DESC:FIELD OF THE INVENTION:
This invention relates to the field of medical engineering.

Particularly, this invention relates to generalised surgical navigation or guidance tool for lumbar spine surgeries by using Minimum Invasive Surgery techniques

Specifically, this invention relates to a system and method for development of a generalised path guidance tool to assist in minimum invasive surgery of lumbar spine.

BACKGROUND OF THE INVENTION:
Minimally invasive spine surgery (MISS) was first performed in the 1980s, but has recently seen rapid advances. Figure 1 shows a human spine. Technological advances have enabled spine surgeons to expand patient selection and treat an evolving array of spinal disorders, such as degenerative disc disease, herniated disc, fractures, tumours, infections, instability and deformity. MISS was developed to treat disorders of the spine with less disruption to the muscles as shown in fig. 1. This can result in quicker recovery, decrease operative blood loss, and speed patient return to normal function. In some MISS approaches, also called "keyhole surgeries," surgeons use a tiny endoscope with a camera on the end, which is inserted through a small incision in the skin. The camera provides surgeons with an inside view, enabling surgical access to the affected area of the spine.

Figure 2 illustrates a MISS Procedure which is current state of art.
Through small keyhole tubular retractor placed and rested on vertebra of interest. Through tubular retractor, small wire drill passed and advanced on human vertebra. The path is continuously monitored through C arm X ray machine. Generally, 20~30 X rays are required to check path of drill. If satisfactory, then instrument passed through retractor and hole enlarged and pedicle screw placed in position.

MISS procedures are used to treat spinal disorders such asSpinal deformities such as Scoliosis (Stair Case Effect), Degenerative Disc Disease, Herniated Disc, Vertebral compression fractures, Tumors, Spinal infections, Spinal instability, etc.

Problems associated with such procedures are enlisted below:
• Highly skilled surgery technique
• Takes usually long time e.g. 4-24 hrs
• During each step requires confirmation of position of tool by C arm X-ray usually more than 40 exposures per surgery
• increases risk to Surgeon and Assistants of X ray exposure

Potential benefits of MISS comprise:
• Smaller incisions
• Smaller scars/less scar tissue
• Reduced blood loss
• Less pain
• Less soft tissue damage
• Reduced muscle retraction
• Decreased postoperative narcotics
• Shorter hospital stay
• Possibility of performing on outpatient basis
• Faster recovery
• Quicker return to work and activities

Surgery Risks associated with MISS comprise:
• Dissatisfactory Instrumentation Placement; may require re-operation
• Incision problems
• Death
• Spinal fluid leakage
• Paralysis
• Bleeding, Blood vessel damage, Blood clots, Bruising
• Pain or discomfort
• Allergic reaction, Anesthesia reaction, Headache
• Infection
• Pneumonia
• Stroke

OBJECTS OF THE INVENTION:
An object of the invention is to design and develop a generalised surgical guidance fixture to minimize risk of dissatisfactory location of instrument.

Another object of the invention is to develop guidance fixture to minimize risk of dissatisfactory location of instrument which will assist a surgeon to reduce surgery time, thus saving operating theatre costs as well as protecting staff from X-ray exposures.

SUMMARY OF THE INVENTION:
According to this invention, there is provided a generalised path guidance tool to assist in minimum invasive surgery of lumbar spine, said tool comprises:
- two vacuum cups, spaced apart from each other, configured to secure said tool to body part;
- two retractor tubes, in said spaced apart region, with a hemi-spherical locator, at its operative distal end, said locator configured to engage with a portion of said bone, said tube configured to comprise a plurality of guide tubes to allow a surgical instrument to pass through it;
- knob provided on cross axis in order to set angle between said retractor tubes and said vacuum cups; and
- sliding mechanism, with a linear adjustment know to provide linear adjustments along longitudinal and cross axes and an angular adjustment knob, configured to provide angular adjustment of retractor tube in sagittal plane as well as provides easy access along longitudinal axis.

Typically, said hemi-spherical locator is a metallic hemi-spherical locator.

Typically, said hemi-spherical locator comprises a central drill for guide wire to be located at interface of articular processes of neighbouring lumbar vertebrae where the locator is placed.

Typically, said hemi-spherical locator is a spherical locator.

Typically, said hemi-spherical locator is a fork-shaped locator.

Typically, said tool comprises multiple retractor tubes can mounted on longitudinal axis with predetermined distance and angles between two tubular retractors.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:

Figure 1 shows a human spine;

Figure 2 illustrates a MISS Procedure which is current state of art;

Figure 3 illustrates Lumbar Vertebra;

Figure 4 illustrates resting surface for MISS on Lumbar Vertebrae;

Figure 5 illustrates Pedicle angle – Lumbar Vertebra; and

Figures 6 and 7 show construction of generalised surgical guide for MISS for Lumbar vertebrae.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Approximately, only 10% to 15% of surgeries on spine are for cervical spine or scoliosis in thoracic spine. Major amount of surgeries are done on lumbar spine for vertebral fractures or slip discs in lumbar vertebral region. In this section of spine, pedicle cross-section in more as compared to thoracic or cervical spine. It is proposed to design and develop a generalized surgical guide or drilling template to accommodate group of patients with age, size and different demography.

According to this invention, there is provided to a system and method for development of a generalized surgical path guidance tool. The development of this generalized surgical path guidance tool is imperative in assistance of Minimally Invasive Spine Surgery (MISS) and Transforaminal Lumbar Interior Fusion (TLIF) surgeries along with BioCAD models retrieved from non-invasive imaging techniques and Reverse Engineering approach.

