Teaching Case

A healthy 13-month-old boy from the Gambia presented with acute pain in his right hand/foot following a fall injury seven weeks earlier. Radiographs detected a subacute tibial fracture and possible fracture sequelae in the 3rd metacarpal/1st metatarsal bone. Acute admission and skeletal survey were performed for suspected child abuse.

Radiographs of hand and foot depict deformed phalangeal, metacarpal and metatarsal bone structure with sclerosis, osteolysis and periosteal reaction (Fig. 1 and2). In addition, there is a subacute distal tibial fracture with periosteal reaction. There is no evidence of osteopenia, although it is not a radiographic diagnosis (Fig. 3). The skeletal survey revealed no other pathology.
Five months later, magnetic resonance imaging (MRI) diagnosed chronic osteomyelitis in the right 3rd metacarpal bone with a ‘cloaca’ related to extensor tendons (Fig. 4).

Background: Sickle cell disease (SCD) is an autosomal recessive multisystemic disorder due to chronic haemoglobinopathy. Anaemia, vaso-occlusion and superimposed infection are dominant features of the disease, which shows a high prevalence in sub-Saharan Africa, Mediterranean Basin, Middle East and India [1]. Major clinical SCD findings are acute vaso-occlusive pain/thrombosis in different organs and infections, partially due to hyposplenism [1].
Clinical perspective: Musculoskeletal abnormalities develop as a result of chronic anaemia with bone infarctions/osteomyelitis. The resulting bone marrow remodelling and osteopenia may predispose to pathological fractures [2-4]. Bone infarction caused by sickling of red blood cells typically occurs in long bone medullary cavities and epiphysis, commonly in the femoral head. In children, infarction commonly presents as “hand-and-foot” syndrome or dactylitis.
Imaging perspective: Radiography reveals areas of diaphyseal lucency, periosteal reaction or even osteolysis/deformity leading to growth disturbances. It can fail to depict osteomyelitis and/or infarction in early stages [2].
MRI is sensitive for the detection of initial bone marrow oedema where T2-weighted fat-saturated sequences reveal osteomyelitis with high-signal intramedullary oedema/fluid, eventually sequestra and a communication between intra- and extraosseous compartments, known as ‘cloaca’. Gd-enhanced T1-weighted images demonstrating irregular peripheral bone marrow enhancement favour osteomyelitis over infarction. Image-guided needle aspiration is a valuable tool to distinguish septic arthritis from non-pyogenic intraarticular fluid [2].
Outcome: In musculoskeletal SCD manifestations, acute dactylitis is usually a clinical diagnosis managed with hydration, analgesics and a warm cover. Preventive medical therapy for SCD with hydroxyurea may be indicated and stem cell transplantation considered [5].
Teaching point: When fractures present in small children with an unclear history of trauma, non-accidental injury should always be considered. In this case, the fractured tibia raised the serious concern of child abuse, however additional imaging revealed skeletal abnormalities with fracture type, site and healing not typical for abuse. Possible underlying conditions should be kept in mind such as, in this case, undiagnosed sickle cell disease that caused dactylitis combined with a pathologic fracture.

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