Volume 4, Case 16
Martin I. Herman, MD
LeBonheur Children's Medical Center
University of Tennessee School of Medicine
This is a 6-year old male who presents with a chief complaint of a limp which began 6 months ago. There is no history of trauma, fever, swelling or pain. Recently, he began complaining of right hip pain and the limping became more noticeable. He was seen by his physician on two occasions in the last six months for this complaint. Mother was advised to administer ibuprofen on both visits. He was diagnosed as having toxic synovitis of the hip joint on the first encounter and a non-specific soft tissue injury at the second visit.
His past history is not contributory. His family history is negative for arthritis or skeletal disorders. His growth and development are normal.
Exam: VS T36.9 C, P 108, R 24, BP 110/68. Wt. 24.3 kg. Alert, active, well developed, in no acute distress. He is not toxic. HEENT exam negative. Neck without lymphadenopathy or thyromegaly. Heart regular without murmurs. Lungs clear bilaterally. Abdomen soft, no organomegaly, no masses. Normal male genitalia. Extremities: There is a 2 cm leg length discrepancy. His right thigh is smaller than his left. There is pain with hip extension and external rotation. Trendelenburg test: no hip abductor weakness. Gait: shortened stance phase on the right. The right knee is flexed indicative of a leg length discrepancy.
Lab studies: CBC WBC 7,000, Hgb 12.0, Hct 36%, ESR 13 mm/hr. UA normal. Radiographs of his hips are obtained.
View hip radiographs.
The right hip (left on the image) shows widening of the joint space. The femoral epiphysis is fragmented and flattened. The physis appears narrow. The femoral neck is short and wide (Coxa magna). There is flattening of the femoral capitellum (Coxa plana). Not seen here but common in patients with this disease is lateral displacement of the femur relative to the acetabulum (Coxa varus).
Discussion
Avascular necrosis (AVN) of the femoral head may be idiopathic (Legg-Calve-Perthe's Disease) or due to some insult to the vascular supply of the femur. For example, septic arthritis of the hip, trauma to the hip, especially with dislocation, or steroid use may result in avascular necrosis. In our patient, there is no recall of trauma, steroid use or known congenital hip disease to explain his AVN, leaving Legg-Calve-Perthe's Disease to be the best explanation of his radiographic findings and limp.
Pathophysiology. The blood supply of the femoral head changes with time and growth. Initially the main source of nutrition is supplied directly by nutrient vessels within the femoral head. A small amount of blood passes to the head via the ligamentum teres. By the time the child reaches 1.5 years of age the blood supply has changed. Now most of the blood is being supplied by the femoral circumflex arteries, which enter the femoral epiphysis after traversing the hip capsule. Any injury to the hip can result in avascular necrosis since the blood supply is so tenuous.
Limping is a dysfunction in gait which can be divided into two phases, the stance and the swing phase. The stance phase begins with the heel strike and ends with the toe off. The swing phase begins with the push off and ends with the heel strike. Both feet are on the ground for about 20% of the cycle. Any aberration of the cycle will be noticed as a limp. The gait may appear choppy or labored and may be due to pain, weakness or deformity. Determining the cause of the limp may be easier if one can determine what type of limp is present. Historically, limps have been divided into three types: antalgic, Trendelenburg, and short leg.
Antalgic gait is caused by pain and is also called the quick step gait. Patients with this will have a shorter stance phase on the affected leg. This quick step minimizes the time stress is placed on the painful extremity. A compensatory acceleration is seen in the contralateral swing phase.
Trendelenburg gait, also called the abductor lurch gait, is seen in children with chronic hip disease. In this type of gait the hip drops down (pelvic tilt) during the swing phase due to weakness of the contralateral gluteus medius muscle. With bilateral involvement, the trunk will sway from side to side with walking. Trendelenburg gaits do not affect the amount of time standing on either foot. You can detect gluteus medius paresis by performing the Trendelenburg test. In this test, the patient is asked to stand with one foot off the ground and is observed for dropping or tilting of the pelvis on that side. A slight rise in the pelvis is to be expected. In the case of our patient, the Trendelenburg test was negative for pelvic tilt on either side, indicating that the cause of his limp was not due to muscle weakness, nor was the condition present long enough to result in atrophic weakness of the gluteus medius muscles.
