Retrospective monocentric study.
To report radiologic outcomes of a consecutive series of AIS patients, operated with a bivertebral autostable claw for the upper instrumentation over a 5-year period.
Summary of background data
The upper fixation represents the weakest part of long constructs because of local anatomy and the high pull-out forces. Various implants have been proposed, but proximal junctional failures (PJF) and shoulder imbalance still occur with variable incidence. The autostable claw is a new implant, safe, and low profile, combining the mechanical strength of hooks with the initial stability of pedicle screws.
All AIS patients operated between January 2010 and July 2015 for a Lenke 1 or 2 curve with the bivertebral autostable claw were included. A minimum 2-year follow-up was required. Full-spine biplanar stereoradiographs were performed preoperatively, within 8 weeks postoperative and at latest examination. Local and global sagittal and coronal parameters were analyzed and complications were reported.
237 patients (191 Lenke 1 and 46 Lenke 2) were included, with a mean follow-up of 4.1 ± 0.6 years. PJF occurred in 2 patients (0.8%), and radiologic PJKs were observed in 8.4% of the series. Shoulder balance was efficiently restored or maintained in 88.2%.
The bivertebral autostable claw is a safe and robust alternative to pedicle screws for proximal fixation in AIS long constructs. Compression and/or distraction can be applied to level shoulders, and mechanical failures remain rare at 4-year follow-up.
Level of evidence
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Conflict of interest
ALS (none), EF (none), KM (other from Implanet, outside the submitted work), BI (other from Implanet, Zimmer Biomet, and Medtronic, outside the submitted work).
Retrospective study approved by the Local Ethic Committee.
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Simon, A.L., Ferrero, E., Mazda, K. et al. Bivertebral autostable claws for the proximal fixation in thoracic adolescent idiopathic scoliosis surgery. Spine Deform (2020) doi:10.1007/s43390-020-00040-5
- Adolescent idiopathic scoliosis
- Upper instrumented vertebra
- Autostable claw
- Shoulder balance
- Sagittal balance