This study is a retrospective review of 41 patients (60 extremities) identified over a 40 year period at the Texas Scottish Rite Hospital and the St. Louis Shriners Hospital that were previously categorized as a phocomelia. The authors have reclassified these patients as representing a more severe form of longitudinal dysplasia. Twenty-nine limbs in 16 patients were reclassified as having characteristics consistent with a proximal radial longitudinal dysplasia including an abnormal glenoid and an absent proximal part of the humerus. They had a recognizable distal part of the humerus which articulated with the proximal part of the ulna associated with radial-sided hand abnormalities. Seven of these extremities were in patients with thrombocytopenia-absence radius syndrome, but additional musculoskeletal conditions were rare. Twenty limbs in 17 patients were reclassified as having characteristics consistent with a proximal ulnar longitudinal deficiency. These patients demonstrated a hypoplastic glenoid with a single arm/forearm bone that had the proximal characteristics of a humerus and the distal characteristics most similar to a radius. The bone was commonly bifurcated distally. The elbow joint was absent and there were carpal and hand abnormalities typical of the ulnar longitudinal deficiency. Associated musculoskeletal abnormalities such as proximal femoral focal deficiencies were common in these patients. Eleven limbs in 10 patients were identified as having severe combined dysplasia that were associated not only with congenital cardiac anomalies but also other musculoskeletal anomalies. The authors suggest that the classifications currently used for radial longitudinal dysplasia and ulnar longitudinal dysplasia be amended to include these severe dysplasias.
This study challenges the original classification provided by Frantz and O-Rahilly in 1961 and subsequently adopted by the ASSH in 1976. Multiple authors have since then have questioned this classification and this large series provides further evidence against the characterization of a transverse intercalated segmental dysplasia. These patients demonstrate severe upper extremity deformities which cannot be easily placed into the previous phocomelia classification. In addition, these extremities do not demonstrate true segmental deficits. They are typically abnormal throughout including that of severe hand deformities. In addition, many of these patients exhibited milder forms of longitudinal deficiencies on the contralateral side which would suggest that the deformities in the involved extremities represent severe manifestations in the continuum of longitudinal dysplasia. Although these new classification recommendations may not ultimately change treatment recommendations, it is more in keeping with the recent knowledge collected on genetic and developmental biological research. In addition, this classification may better allow clinicians to recognize associated systemic medical conditions or associated musculoskeletal conditions which may allow for more early diagnosis and appropriate treatment.
Phocomelia, Longitudinal, Dysplasia, Deficiency
Journal of Bone and Joint Surgery