Cervical kyphosis in diastrophic dysplasia

Spinal Manifestations of Skeletal Dysplasia: A Practical Guide for Clinical Diagnosis

Skeletal dysplasias are a group of genetic conditions defined by atypical bone or cartilage growth and development. Skeletal abnormalities include short stature, limb deformity, joint contracture, and spinal deformity. Over 90% of disorders have a known genetic mutation that can definitively determine the diagnosis. As patients may present with a primary spinal concern, a careful clinical and radiographic evaluation can allow the physician to develop a working diagnosis to guide additional evaluation. Spinal manifestations include scoliosis and kyphoscoliosis, cervical instability, cervical kyphosis, thoracolumbar kyphosis, spinal stenosis, and atypical vertebral body morphology. An understanding of the affected conditions, prevalence, and natural history of these radiographic findings aids the orthopaedic surgeon in establishing a diagnosis and guides appropriate orthopaedic care.

Pediatric Cervical Kyphosis: A Retrospective Multicenter Analysis and Literature Review

Introduction

This study aims to investigate cervical kyphosis in children, which has gained increasing attention in recent years due to its higher incidence and its association with tumor surgeries, and to shed light on the unique anatomical and biomechanical differences between pediatric and adult populations regarding cervical sagittal alignment. Additionally, it explores the diverse causes and management approaches, which often pose significant challenges. Furthermore, this study presents the management outcomes from three spine centers in the Middle East.

Methods

A retrospective analysis was conducted on patient records from 2009 to 2021 in three centers located in Saudi Arabia, Egypt, and Jordan. Demographic and clinical data were collected, imaging studies were reviewed, and various treatment modalities and their corresponding outcomes were documented and analyzed. Additionally, a literature review on pediatric cervical kyphosis and its management was performed.

Results

Seventeen patients were included in this study. The average age at presentation was 11.9 years. Among the participants, 14 underwent surgical treatment, 1 was treated with Minerva orthosis, and 2 were observed. The mean follow-up period was 32.4 months. In surgically treated patients, a statistically significant higher degree of correction was achieved when combining anterior and posterior surgeries compared to performing standalone anterior or posterior surgery (P-value = 0.014).

Conclusions

Although rare, pediatric cervical kyphosis is a significant condition within the spectrum of pediatric deformities and frequently occurs as a component of syndromes or as a result of iatrogenic factors. Neck pain and myelopathy are the most commonly observed symptoms. Thorough evaluation and complex surgical interventions are typically required for most cases.

Neonatal Halter Traction for Severe Cervical Spine Deformity: A Technical Case Report With 2-Year Follow-up

BACKGROUND AND IMPORTANCE

Although rare, severe congenital cervical spine deformity can present with limited treatment options and potentially catastrophic outcomes. The use of halter traction for cervical deformity correction in children has been well described, but it has not been previously reported in the management of neonates.

CLINICAL PRESENTATION

A baby girl born at full-term gestation presented with generalized hypotonia, bilateral club feet, and significant right upper extremity weakness. Imaging demonstrated a severe congenital swan-neck deformity with spinal cord compression. Halter traction was initiated in the neonatal intensive care unit with subsequent neurological and radiographic improvement. After 7 days, traction was discontinued and she was placed in a custom-fitted cervico-thoracic orthosis. At 2 years of follow-up, she remains neurologically stable with maintained cervical alignment.

CONCLUSION

Halter traction followed by external bracing is technically possible in the neonatal period. For children with severe cervical congenital deformity, this technique can reduce spinal cord compression, provide significant deformity correction, and delay the need for definitive operative spinal stabilization.

