Next Lesson - Conditions of the Lower Leg
Core
Want more information on anatomy before you begin looking at conditions? Head to our articles on Bones of the Foot, Bones of the Lower Limb and Muscles of the Lower Leg!
Normally the talus (the ankle bone, which sits on top of the heel bone) sits firmly in a mortise (a bracket-shaped socket) formed by the tibia and fibula. The bony bumps at the ends of these two bones are the malleoli: the medial malleolus (inner ankle, on the tibia) and the lateral malleolus (outer ankle, on the fibula).
Because the talus is held in this socket, the direction and rotation of the force applied to the ankle lead to characteristic patterns of fracture:
- Eversion/external rotation injury. Eversion is turning the sole of the foot outwards, and external rotation is twisting the foot outwards. The talus is forced outwards against the lateral malleolus and breaks it. The same force pulls on the medial/deltoid ligament of the ankle. This medial/deltoid ligament can tear, or can pull off the medial malleolus, giving a bimalleolar fracture (a fracture of both malleoli).
- Inversion/internal rotation injury. Inversion is turning the sole of the foot inwards, and internal rotation is twisting the foot inwards. The force strains the lateral side of the ankle and can rupture the lateral ligament (or break the lateral malleolus). The medial malleolus is often fractured as well. The result can be a medial malleolus fracture with lateral ligament rupture, or a bimalleolar fracture if the lateral malleolus breaks too.
Diagram - X-ray of fracture of the lateral and medial malleoli. A fracture of both the lateral and medial malleoli is known as a bimalleolar fracture
Creative commons source by Steven Fruitsmaak [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Bimalleolar (medial and lateral malleoli) and trimalleolar (medial and lateral malleoli and posterior aspect of the tibia) fractures are commonly described by the malleoli involved. The historical term Pott’s fracture is variably defined, but usually means a bimalleolar or trimalleolar fracture, and is used less often in modern practice. A fracture of the lateral malleolus on its own is the most common type of ankle fracture (55% of ankle fractures in one large Danish study). A force applied in one direction often causes damage to the ligaments on the other side of the ankle. This happens because of talar shift (the talus moving out of its normal position), which can cause a fracture at the attachments of the ligaments.
Ankle fractures are diagnosed using x-rays, and the Ottawa ankle and foot rules (a checklist of examination findings) are used to decide who needs an x-ray. Treatment depends on whether the fracture is stable or unstable, which is judged on the x-ray. In a stable fracture, the talus stays in its normal position in the mortise and the joint space is not widened. In an unstable fracture, the talus has shifted or the space between the talus and the medial malleolus has widened. Stable fractures can usually be treated without surgery, in a boot or a cast. For a fracture of one malleolus treated without surgery, NICE advises immediate unrestricted weight-bearing as tolerated, which means walking on the ankle straight away, as far as pain allows. Unstable fractures often need surgical stabilisation (fixing the bones in place), and NICE advises considering surgery on the day of injury or the next day. Surgery can be high risk, especially in patients with diabetes or reduced blood supply.
An ankle sprain is a stretch, or a partial or complete tear, of one or more of the ankle ligaments. The mode of injury is usually excessive external rotation, eversion or inversion of the ankle.
The most common of these is an inversion injury of a plantarflexed (pointing downwards) and weight-bearing ankle (e.g. rolling the ankle in when running). This sprains the anterior talofibular ligament (a ligament on the outer side of the ankle, joining the lateral malleolus to the talus).
In a severe sprain, it is possible to get a secondary complication of a 5th metatarsal avulsion fracture. The 5th metatarsal is the long bone behind the little toe. An avulsion fracture is an injury where a piece of bone is pulled off at the point where a tendon or ligament attaches to it. At the base of the 5th metatarsal, the avulsion fracture is caused by the pull of fibularis brevis (a muscle on the outer side of the lower leg, whose tendon attaches there). It can also be caused by the pull of the lateral band of the plantar aponeurosis (a strong band of tissue under the sole of the foot). With non-surgical (conservative) management, pain from an ankle sprain usually falls quickly over the first 2 weeks. However, 5% to 33% of people still have pain 1 year after a sprain. Some people develop ongoing symptoms due to chronic ankle instability (the ankle repeatedly giving way) or persistent ligament injury, especially without proper rehabilitation (a programme of exercises). Anyone who is not improving as expected needs further assessment.
