When a child presents with a painful joint, the task of identifying the likely cause is not always an easy one. While it is true that many joint problems in children can be readily diagnosed from x-ray, there are some conditions which are difficult to identify early in the course of the disease.
Some of the more common conditions which can produce painful joints in children are listed in the following groups:
Trauma
Fractures
Slipped epiphyses
Dislocations
Sprains and strains
Orthopedic problems
Legg-Calve-Perthes disease
Slipped capital femoral epiphysis
Osgood-Schlatter's disease
Infections
Pyogenic arthritis
Osteomyelitis
Neoplasms
Leukemia
Collagen Vascular Disorders
Juvenile rheumatoid arthritis
For most of the above conditions, a careful and thorough evaluation of the involved area together with a detailed history, will usually provide ample clues to the cause of the problem.
Trauma
When a history of trauma is involved at the time of onset of acute pain, radiographic evaluation of the involved joint is usually necessary to rule out fractures, slipped epiphyses, and dislocations. If the x-rays show no cause for the pain, then joint evaluation for signs of variable instability, accompanied by inflammation and painful passive range of motion, usually indicates a sprain or strain as the likely cause.
Orthopedic Problems
Legg-Calve-Perthes disease of the hip should be the major consideration in children 3-12 who present with a limp and complain of vague pain in the groin which radiates to the anteromedial knee on the same side. X-rays will usually be diagnostic.
Slipped capital femoral epiphysis presents with similar clinical findings as Legg-Calve-Perthes disease, except that the child is more commonly an adolescent 10-15. Children in this age range who complain of hip, thigh and/or knee pain should be suspected of having this condition.
Osgood-Schlatter's disease is a likely diagnosis in a child who has localized pain over the tibial tubercle, with associated tenderness and soft tissue swelling. The history usually includes either knee trauma or activities involving repetitive flexion and extension of the involved knee.
Pyogenic Arthritis
In this disorder the joint is infected by bacteria of one of the pyogenic groups. Typically there is acute joint infection of rapid development, but the infection may be subacute or even chronic. The onset is usually acute with pain and swelling of the affected joint, systemic illness with malaise and fever.
Early signs and symptoms in the young infant, in the first year or two of life, may include poor feeding, irritability, and low or normal temperature. Later, as the infection destroys more of the joint there may be pseudo-paralysis of the involved joint and the overlying tissues may become swollen, tender, and warm.
In older children, early signs may include fever, malaise and refusal to walk, with the overlying tissues becoming swollen, tender and warm. Later, the older child may complain of severe pain and myospasm, and joint splinting may be evident.
Earliest x-ray changes may include distention of the joint capsule. Subsequent changes include narrowing of the cartilage space, erosion of the subchondral bone, irregularity and fuzziness of the bone surfaces, bone destruction and diffuse osteoporosis.
Pyogenic arthritis must be differentiated from acute infections near the joint, especially acute osteomyelitis. The rapid onset of symptoms, fever, leucocytosis and the presence of pathogenic organisms in the aspirated joint fluid are important diagnostic features.
Osteomyelitis
Osteomyelitis is an infectious process that most commonly involves the metaphyseal area of long bones and occasionally a vertebral body. Early signs include localized tenderness over a metaphysis and pain on weight bearing. Other clinical findings may include limitation of motion, localized erythema, warmth, tenderness, swelling and fever, elevated pulse rate and occasionally, severe, constant throbbing pain over the end of the shaft of the affected bone. X-ray changes are usually not apparent until 10 days after the onset, making this a disorder which requires special imaging techniques for its accurate identification early in its course. A radionuclide bone scan will usually be positive as early as the second day of the infection.
Leukemia
The most common cause of cancer in children, acute lymphoblastic leukemia, should be suspected in young children 2-5 who have a history of sickness, appear anemic, and complain of bone or joint pain. The cause of the bone pain is due to the infiltration of leukemic cells under the periosteum of the affected bone. Occasionally, x-rays will show evidence of white metaphyseal bands or metaphyseal fuzziness which is rarely seen in many other conditions.
Juvenile Rheumatoid Arthritis
Arthritis in children should be considered as a diagnosis of exclusion which demands chronicity. That is, all of the above conditions should be excluded, and the symptoms should have been present for at least six weeks before a diagnosis is made. Clinical findings include pain and swelling of any of the following joints: metacarpophalangeal, wrist, foot, ankle, knee or cervical spine. The presentation may present in either a symmetrical pattern, such as in polyarticular disease, or an asymmetrical pattern as is seen with the pauciarticular variety.
Peter Fysh, DC
San Jose, California
Editor's Note: Dr. Fysh is currently conducting pediatric seminars. He may be contacted at: (408) 944-6000.
