WO2016138913A1

WO2016138913A1 - A method for connecting custom made guides to conventional instruments of joint replacement

Info

Publication number: WO2016138913A1
Application number: PCT/EG2015/000013
Authority: WO
Inventors: Mahmoud Alm EL Din HAFEZ; Ahmed Abdel Moghny SALEM
Original assignee: Hafez Mahmoud Alm El Din
Priority date: 2015-03-05
Filing date: 2015-03-05
Publication date: 2016-09-09
Also published as: TN2017000370A1

Abstract

Custom made guides or patient specific instruments (PSI) for knee replacement is currently used to replace or guide conventional instruments by pin locating techniques. All currently available PSI techniques are company specific and can only be used for certain implants produced by the specific company. This new method is meant to integrate important parts of conventional instruments to the parts or templates of PSI. The invention includes 10 different methods and techniques to fit currently available conventional instruments regardless of the implant manufacturers. The integration is used to transfer the preoperative planning built in PSI to different pieces of conventional instruments allowing the machining (cutting and fashioning) of bone according to the preoperative plan. Using the specific software, these methods are modified to fit any new cutting blocks or conventional instruments that will be introduced in future. The same principles are used for other joint replacement.

Description

A Method for Connecting Custom Made Guides to Conventional Instruments of Joint Replacement

Technical Field

Joint replacement is the standard treatment for advanced osteoarthritis. Each prosthesis for joint replacement has a set of conventional instruments with different sizes of cutting blocks and jigs.

Recently, a new technique was introduced, which is called custom made guides or patient specific instruments (PSI) for knee replacement. This technique is used to transfer the preoperative planning to the intraoperative performance and reduce the number of conventional instruments. One of the most common joint replacement is total knee arthroplasty (TKA), which has a set of instruments reach more than one 100 pieces.

Background of the Invention

The continuous development is an essential requirement to overcome increasing demand for TKA. This development is now focused on surgical techniques and instruments to achieve a better function and longer survival of artificial knee joints. Surgeons face a challenge during the surgery to handle and manipulate a large number of instruments that may exceed 100 pieces.

Navigation and robotics systems are used for TKA but they are adding more difficulties regarding complexity and time consumption. Also, they still rely on some pieces of the conventional instruments. These reusable instruments are designed for certain prostheses (company specific) and cannot be used for other prostheses (implants). The PSI technique is now produced by some implant companies manufacturing knee prosthesis but they are designed and only used for these particular implants.

This invention is meant to integrate PSI with conventional instruments. Different methods are used to couple and connect the custom made guides to important pieces of any conventional instruments produced by different implant manufacturers. The same principles can be used for other joint replacement such as hip, shoulder, elbow, ankle and others.

Disclosure of Invention:

The invention is a method for integrating custom made guides (also called patient specific instruments or templates) to conventional instruments for joint replacement. The method is used for any cutting blocks and instruments regardless of manufacturing companies.

The invention introduce 10 coupling methods for both femoral and tibial parts to several cutting block shapes and sizes and it is suitable to be used for any commercially and currently available conventional instruments.

These methods give surgeons a variety of techniques to be used for any on shelf implants and any patient specific knee instruments.

The method based on coupling and integrating conventional instruments into custom made guides manufactured specifically for each patient. The methods based on different designs and shapes of custom made guides (PSI) to fit available cutting blocks. Using the specific software, these methods are modified to fit any new cutting blocks or conventional instruments that will be introduced in future.

Insertion block coupling technique (figures 1-A and 1-B) present a method of coupling based on deep indents at the back side surface of cutting block. Housing technique (figures 2-A and 2-B) depends on interlocking the cutting block from three sides and mounting it smoothly on custom made guide. To insure accurate coupling, extra pins are used to support fixation of cutting block to custom made guide.

Third technique (figures 3-A and 3-B) use a method of pins fixation for cutting blocks which has a back side holes. In addition it makes a good positioning for cutting block and material saving for custom made guide.

