The medial triceps head dislocates over the medial epicondyle | Often snaps the ulnar nerve with it | Dynamic ultrasound is the key diagnostic test | Surgery when conservative care fails
TYPES OF SNAPPING ELBOW
Critical Must-Knows
- What it is: the medial head of the triceps (or an accessory anconeus epitrochlearis muscle) dislocates over the medial epicondyle during elbow flexion, producing a painful snap
- Ulnar nerve involvement is common: the dislocating muscle often carries the ulnar nerve with it, so patients may have both mechanical snapping and ulnar neuropathy symptoms (numbness in the little and ring fingers, weakness of the intrinsics)
- Dynamic ultrasound is the diagnostic gold standard: real-time imaging during active flexion and extension shows the muscle or nerve moving over the epicondyle — plain films and static MRI can miss it
- Conservative first: activity modification, avoiding provocative positions, NSAIDs, and night splinting; surgery (resection of the snapping portion of triceps, with ulnar nerve decompression or transposition if needed) for failed conservative care
- Think of it in overhead athletes: pitchers, javelin throwers, weightlifters, and gymnasts — anyone who repetitively loads the medial elbow in flexion
Clinical Pearls
- "Feel for the snap yourself — place your fingers over the medial epicondyle and ask the patient to flex and extend the elbow actively; the snap is often palpable and audible
- "Always test for ulnar nerve symptoms — the presence or absence of neuropathy changes management (isolated resection versus resection plus nerve transposition)
- "Dynamic ultrasound beats MRI because the pathology is positional — a static scan in extension may look completely normal
- "Distinguish snapping triceps from isolated ulnar nerve subluxation and from medial collateral ligament injury — the history and examination are different
Clinical Imaging
Critical Snapping Triceps Exam Points
Dynamic Ultrasound is the Key Test
The diagnosis is made by real-time dynamic ultrasound with the patient actively flexing and extending the elbow. Static imaging (plain X-ray, MRI at rest) often appears normal because the dislocation only happens with motion. If you suspect snapping triceps, order dynamic musculoskeletal ultrasound.
Ulnar Nerve Status Changes Management
The presence or absence of ulnar neuropathy is the critical branch point. Isolated snapping without neuropathy: resection of the snapping portion alone. Snapping with neuropathy: resection plus ulnar nerve decompression or anterior transposition. Always document sensation in the little finger and interosseous strength.
Distinguish from Isolated Ulnar Nerve Subluxation
Isolated ulnar nerve subluxation (Type III) snaps without a clear triceps component. The history is a snap with flexion but no palpable muscle band. Management is cubital tunnel release with or without transposition. Do not assume every snapping medial elbow is triceps-related.
Overhead Athletes are the Classic Population
Baseball pitchers, javelin throwers, weightlifters, and gymnasts place repetitive valgus and flexion stress on the medial elbow. In this group, think of snapping triceps alongside ulnar collateral ligament injury and valgus extension overload.
Memory aids
Overview
Snapping triceps syndrome is a cause of painful mechanical snapping over the medial aspect of the elbow. The condition occurs when the medial head of the triceps tendon or an accessory muscle band (the anconeus epitrochlearis) dislocates over the medial epicondyle during elbow flexion, often snapping back into place on extension. The snap is frequently accompanied by subluxation of the ulnar nerve, which lies in the cubital tunnel directly posterior to the medial epicondyle.
The syndrome is uncommon but well described in the literature, particularly in overhead throwing athletes, weightlifters, and gymnasts — anyone who repetitively loads the medial elbow in deep flexion. It can be unilateral or bilateral and may present with isolated mechanical symptoms or with combined mechanical snapping and ulnar neuropathy.
The examiner's challenge is to recognise the condition, distinguish it from isolated ulnar nerve subluxation and other causes of medial elbow pain, and confirm it with dynamic ultrasound — the diagnostic test of choice. Management is conservative initially; surgery (resection of the snapping structure, with or without ulnar nerve transposition) is reserved for patients with persistent symptoms.
