Biomechanical effects of cranial closing wedge osteotomy on joint stability in normal canine stifles: an ex vivo study

BACKGROUND

Cranial closing wedge osteotomy (CCWO) is a functional stabilisation technique for cranial cruciate ligament (CrCL) ruptures. This biomechanical study aimed to evaluate the influence of CCWO on the stability of the stifle joint. Eighteen Beagle stifle joints were divided into two groups: control and CCWO. The stifle joints were analyzed using a six-degree-of-freedom robotic joint biomechanical testing system. The joints were subjected to 30 N in the craniocaudal (CrCd) drawer and proximal compression tests and 1 Nm in the internal-external (IE) rotation test. Each test was performed with an extension position, 135°, and 120° of joint angle.

RESULTS

The stifle joints were tested while the CrCLs were intact and then transected. In the drawer test, the CCWO procedure, CrCL transection, and stifle joint flexion increased CrCd displacement. The CCWO procedure and CrCL transection showed an interaction effect. In the compression test, the CCWO procedure decreased and CrCL transection and stifle joint flexion increased displacement. In the IE rotation test, CCWO, CrCL transection, and stifle joint flexion increased the range of motion.

CONCLUSIONS

CCWO was expected to provide stability against compressive force but does not contribute to stability in the drawer or rotational tests. In the CCWO-treated stifle joint, instability during the drawer test worsened with CrCL transection. In other words, performing the CCWO procedure when the CrCL function is present is desirable for stabilizing the stifle joint.

Meniscal Load and Load Distribution in the Canine Stifle after Modified Tibial Tuberosity Advancement with 9 mm and 12 mm Cranialization of the Tibial Tuberosity in Different Standing Angles

OBJECTIVES

 The aim of this study was to investigate the kinetic and kinematic changes in the stifle after a modified tibial tuberosity advancement (TTA) with 9 and 12 mm cranialization of the tibial tuberosity in different standing angles.

STUDY DESIGN

 Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs. Sham TTA surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty percent body weight was applied to the limbs with the stifle in 135 or 145 degrees of extension. Each knee was tested in 135 degrees with intact cranial cruciate ligament (CCL) and deficient CCL with 12 mm cranialization of the tibial tuberosity in 135 and 145 degrees of extension. The last two tests were repeated with 9 mm.

RESULTS

 Transection of the CCL altered kinematics and kinetics. Tibial tuberosity advancement with 12 mm cranialization sufficiently restored stifle kinematics in 135 and 145 degrees but 9 mm TTA failed to do so in 135 degrees. The same effects were seen for internal rotation of the tibia. After TTA, a significant reduction in the force acting on both menisci was detected.

CONCLUSION

 Tibial tuberosity advancement could restore stifle kinematics and meniscal kinetics after transection of the CCL ex vivo in the present study. Tibial tuberosity advancement reduced the contact force ratio on both menisci significantly. No changes of peak pressure and peak pressure location occurred following TTA under any of the tested experimental settings. Increased stifle extension (145 degrees) might lead to more stability, contradictory to biomechanical theory.

Evaluation of Meniscal Load and Load Distribution in the Canine Stifle after Tibial Plateau Levelling Osteotomy with Postoperative Tibia Plateau Angles of 6 and 1 Degrees

OBJECTIVES

 The aim of the study was to investigate the kinetic and kinematic changes in the stifle after a tibial plateau levelling osteotomy (TPLO) with a postoperative tibia plateau angle (TPA) of either 6 or 1 degrees.

STUDY DESIGN

 Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs from adult Retrievers.Hinge plates were applied and a sham TPLO surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty per cent bodyweight was applied to the limbs with the stifle in 135 degrees of extension. Each knee was tested with intact cranial cruciate ligament (CCL), deficient CCL, 6 degrees TPLO and 1degree TPLO.

RESULTS

 Transection of the CCL altered kinematics and kinetics. However, comparing the intact with both TPLO set-ups, no changes in kinematics were detected. After 1 degree TPLO, a significant reduction in the force acting on both menisci was detected (p = 0.006).

CONCLUSIONS

 Tibial plateau levelling osteotomy restores stifle kinematics and meniscal kinetics after transection of the CCL ex vivo. The contact force on both menisci is reduced significantly after TPLO with a TPA of 1 degree. Increased stifle flexion might lead to caudal tibial motion.

Function of the crocodilian anterior cruciate ligaments

The anterior cruciate ligament (ACL) is an important knee stabilizer that prevents the anterior subluxation of the tibia. Extant crocodiles have two ACLs, the ACL major and minor, yet their functional roles are unclear. We here examined in-situ forces within the ACL major and minor in saltwater crocodiles (Crocodylus porosus) with a 6-degree-of-freedom robotic testing system under the following loading conditions: (a) 30 N anterior tibial load at 150°, 120°, and 90° knee extension; (b) 1 Nm internal/external torque at 150° and 120° knee extension; (c) 30 N anterior tibial load +1 Nm internal/external torque at 150° and 120° knee extension. The In-situ force in the ACL minor was significantly higher than that of the ACL major in response to anterior tibial load at 90° knee extension, and anterior tibial load + external torque at both 150° and 120° knee extension. Meanwhile, the force in the ACL major was significantly higher than that of the ACL minor in response to internal torque at 120° knee extension, and anterior tibial load + internal torque at 150° knee extension. The present results showed that the ACL minor and major of saltwater crocodiles have different functions. In response to anterior tibial load + internal/external torques, either of two ACLs reacted to opposing directions of knee rotation. These suggest that two ACLs are essential for walking with long axis rotation of the knee in crocodiles.

