The Journal of bone and joint surgery. American volume
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J Bone Joint Surg Am · Nov 2001
Type-II error rates (beta errors) of randomized trials in orthopaedic trauma.
Although an investigator may limit bias through randomization, concealment of patient allocation, and blinding, the results of randomized trials may be less convincing when the sample size is not sufficiently large to reveal a true difference between treatment groups. When the sample size is small, randomized trials are subject to beta errors (type-II errors)--that is, the probability of concluding that no difference between treatment groups exists when, in fact, there is a difference. The purpose of this study of randomized trials involving fracture care published between 1968 and 1999 was twofold: (1) to evaluate type-II error rates and study power (1 - beta) for the primary outcomes and (2) to identify whether investigators clearly identified the primary and secondary outcomes. ⋯ Mean type-II error rates in the orthopaedic trauma trials that we analyzed exceeded accepted standards. Investigators can reduce type-II error rates by performing power and sample-size calculations prior to conducting a trial.
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J Bone Joint Surg Am · Nov 2001
Percutaneous pinning of the proximal part of the humerus. An anatomic study.
Closed reduction and percutaneous pinning of unstable proximal humeral fractures is a well-described technique with some theoretical advantages over open techniques. To our knowledge, the risk of injury to neurovascular structures from percutaneous pinning of the proximal part of the humerus has not been studied. We sought to quantify this risk using a cadaveric model. ⋯ The technique used in this study may be associated with a risk of injury to important anatomic structures about the shoulder. Lateral pins should be distal enough to avoid injury to the anterior branch of the axillary nerve, and multiple fluoroscopic views should be obtained to avoid penetration of the humeral head cartilage. There may be a risk of injury to the cephalic vein, the biceps tendon, and the musculocutaneous nerve with use of anterior pins, and these pins should be employed with caution. Greater tuberosity pins should be placed with the arm in external rotation, should be aimed for a point 20 mm from the inferior aspect of the humeral head, and should not overpenetrate the cortex.