Acetabulum Fractures
What Is the Acetabulum?
The acetabulum is the cup-shaped part of the pelvis that forms the socket of the hip. The rounded femoral head fits inside it to create a weight-bearing ball-and-socket joint. Articular cartilage covers both surfaces, while the labrum, capsule and surrounding muscles contribute to stability and smooth movement. An acetabular fracture crosses this socket and may disrupt the joint surface, the front or back wall, one or both structural columns, or several regions at once. It differs from a fracture through the upper femur even though both injuries may be described casually as a broken hip. The hip overview explains the neighbouring anatomy and other conditions that can affect this joint.
How Do Acetabular Fractures Occur?
In younger adults, a high-energy collision, fall from height or crushing injury can drive the femoral head into the socket. The same force may cause a hip dislocation, femoral-head damage, marginal impaction of the socket, sciatic-nerve injury or injuries to the chest, abdomen, spine and other limbs. A hip dislocation needs its own urgent pathway. In older adults, weaker osteoporotic bone may fracture after a fall from standing or another lower-energy event, often with a different anterior-column pattern and substantial impaction. This is distinct from, but may be confused with, common upper-femur hip fractures. Mechanism and bone quality therefore shape both the fracture pattern and the patient’s overall treatment risk.
Symptoms and Associated Injuries
Severe groin, buttock or hip pain and inability to stand or bear weight are common. The leg may appear shortened or rotated if the hip is dislocated, and movement can be extremely painful. Numbness, weakness or altered sensation in the leg or foot may indicate sciatic-nerve involvement. High-energy trauma can also cause bleeding and injuries outside the hip; symptoms from the abdomen, chest, head or spine may be more immediately dangerous than the socket fracture. Associated pelvic fractures can increase concern for blood loss and organ injury. Upper-femur hip fractures require a distinct assessment because they do not cross the socket. A femoral shaft fracture creates another major source of pain, instability and bleeding. Every patient therefore needs a whole-trauma assessment rather than an isolated hip examination.
Understanding Wall, Column and Transverse Patterns
Specialists describe acetabular fractures by the part of the socket and supporting pelvic structure involved. A wall fracture affects the rim that helps contain the femoral head. A column fracture disrupts one of the main front or back structural pathways connecting the socket to the pelvis. A transverse line crosses both columns, while associated patterns combine features. Classification helps surgeons understand stability, select an approach and communicate, but the label alone does not decide treatment. Joint congruence, involvement of the weight-bearing dome, comminution, marginal impaction, cartilage or femoral-head injury, bone quality and the patient’s health are also important. No single displacement threshold applies safely to every pattern and patient.
Emergency Assessment and Hip Reduction
Care begins with trauma priorities: airway, breathing, circulation, bleeding control and identification of head, chest, abdominal, spinal and limb injuries. The hip and skin are inspected without repeatedly moving an unstable limb. Clinicians document pulses, foot warmth and colour, and sciatic-nerve function by testing ankle and toe movement and sensation before and after interventions. A dislocated hip is an orthopaedic emergency and usually requires prompt reduction under appropriate sedation or anaesthesia once immediate life threats are addressed. Reduction puts the femoral head back in the socket; it does not definitively repair the acetabular fracture. If closed reduction is unsafe or unsuccessful, an open procedure may be needed.
X-Rays, CT and Additional Tests
An anteroposterior pelvis X-ray provides an initial overview. Oblique Judet views show the acetabular walls and columns from complementary angles. CT with multiplanar and three-dimensional reconstructions defines fracture lines, displacement, comminution, marginal impaction, loose fragments and the relationship of the femoral head to the socket; post-reduction CT may identify damage hidden on plain films. Imaging is interpreted with the examination rather than used in isolation. Depending on the mechanism and vital signs, the trauma team may order CT of the head, spine, chest, abdomen or pelvis, vascular imaging, blood tests or other organ-specific investigations. Older adults may also need medical optimisation and later assessment of osteoporosis and fall risk.
When Is Non-Operative Treatment Appropriate?
