All-Inside Meniscal Repair
Brian Reiter
Steven B. Cohen
INTRODUCTION
Over the past decade, we have developed a more complete understanding of meniscus pathophysiology, mechanical properties and functions, repair site healing, and performance and limitations of the evolving all-inside repair techniques (1,10). Arthroscopic meniscal repair technology continues to improve as does our knowledge of the meniscus itself. As new advances are made and research is continued, indications for repair will expand. Over the past few decades, research has stressed the importance of retaining as much functional meniscal tissue as possible in order to maintain normal contact stresses at the articular surface. The importance of a clear and thorough understanding of the indications as well as the technology and techniques involved in treating this subset of meniscus tears is paramount in decreasing the number of patients who develop significant life-long morbidity as a result of these injuries.
Historically, the inside-out method of suture fixation had been the treatment of choice for a repairable meniscus and remains the gold standard by which all new devices are measured. All inside approaches have become more common over the past decade because of their decreased associated risks, shorter operating time, decreased morbidity associated with a larger incision, less need for trained assistants, and often ability to repair tears in anatomic locations difficult to reach by open techniques. However, most studies continue to find that all-inside devices perform inferiorly to traditional suture repair techniques in biomechanical studies (2,4,11,15). The clinical relevance of this is still undetermined and all-inside devices are increasing in popularity.
INDICATIONS
Indications for meniscal repair are similar regardless of technique. It is generally agreed upon that factors that are favorable for fixation include acute symptomatic tears, longitudinal orientation, peripheral red-red/red-white tears, tears >7 to 10 mm in length, unstable tears with >3 mm excursion, concomitant reconstructive surgery (anterior cruciate ligament (ACL) or articular cartilage), and patients who prefer this procedure over continued nonoperative treatment. Contraindications may include degenerative tears in older patients, chronic tears >3 months, avascular tears in the white-white zone, complex tear patterns, stable/incomplete tears, patients unable to comply with weight-bearing and motion restrictions, and associated infectious/rheumatologic/collagen vascular diseases.
Many find that tears of the anterior one third are still most easily and predictably repaired with outside-in or open techniques with all-inside techniques being reserved for more posterior tears and those involving the body. Posterior one third tears are more difficult to reach using an inside-out technique, which also places the neurovascular structures, such as the saphenous nerve medially or peroneal nerve laterally, at risk. Also, all-inside devices are designed to be inserted perpendicular to the tear. An anterior anatomic location may make this difficult even by switching or using an additional accessory portal. In the case of bucket-handle tears displaced into the notch, some feel that traditional inside-out sutures placed in variable configurations are more preferable. It had been thought that the inside-out technique allows more reliable tensioning of the suture into a meniscus that has been torn. However, with the advent of suture-based fixators, bucket-handle tears may also be secured more reliably using the all-inside devices.
Some surgeons will allow immediate weight bearing in extension following repair with the thought that hoop stresses placed through the meniscus will not harm and in fact may aid in healing. However, many still maintain the traditional protocol of nonweight or partial weight bearing for up to 6 weeks. This conversation with the patient and their ability to comply with these restrictions is necessary prior to every planned arthroscopy with
the potential for repair. The patient must understand that a tear may be found irreparable at the time of surgery and a final decision may be made at that time.
the potential for repair. The patient must understand that a tear may be found irreparable at the time of surgery and a final decision may be made at that time.
DEVICES
First Generation
Since their introduction over a decade ago, fixator devices have undergone an evolution. The initial most commonly used “first-generation” fixators were
Meniscus Arrow (Bionx, Blue Bell, Pennsylvania, 1996)
T-Fix (Acufex/Smith and Nephew, Andover, Massachusetts)
SD Sorb Staple (Surgical Dynamics, Norwalk, Connecticut, 1997)
Biostinger (Linvatec, Largo, Florida, 1998)
Fastener (Mitek, Westwood, Massachusetts, 1998)
Clearfix Screw (Mitek, Westwood, Massachusetts, 1998)
Dart (Arthrex, Naples, Florida, 1999)
These devices were similar in that they were somewhat rigid devices made up of varying amounts of polymerized levorotatory polylactic acid (PLLA) and polyglactic acid. Two devices, the Arrow and the Dart, changed the composition of their implant around 2000 to include polylactic acid dextrorotatory “D” stereoisomer configuration. This configuration is more amorphous and possesses different degradation properties (7).
Meniscus Arrow
The first popular fixation device, the “Arrow,” was “T” shaped with a 4-mm-long cross bar and a shaft of varying lengths to be used at the surgeons discretion. The shafts had reverse barbs projecting 90 degrees from each other. Each could be inserted manually or via a device known as the “crossbow” that held multiple arrows and facilitated multiple implant insertions. The disadvantages included chondral damage from retained PLLA fragments as well as suboptimal fixation strength. A recent systematic review showed that the meniscus arrow was by far the most studied device and had a failure rate between 5% and 43.5% with higher rates occurring, as expected, in studies with longer follow-up (13).
T-Fix
Originally, this device was designed in 1984 but was made usable by the advent of the arthroscopic knot pusher by Joe Sklar, M.D. The device consisted of a 17-guage needle preloaded with blue nonabsorbable suture tied to a polyacetal absorbable bar or “T.” A small obturator slid down the needle and pushed the “T” out and clear of the needle tip. A second T-Fix was then inserted 3 to 4 mm from the first, and arthroscopic knots were tied external to the knee and were tensioned using the knot pusher. Much research has been done on the T-Fix, mostly case series and retrospective reviews with failure rates from 1.8% to 43% (13). Again, the studies with longer follow-up tended to reveal higher failure rates.
SD Sorb Staple
This device consisted of two barbed 7-mm fixation posts linked by a 4-mm braided nonabsorbable suture providing two points of fixation. It could be inserted using a manual device or a multifire gun and reportedly resorbed in 15 months. Newer modifications of this device include a lower profile insertion system and longer fixation posts.
Biostinger
Linvatec’s Biostinger was the first cannulated device with a lower profile head allowing insertion over a needle trocar. The violet-colored fixator was easily visualized in the joint and the newly developed “Hornet” insertion device allowed for easy one-handed placement. The implant contained four rows of barbs that decreased pullout strength and came in three sizes each with its own disposable insertion device. Two studies by Barber et al. showed failure rates of 4.9% to 9.0% in 88 patients over a 2 to 3 year follow-up (3,5).
Fastener
Mitek’s “Fastener” was part of their Meniscal Repair System introduced in 1998. The “T”- or “J”-shaped fixator device came in two sizes (6 and 8 mm) with two suture materials, a nonabsorbable Prolene (Ethicon: Cincinnati, Ohio) and absorbable PDS (Ethicon). The insertion device also came in three angled tips. The reported advantage of the “Fastener” was that it was one of the few devices that could be used for a peripheral meniscus tear and that the crosslimb of the device could be placed beyond the capsule. In a study of 37 patients at 1 year follow-up, there were 5 retears (12). The results were similar to other techniques at that time.
Clearfix Screw
A 2 mm-diameter by 10-mm-long headless screw with a 0.3-mm variable pitch was designed to allow for countersinking and compression across the tear site. Insertion was similar to other techniques via a cannulated needle-guided system. Multiple studies have reported a 10% to 25% failure rate (13).
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