Preoperative Joint Space Width Predicts Patient-Reported Outcomes After Total Hip Arthroplasty in Young Patients.

BACKGROUND

In a new health care economy, there is an emerging need to understand and quantify predictors of total hip arthroplasty (THA) outcomes. We investigated the association between preoperative radiographic disease (as measured quantitatively by joint space width [JSW]) and patient-reported function, activity, pain, and quality of life after THA.

METHODS

We retrospectively analyzed 146 patients (146 hips) 55 years or younger with a diagnosis of osteoarthritis who underwent cementless THA between January 2009 and December 2010. Preoperative pelvic radiographs were measured by 1 author blinded to clinical outcomes to establish JSW, defined as the shortest distance between the femoral head margin and the superolateral weight-bearing portion of the acetabulum. The JSW value was treated as a continuous variable when applied to statistical modeling. The relationship between the JSW and the improvement of clinical outcome was examined via a general linear modeling approach with adjustments for patients' age, body mass index, and sex.

RESULTS

We identified an inverse relationship between preoperative JSW and improvements in functional, activity, pain, and quality of life. We found that, as JSW decreased by 1 mm, the outcome measure improvements were modified Harris Hip Score of 6.3 (p<0.001); SF-12 physical: 2.1 (p=0.027); WOMAC-pain: 4.8 (p=0.01); and UCLA Activity: 0.44 (p=0.02).

CONCLUSIONS

Our results demonstrate that patients with greater preoperative joint space have less predictable improvement in terms of function, pain relief, and activity. These findings suggest that THA in young patients with a JSW less than 1.5 to 2 mm provides more predictable improvements in pain and functional outcomes.