Modified gradual ulnar lengthening for treatment of Masada type IIb forearm deformity in children with hereditary multiple osteochondromas

To investigate the effect of modified gradual ulnar lengthening in the treatment of Masada type IIb forearm deformity in children with hereditary multiple osteochondromas (HMO). From May 2015 to October 2020, 12 children with Masada type IIb forearm deformity caused by HMO underwent modified gradual ulnar lengthening in our hospital. Clinical and imaging data were retrospectively analyzed. Clinical evaluation included wrist flexion and extension, wrist ulnar and radial deviation, forearm pronation and supination, and elbow range of motion. The radiographic parameters measured included the radial articular angle, carpal slip, and relative ulnar shortening. The mean operative age of the 12 patients (9 male, 3 female) was 8.5 ± 2.7 years, the mean follow-up was 31.5 ± 5.7 months, and the mean ulnar lengthening was 43.3 ± 9.9 mm. There was no significant difference in the radial articular angle between the preoperative period and the last follow-up (from 36.5° ± 9.2° to 33.8° ± 5.1°, > 0.05). However, significant changes were found in carpal slip (from 61.3% ± 18.8% to 33.8% ± 20.8%) and relative ulnar shortening (from 5.8 ± 3.5 mm to -0.9 ± 4.85 mm) (