Although it is possible that knee replacement is less effective than hip replacement in improving quality of life, it is also possible that the SF-36 is less responsive to change following knee replacement. Perhaps restoration of hip function allows patients to perform the activities defined on the SF-36 better than restoration of knee function. March et al noted that the general health of the younger patients undergoing knee replacement declined in the year after surgery. It is not clear to what extent the decline in health status was a contributor to or a consequence of the poorer functional outcomes of surgery in this age group. The effect of comorbidities on long-term outcomes after joint replacement surgery requires further investigation.
Debate continues over the best way to assess the outcomes of joint replacement surgery.
Yet, it appears that the more generic the instrument, the less responsive it is to change following joint replacement surgery. There is no clear correlation between improvements in health status and health perceptions after joint replacement surgery. Disease-specific measures may provide more relevant information to patients and clinicians than global measures. Patients can be told that, after hip replacement, it is likely they will have less pain and be able to better perform activities of daily living such as dressing, sitting, walking or climbing stairs. The patient can then weigh these benefits against the risks and complications of surgery and make an informed decision.