The Journal of Bone and Joint Surgery

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Commentary & Perspective

Commentary & Perspective on
"The Role of Patient Restrictions in Reducing the Prevalence of Early Dislocation Following Total Hip Arthroplasty. A Randomized Prospective Study"
by E. Louis Peak, MD, et al.

Commentary & Perspective by
Daniel J. Berry, MD*,
Mayo Clinic, Rochester, Minnesota

The paper entitled "The Role of Patient Restrictions in Reducing the Prevalence of Early Dislocation Following Total Hip Arthroplasty: A Randomized Prospective Study" provides valuable information with regard to the effect of withholding certain commonly prescribed functional restrictions following total hip arthroplasty on the risk of early postoperative hip dislocation. One group of patients was assigned postoperative functional restrictions that included use of an abduction pillow in the operating room immediately following surgery and pillows to maintain abduction while in bed, use of elevated toilet seats and elevated chairs in the hospital and at home, temporary prohibition from driving or being a passenger in an automobile, and avoidance of sleeping on the side. When these patients were compared with a group of patients who did not have these restrictions, and with the numbers available (approximately 130 patients in each group), the authors could demonstrate no difference in the risk of dislocation between the two groups. Indeed, by elimination of some restrictions, the authors found that patients recovered faster and that the cost of care was less.

A potential methodological criticism of the study is that it is uncertain whether the authors had sufficient power in the study to conclude that there was in fact a significant difference between the two study groups. When a study endpoint (in this case, dislocation) occurs so infrequently, the number of patients required to demonstrate a difference between two groups is very large, and hence this study is potentially at risk for a type-II error with insufficient power to detect differences between the groups. Despite this statistical concern, from the clinical standpoint the findings are important: there were no early dislocations in 130 patients despite the elimination of some of the hip restrictions that are commonly employed following total hip arthroplasty.

However, the reader should understand that the conclusions that can be drawn from this study are limited—by virtue of the study design as well as the patient population—and may not be generalizable to many practices for the following reasons:

1. The group of patients that was called "unrestricted," was not in fact completely unrestricted with respect to appropriate hip dislocation precautions. They were told to limit hip range of motion for the six weeks to less than 90° of flexion and 45° of external and internal rotation and to avoid hip adduction.

2. The study excluded patients at high risk for dislocation, including patients with hyperflexibility, Alzheimer's disease, or Parkinson's disease.

3. All of the procedures were performed through an anterolateral surgical approach with the patient in the supine position. One cannot assume, therefore, that the results of this study apply to patients who undergo operation through a posterior approach or in a lateral position and who require transfer in the operating room to a supine position after surgery.

The authors deserve credit for using sound scientific methodology to explore a clinical practice that is widely used but based on little objective supporting data. The authors make a convincing case that with their practice model and in a selected group of patients, these traditional hip dislocation precautions were costly and of no value; further study will be needed to determine if the authors' findings can be generalized to broader groups of patients and practices.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. The author received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (DePuy). In addition, a commercial entity (DePuy, Zimmer, and Stryker) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.