GB2362830A

GB2362830A - Cement restrictor

Info

Publication number: GB2362830A
Application number: GB0106980A
Authority: GB
Inventors: Sanjay Valmikrao Sonanis
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-05-31
Filing date: 2001-03-21
Publication date: 2001-12-05
Anticipated expiration: 2021-03-21
Also published as: GB0013035D0; GB2362830B; GB0106980D0

Abstract

A cement restrictor for plugging a bone canal comprises a main body 4 with ridges which anchor against the medullary surface of the bone, and a plunger 3 connected to a diaphragm 2 said plunger expanding the main body when inserted thererin. The main body may have a female screw thread to which a male screw thread at one end of a solid rod can be fitted, so that in use a pusher 1 telescopically fitting over the solid rod can be used to insert the plunger into the main body. The main body may contain a small metallic ball as an X-ray marker. The cement restrictor may be made of any biocompatible material.

Description

2362830 1 Sonanis intramedullary Cement/Canal Universal Restrictor,

Expandabte'(SICURE) Your Reference GB 00 113035.1 Author Mr SANJAY VALMIKRAO SONANIS MBBS; MS Orth (Bom), MCh Orth (UK) SPR, Royal Halifax Infirmary, Halifax, United Kingdom.

Address for Correspondence 1, Teal Court, Steeton Keighley, West Yorkshire BD20 6UW, United Kingdom. Tel & Fax: 00 44 1535 657632 E-mail: SVSONANIS@aol.com Technical field

The present invention relates to a new bony canal plug called 'Sonanis Intramedullary CementICanal Universal Restrictor, Expansile' (SICURE). This device can be used for primary and revision joint replacement surgery (JRS) in the human or any living body. Its main use is in the bony canal to block the further migration of the cement or the bone graft or the plug ftself before or during implant insertion in its final position. It helps to gain a good tight fit of the prosthesis in the bone to increase the longevity of the JRS in the body. It can be used for any surgery where the bony medullary canal needs blocking e.g. Hip replacements, Knee replacements, Elbow replacements etc.

SICURE can be made from biocompatible material which body accepts e.g. plastic (high density polyethylene), metal or bioabsorbable, material e.g. polyglycolic acid.

2 Background

Various plugs have been used in past for joint replacement surgery. But because they are not expandable they cannot be locked in the bone especially when placed distal to isthmus where the bony canal diameter widens distally. When the cement or bone grafts are inserted in the bony canal under pressure there is tendency of the plug get dislodged distally in the canal and on insertion of implant it gets displaced further. So the optimum pressure of the cement or bone graft in the medullary canal is not obtained. This also fails to obtain a good tight fit of the implant in the bone. Inadequate intramedullary pressure causes potential gaps between the cement and the bone; and also between the cement and the implant, thus causing early loosening and failure of joint replacements. Similar problems can occur during revision joint replacement surgery where the impaction bone grafting technique is used and the plug could get displaced distally due to increase pressure of the impacted bone grafts causing insecure fixation and subsidence of the implant causing laxed joint, dislocations and shortening of the limb.

The SICURE implant as the name suggests is designed to avoid the above problems and secure the plug during primary or revision JRS. It can be expanded (opened) in the intrameduflary canal by a locking device at the required site to maintain its position even during high pressures. The cement or the bone grafts can be pressurised over it and a stable fixation of implant can be achieved. It can also be used universally in other joint replacements or bones for blocking the intramedullary canal for various other indications.

Essential technical features SICURE is made up of three main parts 1. Main body (Shuttle cock) Figure 1 & 2 It is a conical, shuttlecock shaped main body Mth a narrow distal end and a broader proximal end. The broader end has finns or petals which can be opened out on pushing the plunger with in K. On to the narrow end at the base of all the finns where they are held together K has a hole in the centre with female screw threads to hold the rod held by a gun for its insertion. The shuttle cock also has a small metallic ball at the base near the central hole which acts as a marker seen on the x-ray to show the position of the shuttle cock in the bone. The outer surface of the shuttle cock has ridges to anchor on the medullary surface of the bone. On inner surface of the shuttle cock there are female threads to lock in the plunger.

2. Plunger with Diaphragm Figure 1 & 2 The plunger is again a cone shape peg wfth a bigger circular disc on its base. The side of the plunger is oblique and ft has mate threads so as to lock inside the shuttle cock. The diaphragm on the broader end of the plunger has oblique radial slits to over tap the diaphragm edges to prevent leakage of the cement or bone graft. The plunger and the diaphragm has a axial tunnel to accommodate the cylindrical solid rod to hold the shuttle cock.

