import { ComparisonTable, ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MedicalImage, MnemonicCard, OnePagerSummary, Tabs, Tab, VivaScenario, VivaScenarioSection } from '@/components/mdx' # Triceps Tendon Rupture ### Imaging Atlas

Antigravity elbow extension may be **partly preserved** even with a complete tear (anconeus and the intact lateral tendinous expansion compensate). A patient who can "just about" straighten the arm can still have a complete rupture - **palpate for a gap and image**. The **fleck sign** (avulsed olecranon flake) is pathognomonic and easy to miss. A normal X-ray does not exclude a tear - proceed to **MRI or ultrasound** if clinical suspicion persists.

Triceps tendon rupture is the **rarest of the major tendon ruptures**, accounting for roughly 1-2% of all tendon injuries. According to PubMed, it occurs most often in **men aged 40-60**, classically during weightlifting (forced eccentric contraction at the end of a bench-press lockout) or after a fall on an outstretched hand that suddenly flexes a contracting elbow. **Key facts students should know:** - The injury is almost always an **avulsion at the tendon-bone junction (enthesis)** off the olecranon, not a midsubstance tear, because the enthesis is the mechanically weakest link. - A large insurance-database cohort identified **male sex, age over 60, ischaemic heart disease, rheumatoid arthritis and chronic kidney disease** as risk factors for complications, and **prior anabolic steroid use** as the strongest predictor of needing revision surgery. - Up to a third of cases have an **associated injury** (radial head fracture, olecranon bursitis, or wrist/forearm injury from the same fall) - examine the whole limb. - Because it is so rare, the **diagnosis is frequently missed** at first presentation, leading to chronic, retracted tears that are harder to repair. **Functional anatomy:** - The triceps brachii has three heads (long, lateral, medial) that converge into a **common tendon** inserting on the **posterior olecranon**. It is the **primary elbow extensor**. - The distal tendon is **bilaminar**: a thick **superficial layer** (from the long and lateral heads) inserts more proximally, and a **deep layer** (mainly the medial head) inserts more distally and broadly. MRI tear-classification systems are built on this two-layer structure. - A **lateral tendinous expansion** blends with the forearm fascia and anconeus. When intact, it allows weak residual extension even after a complete central tear - the source of the "antigravity trap". **Mechanism of failure:** - **Eccentric overload**: a sudden extension force against an actively contracting (decelerating) triceps - the lockout phase of a heavy bench press is the textbook example. - The avulsion propagates through the **enthesis**, sometimes lifting a thin cortical **flake** of olecranon (the fleck sign). - **Pre-existing tendinopathy** weakens the insertion. Anabolic steroids, fluoroquinolones, repeated local steroid injection for olecranon bursitis, and metabolic bone disease (renal failure, hyperparathyroidism) all degrade collagen and predispose to rupture at lower loads. Triceps tears are described by **tear location, completeness, and chronicity**. Use the tabs below. **Partial vs complete - the decision-driving distinction:** - **Partial tear (less than 50% of tendon width):** Antigravity extension usually preserved; pain and focal weakness. Most can have a non-operative trial. - **High-grade partial tear (greater than 50%):** Behaves functionally like a complete tear; significant weakness; usually repaired, especially in athletes. - **Complete tear:** Loss of active extension against gravity (though weak residual extension may persist via anconeus/expansion); palpable gap; surgical repair in active patients. The **superficial layer is involved in essentially all symptomatic tears**; isolated deep-layer tears are not seen in surgical series. - **Avulsion from olecranon (most common):** Tendon-bone junction failure, with or without a bony flake. - **Musculotendinous junction tear:** Uncommon; seen with direct trauma. - **Intramuscular/muscle belly tear:** Rare; managed non-operatively. Location matters for repair: an avulsion is reattached to bone (anchors/tunnels), whereas a retracted musculotendinous tear may need augmentation. - **Acute (less than 3 weeks):** Tendon mobile; direct anatomic repair to the footprint. - **Subacute (3-6 weeks):** Repair still usually possible; may need release of adhesions. - **Chronic (greater than 6 weeks):** Tendon retracts and scars; primary repair may be impossible, requiring **V-Y turndown** or **Achilles tendon allograft** reconstruction with poorer outcomes. The **MRI layered classification** (superficial full-thickness with deep partial tear is the commonest pattern) helps plan whether a single- or double-row repair is needed. **History:** - Sudden **pain and a "pop"** at the back of the elbow during a lift or after a fall. - **Weakness** extending the elbow, or difficulty pushing up from a chair / doing press-ups. - Ask specifically about **steroid use, renal disease and previous olecranon injections**. **Examination:** - **Inspection:** Posterior elbow swelling, ecchymosis, sometimes a visible defect. - **Palpation:** A **palpable gap** just proximal to the olecranon is the most useful sign. - **Active extension against gravity:** Position the shoulder so the elbow must extend against gravity (arm overhead or horizontal). Inability, or marked weakness, suggests a complete tear - but remember weak residual extension does not exclude it. - **Modified Thompson test (squeeze test):** With the arm supported and elbow flexed, squeeze the triceps muscle belly. In an intact tendon the elbow passively extends; **absence of extension** indicates a complete rupture. - **Radiographs first (AP + lateral):** Look for the **fleck sign** - an avulsed flake of olecranon cortex, pathognomonic of a triceps avulsion. Also excludes associated radial head/olecranon fractures. - **Ultrasound:** Cheap, dynamic, operator-dependent; good for confirming a tear and assessing gap, useful in resource-limited settings. - **MRI:** Best for **equivocal cases, partial tears and surgical planning** - quantifies the percentage of tendon torn, which layers are involved, gap/retraction, and muscle quality in chronic tears. Sagittal fat-saturated sequences show fluid at the footprint. A confident clinical diagnosis (gap + antigravity loss + fleck sign) needs no advanced imaging before surgery, but **MRI is invaluable when the examination is equivocal** or a partial tear is suspected. Treatment hinges on **completeness of the tear and patient demand**. Use the tabs below. **Indications:** - **Partial tears (less than 50%)** with preserved antigravity extension. - **Low-demand or high-surgical-risk** patients who decline or cannot tolerate surgery. **Protocol:** - Splint/brace at **30-40 degrees of flexion** for ~4 weeks, then progressive range of motion. - Avoid resisted extension for 6 weeks; graded strengthening thereafter. - **Monitor closely** - a partial tear that progresses, stays painful, or fails to regain strength should be converted to surgical repair. **Indications:** - **Complete tears** in active patients. - **High-grade partial tears (greater than 50%)**, especially in athletes/manual workers. - **Failed non-operative management** of a partial tear. - Acute repair (within ~3 weeks) gives the best results before retraction occurs. **Principles:** Anatomic reattachment of the tendon to its olecranon footprint with a strong construct that permits early protected motion. - **Transosseous bone tunnels (cruciate sutures):** The traditional "gold standard"; reliable but higher re-tear and complication rates in comparative reviews. - **Suture anchors (single- or double-row):** Restore the footprint, lower re-rupture and complication rates; increasingly preferred. - **Knotless suture-bridge / unicortical button:** Maximise footprint coverage and reduce gap formation biomechanically. - **Chronic/retracted tears:** Add **V-Y triceps turndown** or **Achilles tendon allograft** augmentation. - **0-2 weeks:** Splint near extension; protect the repair. - **2-6 weeks:** Hinged brace, progressive passive then active-assisted flexion; avoid resisted extension. - **6-12 weeks:** Active extension and gentle strengthening. - **3-4 months:** Return to sport/heavy lifting once strength and full motion return. Stronger anatomic constructs allow a slightly more aggressive early-motion programme. **Prognosis:** Across systematic reviews, surgical repair gives **excellent patient-reported outcomes** (mean Mayo Elbow Performance Score ~92, high satisfaction), with **about 92% returning to pre-injury function** and essentially all patients regaining at least grade 4/5 extension strength. Outcomes are best for **acute** repairs; chronic, retracted tears requiring grafting do less well. The evidence below was retrieved from PubMed for this topic. Triceps rupture is rare, so the literature is dominated by **systematic reviews of observational series, large database cohorts, and biomechanical/cadaveric studies** rather than randomised trials.

