Hip Fracture-Dislocations

Hip fracture-dislocations are high-energy injuries in which the hip dislocates and something breaks with it: the femoral head, the acetabulum or the femoral neck. They are true orthopaedic emergencies, and the Thompson-Epstein classification, which sorts them by the associated fracture, guides treatment.

Mechanism. Direction decides the pattern.

• Posterior - 90%. High energy: a motor vehicle accident, where the knee strikes the dashboard with the hip flexed, or a fall from height. The associated fractures are of the femoral head (Pipkin), the posterior wall and the femoral neck.
• Anterior - 10%. The hip is forced into abduction and external rotation, usually with lower energy, and associated fractures are less common.
• Central. The head displaces medially through the acetabulum. This is high energy and usually part of a complex acetabular fracture pattern.

Who. The peak is at 20-40 years, the injury of high-energy trauma, with a male predominance of 3:1. It is usually unilateral, and 5-10% of hip dislocations have associated fractures.

The joint. The hip is a ball-and-socket joint, the femoral head seated in the acetabulum, and its stability is both bony and ligamentous: labrum, capsule and ligaments. The sciatic nerve lies posterior to it and the femoral nerve anterior.

The blood supply. It comes from the medial femoral circumflex artery (80%), the retinacular vessels and the ligamentum teres (under 10%). Displacement disrupts the retinacular vessels and may stretch or tear the MFCA, and AVN risk increases with time to reduction.

The sciatic nerve. Lying directly behind the hip, it is the nerve at risk in a posterior dislocation. The peroneal division is the most vulnerable, in its lateral position; the tibial division, placed medially, is less so.

How the fractures happen. A posterior force on the flexed hip drives the head out posteriorly, and fractures may come with it:

• Femoral head (Pipkin) - by impaction or shear
• Posterior wall - a shear fracture from the dislocation
• Acetabular floor - the central dislocation pattern
• Femoral neck - rare but devastating (Pipkin III)

Thompson-Epstein. A classification of posterior dislocations by the fracture that comes with them, and the type points to the treatment. Type V hands over to Pipkin for the head fracture.

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Pipkin. The femoral head fractures, and the fovea is the landmark. Below it the fragment is non-weight-bearing and may be excised if small; above it the fragment carries load and is fixed.

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Timing. Injuries are also described by the time to reduction, and every group is still reduced:

• Acute (under 6 hours) - the optimal time; urgent closed reduction
• Subacute (6-12 hours) - still reducible; urgent reduction is still indicated
• Delayed (over 12 hours) - high AVN risk; still reduce, and open reduction may be needed

History. The mechanism is high-energy trauma: a dashboard injury in a motor vehicle accident (the posterior dislocation), a fall from height, or contact and high-impact sport. The patient has immediate severe pain, cannot bear weight and has a deformed leg, shortened and rotated, with numbness or weakness if the nerve is injured.

Inspection. The deformity is obvious and tells you the direction. A posterior dislocation leaves the leg shortened, adducted and internally rotated; an anterior dislocation leaves it externally rotated and abducted. Swelling may be minimal at first.

Palpation and movement. The hip is tender, the femoral head may be palpable posteriorly or anteriorly, and the greater trochanter sits in the wrong place. Movement is severely limited by pain and mechanical block, and the deformity is fixed.

Neurovascular status. For the sciatic nerve, test dorsiflexion, plantarflexion and sensation in the first web space and the lateral foot; for the circulation, the distal pulses and capillary refill.

Associated injuries. The fractures and injuries that accompany the dislocation:

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

Radiographs. An AP pelvis, and a lateral hip if possible. They show the head out of the acetabulum and the associated fractures of the head, acetabulum and neck. The pre-reduction film is essential because a femoral neck fracture must be excluded before reduction is attempted: traction risks displacing it.

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CT. Post-reduction CT is mandatory, even when the joint appears located. It confirms a concentric reduction, classifies a femoral head fracture by Pipkin, measures the size of the posterior wall fragment, finds loose bodies in the joint, and plans the surgical approach. Pre-reduction CT is usually not needed: reduce first, then scan.

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MRI. Rarely needed acutely and not routine. It is indicated for specific concerns: soft-tissue injury, and AVN assessment later, at 6-12 weeks.

The acutely painful, deformed hip after trauma has a focused differential. The priority is to tell a true dislocation, which is reduced now, from an isolated fracture, which follows a different pathway.

The pathway. Reduce, scan, then treat the fracture.

