Periacetabular Osteotomy With Versus Without Adjunctive Hip Arthroscopy

Inclusion Criteria: * Ages 18 to 50 * Moderate or severe dysplasia by radiographic parameters * Physical examination and/or MR arthrography consistent with intra-articular pathology (equivocal or even negative MR arthrogram for labral tear, chondral flap, ligamentum teres tear, or osteochondral defect, is not grounds for exclusion, since broadly spaced "cuts" of MR imaging may miss small tears) * English- or Spanish-speaking * signed written informed consent for surgery and for research prior to surgery Exclusion Criteria: * Tönnis grade II or III arthritis at baseline * MR cartilage imaging indicating severe arthritis * Prior surgery on the same hip * Contralateral lower limb pathology that threatens validity of outcomes measures directed at the operative hip * History of thromboembolic disease in the lower extremity, pulmonary embolus, or pre-existing thrombophilic blood disorder * Inability to participate in or comply with appropriate rehabilitation protocols * Inability to comprehend and follow instructions, or mental incapacity barring consent * Pregnant women * Lost to follow-up before one year, unless total hip replacement performed before one year (then included for survival analysis)