Femoracetabular Impingement: In Theory and In Practice Tom Bradbury, MD Assistant Professor Emory Orthopaedics and Spine Center March 11, 2011

A delay in non-arthroplasty treatment options for the hip……. Hip pain in the young patient not as common Hip is “deeper” than knee, shoulder Hip is more constrained Hip capsule is very robust Precarious blood supply to the femoral head limited an interest in surgical exposure…a fear of iatrogenic avascular necrosis

What is the etiology of osteoarthritis of the hip?

“ 90% of adult cases of osteoarthritis are the result of a morphologic developmental abnormality ”…..not a intrinsic problem with articular cartilage -Murray, Harris, 1986

“Structural Pediatric Residuals” Developmental Dysplasia Slipped Capital Femoral Epiphysis Legg-Calve-Perthes Disease Multiple Epiphyseal Dysplasia Spondyloepiphyseal Dysplasia

Radiography of Hips with FAI Normal joint space Subtle morphologic aberrations “Normal” to the untrained eye

1991: “cervico-acetabular impingement” secondary to femoral neck malunion 1999: “pincer” type impingement after periacetabular osteotomy for dysplasia

Evolution of an Understanding Reinhold Ganz Anatomy Perfusion Osteotomy Dislocation Impingement

Ganz’s Observation “Overcorrection” of hip dysplasia with periacetabular osteotomy “Iatrogenic retroversion” Hip pain with flexion (Pincer type anterior impingement)

Normal Cam Pincer

Hip “History” Arthrosis Insidious onset Constant Ache Walking on level ground Nocturnal symptoms Pre-arthrosis Sudden onset Sharp, intermittent pain Pain primarily with torsional activities Pain with prolonged flexion

Hip Exam: Gait “Antalgic” – shortened stance phase secondary to pain “Trendelenberg” – contralateral hip drops during stance phase secondary to abductor dysfunction “Abductor Lurch” – torso sways over affected leg during stance phase secondary to abductor dysfunction

Hip Specific Tests Trendelenberg Test Log Roll Passive External Rotation in Extension “C” test Thomas Test Stinchfield Test Ober’s Test Anterior Impingement Test (FADDIR) Posterior Impingement Test DEXTRIT (aka McCarthy)- Dynamic External Rotatory Impingement Test DIRIT- Dynamic Internal Rotatory Impingement Test Scour Test Ober Abduction internal rotation FABER

Hypermobility Beighton’s Criteria for hypermobility (3 of 5) – Thumb to forearm – SF extension > 90 – Elbow hyperextension > 10 – Knee hyperextension > 10 – Palms to floor

Findings Drehmann’s Sign- Obligate abduction and external rotation with forward flexion of the hip Coxa Saltans Interna- Iliopsoas tendon over the ileopectineal eminence Coxa Saltans Externa- Iliotibial band over greater trochanter

Imaging of the Young Hip Start with plain films: 1.Supine AP Pelvis Centered Low with Legs internally rotated 15 degrees 2.Cross table lateral of the hip with the leg 15 internally rotated 15 degrees 3.Dunn 45 of the Hip

Technique: AP – Supine with legs 15 degrees internally rotated – Film-focus distance: 1.2 meters – Point of center: midway between ASIS & Pubis Cross Table Lateral – Leg 15 degrees internally rotated – Perpendicular to long axis of femoral neck

Technique Dunn 45 – Hip flexed 45 degree, abducted 20, in neutral rotation

“ Diagnosis can only be made from a technically sound and properly positioned AP radiograph of the pelvis” -Ganz

“Normal”

LEGS EXTERNALLY ROTATED

ROTATION?

MALROTATION

TILT? Distance from tip of coccyx to superior edge of symphasis? 1 – 3 cm Siebenrock et al. From Sacrococcygeal junction: Male = 47.3 mm Female = 32.3 mm

POINT OF CENTER? ASIS PUBIS

Normal Landmarks

Ilioischial Line Iliopectineal Line

Sourcil

Posterior Wall Anterior Wall

Physeal Scar

Hip Imaging Lingo Acetabular Depth Acetabular Extrusion Acetabular Inclination Femoral Head Coverage Acetabular Version Head Sphericity Head-Neck Offset Congruency

Acetabular Depth The relationship of the true floor of the acetabulum to the ilioischial line Extrusion Index

AE E/A+E Normal = 25% Extrusion Index

Cox Profunda -Floor of fossa medial to ilioischial line - Extrusion Index 0

Cox Profunda -Floor of fossa medial to ilioischial line - Extrusion Index 0

Acetabular Protrusio -Femoral head to ilioischial line -Negative Extrusion Index

Acetabular Inclination (Tonnis angle) Horizontal line between center of femoral heads Line connected the medial and lateral edge of the sourcil

Acetabular Inclination (Tonnis angle) Negative angle = overcoverage/pincer

Acetabular Inclination (Tonnis angle) High positive angle = dysplasia

Lateral Center Edge Angle (of Wiberg) Normal =

Sphericity Measured by containment of physeal scar with circle of femoral head

Acetabular Version Relationship of walls to one another Ischial spine within pelvis Relationship of posterior wall to center of femoral head

Dysplasia Low CE angle (< 25) Elevation of acetabular inclination Elevation of Extrusion index

Retroverted Acetabulum Cross over sign Ischial Spine within pelvis

False profile view AnteriorPosterior

Aspherical head Physeal Scar extends beyond the circle

Femoral Cam Alpha angle > 50

Dunn 45