Intra-articular replacement of the caudal cruciate ligament using a UHMWPE ligament under arthroscopic guidance in a dog: A case report.

Background: As isolated ruptures of the caudal cruciate ligament (CdCL) are rare in dogs, there is no consensus on the indications and the gold-standard surgical technique for treatment. Case Description: A 2-year-old Shepherd dog with an isolated rupture of the CdCL was treated with a new surgical technique for synthetic reconstruction. Three bone tunnels were drilled in the femur and the tibia under arthroscopic guidance to make sure the anatomical insertions of the physiological ligament were respected. An ultra-high molecular weight polyethylene (UHMWPE) implant was fixed with interference screws to reconstruct the CdCL. A synovial inflammation remained present on radiographs for 6 months after the surgery, together with a mild lameness. However, the dog fully recovered clinically and recovered a normal level of activity after 6 months. Liverpool osteoarthritis in dogs questionnaire results at 6 months and 1 year postoperatively were excellent. Conclusion: The use of a UHMWPE implant fixed with interference screws to reconstruct the CdCL allowed a return to full function of the knee without complications, despite a persistent synovial inflammation and mild lameness for a 6-month period after the surgery. The success of this isolated surgical technique could lead to improvements in the surgical management of CdCL rupture, if these initial results are confirmed by a prospective study with a larger number of patients.

Ex-vivo biomechanical analysis of an original repair of canine calcaneal tendon rupture using a synthetic implant as mechanical support fixed by sutures in the proximal tendinous part and by an interference screw in the bone distal part.

Background: Rupture of the common calcaneal tendon is the second most frequent tendon rupture in dogs and may lead to severe lameness and pain. Surgical repair consists of re-apposition of the damaged tendon ends using sutures, but this type of repair is not always possible especially if the tendon has retracted. Tendon augmentation with an ultra-high molecular weight polyethylene (UHMWPE) implant is a recent solution to support the sutures and allow the repair of the canine calcaneal tendon. However, its biomechanical fixation strength remains untested for this pathology. Aim: To evaluate the biomechanical fixation strength of a UHMWPE implant for the repair of the canine calcaneal tendon. Methods: Ex-vivo biomechanical study was carried out on eight cadaveric hindlimbs from four adult dogs. Hindlimbs were tested under two independent modalities: proximal tendinous fixation (PTF) and distal calcaneus fixation (DCF), using a testing machine. PTF was achieved by eight simple interrupted polypropylene sutures performed through the UHMWPE implant. The latter was sandwiched inside the gastrocnemius tendon, which had previously been incised over about 5 cm longitudinally, and through the tendon of the superficial digital flexor. DCF was performed using an interference screw, which locked the UHMWPE implant into a calcaneus tunnel drilled perpendicularly. Results: Yield, failure load, and linear stiffness (mean ± SD) for the DCF modality were 920 ± 139 N, 1,007 ± 146 N, and 92 ± 15.21, respectively, which were greater than for the PTF modality (663 ± 92 N, 685 ± 84 N and 25.71 ± 5.74, respectively, p < 0.05). Failure modes were different between fixation modalities: for PTF it was suture breakage (n = 7/8), while for DCF it was implant damage and slippage (n = 8/8). Conclusion: The biomechanical fixation strength of the UHMWPE implant was greater for DCF than that of PTF, and should be suitable for calcaneal tendon repair in dogs. The clinical prediction of rupture of this calcaneal tendon repair will occur at the level of the PTF.

Long-term outcome following synthetical reconstruction of the medial collateral tarsal ligament in a dog.

Background: Tibiotarsal instabilities caused by partial or complete rupture of the medial collateral tarsal ligament (MCTL) are commonly treated by arthrodesis techniques with poor functional results and significant complication rates. Case Description: This study describes a new surgical technique for synthetic reconstruction of the MCTL in an overweight dog (estimated body condition score 8/9) with an avulsion of the long head of the MCTL. Three bone tunnels were drilled in the distal tibia, the talus, and the central tarsal bone, thus respecting the anatomical insertions of the physiological ligament. An Ultra-High Molecular Weight Polyethylene (UHMWPE) implant was fixed with interference screws to reconstruct the long and short heads of the MCTL. Premature weight-bearing was reported at 2 weeks postoperatively following early removal of the flexible restraint (bivalve resin boot), which had initially been prescribed for 6 weeks. At 11 weeks postoperatively, the tibiotarsal joint showed good valgus stability and the dog's gait was subnormal. At 12 and 16 months postoperatively, the dog regained full function of the operated limb although no weight loss was initiated as recommended. Conclusion: The use of a UHMWPE implant fixed with interference screws to reconstruct the MCTL allowed a return to full function of the tibiotarsal joint, without complications despite an early return to weight-bearing without external restraint. The success of this isolated surgical technique could lead to improvements in the surgical management of MCTL rupture if these initial results are confirmed by a prospective study with a larger number of patients.

Biomechanical cyclic loading test of a synthetic ligament fixation system used for intra-articular stabilization of deficient canine stifles.

