Case Report Type I Osteogenesis Imperfecta: Diagnostic Difficulties H. Bischoff 1 , P. Freitag 2 , G. Jundt 3 , B. Steinmann 4 , A. Tyndall 1 and R. Theiler 1 Departments of 1 Rheumatology, 2 Radiology and 3 Pathology, University Hospital Basel, and 4 Department of Pediatrics, University Hospital Zurich, Switzerland Abstract: A 65-year-old woman presented with verteb- ral fractures of the lumbar spine and a history of pathological fractures following minor trauma, which had occurred before the onset of menopause. Her past medical history was significant for intermittent low back pain since childhood, which was attributed to thoraco- lumbar scoliosis. A diagnosis of unclassifiable osteo- porosis was made until invasive diagnostic procedures suggested a mild form of type I osteogenesis imperfecta (OI). In unclear or atypical perimenopausal osteoporosis and diagnosis of OI should be considered. Keywords: Diagnosis in osteoporosis; Osteogenesis imperfecta; Osteoporosis Introduction Osteogenesis imperfecta (OI) is a genetic disorder causing defects in the structure or synthesis of type I collagen. Most cases result from mutations in the genes coding for the proa 1 or proa 2 chains of type I collagen. Clinical features can include secondary osteoporosis, fragile bones, hyperextensible joints, adult hearing loss, dentinogenesis imperfecta and blue sclera. Forms of OI, depending on the underlying mutation at gene level and inheritance, range from perinatal death to undiagnosed mild cases. The different forms of OI were classified by Sillence in 1978 [1–3]. Case Report A 65-year-old Caucasian woman was admitted with increasing low back pain over several months. There had been no associated trauma. Her past medical history began during school years with low back pain. This was diagnosed as being secondary to a thoracolumbar scoliosis. She had two uncomplicated pregnancies at age 33 and 37 years, during which the back pain increased. At the age of 34 years she underwent a lumbar discectomy at L4–5 plus an L5 laminectomy. During this hospitalisation she had sudden unexplained loss of all her teeth, requiring artificial dentition. At age 46 years she sustained a fracture of the right tibia caused by minor trauma. This was complicated by osteomyelitis, which required additional surgical intervention. As a result, her back pain worsened and she began to use crutches. Menopause occurred at 47 years of age. At age 54 years, the patient fractured her left ankle and right radius, and again at age 55 years fractured both radii. She began to use a corset following fractures of the 11th and 12th thoracic vertebrae at age 56 years. An intertrochanteric fracture of the right femur occurred when she was 62 years old. All fractures were caused by minor trauma such as stumbling from a standing position. Born in 1929, she married in 1952 and worked as a cashier until retirement in 1991. From 1987 to 1991 she received a 50% disability pension. She smoked one pack of cigarettes per day for 40 years and consumed three glasses of wine per day. Her family medical history was not contributory with no reports of pathological fractures in any first degree relatives. A clinical examination revealed fixed kyphosis of the lower thoracic spine and left convex thoracolumbar scoliosis. At a height of 164 cm and a weight of 91 kg Clin Rheumatol (1999) 18:48–51 ß 1999 Clinical Rheumatology Clinical Rheumatology Correspondence and offprint requests to: H. Bischoff, Geriatrische Universita ¨tsklinik, CH-4031, Basel, Switzerland. Tel: +61 265 2525.