Fourth technique (figures 4-A and 4-B) use a full housing arms surrounding the majority of cutting block sides provided by two built in pins (figure 4-A, labels (7 and 8))

Fifth technique (figures 5-A and 5-B) use tapered housing technique for these blocks which has an inclined and tapered shape like a wedge.

The technique in (figures 6-A and 6-B) is more universal for several designs of cutting blocks providing a slot guide and screw fixation method (figure 6, labels (10 and 11)). These made coupling and fitting more accurate and give surgeons the chance to use various types of cutting block regardless of its shapes and designs.

For tibial part, a method is used for accurate positioning of tibial patient specific template in relation to coronal alignment and rotation. This involves a connection of extra medullary rod to tibial part. This technique depends on geometry of tibial patient specific templates. The first technique use a multi holes plate to be inserted into the slot (slit) of the tibial template of PSI. It provides a multi holes with various diameters to fit different sizes of alignment or intramedullary rods produced by different implant manufacturers (figure 7-a). The second one uses the stem hole in the tibial template of PSI to fix and connect the extra medullary rod using a cylinder (extra pin) that fits into the stem hole. The third one depends on making side to fit any size of conventional alignment rods, it is a groove guided fitting (figure 7-c),

Last technique for coupling is used for cruciate sacrificing or posterior stabilized total knee replacement. It is a method to connect the femoral template of PSI to the conventional box cutting block (figure 8). In this technique, the box cutting block is inserted into a groove situated on both anterior and distal sides of the femoral template.

Brief Description of Drawings

1) Femoral template body

2) Cutting block

3) Insertion guide

4) Femur bone

5) Hole guide

6) Fixation pins ) Built-in fixation pins) Housing arms

) Tapered housing

0) Fixation screws

1) Guiding slot

2) Tibial template body

3) Holes of a guiding plate4) Extra medullary rod

5) Guiding plate

6) Stem hole - guiding cylinder7) Groove-guided rod

8) Box cutting block

9) Groove guided box cutting0) Holding arms

Claims

1. Methods to ingrate the preoperative plan built in the femoral and tibial templates of custom made guides or patient specific instruments (PSI) with conventional instruments during joint replacement surgery.

2. The custom made cutting guides has built-in information about sizing, alignment and bone cutting, there are transferred through the coupling techniques to the conventional instruments.

3. In the femoral template, the four in one cutting block of conventional instrument is coupled with the patient specific template using transition fit. The transition fit consists of two rectangular shafts interconnected with two deep indents at the bottom side surface of cutting block.

4. In the femoral template, the four in one cutting block of conventional instrument is coupled with the patient specific template by interlocking fit from three sides. The template is then fixed into position with two pins positioned at opposite sides of the cutting block.

5. In the femoral template, the four in one cutting block of conventional instrument is coupled with the patient specific template and fixed with pins located at the bottom surface of the cutting block

6. In the femoral template, the four in one cutting block of conventional instrument is coupling with the patient specific template using a housing technique. The coupling technique consists of two surrounding arms which have an aquiline end. The arms have built-in pins plugged into two holes located at opposing sides of the cutting block.

7. In the femoral template, the four in one cutting block of conventional instrument is coupling with the patient specific template by interlocking with a trapezoidal-shaped fitting. The template is then fixed into position with two pins positioned at opposite sides of the cutting block.

8. In the femoral template, the four in one cutting block of conventional instrument is coupling with the patient specific template using four pins fixated to the sides of the cutting block through a guidance slot.

9. In the tibial template, the extra medullary rod is coupling with the patient specific part using multi holes plate. The plate is inserted to the slot of the tibial template and the multi holes accommodate and fit different rods of conventional instruments with different diameters.

10. In the tibial template, extra medullary rod is coupling with the patient specific template using stem hole guidance. The cylinder of inverted J- shaped rod is fitted into the stem hole.

11. In the tibial template, extra medullary rod is integrated with the patient specific part by using a side groove. The transverse part of the L-shaped rod is inserted into the groove.

12. In the femoral template, the box cut block is coupled with patient specific template by through a central groove with two holding arms provided by extra fixation pin in each side.