Achilles Tendon Rupture

Patients describe a sudden, audible snap and often report feeling kicked or struck in the back of the lower leg. Sharp initial pain typically settles within hours, leaving a dull ache and inability to push off. Walking is possible but flat-footed and antalgic.

Examine for the Simmonds triad (BOFAS), the combination of which confirms the injury in most cases.

• •Simmonds test (also known as Thompson test): with the patient prone and feet over the end of the couch, squeeze the calf. Absent plantarflexion is positive, with sensitivity around 96 percent for complete rupture
• •Palpable gap in the tendon, typically 2 to 6 cm above the insertion. The gap fills with haematoma within 24 to 48 hours and may then be impossible to feel

• •Altered angle of declination (Matles test): with the patient prone and knees flexed to 90 degrees, the affected foot rests in greater dorsiflexion than the unaffected side because resting tone of the gastroc-soleus is lost

Patients can usually still weakly plantarflex using flexor hallucis longus, flexor digitorum longus, tibialis posterior, peroneals, and plantaris. Preserved active plantarflexion does NOT exclude rupture and is the major reason the diagnosis is missed. Key differentials include medial gastrocnemius tear (tennis leg, negative Simmonds, push-off preserved), DVT, calcaneal avulsion or fracture, and posterior ankle impingement.

Acute Achilles rupture is a clinical diagnosis. Most patients with a typical history and a positive Simmonds test do not need imaging before referral.

Ultrasound is first-line confirmatory imaging when the diagnosis is clinically uncertain. It is dynamic, inexpensive, and can show whether a rupture is complete or partial. BOFAS highlights that the measured ultrasound tendon-gap is not reliably useful for management decisions and should not be over-relied upon.

MRI is reserved for delayed presentation (over 2 weeks), suspected re-rupture, characterising partial tears, or surgical planning. It best assesses proximal retraction, scar tissue, and muscle quality, all of which guide reconstruction options.

Plain radiographs do not diagnose tendon rupture but should be obtained when there is concern for a calcaneal avulsion fracture, particularly in osteoporotic patients or after a forceful direct injury.

Refer urgently to the local foot and ankle or orthopaedic service, ideally within 48 to 72 hours of presentation. Early specialist review allows tendon-end apposition and improves outcomes regardless of whether surgery is ultimately chosen.

Initial primary-care steps:

• •Immobilise in equinus using a removable boot (typically 3 heel wedges, giving around 30 degrees plantarflexion) or a below-knee equinus plaster cast
• •Encourage immediate weight-bearing as tolerated in the boot, in line with current BOFAS consensus and UKSTAR-era practice
• •Provide analgesia
• •Perform a VTE risk assessment per NICE NG89; pharmacological prophylaxis (LMWH, DOAC, or aspirin) is considered when VTE risk outweighs bleeding risk
• •Counsel on a likely 6 to 9 month recovery

Definitive management is shared decision-making between functional non-operative rehabilitation and operative repair. With modern functional rehabilitation, the re-rupture difference between operative and non-operative care is much smaller than in historical plaster cohorts. Surgery may modestly reduce re-rupture risk and tendon elongation in selected patients, balanced against wound, infection, and sural nerve complications (around 4 to 6 percent). For most non-elite adults, functional non-operative rehabilitation gives broadly similar patient-reported outcomes. Operative repair (open or percutaneous) is selectively considered for elite or professional athletes, delayed presentations over 2 weeks where retraction precludes apposition, re-ruptures, and patients who prefer surgery after balanced counselling. Percutaneous techniques reduce wound complications but carry a higher sural-nerve injury risk than open repair.

Rehabilitation is the cornerstone of recovery whether the patient is treated operatively or non-operatively. Outcomes depend more on adherence to a structured protocol than on the choice of treatment arm. Local UK protocols vary; the schedule below is illustrative.

A typical UK functional pathway uses an equinus boot for around 8 to 10 weeks with progressive reduction of plantarflexion.

• •Early phase (0 to 2 weeks): equinus around 30 degrees with 3 heel wedges, weight-bearing as tolerated in the boot, analgesia, VTE assessment
• •Mid phase (2 to 8 weeks): progressive heel wedge removal (typically one wedge every 2 weeks), full weight-bearing in the boot, ankle range of motion within the boot once permitted, proximal hip and knee strengthening
• •Late phase (8 to 12 weeks): wean out of the boot, restore symmetrical gait, closed-chain calf strengthening including isometric and isotonic plantarflexion
• •Return to sport (3 to 9 months): eccentric loading, single-leg heel raise re-education, plyometrics, running progression. Competitive return typically at 6 to 9 months, with full strength often taking 12 months or more

Long-term outcomes are usually good, but persistent calf circumference asymmetry, modest plantarflexion power deficit on isokinetic testing, and reduced single-leg heel-raise endurance are common.

• •BOFAS Hyperbook: Acute Achilles Tendon Rupture - functional non-operative rehabilitation with immediate weight-bearing in an equinus boot is the accepted UK default for most acute ruptures.
• •UKSTAR (Costa et al., Lancet 2020) - functional brace and plaster cast gave equivalent patient-reported outcomes within non-operative management; functional brace is preferred.
• •Willits et al. (JBJS-Am 2010) - operative repair versus accelerated functional non-operative rehabilitation showed similar re-rupture rates when modern rehab protocols were used.
• •Myhrvold et al. (NEJM 2022) - no significant difference in primary outcome between operative repair and non-operative care in acute Achilles rupture.
• •NICE NG89 - VTE risk assessment is required in all patients placed in lower-limb immobilisation; pharmacological prophylaxis is considered when VTE risk outweighs bleeding risk.

• •Classic demographic: 30 to 50 year old man, intermittent racquet sport, sudden pop in posterior calf, walks flat-footed but possible.
• •Preserved active plantarflexion does NOT exclude rupture - FHL, FDL, tibialis posterior, peroneals, and plantaris compensate; this is the commonest reason for the missed diagnosis.
• •The 48 to 72 hour window is the classic mislabel as calf sprain once the gap fills with haematoma; Simmonds plus Matles is the diagnostic combination.
• •Fluoroquinolones (ciprofloxacin, levofloxacin - MHRA warning) and corticosteroids are the two drug-class risk factors to know.
• •UK practice is shared decision-making with functional non-operative rehab as the common default; surgery selectively for elite athletes, delayed presentation, or re-rupture.
• •VTE risk assessment is mandatory whenever immobilising in a boot or cast per NICE NG89.