**1. Introduction**

150 A Bird's-Eye View of Veterinary Medicine

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The femoro-patellar-tibial joint is one of the most complex, with different structures that, altogether, keep the joint stability and functionality (Cook, 2010; de Rooster et al., 2010, Pozzi & Kim, 2010). Due to its big functional demand, the cranial cruciate ligament (CrCL) is the structure most frequently injured. The rupture of this ligament is of the most common causes of lameness in the dog and the resulting instability leads to the development of degenerative joint disease (DJD). Still today, the search for the ideal technique to treat CrCL rupture, with joint stabilization and prevention or minimization of DJD, persists. However, would joint stabilization be the only factor to be considered for the treatment of CrCL rupture and its sequels? Won't the effects of instability on the other structures deserve more investigation? Would the inflammatory response mediators be responsible for the looseness of the intra-articular graft or is it exclusively due to improper fixation or inadequate postoperatory?

According to literature, the joint degeneration process starts as soon as seven days after CrCL rupture and, at Day 21, signals suggesting osteoarthritis can be radiographically examined. In arthroscopic evaluation, however, lesions are already significant and characteristic in this period.

Arthroscopy is a minimally invasive exam, with minimal morbidity, which allows complete visualization of structures with magnification of images and precise diagnosis of the articular condition in its natural environment. The minimal morbidity enables periodic joint evaluations (Van Ryssen & Van Bree, 1998; Hulse et al., 2010; Goldhammer et al., 2010), what permits to monitor the lesion ( Borges, 2006; Bleedorn et al., 2011) and the treatment evolution (Case et al., 2008), allowing the articular function prognosis (Ljungvall & Ronéus, 2011).

Arthroscopy can be employed for evaluating and defining the DJD staging. It gives the surgeon a better understanding of the joint degeneration process, the most prevailing condition among all diseases in the dog.

The arthroscopy had a significant impact especially in our clinical practice in what concerns diagnosis and treatment of articular alterations in the dog. Non-specific arthritis,

Arthroscopic Follow-Up After Rupture of the Cranial Cruciateligament 153

diagnostic method that, despite being an invasive procedure and requiring anesthesia, it allows direct and magnified evaluation of the articular structures, and enables serial evaluations, once tissue invasion and morbidity are minimal (Van Ryssen & Van Bree, 1998; Frizziero & Ronchetti, 2002; Arias et al., 2003; Beale et al., 2003; Melo et al., 2003; Borges, 2006; Rezende et al., 2006; Hulse, et al., 2010; Bleedorn et al., 2011). In CrCL rupture, arthroscopy offers more than a precise diagnosis of the affection, it allows evaluation through magnified visualization of degenerative alterations of the joint such as fibrillation, cartilage erosion, synovial membrane proliferation, and neovascularization, osteophytes formation, besides detecting lesions in the menisci (Siemering & Eilert, 1986; Adamiak, 2002; Borges, 2006; Case et

Arthroscopy in dogs, initially employed for diagnostic purpose, has become a surgical alternative to many articular affections (Rochat, 2001) and has revolutionized the treatment of joint disease in human beings and animals (Beale & Hulse, 2010). The magnifying of the structures allows the surgeon to recognize and treat lesions that could not be distinguished through arthrotomy (Van Ryssen & Van Bree, 1998; Sams, 2000; Borges, 2006; Beale & Hulse,

This study was submitted to and approved by the UFMG committee for ethics in research,

Eighteen mixed breed, adult healthy dogs (9 males and 9 females), with 18 to 25kg of body mass were used in this work. The animals were sheltered in individual cages and fed with commercial pet food and water *ad libitum.* Bilateral radiographic examination of the stifle joint was performed in craniocaudal and mediolateral incidences to confirm the radiographic normality of these joints in both hind limbs. Blood samples were collected for serum biochemical analysis, hemogram, and coagulogram. After 15 days of adaptation period, the first arthroscopy was performed to articular evaluation and CrCL section, and the second, for articular evaluation 21 days later. The animals were premedicated with atropine sulfate (0.044mg/kg), subcutaneously, and xylazine chlorhydrate (1mg/kg), intramuscularly. Anesthesia was induced with sodium thiopental (12.5mg/kg), intravenously, and maintained with isoflurane in semi-open circuit. Antibiotic prophylaxis was performed with cefalotin (30mg/kg), intravenously, 30 minutes before surgery. All animals received tramadol chlorhydrate (2mg/kg), intramuscularly, in the immediate post-

The animals were submitted to arthroscopic evaluation and subsequent CrCL section. The animals were prepared for aseptic surgery and positioned in dorsal recumbence over a metal gutter. Synovial fluid was collected in heparinized syringe and the joint cavity was distended with 10 to 15 ml of Ringer's lactate solution thereafter. A 5 mm cutaneous incision was performed in the lateral parapatellar region, and the articular capsule was incisioned with a scalpel blade No. 11 for introducing the arthroscopic sheath guided by atraumatic trocar. The irrigation system was attached to the arthroscopic sheath while the atraumatic trocar was removed and replaced by a 2.7mm, 30º arthroscope, connected to the camera. Arthroscopic evaluation was conducted based on the articular compartments, as suggested by Person (1985). Articular structures were inspected: the lateral compartment with

al., 2008; Goldhammer et al., 2010; Hulse et al., 2010; Bleedorn et al., 2011.