Figure 3 illustrates Lumbar Vertebra.

In human body, there are 5 lumbar vertebrae i.e. L1 to L5 are with spinous, transverse, and articular processes as shown in Figure 3.

As per expert’s opinion, the start point for pedicle screw entry is on transverse process at the intersection of articular processes as shown in Figure 4.

Figure 4 illustrates resting surface for MISS on Lumbar Vertebrae.

Since, the start point is on intersection of articular spinous processes and convex spherical region; it provides more difficulty to start drilling due to its spherical nature.

The objective of the work is to design generalized surgical guides which facilitates easy drilling, reference to guide wires for patients with different age groups, sizes, and angle (?), which can be easily estimated from CT scan image as illustrated in Figure 5.

Figure 5 illustrates Pedicle angle – Lumbar Vertebra.

Figures 6 and 7 show construction of generalised surgical guide for MISS for Lumbar vertebrae.
Part Material Purpose
Vacuum Cups (02 Nos) Rubber (Bio compatible) To fix/hold fixture to human body in prone position

Tubular Retractor (02 Nos) Metallic, ABS or polymer material To guide drill / tool, guide wire, etc. – provides path
Locators (02 Nos) Metallic / High density materials • To provide location
• Shape hemispherical or modified fork type to accommodate / locate or provide guide over pin shaped articular processes.
• Provides guide for drill, to initiate over spherical headed articular process
Bridge (cross shaped) (1 no.) Stainless/chromium steel, etc. • Supports tubular retractor, provides linear and angular adjustments to tubular retractor
Knob for angular adjustment ‘?’ Bio compactible metallic/plastic material • Provides angular adjustment as shown in fig. 6
Knob for angular adjustment of tubular retractor Bio compactible metallic/plastic material • Provides angular adjustment as shown in fig. 7
• Provides linear adjustments as well as movement of cross member carrying tubular retractor to adjust to L1 to L5 vertebra.

Figure 6 illustrates a Generalised Surgical Guide - Axial Plane.

Figure 7 illustrates a Generalised Surgical Guide –Longitudinal View.

Figure 6 and Figure 7 show conceptual design of generalized surgical guide for MISS. Since, posterior area of body i.e. the patient is lying in prone position i.e. lying on chest down and back up. This facilitates surgeon easy access to back and neck region. This generalized fixture is fixed or secured to back in lumbar spine (S) region using two vacuum cups (12, 14), spaced apart from each other, as shown in Figure 7. The construction of bridge is made in the form of cross with facility of linear as well as angular adjustments along longitudinal and cross axes. A knob (16) provided on cross axis is used to set angle (?) between guide tubes (18), same as in pedicle axes of lumbar vertebra in interest, which can be easily estimated from CT scan axial images. A surgical instrument (30) passes through a guide tube (18) Through this guide tubes, tubular retractor of ABS or polymer material is passed with locator. It is proposed to use hemi-spherical metallic locator (20) with central drill for guide wire to be located at interface of articular processes of neighbouring lumbar vertebrae (L). The shape and size of locator is either spherical or fork type to facilitate easy insertion, location as well as easiness in drilling using guide wire. This metallic locater will facilitate easy detection in X-ray exposures due to different material density and fitted to tubular retractor manufactured by using ABS or bio-compatible materials using additive manufacturing techniques. The longitudinal axis or bridge is provided with sliding mechanism (22) with angular adjustment knob, which provides angular adjustment of retractor tube (24) in sagittal plane as well as provides easy access along longitudinal axis of lumbar spine. Also, multiple such retractor tubes can be mounted on longitudinal axis with predetermined distance between two tubular retractors and angles estimated from CT scan axial and sagittal planes. This will provide additional advantage for fixation of metallic rods used in Spinous fusion and stabilization.

This generalized surgical guide for MISS can be used for variety of surgeries for patients suffering from vertebral fractures, scoliosis as well as slip discs and needs spine stabilization, etc.

While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
,CLAIMS:WE CLAIM,

1. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine, said tool comprising:
- two vacuum cups (12, 14), spaced apart from each other, configured to secure said tool to body part;
- two retractor tubes (24), in said spaced apart region, with a hemi-spherical locator, at its operative distal end, said locator configured to engage with a portion of said bone, said tube configured to comprise a plurality of guide tubes (18) to allow a surgical instrument (30) to pass through it;
- knob (16) provided on cross axis in order to set angle between said retractor tubes (24) and said vacuum cups (12, 14); and
- sliding mechanism (22), with a linear adjustment know to provide linear adjustments along longitudinal and cross axes and an angular adjustment knob, configured to provide angular adjustment of retractor tube (24) in sagittal plane as well as provides easy access along longitudinal axis.

2. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine as claimed in claim 1 wherein, said hemi-spherical locator is a metallic hemi-spherical locator.

3. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine as claimed in claim 1 wherein, said hemi-spherical locator comprising a central drill for guide wire to be located at interface of articular processes of neighbouring lumbar vertebrae where the locator is placed.

4. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine as claimed in claim 1 wherein, said hemi-spherical locator is a spherical locator.

5. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine as claimed in claim 1 wherein, said hemi-spherical locator is a fork-shaped locator.

6. A generalised path guidance tool to assist in minimum invasive surgery of lumbar spine as claimed in claim 1 wherein, said tool comprising multiple retractor tubes can mounted on longitudinal axis with predetermined distance and angles between two tubular retractors.

Dated this 13th day of December, 2017

CHIRAG TANNA
of INK IDEÉ
APPLICANT’S PATENT AGENT