Pathophysiology
Relevant anatomy
The medial head of the triceps brachii arises from the posterior aspect of the humerus distal to the radial groove and inserts onto the olecranon. In some individuals, an accessory muscle band — the anconeus epitrochlearis — arises from the medial head and crosses the cubital tunnel to insert onto the olecranon or the fascia over the medial epicondyle. This accessory band is present in approximately 10 to 25 percent of the population and is the anatomic substrate for snapping triceps in many cases.
The ulnar nerve passes through the cubital tunnel, a fibro-osseous canal bounded by the medial epicondyle anteriorly, the olecranon posteriorly, and the Osborne ligament (a fascial band between the two heads of the flexor carpi ulnaris) distally. The roof of the cubital tunnel is formed by a fibrous arcade. When the elbow flexes, the cubital tunnel narrows and the ulnar nerve normally glides slightly. In snapping triceps, the dislocating triceps tendon or accessory muscle band pushes the ulnar nerve anteriorly over the medial epicondyle, producing both the mechanical snap and neural compression.
Pathophysiology
The fundamental problem is a mechanical conflict between a mobile structure (the medial triceps tendon or an accessory band) and a fixed bony prominence (the medial epicondyle). During elbow flexion:
- The triceps tendon or accessory band moves anteriorly relative to the humerus.
- It encounters the medial epicondyle and is forced to dislocate over it.
- The ulnar nerve, if adjacent to the dislocating structure, is carried with it.
- On extension, the structure snaps back into its normal position.
Repeated dislocation causes repetitive traction and compression of the ulnar nerve, leading to focal demyelination, inflammation, and in chronic cases axonal loss. The snapping tendon itself can become irritated and inflamed, producing localized pain.
Clinical Pearl
The anconeus epitrochlearis is the classic anatomic variant responsible for snapping triceps, but any thickened or bifurcated medial triceps tendon can produce the same effect. The key concept is a mobile soft-tissue structure crossing a bony pulley.
Classification
Snapping elbow can be classified by the structure involved and by the presence or absence of ulnar nerve symptoms. This classification guides management.
Classification of Snapping Elbow
| Type | Structure involved | Ulnar nerve | Management |
|---|---|---|---|
| Type I — Isolated snapping triceps | Medial triceps head or accessory muscle band dislocates over medial epicondyle | No neuropathy | Conservative first; resection of snapping portion if symptoms persist |
| Type II — Snapping triceps with ulnar nerve subluxation | Dislocating triceps carries the ulnar nerve over the medial epicondyle | Neuropathy present (sensory and/or motor) | Resection of snapping portion plus ulnar nerve decompression or anterior transposition |
| Type III — Isolated ulnar nerve subluxation | Ulnar nerve subluxates alone without a clear triceps component | Neuropathy usually present | Cubital tunnel release with or without anterior transposition |
Clinical Pearl
Type II is the most common presentation in clinical practice because patients with a painless mechanical snap (Type I) often do not seek medical attention. The presence of ulnar nerve symptoms is the branch point that changes operative management from isolated resection to resection plus nerve transposition.
Clinical Presentation
History
Patients typically report a painful snapping or clicking sensation over the medial aspect of the elbow that occurs with flexion and resolves on extension. The snap may be audible and is often visible. Common features include:
- Mechanical symptoms: a palpable or audible snap with elbow flexion, often reproduced during everyday activities such as lifting, throwing, or push-ups
- Pain: aching or sharp pain localized to the medial epicondyle, worse after activity
- Ulnar nerve symptoms: numbness or tingling in the little and ring fingers, worse at night or with prolonged elbow flexion; in chronic cases, weakness of the interossei (difficulty spreading fingers) and thumb adduction (Froment sign)
- Activity history: overhead throwing, weightlifting, gymnastics, or occupations requiring repetitive elbow flexion under load
Physical examination
Inspection: there may be visible snapping over the medial epicondyle during active flexion and extension. Look for muscle wasting in the hand (interossei, hypothenar eminence) if chronic ulnar neuropathy is present.
