**2. Materials and methods**

152 A Bird's-Eye View of Veterinary Medicine

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

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 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

arthroscopy.

the arthroscopic exam right before rupture.

This study was submitted to and approved by the UFMG committee for ethics in research, under protocol number 14/02.

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 postoperative period and during 24 hours for pain management.

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

Arthroscopic Follow-Up After Rupture of the Cranial Cruciateligament 155

3 Moderate: remarkable low projection irregularities, countable bone neoformation

suprapatellar pouch, the tibial plateau, and the intercondylar fossa. Table 2. Score system for the presence of osteophytes evaluated by stifle joint arthroscopy on

The lateral and medial menisci were evaluated according to the presence or absence of lesion. For the cruciate ligaments, the presence or absence of alterations was determined, according to neovascularization, looseness, and fiber rupture. The long digital extensor tendon was evaluated according to the presence or absence of neovascularization and villi at the insertion of the femur condyle. The variables of this study are the lesions that might have arisen or evolved, after the ligament rupture, evaluated on Day 21 by arthroscopy. The Wilcoxon test was employed for paired samples for all variables (lesions), except osteophytes, for which a

The arthroscopic examination was possible in both evaluation moments, and, as described by Person (1985), systematic examination of the joint allowed the ordering of the results (Tables 3 and 4). All structures that were visualized on Day 0 were also seen on Day 21, when it was possible to detect, in 100% of the joints, alterations in relation to Day 0, fact that was expected given the joint instability, however, statistical significance was noticed in 83.3% (Table 5). The parapatellar approach was adequate for evaluating all the articular structures or regions in this study, as well as for sectioning the CrCL. The positioning of the animal allowed flexion, extension, *varus* and *valgus* movements, and rotation of the joint during the procedure, facilitating the detailed arthroscopic examination, as reported in literature (Van Ryssen & Van Bree, 1998; Arias et al., 2003; Beale et al., 2003; Melo et al.,

individualized contour, present all over the periarticular region, including the

4 Severe: remarkable irregularity, neoformations with high projection

Days 0 and 21 after section of the cranial cruciate ligament (CrCL).

unilateral test was used. For comparisons, significance was set at P < 0.05.

Structure Region Alteration Wilcoxon P-value

Villi

Vascularization Fibrous cord

Fibrillation Vascularization 136.0 120.0

10.00 1.00

0.000 0.001

0.100 1.000

No variability1

No variability1

Score Description

**3. Results and discussion** 

2003; Rezende et al., 2006, Borges, 2006).

Lateral and medial compartments, suprapatellar region, and insertion of the patellar ligament and tendon

Patella Erosion

Synovial membrane

Articular cartilage

1 Absent: smooth articular surface. 2 Mild: low projection irregularities.

with individualized contour.

visualization of the synovial membrane, the lateral femur condyle, the long digital extensor tendon, the intercondylar fossa, the tibial plateau, the menisci, the intermeniscal and cruciate ligaments, the medial compartment, the medial femur condyle, the femoropatellar joint (articular surfaces of femur and patella, trochlear ridges), and the suprapatellar pouch. A second cutaneous and capsular incision was performed in the medial parapatellar region for introducing the arthroscopic scissor, as mentioned above. The CrCL was sectioned, remaining the intra-articular stumps. The CrCL section was confirmed by direct visualization by arthroscopy, and by the test of cranially dislocating the tibia in relation to the femur. The animals were kept in individual 4.5m² cages, for 21 days, and, after that period, submitted to new arthroscopic examination. Synovial fluid was collected, and the joint cavity was distented as described above. The intra-articular structures were systematically evaluated, as previously described, and the alterations found in the soft and in the hard tissues were documented . The images were analyzed based on the arthroscopic findings on Day 0, when the first arthroscopy was performed followed by the CrCL rupture, and at Day 21, when a new arthroscopy was conducted for evaluating the articular lesions. The structures were also individually evaluated, and abnormalities were registered. According to their quantity and aspect, villi were classified (Tab.1) from 1 to 4; grade 1 represented absence of lesion and 4, severe lesion. The villi were also morphologically classified as: filamentous, thin, interlaced, short, and as polyp, staff, fringe, bush, fan, and cauliflower shapes. In addition, they were categorized in respect to their localization: lateral and medial compartments, patellar ligament, and patellar tendon. The presence or absence of intra-articular fibrous cords was taken into account. Additionally, the articular cartilage was evaluated by area: patella, suprapatellar pouch, trochlear surface, intercondylar fossa, medial and lateral femur condyles, trochlear ridges of the femur, and surface of the tibia condyles. Likewise, the presence of osteophytes was classified according to the scores in Table 2.

#### Villi of the synovial membrane


#### Score Description 1 Absent. 2 Mild: discrete presence of ingurgitated vessel in up to two regions. 3 Moderate: vascularization, apparent hyperemia at the lateral and medial compartments, cruciate ligaments, and menisci. 4 Severe: hypervascularization, hyperemia of the lateral and medial

Table 1. Scores system for the synovial membrane characteristics evaluated by stifle joint arthroscopy on Days 0 and 21 after section of the cranial cruciate ligament (CrCL).

compartments, menisci, and ligaments; articular hemorrhage.


Table 2. Score system for the presence of osteophytes evaluated by stifle joint arthroscopy on Days 0 and 21 after section of the cranial cruciate ligament (CrCL).

The lateral and medial menisci were evaluated according to the presence or absence of lesion. For the cruciate ligaments, the presence or absence of alterations was determined, according to neovascularization, looseness, and fiber rupture. The long digital extensor tendon was evaluated according to the presence or absence of neovascularization and villi at the insertion of the femur condyle. The variables of this study are the lesions that might have arisen or evolved, after the ligament rupture, evaluated on Day 21 by arthroscopy. The Wilcoxon test was employed for paired samples for all variables (lesions), except osteophytes, for which a unilateral test was used. For comparisons, significance was set at P < 0.05.
