Complications of Surgical Treatment of Perthes Disease

Introduction

Legg-Calve-Perthes disease (LCPD) is a self-limited childhood hip condition that can produce permanent deformity of the femoral head. Its treatment remains a challenge, given the wide variation in stage and disease severity. Early containment surgery has become increasingly popular in LCPD, especially for children who present at a later age. Surgical techniques utilized range from minimally invasive, including tenotomies and casting, to more extensive, including redirectional osteotomies of the proximal femur and acetabulum. Treatment for LCPD can be fraught with complications if preoperative planning and indications are taken lightly. Age at diagnosis, stage of LCPD, and extent of disease all have implications for treatment prognosis. The ideal treatment remains controversial at this point, as there is no consensus on optimal treatment ; however, there is agreement that the primary goal of treatment is to prevent femoral head deformity and maintain the sphericity of the hip joint by providing femoral head containment. A deliberate and thoughtful preoperative approach to the individual patient’s anatomy and pathology is necessary to optimize outcomes and minimize complications for LCPD.

Preoperative

LCPD results from disruption of the blood supply to the femoral epiphysis, leading to avascular change and deformation of the femoral head. Waldenstrom described the progression of the disease through predictable stages based on unique radiographic features. Joseph et al. further divided the first three stages into early and late phases. We do know that LCPD itself is a self-limiting condition, and that complete revascularization of the avascular epiphysis occurs over a period of time without any treatment. However, the permanent deformation of the femoral head that results from progression through these stages can lead to stiffness and pain of the hip joint, as well as premature degenerative osteoarthritis.

Extensive work by Joseph et al. has demonstrated that epiphyseal extrusion is one of the most important factors that contributes to deformation of the femoral head, and thus it has been suggested any intervention aimed at preventing femoral head deformation ought to be instituted prior to disease progression to Waldenstrom stage IIb. Therefore, preoperative selection of patients who may benefit from surgery ought to focus on obtaining a correct diagnosis, careful history and physical examination, and radiographic evaluation to accurately identify stage of the disease. Patients who can be identified in the early stages of disease may have a more successful outcome with surgery, Children older than 8 years of age at disease onset can be subject to rapid extrusion of the epiphysis, and may also benefit from surgery. It has also been demonstrated that patients with significant disease severity according to the lateral pillar classification (B/C border, C) may also benefit from early surgery. Patient selection is critical in LCPD to determine who may be most successful with surgery.

Radiographic Workup

Since the initial description of LCPD more than 100 years ago, the diagnosis and staging of the disease have been based on plain radiographs. Typically, anteroposterior and frog lateral projections of the pelvis are obtained ( Fig. 30.1A–B ), providing orthogonal views to adequately assess the femoral head and provide information to determine Waldenstrom stage. Serial radiographs will be performed to determine progression through these stages, ultimately until healing of the femoral head occurs. Standing lower extremity alignment films can also be obtained to examine for limb length discrepancy as well as varus/valgus alignment. Maximum abduction radiographs can also be obtained to demonstrate the degree of abduction the patient has in full extension.

However, given that prognostic classifications often are applied in the fragmentation stage, this may be after deformity of the femoral head occurs and too late in the disease process to maximize the effects of the intervention. Magnetic resonance imaging (MRI) has been utilized recently to determine femoral head involvement early in the disease course using both gadolinium-enhanced and diffusion-weighted MRI ( Fig. 30.1D ). Preoperative imaging must take into consideration a wide differential diagnosis, including infection, skeletal dysplasia, malignancy, and traumatic avascular necrosis; each of these can cause radiographic changes that may mimic the early stages of LCPD ( Fig. 30.1 ).

Intraoperative – Containment Treatment

Containment can be achieved by various surgical and nonsurgical methods. The femur can be positioned in abduction/internal rotation or abduction/flexion, which can be achieved by casting, bracing, or surgery on the femur. Containment can also be achieved by performing a pelvic osteotomy to reorient the acetabulum to cover the anterolateral part of the femoral epiphysis. For children under 8 years of age at disease onset, the outcomes of bracing/cast treatment and surgery for the purposes of containment have been shown to be approximately equal clinically.

