Background: International registries with large, heterogeneous
patient populations provide excellent research opportunities for studying
factors that influence treatment outcomes after total hip arthroplasty. In the
present study, we used a European multinational database to investigate
whether there is an association between three functional variables
(preoperative pain, mobility, and motion) and functional outcome.
Methods: We performed a retrospective cohort study on preoperative
and follow-up clinical data that were prospectively entered into the
International Documentation and Evaluation System European hip registry
between 1967 and 2002. The inclusion criteria for this study were an age of
more than twenty years, an underlying diagnosis of osteoarthritis, and a
Charnley class-A functional designation at the time of surgery. A total of
12,925 patients (13,766 total hip arthroplasties) who met these criteria were
entered into the analysis. Three functional variables (pain, mobility, and
motion) that were assessed preoperatively were evaluated postoperatively at
various follow-up examinations for a maximum of ten years.
Results: Six thousand four hundred and one patients could walk
longer than ten minutes preoperatively; of these, 57.1% had a walking capacity
of more than sixty minutes at the time of the most recent follow-up. In
comparison, 6896 patients had a preoperative walking capacity of less than ten
minutes and only 38.9% of these patients could walk more than sixty minutes at
the time of the most recent follow-up. The difference was significant (p <
0.01). Similarly, 10,375 patients had a preoperative hip flexion range of
>70°; of these, 74.7% had a flexion range of >90° at the time of
the most recent follow-up. In comparison, 2793 patients had a preoperative hip
flexion range of <70° and only 62.6% of these patients had a flexion
range of >90° at the time of the most recent follow-up. The difference
was also significant (p < 0.01). Lasting, complete, or almost complete pain
relief was achieved by >80% of the patients following total hip
arthroplasty regardless of their preoperative categorization of pain.
Conclusions: Patients with poor preoperative walking capacity and
hip flexion are less likely to achieve an optimal outcome with regard to
walking and motion. In contrast, there is no correlation between the
preoperative pain level and pain alleviation, which is generally good and
long-lasting after total hip arthroplasty.
Level of Evidence: Prognostic Level II. See Instructions
to Authors for a complete description of levels of evidence.