Valgus Osteotomy to Correct Impingement and Improve Limb Position

Catterall and others have defined methods for managing late femoral head deformity without entering the hip joint. These patients often have pain, a shortened limb, and a limp caused by the coxa vara resulting from severe Perthes disease ( Fig. 2 ). These patients sometimes have a flexion contracture with the leg held in adduction to avoid lateral femoral head impingement. Physical examination and radiographic examination can confirm the deformity and cause of symptoms. Often, abducting the hip causes discomfort and pelvic rotation because of the extruded femoral head impinging on the acetabular rim.

( A ) Left hip Legg-Calvé-Perthes disease in a 10-year-old child. ( B ) Treatment by combined Salter innominate osteotomy plus femoral varus osteotomy. The femoral head is well-contained. ( C ) Three years later, the femoral head remains round following containment; however, growth disturbance of the proximal femur caused coxa brevis. The greater trochanter abuts the lateral margin of the acetabulum and limits abduction. ( D ) Following correction with proximal femoral valgus osteotomy, the hip abduction is improved.

Such patients can be improved by extraarticular proximal femoral osteotomies. In planning for such an osteotomy, one obtains an adduction radiograph to confirm the position where the more medial portion of the femoral head better centers itself within the acetabulum ( Fig. 3 ). An MRI and an arthrogram may also be helpful in this assessment.

( A ) Anteroposterior pelvis diagram of a patient with Perthes disease with hip impingement. ( B ) Attempted abduction causes tilting of the pelvis and hip pain. The lateral portion of the femoral head impinges on the lateral margin of the acetabulum and causes the joint to hinge open medially. ( C ) When planning a valgus osteotomy a radiograph is obtained with the hip in an adducted position to indicate whether the anterolateral bump can be moved away from the acetabular rim. ( D ) Diagram demonstrates correction of impingement and improved pelvic position after proximal femoral valgus osteotomy.

In most cases the operative procedure includes a proximal femoral valgus osteotomy, whose principle is to correct lateral impingement of the femoral head. The extension component of the femoral osteotomy is somewhat less important. The anterolateral impinging portion of the enlarged femoral head is left intact and not removed. This traditional philosophy differs from later treatment ideas, which are presented next, in which the femoral head and neck are recontoured.

When significant valgus is performed, the hip is at some risk for instability and in such cases a shelf acetabuloplasty can be added to stabilize the hip joint ( Fig. 4 ). An added shelf acetabuloplasty supports the labrum and prevents any risk for residual subluxation ( Fig. 5 ). Decision regarding which patient should have a valgus osteotomy alone versus which might benefit by the addition of a shelf procedure to prevent femoral head subluxation has not been clearly established and requires experience and judgment.

( A ) Depiction of femoral head deformity secondary to Perthes with risk for subluxation caused by a dysplastic acetabulum. ( B ) Risk for further subluxation may increase after proximal femoral valgus osteotomy. ( C ) Shelf acetabuloplasty to prevent femoral head migration after proximal femoral valgus osteotomy may be indicated for patients with an upward-sloping acetabular margin.

( A ) An 11-year-old boy with severe right femoral head deformity caused by Perthes disease. Hinge abduction prevents containment. ( B ) Anteroposterior view of right hip taken intraoperatively after valgus osteotomy plus shelf acetabuloplasty. ( C ) Radiograph obtained 7 years after the surgical procedure. The child is asymptomatic.

The overriding principle of extraarticular osteotomy to prevent late deformity in Perthes disease is to reposition the limb so that the child can walk more normally without impinging the lateral segment of the femoral head. At follow-up most patients treated with valgus osteotomy have satisfactory flexion and extension, continued decreased hip rotation, but much improved hip abduction and a significant improvement in limb length difference. Parents and the patient are usually happy with the procedure because of the improvement in functional limb length difference and limp.

Most centers that treat patients with late Perthes disease have had satisfactory results with the procedure and have been slow to move toward femoral head reshaping procedures. One reason for this is that most patients with an enlarged femoral head have some acetabular dysplasia and if the femoral head is brought down to normal size, there is a risk for hip subluxation. Also, there has been less long-term follow-up regarding head–neck reshaping procedures in Perthes disease.

It is important for the surgeon to be aware of gradual knee valgus syndrome (secondary to chronic hip varus). Hip osteotomy can unmask the knee valgus and it may suddenly “appear” following surgery. One may have to warn parents of this phenomenon and may need to perform simultaneous medial–distal femoral stapling or acute distal osteotomy or possibly late distal osteotomy.

Greater Trochanteric Transfer (Relative Femoral Neck Lengthening)

Greater-trochanteric abutment is a major problem in many cases of healed Perthes for various reasons. In the nontreated cases it is more likely caused by trochanter overgrowth and relative coax vara with head flattening, whereas in surgically treated cases it is often related to varus osteotomy, which worsens an already existing proximal femoral varus deformity. With better understanding of the proximal femoral vascularity, the position of the soft spot, and subretinacular vessels, relative neck lengthening and trochanteric distalization have become successful tools in dealing with treatment of mechanical problems of trochanteric abutment and safe-trochanteric distalization.

Acetabular Procedures

It is important to note that true acetabular dysplasia can coexist in cases of Perthes disease as a morphologic response to the flat, elliptical, mushroom-shaped growing femoral head. An important technical point to note is that of potential iatrogenic acetabular undercoverage following femoral procedure, such as open femoral osteochondroplasty or head-reduction procedure. These can lead to hip instability caused by the relative imbalance in joint congruity from treating the femoral side and may require an additional acetabular procedure, such as the Bernese periacetabular osteotomy, to counteract instability.

Other acetabular procedures have also been reported for management of patients with sequelae of Perthes’ disease. Shelf acetabuloplasty has been reported as an alternative to proximal femoral valgus osteotomy for patients who have hinge abduction and severe Perthes disease. The Chiari osteotomy has been performed to relieve pain in patients with long-term sequelae of Perthes’ disease. The mechanism for pain relief is uncertain, but there may be an element of labral support and redistribution of weight-bearing forces that improve the mechanics of the hip joint when greater acetabular coverage is obtained. The acetabular dysplasia may need to be addressed in patients with healed Perthes, particularly those that present with typical features of dysplasia, such as sloping acetabular roof, hypertrophied labrum, or large labral tears.