Below you will find a translation of the following study from France on the ZLig method - translated from English:
Translated from an abstract of the presentations at the ACVS Congress in Las Vegas 2019 and the AFVAC Congress in Lyon 2019.
Update January 2022 of the study on the ZLig method
RECONSTRUCTION OF THE CRANIAL CRUCIAL LIGAMENT IN DOGS USING THE ZLIG METHOD
With the synthetic ligament STIF-VETLIG GLOBAL PROSPECTIVE STUDY FROM 2012 TO 2021 IN 107 CASES LE DOZE P. 1, PARIS P.2, PAGES G.3 1-2 DMV, La Cardelle Veterinary Clinic, 84 Chemin dit de Cannes 06530 LE TIGNET, FRANCE 3 ECVS
INTRODUCTION ZLig method
When operating on cranial cruciate ligament (CCL) defects in dogs, the most common techniques are compensatory and alter the biomechanics of the knee joint.
Dynamic stabilization of the knee joint (TPLO, TTA) are quite invasive (tibial osteotomies), with complications that, although rare, can be potentially dramatic and can be very disabling for the dogs and their owners.
The extra-articular techniques often show disappointing results in large dogs.
The experience gained in human surgery over 25 years with the last generation of synthetic implants (LARS) for intra-articular reconstruction has shown that they are reliable and well tolerated. The same technology, with special implants adapted to dogs (STIF-VETLIG GLOBAL tm - called ZLig method in Germany - author's note) was used for this prospective study, started in 2012, to improve CCL surgery, by reconstructing the torn ligament itself to treat the pathological laxity and restore the physiological biomechanics of the knee joint.
The first 15 cases of this study were the subject of a veterinary doctoral thesis (Dr. PAGES) at VETAGROSUP LYON, the results of which encouraged us to continue it.
MATERIAL AND METHOD ZLig method
Under general anesthesia (specific protocol for each patient), a major shave and careful preparation of the skin are performed.
Upon admission, prophylactic antibiotherapy is initiated (Augmentin, 15 mg/kg IV).
The surgical technique is the same as in humans: a medial arthrotomy is performed through a medial arthrotomy through an anteromedial approach to the knee joint. The patella is dislocated laterally and resection of the infrapatellar fat pad allows complete intraarticular exploration. The cruciate ligament rupture is confirmed.
If present, the meniscal lesions are treated with a partial meniscectomy. Hyperflexion of the knee joint allows the floor of the intercondylar notch to be clearly seen and then a 2 mm long K-wire is inserted from the inside out into the lateral femoral condyle from the center of the CCL toward the upper outer lateral cortex. The lower third of the lateral edge of the caudal cruciate ligament crossed by the K-wire is a good landmark for insertion.
Depending on the weight of the animal, a cannulated drill is used and the size of the band is selected depending on the weight of the dog.
The drill is passed through the K-wire to create a femoral tunnel. The same surgical pin is then inserted through the femoral tunnel into the tibial attachment of the CCL to then exit distally on the medial aspect of the tibial metaphysis. This K-wire is used to guide the bore of the tibial tunnel from the outside to the inside.
Two transverse bone tunnels are then drilled (not performed at the beginning of our study), proximal and distal to the previous ones, in the femur and tibia. The STIF-Vetlig Global Ligament is guided through the tunnels using a thin tube and a metal loop.
The intra-articular part of the implant consists only of longitudinal fibers, the so-called “free fibers”, which make up the peculiarity of this implant and its resistance to fatigue caused by the physiological stresses of bending and twisting.
Therefore, the free fibers in the joint must be well adapted and the braided area must be placed in the bone tunnels.
The implant is then placed in the femoral bone tunnel with a suitable
Interference screw fixed. After reduction of the kneecap, isometry is checked throughout the entire range of motion.
The implant must control the front drawer but must not be too tight in any position, i.e. it must not slide into the tibial tunnel during movement. As soon as this adjustment has been made, the implant is fixed in the tibial tunnel. To achieve immediate strength, this primary fixation is achieved by passing and fixing the implant with two interference screws in the two transverse tunnels that run perpendicular to the femoral and tibial axes.
After careful cleaning with a saline solution, the joint is closed layer by layer. The final step is a moist cotton bandage with light compression for 48 hours.
The animal does not need to be immobilized and will resume normal activity when it feels like it.
Only a bandage and moderate rest (to ensure soft tissue healing) are recommended until the skin sutures are removed.
The removal of the stitches will be carried out 10 to 12 days after the operation, an orthopedic check-up at 1, 3 and 6 months after the operation and an examination will be sent later if the animal cannot be seen in the clinic.
101 dogs with a total of 107 CCL ruptures were presented to the La Cardelle Veterinary Clinic (France) between December 2012 and November 2019 and were included in the study with owner consent:
- The smallest dog weighed 6 kg (Shih-tzu), the largest weighed 81 kg (Mastiff - bilateral), the majority were over 20 kg, 5 dogs were over 70 kg.
