Perioperative Care of the Patient With Osteogenesis Imperfecta

Abstract

Osteogenesis imperfecta is an inherited disorder of the connective tissue whose primary manifestation is an increased susceptibility to fractures. Severely affected patients often suffer multiple fractures after minimal or no trauma. In addition to its primary effect on the skeletal system, the alterations in connective tissue may affect several extraskeletal structures, such as the cardiovascular system, sclera, middle and inner ear, tendons/ligaments, central nervous system, and teeth. Patients with osteogenesis imperfecta also have a greater incidence of airway anomalies, thoracic anatomy abnormalities, coagulation dysfunction, hyperthyroidism, and an increased tendency to develop perioperative hyperthermia. Given the multisystem involvement of osteogenesis imperfecta, several issues exist that may impact the perioperative management of these patients. Of particular concern are the associated cardiovascular anomalies, increased incidence of perioperative bleeding, easily fractured bones and teeth, airway anomalies, the tendency to develop intraoperative hyperthermia, and hyperthyroidism.

Although the primary manifestation of osteogenesis imperfecta is the clinical feature of fractures following incidental trauma, the primary pathogenetic defect of type I collagen formation manifests in several areas throughout the body. These include the tendons/ligaments, sclera, skin, middle and inner ear structures, teeth, and the cardiovascular system. There also is a recognized association between osteogenesis imperfecta and cardiovascular anomalies, airway anatomy anomalies, coagulation dysfunction, and endocrine abnormalities. Given the multi-system involvement of this disease, several perioperative implications exist. This article reviews the potential perioperative manifestations of osteogenesis imperfecta, provides case examples of patients with osteogenesis imperfecta with required bilateral tibial osteotomies and intramedullary rod placement, and provides key points to be considered in the perioperative management of such patients.

Genetic and Biochemical Basis of Osteogenesis Imperfecta

Osteogenesis imperfecta is an autosomal dominant disorder that results in the defective synthesis of type I collagen, which is the primary component of the extracellular matrix of bone and skin that leads to the classic clinical manifestation of brittle bones.¹ Type I collagen normally is composed of 3 amino acid chains that are rich in glycine, proline, and hydroxyproline. Glycine occupies every 3 residue along the a chains and is crucial for the normal helical formation of type 1 collagen. Its small side chain can be incorporated into the spatial constraints in the interior of the helix formed by these 3 amino acid chains. In the majority of cases, the gene defect in osteogenesis imperfecta results in the substitution of another amino acid in the place of glycine along the amino acid chain thereby interfering with the normal helical structure of the collagen molecule. This defect leads to the classic triad of osteogenesis imperfecta including susceptibility to fractures, blue sclerae, and conductive hearing loss. The diagnosis is confirmed by abnormal collagen synthesis in cultured fibroblasts.

Classification of Osteogenesis Imperfecta

Although initially divided into 2 forms, osteogenesis imperfecta congenita occurring at birth and osteogenesis imperfecta tarda occurring later in life, the current classification divides osteogenesis imperfecta into 4 types based on its phenotypic manifestations and the radiographic appearance of the bones. Osteogenesis imperfecta type I (mild) is considered the mildest form of the disease and is compatible with long-term survival in adulthood.

Children with osteogenesis imperfecta type I exhibit an increased frequency of fractures, short stature, blue sclerae, and progressive hearing impairment in 30% to 60% of patients. As adults these patients may develop premature osteoporosis. Types I and IV can be subdivided into groups A and B based on the absence or presence of dentinogenesis imperfecta or abnormal tooth formation. Patients with type I and IV osteogenesis imperfecta have a normal life-span.

Osteogenesis imperfecta type II (lethal perinatal osteogenesis imperfecta) manifests at birth or in utero. This is an extreme form of osteogenesis imperfecta with marked involvement of the skeletal and connective tissue systems. These patients have multiple in utero fractures, micromelia, bowing of the extremities, and a small thorax that can lead to respiratory failure. Affected patients usually die in utero or within days of birth.