3 3. Gun with two telescoping rods The instrumentation used to hold the above assembly together has a gun on one end holding the two telescoping rods. On pulling the trigger the outer sleeve rod gets pushed distally over the inner solid rod. The inner solid rod has threads at the distal end to hold the shuttle cock in its position and the sleeve on the rod acts as a pusher pushing the plunger and the diaphragm together distally when forced in action (Figure 3A & 313). The plunger and the diaphragm forces the the shuttle cock to open mechanically and lock in place in the bone.

Procedure The device is assembled wfth the solid threaded rod distal end being screwed in the shuttle cock and the diaphragm with plunger threaded on R. The cannulated rod is passed over the solid rod and held with the gun on the other end. The After preparing the bony canal, the unexpanded SICURE is inserted in the intramedullary canal by the surgeon at the required site. The gun is put into action and the cannulated rod is moved distally to push the diaphragm with the plunger to force open the shuttlecock, while the shuttle cock still held in place by the solid rod. Expanded SICURE is anchored and is locked on to the inner wall of the bone thus securing its place. After this either cement is pressurised or the bone impaction technique is carded out before inserting the final implant for JRS.

Illustrations Figure 1. Shows the dose-up cut section View of the SICURE as seen from the side.

Figure 2. Shows the perspective view of the SECURE from the top.

Figure 3. A. SICURE loaded with the assembly. B. SICURE when expanded.

Figure 4. Final expanded position of the SICURE locked in with the plunger.

4

Claims

Sonanis Intramedullary Cement/Canal Universal Restrictor, Expansile (SICURE) is a plug used to block the bony canal during primary and revision joint replacement surgery (Figure 1 & 2).
2. A plug as claimed in Claim 1, SICURE includes Shuttle cock, Plunger with a diaphragm, and a gun with two telescoping rods.
A plug as claimed in 1, and 2 where the plunger with the diaphragm is pushed into the shuttle cock by the telescoping rod and the shuttle cock is opened in the bony canal (Figure 3A & 313).
4. A plug as eJaimed in 3, where the plunger has male threads to lock into the female threads of the shuttle cock and the outer surface of the shuttle cock has ridges to anchor in the bone.
5.

A plug as claimed in any preceding claim that the inner solid rod holds the shuttle cock at one end and the cannulated rod pushes the plunger with the diaphragm in the shuttle cock with the help of a gun.
6. A plug as claimed in any preceding has a diaphragm on the plunger with radial sifts to accommodate various diameter of the bony canal.
7. A plug as claimed in any groceeding which is made from biocompatible material like plastics, metal, or bioabsorbable (bioresorbable) material or combination of these materials.
8. SICURE the bone plug as described is illustrated in the accompanying drawings Figure 1,2,3, and 4.

8. SICURE the bone plug as described is Mustrated in the accompanying drawings Figure 1,2,3, and 4.

Amendments to the claims have been filed as follows Sonanis Intramedullary Cement/Canal Universal Restrictor, Expansile (SICURE) is a plug used to block the bony canal during primary and revision joint replacement surgery (Figure 1 & 2).

A plug as claimed in Claim 1, SICURE includes Shuttle cock, Plunger with a diaphragm, and a gun with two telescoping rods.

SICURE as claimed in 1, and 2 has a plunger with the diaphragm which is pushed into the shuttle cock by the telescoping rod and the shuttle cock is opened in the bony canal (Figure 3A & 313).

SICURE as claimed in 3, where the plunger has mate threads to lock into the female threads of the shuttle cock and the outer surface of the shuttle cock fins have ridges (threads) to anchor in the bone.

SICURE as claimed in any precedings claim that the inner solid rod holds the shuttle cock at its threaded end and the cannulated rod pushes the plunger with the diaphragm into the shuttle cock with a help of a gun.

6. SICURE as claimed in any precedings has a diaphragm on the plunger base which has radial slits which overlaps on its edges to accommodate various diameters of the bony canal to accommodate and block it under pressure.

7. SICURE as claimed in any proceedings can be made from biocompatible material like plastics (low or high density polyethylene), metal, or bioabsorbable or bioresorbable materials (polyglycolic acid or polylactic acid) or combination of these materials.