Hip Fracture-Dislocations

Hip fracture-dislocations are high-energy injuries combining hip dislocation with associated fractures (femoral head, acetabulum, femoral neck). They are true orthopaedic emergencies requiring urgent reduction within 6 hours to minimize AVN risk. The Thompson-Epstein classification guides treatment based on associated fractures.

Mechanism of Injury

Posterior dislocation (90%):

• Dashboard injury: Knee strikes dashboard with hip flexed
• High energy: Motor vehicle accident, fall from height
• Associated fractures: Femoral head (Pipkin), posterior wall, femoral neck

Anterior dislocation (10%):

• Forced abduction: Hip forced into abduction and external rotation
• Less common: Usually lower energy
• Associated fractures: Less common

Central dislocation:

• Acetabular fracture: Medial displacement through acetabulum
• High energy: Usually part of complex acetabular fracture pattern

Epidemiology

• Incidence: 5-10% of hip dislocations have associated fractures
• Age: Peak 20-40 years (high-energy trauma)
• Gender: Male predominance (3:1 ratio)
• Laterality: Usually unilateral
• Associated injuries: Other fractures (20-30%), head injury (10-15%), knee injuries (10-15%)

Hip Joint Anatomy

The hip joint:

• Ball-and-socket: Femoral head in acetabulum
• Stability: Bony and ligamentous (labrum, capsule, ligaments)
• Blood supply: MFCA (80%), retinacular vessels, ligamentum teres (under 10%)
• Nerves: Sciatic nerve (posterior), femoral nerve (anterior)

Posterior structures at risk:

• Sciatic nerve: Lies posterior to hip, vulnerable in posterior dislocation
• Peroneal division: Most vulnerable (lateral position)
• Tibial division: Less vulnerable (medial position)

Pathophysiology

Posterior dislocation mechanism:

• Dashboard injury: Knee strikes dashboard with hip flexed
• Force transmission: Posterior force on flexed hip
• Dislocation: Femoral head dislocates posteriorly
• Associated fractures: Femoral head (impaction), posterior wall (shear), femoral neck (rare)

Blood supply disruption:

• Retinacular vessels: Disrupted with displacement
• MFCA: May be stretched or torn
• AVN risk: Increases with time to reduction
• 6-hour window: Critical for blood supply preservation

Associated fracture patterns:

• Femoral head (Pipkin): Impaction or shear fracture
• Posterior wall: Shear fracture from dislocation
• Acetabular floor: Central dislocation pattern
• Femoral neck: Rare but devastating (Pipkin III)

History

Mechanism: High-energy trauma

• Dashboard injury: Motor vehicle accident (posterior dislocation)
• Fall from height: High-energy fall
• Sports: Contact sports, high-impact activities

Symptoms:

• Immediate severe pain
• Inability to bear weight
• Leg deformity (shortening, rotation)
• Numbness or weakness (if nerve injury)

Physical Examination

Inspection:

• Posterior dislocation: Leg shortened, adducted, internally rotated
• Anterior dislocation: Leg externally rotated, abducted
• Deformity obvious
• Swelling (may be minimal initially)

Palpation:

• Tenderness over hip
• Palpable femoral head (posterior or anterior)
• Greater trochanter position abnormal

Range of Motion:

• Severely limited (pain, mechanical block)
• Fixed deformity

Neurovascular Status:

• Sciatic nerve: Assess dorsiflexion, plantarflexion, sensation (first web space, lateral foot)
• Vascular: Distal pulses, capillary refill
• Document BEFORE reduction: Critical for medicolegal and clinical assessment

Associated Injuries

• Femoral head fracture (Pipkin): 10-15%
• Posterior wall fracture: 20-30%
• Acetabular fracture: 10-15%
• Femoral neck fracture: 5-10% (Pipkin III)
• Knee injuries: 10-15% (PCL, patella)
• Other fractures: 20-30%

The acutely painful, deformed hip after trauma has a focused differential. The priority is to distinguish a true dislocation (reduce now) from an isolated fracture (different pathway), and to never miss an occult femoral neck fracture before pulling on the leg.

The topic's open-reduction indications name "incarcerated fragments" and "non-concentric reduction," and the irreducible-hip viva raises "interposed soft tissue or an entrapped nerve" — but the single most important post-reduction question deserves its own framework: once the head is back in the socket, is the reduction truly concentric? In a fracture-dislocation this is not a formality, because bone and cartilage fragments generated by the injury are the classic block to congruity.

