19. Disorders Of The Foot And Ankle Flashcards
What are compartments of the limbs bound by?
bound by bone and deep fascia
What is compartment syndrome?
Trauma (blunt or penetrating) to a fascial compartment may lead to haemorrhage and/or oedema and cause a rise in intracompartmental pressure
What are the clinical signs of compartment syndrome?
- severe pain in the limb which is excessive for the degree of injury
- increasing and not relieved by analgesia
- the pain is classically exacerbated by passive stretch of the muscles
How is compartment syndrome treated?
fasciotomy (surgical decompression)q
What are early short term consequences of compartment syndrome?
- Decreased perfusion of muscle
- Ischaemic muscle releases mediators which further increase capillary permeability and exacerbate the rise in intracompartmental pressure
In severe untreated cases:
- rhabdomyolysis
- acute kidney injury can result.
Later neurovascular signs
What are the late short term consequences of compartment syndrome?
If the compartment pressure exceeds the systolic arterial pressure:
- loss of peripheral pulses
- increased capillary refill time.
Nerve fibres are susceptible to ischaemia
Which nerves are affected first in compartment syndrome and what is the implication of this?
Thin cutaneous nerve fibres are affected more quickly than the motor fibres, so distal paraesthesia precedes loss of motor function.
What are the long term consequences of compartment syndrome?
- rhabdomyolysis can result in acute kidney injury which may become chronic
- necrotic muscle may also undergo fibrosis leading to Volkmann’s ischaemic contracture
What is Volkmann’s ischaemic contracture?
a permanent painful and disabling contracture of the affected muscle groups
What is the typical mechanism injury for ankle fracture?
Inversion or eversion injury
What is important to consider in fractures?
co-morbidities (e.g. diabetes, neuropathy, peripheral vascular disease, smoking) as these are likely to affect fracture healing
What needs to be done if fracture blisters appear?
Surgery often needs to delayed until after the blisters have healed. Sometimes the skin over the fracture blister becomes necrotic, so healing can take a considerate amount of time
What are open ankle fractures?
skin barrier is breached and there is a direct communication between the fracture and the external environment
How is the risk of osteomyelitis(infection of the bone) reduced in open ankle fractures?
Require urgent surgery with extensive irrigation and debridement
What is wound irrigation?
steady flow of a solution across an open wound surface to achieve wound hydration, to remove deeper debris, and to assist with the visual examination
What is debridement?
removal of damaged tissue or foreign objects from a wound.
What do different part of the ankle ring ( ankle joint and associated ligaments) represent?
- proximal part of the ring: articular surfaces of the tibia and fibula, united at the inferior tibiofibular joint by syndesmotic ligaments.
- medial side: formed by the medial (deltoid) ligament
- inferior part: formed by the subtalar joint
- lateral side: formed by the lateral ligament complex of the ankle (anterior talofibular, talocalcaneal and posterior talofibular)
What is important to remember in ankle fractures with regard to numbers of structures damaged?
When there is a fracture, likely to be more than one structure that is damaged (another bone, or ligaments, usually on the opposite side) (can’t break a ring in one place)
What other structures may be damaged in an injury that results in either forced eversion or external rotation of the foot?
an injury that results in either forced eversion or external rotation of the foot will push against the lateral malleolus, potentially leading to an oblique fracture of the lateral malleolus, and will pull on the medial ligaments, leading to a ruptured deltoid ligament or a transverse fracture of the medial malleolus
What other structures may be damaged in an injury that results in either forced forced adduction or inversion of the foot?
an injury that results in either forced adduction or inversion of the foot can push the medial malleolus off the tibia (oblique fracture) and pull on the lateral structures, leading to ruptured lateral ligaments or a transverse fracture of the lateral malleolus.
What is a talar shift?
Talus shifts medially or laterally within the ankle joint
Disruption of which ligaments causes talar shift?
Disruption of any two out of the syndesmosis, medial (deltoid) or lateral ligamentss, the ankle mortise becomes unstable and widens so that the talus can shift medially or laterally within the ankle joint
How are stable ankle joints treated?
