Congenital Dislocation of the Hip

For the great majority of children younger than 18 months of age with congenital dislocation of the hip (CDH), closed reduction has been the simplest and safest method of treatment. For the few children who have required open reduction after failure of closed methods, the choice operative approach has been the classic anterior iliofemoral approach or the recently revived medial approach first described by Ludloff.’ Each technique offers its own advantages. Advocates of the medial approach described it as a simpler method requiring less dissection and tissue destruction; it attacks the structures at the inferior aspect of the acetabulum which prevent red~ct ion.~*”*’~ Advocates of the anterior iliofemoral approach acknowledge that more dissection is required, but they point out that the approach allows for a more thorough exploration of the joint, and routine capsulorrhaphy. In addition, the anterior approach permits acetabular reconstructive procedures to be performed when necessary. Results of a preliminary series of medial approach open reductions were assessed to determine whether there are additional advantages to the medial approach that warrant its continued use in preference to the anterior iliofemoral approach. Maintenance

For the great majority of children younger than 18 months of age with congenital dislocation of the hip (CDH), closed reduction has been the simplest and safest method of treatment. For the few children who have required open reduction after failure of closed methods, the choice operative approach has been the classic anterior iliofemoral approach or the recently revived medial approach first described by Ludloff.' Each technique offers its own advantages. Advocates of the medial approach described it as a simpler method requiring less dissection and tissue destruction; it attacks the structures at the inferior aspect of the acetabulum which prevent red~ction.~*"*'~ Advocates of the anterior iliofemoral approach acknowledge that more dissection is required, but they point out that the approach allows for a more thorough exploration of the joint, and routine capsulorrhaphy. In addition, the anterior approach permits acetabular reconstructive procedures to be performed when necessary.
Results of a preliminary series of medial approach open reductions were assessed to determine whether there are additional advantages to the medial approach that warrant its continued use in preference to the anterior iliofemoral approach. Maintenance From  of reduction, acetabular dysplasia, and the presence of avascular necrosis were examined in detail.

MATERIALS
All children who had previous avascular necrosis, arthrogryposis, myelomeningocele, or other neurologic diseases were excluded from the study group, leaving 11 children with 15 dislocated hips (eight right and seven left) to be evaluated. All of the 11 children were treated during the period from 1970 to 1978. In addition, all were white, all but one were female, and all had undergone unsuccessful closed reduction treatment prior to the use of medial approach open reduction.
The time of preliminary traction, which was used in 14 hips, ranged from four to 85 days (mean, 44 days). The purpose of this traction was to pull the femoral head down to the level of the triradiate cartilage.' The patients' age a t the time of open reduction ranged from three to 12 months (mean, 8% months). The surgical method used was the medial approach described by Ferguson,' proceeding inferiorly to the adductor longus. A hip spica cast was applied postoperatively to maintain hip flexion and abduction for a period ranging from five to 20 weeks (average, 9 weeks). Using abduction braces, a further period of hip abduction was maintained to encourage acetabular development. Follow-up to final evaluation in the 15 hips ranged from two to 9% years (average, 4% years).

