Femoral Head Fractures

High Yield Overview

FEMORAL HEAD FRACTURES

Pipkin Classification | Associated Hip Dislocation | AVN Risk

6 hoursTarget for dislocation reduction

10-40%AVN rate depending on Pipkin type

75-90%Associated with posterior hip dislocation

Type IVPipkin with acetabular fracture - worst prognosis

PIPKIN CLASSIFICATION

Type I

PatternFragment BELOW fovea (non-weight-bearing)

TreatmentExcise if small, fix if large

Type II

PatternFragment ABOVE fovea (weight-bearing)

TreatmentORIF required

Type III

PatternType I or II + femoral neck fracture

TreatmentArthroplasty (elderly) or fix neck + head

Type IV

PatternType I or II + acetabular fracture

TreatmentFix acetabulum + address head

Critical Must-Knows

Pipkin I = BELOW fovea (non-weight-bearing) - may excise if small fragment
Pipkin II = ABOVE fovea (weight-bearing) - MUST fix or excise
Pipkin III = associated femoral neck fracture - high AVN risk, often arthroplasty
Reduce dislocation URGENTLY - every hour increases AVN risk

Examiner's Pearls

"
Fovea is the KEY landmark - above vs below determines treatment
"
Posterior dislocation = anterior approach for ORIF (avoid posterior blood supply)
"
CT scan ESSENTIAL after reduction - assess fragment size and location
"
Time to reduction is the most important prognostic factor

Clinical Imaging

Imaging Gallery

Entire treatment course of a Pipkin type IV femoral head fracture in a patient with posterior hip dislocation status post motor vehicle collision. Initial AP pelvic radiograph (a) with posterior super — Entire treatment course of a Pipkin type IV femoral head fracture in a patient with posterior hip dislocation status post motor vehicle collision. IniCredit: Wong PK et al. via Int J Emerg Med via Open-i (NIH) (Open Access (CC BY))

Pipkin Type I femoral head fracture with ORIF and 3-year follow-up — Pipkin Type I Femoral Head Fracture. (a) Pre-op AP showing posterior hip dislocation with infrafoveal head fragment. (b) Post-reduction radiograph. (c,d) 3-year follow-up AP and lateral showing excellent outcome after ORIF of fragment below fovea (non-weight-bearing zone).Credit: Shakya et al., BMC Musculoskelet Disord 2023, PMC10116746, CC BY 4.0

Pipkin Type II femoral head fracture with Herbert screw fixation and 7-year follow-up — Pipkin Type II Femoral Head Fracture with Herbert Screw Fixation. (a) Pre-op showing suprafoveal (weight-bearing) fragment. (b) Post-op with Herbert screw. (c) 4-year follow-up. (d) 7-year follow-up showing progression to post-traumatic OA. ORIF is mandatory for Type II as fragment is in weight-bearing zone.Credit: Shakya et al., BMC Musculoskelet Disord 2023, PMC10116746, CC BY 4.0

Pipkin Type III showing CT imaging and combined fixation approach — Pipkin Type III Femoral Head + Neck Fracture. (a) Coronal CT showing femoral head fragment with ipsilateral femoral neck fracture. (b) 3D CT reconstruction for surgical planning. (c) Post-operative AP with Herbert screws for head + cannulated screws for neck via combined approach. Consider THA in elderly due to high AVN risk.Credit: Shakya et al., BMC Musculoskelet Disord 2023, PMC10116746, CC BY 4.0

Time is Femoral Head!

URGENT Reduction Priority

Reduce hip dislocation within 6 HOURS. AVN risk increases exponentially with time. Reduce in ED if possible, OR if not. Do NOT delay for elaborate imaging.

Post-Reduction CT

After concentric reduction confirmed on XR. CT defines fragment size and location. Assess for loose bodies in joint. Plan surgical approach and fixation.

