High Yield Overview

HIP DISLOCATIONS - TIME IS HIP

90% Posterior | Reduce within 6 Hours | Sciatic Nerve at Risk

90%Posterior dislocations

6hGolden time to reduce

10-20%Sciatic nerve injury

20-40%AVN risk if delayed

DIRECTION OF DISLOCATION

Posterior

Pattern90% - dashboard injury, knee flexed

TreatmentUrgent closed reduction

Pattern10% - forced abduction, obturator/pubic type

TreatmentClosed reduction, assess stability

Central

PatternWith acetabular fracture

TreatmentTreat as acetabular fracture

Critical Must-Knows

Posterior dislocation is most common (90%) - mechanism is dashboard injury (knee hitting dashboard = flexed hip)
Sciatic nerve at risk in posterior dislocation (10-20%) - peroneal division most vulnerable
6-hour golden window - AVN risk increases significantly if reduction delayed beyond 6 hours
Associated fractures common - femoral head (Pipkin), acetabulum (posterior wall), femoral neck
CT post-reduction mandatory to assess concentric reduction and associated fractures

Examiner's Pearls

"
Posterior: leg shortened, adducted, internally rotated. Anterior: externally rotated, abducted
"
Sciatic nerve palsy: most recover by 2 years, explore if no recovery by 6 months
"
Pipkin I and II = different - Pipkin I below fovea (ORIF), Pipkin II above fovea (excise if small)
"
Thompson-Epstein classification for posterior; Epstein classification for anterior

Clinical Imaging

Imaging Gallery

(a) Anterior-posterior radiograph of a left posterior hip dislocation. (b) After proper sedation in the emergency department, the hip was successfully reduced. — (a) Anterior-posterior radiograph of a left posterior hip dislocation. (b) After proper sedation in the emergency department, the hip was successfullyCredit: Skelley NW et al. via Sports Health via Open-i (NIH) (Open Access (CC BY))

Antero-posterior radiograph (a) of 60 years female with Garden stage IV and Pauwels type II subcapital femoral neck fracture. Immediate postoperative antero-posterior radiograph (b) of the same patien — Antero-posterior radiograph (a) of 60 years female with Garden stage IV and Pauwels type II subcapital femoral neck fracture. Immediate postoperative Credit: Magu NK et al. via Indian J Orthop via Open-i (NIH) (Open Access (CC BY))

Antero- posterior radiograph of hip: posterior dislocation of hip associated with fracture of acetabulum, femoral head, femoral neck, greater trochanter — Antero- posterior radiograph of hip: posterior dislocation of hip associated with fracture of acetabulum, femoral head, femoral neck, greater trochantCredit: Jangir R et al. via J Orthop Case Rep via Open-i (NIH) (Open Access (CC BY))

Pedigree drawings of the family with Developmental Dysplasia of the Hip (DDH). Open squares and circles represent unaffected males and females, respectively. Filled squares and circles represent affec — Pedigree drawings of the family with Developmental Dysplasia of the Hip (DDH). Open squares and circles represent unaffected males and females, respecCredit: Open-i / NIH via Open-i (NIH) (Open Access (CC BY))

Bilateral posterior hip dislocations - imaging and surgical treatment — Seven-panel (a-g) bilateral posterior hip dislocations in 30-year-old male: (a) Pre-reduction AP pelvis showing bilateral posterior dislocations with femoral heads superior to acetabula. (b) Post-reduction AP showing hips relocated. (c-d) CT axial and sagittal demonstrating posterior wall fractures requiring surgical fixation. (e-g) Intraoperative photos showing posterior approach, femoral head inspection, and acetabular wall repair.Credit: Keel MJ et al., Eur J Trauma Emerg Surg - CC BY 4.0

Critical Hip Dislocation Exam Points

Time is Critical

6-hour golden window for reduction. AVN risk increases from 5% (under 6h) to 40%+ (over 12h). This is a true orthopaedic emergency. Reduce as soon as possible.

Sciatic Nerve

10-20% sciatic nerve injury in posterior dislocation. Peroneal division most vulnerable. Document nerve function BEFORE and AFTER reduction. Most recover by 2 years.

Associated Injuries

High-energy mechanism - look for associated injuries: femoral head fracture (Pipkin), acetabular fracture (posterior wall), femoral neck fracture (15%), knee injuries (PCL, patella).

Post-Reduction CT

CT mandatory after reduction. Assess for: concentric reduction, incarcerated fragments, femoral head impaction, acetabular fracture, femoral neck fracture.

Quick Decision Guide

Injury Pattern	Key Finding	Treatment	Pearl
Simple posterior dislocation	No fracture on X-ray	Urgent closed reduction, CT after	6-hour window - treat as emergency
Posterior + posterior wall fracture	Posterior wall on CT	Reduce, CT assess wall size, ORIF wall	Wall over 40% = unstable, needs fixation
Posterior + Pipkin fracture	Femoral head fragment	Reduce, Pipkin classification guides Rx	Pipkin I (below fovea) = consider ORIF
Dislocation + femoral neck fracture	Femoral neck visible	Cannot reduce closed - open reduction	Devastating injury - high AVN risk
Anterior dislocation	Leg externally rotated, abducted	Closed reduction	Less common (10%), check femoral vessels

Mnemonic

SAIDPosterior Hip Dislocation Position

Shortened

Leg appears shorter

Adducted

Leg pulled toward midline

Internally rotated

Foot points inward

Dashboard injury

Mechanism - knee hits dashboard

Memory Hook:The patient SAID 'my knee hit the dashboard' - leg is Short, Adducted, Internally rotated, from Dashboard injury!

