Ankle Fractures:
Cast, Boot or Surgery?

Anatomy of the ankle joint

The ankle joint is formed where the lower ends of the two leg bones — the tibia (shinbone) and the thinner fibula on the outer side — wrap around the top of the talus, a foot bone. The bony bumps you can feel on each side of the ankle are the malleoli: the medial malleolus (inner, part of the tibia) and the lateral malleolus (outer, the end of the fibula). The back edge of the tibia is sometimes called the posterior malleolus. Together they form a snug socket, often called the mortise, held together by strong ligaments — including the syndesmosis, the band of ligaments that binds the tibia and fibula together just above the joint.

Doctors describe ankle fractures by how many malleoli are broken (unimalleolar, bimalleolar or trimalleolar) and, for the outer bone, where the fibula breaks relative to the syndesmosis. In the widely used Weber classification, a Weber A fracture is below the joint line, Weber B is at the level of the joint, and Weber C is above it, where syndesmosis injury is more likely. In Japanese the injury is usually called sokukansetsu kossetsu (足関節骨折) or kabu kossetsu (果部骨折).

Who gets it and how

Ankle fractures occur at all ages, but their pattern changes over a lifetime. In a survey of 1,500 adult ankle fractures seen over three years at the Edinburgh Orthopaedic Trauma Unit, the highest age-specific incidence was in women aged 75 to 84. Isolated malleolar fractures — most often of the lateral malleolus — made up two thirds of the series, bimalleolar fractures about a quarter and trimalleolar fractures 7%; open fractures were 2% (Court-Brown et al., Acta Orthopaedica Scandinavica, 1998).

The typical mechanism is the foot twisting while the body's weight is on it — most commonly the foot turning outward or rolling inward. In younger people this often happens in sport or a fall; in older people, a simple trip at ground level is enough, especially when bone density is reduced. Ankle fractures in older women can be one of the signs that a bone health assessment is worthwhile.

Sprain or fracture? Symptoms and when an X-ray is needed

A sprain and a fracture can look very similar: pain, swelling and bruising around the ankle. Features that make a fracture more likely include tenderness directly over the bone (rather than over the soft ligaments in front of it), an inability to put weight on the foot, and visible deformity.

To avoid both missed fractures and unnecessary X-rays, many emergency doctors use the Ottawa ankle rules. In short, an ankle X-ray is recommended if there is pain around the malleoli and either bone tenderness along the back edge or tip of either malleolus, or an inability to take four steps both straight after the injury and at the time of examination. Similar rules cover the midfoot.

Diagnosis: stable or unstable?

Standard X-rays of the ankle (front, side and "mortise" views) show most fractures. The most important judgement is whether the fracture is stable. In a stable fracture the talus stays centred under the tibia, and the ankle can usually be treated without an operation. In an unstable fracture, the ligaments or bone on both sides of the joint are disrupted, and the talus can shift out of position — even a small shift changes how load is carried across the joint and may increase the risk of later arthritis.

To judge stability, doctors may compare the gap on the inner side of the joint, take X-rays while the patient stands (weight-bearing views), or perform a stress X-ray. A CT scan is commonly used for complex fractures, especially those involving the posterior malleolus, to plan treatment. MRI can help when ligament or cartilage injury is suspected. A fracture high up the fibula near the knee combined with an inner ankle injury (sometimes called a Maisonneuve injury) can be missed if only the ankle is X-rayed, which is one reason the whole leg is examined.

Treatment options

The choice depends mainly on stability, but also on age, bone quality, skin condition, diabetes or nerve problems in the feet, smoking, activity demands and personal preference. The table below is a simplified overview; individual decisions are made with the treating surgeon.

Fracture pattern	Usual first approach	When surgery is considered
Stable, isolated outer ankle (e.g. many Weber B)	Walking boot, brace or cast; weight-bearing as comfort allows	Rarely; mainly if later X-rays show the joint shifting
Small avulsion / Weber A	Treated much like a sprain, with a brace or boot	Rarely
Unstable (bimalleolar, trimalleolar, or with talar shift)	Surgery (plates and screws) in most fit adults	Commonly; close contact casting may be an alternative for some older adults
Syndesmosis injury (often Weber C)	Depends on whether the tibia and fibula separate under stress	When the syndesmosis is unstable; fixed with screws or a suture-button device
Open fracture or dislocation	Emergency realignment, antibiotics and surgical care	Always requires urgent specialist treatment

Non-operative treatment for stable fractures

For decades, stable ankle fractures were treated in a below-knee plaster cast for about six weeks. Several trials have now tested whether lighter or shorter immobilisation works as well — which matters for people who need to commute, work and climb stairs.

A removable boot allows washing and gentle movement, but it also relies on the patient wearing it as instructed. Follow-up X-rays in the first one to two weeks are usually advised to confirm that the fracture remains stable.

Surgery for unstable fractures

The standard operation is open reduction and internal fixation (ORIF): the broken bones are realigned through an incision and held with plates and screws, and an unstable syndesmosis is stabilised with screws or a suture-button device. The aim is to restore the talus to its correct position in the mortise so the bone can heal in a good alignment. Surgery may be delayed for several days while severe swelling settles, to reduce wound problems. Risks include wound infection or breakdown, irritation from the metalwork (sometimes leading to removal), nerve irritation around the scar, and blood clots.

For older adults, whose skin and bone are more fragile, surgery carries a higher rate of wound complications. This led to a large trial of an alternative.

Older adults, unstable fracture	Close contact cast	Surgery (ORIF)
Function at 6 months	Equivalent on average in the AIM trial
Wound infection / breakdown	Less common	More common
Healing in imperfect position	More common on X-ray	Less common
Other points	Needs specific casting skill; about one in five later converted to surgery	Operative and anaesthetic risks; possible metalwork removal

Recovery and rehabilitation

Bone healing in the ankle typically takes around six weeks or more, but regaining full strength, balance and confidence often takes several months. Swelling at the end of the day can persist for many months, particularly after surgery.

Traditionally, patients were told not to put weight on the ankle for six weeks after surgery. That advice has been tested directly.

Many people wonder whether formal physiotherapy is needed once the cast or boot comes off. For uncomplicated fractures, the answer may be "not always".

Practical points that commonly come up in Tokyo: driving is generally not advised while wearing a cast or boot on the right leg (check with your doctor and insurer); commuting on crowded trains and long station staircases can be hard for several weeks, so plan for a seat, elevators, or remote work where possible; and return to running, jumping and pivoting sports usually takes several months, guided by the treating team. Calf swelling, pain or redness — or sudden breathlessness — can be signs of a blood clot and need urgent assessment.

Long-term outlook

Most people with ankle fractures return to their normal activities. Some have persistent stiffness, swelling or aching for a year or longer, and a minority — more often after severe fractures involving the joint surface or the posterior malleolus — develop post-traumatic arthritis of the ankle years later. Keeping a healthy weight, regaining calf strength and balance, and addressing bone health in older adults are sensible steps after any ankle fracture.

When to see a doctor

After a twisting injury, see a doctor if you cannot take four steps, if the bony edges of the ankle are tender, or if pain and swelling are not improving after a few days. Go to an emergency department immediately for deformity, an open wound, or a numb or cold foot. In Japan, an orthopaedic clinic (整形外科) can usually take X-rays the same day; if the fracture is unstable or involves the syndesmosis, ask about referral to an orthopaedic trauma or foot and ankle surgeon. Bring any X-ray images or reports if you were first seen elsewhere.