At a Glance

Femoral head fractures (Pipkin classification) occur with posterior hip dislocations and are orthopedic emergencies. URGENT reduction within 6 hours is critical - AVN risk increases exponentially with delay. Pipkin I (fragment inferior to fovea) can often be excised. Pipkin II (fragment involves weightbearing dome) requires ORIF. Pipkin III (with femoral neck fracture) often needs arthroplasty due to high AVN risk. Pipkin IV (with acetabular fracture) requires addressing both injuries. Post-reduction CT scan is ESSENTIAL to assess fragment size and location. Time to reduction is the most important prognostic factor.

Femoral Head Fracture - Pipkin Management Guide

Pipkin Type	Fragment Location	Management
Type I - small fragment	Below fovea (non-weight-bearing)	Excise fragment, remove loose bodies
Type I - large fragment	Below fovea but over 20% surface	Consider ORIF with countersunk screws
Type II	Above fovea (weight-bearing)	ORIF REQUIRED - countersunk screws
Type III - young patient	Any + femoral neck fracture	Fix neck urgently + address head
Type III - elderly patient	Any + femoral neck fracture	Total hip arthroplasty
Type IV	Any + acetabular fracture	Fix acetabulum through posterior + anterior approach for head
Irreducible dislocation	Interposed fragment	Emergent open reduction
Delayed presentation over 6 hours	Any type	Still reduce urgently, accept higher AVN risk

Mnemonic

PIPKINPIPKIN for Classification

Position relative to fovea

Inferior (Type I - below fovea)

Proximal (Type II - above fovea)

Knocked neck (Type III - femoral neck fracture)

Injury to acetabulum (Type IV)

Need urgent reduction regardless

Memory Hook:PIPKIN: I below, II above - just remember 'I is Inferior, II is Superior to fovea'!

Mnemonic

FOVEAFOVEA for Management

Fragment above = Fix it (Type II)

Observe for small fragments below fovea

Very urgent reduction (under 6 hours)

Excise small non-weight-bearing fragments

Approach: anterior for posterior dislocation

Memory Hook:The FOVEA is your landmark - above it means weight-bearing!

Mnemonic

TIMEAVN Risk Factors

Time to reduction (most important)

Initial displacement severity

Multiple reduction attempts

Extended dislocation (over 6 hours)

Memory Hook:TIME is the enemy of the femoral head blood supply!

Mnemonic

SIXSIX for Reduction Time

Six hours is the target

Increasing AVN after six hours

eXpedite reduction urgently

Memory Hook:SIX hours - reduce by six or pay the price!

Overview

Femoral head fractures are uncommon injuries that almost exclusively occur in association with traumatic hip dislocation, most commonly posterior. First classified by Pipkin in 1957, these fractures result from high-energy trauma where the femoral head impacts against the acetabular rim during dislocation.

The critical determinant of outcome is the time from injury to reduction. Prolonged dislocation leads to stretching and occlusion of the medial femoral circumflex artery (MFCA), the primary blood supply to the femoral head. Avascular necrosis (AVN) rates increase dramatically after 6 hours of dislocation.

The Pipkin classification guides management by distinguishing between fragments involving the weight-bearing (superior to fovea - Type II) and non-weight-bearing (inferior to fovea - Type I) portions of the femoral head. Types III and IV represent more complex injuries with associated femoral neck and acetabular fractures respectively.

For the orthopaedic examination, you must know the Pipkin classification, understand the urgency of reduction, and be able to discuss surgical approaches and indications.

