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Objective:  The aim of this study was to describe the arthroscopic changes to the caudal cruciate ligament (CdCL) in dogs with cranial cruciate ligament disease., Study Design:  Arthroscopic video recordings ( n  = 117) of the stifle with cranial cruciate ligament disease were reviewed. The extent of CdCL tearing was described. Signalment, palpable stifle stability and the presence of a meniscal tear were recorded. Pathology of the synovial joint and the synovium overlying the CdCL were scored at two time points.Two-way interactions were investigated ( p  < 0.05). Univariate analysis and a Wald test ( p  < 0.20) were performed. Factors were retained with a Wald test p  < 0.05 or if a confounder, then a changing model coefficient >15%. A weighted kappa statistic was used to evaluate intraobserver agreement., Results:  Caudal cruciate ligament tearing was identified in 94% of stifles. Longitudinal tearing (76%) was the most common type of damage (45% partial, 31% full thickness). Synovitis was present in all joints and changes to the synovium overlying the CdCL were less frequently identified (67%).Synovitis was associated with the degree to CdCL tearing. Synovitis overlying the CdCL was associated with lower body weight and lower CdCL damage., Conclusion:  Caudal cruciate ligament damage is common in dogs with cranial cruciate ligament disease and longitudinal tearing was the most common injury identified. Severity of joint pouch synovitis was positively correlated with the degree of CdCL damage and the portion of the CdCL not exposed to the synovium was unaffected. These findings suggest synovitis is likely a contributor to CdCL injury., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective: To investigate histopathological features of synovium from dogs with cranial cruciate ligament disease (CCLD) to seek mechanisms of osteoarthritis (OA) associated with CCLD., Study Design: Retrospective, single-institution case series., Animals: Thirty client-owned dogs., Methods: Synovial biopsies (n = 30) obtained from stifles with CCLD were assessed by using two synovitis histopathology grading systems (Krenn and Hospital for Special Surgery [HSS]). The Krenn synovitis score was interpreted as "no synovitis," "low-grade," or "high-grade," while inflammatory subtype (low, mixed, or high) was determined by a computational algorithm within the HSS system. Comparison of synovitis scores was based on degree of CCL rupture and presence of meniscal tears., Results: Histopathological changes and synovitis scores were similar regardless of degree of rupture (partial n = 5, complete n = 25) or presence of meniscal injury (n = 12) and were characterized by hyperplastic and lymphoplasmacytic synovitis with increased vascularity (30/30) and the presence of hemosiderin deposits (28/30), binucleated plasma cells (28/30), mucoid change (25/30), and Mott cells (16/30). Thirteen (43%) specimens were consistent with high-grade synovitis according to the Krenn system, while 11 (37%) specimens fit into the high-inflammatory subtype with the HSS system., Conclusion: Synovitis associated with canine CCLD in this study population was lymphoplasmacytic and was often highly inflammatory, with the presence of cells pertaining to humoral immunity. Humoral immune responses may play key roles in the synovitis associated with CCLD., Clinical Significance: Modulation of biological factors that provoke humoral immune responses may mitigate symptoms of OA that persist and progress even after surgical treatment of CCLD in dogs., (© 2021 The American College of Veterinary Surgeons.)

