What’s new in Extracapsular Cruciate Repair? ... A Lot!

Author: R. Randy Basinger DVM, DACVS

Extracapsular suture repair for the treatment of unstable stifles due to cranial cruciate ligament insufficiency has been around for decades and has helped tens of thousands of dogs. Although osteotomy techniques like TPLO and TTA have become the standard of care for large breed and athlete dogs, the extracapsular repair has remained a very useful technique that can be done in your hospital when referral is not an option.

Because of the frequent use of this procedure, modifications have been made over the years to address the weaknesses of the original technique. The development of a tensioning and crimping system with nylon leader line was a quantum improvement over the original hand-tying system. Ongoing improvements have focused on increasing the strength and limiting the stretch of the implanted material; increasing the strength of the anchoring points, and maximizing isometry so the suture is uniformly tight during the entire range of motion. There are a number of new systems currently marketed to veterinarians that have incorporated these new features. However, It is important to remember that all these techniques are still mechanically extracapsular repairs. As such, they mechanically constrain the tibia from subluxating cranially and also nearly eliminate the normal internal rotation of the tibia.

Most of the newer implants, whether a suture, tape, or loop are made of ultra-high molecular weight polyethylene. This material is much stronger than nylon leader line and does not stretch. The anchoring points are bone tunnels with buttons or interference screws, screw-in anchors with holes or flanges, or screw-in anchors with the material already attached. The implants are placed so that they counter the force of subluxation from the isometric points that have been identified on the distal femur and proximal tibia.

The Everost OrthoZIP system was developed by the same bio–engineer that created the original nylon leader line tensioning and crimping system. This system employs a selftightening ultra-high molecular weight polyethylene loop that is placed over titanium anchors with a cancellous thread profile and a “sewing-bobbin” shaped head to retain the loop. After arthrotomy and inspection and treatment of any meniscal injuries, the anchor points are identified, pre-drilled, and the anchors placed. Then the loop is placed over the anchors and tightened by pulling on the two free ends. The loop maintains the tension without any knotting or crimping. Several sizes are available to cover a full range of patient sizes.

Courses are taught around the country to facilitate your incorporation of these improved extracapsular repair techniques into your practice situation.

Example Case: Butch

8 year old MN Boykin Spaniel – retired hunting dog Acute Cr. Cruciate Rupture RR

SO: BAR Marked lameness RR BCS 4.5/9
R cranial drawer and + tibial compression test
Thigh circumference 13” L, 12.25” R Normal range of motion RR
Grade I-II MLP RR, none in L
Rads: R tibial plateau angle = 26 degrees, ++ effusion, minimal O
A: R Cr. cruciate tear with medial patellar laxity 
P: Educate O about Cr. Cruciate dzz, MLP, surgical options, complications and aftercare.

Due to patient’s, size, age, TPA, and concurrent medial patellar laxity I recommend extracapsular suture repair. O agrees and request surgery today.

Anesth today – see separate record. Sx report: A medial limited arthrotomy was made to find the cranial cruciate ligament completely torn. Torn remnants excised. The mensci were inspected and a complex medial meniscal tear was identified and excised. At the F2 and T2 isometric points on the femur and tibia, anchor posts were pre-drilled and placed. The OrthoZIP loop was placed over the anchors and tightened until drawer was eliminated. Range of motion still normal. Routine closure and tegaderm bandage placement. Postoperative radiographs show the stifle reduced and proper implant placement.

About the Author

Randy Basinger, DVM, DACVS, is boardcertified in veterinary surgery. In 1988, he founded VCA Animal Specialty Center of South Carolina. Dr. Basinger has been honored by the ACVS for the best research publication by a resident, and as the 2005 South Carolina Veterinarian of the Year. He has published four book chapters and 15 scientific articles and has completed successful research projects in the university and practice setting. He currently operates VetSurgLLC.

About the Author

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Butch

Limited medial arthrotomy & torn cruciate

Excised meniscal tear

OrthoZIP anchors and loop placement

Post- Op Rad