Anatomy

Anatomy and Blood Supply

Femoral Head Anatomy

Weight-Bearing Dome:

Superior aspect of femoral head
Covered by articular cartilage
Critical for hip biomechanics
Pipkin II involves this area

Fovea Capitis:

Small depression on femoral head
Attachment of ligamentum teres
Landmark for Pipkin classification
Below fovea = non-weight-bearing

Circumflex femoral arteries anatomy showing medial and lateral circumflex arteries — Circumflex Femoral Arteries. The profunda femoris artery and its branches including the medial femoral circumflex artery (MFCA) - the primary blood supply to the femoral head (80%). The MFCA courses posteriorly and is at risk with posterior hip dislocation, making urgent reduction critical to prevent AVN.Credit: Mikael Häggström, Gray's Anatomy (1918)

Blood Supply (CRITICAL KNOWLEDGE)

Medial Femoral Circumflex Artery (MFCA):

Primary blood supply to femoral head (80%)
Arises from profunda femoris
Courses posterior to femoral neck
Gives off retinacular arteries
AT RISK with posterior dislocation

Lateral Femoral Circumflex Artery:

Minor contribution to head
Supplies greater trochanter primarily

Ligamentum Teres Artery (Foveal Artery):

Branch of obturator artery
Supplies small area around fovea
Contribution variable (significant in 10-20%)
NOT adequate to prevent AVN alone

Why Posterior Dislocation Threatens Blood Supply

MFCA courses posteriorly
Dislocation stretches/kinks artery
Prolonged dislocation = ischemia
Reduction relieves stretch
But damage may be done if delayed

Key Point: Anterior approach for ORIF after posterior dislocation avoids further damage to already compromised posterior blood supply.

Classification Systems

Pipkin Classification (1957)

Pipkin Classification Summary

Type	Fragment Location	Key Feature	Management
Type I	Below fovea	Non-weight-bearing zone	Excise small, ORIF if large
Type II	Above fovea	Weight-bearing zone	ORIF required
Type III	I or II + neck fracture	Very high AVN risk	Arthroplasty (elderly) or fix
Type IV	I or II + acetabular fracture	Complex polytrauma	Combined approaches

Key Landmark

The fovea is the critical landmark. Above fovea = weight-bearing = must fix. Below fovea = non-weight-bearing = may excise if small.

Clinical Presentation

Mechanism

High-Energy Trauma:

Motor vehicle accidents (dashboard injury)
Fall from height
Sporting injuries (rare)
Industrial accidents

Classic Dashboard Mechanism:

Hip flexed and adducted (sitting position)
Knee impacts dashboard
Force transmitted along femur
Posterior dislocation with head fracture

History

Symptoms:

Severe hip/groin pain
Cannot move leg
Leg appears shortened and internally rotated
History of high-energy trauma

Associated Injuries:

Knee injuries (PCL, patella fracture)
Femoral shaft fracture (floating hip)
Other pelvic/acetabular fractures
Sciatic nerve injury (10-20%)

Physical Examination

Classic Posterior Dislocation Position:

Hip flexed, adducted, internally rotated
Shortened leg
Obvious deformity
Unable to move hip

Neurovascular Assessment (MANDATORY):

Structure	Assessment	Injury Rate
Sciatic nerve	Foot dorsiflexion/plantarflexion, sensation	10-20%
Common peroneal	Toe extension, dorsum sensation	Higher risk
Tibial	Toe flexion, plantar sensation	Lower risk
Pulses	Femoral, popliteal, DP, PT	Rare injury

Document Nerve Status BEFORE Reduction:

Crucial for medicolegal purposes
Differentiate injury from iatrogenic damage
Most recover with reduction

Investigations

Initial Imaging

AP Pelvis Radiograph:

First-line investigation
Confirm dislocation
Assess for associated fractures
Do NOT delay reduction for imaging

Lateral Hip (if possible):

Assess posterior dislocation
May be difficult to obtain

Post-Reduction Imaging

AP and Lateral Hip:

Confirm concentric reduction
Look for joint space widening (interposed fragment)
Assess for associated fractures

CT Scan (ESSENTIAL After Reduction)

Indications:

All hip dislocations after reduction
Assess femoral head fracture pattern
Identify loose bodies
Plan surgical approach

CT Findings to Document:

Fragment size (% of head)
Fragment location (above/below fovea)
Articular step-off
Loose bodies in joint
Associated acetabular fracture
Femoral neck integrity

3D Reconstruction

Helpful for surgical planning
Visualize fragment orientation
Assess head sphericity
Plan screw trajectory

MRI (Usually Not Acute)

Assess for early AVN (weeks later)
Cartilage damage assessment
Not routine in acute setting

Management Algorithm

Management Principles

Priority Order:

URGENT REDUCTION - Under 6 hours target
Assess fragment size and location (CT)
Remove incarcerated fragments/loose bodies
Fix weight-bearing fragments
Monitor for AVN

Time Critical

Hip dislocation is a TIME EMERGENCY. AVN risk increases dramatically after 6 hours. Reduce in ED if possible. Do NOT delay for elaborate imaging.

Surgical Technique

Smith-Petersen (Anterior) Approach

Preferred for posterior dislocations - protects MFCA

Positioning:

Supine on radiolucent table
Affected hip slightly externally rotated
C-arm available

Approach:

Interval between sartorius and tensor fascia lata
Develop interval to expose hip capsule
Identify ascending branch of lateral femoral circumflex
T-capsulotomy for exposure

Exposure:

Excellent visualization of femoral head
Direct access to anterior/superior head
Can see fragment and reduce anatomically

This approach protects the posterior blood supply.

Complications

Avascular Necrosis (AVN)

Risk Factors:

Dislocation time (most important)
Multiple reduction attempts
Pipkin type (III highest)
Severity of initial injury
Age (higher in older patients)

Incidence by Type:

Pipkin Type	AVN Rate
Type I	10-15%
Type II	15-25%
Type III	40-60%
Type IV	20-30%

Time-Dependent Risk:

Under 6 hours: 10-15%
6-12 hours: 20-40%
Over 12 hours: 50%+

Management of AVN:

Conservative initially if asymptomatic
Core decompression for early stages
Total hip arthroplasty for advanced disease
Young patients: consider joint preservation

Post-Traumatic Arthritis

Incidence: 20-50% at 10 years

Contributing Factors:

Residual articular incongruity
Cartilage damage at injury
AVN progression
Retained loose bodies

Management:

Activity modification
NSAIDs
Intra-articular injections
Total hip arthroplasty for end-stage

Heterotopic Ossification

Risk Factors:

Delayed surgery
Extensive soft tissue trauma
Male gender
Head injury

Prevention:

Indomethacin 75mg daily x 6 weeks
Single-dose radiation (700 cGy)
Low-dose radiation for high risk

Sciatic Nerve Injury

Incidence: 10-20% with posterior dislocation

Prognosis:

Most recover after reduction
Peroneal division worse than tibial
EMG at 3-4 weeks if no recovery

Recurrent Dislocation

Rare
Usually due to malreduced posterior wall
May need revision fixation

Postoperative Care

Immediate Postoperative (0-2 weeks)

Day of Surgery:

Abduction pillow or wedge
DVT prophylaxis (enoxaparin)
Pain management
Hip precautions if needed

First 2 Weeks:

Wound checks
Protected weight-bearing (toe-touch)
Gentle ROM exercises
DVT prophylaxis continued

Early mobilization reduces DVT risk.

Outcomes and Prognosis

Overall Outcomes

Outcomes by Pipkin Type

Pipkin Type	Good/Excellent Result	AVN Rate	Prognosis
Type I	80-90%	10-15%	Best
Type II	70-80%	15-25%	Moderate
Type III	40-50%	40-60%	Poor
Type IV	50-60%	20-30%	Variable

Prognostic Factors

Favorable Factors

Reduction under 6 hours. Pipkin I with small fragment. Anatomic reduction achieved. Young patient. No associated fractures.

Poor Prognostic Factors

Delayed reduction over 12 hours. Pipkin III pattern. Non-anatomic reduction. Multiple reduction attempts. Associated neck fracture.

