Bilateral Successive Cranial Cruciate Ligament Rupture Treated by Extracapsular Stabilization Surgery in a Pet Rabbit (Oryctolagus cuniculus)

Treatment of osteoarthritis by implantation of Mg- and WE43-cylinders - A preclinical study on bone and cartilage changes and their influence on pain sensation in rabbits

With its main features of cartilage degeneration, subchondral bone sclerosis and osteophyte formation, osteoarthritis represents a multifactorial disease with no effective treatment options. As biomechanical shift in the trabecular network may be a driver for further cartilage degeneration, bone enhancement could possibly delay OA progression. Magnesium is known to be osteoconductive and already showed positive effects in OA models. We aimed to use magnesium cylinders to enhance subchondral bone quality, condition of cartilage and pain sensation compared to sole drilling in vivo. After eight weeks of implantation in rabbits, significant increase in subchondral bone volume and trabecular thickness with constant bone mineral density was found indicating favored biomechanics. As representative for pain, a higher number of CD271+ vessels were present in control samples without magnesium. However, this result could not be confirmed by sensitive, objective lameness evaluation using a pressure sensing mat and no positive effect could be shown on either cartilage degeneration evaluated by OARSI score nor the presence of regenerative cells in CD271-stained samples. The presented results show a relevant impact of implanted magnesium on key structures in OA pain with missing clinical relevance regarding pain. Further studies with shifted focus should examine additional structures as joint capsule or osteophytes.

Arthroscopic approach and anatomy of the stifle joint in the rabbit

OBJECTIVE

To describe a technique and normal findings for arthroscopy of the stifle in rabbits.

STUDY DESIGN

Cadaver study.

ANIMALS

Twenty cadaveric stifles from New Zealand White rabbits were examined.

METHODS

The arthroscope was placed through a medial portal, and instrument portals were created on the lateral aspect of the joint. The same portals were used for examination of the entire joint and palpation of structures with a probe.

RESULTS

Structures identified in the proximal aspect of the stifle included the suprapatellar pouch, suprapatella, patella, medial and lateral proximal recesses, medial and lateral trochlear ridges, trochlear groove. Structures identified in the distal aspect of the joint included the cranial and caudal cruciate ligaments, medial and lateral menisci, medial and lateral femoral condyles, the long digital extensor tendon, and the cranial meniscal ligaments were identified. All of the proximal structures could be seen in 16/20 limbs. Distally, the cranial cruciate ligament could be identified and manipulated most often (17/20 limbs), followed by the caudal cruciate ligament (11/20), the menisci (9/20), and condyles (9/20). The average examination time was 27 minutes. There was a variably present femorotibial membrane.

CONCLUSION

We conclude that the arthoscopic evaluation of the stifle in rabbits is a viable surgical approach and could be used for rabbit models or to examine clinical cases with stifle pathology. Precise portal placement and adequate infrapatellar fat pad debridement were critical for success.

Surgical Correction of Patellar Luxation in a Rabbit

A two-and-a-half-year-old giant lop-eared rabbit, weighing 5.1 kg, presented with a one-month history of intermittent right hind limb lameness. The limb locked in extension during hopping. On examination, a grade-2 medial patellar luxation of the right hind was diagnosed, with associated stifle joint swelling. Radiographic findings of the right stifle comprised periarticular osteophyte formation consistent with mild degenerative joint disease and joint effusion. Surgical correction involving right trochlear wedge recession sulcoplasty and lateral imbrication was carried out to stabilise the patella in the trochlear groove. The right hind limb lameness resolved, and the patella was stable at a 6-month postoperative examination. One year postoperatively, the right patella was luxating again concurrent with bilateral stifle effusions. Euthanasia was performed twenty months after surgery due to recurrent lameness in the right hind limb.