SLC26A2-Associated Diastrophic Dysplasia and rMED-Clinical Features in Affected Finnish Children and Review of the Literature

Diastrophic dysplasia (DTD) is a rare osteochondrodysplasia characterized by short-limbed short stature and joint dysplasia. DTD is caused by mutations in SLC26A2 and is particularly common in the Finnish population. However, the disease incidence in Finland and clinical features in affected individuals have not been recently explored. This registry-based study aimed to investigate the current incidence of DTD in Finland, characterize the national cohort of pediatric subjects with DTD and review the disease-related literature. Subjects with SLC26A2-related skeletal dysplasia, born between 2000 and 2020, were identified from the Skeletal dysplasia registry and from hospital patient registry and their clinical and molecular data were reviewed. Fourteen subjects were identified. Twelve of them were phenotypically classified as DTD and two, as recessive multiple epiphyseal dysplasia (rMED). From the subjects with available genetic data, 75% (9/12) were homozygous for the Finnish founder mutation c.-26+2T>C. Two subjects with rMED phenotype were compound heterozygous for p.Arg279Trp and p.Thr512Lys variants. The variable phenotypes in our cohort highlight the wide spectrum of clinical features, ranging from a very severe form of DTD to milder forms of DTD and rMED. The incidence of DTD in Finland has significantly decreased over the past decades, most likely due to increased prenatal diagnostics.

Surgical Management of Pediatric Cervical Angular Kyphosis with 540° Approach and Metacarpal Plate: A Case Report and Introduction of a Novel Technique

Surgical decompression, deformity correction, and instrumentation of the upper cervical spine are challenging problems in cervical kyphosis, especially in infants and pediatrics. According to patients' age, surgical exposure is difficult and selecting the appropriate instrument for rigid fixation is crucial. In this article, we present a case of 2 years old with cervical angular kyphosis, which was approached posteriorly at first. Through posterior approach, C3–C5 laminectomy with complete excision of spinous process was performed. Then, the patient's position was changed to supine and C3–C5 corpectomies were performed anteriorly with a longitudinal incision, and the thecal sac was decompressed. A titanium cage with appropriate size and graft was placed after possible deformity correction conducted with head traction and neck extension. Anterior fixation was performed with two, 2-mm T-shaped metacarpal plates with two screws in C2 and four screws in C6. The patient's position was changed to prone again, and posterior fixation was done with two metacarpal plates located on lateral masses. We showed that a novel technique in correction and fixation of cervical kyphosis in pediatric is using metacarpal plates while they are fixed to lateral masses.

Best practice guidelines for management of spinal disorders in skeletal dysplasia

BACKGROUND

Disorders of the spine present a common and difficult management concern in patients with skeletal dysplasia. Due to the rarity of these conditions however, the literature, largely consisting of small, single institution case series, is sparse in regard to well-designed studies to support clinical decision making in these situations.

METHODS

Using the Delphi method, an international, multi-disciplinary group of individuals, with significant experience in the care of patients with skeletal dysplasia, convened to develop multi-disciplinary, "best practice" guidelines in the care of spinal disorders in patients with skeletal dysplasia.

RESULTS

Starting with 33 statements, the group a developed a list of 31 "best practice" guidelines.

CONCLUSIONS

The guidelines are presented and discussed to provide context for clinicians in their decision making in this often-challenging realm of care.

Cervical spine surgery in patients with diastrophic dysplasia: Case report with long-term follow-up

Cervical kyphosis in diastrophic dysplasia (DTD) is a very dangerous deformity which may lead to compression of neural structures resulting in tetraplegia or even. Treatment of this deformity is usually surgical, but no long-term follow-up studies are presented in the literature. Authors present a case of two children with DTD who underwent anterior corpectomy due to severe cervical kyphosis. The kyphotic deformity was corrected and the normal spinal canal width was restored. The effects of the correction remained stable for respectively 6 and 10 years of the follow-up period. The unique follow-up confirms that this type of intervention leads to an effective and long lasting results. Significant cervical kyphosis in patients suffering from DTD may be treated surgically using anterior approach even in young children with a favorable and lasting results.

Upper cervical spine fusion in children with skeletal dysplasia

BACKGROUND

Skeletal dysplasias have been associated with upper cervical instability. Many patients are initially asymptomatic, but the instability may progress to subluxation and dislocation and complications thereof, including death. Surgery is hampered by petite osseous structures and low bone formation rate.

