Importance of Radiographs in Diagnosing Metaphyseal Pathologies of the Knee Joint in an Era of Advanced Imaging

Purpose or Learning Objective: In the current scenario where radiologists increasingly depend on cross-sectional imaging, in this pictorial review we reinforce the role of conventional radiography in diagnosing and monitoring various metaphyseal abnormalities around the knee joint in pediatric patients. Radiographs are an easy investigation to monitor response to therapy for patients requiring follow-up.

Methods or Background: Twenty-five pediatric knee radiographs performed in a tertiary referral center were evaluated over a period of 2 years. The causes of metaphyseal abnormalities were broadly grouped into those causing (1) metaphyseal widening, (2) bulbous expansion, with deformed dysplastic metaphyses, (3) lytic and sclerotic metaphyseal bands, and (4) linear striations, along with (5) cortical-based lesions and (6) surface lesions. The final diagnosis was made after correlation with clinical history, laboratory parameters, histopathologic diagnosis when available, and assessment of other afflicted areas.

Results or Findings: A widened metaphyseal morphology appearing irregular/cupped/abnormally angulated with or without involvement of epiphysis was noticed in conditions such as spondyloepimetaphyseal dysplasias, metaphyseal chondrodysplasia, osteosclerotic metaphyseal dysplasia, rickets, and Blount’s disease. Causes of bulbous expanded and deformed metaphyses were enchondromatosis, mucopolysaccharidosis, achondroplasia, chondrodysplasia punctata, and Pyle’s disease. Lucent metaphyseal bands/areas were seen secondary to leukemia/lymphoma, infection, systemic illness, neuroblastoma, growth arrest lines, and also as a normal variant. Syphilitic osteomyelitis, osteopetrosis, lead poisoning, and osteogenesis imperfecta resulted in sclerotic bands within the metaphyses. A pattern of metaphyseal linear striations was seen in melorheostosis, osteopathia striata, and osteopoikilosis. Surface and cortical-based metaphyseal neoplastic etiologies were juxtacortical chondroma, chondromyxoid fibroma, lymphoma, parosteal/periosteal osteosarcoma, and chondrosarcoma.

Conclusion: The pattern recognition of metaphyseal abnormalities on radiographs helps radiologists make a reasonable diagnosis when faced with challenging conditions. Although radiography alone in some cases is insufficient and requires further evaluation, it helps to form an adequate preliminary opinion in most cases and eliminates the need for any further evaluation for many pathologies.

Publication History

Article published online:
22 May 2024