Bone and suture anchors

Contents

Overview

The complete or partial detachment of ligaments, tendons and/or other soft tissues from their associated bones within the body are relatively commonplace injuries, particularly among athletes. Such injuries are generally the result of excessive stresses being placed on these tissues. By way of example, tissue detachment may occur as the result of an accident such as a fall, over-exertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities.

In the case of a partial detachment, the injury will frequently heal itself, if given sufficient time and if care is taken not to expose the injury to further undue stress. In the case of complete detachment, however, surgery may be needed to re-attach the soft tissue to its associated bone or bones.

Numerous devices are currently available to re-attach soft tissue to bone. Examples of such currently-available devices include screws, staples, suture anchors and tacks. source

History and Development

Suture

History

The history of sutures begins more than 2,000 years ago with the first records of eyed needles. The Indian plastic surgeon, Susruta (AD c380-c450), described suture material made from flax, hemp, and hair. At that time, the jaws of the black ant were used as surgical clips in bowel surgery. In 30 AD, the Roman Celsus again described the use of sutures and clips, and Galen further described the use of silk and catgut in 150 AD. Before the end of the first millennium, Avicenna described monofilament with his use of pig bristles in infected wounds. Surgical and suture technique evolved in the late 1800s with the development of sterilization procedures. Finally, modern methods created uniformly sized sutures.

Catgut and silk are natural materials that were the mainstay of suturing products, and they remain in use today. The first synthetics were developed in the 1950s, and further advancements have led to the creation of various forms. The different types of sutures offer different qualities in terms of handling, knot security, and strength for different purposes. No single suture offers all of the ideal characteristics that one would wish for. Often the trade-off is in tissue handling versus longevity versus healing properties.

Development

Arthroscopic techniques for stabilization of the shoulder have continued to evolve over the past decade.

Bone, suture, and tissue anchors

Suture design

Bone anchors or suture anchors are devices which attach soft tissue to bone. This may be achieved by tieing one end of a suture to soft tissue and the other end to a device which "anchors" the suture to the bone. source

Suture Anchors are very useful fixation devices for fixing tendons and ligaments to bone. They are made up of:

  1. The Anchor - which is inserted into the bone. This may be a screw mechanism or an interference fit (like a rawlbolt used in DIY). They may be made of metal or biodegradable material (which dissolves inthe body over time).
  2. The Eyelet - is a hole or a loop in the anchor to through which the suture passes. This links the anchor to the suture.
  3. The Suture - is attached to the anchor by through the eyelet of the anchor. It also may be a non-absorbable material or a biodegradable material

Suture anchors are small devices placed in bone that have attached sutures or other materials that can be used for repair of soft tissues structures. They are most commonly used in the shoulder and knee regions for reattaching ligaments and tendons. There are several different designs including screws and metal posts with attached barbs. source

Materials of sutures

Choice of suture material depends on:source

Suture materials

Bioabsorable material

Others

Choosing the right suture material

Types

Mechanism

The anchor is inserted to the bone and the suture attaches to the tendon - thus fixing the tendon to the bone via the suture-anchor device {figure below)

Suture achor mechanism.

Ideal suture characteristics

The ideal suture has the following characteristics:

Unfortunately, at the present time, no single material can provide all of these characteristics. In different situations and with differences in tissue composition throughout the body, the requirements for adequate wound closure require different suture characteristics.source

Essential suture characteristics

All sutures should be manufactured to assure several fundamental characteristics, as follows:

Other suture characteristics

The following terms describe various characteristics related to suture material:

Possible failure mechanisms

Suturing techniques

Simple suture or everting interrupted suture

Insert the needle at a 90° angle to the skin within 1-2 mm of the wound edge and in the superficial layer. The needle should exit through the opposite side equidistant to the wound edge and directly opposite the initial insertion. Oppose equal amounts of tissue on each side. A surgeon's knot helps place the nonabsorbable suture. Strive to evert the edges and avoid tension on the skin, while approximating the wound edges. Place all knots on the same side.

Simple running suture

This suture method entails similar technique to the simple suture without a knotted completion after each throw. Precision penetration and tissue opposition is required. The speed of this technique is its hallmark; however, it is associated with excess tension and strangulation at the suture line if too tight, which leads to compromised blood flow to the skin edges. Another variant is the simple locked running suture, which has the same advantages and similar risks. The locked variant allows for greater accuracy in skin alignment. Both styles are easy to remove. Additionally, the running sutures are more watertight.

Mattress suture

Vertical mattress sutures can aid in everting the skin edges. Employ this technique also for attachments to a fascial layer. The needle penetrates at 90° to the skin surface near the wound edge and can be placed in deeper layers, either through the dermal or subdermal layers. Exit the needle through the opposite wound edge at the same level, and then turn it to repenetrate that same edge but at a greater distance from the wound edge. The final exit is through the opposing skin edge, again at a greater distance from the wound edge than the original needle entrance site. Place the knot at the surface. A knot placed under tension risks a stitch mark.

The horizontal mattress can be used to oppose skin of different thickness. With this stitch, the entrance and exit sites for the needle are at the same distance from the wound edge. Half-buried mattress sutures are useful at corners. On one side, an intradermal component exists, in which the surface is not penetrated. Place the knot at the skin surface on the opposing edge of the wound.

