This post consists of links to and excerpts from the awesome A Systematic Approach to the Evaluation of a Limping Child [PubMed Abstract] [Full Text HTML] [Full Text PDF]. Am Fam Physician. 2015 Nov 15;92(10):908-16.
Please also review A prospective study of screening for musculoskeletal pathology in the child with a limp or pseudoparalysis using erythrocyte sedimentation rate, C-reactive protein and MRI [PubMed Abstract] [Full Text HTML] [Full Text PDF]. J Child Orthop. 2018 Aug 1;12(4):398-405. doi: 10.1302/1863-2548.12.180004.
Here are excerpts from A Systemic Approach:
A limp is defined as a deviation from a normal age-appropriate gait pattern resulting in an uneven, jerky, or laborious gait. It can be caused by pain, weakness, or deformity as a result of a variety of conditions. Transient synovitis is the most common diagnosis. Other causes of acute limp include contusion, foreign body in the foot, fracture, osteomyelitis, septic arthritis, reactive arthritis, and Lyme arthritis. Causes of chronic limp include rheumatic disease, dermatomyositis, acute rheumatic fever, inflammatory bowel disease, and systemic lupus erythematosus. Evaluation of a limping child should begin with a history focused on identifying pain, trauma, and associated systemic symptoms. For a limping child with focal findings on physical examination, initial imaging includes anteroposterior and
lateral radiography of the involved site. If there are no focal findings on physical examination, radiography of both
lower extremities should be performed. Laboratory testing is guided by history and physical examination findings.
Septic arthritis of the hip should be suspected in a child with an oral temperature more than 101.3°F (38.5°C), refusal
to bear weight, erythrocyte sedimentation rate more than 40 mm per hour, peripheral white blood cell count more
than 12,000 per mm3 (12 × 109 per L), or C-reactive protein level more than 20 mg per L (180.96 nmol per L). (Am Fam
Physician. 2015;92(10):908-916. Copyright © 2015 American Academy of Family Physicians.)