Hip Dysplasia

Introduction[edit | edit source]

Hip dysplasia refers to the abnormalities relating to size, shape, orientation or organization of either the femoral head or the acetabulum, or both.[1]It is most often the term given to infantile hip instability, shallowness of the hip socket or hip dislocation.[2]. Developmental dysplasia of the Hip (DDH) generally refers to hip dysplasia of the infant or child. [2]. Acetabular dysplasia itself refers to an immature, shallow acetabulum. Hip dysplasia diagnosed during adolesence or adulthood is often called acetabular dysplasia because it's shallowness does not fully support the femoral head.[2]

Diagram of Hip joint structures' position

The image on the right is a schematic depiction of hip joint structures' positions in hip dysplasia: A - Normal, B - Dysplasia, C - Subluxation, D - Luxation

Presentation of hip dysplasia varies from minor hip instability to frank dislocation. The exact etiology is still elusive. Multifactorial in nature, a combination of genetic, environmental, and mechanical factors plays a role.[3]

Other terms used for hip dysplasia (depending on severity and time of occurrence) include:

  • Developmental Dislocation of the Hip
  • Hip Dislocation
  • Congenital Dislocation of the hip.
    • It must be noted that Congenital Dislocation is not often used as this term refers to a condition present at birth which is associated with a proliferation or absence of normal tissue. In the case of DDH the hip joint is normal apart from the instability.

Early diagnosis and management of hip dysplasia will prevent long term complications e.g. persistent dislocation, limp and early hip osteoarthritis.[3]

Clinically Relevant Anatomy[edit | edit source]

The Hip joint is a classical ball-and-socket joint. It meets the four characteristics of a synovial or diarthrodial joint: it has a joint cavity, joint surfaces are covered with articular cartilage, it has a synovial membrane producing synovial fluid, and it is surrounded by a ligamentous capsule.[4]

  1. Acetabulum and femoral head development are intimately related. Development of the acetabular cavity is determined by the presence of a concentrically reduced femoral head. When the femoral head is not in contact with the acetabulum, the latter does not develop adequately and it is flat-shaped[5].
  2. A deep concentric position of the femoral head in the acetabulum is necessary for a normal development of the hip. When the bone structures of the hip are fully grown, we can speak of a ball and socket joint between the rounded head of the femur and the cup-like acetabulum of the femur.[6]
  3. The proximal femur is completely cartilaginous at birth[5].

Pathology[edit | edit source]

Hip dysplasia in an adult

The formation of the hip joint is highly dependent on the dynamic relationship between femur and acetabulum. Any interference with proper contact between these two in utero or infancy leads to DDH.

Maligned contact for a prolonged period leads to chronic changes like hypertrophy of capsule, ligament teres, the formation of thickened acetabular edge (neolimbus), which further prevents the contact, and prevents the relocation of the femoral head[3]. The very cellular hyaline cartilage allows the femoral head to glide into acetabulum generating the palpable clunk known as the Ortolani sign.[7]

DDH alters hip biomechanics, overloading the articular cartilage and leading to early osteoarthritis. DDH is the main cause of total hip replacement in young people (about 21% to 29%)[5].

Epidemiology[edit | edit source]

Neonate.jpeg

The reported incidence of developmental dysplasia of the hip varies between 1.5 and 20 per 1000 births, with the majority (60-80%) of abnormal hips resolving spontaneously within 2-8 weeks (so-called immature hip).

