1 Anatomical considerations (a): The talus plays a key role in no less than 3 joints: (1) the ankle joint – articulating with the tibia and fibula; (2) the subtalar joint – articulating with the calcaneus. (3) the talonavicular joint: along with the calcaneocuboid joint, this forms the midtarsal joint. Secondary osteoarthritic changes may occur following fractures which cause articular irregularity.

2 Anatomical considerations (b): Secondary osteoarthritis may also follow avascular necrosis which occurs in half of all talar neck fractures. The blood supply of the talus enters at three sites: (1) the neck; (2) the sinus tarsi area; (3) the medial side of the body. The more sources are disturbed, the greater is the risk to the blood supply.

3 Mechanisms of injury: The commonest fracture is of the neck. This may occur in car accidents, when pedal impact (1) forces the talar neck against the tibial margin (2). (There is a long association between this injury and light aircraft crashes where the feet are violently dorsiflexed against the rudder pedals – ‘aviator’s astragalus’.) The injury may also follow falls from a height in a crouching position.

4 Classification of talar neck fractures (a):Talar neck fractures have been classified into four groups of increasing severity. In Group I the talar neck is fractured without displacement. Incomplete hair-line cracks are not uncommon. Only the blood supply through the neck is affected, and the incidence of avascular necrosis is under 10%.

5 Classification (b): In Group II fractures there is an accompanying subtalar subluxation. The proximal portion of the talus adopts a position of plantar flexion (1). The head of the talus maintains its relationship with the navicular and calcaneus (and the rest of the foot) which sublux forwards (2).

6 Classification (c): Note in the radiographic example a more severe degree of plantar flexion of the proximal fragment, and greater subluxation. The blood supplies through the neck and sinus tarsi are both interrupted, and the incidence of avascular necrosis rises to 50% in fractures of this type.

7 Classification (d): Group III injuries: With further dorsiflexion and upward force (1) the tibia is driven between the two talar fragments. The posterior fragment is extruded backwards, while at the same time the convex posterior articular surface of the calcaneus (2) guides it medially. It comes to rest with its medial surface (3) caught on the sustentaculum tali (4).

8 Classification (e): In its final position (ctd) the main portion of the talus lies on the medial side of the ankle, with its fractured surface (5) pointing laterally. All three sources of blood supply are disturbed. The risks of avascular necrosis are high, rising to 85%.

9 Classification (f): In the rare Group IV injury, the head of the talus dislocates from the navicular (1) in association with a Group III (2) or a Group II injury. The incidence of avascular necrosis here is also high.

10 Diagnosis: The diagnosis may be suspected from the history, but is made radiologically. Care must be taken to differentiate between Type 1 and Type 2 injuries. If doubt exists, two laterals, one in dorsiflexion (1) and one in plantar flexion (2) should be taken and compared. These will reveal any subluxation (Type 2 illustrated).

11 Treatment of Type I injuries: Apply a padded plaster with a toe platform and elevate for about a week (1). Then non-weight bearing with crutches for 3 months (2). The fracture is then assessed out of plaster for union and absence of avascular necrosis (3). If there are no complications, weight bearing may commence with a light support (4). Physiotherapy will be required for the ankle, subtalar joint and calf.

12 Treatment of Type II injuries (a): While some prefer open reduction for all these fractures, closed methods may be attempted: (1) The foot is plantar flexed and everted. (2) A padded plaster is applied in this position and check radiographs taken. If a satisfactory reduction has been obtained, then conservative treatment may be continued.

13 Treatment of Type II injuries (b): (3) The limb is elevated for a week before (4) non-weight bearing is permitted. After 3–4 weeks the plaster is changed under intensifier control and the foot brought up to a right angle (5). Non-weight bearing is continued for a further 6 weeks. Thereafter, if the fracture is united and there is no evidence of avascular necrosis, weight bearing may be allowed with support (6). Physiotherapy will almost certainly be required.

14 Treatment of Group II injuries (c): If closed methods fail in obtaining a reduction, open reduction will be required. The fracture may be secured with a Kirschner wire passed backwards from the head of the talus into the body, with the aftercare being similar to that described in the previous frame. The Kirschner wire may be removed at the change of plaster. For more rigid fixation, a cannulated screw may be preferred.

15 Treatment of Group III injuries (a): The displaced portion of the talus is situated subcutaneously, and there should be no delay in reducing it as the overlying skin is tightly stretched over the bone and likely to slough. Facilities for open reduction should be available, but closed methods may be attempted first. Begin by gripping the heel and applying traction to it.

16 Treatment of Group III injuries (b): Maintaining traction (1), use the knee (2) to dorsiflex the foot. Pull the heel slightly forward and evert it (3) to open up the space for the talus. Apply strong pressure over the displaced body of the talus (4), pressing laterally, but also slightly anteriorly and downwards. Now plantar flex the foot. If purchase on the heel is poor, a Steinman pin through the heel and a calliper may be used.