The so called short leg gait is the result of true or pseudo leg length discrepancies. In this gait, the longer leg will have persistent knee flexion on standing. The child might also walk on the toes of the shorter leg to compensate. An up and down motion of the pelvis may be seen in this gait, but the Trendelenburg test will be normal. True leg length abnormality can be determined by measuring the anterior iliac spine to medial malleolus distance. Apparent or pseudo-leg length mismatches may be due to joint contractures of either hip or knee flexors. In this case, measuring the umbilical to medial malleolus distance will quantify the differences more accurately.
Our patient had a 2 cm discrepancy and, when standing, it appeared that the right leg was longer as he kept the right knee flexed. His gait was consistent with both an antalgic gait and a short leg gait.
The differential diagnosis of limping may be divided into categories by disease class and also sub-divided by age at presentation. For the purposes of this discussion, I have divided the etiologies of limp into pathophysiologic groups as follows: vascular (vasculitic and inflammatory), infectious, congenital, trauma, toxic/metabolic, neoplastic, degenerative, neuromuscular, and other.
Vascular causes include juvenile rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosis, scleroderma, Henoch Schonlein purpura, psoriasis, insect venoms, Stevens-Johnson syndrome, and deep venous thrombosis. Rheumatologic conditions such as juvenile rheumatoid arthritis (JRA) can present in a single joint and are easily mistaken for a septic joint. An associated rash or iridocyclitis may help in making the diagnosis. Limping may also be a presenting problem in Henoch Schonlein purpura (HSP) as arthritis may occur in association with HSP.
Rheumatic Fever, Lyme Disease and Kawasaki's Disease should be kept in mind (see infectious causes). Other inflammatory conditions associated with limping include serum sickness, Stevens-Johnson syndrome, reactions to insect venom and overuse syndromes.
Deep Vein Thrombosis (DVT) is rare in children but may present in patients with hypercoagulable states, poor blood flow, or after trauma to the lower extremities. The diagnosis of DVT may be made via Doppler flow studies, impedance plethysmography or venograms. Treatment will vary depending on the age of the thrombus, location and co-existing disease. Psoriasis may have an arthritis associated with its dermatologic manifestations and, ironically, the arthritis can precede the skin changes. The collagen vascular disorders and rheumatoid diseases constitute a wide assortment of diseases that may present with limping. Often, radiographic findings will be absent until degenerative changes occur.
Infectious causes include osteomyelitis, septic arthritis, toxic synovitis, diskitis, Lyme arthritis, tuberculous arthritis, etc. Bone and joint infections can be easily missed and can result in permanent sequelae if the diagnosis is delayed. Usually there is fever with swelling, erythema and tenderness near the area of infection, but often the only help in detecting osteomyelitis or pyogenic arthritis is the limp. Major etiologic agents include Staphylococcus aureus and Streptococcus pyogenes (group A beta-hemolytic strep). In neonates, group B streptococcus may be causative. Adolescents need to be screened for Neisseria gonorrhea and, in patients with sickle cell anemia, Salmonella species may be the cause.
Evaluation should include the spine and pelvis in addition to the extremity to avoid missing diskitis or sacroiliac disease.
Not to be confused with infectious arthritis, toxic synovitis presents as joint pain with low grade fever usually associated with or shortly after a viral illness. It is self-limited and can be treated with analgesics and observation. Rubella vaccine can also cause an arthritis.
Lyme arthritis is a sequelae to Lyme disease, a tick-borne infection due to Borrelia burgdorferi. Characteristically the disease starts with erythema migrans. It may involve all major body systems, including the brain, peripheral nerves (Bell's Palsy is seen, often bilaterally) and joints. Five types of arthritis can occur: 1) episodic, involving 1-4 joints for < 1 week recurring at least 2 weeks later, 2) acute pauciarticular, 1-4 joints for < 4 weeks, 3) chronic pauciarticular, 1-4 joints > 4 weeks, 4) > 3 joints in sequence, and 5) > 5 joints. Treatment may include amoxicillin, doxycycline (if older than 9) or ceftriaxone.
