Written by Bob Baravarian, DPM, FACFAS and Sydney K. Yau, DPM
Lateral column pain is a fairly common occurrence after an injury such as a sprained ankle or twisting injury to the foot. Accordingly, let us consider a case study of a healthy 34-year-old female, who twisted her foot on a sidewalk curb while wearing heels. She did not feel much pain at that time but the next day, her foot became very swollen and she presented to the emergency room for treatment. X-rays of the foot and ankle were negative at the emergency room. The physicians in the ER put the patient in a splint, gave her crutches and asked her to follow up with her doctor.
The patient subsequently felt better over the next few days and did not end up following up with a doctor. Three weeks later, the patient began increasing her activity and noticed that her foot began to swell again and became very tender. She had the most tenderness when she put weight on the foot. However, she did feel some soreness in the lateral aspect of her foot, even when she was sitting. She presented to the office for evaluation three weeks after the original injury occurred.
What The Diagnostic Workup Revealed
The patient presented with a mildly swollen and warm foot with no ecchymosis present. There was pain on direct palpation to the cuboid on the lateral side of the foot. There was no pain on palpation to the styloid process, the anterior process of the calcaneus, lateral or medial malleoli, or navicular tuberosity. The patient had no pain on palpation at the Lisfranc ligament and no pain on stress to the tarsometatarsal joints or midtarsal joint. There was no pain upon palpation along the lateral collateral ligaments and we noted there was no ankle instability.
There was a negative anterior drawer test on the ankle. There was pain along the peroneal tendons in the lateral calcaneus region without signs of gross weakness. She had good strength to all four quadrants of the lower extremity with no pain on resistance to these muscle groups. She had a collapsing medial longitudinal arch with weightbearing along with mild abduction of the forefoot and slight valgus of the heels.
Three weeks after the injury, radiographs showed no obvious fracture or dislocation of the foot or ankle. Incidentally, there was an os peroneum, which was well corticated but had multiple small fragments associated with the actual os peroneum region. The actual os peroneum was in an abnormal position against the cuboid and sitting very close to the cuboid in proximity. There was also a potential lateral cuboid stress fracture in the central portion of the cuboid that we noted on the radiographs. The patient’s overall alignment was stable.
A Closer Look At The Differential Diagnosis Possibilities
The patient’s symptoms and exam reveal an asymptomatic ankle and medial column of the foot. The patient has lateral column foot pain. The following differential diagnoses are possible causes of this patient’s pain.
Anterior process calcaneal fracture. This is a common avulsion fracture, which occurs from a twisting injury to the foot or ankle. A medial oblique radiograph is the best view to obtain an unobscured view of this area. A computed tomography (CT) scan or magentic resonance image (MRI) may be helpful as well.
In the case of this patient, the anterior process of the calcaneus was intact. In cases of an anterior process calcaneal fracture, clinicians can pursue boot immobilization to facilitate healing of the fracture. If the area continues to cause pain, one may excise the fracture fragment surgically.
Peroneal tendon pathology. With a lateral ankle sprain, the peroneus brevis tendon is more often involved. The patient often will present with pain on palpation along the peroneal brevis tendon and the posterior fibular groove. They may also present with pain at its insertion into the styloid process of the fifth metatarsal base. The peroneus longus may also tear but this is far less common unless one notes an os peroneum. An ultrasound is often very useful in evaluating the peroneal tendons dynamically. A MRI is also useful in differentiating if there is a tear in the tendon or if it is a tendonitis.
Treatment for peroneal tendonitis involves physical therapy and bracing. Peroneal tendon tears often do not get better with conservative therapy and surgical repair of the tendon is often indicated. It is important to evaluate the ankle in cases of peroneal tendon pathology. An unstable ankle may be the cause of peroneal pathology and a repair of the peroneal tendon tear without addressing lateral ankle instability will likely fail in the long term.
In this case, the patient had a stable ankle with no pain along the course of the peroneal tendons or at the insertion of the peroneal brevis. There was no swelling along the peroneal tendons either.
Painful os peroneum. An os peroneum is a small round accessory ossicle, which is located within the substance of the peroneus longus tendon near the cuboid. It is present in approximately 26 percent of feet. With the presence of a well corticated os peroneum, it is unlikely that the ossicle itself was fractured. However, it is possible that the patient tore the peroneus longus tendon near the os peroneum. If there is a peroneus longus tendon tear, there may be a distal or proximal migration of the os peroneum after the injury, depending on where the tendon tore. A frank rupture of the peroneus longus tendon may show a more dramatic change in the location of the ossicle. Unfortunately, no films were available of her foot before the injury.
Treatment for this injury involves physical therapy and bracing. Occasionally, the patient may have to go on to repair of the peroneus longus tendon with excision of the ossicle. This patient did not have any pain upon palpation along the peroneus longus tendon and had good strength on resistance to the peroneus longus. Accordingly, it is unlikely that the os peroneum was injured. If the patient continues to be symptomatic after immobilization, MRI may be useful in identifying a peroneus longus tear, which may be non-painful if it is fully torn.
Cuboid syndrome/cuboid stress fracture. Cuboid syndrome presents with pain due to subluxation of the calcaneocuboid joint. This can often be a minor subluxation. One may not readily appreciate this on X-ray and this is often a clinical diagnosis. Often, the pain is pronounced with weightbearing, walking or heavy activity in patients with a pronated foot type due to the additional strain on the joint with abduction of the forefoot on the rearfoot.
The more common injury is a cuboid stress fracture, which occurs when the forefoot is abducted on the rearfoot, causing the cuboid to be constantly compressed. This may be visible on radiographs as a hairline fracture or possible lateral cuboid compression fracture with the cortex showing a small break. One may obtain a MRI to evaluate the area more closely. Edema in the cuboid may indicate a stress fracture or a stress reaction. Treatment for a stress fracture or stress reaction in the cuboid includes immobilization of the foot and ankle with a controlled ankle motion (CAM) walker.
We believed this particular patient had a stress reaction to her cuboid. We had her use a CAM walker for four weeks and begin physical therapy three weeks after presenting to the office. We utilized a custom functional orthotic to help stabilize the position of her foot and returned to her regular activity without any complications six weeks after she presented to the office.
Lateral column pain can be difficult to diagnose. There are many causes of lateral foot pain and a good knowledge of the anatomical structures present on the lateral column foot is helpful in determining an accurate diagnosis.
Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Chief of Podiatric Foot And Ankle Surgery at the Santa Monica UCLA Medical Center and Orthopedic Hospital, and is the Director of the University Foot and Ankle Institute in Los Angeles.
Dr. Yau is a Fellow at the University Foot and Ankle Institute in Los Angeles.
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