17 Treatment of Group III injuries (c): After reduction, proceed with elevation and gradual mobilisation as described in Frame 13 above. If closed reduction fails (as it often does), open reduction will be necessary. The condition of the skin and any planned internal fixation will dictate the incision(s). These fractures may be fixed (best through a posterolateral incision) with one or two cancellous screws passed from behind through the body of the talus and into the head (5). Cannulated screws may also be used; these can be threaded over Kirschner wires which have been inserted temporarily to hold the reduction (6). The AO group, with an eye to rapid mobilisation, in fact recommend internal fixation along these lines for all talar neck fractures.

Treatment of Group IV injuries: These uncommon injuries are likely to require open reduction. All fragments should be retained, even if completely detached and obviously avascular. On no account should the talus be excised.

Complications of talar neck fractures (a):

Skin necrosis: The skin may become tightly stretched over a displaced talus and undergo necrosis with late sloughing. Early reduction is imperative to avoid this complication.

(b): Open injuries: Thorough debridement of the wound is essential, but again every effort must be made to retain the main fragments. Treatment should follow the usual lines established for the management of open fractures. If sepsis occurs in conjunction with avascular necrosis, healing may be obtained only after excision of the avascular fragments.

18 Complications ctd: (c) Ankle fracture: Rarely, malleolar fracture may be found complicating talar neck fractures. Closed reduction is here unreliable, and open reduction with internal fixation of the malleolar fracture is desirable. (Illus.: Group III fracture, with fracture of the lateral malleolus.)

19 Complications ctd:(d) Avascular necrosis: The diagnosis is made from the radiographs. Increased density is often apparent by 6 and usually by 12 weeks, but do not be confused by the dense shadows cast by the overlying malleoli in the lateral. Revascularisation always occurs in closed injuries and is usually advanced by 8 months. (Check progress by monthly radiographs.) Weight bearing before revascularisation is complete is likely to cause marked flattening of the talus (Illus.). Local supports and physiotherapy will be required. Because of its key position, avascular necrosis of the talus may lead to osteoarthritis of the ankle, subtalar or midtarsal joints (or any combination of these).

20 Complication ctd: (e) Osteoarthritis: This is said to occur¹ after all displaced fractures. All such patients should be counselled at the outset that chronic pain is the expected outcome, even with an anatomical reduction. Determination of the joints involved (e.g. all three in the case above) is required for any late fusion, and this may be aided by the site of the pain and the X-ray appearances. Local anaesthetic infiltration of suspected joints is occasionally helpful.

21 Other talar lesions: (a) Dome fractures: A fracture may involve a portion of the upper articular surface of the talus (1) as a result of a shearing injury. If undisplaced, this may be treated by a period of 6 weeks in a cast before reassessment by arthroscopy and an MRI scan. If the fragment is substantial and inverted or badly displaced, it should be secured with Smillie pins (2), a Herbert screw, or biodegradable pegs. If the fragment is small, it may be excised and the bone drilled. Thereafter, plaster fixation for 6 weeks is advisable.

22 (b) Osteochondritis tali: This may occur as a sequel to a non-displaced shearing fracture, although frequently there is no history of injury. (Note the lesion on the medial side of the upper articular surface.)

Where the fragment is substantial, with appreciable associated pain and swelling, it may be secured with a Herbert or other double pitch screw or a biodegradable dowel. Its base may be drilled in an attempt to encourage revascularisation.

23 (c) Avulsion fractures: Minor avulsion fractures of the talus may result from inversion, eversion, plantar flexion and rarely dorsiflexion strains of the ankle – when flakes of bone are pulled off by ligamentous or capsular attachments. These injuries require symptomatic treatment only (e.g. 2–4 weeks in a below-knee walking plaster).

24 (d) Fracture of the lateral process of the talus: These injuries are uncommon (demonstrated here on a CT scan), but are seen with increasing frequency as a result of snowboarding accidents. The subtalar joint is involved, and they are probably best dealt with by open reduction and internal fixation using a cancellous screw.

25 (e) Fractures of the body of the talus: 1. The upper articular surface of the talus may be fractured by the same mechanisms which produce compression fractures of the ankle. Vertical splits without significant disturbance of the ankle or subtalar joints (Illus.) may be treated as Group 1 talar neck fractures. 2. If displacement has occurred, accurate reduction and cross-screwing should be carried out. CT scans are useful in assessing dome fractures.

26 Body fractures ctd: 3. Often there is a high degree of comminution. The convexity of the body may be flattened and the talus compressed as it is squeezed between the tibia and calcaneus. Such fractures may also involve the subtalar joint, and there is invariably extensive damage to the cartilaginous surfaces of the ankle joint. Surgical reconstruction is seldom possible.

