Intravital Measurements During Instrumental Correction of Idiopathic Scoliosis

Abstract

In 1958, on joining the staff of the New York Orthopedic Hospital, it was my good fortune to become associated with several men who were deeply interested in the problems of scoliosis and spine fusion, in fact, an interest that has been maintained since the original work of Hibbs with this disease. This investigation has consisted of two parts, the first of which, the clinical, began when Professor Frank E. Stinchfield made me responsible for the Scoliosis Service at Columbia University. With a background of over 2,500 surgically treated patients with spinal deformity, the majority of whom have been carefully followed, it was believed that the New York Orthopaedic Hospital could provide valid conclusions about the efficacy of existing treatment. In 1965, the second phase, the experimental, was begun in the Biomechanics Laboratory of the University of Gothenburg. Professor Carl Hirsch has provided the facilities, encouragement, and personal guidance which enabled this work to be carried out. Any study of this nature depends upon the cooperation and assistance of many people. I would like to thank the staff at the Orthopedic Clinic for their suggestions and cooperation. During the execution of particular phases of this project, technical problems arose which required the assistance of specialists from other institutions. I would particularly like to thank Engineers Sören Rolandsson and Hans Akesson of the AB Atomenergi in Studsvik,

Measurement of forces generated during distraction of growing-rods in early onset scoliosis

“…It is known however that the load to failure of a thoracic lamina instrumented with a hook is around 670 N in the adolescent [12] and that recommended values of distraction force with Harrington instrumentation did not exceed 400 N [13] . In our patients, growing-rods were positioned on the concavity of the scoliotic curve like Harrington rods, and the attachment to bone was via pedicle screws or laminar hooks at the bottom levels, lower thoracic or lumbar, and via laminar and pedicle hooks at the upper thoracic levels.…”

Implantable sensor technology: measuring bone and joint biomechanics of daily life in vivo

“…Around the same time as Rydell's attempt to measure hip forces, Waugh used Harrington rods instrumented with strain gages for spine fixation to measure forces in vivo [37]. As with Rydell's femoral component, the strain gages on the Harrington rods connected via percutaneous wires allowed measurement for only one day.…”

Results of the spine-to-rib-cage distraction in the treatment of early onset scoliosis

“…Two rods were then contoured for sagittal balance, connected to the hooks and/or screws and implanted in a subfascial position on the concavity of the coronal curvature as in previously designed spinal systems 47. At 10-s time interval every 2 mm of distraction was observed in order to allow for the viscoelastic properties of the spinal soft tissues to act 89. The distraction normally stopped after 15–20 mm of elongation and in any case until the implant demonstrated inability to sustain further manual elongation without undue signs of rotation or dislocation.…”