Guided growth for coronal lower limb deformities in skeletal dysplasia.

Coronal angular deformities of the lower limbs are common in young children with skeletal dysplasia . The guided growth technique has been applied to correct deformities in children, but there are few comprehensive reports on the effectiveness of the procedure in skeletal dysplasia. We reviewed 44 limbs of 22 patients with various types of skeletal dysplasias who underwent guided growth surgery. Fifteen varus and 29 valgus limbs were treated with 102 epiphysiodesis. The average age at surgery, at implant removal, and at the latest examination was 10.4 ± 3.6 years, 11.8 ± 3.7 years and 14.1 ± 4.4 years, respectively. The mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (mMPTA), lateral distal tibial angle (mLDTA) and mechanical axis deviation (MAD) were measured from standing anteroposterior radiographs of both lower limbs. The mLDTA, mMPTA and MAD were successfully improved after surgery. Moderate or severe deformities were observed in 100% of the varus and 83% of the valgus limbs preoperatively, whereas only 14% of the varus and 20% of the valgus limbs had residual deformities at the latest examination. Correction of deformities was limited in some older children. Fifteen limbs (34%) required repeated implantations due to recurrence or inverted deformity. The guided growth surgery is effective in correcting coronal angular deformities in children with skeletal dysplasia with a limited risk of complications. The timing of surgery and implant removal is critical in obtaining satisfactory correction and preventing recurrence or inverted deformities.

Two children with hypophosphatasia with a heterozygous c.1559delT variant in the ALPL gene, the most common variant in Japanese populations.

Hypophosphatasia (HPP), a genetic disorder characterized by decreased tissue-nonspecific alkaline phosphatase (TNSALP) activity, is caused by loss-of-function mutations in the ALPL gene, which encodes TNSALP. The most frequent pathogenic variant in Japanese patients with HPP is a frameshift mutation in the ALPL gene, c.1559delT, and its carrier frequency is reported to be one in 480 in the Japanese population. We report the cases of two Japanese children with HPP who had a heterozygous c.1559delT variant in the ALPL gene. One case (involving a neonate) exhibited respiratory insufficiency associated with vitamin B6 dependent convulsions, significant defective mineralization similar to the severe form of HPP, and extremely low ALP activity. Enzyme replacement therapy (ERT) using asfotase alfa promptly improved her respiratory insufficiency, bone mineralization, and maintained her motor development during infancy. The second case involved a 10-year-old boy who demonstrated diffuse musculoskeletal pain and weakness that progressively disturbed mobility. Although he showed no bony lesions, the clinical symptoms and biochemical abnormalities were compatible with childhood HPP. ERT successfully relieved the severe generalized pain and significantly improved motor function.