27 Treatment: A typical conservative line of treatment might be: (1) Initial pressure bandaging and elevation. (2) Intensive active exercises as soon as pain and swelling will permit. (3) Avoidance of weight bearing until union is well advanced (about 8–10 weeks). Persistent pain and functional restriction would be indications for ankle fusion.

28 (f) Compression fractures of the head of the talus: These fractures are uncommon, but usually highly comminuted and unsuitable for attempts at reconstruction. Early mobilisation of the foot should be the aim, and a regimen similar to that described in the previous frame may be followed.

29 Calcaneal fractures: Mechanisms of injury (a): The commonest cause of calcaneal fracture is a fall from a height on to the heels. Important factors include the height fallen, the nature of the ground, and the weight of the patient. The injury is common in slaters, window cleaners and construction workers. Rarely the injury may be produced by impact from below (e.g. a below-deck explosion on a ship).

30 Mechanisms of injury (b): Taking into account the commonest cause of injury, it is essential when examining a case of suspected calcaneal fracture that you do not overlook: (1) a similar fracture on the other side; (2) a wedge fracture of the spine (dorsolumbar junction fractures are present in 5% of calcaneal fractures); (3) upper limb injuries.

31 Clinical appearance: In major fractures, the heel when viewed from behind appears: (1) wider, (2) shorter and flatter, and (3) tilted laterally into valgus. There is often tense swelling of the heel, marked local tenderness, and later bruising (4), which may spread into the medial side of the sole and proximally to the calf. Weight bearing is usually, but not always, impossible.

32 Radiographs (a): The most important view is a well-centred and well-exposed lateral projection (1). An axial projection (2) is helpful in visualising the pillar of the heel (3), the sustentaculum tali (4), the anterior talocalcaneal joint (5) and the posterior talocalcaneal joint (6). This film is taken with the tube tilted at 40° from the vertical (7), preferably with the foot dorsiflexed, but pain may force this projection to be abandoned. An AP foot allows visualisation of the calcaneocuboid joint.

33 Radiographs (b): Oblique projections may be helpful if there is remaining doubt, or to obtain better visualisation of the posterior calcaneal facet. The four projections described by Brodén are particularly valuable for the latter. (The foot is internally rotated 30–40°, with the ankle in the neutral position. Four films, with tube tilts of 10, 20, 30 and 40° are taken, with the beam centred on the lateral malleolus).

34 Radiographs (c): This oblique projection shows the posterior talo-calcaneal joint quite clearly, with a split in the posterior articular surface of the calcaneus.

35 Radiographs (d): CT scans can be of value in assessing the nature and degree of comminution of a calcaneal fracture, and any subtalar and calcaneocuboid joint involvement. Coronal, transverse and sagittal projections have all been used. The coronal projection chosen as a standard to allow useful comparison of cases is made through the widest part of the talus. In the scan above the comminution of the calcaneus and involvement of the subtalar joint is obvious.

36 Radiographs (e): In this sagittal cut of the previous case the downward projecting axe-like lateral process of the talus can be clearly seen, with the extensive calcaneal comminution it has caused. It also gives evidence of alteration to the angles of Bohler and Gissane.

37 Radiographs (f): In the interpretation of calcaneal fractures two common constructions are used: (i) Bohler’s salient angle: This is formed by the intersection of two lines, both starting from the posterior articular surface of calcaneus, with one touching the anterior articular process of the calcaneus and the other the superior angle of the tuberosity. The angle normally lies in the 20–40° range, and is decreased in any fracture which flattens the heel, whether this is extra- or intra-articular.

38 Radiographs (g): (ii) The crucial angle of Gissane: This is the angle between two bone struts, both of which are obvious in the lateral projection; one lies along the lateral border of posterior articular process of the calcaneus, while the second extends anteriorly to the beak of the calcaneus at the upper margin of the calcaneocuboid joint. A decrease in this angle is indicative of significant disruption of the sub-talar joint, and this is often also associated with proximal displacement of the prominence of the heel.

39 Types of calcaneal fracture: The key factor in assessing calcaneal fractures is whether or not there is involvement of the subtalar joint. Here the common fracture patterns have been arranged roughly in order of complexity, with the most difficult, the intra-articular fractures, at the end.

A. Vertical fracture of the tuberosity: The subtalar joint is not involved (1), and the prognosis is excellent. Nevertheless, swelling may be severe, and should be controlled by firm bandaging over wool and elevation of the limb (2).

40 Vertical fracture ctd: Weight bearing, whilst not harmful, will be painful or impossible, and crutches will be required for some weeks; they may be discarded when pain settles (3). A crepe bandage or similar support may be worn until swelling subsides. Any long-term term heel pain may be controlled with a sorbo rubber heel cushion (4).