Use of the proximal portion of the tibia for measurement of the tibial plateau angle in dogs

OBJECTIVE: To determine whether the canine tibial plateau angle (TPA) can be accurately measured from lateral radiographic views of the stifle joint that include only the proximal portion of the tibia. SAMPLE POPULATION: 282 lateral radiographic views of the stifle joint from 128 dogs. PROCEDURE: 236 radiographs were obtained from 102 dogs with no stifle joint disease, and 46 were obtained from 26 dogs with cranial cruciate ligament rupture. Radiographs were digitized. Tibial plateau angles were determined by measuring the angle between the intersection of the tibial plateau slope line and perpendiculars to 4 tibial axes. The gold standard TPA was based on a reference axis that used the entire length of the tibia and was determined by the line connecting the midpoint of the tibial intercondylar eminence and the center of the talus. Tibial plateau angle1, TPA2, and TPA3 were based on tibial axes that were determined by use of only the proximal portion of the tibia. RESULTS: TPA determined on the basis of the shortest proximal reference axis (TPA1) was not accurate. However, as the length of the reference axis increased, reliability of the TPAs obtained from proximal reference axes improved, and their correlations with the gold standard TPA increased (r = 0.78, 0.86, and 0.92 for TPA1, TPA2, and TPA3, respectively). Equations obtained by regression analysis allowed estimation of the gold standard TPA with some degree of accuracy. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a proximal reference axis to calculate TPA may be an alternative to a calculation based on the full-length axis.     

Inclination of the patellar ligament in relation to flexion angle in stifle joints of dogs without degenerative joint disease

OBJECTIVE: To measure the angles between the patellar ligament and the tibial plateau and between the patellar ligament and the common tangent at the tibiofemoral contact point (TFCP) throughout the full range of motion of the stifle joint in dogs and determine the flexion angles at which the patellar ligament is perpendicular to the tibial plateau or to the common tangent. SAMPLE POPULATION: 16 hind limbs from cadavers of 9 adult dogs without radiographically detectable degenerative joint disease. PROCEDURES: Mediolateral radiographic views of the stifle joints from full extension through full flexion were obtained (10 degrees increments). Angles between the tibial and femoral long axes (beta), between the patellar ligament and the tibial plateau gamma), and between the patellar ligament and the common tangent at TFCP (alpha) were measured. Data were analyzed via simple linear regression. RESULTS: In canine stifle joints, angles gamma and alpha decreased linearly with increasing flexion (angle beta). The patellar ligament was perpendicular to the tibial plateau and perpendicular to the common tangent at the TFCP at 90 degrees and 110 degrees of flexion, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: By use of the conventionally defined tibial plateau, data suggest that at approximately 90 degrees of flexion in stifle joints of dogs, shear force in the sagittal plane exerted on the proximal portion of the tibia shifts the loading from the cranial to the caudal cruciate ligament. Analyses involving the common tangent at the TFCP (a more anatomically representative reference point) identified this crossover point at approximately 110 degrees of joint flexion.     

Determination of Pelvic Limb Alignment in the Large‐Breed Dog: A Cadaveric Radiographic Study in the Frontal Plane

Objectives— To report a method for radiographic determination of the mechanical axis of the canine pelvic limb and its relationship to the joints and bone axes. To report reference ranges for the relationships between the axes of the pelvic limb and for joint position relative to the pelvic limb axis. Study Design— Cadaveric radiographic anatomic study. Animals— Pelvic limbs (n=101) from normal midsized to large breed dogs; tibiae (n=105) from dogs with cranial cruciate ligament disease (previous study). Methods— Extended full‐limb radiography was performed and images analyzed to determine: mechanical joint reference angles (femur, tibia), pelvic limb axis, tibiofemoral and metatarsotibial angle, mechanical axis—femur/metatarsus angle, and mechanical axis deviation (MAD) of the stifle/tarsus. Results— Mean mechanical angles were: lateral proximal femoral (103.7°±5.4°), lateral distal femoral (98.6°±2.5°), medial proximal tibial (92.2°±1.8°), medial distal tibial (95.9°±2.2°), tibiofemoral (9.1° varus ±2.8°), metatarsotibial (0.6° valgus ±2.1°). Mean mechanical axis—femur and—metatarsus angles were 5.6° (±1.7°) and 2.9° (±1.5°), respectively. Mean MAD of the stifle and tarsus were 3.6% (±1.1%) and 1.2% (±0.6%), respectively. Tibial angles were not different between dogs with and without cranial cruciate ligament disease. Conclusions— Mechanical axes of the canine pelvic limb and their relationship to the joints can be determined by full‐limb radiography. Clinical Relevance— Techniques and reference ranges may be useful for diagnosis, surgical planning, and postoperative assessment of pelvic limb deformities.     

