Fig. 15.1
MRI of the right hip shows an osteoid osteoma at the upper metaphyseal end of the right femur
This case illustrates several learning points:
- (a)
Many cases of limp or limb pain are attributed to trauma which actually is insignificant or eventually irrelevant to the final diagnosis [1].
- (b)
Nocturnal pains should alert one to the possibility of osteoid osteoma or malignancy and specifically pains that wake up a child at night argue against functional causes.
- (c)
Subtle physical findings – in this case, the mild wasting of the mid thigh can give a clue to the diagnosis in cases of limp.
- (d)
Pain originating in the region of the hip may be referred to the knee [2].
- (e)
Targeted investigation after localizing the origin of the pain easily reveals the diagnosis in most cases (MRI of the hip revealed the pathology in this boy).
- (f)
Last but not the least, investigation and approach to a limping child are best performed by a specialist with experience in musculoskeletal medicine with the help of an orthopedic surgeon being sought in select cases, most often after a diagnosis [3].
Introduction
A limp is defined as any deviation in the walking pattern away from the expected normal for the child’s age [4]. The causes range from simple and benign as ill-fitting new shoes or a plantar wart or strain/sprain to potentially devastating diagnoses such as septic arthritis or even malignancy. This chapter details the causes of a limp in a child and broadly categorizes them based on their underlying causation into a painless or painful limp. A careful history and physical examination are often all that are necessary to arrive at a final diagnosis in several cases [5]. In the rest, they provide a direction to investigate and identify the cause. The bedside approach is discussed in detail.
Epidemiological Data from India and Abroad
The exact incidence of limping in children in India is not known. A study of 243 children, from Scotland, less than 14 years of age presenting to the emergency department for acute atraumatic limp, reported an incidence of 1.8 per 1000 children, with a male-to-female ratio of 1.7:1 and a median age of 4.4 years [6]. Limb involvement was almost equal and it was painful in 80 % of the children. The predominant diagnosis was transient synovitis of the hip (TSH) in 39.5 % and Legg-Calve-Perthes disease (LCPD) accounted for 2%. Uniquely in our country, the referral pathways (either by self-referral or by family physician) lead many children to see the orthopedic surgeon as a point of first contact even though orthopedic causes account for only a fraction of the cases.
The Normal Gait
In order to understand and approach limp better, it is important to have a basic understanding of the physiology of gait. The normal child begins to walk at 12–14 months of age. Initially it is normal for the child to walk with a wide-based externally rotated gait, taking numerous short steps. The gait then undergoes orderly stages of development. Walking velocity, step length and the duration of the single-limb stance increase with age and the number of steps taken per minute decreases. A mature gait pattern is well established by about 3 years of age and the gait of a 7-year-old child resembles that of an adult [7] (Fig. 15.2). A normal mature gait cycle consists of the stance phase, during which the foot is in contact with the ground and the swing phase, during which the foot is in the air.
Fig. 15.2
The normal gait cycle
Etiopathology of Limping
Limping Can Be Caused by Three Categorical Processes [8, 9]
- 1.
Painful (antalgic gait): The child attempts to minimize support time on the painful limb resulting in a decreased stance phase of the affected limb and a compensatory increased stance phase on the opposite side. The pain could originate from any of the anatomical structures of the limb or even the abdomen and can be traumatic, infectious, inflammatory or neoplastic in origin.
- 2.
Nonpainful (Trendelenburg gait): Here the stance phase is equal between involved and non-involved limbs, but the child leans or shifts toward the involved limb to balance. This gait is indicative of proximal muscle weakness or hip instability. The causes may be congenital or acquired such as limb length discrepancies, limb deformities, muscle contractures or shortened tendons.
- 3.
Neuromuscular problems (including weakness or ataxia – cerebellar or sensory): Unsteady gait can be a result of muscle injury, inflammation or dystrophy, or a focal lesion in the central or peripheral nervous system affecting either proprioception or motor control.
Causes of Limp by Anatomic Site of Origin
Limp can be best classified by the anatomic site of origin (Table 15.1) [4, 8, 9]. The division of the causes into common, less common and rare is based on the perception of a primary care pediatrician.
Table 15.1
Causes of limp by anatomical origin
Anatomical origin | Common | Less common | Rare |
|---|---|---|---|
Skin/soft tissue | Impacted foreign bodies Thorn/splinter | ||
Muscle, ligament, entheses | IM injections, sprain, strain, and sports injuries | Viral myositis | Juvenile dermatomyositis ERA |
Bones | Trauma Occult fracture, toddler abuse Vitamin D3 deficiency | Leukemia Osteoid osteoma Osteomyelitis Leg length discrepancy Unicameral bone cyst | Caffey disease Osteosarcoma Ewing sarcoma |
Neurological | Cerebral palsy | Guillain-Barre syndrome | Polio Zoster Polyarteritis nodosa Spinal cord diskitis |
Vaso-occlusive | Vasculitis-HSP | Deep vein thrombosis | Rarer vasculitides |
Joints (hip alone) | Transient synovitis (TSH) Reactive arthritis | LCPD SCFE Tuberculosis DDH AVN – femoral head | Septic arthritis Protrusio acetabuli |
Joints (knee alone) | Reactive Overuse Osgood-Schlatter disease Chondromalacia patellae | Juvenile psoriatic arthritis OJIA | Coagulopathy |
Joints (ankle, subtalar alone) | Tuberculosis Tumor Tarsal coalition | ||
Joints (multiple) | Postinfective including RF Reiter’s syndrome | PJIA OJIA ERA SLE | |
Functional | Conversion reaction | RSD |
Approach to a Child with Limp
The approach to rheumatologic and musculoskeletal etiology of limp is as follows [4, 5, 8–11]:
Ask: A thorough history is to be obtained from parents and child (as appropriate). An incomplete history and an uncooperative patient pose a significant challenge. Table 15.2 lists the questions to be asked with possible etiologies.
Table 15.2
Approach to a child with limp – ASK
What
Why
Age
1–4 years – DDH, OJIA, TSH, leg length discrepancy
4–10 years – TSH, LCPD
Adolescent – overuse (sports), SCFE
Sex
Male – coagulopathies (X-linked recessive), SCFE,
Osgood-Schlatter disease, ERA, TSH
Female – OJIA, PJIA, chondromalacia patellae
Trauma (significant vs. insignificant)
IM injections
Accidental vs. recurrent
Danger in attributing a limp to trauma and missing a potentially significant diagnosis
Recurrent – consider non-accidental injury
Onset
Acute (hours to days) – trauma, coagulopathies, TSH, vaso-occlusive, septic arthritis
Subacute (days to weeks) – viral myositis, reactive arthritis, osteomyelitis, malignancy
Chronic (weeks to months) – JIA, SCFE, malignancy
Type of pain (if child is capable of describing)Related posts:
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