Reducing Patella Dislocations in the Field

A 13-year-old female was playing basketball in gym class. As she ran down the court, she attempted to change direction to avoid another player. She twisted quickly to her left while her right foot was planted firmly on the floor in front of her. She reported feeling a pop, followed by excruciating pain in her right knee. She fell to the ground and was unable to straighten her leg.

When EMS arrived, they found the patient lying on the gym floor, crying from the pain. She was diaphoretic and tachycardic, holding her right leg in flexion, and there was noticeable swelling along the lateral aspect of the right knee joint. Circulatory and sensory function were normal in the foot, and she appeared to have normal motor function as well, but testing was restricted by severe pain. The patient’s discomfort prevented splinting. The crew was unable to move her to a stretcher for transport because even minimal movement produced a significant increase in pain.

The crew placed ice on the knee and requested an ALS intercept for pain management; it arrived in less than 20 minutes, during which time the patient continued to cry and exclaim about her pain, which she rated 10/10. The paramedic providers administered two doses of 5 mg morphine IM before pain was adequately controlled to facilitate splinting and transfer from the floor to the ambulance stretcher. Transport time was approximately 30 minutes over rural roads. Paramedics contacted medical control for two additional doses of intravenous morphine en route.

When the patient arrived at the ED, the physician immediately straightened the leg and reduced the dislocation, and the patient’s pain went away. “That was so simple!” her father said. “Why couldn’t the EMTs just do that?”

Changes in New York

In New York we asked that question too: Why can’t EMS providers reduce patella dislocations? The answer was that joint dislocation reduction was outside our state’s scope of practice for EMS providers. We elected to study the problem, review the literature and appeal to the State Emergency Medical Advisory Committee and Department of Health to change the scope of practice.

We could not isolate the number of cases of patella dislocation that occurred in the system because they could be reported in many different ways in the medical record. Review of some agency-controlled substance-administration records showed that patients with patella dislocation were being treated with opioid pain medications, as well as benzodiazepines in some cases. Internet searching revealed multiple protocols for reduction of patella in wilderness, austere and rural environments and prior articles about field patella reductions, but no articles demonstrating harm could be found. Since there was significant opportunity for benefit and no potential for harm, reduction of patella dislocations is now within the scope of practice of emergency medical technicians in New York state.

Patella dislocation reduction is a simple skill that can be performed by EMS providers in the field (if it’s within their scope of practice and allowed by their agency). This injury is easily recognizable, and dislocation reduction provides the patient substantial pain relief. As time passes while the bone remains out of place, swelling increases, and relocation becomes more difficult. BLS providers can perform this basic maneuver quickly before a significant amount of edema sets in, potentially eliminating the need for ALS pain control, avoiding unnecessary delays in transport and improving prehospital patient care.

Physiology and Pathophysiology

The patella is a sesamoid bone that covers and protects the anterior aspect of the knee joint and functions as a pulley for the quadriceps muscle. It articulates directly with the femur and serves as the attachment point for the quadriceps tendon superiorly. The patella slides up and down with flexion and extension of the knee joint and maximizes the force potential of the muscle. It is held in place inferiorly by the patellar tendon, while the medial and lateral patellofemoral ligaments provide in-line support to prevent lateral displacement.

Most patellar dislocations occur when there is simultaneous contraction of the quadriceps with the knee in a flexed position and rotation of the joint itself. This typically occurs when the femur rotates over a stationary tibia. This generates a strong directional force that dislodges the patella from its position in the patellofemoral groove. Less commonly a direct blow to the patella while the knee is flexed can also cause dislocation. Approximately 25% of these injuries are associated with a fracture. Most of these injuries are sports-related, and a majority occur in females. These injuries are often recurrent, and patients may report a prior history of patellar dislocation.

Patellar dislocations are usually clinically obvious. The patella will be noticeably absent from its usual position in front of the knee and will appear as a large swelling either medial or lateral to the joint. Patients will report that their knee suddenly gave out, followed by severe pain and swelling. The knee will be held in flexion, and the patient will be resistant to extending the knee and unable to bear weight on the leg.

