Photo Credit: Russell Stitzlein
Things were a bit quiet the other morning so I decided to go up to the OR and join the rest of the team who were fixing a distal tibia fracture and see if I could learn a thing or two while waiting for the next consult to come in. I wasn’t scrubbed in for more than five minutes when a page came through from the ED. Normally the residents page to call consults, so when the circulating nurse read the text page and it was from one of the ED attendings, I asked that she call right away to see if it might be something more urgent than usual. The ED attending relayed that she had a construction worker in the ED who had a crane lift swing and hit his leg, leaving him with a grossly deformed knee and an absent popliteal (major artery that courses behind the knee) pulse. My mind immediately focused on a few serious injuries that might fit the description, including a knee dislocation. If there was indeed a vascular compromise, it would be a surgical emergency, so I asked that they have vascular surgery on standby, get Xrays immediately and told them I’d be right down to evaluate the patient.
I scrubbed out of the case and rushed down to the ED where I found my patient calmly awaiting Xrays. As I pulled back the sheet that covered his legs, I immediately felt a sense of relief – it looked like a patella (knee cap) dislocation and not a more serious injury and the patient’s leg looked well perfused. A quick neurovascular exam demonstrated that the patient had a bounding dorsalis pedis (artery that courses along the top of the foot) pulse, meaning that a vascular injury at the level of the knee was highly unlikely, and showed that the patient’s nerves were likely uninjured since he had a normal sensory and motor exam. At that point, I advised the ED attending that we would not need vascular surgery to be involved. Xrays confirmed my suspicion and further assuaged my initial fears. I then proceeded to reduce the patella by providing adequate analgesia and getting the patient to relax his quadriceps muscles, allowing the patella to easily slide up and over the lateral femoral condyle and back into the trochlea where it belongs. Reducing the patient’s patella led to immediate pain relief and restoration of normal knee function.
There was still the matter of the laceration over the knee joint which was concerning that it might communicate with the joint, which would mean the patient would require emergency surgery to wash out his knee and prevent infection. Closer examination of the patient’s Xrays showed a possible air-fluid level in the knee effusion. Since air doesn’t normally exist in the joint or soft tissues, the only way for it to get in is through an opening in the skin or infection (and there is no reason to believe this patient’s knee was infected prior to his injury). To test to see if the laceration communicates with the joint, I injected sterile saline into the knee. To rule out a traumatic arthrotomy, 150cc of saline need to be injected into the knee without having any of the fluid exit from the wound. As soon as I had injected 10cc of saline into the joint, fluid began flowing out of the laceration, indicating the laceration communicated with the knee joint and meaning that our patient needed to go to the OR to have his knee washed out to prevent infection and further injury to his knee.
We took him to the OR within two hours and were able to find the small hole in his knee capsule which we repaired and then we irrigated his knee with 9L of sterile saline in order to wash out any debris or bacteria that might have been able to enter the joint via the small rent in the capsule. We kept the patient in the hospital for 48 hours to give IV antibiotics and then sent him home with a knee immobilizer to help stabilize his knee due to the ligamentous injury caused when his patella dislocated.