Orthopaedic manifestations and management of spondyloepimetaphyseal dysplasia Strudwick type

Variant of the catalytic cysteine of UFSP2 leads to spondyloepimetaphyseal dysplasia type Di Rocco

Spondyloepimetaphyseal dysplasia (SEMD) is characterized by vertebral, epiphyseal, and metaphyseal alterations. Patients become predominantly apparent with disproportionate short stature. The genetic background of SEMD is heterogeneous, with different modes of inheritance (autosomal dominant, autosomal recessive, and X-linked disorders). Amongst the genes in which variants are known to cause SEMD, UFM1-specific protease 2 (UFSP2) encodes a cysteine protease involved in the maturation of Ubiquitin-fold modifier 1 (UFM1). Heterozygous pathogenic variants affecting the C-terminal catalytic domain of UFSP2 are related to two entities of skeletal dysplasia, Beukes hip dysplasia (BHD) and SEMD type Di Rocco (SEMDDR). This is the first report of a de novo heterozygous variant affecting the catalytic Cys302 residue of UFSP2 (NM_018359.3:c.905G>C, p.(Cys302Ser)) causing SEMDDR. According to previously described patients with SEMDDR, our patient presented with disproportionate short stature, genu varum, gait instability, and radiologically detected epiphyseal and metaphyseal alterations. Additionally, a bell-shaped thorax, lumbar hyperlordosis, muscular hypotonia, and coxa vara were observed in the patient described in this study. Our findings underline the fundamental importance of an intact catalytic triad of the human UFSP2 for normal skeletal development and extend the phenotypical features of patients with UFSP2-related skeletal dysplasia.

[Short-term outcomes of total hip arthroplasty in the treatment of Tönnis grade 3 hip osteoarthritis in patients with spondyloepiphyseal dysplasia]

OBJECTIVE

Severe hip osteoarthritis, caused by bone or joint maldevelopment, biomechanical transformation and previous surgical intervention, is inclusively existed in spondyloepiphyseal dysplasia (SED). To investigate and discuss the short-term efficacy and possible effects of total hip arthroplasty in the treatment of Tönnis grade 3 hip osteoarthritis in patients with SED.

METHODS

From January 2017 to June 2019, 374 patients with hip osteoarthritis were involved for total hip arthroplasty conducted by senior professional surgeons, of whom 9 patients (6 males and 3 females) with 12 hip osteoarthritis secondary to the SED met the inclusive and exclusive criteria and received the above-mentioned hip operation. The short-term outcomes were observed.

RESULTS

All the patients were implanted with Johnson & Johnson ceramic on ceramic cementless hip prostheses within the arthroplasty. They were followed up for an average period of 20 months. Except for one muscular calf vein thrombosis case, no complications, such as aseptic loosening, joint dislocation, fracture, neurovascular injury, deep vein thrombosis and infection were observed in all the 9 patients. Before the surgery, the average Harris hip score was 35.55, while the average of the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) was 56.56. The level of quality of life indicated by SF-12 score was 41.56 on average. The mean pre-operation visual analogue scale (VAS) was 7.44. At the last follow-up, the average Harris hip score increased to 89.56, whereas the average WOMAC declined to 41.11. Compared with the baseline point, the average SF-12 score went up to 56.33. Dramatic drop of the mean VAS value to 2.67 was also observed at the last follow-up. In addition, post-operative increase of several pelvic-related parameters including pelvic incidence, pelvic tilt and sacral slope could be observed in the SED patients. The average measured pelvic incidence, pelvic tilt and sacral slope were 68.95°±4.60°, 52.75°±1.06° and 17.45°±1.77° before operation, respectively; whilst the mean value of these specific parameters increased to 76.98°±5.12°, 60.51°±4.35° and 18.10°±2.02°, respectively. The even leg lengths of the lower extremities were obtained after total hip arthroplasty.

CONCLUSION

Total hip arthroplasty is satisfactory in the short-term pain relieve and function recovery for the management of Tönnis grade 3 hip osteoarthritis secondary to the SED.

UFSP2-related spondyloepimetaphyseal dysplasia: A confirmatory report

Spondyloepimetaphyseal dysplasias (SEMDs), which comprise a heterogeneous group of autosomal-dominant, autosomal-recessive and X-linked recessive disorders, are characterized by anomalies of the spine, the epiphyses and metaphyses of the long bones, resulting in short stature and osteoarthritic changes of the joints. UFSP2 gene encodes a highly conserved cysteine protease which cleaves two C-terminal residues from ubiquitin-fold modifier 1, an ubiquitin-like post-translational modifier protein. In 2018, Di Rocco, M reported for the first time that a novel heterozygous variant exon 11: c.1277A > C of the UFSP2 gene was the cause to spondyloepimetaphyseal dysplasia mainly manifested as: short stature, anterior vertebral dysplasia, hip dysplasia, flat vertebra, spinal metaphyseal dysplasia, irregular acetabular apex, distal femoral metaphyseal dysplasia, proximal tibial metaphyseal dysplasia, osteoarthritis and so on. In this report, we describe a boy with spondyloepimetaphyseal dysplasia due to a novel mutation exon 11: c.1283A > G (leading to p. H428R) of the UFSP2 gene. This is the second report to describe children with SEMDs associated with an UFSP2 variant. However, it is the first to describe a UFSP2 gene mutation exon 11: c.1283A > G (leading to p. H428R). Our findings of a novel heterozygous mutation of UFSP2 gene add to the list of 2 reported heterozygous mutations of UFSP2 which led to hereditary osteopathy.