Before deciding to perform a patellar reduction in the field, it is important to rule out other possible injuries to the knee that are not amenable to the same reduction technique. True knee dislocations, quadriceps tendon ruptures and patella fractures are less-benign injuries that can mimic patellar dislocation. Careful examination of the joint, as well as distal pulses, motor function and sensation is essential. At times identifying the true nature of the injury may be difficult if the patient has a significant amount of edema or tissue, either muscle or fat, around the knee.

Tibiofemoral (“true”) knee dislocation is an uncommon but significant injury that can result in damage to the popliteal artery and loss of blood supply to the lower leg. Knee dislocation is an orthopedic emergency. The tibia will appear out of alignment with the plane of the femur, and the joint will be unstable due to severe damage to the supporting ligaments. Like patellar dislocations, these will often spontaneously reduce and appear normal.

If the quadriceps tendon is disrupted, the patella will be “high-riding,” displaced above the knee joint in line with the femur. The patella will be palpable above its normal position over the joint. Similarly, a fracture of the patella itself may cause parallel displacement of the bone or a palpable divot over the joint. In most cases patella dislocation is easily differentiated from these injuries by lateral displacement of the kneecap. When in doubt, splint in the position of comfort and do not attempt a reduction.

After other injuries have been ruled out, preparing to manually reduce a patellar dislocation can begin with a physical exam. First assess for signs of neurovascular compromise. Palpate the posterior tibial and dorsal pedis pulses bilaterally and compare for symmetry. Ask the patient to wiggle their toes and ensure sensation is intact. Palpate the patella and feel for possible fracture of the bone. If there is any evidence of circulatory, neurologic or motor deficits, do not proceed with a reduction. If the patient’s body habitus does not allow for proper physical assessment, stop and immobilize the joint in the position found.

Once the physical exam is complete, the team can proceed with reduction. One provider will grasp the ankle on the affected leg and gradually extend the knee while a second provider applies steady, firm pressure on the patella toward the midline. The patella will pop back into position, and the patient will sigh with relief. The entire procedure should take less than 30 seconds. Some increase in pain should be anticipated during the procedure, but if the increased pain is severe or resistance is met, stop and splint in the position found. Once straight, the knee joint should be stabilized with a knee immobilizer or posterior splint. Again, check for neurovascular compromise and document your findings. Patients who have successful reduction on scene still require further assessment by a physician to rule out an associated fracture.

Conclusion

A healthy 24-year-old male collides with another player during a rugby match, receiving a direct blow from the other player’s knee to the lateral aspect of his knee. He immediately feels pain and is unable to bear weight on the affected leg. He says he’s dislocated the kneecap before and this feels similar. He lies on his back on the grass, grimacing in pain, his leg bent at the knee. There is a large swelling just medial to the knee joint.

Palpation of the swollen area reveals an intact patella with no grooves or movable fragments concerning for an underlying fracture. Distal pulses, motor function and sensation are intact and symmetrical bilaterally. The patient consents to a manual reduction by the BLS crew—he says his experience with this injury has shown him that putting the kneecap back into place alleviates his pain. The patella pops easily back into place with the crew’s help, and the patient sighs with relief. The leg is immobilized, and he is moved to the stretcher. He remains comfortable for the duration of transport.

Patella dislocation reduction is a simple procedure that can be easily performed by both basic and advanced life support personnel. Patients will receive prompt pain relief without the need for large doses of pain medication, allowing expedited transport. The introduction of this skill into the BLS protocols in New York provides EMTs an additional tool for providing better patient care in the field.

Find an educational video on patella dislocation and reduction from the author at https://www.emsworld.com/video/218850/patella-dislocation-and-reduction.

Michael W. Dailey, MD, FAEMS, is chief of the Division of Prehospital and Operational Medicine and an associate professor of emergency medicine at Albany Medical College in New York.