By David R. Diduch, MS, MD
Preserving the meniscus is a well-established hallmark of knee surgery to prevent arthrosis. The recent explosion of all-inside meniscal repair devices has made repair more attainable to even the general orthopaedic surgeon. This is a good thing. However, with this plethora of implants comes the difficult task of determining which are better as there is a dearth of literature regarding each device.
All meniscal repair innovations must stand up against the gold standard, which remains inside-out suture repair. Alternating vertical sutures on the superior and inferior surfaces are the strongest constructs mechanically. These have produced healing rates of 60-80% with isolated repairs, and roughly 90% with repairs in conjunction with ACL reconstruction. The problem has been with the morbidity associated with the additional posterior incisions and the inherent risks to the neurovascular structures, not to mention the extra manpower needed to perform this type of repair.
All-inside meniscal repair has undergone an evolution of sorts. The first generation involved cumbersome suture hooks passed in the back of the knee through cannulas with arthroscopic knot tying. While successful, the difficulty in the technique prevented its widespread acceptance. This evolved into the suture anchor concept from the front with the T-Fix (Smith & Nephew, Andover, Mass). This required 2 separate anchors placed across the tear with an arthroscopic knot pusher to tie a knot between them. The problem was the inability to tension the knot adequately to compress the tear. However, we learned that it was safe to cross the tear with a puncturing device and anchor this on the periphery of the meniscus. This led to an explosion of all-inside repair devices.
The third generation of all-inside repair involved various absorbable implants to include arrows, darts, screws, fasteners, and other devices that anchored on the periphery and had some type of head to compress the tear. The meniscal arrow (Bionx, Blue Bell, Pa) was probably the most popular as it was basically the first such device. The common concern with all of these is risk of articular cartilage abrasion due to the rigid implant. If inserted obliquely, the tip may abut the tibial surface and drive the head into the femur. In addition, there were various reports of breakage, migration, extrusion from the joint, and transient pain until resorbed.1,2 Compounding the problem was that they were so easy to put in that surgeons may have begun to change their indications for repair. However, the success rate with these all-inside devices has been reasonably good with short-term follow-up.3,4
These problems with chondral abrasion and implant-related morbidity have led to development of the fourth generation of implants. Two new devices incorporate a combination of suture, slip knot, and a peripheral anchor. The fast T-Fix (Smith & Nephew, Andover, Mass) involves 2 of the T-Fix anchors on a single inserter. The anchors are separately placed at the rim of the meniscus through the tear and then a slip knot is tensioned across the tear. The Rapid-Loc meniscal repair device (Mitek Worldwide, Westwood, Mass) involves a single backstop that is deployed on the rim of the meniscus connected by a segment of suture to a slip knot that cinches down an absorbable top hat on the surface of the meniscus to compress the tear. Given the lack of a rigid implant, both of these constructs share the potential ability to deform and move with the meniscus with weight bearing activities and decrease chondral abrasion. Indeed, chondral abrasion scores were lower for company-sponsored studies for the Rapid-Loc in an animal model compared to arrows and other devices.
However, distinct differences exist between these 2 implants. The fast T-Fix requires a sharp inserter to be extended well beyond the meniscus periphery so that the backstop can be deployed, potentially placing the neurovascular structures at risk. If an additional depth stop is not applied to the device, it actually penetrates 22 mm when buried to the hub. In a cadaver study (submitted for publication), we found that these were correctly inserted only 63% of the time by experienced surgeons. The Rapid-Loc in a similar study (submitted for publication) was correctly inserted 85% of the time. Problems with the remaining devices were minor and of questionable clinical significance. This device has a depth stop limiter of only 13 mm. The backstop is deployed further into the periphery using a blunt, flexible spring, which is much safer to the neurovascular structures. The ability to tension the repair is quite remarkable; in fact, the surgeon can even over tension the device if not careful. I have had occasion to rearthroscope patients with this device and have found in each case the meniscal tissue grows over the surface of the implant and I have seen no evidence of chondral abrasion. Even though we just published a paper with the arrows having good clinical success,3 I switched to the Rapid-Loc device over a year ago given its easy and safe insertion, ability to adjust compression of the tear, and diminished risk of chondral abrasion. Although it is too early to tell for either of these devices, I feel the clinical healing rate thus far is excellent.
These new all-inside meniscal repair techniques offer distinct advantages over existing all-inside methods, including the ability to adjust tension on the repair and a flexible construct for weight-bearing forces. Good comparative and prospective studies are needed in this rapidly growing area of orthopaedics. Until then, the safest recommendation is to use these devices when the ACL is reconstructed and the healing environment is optimal, perhaps reserving inside out repairs for isolated meniscal tears.
Dr. Diduch, Co-Director, Sports Medicine, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports.
1. Anderson K, et al. Arthroscopy. 2000;16(7):749-753.
2. Ross G, et al. Arthroscopy. 2000;16(7):754-756.
3. Gill SS, Diduch DR. Arthroscopy. 2002;18(6):569-577.
4. Jones HP, et al. Arthroscopy. 2002;18(1):64-69.