Cranial cruciate ligament disease and rupture (CCLD/R) is one of the most common orthopaedic conditions in dogs, eventually leading to osteoarthritis of the stifle joint. Certain dog breeds such as the Staffordshire bull terrier have an increased risk of developing CCLD/R. Previous studies into CCLD/R have found that glycosaminoglycan levels were elevated in cranial cruciate ligament (CCL) tissue from high-risk breeds when compared to the CCL from a low-risk breed to CCLD/R. Our objective was to determine specific proteoglycans/glycosaminoglycans in the CCL and to see whether their content was altered in dog breeds with differing predispositions to CCLD/R. Disease-free CCLs from Staffordshire bull terriers (moderate/high-risk to CCLD/R) and Greyhounds (low-risk to CCLD/R) were collected and key proteoglycan/glycosaminoglycans were determined by semi-quantitative Western blotting, quantitative biochemistry, quantitative reverse transcription polymerase chain reaction, and immunohistochemistry. Gene expression of fibromodulin (P = 0.03), aggrecan (P = 0.0003), and chondroitin-6-sulphate stubs (P = 0.01) were significantly increased, and for fibromodulin this correlated with an increase in protein content in Staffordshire bull terriers compared to Greyhound CCLs (P = 0.02). Decorin (P = 0.03) and ADAMTS-4 (P = 0.04) gene expression were significantly increased in Greyhounds compared to Staffordshire bull terrier CCLs. The increase of specific proteoglycans and glycosaminoglycans within the Staffordshire bull terrier CCLs may indicate a response to higher compressive loads, potentially altering their risk to traumatic injury. The higher decorin content in the Greyhound CCLs is essential for maintaining collagen fibril strength, while the increase of ADAMTS-4 indicates a higher rate of turnover helping to regulate normal CCL homeostasis in Greyhounds., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Cranial cruciate ligament rupture (CCLR) is one of the most common orthopaedic disorders diagnosed in dogs yet the factors which influence postoperative clinical outcomes are poorly understood. Low vitamin D status has been linked to poorer clinical outcomes in human patients undergoing elective orthopaedic surgery. The aim of this study was to examine the relationship between pre-operative vitamin D status, as defined by serum 25 hydroxyvitamin D (25(OH)D) concentrations, and initial disease severity and clinical outcomes in dogs undergoing surgical treatment for a CCLR. Serum 25(OH)D concentrations were measured in 44 dogs with a CCLR on the day before surgery. C-reactive protein concentrations were measured at a median time of 1 day post-surgery and the patient's clinical and radiographic response to CCLR surgical treatment was assessed at a median timepoint of 60 days post-surgery. Serum 25(OH)D concentrations in dogs with a CCLR was not significantly different to a population of healthy dogs (median 74.1 nmol/L and 88.40 nmol/L, respectively). There was no significant correlation between pre-operative serum 25(OH)D concentrations and length of pre-diagnosis clinical signs, pre-operative lameness scores or day 1 post-operative CRP concentrations. Thirty nine of the 44 dogs were re-examined at a median 60 days post-surgery. There was no relationship between the day 60 lameness scores and pre-operative serum 25(OH)D concentrations. In summary, we discovered that the vitamin D status of dogs with a CCLR was not significantly lower than healthy dogs and pre-operative serum 25(OH)D concentrations were not correlated to either pre-surgical disease severity or post-operative clinical outcomes., (Copyright © 2021. Published by Elsevier Ltd.)

Cranial cruciate ligament disease (CCLD) is the most common cause of pelvic limb lameness in dogs but its precise aetiopathogenesis is uncertain. Fibrillin microfibrils (FM) are complex macro-molecular assemblies found in many tissues including ligaments, where they are thought to play an important mechanical role. We hypothesised that FM ultrastructural variation correlates with the differing predisposition of canine breeds to CCLD. Non-diseased cranial and caudal cruciate ligaments (CCLs and CaCLs) were obtained from Greyhound (GH) and Staffordshire Bull Terrier (SBT) cadavers. Fibrillin microfibrils were extracted from the ligaments by bacterial collagenase digestion, purified by size-exclusion chromatography and subsequently visualized by atomic force microscopy (AFM). With AFM, FMs have a characteristic beads-on-a-string appearance. For each FM, periodicity (bead-bead distance) and length (number of beads/FM) was measured. Fibrillin microfibril length was found to be similar for GH and SBT, with non-significant inter-breed and inter-ligament differences. Fibrillin microfibril periodicity varied when comparing GH and SBT for CCL (GH 60.2 ± 1.4 nm; SBT 56.2 ± 0.8 nm) and CaCL (GH 55.5 ± 1.6 nm; SBT 61.2 ± 1.2 nm). A significant difference was found in the periodicity distribution when comparing CCL for both breeds (P < 0.00001), further, intra-breed differences in CCL vs CaCL were statistically significant within both breeds (P < 0.00001). The breed at low risk of CCLD exhibited a periodicity profile which may be suggestive of a repair and remodelling within the CCL., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The usefulness of studying posture and its modifications due to locomotor deficiencies of multiple origins has been widely proven in humans. To assess its suitability in the canine species, static posturography and dynamic pedobarography were performed on lame dogs affected with unilateral elbow dysplasia and cranial cruciate ligament rupture by using a pressure platform. With this objective, statokinesiograms and stabilograms, the percentage of pressure distribution between limbs, paw area, mean pressure, and peak pressure, were obtained from lame and sound dogs. These data were compared with Peak Vertical Force values originated from a force platform in the same recording sessions., Results: Significant differences were found in the parameters mentioned above between sound and lame dogs and limbs., Conclusions: Posturography and pedobarography are useful and reliable for the monitoring of fore and hindlimb lameness in dogs, providing a new set of parameters for lameness detection.

