الفهرس 
Anatomy and BiomechanicsOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
Dislocation is one of the most common complications after total hip arthroplasty and also it is one of the most serious and painful complications that need urgent and careful interference.
The etiology of THA instability is often multifactorial. Patient demographics, operative technique and implant design variables have been demonstrated to affect the risk of dislocation.
Dislocation after total hip arthroplasty can be categorized as early or late on the basis of the timing of the onset. Early dislocation usually occurs in the early post- operative period within six months after the arthroplasty and is often successfully treated with nonoperative means. In contrast, late dislocation occurs after five years and generally requires surgical treatment. This classification is useful because it highlights the differences in the etiology of the dislocation in each category, which in turn determines the type of treatment that is selected.
Patient related conditions such as compliance, substance abuse, neuromuscular disorder that affect hip mechanics, and primary reconstruction for hip fracture have been associated with higher dislocation rates than normal. Surgical issues also play a role; These include improper component position, sources of secondary impingement, operative approach, and poor soft tissue tension at the time of implantation.
Dislocation problems can be avoided by preoperatively identifying patients at high risk for dislocation and applying appropriate preventive measures, Recently the advances regarding the prosthetic design include (using of large head size, keeping neck circumference to a minimum, using of elevated rim and constrained liners.), proper intra-operative components positioning, avoiding impingement and Evaluation of stability and soft tissue tension.
Postoperative patient education can help prevent dislocation. It is helpful for both the surgeon and physical therapists to emphasize the importance of hip dislocation precaution before the patient is discharged from the hospital after total hip arthroplasty.