The incidence varies from 0.06 in Africans to 76.1 per 1000 in Native Americans due to the combination of genetics and swaddling.[7]

Etiology[edit | edit source]

The following are the risk factors for DDH:

  • Female gender (M: F ratio ~1:8) The increased incidence is probably due to ligamentous laxity from maternal hormones.[3]
  • Firstborn baby. The incidence of DDH is 10 times more in new borns with breech malposition
  • Family history/ genetic factors. eg Certain ethnic populations (Native Americans and Sami people). Some studies suggest it is linked with the hormone relaxine and /or it has something to do with chromosone 13
    • Genetic factors related to abnormal development include instances where musculoskeletal forces develop with unbalanced forces on the hips, ultimately leading to dislocation. Dislocation which occurs early on in development is generally the most severe. Here the acetabulum is shallow, with a false acetabulum developing. The femoral head, while remaining well formed is smaller than normal, as is the greater trochanter. The neck of the femur is also shorter than normal. This is generally referred to as teatrogenic DDH.[8]
  • Breech presentation. The legs of the foetus are pressed inside the uterus leading to hip dislocation if the ligaments are lax. The caput femoris tends to be pushed out of the acetabulum.
  • Any physical limitation (eg oligohydramnios, twins) in utero can contribute to DDH. It also increases the risk of other abnormalities like Metatarsus adducts, congenital muscular torticollis, and congenital knee dislocation.
  • Spina bifida[7]
  • Swaddling in the adducted and extended position. Explains the increased incidence in specific populations including American Indians, Japanese and Turkish infants[3].
  • Structural abnormalities eg shallow acetabulum, a flat or irregular caput femoris, a femoral or acetabular anteversion, and a decreased head offset or perpendicular distance from the center of the femoral head to the axis of the femoral shaft.[9][10][11]

It is, however, important to note that etiology is most often multifactorial and not simply due to one factor or another.

Characteristics/ Clinical presentation[edit | edit source]

Clinical features vary for mild hip instability, limited abduction in the infant, less mobility or flexibility on one side, limping or toe walking, and osteoarthritis in the adult.[3]

Developmental dysplasia of the hip is usually suspected in the early neonatal period due to the widespread adoption of clinical examination (including the Ortolani test, Barlow manoeuvres, and Galeazzi sign).[7]

Natural history of DDH[edit | edit source]

In 88% of infants born with hip instabilty, hips become stable by 2 months of age. Those that do not however, progress to subluxation or complete dislocation.[8]

Hips dislocated at birth do not often reduce spontaneously.[8]

With hip dysplasia without subluxation degenarative joint disease doesn't usually occur before the end of the 4th decade. and has a mean incidence at the age of 57 years.[8]

In hips showing subluxation, arthritic changes usually occur and with severity associated with degree of subluxation. With severe subluxation, symptoms can begin as early as after skeletal maturity.[8]

In complete dislocation without treatment the following is observed:

  • Soft tissue changes, particularly that of muscles and ligaments to improve stability of the joint. This in turn limits reducibility of the joint.
  • Pain is not common in young children, but increases as the patient matures. Thigh pain and pain in the lower back are common complaints following extensive walking.
  • In older patients, knee pain can develop from repeated excessive valgus force on the knees.[8]

Diagnosis and Diagnostic procedures[edit | edit source]

The goal is to provide an optimal environment for the growth of the femoral head and acetabulum. So a high index of suspicion and routine surveillance is needed to detect DDH and prevent complications.

Firstly a thorough history needs to be done.[8]

  • Family history
  • Interuterine position
  • number of pregnancies
  • Oligohydramnius

It is also important to consider the presence of other deformities which are often associated with DDH. These include:[8]

  • Torticolus
  • Calcaneo-valgus feet
  • Metatarsus adductus

Diagnosis under 3 months[edit | edit source]

The following are clinical signs which can be used in diagnosing DDH.[8]

  1. Asymmetrical skin folds. Normal inguinal folds stop before the anal apeture. Abnormal skin folds extend posteriorly and laterally beyond the anal apeture. Other assymetrical skin folds to note are gluteal and on the thighs.
  2. Excessive looseness of hip and knee flexion is a probable sign of DDH.
  3. Klisic line: Drawn from tip of the greater trochanter to the ASIS, then continued superioirly and medially towards the ambilicus. In a normally developed hip joint, this line will bisect the ambilicus, but in an abnormal developed hip, the line passes below the ambilicus.
  4. Adduction contracture: This only usually develops 2-3 months after birth.
  5. Ortolani and Barlow tests positive.