AIM

To review the outcomes of surgical fusion of upper cervical instability in children with rare skeletal dysplasias.

MATERIAL AND METHODS

A retrospective study of eight children with five different rare skeletal dysplasias needing upper cervical instrumented stabilization. Cases were evaluated for clinical, radiologic, and quality-of-life outcomes, with median follow-up time of 5 years.

RESULTS

Six patients underwent posterior, segmental cervical spine instrumentation and fusion (three C1/C2 fusions, three occipitocervical fusions), one anterior cervical instrumented spinal fusion, and one anteroposterior fusion. Autogenous bone grafting was used in all patients, and seven were immobilized using a halo body jacket. Nonunion in occipitocervical fusions was common in these patients (3/8 patients). Rib autograft from occiput to cervical spine with recombinant human BMP-2 was used to salvage nonunions.

CONCLUSIONS

Surgical fixation in the pediatric cervical spine is hampered by fragile posterior structures. A postoperative immobilization by halo vest for 4 months is customary. Selective anterior corpectomy and plate fixation is not recommended in pediatric patients with skeletal dysplasias.

LEVEL OF EVIDENCE

Level 4, Case Series.

SLC26A2 disease spectrum in Sweden - high frequency of recessive multiple epiphyseal dysplasia (rMED)

Diastrophic dysplasia (DTD) is an autosomal recessive skeletal dysplasia caused by SLC26A2 mutations. Clinical features include short stature, joint contractures, spinal deformities, and cleft palate. SLC26A2 mutations also result in other skeletal dysplasias, including the milder recessive multiple epiphyseal dysplasia (rMED). DTD is overrepresented in Finland and we speculated that this may have influenced the prevalence and spectrum of SLC26A2-related skeletal conditions also in Sweden. We reviewed the patient registry at Department of Clinical Genetics, Karolinska University Hospital, Stockholm to identify subjects with SLC26A2 mutations. Seven patients from six families were identified; clinical data were available for six patients. All but one patient had one or two copies of the Finnish SLC26A2 founder mutation IVS1+2T>C. Arg279Trp mutation was present in compound heterozygous form in five patients with phenotypes consistent with rMED. Their heights ranged from -2.6 to -1.4 standard deviation units below normal mean and radiographic features included generalised epiphyseal dysplasia and double-layered patellae. Two rMED patients had hypoplastic C2 and cervical kyphosis, a severe manifestation previously described only in DTD. Our study confirms a high prevalence of rMED in Sweden and expands the phenotypic manifestations of rMED.

Scoliosis-Associated Cervical Spine Pathologies

STUDY DESIGN

A total of 126 scoliosis patients admitted to the hospital were screened for concomitant cervical pathologies.

OBJECTIVES

To investigate the prevalence of cervical spine pathologies and the clinical relevance of magnetic resonance imaging (MRI) in the evaluation of patients with neuromuscular, congenital, syndromic, and idiopathic scoliosis.

BACKGROUND SUMMARY

With the development of MRI, upper neural axis abnormalities such as syringomyelia and Chiari malformation are increasingly being found in patients with scoliosis, but no report in the literature describes other pathologies in the cervical area seen concomitant with different scoliosis types.

METHODS

A total of 126 consecutive patients who were classified as having neuromuscular, congenital, syndromic, and idiopathic scoliosis were retrospectively evaluated. Data regarding cervical neural axis abnormalities obtained from the MRI studies were analyzed and classified into each type of scoliosis group.

RESULTS

A total of 126 patients with scoliosis were evaluated for hindbrain and cervical spine anomalies. Patients were divided into 4 groups regarding the type of scoliosis. The cervical spine of all patients was evaluated with MRI and other radiologic methods when needed. The most frequently seen pathology was syringomyelia. Other pathologies found included congenital vertebral anomalies, Chiari malformation, arachnoid cyst, atlanto-axial dissociation, split cord, posterior vertebral fusion, vertebral hypoplasia, neurenteric cyst, myelomalacia, dermoid cyst, and decrease in craniovertebral angle. Cervical pathologies were most frequently seen in neuromuscular scoliosis, followed by congenital and syndromic groups.

