Hip Dislocation

IncidencePosterior Hip Dislocation


Young men


Posterior / Anterior 9:1




High velocity injury

- head direction at impact decides direction of dislocation


Anterior Dislocation 


Externally rotated & abducted leg

- flexion = inferior dislocation

- extension = pubic dislocation


Posterior Dislocation


Axial compression of adducted leg

- more flexion causes pure dislocation without fracture




Inherently stable joint

- large head on smaller neck

- allows deep seating of femoral head

- acetabulum deepened by labrum

- capsule reinforced by ilio/pubo/ischio femoral ligaments


40% femoral head in contact with articular cartilage

10% in contact with labrum


Blood supply


Majority by deep branch of Medial Circumflex Femoral Artery

- minimal by medial epiphyseal artery via ligamentum teres

- little to non via LCFA



- arises medial aspect of profunda

- along posterior intertrochanteric crest extracapsular / back of femoral neck

- passes between iliopsoas and pectineus medially

- runs along inferior border of obturator externus, above adductor brevis

- deep to quadratus femoris

- emerges between quadratus and inferior gemellus

- runs over conjoint tendon (2 gemelli and obturator internus)

- then penetrates capsule between conjoint and piriformis

- runs along superior aspect of neck to femoral head


Transverse branch (to ischium) and ascending branch (to trochanteric fossa0

- arise anterior to quadratus


Must protect this deep branch MCFA in a posterior approach


With dislocation and capsular tears

- some ascending cervical branches stretched/kinked

- emergent reduction can improve blood flow to femoral head


Associated Injuries


50-95% have other injury


Acetabular fracture


Femoral head fracture / Pipkin fracture


Sciatic nerve 10% / posterior dislocation


Patella fracture




Femoral artery injury - anterior dislocation


Femoral shaft fracture

- reduce head via steinman pin in proximal fragment

- then IMN femur






1. Medial / Central

- really medial displacement with acetabular fracture


2. Anterior 

- pubic / obturator / perineal


3. Posterior


Posterior Hip Dislocation Lateral




Capsule & Ligamentum teres torn


Labral tears & muscular injuries also occur


Y / iliofemoral ligament often intact with posterior dislocation

- blocks reduction

- bony fragments also block reduction


Clinical Features / Xray


Posterior dislocation

- leg shortened, flexed, adducted & internally rotated 

- head small on xray


Posterior Hip Dislocation


Anterior dislocation 

- leg short and externally rotated

- head larger on xray


Check NV status / sciatic nerve


Hip fracture dislocation






Assess & manage life threatening injuries

- EMST / ATLS principles




1. Emergent reduction

- closed +/- open

- reduce risk AVN 



- < 6 hours 10%

- 20% - 50% if >24 hours


2.  Assess stability


Posterior wall fracture > 40%

- need ORIF for stability


Hip Dislocation Posterior Wall FractureHip Dislocation Posterior Wall Fracture


Posterior wall fracture < 40%

- can be unstable

- EUA after reduction to assess stability

- should be able to flex to 90o and some IR without instability


3. Screen for retained fragments


Compulsory CT

- xray will not detect fragments < 2mm


Hip Dislocation Loose Body


Remove / ORIF depending on size of fragment and location / Pipkin type


4. Reconstruct acetabulum if unstable or incongruent


Closed Reduction Posterior Dislocation




Full muscle paralysis on radiolucent table 

- supine

- assistant places downward pressure on ASIS

- operator up on bed grasping leg

- flex hip to 90o, flex knee to 90o



- ER head around acetabulum / axial traction or

- IR head around acetabulum / axial traction


Post reduction

- check concentric reduction on II

- check stability in flexion


Unstable reduction

- skeletal traction / femoral steinman pin


Post op


NV examination when patient awake

- ensure sciatic nerve working

- ensure hasn't become entrapped with reduction




Closed Reduction Anterior Dislocation



- as above

- traction in line with femur flexed

- internal rotation maneuver


Irreducible Dislocations



- 2-15%




1.  Capsule / Labrum / Ligamentum teres

2.  Muscle interposition

- anterior usually rectus / psoas

- posterior usually piriformis / G maximus

3. Bone fragment

4.  Muscle tone

- patient requires relaxant




Open reduction


Non-concentric Reduction


Esssential to obtain X-ray and CT after reduction



- head - teardrop distance must equal contralateral side



- only with CT can < 2mm fragments be seen


Pipkin Infrafoveal CT



- may be needed to see labral tears blocking reduction


Open reduction




1.  Irreducible dislocation


2.  Non-concentric reduction

- loose bodies / interposed tissue


3.  Post operative sciatic nerve palsy


4.  Unstable posterior acetabular fracture


5.  Associated NOF fracture


6.  ORIF Pipkin fracture




Usually from direction of dislocation

- preserve intact capsule

- preserve remaining blood supply

- i.e. with posterior dislocation the posterior capsule will be torn

- provides entry into joint


Posterior Approach


Aim to preserve intact anterior capsule and blood supply

- beware sciatic nerve

- divide piriformis and conjoint tendon away from insertion to preserve deep branch MCFA

- may need to extend posterior capsular rent

- allows direct visualisation of blocks to reduction

- blocks include G. max, piriformis, capsule, bony fragments

- may need to excise ligamentum teres

- explore acetabulum for loose bodies

- close capsule afterwards

- may need to excise L Teres


Other issues


Posterior acetabular fracture

- ORIF if > 40% or unstable


Pipkin fracture

- manage as per Femoral Head Fractures


Subcapital fracture

- Watson Jones / Smith Peterson approach

- supplementary lateral approach to insert fixation


Post Operative


NWB for 6/52


Bone scan re vascularity 



- °AVN = FWB

- AVN = consider bisphosphonates


Yue et al J Orthop Trauma 2001

- 5/54 low blood flow on early SPECT

- no correlation with AVN






Related to

- time to reduction <12/24

- velocity of injury

- open reduction vs closed (x4)

- direction (anterior < posterior)



- < 6/24 = 2-10%

- > 12/24 = 52%



- posterior 17%

- anterior 2%


Tends to be localised

- revascularisation occurs on reduction

- damage to lateral & medial epiphyseal artery

- metaphyseal blood supply remains

- occurs in first 18 months





- 15 - 20 %




- instability

- incongruous reduction

- cartilage damage at time of dislocation


Philippon et al Arthroscopy 2009

- hip arthroscopy post traumatic dislocation in 14 athletes

- all had chondral defects, 11 had loose fragments

- all patients had labral tears


Sciatic Nerve Palsy 


Posterior dislocation

- 8 - 19%

- more common after fracture / dislocation



- usually partial CPN

- usually resolves


Only explore if onset after MUA


Else observe


Instability < 1%


Myostitis Ossificans



- usually little functional problem