Complications of the Periacetabular Osteotomy for Treatment of Adolescent Hip Dysplasia

Surgeon Experience/Learning Curve

In a 1999 report by Dr. Ganz examining 508 PAO cases, it was noted that 85% of technical complications occurred within the first 50 cases. Davey and Santore found a nearly six fold decrease in major complication rate between their initial 35 cases (17%) and their subsequent 35 cases (2.9%). Similar observations have since been noted by a number of other authors, suggesting a substantial learning curve associated with the PAO.

Attempts to mitigate and/or accelerate this substantial learning curve are thus critical to overall complication risk reduction. Advanced fellowship training with a surgeon experienced in proper technique is now more feasible than in the past. Additionally, during early “independent” practice, access to an expert mentor for case discussion/progress monitoring and regular operation with an experienced cosurgeon have been suggested as means to achieve this.

Operative Time

Operative time is influenced by a number of factors, including patient pathology, surgeon technical skill/experience, and operating room team cohesiveness. Considering these factors, it is not surprising that increased operative time has been associated with complications with PAO. Factors shown to improve surgical time and patient outcomes include a trained, cohesive operating room team, use of care pathways, and operating with a second, trained attending surgeon.

Patient Selection

Careful patient selection is a critical early step in complication mitigation and overall outcome optimization. Ideal candidates for PAO are patients who are relatively young (≤30 years) with good to excellent hip joint congruency and minimal evidence of osteoarthritis. Older patient age (>40 years), joint incongruency, evidence of osteoarthritis (Tonnis grade ≥2), and increased preoperative disability have been described as significant independent risk factors for poor outcomes. In some cases older patients with healthy cartilage and younger physiologic age, as well as some patients with severe disability at presentation, can still have excellent outcomes.

Obesity has increasingly been recognized as a significant risk factor for perioperative complications and should be factored into decision-making on a patient-specific basis. A large multicenter study noted a nearly seven fold increase in the major complication rate in obese patients (body mass index [BMI] >30) (22.3%) compared to nonobese patients (3.1%). Wound complications requiring reoperation were particularly frequent among obese patients, with 11% requiring reoperation for deep infection and 15% requiring reoperation for superficial infection. Excess adipose tissue may also obscure anatomic landmarks and/or complicate instrument positioning for the osteotomies of the PAO. Though perioperative risk reduction strategies for these patients and their efficacy have yet to be fully explored, it remains important to consider BMI in patient selection and preoperative planning. Weight loss prior to surgery may be beneficial for patients in this higher-risk group to minimize their complication risk.

The most common indication and underlying diagnosis for PAO is idiopathic hip dysplasia. Although some debate exists on the etiology of that dysplasia (missed/residual childhood dysplasia vs. adolescent-onset dysplasia), this is primarily referred to as developmental dysplasia of the hip (DDH). Many other conditions do have associated hip instability and hip undercoverage, though, including Down syndrome, Elhers–Danlos, Charcot–Marie–Tooth, post-Perthes deformities, and cerebral palsy. While these patients do have significant improvement with PAO, there is a higher risk of complications as compared to patients with an underlying DDH diagnosis. Patients with these conditions should be counseled appropriately.

Surgical Planning and Treatment Selection

Prior pelvic reconstructive surgery is not uncommon in this population and may be associated with increased complication risk. The authors of one study, for instance, noted a higher rate of nerve injuries in a cohort with prior reconstructive surgery compared to a cohort undergoing primary surgery, which they attributed to greater degrees of deformity correction in this group and potential retraction of neurovascular structures, as well as increased susceptibility to stretch injuries and retraction secondary to scar tissue and nerve adhesions. Clinical improvement following PAO in these patients may also be more modest relative to patients undergoing primary surgery. This highlights several challenging aspects to PAO in patients with prior pelvic surgery.

Adjunct procedures performed concurrently with the PAO, including hip arthroscopy and open femoral osteochondroplasty, have increasingly been utilized to address associated pathologies of the hip, achieve comprehensive correction of deformity in a single surgical setting, and minimize risk of persistent and/or recurrent symptoms. Frequently associated pathologies and their respective treatments are summarized in Table 28.2 . Complication risk with combination surgeries appear to be no higher than the risks posed by these treatments performed as isolated procedures.