Fri., 10/5/12 Pelvis & Acetabulum, PAPER #67, 4:20 pm OTA-2012
Predicting the Need for Arthroplasty after Acetabular Open Reduction and Internal Fixation
Rebecca Clinton, MD1; Theodore T. Manson, MD1; Renan Castillo, PhD2;
Robert S. Sterling, MD1;
1R Adams Cowley Shock Trauma Center, Department of Orthopaedics,
University of Maryland Medical School, Baltimore, Maryland, USA;
2Center for Injury Research & Policy, Johns Hopkins Bloomberg School of Public Health,
Baltimore, Maryland, USA
Purpose: Open reduction and internal fixation (ORIF) of acetabular fracture minimizes the risk of posttraumatic arthrosis and maximizes joint preservation. However, a certain percentage of patients who undergo ORIF require later conversion to total hip arthroplasty (THA) for arthritis. We hypothesize that there is a threshold amount of joint-space narrowing predictive of subsequent THA in patients who are status postacetabular ORIF.
Methods: This study was performed at a Level I statewide referral center for acetabular fracture patients between 2002 and 2009. Our study group consisted of 31 acetabular fracture initially treated with ORIF that subsequently underwent THA within 3 years. We compared these patients to a control group of 31 age- and fracture pattern–matched pairs who were followed for at least 1 year after acetabular ORIF and have not required THA. Radiographs from the time of ORIF, 3 months, and 6 months were reviewed and joint space measured as a percentage of the unaffected side. All patients were treated by fellowship-trained orthopaedic trauma surgeons and in general began full weight bearing at 3 months after fracture fixation. Predictive cutoff values were evaluated using standard criteria: sensitivity, specificity, and positive predictive values (the probability that given a positive prediction of THA, the patient ends up having a THA).
Results: The average age of the patients in the control and study groups was 50 years. The average time from acetabular fixation to total hip arthroplasty was 406 days. The predominant fracture pattern in both groups was transverse, posterior wall. At the 3-month visit after ORIF of an acetabular fracture, if a patient had more than 20% narrowing of the joint space, this represented more than a 90% positive predictive value of future THA (95% confidence interval [CI]: 0.69, 0.98). At the 6-month visit, the correlation between joint-space narrowing and future THA was not as strong; however, if a patient had over 30% narrowing, there was an 80% positive predictive value of needing a later THA (95% CI: 0.51, 0.97).
Conclusion: Joint-space narrowing at the 3-month visit after ORIF is highly correlated with subsequent THA. Six-month values are less predictive of need for later THA. This is particularly useful for patient counseling regarding prognosis at the 3-month visit after acetabular fracture fixation.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.