What It Is: A double crush injury occurs when a nerve is compressed at multiple sites along its path. It is believed that an injury at one segment of the nerve may weaken the nerve as a whole and allow for additional injury at a distant site.1 Common sites of double crush injury in the lower leg include 1) the nerve root as the nerve exits the spinal canal in the low back and 2) the tibial nerve as it courses around inner part of the ankle which is called tarsal tunnel syndrome.
How It Happens: Double crush injury may occur in response to low back pain (acute or chronic) caused by pinching of the lumbar nerve root next to the spinal cord.2 The lumbar nerve root injury may lead to compression of any of the nerves farther down in the leg and affect the hip, knee, or ankle.3 In other words, an injury which is originally caused by nerve compression or stretching close to the spinal cord may result in subsequent injury to the nerves farther down the leg. The two areas of involvement result from the same initial site of injury.4 Many patients with tarsal tunnel syndrome present initially with pain, numbness, tingling, or weakness in the ankle or foot despite not sustaining an injury to the ankle itself.5
Presentation and Causes of Tarsal Tunnel Syndrome: Most patients who have tarsal tunnel syndrome may initially complain of pain or numbness in the foot, changes in sensation along the bottom of the foot, or muscle changes if the first 4 toes.6 This could affect how an individual walks or runs. Nerve involvement might also impact an individual’s standing tolerance. Aside from the compression closer to the spinal cord, factors that may contribute to tarsal tunnel syndrome including flat feet, a sprained ankle, or tendonitis. Sometimes, patients may present with low back pain, sciatica-like symptoms with pain in the rear end, or pain down the entire leg.
Diagnosis: A diagnosis of tarsal tunnel syndrome requires a thorough subjective history and clinical exam. X-rays and MRI may be taken of the ankle and/or the low back. Often, an EMG will be prescribed to identify where the problems are along the nerve pathway.
Management: Often double crush injuries are initially treated with conservative measures that focus on reducing irritation to the nerve as it travels down the leg. Your podiatrist may prescribe physical therapy. Weil Foot and Ankle Institute’s in house physical therapists, who are experts at foot and ankle conditions, address both the back and ankle sources of the symptoms. Physical therapy may include techniques to reduce inflammation, improve ankle stability, and strengthen the abdominal and rear end muscles to reduce stress on the low back. If physical therapy does not fully resolve the tarsal tunnel syndrome symptoms, the podiatrist may recommend a surgical procedure to relieve compression at the ankle. In this procedure, the surgeon will decompress the tarsal tunnel to allow more space for the nerve, blood vessels, and tendons. Lumbar injections may also be suggested to reduce inflammation at the nerve root.
If you have concerns that you may have symptoms of tarsal tunnel syndrome, please reach out to the Weil Foot and Ankle Institute podiatrists. They have the tools to properly diagnose and treat tarsal tunnel syndrome so that you do not need to continue to suffer.
- Kane, Patrick M. MD; Daniels, Alan H. MD; Akelman, Edward MD Double Crush Syndrome, Journal of the American Academy of Orthopaedic Surgeons: September 2015 – Volume 23 – Issue 9 – p 558-562.
- Jacob JR, Rao JP, Ciccarelli C: Traumatic dislocation and fracture dislocation of the hip: A long-term follow-up study. Clin Orthop Relat Res 1987;214:249–263.
- Fassler PR, Swiontkowski MF, Kilroy AW, Routt ML Jr: Injury of the sciatic nerve associated with acetabular fracture. J Bone Joint Surg Am 1993;75(8):1157–1166.
- Golovchinsky V: Double crush syndrome in lower extremities. Electromyogr Clin Neurophysiol 1998;38(2):115–120.
- Augustijn P, Vanneste J: The tarsal tunnel syndrome after a proximal lesion. J Neurol Neurosurg Psychiatry 1992;55(1):65–67.
- Cimino WR. Tarsal Tunnel Syndrome: Review of the Literature. Foot & Ankle. 1990;11(1):47-52.