Managing Borderline Dysplasia: It Can Take More Than Just a Periacetabular Osteotomy: Commentary on an article by Jeffrey J. Nepple, MD, et al.: "Outcomes of Periacetabular Osteotomy for Borderline Acetabular Dysplasia".

Abstract

Commentary Nepple et al. report the outcomes of a single experienced surgeon treating patients with borderline hip dysplasia from 2010 to 2020. The article correctly points out that a majority of clinical reports of outcomes of treatment for patients with borderline hip dysplasia used arthroscopy without periacetabular osteotomy (PAO)1. This article represents an important contribution documenting the outcomes of treatment correcting structural causes of instability with or without arthroscopy. A previous series of PAOs, including cases from the senior author, used different criteria (lateral center-edge angle [LCEA] of 15° to 25°) to define mild dysplasia2, and those outcomes are not directly comparable with those in the current article, in which an LCEA of 18° to 25° was used to describe borderline dysplasia. The results in the current article demonstrate clinical success in 148 of 156 hips in patients undergoing primary surgery. The article provides important data on radiographic parameters for correction of acetabular dysplasia. The article does not provide a detailed analysis of preoperative femoral neck morphology or femoral torsion. However, several points regarding this clinical series of patients with borderline hip dysplasia are instructive. The authors point out that “A comprehensive assessment of the hip … is critical to informing an accurate diagnosis. Currently, there remain no clear clinical guidelines to differentiate between fundamental mechanical diagnoses (impingement compared with instability) and definitively guide treatment selection.” In other words, the clinical assessment of the patient presentation plays an important role in discriminating between the underlying pathologic mechanisms of impingement or instability. In the entire cohort of 186 hips in 178 patients, only 21 hips underwent an isolated PAO. The majority of treated hips required addition of a concomitant hip arthroscopy to the PAO as treatment for labral or articular cartilage pathology (130 of 186 hips). Similarly, 120 hips required a femoral osteoplasty to treat impingement at the time of the PAO. These 2 important observations emphasize the importance of clinicians and learners who are interested in treating patients with this type of hip pathology gaining experience in evaluating patients with instability as well as patients with impingement. The ability to differentiate instability from impingement depends in part on clinical exposure to the presentation of these types of hip pathology. Of note, neither the evaluation nor treatment of the young adult hip is addressed in the latest iteration of the Accreditation Council for Graduate Medical Education (ACGME) Orthopaedic Surgery Milestones3. This study does not provide an assessment with a control group with similar labral and intra-articular pathology treated without arthroscopy. Therefore, it is unclear whether hip arthroscopy with labral refixation and chondral interventions as performed in this cohort would be required to achieve similar outcomes. A previous study indicated that not treating femoroacetabular impingement at the time of the PAO was associated with poorer long-term outcomes4. However, the reported data in the current study indicate that hip arthroscopy at the time of the PAO has not adversely impacted results. Nepple et al. also point out the adverse impact that a previous unsuccessful hip arthroscopy has on the outcomes in patients with borderline hip dysplasia. The majority of these previous arthroscopies were not performed by the senior author. It is not clear whether these patients had concomitant impingement with borderline dysplasia and developed instability after arthroscopy, or they had clinical instability that had been misdiagnosed as impingement initially. There are many reports detailing successful treatment of femoroacetabular impingement arthroscopically in the setting of borderline dysplasia1. However, clearly a hip arthroscopy that leaves the patient with symptomatic hip instability has an adverse impact on outcome after structural correction with PAO. Finally, the diversity of treatments required to provide successful outcomes in the cohort of patients studied by Nepple et al. provides some evidence for the need for personalized medicine in the care of young patients with hip pathology. As with all such clinical series, the reported results are a benchmark for all clinicians to aspire toward. The results in this article represent the work of an experienced surgeon selectively managing multiple aspects of hip pathology to optimize outcomes in this defined cohort of patients.