Palpation: place the fingertips over the medial epicondyle and cubital tunnel and ask the patient to flex and extend the elbow actively. A palpable snap or subluxation of a tendon or nerve is often evident. Tenderness over the medial epicondyle and cubital tunnel is common.
Special tests:
- Ulnar nerve Tinel test: percussion over the cubital tunnel reproduces tingling in the ulnar nerve distribution — positive if neuropathy is present
- Elbow flexion test: holding the elbow in maximal flexion for 60 seconds reproduces ulnar nerve symptoms — positive in cubital tunnel syndrome or ulnar nerve subluxation
- Froment sign: the patient pinches a piece of paper between the thumb and index finger; weakness of the adductor pollicis (ulnar nerve) causes flexion of the thumb interphalangeal joint (compensation by flexor pollicis longus, median nerve)
- Wartenberg sign: the little finger drifts into abduction at rest due to weakness of the palmar interossei
Neurovascular examination: document sensation in the ulnar nerve distribution (dorsal and palmar aspects of the little finger and the ulnar half of the ring finger) and strength of the intrinsic hand muscles. Document two-point discrimination if neuropathy is suspected.
Clinical Pearl
The most reliable examination finding is the reproducible snap with active flexion felt by the examiner's fingers over the medial epicondyle. If you can feel it yourself, you have made the diagnosis clinically. Always pair this with a full ulnar nerve examination because the presence of neuropathy changes management.
Investigations
Imaging
Dynamic musculoskeletal ultrasound is the first-line and most valuable imaging test. It is performed with the patient actively flexing and extending the elbow while the transducer is placed over the medial epicondyle in a longitudinal orientation. Real-time imaging demonstrates:
- Dislocation of the medial triceps tendon or an accessory muscle band over the medial epicondyle
- Concomitant subluxation of the ulnar nerve
- The relationship between the snapping structure and the nerve
- Any anatomic variant such as a bifurcated medial triceps head or anconeus epitrochlearis
Magnetic resonance imaging (MRI) is useful for evaluating associated pathology but is a static test and may miss the dynamic dislocation. MRI can demonstrate:
- Enlargement and increased signal of the ulnar nerve on T2-weighted or fat-suppressed sequences
- Fluid in the cubital tunnel
- An accessory muscle band or bifurcated triceps tendon
- Thickening or signal change in the triceps tendon
Plain radiographs are usually normal but should be obtained to exclude bony pathology such as an avulsion fracture, osteophyte, or loose body.
Electromyography (EMG) and nerve conduction studies are indicated if ulnar neuropathy is suspected. Findings may include:
- Slowing of ulnar nerve conduction velocity across the elbow
- Prolonged distal motor latency
- Denervation changes in the ulnar-innervated intrinsic hand muscles (positive sharp waves, fibrillation potentials, reduced recruitment)
Diagnostic approach
Investigations in Snapping Triceps Syndrome
| Investigation | Role | Key finding |
|---|---|---|
| Dynamic ultrasound | First-line imaging; confirms diagnosis | Real-time dislocation of triceps and/or ulnar nerve over medial epicondyle during flexion |
| MRI | Static assessment of soft tissues and nerve | Ulnar nerve enlargement and T2 hyperintensity; accessory muscle band; cubital tunnel fluid |
| Plain X-ray | Exclude bony pathology | Usually normal; may show osteophytes or loose bodies as alternative causes |
| EMG / Nerve conduction | Assess ulnar neuropathy severity | Slowing across elbow; denervation in intrinsic hand muscles |
Clinical Pearl
If a patient has classic history and examination but static MRI is normal, do not be reassured — the diagnosis is made by dynamic ultrasound. Always request a dynamic musculoskeletal ultrasound study with active elbow flexion and extension.
