User’s Guide to the Orthopaedic Literature: How to Use an Article About Prognosis

Prognosis studies are investigations examining the possible outcomes of a disease or operative procedure and the probability with which they can be expected to occur. Primary guides for assessing the validity (study methodology) of a prognosis study are: Was there a representative sample of patients? Were the patients sufficiently homogeneous with respect to prognostic risk? If not, did the investigators provide estimates for all clinically relevant subgroups? Secondary guides for assessing the validity (study methodology) of a prognosis study are: Was follow-up sufficiently complete? Were objective and unbiased outcome criteria used? You are an orthopaedic surgeon consulting on the case of a seventy-seven-year-old woman with osteoarthritis in the right hip causing pain and functional impairment who was referred to you by a local family physician. The woman had a left total hip arthroplasty twelve years ago, with a good result. For the present problem, she received a course of conservative therapy including anti-inflammatory medications and physiotherapy. She currently uses a cane to walk and is no longer able to do housework. On examination, she is found to be moderately overweight (67 kg) and 5 ft (152.4 cm) tall. She has a 2-cm limb-length discrepancy and a severely restricted range of motion of the right hip. Examination of anteroposterior radiographs of the pelvis and the right hip reveal advanced osteoarthritis with large osteophytes, subchondral cysts, and decreased joint space. Additional evaluation of the radiograph of the right hip reveals a femoral canal-flare index (the canal width 20 mm proximal to the geometric center of the lesser trochanter divided by the canal width at the isthmus of the femur) of 2.0. Evaluation of a radiograph of the left hip, in which a so-called hybrid hip arthroplasty (fixation of the acetabular component without cement and the femoral component with cement) was done, reveals …