Nontraumatic Hip Pain in Active Children: A Critical Differential
Lynda F. Gerberg, MD; Lyle J. Micheli, MD
In Brief: A case report of an 8-year-old baseball player who was diagnosed with Legg-Calvé-Perthes (LCP) disease gives an opportunity to consider the many nontraumatic causes of hip pain. Possibilities include slipped capital femoral epiphysis, septic arthritis, transient synovitis, juvenile rheumatoid arthritis, and bone tumor. Radiographs and bone scans are used to document and stage LCP, and to evaluate the effectiveness of treatment. Though the aggressiveness of treatment depends on the disease stage, the treatment of choice is generally nonsurgical containment of the femoral epiphysis with a cast or orthosis.
When an active young person presents with a limp and hip pain, an injury should of course be considered; however, it is also important to think about the many nontraumatic entities with similar presentations.
Our case report of a patient who had Legg-Calvé-Perthes (LCP) disease (avascular necrosis of the femoral head) demonstrates the importance of a thorough exam and referral when necessary.
An 8-year-old Little League baseball player presented with a history of intermittent pain in his left hip over the past 6 months. It had begun gradually and was initially most noticeable during baseball practice. Crutches and activity restriction, prescribed after a recent exacerbation, had provided no relief, and he was referred to our orthopedic sports medicine clinic.
There was no history of acute trauma. He had been experiencing pain with all activities. He had no history of illness.
On physical exam, the patient walked with an antalgic limp. He otherwise appeared to be in good health with appropriate height and weight for his age. He was afebrile. There were no gross deformities in his legs or hips and no differences in temperature or girth between the limbs. He had marked discomfort to palpation over the entire left hip region. Internal rotation and hip abduction caused significant pain. When compared with the opposite side, decreases were noted in hip range of motion in abduction, internal rotation, and flexion.
A full laboratory work-up included complete blood count, erythrocyte sedimentation rate, antinuclear antibody, rheumatoid factor, and Lyme titer. There were no significant findings. Plain radiographs demonstrated a "moth-eaten" radiolucency suggestive of osteopenia of the femoral epiphysis and neck (figure 1a). The femoral epiphysis was shortened. A bone scan (figure 1b) demonstrated evidence of avascularity of the left femoral epiphysis consistent with LCP disease.
The patient was placed in a Petrie spica cast with the hip in 30° abduction and 30° internal rotation. A follow-up x-ray (figure 1c) demonstrated proper containment of the femoral epiphysis within the acetabulum.
The patient was pain free 2 weeks after cast application. After cast removal at 6 weeks, physical therapy was instituted to restore full range of motion and strength to the hip, and three-point partial weight bearing was begun. Anteroposterior and frog lateral radiographs taken after 1 month of physical therapy demonstrated continued containment and no fragmentation of the femoral epiphysis. The patient remained pain free, and hip range of motion improved. He was sent home on crutches for another 12 weeks after which crutch use was tapered. Nine months after initial diagnosis he was taken off crutches completely and was asymptomatic.
Anteroposterior and frog lateral x-rays taken 1 year after initial presentation (figure 1d) demonstrated that the femoral epiphysis had remodeled within the acetabulum with a good spherical shape. Mild sclerotic changes had not progressed and the joint space was preserved. The patient returned to sports without difficulty.
More on Legg-Calvé-Perthes Disease
LCP disease may present between ages 2 and 12; the majority of cases occur when patients are between 4 and 8 years old. In boys the incidence is 1:750; in girls it is 1:3,700 (1).
Initially pain free, this condition often presents as a limp after activity. The limp usually worsens, and eventually the patient may complain of pain in the hip, groin, inner thigh, or occasionally the knee. Muscle spasm and synovitis can limit motion, particularly abduction and internal rotation. Though various triggers of LCP disease have been hypothesized, including trauma, synovitis, and hypercoagulability, the pathogenesis these hold in common is interrupted blood supply of the growing femoral epiphysis (2).