Tuberculous disease of the bones was once a major concern and may be showing a resurgence in today's medical environment because of multiple drug resistance, AIDS and other immune suppressed patients in our communities. There are some infectious diseases that will have an arthritic component to them. Yersenia enterocolitica, hepatitis A & B, infectious mononucleosis, rubella, rubeola, coxsackie virus and human parvovirus B-19 all cause arthritis/arthralgias and should be considered as possible etiologies in the evaluation of the limping patient.
One particularly common infectious source of limping is Hallux incarnatus or ingrown toenail. This usually affects teenagers, especially those active in sports. The mechanism in this disorder involves the way the nail is clipped or manually pared. Treatment consists of soaking and local treatment. If infection recurs, surgical removal of the nail or part of the nail is effective.
Congenital causes of limp include coxa vara, congenital hip dysplasia, congenital short femur, spinal dysraphism, and other congenital limb deficiencies. Congenital hip dislocation (CHD) usually presents in the nursery but may not be detected until the child is older. This topic was presented in Pediatrics in Review, vol. 16, no. 8, 1995. Please refer to that issue for more details. Another radiographic case of congenital hip dislocation and a discussion are presented in Case 13 of Volume 2, Vomiting Following Reduction of Intussusception.
As some children may not have dislocated hips at birth, the term congenital hip dislocation is a misnomer. For those whose dislocation occurs later in the first year of life, the term "acquired hip dislocation" is more appropriate. Meyers dysplasia, which can look similar to Legg-Calve-Perthes disease, involves the growth plates of both femoral capital epiphyses only. Also, multiple epiphyseal dysplasia and hypothyroidism can mimic LCP. Multiple epiphyseal dysplasia is inherited as an autosomal-dominant trait. It presents in two ways: hip abnormalities and short stature. Hip pain occurs by age 5 and certainly by age 10. The epiphysis will appear flattened but otherwise normal.
Examples of trauma include toddler's fracture, stress fracture, patellofemoral pain, spondylolisthesis, ruptured plantaris tendon, knee strain, meniscal injuries, herniated nucleous pulposis. When trauma is the cause of the limp, the older child or adolescent will provide an accurate description of the forces invoked. Toddlers (age 1-3 years), however, can present without a history for injury, or the witness may have felt the trauma was too insignificant to cause a fracture. Such a scenario is often found in children who have a non-displaced fracture of the tibia, known as the toddler's fracture.
The toddler's fracture usually is a spiral fracture of the distal tibia without displacement. Refer to Case 17 in Volume 4, The Toddler's Fracture: Accident or Child Abuse. Sometimes the fracture is only picked up on follow-up radiographs or by bone scan. In addition to the toddler's fracture, two other injuries noted in the limping toddler include fibula fractures caused by recurrent infant walker trauma and occult cuboid fractures. Always consider the possibility of inflicted injuries when assessing infants and children with limping, and look for bucket handle fractures or corner fractures that are suggestive of child abuse.
Also remember that contusions, muscle injuries, splinters, foreign bodies and shoe abnormalities can result in limping. Teenagers and school age children may have sprains of the ankle, knee or hip resulting in limping. Other traumatic causes of limping would include an avulsion fracture of the base of the fifth metatarsal, ankle sprains, and stress fractures of the metatarsals. Salter Harris Type 1 fractures of the distal fibula may appear as simple ankle sprains. Refer to Case 3 of Volume 3, Ankle Injuries: A Sprained Ankle?
Also the limping patient may have torn his plantaris tendon. This structure is an aponeurosis found in the lower leg posterior compartment and may rupture during exercise. Patients report a snapping noise, then onset of pain. Pain is increased with dorsiflexion. Treatment involves resting the lower leg (splinting and non-weight bearing) and analgesics.
Patellofemoral disorders include patellar subluxation, recurrent patellar dislocation and chondromalacia patella. This is more commonly seen in females and is easily aggravated by repetitive bending. Permanent injury to the cartilage is rare. Typically pain is elicited by squeezing the patella or is exacerbated by stair climbing. Treatment includes anti-inflammatory medications, rest and ice applications. Rarely, a surgeon may need to debride the underside of the patella.
