IN THIS NEWSLETTER:
Spinal cord injury in the dog remains one of the more common conditions seen in our referral practice. Far and away the most common spinal cord injury we see is intervertebral disc herniation. Essentially all of these cases are seen first by the primary care doctor, and initial medical management of the case is extremely important in long-term outcome many times.
The rationale for medical management is based upon the pathophysiology of spinal cord trauma. Spinal cord contusion or laceration initiates a progressive series of pathologic events. The results of which are a varying degree of tissue necrosis and neurological dysfunction. Neuro deficits are a result of mechanical disruption of the neuronal pathways, and the delayed injury that develops over a period of hours to days post-insult. The latter is due to the ischemic damage to the cord. Degree of ischemia is directly correlated with severity of the initial injury and is progressive. Along with decreased spinal cord blood flow, there is release of endogenous auto-destructive factors (free radicals, arachidonic acid metabolites, opiod peptides, etc.). Corticosteroids are the most commonly utilized mediators of these ischemic factors in clinical medicine. There are numerous studies which show a positive response to the use of large doses of methylprednisolone sodium succinate (Solu Medrol®). Initial dose suggested is 30 mg/kg IV as a bolus, followed by repeated multiple doses of 15 mg/kg given at 2 hours and 6 hours followed by a continuous infusion of methylprednisolone sodium succinate at a rate of 2.5 mg/kg/hr for 48 hours. This is an expansion of earlier recommended treatment durations of up to 24 hours.
It has been my experience that it is not uncommon for g.i. complications (vomiting, melena) to be seen before a full 48 hours of treatment has been achieved, necessitating discontinuation of the steroid drip and initiation of g.i. protectants. Interestingly, I have been unable to find any documentation that prophylactic use of g.i. protectants is of any benefit, and we do not routinely administer these prophylactically.
The role of surgical management is to rapidly decompress the spinal cord. Continuing compression of the cord can be due to both the mass effect as well as spinal cord edema. Treating the ischemia, which results from continued cord compression, is the identical rationale for the medical management. Based upon the pathophysiological events that occur with spinal cord injury, i.e. the progressive nature of the ischemia, early and appropriate surgical intervention is of paramount importance.
Appropriate initial medical management followed by early surgical intervention complement each other in our goal of attenuating the continuing damaging initiated by spinal cord injury.
We have been extremely pleased with acceptance of the tibial plateau leveling osteotomy procedure (TPLO) for reconstruction of cranial cruciate ligament deficient stifles. We initially began using the TPLO primarily in our large breed patients and those canine athletes in which we wanted a more predictable outcome versus traditional extra-capsular repair. Results have been very encouraging and patient outcome has overall been very good; we now have between 25 and 30 of these large breed dogs out to a sufficient period of time postop that we feel we are getting much better results, faster, than we did with our prior reconstruction techniques, and we are now recommending the TPLO as the procedure of choice for large breeds. Additionally, new instrumentation and plates are available which allow us to offer TPLO's in dogs under 18 kg (40 lb.) body weight, and in those cases in which small skeletal size made placement of the 3.5 mm TPLO plate difficult. If you are interested in more information on the TPLO, or have a case which is a candidate, please give us a call.
One of the more common orthopedic injuries seen in practice is luxation of the coxofemoral joint. It can also be one of the more frustrating injuries in which to achieve a successful resolution, especially when complicated by pre-existing disease of the hip joint such as degenerative joint disease or dysplasia.
Management of the patient with hip luxation first begins with overall patient assessment and evaluation for concurrent internal injuries, especially involving the diaphragm and the urinary bladder when automobile injury is a factor. Most luxations occur in a craniodorsal manner, with the femoral head forced dorsal and then cranial to the acetabulum by the force of the injury and the pull of the gluteal muscles. Initial examination findings often show a patient with a limb that is held at an awkward angle, with the knee and foot externally rotated and adducted. Details of the palpable findings can be reviewed in surgical texts, however; a good quality radiograph is diagnostic in all instances, with a both a lateral view and a VD view recommended.
Initial treatment recommendations depend upon close examination of the radiograph. It is not uncommon to find a small fracture fragment off the femoral head situated within the acetabular fossa. This usually represents the area where the round ligament's attachment has been fractured off the femoral head. A closed reduction is not suggested in these cases where a fracture fragment is identified, as that will lead to accelerated hip joint DJD and also predispose the closed reduction to failure.
In instances where the femoral head anatomy and acetabular anatomy are normal, and there is no fracture fragment noted within the joint, I recommend a closed reduction be done initially, if possible. If the hip can be reduced and does not tend to readily reluxate, I place these dogs in a non weight-bearing, or Ehmer sling for 14 to 21 days. Closed reduction can be expected to be successful in about 50 % of the cases.
In the case where there is a fracture fragment within the joint, abnormal joint anatomy (either the femoral head or acetabulum), or in cases with a failed closed hip reduction, surgical reduction of the hip joint can be done. Over the course of my practice, I have found that I typically rely on two different surgical methods for reducing coxofemoral luxations.
Physically pinning the hip joint in place, using a trans-acetabular IM pin, is one method of surgical fixation I have found to produce reliably good results. I tend to reserve this for dogs under 40 lbs. body weight, however; I have used this with success in several large breed dogs. The technique is not as technically demanding as the Knowles Toggle Pin, but has the disadvantage of requiring a second surgical procedure to remove the pin, and of requiring the dog to be non weight-bearing while the pin is across the hip joint. The TA pin is left in and the hip is placed in an Ehmer sling for 3 weeks. Following pin removal, further exercise restriction is advised for an additional 3-4 weeks.
Knowles Toggle Pin
This technique and it's modifications involve the creation of an artificial round ligament between the fovea capitis and the acetabulum. Synthetic suture material such as braided or monofilament non-absorbable nylon is used. The suture is placed through a commercially available toggle pin (IMEX® Veterinary), which is inserted through a hole drilled in the acetabular fossa. The toggle pin will lie flat against the medial wall of the acetabulum, within the pelvic canal. By passing this suture through a tunnel drilled from fovea capitis out the lateral cortex of the femur, just distal to the greater trochanter, the suture can be tensioned and the femoral head held firmly within the depth of the acetabulum. This technique I have found especially useful when there is abnormal hip joint anatomy, or if the patient must bear weight on the repair early in the postop period.
Both of these techniques can be considered in managing your cases of coxofemoral luxation. Both ultimately rely on periarticular fibrosis to strengthen and maintain the hip long-term. If you have questions about hip luxations, please feel free to give me a call.
It’s hard to believe that it was back in January of 1994 that we opened
the doors and started our referral practice here in Tulsa. We would
all like to take a moment to thank everyone for their support over the
years, and for the friends we have made by virtue of coming to Tulsa.
We are looking forward to the next 10 years!
Healing time with the TPLO requires about two months for the bone and slightly longer for soft tissues. Strict confinement is mandatory during the healing process. Because the plateau leveling allows the joint pain to rapidly subside, the major problem during recovery is excessive patient activity prior to the completion of the bone healing. Most patients return to controlled activity in 2 months, and full activity in 3 to 4 months. Patients can return to athletic competition (field trials, hunting, agility trials, Schutzhund) usually by 6 months after surgery.
For more information on TPLO, please do not hesitate to give us a call.