**4. Discussion**

**Figure 2.** (A) Hanging from a door or bar, (B) chair bends, (C) bending on a roll, (D) lying on two chairs, and (E) bending

Postoperative exercises were designed to activate the ratchet mechanism and to further elongate the distance between the pedicle screws. Two to three weeks after surgery, patients are directed to perform five basic Schroth-like exercises that enabled gradual elongation of the ratchet mechanism, leading to further curve reduction (**Figure 2**). The patients bend towards the corrective direction, and the device maintains the designated correction after the patients'

(1) Hanging from an open door or bar; the exercise begins with both hands holding the door top with the hips and knees bent at 90°, while the knees and toes lean on the door. By extending the

return to the neutral position. There are five basic exercises:

over the band.

**2.4. Postoperative exercises**

186 Innovations in Spinal Deformities and Postural Disorders

The current communication describes a unique approach to moderate AIS curve correction. The new approach combines operative curve correction followed by additional correction with exercises performed after the surgery. The designated scoliosis specific exercises become an integral part of the treatment protocol with the ratchet device. This differs dramatically from scoliosis correction by spinal fusion. By avoiding spinal fusion, natural spinal motion

**Figure 3.** Case 1: (A) Preoperative standing AP X-ray, (B) postoperative standing AP X-ray, and (C) after 3 months of exercises. The expandable rod has elongated with further curve reduction.

is preserved by in large and allows further curve correction by exercising. The novel ratchet spinal implant may be looked upon as an internal brace. It is, therefore, logical to combine the internal brace with scoliosis specific exercises. Schreiber et al. in a randomized controlled study on nonoperative management of AIS reported that a combination of standard of care of AIS including bracing with Schroth scoliosis specific exercises gave a better curve correction than care without exercises [8]. Our novel concept and method also combine a brace, although internal, and exercises in the management protocol. The postoperative quasi Schroth corrective exercises help in reducing the final Cobb angle. Schreiber suggested that Schroth exercises should be considered as an add-on to the standard of care of AIS. Likewise, the correcting exercises after ApiFix® implantation should also be viewed as an add-on to surgical treatment. Theoretically, the combination of exercises with ApiFix® surgery may be more efficient than external bracing and Schroth maneuvers as the ratchet mechanism captures the correction gained during exercises.

The biomechanical properties of the ApiFix® ratchet device were investigated by Holewijn et al. [9]. They performed a biomechanical study on cadaveric thoracic spines in which they compared spinal motion with the ApiFix® device or with rigid pedicle screw fixation. The ratchet device caused a 40% decrease in range of motion in flexion/extension and about 18% in lateral bending, while the range of motion in axial rotation remained unaffected. In comparison, rigid instrumentation caused a significantly (p < 0.05) larger decrease in range of motion in flexion/extension (−80.9%), lateral bending (−75.0%), and axial rotation (−71.3%). The study of Holewijn et al. [9] showed that spinal range of motion was significantly less constrained by the ratcheted device as compared to rigid pedicle screw-rod instrumentation. Therefore, it can

Fusionless Correction of Moderate Adolescent Idiopathic Scoliosis with a New Minimally Invasive Dynamic... http://dx.doi.org/10.5772/intechopen.69457 189

is preserved by in large and allows further curve correction by exercising. The novel ratchet spinal implant may be looked upon as an internal brace. It is, therefore, logical to combine the internal brace with scoliosis specific exercises. Schreiber et al. in a randomized controlled study on nonoperative management of AIS reported that a combination of standard of care of AIS including bracing with Schroth scoliosis specific exercises gave a better curve correction than care without exercises [8]. Our novel concept and method also combine a brace, although internal, and exercises in the management protocol. The postoperative quasi Schroth corrective exercises help in reducing the final Cobb angle. Schreiber suggested that Schroth exercises should be considered as an add-on to the standard of care of AIS. Likewise, the correcting exercises after ApiFix® implantation should also be viewed as an add-on to surgical treatment. Theoretically, the combination of exercises with ApiFix® surgery may be more efficient than external bracing and Schroth maneuvers as the ratchet mechanism captures the correc-

**Figure 3.** Case 1: (A) Preoperative standing AP X-ray, (B) postoperative standing AP X-ray, and (C) after 3 months of

exercises. The expandable rod has elongated with further curve reduction.

