Mesomelic skeletal dysplasias.

Mesomelic shortening of the extremities lends itself as a useful clinical and/or radiologic sign to characterize a group of hereditary bone dysplasias. Table 1 and Figure 4 are presented to facilitate the comparison between the many different types of mesomelic dwarfism. Differential diagnosis between these types is not difficult because of the specific bone changes and extraskeletal malformations present. As in many hereditary syndromes, however, there may be wide clinical variability within a single entity, and meticulous clinical and radiologic examination must be done to arrive at the correct diagnosis. Certain other forms of chondrodystrophies, such as achondroplasia, hypochondroplasia, pseudoachondroplasia and distrophic dwarfism, can be easily differentiated from the mesomelic dysplasias by their clinical features and skeletal radiographs. Nothing is known about the pathogenesis of the various forms of mesomelic dysplasias. There is no available specific treatment, although corrective surgery has benefited selected patients. The correct diagnosis is, however, important both for prognostication and accurate genetic counseling.     

Bilateral total hip replacement in pseudoachondroplasia

Pseudoachondroplasia is an inherited skeletal dysplasia with short-limbed dwarfism and early onset of osteoarthritis. A 29-year-old pseudoachondroplastic woman presented with progressively painful hips secondary to severe osteoarthritis of both joints, so that total joint replacements were necessary to restore her mobility and quality of life. The implants inserted had to be specifically manufactured in accordance with the individual geometry and reduced bone size. In addition, the implants mechanical resistance to dynamic loading conditions had to be tested prior to total hip replacement surgery.     

Newly synthesized proteoglycans in pseudoachondroplasia

In an attempt to elucidate the biochemical defect in pseudoachondroplasia, proteoglycan metabolism was investigated in cartilage from a patient with the dominant form of this condition. Iliac-crest cartilage was radioactively labeled with ³⁵S-sulfate and the newly synthesized proteoglycans examined for their hydrodynamic size and glycosaminoglycan composition. The banding pattern of the purified proteoglycans was analyzed by gel-electrophoresis using large pore polyacrylamide-agarose. We found a normal chain-length of glycosaminoglycans and a normal ratio of chondroitin-6-sulfate to chondroitin-4-sulfate. The proteoglycans were not enriched in keratan sulfate. Gel electrophoretic analysis of the proteoglycans disclosed a banding pattern comparable to that of two normal controls. In contrast to the findings of other authors no differences between the proteoglycans of pseudoachondroplastic and normal cartilage were detected.     

Upper cervical spine instability in pseudoachondroplasia

BACKGROUND: Pseudoachondroplasia (PSACH) is a rare autosomal dominant skeletal dysplasia associated with os odontoideum and atlantoaxial instability. This study aims to define the characteristics of upper cervical spine instability in patients with PSACH and analyze the relation between the incidence of upper cervical instability and os odontoideum. METHODS: Fifteen patients (10 women and 5 men) with PSACH of Korean ethnicity with mean age of 23.7 years (range, 3-44 years) at presentation to our hospital with varied complaints, including short stature, limb deformity, neck pain, and neurological symptoms, were evaluated clinicoradiologically for upper cervical spine instability. The patients were separated into group 1 (n = 9) with os odontoideum and group 2 (n = 6) without os odontoideum. Comparisons were made using parameters such as instability index, rotational instability, atlantodens interval and space available for cord, and analysis done to correlate cervical instability with age and Japanese Orthopedic Association (JOA) score. RESULTS: Significant differences were found statistically when the 2 groups were compared on the basis of the space available for the cord (SAC), JOA scoring, and rotational instability. Linear relationship was found between instability and age and JOA score. Incidence of os odontoideum was 60% in our study group. CONCLUSIONS: Os odontoideum led to an increase in the incidence of upper cervical spine instability. Instability increased with the age. The presence of os odontoideum and atlantoaxial instability did not warrant for surgery because no signs of cervical myelopathy developed or progressed in our patients during the follow-up period, but these patients should undergo regular clinical and radiological evaluation. LEVEL OF EVIDENCE: Level IV prognostic study.     

