Femoroacetabular Impingement

DefinitionHip CAM CT 1

 

Aberrant morphology involving the proximal femur and acetabulum

- usually between the femoral neck and the acetabular rim

- during terminal motion of the hip

 

Can cause pain secondary to labral and chondral lesions

- may lead to early OA

 

Aetiology

 

Childhood conditions

- Perthes

- DDH

- SUFE

 

Post trauma

- prior femoral neck fracture

 

Acetabular retroversion

- posteriorly orientated acetabular opening

- relative prominence of anterior rim

- crossing of anterior and posterior walls on the AP radiograph

 

Acetabular Crossover Sign

 

Previous periacetabular osteotomy

 

Coxa

- profunda (deep socket)

- breva

- magna

- vara

 

Protrusio

 

Types

 

Cam

Pincer

Mixed

 

Cam impingement 

 

Between head and acetabulum 

 

Abnormal femoral head morphology

- often with flexion

- damage to anterior labrum and shearing of cartilage (carpet lesions)

 

Usually young men

 

CAM lesion x-rayHip Cam LesionHip CT Anterior Cam Lesion

 

Pincer impingement 

 

Between neck and acetabulum

 

Hip Pincer Impingement

 

Due to overcoverage of femoral head

- profunda, protrusio

- acetabular retroversion / relative anterior rim overcoverage

 

Damage to anterior labrum

 

Epidemiology

 

Young active males

- CAM impingement

 

Middle aged athletic women

- pincer impingement

 

History

 

Groin pain

- with rest

- with activity

 

Pain with flexion

 

Clicking from labral tear

 

Examination

 

Typically limited ROM

 

AP impingement 

- IR / flexion /  adduction

- most common

 

Posteroinferior impingement

- full extension and external rotation

 

X-ray

 

True AP

- coccyx and symphysis pubis within 1-2cm of each other 

- for assesment of retroversion / crossover sign

- bony prominence junction anterolateral head and neck

- ossification of labrum

- acetabular spurs

 

Hip Cam Lesion Xray

 

Lateral 

- shows CAM

 

CT reconstruction

 

Very good for bony morphology

 

Case 1

 

CAM Lesion CT

 

Case 2

 

Hip Cam CT SagittalHip CT Cam 3DHip Cam CT 3D 2HIp Cam CT 3D 3

 

MRA

 

Labral lesions

 

Hip MRI Labral Tear CoronalHip CAM Anterior Labral Degenerative TearHip MRI Labral Lesion

 

Femoral head morphology / Alpha angle

 

T1 axial MRI

- circle drawn on circumference of femoral head

- line from centre to where head extends beyond circle

- line drawn to centre of femoral neck at its narrowest

- angle > 55o may be indicative of CAM

 

Hip MRI Anterior CAMHip CAM Alpha Angle

 

Beta angle

 

Distance between pathological head-neck junction and acetabular rim

- hip in 90o flexion

 

Management

 

Non Operative

 

Activity modification

Stretching

Usually problem does not resolve

 

Operative

 

Options

 

Open femoral head arthoplasty with surgical dislocation

Hip arthroscopy

 

Open femoral head arthoplasty

 

A.  Surgical dislocation of femoral head

 

Ganz Osteotomy

- preservation of blood supply

- deep branch of medial circumflex artery most important

- runs posterior to obturator externus

- emerges at superior border of quadratus femoris

- over short external rotators

- then retinacular vessels up anterosuperior neck

 

Approach

- must preserve short external rotators

- trochanteric osteotomy

- greater trochanter slid anteriorly

- has abductors and vas lateralis attached

- capsule divided in lazy S

- preserving capsule over anterosuperior neck 

- reflected subperiosteally off neck (like banana skin)

- dividing lig teres and dislocating hip

 

B.  Femoral head osteoplasty

- allow flexion of 120o

- rotation of 40o

 

3.  Acetabular debridement 

- debridement acetabular chondral flaps

- osteotomy of the acetabular rim (up to 1cm)

- reattachment / debridement of labral lesions

 

Arthroscopy 

 

Indications

- debridement of labral tears

- femoral head osteoplasty

 

Technique

 

Position

- patient supine

- foot IR full initially, leg extended

- traction applied

 

Hip Arthroscopy Portal Insertion II

 

Anterolateral viewing portal

- hip distracted

- under II vision

- guide wire in place

- dilators, insert cannula

 

Anterior working portal

- triangulate, using II

- anterior labral and CAM resection

 

Hip Arthroscopy Anterior Portal

 

Posterior working portal

- accessory for labrum and rim

 

Assess Cartilage

 

Hip Arthroscopy Chondral DamageHip Arthroscopy Carpet Lesion

 

Assess for Labral Tears

 

Hip Arthroscopy Degenerative Labral Tear From CAM lesionHip scope normal acetabular Labrum

 

Labral resection

- with long resector

 

Hip Arthroscopy Initial ViewHip Arthroscopy Post Labral Resection

 

Acetabular rim resection

- if necessary

- long burr

- difficult to know extent of resection required

- check on II

 

CAM resection

- flex hip, ER

- T capsulotomy to expose CAM lesion

- performed with long thin scapel

- burr resection of CAM lesion

- again, under II guidance

- put hip through range to ensure adequate debridement

- T capsulotomy exposes CAM well

- isolated reports of hip dislocation

 

Hip Arthroscopy Labral and Rim ResectionHip Arthroscopy CAM Lesion ExposedHip Arthroscopy CAM resection

 

FAI Cam Resection 1FAI Cam Resection 2FAI Cam Resection 3

 

Results

 

Labrum

 

Larson et al Arthroscopy 2009

- retrospective comparison of labral debridement v fixation in CAM / Pincer

- significantly improved hip scores in repair grou

- 67% G/E in debridement

- 90% G/E in fixation

 

Athletes with CAM

 

Singh et al Arthroscopy 2010

- 27 Australian Rules Playes

- treatment of chondral lesions / labral lesions / majority with CAM lesions

- high level of satisfaction and 26/27 returned to high level sport

 

OA

 

Byrd et al Arthroscopy 2009

- 10 year follow up

- 80% good results if no OA

- 7/8 with OA had THR at mean of 6 years