Objectives: To report short-term radiographic and clinical outcome and complications following tibial plateau levelling osteotomy for the treatment of cranial cruciate ligament insufficiency in dogs less than 18·1 kg with tibial plateau angle greater than 35° using anatomically contoured six-hole locking compression plates., Methods: Retrospective data were collected on: preoperative, postoperative and follow-up tibial plateau angles, plateau segment rotation, tibial tuberosity width and length of the cranial aspect of tibial tuberosity segment from the patellar tendon insertion and rotation of the tibial plateau below the level of the insertion of the patellar ligament., Results: In 26 small dogs (29 stifles in total), mean preoperative, postoperative and follow-up tibial plateau angles were 38·2°, 4·8°, and 4·4°, respectively. Documented postoperative complications were limited to patellar tendinopathy in a single case (3·4%) and tibial tuberosity or fibula fracture were not observed., Clinical Significance: Short-term radiographic and clinical outcome of tibial plateau levelling osteotomy stabilised with anatomically contoured six-hole locking compression plates for the treatment of small dogs with large tibial plateau angle suggests a very low risk of complications. Rotation beyond the "safe point" is necessary to perform full rotation in some cases, but does not appear to incur an increased risk of tibial tuberosity fracture., (© 2016 British Small Animal Veterinary Association.)

Degenerative cranial cruciate ligament (CCL) rupture is characterized histologically by degenerating extracellular matrix (ECM) and chondroid metaplasia. Here, we describe the progression of chondroid metaplasia and the changes in the expression of ECM components in canine CCL rupture (CCLR). CCLs from 26 stifle joints with CCLR (CCLR group) and normal CCLs from 12 young beagles (control group) were examined histologically and immunohistochemically for expression of type I (COLI), type II (COLII), type III collagen (COLIII) and Sry-type HMG box 9 (SOX9). Cell density and morphology of CCLs were quantified using hematoxylin-eosin staining. The percentage of round cells was higher in the CCLR group than in controls. COLI-positive areas were seen extensively in the connecting fibers, but weakly represented in the cytoplasm of normal CCLs. In the CCLR group, there were fewer COLI-positive areas, but many COLI-positive cells. The percentages of COLII-, COLIII- and SOX9-positive cells were higher in the CCLR group than in controls. The number of spindle cells with perinuclear halo was high in the CCLR group, and most of these cells were SOX9-positive. Deposition of COLI, the main ECM component of ligaments, decreased with increased COLIII expression in degenerated CCL tissue, which shows that the deposition of the ECM is changed in CCLR. On the contrary, expression of SOX9 increased, which may contribute to the synthesis of cartilage matrix. The expression of COLII and SOX9 in ligamentocytes showed that these cells tend to differentiate into chondrocytes.

This case report describes the management of cranial cruciate ligament avulsion from the femur of a four-year-old Norwegian Forest cat that presented with a history of lameness which had not improved with conservative treatment. During medial arthrotomy, avulsion of the cranial cruciate ligament from the caudomedial aspect of the lateral femoral condyle was suspected and the torn portion resected. A modified Maquet technique was performed on the left tibia resulting in a rapid improvement in lameness postoperatively. Histopathology of the resected cranial cruciate ligament confirmed avulsion. To the authors' knowledge this is the first reported use of this technique in the cat, and the first of stifle instability due to cranial cruciate ligament avulsion from the femur in the cat., (© 2013 British Small Animal Veterinary Association.)

