Achondroplasia: recent advances in diagnosis and treatment

Surgical outcome after treatment of thoracolumbar spinal stenosis in adults with achondroplasia

PURPOSE

To describe the complications and the outcome of patients with achondroplasia undergoing thoracolumbar spinal surgery.

METHODS

Retrospective analysis of prospectively collected data of all patients with achondroplasia undergoing surgery within the years 1992-2021 at the thoracic and/or lumbar spine. The outcome was measured by analyzing the surgical complications and revisions. The patient-rated outcome was assessed with the COMI score from 2005 onwards.

RESULTS

A total of 15 patients were included in this study undergoing a total of 31 surgeries at 79 thoracolumbar levels. 12/31 surgeries had intraoperative complications consisting of 11 dural tears and one excessive intraoperative bleeding. 4/18 revision surgeries were conducted due to post-decompression hyperkyphosis. The COMI score decreased from 7.5 IQR 1.4 (range 7.1-9.8) preoperatively to 5.3 IQR 4.1 (2.5-7.5) after 2 years (p = 0.046).

CONCLUSION

Patients with achondroplasia, the most common skeletal dysplasia condition with short-limb dwarfism, are burdened with a congenitally narrow spinal canal and are commonly in need of spinal surgery. However, surgery in these patients is often associated with complications, namely dural tears and post-decompression kyphosis. Despite these complications, patients benefit from surgical treatment at a follow-up of 2 years after surgery.

Skeletal development of achondroplasia: analysis of genotyped patients

BACKGROUND

Achondroplasia is a skeletal dysplasia caused by substitution of arginine for glycine at codon 380 (G380R) mutation of the fibroblast growth factor receptor 3. To date, the developmental course of the phenotype (short stature and skeletal characteristics) has not been clarified in the genotyped population.

METHODS

The relationship between age and clinical data (height, arm span and measurements of skeletal radiographs) were statistically analyzed from 27 achondroplasia patients with the G380R genotype.

RESULTS

The height standard deviation score had positive correlation and decreased with age, while span-to-height ratio did not. Among measurements of skeletal radiographs, the pelvic index, which represents the squared pelvis deformity, were correlated and increased with age. However, interpedicular distance of the first and fourth lumbar vertebrae (L1:L4) ratio as an index for the caudally narrowed pattern of the lumbar spinal canal and fibula-to-tibia ratio for the disproportionally long fibulae were not correlated and did not increase with age.

CONCLUSION

In making a clinical diagnosis of achondroplasia in early infancy, it should be noted that short stature and squared pelvis deformity are not prominent.

Molecular defects in achondroplasia and the effects of growth hormone treatment

Achondroplasia is a common skeletal dysplasia with severe growth retardation. Recently, mutations in the fibroblast growth factor receptor 3 (FGFR3) were identified in patients with achondroplasia. In the present study, 70 of 75 Japanese patients with achondroplasia were found to have a G1138A mutation in FGFR3, and two patients had a G1138C mutation. Growth hormone therapy was given to 145 patients with achondroplasia. Significant dose-dependent effects on skeletal growth were obtained, with no long-term adverse effects.