What is the role of bone scintigraphy in the diagnosis of infected joint prostheses?
OBJECTIVE
To analyse the role played by bone scintigraphy in the diagnosis of infected joint prostheses.


METHODS
The study included 77 patients, aged 32-77 years, in whom infection of a joint prosthesis (48 hip, 29 knee) was suspected. In all patients the following examinations were performed consecutively: a two-phase Tc methylene diphosphonate (Tc-MDP) bone scan, a Tc hexamethylproplyene amine oxime (Tc-HMPAO) labelled white blood cell (WBC) scan, and a Tc microcolloid bone marrow (BM) scan. The minimum interval between examinations was 48 h. The diagnoses were based on data obtained from bacteriological cultures.


RESULTS
The bone scan was positive in all patients and 28 of them had an infection (sensitivity 100%, specificity 0%). The WBC scan was positive in 61 patients but only 27 had an infection. The WBC scan was negative in 16 patients, and the possibility of infection was discarded in 15 of these cases (sensitivity 96%, specificity 30%). The results of the bone marrow scan were not compatible with those of the WBC scan (suggestive of infection) in 27 patients: 26 of them had prosthesis infection. The results of both examinations were compatible in the other 34 patients and the possibility of infection was discarded in 33 of these patients (sensitivity 92.8%, specificity 98%). The addition of a BM scan to a WBC scan decreased the sensitivity from 96% to 92.8% but increased specificity from 30% to 98%. The addition of a bone scan to this dual combination did not alter the results.


CONCLUSIONS
When infection of a prosthesis is suspected the diagnostic procedure should start with a WBC scan followed, if positive, by a BM scan. This procedure reduces the cost, the time required for a diagnosis, and the dose of radiation received by the patient.
Segura
Ana Benítez
AB
S. Medicina Nuclear, CSUB, Hospital de Bellvitge, c/Feixa Llarga s/n, 08970 L'Hospitalet de Llobregat, Barcelona, Spain.
Muñoz
Antonio
A
Brulles
Yvonne Ricart
YR
Hernandez Hermoso
José Antonio
JA
Díaz
Maria Carmen
MC
Bajen Lazaro
Maria Teresa
MT
Martín-Comín
Josep
J
D000328:Adult; D000368:Aged; D001842:Bone and Bones / Q000000981:diagnostic imaging; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects*; D007720:Knee Prosthesis / Q000009:adverse effects; D007962:Leukocytes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010000:Osteitis / Q000000981:diagnostic imaging* / Q000209:etiology; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging* / Q000209:etiology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017556:Technetium Compounds; D019690:Technetium Tc 99m Exametazime; D013669:Technetium Tc 99m Medronate; D017971:Tin Compounds
D019275:Radiopharmaceuticals; D017556:Technetium Compounds; D017971:Tin Compounds; C033493:technetium Tc 99m tin colloid; D019690:Technetium Tc 99m Exametazime; D013669:Technetium Tc 99m Medronate