Developmental dysplasia of the hip

Orthopedic course
overview
Introduction
Epidemiology
Etiology and pathogenesis
Pathology
Clinical Features and tests
Imaging
Treatment
Complications
Questions
References

1. Developmental Dysplasia of the Hip ( DDH ) Diaa Mohammad Srahin 5 th year Medical Student Al-Quds University Orthopedic course Dr. Ziyad Al- Zeer

2. Overview Introduction Epidemiology Etiology and pathogenesis Pathology Clinical Features and tests Imaging Treatment Complications Questions References

3. Introduction Definition Of DDH Dysplasia of the hip that develop during fetal life or in infancy . The old name was ‘‘congenital dysplasia of the hip (CDH).’’ The name has changed to indicate that not all cases are present at birth and that some cases can develop later on during infancy and childhood.

4. DDH comprises a spectrum of disorders including : Acetabular dysplasia  a shallow or underdeveloped acetabulum. Subluxation Dislocation Teratologic hip dislocated in utero and irreducible on neonatal exam associated with neuromuscular conditions and genetic disorders , commonly seen with arthrogryposis , myelomeningocele .

5. Epidemiology Incidence most common orthopedic disorder in newborns. dysplasia is 1:100 dislocation is 1:1000 Location most common in left hips in females bilateral in 20% Risk factors first born female (6:1 over males) breech family history oligohydramnios

6. Etiology and pathogenesis Genetic factors must be important, for DDH tends to run in families and even in entire populations. Two heritable features which could predispose to hip instability are : generalized joint laxity (a dominant trait). shallow acetabula (a polygenic trait which is seen mainly in girls and their mothers). .

7. Hormonal changes Hormonal changes in late pregnancy may aggravate ligamentous laxity in the infant. This could account for the rarity of hip instability in premature babies. Intrauterine malposition especially a breech position with extended legs , would favor dislocation . Normal  womb position. Breech  womb position.

8. Postnatal factors play a part in maintaining any tendency to instability. This may account for the unusually high incidence of DDH in Inuit and Sami peoples, who swaddle their babies and carry them with hips and knees fully extended; compare the rarity of DDH in African peoples, who carry their babies astride their backs with hips abducted . Tight car seats prevent legs from spreading apart . Wider car seats provide room for legs to be apart, putting the hips in a better position. Baby carriers that force the baby’s legs to stay together may contribute to hip dysplasia. Baby carriers should support the thigh and allow the legs to spread to keep the hip in a stable position.

9. Pathology The acetabulum is unusually shallow (shaped like a saucer instead of a cup ). The femoral head slides out posteriorly and then rides upwards “ Superiolaterally “. The capsule is stretched and the ligamentum teres becomes elongated and hypertrophied. The acetabular labrum and its capsular edge may be pushed into the socket by the dislocated femoral head; this firocartilaginous limbus may obstruct any attempt at closed reduction of the femoral head. Maturation of the acetabulum and femoral epiphysis is retarded and the femoral neck is unduly anteverted .

10. Clinical features The ideal, is to diagnose every case at birth. For this reason, every newborn child should be examined for signs of hip instability. Where there is a family history of congenital instability, and with breech presentations or signs of other congenital abnormalities, extra care is taken and the infant may have to be examined more than once. Even then some cases are missed. In the neonate, there are several ways of testing for instability e.g. Ortolani’s test , Barlow’s test.

11. Mainstay of physical diagnosis is palpable hip subluxation dislocation on exam  Barlow   dislocates a  dislocatable  hip by adduction and depression of the flexed femur Ortolani     reduces a dislocated hip by elevation and abduction of the flexed femur Galeazzi  (Allis)    apparent limb length discrepancy due to a unilateral dislocated hip with hip and knee flexed at 90 degrees femur appears shortened on dislocated side Hip clicks are nonspecific findings. Barlow and Ortolani a rarely positive after 3 months of age because of soft-tissue contractures about the hip

12. Ortolani’s test In Ortolani’s test, the baby’s thighs are held with the thumbs medially and the fingers resting on the greater trochanters; the hips are flexed to 90 degrees and gently abducted. Normally there is smooth abduction to almost 90 degrees . In congenital dislocation the movement is usually impeded, but if pressure is applied to the greater trochanter there is a soft ‘clunk’ as the dislocation reduces. If abduction stops halfway and there is no jerk of entry, there may be an irreducible dislocation.

