Editorial Commentary: Most Patients With Borderline Hip Dysplasia Do Well After Hip Arthroscopy: Could Instability Be the Problem for Those Who Do Poorly?

Borderline hip dysplasia (BHD) is often defined based on the lateral center edge angle. While patients with frank hip dysplasia often require bony realignment with periacetabular osteotomy and/or derotational femoral osteotomy, patients with BHD represent an "in-between" group of patients. While many, perhaps even most, patients with BHD will have successful outcomes after hip arthroscopy alone, some will be unresponsive to an arthroscopic-only approach and require the same surgical treatments as those with frank dysplasia. A variety of radiographic and arthroscopic parameters can be used to assess the degree of instability in patients with BHD. It may be that patients with "borderline" hip dysplasia combined with hip instability are more likely to fail an arthroscopic-only approach but to date we still do not have a great algorithm for determining which patients with BHD should undergo bony treatment with periacetabular osteotomy. It is important for future studies to continue to seek out characteristics of BHD patients that predict failure of an arthroscopic-only approach. This will not only allow for optimal initial surgical treatment in "at-risk" patients with BHD but will also improve success rates in BHD patients selected for hip arthroscopy as initial surgical treatment.