Osteogenesis imperfecta type III (progressive deforming osteogenesis imperfecta), is the most severe, non-lethal form of osteogenesis imperfecta, and results in growth retardation, multiple fractures, progressive kyphoscoliosis, vertebral compression, blue sclerae, and dentinogenesis imperfecta. Fractures occur from minor trauma and result in severe extremity deformities. These patients have a reduced life span with death occurring in the second to fourth decade of life due to progressive pulmonary involvement.

Patients with osteogenesis imperfecta type IV demonstrate moderate skeletal fragility and short stature. They sustain fractures in utero or following minor trauma or bowing of the lower extremities once weight bearing begins following ambulation. These patients are less severely affected than patients with type III osteogenesis imperfecta and can attain an acceptable quality of function with orthopedic interventions.

Cardiovascular involvement

As with other disorders affecting the connective tissue (Ehlers-Danlos syndrome, Marfan’s syndrome, Hurler’s syndrome, and pseudoxanthoma elasticum), cardiovascular involvement may occur with osteogenesis imperfecta.^2,3 The severity of skeletal involvement does not directly correlate with the degree of cardiovascular involvement. The cardiac pathology is limited to the left-sided heart valves with aortic insufficiency being the most common cardiac lesion followed by mitral regurgitation or mitral valve prolapse. The latter was present in our first patient.^2,3 Although mitral valve prolapse has been suggested to be a common cardiac manifestation of osteogenesis imperfecta, Hortop et al² reported an incidence of only 6.9% in their cohort of 109 patients with osteogenesis imperfecta; an incidence that is not greater than the 4% to 8% incidence found in the normal adult population. Therefore, its exact association with osteogenesis imperfecta remains controversial.

Hortop et al² also reported aortic root dilatation in 8 (12.1%) of 66 patients with osteogenesis imperfecta. The extent of the aortic root dilatation was mild (maximum of 4.3 cm) and the authors noted that this is in marked contrast to the aortic root involvement that occurs in patients with Marfan’s syndrome. Hortop et al² also suggest that since the aortic root dilatation was non-progressive, specific therapy such as the use b-adrenergic antagonists that are used in patients with Marfan’s syndrome, is not indicated. However, reports exist in the literature on aortic dissection and death in patients with osteogenesis imperfecta.^4,5

Isotalo et al⁴ reported a 65-year-old patient who died following a type A aortic dissection 18 years after successful surgery on the aortic valve. They also reported that their patient was the fourth reported in the literature demonstrating the potential for aortic dissection in osteogenesis imperfecta and they recommend aggressive treatment of risk factors such as hypertension in this population.⁴

To date, a limited number of reports on the association of congenital heart disease and osteogenesis imperfecta have been reported. Janoskuti et al⁶ reported a 20-year-old patient with a membranous ventricular septal defect and osteogenesis imperfecta while Manoria et al⁷ reported 1 patient with the associated findings of osteogenesis imperfecta and an atrial septal defect. Vetter et al⁸ examined 58 children with various forms of osteogenesis imperfecta and noted congenital heart disease in 4 patients including valvular aortic stenosis (n=1), atrial septal defect (n=2), and tetralogy of Fallot (n=1). Given the paucity of reports in the literature of patients with osteogenesis imperfecta and congenital heart disease, these reports may represent a random occurrence and not a true association.

Cardiovascular involvement in osteogenesis imperfecta generally manifests in the second to fourth decade of life. Although rare, preoperative echocardiography appears indicated in these patients at the time of initial diagnosis and then once again when they reach the second decade of life to identify clinically significant aortic or mitral valve disease. Patients with mitral valve prolapse, valvular dysfunction, or congenital heart disease should receive prophylactic antibiotics to prevent subacute bacterial endocarditis.

Perioperative Airway Concerns

Patients with osteogenesis imperfecta also may present the potential for dental damage or difficulties with airway management. Osteogenesis imperfecta type I and IV can be subdivided into types A and B based on the absence or presence of dentinogenesis imperfecta or abnormal tooth formation.^9,10 In patients with type B osteogenesis imperfecta, otherwise inconsequential contact may lead to dental trauma during airway manipulation and the use of tooth guards should be considered.