Mnemonic

FABERAnterior Hip Dislocation Position

Flexed

Hip may be slightly flexed

Abducted

Leg falls away from midline

Bulge anteriorly

Head palpable in groin

Externally rotated

Foot points outward

Rare (10%)

Much less common than posterior

Memory Hook:Anterior dislocation puts the hip in forced FABER position!

Mnemonic

6 AVN6-Hour Rule Importance

6 hours

Golden window for reduction

AVN risk

Avascular necrosis increases

Very urgent

True orthopaedic emergency

No delay

Every hour counts

Memory Hook:After 6 hours, AVN risk climbs - '6 AVN' reminds you time is hip!

Mnemonic

PERONEAL PRONESciatic Nerve in Posterior Dislocation

Peroneal

Division most at risk

Examine

Before and after reduction

Recovery expected

90% recover by 2 years

Observe initially

Most are neuropraxia

No recovery at 6 months

Consider exploration

EMG/NCS

If not recovering at 3 months

Always document

Medicolegal requirement

Lateral nerve vulnerable

Peroneal = lateral

Memory Hook:Peroneal is prone to injury when the hip goes posterior!

Overview and Epidemiology

Why This Topic Matters

Hip dislocation is a true orthopaedic emergency with time-sensitive management. The examiner will test your understanding of the 6-hour rule, sciatic nerve considerations, and associated injuries. Getting the basics wrong shows poor emergency management understanding.

Demographics

Young adults (MVA, high-energy trauma)
Native hips - dislocation rare in healthy hip
Male predominance (2:1) - high-risk activities
Prosthetic hips - much more common (different topic)

Mechanism

MVA most common (dashboard injury)
High-energy sports (AFL, rugby)
Industrial accidents
Fall from height
Force vector determines direction

Anatomy and Mechanism

Key Anatomical Concept

The hip is inherently stable - a ball-and-socket joint requiring significant force to dislocate. Stability comes from: bony congruity, acetabular labrum, strong capsular ligaments (iliofemoral, pubofemoral, ischiofemoral), and surrounding muscles.

Femoral Head Blood Supply

Artery	Source	Contribution	Clinical Relevance
MFCA - Retinacular vessels	Profunda femoris	80-90% of head	Damaged in dislocation - AVN risk
LFCA	Profunda femoris	Minimal	Minor contribution
Ligamentum teres artery	Obturator artery	10-20% (variable)	More important in children
Intraosseous from neck	Metaphyseal	Variable	May be compromised

AVN Mechanism

Dislocation stretches/tears the retinacular vessels (from MFCA) that supply the femoral head. Prolonged dislocation = prolonged ischemia. AVN risk doubles after 6 hours and approaches 50% after 12-24 hours.

Classification Systems

Thompson-Epstein Classification (Posterior)

Type	Description	Treatment
Type I	Simple dislocation, no/minimal fracture	Closed reduction, conservative
Type II	Posterior wall rim fracture (small)	Closed reduction, assess stability
Type III	Large posterior wall fracture (unstable)	ORIF posterior wall
Type IV	With acetabular floor fracture	ORIF acetabulum
Type V	With femoral head fracture (Pipkin)	Pipkin classification guides treatment

Practical Simplification

In practice, think: Simple dislocation (reduce urgently) vs Complex (with fracture - reduce, then definitive fix). CT post-reduction determines if wall/head fixation needed.

Clinical Assessment

History

Mechanism: MVA, dashboard, sport - force vector matters
Time of injury: 6-hour rule critical
Associated injuries: polytrauma? knee injury?
Medical history: native vs prosthetic hip
Anticoagulation: bleeding risk assessment

Examination

ATLS first in polytrauma
Obvious deformity - position diagnostic
Leg length discrepancy
Neurovascular status: sciatic (peroneal), femoral
Knee examination: PCL, patella (dashboard)
Log roll: pelvic stability

Posterior vs Anterior Clinical Signs

Finding	Posterior	Anterior
Leg position	Shortened, adducted, IR (SAID)	Abducted, externally rotated
Knee position	Flexed	May be extended
Head palpable	Not anteriorly (empty)	Palpable in groin (bulge)
Nerve at risk	Sciatic (peroneal)	Femoral, lateral cutaneous
Frequency	90%	10%

Polytrauma Assessment

ATLS takes priority. Hip dislocation often occurs in polytrauma setting. Complete primary and secondary survey. Missed ipsilateral femoral neck fracture is a disaster - do not attempt closed reduction if neck fracture suspected.

Investigations

Imaging Protocol

ImmediateAP Pelvis X-ray

Diagnosis usually obvious. Look for associated fractures: posterior wall, femoral head (shenton's arc), femoral neck. Do not delay reduction for extensive imaging.

Pre-ReductionLateral Hip (if available quickly)

Judet views if stable. Do not delay reduction - X-ray after if unstable patient.

Post-ReductionCT Scan (MANDATORY)

Assess: concentric reduction, incarcerated fragments, femoral head impaction, posterior wall size, occult femoral neck fracture. This dictates further treatment.

If SuspectedMRI

Suspected labral pathology, soft tissue incarceration, early AVN assessment. Not urgent.

