Relationship of tibial plateau slope to limb function in dogs treated with a lateral suture technique for stabilization of cranial cruciate ligament deficient stifles

OBJECTIVE: To evaluate the effect of a lateral suture technique (LST) on tibial plateau angle (TPA) measurement and to compare TPA with functional outcome in dogs treated for cranial cruciate ligament (CrCL) rupture with LST. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Dogs (n=34) with unilateral CrCL instability. METHODS: All dogs had lameness examination, survey stifle radiographs, and force plate analysis before and at 6, 12, 24, and 48 weeks after surgery. Radiographic osteoarthritis (OA) scores and lameness scores were assigned using previously reported methods. Preoperative radiographs were performed in all dogs, and postoperative serial radiographs were performed in 6 dogs for measurement of TPA. Differences in TPA measurements were evaluated with a random effects repeated measures model. The significance of LST on TPA measurement was established in 6 dogs and the effect of TPA on vertical impulse, peak vertical force, progression of radiographic scores, and lameness score were analyzed by general linear models in all dogs. Differences were considered significant if P<.05. RESULTS: Significant differences were not noted between pre- and serial postoperative measurements of TPA. A significant correlation was not established between TPA and postoperative vertical impulse, peak vertical force, lameness score, or radiographic OA scores. CONCLUSIONS: TPA values were unchanged after LST and TPA does not affect outcome measures in dogs treated with LST. CLINICAL RELEVANCE: TPA has no predictive value on clinical outcome in dogs treated with LST for stabilization of CrCL deficient stifles.     

Meniscal injury following initial cranial cruciate ligament stabilization surgery in 26 dogs (29 stifles)

OBJECTIVE: To describe clinical signs, arthroscopic findings, and outcome in a group of dogs undergoing second look arthroscopy for the treatment of meniscal tears following original surgery to correct a CCL deficient stifle joint. METHODS: The medical records of 26 dogs from the Veterinary Teaching Hospital at Texas A&M University and the Veterinary Orthopedic Center (Round Rock, Texas) that had second look arthroscopy for lameness following an original surgical procedure were reviewed. Pre-operative clinical findings, 2nd look arthroscopic findings and owner assessed outcome were documented. RESULTS: Postliminary bucket handle tears of the medial meniscus were detected in 22 (75.9%) cases. Other postliminary meniscal injuries included frayed caudal horn tears of the medial meniscus 6 (20.7%), and longitudinal tears of the lateral meniscus 1 (3.4%). An audible or palpable click was present in 27.6% of cases. An improvement or resolution of lameness was reported in 96.5% of cases reported. In conclusion, tears of the medial meniscus are a significant cause of lameness in dogs subsequent to surgery for cranial crucial ligament ruptures. Increased lameness or acute onset of lameness after surgery for cranial crucial rupture is a consistent finding. In rare cases, a palpable or audible click will be appreciated. Arthroscopic evaluation and partial meniscectomy improve or resolve lameness in the majority of cases. CLINICAL SIGNIFICANCE: Sudden or increased lameness in dogs with historical CCL stabilization surgery should be evaluated and treated arthroscopically for postliminary meniscal injury if another cause for lameness can not be determined.     

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.     

Force plate analyses before and after stabilization of canine stifles for cruciate injury

Ground reaction forces were measured from the hind limbs of 9 dogs before and after stabilization of unilateral cranial cruciate ligament rupture. Before surgery, peak vertical force, associated impulses, and weight distribution were significantly less (multivariate analysis P less than 0.02) in the affected limb, compared with the clinically normal limb. Craniocaudal peak forces and impulses, divided into braking and propulsion, also were significantly less in the affected limb. At a minimum of 7 months after retinacular imbrication, all vertical and craniocaudal measurements in the affected limb were increased significantly. Significant changes were not found in the normal limb. Furthermore, at the postoperative evaluation, there was no significant difference in any measurement between the affected and normal hind limbs. The results indicated restoration of function in the cruciate-deficient limb when compared with the clinically normal hind limb at a walking gait during the study time period.     

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.     

Comparison of tibial plateau angles in normal and cranial cruciate deficient stifles of Labrador retrievers

OBJECTIVE: To investigate tibial plateau angles (TPA) in normal and cranial cruciate ligament (CCL) deficient stifles of Labrador retrievers. STUDY DESIGN: Prospective clinical study. ANIMALS: Eighty-one client-owned purebred Labrador retrievers. METHODS: Lateral radiographs of the tibia were obtained from 2 groups of dogs. Group I (42 dogs) had CCL rupture diagnosed by arthrotomy or arthroscopy. Group II (39 dogs) had no history of orthopedic problems, no radiographic evidence of CCL rupture, and dogs were >8 years of age. The tibial axis and the tibial plateau were determined on the radiographs, and the TPA was measured using image measurement software. The TPA measurement results of groups I and II were compared. RESULTS: Group I (CCL rupture) had a mean TPA (+/-SD) of 23.5 (+/-3.1) degrees, and group II (normal) had a mean TPA (+/-SD) of 23.6 (+/-3.5) degrees. With a P value of.97, no statistical difference was detected between the 2 groups. CONCLUSIONS: No correlation between the magnitude of TPA and CCL rupture was identified in this group of Labrador retrievers. CLINICAL RELEVANCE: In Labrador retrievers, TPA should not be used as a predictor of CCL rupture.     

Computed tomographic evaluation of the canine intercondylar notch in normal and cruciate deficient stifles.

In the human and veterinary orthopaedic literature it has been implied that intercondylar notch stenosis is a mechanical factor in cranial cruciate ligament rupture and intraarticular graft failure. The patients in this study were classified as normal (32), unilateral cruciate rupture (23), or bilateral cruciate rupture (17). The dogs were placed under general anaesthesia and both stifles were scanned via computed tomography (CT) as previously described. Three CT slices at predetermined levels were evaluated within the notch. Measurements included opening notch angle, notch width and height, condyle width, and notch width index (notch width/condyle width) at two different heights within the notch. Intercondylar notch measurements at the most cranial extent were significantly more narrow in unilateral and bilaterally affected stifles when compared to the normal population. Significant differences were noted in the opening notch angle (ONA), notch width index (NWI), NWI at two thirds notch height (NWI2/3), and tibial slope index (TSI). No significant differences were noted between unilateral and bilateral affected stifles. Increased mechanical contact of the cranial cruciate ligament with a stenotic intercondylar notch may predispose the ligament to mechanical wear and structural weakening. Intercondylar notch measurements have been used as a tool to predict the risk of anterior cruciate ligament injury in young human athletes, and to assess the risk factors for intra-articular graft replacements. Our findings may be useful in developing similar predictive models using stifle CT scans.     

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.     

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.

     

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.     

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.     

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.