13. Barlow’s test Barlow’s test is easily performed by adducting the hip while applying light pressure on the knee, directing the force posteriorly.  If the hip is dislocatable - that is, if the hip can be popped out of socket with this maneuver - the test is considered positive. The   Ortolani maneuver is then used, to confirm the positive finding (i.e., that the hip actually dislocated).

14. Every hip with signs of instability – however slight – should be examined by ultrasonography . This shows the shape of the cartilaginous socket and the position of the femoral head. Late features An observant mother may spot asymmetry, a clicking hip, or difficulty in applying the napkin (diaper) because of limited abduction . With unilateral dislocation the skin creases look asymmetrical and the leg is slightly short ( Galeazzi’s sign ) and externally rotated; With bilateral dislocation there is an abnormally wide perineal gap . Abduction is decreased . Contrary to popular belief, late walking is not a marked feature; nevertheless, in children who do not walk by 18 months dislocation must be excluded . Likewise , a limp or Trendelenburg gait, or a waddling gait could be a sign of missed dislocation

15. Asymmetrical thigh creases Limited abduction Galeazzi’s sign waddling gait

16. If the patient stands on the healthy side, his abductor muscles will support his weight, the contralateral side will not tilt down . While if the patient stands on the affected side, because of his weak abductor , the pelvis will drop on the other side

17. Imaging Because the proximal femur at birth is all cartilaginous , radiographs cannot be used to detect the position of the head of the femur in relation to the acetabulum . Ultrasound is used to assess the position of the head of the femur until the age of 4–6 months when the ossific center of the proximal femur starts to develop . Dynamic ultrasound: Using ultrasound to assess the stability of the head of the femur in the acetabulum during various movement of the hip joint. After the ossific center is formed (around 4–6 months), the ultrasound waves cannot penetrate the ossific center. Plain radiographs are used to assess the hip joint.

18. Dynamic ultrasound. Assessment of the hip position by ultrasound during various positions. a To the left with hip adduction, the femoral head ( dotted circle) lies outside a line along the pelvic bone (dotted line). b With hip abduction , partial reduction occurs.

19. Interpretation of the ultrasound of the hip Alpha angle It represents the bony acetabulum . Normal is more than 55 degree . This indicates good bony coverage of the head of the femur (deep acetabulum ). Beta angle It represents the cartilaginous acetabulum . Beta angle should be less than 50 degree. This indicate that the head of the femur is not subluxated ( B ig B eta B ad).

20. Ultrasound assessment of the hip joint. Alpha angle is the angle between the ileum (thick line) and a line extending from the triradiate (arrow ) to the edge of the acetabulum (thin line). Beta angle is the angle between the ilium (thick line) and line extending from the edge of the bony acetabulum to the edge of the labrum (dotted linea )

21. Diagnosis of missed DDH after the age of six months Limited abduction of the affected hip . Limb length discrepancy (LLD) (‘‘positive Galeazzi sign ’’). Limping (for unilateral cases) and waddling gait (for bilateral cases). Pain is NEVER a symptom of UNTREATED DDH until the development of hip arthritis (usually by the 4th decade of life ).

22. Radiographs of missed DDH The femoral head is ossified. Femoral head is out of the acetabulum [in the upper lateral quadrant formed by crossing of Hilgenreiner line and Perkins’ line . Broken Shenton’s line (imaginary line between the obturator foramen and lower border of the neck of femur ). Increased acetabular index ( normal acetabular index should be less than 24 degree at age of 24 months). Delayed ossification of the femoral head (the affected side is smaller than the normal side ).

23. Anteroposterior pelvis radiographs of 14-month-old girl with left hip DDH. The radiograph shows the ossific center on the left side (arrow ) smaller than the right side and lying in the upper lateral quadrant of the crossing two lines ( Hilgenreiner and Perkins ) (the normal right side lies in the lower medial quadrant). The Shenton’s l ine (curved line across the obturator foramen and lower border of the neck) is intact on the right side ( continuos curved line) and broken in the left side (curved dotted line). The dislocated side shows increased acetabular index (the angle between the Hilgenreiner line and line from the triradiate to the lateral part of the acetabulum ) compared to the right side

24. Treatment Nonoperative abduction splinting/bracing ( Pavlik  harness)        indications DDH < 6 months of age and reducible hip is a dynamic splint that requires normal muscle function for successful Outcomes. contraindicated in patients with teratologic hip dislocations, spina bifida or spasticity. outcomes overall Pavlik harness has success rate of 90 %. dependent upon age at initiation of treatment and time spent in the harness. abandon pavlik harness treatment if not successful after 3-4 weeks  If pavlik harness fails, convert to semi-rigid abduction brace with weekly ultrasounds for an addition 3-4 weeks before considering further intervention.   

