Repair and Management of Knee Dislocation with Associated Popliteal Artery Injury and Peroneal Nerve Injury
First-Place Article, 2015 Paper of the Year Competition

by Kellyn S. Hood, OTC

Introduction
Knee dislocation with a popliteal artery injury is uncommon (1). According to studies, an injury involving a knee dislocation accounts for less than 1% of extremity injuries (1,2), and associated vascular compromise injury accounts for 30% of knee dislocation injuries (1,2,4). Significant complications are associated with knee dislocations that involve cruciate and collateral ligament disruption, and also can involve limb-threatening vascular injuries (2). The popliteal artery is extremely susceptible to injury with associated knee dislocations, due to the limited mobility of the artery (2).

This case report will discuss a 43 year old male who had delayed treatment for a knee dislocation with associated popliteal artery injury, as well as peroneal nerve injury and multi-ligamentous damage.

Case Report

A 43 year old male presented to the emergency department, at 5:00 PM, after sustaining a fall while running on wet grass towards a “slip n slide”. He reported that he hyperextended his right knee, and fell on top of it when he slipped on the grass. He was immediately unable to bear weight on his leg. He presented, initially, with a blood pressure of 71/43 mmHg, weakness in his foot, and numbness to his lateral calf. He denied any syncopal episodes, loss of consciousness, or head trauma. Special tests conducted included negative anterior drawer, negative x-ray of his right ankle, and negative x-ray of his right knee. He was given crutches and a knee immobilizer. While attempting to mobilize in crutches, he became light-headed. He was given something to eat and pain medication, and was discharged home at 6:43 PM.

At 11:08 PM, the same day, patient returned to the emergency department for continued light-headedness and poor pain control. Pain was described, by the patient, as localized to the knee and sharp in nature. Upon re-arrival to the emergency department, blood pressure was 124/70 mmHg. Patient presented with the right knee swollen and tender to palpation along the lateral aspect of the leg. His right leg, distal to the knee, was cold to touch, with a faint peripheral dorsalis pedis pulse, compared bilaterally. Patient was unable to move his leg due to pain and weakness in the leg. Special testing included a CT scan that was performed, which revealed a vascular flow cutoff to the lower leg. There was a 5cm segment of acute occlusion of the popliteal artery, which extended proximal to the trifurcation of the popliteal artery. Patient was then transferred to the care of vascular surgeons, immediately, for treatment to include surgery. Final diagnosis included right knee dislocation with popliteal artery injury, peroneal nerve injury, and lateral collateral ligament damage.

Patient was taken urgently to surgery at 5:00 AM for exploration of a right popliteal artery occlusion, and primary repair of right popliteal artery dissection with a Dacron patch. At the completion of the surgery, there was a palpable posterior tibial pulse, and there were no immediate complications noted.

At four days post-operative, patient was discharged to home. He was not cleared to resume work responsibilities, and was to remain non-weight bearing on his right leg at all times, as well as keep a full leg length immobilizing brace on at all times. Home health physical therapy was ordered.

Follow up with vascular surgeon, at 18 days post operation, revealed a well healing incision, no drainage or erythema, and palpable pedal pulse in his right foot. Patient was released for surgery with Orthopedics, should the need arise due to extensive ligamentous damage.

Follow up with Orthopedics revealed MRI results of the right knee. MRI revealed anterior cruciate ligament tear, posterior cruciate ligament tear, slight tear in the posterior horn of the medial meniscus, lateral collateral ligament tear, non-displaced fracture of the anterior medial tibial plateau, extensive bone bruise of the medial femoral condyle, and a large joint effusion. Patient was to continue immobilization for six more weeks, and at that point therapy for peroneal nerve palsy would be initiated. Early surgical reconstruction of the knee was not indicated secondary to recent vascular surgery.