Modified tibial tuberosity advancement procedure with tuberosity advancement in excess of 12 mm in four large breed dogs with cranial cruciate ligament-deficient joints

OBJECTIVE: To describe a modification of the tibial tuberosity advancement (TTA) procedure that required tuberosity advancement in excess of 12 mm for the stabilization of cranial cruciate ligament (CrCL) deficient stifle joints. METHODS: Four large breed dogs with CrCL deficient stifle joints (one bilateral) underwent a modified TTA of 15 or 16 mm in order to obtain a patellar tendon angle of 90 degrees to the tibial plateau slope or common tangent between femur and tibia in the extended limb position. The desired TTA was achieved by displacing a 12-mm cage distally; this displacement distance was calculated from two similar triangles formed within the planned osteotomy site. An allogenous cancellous bone block placed proximal to the cage provided buttress support; a corticocancellous allograft filled the remainder of the gap. Tibial tuberosity fixation was performed as previously described. RESULTS: Healing of the osteotomy defects with incorporation of the cancellous block was observed at a mean of 8.6 weeks postoperatively. Normal return of limb function was reported in all of the dogs except for one dog that underwent revision surgery four months postoperatively for a continued lameness. Technical errors at the time of the original surgical procedure in this dog resulted in insufficient tuberosity advancement; additional advancement was performed, which resolved the lameness. CLINICAL SIGNIFICANCE: Results in this series suggest that our modification of the TTA, in order to advance the tuberosity in excess of 12 mm, could be successfully obtained using the currently available implants.     

Kinetic and kinematic analysis of the right hind limb during trotting on a treadmill in Labrador Retrievers presumed predisposed or not predisposed to cranial cruciate ligament disease

Objective-To identify gait characteristics during trotting on a treadmill in nonlame Labrador Retrievers presumed predisposed or not predisposed to cranial cruciate ligament disease (CCLD). Animals-Clinically normal Labrador Retrievers presumed predisposed (n = 10) or not predisposed (7) to CCLD. Procedures-The right hind limb of each dog was classified by use of a predictive score equation that combined tibial plateau angle and femoral anteversion angle as presumed predisposed (high score [> -1.5]) or not predisposed (low score [≤ -1.5]) to CCLD. Tarsal joint, stifle joint, and hip joint kinematics, net moments, and powers were computed. Results-The stifle joint was held at a greater degree of flexion in limbs presumed predisposed to CCLD (130.9° vs 139.3°). More power was generated by muscles acting on the stifle joint in the early stance phase of limbs presumed to be predisposed to CCLD (2.93 vs 1.64 W/kg). The tarsal joint did not reach the same degree of extension in limbs presumed predisposed to CCLD, compared with that in limbs presumed not predisposed to CCLD (179.0° vs 161.0°). Velocity, stance time, vertical and craniocaudal forces, angular velocities, and net joint muscle moments did not differ between groups. Conclusions and Clinical Relevance-Gait mechanics of dogs with high (> -1.5) and low (≤ -1.5) tibial plateau angle and femoral anteversion angle scores were characterized on a treadmill, which may help in the identification of dogs predisposed to CCLD.     

