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Surgical stabilization of cranial cruciate ligament rupture has been extensively reported on in orthopedic literature. DeAngelis and Lau (1) were the first to describe an extracapsular (EC) suture technique 4 decades ago and several variations have been described since. Extracapsular techniques involve the placement of a suture or sutures outside the joint capsule that spans the stifle joint to mimic the function of the cranial cruciate ligament in restraining cranial tibial thrust and internal rotation of the stifle. The position of the suture attachment points, the method of attachment, and the type of suture have been the major variants from one modification of the technique to another, but all variations share some common factors. The first of these is that EC repair techniques have a very good success rate that is comparable to other techniques and estimated at 85% or better (2). These techniques also are associated with almost invariable eventual failure of the EC suture which does not usually equate to clinical failure for the patient. Extracapsular techniques are also associated with other common problems including significant progression of osteoarthritis (3).
The latest variation of the EC repair is called the “Tightrope” technique (Arthrex Vet Systems, Naples, Florida, USA). Developed and patented by Dr. Jimi Cook of the University of Missouri, the technique is designed to address several of the deficiencies inherent in the EC approach, especially as it pertains to treatment of cranial cruciate ligament rupture in large breed dogs. When Drs. DeAngelis and Lau developed the first EC technique, the typical cruciate disease patient was an older, small breed dog (4). Many of the failures of these techniques in recent years have been attributable to the extreme forces placed on the repair by young, active, large-breed dogs which currently make up the majority of clinical cases. Tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA), and other geometry-modifying surgical procedures have been developed to meet the demands of a large-breed patient. These procedures have come with greater cost for the owner, more equipment and training requirements for the surgeon, and generally higher complication rates (5–8). Dr. Cook’s avowed goals for the Tightrope procedure are to develop a technique that is minimally invasive, cost-effective, less technically demanding, and stands up to the demands placed on the repair by all types of patients (9). Three characteristics of the technique set it apart and facilitate achievement of the stated goals.
What is the verdict on the Tightrope procedure? It is fair to say that it is still early days where this question is concerned but some encouraging data have emerged. Dr. Cook has presented data suggesting that the procedure may produce results similar to TPLO with a lower complication rate (9,13). The reports need to be viewed with some caution, however, since although they include results from over 1000 cases, they primarily present subjective measures based on owner questionnaires and evaluation of radiographic osteoarthritis. At this point it would be fair to conclude that Tightrope does not represent anything “revolutionary” in the treatment of cranial cruciate ligament rupture since it is a variation on a long-established technique. However, it may well prove to be an example of “building a better mousetrap” and could provide an important treatment alternative to TPLO or TTA, especially in active, large-breed dogs.
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