Clinical and radiological characteristics of forearm deformities in children with multiple hereditary exostoses

Genij Ortopedii, Vol. 25, no 4, 2019 © Zakharyan E.A., Belousova E.A., Pozdeev A.P., 2019 DOI 10.18019/1028-4427-2019-25-4-487-492 Clinical and radiological characteristics of forearm deformities in children with multiple hereditary exostoses E.A. Zakharyan1, E.A. Belousova2, A.P. Pozdeev1 The Turner Scientific and Research Institute for Children’s Orthopedics, Saint Petersburg, Russian Federation 2 North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russian Federation 1 Introduction The incidence of forearm deformities in children with multiple hereditary exostoses (MHE) ranges from 30 to 80 %. There are few studies of deformities of the forearm in MHE patients in the literature that describe not only the location of exostoses and position of the head of the radius but also the true variants of forearm deformities. The aim of the study was to investigate forearm bone deformities in patients with multiple hereditary exostoses. Materials and methods Radiographs of the bones of the forearm in 84 patients (151 limbs) diagnosed with multiple hereditary exostoses in the age of four to 17 years who were treated at our institute from 2004 to 2018 were retrospectively analysed. The study involved 47 boys and 37 girls; 67 patients (80 %) had bilateral lesions, and 17 patients (20 %) had lesions of only one upper limb. Patients were divided into four groups depending on the type according to the Jo& Jung’s classification. The deformities were evaluated based on radiological methods in accordance with the reference lines and angles for the forearm bones. Results The most common variants of forearm deformities were revealed: varus recurvatum at the border of the upper and middle third of the ulna (55 %), varus recurvatum at the border of the upper and middle third of the ulna associated with varus of the radius in the middle third (15 % of cases); as well as their combinations accompanied by dislocation or subluxation of the radial head (30 %). RAA (radial articular angle) and RB (radial bowing) did not have significant difference in various types of deformities of the forearm according to Jo&Jung’s classification. Conclusion The study of the variety of forearm deformities in children due to multiple hereditary exostoses will assist in a differentiated approach to the choice of surgical treatment methods depending on the type of deformity. Keywords: multiple hereditary exostoses, forearm deformities, classification INTRODUCTION Multiple hereditary osteochondromas (HMO) also known as multiple hereditary exostoses (HME) is a genetic autosomal dominant inherited disorder of the human skeleton; primary spontaneous mutations are observed in 20 to 30 % of cases. Its incidence is 1:50,000 newborns. The pathology may manifest itself already in infants of the first year of life. Multiple osteochondromas is a frequent pathology in the pediatric practice. Its incidences make from 16 to 43 % of all cases of tumours, tumour-like and dysplastic bone diseases, as reported. Deformities of forearm develop due to multiple exostoses in 30 to 80 % of cases: ulnar (83 %) and radial (17) club hand among them [1, 2, 3]. Limb length discrepancy, angular deformities, and decrease in the range of motion in the adjacent joints as well as pain due to local irritation of muscles, tendons and nerves due to exostosis are observed. Progression of angulation may result in instability in the elbow and wrist joints. Three classifications that reflect deformities of the forearm bones due to HMO were found in the literature sources on this topic. The classification developed by A.P. Pozdeev and L.Yu. Khodzhaeva is based on the ulnar deviation of the hand, restriction of movements in the adjacent joints, presence/absence of deformities of the bones of the forearm, magnitude of the forearm shortening, presence/absence of rotation restriction, decentering /subluxation /dislocation of the radial head. Thus, they distinguish five grades of ulnar club hand [3]: Grade I: ulna deviation within 10–15°. The hand acquires its central position actively or passively, full range of motion in the adjacent joints; Grade II: ulna deviation up to 30°. The hand acquires its central position actively or passively; there is arch-like deformity of the forearm bones and its shortening up to 2.5 cm; restricted rotation due to decentering and radial head subluxation;  Zakharyan E.A., Belousova E.A., Pozdeev A.P. Clinical and radiological characteristics of forearm deformities in children with multiple hereditary exostoses. Genij Ortopedii, 2019, vol. 25, no 4, pp. 487-492. DOI 10.18019/1028-4427-2019-25-4-487-492. (In Russian) Original Article 487 Genij Ortopedii, Vol. 25, no 4, 2019 Grade III: ulna deviation is more than 30°. The hand does not acquire the centered position; forearm bones deformity and its shortening up to 3 cm, sharp restriction of rotation due to subluxation and full dislocation of the radial head; Grade IV: ulnar deviation more than 30°; the hand does not acquire the centered position; full dislocation of the radial head; deformities of both forearm bones; rotation within 10–15°; Grade V: ulnar deviation not more than 30°, lesions of distal parts in both bones; dislocation of the redial head; deformity of the metadiaphyses of both bones; considerable shortening of the segment, muscle hypotrophy, flexion contracture of fingers. The second classification was developed by Masada and Ono, and evaluates the relationship of osteocartilaginous exostoses location and presence/ absence of radial head dislocation (Fig. 1) [4, 5]: Type I: osteocartilaginous exostoses are located in the distal ulna and there is no radial head dislocation; Type IIА: radial head dislocation and osteocartilaginous exostoses in the proximal methaphysis of the radius, shortening of the ulna; Type IIВ: osteocartilaginous exostoses are located in the distal ulna associated with radial head dislocation, no ulna shortening; Type III: osteocartilaginous exostoses are located in the distal radius, without radial head dislocation, shortening of the radius. Type IV: osteocartilaginous exostoses located in the distal parts of both bones Type IVA: osteocartilaginous exostoses located in the distal parts of both forearm bones combined with radial head dislocation; Type IVB: osteocartilaginous exostoses located in the distal parts of both forearm bones without radial head dislocation (Fig. 2) [7]. Fig. 2 Schematic presentation of anatomical abnormalities in accordance with the classification of Jo A.R., Jung S.T. (2017) However, these classifications do not fully disclose the entire variety of deformities of the forearm bones in children due to osteocartilaginous exostoses, but indicate only the location of exostoses and the position of the head of the radius. Thus, a combination of radial head dislocation with multiplanar deformities of the forearm bones leads to limitation of rotation and loss of function of the uppe (...truncated)