Histopathology of the temporal bone in osteogenesis imperfecta congenita: a report of 5 cases

The histopathologic findings in 8 temporal bones from 5 patients with osteogenesis imperfecta congenita are reported. The otic capsule, bony walls of middle ear, and ossicles showed evidence of both deficient and abnormal ossification. Microfractures were found in the otic capsule and in the anterior process and handle of the malleus, in addition to their common location at the crura of the stapes. The cochlear and vestibular end-organs appeared normal. Pathologic changes compatible with otosclerosis were not seen. The possible implication of these changes on hearing and balance is discussed.

Lethal osteogenesis imperfecta congenita and a 300 base pair gene deletion for an alpha 1(I)-like collagen

Broad boned lethal osteogenesis imperfecta is a severely crippling disease of unknown cause. By means of recombinant DNA technology a 300 base pair deletion in an alpha 1(I)-like collagen gene was detected in six patients and four complete parent-child groups including patients with this disease. One from each set of the patients' clinically unaffected parents also carried the deletion, implying that affected patients were genetic compounds. The study suggests that prenatal diagnosis should be possible with 100% accuracy in subjects without the deletion and with 50% accuracy in those who possess it (who would be either heterozygous--normal, or affected with the disease).

Abnormal type I collagen metabolism by cultured fibroblasts in lethal perinatal osteogenesis imperfecta

Cultured skin fibroblasts from seven consecutive cases of lethal perinatal osteogenesis imperfecta (OI) expressed defects of type I collagen metabolism. The secretion of [14C]proline-labelled collagen by the OI cells was specifically reduced (51-79% of control), and collagen degradation was increased to twice that of control cells in five cases and increased by approx. 30% in the other two cases. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that four of the OI cell lines produced two forms of type I collagen consisting of both normally and slowly migrating forms of the alpha 1(I)- and alpha 2(I)-chains. In the other three OI cell lines only the 'slow' alpha (I)'- and alpha 2(I)'-chains were detected. In both groups inhibition of the post-translational modifications of proline and lysine resulted in the production of a single species of type I collagen with normal electrophoretic migration. Proline hydroxylation was normal, but the hydroxylysine contents of alpha 1(I)'- and alpha 2(I)'-chains purified by h.p.l.c. were greater than in control alpha-chains. The glucosylgalactosylhydroxylysine content was increased approx. 3-fold while the galactosylhydroxylysine content was only slightly increased in the alpha 1(I)'-chains relative to control alpha 1(I)-chains. Peptide mapping of the CNBr-cleavage peptides provided evidence that the increased post-translational modifications were distributed throughout the alpha 1(I)'- and alpha 2(I)'-chains. It is postulated that the greater modification of these chains was due to structural defects of the alpha-chains leading to delayed helix formation. The abnormal charge heterogeneity observed in the alpha 1 CB8 peptide of one patient may reflect such a structural defect in the type I collagen molecule.

Acute bilateral extradural hematomas in a case of osteogenesis imperfecta congenita

Acute bilateral extradural hematomas occurred after apparently trivial trauma in a patient suffering from osteogenesis imperfecta congenita. Factors influencing the development of this dramatic complication are peculiar to this rare disorder of bone and connective tissue development and include bony weakness, increased vascular fragility, and possible coagulopathies.

Ocular findings in osteogenesis imperfecta congenita

Osteogenesis imperfecta is a rare, inherited, connective-tissue disorder. The three main signs of this disease are multiple bone fractures, blue scleras, and deafness (osteosclerotic type). In our research, only a few reports of the morphologic studies of the eyes of patients with osteogenesis imperfecta were found. This report describes the ocular histopathologic condition of four cases of osteogenesis imperfecta congenita, with emphasis on the ultrastructural characteristics of the collagen in the cornea and sclera.