Factors that may impact on airway management include megalocephaly, macroglossia, and a short neck.^11,12 These airway issues may further be complicated by the potential risk of cervical spine injury during neck extension and/or a limited range of motion of the cervical spine.¹¹ The latter was present in the patients who are described in the case examples included in this article. A laryngeal mask airway was used for airway management in these patients, thereby avoiding the need for direct laryngoscopy and endotracheal intubation with the potential for cervical spine injury.

Previous reports in the literature have illustrated various problems related to airway management during the intraoperative care of patients with osteogenesis imperfecta. In a review of 266 anesthetics in 63 patients with osteogenesis imperfecta, Hall et al¹³ reported difficult intubation in 2 patients related either to a short neck or dental problems. They also noted difficult bag-mask ventilation in some patients especially those with osteogenesis imperfecta type III or IV related either to midface or mandibular deformities. Edge et al¹⁴ reported a difficult endotracheal intubation in a 32-year-old woman with osteogenesis imperfecta. After a failed nasal and oral fiberoptic approach, endotracheal intubation was accomplished with some difficulty by passing an endotracheal tube through an laryngeal mask airway. The entire intubation took >2 hours. Others have reported the use of nasal fiberoptic intubation, the intubating laryngeal mask airway, or a standard laryngeal mask airway as techniques of airway management.^15-17

Central Nervous System Issues

Central nervous system issues may include basilar impression or invagination syndrome (ventral brainstem compression from an invaginating clivus-odontoid complex), craniovertebral junction problems including atlantoaxial subluxation, and hydrocephalus similar to that reported in other inherited disorders of bone or cartilage development.^18,19

Sawin and Menezes¹⁹ reviewed the clinical course and treatment plan for basilar invagination in 25 patients with osteogenesis imperfecta. They noted a male:female ratio of 1:1 and a mean age at presentation of 11.9 years (range, 13 months to 20 years). Signs and symptoms included headache (76%), lower cranial nerve dysfunction (68%), hyperreflexia (56%), quadraparesis (48%), ataxia (32%), nystagmus (28%), and scoliosis (20%). Ventral brainstem compression was noted in 84% and hydrocephalus in 32%. In addition to the obvious neurological implications of these problems, they also may further complicate airway management. Therefore, the preoperative evaluation should focus on an evaluation for the signs and symptoms of upper cervical cord compression supplemented as needed with radiographic evaluation of the craniovertebral junction. The significance of these issues is demonstrated by reports of death related to cervical spine compression in patients with osteogenesis imperfecta.²⁰

Additional concerns related to the central nervous system of patients with osteogenesis imperfecta include early onset deafness and anatomical/developmental abnormalities.^21-23 Imani et al²¹ assessed hearing in 22 children with osteogenesis imperfecta over a 5-year study period. They noted normal hearing in 5 (22.7%) patients, conductive hearing loss in 14 (63.6%), which respond to treatment of otitis media with effusion in all but 2 patients, and sensorineural hearing loss in 3 (13.6%). They concluded that although the literature suggests hearing loss starting in the second or third decade of life in patients with osteogenesis imperfecta, they noted hearing loss in 77.3% of the patients that they screened with a median age of 9 years. These findings have obvious implications for long term function of these patients, but also mandates a review of the patient’s history and previous medical therapies to ascertain whether hearing loss is present given the impact it has on the healthcare provider’s ability to communicate with the patient during the perioperative period.

