Legg-Calvé-Perthes is an idiopathic avascular necrosis (AVN) of the capital femoral epiphysis in a young child. The condition tends to run a fairly predictable time course. It affects both hips in about 10% of cases and is much more common in boys (about 4:1). Children with Legg-Calvé-Perthes disease most commonly present between the ages of 4 and 8 years, but the condition may be seen in children less than 2 years old and as old as skeletal maturity. Most of the trouble with Legg-Calvé-Perthes disease revolves around making the diagnosis, dealing with the parents, and being selective about surgical treatment. Without careful selection, the orthopaedist can get into trouble by overtreating the young or the mildly affected, or the untreatable severe cases, or conversely, get into trouble by missing the more involved older child who would really benefit from surgical management (Fig. 25-1).

The key to staying out of trouble and making the diagnosis of Legg-Calvé-Perthes is to recognize that the presentation can be very subtle and may be mistaken for transient synovitis in the early stages. The most common experience of
the orthopaedist at diagnosis is a mom who says “I notice a slight limp at the end of the day, but he wasn’t complaining of pain.”

Another source of trouble with Perthes is being fooled by conditions that imitate it.

On physical examination, the only sign of a problem may be a subtle asymmetry in hip motion, typically a loss of hip abduction and/or internal rotation. In a young child in the early stages of the disease, the examiner should carefully control the pelvis during examination to avoid missing subtle asymmetry between the hips.

In later stages of the disease, the child may have a flexion contracture and a positive Thomas test. Contracture or spasm of the adductor tendon can also be seen. Just as it is easy to miss a subtle loss of hip motion, it is easy to miss gait abnormalities early in the condition. If there is a subchondral fracture or a hip effusion, the child may walk with either an antalgic gait or with the foot somewhat externally rotated. Later in the condition, the child may develop a Trendelenburg gait and have a Trendelenburg sign.

To stay out of trouble, order an anteroposterior and frog lateral plain radiograph at the first visit for any child who presents complaining of hip or thigh pain.

If there is a synovitis, the pelvis is shifted to the affected side because the X-ray technician is trying to abduct that side but since the hip won’t abduct, the child elevates that pelvis and it appears “catawampus,” or out of line. Be aware that even high-quality plain radiographs may be normal at the first visit.

On initial radiographs, look for the extent of involvement of the femoral epiphysis, paying particular attention to the lateral pillar, the key to prognosis. Increasingly, MRI is becoming essential in the management of Perthes. Although radiographs are always the starting point, MRI can “predict” what future radiographs will look like, as gadolinium-enhanced and diffusion-weighted MRI can identify the ischemic areas of the femoral head early in the disease process.

The treatment of Legg-Calvé-Perthes disease remains controversial and has been dominated in the past more by personal preference and local customs than good data. There are several keys to staying out of trouble when treating Perthes. NEWSFLASH! It is important to understand how much the concept of a “dead hip” terrifies parents. Parents who present to you, especially for a second opinion, can be bewildered by information on the web and the multiple varying opinions that they get from experienced “experts.” To stay out of trouble you will need more time with these families to explain the pathophysiology of the condition, the expected time course, and the limited amount of long-term natural history and treatment data. It is disconcerting to families to learn how uncertain the experts are about definitive treatment.

It is clear that the orthopaedic surgeon should focus attention on children 8 years and older, and on those with moderate hip involvement (Herring B, or B/C). Surgeons and children get in trouble when a complication occurs in the process of overtreating one of the 60+% of children who would do perfectly well without ever seeing a doctor.

Trying to rest the hip of an active (often hyperactive) boy or girl with Legg-Calvé-Perthes can create trouble for the family and the doctor. Children younger than 7 years cannot use crutches effectively. Even older children capable with crutches will be highly noncompliant, especially considering that the request is to use crutches for many months. Therefore, when resting the hip seems important, many prefer to use abduction (Petrie casts) for a period of 6 weeks, followed by physical therapy to work on hip and knee range of motion. To stay out of trouble with Petrie casts, be careful to pad carefully around the Achilles tendon, as this is
a common site of cast pressure sores. Also, prepare the family for a child who is difficult to transport and move around the house.

Should the orthopaedist choose a surgical option, there are certainly several areas that can be sources of trouble for any of the operations: shelf arthroplasty or varus derotational osteotomy (VDRO). Each of these surgical options has one or more champions who promote it as the best option for most kids. Each method has pros and cons and sources of trouble. A common theme for any procedure is to avoid surgery on a very stiff hip.

Slipped capital femoral epiphysis (SCFE) is the most common adolescent hip disorder, estimated at 1 per 10 000 in the United States, and is probably increasing with the epidemic of pediatric obesity. About 80% of the cases occur during the adolescent growth spurt (at ˜12 years of age for girls and 13.5 years of age for boys). The condition is said to be more common in obese African American boys, and more common on the left side. In northern climates, presentation is most common in late summer/early fall, perhaps due to months of low sunlight followed by more active summer months.

One key to staying out of trouble with SCFE is to recognize the child who is an outlier in terms of these demographic criteria. If the child is 11 years old or younger, consider a possible underlying cause such as renal osteodystrophy, hypothyroidism, panhypopituitarism, and hypogonadal conditions. These require an endocrine evaluation and also increase the risk of subsequent contralateral slip. About 25% of the cases of SCFE are bilateral, although some experts believe that up to 60% to 80% are bilateral, many being silent cases that are not discovered until much later. Perhaps the greatest source of trouble with SCFE is a delay in diagnosis (Fig. 25-2). Remember that in SCFE associated with renal failure, the SCFEs are bilateral in 95% of cases.

At presentation, the child will usually have hip, groin, or thigh pain, often for a long time. Although many reports have described the challenges that primary care doctors face in diagnosing SCFE, the diagnosis is missed by orthopaedic surgeons missing the diagnosis. These include stories in which the surgeon first thinks of SCFE while trying to get the externally rotated hip into the leg holder for a knee arthroscopy, or worse, discovering a SCFE at one of the knee arthroscopy postop visits (Fig. 25-3). On physical examination, these children will often have an abductor lurch or an antalgic gait. The foot is usually externally rotated. On the table-top examination, the patient will demonstrate obligate external rotation and abduction with attempts to flex the hip. To stay out of trouble, recognize the signs of an unstable SCFE. Children will not be able to walk and may have pain just with gentle log-rolling of the hip.

Poor imaging, or the misreading of good imaging, can be a source of trouble with SCFE. An AP and frog lateral of both hips should be obtained. Although some believe that the true lateral radiograph is more sensitive, it is much harder to
obtain in a morbidly obese adolescent with hip pain. Often, the AP view will show important signs of a mild SCFE for the careful observer, such as subtle physeal widening, a break in Klein line (Fig. 25-4), or a decrease in femoral epiphyseal height of the involved side compared to the opposite side.

More advanced imaging, such as an MRI, is rarely necessary in SCFE. In some select cases, when there is a very high clinical suspicion, but no confirming evidence on good quality plain radiographs, an MRI can be helpful to make the diagnosis (Fig. 25-5). The surgeon should look for edema on either side of the physes. Other signs on MRI may be slight widening of the physes and a hip effusion. Beware, however, that an obese adolescent with a hip effusion could certainly have other conditions.