Hip Dislocation

Definition/Description

Hip dislocation is the dislocation of the femoral head from the acetabulum. Most of the time, this results in damage to the tissues surrounding the hip joint. Traumatic hip dislocations are considered a medical emergency and treatment should be sought as soon as possible. [1]

Clinically Relevant Anatomy

The ball-and-socket joint of the hip anatomy is found in the acetabulum and femoral head. The acetabulum is cup-shaped and the femoral head is spherical. [2]

The hip joint is a load-bearing ball joint that primarily provides support. The stability of the hip joint is provided primarily by the joint capsule and its surrounding muscles and ligaments. They stabilize the femoral head in the acetabulum and ensure that the hip joint can move in all available planes.

Epidemiology /Etiology

Characteristics

The following patient characteristics confer an increased risk of developing hip dislocation:[3]

• Female > male
• Alcohol abuse
• Various pre-operative disorders
• Older age:
  • Reduced muscle mass reduces stress on the hip prosthesis and reduces natural protection against hip dislocation
  • Increased risk of falls due to impaired balance
  • Neuromuscular dysfunction associated with old age – eg, neuropathy or cerebrovascular accident
  • Cognitive impairments
• Great dexterity
• Poor follow instructions
• Increased tendency to fall
• Chronic hip instability[4]

Causes

The causes of hip dislocation can be mainly divided into two categories, mainly congenital hip dislocation and acquired hip dislocation.

Congenital hip dislocation (CHD)

Also known as developmental dysplasia of the hip (DDH). All newborns are evaluated for DDH of the hip within a few days of life and within six weeks, so that treatment can be initiated as early as possible if necessary. [5] The incidence of CHD is 1.5 to 20 per 1.000 births, an 8-fold increase in Girls are more common than boys. [6][7] This is because women have greater hip mobility. [3] More than 80% of clinically unstable hips have been shown to resolve spontaneously at birth. [8]

Hip dysplasia in an adult

Acquired hip dislocation

Young adults are most affected by traumatic hip dislocations, mainly caused by motor vehicle accidents, and are often the result of high-strength external forces. [9] Another common mechanism is falling from a height. [5] Thus, hip dislocations are rarely isolated and often occur in combination with other disorders Injury or fracture. When the hip is dislocated, the soft tissues surrounding the hip, such as the muscles, ligaments, and labrum, can also be damaged. Nerve damage may also be present. [5] Acetabular and femoral head fractures are most commonly associated with traumatic hip dislocation. [9] Hip dislocation Depending on the displacement of the femoral head relative to the acetabulum, it is classified as anterior or posterior. Posterior dislocations of the hip are more common, accounting for approximately 85-90% of cases. [10] The position of the hip joint will be in flexion adduction and internal rotation with significant The legs are shortened. For anterior hip dislocations, the hip will be minimally flexed and positioned in abduction and external rotation.

A superiorly dislocated hip post trauma

The highest incidence of dislocation after hip arthroplasty occurs immediately or in the first three months after surgery. This is usually caused by less trauma, usually a fall or turning into a contraindicated position and exerting pressure on the cut capsule for Replacement surgery. The incidence of hip dislocation after hip replacement surgery depends on patient surgery and hip implant factors. In general, the larger the femoral head after surgery, the less likely the patient will be to dislocate.

Dislocated total hip replacement

Characteristics/Clinical Presentation

• Pain:[4]
  • Severe pain is the most common symptom. As the femoral head separates from the acetabulum, the surrounding muscles and tendons can also be damaged. Subsequent knee injuries may also be present.
  • Radiating knee pain
• Swelling
• Leg length differences and deformities:
  • Most often the affected leg will be shortened and the hip deformed
• Hip immobility:[4]
  • Reduced hip range of motion
  • inability to walk due to pain and swelling
• Traumatic hip dislocations:[9]
  • Male > female
  • Posterior > anterior
• There may be neurological consequences (mainly in the distribution of the sciatic nerve)

Differential Diagnosis

• Hip dysplasia
• Hip sublaxation

Diagnostic Procedures

• X-rays: AP pelvis and lateral
  • Confirmation of misalignment and successful relocation
  • Assess for associated fractures
  • Progression of hip dysplasia
• CT:
  • Rule out concomitant injuries to traumatic dislocations (eg, acetabular or femoral head fractures)
  • Clearance of lumbar spine[11]

Complications

Immediate:[5]

