Hip Injuries and Dislocations Overview

Hip Injuries

• Hip dislocation is rare but often involves associated injuries.
• The mechanism is typically high-energy trauma in young patients.
• Hip dislocation is a significant orthopaedic emergency.

Hip Dislocation Classification

• Simple: Pure dislocation without additional fractures.
• Complex: Dislocation with fracture of the acetabulum or proximal femur.

Anatomical Classification (Posterior Dislocation)

• Posterior dislocation accounts for about 90% of cases.
• It occurs with axial loading on the femur, usually when the hip is flexed and adducted.
• Dashboard injuries are a common cause due to axial loading through a flexed knee.

Associated Injuries with Posterior Dislocation

• Avascular necrosis (osteonecrosis) of the femoral head can occur.
• Posterior wall acetabular fractures may be present.
• Femoral head fractures can occur.
• Sciatic nerve injuries can result in the impairment of the nerve.
• Ipsilateral knee injuries can be observed in approximately 25% of cases.

Anatomical Classification (Anterior Dislocation)

• Anterior dislocation is associated with femoral head impaction or chondral injury.
• This occurs when the hip is in abduction and external rotation.

Clinical Presentation of Hip Injuries

• History: Includes symptoms and circumstances leading up to the injury.
• Symptoms: Acute pain, inability to bear weight, deformity (obvious malformation).
• Physical Exam: ATLS (Advanced Trauma Life Support) protocol is important, as 95% of dislocations occur with associated injuries.

Clinical Presentation (Posterior Dislocation)

• Commonly associated with posterior wall and anterior femoral head fractures.
• The hip and leg exhibit slight flexion, adduction and internal rotation.
• Neurovascular exam is crucial (sciatic nerve injury possibly occurs in 10-20% of cases)
• Examine the knee for any associated injuries as well.

Clinical Presentation (Anterior Dislocation)

• The hip and leg exhibit flexion, abduction and external rotation.
• Often an obvious malformation can be observed.

Radiology of Hip Injuries

• X-ray: AP pelvis view often reveals posterior dislocation. The femoral head is usually smaller on the injured side compared to the uninjured. Shenton's line, a curved line, is often broken. The lesser trochanter shadow may not be apparent in the affected (internally rotated) limb.
• CT: Used to determine the direction of dislocation to exclude any loose bodies and associated fractures in the area.

Treatment of Hip Injuries

• Hip injuries are orthopaedic emergencies.
• Immediate ATLS protocol is paramount.
• Perform emergent closed reduction (UGA) within 6 hrs.
• The patient is supine and traction is applied in line with the deformity.
• Adequate sedation and muscle relaxation are essential.
• Evaluate hip stability after reduction.

Post-reduction of Hip Injuries

• Post-reduction CT scan is often required to detect associated fractures and verify correct concentricity of reduction (incarcerated fragments are addressed).
• Protected weight bearing is typically required for 4 to 6 weeks after a simple dislocation.

Operative Treatment of Hip Injuries (Open Reduction)

• Necessary for irreducible dislocations, incarcerated fragments, delayed presentations, or non-concentric reduction.
• Open reduction and/or removal of the incarcerated fragments are often done on an urgent basis.
• Associated fractures of the acetabulum, femoral head, or femoral neck may need to be stabilized prior to reducing the hip.

Complications of Hip Injuries

• Post-traumatic osteoarthritis (OA): Can occur in up to 20% of simple dislocations and is more frequent in complex cases.
• Femoral head osteonecrosis: Occurs in 5-40%, often linked with a delayed reduction.
• Sciatic nerve injury: Has an incidence of 8-20% and can delay treatment.
• Associated fractures: fractures to the femur shaft.

Femoral Neck Fracture

• Epidemiology: Common in the aging population (women more than men, postmenopausal often).
• Mechanism of Trauma: Usually high-energy in youth and low-energy falls in older adults.
• Associated injuries: Femoral shaft fractures (6-9%)
• Prognosis: Higher mortality rates (25-30% at 1 year) compared to vertebral compression fracture, often pre-injury mobility is a key determinant of post-operative outcome.

Pathophysiology of Femoral Neck Fractures

• The femoral neck is bathed in synovial fluid (intracapsular), lacks a periosteal layer, leading to limited callus formation, and negatively impacting healing.

Blood Supply to the Femoral Head

• The medial femoral circumflex artery is a major supplier; contributions also come from the lateral femoral circumflex artery and the artery of the ligamentum teres. Proper blood supply to femoral neck is critical since a disrupted blood supply (often seen in displaced femoral neck fractures) may cause intracapsular hematoma.

Classification of Femoral Neck Fractures (Garden Classification)

• Garden stage I: Undisplaced and incomplete, often valgus impacted, in which no actual bone dislocation exists.
• Garden stage II: Undisplaced complete fracture
• Garden stage III: Complete fracture, incompletely displaced
• Garden stage IV: Completely displaced, complete fracture

Classification of Femoral Neck Fractures (Pauwels Classification)

• This classification is based on the inclination angle of the fracture line to the femoral neck and varies based on I/II/III levels.

Anatomical Classification of Femoral Neck Fractures

• Transcervical fracture
• Basicervical frcture
• Subcapital fracture

Clinical Presentation, Symptoms

• Impacted & stress fractures: Mild to moderate groin pain, pain along the medial aspect of thigh/knee.
• Displaced fractures: Pain in the entire hip region.

Clinical Presentation, Physical Exam

• Impacted & stress fractures: Mild discomfort with ROM (active or passive), no obvious deformity, muscle spasms at extremes of motion, localised pain when percussion is applied over the greater trochanter.
• Displaced fractures: Obvious Clinical deformity (patient cannot walk), pain with percussion, leg in external rotation and abduction, leg shortening.

Radiology

• Obtain AP pelvis and cross-table lateral images of the femur. Internal rotation. AP hip images are often used to precisely define the fracture type. Garden classification is primarily based on AP pelvis x-rays.

Treatment, Nonoperative

• Bed rest.
• Considered for some non-ambulatory patients with minimal pain and high risk to sustain surgical intervention.

Treatment, Operative (CRIF)

• Indicated for displaced fractures in younger/physiologically younger patients (< 65 years old).

Treatment approach (General Considerations)

• Based on: Displacement, patient's physiological age, presence of ipsilateral femoral neck and shaft fractures. Femoral neck fracture is most crucial and usually addressed first to avoid AVN & non-union complications.

Treatment (Multiple Cancellous Screws)

• Indications applicable to nondisplaced and minimally displaced transcervical and Garden classification I/II fractures in older patients with nondisplaced or minimally displaced fractures. Displaced transcervical fractures in younger patients. Surgical intervention may be essential. Necessary steps include reducing any displaced fractures to minimise vascular compromise.

Treatment (Dynamic (Sliding) Hip Screw)

• Indications include basicervical fractures and vertical fractures in younger patients. This approach is often biomechanically better than multiple cancellous screws.

Treatment (Hemiarthroplasty)

• Debilitated elderly patients
• Metabolic bone disease (osteoporosis)
• Neglected fractures

General Considerations for Surgical Procedure

• Reduction method and quality has more pronounced effect on healing than time of surgery. Bring elderly patients to surgery as soon as medically feasible. Emphasise the benefits of early post-surgery mobility. Good clinical outcomes are improved in younger/medcially fit patients if surgery is performed within 4 days from the injury.

Complications from Hip Fracture Treatment

• Avascular necrosis (AVN) of femoral head
• Non-union
• Mal-union
• Associated fractures (femoral shaft)
• Post-traumatic Osteoarthritis (OA)