summary Adult Dysplasia of the Hip is a disorder of abnormal development of the hip joint resulting in a shallow acetabulum with lack of anterior and lateral coverage. Diagnosis is made with plain radiographs of the hip joint. Treatment typically involves periacetabular osteotomies for those with concentrically reduced hips with congruous joint space and total hip arthroplasty for those presenting with end stage osteoarthritis. Epidemiology Incidence US: 3-5% estimated that 10% of all THA are performed as a result of dysplasia Demographics females > males 2-4x relative risk increase Risk factors breech presentation, female sex, primiparity, and family history Etiology Pathophysiology abnormal movement of the femoral head within the acetabulum due to both osseous and soft tissue abnormalities leads to overload of the acetabular rim leading to secodnary OA Associated conditions increased femoral anteversion, coxa valga, head-neck junction deformitites, femoral head asphericity, hypoplasia of the femoral intramedullary canal, posterior displacement of the greater trochanter Anatomy Acetabulum normal anteversion 15°, abduction 45° Proximal femur femoral head center of the femoral head should be at level of the greater trochanter proximal femur normal femoral neck anteversion: 15° relative to the femoral condyles normal neck shaft angle: 125° Classification Crowe Classfication Grade Proximal displacement Femoral head subluxation I <10% vertical height of pelvis Proximal migration of head neck junction from inter-teardrop line <50% of femoral head vertical diameter II 10-15% 50-75% III 15-20% 75-100% IV > 20% >100% Hartofilakidis Classification Dysplasia (Type A) Femoral head within acetabulum despite some subluxation. Segmental deficiency of the superior wall. Inadequate depth of true acetabulum. Low dislocation (Type B) Femoral head creates a false acetabulum superior to the true acetabulum. There is a complete absence of the superior wall. Inadequate depth of true acetabulum. High dislocation (Type C) Femoral head is completely uncovered by the true acetabulum and has migrated superiorly and posteriorly. There is a complete deficiency of the acetabulum and excessive anteversion of the true acetabulum. Presentation Symptoms hip or groin pain with insidious onset exacerbating activitis include hip flexion or external rotation in weight bearing stance lateral hip pain and a limp or Trendelenburg gait may occur with abductor fatigue Physical exam insepction evaluation of gait; abductor fatigue or Trendelnburg sign overall ligamentous laxity; Beighton score motion increased internal rotation with the hip in flexion login to view 1 more bullet provocative tests anterior apprehension sign login to view 2 more bullets prone external rotation tests login to view 1 more bullet Imaging Radiographs recommended views AP lateral false-profile view findings asphericity of the femoral head coxa valga (increase neck-shaft angle) narrow femoral canal measurements lateral center-edge angle (LCEA) of Wiberg login to view 5 more bullets Tonnis angle login to view 5 more bullets anterior center-edge angle of Lequesne login to view 6 more bullets Femoro-Epiphyseal Acetabular Roof (FEAR) index login to view 3 more bullets CT indications preoperative planning should only be ordered by treating surgeon findings adequate assessment of acetabular and proximal femoral osseous morphology including excessive anteversion or retroversion login to view 2 more bullets Prevention Identification and prevention of infantile developmental dysplasia (DDH) Pavlik harness, closed and open reductions, spica casting, proximal femoral osteotomies Treatment Nonoperative supportive measures role of long-term nonsurgical management in symptomatic dysplasia is limited given premature progression of secondary OA Operative hip arthroscopy indications login to view 3 more bullets outcomes login to view 2 more bullets periacetabular osteotomy (PAO) indications login to view 4 more bullets advantages login to view 5 more bullets outcomes login to view 2 more bullets salvage pelvic osteotomy (Chiari, Shelf) indications login to view 2 more bullets outcomes login to view 2 more bullets hip resurfacing indications login to view 1 more bullet outcomes login to view 3 more bullets total hip arthroplasty (THA) indications login to view 2 more bullets outcomes login to view 7 more bullets Techniques Supportive measures technique weight loss, NSAIDs, activity modification, intra-articular injections Hip arthroscopy technique should not be performed in isolation as it does not treat underlying pathologic cause hip arthroscopy performed concomitantly with PAO to address labral pathology or evaluate for chondral injuries login to view 2 more bullets Periacetabular osteotomy (PAO) (Ganz, Bernese) approach modified Smith-Petersen technique involves osteotomies in the pubis, ilium, and ischium near the acetabulum allows significant three-dimensional correction of the acetabulum importantly, the osteotomies avoid disruption to the posterior column login to view 1 more bullet complications hip arthroplasty performed after PAO may lead to increased incidence of a retroverted acetabular cup Salvage Osteotomies Chiari Osteotomy technique login to view 2 more bullets complications login to view 1 more bullet Shelf Osteotomy approach login to view 1 more bullet technique login to view 3 more bullets Hip Resurfacing technique posterior approach with release from the piriformis to the gluteus maximus tendon login to view 1 more bullet unable to address limb length complications postoperative femoral neck fracture Total Hip Arthroplasty approach anterior, lateral or posterior based approaches may be used technique trochanteric osteotomy may be needed to improve visualization, especially in Crowe type III or IV dysplastics goal is to place the acetabular component in the true acetabulum to restore normal hip center of rotation and biomechanics login to view 1 more bullet components may need to be medialized or used with augments to gain adequate coverage and stability of the acetabulum login to view 1 more bullet a high hip center can be used to gain adequate bony stability, but is less ideal biomechanically modular femoral components allow for correction of rotational deformities complications increased risk of loosening with a high hip center increased risk of neurovascular injury and infection Complications Sciatic nerve palsies 10 times increased incidence of sciatic nerve palsy (5-15%) lengthening of greater than 4 cm can lead to sciatic nerve palsy that will present clinically as a foot drop Nonunion 29% nonunion with greater trochanter osteotomy subtrochanteric osteotomy and trochanter advancement lowers nonunion rate Hip Dislocation increased risks of hip dislocation after arthroplasty (5-10%), especially when high hip center is used Component loosening placement of the acetabular component in a high hip position associated with increased risk of loosening Periprosthetic femur fx Infection Prognosis 48% of THA in patients < 50-years-old are a result of dysplasia