Hamstring graft technique for stabilization of canine cranial cruciate ligament deficient stifles

OBJECTIVE: To investigate the harvest and application of hamstring grafts for canine cranial cruciate ligament (CrCL) reconstruction. STUDY DESIGN: Experimental study. ANIMALS: Four adult female hounds, weighing 26.3 +/- 1.6 kg (mean +/- SEM). METHODS-One stifle in each dog was randomly chosen for hamstring graft CrCL reconstruction after native CrCL transection. Arthroscopy was performed to evaluate graft integrity at 12 weeks. Gait analysis and stifle radiographs were performed preoperatively and up to 52 weeks after graft placement. Dogs were killed 12 (n = 2) or 52 weeks (n = 2) after CrCL reconstruction. Tissues were evaluated grossly and with light and confocal laser microscopy. RESULTS: Hamstring grafts were intact in all stifles at 12 weeks (n = 4) and 52 weeks (n = 2). Grossly, there was no osteoarthritis in stifles at 12 weeks and only chondrophytes along the trochlear ridges at 52 weeks. Minimal radiographic evidence of osteoarthritis developed in stifles with grafts during the study. Lameness in limbs with grafts resolved by 52 weeks. Graft tissue was highly vascular, ligamentized, and undergoing active remodeling at 12 weeks. Fifty-two weeks after graft placement, intraarticular graft tissue was well vascularized, mature, and encapsulated by synovium, and graft-bone interfaces were characterized by Sharpey's fiber insertions. There was no evidence of graft necrosis using confocal laser microscopy at either time point. CONCLUSIONS: The hamstring graft technique may be a viable method of canine CrCL reconstruction. CLINICAL RELEVANCE: Hamstring grafts may be an alternative technique for canine CrCL reconstruction. Further study is needed before clinical application.     

Vascular distribution in ruptured canine cranial cruciate ligament

Objective: To (1) determine the microanatomic vascular distribution in ruptured canine cranial cruciate ligaments (CCL) using specific vascular immunohistochemical techniques, and (2) compare vessel density between ruptured and intact canine CCL and between different areas of interest in ruptured CCL using histomorphometric analysis. Study Design: In vitro study. Animals: Dogs (n=41) admitted for surgical treatment of ruptured CCL and 19 dogs euthanatized for nonorthopedic conditions. Methods: Diseased (variable CCL rupture) and intact (normal control) CCL were processed for immunohistochemical staining specific to vessels (factor VIII, laminin). Mean vascular density was assessed and compared in areas of interest (torn end versus remaining core regions of CCL, proximal femoral versus distal tibial core CCL regions). Results: Ruptured CCL was more vascular than intact CCL; however there was no difference in vascular density between the torn end and the remaining core area of the ruptured CCL. Ruptured CCL was vascularized to a greater degree at the proximal portion than the distal portion of the CCL. Partially ruptured CCLs had a higher vessel density than completely ruptured CCLs. Conclusions: Vascular density is increased in diseased CCL compared with intact CCL. It remains to be determined whether this finding is associated with the cause of CCL rupture or is a result of CCL degeneration and rupture.     

Histologic changes in ruptured canine cranial cruciate ligament

OBJECTIVES: To determine changes to the cells and collagenous and amorphous extracellular matrix (ECM) structure in ruptured canine cranial cruciate ligaments (CCL). STUDY DESIGN: Prospective clinical study. ANIMALS: CCL specimens obtained from 29 dogs with ruptured CCL and 6 young dogs with intact CCL. METHODS: Ligament fibroblast number density and phenotype were determined in the core and epiligamentous regions. ECM birefringence and crimp structure in the core region were also studied. RESULTS: Loss of fibroblasts from the core region of ruptured CCL was seen (P <.001), whereas, in the epiligamentous region, cell number densities were similar in ruptured and intact CCL (P =.7). In ruptured CCL, numbers of typical ligament fibroblasts (fusiform and ovoid cells) were decreased, and numbers of cells exhibiting chondroid transformation (spheroid cells) were increased in the core region (P <.001). Expansion of the volume of the epiligamentous region was also seen, although bridging scar tissue was not seen between the ends of ruptured CCL. The structure of the ECM collagen in the core region was extensively disrupted in ruptured CCL. This was, in part, because of decreased birefringence and elongation of the crimp in the remaining collagen fibers when compared with intact CCL (P <.01). CONCLUSIONS: Extensive alterations to the cell populations and collagenous ECM structure were seen in ruptured CCL. Although a proliferative epiligamentous repair response was seen in ruptured CCL, there was a lack of any bridging scar between the ruptured ends of the CCL. CLINICAL RELEVANCE: The cellular and ECM changes in ruptured CCL that we have described appear to result from the cumulative effects of remodeling and adaptation to mechanical loading and microinjury. Treatment of early cruciate disease in dogs will need to inhibit or reverse these progressive changes to CCL tissue, which are directly associated with partial or complete structural failure of the CCL under conditions of normal activity.     

