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 pelvis radiograph

 

Previous periacetabular osteotomy

 

Coxa

- profunda (deep socket)

- breva

- magna

- vara

 

Protrusio

 

Types

 

Cam

Pincer

Mixed - CAM and Pincer

 

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 CT Anterior Cam Lesion

 

Pincer impingement 

 

Between neck and acetabulum

 

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

 

Lateral 

- shows CAM

 

CT reconstruction

 

Very good for bony morphology of the CAM

 

Case 1

 

CAM Lesion CT

 

Case 2

 

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

 

Case 3: Subspine Impingement

 

Subspine Impingement 1Subspine impingement 2

 

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

Core strengthening

 

Indications

- pain < 1 year

- OA

 

Hip Arthroscopy Anterior PortalHip Pincer Impingement

Hip Cam LesionHip Arthroscopy Chondral Damage

 

 

Operative

 

Options

 

Open femoral head arthoplasty with surgical dislocation - now rearely done

 

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 / repair of labral tears

- femoral head osteoplasty

 

Technique

 

Position

- patient supine

- foot IR full initially, leg extended

- traction applied

 

Hip Arthroscopy Portal Insertion II

 

Portals

 

Proximal anterolateral viewing portal (PALA)

- hip distracted

- under II vision

- guide wire in place

- dilators, insert cannula

 

Mid Anterior working portal

- triangulate, using II

- anterior labral and CAM resection

 

Posterior working portal

- accessory for labrum and rim

- rarely used

- can be used to remove loose bodies

 

Distal anterolateral Working Portal (DALA)

- between midanterior and PALA
- useful for labral repair

 

Labral Repair

 

Assess for Labral Tears

 

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

Hip Arthroscopy Carpet Lesion

 

Labral resection

- with long resector

- rarely performed now

- if labrum irreparable or ossified

 

Hip Arthroscopy Initial ViewHip Arthroscopy Post Labral Resection

 

Acetabular rim resection / Acetabuloplasty

- 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

 

RCT Surgery v Nonoperative

 

Griffin Lancet 2018

- 348 patients randomized to surgery v personalized hip therapy

- 1 year follow up, significant improvements in hip arthroscopy group

 

Labrum Repair v Debridement

 

Larson et al Arthroscopy 2009

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

- significantly improved hip scores in repair group

- 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