Non-operatively with an aircast boot or a fibreglass cast for comfort - can weight-bear safely and there is a low rate of complications such as secondary osteoarthritis
How are non-stable ankle joints treated?
need surgical stabilisation
What does an ankle sprain refer to?
Partial or complete tear of one or more ligaments of the ankle joint
How are ankle sprains treated?
- 90% heal with rest and time
- those that do not heal can cause late ankle instability and sometimes require surgery
What factors can contribute to an increased risk of ankle sprains?
- Weak muscles/tendons that cross the ankle joint, especially the peroneal muscles
- Weak or lax ankle ligaments - this can be hereditary or due to overstretching of ligaments as a result of repetitive ankle sprains
- Inadequate joint proprioception (i.e. sense of joint position)
- Slow neuromuscular response to an off-balance position
- Running on uneven surfaces
- Shoes with inadequate heel support
- Wearing high-heeled shoes - due to the weak position of the ankle joint with an elevated heel, and a small base of support
What are the most common mechanisms for ankle sprains?
Ankle sprains occur usually through excessive strain on the ligaments of the ankle. This can be caused by Excessive external rotation, inversion or eversion of the foot due to an external force
When the foot is forced past its normal range of motion, the excess stress puts a strain on the ligaments. If the strain is great enough to pull a ligaments past its yield point, the ligament becomes damaged or ‘sprained’
Which ligament is most commonly affected in ankle sprain and what is the mechanism for this?
anterior talofibular ligament: inversion injury affecting a plantar-flexed and weightbearing foot.
What is an avulsion fracture?
A tendon or ligament is placed under tension and instead of the tendon or ligament tearing, a fragment of bone is pulled off at the insertion site
What common avulsion fracture occurs in severe ankle sprains and why?
Fifth metatarsal tuberosity avulsion:
Peroneus (fibularis) brevis tendon is attached to a tubercle on the base of the 5th metatarsal. In an inversion injury, it is under tension and can pull off a fragment of bone at its insertion site
What might a 5th metatarsal avulsion fracture be confused for in children?
Unfused apophysis
What mechanisms can cause achilles tendon rupture?
- Making a forceful push-off with an extended knee (e.g. during jumping)
- A fall with the foot outstretched in front and the ankle dorsiflexed, forcibly overstretching the tendon
- Falling from a height, or abruptly stepping into a hole or off a kerb.
What is the common site on the achilles tendon for rupture and why?
‘Vascular watershed’ area, approximately 6cm proximal to the insertion of the Achilles tendon
- area of decreased vascularity and thickness
What is more common in achilles tendon rupture, complete or partial tear?
complete
What are the signs and symptoms of achilles tendon rupture?
- A sudden and severe pain at the back of the ankle or in the calf (like being ‘kicked in the heel’)
- The sound of a loud pop or snap
- A palpable (and sometimes visible) gap or depression in the tendon
- Initial pain and swelling followed by bruising
- Inability to stand on tip toe or to push-off whilst walking
What is the Thompson’s test?
Used to evaluate achille’s tendon, squeeze calf, result is positive if there’s no movement
Why is surgical reconstruction of tendon ruptures difficult?
When the tendon ruptures, Two ends are frayed (like a mop head)
How are most Achilles tendon ruptures treated and why?
Treated conservatively, with the foot being held in the correct position in an aircast boot
- surgical reconstruction is difficult
What is the complication rate of achilles tendon surgery and why?
5-10% of patients have wound complications because the overlying skin is thin and poorly vascularised
What is the rate of re-repture of Achilles tendon?
2-8% after surgery with a
similar rate after conservative management
What is hallux valgus?
- Varus deviation of the first metatarsal
- Valgus deviation and/or lateral rotation of the hallux
- Prominence of the first metatarsal head, with or without an overlying callus
Define hallux valgus
Hallux (big toe) valgus (distal part deviated laterally)