Nonsurgical Containment Treatment

One of the primary concerns prior to treatment must be the range of motion of the hip, as a stiff hip is not able to be successfully contained. Stiffness of the hip can result from irritability, inflammation, and synovitis, which can cause guarding of the hip joint and limitations in motion. One of the primary limitations to nonoperative containment in the early stage of LCPD is lack of hip abduction, from adductor spasm, contracture, or irritability.

First-line therapies to relieve pain and inflammation include rest, nonsteroidal anti-inflammatories, and restriction in weight bearing. Various abduction orthoses and casting methods have been described to provide nonsurgical containment. Petrie et al. described a weight-bearing cast in abduction that allows the child to still be able to flex and extend at the hip, allowing for a bit more activity around the home. This method consists of two long-leg casts with a bar in between to hold the legs in abduction to as close to 45 degrees as possible, as well as 5 to10 degrees of internal rotation and knees at 10 to 15 degrees of flexion. Subsequently, other abduction orthoses have also been developed, although the long-term results have proven inconsistent. Abduction casts and braces can be used to contain the femoral head within the acetabulum in hopes of promoting and maintaining a spherical shape during the healing process. Success has been described with an A-frame orthosis using a regime of brace wear for 20 hours per day for an average of 13 months during the early disease stages, with positive results at skeletal maturity. Complications resulting from this treatment include: psychological distress, decreased activity and participation in age-appropriate activities for the child being treated, tedious treatment, and the fact that it is labor-intensive. If physiological hip motion is not present, an adductor tenotomy and brief period of casting followed by an abduction orthosis was found effective by the authors for a nonsurgical containment method. Controversy remains, as these treatment methods have not been shown to be effective for long-term containment, and they present both physical and psychological challenges for the child and family.

Casting can also be performed as an adjunct to the below surgical treatments in order to gain motion prior to either femoral or pelvic osteotomy, if the hip is stiff preoperatively ( Fig. 30.2A ). An arthrogram can be performed to ensure the femoral head can be contained with a combination of abduction and internal rotation without hinge abduction ; the hip can then be casted in abduction prior to performing bony surgery once range of motion has been established.

Arthrogram/Adductor Tenotomy

Examination under anesthesia is helpful to differentiate whether the patient is suffering from a spasm of the adductor musculature or a true fixed contracture. Preoperatively motion must be assessed carefully, as the deformation of the femoral head can cause pain as well as restricted motion, abduction in particular. Catterall described the value of arthrography under general anesthesia to relax the patient’s musculature and eliminate pain to accurately assess the true range of motion of the hip. Use of dynamic fluoroscopy is helpful to determine if the medial joint space is widened, the joint space is narrowed superolaterally, and the superolateral corner of the femoral head failed to move medially with abduction (indicating a shift in the center of rotation to the lateral edge of the acetabulum). This has been identified as “hinge abduction” and may cause increased pain, restricted motion, flexion-adduction contracture of the hip, apparent shortening of the affected leg, and ipsilateral genu valgum. It has been identified as a poor prognostic indicator. Preoperative identification of the presence of hinge abduction is crucial, as the hip may not be amenable to preservation in this situation and may be a better candidate for salvage surgery.

Shore et al. describe a combined experience over 70 years among the reviewers to describe hinge abduction; the consensus of these authors determined that irreduciblity, or hinging, is present when the femoral epiphysis cannot pass underneath the chondrolabral complex in abduction, or if excessive labral deflection or a bilobed femoral head/biconcave acetabulum is present. Given the ambiguity in the definition, however, and the fact that it represents an active and ever-changing process, Shore et al. cautioned against using “hinge abduction” as an indication for surgery, as the diagnostic agreement can be inconsistent. However, it can indicate that a femoral or pelvic osteotomy may be contraindicated and unsuccessful.

In young children, an isolated adductor tenotomy is a tool that can be utilized to improve motion prior to casting or bracing ; however, it has not been shown to consistently improve motion over bracing and therapy alone.