CA2723643A1 - X-plate - Google Patents

Abstract

A method for limiting growth of a bone growth plate in children is achieved by using a Tethered X-Plate as depicted in Fig 1. The Tethered X-Plate, made out of titanium, is composed of a centre section (1) in the centre of which a small hole (4) is located. It has four extensions (2) in which four holes (3) are located in which accept four screws (6). The centre to centre distance between two horizontal holes (2) is 16 mm for adolescent and 14 mm for children under the age of 10 years.
The four holes (4) are smoothly tapered (5) so that the screws (6) could be inserted in multi-directions as decided by a surgeon and as depicted in Fig 3. The surgeon by inserting a 0.8 mm temporary guide pin through the central hole (4) directly into the bone growth plate would be able to precisely locate the Tethered X-Plate and the multi-directional flexibility would allow the surgeon to install the screws (6) parallel to the patient's specific growth plate.

Description

Description Field of the Invention: Growth plates, also known as Epiphyseal Plates or Physis, are areas of growing cartilage tissues near the ends of long bones. The growth plate determines the future length and shape of a mature bone.

The long bones of the body do not grow from the centre outwards; rather, they grew at each end of the bone around the growth plate. When a child becomes full-grown, the growth plates harden into solid bone.

Since muscles and bones grow at different rates, a child's bones may be weaker than the ligament tissues that connect the bone to other bones. Therefore, early determination of abnormal growth of the growth plate and its treatment become extremely vital for the well-being of the child's future. These abnormalities could be hereditary or as a result of injury.

The Tethered X-Plate with its two extensions (2) on each side, which can accept 4mm screws (6) through the holes (3), would provide a temporary physical growth arrest in a child's growing bone. This is achieved by gradually guiding the natural growth of the growth plate, which in turn eliminates or minimizes the abnormal growth of the growth plate. By using this tethered X-Plate, an Orthopaedic surgeon can do a guided inhibition of the growth plate.

Background: Interest in mechanical disruption of abnormal physical growth of bone is as old as the concept of permanent surgical of epiphysiodesis. Similar devices and materials, such as Wire by Haas (1), Staples (one to three) by Blount (2), and Trans-Physical Screw by Metaizeau et al (3), have been used to shorten a bone growth or correct its angulations. But, many complications, such as implant failure (wire breakage, staple extrusion or breakage), recurrence of deformity, and inadvertent angular deformity because of eccentric horizontally insertion of staples or screws have been reported in literatures (4-6).

Recently, a new method by using an 8-shaped plate, called Eight-Plate, has been reported by Stevens et al (7). This plate, which is approximately 7 mm wide and has only two holes, affords only a point like tether on the physis and, if inserted eccentrically in horizontal direction, there could be a theoretical risk of undesired guided growth associated with it.

Similarly, the X-Plate by Beutter et al (8) lacks a central hole and furthermore since it has a slight curvature towards its inside, the plate cannot be precisely located over the bone's growth plate as well as that the screws converge to a single point. This significantly limits an Orthopaedic surgeon's flexibility and makes it extremely difficult for the surgeon to precisely locate and install the plate, and consequently increases the possibility of the converging screws to permanently damage the growth plate.

Summary of the Invention: Unlike the above mentioned similar devices, the described Tethered X-Plate spreads the point area of tether effect over a wider area (16 mm for adolescent and 14 mm for children under the age of 10 years as compared to 7 mm of the Eight-Plate for instance) and eliminates the possibility of some iatrogenic complications. As a result, the same results would be achieved regardless whether the Tethered X-Plate is installed, in the horizontal direction, on slightly posterior or anterior aspects of the growth plate.

The temporary guide pin inserted through the central hole (4) provides the surgeon with the ability to precisely locate the Tethered X-Plate over the bone growth plate in the vertical direction and the multi-directionality of the holes (2) ensures the screws (6) are inserted parallel to the growth plate, as opposed to converging to a point. This specification makes it as a safe temporary device to limit growth of a growth plate without any undesired harm effect on that growth plate.

References 1-Haas SL: Retardation of bone growth by a wire loop. J Bone Joint Surg Am 1945;27:25 2-Blount WP, Clark GR: Control of bone growth by epiphyseal stapling:
Preliminary report. J Bone Joint Surg Am 1949;31:464 3-Metaizeau JP,Wong-Chung J, Bertrand H, et al: Percutaneous epiphysiodesis using transphyseal screws (PETS).J Pediatr Orthop 1998;18:363.

4-Bylander B, Selvik G, Hansson LI, et al: A roentgen stereophotogrammetric analysis of growth arrest by stapling. J Pediatr Orthop 1981;1:81.

5-Inan M, Chan G, Littleton AG, Kubiak P, Bowen JR. Efficacy and safety of percutaneous epiphysiodesis.J Pediatr Orthop 2008 ;28(6):648-5 1.

6-Campens C, Mousny M, Docquier PL: Comparison of three surgical epiphysiodesis techniques for the treatment of lower limb length discrepancy.
Acta Orthop Belg 2010; 76(2):226-32.

7-Stevens PM, Joshua BK: Guided Growth for Pathological Physes. Radiographic Improvement During Realignment. J Pediatr Orthop 2008;28:632-639.

8-Beutter et al: X-Plate (KR2006123370 A) Brief Description of the Drawings Having thus described the invention, reference will now be made to the attached drawings, which are not necessarily drawn to scale:

Fig 1: shows schematically a top view of the Tethered X-Plate identifying different sections of the Plate.

Fig 2: shows a cross section of the tethered X-Plate and its different sections.
Fig 3: shows an isometric view of the Tethered Plate and its different sections.

The plate is composed of four identical extensions (2), as shown in Fig 1, which are attached to the central body (1). Each extension has a 4mm smoothly tapered hole (3,5) via which fixation of the Tethered X-Plate to the bone through four screws (6) could be done(Fig 3). The width of the extensions is 11 mm with a mm radius filleted steep around the hole, as shown in Fig 2. The central body (1) of the Tethered X-Plate is 12 mm in diameter and has a central hole of 1 mm(4).
The central hole can take a 0.8 mm guide pin, which can be used to locate precisely the growth plate under fluoroscopic control. The center to center distance between two horizontal holes (3,5) is 16 mm for adolescent and 14 mm for children 10 years old and under. The thickness of the plate is 2 mm, as shown in Fig 2.

Claims (2)

1. A method for limiting growth of growth plates in children's bones is achieved by installing a Tethered X-Plate over the patient's specific growth plate. The Tethered X-Plate, Fig 1, with its central hole (4), would be centered over the bone's growth plate via insertion of a temporary guide pin through the hole (4) directly into the growth plate. The Tethered X-Plate is then screwed on with two screws (6) on each side through the holes (2). This would not only allow the Tethered X-Plate to bend according to the shape of the bone's surface and remain fixed via four screws (6), it would also prevent the Tethered X-Plate to be off centered in vertical direction hence completely eliminating any possibility of the screws (6) damaging the growth plate.

2. The method according to Claim 1, by providing a uniform tether effect on a wider area (16 mm for adolescent and 14 mm for children under the age of years), prevents asymmetric growth of the growth plate even when the Tethered X-Plate is installed slightly eccentric in the horizontal direction.