188 Innovations in Spinal Deformities and Postural Disorders

The biomechanical properties of the ApiFix® ratchet device were investigated by Holewijn et al. [9]. They performed a biomechanical study on cadaveric thoracic spines in which they compared spinal motion with the ApiFix® device or with rigid pedicle screw fixation. The ratchet device caused a 40% decrease in range of motion in flexion/extension and about 18% in lateral bending, while the range of motion in axial rotation remained unaffected. In comparison, rigid instrumentation caused a significantly (p < 0.05) larger decrease in range of motion in flexion/extension (−80.9%), lateral bending (−75.0%), and axial rotation (−71.3%). The study of Holewijn et al. [9] showed that spinal range of motion was significantly less constrained by the ratcheted device as compared to rigid pedicle screw-rod instrumentation. Therefore, it can

tion gained during exercises.

**Figure 4.** Case 2: (A) Preoperative standing AP X-ray and (B) postoperative standing AP & lateral X rays, and (C) after 9 months of exercises. The expandable rod has elongated with further curve reduction. D1: Scoliometer measurement before surgery 7. D2: Scoliometer measurement after surgery 2.

be assumed that the concave ratchet device enables scoliosis correction with preservation of a more physiological spinal motion. Holewijn et al. [9] also found that adjacent segment biomechanics were not significantly altered. These beneficial biomechanical characteristics can be attributed to the polyaxial connectors between the implant and screws. Therefore the risk of implant failure is deemed low as implant loads in the absence of spinal fusion are expected to be minimal.

At the time of writing, the new dynamic device was utilized in over 100 cases in Europe and Israel. The clinical outcome observed in those cases documented that curve correction and stabilization of moderate AIS without concomitant fusion were both efficient and durable (unpublished results). Although there were few failures, analysis of the failed cases revealed that each failure was related to operation on curves bigger than 60°, rigid curves or to improper pedicle screw placement. In properly selected candidates for instrumentation with ApiFix®, no implant failures or loosening were observed. The clinical experience gained lends support to the view that the ratchet device is a valid alternative to traditional standard surgery with long instrumentation and fusion. The main curves (Lenke 1 or Lenke 5) were reduced, and curve reduction was maintained during the follow-up period. Although the ApiFix® device operates in a distraction mode that may produce kyphosis, there was no clinically significant change in the sagittal curves of the spine in the operated patients. Long term, 2–4 years follow-up, of a cohort of operated patients showed no curve progression, adding on, or implant failure.

Curve correction without fusion in the management of AIS is not a new concept. Fusionless scoliosis surgery has the benefit of curve correction without limiting spinal motion. Betz et al. [5] and Samdani et al. [6] reported growth-modulating convex vertebral body stapling and/or convex vertebral body tethering as a nonfusion surgical alternative for idiopathic scoliosis that occurs before the onset of the adolescent growth spurt. The published clinical results of that technique are promising [4–6]. The indications chosen for the use of ApiFix® in managing moderate AIS are almost identical to the indications of vertebral body tethering, although the surgical approach (posterior vs. anterior) and the age of the patients are different [6]. Some of the shortcomings of vertebral body tethering/stapling include the inability to predict the amount of curve correction and whether overcorrection will occur. In contrast, the final curve correction with ApiFix® can be predicted to closely match the magnitude seen on the preoperative bending views, and there is no possibility of overcorrection.

In addition to the loss of natural spinal motion, standard fusion surgery has additional disadvantages, including considerable blood loss, requiring blood transfusions [10, 11], a 12% prevalence of non-neurologic complications [11, 12], late infections, and pseudoarthrosis. Almost all complications can be avoided by the use of ApiFix®: specifically, there is minimal blood loss and no need for blood transfusion, the prevalence of non-neurologic complications is negligible, neurological complications can be expected to be significantly reduced by the use of only two pedicle screws and the gradual nature of the deformity correction, and there is no risk of pseudoarthrosis since fusion is not attempted. The ultra-short operative time and hospital stay are also significant advantages.

In conclusion, our experience with this novel dynamic device demonstrated consistent curve improvement and stabilization. It lends support to the concept that surgery with this new posterior dynamic device combined with postoperative scoliosis specific exercises may be a viable alternative to fusion and and non-compliant brace users for managing moderate AIS curves.