Objective: To determine short- and long-term rates of successful outcomes of surgical and nonsurgical treatments for overweight dogs with cranial cruciate ligament rupture (CCLR)., Design: Prospective, randomized, clinical trial. Animals-40 client-owned overweight dogs with unilateral CCLR., Procedures: Dogs were randomly assigned to nonsurgical (physical therapy, weight loss, and NSAID administration) or surgical (tibial plateau leveling osteotomy) treatment groups; dogs in both groups received the same nonsurgical treatments. Dogs were evaluated immediately before and 6, 12, 24, and 52 weeks after initiation of treatments via owner questionnaires, gait analysis, and dual-energy x-ray absorptiometry. A successful outcome was defined as an affected limb net ground reaction force > 85% of the value for healthy dogs and a ≥ 10% improvement in values of questionnaire variables., Results: Owner questionnaire responses indicated dogs in both groups improved during the study, but dogs in the surgical treatment group seemed to have greater improvement. Body fat percentages for dogs in both treatment groups significantly decreased during the study. Surgical treatment group dogs had significantly higher peak vertical force for affected limbs versus nonsurgical treatment group dogs at the 24- and 52-week evaluation times. Surgical treatment group dogs had a higher probability of a successful outcome (67.7%, 92.6%, and 75.0% for 12-, 24-, and 52-week evaluations, respectively) versus nonsurgical treatment group dogs (47.1%, 33.3%, and 63.6% for 12-, 24-, and 52-week evaluations, respectively)., Conclusions and Clinical Relevance: Overweight dogs with CCLR treated via surgical and nonsurgical methods had better outcomes than dogs treated via nonsurgical methods alone. However, almost two-thirds of the dogs in the nonsurgical treatment group had a successful outcome at the 52-week evaluation time.

Background: Magnetic resonance (MR) imaging is the preferred diagnostic tool to evaluate internal disorders of many joints in humans; however, the usefulness of MR imaging in the context of osteoarthritis, and joint disease in general, has yet to be characterized in veterinary medicine. The objective of this study was to assess the diagnostic accuracy of short-duration 3 Tesla MR imaging for the evaluation of cranial and caudal cruciate ligament, meniscal and cartilage damage, as well as the degree of osteoarthritis, in dogs affected by non-traumatic, naturally-occurring cranial cruciate ligament rupture (CCLR). Diagnoses made from MR images were compared to those made during surgical exploration. Twenty-one client-owned dogs were included in this study, and one experienced evaluator assessed all images., Results: All cranial cruciate ligaments were correctly identified as ruptured. With one exception, all caudal cruciate ligaments were correctly identified as intact. High sensitivities and specificities were obtained when diagnosing meniscal rupture. MR images revealed additional subclinical lesions in both the cranial and caudal cruciate ligaments and in the menisci. There was a "clear" statistical (kappa) agreement between the MR and the surgical findings for both cartilage damage and degree of osteoarthritis. However, the large 95% confidence intervals indicated that evaluation of cartilage damage and of degree of osteoarthritis is not clinically satisfactory., Conclusions: The presence of cruciate ligament damage and meniscal tears could be accurately assessed using the MR images obtained with our protocol. However, in the case of meniscal evaluation, occasional misdiagnosis did occur. The presence of cartilage damage and the degree of osteoarthritis could not be properly evaluated.

This retrospective study evaluated the incidence of meniscal injury in cats with cranial cruciate ligament (CCL) ruptures. Medical records for cats diagnosed with CCL ruptures treated by a lateral fabellotibial suture (LFS) were reviewed for signalment, history, physical examination and surgical findings. Ninety-five cats (98 stifles) met the inclusion criteria. The incidence of meniscal injuries in feline CCL deficient stifles was 67%. Isolated medial meniscal injuries were found in 55 stifles (56%), isolated lateral meniscal injuries were found in 5 stifles (5%), and lateral and medial meniscal injuries were found in 6 stifles (6%). There was no correlation between the presence of a meniscal injury and age, breed, sex, weight, duration of lameness, presence of concurrent medial patellar luxation, degree of degenerative joint disease, or presenting side of lameness. Given the high rate of meniscal pathology in cats with CCL ruptures, exploratory surgery for meniscal assessment and concurrent stifle stabilization should be considered in feline patients.

Objective: To (1) discover kinematic variables that differ between dogs with cranial cruciate ligament rupture (CCLR) and control dogs and (2) to identify suitable outcome variables for longitudinal studies on the effects of surgical interventions for CCLR in dogs., Study Design: In vivo case-control comparison., Animals: Dogs with unilateral CCLR (n=16), and no other detectable neurologic or orthopedic disease and 10 dogs without CCLR, neurologic, or orthopedic disease., Methods: Kinematic data was collected from dogs as they walked at constant speed on a treadmill, using an infrared camera system and adhesive reflective markers applied to the pelvic limbs. Data on 5 selected variables was extracted and comparisons made between paired pelvic limbs in both CCLR and control dogs and between control and CCLR dogs., Results: Comparisons in CCLR dogs revealed significant differences between affected and unaffected limbs for many examined variables; the largest differences were in paw velocity and stifle angular velocity. There were highly significant differences between CCLR and control dogs when examining paired limb ratios for 4 of the variables, the largest differences were in stride length and paw velocity., Conclusions: Kinematic analysis provides straightforward and objective methods for defining the lameness associated with CCLR in dogs. Paw velocity and stride length were most notably reliable and not susceptible to systematic alterations in stifle joint dynamics that might be associated with specific surgical procedures., Clinical Relevance: This study identifies several variables that can provide the objective measurements essential to evaluate the efficacy of surgical interventions for CCLR in dogs.