Effect of tibial plateau leveling on stability of the canine cranial cruciate-deficient stifle joint: an in vitro study

OBJECTIVE: To evaluate the effect of tibial plateau leveling on joint motion in canine stifle joints in which the cranial cruciate ligament (CCL) had been severed. STUDY DESIGN: In vitro cadaver study. ANIMALS: Six canine cadaver hind legs. METHODS: Radiographs of the stifle joints were made to evaluate the tibial plateau angle with respect to the long axis of the tibia. The specimens were mounted in a custom-made testing device to measure cranio-caudal translation of the tibia with respect to the femur. An axial load was applied to the tibia, and its position was recorded in the normal stifle, after transection of the CCL, and after tibial plateau leveling. Further, the amount of caudal tibial thrust was measured in the tibial plateau leveled specimen while series of eight linearly increasing axial tibial loads were applied. RESULTS: Transection of the CCL resulted in cranial tibial translation when axial tibial load was applied. After tibial plateau leveling, axial loading resulted in caudal translation of the tibia. Increasing axial tibial load caused a linear increase in caudal tibial thrust in all tibial plateau-leveled specimens. CONCLUSIONS: After tibial plateau leveling, axial tibial load generates caudal tibial thrust, which increases if additional axial load is applied. CLINICAL RELEVANCE: Tibial plateau leveling osteotomy may prevent cranial translation during weight bearing in dogs with CCL rupture by converting axial load into caudal tibial thrust. The amount of caudal tibial thrust seems to be proportional to the amount of weight bearing.     

PREVALENCE,ASSOCIATION WITH STIFLE CONDITIONS,AND HISTOPATHOLOGIC CHARACTERISTICS OF TIBIAL TUBEROSITY RADIOLUCENCIES IN DOGS

A tibial tuberosity radiolucency is sometimes identified on lateral radiographs of canine stifle joints, however little is known about the cause or significance. The purpose of this study was to describe the prevalence, association with other stifle conditions, and histopathologic characteristics of tibial tuberosity radiolucencies in a group of dogs. Radiographs of all canine stifle joints over 5 years were evaluated. Presence or absence of a tibial tuberosity radiolucency was recorded by an observer who was unaware of clinical status. Patient signalment and presence of other stifle joint conditions were recorded from medical records. A tibial tuberosity radiolucency was found in 145/675 dogs (prevalence = 21.5%). Statistically significant associations were identified between tibial tuberosity radiolucency and stifle condition (P < 0.0001), breed size (P = 0.011), and younger age of presentation (P = 0.001), but not with gender (P = 0.513). Dogs with a tibial tuberosity radiolucency had higher odds of having a medial patellar luxation than dogs without (OR = 9.854, P < 0.0001, 95% CI 6.422–15.120). Dogs with a tibial tuberosity radiolucency had lower odds of having a cranial cruciate ligament rupture than dogs without (OR = 0.418, P < 0.0001, 95% CI 0.287–0.609). Four canine cadavers, two with normal stifles and two with tibial tuberosity radiolucencies, underwent radiographic, computed tomographic, and histologic examination of the stifles. Computed tomography revealed a hypoattenuating cortical defect in the lateral aspect of the proximal tibial tuberosity that corresponded histopathologically to a hyaline cartilage core. Findings indicated that the tibial tuberosity radiolucency may be due to a retained cartilage core and associated with medial patellar luxation in dogs.     

Radiographic measurement of craniocaudal instability in stifle joints of clinically normal dogs and dogs with injury of a cranial cruciate ligament

OBJECTIVE: To determine craniocaudal laxity of the stifle joint of dogs when joints were positioned in tibial compression or neutral position. SAMPLE POPULATION: 19 normal stifle joints in 10 clinically normal dogs, 29 stifle joints with varying injury to the cranial cruciate ligament (10 complete ruptures alone, 10 complete ruptures with concomitant damage to the medial meniscus, 6 partial ruptures alone, and 3 partial ruptures with concomitant meniscal tearing), and 19 unaffected contralateral stifle joints in those 29 dogs. PROCEDURE: Relative displacement of bony landmarks was measured on paired lateral radiographs (neutral and tibial compression positions). Two measuring techniques were customized for use in dogs. RESULTS: The first technique failed to distinguish results in normal stifle joints from those in stifle joints with partial deficiency of cranial cruciate ligaments. Significant differences were found for joints with complete rupture, compared with stifle joints in clinically normal dogs. The second technique detected differences between normal stifle joints and injured joints with partial or complete rupture of the cranial cruciate ligament. Significant differences were not detected between joints with partial versus complete rupture. Adjusting data to account for size of dog did not improve results. CONCLUSIONS AND CLINICAL RELEVANCE: A wide range in measurements of laxity was found for stifle joints with intact cranial cruciate ligaments. Differences in degree of damage to the ligament and medial meniscus cannot be deduced from the amount of relative displacement measured on radiographs. Pathologic changes to the cranial cruciate ligament will not necessarily induce detectable changes in laxity of stifle joints in dogs.     

