A range that is likely to include the given value. Usually presented as a percent (%). For example, a value with 95% confidence interval implies that when a measurement is made 100 times, it will fall within the given range 95% of the time.

A blood clot occurring in a leg vein and verified with Doppler ultrasound or venography. Proximal deep vein thrombosis was defined as blood clot occurring in either popliteal, femoral, or any deep veins of the pelvis. Distal vein thrombosis was defined as blood clot occurring distal to the popliteal vein in the calf veins of the leg. When both bilateral and unilateral clots data were available, unilateral clots data was used for the analysis.

A statistical method based on the assumption that the effects observed in different studies (in a meta-analysis) are truly different.

A method of identifying and measuring publication bias.

The surgical procedure to treat hip fracture.

Measure of degree of variation due to statistical heterogeneity. Usually reported as a percent ranging from 0 to100.

Total hip arthroplasty, total knee arthroplasty, hip fracture surgery.

The process of extracting and pooling data from several studies investigating a similar topic to synthesize a final outcome.

Knee arthroscopy, surgical repair of a lower extremity injury distal to the hip (open reduction internal fixation of the femur, tibia, ankle or foot, intermedullary fixation, ankle fusion, osteotomy of the tibia or femur, open ligament reconstruction of the knee or ankle, and tendon repair) or elective spine surgery (anterior or posterior spinal fusion +/- decompression, laminectomy, or diskectomy all of the lumbar region).

An odds ratio is the ratio of an event occurring in an exposed group to an event occurring in the nonexposed group in a given population. A ratio of one indicates no difference in the odds between the two groups. Peto's odds ratios are used to compare two groups when the number of events is rare.

The possibility that published studies may not represent all the studies that have been conducted, and therefore, create bias by being left out of a meta-analysis.

A blood clot in the vasculature of the lung. In order to have a pulmonary embolism in our review, it needed to be verified with spiral computed tomography angiography or ventilation/perfusion scan with either Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) criteria or high clinical suspicion based on symptoms for pulmonary embolism.

The ratio of an event occurring in an exposed group to an event occurring in a nonexposed group in a given population. A ratio of one indicates no difference in the risk between the two groups.

A “what if” analysis that helps determine the robustness of a study. Helps determine the degree of importance of each variable for a given outcome.

A measure of the variability of a dataset. For a simple dataset with numbers, can be calculated using the following formula: σ = ((∑(x-x_m))²/N)^0.5 where σ is standard deviation, x_m is the average, ∑(x-x_m) is the sum of x_m subtracted from each individual number x, N is the total number of values.

Variability in the observed effects among studies in a meta-analysis.

The surgical replacement of the hip.

The surgical replacement of the knee.

The occurrence of either a deep venous thrombosis or pulmonary embolism.