Ruptured vertebral disc is more a disease of adults but has been seen in teenagers, especially those involved in heavy weight training or arduous labor. Symptoms are similar to those found in adults with paresthesias, foot drop, or intractable pain. Treatment depends on the extent of nerve impingement and may involve physical therapy, exercises, chemonucleolysis or surgery.
Toxic/metabolic causes include drugs, rickets, scurvy, hyperparathyroidism. Surprisingly, some drugs can cause limb pains and present as limping. Vitamin A intoxication and carbamazepine have been implicated. Corticosteroids, ergotamine, phenothiazines and thiazides may cause muscle cramps. Also, recall that some drugs can cause a lupus-like syndrome. Hypercalcemia can cause bone pains. Rickets may be associated with fractures and pain. The most common form of rickets seen in the U.S. is vitamin D-resistant. It is inherited in an X-linked dominant manner. The defect is in the proximal absorption of phosphate which leads to hyperphosphaturia. Skeletal changes occur as the child ages. Other metabolic diseases that affect the skeletal system include the mucopolysaccharidoses. All of these disorders usually involve some type of spinal deformity, with kyphosis being the most common.
Neoplastic causes include benign bone tumors (unicameral and aneurysmal bone cysts), malignant bone tumors, metastatic bone disease, and leukemia. Sarcoma may involve the hip, femur or proximal tibia. Growing children are affected most often, with the peak incidence occurring in the teen years. The two most often seen are Ewing's sarcoma and osteogenic sarcoma.
Leukemia may present with limb pain or a limp. Metastatic disease from other primary sites such as neuroblastoma and lymphoma may also cause bone pain and limping. Another cause of lower extremity weakness, and hence limping, is a sacrococcygeal teratoma. Benign bone lesions such as osteochondromas and osteoid osteoma may be found in the limping child.
Degenerative causes include avascular necrosis of the femoral head (Legg-Calve-Perthe's Disease). Legg described a non-tuberculous degeneration of the hip among American children in 1909 at the same time Perthes of Germany and Calve of France did. Originally thought to be due to some infectious process, Legg-Calve-Perthes (LCP) is currently believed to be caused by avascular necrosis of the femoral head ossification center. It is seen in about 1 out of 750 children who usually present between ages 4 and 10. Most likely LCP is due to repeated trauma to the hip in active boys which may impair the blood supply to this area. Typical patients will complain of pain with hip motion and limp. The pain may radiate down the thigh towards the knee. Swelling and tenderness on exam are rare. Other findings might include limited internal rotation, decreased hip abduction, and mild hip flexion contractures. Occasionally, the thigh is atrophic.
Laboratory examinations are all normal, and the diagnosis is made by plain radiographs of the hips once significant necrosis has occurred. Radiographs may be negative early on. Management of patients with LCP depends on when they present. Young children who still have substantial femoral head cartilage have a good prognosis. Goals of therapy include resolving the hip joint inflammation and positioning the femoral head in such a way as to promote healing. If 50% or more of the femoral head can be seen, therapy is aimed at maintaining the range of motion until healing occurs. When more than 50% of the head is involved, orthopedists will place the hip in an abduction brace, or hip spica cast, or perform an osteotomy of the proximal femur to position the femoral head well into the acetabulum. Usually the brace is used for children under 7, and osteotomy reserved for the older patient. Ultimately, the outcome for those who present with less than 50% of their femoral head involved is good. Children under 6 do very well, but those over 10 or those with flattening of the femoral head do not.
Avascular necrosis of the tarsal navicular (Kohler's disease) can be difficult to diagnose. Irregular ossification of tarsal bones is common and, when they occur in the absence of pain or swelling, the diagnosis should be that of a normal variant. However when there is pain or swelling, Kohler's disease is present. This disorder typically is seen in boys between 4 and 7 years. Pain is aggravated by running. Radiographs show a flattened navicular, which is radiodense and may appear fragmented. Bilateral changes occur commonly. For severe symptoms, a short walking cast (3-6 weeks) may be helpful. If asymptomatic, no treatment is needed.