Collagen fragmentation in ruptured canine cranial cruciate ligament explants

Collagen fragmentation in cranial cruciate ligament (CCL) explants and stifle synovial fluid was investigated in dogs with ruptured and intact CCL. Cathepsin K and tartrate-resistant acid phosphatase (TRAP) activities were determined in CCL explant supernatants. Formation of collagen fragments was determined in explant supernatants and stifle synovial fluid. Cathepsin K(+) and TRAP(+) cells were stained specifically in histological sections of CCL. Formation of telopeptide collagen fragments was increased in ruptured CCL explants and stifle synovial fluid from dogs with ruptured CCL. In ruptured CCL explants, release of collagen fragments was associated with extracellular release of TRAP and the presence of cathepsin K(+) cells within CCL tissue. Cathepsin K(+) and TRAP(+) cells were only seen in ruptured CCL. It was concluded that infiltration of the CCL with TRAP(+) cells in dogs with CCL rupture is associated with increased collagenolysis. It is hypothesized that recruitment and activation of TRAP(+) mononuclear cells within the synovium and CCL precipitates CCL rupture through upregulation of collagenolytic enzymes and collagen degradation.     

Isometry of potential suture attachment sites for the cranial cruciate ligament deficient canine stifle.

For a suture that spans a joint to provide support without limiting range of motion, its attachment points on either side of the joint must remain the same distance from each other from full extension to full flexion. The effect of location of the tibial crest attachment for a fabello-tibial crest suture was studied in seven canine cadaveric stifles. The distance from a fabella marker to each of 11 tibial markers was determined from radiographs of each limb, as it progressed from 150 degrees to 130 degrees , 105 degrees , 90 degrees , 65 degrees and 45 degrees of flexion. The marker locations that were more proximal and cranial on the tibial crest had the least percent change in distance. The effect of anchoring the suture to the femur at a site other than the fabella was investigated using the same radiographs. Five marks were placed in a grid on the caudal portion of the femoral condyle and supracondylar region. The mean percent change in length from each femoral point to the five more proximal and cranial tibial markers was determined. The least change in length occurred for those femoral points located close to the origin of the cranial cruciate ligament. Locations more proximal or cranial resulted in large changes in length, particularly when matched with less ideal tibial locations. Although this study does not directly examine length changes in sutures, it demonstrates that there are some locations for the origin and insertion of an extracapsular suture that are associated with less length change than others, and also forms the basis for future investigations.     

System behavior of commonly used cranial cruciate ligament reconstruction autografts

Biomechanical analysis was performed on the cranial cruciate ligament (CCL) and three autogenous tissues used for CCL reconstruction in the canine stifle. The autogenous tissues were patellar ligament-based autografts described for over-the-top CCL replacement and included the central one third of the patellar ligament, the medial one third of the patellar ligament, and the lateral one third of the patellar ligament with fascia lata. Tension testing produced abrupt failure of the central and medial autografts but sequential failure of the lateral autograft. Structural properties were determined for the overload condition and within the load range of normal activity for the CCL (physiologic range). None of the autograft systems approached the stiffness, maximum load, and energy absorbed to maximum load of the CCL. The central and lateral autografts were stiffer, had greater maximum loads, and absorbed more energy to maximum load than the medial autograft. The central and lateral autografts had an elastic range, as defined by proportional limit, which corresponded to the physiologic range of loading for the CCL. Loads that corresponded to physiologic displacement of the lateral and central autografts were near the maximum load of the fixation site, which underscored the need for postoperative support of the repaired stifle.     