CONCLUSIONS

Cervical spinal pathologies vary according to the type of scoliosis. The number of cervical spinal pathologies diagnosed in idiopathic scoliosis patients was least compared with neuromuscular and syndromic groups. The most common pathology was syringomyelia, followed by congenital vertebral anomalies and cerebral tonsillar hernia. Preoperative MRI scan provides vital information regarding cervical spinal pathologies encountered in scoliosis patients.

Review of cervical spine anomalies in genetic syndromes

STUDY DESIGN

Focused review of the literature.

OBJECTIVE

Assist spine specialists in diagnosis and treatment of cervical spine anomalies found in selected genetic syndromes.

SUMMARY OF BACKGROUND DATA

Cervical spine instability and/or stenosis are potentially debilitating problems in many genetic syndromes. These problems can be overlooked among the other systemic issues more familiar to clinicians and radiologists evaluating these syndromes. It is imperative that spine specialists understand the relevant issues associated with these particular syndromes.

METHODS

The literature was reviewed for cervical spine issues in 10 specific syndromes. The information is presented in the following order: First, the identification and treatment of midcervical kyphosis in Larsen syndrome and diastrophic dysplasia (DD). Next, the upper cervical abnormalities seen in Down syndrome, 22q11.2 Deletion syndrome, pseudoachondroplasia, Morquio syndrome, Goldenhar syndrome, spondyloepiphyseal dysplasia congenita, and Kniest dysplasia. Finally, the chin-on-chest deformity of fibrodysplasia ossificans progressiva.

RESULTS

Midcervical kyphosis in patients with Larsen syndrome and DD needs to be evaluated and imaged often to track deformity progression. Upper cervical spine instability in Down syndrome is most commonly caused by ligamentous laxity at C1 to C2 and occiput-C1 levels. Nearly 100% of patients with 22q11.2 deletion syndrome have cervical spine abnormalities, but few are symptomatic. Patients with pseudoachondroplasia and Morquio syndrome have C1 to C2 instability related to odontoid dysplasia (hypoplasia and os odontoideum). Morquio patients also have soft tissue glycosaminoglycan deposits, which cause stenosis and lead to myelopathy. Severely affected patients with spondyloepiphyseal dysplasia congenita are at high risk of myelopathy because of atlantoaxial instability in addition to underlying stenosis. Kniest syndrome is associated with atlantoaxial instability. Cervical spine anomalies in Goldenhar syndrome are varied and can be severe. Fibrodysplasia ossificans progressiva features severe, deforming heterotopic ossification that can become life-threatening.

CONCLUSION

It is important to be vigilant in the diagnosis and treatment of cervical spine anomalies in patients with genetic syndromes.

Treatment of spinal deformities in patients with diastrophic dysplasia: a long-term, population based, retrospective outcome study

STUDY DESIGN

A long-term, population based, retrospective follow-up study.

OBJECTIVE

To evaluate long-term outcomes of brace and surgical treatment for spinal deformities in patients with diastrophic dysplasia (DD).

SUMMARY OF BACKGROUND DATA

Literature on the brace treatment and surgery of spinal deformities in patients with DD is limited.

METHODS

All patients with DD undergoing either brace treatment or surgery for spinal deformity with a minimum of 2 years follow-up were identified in our country. Eight patients had undergone brace treatment and 12 had been treated operatively. Two patients had early progressive and the rest idiopathic-like scoliosis. Five patients underwent posterior only, 1 anterior only, and 6 anteroposterior surgery. Patients' mean age at the beginning of brace treatment was 6.9 (range, 0.9-12.7) years and at the time of surgery 13.4 (range, 6.5-20.1) years. The follow-up time averaged 17 (range, 6.6-44.3) years for the brace and 14.0 (range, 2.1-37.2) years for the surgical treatment group. The radiographic follow-up rate was 100%.

