Achilles Tendon Rupture

Achilles tendon rupture produces a distinctive constellation of findings that, once experienced, is rarely forgotten. The onset is sudden and unmistakable. **Call Maryland Orthopedic Specialists at [(301) 515-0900](tel:3015150900) immediately if you experience any of the following after a sudden lower-leg event:**

• Sudden audible pop or snap — Patients frequently report hearing or feeling what sounds like a gunshot or whip-crack at the back of the ankle at the moment of injury.
• Immediate sharp pain, then paradoxical reduction — There is often a brief, severe pain followed by a surprisingly rapid decrease in acute discomfort. This paradoxical pain reduction is a hallmark of complete rupture and frequently leads patients to underestimate the severity of the injury.
• Inability to push off or rise onto the toes — Loss of active plantarflexion power against gravity is the most functionally disabling symptom. Walking is possible but weak and abnormal.
• Positive Thompson test — A clinical maneuver performed in the office that strongly suggests complete rupture (see How We Diagnose It below).
• Palpable gap in the tendon — A tender defect 2–6 cm above the heel can often be felt directly through the skin in the acute phase, before swelling obscures it.
• Flat-footed, antalgic gait — Without effective push-off, patients walk with a shortened stride and an exaggerated toe-up (calcaneal gait) pattern on the affected side.

Most Achilles tendon ruptures are diagnosed clinically. The history and physical examination are highly accurate. Imaging is used selectively to confirm equivocal cases and for surgical planning.

Clinical Examination

Thompson Test (Simmonds-Thompson) The gold-standard clinical test for Achilles tendon rupture. The patient kneels on the examination table or lies prone with the foot hanging free. The examiner squeezes the calf muscle belly. In an intact tendon, this produces passive plantarflexion of the foot. Absence of plantarflexion constitutes a positive test, indicating complete rupture. A meta-analysis of 15 studies comprising 808 patients demonstrated sensitivity of 73–96% and specificity approaching 93–100% for complete rupture.

Palpation of the Tendon Gap In the acute setting (before significant swelling), a discrete palpable defect at the rupture site, characteristically 2–6 cm above the calcaneal insertion, can be identified on gentle palpation. This finding has high positive predictive value in combination with the Thompson test.

Matles Test The patient lies prone and actively flexes both knees to 90°. The resting angle of the ankle is observed: with an intact Achilles, the foot rests in slight plantarflexion. With a complete rupture, the affected foot falls into relative dorsiflexion (neutral or beyond) due to loss of passive tendon tension. The Matles test increases diagnostic accuracy when combined with the Thompson test and is particularly useful when swelling limits palpation.

Imaging

Ultrasound Ultrasound is the preferred first-line imaging modality when clinical findings are equivocal or when accurate characterization of rupture extent is needed before treatment decisions. Dynamic real-time ultrasound allows direct visualization of tendon continuity, measurement of gap width (critical for surgical vs. non-operative triage), and assessment of tendon apposition in equinous (plantarflexed) position. This is a key determinant of non-operative candidacy. Ultrasound sensitivity for complete rupture is 95% with specificity of 99% (meta-analysis, Aminlari et al., 808 patients). Dynamic assessment in maximum plantarflexion can demonstrate whether the tendon ends approximate, informing non-operative management decisions.

MRI MRI is reserved for equivocal cases, chronic or neglected ruptures, preoperative planning in complex cases (significant degenerative change, large tissue gaps, prior tendon surgery), or when augmentation strategies are being considered. MRI precisely characterizes rupture morphology, residual tissue quality, gap length, and the condition of the paratenon. This information guides augmentation choices in high-risk tissue.

What You Leave With

After your evaluation at MOS, you will have a confirmed diagnosis, ultrasound results (often same-day), a clear explanation of your injury in plain language, and a personalized treatment plan (whether surgical or non-operative) with a realistic recovery timeline before you walk out the door.

Recovery from Achilles tendon rupture is a prolonged, calf-strength-limited process regardless of treatment choice. Setting realistic expectations is as important as selecting the right treatment.

Non-Operative Recovery Timeline

• Acute / Boot Phase (Weeks 1–8): Walking boot with heel wedges; early weight-bearing; progressive wedge reduction; ankle ROM exercises begin week 1–2
• Active Rehabilitation (Weeks 8–16): Transition out of boot; progressive PT; calf strengthening; proprioception and balance training
• Return to Running (Months 4–6): Running progression begins when single-leg calf endurance exceeds 90% limb symmetry index
• Return to Sport (Months 9–12): Full unrestricted sport when RTS criteria are met (see below)

Surgical Recovery Timeline

• Postoperative / Boot Phase (Weeks 1–8): Protective boot with early weight-bearing; wound management; gentle ROM from week 2
• Active Rehabilitation (Weeks 8–16): Progressive PT; calf strengthening; proprioception and balance; walking normalized
• Return to Running (Months 3–5): Running progression begins earlier than non-operative due to more certain tendon integrity
• Return to Sport (Months 6–9): Full unrestricted sport when RTS criteria are met

The Rate-Limiting Step: Calf Strength

Tendon healing is not the primary barrier to return to sport. Recovery of calf muscle strength and endurance is. Studies consistently demonstrate that calf strength deficits persist well beyond clinical healing: isokinetic calf strength remains approximately 10–20% below the uninjured limb at 12 months, and deficits in heel-rise endurance have been documented at 7-year follow-up in some cohorts. This is the reason return-to-sport timelines are measured in months, not weeks.

Return-to-Sport Criteria

Return to unrestricted sport at MOS is criteria-based, not calendar-based. All of the following should be met before clearance:

• Single-leg heel-rise endurance: ≥90% symmetry index (number of repetitions to failure) compared to the contralateral limb
• Single-leg hop testing: ≥90% limb symmetry index across triple hop, crossover hop, and timed 6-meter hop
• Isokinetic plantarflexion strength: ≥90% side-to-side symmetry at functional speeds
• Full pain-free range of ankle motion in functional tasks
• Psychological readiness: patient confidence and readiness to return (patient-reported outcome tools)
• Sport-specific movement competency: jogging, running, cutting, jumping as appropriate to the sport