Experimental cranial cruciate replacement in cattle using a patellar ligament graft

The cranial cruciate ligament was surgically removed from the right stifle joint in ten heavy steers and two bulls, and replaced with a tendon-ligament graft harvested from the tendon of the gluteobiceps muscle including a portion of the lateral patellar ligament. Two surgical techniques (placing the graft through a femoral bone tunnel and placing the graft through the joint space) were compared using six animals in each group.

Both surgical techniques were easily performed and caused minimal postoperative inflammation. The clinical response observed over four to five months was considered satisfactory in 9 of 12 animals. However, the tensile strength of the graft determined at necropsy was less than the cranial cruciate ligament in the opposite normal stifle in all animals tested.

     

Proximal tibial intraarticular ostectomy for treatment of canine cranial cruciate ligament injury

OBJECTIVE: To report a technique for surgical alteration of the slope of the tibial plateau by a proximal tibial intraarticular ostectomy (PTIO) after injury to the canine cranial cruciate ligament (CCL) and to determine the outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Dogs (n=52) with CCL injury in 60 stifle joints. METHODS: CCL injury was treated by lateral stifle arthrotomy, removal of CCL remnants, and appropriate meniscal surgery. PTIO was performed to remove a wedge of bone from the proximal aspect of the tibia. The ostectomy site was reduced and stabilized using a bone plate and screws applied to the medial surface of the tibia as well as a craniocaudal positional screw. Dogs were evaluated at 6 weeks, 6, and 12 months by complication assessment, lameness scores, stifle range of motion (ROM), thigh circumference, radiographic assessment, degenerative joint disease (DJD) scores, and surgeon and owner evaluation of function. RESULTS: Lameness scores improved by 6 and 12 months in all but 1 dog. Thigh circumference and DJD were increased at 6 and 12 months. Complications occurred in 20% of dogs with all but 1 occurring perioperatively or within 6 weeks; most common were injury to the long digital extensor tendon (4 dogs) and plate failure (3); 2 other dogs required surgery to treat complications. Most owners (98%) reported that lameness had improved by 12 months; 90% were extremely or very satisfied with the procedure and 90% would have the same procedure performed on another dog. CONCLUSION: PTIO to level the tibial plateau provided a satisfactory clinical outcome in dogs >20 kg with CCL injury and the complication rate was similar to tibial plateau levelling osteotomy (TPLO). Stifle osteoarthritis continued to progress radiographically. CLINICAL RELEVANCE: PTIO represents an alternative to TPLO that does not require specialized surgical equipment.     

Preliminary study evaluating tests used to diagnose canine cranial cruciate ligament failure

O bjective : To estimate specificity, sensitivity, positive predictive value and negative predictive value of tests and signs used for the diagnosis of cranial cruciate ligament failure in dogs.
M ethods : One stifle in each of 42 dogs was examined: 25 "affected" and 17 "control" dogs. All dogs were subjected to the following tests when conscious: cranial drawer, tibial compression, patellar tendon palpation and palpation of the medial aspect of the joint. Under general anaesthesia, cranial drawer and tibial compression tests were repeated and a lateral stifle radiograph was taken to evaluate changes of the infrapatellar fat pad. The results were analysed using a 2×2 table method. Sensitivity, specificity, positive predictive value and negative predictive value were estimated.
R esults : The sensitivity of the cranial drawer and tibial compression tests was surprisingly low when performed on conscious patients but significantly better when performed under anaesthesia. Similarly, palpation of the medial aspect of the stifle joint cannot be considered a reliable indicator of cranial cruciate ligament injury. Patellar palpation and radiographic assessment showed excellent sensitivity, specificity, positive predictive value and negative predictive value.
C linical S ignificance : In the diagnosis of cranial cruciate ligament, it is essential that the clinician is aware of each test's features and limitations to reduce the risk of misdiagnosis.     