Subcuticular suture

Sutures can be placed intradermally in either a simple or running fashion. Place the needle horizontally in the dermis, 1-2 mm from the wound edge. Do not pass the needle through the skin surface. The knot is buried in the simple suture, and the technique allows for minimization of tension on the wound edge. In a continuous subcuticular stitch, the suture ends can be taped to the skin surface without knotting.

Suture anchoring methods

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Keyhole tenodesis

Pull-out stitch

Bone tunnels with either suture fixation, or interference screw fixation

Other information on suture

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Suture types.jpeg
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Conditions treated by bone, suture, and tissue anchors

Treatment methods and procedures

Soft tissue re-attachment procedures utilizes following ways:

Arthroscopic Rotator Cuff Repair

Screws The detached soft tissue is typically moved back into its original position over the bone. Then the screw is screwed through the soft tissue and into the bone, with the shank and head of the screw holding the soft tissue to the bone.

Staples The detached soft tissue is typically moved back into its original position over the bone. Then the staple is driven through the soft tissue and into the bone, with the legs and bridge of the staple holding the soft tissue to the bone.

Suture anchors

Tacks The detached soft tissue is typically moved back into its original position over the bone, and then a tack-receiving hole is generally drilled through the soft tissue and into the bone. Then the tack is driven through the soft tissue and into the bone, so that the shaft and head of the tack will hold the soft tissue to the bone.

Advantages and disadvantages of various treatment procedures

Disadvantages:

Other facts

  1. Tissue adhesives: In recent years, topical cyanoacrylate adhesives ("liquid stitches") have been used in combination with, or as an alternative to, sutures in wound closure. The adhesive remains liquid until exposed to water or water-containing substances/tissue, after which it cures (polymerizes) and forms a flexible film that bonds to the underlying surface. The tissue adhesive has been shown to act as a barrier to microbial penetration as long as the adhesive film remains intact. Limitations of tissue adhesives include contraindications to use near the eyes and a mild learning curve on correct usage.
  2. Antimicrobial sutures: Another recent development in wound closure involves the use of sutures coated with antimicrobial substances to reduce the chances of wound infection. While long-term studies are not yet available, preliminary results indicate that these sutures are effective at keeping bacteria out of wounds.
  3. Polymethylmethacrylate can be used to augment anchor fixation, reducing the risk of anchor pull-out failure, regardless whether the suture anchor hole is stripped or unstripped. source

Market data for conditions and various treatment procedures

Number of patients by geography

Number of patients by procedure

Projected size of patient populations

Overview information on the patents in these areas

Queries used on patent database

Patents by geography

Geographical distribution of patents

Patent timeline

The IP activity initiated during early 70s, and a continuous increase in the IP activity evident thereafter, with maximum activity during the year 2004.

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Patents by assignees

Assignees with more than 15 records are considered as major players.

Major players


IP activity during 2000-2006 of major assignee

Visual patent landscape snapshot

Components of anchors and features - An interactive model

Components of anchore source

Various anchor components

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Patent landscape by anchor component

Suture componenets:-

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List of patent numbers

Anchor component

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Competitors in these areas

Individual competitors' patents assessed by anchor components

Anchors can be catagorized as:


Anchor structure Chemical fasteners Mechanical fasteners Component material Application Pat/Publ. No. Assignee/Inventor
Double helix structure NA Barb Biodegradable, biocompatible metals, bioactive substances Soft tissue or tendon to bone US20060195103 A1 Culbert, Brad, S. | von Hoffmann, Gerard | Cachia, Victor, V.
Hook-like terminal NA Barb, clip, staple, post, eyelet, and hook Autologous tissue, xenograph material, and synthetic. prosthetic heart valve US20060052867 Medtronic
Continuous wire Surgical adhesive Barbs, sutures, staples, and combinations, magnetic fastener Biologically compatible resilient material Gastrointestinal tract US20050125020 GI Dynamics
Sleeve-like structure, tubular stent-like structure, helical coil, polymeric tube, conical structure and metallic mesh. Weld, glue, or adhesive Hooks, lips, surface roughness Natural and biologic tissue, collagenous material, shape memory, synthetic, or bioresorbable Heart (preventing formation of thrombi in the left atrial appendage) US20050070952 NMT Medical
Double helix structure NA Barbs, lips, eye or hook NA Soft tissue or tendon to bone US20050033289 Culbert, Brad, S.
Staple (fluke-bearing anchor ) Surgical glue Hook, flukes Viscoelastic material Soft tissue or tendon to bone US20030163160 Bell, Michael, S G | Lee, James | Lee, Leonard, G
Conical, spherical NA Ramped extensions or barbs Medical-grade construction materials Bones or bone fragments US20030097132 Culbert, Brad S. | Hoffmann, Gerard von | Cachia, Victor V.
Stacked rods is circular or elliptical NA Slotted screws, staples, bolts, hooks or clamps Biocompatible material Spinal fixation US20030083749 Haines, Timothy
Single hook, multiple hooks, stent, helix, loop and disk Glue Barbs, hook Biocompatible material Heart treatment US20030078465 Domingo, Nicanor | Whayne, James G
Tubular NA Tines, prongs, or barbs Bioabsorbable materials Knee joint US20030040795 Jacobs, Daniel


Competitive products

Competitive products