Because the **anconeus** and the **intact lateral tendinous expansion** of the triceps provide weak residual extension. This is the "antigravity trap" - never exclude a complete tear on partial extension alone. Palpate for a gap and obtain a radiograph (fleck sign) or MRI. The **fleck sign** - a small avulsed flake of cortical bone pulled off the **posterior olecranon** - best seen on the **lateral** radiograph. It confirms an avulsion-type rupture at the enthesis. A **suture-anchor (double-row/footprint-restoring) repair** is reasonable: systematic reviews show **lower complication and re-rupture rates** than transosseous tunnels, and biomechanically it restores far more of the native footprint with higher load to failure. Transosseous tunnels remain an acceptable, familiar alternative. Acute repair (less than 3 weeks) allows direct anatomic reattachment. In **chronic tears** the tendon retracts and scars, so plan for **V-Y triceps turndown or Achilles tendon allograft augmentation**, and counsel the patient that outcomes are less reliable than acute repair.

There is **no large randomised trial or dedicated society guideline** for this rare injury, so practice is guided by systematic reviews and expert consensus. Practice is broadly consistent worldwide. **Registry note:** Unlike arthroplasty, there are no national joint-registry data for triceps tendon repair; the strongest population-level evidence comes from **large insurance-claims database cohorts** (e.g. Lee 2022), which inform risk-factor counselling rather than implant choice.