2010; Hulse et al, 2010; Bleedorn et al., 2011 ).

operative period and during 24 hours for pain management.

**2. Materials and methods** 

under protocol number 14/02.

hemarthrosis, meniscus lesions, ligament partial ruptures, femoral condyle osteochondrosis, and presence of loose cartilaginous bodies not diagnosed by the radiographic exam are examples of clinical situations that nowadays are promptly diagnosed and treated through arthroscopy.

The arthroscopic monitoring of the femoro-patellar-tibial joint after CrCL rupture changed the procedures by which such condition is treated in our routine, and its stabilization began to be considered as a condition that must be treated the most precociously possible and through arthroscopy. The main challenge is the development of efficient therapies for the osteoarthritis control. The association of articular stabilization with cell therapy (stem cells, growth factors) is one of the alternatives under study at the moment. The purpose of this chapter is, in the meanwhile, presenting the articular findings, under arthroscopic vision, 21 days after arthroscope-guided CrCL rupture, taking as reference the parameters found in the arthroscopic exam right before rupture.

The rupture of the cranial cruciate ligament (CrCL) is one of the most frequent orthopedic affections in the dog (Johnston, 1997; Beale & Hulse, 2010; Van Bree et al., 2010). After rupture, the CrCL does not regenerate, leading to lost of joint stability. The resulting instability leads to the development of degenerative joint disease (DJD) ( Innes, 2010), and treatment is still challenging. The unavoidable DJD progression (Vasseur & Berry, 1992; Lazar et al., 2005) is caused by enzymatic degradation of the articular cartilage (Bennett & May, 1997). As the alterations in the cartilage progress, reduction in the content of proteoglycans, hyalunoric acid, and collagen (in minor proportion) occur due to the action of catabolic enzymes released by the DJD. Once the cartilaginous lesion is installed, the subchondral bone is exposed to the synovial fluid and, when subjected to abnormal pressures and tensions, reacts forming osteophytes and subchondral sclerosis (Johnston, 1997). Periarticular osteophytes indicate articular instability and are one of the most evident radiographic signs of DJD (Schrader, 1995; Innes et al., 2004). Osteophytes are bone projections located at the peripheral region of the joint, most frequently at the osseous insertion of the synovial membrane, the perichondrium, and the periosteum, though it may occur at the central region of the joint (Johnston, 1997). As the DJD evolves, after CrCL rupture, formation of osteophytes occurs first at the osteochondral margin of the lateral and medial trochlear ridges, then at the proximal region of the tibia and the proximal and distal borders of the patella (Lewis et al., 1987; Moore & Read, 1996). Some studies attribute to the synovitis and the consequent release of inflammatory mediators by the synoviocytes the triggering factors for DJD (Lipowitz et al., 1985;). In DJD, the synovial villi are hypertrophied, with augmented mature and immature collagen in the subsynovial tissue (Jonhston, 1997). McIlwraith & Fessler (1978) classified morphologically the villi in filamentous, thin, interlaced, short, and in the shapes of polyp, staff, fringe, bush, fan, and cauliflower. In normal joints, the thin polyp-shaped, and the short, rounded, membranous and staff-shaped villi are commonly observed (McIlwraith & Fessler, 1978; Kurosaka et al., 1991), while bigger and reddish villi, with petechial hemorrhages, and in the shapes of fan, cauliflower, fringe and bush are frequently found in joints with synovitis (McIlwraith & Fessler, 1978). The follow-up of the degenerative process evolution, as well as its treatment response, is constantly challenging. Among the methods routinely used in DJD diagnosis are the clinical evaluation (which is subjective) and the radiographic and ultrasonographic examination (which rely on the evaluator's experience). The arthroscopy is another diagnostic method that, despite being an invasive procedure and requiring anesthesia, it allows direct and magnified evaluation of the articular structures, and enables serial evaluations, once tissue invasion and morbidity are minimal (Van Ryssen & Van Bree, 1998; Frizziero & Ronchetti, 2002; Arias et al., 2003; Beale et al., 2003; Melo et al., 2003; Borges, 2006; Rezende et al., 2006; Hulse, et al., 2010; Bleedorn et al., 2011). In CrCL rupture, arthroscopy offers more than a precise diagnosis of the affection, it allows evaluation through magnified visualization of degenerative alterations of the joint such as fibrillation, cartilage erosion, synovial membrane proliferation, and neovascularization, osteophytes formation, besides detecting lesions in the menisci (Siemering & Eilert, 1986; Adamiak, 2002; Borges, 2006; Case et al., 2008; Goldhammer et al., 2010; Hulse et al., 2010; Bleedorn et al., 2011.

Arthroscopy in dogs, initially employed for diagnostic purpose, has become a surgical alternative to many articular affections (Rochat, 2001) and has revolutionized the treatment of joint disease in human beings and animals (Beale & Hulse, 2010). The magnifying of the structures allows the surgeon to recognize and treat lesions that could not be distinguished through arthrotomy (Van Ryssen & Van Bree, 1998; Sams, 2000; Borges, 2006; Beale & Hulse, 2010; Hulse et al, 2010; Bleedorn et al., 2011 ).