Confirming concentricity

• Immediate post-reduction AP then mandatory CT: compare the injured hip's joint space with the normal side.
• Asymmetric or widened joint space — a medial or superior clear space greater than 2 mm relative to the contralateral hip — means the hip only looks reduced. There is interposed tissue or a retained fragment until CT proves otherwise.
• A hip that reduces then re-subluxates, or "clunks" through range, signals mechanical incongruity or gross instability rather than a stable reduction.

Why a closed reduction fails (the irreducible hip)

Roughly a small minority of posterior dislocations are irreducible by closed means. Recognised blocks include:

• Buttonholing of the femoral head through a rent in the posterior capsule or the short external rotators.
• Inverted or infolded labrum trapped between head and acetabulum.
• Incarcerated osteochondral or bony fragment — a posterior-wall or Pipkin femoral-head fragment lodged in the joint (the fracture-dislocation-specific block).
• Interposed piriformis or gluteal tendon.
• An ipsilateral femoral neck fracture absorbing the reduction force — which is why the neck must be scrutinised first; forcing traction here is dangerous.

Why a "reduced" hip stays non-concentric

Even after a successful-looking reduction the joint may remain incongruent because of an incarcerated intra-articular fragment (most common), an infolded labrum, a retained ligamentum teres remnant, or interposed capsule.

Response

Do not keep pulling. After a maximum of 2-3 gentle attempts under adequate relaxation, an irreducible or non-concentric hip is an indication for open reduction, approach dictated by the pathology (usually Kocher-Langenbeck for a posterior fragment): remove loose bodies, reduce and fix the wall or head fragment, and confirm concentric congruity. Retained fragments are not benign — they cause third-body wear, chondral abrasion and accelerated post-traumatic arthritis.

AVN

5-40% incidence (depends on timing and pattern):

• Cause: Disruption of blood supply, delayed reduction, displacement
• Prevention: Urgent reduction (under 6 hours), anatomic reduction
• Management: Monitor with X-rays (6, 12 weeks, 1 year), THA if symptomatic

Sciatic Nerve Injury

10-20% incidence:

• Cause: Dislocation itself or surgical approach
• Prevention: Protect nerve during approach, document function
• Management: Observation (most recover by 2 years), explore if no recovery by 6 months

Heterotopic Ossification

20-30% incidence:

• Cause: Surgical approach, delayed reduction, associated injuries
• Prevention: Prophylaxis (indomethacin, radiation)
• Management: Excision if symptomatic (wait for maturity)

The complications table and the AVN discussion both flag heterotopic ossification (HO) at roughly 20-30% (and 25% in the surgical-hip-dislocation meta-analysis) and prescribe "prophylaxis (indomethacin, radiation)" without detail — yet the when, how much and to whom is a recurring viva point that the topic never develops.

Risk stratification

HO is the price of operative posterior exposure, not of the dislocation itself. Risk is highest with the Kocher-Langenbeck approach, extensive muscle stripping, retained devitalised gluteus minimus, delayed surgery, associated head injury, and male sex. A simple closed reduction with no operative wound carries a low HO risk and needs no prophylaxis.

Grading — the Brooker classification

• Brooker I: islands of bone within the soft tissues.
• Brooker II: bone spurs from pelvis or femur with at least 1 cm between opposing surfaces.
• Brooker III: opposing bone surfaces with less than 1 cm between them.
• Brooker IV: apparent bony ankylosis of the hip.

Only the higher grades (III-IV) usually become clinically relevant through loss of motion.

Prophylaxis options

Established HO

Excise only symptomatic HO and only once mature — a quiescent bone scan and normalised alkaline phosphatase, usually beyond 6-12 months — combining excision with peri-operative single-dose radiotherapy or indomethacin to limit recurrence.

