Dega

Dega Osteotomy for the Correction of Acetabular

Dysplasia of the Hip: A Radiographic Review

of 21 Cases

Ahmed Al-Ghamdi, MD, FRCSC,* Juan Sebastian Rendon, MD,w Fareed Al-Faya, MD, FRCSC,*

Neil Saran, MD, MSc, FRCSC,*wz Thierry Benaroch,MD, MSc, FRCSC,*wz and

Reggie C. Hamdy, MD, MSc, FRCSC*wz

Background: The Dega osteotomy is a versatile procedure that is

widely used to treat neuromuscular hip dysplasia. There is a

paucity of the English language literature on its use in acetabular

dysplasia seen in developmental dysplasia of the hip (DDH).

Methods: A retrospective radiographic and chart review was

performed for all patients diagnosed with DDH who underwent

a modified Dega osteotomy between March 1995 and December

2008 at the Shriners Hospital for Children or the Montreal

Children’s Hospital (Montre´ al, Canada) by 2 orthopaedic

surgeons. Radiographic parameters were measured at the

preoperative, immediate postoperative, and final follow-up time

points. These parameters included the acetabular index, center

edge angle, Reimer’s extrusion index, Shenton line, and grading

by the Severin classification.

Results: A total of 20 patients (21 hips), of which 18 were female,

underwent a modified Dega osteotomy at an average age of 55.6

months (range, 20 to 100 mo). Of the 21 hips (1 bilateral and 19

single cases), 9 hips involved the right side and 12 hips involved

the left side. Before surgery, 9 patients had a subluxated hip, 7

patients had a dislocated hip, and 5 patients had a dysplastic

hip. Ten hips underwent concomitant procedures including 10

open reductions with capsulorraphy. The acetabular index

improved from 37 degrees (SD 8) preoperatively to 19 degrees

(SD 8) on the date of last visit. The center edge angle improved

from 2 (SD 17) to 25 degrees (SD 12).

Conclusions: The results of this study demonstrate that the

modified Dega osteotomy produces near-normal lateral coverage

parameters in children with DDH.

Level of Evidence: Therapeutic study, clinical case series: level IV.

Key Words: congenital dislocation, pelvic osteotomy, acetabulum,

open reduction

(J Pediatr Orthop 2012;32:113–120)

Acetabular dysplasia seen in developmental dysplasia

of the hip (DDH) is characterized by typical

morphologic features. Salter’s 1 simple yet elegant porcine

experiments showed that acetabular dysplasia was secondary

to a malpositioning of the hip and was characterized

by a maloriented and hypoplastic acetabulum. Additional

associated characteristics have been described by Wedge2

as “combinations of maldirection, marginal erosion,

torsion, hypoplasia (localized or global deficiency), abnormal

shape, and decreased surface area of the acetabulum

available for bearing articular cartilage to articulate with the

frequently misshapen femoral head.”

Various surgical techniques have been described to

treat acetabular dysplasia. Although redirectional innominate

osteotomies such as the Salter innominate

osteotomy,3 Sutherland double innominate osteotomy,4

and Steel triple5 and To¨ nnis et al triple6 osteotomies

reorient the hip, acetabuloplasty procedures such as the

Pemberton,7 Dega,8 and San Diego9 are felt to address

both the malorientation and the hypoplasia by

“reshaping” and improving the volume of the acetabulum.

10,11 The San Diego (modified Dega) osteotomy has

been shown to be a useful versatile osteotomy in which

coverage can be directed to match the specific deficiency.9

Although large case series on the utility of the Dega and

modified Dega in treating spastic hip dysplasia exist,9,12

there are limited publications in the English literature

regarding the use of this technique on patients diagnosed

with DDH.12–14

This study describes and analyzes the radiographic

outcome of 21 cases diagnosed with DDH and treated

with a modified Dega osteotomy. The principal aim was

to assess the impact of this surgical technique on the

acetabular index (AI) at final follow-up. Secondary aims

included assessing the impact of the surgical technique on

the center edge angle (CEA),15 AI of Sharp,16 Reimer’s

extrusion index,17 and the continuity of the Shenton

line,18 and grading the results of the treatment at final

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