Suture Anchor Case Examples
Reconstruction of Collateral Ligaments
Collateral ligament injuries are common in small animal patients. Traumatic injuries can result in tears of the ligaments, avulsions of ligament origins/insertions, or loss of ligaments from shearing injuries. Torn collateral ligaments are often sutured for primary reconstruction; however, due to the slow healing and remodeling of collateral ligament tears, it is common to utilize sutures and anchors to support a primary repair. Placing a suture anchor at origin and insertion of the collateral ligament and spanning the two anchors with a relatively strong strand of suture material is a typical method of supporting primary ligament repair. Collateral ligament avulsions are repaired by placing a single suture anchor at the avulsion site and then reattaching the ligament to the bone via the anchor. Some surgeons will elect to include a second anchor and suture loop to create a prosthetic ligament to protect the avulsion site during the early healing phase (similar to protection of a primary repair). Injuries, such as shearing injuries, resulting in actual loss of the collateral ligament, carry a more guarded prognosis. However, suture anchors can be utilized to facilitate placement of prosthetic ligaments that serve to maintain joint stability during the formation of functional fibrous tissue, which helps maintain joint stability over time.
Stabilization of Shoulder Subluxation and Luxation
Primary, traumatic luxation of the shoulder joint is not common in small animal practice, but can occur. Congenital and developmental shoulder subluxation and luxation occur in small-breed dogs, and chronic shoulder instability occurs in large-breed, athletic dogs. Surgical stabilization for these cases can include joint capsule imbrication and prosthetic suture placement to provide reduction and strength for supporting tissue healing and strengthening of the rotator cuff. Suture anchors can be utilized for attaching these periarticular sutures. Anchors can also be used for reattaching avulsed joint capsules or glenumeral ligaments to bone.
Joint Capsule Reattachment
With traumatic joint luxations, the joint capsule is always torn to some degree, and re-establishing its integrity and function is a primary goal of treatment. In some cases, the damage to the joint capsule is in the form of avulsion from the bone. In these cases, reattachment of the joint capsule to the bone increases the mechanical stability of the repair and may lead to more rapid return to function. Use of anchors in this fashion greatly facilitates re-attachment of the avulsed joint capsule by allowing the exact number of anchor points to be utilized. In comparison to more mechanically demanding scenarios, relatively small suture materials can be utilized for joint capsule reattachment. The photo to the right shows a reduced elbow luxation with avulsed joint capsule. Three suture anchors have been pre-placed into the ulna and will be used to re-position the joint capsule.
Capsulorrhaphy for Hip Luxation
A number of methods for maintenance of surgical reduction of hip luxations are currently popular and include: the toggle pin method, ilio-femoral sutures to limit external rotation of the hip, and caudo-distal transposition of the greater trochanter. Each of these methods depends on the joint capsule and associated muscles for acute and long-term maintenance of joint stability. If the joint capsule is severely traumatized and not conducive to primary repair, some surgeons will elect to perform a capsulorrhaphy or dorsal augmentation of the joint capsule. This is accomplished by placing sutures from the dorsal acetabular rim to the proximal femur. These sutures are utilized to augment or mimic the strength of the dorsal aspect of the joint capsule with the hope that this added strength will assist in maintaining joint integrity while healing of the compromised joint capsule occurs. Ilio-femoral sutures can be a part of this dorsal augmentation, or can be utilized alone. The purpose of the ilio-femoral suture is to limit external rotation of the hip and thus decrease likelihood of repeat luxation. With any of the just mentioned surgical methods for stabilization of hip luxations, it is important to remember that the use of sutures and anchors must be considered temporary solutions until the joint capsule and periarticular soft tissue can heal. As such, patients with poor hip conformation are not good candidates for these methods of repair and should be considered for salvage procedures, such as FHNE or THR.
Tendon and Ligament Reattachment
Other tendon and ligament injuries, such as the origin of the gastrocnemius, long digital extensor tendon of origin, and gluteal tendons of insertion may provide ideal indications for the use of suture anchors. In these cases, anchors are used in a fashion similar to treatment of collateral ligament injuries. Treatment of calcanean, patellar, and triceps tendon injuries may be successfully treated using suture anchors in very select cases. However, their use is not generally recommended for these structures due to the very dense bone at the attachment sites, the anatomical considerations unique to these sites, and the availability of other techniques which may be more appropriate for these problems.