X-ray Signs of Hip Dislocation

Posterior hip dislocation on AP pelvis radiograph with splinting — Acute posterior hip dislocation: (a) AP pelvis radiograph demonstrating left posterior hip dislocation with the femoral head displaced superolaterally relative to the acetabulum. Note the smaller apparent head size compared to the contralateral side (head is further from the plate) and internal rotation of the femur. (b) Splinted position for transport showing the externally rotated, shortened limb. Posterior dislocations account for 90% of traumatic hip dislocations and typically result from dashboard injuries.Credit: Open-i/PMC - CC BY 4.0

Posterior Dislocation

Head superolateral to acetabulum
Smaller apparent head size (further from plate)
Shenton's line disrupted
Look for posterior wall fragment
Internal rotation of lesser trochanter

Anterior Dislocation

Head inferomedial (obturator) or anteromedial (pubic)
Larger apparent head size (closer to plate)
Shenton's line disrupted
External rotation - lesser trochanter prominent
Head may overlap obturator foramen

Posterior hip dislocation with CT confirmation and post-reduction imaging — Classic posterior hip dislocation case (A-E). (A) AP pelvis X-ray showing left hip posterior dislocation with femoral head displaced superolaterally (arrows). (B-C) Axial CT scans demonstrating the posteriorly dislocated femoral head and associated injury. (D-E) Post-reduction X-rays confirming concentric reduction with normal hip joint alignment restored.Credit: PMC - CC BY 4.0

Management Algorithm

6-Hour Rule

Reduce within 6 hours! Every hour of dislocation increases AVN risk. Under 6h = 5% AVN. 6-12h = 15-20% AVN. Over 12h = 30-50% AVN. This is non-negotiable - prioritize reduction.

Flowchart for Hip Dislocation Management — Management Algorithm for Hip Dislocation - This flowchart outlines the decision pathway from initial reduction to definitive management.Credit: OrthoVellum

Closed Reduction Technique - Comprehensive Guide

Pre-Procedure Preparation

Documentation

Time of injury - 6-hour rule critical
Sciatic nerve exam - document BEFORE reduction
Peroneal: dorsiflexion, toe extension, dorsal foot sensation
Tibial: plantarflexion, plantar sensation
Informed consent - AVN, nerve injury, need for open procedure

Setup

General anaesthesia or deep sedation - muscle relaxation essential
Theatre or ED resuscitation bay (if stable)
Fluoroscopy available - confirm reduction
Assistant to stabilize pelvis - this is crucial
Padded table - patient supine
Backup plan for open reduction if needed

Allis Maneuver (Preferred Technique)

Step-by-Step Allis Maneuver

Step 1Position Patient

Supine on firm table. Assistant positioned at patient's pelvis with hands pressing down on ASIS bilaterally. This counterforce is essential - without it, you'll pull the whole patient toward you.

Step 2Flex Hip and Knee

Stand at the side of the table, facing the patient's head. Flex the hip to 90° and knee to 90°. This relaxes the iliofemoral ligament (strongest ligament in body) and positions the head at the acetabular opening.

Step 3Apply Axial Traction

Grasp the proximal tibia/knee region. Apply steady, in-line axial traction pulling the femur toward the ceiling (with hip at 90°). This is NOT a jerking motion - steady sustained force.

Some surgeons place knee in crook of elbow for leverage
Full body weight can be used - stand on table if needed

Step 4Gentle Rotation

While maintaining traction, apply gentle internal and external rotation to the leg. This helps disengage the femoral head from behind the acetabulum and guides it over the rim.

Listen/feel for a satisfying clunk of reduction
Do NOT use excessive force or rotation

Step 5Confirm Reduction

Once reduced, leg should return to normal length and alignment. Test ROM carefully - hip should move through flexion, extension, rotation smoothly. Obtain fluoroscopy or X-ray immediately.

Technique Pearl - Leverage

For strong patients or difficult reductions, stand on the table for better leverage. Place the patient's knee in the crook of your elbow, hold the tibia, and use your body weight to provide steady axial traction. This is the "Captain Morgan" technique variation.

Alternative: Stimson Maneuver

Stimson Technique

Patient prone on table with injured leg hanging off
Hip flexed over edge of table (90°)
Knee flexed to 90°
Gravity provides traction on the hanging limb
Assistant stabilizes pelvis
Surgeon applies downward pressure on calf with gentle rotation
Useful when Allis fails, but requires rolling patient prone

Advantages/Disadvantages

Advantages:

Gravity provides continuous traction
Less physical effort for surgeon
Muscle relaxation with gravity

Disadvantages:

Requires rolling polytrauma patient prone
Cannot visualize patient face (airway)
Not suitable for unstable patients

Critical Technical Points

Do's

Document sciatic nerve function before AND after
Ensure adequate sedation/relaxation - fighting muscles = failure
Use steady sustained traction - not jerky movements
Have assistant stabilize pelvis firmly
Confirm reduction with imaging immediately
Get CT post-reduction - mandatory

Don'ts

Don't use excessive force - risk of iatrogenic fracture
Don't attempt more than 2-3 times - go to open if failing
Don't reduce if femoral neck fracture suspected - catastrophic
Don't forget post-reduction CT - miss fragments or wall
Don't delay for imaging - time is hip, reduce first
Don't wait for specialist if unavailable - reduce within 6h

Troubleshooting Failed Reduction

Problem	Likely Cause	Solution
Can't reduce despite good traction	Incarcerated fragment (labrum, osteochondral)	Proceed to open reduction - cannot force closed
Reduces but immediately redislocates	Posterior wall fracture (unstable)	Maintain reduction with traction, CT, plan ORIF wall
Patient fighting reduction attempts	Inadequate muscle relaxation	Increase sedation/paralysis, ensure full GA
Reduction attempted but limb still short/IR	Not actually reduced, head still out	Obtain fluoro immediately, reattempt or open
Clunk felt but CT shows non-concentric	Incarcerated soft tissue or fragment	Urgent operative removal of incarcerated tissue

When to Abandon Closed Reduction

Stop closed reduction if: (1) X-ray shows femoral neck fracture - closed forces will displace it, (2) More than 2-3 gentle attempts fail - something is blocking reduction, (3) Patient becomes hemodynamically unstable. Proceed to open reduction urgently - still need to meet 6-hour window.

