Below you will find a translation of the following Study from France Regarding 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.
January 2022 update of the study on the ZLig method
CRANIAL CROSS LIGAMENT RECONSTRUCTION IN DOGS BY MEANS OF THE ZLig Method
With the synthetic ligament STIF-VETLIG GLOBAL PROSPECTIVE STUDY FROM 2012 TO 2021 IN 107 CASES LE DOZE P. 1, PARIS S.2, PAGES G.3 1-2 DMV, Veterinary Clinic La Cardelle, 84 Chemin dit de Cannes 06530 LE TIGNET, FRANCE 3 ECVS
INTRODUCTION ZLig method
In the surgical treatment of 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) is quite invasive (tibial osteotomies), with complications that, although rare, can be potentially dramatic and can be very limiting for the dogs and their owners.
Extra-articular techniques often show disappointing results in large dogs.
Over 25 years of experience in human surgery with the latest generation of synthetic implants (LARS) for intra-articular reconstruction has shown them to be reliable and well-tolerated. The same technology, with special implants adapted for dogs (STIF-VETLIG GLOBAL), is now available for dogs.tm – called ZLig method in Germany – author's note) was used for this prospective study, which began 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 thorough shave and careful preparation of the skin are performed.
Upon admission, prophylactic antibiotic therapy is initiated (Augmentin, 15 mg/kg IV).
The surgical technique is the same as in humans: A medial arthrotomy is performed through an anteromedial approach at the knee joint. The patella is laterally dislocated, and resection of the infrapatellar fat pad allows for complete intra-articular exploration. The cruciate ligament rupture is confirmed.
If present, meniscal lesions are treated by partial meniscectomy. Hyperflexion of the knee joint allows good visualization of the floor of the intercondylar notch, and then a 2 mm long K-wire is inserted medially-laterally into the lateral femoral condyle from the center of the collateral ligament (CCL) towards the superior lateral cortex. The lower third of the lateral border of the cruciate ligament, which is crossed by the K-wire, serves as a good reference point for insertion.
Depending on the animal's weight, a cannulated drill is used, and the size of the band is chosen according to the dog's weight.
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 insertion of the collateral ligament (CCL), exiting distally on the medial side of the tibial metaphysis. This K-wire serves to guide the drilling of the tibial tunnel from the outside in.
Subsequently, two transverse bone tunnels are drilled (not performed at the beginning of our study), proximal and distal to the previous ones, into the femur and tibia. Using a thin tube and a metal loop, the STIF-Vetlig Global Ligament is guided through the tunnels.
The intra-articular part of the implant consists only of longitudinal fibers, the so-called "free fibers", which constitute the special feature 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 placed in the bone tunnels.
The implant is then inserted into the femoral tunnel using a suitable
The interference screw is fixed. After repositioning the patella, the isometric position is checked throughout the entire range of motion.
The implant must control the anterior drawer sign but must not be too tight in any position; that is, it must not slip into the tibial tunnel during movement. Once this adjustment is achieved, the implant is fixed within the tibial tunnel. To achieve immediate stability, this primary fixation is reinforced by passing and securing the implant with two interference screws in the two transverse tunnels, which run perpendicular to the femoral and tibial axes.
After thorough cleaning with a saline solution, the joint is closed layer by layer. This is finished with a moist cotton dressing with light compression for 48 hours.
The animal does not need to be immobilized and will resume its normal activity when it feels like it.
Until the skin sutures are removed, only a bandage and moderate rest (to ensure the healing of the soft tissues) are recommended.
The sutures are removed 10 to 12 days after the operation, an orthopedic check-up is performed 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 at the La Cardelle veterinary clinic (France) between December 2012 and November 2019 and were included in the study, with the consent of the owners:
- The smallest dog weighed 6 kg (Shih-tzu), the largest 81 kg (Mastiff - both sides), the majority were over 20 kg, 5 dogs weighed over 70 kg.