Anchor-Orthopedic Wire-Polymethylmathacrylate-Acetabular Fracture Repair
Articular fractures should be anatomically reduced and rigidly fixed. With acetabular fracture repair, it is often difficult to contour available bone plates to maintain accurate, anatomic alignment as screws are tightened into the plate. In other words, if the plate is nearly contoured, initial screw application will appear accurate; however, as additional screws are placed and tightened, any error in plate contour will result in translation of the bone and loss of reduction. To overcome the difficulty of plate contouring, special acetabular plates have been developed. In addition, reconstruction plates have been utilized in larger canine patients. Recent reports (Lewis, et al: Veterinary Surgery. 1997 May-Jun; (3):223-34) have outlined an alternate procedure for repair of acetabular fractures in small animal patients. Specifically, bone screws or similar devices are placed along the dorsal acetabular rim and are connected with orthopedic wire. The fracture is held in reduction while PMMA is applied over the implant/wire composite frame. The PMMA conforms to the surface of the bone and strength is achieved because the composite structure is held in place by the threaded implants. Anchors may be beneficial when used for this technique, as they provide excellent bone purchase while allowing for easy retention of the orthopedic wire in the eyelet. It is important to note that to date, this method has been used in relatively small patients.
Stabilization of Cranial Cruciate Deficient Stifles
A few recommendations are provided regarding use of suture anchors for stabilization of cranial cruciate deficiency. Many questions are being asked about the appropriateness of this use, and several general guidelines and concerns can be outlined. Surgeons who assisted in development and testing of these suture anchors were referral orthopedic surgeons utilizing tibial plateau leveling osteotomy (TPLO) as their treatment of choice for cranial cruciate tears. However, in selected patients, suture anchors have been utilized instead of the fabella for extracapsular reconstructions. Use of suture anchors enhances more isometric placement of sutures than using the fabella; however, in large active patients, it must be stressed that combinations of techniques should be utilized. For example, a fabellar suture in addition to an anchor suture could be utilized along with capsular imbrication and/or fascia latae transfer. Remembering that all prosthetic suture/ligament applications will likely fail (this includes current fabellar-tibial suture loops), it must be hoped that peri-articular fibrosis will maintain joint stability after such failure. Perhaps the use of multiple techniques creates a situation in which multiple failures must occur over time before there is only fibrosis and fascial transfer to maintain long-term stability. More and more customers are incorporating additional use of suture anchors as a portion of their CCL repair in challenging patients. Do not purchase suture anchors as the sole method of extracapsular repair of cruciate disease; however, selected adjunct use of these anchors may simplify and enhance cruciate repairs.
Many customers want specific recommendations regarding suture material type and size. Due to the widespread variations in patient size, underlying pathology, and presence or absence of infection, specific recommendations cannot be made. However, feedback to date indicates that about 50% of cases have utilized monofilament sutures, while the other 50% have utilized braided materials. In human surgery, there are dozens of suture anchors available, and many are pre-loaded with braided suture material. Large diameter, monofilament nylon fishing line has been popularized in veterinary medicine and may be appropriate in demanding situations such as repair of CCL deficient stifles in large, active patients. However, this stiff line is not conducive to acute bends at anchors and is difficult to handle. Current 4.7mm anchors will support use of most brands of 80 pound monofilament nylon leader and #2 -#4 braided materials. Number 5 braided materials may be difficult to utilize if the material of choice tends to fray significantly when cut. Popular monofilament materials also include Prolene and Ethilon in sizes “0” and “2.” Consider the difference between a closed tear of carpal collateral ligament that undergoes primary repair and prosthetic ligament support compared to a deep shearing injury loss of the same ligament in a similar patient. The shearing injury is less stable, but being open and contaminated may lead one to utilize monofilament material for repair. Size of material selected is dependent on patient size. Braided material tends to have better handling and tying characteristics, is more conducive to sudden direction change, and is generally stronger than monofilament material. However, in veterinary medicine, both have been associated with fistulous tracts. Use of higher quality braided material and improved aseptic techniques seem to be leading to increased use of braided suture material in veterinary surgery. Newer monofilament, non-absorbable sutures show promise as well.