The presence of pain over an enthesis defines enthesitis and is a major (or sole) clinical feature of childhood spondyloarthropathies. However, the presence or degree of tenderness of the entheses in healthy children is unknown. We studied the prevalence of enthesalgia and pain thresholds over entheses in healthy children and whether these sites are different from those in patients diagnosed with seronegative enthesopathic arthropathy (SEA syndrome).
We examined 234 schoolchildren aged 8 to 16 years for enthesalgia; those reporting tenderness were compared to randomly selected patients with SEA syndrome previously diagnosed in a tertiary outpatient clinic.
Enthesalgia in at least one site was found in 68 children (29%). Schoolchildren had fewer sites than patients (mean 1.2 +/- 2.8 sites vs 8.1 +/- 4.5 sites; p < 0.0001). Enthesalgia was not associated with age, sex, or self-reported activity level. In schoolchildren, pressure thresholds were higher with age (p < 0.0001), and in boys (p = 0.014), and were decreased in those with enthesalgia (p = 0.003). The metatarsal heads had the lowest pain thresholds. Significant sites specific for SEA patients were: plantar fascial insertion (p < 0.0001), Achilles tendon insertion (p = 0.001), sacroiliac joint (p = 0.002), and inferior pole of the patella (p = 0.003). Of these 8 sites, only 10% of schoolchildren reported tenderness in 3 sites compared to 56% of children with SEA syndrome.
Enthesalgia is not rare in children; metatarsalgia or a limited number of tender entheses should not define enthesitis. Enthesalgia in 3 of the 8 specific tender entheses noted above may better define childhood enthesitis.