Axis (C2) Fracture

The axis is built around its upward peg, the odontoid, which fits inside the ring of the atlas above and is held snugly against it by the transverse ligament. This arrangement lets the head rotate while keeping the spinal cord protected. Behind the body of the axis is a ring of bone through which the cord passes. Understanding this layout explains the main fracture types: those through the peg, those through the ring, and those through the body.

The most common is an odontoid (peg) fracture. These are grouped by where the break occurs: near the tip, through the base of the peg where it meets the body, or extending down into the body itself. The break through the base is the most common and the most likely to have trouble healing. A second important type is the "hangman's fracture", a break through the ring of the axis on both sides, which is covered in more detail on our traumatic spondylolisthesis page. Fractures of the axis body make up the remainder. Identifying the exact type is central to deciding treatment.

In younger people, axis fractures usually result from high-energy trauma such as road traffic collisions and falls from height. In older people — in whom odontoid fractures are especially common — the injury frequently follows a low-energy fall from standing height, often with the head forced backwards or forwards. The rising number of these injuries in older adults reflects both an ageing population and the effect of weaker bone.

The usual symptom is pain high in the neck and at the base of the skull, with stiffness and a reluctance to move the head. In older people the injury can be surprisingly subtle, sometimes with only modest pain despite a significant fracture. The spinal cord is often spared, but any weakness, numbness or difficulty with breathing or swallowing is important and is carefully assessed.

Neck pain after a fall or collision — particularly in an older person — should be assessed, and the neck kept still until a serious injury has been excluded. Warning signs needing immediate attention include weakness or numbness in the limbs, problems with balance, and any difficulty breathing or swallowing. Because the injury is at the top of the neck, close to vital structures, careful and prompt assessment is essential, and a "normal" appearance should not lead to complacency in older patients.

A CT scan is the key investigation, showing the fracture and how far the fragments have moved. Plain X-rays can miss odontoid fractures, especially in older people, so a low threshold for CT is important. An MRI scan assesses the ligaments and the spinal cord and helps to judge stability. The precise fracture type, the gap between the fragments and their alignment all feed into the treatment decision.

Many axis fractures can be treated without surgery. Stable fractures — for example many tip fractures and those extending into the body — are usually managed in a rigid collar or brace for a period of weeks while the bone heals. Some fractures through the base of the peg are also treated non-surgically, particularly where surgery carries higher risks, though these have a greater tendency not to heal fully. Follow-up imaging monitors healing and alignment.

Surgery is considered for unstable fractures, for fractures that are significantly displaced, and for some base-of-peg fractures with a higher risk of non-union. Operations may involve a single screw placed up through the peg to hold it, or fixation and fusion of the top two vertebrae from behind. In older patients, the decision between a brace and surgery is finely balanced, weighing the higher non-union rate of brace treatment against the risks of an operation, and is made individually. Guidelines acknowledge that the evidence does not point to a single best answer for every patient.

Most axis fractures ultimately do well, though the path varies with the fracture type and the treatment. Base-of-peg fractures are the most likely to have difficulty healing, and sometimes a fracture that does not fully knit together still causes few symptoms if it remains stable. Some lasting reduction in neck rotation can remain, reflecting the specialised role of the top of the neck. In older patients, overall health has a major influence on recovery, and care is tailored accordingly.

The main concern with odontoid fractures is non-union — failure of the peg to heal — which can leave instability. Other potential issues include residual neck stiffness and the specific risks of a halo, a brace or surgery. In frail older patients, the complications of immobility and of any operation are weighed carefully. Regular follow-up imaging helps detect problems early.

Myth: "A neck fracture in an older person is obvious." Fact: Odontoid fractures can be subtle, with only modest pain, so a careful assessment and CT are important.

Myth: "Every axis fracture needs surgery." Fact: Many are treated successfully in a collar or brace; surgery is reserved for unstable or displaced fractures.

Myth: "If a fracture doesn't fully heal, it must be fixed." Fact: A stable non-union can sometimes cause few symptoms, though it is monitored; treatment is individualised.

This page is for general education and does not replace an individual assessment. Treatment depends on a person's specific symptoms, examination findings, imaging findings and overall health, and should always be discussed with a suitably qualified healthcare professional.

The axis, or C2, is the second bone of the neck and one of the most important. Projecting upwards from its body is a peg of bone called the odontoid process (or dens), around which the atlas (C1) and the skull rotate — this is what allows you to turn your head from side to side. A fracture of the axis usually involves this peg, but it can also involve the ring of bone behind it or the main body. Axis fractures are among the most common fractures of the neck, and odontoid fractures in particular are now the single most frequent cervical spine fracture in older people, often after a relatively minor fall. This page explains the types of axis fracture, how they are assessed, and how they are treated.

• —Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am. 1974;56(8):1663-1674. (PMID: 4434035)
• —Ryken TC, Hadley MN, Aarabi B, et al. Management of isolated fractures of the axis in adults. Neurosurgery. 2013;72 Suppl 2:132-150. doi:10.1227/NEU.0b013e318276ee40
• —Grauer JN, Shafi B, Hilibrand AS, et al. Proposal of a modified, treatment-oriented classification of odontoid fractures. Spine J. 2005;5(2):123-129. doi:10.1016/j.spinee.2004.09.014
• —Vaccaro AR, Kepler CK, Kopjar B, et al. Functional and quality-of-life outcomes in geriatric patients with type-II dens fracture. J Bone Joint Surg Am. 2013;95(8):729-735. doi:10.2106/JBJS.K.01636
• —Smith HE, Kerr SM, Maltenfort M, et al. Early complications of surgical versus conservative treatment of isolated type II odontoid fractures in octogenarians: a retrospective cohort study. J Spinal Disord Tech. 2008;21(8):535-539. doi:10.1097/BSD.0b013e318163570b
• —Bransford RJ, Alton TB, Patel AR, Bellabarba C. Upper cervical spine trauma. J Am Acad Orthop Surg. 2014;22(11):718-729. doi:10.5435/JAAOS-22-11-718
• —Chapman J, Bransford R. Geriatric spine fractures: an emerging healthcare crisis. J Trauma. 2007;62(6 Suppl):S61-62. doi:10.1097/TA.0b013e318065ae60
• —Joaquim AF, Patel AA. Surgical treatment of Type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion? Neurosurg Focus. 2015;38(4):E11. doi:10.3171/2015.1.FOCUS14781
• —Robinson AL, Möller A, Robinson Y, Olerud C. C2 Fracture Subtypes, Incidence, and Treatment Allocation Change with Age: A Retrospective Cohort Study of 233 Consecutive Cases. Biomed Res Int. 2017;2017:8321680. doi:10.1155/2017/8321680
• —National Institute for Health and Care Excellence (NICE). Spinal injury: assessment and initial management. NICE guideline NG41. 2016. https://www.nice.org.uk/guidance/ng41
• —Hsu WK, Anderson PA. Odontoid fractures: update on management. J Am Acad Orthop Surg. 2010;18(7):383-394. doi:10.5435/00124635-201007000-00001
• —Ryken TC, Hadley MN, Aarabi B, et al. Management of acute combination fractures of the atlas and axis in adults. Neurosurgery. 2013;72 Suppl 2:151-158. doi:10.1227/NEU.0b013e318276ee55
• —Guideline note (place near references): The Congress of Neurological Surgeons / AANS "Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries" (2013) and NICE NG41 were reviewed. AAOS-affiliated review literature (JAAOS) informed the management discussion. No stand-alone AAOS clinical practice guideline specific to axis fractures was identified at the time of writing.

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.