RESULTS

Both thoracic and lumbar curves progressed during brace treatment (mean major curve progression 12%, range, -43%-53%). Before surgery, the mean Cobb angle of the thoracic curve was 68 degrees (range, 42 degrees-100 degrees) and 46 degrees (25 degrees-68 degrees) in the lumbar spine. At final follow-up visit, the mean correction was 23% (-6%-76%) for the thoracic curve and 25% (-68%-82%) for the lumbar curve. The correction of the major curve was higher in patients undergoing anteroposterior versus posterior only (40% vs. 13%, P = 0.017). Five (42%) operated patients had significant complications. The SRS-24 yielded 92 (79-103) points for the brace treatment and 93 (73-114) points for the surgical group, respectively.

CONCLUSION

Brace treatment does not prevent progression of the spinal deformity in patients with DD. Anteroposterior surgery is indicated in patients with severe spinal deformities. The risk for major complications is high especially in patients with marked kyphosis.

[Spinal problems in persons with skeletal dysplasias]

Most skeletal dysplasias are characterized by small stature. Less well known is the fact that most skeletal dysplasias are also associated with specific spinal problems or deformities. This article summarizes the various aspects of spinal problems in this patient population as well as the diagnostic strategies and current and new treatment options.

Early degeneration of the knee in diastrophic dysplasia: an MRI study

Magnetic resonance imaging (MRI) findings of 23 patients (13 females, 10 males; 45 knees) with diastrophic dysplasia were examined. The age of the patients ranged from 5 to 40 years (mean 20.5 years). T1- and T2-weighted MR images were obtained. MRI revealed degenerative changes in the articular cartilage of the knees from age 6 years. The subchondral bone of the distal femur was often fragmented, and cartilaginous intrusions from the growth plate into the metaphysis were noted. Menisci developed abnormally. In 43 (96%) of the knees studied, the anterior cruciate ligament was either thinned or rudimentary, or could not be detected. The posterior cruciate ligament was affected in 40 (89%) knees but was at least rudimentary in all patients. In contrast, the patellar tendon was thick and short and the patella was in an inferior position The patella showed bony fragmentation in 32 (71%) knees. The pathologic changes in all joint compartments increased with age, reflecting early degeneration of the knee in this disease.

Total knee arthroplasty in patients with diastrophic dysplasia

BACKGROUND

Diastrophic dysplasia results in severe disproportionate short stature, generalized joint deformities, and early osteoarthritis. The knee joint often has an abnormal valgus position and is unstable, and degeneration of all joint compartments occurs, even during growth. The purpose of our study was to evaluate the clinical and radiographic results of total knee arthroplasty in a series of patients with diastrophic dysplasia.

METHODS

Between February 1992 and March 2000, twenty-one primary total knee arthroplasties were performed on fourteen consecutive patients with severe osteoarthritis due to diastrophic dysplasia. The patients were followed prospectively with clinical examinations, determination of the Hungerford knee scores, and radiographs. Preoperatively, ten knees had chronic dislocation of the patella. The mean duration of follow-up was 3.4 years.

RESULTS

The mean Hungerford knee pain and total scores improved from 5.8 points and 46 points preoperatively to 50 points and 83 points, respectively, at the final follow-up examination (p < 0.001 for both comparisons). Two knees required a distal femoral corrective osteotomy because of metaphyseal angulation. None of the total knee arthroplasties had to be revised during the follow-up period. Six complications were recorded.

CONCLUSIONS

Total knee arthroplasty substantially improved the function of patients with diastrophic dysplasia. Additional peripatellar procedures were commonly needed, and complications were frequent.

