CASE 13287 Published on 07.04.2016
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Preoperative digital planning in adult developmental dysplasia of the hip

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Zeljko L Stepanovic1, Ana Rankovic2

(1) MD, PhD, Orthopaedic Surgeon;
(2) MD, Radiologist
Clinical Center Kragujevac,
Clinic for Orthopedic and Trauma Surgery;
Department of Radiology;
Zmaj Jovina 30
34000 Kragujevac;
Email:stepakg@gmail.com
Connected authors
Patient

64 years, female

Categories
Area of Interest Musculoskeletal system ; Imaging Technique Digital radiography, CT-High Resolution
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Clinical History
A 64-year-old woman was investigated for surgical treatment of developmental hip dysplasia. Her complaint was bilateral hip pain and restriction in daily activities for the past two years. She had two deliveries and managed to compensate her disabilities before. The patient has short stature, hyperlordosis and equal lower limb length.
Imaging Findings
Digital pelvic radiography (Fig. 1) revealed the Crowe type IV bilateral developmental dysplasia of the hip (DDH). [1] Radiographic imaging of the pelvis enabled virtual preoperative templating (Fig. 2), although preoperative planning needed more sophisticated imaging techniques. Multiplanar CT of the pelvis was performed to further investigate bone stock and perform morphometric measurements of bony landmarks of the pelvis and femora (Fig. 3) MDCT scan of the pelvis provided accurate position of dislocated femoral heads relative to real acetabuli (Fig. 4). Essentially, 3D-CT scan showed bilateral high unsupported posterior hip dislocation, with exact relation between deformed femoral heads, iliac wings and true acetabuli. On both iliac wings two neoacetabuli were found, indicating an evolution of hip dysplasia (Fig. 5).
Discussion
Developmental dysplasia of the hip (DDH) may range from hardly detectable acetabular dysplasia to immensely malformed and highly dislocated hip.
The incidence of established developmental hip dislocation ranges between 1.5 and 20 per 1000 newborns. [2] Children whose parents had DDH are 10 times more prone to express DDH compared to their peers whose parents did not. [3]
Adolescent and adult DDH exists in two forms, those that were previously treated, and some that were left untreated, leading to premature hip osteoarthritis and groin pain. Almost 80% of total hip replacements (THR) performed in women and 15% in men are related to some degree to hip dysplasia. [4] Due to inefficient abductor musculature these patients limp or have a waddling (Trendelenburg) gait. [5]
Radiographic findings of DDH include shallow, mostly retroverted acetabulum and insufficient coverage of the femoral head, an increased femoral anteversion with shortened femoral neck and coxa valga. [6] Crowe classification is widely accepted in addressing THR for DDH, although frequently it is not a helpful tool for pre-operative planning. [1, 7] It is based on the extent of proximal migration of the femoral head addressing the ratio between the vertical distance of interteardrop line and the femoral head-neck junction (b) and the pelvic height (a); (type I < 50% subluxation or proximal dislocation <0.10; type II >50% and 74% subluxation or proximal dislocation 0.10 to 0.15, type III > 75% and 99% subluxation or proximal dislocation 0.16 to 0.20, type IV > 100% or complete dislocation >0.20). [1, 7] Eftekhar and Hartofilakidis proposed a radiologic classification depending on the grade of femoral head dislocation. The severity of DDH was divided into three and four stages, ranging from dysplasia to complete dislocation. [8, 9] CT studies confirmed a wide variety of deformities within the same Crowe grade. [10] MDCT provides valuable information regarding the type of deficiency and degree of acetabular dysplasia and may be used for 3D computerized preoperative planning. [11, 12] Preoperative digital planning has proven useful in joint replacement surgery allowing surgeons to choose an appropriate implant from the database [13, 14]
The patient underwent one stage modular total hip arthroplasty of the right hip with subtrochanteric shortening and realignment osteotomy according to preoperative digital templating (Fig.6a, b).
Take home message:
Digital preoperative planning in addressing total hip replacement in DDH improves the procedure's precision and its outcome, ensures the required implants are available, minimizing the costs and complications.
Differential Diagnosis List
Developmental dysplasia of the hip (luxatio coxae congenita bilateralis)
none
Final Diagnosis
Developmental dysplasia of the hip (luxatio coxae congenita bilateralis)
Case information
URL: https://www.eurorad.org/case/13287
DOI: 10.1594/EURORAD/CASE.13287
ISSN: 1563-4086
License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

Plain X-ray of the pelvis

Plain X-ray of the pelvis
Radiographic findings of Crowe IV bilateral DDH. True acetabuli are shallow and inferior to irregular, highly displaced femoral heads. In DDH B/A ratio varies from &lt; 0.10 in Crowe type I to &gt; 0.20 in Crowe type IV. [1]
Figure 2

Preoperative radiographic images of the pelvic region with virtual planning

Preoperative radiographic images of the pelvic region with virtual planning
Digital radiographs of the pelvis demonstrating preoperative templating procedure and calculated transverse subtrochanteric shortening osteotomy using digital planning software.
Figure 3

MDCT scan of the pelvis – posterolateral view

MDCT scan of the pelvis – posterolateral view
3D reconstruction CT scan showed two shallow neoacetabuli on both iliac wings, indicating an evolution of hip dysplasia from low supported hip luxation to high unsupported hip luxation [8].
Figure 4

Axial CT images of the pelvis

Axial CT images of the pelvis
Axial CT of the pelvis demonstrated hypoplastic acetabuli with moderate increase in the right acetabular anteversion (21º) and normal acetabular anteversion (15º) of the left acetabulum. An angle &lt;15° is indicative of acetabular retroversion. [10]
Figure 5

Postoperative images of the pelvic region

Postoperative images of the pelvic region
Postoperative radiographs of the pelvis, showing surgical placement of the modular total hip prosthesis with plate osteosynthesis of the subtrochanteric osteotomy. An implant position was analyzed by digital planning software.
Figure 6

MDCT scan of the pelvis - PA view

MDCT scan of the pelvis - PA view
MDCT scan showed bilateral high unsupported hip dislocation with exact relation between posteriorly displaced, deformed femoral heads, iliac wings and true acetabuli.