Sever's disease results in a painful heel and limping. It is most common in active children between 9 and 12 years. The calcaneal apophysis joins with the secondary ossification center to form the posterior portion of the calcaneus. The Achilles tendon inserts onto the secondary ossification center. Stress on this insertion results in microfractures, which lead to inflammation and pain. Although it was previously held that the fragmentation and sclerotic changes seen on lateral radiographs of the calcaneal apophysis were diagnostic of this condition, it is now thought these changes represent one of several normal patterns for ossification. The diagnosis is now made on clinical grounds with a typical history and tenderness at the insertion of the Achilles tendon. Treatment may include heel pads or Achilles stretching prior to participation in sports. Ice may also be of benefit following exercise. Refer to Case 20 in Volume 1, Sever's Disease.
Osgood Schlatter's disease is characterized by pain just below the knee in the vicinity of the tibial tuberosity. This disease is felt to be due to repeated microtrauma to the insertion of the patella tendon, similar to Sever's disease. It occurs most often in adolescent boys during accelerated growth. The diagnosis is made based on the presence of tenderness to palpation over the tibial tuberosity. The tuberosity may be more prominent. No effusions should be found and the pain should be exacerbated by forced extension against resistance or jumping repetitively. Resolution occurs when the secondary ossification center fuses to the proximal tibia, which occurs with maturation. Treatment is limiting activity and also may involve immobilization and anti-inflammatory medications.
Slipped capital femoral epiphysis (SCFE) is a medial or posterior slipping of the femoral capital epiphysis. It often presents with a limp. This diagnosis is difficult to make and is often delayed. SCFE patients are usually overweight or have had a significant shear stress applied to the femoral head. SCFE will often present with knee pain, thigh pain, groin pain, or hip pain. SCFE should be considered when pain in one of these areas is present. Physical exam finds the hip externally rotated with painful range of motion, especially to internal rotation, abduction and flexion. Early symptoms may be subtle. Delaying the diagnosis results in worsening of the condition and a poorer outcome. Refer to Case 10 in Volume 2, Thigh and Knee Pain in an Obese 10-Year Old.
Osteochondritis dessicans is a disease in which a small island of bone dies and is then sloughed. Typically, the child complains of poorly localized knee pain. Osteochondritis dessicans commonly presents in the preteen or early adolescent. Pain with full flexion is usually found. If there is a piece of sloughed bone, one may find an effusion. Locking of the knee can occur while in flexion. Typically involving the distal femur, osteochondritis dessicans can be easily identified on plain AP radiographs of the femur. Treatment starts with immobilization. Isometric exercises may help retain quadriceps tone. Arthroscopic surgery is indicated for continued pain.
Freiberg's disease is another example of avascular necrosis. This time the second metatarsal is involved. Treatment for this one is use of a shoe insert to ease weight bearing. Other osteochondroses such as Scheurmann's (involving the spine) or Ashman's (involving the 5th metatarsal) can present as limping.
Neuromuscular conditions include any disease causing weakness in the hip girdle or lower spine or extremities which can present as limping. The reader is referred to standard neurology texts for more discussion on the myopathic or neuropathic entities.
Miscellaneous causes include sickle cell disease, hemophilia, tarsal coalition, Blount's disease, conversion reactions/hysteria, and growing pains.
Blount's Disease is a major cause of angular deformation in children. It is also called infantile tibia vara and results from some problem with the growth of the posteriomedial aspect of the tibial physis. Physiologic bowing usually has resolved by age 3, but Blount's disease advances to more severe angulation. Bracing is needed for those children between 14 and 30 months if the metaphyseal-diaphyseal angle is 9 to 16 degrees and the knee is unstable when walking. Tarsal coalition is a congenital disorder that results in a vertical talus with a fixed foot deformity. Patients usually present with foot pain and limping.
Conclusion: Limping is a common symptom found in pediatric patients. The evaluation of these patients requires a careful history and detailed examination. There are many other sources which discuss limping.
References