Surgical Technique

Closed Reduction Technique

Preparation:

Adequate anesthesia and muscle relaxation (GA preferred)
Fluoroscopy available
Assistant required for counter-traction

Posterior Dislocation (Allis/Bigelow):

Patient supine, assistant stabilizes pelvis
Hip flexed to 90 degrees, knee flexed
Inline traction along femoral axis
Gentle internal rotation while maintaining traction
Feel for "clunk" as head relocates
Assess stability through range of motion

Anterior Dislocation:

External rotation, extension, and traction
Less common, often require open reduction

Post-Reduction Assessment:

Fluoroscopy to confirm concentric reduction
Full ROM under fluoro to assess stability
CT scan to exclude loose fragments or fracture

Emergency reduction within 6 hours is critical to minimize AVN risk.

Complications

Complication	Incidence	Risk Factors	Management
AVN	10-40%	Delayed reduction over 6h, repeated attempts	Surveillance, THA if symptomatic
Sciatic nerve injury	10-20%	Posterior dislocation, bone fragments	Observe, most recover by 2 years
Post-traumatic OA	20-40%	Cartilage damage, malreduction, AVN	Activity modification, THA long-term
Recurrent dislocation	Rare in native hip	Posterior wall deficiency, malreduction	Revision ORIF or THA
Heterotopic ossification	3-5%	Delayed surgery, brain injury	Prophylaxis: indomethacin or RT
Femoral head collapse	Variable	AVN, untreated Pipkin	THA

Posterior hip dislocation with intra-articular loose bodies on CT — Four-panel (a-d) left posterior hip dislocation with intra-articular fragments: (a) Lateral X-ray showing posterior dislocation. (b) Post-reduction AP pelvis with Shenton's line drawn (dotted line) showing persistent incongruency on left. (c-d) CT axial and coronal with arrows indicating intra-articular loose body causing non-concentric reduction. These fragments require surgical removal to prevent cartilage damage and improve reduction quality.Credit: Karthik K et al., Indian J Orthop - CC BY 4.0

Avascular Necrosis

AVN Timeline

AVN may take 6-24 months to become apparent on X-ray. MRI can detect earlier (marrow changes). Follow with X-rays at 6 weeks, 3 months, 6 months, 1 year, 2 years. Treat symptomatic AVN with THA.

Postoperative Care and Rehabilitation

Rehabilitation Protocol

Protected Weight BearingWeek 0-6

Toe-touch or protected weight bearing depending on stability. Bed rest initially. Thromboprophylaxis. ROM exercises.

Progressive Weight BearingWeek 6-12

If stable and no fracture: progress to full weight bearing. If ORIF: protected until fracture healing assessed on X-ray.

StrengtheningMonth 3-6

Full weight bearing. Progressive strengthening. Gait training. Hip abductor focus.

Return to ActivityMonth 6+

Return to sport/activity once strength restored. Long-term surveillance for AVN (X-rays).

Weight Bearing Decisions

Simple dislocation (no fracture, concentric reduction): May weight bear as tolerated early. With posterior wall ORIF: Protected until wall healed (6-12 weeks). Pipkin ORIF: Depends on fragment size and fixation.

Outcomes and Prognosis

Prognostic Factors

Outcomes by Pattern

Pattern	Good Outcome Rate	Key Factors	Complications
Simple posterior dislocation	70-80%	Early reduction, no fracture	AVN 5-10%, OA 15-20%
Posterior + wall fracture	50-70%	Quality of reduction, wall stability	AVN 10-20%, OA 20-40%
Pipkin I	60-70%	Fragment size, excision vs ORIF	AVN 10-20%
Pipkin II	40-60%	Articular involvement, reduction quality	AVN 20-30%, OA 30-50%
Pipkin III	20-40%	Age, dual blood supply injury	AVN 40-60%, often THA

Factors Affecting Outcome

Favorable Factors

Reduction within 6 hours, Simple dislocation without fracture, Concentric stable reduction achieved, Young patient without comorbidities, No sciatic nerve injury

Unfavorable Factors

Delayed reduction over 6-12 hours, Associated acetabular or femoral head fracture, Non-concentric or unstable reduction, Sciatic nerve injury (peroneal component), Repeated closed reduction attempts

Long-term Outcomes

Most patients with simple posterior dislocations reduced within 6 hours have good functional outcomes. The main determinants of long-term outcome are development of AVN and post-traumatic osteoarthritis. Younger patients may tolerate mild degenerative change better than older patients. THA remains the salvage procedure for severe AVN or debilitating arthritis.

Evidence Base and Key Trials

Timing and AVN - Hougaard Retrospective

Hougaard K, Thomsen PB • Injury (1986)

Key Findings:

Retrospective study of 100 posterior dislocations
5% AVN if reduced within 6 hours
40%+ AVN if reduced after 12 hours
Established the 6-hour golden rule

Clinical Implication: Reduce posterior hip dislocations within 6 hours to minimize AVN risk.