Combination tibial plateau leveling osteotomy and cranial closing wedge osteotomy of the tibia for the treatment of cranial cruciate ligament-deficient stifles with excessive tibial plateau angle

OBJECTIVE: To describe a surgical technique, and outcome, for treatment of cranial cruciate ligament (CrCL) deficient stifle joints with excessive tibial plateau angle (TPA) by combined tibial plateau leveling osteotomy and cranial closing wedge osteotomy (TPLO/CCWO). STUDY DESIGN: Retrospective clinical study. ANIMALS: Fifteen client-owned dogs (18 stifle joints). METHODS: Medical records of dogs that had TPLO/CCWO were reviewed. Pre- and postoperative TPA, CCWO technique, method of fixation and complications were recorded. In-hospital re-evaluation of limb function and length of time to radiographic healing was reviewed. Long-term outcome was assessed by owner telephone interview. RESULTS: Mean pre- and postoperative TPA was 42 degrees and 8 degrees, respectively. The Slocum biradial saw was used to create the CCWO in 4 stifle joints (mean postoperative TPA, 16 degrees) and a sagittal saw was used in 14 stifle joints (mean postoperative TPA, 5 degrees). Postoperative surgical complications were documented in 77.8% of cases; including patellar tendon thickening (61.1%), and implant loosening or breakage (27.8%), seroma formation (11.1%), and local irritation (11.1%). A second surgical procedure was performed in one-third of cases primarily to retrieve implants. Mean time to documented radiographic healing was 18 weeks. Final in-hospital re-evaluation of limb function (mean, 23 weeks postoperatively) was recorded as no lameness in 73.3% and mild lameness in 26.7%. All interviewed owners were satisfied with outcome and 90.9% reported marked improvement or a return to preinjury status. CONCLUSIONS: Long-term clinical outcome of TPLO/CCWO was very good in dogs with excessive TPA, with high owner satisfaction. Longer healing times and a higher complication rate were observed compared with TPLO alone. CLINICAL RELEVANCE: TPLO/CCWO of the tibia in stifle joints with excessive TPA allows for full correction of the TPA to 5 degrees without eliminating buttress support of the tibial tuberosity.     

Geometry of the femoral condyles in dogs

The stifle joint is one of the most important joints in dogs from the orthopaedic point of view. The aim of this study was to document the morphometric values of femoral condyles, given the close relationship between the shape and function of an anatomic structure. The left femora of 16 mid-sized dogs were used, and diameter and nine radii as well as cranial and caudal bow lengths from each condyle were measured. The photographs were taken of the distal femora from both sides. All measurements were obtained from these images by using software. Additionally, the rotation angle was calculated from the intercondylar distance and the difference between lateral and medial bow lengths. In addition to the rotation angle, the difference of diameter and nine radii between the lateral and medial condyles was determined. All radii except getting at 90° were significantly different between the medial and lateral condyles. The greatest values were determined in the caudal part of the medial condyle. This results the smaller contact area and a greater pressure on the underlying surface, and therefore the meniscus and articular cartilage of the caudal part of the medial side suggests the possibility of a risk of injury as the stifle joint flexes. The mean rotational angle of the femur was also calculated to be 2.18° laterally and 1.02° medially in the caudal and cranial parts of condyles, respectively. The result of this study showed that the lateral and medial condyles had different shapes in canine femur.     

Angle between the patellar ligament and tibial plateau in dogs with partial rupture of the cranial cruciate ligament