Coagulation Function

A significant perioperative issue related to osteogenesis imperfecta is an associated bleeding diathesis, the incidence of which has been reported to vary from 10% to 30%.^22,23 The bleeding diathesis may be severe and has resulted in intraoperative mortality.²⁴ The coagulation defect appears to be primarily related to the effect of the abnormal collagen on platelet-endothelial cell interactions. This defect results in increased capillary fragility, defective contraction of small blood vessels after injury, and defective platelet aggregation.^25,26 In a laboratory investigation of 58 patients with osteogenesis imperfecta, Evensen et al²⁶ noted increased capillary fragility (35%), decreased platelet retention (33%), and a reduced factor VIII antigen concentration (23%). Less common findings included reduced risocetin cofactor, deficient platelet aggregation induced by collagen and a prolonged bleeding time. Given that these defects relate primarily to capillary fragility and platelet dysfunction, routine preoperative coagulation tests (prothrombin time, partial thromboplastin time) generally are normal.

When a bleeding diathesis is suspected, preoperative hematology consultation for platelet function testing may be indicated. Given these problems, medications, most importantly nonsteroidal anti-inflammatory drugs, which have deleterious effects on platelet function, should be avoided. Anecdotal reports have suggested the potential efficacy of desmopression or recombinant factor VIIa as a means of augmenting coagulation function in patients with osteogenesis imperfecta.^27,28

Intraoperative Temperature Dysregulation

Intraoperative hyperthermia and metabolic acidosis have been noted in patients with osteogenesis imperfecta. Although some authors have suggested that these patients have an increased incidence of malignant hyperthermia,^29,30 the general consensus is that the hyperthermia and acidosis, which may occur with osteogenesis imperfecta, is not related to malignant hyperthermia.^11,13

Various theories have been postulated to explain intraoperative hyperthermia including an increased metabolic rate or associated hyperthyroidism.^11,31 Intraoperative hyperthermia also has been shown to be more common in patients who have received anticholinergic medications and with inhalational versus intravenous anesthesia.^11,13,32 Given the potential for these problems, consideration should be given to placement of the patient on a cooling blanket during the procedure in the event that hyperthermia requires therapy. Increased postoperative febrile responses in the absence of acute infectious causes also has been reported in this population.³³

Case Reports

Review of these patients’ medical and hospital records and presentation of these case reports were approved by the Institutional Review Board of the University of Missouri. Both patients were treated during volunteer orthopedic surgical trips to the Dominican Republic.

Patient 1

A 14-year-old, 54 kg girl presented for bilateral tibial osteotomies and intramedullary rod placement for the treatment of bilateral tibial bowing related to osteogenesis imperfecta (Figure 1).

Her medical history included a diagnosis of osteogenesis imperfecta made at age 18 months due to repeated long bone fractures and progressive skeletal deformities. She reported no other medical illnesses or hospitalizations. Her past surgical history was negative.

Physical examination was positive for mild to moderate macroglossia. Airway examination revealed a Mallampati grade 2 airway. Neck flexion and extension were limited to approximately 30° from a neutral position. Cardiovascular examination revealed a midsystolic murmur with a click; previous echocardiography had revealed mitral valve prolapse with normal myocardial function without other abnormalities.

In the operating room, all pressure points were padded. After the placement of routine monitors, inhalation induction was performed with sevoflurane in 100% oxygen, and a 16-gauge intravenous catheter in place.

Ampicillin (1 g) was administered intravenously for subacute bacterial endocarditis prophylaxis. Following anesthetic induction, a laryngeal mask airway was placed without difficulty. Maintenance anesthesia consisted of sevoflurane in air/oxygen supplemented with fentanyl (total intraoperative dose: 3.5 mcg/kg) titrated according to the respiratory rate. The surgical procedure lasted 4 hours and 20 minutes during which estimated blood loss was 500 mL. Fluid administration included 2 liters of lactated ringers. Intraoperatively, the patient’s body temperature increased from 35.8°C to 37.8°C. At the completion of the procedure, the patient was turned into the lateral position and a caudal block was placed with 30 mL of 0.25% bupivacaine with 1 mcg/kg of clonidine. Sevoflurane was discontinued and the laryngeal mask airway was removed when the patient awakened. Her postoperative course was uncomplicated.

Patient 2

A 12-year-old, 46 kg boy presented for bilateral tibial osteotomies and intramedullary rod placement for the treatment of bilateral femoral bowing related to osteogenesis imperfecta (Figure 2). This patient was the younger sibling of Patient 1.