If Ortolani and Barlow tests are positive, ultrasonography is recommended. Ultrasound is the modality of choice in children under the age of 6 months as it is during this time the femoral head is predominantly cartilaginous and therefore cannot be picked up on X-ray. Once there is a significant ossification has occurred (over 6 months of age) then an x-ray examination can be performed.[8]

Diagnosis between 4 months and walking age (about 12 months)[edit | edit source]

The following are clinical signs which can be used in diagnosing DDH.[8]

  1. Contracture of the hip adductors, iliopsoas and hamstrings of the affected side.
  2. Skin fold asymmetries worsen.
  3. Flattening of the buttock. This is observed in prone and is more easily discerned with unilateral involvement.
  4. Greater trochanter height difference. Observed in supine, legs extended. Thumbs are placed on the ASIS and index fingers on the greater trochanters.
  5. Affected limb often postures in 15° -25° lateral rotation.
  6. Telescoping sign.
  7. Galeazzi sign

Diagnosis after 12 months of age[edit | edit source]

The following are clinical signs which can be used in diagnosing DDH.[8]

  1. With a subluxed hip, there may be a delayed Trendelenburg sign or limp.
  2. With complete dislocation there is usually a limp in stance phase of the affected side. This is seen as a contralateral downward tilt of the pelvis and the spine laterally deviating toward the dislocated side. Also known as Duchenne compensation of the Trendelenburg sign.
  3. In unilateral involvement, toe walking on the affected side or flexing of the contralateral knee is seen as a compensatory gait pattern.
  4. Vertical telescoping movement during gait may also be observed, due to the instability of the dislocated hip.
  5. Shortened leg length of the affected leg.
  6. Prominence of the greater trochanter.
  7. Buttocks broad and flat.
  8. Limitation of hip abduction and extension.
  9. Positive Trendelenburg sign if unilateral involvement, otherwise a waddling or duck gait will be observed in bilateral involvement.
  10. The perineal space will be widened and the distance between thighs increased.
  11. Anterior tilt of the pelvis and lumbar lordosis may also be observed.
  • Note: With acetabular dysplasia only, there may be no clinical signs.

[12]

Treatment/Management[edit | edit source]

All treatment efforts are based on obtaining a concentrically positioned femoral head into the acetabulum so the latter is stimulated to grow normally. Acetabular potential of correction diminishes dramatically after three to four years of age; therefore, early interventions are paramount to obtain the best results with less surgical aggression[5]. Various treatment modalities like abduction splinting, closed reduction, open reduction are available.

Double diapering is most likely harmless, but efficacy is close to zero.[3]

The treatment depends on the age of the patient and the degree of dysplasia.

  • Minor hip instability (Barlow positive, Ortalani negative) spontaneously recovers in 90% of cases in the first two weeks of life.
  • Continued surveillance by the primary care provider during infancy improves detection and early referral.
  • Pavlik harness corrects 95% of DDH if applied before six months.
  • Residual dysplasia occurs even after appropriate treatment, so annual follow up is required until skeletal maturity.
  • Without early treatment, the child may develop limp, leg length discrepancy, limited hip abduction, and in fact, DDH is the most common cause of early osteoarthritis in women under age 40.[3]

The higher the age at presentation, the worse the outcomes after intervention for DDH. By the age of eight years, it is thought that possible complications of treatment may lead to a poor outcome, no better than if DDH is left untreated[5]

Treatment under the age of 3 months[edit | edit source]

Baby wearing a Pavlik harness

Pavlik harness (placing the hips into flexion and gentle abduction. Generally 10-12 weeks. This is for hips which are unstable but reducible.[8][13]

Also a Frejka Pillow is used but is not indicated in all forms of hip dysplasia.

If the harness fails, surgical intervention - open or closed reduction as well as traction and/ or manipulation may be required.[8]

With persistent dysplasia operative management correcting boney dysplasia is needed.[8]

Note: Even with treatment of DDH, the following can still develop:

  • Maldirected acetabulum
  • Capacious acetabulum
  • Lateralised acetabulum
  • False acetabulum
  • Proximal femoral dysplasia

Therefore, follow-up is recommended until skeletal maturity.