OBJECTIVE: To measure the angles between the patellar ligament and the tibial plateau and between the patellar ligament and the common tangent at the tibiofemoral contact point (TFCP) in stifle joints of dogs with partial rupture of the cranial cruciate ligament (CrCL) for comparison with data obtained for stifle joints in dogs with intact CrCLs. SAMPLE POPULATION: 60 stifle joints of 54 dogs with surgically confirmed partial CrCL rupture. PROCEDURES: Mediolateral radiographic views of the stifle joints were obtained, and the angles between the patellar ligament and the conventionally defined tibial plateau (angle gamma) and between the patellar ligament and the common tangent to the TFCP (angle alpha) were measured at incidental stifle joint flexion (angle beta) by 2 independent observers. Data underwent linear regression analysis and were compared with findings in joints of dogs without degenerative joint disease. RESULTS: In stifle joints of dogs with a partial rupture of the CrCL, angles gamma and alpha were 5 degrees and 2 degrees larger than each corresponding angle in healthy canine joints. At 100 degrees of flexion, the patellar ligament was perpendicular to the conventionally defined tibial plateau. At 110 degrees of flexion, the patellar ligament was perpendicular to the common tangent at the TFCP. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, stifle joints with partially ruptured CrCLs have marginally larger angles between the patellar ligament and the tibial plateau, compared with joints with intact CrCLs; at equivalent angles of flexion, comparatively greater shear force affects the CrCLs in stifle joints with partial CrCL ruptures.     

Effect of Distal Femoral Growth Plate Fusion on Femoral-Tibial Length

Unilateral distal femoral epiphysiodesis in seven 10 week old crossbred Doberman Pinscher littermates resulted in a significant (p less than or equal to 0.0001) femoral length deficit of 23.5% without clinically detectable alterations in gait up to 42 weeks after surgery. In addition to compensatory hyperextension of the stifle joint, the ipsilateral tibia showed significant (p less than or equal to 0.0001) acceleration in longitudinal growth. The combined femoral-tibial length at necropsy was still significantly shorter (p less than or equal to 0.0001) in the treated leg than in the control leg despite the increased tibial growth. Unlike other species, neither of the other two femoral growth plates produced any significant compensatory increase in length after fusion of the distal growth plate. The femoral condyles of the treated legs rotated caudally and degenerative joint disease developed in all stifle joints of the treated legs. No contralateral limb abnormalities were evident radiographically.     

Effect of tibial tuberosity advancement on cranial tibial subluxation in canine cranial cruciate-deficient stifle joints: an in vitro experimental study

OBJECTIVE: To evaluate the effect of tibial tuberosity advancement (TTA) on tibiofemoral shear force as reflected by measurement of cranial tibial subluxation (CTS) and patella tendon angle (PTA) in the canine cranial cruciate ligament (CrCL) deficient stifle joint. STUDY DESIGN: In vitro cadaver study. ANIMALS: Canine cadaveric hind limbs (n=10). METHODS: CTS and PTA were evaluated from lateral radiographic projections in axially loaded intact CrCL stifle joints, after transection of the CrCL, at a maximally advanced tibial tuberosity position, and at a critical point position. A custom-designed hinge plate allowed alteration of the tibia to tibial tuberosity distance (Ti-TT) under axial load. Digitized radiographic images were used to quantify CTS, PTA, and Ti-TT. Comparisons within groups were made using 1-way repeated measures ANOVA. A post hoc Tukey's HSD test was used to determine post-ANOVA pair-wise comparison within these groups. Significance was set at a value of P<.05. RESULTS: CTS occurred after CrCL transection, which was significantly different from the intact position (P<.01). Subsequent stability of the stifle joint was obtained by advancing the tibial tuberosity. In the maximally advanced tibial tuberosity position, caudal tibial thrust was generated resulting in caudal tibial subluxation that was significantly different from the transected CrCL position (P<.01) and from the intact CrCL position (P<.01). Despite a stable joint, there was slight CTS at the critical point position, which was significantly different from the intact CrCL position (P<.05). The PTA at the maximally advanced position was significantly different from the intact, critical point and reference 90 degrees PTAs (P<.01). The PTA at the critical point position was significantly different from the intact and maximally advanced tibial tuberosity PTAs (P<.01), but not different (P>.05) from the reference 90 degrees PTA. CONCLUSION: We demonstrated that advancement of the tibial tuberosity neutralized cranial tibial thrust, and converted cranial tibial thrust into caudal tibial thrust. Neutralization of tibiofemoral shear forces occurred at a PTA of 90.3+/-9.0 degrees. CLINICAL RELEVANCE: TTA can effectively change the magnitude and direction of the tibiofemoral shear force, and thus may be used to prevent craniotibial translation in a CrCL deficient stifle joint.     

