As hip replacements age, the components will wear and the hip will lose its' initial soft-tissue tension. This combined with a general increase in tissue laxity can lead to episodes of dislocation. The risks of dislocation are greatest during the early post-operative period when the tissues are still healing and later at 5-7 years. Treatment of early dislocation is usually conservative, so long as the components are correctly positioned. However, patients who dislocate after many years tend to continue to do so and often require revision.
In these cases, the cup is usually removed and replaced with an implant that will allow a larger head. Using a large head gives greater stability and long-term function.
The stem is usually changed. This is done so that the head can be changed and the offset (distance from the centre of the head to the attachment of the abductor muscles) increased. Rather then remove the original implant and all the cement (which carries significant risks), it is possible to use mini-stems which can be cemented into the space left by the old implant.
Once this is done, the patient can usually weight-bear fully but should follow standard hip precautions until the tissues have healed and stability restored.