Treatment algorithm for symptomatic borderline dysplasia Conservative treatment, arthroscopy, or osteotomy?

Background The algorithm for treatment of borderline dysplasia is controversial. Although hip arthroscopy for the treatment of symptomatic consequential damage to the labrum and cartilage is undisputed, the treatment of soft tissue with capsuloplasty is congruent with multidimensional axis corrections on the pelvis. Objective The aim of this work is to present radiological parameters for the definition of borderline dysplasia, the MRI-morphological and intraoperative characteristic consequential damage to the labrum, LCF and cartilage as well as an overview of bony and soft tissue parameters of instability in borderline dysplasia. Material and methods The studies published in the literature up to 2021 on the diagnosis and treatment were systematically analyzed. Results In order to diagnose borderline dysplasia, in addition to the lateral center-edge angle, further radiological parameters are necessary in order to estimate the anterior and posterior acetabular roof. Borderline dysplasia-specific pathologies of cartilage, labrum and the ligament of the head of the femur, which are indications of joint instability, must be included in the therapeutic considerations. The bony stability of the joint can be assessed radiologically by using the femoro-epiphyseal acetabular roof index. Torsional pathologies of the proximal femur must be clarified with rotation magnetic resonance imaging sequences. The stability of the capsule, ligamentous apparatus and musculature should be analyzed clinically and with the pull test. Conclusion In the treatment of borderline dysplasia the consequential damage can be treated by hip arthroscopy if the hip joints are stable. Unstable hip joints should only be treated with a multidimensional axis correction and the consequential damage can be arthroscopically addressed. For optimal results it is imperative to use a patient-specific approach to decision making that includes a comprehensive patient and imaging assessment.