Management
Conservative treatment is the first-line approach for all patients, particularly those without significant ulnar neuropathy. It includes:
- Activity modification: avoidance of provocative activities such as overhead throwing, deep elbow flexion, and heavy lifting
- Night splinting: a thermoplastic splint holding the elbow in 30 to 45 degrees of flexion prevents extreme flexion during sleep and reduces ulnar nerve compression
- Non-steroidal anti-inflammatory drugs (NSAIDs): for pain relief and reduction of peritendinous inflammation
- Physical therapy: stretching of the triceps and flexor-pronator mass, strengthening of the periscapular and rotator cuff musculature (in throwers), and technique modification
- Nerve gliding exercises: if mild ulnar neuropathy is present, neural mobilisation exercises may reduce symptoms
Conservative management has variable success. Patients with an identifiable mechanical snap and mild symptoms may improve with activity modification alone. Those with persistent symptoms after 3 to 6 months of conservative care are candidates for surgery.
Clinical Pearl
The critical operative decision is whether to transpose the ulnar nerve. If the nerve subluxates with the triceps and the patient has neuropathy, transposition is usually recommended to prevent ongoing traction and compression. In-situ decompression alone risks persistent symptoms if the nerve remains unstable.
Complications
Complications of Snapping Triceps Syndrome
| Complication | Context | Key point |
|---|---|---|
| Persistent snapping / recurrence | Inadequate resection of the snapping structure | Ensure complete resection of the accessory band or dislocating tendon at index surgery |
| Ulnar nerve injury | Surgical traction or inadequate transposition | Handle the nerve delicately; transpose if unstable to prevent postoperative neuropathy |
| Postoperative stiffness | Any elbow surgery | Early controlled mobilisation; avoid prolonged immobilisation |
| Infection | Any open surgery | Standard perioperative antibiotics and sterile technique |
| Medial epicondyle fracture | Rare; excessive bone removal or avulsion | Preserve the medial epicondyle and flexor-pronator origin |
| Incomplete relief of neuropathy | Chronic compression with axonal loss | Set realistic expectations; recovery may take months and may be incomplete if denervation is advanced |
Clinical Relevance
Snapping triceps syndrome is a high-yield topic because it tests the candidate's understanding of dynamic elbow pathology, ulnar nerve anatomy, and the interface between sports medicine and peripheral nerve surgery. Examiners may present it as:
- A sports-medicine case in an overhead athlete with medial elbow pain and snapping
- A peripheral nerve viva focusing on ulnar neuropathy at the elbow with an unstable nerve
- An imaging interpretation question showing dynamic ultrasound or MRI of the cubital tunnel
- A surgical technique question asking how to manage a patient with both snapping and neuropathy
The condition also illustrates broader principles: the importance of dynamic imaging for positional pathology, the need to assess nerve function in every case, and the concept that anatomic variants (the anconeus epitrochlearis) can produce clinically significant pathology.