Morphology, histology and functional anatomy of the canine cranial cruciate ligament

Morphologically the canine cranial cruciate ligament can be divided into a cranio-medial and caudo-lateral component which perform reciprocal functions at all angles of flexion of the stifle joint. Histologically the main constituents of these two components are bundles of longitudinally orientated collagen fibre. The results of the study of the effect of partial and total sectioning of the cranial cruciate ligament on the "anterior-draw" movement implied that the relatively minor degree of movement, elicited following sectioning of either of the components of the ligament, would not be detected under clinical conditions. For joint instability to be clinically detectable most of the ligament must have ruptured, or the intact portion must have undergone degenerative or disruptive changes.     

Immunohistochemical and histomorphometric evaluation of vascular distribution in intact canine cranial cruciate ligament

Objectives: To (1) describe vascular distribution in the grossly intact canine cranial cruciate ligament (CCL) using immunohistochemical techniques specific to 2 components of blood vessels (factor VIII for endothelial cells, laminin for basement membrane); and (2) compare the vascularity in different areas of interest (craniomedial versus caudolateral bands; core versus epiligamentous regions; and proximal versus middle versus distal portions) in the intact normal canine CCL. Study Design: In vitro study. Animals: Large, mature dogs (n=7) of breeds prone to CCL disease that were euthanatized for nonorthopedic conditions. Methods: Intact CCL were collected from fresh canine cadavers free from stifle pathology. CCL tissue was processed for immunohistochemistry and stained for factor VIII and laminin. Vascular density was determined by histomorphometric analysis. Results: Specific vascular staining was sparsely identified throughout the CCL; however, the proximal portion of the CCL appears to have a greater number of vessels than the middle or distal portion of the ligament. Conclusions: The CCL is a hypovascular tissue and its vascular distribution is not homogeneous.     

Evaluation of a canine cranial cruciate ligament repair system for use in equine laryngoplasty

OBJECTIVE: To report the use of a nylon suture system (Canine Cranial Cruciate Ligament Repair System; Securos Inc Veterinary Orthopedics) as a prosthesis for equine laryngoplasty. STUDY DESIGN: Experimental and prospective clinical study. ANIMALS: Cadaver specimens (n = 5) and 7 horses with left laryngeal hemiplegia. METHODS: A commercially available monofilament nylon suture system was implanted as a laryngeal prosthesis. Arytenoid cartilage abduction was achieved with a tensioning device applied to the suture prosthesis during transnasal endoscopic observation. Suture fixation was achieved with crimping clamps and a crimping device. RESULTS: The nylon suture system was suitable as a laryngeal prosthesis for arytenoid cartilage abduction. The ratchet mechanism of the tensioning device facilitated abduction of the arytenoid cartilage and suture fixation was achieved by the crimped clamp without any loss of tension. Postoperatively, there was a slight loss of tension in 4 horses and complete loss of tension in 1 horse because of cartilage failure. After convalescence, none of the horses had abnormal respiratory noise, exercise intolerance or cough. CONCLUSIONS: A nylon suture system designed for canine cranial cruciate ligament repair was used successfully as a laryngeal prosthesis and facilitated control of the degree of arytenoid cartilage abduction during laryngoplasty. CLINICAL RELEVANCE: For improved control of the degree of arytenoid cartilage abduction during laryngoplasty, use of a nylon suture system with metal crimps should be considered.     

Effect of signalment on the presentation of canine patients suffering from cranial cruciate ligament disease

Objective : To determine the effect of signalment on the incidence and presentation of patients suffering from cranial cruciate ligament disease. Methods : Data relating to 426 dogs (44 breeds) that met specific selection criteria were obtained from the hospital archive (2002 to 2008). Cases were followed up for 2 years. Results : The breeds most commonly presented with cranial cruciate ligament disease were Labrador retriever (16%), Rottweiler (15%), golden retriever (12%) and boxer (9%). Rottweilers were significantly more likely (69%; P=0·05) to develop and present with (50%; P=0·03) bilateral cranial cruciate ligament disease. Rottweilers presenting with cranial cruciate ligament disease were significantly younger (median 977 days; P<0·0001) than other breeds; golden retrievers being significantly older at presentation (median 1994 days; P=0·004). Neither sex nor neutered status significantly affected the incidence of developing (P=0·77 and P=0·30, respectively) or presenting with (P=0·62 and P=0·35, respectively) bilateral cranial cruciate ligament disease. Entire dogs were significantly younger than neutered dogs at presentation (P=0·0004). Entire female dogs presented significantly younger than neutered females (P=0·0002), entire males (P=0·01) and neutered males (P=0·0001). Clinical Significance : Breed affects the incidence of developing and presenting with bilateral cranial cruciate ligament disease. Breed and sex both affect the age that patients present with cranial cruciate ligament disease.     

