RU2230518C2 - Put-on hook for fixing of rod to spine rear parts - Google Patents

Abstract

FIELD: medicinal equipment, in particular, equipment for surgical correction and stabilization of diseased or injured spine.

SUBSTANCE: put-on hook has tongue made in the form of rectangle for attachment to bone structures and U-shaped base for attachment to rod. Hook tongue has end extending above base. Site of attachment of hook base to rod is equipped with longitudinal channels. Hook base contacting with outer surface of arch or transverse branch is made in the form of platform having width equal to width of hook tongue and exceeding thickness of hook base.

EFFECT: increased efficiency in surgical treatment of spine, reduced risk of complications owing to simplified mounting of construction and enhanced reliability in fixing thereof to bone structures and rod.

1 dwg

Description

The invention relates to medical equipment, namely to devices used for surgical correction and stabilization of the spine in case of its diseases and injuries.

A device for the surgical treatment of diseases and injuries of the spine, Cotrel Dubosset Instrumentation (CDI) of the Horizon system, which uses open hooks as a support-fixing element, which has a tongue for attachment to bone structures and a U-shaped base for attachment to the rod in the center (Promotional booklet, C.D. HORIZON Deformities Correction System, System for correction of spinal deformities “Infomedia, Ltd.” - 103287, Moscow, Petrovsko-Razumovsky pr., 29, 21 s).

The support-fixing contour of the hook tongue in contact with bone structures is insufficient, which leads to two types of complications. In the acute period, a fracture of the supporting bone structures is possible at the time of the correction when the derotation or translation is performed. In the long term after surgery, bone resorption occurs in the metal-bone contact zone, the hooks break apart and move relative to the bone structures. Instability arises, pseudoarthrosis develops with a loss of the achieved correction.

The rod is installed in a U-shaped opening of the base of the hook, which tightly covers the rod 1/2 (on both sides and from the bottom), which limits the maneuver and makes it difficult to install the rod in case of severe deformations and in unusual situations.

The depth of coverage of the bone structure by the tongue of the hook is insufficient, which leads to its rapid loosening and failure of fixation. In addition, when mounting the structure, an excessive amount of special tools for installing hooks is required (pediculate elevator 84626, implant holders 84689E, 89690E, 89691E, multi-function holder screwdriver 84694E, four-pole tool for initial installation of the fixing nut 84682E, translation tool for installing the fixing nuts 84697E, pusher hooks 84695 N and others), which complicates the installation of hooks, increasing the duration of the operation and blood loss.

The closest technical solution to the proposed device is another modification of the CDI, the Texas Scottish Rite Hospital system (Texas Scottish Rite Hospital, TSRH® Spinal System), which uses hooks with a tongue for attaching to bone structures and a U-shaped base for side mounts (Promotional booklet, TSRH® Spinal System Design Rationale, Sofamor Danek Grup, PL672 © 1994 DANEK, 12 c.)

Hooks in this system have the following design drawbacks: the U-shaped base of the hook is fixed to the rod on the side of one of the sides, on the plane of which there are two recesses for the rod with a smooth surface, which does not allow for rigid fixation and leads to the displacement of the hook relative to the rod in horizontal ( rotation) and sagittal (flexion) planes; the area of the support-fixing contour of the hooks in contact with the bone structures (tongue and the anterior support area of the base of the hook in the form of a rectangle) is insufficient, which leads to resorption of the bone in the metal-bone contact area, loosening and displacement of the hooks relative to the bone structures with the occurrence of instability, the development of pseudoarthrosis and the loss of correction; non-compliance with the principle of universality of hooks (i.e., 18 names of hooks of various sizes) is more confusing than the possibility of using the design in unusual situations, which complicates preoperative planning, increases the duration of the operation and blood loss;

In this regard, the TSRH system cannot be used for osteopenia and / or osteoporosis. In addition, the authors of the construction themselves recognize the possibility of undesirable consequences (early or late loosening of hooks, pseudoarthrosis, rod migration, bending, weakening or destruction of individual elements or the entire structure, loss of correction, physiological bending and growth), which is directly related to the above design flaws this system.