Total hip arthroplasty in diastrophic dysplasia

BACKGROUND

Diastrophic dysplasia results in severe disproportionate growth failure, multiple joint deformities, and early osteoarthritis of the hips. Mortality is increased in early childhood, but thereafter life expectancy is normal. Because of severe flexion deformities, resting pain, and diminished movements of the hip joints, total hip arthroplasty is indicated at an early age. The purpose of our study was to evaluate prospectively the midterm results of total hip arthroplasty in a consecutive series of patients with diastrophic dysplasia.

METHODS

Between 1982 and 1996, forty-one total hip replacements were performed in twenty-four consecutive patients with diastrophic dysplasia (mean age, forty-one years) at our hospital. The patients were followed prospectively for a minimum of five years with clinical examination, determination of Harris hip scores, and radiographs. Twenty-two patients (thirty-eight hips) were examined clinically and radiographically at the time of follow-up, and the remaining two patients (three hips) were contacted only by telephone. The mean duration of follow-up was 7.8 years.

RESULTS

The mean Harris hip score increased from 44 points (range, 25 to 66 points) before the operation to 70 points (range, 37 to 89 points) at the final follow-up examination (p < 0.001). Ten complications (24%) were recorded. Five (12%) of the forty-one hips required revision because of aseptic loosening of the acetabular component at a mean of 9.4 years after the primary operation. No revisions were due to aseptic failure of the femoral component.

CONCLUSIONS

Implant survival was good and the Harris hip scores increased significantly after total hip arthroplasty in patients with diastrophic dysplasia. However, shortening femoral osteotomy and transposition of the greater trochanter, adductor and flexor tenotomies, and modification of the femoral stem were frequently needed. Total hip arthroplasty is recommended for patients with diastrophic dysplasia and severe degeneration of the hip joints, even for those who are relatively young.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Cervical kyphosis: predictive factors for progression of kyphosis and myelopathy

STUDY DESIGN

A retrospective study of 13 patients with cervical kyphosis. The authors propose new methods of measuring spinal cord compression and predicting the progression of kyphosis.

OBJECTIVES

To ascertain predictive factors for progression of cervical kyphosis and myelopathy.

SUMMARY OF BACKGROUND DATA

Cervical kyphosis may be congenital, result from decompression surgery, or occur as a posttraumatic deformity. Although there is the potential for progressive deformity and the development of myelopathy in all these situations, there are few previous reports of predictive factors for progression of cervical kyphosis and myelopathy in patients with cervical kyphosis.

METHODS

The authors studied radiographs and magnetic resonance imaging scans of 13 patients with cervical kyphosis, including 9 who had been operated on and had postsurgical secondary kyphosis, and 4 with idiopathic kyphosis without any of the above causes. Compression of the spinal cord at the apex of the cervical kyphosis was evaluated by magnetic resonance imaging of the ratio between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex.

RESULTS

The mean ratio between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex in five patients in whom myelopathy did not develop was 0.37, and was 0.21 in the patients in whom myelopathy developed. Progression of cervical kyphosis was associated with osteophyte formation at the anterior aspect of the vertebral body.

CONCLUSION

A ratio below 0.3 between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex was a risk factor for cervical myelopathy. One of the most predictable risk factors of progression of the cervical kyphosis was osteophyte formation at the anterior aspect of the vertebral body.