RESULTS
Each patient's roentgenograms, representative of the course of care, were evaluated for the presence of acetabular deformity, persistent femoral head subluxation and avascular necrosis. Hips which had avascu-0009-921X/82/0900/127 $01.10 0 J. B. Lippincott Co. lar necrosis were segregated into two groups: those with involvement of the ossific nucleus only, and those with involvement of the ossific nucleus in conjunction with growth plate All 15 hips at most recent evaluation or just prior to subsequent surgery displayed a range of deformity and insufficient acetabular development from mild to severe. The osseous development of the acetabulum, which occurs in response to a well-seated, FIG. 1B. The same patient as in Fig. 1A after 21 months in the abduction brace. Notice the persistent dysplasia with minimal residual subluxation.
concentrically contained femoral head, continued to be delayed. This delay in development was observed in the roentgenograms as an irregularity in ossification of the weight-bearing area of the acetabulum and also, by an increase in the acetabular index.
All 15 hips roentgenographically displayed mild to severe persistent subluxation of the femoral head at the time of cast removal. The evidence of persistent subluxation resulted in continued treatment in abduction braces, full-time for a prolonged period. Radiographs obtained either at the most recent follow-up or prior to secondary surgical procedures showed that nine of the hips continued to have persistent subluxation. The femoral heads in these nine hips remained partially uncovered as a result of subluxation, as well as of residual acetabular deformity.
CASE REPORTS Case 1. A child had a dislocated right hip treated at five months of age by traction, adductor tenotomy, closed reduction, and hip spica cast; the hip redislocated in the cast. The child had no further treatment until referred to the authors three months later, at which time she was placed in traction for 17 days. A medial approach open reduction was performed at nine months of age. Postoperatively, reduction was maintained by use of a hip spica cast for eight weeks, followed by abduction bracing for 21 months to treat the persistent subluxation (Fig. 1A). When bracing was discontinued, acetabular deformity and minimal femoral head subluxation were still present (Fig.   1B). The patient then underwent innominate osteotomy to correct the residual deformity.
These two persistent features, acetabular deformity and subluxation, were disconcerting, as some form of abduction maintenance was required in 14 hips following removal of the hip spica casts for an average of 18 additional months. Some hips displaying milder forms of subluxation did not require subsequent surgery; they had been corrected by bracing. However, subsequent surgery to improve concentric reduction and acetabular coverage was necessary in six hips. Three hips required innominate osteotomy, two required varus derotation osteotomy in addition to a shelf procedure, and one required a varus derotation osteotomy. Further surgery is still being considered in three hips.
Roentgenographic features of vascular insult presented in ten hips. Six hips demonstrated involvement affecting the ossific nucleus. Four hips had growth plate damage as well as changes in the ossific nucleus. Case 2. A child had a history of bilateral dislocations which were treated at another center in a Pavlik harness beginning at age one month and continuing for five months. After three months in the harness, the left hip was reduced and became stable but the right hip continued to redislocate easily, even though the harness maintained the hip within the acetabulum. The Pavlik harness was discontinued and the child received no further treatment for four months. She reported to the authors at ten months of age. The ossific nucleus was apparent in the right hip, although it was smaller than in the left. This radiographic appearance of the hip indicated no signs of vascular insult resulting from her previous treatment ( Fig.  2A). She was placed in traction for 28 days5 before undergoing medial approach open reduction. Following surgery, reduction was maintained by use of a hip spica cast for six weeks, after which she was placed in an Ilfeld brace. Four months after the open reduction, avascular necrosis was apparent (Fig. 2B). At last follow-up, two years six months after open reduction, vascular insult of the ossific nucleus with growth plate damage was apparent (Fig. 2C). Abduction bracing was continued for the persistent acetabular deformity and femoral head subluxation.

DISCUSSION
In this series, use of the medial approach for congenitally dislocated hips was reserved for those patients younger than 18 months of age who had failed to respond to other treatment methods. Other investigators have obtained good results with this type of open reduction. In children younger than two years of age, Mau et al. ' approached the hip joints superior to the adductor longus, as described by Ludloff,* following a period of traction. They reported no redislocation and indicated that retention was successful; however, 54% of the hips required intertrochanteric and innominate osteotomies. Thirtyfive per cent had slight, transient, ischemic FIG. 2A. A ten-month-old child with right congenital dislocation of the hip having undergone an unsuccessful Pavlik harness treatment. This roentgenogram was obtained four months after the treatment was discontinued. The patient is undergoing traction, and no signs suggesting avascular necrosis have evidenced.
radiographic changes of the femoral head, with 4% having avascular necrosis. ' Ferguson's3 approach went inferior to the adductor longus to release the iliopsoas; it was not preceded by traction. In fact, open reduction was the primary treatment. He reported that the first two hips redislocated because they were immobilized for too short of a period. The next 32 hips were immo- bilized for four months with no redislocations, no subsequent osteotomies, and no avascular necroses. A later report of 100 cases indicated no avascular necroses and three dislocations which required further treatment.4