Objective: To determine fluid retention, glomerular filtration rate, and urine output in dogs anesthetized for a surgical orthopedic procedure., Animals: 23 dogs treated with a tibial plateau leveling osteotomy., Procedures: 12 dogs were used as a control group. Cardiac output was measured in 5 dogs, and 6 dogs received carprofen for at least 14 days. Dogs received oxymorphone, atropine, propofol, and isoflurane for anesthesia (duration, 4 hours). Urine and blood samples were obtained for analysis every 30 minutes. Lactated Ringer's solution was administered at 10 mL/kg/h. Urine output was measured and glomerular filtration rate was estimated. Fluid retention was measured by use of body weight, fluid balance, and bioimpedance spectroscopy., Results: No difference was found among control, cardiac output, or carprofen groups, so data were combined. Median urine output and glomerular filtration rate were 0.46 mL/kg/h and 1.84 mL/kg/min. Dogs retained a large amount of fluids during anesthesia, as indicated by increased body weight, positive fluid balance, increased total body water volume, and increased extracellular fluid volume. The PCV, total protein concentration, and esophageal temperature decreased in a linear manner., Conclusions and Clinical Relevance: Dogs anesthetized for a tibial plateau leveling osteotomy retained a large amount of fluids, had low urinary output, and had decreased PCV, total protein concentration, and esophageal temperature. Evaluation of urine output alone in anesthetized dogs may not be an adequate indicator of fluid balance.

Objective: To evaluate the incidence of and potential risk factors associated with development of postoperative infection-inflammation in a large number of dogs with rupture of the cranial cruciate ligament (CCL) that were treated via elective surgery., Design: Retrospective case series., Animals: 808 dogs that underwent surgery (902 procedures) for rupture of the CCL., Procedures: Medical records of dogs that underwent extracapsular lateral suture (ECLS) stabilization or tibial plateau leveling osteotomy (TPLO) between January 1, 2005, and December 31, 2006, were reviewed. Data regarding development of postoperative infection-inflammation were obtained. Potential risk factors were identified and recorded., Results: 496 ECLS surgeries were performed, and 406 TPLO surgeries were performed. Infection-inflammation developed in 55 of 902 (6.1%) surgeries within 6 months after surgery. There was a significant difference in infection-inflammation rate after the ECLS surgeries (21/496 [4.2%]), compared with rate after the TPLO surgeries (34/406 [8.4%]). Factors associated with a significantly lower rate of infection-inflammation included the use of suture material other than stainless-steel staples for skin closure and postoperative oral administration of antimicrobials., Conclusions and Clinical Relevance: TPLO was associated with a significantly higher rate of infection-inflammation than the infection-inflammation rate after ECLS stabilization. The use of suture material other than staples for skin closure and postoperative oral administration of antimicrobials may be protective in minimizing infection-inflammation in dogs with rupture of the CCL that are treated via ECLS or TPLO.

Abnormal patterns of cell death, including increased apoptosis, can influence homeostasis of ligaments and could be involved in the pathogenesis of cranial cruciate ligament (CCL) rupture. Increased nitric oxide (NO) production has been implicated as a stimulus to increased apoptosis in articular cartilage. This study investigated apoptotic cell death in ruptured canine CCL (CCL group, n = 15), in ruptured CCL of dogs treated with oral L-N6-(1-iminoethyl)-lysine (L-NIL), a selective NO-synthetase(NOS)-inhibitor, (L-NIL group, n = 15) and compared the results with normal canine CCL (control group, n = 10). Orally administered L-NIL at a dosage of 25mg/m2 of body surface area was effective in inhibiting NO production in the articular cartilage of dogs in the L-NIL group, but it did not significantly influence the increased quantity of apoptotic cells found in ruptured CCL specimens. The results of this study suggest that apoptosis of ligamentocytes in the canine CCL is not primarily influenced by increased NO production within the stifle joint.