Treatment from 4 months until walking age[edit | edit source]

With children who have a negative Ortolani sign i.e. does not reduce with the Ortolani sign, or if the femoral head is high-riding above the acetabulum or if soft tissues are contracted, traction may be used.[8]

Traction A form of treatment for Hip dysplasia

Traction is the application of a force to stretch certain parts of the body in a certain direction. This will soften the tissue around the caput femoris and will allow the caput femoris to move back in the acetabulum. Traction consists of pulleys, strings, weights, and a metal frame attached over or on the bed. Traction is most often used for approximately 10 to 14 days. The application of ice on the painful regions helps to numb pain and reduces the inflammation.[14]

Other forms of reduction of a dislocated hip includes closed reduction and spica cast treatment. In the case of casting, this is generally done for 1 month for each month of age at closed reduction, to a maximum of 6 months. The cast is usually changed every 6 weeks owing to the child outgrowing the cast.[8]

Treatment after walking age[edit | edit source]

Approach to treatments for children treated after the onset of walking remains controversial.[8]

Surgical interventions usually consider the level of the femoral head in relation to the acetabulum, presence of a well-formed false acetabulum and tissue contracture.[8]

Interventions are generally either closed reduction or open reduction.[8]


This is a video (3 minutes) re DHD from the mothers view of her neonatal girl.

[15]

Physiotherapy for DHD in Babies[edit | edit source]

Even though DHD is common and usually very well managed, it can be hard and overwhelming for new parents to deal with the dos and don’ts along with the other struggles of parenthood. With physiotherapy we can help the parents feel empowered and enable them to help their babies along the process of healing.

Although it is not standard practice for a paediatrician to refer to a physiotherapist but a visit to a physiotherapist after the diagnosis gives parents a better insight and can help with managing the condition at home specifically during the splint free time at home.

Research has shown that appropriate massage, stretching and strengthening can help with the recovery of the hip while the child is in the brace. All these treatments can be performed by the parents at home once perfected by a visit to the physiotherapist every month.

A baby can exercise and strengthen the hip muscles by using their developmental milestones to their advantage. A physiotherapist should do a thorough assessment of the baby, go through the scans, follow the recommendations by the paediatrician and make a plan that suits the baby according to their age[16].

eg a baby with hip dysplasia needs to be kept in a certain position to give their hip a mechanical advantage. So if it is a baby who is 6 months old, the physiotherapist takes advantage of their current milestones and trains the hip muscles on a number of surfaces keeping the hip position in mind and challenge the hip muscles. This also avoids the chances of delayed milestones that can happen in babies with serial and prolonged periods of casting.

Physiotherapy for older child/adult DHD[edit | edit source]

Hippotherapy.jpeg

Therapy is important to correct poor posture, muscle weakness, poor joint awareness, and associated tendon inflammation. Therapy can improve all these factors including the strength of hip extensors and external rotators, gait re-education, and improving body awareness. Strong muscles will act like shock absorbers and provide greater support for the hip.

If osteoarthritis of the hip is present see this connection for Physiotherapy

  • Exercise: Regular, low- or non-impact exercise such as swimming, aquatic therapy or cycling train strength and range of motion.
  • Weight loss: For those overweight can significantly reduce the stress on the hip and reduce pain.
  • Hippotherapy: A specialized therapy treatment strategy that uses a horse's movement to influence the patient/client in a various number of ways.[17] During hippotherapy, functional riding skills are not taught; the client sits on the horseback and physically accommodates to the three-dimensional movements of the horse's walk. Hippotherapy is shown to motivate the child to engage in therapy, maintain the child's willingness to participate and provide a playful environment while facilitating pain free movement.[18]

Helpful resources[edit | edit source]

The International Hip Dysplasia Institute - A site with information for caregivers and health care professionals.