The natural history of LCP disease occurs in the following stages: (1) Edema develops at the synovial membrane and capsule over 1 to 6 weeks. (2) Necrosis of the femoral epiphysis occurs, and can last from several months to 1 year. (3) Regeneration/resorption lasts 1 to 3 years. Granulation tissue invades the necrotic bone, leaving isolated areas of bone sequestered (1). Invasion by connective tissues leads to resorption and replacement by new immature bone. This may result in weakening of subchondral support. (4) Repair occurs when new, normal bone replaces dead bone. The outcome is related to the percentage of epiphysis involved, the patient's age, and the promptness of the diagnosis (3). Catterall (3) classified LCP disease into four stages based on radiographic findings of percentage of involvement of the epiphysis (figure 2: not shown). Plain radiographs of our patient's hip showed changes that were clearly consistent with LCP disease (Catterall stage 2); however, further imaging is indicated if there is a strong suspicion of LCP disease despite normal plain films. We confirmed our diagnosis with a bone scan, which is highly accurate once symptoms have presented. New developments in nuclear medicine such as the pinhole camera and computerized axial techniques allow even earlier diagnosis of ischemic necrosis (4). Magnetic resonance imaging (MRI) is extremely effective in detecting early and preclinical or asymptomatic avascular necrosis, and it localizes and identifies the extent of the ischemia. Because of cost, MRI should be reserved for early identification when less expensive tests are negative or inconclusive (4).
Other Nontraumatic Hip Disorders
The differential diagnosis in the work-up of a patient with apparent LCP disease takes on added significance because one of the possibilities—slipped capital femoral epiphysis (SCFE)—is an orthopedic emergency and requires immediate referral. Several other hip disorders resemble LCP disease.
Slipped capital femoral epiphysis. SCFE is the most common nontraumatic hip problem in adolescents, and its presentation is similar to that of LCP disease. In SCFE, the epiphyseal plate weakens during rapid growth. The stress of the patient's body weight disrupts the attachment of the femoral neck and the femoral epiphysis, with the femoral neck moving upward and forward on the femoral epiphysis.
Clinically, patients who have SFCE are either obese or tall and thin. The condition usually occurs in children who are slightly older (11 to 16 years) than those who have LCP disease. The physical presentation is similar, but the pain is usually worse. The patient is unable to touch the abdomen with the thigh because the hip externally rotates with flexion. Radiologic studies help differentiate SCFE from other hip disorders. It must be kept in mind that SCFE is an emergency, and requires non-weight-bearing treatment as soon as it is diagnosed (5).
Septic arthritis. In our patient, septic arthritis was quickly ruled out. He appeared healthy, with no fever or other clinical or laboratory signs of sepsis, and the physical exam of his hip did not correlate with the picture of a septic joint.
Though septic arthritis is seen in all age groups, it is most common in infants and children ages 1 to 2 years. Patients often have a history of recent injury or infection such as otitis media. The usually acute onset of septic arthritis is accompanied by fever, apprehension, and loss of appetite. The joint is warm, swollen, and held in flexion. Active and passive range of motion are limited by extreme pain. Physical and laboratory signs of sepsis should prompt quick referral for immediate aspiration of the joint under appropriate conditions.
Transient synovitis. Transient synovitis can resemble LCP disease; however, the patient may have a history of a recent upper-respiratory infection and may have a slight fever, usually no higher than 100°F (37.7°C) to 101°F (38.3°C). Transient synovitis is the most common cause of hip pain in children under age 10. Patients present with pain in the anteromedial aspect of the thigh and knee and walk with a limp. Motion is limited, and a flexion contracture of the hip may be present. Hematologic tests are negative with no signs of sepsis. On radiographs, capsular bulging is evident; no changes in bone are seen, which helps rule out avascular necrosis. Transient synovitis is a self-limited benign condition. Weight-bearing is limited, and radiographs are repeated in 2 to 3 months to rule out LCP disease, which may develop after an episode of transient synovitis.
Rheumatoid arthritis. The hip is the third most common joint to be involved in pauciarticular juvenile rheumatoid arthritis. Children with pauciarticular juvenile rheumatoid arthritis do not present with systemic systems. The insidious onset is accompanied by swelling, stiffness, and minimal pain on motion. Effusion is palpable, and soft-tissue and bony changes are seen on radiographs.