The objective of this study was to investigate if cellular reactivity to collagen type I exists in dogs with unilateral cranial cruciate ligament (CrCL) rupture and if it relates to disease progression. The patient group consisted of 10 dogs with unilateral CrCL rupture. The control dogs consisted of three healthy control dogs, and two healthy dogs with unilateral sham operations of the stifle joint. All dogs were assayed repeatedly every 6 months for 12-24 months. Peripheral blood mononuclear cells were isolated from whole blood and were cultured with human collagen type I at concentrations of 5, 20 and 40 microg/ml for 6 and 7 days. Lymphocyte reactivity to collagen type I occurred not only in dogs with CrCL rupture, but also in sham-operated dogs and healthy dogs. Five of the eight assays (63%) performed at the time of operation or at the time of diagnosis of CrCL rupture had a stimulation index (SI) >or=3.0. This was not significantly different compared to healthy control dogs, not to the sham-operated control dogs. The CrCL rupture was assessed intraoperatively in six cases. Three cases had partial rupture and three had complete rupture. Only one dog with partial rupture, and two dogs with complete rupture had a positive SI. An increase in proliferation to collagen type I was seen in dogs with CrCL rupture, whereas it either remained stable or decreased in the control dogs. No distinct pattern in lymphocyte reactivity to collagen type I could be established from the dogs that sustained a CrCL rupture in the contralateral stifle joint, although most dogs that did not sustain a CrCL rupture in the contralateral stifle joint remained negative during this study with exception of one dog. Further research is required to determine whether cellular reactivity to collagen type I may play an initiating role in cruciate degradation.

Objective: To evaluate anticollagen type I antibodies in synovial fluid of the affected stifle joint, the contralateral stifle joint, and the left shoulder joint of dogs with unilateral cranial cruciate ligament (CrCL) rupture during an extended period of 12 to 18 months., Animals: 13 client-owned dogs with CrCL rupture and 2 sham-operated dogs., Procedures: All dogs were examined and arthrocentesis of all 3 joints was performed every 6 months after surgery. Synovial fluid samples were tested for anticollagen type I antibodies by use of an ELISA., Results: Dogs with partial CrCL rupture had higher antibody titers than dogs with complete rupture. Six of 13 dogs ruptured the contralateral CrCL during the study, whereby higher antibody titers were found for the stifle joints than for the shoulder joint. Seronegative dogs or dogs with extremely low antibody titers and 2 dogs with high antibody titers did not sustain a CrCL rupture in the contralateral stifle joint., Conclusions and Clinical Relevance: In most dogs that had a CrCL rupture of the contralateral stifle joint, a distinct antibody titer gradient toward the stifle joints was detected, suggesting that there was a local inflammatory process in these joints. However, only a small number of sham-operated dogs were used to calculate the cutoff values used to determine the anticollagen type I antibody titers in these patients. Synovial fluid antibodies against collagen type I alone do not initiate CrCL rupture because not all dogs with high antibody titers sustained a CrCL rupture in the contralateral stifle joint.

Objective: To review the gross, microscopic, and functional anatomy of the cranial cruciate ligament (CCL) in dogs., Study Design: Literature review., Methods: Reports of the anatomy and function of the cruciate ligaments in dogs were retrieved by search of the 1975-2005 PubMed database., Results: The CCL has an important biomechanical function resisting cranial drawer, hyperextension, and internal rotation and acts to fine tune and guide the stifle through its rolling and sliding motion. It has a complex architecture, and distinct geographic regions within the ligament have different functional roles depending on the angle and loading conditions. Collagen type I is the main component of the extracellular matrix; the fibrils have a crimped structure. The cruciate ligaments are almost completely covered by synovium, protecting them from synovial fluid. Cruciate blood supply is mainly of soft tissue origin. The intraligamentous network is relatively limited whereas the core of the middle third of the CCL is even less well vascularized. Neurohistologic studies are very limited in the dog. Various mechanoreceptors and proprioceptive receptors have been identified within the substance of the cruciate ligaments., Conclusions: CCL structural characteristics play an important part in its complex behaviour with the crimped pattern of the collagen fibrils being an important determinant of its biomechanical properties. In contrast to reports of managing CCL rupture, there are few reports describing the microanatomy and neurovascular morphology of the cruciate ligaments., Clinical Relevance: Cruciate disease is likely multi-factorial. Improved understanding of CCL degradation leading to CCL rupture is critical to development of new diagnostic tests for cruciate disease in dogs. Appropriate intervention during the early stages of disease process might preserve CCL structural properties by preventing further collagen degradation. Accurate knowledge of functional and fiber bundle anatomy is imperative for reconstruction and restoration of normal stifle joint physiology. Reconstructive goals should alleviate existing instability and mimic normal kinematics. Knowledge of the exact function of the CCL in the neuromuscular control around the stifle joint could possibly explain osteoarthritis progression after CCL damage.