His medical history included a diagnosis of osteogenesis imperfecta type III made at age 6 months. He reported no other medical illnesses or hospitalizations. His past surgical history was negative.

Physical examination was positive for mild macroglossia. Airway examination revealed a Mallampati grade 2 airway. Neck flexion and extension were limited to approximately 45° from a neutral position. Additionally, there was moderate rotational scoliosis and the patient’s head was kept 30° from the midline. Cardiovascular examination was negative.

In the operating room, all pressure points were padded. After the placement of routine monitors, inhalation induction was performed with sevoflurane in 100% oxygen and a 16-gauge intravenous catheter in place. Cefazolin (1 g) was administered intravenously for surgical prophylaxis. Following anesthetic induction, a laryngeal mask airway was placed without difficulty. Maintenance anesthesia consisted of sevoflurane in air/oxygen supplemented with fentanyl (total intraoperative dose: 4 mcg/kg) titrated according to the patient’s respiratory rate. The surgical procedure lasted 3 hours 45 minutes during which time estimated blood loss was 400 mL. Fluid administration included 1.8 liters of lactated ringers. Intraoperatively, the patient’s body temperature increased from 36.8°C to 38.4°C. At the completion of the procedure, the patient was turned into the lateral position and a caudal block was placed with 30 mL of 0.25% bupivacaine with 1 mcg/kg of clonidine. Sevoflurane was discontinued and the laryngeal mask airway was removed when the patient awakened. His postoperative course was uncomplicated.

Summary

In the perioperative care of patients with osteogenesis imperfecta, difficulties with airway management, cardiovascular abnormalities, and coagulation defects are of primary importance, although the disease has multiple potential effects in several different organ systems (Table). Due to the propensity for this group of patients to develop fractures, great care must be taken when handling and transferring patients with osteogenesis imperfecta with attention to careful padding of pressure points after positioning on the operating room table.

No reports exist in the literature on the restriction of any specific anesthetic agent. Consideration should be given to limiting the use of anticholinergic agents given their association with intraoperative hyperthermia. Safe and successful general anesthetic care has been reported with the use of intravenous and inhalational anesthetic techniques.

Kill et al³⁴ reported the development of lactic acidosis without hyperthermia during the use of propofol for an intraoperative anesthetic. They could not offer a specific mechanism to explain what they had observed, but suggested surveillance and further investigation regarding the effects of short-term propofol infusions in children in general.³⁴

No similar problems with propofol in other patients with osteogenesis imperfecta have been reported. Although Libman¹¹ cautioned against the use of succinylcholine given the theoretical potential for fasciculations and fractures, no such problems have been reported in the literature although it has been suggested that succinylcholine be reserved for specific indications.¹³

In addition to general anesthetic techniques, several case reports outlined the use of spinal or epidural anesthetic techniques primarily in the obstetrical population.^35-37 Given the potential for an associated bleeding diathesis, normal coagulation function including platelet function should be demonstrated prior to performing neuraxial techniques. Although reported only once previously in the literature,³⁸ caudal anesthesia was found to be a safe and effective means of providing postoperative analgesia for both patients.

Following the surgical procedure, ongoing postoperative monitoring may be indicated in these patients. The same issues that may lead to difficult endotracheal intubation may place these patients at risk for postoperative obstructive issues when combined with the residual effects of general anesthetic agents.³⁹ Additionally, kyphoscoliosis and other thoracic skeletal deformities may predispose patients to postoperative respiratory failure.

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Authors

Drs Stynowick and Tobias are from the Department of Anesthesiology and Dr Tobias is from the Department of Child Health, University of Missouri, Columbia, Missouri.

Drs Stynowick and Tobias have no relevant financial relationships to disclose.

Correspondence should be addressed to: Joseph D. Tobias, MD, University of Missouri, Dept of Anesthesiology, 3W40H, One Hospital Dr, Columbia, MO 65212.