[In osteogenesis imperfecta no intramedullary nailing and especially no bone plates in childhood]

This is a review of 24 patients with osteogenesis imperfecta of all age groups. 7 severe cases have been followed closely during growth for at least 10 years after multiple series of osteotomies with stabilisation by rodding and plating. The conclusion of the disappointing late results consists in that plating has to be abandoned completely during growth. The indication for rodding has to be restricted severely because of the necessity for replacement of the nails about every two year until cessation of growth. Special operative indications are outlined.

Osteogenesis imperfecta: results obtained with the Sofield method of surgical treatment

The authors report the results obtained in thirteen patients with osteogenesis imperfecta who were treated by the Sofield operation. This operation is indicated both in the congenital and delayed forms of the disease. The results are promising: prevention of deformities and fractures in a high percentage of cases, recovery of the ability to walk in all the patients. The incidence of complications was low, infection being the most serious. Although the use of extending rods reduces the number of reinterventions, it does not appear to improve the results and carries the risk of a greater number of complications. However, the authors have no experience of this particular technique.

[Osteogenesis imperfecta. Up-to-date review (author's transl)]

Based on review of recent literature and in their own experience, authors point out basic concepts on alterations of collagen, emphasizing clinical and radiological data which differ types II and III in neonates.

Biochemical abnormalities in osteogenesis imperfecta

Osteogenesis imperfecta is likely to be caused by primary disorders of synthesis of organic components of connective tissues accounting for clinical and laboratory observations in several affected tissues. Defects in the structure of collagen is well documented in several instances. There is no evidence of a primary disorder in the synthesis of glycosaminoglycans. Several studies of pyrophosphate metabolism and the hormonal control or the overall metabolic activity of isolated cells do not implicate a pathogenic mechanism for this disorder. Detailed biochemical and further clinical correlations are necessary in order to elucidate the pathogenesis of osteogenesis imperfecta.

Management overview of osteogenesis imperfecta

The treatment of osteogenesis imperfecta varies with the age of the patients and the severity of disease. Patients with mild disease rarely develop significant deformities; therefore, the care required is mainly limited to periodic fractures or to associated problems, such as erosion of the teeth, decreased hearing, and difficulties in adjustment. It is the patient with severe disease who often requires an unusual amount of attention. Regardless of the immediate problem, the treatment program should be geared toward the long-term function of the patient; in most cases this will be best served by the prevention and/or correction of long bone deformities, and by encouraging maximum intellectual and academic development. The latter requires contact of the child with normal children by placement in regular school classes. The primary basis of a successful treatment program to maintain acceptable skeletal alignment consists of properly timed operations for insertion of extensible intramedullary rods, together with supportive splints and braces. No other method of treatment, such as the use of systemic medications, has yet been shown to benefit the patient clinically. Progressive improvement in bone strength during childhood permits better eventual function for those patients in whom good skeletal alignment has been maintained. Most patients will become productive members of society, so the combination of optimum physical and optimum academic development will offer maximum opportunity to those who enter the competitive job market.

Fragile bones and fragile ears

Conductive, sensorineural and mixed hearing loss occur in osteogenesis imperfecta in autosomal dominant inheritance pattern. Hearing loss is generally due to the middle and inner ear pathology of osteogenesis imperfecta and only occasionally to the coincidental association of otosclerosis and osteogenesis imperfecta. Two lesions cause the conductive hearing loss of osteogenesis imperfecta: (1) functional ossicular discontinuity due either to stapes superstructure fracture or fibrous replacement, or (2) thick, crumbly, lightly fixed stapes footplate. Cochlear hair cell loss, stria vascularis atrophy and calcification, tectorial membrane distortion and perilymph hemorrhage are autopsy findings that could account for sensorineural hearing loss, which occurs in a surprisingly high percentage of osteogenesis imperfecta patients. Hearing loss occurs earlier in osteogenesis imperfecta than in otosclerosis. Distinctive acoustic impedance and X-ray abnormalities occur in osteogenesis imperfecta. Other otologic findings may include lopped pinna, notching of the helix of the pinna, rosy flush of the medial wall of the middle ear and vestibular abnormalities.