- 2 dogs previously had a TPLO on the other side.
- 47% were male, 53% female.
- The average age was 5.3 years.
- All dogs had functional disability with limping and partial weight bearing and an anterior drawer +++, i.e. over 10 mm.
- Dogs that had already undergone surgery on the affected knee joint were excluded from the study.
RESULTS
101 dogs with 107 reconstructions and a postoperative follow-up of 1 to 9 years (mean 44 months) were included in this study.
The front drawer was missing in 94 cases (87.8%). In 8 cases (7.4%) it was rated as + (less than 5 mm).
The mechanical result is excellent or good in 95.2% of cases.
In 2 cases (1.8%) the anterior drawer was rated ++ (between 5 and 10 mm) but without functional disability. The affected dog shows no signs of limping. The owner reports no impairment of quality of life.
Overall, the front drawer could be improved in 97% of cases.
There were 3 failures (2.8%) with an anterior drawer of more than 10 mm as a preoperative situation.
In 2 cases, the implant slipped in the first 2 months after surgery, early in our experience, before we performed systematic double fixation in transverse tunnels.
In 1 case the implant had to be removed due to a severe staphylococcal infection.
It was possible to examine 3 dogs on a force plate 15 and 60 days postoperatively:
- At D+15, 2 dogs showed a weight bearing of 95% and 1 dog of 85%.
- At D+60, 1 dog showed 100%, 2 dogs 95%.
The survey was conducted using a questionnaire to the owners.
70/101 responded, corresponding to 74 reconstructions with an average postoperative period of 18 months.
- All dogs over 20 kg were able to bear weight again on the first day. The smallest dogs, weighing 13 kg or less, were unable to bear weight again until later, around the fourth day.
- With 70 bands/74 reconstructions, owners found simplicity in the postoperative period. The dog immediately regains its independence and does not require any special attention once the wound has healed. This follow-up was particularly appreciated by those owners who had already had a TPLO experience, which was considered far more complicated, with an average of 8 weeks of very limited activity, often requiring light sedation.
- The dog owners estimated that their dog had fully recovered within 2 months.
- A total of 70 reconstructions / 74 (94.5%) resulted in complete satisfaction.
- 2 owners were not completely satisfied, one of them because his dog, who had followed him on a 20 km bike ride before the injury, now started snorting after 10 km. 1 owner is not satisfied because his dog limps sporadically.
COMPLICATIONS ZLig method
– Of the 107 ligaments operated on, there were 3 superficial skin infections
all of which were cured with local treatment and antibiotics (cephalosporin) without further intervention.
without further surgery:
– 1 severe staphylococcal infection led to revision with removal of the implants, cleaning of the articular joint and tunnels, and antibiotic therapy. Complete healing was achieved within 3 weeks.
without major malfunctions:
– 2 primary fixations were ineffective in the 2 months postoperatively between 2012 and 2014 and 1 in 2019; this led to a revision of the technique with the systematic doubling of this fixation in transverse tunnels and the insertion of longer screws in bone tunnels. Since then there has been no further problem
this type occurred.
– No intolerance reaction to the implant was noted.
DISCUSSION ZLig method
The bad reputation of synthetic implants dating back to the 1980s has left human and veterinary surgeons refusing to use them. However, they are
Results in human surgery for over 25 years with the last generation of implants are very positive.
As some postoperative biopsies show, the very porous intra-articular area of free fibers seems to favor the penetration of fibroblasts and the reconstruction of a collagen structure, increasing the lifespan of the implant since it offers a better resistance to flexion and torsion, as achieved by mechanical in -vitro tests have been proven.
Although TPLO provides good results, we must admit that it does not solve the problem of laxity, which can only be solved by reconstructing the cruciate ligament itself. The TPLO procedure is a fairly invasive technique that causes irreversible changes that are not always easy to resolve in the event of complications, in contrast to intra-articular reconstruction with synthetic fibers, which only requires small bone tunnels.
CONCLUSION ZLig method
Reconstruction of the CCL using the STIF-Vetlig Global intra-articular synthetic implant leads to good to excellent results in 97% of cases. This confirms the comparison with currently accepted techniques. It is a little invasive procedure that we can consider arthroscopy can be performed, in which only small bone tunnels are created without further irreversible damage. The instruments are simple and not expensive. The surgical procedure has rules such as strict asepsis, isometry, strong fixation, but is easily reproducible.
Finally, the quick recovery and the easy postoperative period are the two main advantages for the owners, who often give feedback, especially when
they had already undergone another operation on the contralateral limb (TPLO).
All owners emphasize that they were worried about demanding attention to their dog after the operation and that they were very happy when they saw that the dog could do everything without any problems.
According to the authors, reconstruction of the CCL with a STIF implant definitely deserves consideration by veterinarians.