Page 68 - The value of total hip and knee arthroplasties for patients

Chapter 4
Limitations
A limitation of our study concerns the scoring of the HSS questionnaires. Both the HSS development study and studies using the HSS use different scoring systems.1,8 The main issue is that one of the answering options in the HSS hip and knee questionnaire is “not applicable.” Patients may have multiple reasons to fill in “not applicable” like not knowing what to answer, having lower expectations than possible to score in the answering options (eg, expecting to worsen or to not improve at all) or not doing a specific activity. It is unknown which implications this may have for our results.This answering option also makes it difficult to calculate sum scores for both expectations and their fulfillment. Palazzo et al1 considered the “not applicable” answers automatically as being not applicable in the postoperative questionnaire as well.Another limitation is that the present study was performed in only one centre and in 1 country, so that cultural and demographic variability with regard to expectations and their fulfillment are not taken into account in our results, which limits generalizability. Another issue that potentially limits the generalizability is the somewhat selective drop out. Despite the effor t to prevent loss to follow-up (sending reminders and contacting patients by phone) in THA patients 20% and in TKA patients 23% of the patients were lost to follow-up after 1 year. We found some differences in preoperative expectations between complete cases and patients who did not return the postoperative questionnaire and thus were lost to follow- up. Patients with complete follow-up showed higher preoperative expectations, that is, a higher proportion “back to normal” on some items. The differences in expectations may probably be related to differences in baseline characteristics of patients who did and who did not have complete follow-up. In addition, we were not able to relate the fulfillment of expectations to the occurrence of postoperative complications, as these were not recorded in the context of our study.
Finally, 8 specialized hip and knee arthroplasty orthopaedic surgeons performing the surgeries with 2 different surgical approaches (straight lateral in lateral position of the patient, and the anterior approach [anterior supine intermuscular] in supine position of the patient) may potentially have affected the outcomes and therefore fulfillment of expectations.
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