Background: Cranial cruciate ligament rupture (CCLr) is the most common cause of hind limb lameness in dogs. Currently, surgical management of CCLr is mostly performed using tibial osteotomy techniques to modify the biomechanical conformation of the affected stifle. These surgical techniques have a significant complication rate, associated with persistent instability of the stifle which may lead to chronic postoperative pain. Over the last decade, studies have been published on various techniques of anatomical caudal cruciate ligament reconstruction in veterinary practice, using physiological autografts or woven synthetic implants. Aim: The aim of this ex vivo biomechanical study is to investigate the ex vivo dynamic biomechanical behavior of a synthetic implant [ultrahigh molecular weight polyethylene (UHMWPE) implant] fixed with interference screws for the treatment of CCLr in dogs, according to a fatigue protocol (48 hours per test). Methods: Seven stifles from four skeletally mature canine cadavers were implanted with the synthetic implant. It was fixed with four interference screws inserted in transversal and oblique tunnels in both the distal femur and the proximal tibia. For each case, 100,000 cycles were performed at 0.58 Hz, with traction loads ranging from 100 to 210 N. Results: Neither screw-bone assembly rupture nor a pull-out issue was observed during the dynamic tests. Linear stiffness of the implants associated with a fixation system with four interference screws increased over time. The final displacement did not exceed 3 mm for five of the seven specimens. Five of the seven synthetic implants yielded to a lengthening in functional range (0-3 mm). Linear stiffness was homogeneous among samples, showing a strong dynamic strength of the interference screw-based fixations of the UHMWPE implant in the femoral and tibial bones. Conclusion: This study completes the existing literature on the biomechanical evaluation of passive stifle stabilization techniques with a testing protocol focused on cyclic loading at a given force level instead of driven by displacement. These biomechanical results should revive interest in intra-articular reconstruction after rupture of the CCLr in dogs.

Repair of Tendon Disruption Using a Novel Synthetic Fiber Implant in Dogs and Cats: The Surgical Procedure and Three Case Reports.

Surgical management of tendon rupture is challenging. One concern is to provide adequate tensile strength to prevent distraction during weight-bearing and gap formation following repair, associated with an increased risk of repair failure. Additional challenges may arise from the nature or the chronicity of the lesion. In the event of avulsion, when the tendon is torn off at the bone insertion, its reinsertion on the bone is generally difficult and may even be impossible in the presence of an avulsion fracture, especially when the bone fragment is too small or fragmented. Repair management is also complicated in chronic cases, as degeneration of the tendon may lead to excessive scar tissue formation, tendon retraction, and muscle atrophy, resulting in a large gap and inadequate tissue for reconstruction. The authors describe the surgical procedure for implanting a novel implant, illustrated by three characteristic clinical cases: (1) an acute Achilles tendon avulsion; (2) a chronic patellar tendon rupture; and (3) a chronic avulsion fracture of the triceps tendon. In these three cases, complete recovery of the function was observed at the last clinical evaluation (6 or 8 months), and no complication was noted. A splinted dressing (6 to 8 weeks) was used successfully in two cases. A resin cast (8 weeks) was preferred in case 1, a very active dog. In conclusion, this novel implant represents a simple procedure for the effective repair of chronic tendon rupture, as well as an effective tendon reinsertion on the bone and adequate support for bone tendon healing in the treatment of tendon avulsion, even in cases of fragmented bone fracture. The thinness of the implant facilitates its insertion into the native tendon, while the bone-screw-implant interface provides immediate and lasting mechanical support. This may facilitate the healing process and potentially shorten the period of immobilization.

Original surgical treatment of thoracolumbar subarachnoid cysts in six chondrodystrophic dogs.

BACKGROUND: Subarachnoid cysts are rare conditions in veterinary medicine, associated with spinal cord dysfunction. Most of the 100 cases of subarachnoid cysts described since the first report in 1968 were apparently not true cysts. Reported cysts are usually situated in the cervical area and occur in predisposed breeds such as the Rottweiler. The purpose of this retrospective study, from May 2003 to April 2012, was to describe the distinctive features of thoracolumbar spinal subarachnoid cysts, together with their surgical treatment and outcome in 6 chondrodystrophic dogs. RESULTS: Five Pugs and 1 French Bulldog were examined. Images suggestive of a subarachnoid cyst were obtained by myelography (2/6) and computed tomography myelography (4/6), and associated disc herniation was observed in 3/6 dogs. A hemilaminectomy was performed. The protruding disc eventually found in 5/6 dogs was treated by lateral corpectomy. The ventral leptomeningeal adhesions observed in all dogs after durotomy were dissected. No or only mild post-operative neurological degradation was observed. Follow-up studies (7 months to 4 years) indicated good outcome and no recurrence. CONCLUSIONS: All the thoracolumbar subarachnoid cysts described in these 6 chondrodystrophic dogs were associated with leptomeningeal adhesions. Good results seemed to be obtained by dissecting and removing these adhesions. A protruding disc, found here in 5/6 dogs, needs to be ruled out and can be treated by lateral corpectomy.