• Associated soft tissue injuries
• Nerve injury, especially the sciatic nerve in posterior dislocations (approximately 10% of traumatic dislocations)
• Fracture primarily of the femoral head or acetabulum (primarily the posterior wall)

Long term:[9]

• Avascular necrosis:
  • The 1.7-40% incidence can be reduced to 0-10% if relocation occurs within 6 hours of traumatic dislocation[12]
• Post-traumatic osteoarthritis
• Chronic dislocations
• Leg length discrepancy

Examination

• Observation:
  • Hip dislocation can usually be diagnosed by looking at the hip joint. In the more common posterior dislocations, the hip shortens with external rotation and slight flexion and adduction.
• Imaging (as explained above)
• Neurological evaluation (to identify any associated nerve damage)

Medical Management

Conginital dislocation

Conservative management

• Neonates: flexion/abduction maneuvers.
• Brace: A brace splint or brace can be used to keep the hip in flexion and abduction for a month or two by using a brace splint or brace.
  • This aims to keep the femoral head in its correct position while the ligaments and bone grow and strengthen around it.

Surgery

Surgery is indicated for failure of conservative treatment.

Surgery requires release of the adductor longus muscle, lengthening of the psoas tendon, and insertion of a Kirschner wire. This can significantly improve hip function and prevent future complications. [4] Total hip replacement surgery is an option later in life when function is evident There are limitations and pain.

Acquired hip dislocation

A dislocated hip should be repositioned as soon as possible because the risk of complications from ischemic necrotic nerve injury and subsequent dislocation increases with the time between dislocation and repositioning. [9] The Allis maneuver is usually the preferred reduction method for posterior osteoporosis dislocation[9]

Non-surgical

Closed displacement of the hip is accomplished by applying traction in the opposite direction of dislocation while the hip is flexed to 90°. This is best done under general or local anesthesia and muscle relaxation to prevent further damage to the cartilage and soft tissues. [8] It may It can also be done under anesthesia in the operating room. [5] After repositioning, the stability of the hip joint should be tested very carefully. Depending on the stability of the hip joint and the extent of soft tissue damage, a period of bed rest may be recommended.

Surgical

Indications:

• Failed conservative relocation
• Instability after conservative relocation
• Associated fractures of the femoral head or acetabulum
• Loose bone fragments in the displaced joint space

Hip arthroscopy may be used to assess intra-articular fractures and cartilage damage and to remove intra-articular debris Hip replacement surgery may also be considered if the associated injury is not displaced and immobilized for optimal stability. [9] Hip dislocation Replacement surgery may mean revision surgery to ensure long-term stability of the hip joint.

Open reduction indications:[9]

• For challenging relocation or any obstruction (eg loose debris/soft tissue) limiting closed reduction
• Neurologic deterioration after closed reduction (especially sciatic nerve function after posterior dislocation)
• Cases of Proximal Femur Fracture Contraindication to Lower Extremity Manipulation

Physiotherapy Management

In rehabilitation after hip dislocation, it is important to consider the time frame for soft tissue healing (and, in the case of associated fractures, bone healing). The plastic surgeon will provide guidance on possible weight-bearing limitations after surgery Medical management of the hip. Full recovery after a hip dislocation may take 2-3 months. [5]

• Gait re-education: initial use of mobility aids (walking frame/crutches) to limit weight loading and its progression
• Improving hip range of motion: especially stretching in children after using a brace/splint/brace to maintain hip flexion
• Strengthens the muscles around the hips, with a special focus on the hip stabilizers
• Stretching
• Joint mobilization
• Graded return to activity/sport

See rehabilitation resources below.

Resources

• Hip Dislocation Surgery Rehabilitation Guide
• Hip Dislocation Surgery Rehabilitation Program
• Hip Surgical Dislocation Guidelines

Clinical Bottom Line

Hip dislocations are divided into congenital and acquired. Congenital hip dislocation or developmental hip dysplasia can be treated successfully in children but can cause problems later in life as total hip replacement surgery may be required to improve function of the difference in leg length and pain. Acquired or traumatic hip dislocation is a medical emergency and treatment should be sought as soon as possible. Ideally, relocation should occur within 6 hours of dislocation to minimize complications. Traumatic dislocations reduce open or closed and open or In cases with associated fractures, arthroscopic surgery may be required. Physiotherapy plays an important role in rehabilitation after hip dislocation to return the patient to their previous level of function and prevent further dislocation.