Long-Term Results

Post-Traumatic Arthritis:

Develops in 20-50% at 10 years
Related to articular incongruity
Cartilage damage at time of injury
May progress despite good initial result

Return to Function:

Most patients return to daily activities
High-impact activities often limited
Athletes may have difficulty returning to sport
Occupational modifications may be needed

Evidence Base

Time to Reduction and AVN

III

Hougaard K, Thomsen PB • Clinical Orthopaedics and Related Research (1987)

Key Findings:

Dislocations reduced within 6 hours had 10% AVN rate compared to 58% when reduced after 6 hours

Clinical Implication: URGENT reduction within 6 hours is critical to minimize AVN risk

Surgical Approach Selection

Swiontkowski MF et al. • Journal of Orthopaedic Trauma (1997)

Key Findings:

Anterior approach for femoral head fractures after posterior dislocation preserved remaining blood supply and achieved 85% good/excellent results

Clinical Implication: Use anterior approach for ORIF after posterior dislocation

Pipkin III Outcomes

Marchetti ME et al. • Clinical Orthopaedics (1996)

Key Findings:

Pipkin III fractures had 48% AVN rate and 52% poor outcomes. Early arthroplasty in elderly showed better functional results

Clinical Implication: Consider primary arthroplasty for Pipkin III in elderly patients

Fragment Excision vs ORIF

III

Chen Z et al. • Injury (2011)

Key Findings:

ORIF of large Pipkin I fragments (over 20% head) showed better outcomes than excision, while small fragment excision was equivalent

Clinical Implication: Fix large fragments even if below fovea; excise small fragments

CT for Surgical Planning

III

Tabuenca J, Truan JR • Journal of Bone and Joint Surgery British (2000)

Key Findings:

CT scan after reduction changed surgical plan in 35% of femoral head fractures and identified occult loose bodies in 20%

Clinical Implication: Post-reduction CT is mandatory for surgical planning

Viva Scenarios

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: Posterior Hip Dislocation

EXAMINER

"A 32-year-old male involved in a high-speed MVA presents with his right leg shortened, flexed, and internally rotated. AP pelvis shows posterior hip dislocation. What is your management?"

EXCEPTIONAL ANSWER

Key Discussion Points:

Time to reduction is critical - target under 6 hours
Document sciatic nerve function BEFORE reduction
Closed reduction technique: Allis or Bigelow maneuver
General anesthesia preferred for muscle relaxation
If closed reduction fails, emergent open reduction
Post-reduction CT is MANDATORY
AVN risk increases dramatically after 6 hours
Assess for associated acetabular and femoral neck fractures
Kocher-Langenbeck approach for irreducible posterior dislocation

KEY POINTS TO SCORE

Reduce within 6 hours to minimize AVN risk

Document sciatic nerve function BEFORE reduction

Post-reduction CT is MANDATORY

Closed reduction: Allis or Bigelow maneuver

COMMON TRAPS

✗Delaying reduction for elaborate imaging

✗Not documenting pre-reduction nerve status

✗Forgetting post-reduction CT

LIKELY FOLLOW-UPS

"What if closed reduction fails?"

"What is the AVN rate if reduced after 12 hours?"

"How do you perform the Allis maneuver?"

VIVA SCENARIOChallenging

Scenario 2: Pipkin Classification

EXAMINER

"After reduction of a posterior hip dislocation, CT shows a femoral head fracture with a fragment involving 35% of the head."

