Case: Sacral fracture in a cat
16th November 2014
Molly, a 1 year old cat, presented with a sacral fracture. The sacrum is a single bone that actually forms from three sacral vertebrae that fuse together. Its job is to connect the spinal column with the pelvis. Asuch, it is the route through which all hind limb weight bearing forces and propulsive forces are transmitted from the hind feet in contact with the ground to the rest of the body in front of the pelvis, holding the body up and driving it forwards during locomotion.
There are several important nerves – the sacral nerves – that pass out of holes in the sacrum and from just behind it. They transmit controlling nerve messages to and from the bladder, and also to and from the anus. The sacral nerves also are involved in the transfer of some of the information to and from the hind limbs, though there are several nerves that leave the spine “upstream” of the sacrum which deal with the lion’s share of the communication traffic to and from the hind limbs. One of these is the L7 nerve which leaves the spinal column just in front of the sacrum.
The sacral nerves can be injured or trapped when the sacrum is fractured. The consequences of this are:
* Severe pain (nerves really don’t “like” being trapped)
* Inability to bear weight and walk normally, because the weight bearing link between the pelvis/hind limb(s) and the rest of the body forwards of the hind limbs has been interrupted.
* Loss of control of the bladder. The bladder typically keeps filling until it is fit to pop, and then high pressure in the bladder usually results in further urine trickling out in a steady dribble. If the bladder is left in an “inflated” state for long, the bladder wall can suffer damage which may be irreversible.
We removed a broken fragment of her sacrum to prevent it from impinging the important L7 nerve to the hind limbs that comes out of the spinal column immediately in front of the sacrum. We then “buttressed” her fractured sacrum with a locking plate bent into a U shape, taking the pressure off the fragments and off the sacral nerves while the broken sacrum healed. This is a technique that we have developed ourselves.
The day after surgery Molly was able to walk and was able to urinate voluntarily. She was cage confined for a few weeks but she continued to make excellent progress in the post-operative period and the prognosis for a return to completely normal life is excellent.