Methods and apparatus for coupling a prosthesis to a spinal segment

Inventors

Alamin, Todd • Kothari, Manish • Malandain, Hugues • Cahill, Colin • Fielding, Louis

Assignees

Empirical Spine Inc

Abstract

A method for coupling a prosthesis to a spinal segment in a patient includes the steps of selecting first and second reference points disposed along the spinal segment and pre-operatively measuring a target distance. The target distance extends between the first and second reference points while the patient is in a preferred posture such as the standing position. A prosthesis is coupled to the spinal segment and the prosthesis is then intra-operatively adjusted in order to set the distance between the first and second reference points based on the target distance.

Core Innovation

The disclosure describes methods and apparatus for coupling and intra-operatively adjusting a spinal flexion-constraining prosthesis. Pre-operative target measurements in a preferred patient posture, together with radiographs, are used to set a neutral distance and/or an estimated prosthesis circumference for the prosthesis. The system links the prosthesis or treatment to restricting flexion while permitting extension to reduce pain/instability in conditions described in the disclosure.

The disclosure further describes an elastic tether assembly with compliance elements. Compliance elements are configured to elastically elongate under tension, while a constraining tool is releasably coupled with the compliance element to hold it in a desired position and allow a predetermined amount of elastic elongation. Constraining tool designs are described for temporarily preventing compliance-element elongation during adjustment.

The disclosed workflow includes threshold pain/instability postures, radiopaque markers, dynamic imaging, and measurement of anatomical parameters. Radiopaque markers and measured parameters are used to select and verify implant parameters, including target distance and neutral position concepts. Constraining tools are described with lumens and a locking mechanism to enable concentric alignment of a driver with the locking mechanism, and provision of counter-torque.

The system is described for use with a tether structure coupled with a spinal segment or spine and includes a first compliance element and, in some configurations, a second compliance element. Symmetrical pair constraining tools across a spinal midline are described to align and position compliance elements on opposite sides, with adjustable features for varying the desired position and additional constraints that limit extension or elongation after the predetermined amount of elastic elongation.

Claims Coverage

Independent claims clm-00001 and clm-00011 define a system for restricting flexion of a spinal segment, each centered on a tether or coupled compliance element that elastically elongates under tension and a releasably coupled constraining tool that holds the compliance element in a desired position to allow a predetermined amount of elastic elongation. Across the independent-claim scope, the stated inventive features include tether/compliance coupling, releasably holding to permit predetermined elastic elongation, and optional structural or functional refinements appearing in dependent claims such as symmetric opposite-side coupling, locking and lumen/driver alignment, and post-elongation limitation.

Across clm-00001 and clm-00011, the claim coverage is directed to restricting flexion by coupling a compliance element that elastically elongates under applied tension to a spinal segment, and using a constraining tool releasably coupled to hold the compliance element in a desired position while permitting a predetermined amount of elastic elongation. Dependent claims further narrow and extend this concept by adding specific constraining-tool structures, optional post-elongation limitation, and configurations including symmetric opposite-side placement and locking or driver-alignment features.

Stated Advantages

Documented Applications