Schering-Plough, Wehrheim, Germany], and Simplex P [Howmedica International, London, UK]). Six groups of 3 antibiotic-loaded cement disks were prepared, incorporating 2 g of vancomycin (3 groups) and 2 g of vancomycin plus 2 g of imipenem-cilastatin (3 groups). The disks were placed in saline baths for 5 weeks, with the baths being sampled periodically and the elution rates calculated. The total amount of vancomycin released by the cements treated with vancomycin alone was 7.98 mg for CMW1, 7.74 mg for Palacos R, and 6.76 mg for Simplex P; with the addition of imipenem-cilastatin, the total amount of vancomycin released by the 3 cements increased by 30.58%, 50.52%, and 50.15%. CMW1 had better elution characteristics than the other cements when treated with vancomycin alone; the elution of Palacos R and Simplex P was better than that of CMW1 when vancomycin was combined with imipenem-cilastatin.

Mucoraceae infections of antibiotic-loaded cement spacers in the treatment of bacterial infections caused by knee arthroplasty

Two clinical cases of mycotic infections secondary to knee spacers medicated with antibiotics against bacterial infections are presented. Care must be taken between the first and second stage (when the spacer is in place), and attention must be paid to the management of the surgical wound to avoid secondary contamination.

Pure dislocation of the ankle: three case reports and literature review

Ankle dislocation without fracture is an extremely rare injury. The results of treatment are reported for three patients who had a posteromedial open dislocation, a lateral open dislocation, and a posterior closed dislocation of the ankle. Management consisted of immediate reduction, debridement and capsular suture in the open dislocations, and immobilization with a short leg cast in all patients. At followup no patient had tibiotalar joint instability; a 10 degrees to 15 degrees loss in the range of dorsiflexion was observed in two patients. One patient reported paresthesia in the area of the superficial peroneal nerve. The three patients achieved good long-term functional and radiographic results. Predisposing factors that contribute to the pathogenesis of this lesion are internal malleolus hypoplasia, ligamentous laxity, weakness of the peroneal muscles, and previous ankle sprains. Among the three patients, medial malleolus hypoplasia was present in one patient and previous sprains were seen in the clinical history of another patient.

Biomechanical behaviour at the distal third of the femur: possible use of a medial metaphyseal plate

The incidence of fractures in the distal femur is becoming more frequent and they are often associated to complex lesions with potential complications. Operative treatment is mandatory for elderly people and several methods of internal fixation with appropriate implants have been developed, generally approaching the lateral aspect of the femur. An alternative antero-medial access was proposed several years ago but the biomechanical aspects of its application must be debated. The aim of the present study is to establish if adverse biomechanical effects should be expected when the plate is affixed at the medial side of the femur metaphysis, by analysing the strain pattern of a human cadaver femur submitted to loads simulated in different experimental conditions. Application of load resulted, as expected, in tension in the lateral aspect and compression in the medial aspect of the femur diaphysis but it turned more and more toward the anterior aspect and the compression turned toward the posterior aspect when the levels measured changed from proximal to distal. The plate was next to the neutral axis and produced a moderate stress protection effect (approx. 70 per cent). No biomechanical disadvantages have been observed as a result of the plate being apposed at the medial aspect instead of the conventional lateral aspect of the distal femur.

Quantitative scintigraphic evaluation of total knee arthroplasties: a feasibility study

For the development and validation of a quantitative approach to the analysis of bone scans after total knee arthroplasty, 39 consecutive patients with 40 prostheses (6 males, 33 females; mean age, 70 years) were scheduled for clinical, radiographic, and scintigraphic examination ranging from 9 to 90 months after surgery. Twenty-seven total knee arthroplasties were considered to be asymptomatic and 13 symptomatic according to the clinical and radiographic findings. Significant differences were found for 99mTc-methylene diphosphonate uptake for femur and tibia and between symptomatic and asymptomatic patients. A reference range was determined for radionuclide uptake in the periprosthetic bone of the 27 asymptomatic total knee arthroplasties; this range was then used to identify loose total knee arthroplasties among the 13 symptomatic knees. With a clinical and radiographic followup performed 1 year after scintigraphy as a standard of comparison, a sensitivity of 88% (7/8) and a specificity of 100% (5/5) was demonstrated. These preliminary results suggest the feasibility of a quantitative approach to the scintigraphic evaluation of total knee arthroplasties after the first postsurgical year.

Evaluation of reimplant total hip prostheses and resection arthroplasty

Results of reimplanted total hip prostheses and resection arthroplasty were compared. Using the Iowa hip rating scale, the reimplanted prostheses population was rated higher for function, gait, and absence of deformity, however, the resection arthroplasty population rated better in freedom from pain. Radiographic findings in the reimplanted prostheses population included radiolucent lines around the cement, loosening, and cortex bone stock loss. These findings cause concern for the future of these implants. Repair and remodeling of the bone lesions were observed in resection arthroplasties. It was concluded that if healing of infection is achieved or if resection is performed for mechanical failure, the results may be considered permanent.