The study will assess the outcomes of patients treated with concomitant hip arthroscopy at the time of periacetabular osteotomy (PAO) for patients with hip dysplasia compared with patients treated with PAO alone.

There are currently no absolute indications for intraarticular assessment at the time of periacetabular osteotomy (PAO). Based on investigators' review of the literature and experience, patients who may benefit from intraarticular assessment are those with radiographic or MRI evidence of damage where an intraarticular inspection may help in determining whether a PAO is a reasonable procedure, those with mechanical symptoms likely related to labral pathology, round ligament or cartilage problems and those with hip dysplasia and cam deformities with limited range of motion that may benefit from femoral head neck junction osteochondroplasty. However, despite these relative indications today there is no clear evidence to suggest that these patients will do better than those that do not have intraarticular work done. Hence, the objective of this project is to determine whether intraarticular work at the time of PAO surgery leads to improved pain and function when compared to patients that do not undergo intraarticular work at the time of PAO.

Inclusion Criteria:

• Diagnosis of hip dysplasia (DDH) electing periacetabular osteotomy (PAO) for treatment
• Skeletally mature
• Age 15 - 55
• Tonnis Grade 0 or 1 osteoarthritis (minimal or no arthritis)
• Ability to receive a standard of care preoperative (magnetic resonance imaging) MRI arthrogram of the hip

Exclusion Criteria:

• Pregnant women
• Previous surgery about the hip
• Patients receiving PAO for acetabular retroversion in the absence of DDH
• Previous hip arthroscopy to address intra-articular pathology

Only study personnel authorized by the investigator will collect data/enroll subjects. Data will be stored in electronic files and/or a cabinet, with access to study personnel as authorized by the investigator. The investigator will review the data on a regular basis (at least annually) to verify the validity of the data.

Patients will be randomized in a 1:1 fashion. The first arm will be the "PAO alone" group who will receive a standard periacetabular osteotomy (PAO) on the day of surgery. The second arm will be the "PAO + HA" group who will receive a PAO and hip arthroscopy (HA) on the day of surgery. Any pathology if present that can be corrected with the arthroscope (cartilage and labral abnormalities) will be addressed. This will be followed by a standard PAO. Patients from both groups will have dressings placed in the location of hip arthroscopy portals to remain blinded to the treatment arm during the perioperative period. Only patients in the PAO + HA group will have incisions and sutures under these dressings. The dressings will come off for all patients after 2 weeks, which is standard of care. All other study team members will remain unblinded.