Ahealthy thirty-five-year-old woman slipped and fell while mopping a wet
floor, causing forced abduction of both lower extremities and external
rotation of the right leg. She presented to the emergency room with severe
pain in the right hip, which was fixed in abduction and external rotation. The
neurovascular status of the extremity was normal. Radiographs revealed
anterior hip dislocation without evidence of fracture or dysplasia
(center-edge angle, 28°) (Fig.
1). The hip was reduced with closed manipulation within two hours
after the injury, with the patient under general anesthesia. The patient was
subsequently managed with bed rest without traction for one week. She then
resumed normal walking and underwent a course of physical therapy.
Eight months later, while bearing full weight on the right lower extremity
and rotating the trunk to the left, the patient sustained another anterior hip
dislocation. Closed reduction was accomplished within four hours, and the
patient was placed on bed rest for two weeks. Imaging studies, including
conventional and false-profile hip radiographs, magnetic resonance images, and
computerized tomographic arthrograms, showed only a redundancy of the anterior
capsule and a normal equatorial edge
angle2 of 22°
(Fig. 2). There were no
abnormalities of the labrum, femoral head, or acetabulum. Connective-tissue
disorders were ruled out after a complete rheumatologic evaluation.
Two months after the second dislocation, the patient twisted while in bed
and sustained a third dislocation. Operative repair was recommended. An
anterolateral approach was used to expose the anterior capsule and the
proximal part of the femur. The capsule was redundant but was not torn. It was
imbricated with use of an inverted T overlapping capsulorrhaphy until maximal
tension was achieved. Next, an intertrochanteric derotational osteotomy was
performed just proximal to the lesser trochanter with 25° of external
rotation of the distal fragment, and the site was fixed with a 95° dynamic
condylar screw (Synthes, Oberdorf, Switzerland). Postoperative management
consisted of partial weight-bearing for three months and progressive
physiotherapy. Three months after surgery, range-of-motion testing revealed
that the right hip had a 20° loss of internal rotation and a 15°
increase of external rotation compared with the left hip. Union of the
osteotomy site was observed at three months
(Fig. 3). Two years after
surgery, the dynamic condylar screw was removed to relieve local tenderness
over the lateral aspect of the greater trochanter.
At the time of the five-year follow-up, the patient was pain-free and was
still working in her pre-injury occupation as a janitor. At that time, the
ranges of motion of the right and left hips were 125° and 140° of
flexion, 20° and 45° of internal rotation, and 60° and 45° of
external rotation, respectively. The patient had no further dislocation or
subluxation of the right hip. The Harris hip
score3 was 99
points. Radiographs showed no arthritic changes in the hip
(Fig. 4).
Because of the inherent stability of the hip joint, traumatic anterior
dislocation is uncommon. Thompson and Epstein reported that only 9% of hip
dislocations occur
anteriorly4. In our
search of the literature, we only found seven reported cases of recurrent
anterior hip dislocation in adults, including four in the English-language
literature5-8.
It is important to identify any predisposing factors for recurrent
dislocation, such as connective-tissue disorders, dysplasia of the femoral
head or acetabular rim, fractures, neural deficits, or labral or capsular
ruptures. Such factors may influence the likelihood of recurrent dislocation
and its preferred treatment. Our patient had no predisposing factors for
recurrent dislocation.
There is little information in the literature regarding the treatment of
recurrent anterior hip dislocation, and all recommendations have been based on
case reports with short durations of follow-up. Of the four cases reported in
the English-language literature, one was treated nonoperatively with a
hip-spica cast for eight weeks after a second
dislocation5. Dall
et al. described the use of a 45° external rotation femoral osteotomy
combined with an iliopsoas transfer to the greater
trochanter6.
Shigenobu et al. reported on the use of a capsulorrhaphy and rotational
acetabular osteotomy to treat acetabular
dysplasia7.
We elected to externally rotate the femur only 25°, in contrast with
the 45° described by Dall et
al.6, in order to
decrease the final rotational deformity. We then supplemented the osteotomy
with a capsulorrhaphy to treat the computerized tomographic finding of a
redundant capsule.
In this rare case, this combination of procedures was effective for
avoiding both new dislocations and the development of arthritic changes in the
hip at the time of the five-year follow-up. We could not determine whether the
capsulorrhaphy or the rotational osteotomy was primarily responsible for the
successful result.