References[edit | edit source]

  1. Storer SK, Skaggs DL. Developmental dysplasia of the hip. American Family Physician. 2006 Oct 15;74(8):1310-6.
  2. 2.0 2.1 2.2 International Hip Dysplasia Institute. Understanding Hip Dysplasia. Available from: https://hipdysplasia.org/developmental-dysplasia-of-the-hip/ (accessed 10/01/2023)
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Nandhagopal T, De Cicco FL. Developmental Dysplasia Of The Hip. StatPearls [Internet]. 2020 Oct 10. Available: https://www.ncbi.nlm.nih.gov/books/NBK563157/(accessed 11.10.2021)
  4. Byrd J. Gross anatomy. In: Byrd J, editor. Operative Hip Arthroscopy. 2nd ed. New York: Springer Science + Business Media, Inc; 2004.
  5. 5.0 5.1 5.2 5.3 5.4 Vaquero-Picado A, González-Morán G, Garay EG, Moraleda L. Developmental dysplasia of the hip: update of management. EFORT open reviews. 2019 Sep;4(9):548-56. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6771078/ (accessed 12.10.2021)
  6. American Academy of Pediatrics, Committee on Quality Improvement, Subcommittee on Developmental Dysplasia of the Hip, Clinical Practice Guideline : Early detection of developmental Dysplasia of the hip, Official Journal of the American Academy of Pediatrics Vol 105 No 4 April 2000, downloaded from pediatrics.applications.org at Swets Blackwell 30680247 on November 23, 2011. Level of evidence: 1 A
  7. 7.0 7.1 7.2 7.3 Radiopedia Developmental dysplasia of the hip Available: https://radiopaedia.org/articles/developmental-dysplasia-of-the-hip (accessed 11.10.2021)
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 Bowen JR, Kotzias-Neto A. Developmental dysplasia of the hip. Data Trace Pub.; 2006.
  9. John Crawford Adams, David L. Hamblem, Outline of Orthopaedics, Churcill Livingstone, 1995, twelfth edition, p. 292 – 301.
  10. John Crawford Adams, David L. Hamblem, Outline of Orthopaedics, Churcill Livingstone, 2001, thirteenth edition, p. 305 – 312.
  11. J.Maheshwari. Essential Orthopaedics. 6th edition. Jaypee Brothers Medical Publishers,2019
  12. Dr. Anisuddin Bhatti. Ortolani's Click & Barlow's Maneuver. Available from: http://www.youtube.com/watch?v=mv_kLqZSGdo [last accessed 04/05/13]
  13. Guille JT, Pizzutillo PD, MacEwen GD. Developmental dysplasia of the hip from birth to six months. JAAOS-Journal of the American Academy of Orthopaedic Surgeons. 2000 Jul 1;8(4):232-42.
  14. Enseki KR, Martin RL, Draovitch P, Kelly BT, Philippon MJ, Schenker ML. The hip joint: arthroscopic procedures and postoperative rehabilitation. Journal of Orthopaedic & Sports Physical Therapy. 2006 Jul;36(7):516-25.
  15. Childrens Hospital. Angela and hip dysplasia - Boston Children's Hospital. Available from: http://www.youtube.com/watch?v=bShtxYFdERQ [last accessed 04/05/13]
  16. Inner Strength Physiotherapy for hip dysplasia in babies: a way to empower parents to help their little humans. Available: https://www.innerstrengthbayside.com.au/physiotherapy-for-hip-dysplasia-in-babies-a-way-to-empower-parents-to-help-their-little-humans/(accessed 12.11.2021)
  17. Debuse D, Chandler C, Gibb C. An exploration of German and British physiotherapists' views on the effects of hippotherapy and their measurement. Physiotherapy theory and practice. 2005 Jan 1;21(4):219-42.
  18. Roy Aldridge PT, Farley Schweighart SP, Megan Easley SP. The effects of hippotherapy on motor performance and function in an individual with bilateral developmental dysplasia of the Hip (DDH). J Phys Ther. 2011; 2:54-63