Comparison of two dimensional kinematic analysis of hind limb during trotting on treadmill in chihuahuas with normal and medial patellar luxation stifles after surgical correction

จาก ChulaPedia

Medial patellar luxation is a common cause of abnormal gait encounter in small breed dogs. It is cause of intermittent lameness affecting the stifle joints insmall breed dogs. Patella is a large sesamoid bone buried in quadriceps tendon which it primarily works as extensor mechanism of stifle joint. These structures give a strong movement of the stifle joint which present as a term of joint angular motion or range of motion which it is descriped how much movement exist at a center of joint rotation. The motion loss of stifle joint is associated with gait abnormality which it is seen as a semiflexed posture during gait in dogs with medial patellar luxation. Surgical correction for medial patellar luxation is required to realign the quadriceps apparatus, to stabilize a patella into the normal anatomical position, to restore the stifle extensor mechanism and to promote the normal range of motion. Although the recovering of weight bearing forces increases untill nearly normal after surgery, we cannot conclude that the quadriceps externsor mechanism of stifle joint also returns to normal motion. There is a limitation for understanding about gait mechanism of dogs with medial patellar luxation and functional recovery of stifle joint after surgical correction. The two dimensional kinematic motion analysis was carried out to characterize active range of motion (AROM) , maximal extension angle (MEA) and maximal flexion angle (MFA) of stifle joint, hip joint and tarsal joints on sagittal plane in dogs during trotting on treadmill (velocity 1.11 m/s). Seven healthy Chihuahuas (n=14normal stifles) and 10 Chihuahuas with grade III medial patellar luxation ( MPL) undergoing surgical correction (n=10 MPL stifles) were studied. The parameters were comparing between normal group and MPL group undergone surgical correction at pre-operatively, 2, 4, 6 and 8 weeks post-operatively. The AROM, MEA and MFA of stifle joint in MPL group were significantly lower than normal group (p<0.001). The AROM of tarsal and hip joints in MPL group were significantly higher than in normal group(p<0.001). The surgical correction to realign the quadriceps mechanism was performed with the combined techniques of tibial tuberosity transposition, trochlear block recession, medial desmotomy and lateral imbrication. The AROM of hip joint, stifle and tarsal joints were not significant difference between MPL group and normal group at 8 week post-operatively (p>0.05) . In conclusion, the MPL dog lost the performance of stifle extension. The stifle was more flexion and the degree of motion of the hip joint and tarsal joints were increased to compensate the trotting. Moreover, the AROM of hind limb joints could return to normal function at 8 week postoperatively. Clinical relevance, this kinematic motion analysis will allow detecting abnormal kinematic parameters that will be useful to evaluate surgical outcome by using objective measures in dogs after treatment.