Cruciate disease is a common cause of chronic lameness in dogs. Midsubstance rupture of the cranial cruciate ligament (CCL) arises from progressive pathological failure, often under conditions of normal loading in adult dogs with CCL instability. A high risk of rupture is associated with inflammation of the synovium and adaptive or degenerative changes in the cells and matrix of the CCL. In contrast, CCL rupture in puppies is usually associated with traumatic injury and avulsion of the CCL from its sites of attachment.

Objectives: To investigate changes in concentrations of insulin-like growth factors I (IGF-I) and II (IGF-II) and the expression of IGF-binding proteins (IGFBP) in synovial fluids from dogs with naturally occurring osteoarthritis (OA) of the canine stifle joint secondary to cranial cruciate ligament (CCL) rupture., Study Design: Prospective study with synovial fluid sampling from diseased and contralateral unaffected joints at 0, 1.5, and 5 months., Sample Population: Eleven dogs with unilateral CCL deficiency, with unaffected contralateral joints., Methods: IGF-I and IGF-II concentrations in synovial fluids were estimated by radioimmunoassay at 0, 1.5, and 5 months; Western ligand blotting was performed for intact IGFBPs at 0, 1.5, 5, and 9 months. Both stifle joints were radiographed at 0, 7, and 13 months., Results: The IGF system is altered after CCL rupture and during development of early OA. Mean IGF-I and IGF-II concentrations in index stifle joints at study entry were 201.6 microg/mL and 345.7 microg/mL, respectively, compared with 57.7 microg/mL and 79.4 microg/mL, respectively, for contralateral joints. Index joint IGF concentrations increased after surgical treatment and then declined, although they remained higher than contralateral joints. Index joints had increases in IGFBP-3 and -4, and a decrease in IGFBP-2 expression compared with contralateral joints., Conclusions: Although IGF concentrations are increased in canine OA, alterations in IGFBP profiles may limit the tissue availability of IGF., Clinical Relevance: Manipulation of the IGF system may provide an opportunity for novel treatments of OA in dogs., (Copyright 2003 by The American College of Veterinary Surgeons)

Objective: To measure and compare synovial fluid antibody titers to type-I and -II collagen in stifle joints with instability caused by complete or partial cranial cruciate ligament (CCL) rupture and joints with osteoarthrosis secondary to other pathologic changes in dogs., Animals: 82 dogs with diseased stifle joints., Procedure: Synovial fluid samples were collected from 7 dogs with clinically normal stifles (control group) and 82 dogs with diseased joints (50 stifle joints with complete rupture of the CCL, 20 with partial damage of the CCL, and 12 joints with radiographic signs of osteoarthritis secondary to other arthropathies). Synovial fluid samples were tested for autoantibodies to type-I and -II collagen by an ELISA., Results: In dogs with complete and partial CCL rupture, synovial fluid antibody titers to type-I and -II collagen were significantly increased, compared with control dogs. Forty-eight percent (24/50) of samples from dogs with complete CCL rupture and 35% (7/20) of samples from dogs with partial CCL rupture had antibody titers to type-I collagen that were greater than the mean plus 2 standard deviations of the control group titers. Synovial fluid antibody titers to type-II collagen were high in 40% of the dogs with partial or (8/20) complete (20/50) CCL rupture. Dogs with osteoarthrosis secondary to other pathologic changes had significantly increased synovial fluid antibodies to type-I and -II collagen, compared with control dogs., Conclusion: Increases in autoantibodies to collagen in synovial fluid are not specific for the type of joint disorder. It is unlikely that the anticollagen antibodies play an active role in the initiation of weakening of the CCL.