Limping in a Pandemic

Introduction: Transient synovitis is a common cause of hip pain in children. Patients present with acute limp, hip pain or referred pain to the knee. The mainstay of treatment consists of anti-inflammatory medications and activity limitations. While the exact etiology of transient synovitis is unknown, there has been a noted relationship with an antecedent viral illness. We present one of the first reported cases of transient synovitis caused by COVID-19.

Case Description: A 10-year-old male presented with concerns for left knee pain and limp. Five days prior, the patient developed general URI symptoms and was diagnosed with COVID-19, via rapid testing. His maximum temperature was 38.5°C at home and his respiratory symptoms resolved. Two days prior to presentation, he complained of left knee pain, which progressed to limp, and refusal to bear weight. He denied known injuries, trauma, visible bruising, swelling, redness, or warmth.
He was afebrile and non-weight-bearing on his left leg, otherwise in no apparent distress. On physical exam, he exhibited full, painless range of motion of left knee, no bony tenderness, effusion, or cutaneous changes. There was refusal to bear weight on left leg, and significant pain with internal rotation of left hip.
Lab work revealed there was no leukocytosis. C-reactive protein level and sedimentation rate were unremarkable. Radiographs of bilateral hip and pelvis, and left knee were obtained, which revealed no osseous abnormalities or significant effusion. Patient was given ibuprofen and on follow up exam he exhibited improved discomfort and willingness to bear weight.
With a negative workup and clinical improvement, he was discharged with crutches, instructions for supportive care, and outpatient follow-up. Mother reported no complications during his recovery. He was able to wean from the crutches within a few days and returned to his usual gait within 3 weeks.

Discussion: Transient synovitis can be clinically distinguished from septic arthritis with features of overall well appearance, lack of swelling or redness to the joint, and normal range of motion with mild pain. For our patient, Kocher criteria were helpful in distinguishing transient synovitis from septic arthritis, as well as the clinical improvement with NSAIDs. A clinical dilemma could occur if elevated inflammatory markers were present, as one might expect with acute COVID-19. Though transient synovitis is thought to be related to a viral etiology, there does not appear to be an increase in cases amidst the pandemic described in published literature.

Conclusion: This case illustrates a patient who had COVID-19 with transient synovitis, a previously unreported sequela. When evaluating similar patients, providers should consider the possibility of COVID-19 and ensure appropriate testing and isolation.