Non-operative care may be appropriate when the hip remains stable and congruent, the important joint surface is acceptably aligned, displacement is limited, or surgical risk outweighs likely benefit. This is a selective decision, not simply a choice based on age. The plan can include pain control, early safe movement, a walker or crutches and protected weight bearing according to the pattern and bone quality. Repeat X-rays are important because alignment can change during healing. Prolonged immobility carries its own risks, so teams address breathing, skin care, nutrition and prevention of deep-vein thrombosis using movement, mechanical measures or medication when appropriate. Worsening pain or loss of alignment prompts reassessment.
When Is Open Reduction and Internal Fixation Considered?
Open reduction and internal fixation (ORIF) may be recommended when displacement disrupts the load-bearing joint surface, the femoral head is not centred, the hip is unstable, fragments remain inside the joint, or a pattern is unlikely to maintain acceptable alignment without fixation. Through an approach chosen for the wall or column involved, the surgeon repositions fragments and secures them with plates and screws. More than one approach or staged surgery is occasionally required for complex patterns. Definitive timing depends on resuscitation, soft-tissue condition, associated injuries and operating priorities; it follows physiological stabilisation rather than a universal calendar. The goal is to improve congruence and stability, but cartilage damage at the moment of injury can still affect the long-term result.
Selected Older Adults: Fixation, Replacement or Both
Older adults often have osteoporotic bone, impaction and comminution that make durable fixation more difficult. ORIF, limited or percutaneous fixation, non-operative care, and total hip arthroplasty (THA) with or without acetabular fixation are all possible strategies. Acute THA may be considered for a selected medically suitable patient when the femoral head or cartilage is badly damaged, reconstruction is unlikely to remain stable, or pre-existing arthritis changes the balance of options. It is not an automatic treatment based on age, and replacement introduces its own risks, including dislocation, infection and later revision. The decision considers fracture pattern, remaining bone, ability to follow weight-bearing precautions, prior function, medical risk and patient goals.
Rehabilitation, Weight Bearing and Recovery
Rehabilitation starts with safe transfers, breathing and circulation exercises, and movement of unaffected joints while the fracture and other injuries are protected. The permitted amount of weight bearing is individualized to fixation stability, fracture pattern, bone quality, pain, balance and associated injuries; it should not be advanced from a generic timetable. Physiotherapy then develops hip movement, muscle activation, gait, balance and everyday function. Follow-up X-rays and clinical review guide progression from walking aids. Recovery varies substantially, and some patients retain pain, weakness, stiffness or reduced endurance. Smoking cessation, adequate nutrition, medication review, osteoporosis assessment and fall-prevention measures can support bone health and reduce the chance of another fragility fracture.
Complications and Long-Term Joint Health
Possible complications include infection, wound problems, bleeding, deep-vein thrombosis or pulmonary embolism, sciatic-nerve dysfunction, fixation failure, malunion, nonunion and recurrent instability. Heterotopic ossification can form bone in soft tissues and restrict movement. Damage to the femoral-head blood supply may lead to osteonecrosis, particularly when dislocation or major joint injury is involved; the hip osteonecrosis page explains that condition. Cartilage injury, residual incongruence or collapse can cause post-traumatic hip arthritis even after appropriate treatment, and later hip replacement may be considered. The hip arthritis page describes how persistent pain, stiffness and declining function are evaluated over time.
When Should You Seek Urgent Help?
After significant trauma, severe hip or groin pain, inability to stand, a shortened or rotated leg, numbness, weakness, a pale or cold foot, dizziness, abdominal pain or breathing difficulty requires emergency assessment. During recovery, seek prompt advice for increasing wound redness or drainage, fever, worsening pain, a new change in leg position, loss of movement or sensation, or calf swelling. Chest pain, sudden shortness of breath, coughing blood or collapse may indicate a pulmonary embolism and requires emergency care. Do not test weight bearing or attempt to relocate a deformed hip yourself. For non-urgent follow-up concerning persistent symptoms or treatment options, use the contact page to arrange an orthopaedic review.