Many of you know our two mascots – Tucker and Tess. They’re our receptionist, Diane’s, two little shih tzus. Recently, Tucker injured himself jumping off the sofa.
At first he carried his right rear leg completely up as he walked. He was what we term three-legged lame. However, by the next day he was almost completely normal on the leg. He put up to 95% of his normal pressure on it, and he didn’t seem unduly sore.
At that time, I performed an orthopedic exam to try to localize the problem. In an ortho exam, we place the pet on his side with the effected leg up. I start at the toes and move up to the hip, feeling every bone and every joint for any area that is swollen, moves in the wrong direction, feels out of place, or where he gives me a pain sign.
For Tucker’s ortho exam, everything felt relatively normal. Nothing was out of place or swollen, and he wouldn’t give me a pain sign anywhere. However, we all know Tucker pretty well, and know that he’s a very stoic dog. He hates to complain. So I figured that he was simply masking whatever was going on. I put him on a general anti-inflammatory and ordered exercise restriction, and waited to see how things went.
Two days later we found out when he again started carrying the same leg, and was once again three-legged lame. This time I got to perform my orthopedic exam while he had an active problem, so the problem was a lot easier to find. In short, his hip was out of the socket. This was confirmed with x-rays, as you see to the right.
Dislocated hips are relatively common after any form of blunt trauma to the pelvis. We tend to see them after hit-by-cars, falls from elevation, and occasionally after dog fights. However, it’s relatively rare to see them from something as simple as jumping up and down off the sofa.
A lot of things have to go wrong for the hip to dislocate. There is a very thick, tough ligament that goes from the very end of the femoral head (that’s the ball in the ball-and-socket hip joint) to the acetabulum (that’s the socket part of this same joint). This ligament has to tear for the hip to dislocate. Also, the joint capsule that envelopes the entire joint has to tear as well. And finally, the combined muscular tendons of the area have to fail to some degree. So for a hip to pop out of place, a lot of tough structures have to give way.
Because of the tearing and failing of all these tissues, repairing a dislocated hip is not as simple as TV would have you believe. It’s not a matter of simply “popping it back in place” and everything’s fine. Getting it placed back in the socket is a simple matter, but getting it to stay there is very difficult. The vast majority of cases pop out again with the first challenge to the joint. And so was the case with Tucker. Irrespective our efforts to save the joint we couldn’t get the hip to stay in.
So that meant the next step was a major orthopedic surgery called a Femoral Head Ostectomy, or FHO for short. In an FHO we remove the femoral head and neck completely, so that there is no hip joint. Instead of the normally function hip joint, the pet instead forms a muscular attachment of the rear leg to the pelvis.
This sounds like it might be unstable, but in fact it actually works very, very well. The way I explain it to clients is that after an FHO the back leg works similar to the front leg. If you study the anatomy of a dog’s front leg you’ll realize that there is no joint between it and the body. The front leg forms the shoulder joint through its attachment to the scapula (shoulder blade), but that entire apparatus is attached to the body by muscles only. There is no bone-to-bone joint that attaches the shoulder/shoulder blade to the rib cage. Instead, it’s all held in place by the muscles of the shoulder.
After an FHO the rear leg functions much the same way. The gluteals and other large pelvic muscles hold the femur in place. Because there is no bone-to-bone contact the pet feels no discomfort and walks relatively normally.
Theoretically, FHOs work best in small to medium sized dogs. However, I’ve used the procedure in dogs up to 130 pounds, and almost universally they do very well.
We performed an FHO on Tucker earlier this week, and so far everything is fine. Of course, we’re treating him with the K-Laser to increase his recovery rate and decrease his post-op pain, but I have no doubt that long-term he’s going to do very well.