This refers to pain and dysfunction of the Achilles tendon (the combined tendon of the calf muscles, soleus and gastrocnemius, that inserts into the calcaneus, the heel bone). It is most commonly due to tendinopathy (a painful overuse injury of the tendon, in which inflammation may not be a feature). NICE Clinical Knowledge Summaries now call this Achilles tendinopathy, because the older term tendinitis suggests inflammation of the tendon. This article still uses the older term, tendinitis, in its headings.
Risk factors for Achilles tendinitis include:
- Over-training or unaccustomed use - “too much too soon”.
- A sudden change in training surface - e.g. grass to bitumen.
- Flat (overpronated) feet: the foot rolls inwards too much when walking.
- Some medicines, especially fluoroquinolone antibiotics (a group of antibiotics that includes ciprofloxacin) and corticosteroids (steroid medicines). The risk is higher in people over 60 and when both are taken together. A fluoroquinolone should be stopped at the first signs of tendon pain.
Achilles tendinitis is mostly divided into 2 types (NICE CKS also describes a smaller group, about 15% of cases, called proximal tendinopathy, which affects the part of the tendon closest to the calf muscle):
- Non-insertional tendinitis (involves fibres of the middle portion of the tendon) - the most common type (about 55 to 60% of cases), seen especially in active people such as runners
- Insertional tendinitis (involves fibres at the point where the tendon inserts into the calcaneus, the heel bone) - about 20 to 25% of cases, and more likely with increasing age
Patients present with pain and stiffness at the back of the ankle that worsens with activity, and sometimes thickening of the tendon.
Treatment is easily remembered by the mnemonic RICE:
- Rest
- Ice
- Compression
- Elevation
An Achilles tendon rupture is a complete or partial tear of the Achilles tendon.
Rupture is most common in middle-aged people and often occurs during recreational sport. People who play sport only occasionally are often called ‘weekend warriors’. However, it is important to remember that it can occur at any age. Tendinopathy can lead to rupture, but most people with a complete rupture have had no earlier Achilles symptoms. Fluoroquinolone antibiotics, especially when taken with corticosteroids, also increase the risk of tendon rupture.
A complete tear is more common than a partial tear and patients often experience sudden pain and a popping/snapping sensation. They may have pain, swelling and a gap in the tendon that can be felt (a palpable gap). The gap may be felt in the first few hours after the rupture, but it is not always present because swelling can hide it.
Diagnosis is usually made on examination, for example with the Simmonds-Thompson test. The patient lies face down on the bed with their feet hanging off the edge. The examiner then squeezes the calf. If the Achilles tendon is intact, the foot moves at the ankle (it plantarflexes, which means it points downwards). If the tendon is completely torn, the foot typically stays still: this is a positive test, and it was found in 96% of people with a complete rupture in one study of 174 people. If the tendon is only partly torn, the foot may still move, so a normal result does not rule out a partial tear (in one study on cadavers, bodies donated for research, the foot still moved after up to three-quarters of the tendon had been cut). Ultrasound or MRI scans can also be used to view the tendon. A suspected rupture needs same-day referral to orthopaedics (the bone and joint surgery team) or admission, depending on the local referral pathway (the process each hospital has agreed).
Treatment can be non-surgical or surgical, and the best choice is still debated. Non-surgical treatment uses a cast or a walking boot (used to keep the ankle plantarflexed, pointing downwards, for the first few weeks). In a UK trial called UKSTAR (UK Study of Tendo Achilles Rehabilitation), early weight-bearing in a functional brace (a brace that allows earlier movement) gave results as good as a plaster cast. Surgery lowers the risk of the tendon rupturing again a little (in one large review, about 2 in 100 people after surgery and about 4 in 100 without), although the difference was not clear in studies that used early movement during rehabilitation. Surgery carries more risk of other complications, mainly infection, and sometimes nerve injury. In the same review, any complication occurred in about 5 in 100 people after surgery against about 2 in 100 without. In open surgery, the surgeon makes a cut (incision) in the back of the lower leg and stitches the torn tendon together. Minimally invasive repair, which uses smaller cuts, is also used. Physical therapy (physiotherapy) follows either treatment, and the tendon can take many months to heal.
Reviewed by: Dr. Marcus Judge
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