What are the outcomes of reverse periacetabular osteotomy (PAO) for retroverted acetabula in females in their 20s?

Reverse PAO for Retroverted Acetabula in Females in Their 20s

Reverse periacetabular osteotomy (PAO) is an effective treatment for symptomatic acetabular retroversion in young females, producing clinically significant improvements in pain and hip function at 2-year follow-up, with superior 10-year survivorship compared to acetabular rim trimming. 1, 2, 3, 4

Clinical Outcomes

Pain and Function Improvements

• Patients experience significant pain reduction at 2 years post-operatively, with mean improvements in VAS pain scores and WOMAC pain scores decreasing by 7 points (95% CI -9 to -5) 3

• Hip function improves substantially, with WOMAC function scores improving by 18 points (95% CI -24 to -12) and modified Harris Hip Score increasing by 20 points (95% CI 13 to 27) at minimum 2-year follow-up 2

• Between 51-73% of patients achieve minimal clinically important difference in various outcome measures, indicating that the majority experience meaningful clinical benefit 3

• Hip range of motion improves, particularly internal rotation which increases by 8° (95% CI 2° to 14°) postoperatively 2

Radiographic Correction

• Acetabular coverage is successfully reduced, with lateral center-edge angle decreasing by 8° (95% CI -12° to -5°), anterior center-edge angle decreasing by 12° (95% CI -15° to -9°), and Tönnis angle improving by 9° (95% CI 6° to 13°) 2

Survivorship Data

Superior Long-term Outcomes

• Reverse PAO demonstrates 79% survivorship at 10 years (95% CI 68%-90%), which is substantially superior to acetabular rim trimming at 23% (95% CI 6%-40%) 4

• Five-year survivorship is comparable between treatments at 86% for both reverse PAO and rim trimming, but the rim trimming survivorship curve drops significantly starting at year 6 4

• Only 11% of patients (4 of 37 hips) experience adverse outcomes at final follow-up, with 2 patients requiring conversion to THA and 2 having persistent pain (WOMAC pain score >10) 2

Patient Satisfaction and Quality of Life

• Quality of life improves to levels similar to the general Danish population at 2-year follow-up 3

• The majority of patients report satisfaction with surgical results at 2-year follow-up 3

Factors Associated with Outcomes

Negative Predictors

• Female sex is associated with worse outcomes in patients undergoing reverse PAO for retroversion 1

• Obesity negatively impacts surgical results 1

• Hypermobility is a negative predictor, and females with signs of hypermobility should be counseled about likely guarded improvement 1

• Severely decreased femoral anteversion (<0°) predicts worse outcomes, and these patients may require additional procedures to address femoral version abnormalities 1

• Postoperative severity of radiographic arthritis correlates with worse function, with each additional Tönnis grade associated with 12-point increase in WOMAC function score (95% CI 2 to 22) and 12-point decrease in modified Harris Hip Score (95% CI -20 to -4) 2

• Positive postoperative anterior impingement test is associated with 23-point decrease in modified Harris Hip Score (95% CI -34 to -12) 2

Positive Associations

• Decreased pain is significantly associated with improved hip function, establishing a clear relationship between pain relief and functional gains 3

Complications

• Surgery-related complications occur in 19% of cases (7 of 37 hips), though specific complication types were not detailed in the available evidence 2

• No identifiable factors were associated with complications in the available studies, though this may reflect limited sample sizes 2

Comparison to Dysplasia Treatment

• Reverse PAO for retroversion produces slightly lower improvement in patient-reported outcomes compared to PAO for dysplasia, with mean NAHS improvement of 18.3 points (SD 22.1) for retroverted hips versus 25.2 points (SD 15.2) for dysplastic hips, though this difference was not statistically significant 1

• Postoperative NAHS scores are lower in retroverted hips (76.7, SD 17.9) compared to dysplastic hips (83.0, SD 16.9) at mean 3.5-year follow-up 1

• Reoperation rates and complications are similar between retroversion and dysplasia groups 1

Critical Considerations for Young Females

Preoperative Assessment Requirements

• Femoral version must be routinely assessed preoperatively, as extremely low femoral anteversion (<0°) may necessitate additional procedures to address this abnormality 1

• Screening for hypermobility is essential, particularly in young females, as this predicts worse outcomes 1

• Body mass index should be optimized preoperatively given obesity's negative impact on results 1

Technical Complexity

• Reverse PAO is a technically complex procedure requiring substantial training and preparation by surgeons already familiar with standard PAO 2

• The procedure must be carefully presented to patients with thorough discussion of potential risks and benefits 2

Common Pitfalls

• Failing to assess femoral version preoperatively can lead to suboptimal outcomes, particularly when severe femoral retroversion coexists with acetabular retroversion 1

• Not counseling hypermobile young females appropriately about expected outcomes may lead to unrealistic expectations 1

• Choosing rim trimming over reverse PAO for substantial acetabular retroversion results in significantly worse 10-year survivorship, likely due to reduction of an already smaller lunate surface 4

• Ignoring the association between postoperative impingement signs and poor outcomes may miss opportunities for additional intervention 2