- Two dogs previously had a TPLO on the other side.
- 47 % were male, 53 % were female.
- The average age was 5.3 years.
- All dogs had a functional disability with limping and partial weight bearing and an anterior drawer sign +++, 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 the % cases.
In two cases (1, 8, %), the anterior drawer was rated ++ (between 5 and 10 mm), but without functional impairment. The affected dog shows no signs of limping. The owner reports no impairment of the dog's quality of life.
Overall, the front drawer could be improved in 97 % 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, at the beginning of our experience, before we performed systematic double fixation in transverse tunnels.
In one 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 post-operatively:
- At D+15, 2 dogs showed a weight load of 95 %, 1 dog of 85 %.
- At D+60, 1 dog showed 100%, 2 dogs showed 95%.
The survey was conducted using a questionnaire sent to the owners.
70/101 responded, which corresponds to 74 reconstructions with an average postoperative period of 18 months.
- All dogs over 20 kg were able to carry weight again on the first day. The smallest dogs, weighing 13 kg or less, were only able to carry weight again later, around the fourth day.
- In 70 cases of ligament replacement/74 reconstructions, owners appreciated the ease of the postoperative phase. The dog immediately regains its independence and requires no special attention once the wound has healed. This aftercare was particularly appreciated by owners who had previously undergone TPLO surgery, which was considered far more complicated, with an average recovery period of 8 weeks involving very limited activity and often requiring mild 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.
- Two owners were not entirely satisfied, one because his dog, which had followed him on a 20km bike ride before the injury, now starts to snort after 10km. One owner is not satisfied because his dog limps sporadically.
COMPLICATIONS ZLig method
– Of the 107 ligaments operated on, there were 3 superficial skin infections, which
all of which were cured with local treatment and antibiotics (cephalosporin) without further intervention.
without further surgery:
One severe staphylococcal infection led to revision surgery involving removal of the implants, cleaning of the joint and tunnels, and antibiotic therapy. Complete recovery was achieved within three weeks.
without major malfunctions:
Two primary fixations were ineffective in the two months postoperatively between 2012 and 2014, and one 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, no further problems have arisen with this technique.
of this kind.
– No adverse reactions to the implant were detected.
DISCUSSION ZLig method
The poor reputation of synthetic implants from the 1980s led to a reluctance among human and veterinary surgeons to use them. However, the
Results achieved in human surgery over the past 25 years with the latest generation of implants have been very positive.
As some postoperative biopsies show, the highly porous intra-articular area of free fibers appears to promote the penetration of fibroblasts and the reconstruction of a collagen structure, and to increase the lifetime of the implant, as it increases better resistance to flexion and torsion, as demonstrated by mechanical in vitro tests.
Even though TPLO delivers good results, we must admit that it doesn't solve the problem of laxity, which can only be addressed by reconstructing the cruciate ligament itself. The TPLO procedure is a fairly invasive technique that causes irreversible changes which, in the event of complications, are not always easy to correct, unlike intra-articular reconstruction with synthetic fibers, which only requires small bone tunnels.
CONCLUSION ZLig method
Reconstruction of the CCL using the intra-articular synthetic implant STIF-Vetlig Global leads to good to excellent results in 97 cases. This confirms the results compared to currently accepted techniques. It is a minimally invasive procedure that can be performed arthroscopically, creating only small bone tunnels without causing further irreversible damage. The instruments are simple and inexpensive. The surgical procedure has rules, such as strict asepsis, isometric alignment, and strong fixation, but is easily reproducible.
Ultimately, the rapid recovery and the simple postoperative phase are the two main advantages for owners, who frequently provide feedback, especially when
they had already undergone another operation on the contralateral limb (TPLO).
All owners emphasize that they were worried about the demanding care and attention their dog would receive after the operation and that they were very happy when they saw that the dog could do everything without any problems.
In the authors' opinion, reconstruction of the CCL with a STIF implant should definitely be considered by veterinarians.