The authors concluded that positron emission tomography could be a valid option if research was able to find an uptake pattern specific for septic and aseptic loosening. These conclusions did not appear to relate directly to the results presented. The review suffered from limitations, including failure to assess study quality, inappropriate analysis and lack of details on the review process.

To determine the value of positron emission tomography (PET) in distinguishing between septic and aseptic loosening in hip prosthesis.

PubMed, EMBASE, SCOPUS, CINAHL, AMED, DARE, TRIP, Cochrane Central Register of Controlled Trials, HTA database and Cochrane Musculoskeletal Injuries Group's Specialised Register were searched to June 2007. Search terms were reported and did not include a diagnostic filter.

Prospective studies that evaluated FDG-PET to detect loosening of hip prostheses in patients suspected of redundancy who had undergone surgery at least one year earlier and that involved follow-up of at least six months were eligible for inclusion. The imaging had to be evaluated by at least one expert trained in nuclear medicine blinded to the clinical situation.

Included studies enrolled patients one to two years following surgery. The reference standard in the included studies was microbiological and histological tests following revision surgery or after follow-up of up of six to 12 months.

The authors stated neither how the papers were selected for the review nor how many reviewers performed the selection.

The authors did not state that they assessed validity

The authors stated neither how the data were extracted for the review nor how many reviewers performed the data extraction. Data were presented on 2x2 tables of test performance and sensitivity, specificity and accuracy.

The weighted average of sensitivity was calculated. Heterogeneity was not formally assessed.

Five studies were included in the review (209 patients, 223 hip prostheses and 36 knee prostheses).

Sensitivity for the assessment of hip prostheses ranged from 33% to 94% and was above 88% in all but one study. Specificity ranged from 78% to 97%. After exclusion of one study with very low sensitivity, pooled sensitivity was 92% and pooled specificity was 87%.

FDG-PET could be a valid option if research was able to find an uptake pattern specific for septic and aseptic loosening.

The review addressed a focused question. Inclusion criteria were broad and poorly defined. The literature search was extensive, but did not include specific attempts to locate unpublished studies, so there was a possibility of publication bias. Details on the review process were not reported, so it was not possible to determine whether appropriate steps were taken to minimise bias and errors. Study quality was not assessed, so the reliability of the primary studies was unclear. Heterogeneity was not formally assessed and methods of pooling involved calculating a weighted average, rather than using more sophisticated methods of meta-analysis. One study reported much lower sensitivity than the other studies. Although sensitivity analysis was conducted by removing this study from the pooled analysis, the reasons for lower sensitivity in this study were not investigated. The authors' conclusions did not appear to relate directly to the results presented and should be interpreted with extreme caution.

Practice: The authors did not state any implications for practice.

Research: The authors stated that research was required to find an FDG-PET uptake pattern specific for septic and aseptic loosening. New studies were needed to identify normal and pathological patterns in knee prostheses.

Not stated

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.