Dolicho-odontoid in a boy with pseudoachondroplasia

We report on a 9-year-old-boy with the clinical and radiographic diagnosis of pseudoachondroplasia. An antero-posterior open mouth radiogram, showed an unduly long odontoid and a 3 CT scan confirmed the presence of a long, bifid odontoid. This is the first clinical report describing a dolicho-odontoid in a boy with pseudoachondroplasia.     

Diastrophic dwarfism.

Diastrophic dwarfism is an unusual variety of short-limb dwarfism characterized by the pathognomic triad of ear calcifications, hitch-hiker thumbs, and severe clubfoot. Other clinical features include joint contractures and subluxations, symphalagism of the fingers, kyphoscoliosis, hip dysplasia, and occasional cleft palate. Radiographic findings include flaring of the metaphyses of tubular bones and flattened epiphyses which appear late. The major orthopedic problem in diastrophic dwarfism is correction of the recalcitrant clubfoot deformity; cervical spine subluxation or kyphoscoliosis may also require intervention. This disorder is inherited as an autosomal recessive condition.     

Differential diagnostic considerations in microcephalic dwarfism

PURPOSE: While the rare Seckel-Syndrome is defined by clear criteria, clinical and radiologic findings for microcephalic osteodysplastic primordial dwarfism (MOPD) make an exact diagnosis and classification difficult. By comparing our patients to previously described cases of MOPD we evaluate the hypothesis that this disorder has a greater heterogeneity than has been believed up until now. Furthermore the differential diagnosis of the MOPD-complex is discussed. RESULTS: Two cases that show typical growth retardation, microcephalus and facial anomalies as well as osteodysplastic deformities including hip dysplasia are presented. The parents of both children are consanguineous and of Arabic race. In one of the children growth hormone levels were noticeably decreased. In discrepancy to the Seckel-syndrome both children showed no signs of mental retardation, therefore the classification into the heterogeneous group of microcephalic osteodysplastic primordial dwarfism (MOPD) is the most likely diagnosis. CONCLUSION: It is suggested that microcephalic osteodysplastic primordial dwarfism (MOPD) has a greater clinical and radiological expression than has been assumed up until now. Whether our results are merely a variant or suggest a new subtype of the MOPD can only be resolved by further cases. The exact pathogenesis of the disease currently remains unknown but the most probable cause is an autosomal recessive inheritance.     

Propofol pharmacokinetics in a dwarfism patient

Pharmacokinetic information is important to control anesthetic depth. However, there are few available pharmacokinetic data of propofol in dwarfism patients. We anesthetized a dwarfism patient who underwent spinal decompression, and investigated the pharmacokinetics of propofol. The patient was a 40-year-old man suffering from muscle weakness and numbness in the arms. The operation consisted of two stages; anterior approach in the supine position and posterior approach in the prone position. We also obtained arterial blood for pharmacokinetic analysis. Distribution volume at steady-state and clearance in the supine position was 180 and 0.92 l min- 1, respectively, and in the prone position 127 and 0.74 l min- 1, respectively, in spite of a continuous infusion of dopamine. The data in the supine position were well predicted by Gepts' parameters (used in Diprifusor Zeneca Ltd, Cheshire, UK), which means the target-controlled infusion (TCI) technique can be available in the supine position, while attention is necessary to avoid overdosing when a patient is placed in the prone position.     

The spinal disorders in diastrophic dwarfism.

Of seven patients with diastrophic dwarfism, all had cervical spina bifida occulta. Two had cervical kyphosis, which was severe in one. Scoliosis was present in five patients and was always progressive. Lumbar lordosis was seen in all seven patients and was not progressive.     

Mesomelic dysplasia: presentation of a case and literature of Werner's syndrome

The extremely rare Werner syndrome (tibial hemimelia, foot polydactyly, triphalangeal thumbs) is represented by an own case: a 21 year old female has been treated since her birth in the orthopedic department of Homburg/Saar university clinic. First, during several operative sessions, there was the correction of the bilateral completely webbed fingers and the resection of the supernumerary toes. Because of tibial hypoplasia there was need of bilateral operative club-foot-correction, too. Presentation of the course over 20 years with clinical and roentgenological late results. In several publications we find different classifications of the collective name, tibial hemimelia'; the symptom-triade congenital tibia-defect/foot-polydactyly/triphalangeal thumb was of special interest.