Review Paediatric imaging

Ultrasonography in developmental dysplasia of the hip: A review of current clinical strategies and recommendations for revision of practice

Konstantinos Chlapoutakis1, Stylianos Kolovos2, Carolina Casini3

1Clinical Radiologist, Heraklion, Crete, Greece

2 Orthopaedic Surgeon, Larissa, Thessaly, Greece

3 Paediatrician, Ospedale Sant’ Andrea, Roma, Italy

Submission: 18/9/2016 | Acceptance: 25/2/2017

Developmental dysplasia of the hip is a broad term covering a wide spectrum of hip joint disorders, rang­ing from maturation deficits to severe dysplasia or dis­location. Published prevalence of the disorder ranges from 0.25% to 2.5% or even more in certain geograph­ic areas. Risk factors do exist and include female gen­der, white race, positive family history and mechan­ical restriction during or after birth. Low sensitivity and specificity of clinical examination promoted the development of several sonographic techniques for early diagnosis. Among the above-mentioned tech­niques, Graf’s technique, supported by extended literature and epidemiological data, offers an ana­tomically based description of pathology and effec­tive monitoring of treatment. Universal sonographic screening early in life is strongly recommended and initiation of treatment as early as possible is manda­tory for an optimal outcome.

Key words

Congenital; dislocation; Hip joint/dysplasia; Ultrasonography/diagnosis; Infant

Corresponding Author, Guarantor

Konstantinos Chlapoutakis, Clinical Radiologist, 9 Arkoleontos Str., Heraklion 71202, Crete, Greece


Fig. 1. Barlow and Ortolani maneuvers consist part of the standard infant examination performed by the pediatrician in early infancy. Barlow maneuver aims to identify unstable hips and consists of the application of a posterior force with the hip adduct­ed, which produces a posterior dislocation of the joint (with a palpable clunk). On the contrary, Ortolani maneuver consists of the application of anterior traction on an abducted / flexed dislocated hip, which reduces (with a palpable clunk) the dislocation

US offers us the opportunity to image the non-os­sific(-ied) parts of the hip joint very early in life. Carti­laginous structures (femoral head, cartilaginous roof, labrum), joint capsule and the muscles are adequately ex­amined with US, both in an anatomic and dynamic (when needed) way (Fig. 2).

Fig. 2. Cartilaginous structures (femoral head, cartilaginous roof, labrum), joint capsule and the muscles are adequately ex­amined with ultrasound (blue colour). FH: Femoral Head, FM: Femoral Metaphysis, L: Labrum, HC: Hyaline Cartilage, PP: Prox­imal Perichondrium, GM: Gluteal Muscles / Intermuscular Septa

At the same time, integrity and ade­quacy of the acetabular bony roof is assessed, both quali­tatively and quantitatively, and the position of the femoral head within the joint socket is documented. Several dif­ferent sonographic techniques have been developed and clinically assessed, a few of which are still in clinical prac­tice [23-27]. X-ray nowadays has a historical role in DDH screening and is preserved mainly for late presenting cas­es and treatment monitoring when US is no more techni­cally feasible [28]. CT and MRI still have a role when exam­ining the consequences of neglected or maltreated cases of DDH or when planning hip surgery [29].

The era of hip US began in 1980 when Reinhard Graf pub­lished the original paper about hip US for the diagno­sis of congenital dislocation of the hip in infants [23]. Over the next years, several publications suggested modifications or advances of this technique, or differ­ent techniques altogether. Traditionally, examination techniques have been categorised according to their im­aging focus (acetabular morphology, femoral head cov­erage) or their technical approach (static vs. dynamic). It is beyond the scope of this paper to describe every dif­ferent sonographic technique that is or has been used or proposed. It is our aim to emphasise the main advan­tages and disadvantages of the most widely used ones and then conclude with evidence based conclusions / recommendations.

Measuring the femoral head coverage (FHC), from a tech­nical point of view, seems to be the easiest and more re­producible way to assess a hip joint. On a standard coro­nal hip scan the percentage of the femoral head covered by the acetabular roof is calculated as demonstrated on the figure (Fig. 3).

Fig. 3. Assessment of Femoral Head Coverage (FHC). FHC (per­centage) is calculated in a standard coronal scan by diving ac­etabular width (distance a, measured from the medial part of the acetabulum to a line parallel to the iliac bone) by the fem­oral head diameter (distance b, measured between lines par­allel to the iliac line, the first from the medial part of the ace­tabulum as in distance a and the second from the outer part of the cartilaginous femoral head). FHC is calculated by the for­mula a/b x 100%

There are however certain method­ological problems that significantly reduce the value of the technique, which was originally proposed by Morin (USA) and Terjesen (Norway) [25, 26] and is still utilised in Northern Europe. Ovoid shape (and not spherical) of the femoral head [30], alongside with failure to define a standard plane for measurement, makes the meth­od vulnerable to rotational distortions. Furthermore, the classification scheme utilised for assessment has a wide “gray” zone (FHC<50% may be abnormal) and an unsound reasoning behind it. As a result, it is of limited use, restricted in certain geographic areas [31].

Fig. 6. Defining the Standard Plane of examination. For this purpose, a standardised approach is utilised (lower limb-plane-la­brum) to define the correct scanning position and plane. The yellow triangle represents the labrum, the straight line the correct scan­ning plane and the yellow circle the lower limb of the os ilium

Fig. 7a (above), 7b (below). Provided that a correct image at a standard scanning plane has been acquired, morphological classification into four main categories (I to IV) is then performed. This comprises the first step of the interpretation of the scan

Fig. 8. Dramatic drop of surgical intervention rate in young children documented in Austria between 1991 and 2004 (used with per­mission: Graf R. The use of ultrasonography in developmental dysplasia of the hip. Acta Orthop Traumatol Turc 2007; 41 Suppl 1: 6-13)

The authors declared no conflicts of interest.


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