Tumors. Tumors involving the hip joint must also be kept in mind. The physical exam and radiographic studies will help detect or rule out a bone tumor.
Restoring Hip Function
LCP disease requires individualized treatment; factors include age at onset, change in range of motion, stage of the disease, and Catterall group. Age at onset is a significant prognostic factor—results are significantly better in younger children. Therefore, early diagnosis is the most important factor in preventing long-term complications. The main treatment objectives are to relieve muscle spasm, regain range of motion, and contain the femoral epiphysis within the acetabulum to minimize deformation of the femoral head.
Historically, there have been four methods of treatment (1): observation, bed rest, nonsurgical containment with ambulation, and surgical containment. Currently, observation is chosen only when the patient has no decreased range of motion and meets Catterall's stage I criteria. The child is allowed to continue with regular activities of daily living. Bed rest is rarely used today because it requires lengthy hospitalization (2). However, bed rest with hip abduction has shown satisfactory results in 70% to 80% of patients (1).
If surgery is required, the goals are the same as for nonsurgical treatment: to regain adequate range of motion, minimize deformity, and relieve muscle spasm (5). The femoral head is repositioned via femoral osteotomy or the acetabulum repositioned via pelvic innominate osteotomy. The goal is to place the femoral epiphysis deep within the acetabulum, therefore preventing or minimizing deformation. Surgery should be reserved for patients who have or are progressing to femoral head deformity, but who cannot or will not accept orthoses.
The current treatment of choice is ambulatory management with nonsurgical containment of the femoral epiphysis. This method has been used with extremely favorable results (6). and allows the child to continue most activities of daily living. Good results have been observed in 60% to 70% of patients. Without containment, the femoral epiphysis may become deformed and extrude from the acetabulum during the revascularization stage of LCP disease, particularly if the hip is allowed to maintain adduction and external rotation. Placing the femoral epiphysis within the acetabulum and maintaining abduction and internal rotation reduces forces on the epiphysis, allowing it to remodel properly.
Methods of ambulatory containment include the Petrie spica cast and removable devices such as the Newington A-frame orthosis, the Scottish Rite abduction orthosis (7), and the Toronto brace. It has been our experience that ambulatory casting gives excellent results along with good compliance by the patients and their families.
Long-term prognosis. Long-term outcomes are good in the majority of patients (1,2,5). Approximately 9.5%, however, develop deteriorating symptoms and degenerative arthritis in late adolescence and early adulthood. The development of degenerative arthritis is not related to sports participation after initial treatment (5). These patients often require surgery before age 35. Studies (5) have shown that the abduction extension osteotomy yields the best results, relieving pain, improving range of motion, and correcting any leg length discrepancies.
A Full Return to Activity
Early recognition and intervention can help patients with LCP disease avoid deformity and disability that might otherwise lead to lifelong impairment of activity. Indeed, the long-term prognosis for complete recovery and sports participation after treatment is excellent, and most patients can return to activity without restrictions.
Dr Gerberg is director of sports medicine at Schneider Children's Hospital in New Hyde Park, New York, and an assistant clinical professor of pediatrics at Albert Einstein College of Medicine in Bronx, New York. Dr Micheli is director in the Division of Sports Medicine at the Children's Hospital in Boston, an associate clinical professor of orthopedic surgery at Harvard Medical School in Cambridge, Massachusetts, and a fellow of the American College of Sports Medicine. Dr Goldberg is director of sports medicine at Yale University Health Services and a clinical professor of pediatrics at Yale University School of Medicine in New Haven, Connecticut. Dr Hershman is assistant director of orthopedic surgery at Lenox Hill Hospital in New York City. Dr Micheli and Dr Goldberg are editorial board members of the The Physician and Sportsmedicine. Address correspondence to Lynda F. Gerberg, MD, Schneider Children's Hospital, Long Island Jewish Medical Center, Department of General Pediatrics, 269-01 76th Ave, New Hyde Park, New York, 11040; e-mail to [email protected]