The objective of the present invention is to increase the effectiveness of surgical treatment, reduce the length of hospital stay and the risk of complications by simplifying the installation of the structure, increasing the reliability of fixing the hook to the bone structures and the shaft.

In solving this problem, there is a positive therapeutic and socio-economic effect, which manifests itself in an increase in the duration and rigidity of fixation of the spine, especially with osteopenia and osteoporosis, a decrease in the risk of complications, a reduction in hospitalization time, refusal of external immobilization and a decrease in the number of cases of disability and time stay on disability, which contributes to the most rapid and complete social adaptation of patients.

The technical result is achieved due to the fact that a hook is used with an increased area of the support-fixing contour (the tongue is elongated and stands above the base of the hook, the front area of the base of the hook is wider than the U-shaped base of the hook) in contact with bone tissue. These structural differences reduce the pressure on the bone tissue of the arch and significantly slow down the processes of bone resorption in the zone of contacting metal-bone surfaces. (Bone resorption weakens the fixation of hooks to the bone. Their loosening and displacement relative to the vertebrae leads to a loss of correction, instability and pseudoarthrosis). Rigid fixation of the hook to the rod is achieved by the fact that the rod fits into a recess located on the lateral plane of the branches of the U-shaped base of the hook. The recess covers 1/6 of the circumference of the rod and is equipped with longitudinal (along the longitudinal axis of the rod) furrows. The small coverage of the rod with recesses facilitates the installation of hooks. Furrows increase the coefficient of adhesion of the mating surfaces, which provides a rigid fixation of the hook to the rod and prevents the hook from moving relative to the rod in the horizontal (rotation) and sagittal (bending) planes.

Simplification of the mounting of the structure is achieved due to the fact that as a support and fixing elements, one universal hook size is used, which can be used for fixing by the transverse process or half-arm both from above and from below.

The problem is solved due to the fact that the hook tongue is in the form of a rectangle with the end standing above the base, the zone of attachment of the base of the hook to the rod has longitudinal grooves, the base of the hook in contact with the outer surface of the arch or transverse process is made in the form of a platform whose width is equal to the width of the hook tongue and exceeds the thickness of the hook base.

The invention is illustrated by graphic material, which presents a General view of the hook in the three-dimensional image (C), a top view (B) and in the side projection (A).

The hook consists of a tongue 1 and a U-shaped base 3. In the center of the base there is a U-shaped opening 4, in front there is a front platform 2. On both sides of the branches of the U-shaped base there are recesses with longitudinal grooves 5.

The hook is used as follows. Known methods provide access to the posterior spine. The hook is grabbed onto the base by sequestration forceps. The hook tongue is brought under the bone structure (half-arch, transverse process, rib or spinous process) from the bottom up or from top to bottom and advances until it is completely covered by the hook. Ear bolts are put on the rod. A rod with an eye bolt is brought to the recesses on the branches of the U-shaped base. The free screw end of the ear bolt is inserted into the U-shaped opening and the nut is screwed onto it so that the hook is freely fixed on the rod, but it can be freely rotated and moved around the rod. In the process of correction (contraction, distraction, translation), the nut is tightened to prevent sliding along the shaft. After performing the rotational correction, the nut is finally tightened to exclude rotational mobility. The wound is sutured in layers, leaving the tube of active drainage for two days.

Claims (1)

A hook for fixing rods to the posterior spine, having a tongue in the form of a rectangle for attachment to bone structures and a U-shaped base for attachment to the rod, characterized in that the tongue of the hook has a rectangular shape with an end protruding above the base, the zone of attachment of the base of the hook to the rod has longitudinal grooves, the base of the hook in contact with the outer surface of the arch or transverse process is made in the form of a platform, the width of which is equal to the width of the tongue of the hook and exceeds the thickness of the base of the hook.