25. closed reduction and  spica  casting  indications DDH in 6 - 18 months of age failure of Pavlik treatment arthrography performed at time of reduction medial dye pool >7mm associated with poor outcomes and osteonecrosis Pavlik  harness spica  cast

26. Operative open reduction and  spica  casting  indications DDH in patient >18 months of age failure of closed reduction  open reduction and femoral osteotomy  indications DDH > 2 yr with residual hip dysplasia  anatomic changes on femoral side (e.g., femoral anteversion , coxa valga ) femoral head should be congruently reduced with satisfactory ROM, and reasonable femoral sphericity best in younger children (< 4 yr ) after 4 yr , pelvic osteotomies are utilized

27. open reduction and pelvic osteotomy  Indications DDH > 2 yr with residual hip dysplasia  severe dysplasia accompanied by significant radiographic changes on the acetabular side (increased acetabular index)  used more commonly in older children (> 4 yr ) decreased potential for acetabular remodeling as child ages

28. Complications Osteonecrosis Delayed diagnosis Recurrence approximately 10% with appropriate treatment requires radiographic follow-up until skeletal maturity Transient femoral nerve palsy

29. Questions

30. Evaluation of a 4 week infant who has a hip click reveals a positive ortolani sign. Treatment should include: A. traction, closed reduction, and spica casting. B. triple diapers and reassessment in 1 month C. an AP pelvis x-ray at age 4 months D. Fitting of a Pavlik harness and reassessment in 2 weeks E. an US of the hip, fitting of a Pavlik , and reevaulation in 3 months. The Answer is D

31. A healthy 5-mo-old infant w/ DDH of the L hip has been treated in a Pavlik for 3 months. Exam shows limited ABD and a Galeazzi sign. Management should consist of: A. an arthrogram and closed reduction B. a change of the Pavlik to a Frejka pillow C. no further Rx until the child is 6mos D. Adjustment of the Pavlik and continuation of Rx E. open reduction through a medial approach and spica The answer is A

32. This is an x-ray of a 9-month-old infant who has intoeing . Exam of the hips show ABD of the Left hip to 75 degrees and the Right to 90 degrees. Both the Ortolani and Barlow signs are negative. Management should include: A. observation B. application of a Pavlik harness C. closed reduction of the Left hip D. open reductino of the Left hip E. open reduction of the left hip with innominate osteotomy

33. This is an x-ray of a 9-month-old infant who has intoeing . Exam of the hips show ABD of the Left hip to 75 degrees and the Right to 90 degrees. Both the Ortolani and Barlow signs are negative. Management should include: A. observation B. application of a Pavlik harness C. closed reduction of the Left hip D. open reductino of the Left hip E. open reduction of the left hip with innominate osteotomy The Answer is C

34. The x-ray shows a AP pelvis of a 6yo girl who presents with a limp and intermittent pain in the right groin. Management should include: A. A varus derotational osteotomy of the right femur B. open reduction and adductor tenotomy C. open reduction with femoral and pelvic osteotomies D. PT for muscle strengthening and ROM exercises E. longitudinal traction, closed reduction, and adductor tenotomy

35. The x-ray shows a AP pelvis of a 6yo girl who presents with a limp and intermittent pain in the right groin. Management should include: A. A varus derotational osteotomy of the right femur B. open reduction and adductor tenotomy C. open reduction with femoral and pelvic osteotomies D. PT for muscle strengthening and ROM exercises E. longitudinal traction, closed reduction, and adductor tenotomy The Answer is C

36. References Apley’s System of Orthopaedics and Fractures 9 th ed . by Louis Solomon, David Warwick, Selvadurai Nayagam . Pediatric Orthopedics: A Handbook for Primary Care Physicians. By Amr Abdelgawad , Osama Naga. https:// www.orthobullets.com