Conditions Of The Foot & Ankle Flashcards
What is compartment syndrome? 1️⃣
-condition where there is a rise in increased intra-compartmental pressure due to haemorrhage &/or oedema as a result of trauma (blunt or penetrating)
What are compartments of the limbs bound by and contain? 1️⃣
- bound by bone and fascia
- contain muscles with their nerve and blood supply, together with nerves and vessels to more distal parts of the limb
What are the clinical signs of compartment syndrome? 1️⃣
- severe pain in limb, which is excessive for the degree of injury
- increasing pain and not relieved by analgesia
- pain classically exacerbated by passive stretch of the muscles
What should be done if compartment syndrome is suspected? 1️⃣
-surgical decompression (fasciotomy) of all affected limb compartments
Describe the short term consequences of compartment syndrome 1️⃣
-increased intracompartmental pressure leads to decreased perfusion of muscle.
-ischaemic muscle releases mediatiors which further increase capillary permeability and exacerbate rise in intracompartmental pressure
-in severe cases, rhabdomyolysis
(muscle necrosis) and acute kidney injury can result
- if compartment pressure exceeds systolic arterial pressure, there will be loss of peripheral pulses and increased capillary refill time
- nerve fibres are susceptible to ischaemia; the thin cutaneous nerve fibres are affected more quickly than motor fibres so distal paraesthesia precedes loss of motor function
Describe the long term consequences of compartment syndrome 1️⃣
- the acute kidney injury due to rhabdomyolysis may become chronic
- necrotic muscle may undergo fibrosis, leading to Volkmann’s ischaemic contracture : a permanent painful and disabling contracture of the affected muscle groups
What is the usual mechanism of injury for an ankle fracture? 2️⃣
-inversion or eversion injury
Why should co-morbidities be considered in cases of ankle fractures? 2️⃣
Co-morbidities such as diabetes, neuropathy, peripheral vascular disease and smoking are likely to affect fracture healing
How can the integrity of the overlying soft tissues in an ankle fracture injury be compromised? 2️⃣
- fracture blisters
- skin over fracture blisters can become necrotic
In open ankle-fracture
-skin barrier breached and there is a direct communication between fracture and external environment
How are open ankle fractures treated? 2️⃣
-require urgent surgery with extensive irrigation and debridement to reduce risk of osteomyelitis (bone infection)
How do the bones in a normal ankle appear? 2️⃣
Talus is seated firmly in a mortise comprising the distal tibia and medial and lateral malleoli
Describe how the ankle joint and associated ligaments are visualised as a ring in the coronal plane 2️⃣
- proximal part of ring formed by articular surfaces of tibia and fibula, united at the inferior tibiofibular joint by syndesmotic ligaments
- medial side of the ring is formed by the deltoid ligament
- inferior part of the ring is formed by the subtalar joint
- lateral side is formed by the lateral ligament complex of the ankle (anterior and posterior talofibular ligament and talocalcaneal ligament)
In what ways can this ‘ring’ break and how is joint stability affected? 2️⃣
- single break : joint stable
- A ring usually breaks in 2 places so what appears to be a single fracture of the ankle joint is likely to have occurred in association with ligament damage elsewhere in the ‘ring’
- double break : joint unstable
- double break and dislocation : joint unstable
What can an injury that results in forced eversion or external rotation of the foot cause? 2️⃣
-foot pushes against lateral malleolus, potentially leading to 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
[single break + ligament damage or double break]
What can an injury that results in forces inversion or adduction of the foot cause? 2️⃣
-push 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
[single break + ligament damage or double break]
Describe talar shift 2️⃣
-when there is a disruption of any 2 out of the syndesmosis, medial or lateral ligaments:
Ankle mortise becomes unstable and widens so that the talus can shift medially or laterally within the ankle joint
How are ankle fractures treated? 2️⃣
Stable fractures
- usually treated non-operatively
- aircast boot or a fibreglass cast for comfort
- patients can weight-bear safely and there is a low rate of complications such as secondary OA
Unstable fractures
-need surgical stabilisation
What does an ankle sprain refer to ? 3️⃣
A partial or complete tear of one or more ligaments of the ankle joint
How is an ankle sprain treated? 3️⃣
- 90% heal with just rest and time
- cold compress
-those that do not heal can cause late ankle instability and sometimes require surgery
State some factors that can contribute to an increased risk of ankle sprains 3️⃣
- weak muscles/tendons that cross the ankle joint, especially the peroneal muscles
- weak or lax ankle ligaments (hereditary or due to over-stretching as a result of repetitive ankle sprains)
- inadequate joint proprioception
- slow neuromuscular response to an off-balance position
- running on uneven surfaces
- shoes with inadequate heel support
- wearing high-heeled shoes: weak position of the ankle joint with an elevated heel and small base of support
What causes ankle sprains? 3️⃣
- excessive strain on ligaments of the ankle
- can be caused by excessive external rotation, inversion or eversion of the foot due to an external force
- if strain is great enough to pull a ligament past it’s yield point, the ligament becomes damaged or ‘sprained’
What is the most common mechanism of injury in ankle sprains? 3️⃣
- inversion injury affecting a plantar-flexed and weightbearing foot
- anterior talofibular ligament is at most risk of sprain
When does an avulsion fracture occur? 3️⃣
When 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
In a severe sprain of the ankle, why is it not uncommon to find that the patient has an avulsion fracture of their fifth metatarsal tuberosity?
Peroneus 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.
In what case can normal physiology be confused for a 5th metatarsal fracture on an X-ray? 3️⃣
In children ages 10-16years, unfused 5th metatarsal apophysis can often be seen on foot X-rays.
Need to examine child clinically and look at orientation if the lucent line on the x ray to differentiate
*both the fracture and unfused apophysis can co-exist
When does the rupture of the Achilles tendon most commonly occur? 4️⃣
In men aged 30-50yrs during recreational sports that require bursts of jumping, pivoting and running:
E.g tennis, badminton, football
Describe the mechanism of injury for an Achilles’ tendon rupture 4️⃣
- making a forceful push off with an extended knee e.g during jumping
- a fall with the foot outstretched in front and ankle dorsiflexed, forcibly over-stretching the tendon
- falling from a height or abruptly stepping into a hole or off a kerb
- complete tear is more common than a partial tear
What is often the site of rupture of the Achilles tendon? 4️⃣
‘Vascular watershed’ area, approx 6cm proximal to the insertion of the Achilles’ tendon onto the calcaneal tuberosity
-this is an area of decreased vascularity and decreased thickness of the tendon which together render it more susceptible to tearing
What are the signs and symptoms of a ruptured Achilles tendon? 4️⃣
- sudden and severe pain at the back of the ankle or in the calf
- 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 up on tip toes or push off whilst walking
How is an Achilles’ tendon rupture diagnosed? 4️⃣
Diagnosis often made clinically
-Thompson’s test (aka Simmonds’s test) used
Along with signs and symptoms
MRI and ultrasounds can be used effectively to demonstrate the gap in the Achilles’ tendon
How are Achilles’ tendon ruptures treated? 4️⃣
-mostly treated conservatively with foot being held in the correct position in an aircast boot
- when tendon ruptured, the two ends are frayed, which makes surgical reconstruction difficult
- surgery has relatively high compilation rate involving wound complication due to overlying skin being thing and poorly vascularised
*re-rupture rate of ~2-8% with either treatment