1. Emergency. Pre-reduction radiograph to exclude a femoral neck fracture, nerve function documented, then closed reduction in the emergency department or theatre, within the conventional 6-hour window.
2. Post-reduction CT. Concentricity, loose bodies and the fractures (Pipkin, acetabular, neck), and the plan for definitive treatment.
3. Type I, no fracture. Observe, with protected weight bearing for 6-8 weeks and radiographs for AVN at 6 and 12 weeks and 1 year.
4. Types II-V. Treat the fracture as the classification directs.

Algorithm

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Closed reduction. The Allis manoeuvre for a posterior dislocation:

1. Anaesthesia, sedation or general
2. An assistant stabilises the pelvis
3. Traction in line with the deformity
4. Flexion and internal rotation to disimpact
5. Then traction, external rotation and extension
6. Confirm reduction with fluoroscopy

The Stimson manoeuvre is the alternative: the patient prone with the leg hanging, and gentle traction and rotation. Make no more than 2-3 gentle attempts; if they fail, open reduction is required.

Open reduction. The approach is Kocher-Langenbeck (posterior) or anterior (Smith-Petersen), depending on the pattern.

• Absolute - failed closed reduction after 2-3 gentle attempts, a non-concentric reduction, incarcerated fragments
• Relative - associated fractures that need fixation, delayed presentation (over 12 hours)

Confirming concentricity. Take an immediate post-reduction AP, then the mandatory CT, and compare the joint space with the normal side. A medial or superior clear space greater than 2 mm wider than the contralateral hip means the hip only looks reduced: there is interposed tissue or a retained fragment until CT proves otherwise, and it is an indication for CT and urgent operative removal, never for observation. A hip that reduces then re-subluxates, or clunks through range, signals mechanical incongruity or gross instability rather than a stable reduction.

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Why a closed reduction fails. A small minority of posterior dislocations cannot be reduced closed. The recognised blocks:

• Buttonholing of the femoral head through a rent in the posterior capsule or the short external rotators
• An inverted or infolded labrum trapped between head and acetabulum
• An incarcerated osteochondral or bony fragment, a posterior-wall or Pipkin head fragment lodged in the joint: the block specific to the fracture-dislocation
• Interposed piriformis or gluteal tendon
• An ipsilateral femoral neck fracture absorbing the reduction force, where forcing traction is dangerous

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Why a reduced hip stays non-concentric. Even after a reduction that looks successful the joint may stay incongruent, most commonly from an incarcerated intra-articular fragment, and otherwise from an infolded labrum, a retained ligamentum teres remnant or interposed capsule.

What to do. Stop pulling. An irreducible or non-concentric hip after 2-3 gentle attempts under adequate relaxation needs open reduction, by the approach the pathology dictates, usually Kocher-Langenbeck for a posterior fragment: remove the 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.

Posterior wall. Fix a wall over 40% (unstable), a comminuted wall (Type III) or a non-concentric reduction. Through a Kocher-Langenbeck approach, identify and protect the sciatic nerve, reduce the wall fragments, fix them with a spring plate or buttress plate, and check stability with fluoroscopy. The 40% figure is a guide, and Controversies sets out its limits.

Femoral head (Pipkin). The head is approached from the front, anterior approach (Smith-Petersen or Watson-Jones), to preserve its blood supply.

• Pipkin I - excise a small fragment; fix a large one with headless screws
• Pipkin II - the weight-bearing portion, so ORIF with headless screws, countersunk
• Pipkin III - fix the neck first and urgently, then address the head; the elderly may need THA

Acetabulum (Type IV). A complex pattern that needs acetabular ORIF, perhaps as a staged procedure, with the femoral head addressed separately. The approach, posterior, anterior or combined, depends on the fracture.

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AVN. It follows disruption of the blood supply, delayed reduction and displacement, and it is prevented by urgent, anatomic reduction. Read the evidence carefully (Kellam and Ostrum): the pooled rate for posterior dislocations, 10.6-43%, rises with Thompson-Epstein grade, and the odds ratio of 5.6 for reduction after 12 hours is a relative increase, not an absolute 40% rate. No validated sub-6-hour stratum exists in the cited evidence. The dominant risk is Pipkin III, an associated displaced femoral neck fracture: in Yoon's series both AVN cases were Pipkin III, and no cited rate exists, so do not quote one. Monitor with radiographs at 6 and 12 weeks and 1 year, and offer THA if it becomes symptomatic.

