Effects of alternative instrumentation strategies in adolescent idiopathic scoliosis: A biomechanical analysis

Abstract

The recent advent of modern instrumentation systems has improved the correction of scoliosis, but complicated the surgical decision-making process, especially with the introduction of diverse spinal fixation devices, new preoperative corrective maneuvers, and the reevaluation of many rules concerning the selection of fusion levels and other guidelines for surgical correction. Our objective was to assess the biomechanical effects of different instrumentation strategies for the same scoliotic cases. Several instrumentation strategies suggested by a group of 32 experienced senior surgeons for five cases were individually simulated using a validated computer model implemented in a spine surgery simulator. The resulting geometric indices varied among the five cases (e.g., range of main thoracic Cobb angles: 5-178, 16-298, 25-448, 15-348, 16-328; kyphosis: 22-338, 20-548, 33-558, 24-498, 29-468; and lordosis: 10-528, 24-388, 26-548, 8-288, 34-538). The average correction was better with pedicle screws (71%) than with hooks (51%) and hybrid constructs (67%). For the first time, to our knowledge, the effect of different instrumentation strategies was compared on the same patients, which is possible only with a surgery simulator. A large variability of instrumentation strategies existed among experienced surgeons and produced rather different results. This study questions the criteria for optimal configuration and standards to design the best surgical construct. ß

Computer simulation for the optimization of instrumentation strategies in adolescent idiopathic scoliosis

“…The kinetic model with flexible mechanisms and its validation, detailed elsewhere, [2,4,14,36] are summarized here. The spine model contains the thoracic and lumbar vertebrae (from T1 to pelvis) connected by intervertebral structures.…”

“…Computer models were thus created because they can provide a noninvasive and versatile tool to test various configurations of surgical instrumentations on the same patient [4,36]. A recent simulation study showed that variability in the instrumentation strategies significantly impacts the surgical results [36].…”

Patient‐specific computational biomechanics for simulating adolescent scoliosis surgery: Predicted vs clinical correction for a preliminary series of six patients

“…As mentioned earlier, a series of computer models have previously been developed to simulate the biomechanics of scoliosis surgery [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. These models have used varying approaches to deriving model geometry and material properties, but are all based on the use of 3D elastic beams and springs to provide a lumped parameter representation of the intervertebral joint stiffnesses.…”

“…A series of previous studies have applied computer simulation techniques, principally the finite element (FE) method, to the study of scoliosis. In particular, FE models have been used to explore the biomechanics of scoliosis surgery with a range of different implant types [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], the biomechanics of scoliosis progression (worsening of the deformity) during spinal growth [20][21][22][23][24], and the biomechanics of non-surgical scoliosis treatment using orthotic braces [25][26][27][28][29]. These models have convincingly demonstrated the value of FE simulations in developing treatment strategies to optimize deformity correction and reduce complications; however, they are currently limited in their ability to predict the response of individual spinal tissues (bones, discs, ligaments) to treatment, due to the simplified FE representations of the spinal joints.…”

Computer algorithms and applications used to assist the evaluation and treatment of adolescent idiopathic scoliosis: a review of published articles 2000–2009

“…Aubin et al [54][55][56][57][58] have developed kinematic model including flexible elements to represent each motion segment, implant-vertebra connections, kinematic joints and sets to model surgical instrumentation of the spine. The spine model is personalized to a specific patient using calibrated radiographs [59].…”