The purpose of this study is to determine whether patients with operatively treated acetabular fractures benefit from early weight-bearing as tolerated. The study compares two groups ( n = 25 each), which are randomised into either weight-bearing as tolerated or touch-down weight-bearing for 6-8 weeks postoperatively.

Both study groups are stratified according to

• Type of fracture (anterior approach vs anterior + additional posterior approach)
• Dislocated dome vs non-dislocated/ non existing separate dome fragment

Patients, who are eligible to participate in the trial but choose not to participate in randomisation are asked to enrol in a prospective cohort follow-up cohort. This is to examine a potential participation bias in the RCT groups. These patients will not be counted into the target amount of 50 RCT patients.

For the past 20 years, the established treatment of dislocated acetabular fractures has been surgical reduction and stable osteosynthesis. Good long-term results have been reported in these patients. At present, the mobilisation of these patients after surgery is generally restricted for several weeks ranging from 6-12 weeks touch-down- or non-weight-bearing with no uniform protocol. However there is no scientific evidence for limiting post operative weight-bearing. Accordingly the need of studies on weight-bearing surrounding periarticular fractures has been advocated.

Acetabular fractures in the elderly population are becoming more common and pose significant challenges for treatment including postoperative rehabilitation. Our aim is to investigate if patients benefit of a more liberal weight-bearing regime postoperatively. The primary outcome is measured at 1 year, secondary outcomes are followed up to 10 years postoperatively

Inclusion Criteria:

• Unilateral dislocated acetabulum fracture (displacement of over 2mm in preoperative CT scan)
• The osteosynthesis is performed during 21 days after initial trauma
• The patient is willing to participate in the follow-up

Exclusion Criteria:

• Unwillingness to participate in randomisation
• Bilateral fracture
• Letournel & Judet type Both column or Posterior column and wall fractures
• Any other injury that prevents the patient from partial weight bearing
• Open fracture of the acetabulum
• Pathologic fracture (fragility fractures are not an exclusion criteria)
• Prior functional disability in the pelvis or lower extremity
• Non-Compliance due to dementia or other mental disability
• Prior daily pain medication due to hip-pain
• Unwillingness to accept one of the two mobilisation protocols
• Prior hip replacement on injured side
• BMI > 40

The surgeon is masked The investigator is masked