High-yield overview
The Silfverskiöld Test & Forefoot Overload
BiarticularGastrocnemius crosses knee + ankle
SilfverskiöldIsolates gastroc from soleus
ForefootOverloaded by tight gastroc
RecessionSurgery if conservative fails
Recession Levels (Achilles-sparing)
Strayer
PatternRelease of the gastrocnemius aponeurosis at the musculotendinous junction (commonest).
Treatment
Baumann
PatternIntramuscular recession of the gastrocnemius (and soleus) fascia proximally.
Treatment
Vulpius
PatternInverted-V release of the conjoined gastroc-soleus aponeurosis.
Treatment
Achilles lengthening
PatternReserved for combined gastroc-soleus (Silfverskiöld-negative) equinus; risks push-off weakness.
Treatment
Critical Must-Knows
- The gastrocnemius is BIARTICULAR - it crosses both the knee and the ankle - so a tight gastrocnemius limits ankle dorsiflexion more when the knee is EXTENDED.
- The Silfverskiöld test distinguishes an isolated gastrocnemius contracture from a combined gastroc-soleus (Achilles) contracture.
- Silfverskiöld POSITIVE = dorsiflexion is limited with the knee extended but IMPROVES with the knee flexed (the soleus, which does not cross the knee, relaxes the equation) - an isolated gastrocnemius contracture.
- A tight gastrocnemius shifts load to the forefoot and is an underlying driver of metatarsalgia, plantar fasciitis, Achilles tendinopathy, PTTD and diabetic forefoot ulceration.
- First-line treatment is stretching/eccentric programmes and night splints; refractory cases are treated by gastrocnemius RECESSION.
- Gastrocnemius recession (e.g. Strayer) increases dorsiflexion while avoiding the push-off/plantarflexion weakness associated with tendo-Achilles lengthening.
Clinical Pearls
- “Silfverskiöld: knee straight = limited DF; knee bent = improved DF → isolated gastrocnemius (recession indicated). No change with knee bent → combined contracture (consider Achilles lengthening).
- “Recession (Achilles-sparing) is preferred over TAL when the contracture is gastrocnemius-only, to preserve push-off power.
- “Watch the sural nerve during a Strayer recession.
The Silfverskiöld Test
Positive (isolated gastrocnemius)
Ankle dorsiflexion is limited with the knee extended but improves with the knee flexed. Flexing the knee slackens the biarticular gastrocnemius (which crosses the knee), so the remaining restriction is gastrocnemius-driven. Treat with gastrocnemius recession.
Negative (combined contracture)
Dorsiflexion is limited regardless of knee position - the soleus/Achilles (which do NOT cross the knee) are also tight. This is a combined gastroc-soleus contracture, where tendo-Achilles lengthening is considered (accepting some push-off weakness).
Anatomy & Pathophysiology
Why the Knee Position Matters
The gastrocnemius arises from the femoral condyles (above the knee) and joins the soleus to form the Achilles tendon - so it spans both the knee and the ankle. The soleus arises below the knee and crosses only the ankle. Because of this, a contracted gastrocnemius restricts ankle dorsiflexion most when the knee is straight and is "let out" when the knee bends - the basis of the Silfverskiöld test.
- Equinus = limited ankle dorsiflexion (commonly defined as less than ~10 degrees with the knee extended and the hindfoot held neutral).
- A tight gastrocnemius forces the foot into relative plantarflexion, transferring load to the forefoot and altering gait (early heel rise, increased toe-extensor recruitment).
- This forefoot overload underlies mechanical metatarsalgia, and contributes to plantar fasciitis, Achilles tendinopathy, posterior tibial tendon dysfunction, midfoot/forefoot deformity, and diabetic forefoot ulceration.
Clinical Assessment
Examination
- Measure ankle dorsiflexion with the hindfoot held in neutral (inversion) to lock the midfoot and avoid false dorsiflexion through the midfoot.
- Perform the Silfverskiöld test: dorsiflexion with the knee extended then with the knee flexed to ~90 degrees. Improvement with knee flexion = isolated gastrocnemius contracture.
- Examine the forefoot for metatarsalgia/callosities and assess gait (early heel rise).
Management
Non-operative
- Stretching programmes (knee-extended gastrocnemius stretches), eccentric loading, and night splints/dorsiflexion orthoses.
- Heel lifts/orthoses and footwear modification to off-load the forefoot symptomatically.
- Most patients improve; these are the mainstay before any surgery.
Mnemonic
BENDSilfverskiöld Interpretation
B
Bend the knee
Re-test dorsiflexion with the knee flexed.
E
Eases → gastroc
DF improves on bending = isolated gastrocnemius.
N
No change → combined
DF still limited = gastroc-soleus (Achilles).
D
Decide the level
Gastroc → recession; combined → TAL.
Hook:BEND the knee: if dorsiflexion eases, it is the (biarticular) gastrocnemius.
