The hypothesis of this study is that the Rim Plate method utilizing interfragmentary screws placed through the plate will result in superior fixation, a lower rate of loss of reduction of the fracture fragment, better anatomic healing of the articular (joint) surface, a decreased rate of early post-traumatic arthritic changes of the joint (cartilage) surface, and improved functional outcomes.

Study type: Interventional Estimated enrollment: 60 Allocation: block randomization. The block randomization method is designed to randomize subjects into groups that result in equal sample sizes. This method is used to ensure a balance in sample size across groups over time.

Interventional model: parallel assignment Description: two different methods of screw and plate fixation of posterior wall acetabulum fractures.

Time perspective: Prospective

Population:

Skeletally mature patients who have presented with an acute traumatic fracture of the posterior wall of acetabulum due to dislocation of the femoral head will be included in this study. All surgeons on the study routinely perform both types of repairs.

Treatment arms and Intervention:

Arm A: Rim plate group - This group will consist of 30 patients where the posterior wall fracture will be operatively stabilized with a pelvic reconstruction plate and interfragmentary screws placed through the plate.

Arm B: Buttress plate group - This group will consist of 30 patients where the posterior wall fracture will be operatively fixed with a buttress plate applied under compression without interfragmentary lag or position screws.

Inclusion Criteria:

1. Skeletally mature males and females, ≥ 18 years old and with age less than 65 years.
2. Fracture of the acetabular posterior wall fracture due to acute traumatic hip dislocation, confirmed with anteroposterior pelvic or hip radiographs, and CT scan
3. Operative fixation of fractures within 14 days of presenting to the emergency room.
4. Patient was ambulatory prior to fracture, with or without walking aids
5. Medically optimized for operative intervention
6. Provision of informed consent by patient or legal guardian.

Exclusion Criteria:

1. Patients not suitable for internal fixation (severe osteoarthritis, rheumatoid arthritis, or pathologic fracture).
2. Pre-existing orthopedic fixation, implant, or prosthesis around the affected acetabulum.
3. Patients with metabolic bone disease including diagnosis of osteoporosis.
4. Patients with bony or soft tissue infections around the acetabulum.
5. Patients unable to provide informed consent.
6. Patients having other fractures of Pelvis or acetabulum other than an isolated posterior acetabular wall fracture.
7. Patients with previous history of acetabular fracture (operative or nonoperative)
8. Patients with previous history of hip pathology such as avascular necrosis, hip dysplasia, Legg-Calve Perthes Disease, or advanced degenerative arthritis.