Investigation of the effects of excessive tibial plateau angle and changes in load on ligament tensile forces in the stifle joints of dogs

OBJECTIVE

To investigate the effect of an excessive tibial plateau angle (TPA) and change in compressive load on tensile forces experienced by the cranial cruciate, medial collateral, and lateral collateral ligaments (CCL, MCL, and LCL, respectively) of canine stifle joints.

SAMPLE

16 cadaveric stifle joints from 16 orthopedically normal Beagles.

PROCEDURES

Stifle joints were categorized into unchanged (mean TPA, 30.4°) and excessive (mean TPA before and after modification, 31.2° and 41.1°, respectively) TPA groups. The excessive TPA group underwent a TPA-increasing procedure (curvilinear osteotomy of the proximal aspect of the tibia) to achieve the desired TPA. A robotic system was used to apply a 30- and 60-N compressive load to specimens. The craniomedial band of the CCL, caudolateral band of the CCL, MCL, and LCL were sequentially transected; load application was repeated after each transection. Orthogonal force components were measured in situ. Forces on ligaments were calculated after repeated output force measurements as the contribution of each component was eliminated.

RESULTS

Increasing the compressive load increased tensile forces on the craniomedial and caudolateral bands of the CCL, but not on the MCL or LCL, in specimens of both groups. At the 60-N load, tensile force on the craniomedial band, but not other ligaments, was greater for the excessive TPA group than for the unchanged TPA group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that stress on the CCL may increase when the compressive load increases. The TPA-increasing procedure resulted in increased tensile force on the CCL at a 60-N compressive load without affecting forces on the MCL or LCL.

Biomechanical Effects of Tibial Plateau Levelling Osteotomy on Joint Instability in Normal Canine Stifles: An In Vitro Study

OBJECTIVE

 The aim of the study was to determine the changes in biomechanical characteristics following tibial plateau levelling osteotomy (TPLO) using simulated manual tests.

STUDY DESIGN

 Twenty-one stifles from healthy Beagle dogs that had undergone TPLO or had not (control) were first tested in the intact form, and then the cranial cruciate ligament (CrCL) was transected in each to provide four test situations: control-intact, control-CrCL-transected, TPLO-intact and TPLO-CrCL-transected. The stifles were then analysed using a robotic joint biomechanical testing system. The craniocaudal drawer, axial rotation and proximal compression tests were applied.

RESULTS

 The craniocaudal displacement during the drawer test was not significantly different between the control-intact and TPLO-intact. However, the displacement was significantly greater in the TPLO-CrCL-transected than in the control-intact. In the axial rotation test, the internal-external (IE) rotation was significantly greater in the TPLO-intact than in the control-intact. Similarly, the IE rotation was significantly greater in the TPLO-CrCL-transected than in the control-CrCL-transected. In the proximal compression test, craniocaudal displacement was not significantly different among the control-intact, TPLO-intact and TPLO-CrCL-transected.

CONCLUSION

 These findings suggest that TPLO influences the tension of the collateral ligaments and might generate laxity of the tibiofemoral joint. Instability after the osteotomy might be associated with the progression of osteoarthritis.

Analysis of passive tibio-femoral joint movement of Beagle dogs during flexion in cadaveric hind limbs without muscle

The aim of this study was to evaluate the normal range of motion of the canine tibiofemoral joint and the movement of the tibia relative to the femur, especially the internal/external rotation under flexion. Right stifle joints were harvested from eight skeletally mature Beagle dogs, which were euthanized for reasons unrelated to this study. All muscle tissue was removed from the limbs prior to testing. Flexion and extension tests were conducted using a robotic manipulator with six degrees-of-freedom. Cranial/caudal and medial/lateral displacement and varus/valgus and internal/external rotation were measured at various degrees of flexion. We observed that the tibia rotated internally at an increasing flexion angle with mean peak internal and external rotations of 20.0 ± 13.8° and 4.5 ± 3.6°, respectively. The tibia also tended to displace cranially at an increasing flexion angle, with a mean peak cranial displacement of 8.9 ± 4.4 mm; there was minimal medial displacement when increasing the flexion angle. Valgus rotation also tended to occur at an increasing flexion angle. During the flexion of the canine stifle joint, approximately 20° of internal tibial rotation occurred around the longitudinal axis, along with a rollback motion involving the cranial displacement of the tibia.