Gross osteology and radiology of the pelvic limb of the adult small East African goat

The aim of this study was to provide the detailed normal gross osteology and radiographic anatomy of the pelvic limb in adult small East African goats as a reference for clinical use, biomedical research and teaching. Radiography of the pelvic limb was performed in five adult small East African goats. Bone specimens of four skeletally mature small East African goats were used for gross osteological study. The ilial wing was wide. The ischiatic tuberosity was prominent and well developed. The acetabulum was rounded. The minor trochanter was located caudomedially, and the femoral trochlea was deep and narrow. The lateral and medial condyles of the femur were approximately of the same size. The tibial tuberosity was prominent, and the cochlea grooves were deep with a pronounced intermediate ridge. The trochlea of the talus was deep. The patella presented a prominent tuberosity on the cranial surface. The metatarsal sesamoid bone was seen in all animals. The observed gross osteology and radiographic anatomy of the pelvic limb of small East African goats was consistent with the presence of strong extensor muscles of the hip, stifle and tarsus for propulsion during terrestrial walking and trotting.     

Age‐related morphometric changes of the tidemark in the ovine stifle

Though the ovine stifle is commonly used to study osteoarthritis, there is limited information about the age‐related morphometric changes of the tidemark. The objective of this study was to document the number of tidemarks in the stifle of research sheep without clinical signs of osteoarthritis and of various ages (n = 80). Articular cartilage of the medial and lateral tibial condyles and of the medial and lateral femoral condyles was assessed by histology: (a) to count the number of tidemark; and (b) to assess the OARSI (Osteoarthritis Research Society International) score for structural changes of cartilage. The number of tidemarks varied between anatomical regions, respectively, from 4.2 in the medial femoral condyle to 5.0 in the lateral tibial condyle. The axial part showed a significant higher number of tidemarks than the abaxial part, for all regions except the medial tibial condyle. Whilst the tidemark count strongly correlated with age (Spearman's correlation coefficient = 0.70; 95% confidence interval (95% CI): 0.67–0.73; p < 0.0001), the OARSI score was weakly correlated with age in our cohort of sheep (Spearman's correlation coefficient = 0.25; 95% CI: 0.19–0.30; p < 0.0001). Interestingly, no tidemark was seen in the three animals aged 6 months. Our data indicate that the number of tidemarks increases with age and vary with anatomical region. The regional variation also revealed a higher number of tidemarks in the tibia than in the femur. This could be attributed to the local variation in cartilage response to strain and to the difference in chondrocyte biology and density.     

Proximodistal alignment of the canine patella: radiographic evaluation and association with medial and lateral patellar luxation

Objectives— To evaluate the contribution of proximodistal alignment of the patella to patellar luxation, and to evaluate the structures contributing to proximodistal alignment of the patella relative to the femoral trochlea.
Study Design— Retrospective study using a convenience sample.
Animals— Medium to giant breed dogs (n=106).
Methods— Medical records and stifle radiographs of 106 dogs were reviewed. Radiographic measurements evaluated the proximodistal alignment of the patella with respect to the femoral trochlea, distal aspect of the femur, and proximal aspect of the tibia. Measurements were compared between dogs with clinically normal stifles (controls; n=51 dogs, 66 stifles), and dogs with a clinical diagnosis of medial patellar luxation (MPL, n=46 dogs, 65 stifles) or lateral patellar luxation (LPL, n=9 dogs, 11 stifles) using ANOVA.
Results— In dogs with MPL, the ratio of patellar ligament length (PLL) to patellar length (PL) was increased, as was the ratio of the distance from the proximal aspect of the patella to the femoral condyle (A) to PL ( P <.0001). Dogs with LPL had a decreased A:PL ( P =.003) and an increased ratio of the proximal tibial length (PTL) to distal tibial width (DTW; P =.009).
Conclusions— MPL is associated with a relatively long patellar ligament and patella alta in medium to giant breed dogs. LPL is associated with a relatively long proximal tibia and patella baja. Values for PLL:PL>2.06 and A:PL>2.03 are suggestive of the presence of patella alta, whereas a value for A:PL<1.92 is suggestive of patella baja.
Clinical Relevance— Measurements of both PLL:PL and A:PL are recommended in dogs with patellar luxation, and surgical correction should be considered in those with abnormal values.     