At six weeks status post injury, patient still was unable to dorsiflex ankle and great toe on right leg, so EMG/NCS was ordered for the right lower extremity to evaluate peroneal nerve injury. At this point, patient could start decreasing use of crutches and start increasing the range of motion with the TROM brace. At 12 weeks post injury, there still was very minimal strength with ankle and great toe dorsiflexion. Patient discontinued using the TROM brace and moved to a functional brace. He continued with physical therapy, and was cleared to return to work with restrictions.

Between 4 and 6 months post injury, there were very minimal changes in the EMG/NCS. At 8 months post injury, he was still showing very little signs of improvement with the EMG/NCS. He was cleared to return to full duty, without restriction, with use of AFO and brace.

Patient continued to use his AFO and functional brace. He was then referred to a foot and ankle surgeon for further management of the peroneal nerve palsy. At one-year post injury, patient still does not show any signs of nerve re-innervation. At this point, the foot and ankle surgeon has given the patient two choices. Wear a brace for life, or proceed with a tendon transfer. However, the tendon transfer may not completely alleviate the need for long-term bracing.

Discussion
Due to the extensive nature of this patient’s injuries, there were multiple facets of care that needed to be addressed. The first, and primary approach was to surgically fix the artery and remove the occlusion. Patients who have a popliteal artery injury have a much higher risk of amputation compared to other arterial injures (3), and a higher risk of morbidity or mortality when injuries to other tissues and body systems occur (3). Shock generally presents with active external bleeding, or large hematoma, and requires prompt attention to decrease the chance of a poor prognosis (3). Shock indicates an immediate need for prompt revascularization (3). Open revascularization procedure is still the accepted treatment for the majority of extremity vascular trauma (1). There are clearly risks and disadvantages associated with open revascularization, which include, but are not limited to the need for a larger incision, longer recovery time, and possibility of infection.

Management of the ligamentous injuries was secondary to stabilizing the popliteal artery injury. This patient had extensive ligamentous damage to his knee, and initially surgery was not recommended due to vascular injury. As of two weeks post-operative from the popliteal artery injury, patient was cleared for surgery with Orthopedics by the vascular surgeon, but Orthopedics deferred the surgery due to the recent vascular compromise. Additionally, the patient deferred surgery and wished to continue using the functional brace, which he was given at three months post injury. The patient was functioning at an acceptable level with activities of daily life with his AFO brace and functional brace, as of three months post injury.

Time is a major component with patients who are suspected of having a knee dislocation. Knee dislocations, or suspected knee dislocations, require prompt evaluation, consultation, and treatment (4). The patient discussed in this report presented with low blood pressure, numbness along his leg, and a history of a hyperextension injury to his right knee. Time was of the essence with this injury. While the outcome may not have been different if there was suspicion of a vascular injury with the initial presentation to the emergency department, there is a chance the patient could have deteriorated quicker or had more permanent damage than he did before his later visit to the emergency department. This is why it is crucial to suspect vascular injury or knee dislocation when a patient presents with potential symptoms of shock, history of a hyperextension injury, and decreased sensation to the affected leg.

Peroneal nerve injuries are secondary to trauma, which includes lacerations, dislocations, and fractures (5). To this date, this patient continues to have a peroneal nerve palsy, with very minimal regeneration of the nerve. This patient has been asked to consider a tendon transfer in the future.

About the Author:
Kellyn Hood, OTC, graduated from East Stroudsburg University in 2008 with a BS in Athletic Training Sports Medicine. After spending a year working as an Assistant Athletic Trainer, she returned to her hometown to join Wellspan Orthopedics upon their inception in 2009. Kellyn became a certified Orthopedic Technologist in 2011. She started her journey of attaining a MBA in Healthcare Management in 2013. At Wellspan Health, in addition to being a Certified Orthopedic Technologist, Kellyn also enjoys providing education to other staff members.

When Kellyn is not being creative in the Orthopedic world, she is being creative as an avid line dancer and Mama to her beautiful three year old daughter. All of these things, combined, keep her young at heart so she can keep up with the demands of life.

Kellyn’s favorite quote to live by is “Today I will delete from my diary two days: Yesterday was to learn, and tomorrow will be the consequence of what I can do today”. Author unknown.

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