Implications of metallosis after scoliosis treatment with magnetically controlled growing rods

Professor Cheung, Jason Pui Yin   (Principal Investigator (PI))

Professor Zhang Teng Grace   (Co-Investigator)

24

2021-06-30

112460

Implications of metallosis after scoliosis treatment with magnetically controlled growing rods

immunohistochemistry, MCGR, metallosis

Orthopaedics/Traumatology

Biology and Medicine (M)

202011159013

Seed Fund for PI Research – Basic Research

2020

Completed

Early onset scoliosis (EOS) is a difficult condition to treat as these spinal deformities affect a group of very young children with significant spine and pulmonary growth potential. Growing rods are the gold standard for treatment of EOS because it allows regular distractions of the rod to allow the spine to lengthen as the child grows. However, these traditional growing rods require surgical lengthening every 6 months for spinal growth to allow the patient recovery in between. This amounts to a significant number of surgeries. A 5-year old girl who reaches skeletal maturity at the age of 13 will require 16 operations for distraction purposes alone. These multiple surgeries carry increased anesthetic and wound complication risks. Magnetically controlled growing rods (MCGRs) have revolutionized the management of EOS. In addition to providing similar clinical and radiological results as traditional growing rods, it allows non-invasive lengthening of the spine that can be performed in an out-patient setting. More frequent distractions of the rod are also possible to better mimic normal spine growth. With such benefits of rod lengthening without surgery, the MCGR has become one of the most popular management options for EOS. Despite these advantages, there are growing concerns regarding several complications that have become apparent now that the MCGR has been in use for nearly a decade. One particular complication of note is metallosis whereby black wear particles are found within the soft tissues around the implant. The exact cause and components of the metallosis is still uncertain but as these young patients with EOS have yet to reach their childbearing age, there may be long-term implications including teratogenicity and carcinogenicity. Due to these concerns, we aim to discover the underlying mechanisms generating metallosis, its components and immune reactions. We hypothesize that increased bending moments on the MCGR lead to more metallosis. Moreover, metallosis causes pro-inflammatory changes in the surrounding soft tissue. The implications of our findings will reach significant global impact since new MCGR surgeries are performed at an exponential rate. Our findings will possibly lead to implant and technique modifications to benefit these young children with spinal deformities. Hence the objectives of this proposal are: 1. To examine the relationship between wearing cycles and the quantity and components of metallosis. 2. To classify the local tissue immunological reaction to metallosis.