EXCEPTIONAL ANSWER

Key Discussion Points:

Type I: Below fovea (inferior) - non-weight-bearing
Type II: Above fovea (superior) - weight-bearing, requires ORIF
Type III: I or II + femoral neck fracture - very high AVN risk
Type IV: I or II + acetabular fracture - complex management
Small Type I: excise fragment and loose bodies
Large Type I (over 20%): consider ORIF
Type II: ORIF with countersunk screws mandatory
Type III elderly: total hip arthroplasty
Type III young: fix neck urgently + address head
Type IV: staged posterior (acetabulum) + anterior (head)

KEY POINTS TO SCORE

Fovea is KEY landmark - above = weight-bearing

Type I small: excise; Type I large: ORIF

Type II always requires ORIF

Type III elderly: consider THA

COMMON TRAPS

✗Not knowing Type III has highest AVN risk (40-60%)

✗Missing the fovea as the critical landmark

✗Treating all Type I the same regardless of size

LIKELY FOLLOW-UPS

"What size Type I fragment warrants ORIF?"

"What approach for Pipkin II after posterior dislocation?"

"Why is Type III prognosis so poor?"

VIVA SCENARIOChallenging

Scenario 3: Pipkin II ORIF

EXAMINER

"A CT after reduction of a posterior hip dislocation shows a Pipkin II fracture - the fragment involves 30% of the femoral head above the fovea. No associated neck or acetabular fracture."

EXCEPTIONAL ANSWER

Key Discussion Points:

Anterior approach for posterior dislocation - protects MFCA
Smith-Petersen interval (sartorius/TFL)
T-capsulotomy for exposure
Reduce fragment anatomically
Fixation: countersunk Herbert screws or buried mini-fragment screws
Hardware must NOT protrude above cartilage surface
Remove all loose bodies
Confirm reduction with fluoroscopy
Post-op: protected weight-bearing 6-8 weeks
Monitor for AVN with serial radiographs

KEY POINTS TO SCORE

Use ANTERIOR approach for posterior dislocation (protects MFCA)

Smith-Petersen interval

Countersunk hardware (Herbert screws)

All hardware BELOW cartilage surface

COMMON TRAPS

✗Using posterior approach after posterior dislocation (damages MFCA further)

✗Hardware proud above cartilage

✗Leaving loose bodies in joint

LIKELY FOLLOW-UPS

"Why anterior approach for posterior dislocation?"

"What is the blood supply to the femoral head?"

"What is the AVN rate for Pipkin II?"

MCQ Practice Points

Classification Question

Q: What is the key anatomical landmark in the Pipkin classification?

A: The fovea capitis. Type I = below fovea (non-weight-bearing), Type II = above fovea (weight-bearing). The fovea determines whether fixation is mandatory.

Time Question

Q: What is the target time for reduction of a traumatic hip dislocation?

A: Under 6 hours. AVN risk is 10-15% if reduced within 6 hours, rising to over 50% if delayed beyond 12 hours.

Approach Question

Q: Which surgical approach is preferred for ORIF of a femoral head fracture after posterior hip dislocation?

A: Anterior (Smith-Petersen) approach. This protects the already-compromised posterior blood supply (MFCA) from further damage.

Blood Supply Question

Q: What is the primary blood supply to the femoral head?

A: Medial femoral circumflex artery (MFCA) provides 80% of blood supply via retinacular vessels. It courses posteriorly and is at risk with posterior dislocation.

Management Question

Q: How should a Pipkin III fracture be managed in an elderly patient?

A: Total hip arthroplasty. The combination of femoral head and neck fracture has very high AVN rates (40-60%). In elderly patients, arthroplasty provides better functional outcomes.

Australian Context

In Australian major trauma centres, femoral head fractures are managed according to RACS trauma guidelines with emphasis on emergent reduction within 6 hours. General anaesthesia is preferred for controlled reduction with adequate muscle relaxation. All major trauma centres have CT available for post-reduction assessment.

Hip arthroplasty procedures for Pipkin III injuries in elderly patients are covered under Medicare. Rehabilitation services are available through the public system with private health insurance providing additional coverage for elective revision procedures.

Australian trauma registries contribute to ongoing research on outcomes following femoral head fractures, with data showing results comparable to international series when time to reduction is optimized.

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