Evidence Base
Evidence
Silfverskiöld Test & Gastrocnemius Recession
DeOrio JK, Lewis JS • Foot Ankle Int (2013)
Key Findings:
- Prospective series of 29 patients undergoing Strayer gastrocnemius recession (during total ankle replacement) with Silfverskiöld testing
- Recession increased dorsiflexion by an average of 12.6 degrees with the knee extended and 10.1 degrees with the knee flexed
- Gain occurred regardless of the Silfverskiöld result, with markedly positive tests gaining most
- Gastrocnemius recession avoids the push-off/plantarflexion weakness of Achilles lengthening
Clinical implication: Quantifies the dorsiflexion gained by gastrocnemius recession and supports it as an Achilles-sparing way to correct equinus.
Evidence
Gastrocnemius Recession for Metatarsalgia
Cortina RE, Morris BL, Vopat BG • Foot Ankle Clin (2018)
Key Findings:
- Gastrocnemius contracture causes mechanical metatarsalgia by overloading the forefoot
- Altered gait increases toe-extensor recruitment and forefoot pressure
- Patients with mechanical metatarsalgia and gastrocnemius contracture show ankle equinus and a positive Silfverskiöld test
- Non-operative therapy is first-line; gastrocnemius lengthening is an option when it fails
Clinical implication: Links isolated gastrocnemius contracture to forefoot overload (metatarsalgia) and supports recession when conservative care fails.
Viva Scenarios
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Scenario 1: Refractory metatarsalgia with tight calves
Clinical prompt
“A patient has persistent forefoot pain and callosities under the metatarsal heads despite orthoses, and you notice limited ankle dorsiflexion. How do you assess and treat this?”
Practical approach
I would suspect a gastrocnemius (equinus) contracture overloading the forefoot. I would measure ankle dorsiflexion with the hindfoot held in neutral, then perform the Silfverskiöld test: if dorsiflexion is limited with the knee extended but improves with the knee flexed, the contracture is an isolated gastrocnemius problem (positive test); if it is limited regardless of knee position, the soleus/Achilles are also tight (combined). For an isolated gastrocnemius contracture, I would start with gastrocnemius stretching, eccentric loading and night splints plus forefoot off-loading orthoses. If symptoms persist, I would offer a gastrocnemius recession (a Strayer release at the musculotendinous junction), which reliably increases dorsiflexion while preserving push-off, protecting the sural nerve. I would reserve tendo-Achilles lengthening for a combined contracture, counselling about plantarflexion weakness.
Key clinical points
Link forefoot overload to gastrocnemius equinus
Measure DF in hindfoot neutral; perform the Silfverskiöld test
Conservative first (stretch/splint/orthoses)
Isolated → gastroc recession; combined → TAL
Common pitfalls
Measuring dorsiflexion through the midfoot (false normal)
Doing an Achilles lengthening for an isolated gastrocnemius contracture (push-off weakness)
Further questions
“Why does the Silfverskiöld test work?”
“The gastrocnemius is biarticular (crosses the knee); flexing the knee slackens it, so any residual dorsiflexion limit is from the soleus/Achilles.”
Guidelines, Registries & Global Practice
Global Practice Picture
Isolated gastrocnemius contracture is increasingly recognised worldwide as an under-appreciated, correctable driver of forefoot and hindfoot pathology. The internationally consistent approach: measure dorsiflexion in hindfoot neutral, apply the Silfverskiöld test to localise the contracture, treat conservatively first, and use an Achilles-sparing gastrocnemius recession (rather than Achilles lengthening) for refractory isolated gastrocnemius equinus.
Side-by-Side Synthesis
DF knee extended
- Isolated gastrocnemius
- Limited
- Combined gastroc-soleus
- Limited
DF knee flexed
- Isolated gastrocnemius
- Improves
- Combined gastroc-soleus
- Still limited
Silfverskiöld
- Isolated gastrocnemius
- Positive
- Combined gastroc-soleus
- Negative
Preferred surgery
- Isolated gastrocnemius
- Gastrocnemius recession (Strayer)
- Combined gastroc-soleus
- Tendo-Achilles lengthening
Push-off power
- Isolated gastrocnemius
- Preserved
- Combined gastroc-soleus
- May be weakened
Exam day cheat sheet
Concept
- Gastrocnemius is biarticular (knee + ankle)
- Equinus = limited ankle dorsiflexion
- Measure DF in hindfoot neutral
- Drives forefoot overload
Silfverskiöld Test
- Positive: DF limited knee-extended, improves knee-flexed
- = isolated gastrocnemius contracture
- Negative: limited regardless = combined
- Determines recession vs TAL
Management
- Stretch / night splint / orthoses first
- Gastroc recession (Strayer) - Achilles-sparing
- TAL for combined contracture
- Protect the sural nerve