Sciatic nerve injury. Caused by the dislocation itself or by the surgical approach, and prevented by protecting the nerve at operation and documenting its function. Observe it: most injuries recover by 2 years, and a nerve with no recovery by 6 months is explored. The Cornwall review puts the incidence at about 10% in adults and recovery, at least partial, at 60-70%, and complete recovery is less common than that.

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Heterotopic ossification occurs in roughly 20-30% after these injuries (25% in the surgical-hip-dislocation meta-analysis), and prophylaxis with indomethacin or radiation is standard advice. When, how much and to whom is the recurring viva point.

Who is at risk. HO is the price of operative posterior exposure rather than of the dislocation itself. Risk is highest with the Kocher-Langenbeck approach, extensive muscle stripping, retained devitalised gluteus minimus, delayed surgery, an associated head injury, and male sex. A simple closed reduction with no operative wound carries a low risk and needs no prophylaxis; reserve indomethacin or single-dose radiotherapy for high-risk operative cases.

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

• 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 less than 1 cm apart
• Brooker IV - apparent bony ankylosis of the hip

Established HO. Excise only symptomatic HO and only once it is mature, shown by a quiescent bone scan and a normalised alkaline phosphatase, usually beyond 6-12 months. Cover the excision with peri-operative single-dose radiotherapy or indomethacin to limit recurrence.

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Early. No immobilisation: mobilise early and start hip range of motion immediately, with physiotherapy for range and strengthening. Weight bearing depends on the fractures. A simple dislocation is touch-down weight bearing for 6-8 weeks; with fractures the patient is non-weight bearing until they heal.

Rehabilitation protocol. It runs in four stages:

• Weeks 0-2 - touch-down or non-weight bearing depending on the fractures; hip range of motion; quadriceps and hip strengthening; ice and elevation
• Weeks 2-6 - protected weight bearing continues; progressive range and strengthening; balance and proprioception
• Weeks 6-12 - progressive weight bearing if the fractures have healed; full range; progressive activity
• Weeks 12 and beyond - return to sport when strength and range are normal; continued monitoring for AVN

The success-rate and return-to-function percentages in this section are conventional teaching ranges, not measurements from a cited cohort; the verified outcome data on this page are Kellam & Ostrum (AVN 10.6-43%, OR 5.6 beyond 12 hours), Upadhyay (24% osteoarthritis at a mean 14.6 years, occupation-driven), Khalifa (85% satisfactory, 74% anatomic, AVN 12%/HO 25%/OA 16%) and Yoon (AVN confined to Pipkin III).

Post-traumatic arthritis. At 10 years it affects 20-30% after a Type I injury and 30-40% after Types II-V, driven by cartilage injury, AVN and malreduction.

What moves the outcome. Urgent reduction (under 6 hours), a simple Type I dislocation with no associated fracture, and complete rehabilitation favour a good result. Reduction delayed over 12 hours, associated fractures (Types II-V), Pipkin III and incomplete rehabilitation count against it.

Prevention. Primary prevention is seatbelt use, which prevents the dashboard injury, airbag deployment, safe driving practices and protective equipment in sport. After the injury, complete rehabilitation before returning to sport, keep up strength and conditioning, and return to activity gradually.

Return to sport. Usually at 6-12 months after surgery, depending on associated injuries and AVN risk, and 70-85% return to their pre-injury level; associated injuries, AVN and compliance with rehabilitation decide who does. The criteria:

• Full range of motion, equal to the other side
• Strength greater than 90% of the other side
• No pain or instability
• No AVN on imaging
• Single-leg hop greater than 90% of the other side
• Agility testing passed and sport-specific drills completed

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.

The 6-hour rule. Widely taught, but not a sharp biological threshold. The statistically robust step-up in AVN in the meta-analysis comes around the 12-hour mark, and the pragmatic message is unchanged: reduce as soon as safely possible.

The posterior wall threshold. "40% = unstable" oversimplifies. Static CT poorly predicts stability in the 20-50% indeterminate zone, and examination under anaesthesia remains the reference standard for the borderline wall.

Which approach for the femoral head. For displaced femoral head fractures the debate continues between anterior approaches, posterior approaches and the Ganz surgical hip dislocation. Surgical hip dislocation gives the best articular view but adds a trochanteric osteotomy, and its reported AVN rates are comparable rather than clearly superior.

Pipkin I: excise or fix? Small infra-foveal fragments may be excised, but excising larger fragments risks instability and degenerative change. There is no consensus fragment-size cut-off; the decision is individualised to fragment size, comminution and joint congruity.