Osteophyte formation in the canine stifle joint following treatment for rupture of the cranial cruciate ligament

A clinical and radiological study of osteophyte formation following surgical or conservative treatment for rupture of the cranial cruciate ligament (C.C.L.), was carried out in thirty-eight dogs. Osteophyte formation had occurred in all of the affected stifle joints, in the period between treatment and the re-examination, irrespective of the method of treatment. In general, the degree of formation was less than that which had occurred before treatment. In the larger and more obese dogs, osteophyte formation was more extensive. The degree of lameness did not appear to be related to the degree of osteophyte formation radiographically evident at re-examination. No direct correlation could be established between the degree of joint instability, assessed at the re-examination, the degree of osteophyte formation following treatment, or the function of the limb.     

Synovial membrane changes after experimental transection of the cranial cruciate ligament in dogs

Degenerative joint disease and inflammation of the synovial membrane were produced in the left stifle of 16 dogs by severing the cranial cruciate ligament. Arthrotomy only was performed on the right stifle. Synovial membrane from these joints was histologically examined at 1, 2, 8, and 13 weeks after surgical operation. Similar tissue was obtained from 4 healthy dogs for comparison. Inflammatory changes in the synovium of the left stifle progressed with time and were prominent at 8 weeks postoperatively; subsynovial fibrosis was greatest at 13 weeks. Inflammation of the synovial membrane and subsynovial tissue was characterized by synovial cell hypertrophy and hyperplasia, plasma cell and lymphocyte infiltration, and increased vascularization of the subsynovial region.     

Use of compression stress radiography for the detection of partial tears of the canine cranial cruciate ligament

Twenty-three cases of partial rupture of the cranial cruciate ligament (CCL) were reviewed. All of these patients were evaluated for clinical and radiographic signs of instability. Nine cases showed a negative drawer sign on manual assessment. A positive radiographic tibial compression test was obtained for all stifle joints with a partially ruptured cruciate. In 13 cases, the site of injury and the appearance of the torn ends were evaluated. The final diagnosis of partial CCL rupture was made by direct visualisation and probing of the CCL during arthrotomy (22 cases) or arthroscopy (one case).     

Nitric oxide and metalloproteinases in canine articular ligaments: a comparison between the cranial cruciate, the medial genual collateral and the femoral head ligament

Osteoarthritis due to cranial cruciate ligament (CCL) rupture or hip dysplasia is one of the most important causes of chronic lameness in dogs. This study aimed at comparing nitric oxide (NO) production by the CCL with that of the femoral head ligament (FHL) and the medial collateral ligament (MCL), and investigating the pathway of NO production and the concomitant metalloproteinase (MMP) activity in the presence or absence of an inflammatory stimulus. Ligaments of normal dogs were subjected to different stimuli, and NO and MMP activity from explant culture supernatants were compared. The results showed that in explant cultures of the canine CCL more NO was produced than in those of the other two ligaments. A higher level of NO was produced when CCLs were exposed to the inducible nitric oxide synthase (iNOS)-inducing cocktail TNF/IL-1/LPS, and NO synthesis could be inhibited by both l-NMMA, a general nitric oxide synthase (NOS) inhibitor and l-NIL, a specific iNOS inhibitor. However, a correlation between NO synthesis and iNOS expression levels as determined by immunohistochemistry was not observed. In contrast to CCL, no evidence for iNOS-dependent NO synthesis was observed for MCL and FHL. The CCL produced less MMP than MCL and FHL, and no correlation between MMP and NO could be demonstrated. MMP activity in the CCL increased significantly after 48 h of incubation with the inflammatory stimulus. The results suggest that in canine osteoarthritis NO synthesized by canine CCL plays a more important role in the pathogenesis of osteoarthritis of the stifle than that synthesized by FHL and MCL.