Limitation: Retrospective, older study, but principle widely accepted.

Sciatic Nerve Prognosis

Hillyard RF, Fox J • J Bone Joint Surg Am (2003)

Key Findings:

Retrospective review of sciatic injuries with hip dislocation
90% had partial or complete recovery
Peroneal division slower to recover
Exploration if no recovery by 6 months

Clinical Implication: Most sciatic injuries recover - observe initially, explore if not improving by 6 months.

Limitation: Retrospective, variable follow-up.

Posterior Wall Stability - Moed

Moed BR et al. • J Orthop Trauma (2007)

Key Findings:

40% posterior wall involvement = unstable
Dynamic exam under fluoro to assess stability
Unstable walls need ORIF
Buttress plating technique

Clinical Implication: CT measurement of posterior wall size guides surgical decision - over 40% = ORIF.

Limitation: Measurement technique can vary.

Pipkin Fracture Outcomes

Stannard JP et al. • J Orthop Trauma (2000)

Key Findings:

Pipkin I outcomes better than Pipkin II
Small fragments below fovea can be excised
Large fragments or weight-bearing involvement = ORIF
Pipkin III has high failure rate

Clinical Implication: Fragment location and size guides Pipkin treatment. Pipkin III = prepare for THA.

Limitation: Small numbers, variable techniques.

HO Prophylaxis - Neal

Neal B et al. • Cochrane Database (2010)

Key Findings:

NSAIDs or radiation reduce HO
Indomethacin 75mg daily for 6 weeks
Single-dose RT 700cGy effective
Consider in high-risk (TBI, delayed surgery)

Clinical Implication: Prophylaxis for HO if risk factors present - indomethacin or radiation.

Limitation: Bleeding risk with NSAIDs, radiation availability.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: Simple Posterior Hip Dislocation

EXAMINER

"A 25-year-old male is brought to ED after an MVA. He was an unrestrained front passenger. His left leg is shortened, adducted, and internally rotated. He has no other obvious injuries and is haemodynamically stable. X-ray shows a posterior hip dislocation with no obvious fracture. It is 2 hours since the accident. How would you manage this patient?"

EXCEPTIONAL ANSWER

This is a posterior hip dislocation in a young male 2 hours post-injury - a true orthopaedic emergency where time is critical. My priorities are: First, complete ATLS assessment - though he seems stable, MVA can have occult injuries. I would ensure there is no C-spine injury before manipulation. Second, before any reduction, document **sciatic nerve function** - test dorsiflexion (peroneal) and plantarflexion (tibial), and sensation over the dorsum of foot and lateral leg. Document carefully pre-reduction. Third, this needs **urgent closed reduction** - we are within the 6-hour golden window. After 6 hours, AVN risk increases significantly. I would perform reduction under GA or deep sedation in theatre with muscle relaxation. My technique would be the **Allis maneuver**: hip and knee flexed to 90 degrees, axial traction along the femur with gentle rotation. Fourth, post-reduction: reassess neurovascular status (document any change), confirm reduction with X-ray, and obtain **CT scan** to assess for concentric reduction, posterior wall integrity, loose bodies, and occult femoral head or neck fracture. Fifth, if CT shows concentric reduction and no significant wall fracture, I would manage with toe-touch weight bearing initially, thromboprophylaxis, and surveillance for AVN with serial X-rays.

KEY POINTS TO SCORE

Time is critical - 6-hour rule for AVN prevention

Document sciatic nerve function BEFORE reduction

Reduce urgently under GA/sedation with muscle relaxation

Allis maneuver: hip/knee 90°, axial traction, gentle rotation

CT post-reduction is mandatory - concentric reduction, wall, fragments

COMMON TRAPS

✗Delaying reduction for extensive imaging

✗Not documenting neurovascular status before reduction

✗Not getting CT post-reduction (missing fragments or wall fracture)

✗Aggressive repeated reduction attempts risking iatrogenic injury

LIKELY FOLLOW-UPS

"What if CT shows 45% posterior wall fracture?"

"What if he has a foot drop post-reduction that wasn't there before?"

"What follow-up would you arrange for AVN surveillance?"

VIVA SCENARIOChallenging

Scenario 2: Hip Dislocation with Posterior Wall Fracture

EXAMINER

"A 30-year-old female presents after a motorcycle accident with a posterior hip dislocation. You perform closed reduction successfully at 4 hours post-injury. Post-reduction CT shows concentric reduction but a displaced posterior wall fragment involving approximately 50% of the articular surface. She has normal sciatic nerve function. What is your further management?"

EXCEPTIONAL ANSWER

This is a posterior hip dislocation with a significant posterior wall fracture - the CT shows 50% involvement which is well above the 40% threshold for instability. Even though the hip is reduced, this will be unstable and will redislocate with normal hip movement. My management would be: First, confirm reduction is maintained - this should be stable at rest, but will likely redislocate with flexion/internal rotation. I would keep her in traction or a posterior hip brace until surgery. Second, plan for **ORIF of the posterior wall** within the next 3-7 days. Urgent but not overnight emergency now that the hip is reduced. Third, the approach would be a **Kocher-Langenbeck** posterior approach. The key steps are: protect the sciatic nerve, debride the fracture hematoma, reduce the posterior wall fragment anatomically, and fix with a spring plate and lag screws functioning as a buttress plate. Fourth, intraoperatively, I would assess posterior wall stability under fluoroscopy with hip flexion to ensure the repair is stable. Fifth, postoperatively, I would use hip precautions (avoid flexion beyond 70-80°, no adduction, no IR) and protected weight bearing for 6-12 weeks until the wall has healed.