Immediate Postoperative

• Immobilization: None (early mobilization)
• Weight bearing: Depends on associated fractures
  • Simple dislocation: Touch-down weight bearing 6-8 weeks
  • With fractures: Non-weight bearing until fractures heal
• ROM: Early hip ROM (immediate)
• PT: Hip ROM, strengthening

Rehabilitation Protocol

Weeks 0-2:

• Touch-down or non-weight bearing (depending on fractures)
• Hip ROM exercises
• Quadriceps and hip strengthening
• Ice and elevation

Weeks 2-6:

• Continue protected weight bearing
• Progressive ROM and strengthening
• Balance and proprioception

Weeks 6-12:

• Progressive weight bearing (if fractures healed)
• Full ROM
• Progressive activity

Weeks 12+:

• Return to sport (when strength and ROM normal)
• Continue monitoring for AVN (X-rays at 6, 12 weeks, 1 year)

Return to Sport

Criteria:

• Full ROM (equal to contralateral)
• Strength greater than 90% of contralateral
• No pain or instability
• Functional testing passed
• No AVN on imaging

Timeline: Usually 6-12 months postoperatively, depending on associated injuries.

Overall Outcomes

Simple dislocation (Type I):

• Success rate: 85-90% (with urgent reduction)
• Functional outcomes: 80-85% return to pre-injury level
• Complications: 10-15% (AVN, HO, arthritis)

With fractures (Type II-V):

• Success rate: 70-85% (depends on fracture pattern)
• Functional outcomes: 70-80% return to pre-injury level
• Complications: 20-30% (AVN, HO, arthritis, nerve injury)

Functional Outcomes

Return to sport:

• Timeline: 6-12 months postoperatively
• Rate: 70-85% return to pre-injury level
• Factors: Associated injuries, AVN, rehabilitation compliance

Functional testing:

• Hip strength: 90%+ of contralateral
• ROM: Full (if no complications)
• No pain or instability

Long-Term Prognosis

AVN risk:

• Type I (under 6h): 5-10%
• Type I (over 12h): 40%+
• Type II-V: 20-40% (depends on timing and pattern)
• Pipkin III: 40-60% (disaster)

Post-traumatic arthritis:

• Type I: 20-30% (at 10 years)
• Type II-V: 30-40% (at 10 years)
• Risk factors: Cartilage injury, AVN, malreduction

Factors Affecting Outcomes

Positive factors:

• Urgent reduction (under 6 hours)
• Simple dislocation (Type I)
• No associated fractures
• Complete rehabilitation

Negative factors:

• Delayed reduction (over 12 hours)
• Associated fractures (Type II-V)
• Pipkin III (head + neck)
• Incomplete rehabilitation

Prevention

Primary prevention:

• Seatbelt use (prevents dashboard injury)
• Airbag deployment
• Safe driving practices
• Protective equipment in sports

Secondary prevention (after injury):

• Complete rehabilitation before return to sport
• Continued strength and conditioning
• Gradual return to activity

Return to Sport Criteria

Clinical:

• Full ROM (equal to contralateral)
• Strength greater than 90% of contralateral
• No pain or instability
• No AVN on imaging

Functional:

• Single-leg hop test (greater than 90% of contralateral)
• Agility testing passed
• Sport-specific drills completed

Timeline: Usually 6-12 months postoperatively, depending on associated injuries and AVN risk.

Global Epidemiology

• Hip dislocation overall is uncommon; roughly 5-15% of all traumatic dislocations and the great majority follow high-energy mechanisms (road traffic collisions, falls from height).
• Posterior pattern accounts for around 90% of cases; associated fractures (femoral head, posterior wall, neck) are present in a substantial minority and define the fracture-dislocation subgroup.
• Strong male predominance (roughly 3:1) with a young peak (20-40 years), mirroring high-energy trauma demographics worldwide.
• In low- and middle-income settings the same injury skews toward motorcycle and pedestrian trauma, and pre-hospital delay is the dominant modifiable risk factor for AVN.

Side-by-Side Guidance

Registries and Practice Variation

• Dedicated dislocation registries are limited, but national arthroplasty registries (NJR UK, AJRR US, AOANJRR Australia, SHAR Sweden) capture the downstream burden: post-traumatic arthritis and AVN are recognised indications for conversion to total hip arthroplasty in young adults.
• High-resource centres: 24/7 trauma access, immediate CT, fellowship-trained pelvic/acetabular surgeons and surgical-hip-dislocation capability.
• Limited-resource centres: emphasis on rapid closed reduction (the single highest-value intervention), selective transfer for complex fixation, and pragmatic non-operative management of small fragments.