High Prevalence of Growth Plate Gene Variants in Children With Familial Short Stature Treated With GH

CONTEXT

Familial short stature (FSS) is a term describing a growth disorder that is vertically transmitted. Milder forms may result from the combined effect of multiple genes; more severe short stature is suggestive of a monogenic condition. The etiology of most FSS cases has not been thoroughly elucidated to date.

OBJECTIVES

To identify the genetic etiology of severe FSS in children treated with GH because of the diagnosis of small for gestational age or GH deficiency (SGA/GHD).

DESIGN, SETTINGS, AND PATIENTS

Of 736 children treated with GH because of GHD/SGA, 33 with severe FSS (life-minimum height -2.5 SD or less in both the patient and shorter parent) were included in the study. The genetic etiology was known in 5 of 33 children prior to the study [ACAN (in 2], NF1, PTPN11, and SOS1). In the remaining 28 of 33, whole-exome sequencing was performed. The results were evaluated using American College of Medical Genetics and Genomics standards and guidelines.

RESULTS

In 30 of 33 children (90%), we found at least one variant with potential clinical significance in genes known to affect growth. A genetic cause was elucidated in 17 of 33 (52%). Of these children, variants in growth plate-related genes were found in 9 of 17 [COL2A1, COL11A1, and ACAN (all in 2), FLNB, FGFR3, and IGF1R], and IGF-associated proteins were affected in 2 of 17 (IGFALS and HMGA2). In the remaining 6 of 17, the discovered genetic mechanisms were miscellaneous (TRHR, MBTPS2, GHSR, NF1, PTPN11, and SOS1).

CONCLUSIONS

Single-gene variants are frequent among families with severe FSS, with variants affecting the growth plate being the most prevalent.

Molecular genetics of the COL2A1-related disorders

Type II collagen, comprised of three identical alpha-1(II) chains, is the major collagen synthesized by chondrocytes, and is found in articular cartilage, vitreous humour, inner ear and nucleus pulposus. Mutations in the collagen type II alpha-1 gene (COL2A1) have been reported to be responsible for a series of abnormalities, known as type II collagenopathies. To date, 16 definite disorders, inherited in an autosomal dominant or recessive pattern, have been described to be associated with the COL2A1 mutations, and at least 405 mutations ranging from point mutations to complex rearrangements have been reported, though the underlying pathogenesis remains unclear. Significant clinical heterogeneity has been reported in COL2A1-associated type II collagenopathies. In this review, we highlight current knowledge of known mutations in the COL2A1 gene for these disorders, as well as genetic animal models related to the COL2A1 gene, which may help us understand the nature of complex phenotypes and underlying pathogenesis of these conditions.

The hip in osteochondrodysplasias: general rules for diagnosis and treatment

The management of hip pathology in osteochondrodysplasia (skeletal dysplasia) is complex and a multidisciplinary approach is vital. Thorough clinical assessment and knowledge of the natural history of the different disorders provides the basis for this.

Coxa vara in chondrodysplasia: prognosis study of 35 hips in 19 children

BACKGROUND

To better understand anatomical and functional outcomes of coxa vara in chondrodysplasia according to the initial presenting hip morphology, disease type, and impact of surgery.

METHODS

Clinical and radiographic records of 19 children (35 hips) diagnosed with coxa vara and with osteochondrodysplasia were reviewed. We classified the hip radiographic findings into 2 groups: (a) group I, coxa vara with a fragmented and/or nonossified head; and (b) group II, coxa vara with a regular femoral head. Surgical indications in coxa vara included decreased range of hip motion (usually diminished abduction, extension, and internal rotation), coxa vara with progression documented on regular follow-up hip radiographs, and/or severe coxa vara with a Hilgenreiner epiphyseal angle (HEA) of 60 degrees or more. Follow-up was until the completion of growth and, for some patients, into early adulthood. Mean follow-up was 8 years.

RESULTS

Twenty-five hips were operated on in 13 patients. In 23 hips, the procedure was a valgus osteotomy fixed by pins and wire. A pelvic extension osteotomy without valgus osteotomy was performed in one patient (2 hips). Coxa vara recurred in 7 hips. In 4 of these hips, repeat surgery with hypervalgus osteotomy was indicated to stop epiphyseal slipping (3 hips) or to improve the arc of motion (1 hip). Functional outcomes were poor in coxa vara associated with poor epiphyseal development (nonossified or fragmented epiphysis) as seen in spondyloepiphyseal dysplasia congenita, spondyloepimetaphyseal dysplasia, Kniest disease, and multiple epiphyseal dysplasia. Coxa vara with physeal instability as observed in spondylometaphyseal dysplasia resulted in deformity recurrence postoperatively during growth. In contrast, outcome was better in cases of coxa vara with nonphyseal/nonepiphyseal involvement, that is, good femoral head morphology, stable physis, and good articular cartilage, as seen in cases of metaphyseal dysplasia and cleidocranial dysplasia.

CONCLUSIONS

Coxa vara with physeal and epiphyseal involvement and severe impairment of the articular cartilage has a poor prognosis even after reconstructive surgery. In coxa vara with an abnormal physis, there were numerous postsurgical recurrences of the deformity during growth if the physis was not stabilized at the time of valgus osteotomy. In these cases, we should delay osteotomy until an HEA greater than 60 degrees. Coxa vara in which only the metaphysis of the femoral neck is involved, the deformity is milder and often requires no treatment. Indications for surgery in this group are increasing coxa vara, Trendelenburg gait, or an HEA greater than 60 degrees.