KEY POINTS TO SCORE

Posterior wall over 40% = unstable, needs ORIF

Kocher-Langenbeck approach for posterior wall fixation

Protect sciatic nerve during surgery

Spring/buttress plate fixation principle

Hip precautions and protected WB post-op

COMMON TRAPS

✗Conservative treatment of 50% wall fracture - will redislocate

✗Not recognizing the instability threshold (40%)

✗Not protecting sciatic nerve during posterior approach

✗Excessive hip flexion before wall healed

LIKELY FOLLOW-UPS

"What are the dangers of the Kocher-Langenbeck approach?"

"How do you assess posterior wall stability intraoperatively?"

"What HO prophylaxis would you use?"

VIVA SCENARIOCritical

Scenario 3: Pipkin Fracture

EXAMINER

"A 35-year-old presents after an MVA with a posterior hip dislocation. You reduce the hip successfully at 5 hours. CT post-reduction shows a femoral head fragment (Pipkin type II - above the fovea involving 30% of the weight-bearing surface). The acetabulum appears intact. There is no sciatic nerve injury. How would you manage this?"

EXCEPTIONAL ANSWER

This is a Pipkin II fracture - a femoral head fracture above the fovea involving 30% of the weight-bearing surface. This is a complex injury with significant implications because the fragment involves the critical weight-bearing dome of the femoral head. My management would be: First, the hip is reduced and we are within acceptable time for vascular supply - that is good. However, a Pipkin II with 30% involvement cannot be ignored. Second, this fragment needs to be addressed surgically. The options are: (1) **ORIF of the fragment** - this is my preference for a fragment this size involving weight-bearing surface. Fix with countersunk headless screws (Herbert or Acutrak) via either a surgical hip dislocation (Ganz) approach for anterosuperior access or anterior approach (Smith-Petersen). (2) **Fragment excision** - only if fragment is small and comminuted, not appropriate here with 30% involvement. Third, my preferred approach would be a **Ganz surgical hip dislocation**: trochanteric osteotomy, anterior hip dislocation, direct visualization of the femoral head for anatomic reduction and screw fixation. This protects the blood supply. Fourth, postoperatively, protected weight bearing for 6-8 weeks, thromboprophylaxis, and surveillance for AVN which remains a risk. I would counsel the patient that long-term outcome may include OA or AVN requiring hip replacement.

KEY POINTS TO SCORE

Pipkin II = above fovea, involves weight-bearing surface

30% involvement = significant, needs ORIF not excision

Ganz surgical dislocation approach preserves blood supply

Headless countersunk screws for fixation

Prognosis guarded - AVN and OA risks remain

COMMON TRAPS

✗Excising a large weight-bearing fragment

✗Ignoring the fragment and treating conservatively

✗Using posterior approach which limits head visualization

✗Not counseling about long-term prognosis

LIKELY FOLLOW-UPS

"How does Pipkin I differ from Pipkin II in management?"

"Describe the Ganz surgical hip dislocation approach"

"What is a Pipkin III and how would you manage it?"

MCQ Practice Points

Timing Question

Q: What is the approximate AVN rate if a posterior hip dislocation is reduced after 12 hours? A: 40-50%. The 6-hour rule: under 6h = 5% AVN, 6-12h = 20%, over 12h = 40%+. Time to reduction is the most important modifiable factor.

Nerve Question

Q: Which division of the sciatic nerve is most commonly injured in posterior hip dislocation? A: Peroneal (common peroneal) division. It is more lateral and tethered, making it more vulnerable. Clinically presents as foot drop and dorsal foot numbness.

Clinical Question

Q: What is the classic leg position in posterior hip dislocation? A: Shortened, Adducted, Internally Rotated (SAID). The leg appears shorter, is pulled toward midline, with the foot pointing inward. This is the dashboard injury position.

Wall Question

Q: At what percentage of posterior wall involvement does the hip become unstable post-reduction? A: Over 40% posterior wall involvement. This threshold indicates the need for ORIF to prevent redislocation. Assess on CT post-reduction.

Classification Question

Q: What distinguishes Pipkin I from Pipkin II femoral head fractures? A: Pipkin I = below the fovea (infrafoveal), spares weight-bearing surface. Pipkin II = above the fovea (suprafoveal), involves weight-bearing surface and has worse prognosis.

Imaging Question

Q: What mandatory imaging is required after closed reduction of a hip dislocation? A: CT scan. Essential to assess: concentric reduction (no incarcerated fragments), posterior wall integrity, femoral head fracture, occult femoral neck fracture, and loose bodies.

Australian Context

Epidemiology

MVA remains main cause despite seatbelt laws
High-speed rural crashes
AFL and NRL occasional sporting injury
Elderly falls - often prosthetic hip
Trauma network designation matters for referral pathways

Medicolegal Considerations

Key documentation: (1) Time of injury AND time of reduction - the 6-hour rule, (2) Sciatic nerve exam before AND after reduction, (3) Consent including AVN and nerve risks, (4) Post-reduction CT performed and reviewed, (5) Follow-up plan for AVN surveillance. Delayed reduction and missed sciatic nerve injury are litigation risks.