Comparison of normograde and retrograde intramedullary pinning of feline tibias

This study evaluated the effects of normograde and retrograde intramedullary pinning of mid-diaphyseal fractures of the feline tibia on the anatomical structures of the stifle joint. Using the paired pelvic limbs from five mature feline cadavers, a transverse, mid-diaphyseal osteotomy was performed, and each tibia was pinned in a normograde or retrograde fashion. The stifle joints were examined to determine the pin exit site and measure the distance from the exit site to pertinent anatomical structures of the stifle joint. Neither normograde nor retrograde intramedullary pinning resulted in damage to the cruciate ligaments, menisci, intermeniscal ligament, femoral condyles, or joint capsule. The patellar tendon was penetrated in all five tibias during retrograde pin insertion.     

Effect of Tibial Tuberosity Advancement on Femorotibial Contact Mechanics and Stifle Kinematics

Objective— To evaluate the effects of tibial tuberosity advancement (TTA) on femorotibial contact mechanics and 3-dimensional kinematics in cranial cruciate ligament (CrCL)-deficient stifles of dogs.
Study Design— In vitro biomechanical study.
Animals— Unpaired pelvic limbs from 8 dogs, weighing 28–35 kg.
Methods— Digital pressure sensors placed subjacent to the menisci were used to measure femorotibial contact force, contact area, peak and mean contact pressure, and peak pressure location with the limb under an axial load of 30% body weight and a stifle angle of 135°. Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TTA-treated conditions. Repeated measures analysis of variance with a Tukey post hoc test ( P <.05) was used for statistical comparison.
Results— Significant disturbances to all measured contact mechanic parameters were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and internal tibial rotation in the CrCL-deficient stifle. No significant differences in any contact mechanic and kinematic parameters were detected between normal and TTA-treated stifles.
Conclusion— TTA eliminates craniocaudal stifle instability during simulated weight-bearing and concurrently restores femorotibial contact mechanics to normal.
Clinical Relevance— TTA may mitigate the progression of stifle osteoarthritis in dogs afflicted with CrCL insufficiency by eliminating cranial tibial thrust while preserving the normal orientation of the proximal tibial articulating surface.     

Histomorphometric analysis of the proximal portion of the femur in healthy dogs

OBJECTIVE: To describe the cancellous bone architecture of the head and neck of the femur in healthy dogs by use of automated histomorphometry techniques in conjunction with histologic grading of articular cartilage. ANIMALS: 30 mature male dogs with healthy coxo-femoral joints PROCEDURE: Dogs were 1.5 to 4 years old and weighed 27 to 37 kg. Computer images of fine-detail radiographs of 100-microm-thick coronal and transverse plane sections of the head and neck of the femur (14 dogs) were analyzed by use of histomorphometry software. Statistical comparisons among histomorphometric indices of 4 regions were performed. Histologic preparations of coronal and transverse plane sections of femoral head articular cartilage (16 dogs) were graded. Median grades for lateral, medial, cranial, and caudal halves of the femoral head articular cartilage were determined. RESULTS: Bone volume/total volume, trabecular thickness and number, and bone surface/total volume were significantly higher in the femoral head than in the femoral neck. Anisotropy (trabecular alignment) and trabecular separation were significantly higher in the femoral neck than in the femoral head. Anisotropy was significantly higher in the caudal half of the femoral neck than in the cranial half. Cartilage had histologic grades indicating health without significant differences among lateral, medial, cranial, and caudal halves of femoral head cartilage. CONCLUSIONS AND CLINICAL RELEVANCE: A predictable cancellous architecture in the head and neck of the femur is associated with healthy cartilage.     

Avulsion of the tibial tuberosity in a litter of greyhound puppies

Avulslon of the tibial tuberosity was dlagnosed In six of seven greyhound ilttermates aged flve and a half months. The puppies showed hindlimb lameness of varying severity. Radiological assessment of affected stifle joints revealed partial or complete avulsion of the tlblal tuberoslties. In four puppies the lesions were bliaterai. Euthanasia of the two most severely affected puppies performed; the changes observed on histopathological examination of their cranioproximal tibiae suggested that the underlying lesion was that of osteochondrosis. A heredltary predisposition In greyhounds to osteochondrosis of the physis between the apophysis and the cranioproximal tibia1 dlaphysis Is postulated.