Roose et d.'* described their technique for
routine medial approach open reduction as being similar to Ferguson's, although preoperative traction was used in half of the patients. Twenty-five per cent of the hips demonstrated persistent subluxation, and 25% had redislocations. Thirty-five per cent of the hips required subsequent surgery. They found no avascular necroses.
StaheliI3 reported his results using the Ferguson approach after failure of previous attempts at reduction. One hip of 40 redislocated, and 40% of the hips required subsequent surgery. Fifteen per cent had avascular necrosis. Weinstein and Ponseti14 reported their experience with the medial approach open reduction after failure of closed methods. Prereduction traction was used in half of their cases. They reported no redislocations, but 9% of the cases had subluxation. One child required two more open reductions and a femoral derotation osteotomy. Avascular necrosis occurred in 9%.
The presence of acetabular deformity was judged by inspection, because the acetabular indices were inconsistent in the sequence of roentgenograms for some patients. The variation in the measurement of the acetabular index was demonstrated by Caffey et a1.,2 whose studies of this measurement in infants indicated it to be a less than reliable method of assessment. Femoral head subluxation was also judged by inspection, because the center-edge angle in the face of acetabular deformity was not representative of subluxation alone. The need for subsequent surgery to improve hip function following a medial approach open reduction was assessed and considered to be an indicator of acetabular deformity and femoral head subluxation. The labeling of the medial approach as a failure, implying that further surgery should be undertaken, must be qualified by noting that such treatment was considered only when long-term follow-up showed that subluxation was progressing. Although no redislocations occurred in this series, all of the hips had acetabular deformity, and in nine hips there was persistent subluxation of the femoral head that could not be managed by bracing alone. Fifty-three per cent of the hips have already undergone or will undergo subsequent surgery to improve coverage of the femoral head or concentric reduction. Concentric reduction of the femoral head without impediment is important. The medial approach is effective in dealing with structures that prevent reduction in the inferior acetabulum but it is not effective in dealing with obstructions in the superior acetabulum. Of equal importance is an adequately performed capsulorrhaphy for stable reduction, which cannot be accomplished through a medial approach. Both principles must be applied to stimulate development of the acetabulum. In the authors' experience, postoperative maintenance in abduction braces alone was not sufficient for acetabular development in every patient. In retrospect, for patients with problem hips, a prolonged period of postoperative casting (longer than the average of nine weeks reported in this series) may have resulted in better stability and less residual dysplasia.
The incidence of avascular necrosis in this series was 67%, with involvement of just the ossific nucleus in 40% and involvement of the ossific nucleus in association with the growth plate in 27%. Although all of the patients had undergone unsuccessful open or closed reduction treatment prior to the medial approach, radiographs indicated that none of the cases of avascular necrosis could be attributed to the earlier treatments. This is a high incidence of avascular necrosis when compared with closed methods and open reduction by the anterior iliofemoral approach following an appropriate period of traction. The inherent problem with the medial approach is the difficulty with visibility of vascular structures that cross through the surgical area. Attention to detail is necessary to minimize damage to the vascularity of the femoral head. Damage to branches of the medial circumflex artery and accompanying veins that cross over the anteromedial capsule is almost inevitable, even when great care is taken to avoid it.
In the authors' experience, the success with the Pavlik harness in younger children, and with traction followed by closed reduction in children 18 months of age and younger, has obviated the need for operative intervention in most p a t i e n t~. '~~~*~' When open reduction is required in children younger than 18 months of age because closed attempts have failed, the anterior iliofemoral approach is preferred, as it permits adequate exposure of the acetabulum and a capsulorrhaphy, which is necessary for retention of reduction while the hip joint develops. The results of this small series caused the authors to discontinue medial approach open reduction in patients younger than 18 months of age with CDH.

SUMMARY
In a retrospective clinical review of patients with congenital dislocation of the hip who underwent open reduction through the Ludloff medial approach, stability of reduction, acetabular development and presence of avascular necrosis were evaluated in 11 patients with 15 dislocated hips. This approach was reserved for patients younger than 18 months of age in whom closed reduction had failed. Ten patients with 14 hips underwent preoperative traction. All 15 hips at follow-up or just prior to subsequent surgery displayed dysplastic and insufficient acetabular development, with persistent subluxation in nine hips. Subsequent surgery to obtain better concentric reduction and acetabular coverage was performed in six hips, and further surgery is being considered in four other hips. Ten hips showed signs of avascular necrosis of the ossific nucleus, with additional involvement of the growth plate in four hips. The medial approach resulted in inadequate concentric reduction, with a high incidence of avascular necrosis. In the majority of patients in this small series, a secondary procedure was needed to improve hip stability and the acetabular dysplasia.