HIP DISLOCATIONS

High-Yield Exam Summary

Key Facts

•Posterior 90%, Anterior 10%
•6-hour rule: reduce early to minimize AVN
•SAID position: Shortened, Adducted, IR (posterior)
•Dashboard injury = posterior dislocation

Sciatic Nerve

•10-20% injury rate in posterior dislocation
•Peroneal division most vulnerable
•Document BEFORE and AFTER reduction
•90% recover by 2 years, explore at 6 months if not

Thompson-Epstein

•Type I-II: Simple or small wall fragment
•Type III: Large posterior wall (over 40%) - ORIF
•Type IV: Acetabular floor fracture
•Type V: Femoral head fracture (Pipkin)

Pipkin Classification

•Pipkin I: Below fovea - better prognosis
•Pipkin II: Above fovea - weight-bearing involved
•Pipkin III: With femoral neck - disaster
•Pipkin IV: With acetabular fracture

Post-Reduction CT

•MANDATORY after every reduction
•Check: concentric reduction, wall, fragments
•Non-concentric = incarcerated tissue/bone
•Over 40% wall = needs ORIF

AVN Rates

•Under 6 hours: 5% AVN
•6-12 hours: 20% AVN
•Over 12 hours: 40%+ AVN
•Surveillance X-rays for 2 years

Injury Pattern

Key Finding

Treatment

Pearl

Simple posterior dislocation

No fracture on X-ray

Urgent closed reduction, CT after

6-hour window - treat as emergency

Posterior + posterior wall fracture

Posterior wall on CT

Reduce, CT assess wall size, ORIF wall

Wall over 40% = unstable, needs fixation

Posterior + Pipkin fracture

Femoral head fragment

Reduce, Pipkin classification guides Rx

Pipkin I (below fovea) = consider ORIF

Dislocation + femoral neck fracture

Femoral neck visible

Cannot reduce closed - open reduction

Devastating injury - high AVN risk

Anterior dislocation

Leg externally rotated, abducted

Closed reduction

Less common (10%), check femoral vessels

Artery

Source

Contribution

Clinical Relevance

MFCA - Retinacular vessels

Profunda femoris

80-90% of head

Damaged in dislocation - AVN risk

LFCA

Profunda femoris

Minimal

Minor contribution

Ligamentum teres artery

Obturator artery

10-20% (variable)

More important in children

Intraosseous from neck

Metaphyseal

Variable

May be compromised

Type

Description

Treatment

Type I

Simple dislocation, no/minimal fracture

Closed reduction, conservative

Type II

Posterior wall rim fracture (small)

Closed reduction, assess stability

Type III

Large posterior wall fracture (unstable)

ORIF posterior wall

Type IV

With acetabular floor fracture

ORIF acetabulum

Type V

With femoral head fracture (Pipkin)

Pipkin classification guides treatment

Finding

Posterior

Leg position

Shortened, adducted, IR (SAID)

Abducted, externally rotated

Knee position

Flexed

May be extended

Head palpable

Not anteriorly (empty)

Palpable in groin (bulge)

Nerve at risk

Sciatic (peroneal)

Femoral, lateral cutaneous

Frequency

90%

10%

Problem

Likely Cause

Solution

Can't reduce despite good traction

Incarcerated fragment (labrum, osteochondral)

Proceed to open reduction - cannot force closed

Reduces but immediately redislocates

Posterior wall fracture (unstable)

Maintain reduction with traction, CT, plan ORIF wall

Patient fighting reduction attempts

Inadequate muscle relaxation

Increase sedation/paralysis, ensure full GA

Reduction attempted but limb still short/IR

Not actually reduced, head still out

Obtain fluoro immediately, reattempt or open

Clunk felt but CT shows non-concentric

Incarcerated soft tissue or fragment

Urgent operative removal of incarcerated tissue

Closed Reduction Technique

Preparation:

Adequate anesthesia and muscle relaxation (GA preferred)
Fluoroscopy available
Assistant required for counter-traction

Posterior Dislocation (Allis/Bigelow):

Patient supine, assistant stabilizes pelvis
Hip flexed to 90 degrees, knee flexed
Inline traction along femoral axis
Gentle internal rotation while maintaining traction
Feel for "clunk" as head relocates
Assess stability through range of motion

Anterior Dislocation:

External rotation, extension, and traction
Less common, often require open reduction

Post-Reduction Assessment:

Fluoroscopy to confirm concentric reduction
Full ROM under fluoro to assess stability
CT scan to exclude loose fragments or fracture

Emergency reduction within 6 hours is critical to minimize AVN risk.

Complication

Incidence

Risk Factors

Management

AVN

10-40%

Delayed reduction over 6h, repeated attempts

Surveillance, THA if symptomatic

Sciatic nerve injury

10-20%

Posterior dislocation, bone fragments

Observe, most recover by 2 years

Post-traumatic OA

20-40%

Cartilage damage, malreduction, AVN

Activity modification, THA long-term

Recurrent dislocation

Rare in native hip

Posterior wall deficiency, malreduction

Revision ORIF or THA

Heterotopic ossification

3-5%

Delayed surgery, brain injury

Prophylaxis: indomethacin or RT

Femoral head collapse

Variable

AVN, untreated Pipkin

THA

Pattern

Good Outcome Rate

Key Factors

Complications

Simple posterior dislocation

70-80%

Early reduction, no fracture

AVN 5-10%, OA 15-20%

Posterior + wall fracture

50-70%

Quality of reduction, wall stability

AVN 10-20%, OA 20-40%

Pipkin I

60-70%

Fragment size, excision vs ORIF

AVN 10-20%

Pipkin II

40-60%

Articular involvement, reduction quality

AVN 20-30%, OA 30-50%

Pipkin III

20-40%

Age, dual blood supply injury

AVN 40-60%, often THA

Type	Description	Treatment	Prognosis
Pipkin I	Head fracture BELOW fovea	Small = excise; large = ORIF	Better - spares weight-bearing
Pipkin II	Head fracture ABOVE fovea	ORIF if possible; large = poor prognosis	Worse - weight-bearing surface
Pipkin III	Any head fracture + femoral neck fracture	THA (young) or fix neck then head	Poor - double blood supply insult
Pipkin IV	Any head fracture + acetabular fracture	ORIF acetabulum, address head	Complex, requires staging