Lung function in diastrophic dysplasia

Diastrophic dysplasia (DD) is a rare skeletal dysplasia characterized by short-limbed short stature, contractures and early degeneration of joints, and spinal deformities such as scoliosis. Mortality is increased in the neonatal period, in part due to tracheo- and bronchomalacia. Additionally, spinal deformities are very rigid, decreasing mobility of the chest cage. The aim of our study was to evaluate lung volumes and airway flow dynamics in patients with DD. A total of 31 patients (12 males, 19 females) underwent a detailed clinical examination measurements of standing height PA-radiography of the spine, flow-volume spirometry, and body plethysmography. The patients were assigned to two groups: children and adolescents (0-18 years, n = 18) and adults (over 18 years, n = 13). The mean spirometric parameters were mostly within the predicted value range, although the variation was wide. At least one abnormally low spirometry parameter was found in 6 (33%) of the children and adolescents and in 7 (54%) of the adults. Mean forced vital capacity (FVC) was 104% (range 48-163%) of predicted values in the children and adolescents and 95% (58-140%) of the adults. Peak expiratory flow (PEF) values were abnormal in 4 (22%) of the children and adolescents and in 5 (39%) adults. The mean plethysmographic parameters were all within the predicted value range. At least one abnormal plethysmographic value was found in 6 (33%) of the children and adolescents and in 4 (31%) of the adults. Airway resistance (Raw) was significantly higher in the adults than in the children and adolescents (P = 0.016), and was abnormally high in 3 (23%) of the adults. The angle of thoracic or thoracolumbar scoliosis correlated with the percentages of the predicted values of FVC (r(s) = - 0.66), forced expired volume in 1 sec (FEV(1)) (r(s) = - 0.56), and total lung capacity (TLC) (r(s) = - 0.67). Age correlated with the FEV(1)/FVC ratio (r(s) = - 0.41), with the maximal expired flow at 50% FEV (MEF(50)) values (r(s) = - 0.55), with the residual volume (RV) values (r(s) = - 0.47), and with the RV/TLC ratio (r(s) = - 0.43). Variable bronchial obstruction was found in 1 (6%) child and in 2 (17%) adults. Although the patients with DD had, on average, normal lung volumes, large individual variation occurred. Airway resistance was increased in adults. The angle of scoliosis correlated inversely with lung volume parameters.

Thoracic and lumbar spine in diastrophic dysplasia: a clinical and magnetic resonance imaging analysis

STUDY DESIGN

Cross-sectional study to evaluate the thoracic and lumbar spine in patients with diastrophic dysplasia (DD).

OBJECTIVES

To find the causative factors behind the spinal deformities and restricted mobility of the spine.

SUMMARY OF BACKGROUND DATA

Typical findings in this skeletal dysplasia are short-limbed stature, multiple joint contractures, early degeneration of joints, and spinal deformities such as cervical kyphosis, scoliosis, and exaggerated lumbar lordosis. The pathogenic mechanism of scoliosis is unknown.

METHODS

A physical examination was performed on 88 patients (55 females, 33 males) with an average age of 31 years (range, 3-56). Magnetic resonance (MR) images from T2 to S1 and radiographs were obtained. Degree of scoliosis was measured according to Cobb from standing radiographs. The anatomy of the medulla and the size of the spinal canal were assessed. The transverse dural tube area was measured from L2 to S1. Disc space, degeneration, and protrusions were evaluated. Vertebral abnormalities, if any, facet joint degeneration and the state of the spinal muscles were also assessed.

RESULTS

Physical examination showed diminished mobility of the spine. Scoliosis was noted in 70 patients with an average of 42 degrees (range, 11-188 degrees ). The mean transverse area of the dural tube ranged from 94 mm(2) at L2-L3 to 57 mm(2) at L5-S1. The area was smaller at all levels compared with reference values (P < 0.001). One patient had severe thoracic and lumbar spinal stenosis. Five patients had compression of neural structures in the lumbar spinal canal in MR images, but had no clinical symptoms. All patients exhibited narrowed disc heights and a decrease in the signal intensity of discs on T2-weighted images. The prevalence of disc protrusions was low; three patients had a prolapse in the lumbar spine. Two patients displayed vertebral anomalies. All patients also had muscular atrophy and degenerative-like facet joint hypertrophy. The severity of these changes increased with age.

CONCLUSIONS

Abnormal disc structure and rapid degeneration explain the diminished decreased mobility of the spine and may be a causative factor in the development of scoliosis. Muscular atrophy may be caused by reduced physical activity and rigid spinal deformities. The spinal canal is narrowed, but symptomatic lumbar spinal stenosis is uncommon.