Interdisciplinary Care Improves Functional Mobility in an Individual with Type IX Osteogenesis Imperfecta

Osteogenesis imperfecta (OI), in its typical form, is a genetic disorder of type I collagen. OI may be mild causing a few fractures to severe with hundreds of fractures in a lifetime. Characteristics in individuals with moderate to severe OI include short stature, multiple fractures, muscle weakness, joint laxity, skeletal deformities, hearing loss, curvature of the spine, blue sclera, and/or diffuse osteopenia which challenges their overall mobility [4, 9]. The traditional classification of OI by Sillence is a four-type subdivision [13]. Types I–IV are a heterogeneous group due to type I collagen gene mutations. Type I, the most prevalent with the lowest fracture risk, are community walkers. Type II is lethal in the perinatal period. Type III is moderate to severe with multiple fractures and progressive bone deformity, therefore typically limited to household ambulation. Type IV is between type I and III with moderate risk of bone deformities and fractures, but those affected are typically community walkers. The revised OI classifications now identify at least eight types of OI, and research continues to identify more recessive forms [16, 17]. Types V through VIII are recessive forms, with mutations in genes other than COL1A1 or COL1A2; these types present with moderate to severe characteristics and are approximately less than 10% of all OI cases [7]. Type IX OI was recently identified as an autosomal recessive form due to a homozygous mutation in the PPIB gene [1]. Individuals with type IX present with clinical features similar to individuals with type III or IV but have radiographic features of a recessive form of OI including wide and/or flat bones and popcorn lesions in the growth plates [1]. Over the last decade, the interdisciplinary care of bisphosphonate treatment, surgical rodding, genetic testing, and rehabilitation has resulted in improved functional abilities in children with moderate to severe OI [4, 5, 7, 18]. Optimal care occurs with an interdisciplinary care approach working toward the goal of independence in self-care and mobility. Surgical osteotomy and intramedullary (IM) rod placement may be indicated for children with multiple fractures and long bone deformities. The goal of IM rodding is to provide internal stability, correct deformity, reduce fractures, and promote proper alignment throughout growth for weight bearing [4]. The Fassier and Duval telescopic growing rod technique has resulted in fewer surgeries, lower complication rates, less rod migration, shorter recovery, and improved mobility [4, 5, 10, 18]. General rehabilitation guidelines have been developed by the OI Foundation [9], Shriners Hospital for Children in Canada [4], Campbell [2], and Gerber [6]. Physical therapy (PT) is essential in facilitating family education, safe weight bearing, aerobic conditioning, and strengthening in a safe environment while maximizing gait and functional independence. Literature review yielded minimal published rehabilitation studies on individuals with OI. Caudill et al. [3] reported decreased ankle strength and functional limitation in individuals with type I versus healthy peers. Children with type I and IV OI also have reduced exercise capacity, muscle force, and overall cardiopulmonary function compared to typically developing peers [14, 15]. There are no case studies focused on rehabilitation and none specific to type IX OI. The purpose of this case report is to illustrate rehabilitation and functional mobility progression in an individual with type IX OI following bilateral femoral and tibia osteotomies with IM rodding over the course of the first two post-operative years.