Type	Hip Position	Head Location	Associated
Obturator (Inferior)	Flexed, abducted, ER	Obturator foramen area	Head impaction common
Pubic (Superior)	Extended, abducted, ER	Public ramus area	Less common, femoral vessel risk

Feature	What to Assess	Why It Matters
Concentric reduction	Joint space equal all around	Non-concentric = incarcerated fragment
Posterior wall	Size and displacement of fragment	Over 40% wall = unstable, needs ORIF
Femoral head	Impaction, osteochondral fragments	Pipkin classification, ORIF planning
Femoral neck	Occult fracture	Missed neck = complications
Acetabular columns	Associated column fractures	May change surgical approach
Loose bodies	Intra-articular fragments	Needs arthroscopic or open removal

Indication	Reason	Preferred Approach
Failed closed reduction	Incarcerated fragment or buttonholing	Posterior (Kocher-Langenbeck)
Non-concentric reduction on CT	Intra-articular loose body	Arthroscopy or Kocher-Langenbeck
Associated femoral neck fracture	Cannot reduce closed safely	Anterior (Smith-Petersen) for neck access
Large posterior wall fracture (over 40%)	Requires ORIF for stability	Kocher-Langenbeck
Pipkin fracture requiring ORIF	Large or displaced head fragment	Ganz (anterior) or Kocher-Langenbeck

Problem	Cause	Solution
Cannot visualize sciatic nerve	Buried in scar/hematoma	Trace from sciatic notch, use nerve stimulator, extend exposure
Hip still unstable after wall ORIF	Inadequate reduction or wall size	Re-assess reduction, consider additional plate, bone graft
Articular impaction on head	Femoral head impaction injury	Elevate and bone graft if amenable, or accept and monitor for OA
Bleeding from superior gluteal vessels	Injury during exposure	Ligate carefully, avoid disrupting nerve
Femoral head fragment too comminuted for ORIF	Severe Pipkin injury	Excise fragments if not weight-bearing; if severe consider THA

Associated Injury	Timing	Treatment
Posterior wall fracture over 40%	After reduction, CT confirmation	ORIF via Kocher-Langenbeck
Pipkin I (below fovea, small)	After reduction	Excision, may consider ORIF if large
Pipkin II (above fovea)	After reduction	ORIF if possible, salvage if not
Pipkin III (with neck fracture)	Urgent	Fix neck first or consider THA
Pipkin IV (with acetabulum)	Staged	Reduce, then ORIF acetabulum + head
Femoral neck fracture	Do NOT reduce closed!	Open reduction, fix neck first

Hip Dislocations

Hip Dislocations

HIP DISLOCATIONS - TIME IS HIP

DIRECTION OF DISLOCATION

Critical Must-Knows

Examiner's Pearls

Clinical Imaging

Imaging Gallery

Critical Hip Dislocation Exam Points

Time is Critical

Sciatic Nerve

Associated Injuries

Post-Reduction CT

Quick Decision Guide

SAIDPosterior Hip Dislocation Position

FABERAnterior Hip Dislocation Position

6 AVN6-Hour Rule Importance

PERONEAL PRONESciatic Nerve in Posterior Dislocation

Overview and Epidemiology

Demographics

Mechanism

Anatomy and Mechanism

Key Anatomical Concept

Femoral Head Blood Supply

Sciatic Nerve Anatomy

Course

Vulnerability

Sciatic Nerve Injury Pattern

Mechanism of Dislocation

Posterior (90%)

Anterior (10%)

Classification Systems

Thompson-Epstein Classification (Posterior)

Pipkin Classification (Femoral Head Fractures)

Pipkin III - The Disaster

Anterior Hip Dislocation Classification

Clinical Assessment

History

Examination

Posterior vs Anterior Clinical Signs

Polytrauma Assessment

Investigations

Imaging Protocol

X-ray Signs of Hip Dislocation

Posterior Dislocation

Anterior Dislocation

Post-Reduction CT Evaluation

Management Algorithm

6-Hour Rule

Closed Reduction Technique - Comprehensive Guide

Pre-Procedure Preparation

Documentation

Setup

Allis Maneuver (Preferred Technique)

Step-by-Step Allis Maneuver

Alternative: Stimson Maneuver

Stimson Technique

Advantages/Disadvantages

Critical Technical Points

Do's

Don'ts

Troubleshooting Failed Reduction

When to Abandon Closed Reduction

Open Reduction - Kocher-Langenbeck Approach

Pre-operative Planning (If Open Required)

Consent Points

Equipment

Kocher-Langenbeck Approach (Comprehensive)

Step-by-Step K-L Approach

Critical Technical Points

Sciatic Nerve Protection

Posterior Wall ORIF Principles

Intraoperative Troubleshooting

Closure

HO Prophylaxis

Management of Associated Injuries

Surgical Technique

Closed Reduction Technique

Open Reduction Indications

Femoral Head Fracture Management