Anesthetic considerations for the patient with osteogenesis imperfecta

Anesthetizing a patient with osteogenesis imperfecta is an uncommon and challenging event for most anesthesiologists. The manifestations of this disease directly affect anesthetic management. The choice of anesthetic technique must be carefully considered in view of the abnormalities in such patients. Local or regional anesthesia is very useful in patients with osteogenesis imperfecta, but when general anesthesia is mandatory ketamine hydrochloride is often a good choice. Close monitoring during anesthesia and surgery is essential.

Surgical treatment of the tibia in osteogenesis imperfecta

Segmentation and intramedullary rod fixation of the tibia have been found to be safe and effective procedures in osteogenesis imperfecta. An extensible rod is more difficult to insert than a solid rod due to the problem of obtaining an adequate fit distally, so the practical advantage of one type over the other is not as great as it is for the femur. When the procedure is used for the proper indications and with sufficient attention to detail, severe deformities can be corrected, thus allowing many children to become or remain ambulatory.

The morbid anatomy of the skeleton in osteogenesis imperfecta

Clinically, the two most prominent features of osteogenesis imperfecta are dwarfing and bone fragility. Radiologic examination reveals severe osteopenia with or without multiple deformities. Histological examination of samples obtained from 16 iliac crest biopsies compared with 21 age-matched controls revealed a significantly diminished amount of bone matrix without an associated decrease in the number of bone cells, suggesting a quantitative deficiency of collagen production. Radiologic studies of 46 affected children and autopsy studies of two children revealed abnormalities in the ossification of the secondary centers of ossification, together with evidence of fracture and fragmentation of the epiphyseal growth plates causing a characteristic radiologic appearance which may be likened to a bag of popcorn. These epiphyseal abnormalities may contribute to the limb shortening in some cases.

Nonoperative treatment of osteogenesis imperfecta: orthotic and mobility management

The problem of osteoporosis superimposed on the basic collagen defect of osteogenesis imperfecta has been approached by the use of plastic containment orthoses for the lower limbs, in addition to developmentally staged mobility devices that assist early standing and walking. The purpose of forcing early weight-bearing is to provide stress to the lower limb bones in order to minimize osteoporosis, prevent refracture and deformity, and curb subsequent immobilization osteoporosis, thus breaking a vicious cycle. Management goals are based upon adult needs for independence: efficiency in daily living activities and in mobility. These goals were reached in most of our patients via use of plastic orthoses, early weight-bearing, and electrically powered wheelchairs. Manual osteoclasis of the tibia followed by plastic orthoses utilizing principles of fluid compression to support fractured or structurally weak bones appeared successful at the time of follow-up. Intramedullary rodding of the femur was necessary in most of the 12 children with osteogenesis imperfecta congenita. Supplementary plastic orthoses have reduced the refracture rate in both the tibia and the femur. Social integration of the children was reflected by the fact that among the 12 OI congenita cases, ten were attending regular educational institutions. Twelve OI tarda children fared well, all attaining complete independence in daily living, mobility and ambulation. Seven of this group were treated with intramedullary rodding of the femur or tibia and with plastic orthoses. Five patients required no treatment.

Further clinical experience with the extensible nail

The extensible nail for treatment of children with brittle bones offers distinct advantages over the conventional rod. It appears to elongate with growth and thus obviates periodic replacement of the rod as the child grows. Complications have been few in this and other series. Recent modifications of the technique for the femur and tibia, and various changes in the original design, constitute significant improvements in the intramedullary nail method.

Internal fixation of the femur in patients with osteogenesis imperfecta

The operation of fragmentation and intramedullary rod fixation of the femur with an extensible device has proved valuable for children with osteogenesis imperfecta because it permits these children to remain ambulatory. The use of an extensible rather than a solid rod has greatly decreased the need for reoperation.

Observation on the surgical management of osteogenesis imperfecta

Surgical treatment is a safe adjunct to the management of the child with osteogenesis imperfecta. Its objectives are to control fractures and correct deformities. It may significantly improve the functional status of the child. The long-range aim of bioscience is to determine and correct this genetic defect and thereby avoid the need for orthopedic methods of managements.