Evidence
Snapping Triceps Syndrome: Review and Proposed Operative Treatment Algorithm
- Comprehensive literature review of snapping triceps syndrome and snapping elbow
- Proposed a treatment algorithm based on the presence or absence of ulnar nerve subluxation and neuropathy
- Recommended dynamic ultrasound as the diagnostic modality of choice
- Suggested resection of the snapping triceps portion with concomitant ulnar nerve transposition when neuropathy is present
Snapping Triceps Syndrome: Surgical Technique
- Detailed step-by-step surgical technique for resection of the snapping medial triceps head
- Described a medial approach with identification and protection of the ulnar nerve
- Emphasised resection of the dislocating tendon or accessory band while preserving triceps function
- Reported good outcomes with resolution of snapping and improvement in ulnar nerve symptoms when transposition was combined
Ultrasonographic Differential Diagnosis of Medial Elbow Pain
- Review of ultrasound findings in medial elbow pain including ulnar collateral ligament injury, ulnar neuropathy, and snapping triceps
- Described dynamic ultrasound technique for identifying ulnar nerve subluxation and snapping triceps
- Highlighted the utility of real-time imaging to distinguish between soft-tissue and neural causes of snapping
- Provided imaging criteria for cubital tunnel syndrome versus ulnar nerve instability
Bilateral Snapping Triceps Syndrome: A Case Report
- Case report of bilateral snapping triceps syndrome in a 47-year-old man
- Dynamic ultrasound confirmed bilateral dislocation of the medial triceps head over the medial epicondyle during elbow flexion
- MRI showed accessory muscle bands (anconeus epitrochlearis) bilaterally
- Patient was managed conservatively with activity modification and achieved symptom resolution
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
A Snapping Elbow in a Thrower (~4 min)
"A 22-year-old baseball pitcher presents with a 6-month history of painful snapping over the medial elbow when throwing. He also reports intermittent numbness in his little finger. The examiner asks you to take a history, examine him, and discuss your management."
History: I would ask about the onset, character, and timing of the snap — whether it is painful, audible, and reproducible with flexion. I would enquire about ulnar nerve symptoms (numbness in the little and ring fingers, night symptoms, hand weakness) and any history of trauma. I would ask about training load, throwing mechanics, and previous treatments.
Examination: I would inspect for visible snapping during active flexion and extension, palpate over the medial epicondyle and cubital tunnel for tenderness and a palpable snap, and perform a full ulnar nerve examination including Tinel test, elbow flexion test, Froment sign, Wartenberg sign, sensation in the ulnar distribution, and interosseous strength.
Investigations: I would request dynamic musculoskeletal ultrasound with active elbow flexion and extension to visualise the dislocating structure. I would also arrange an MRI to assess the ulnar nerve and soft tissues, plain X-rays to exclude bony pathology, and EMG/nerve conduction studies if ulnar neuropathy is confirmed clinically.
Management: Initial conservative management with activity modification, night splinting, NSAIDs, and physical therapy. If symptoms persist after 3 to 6 months, or if ulnar neuropathy is progressive, I would offer surgical resection of the snapping portion of the triceps. If the ulnar nerve is unstable or neuropathy is present, I would add ulnar nerve decompression and anterior transposition.
Operative Management of Snapping Triceps with Ulnar Neuropathy (~4 min)
"A 30-year-old weightlifter has failed 6 months of conservative management for snapping triceps syndrome. He has moderate ulnar neuropathy with numbness in the little finger, positive Tinel and flexion tests, and EMG showing slowing across the elbow. The examiner asks you to describe your operative plan."
Indication: Failed conservative management with progressive ulnar neuropathy is a clear indication for surgery.
Approach: I would use a medial approach to the elbow. The patient is positioned supine with the arm on a hand table or across the chest. A tourniquet is applied to the upper arm.
Steps: I would make an incision over the medial epicondyle, identify and protect the ulnar nerve throughout, release the cubital tunnel roof and Osborne ligament, identify the snapping portion of the medial triceps or the accessory muscle band, and resect it. I would then assess ulnar nerve stability — if the nerve subluxates or if neuropathy is moderate, I would perform anterior subcutaneous transposition of the ulnar nerve, ensuring no kinking and preserving the motor branches.
Closure and rehabilitation: I would close in layers, apply a soft dressing, and begin early controlled elbow mobilisation to prevent stiffness. Night splinting in slight flexion for 2 to 4 weeks. Return to sport is typically 3 to 6 months depending on the procedure and recovery.
Differentiating Causes of a Snapping Elbow (~3 min)
"A 25-year-old gymnast reports a snap over the medial elbow with flexion. The examiner asks you to list the differential diagnosis and explain how you would distinguish between them."
Differential diagnosis: The causes of a snapping medial elbow are snapping triceps syndrome, isolated ulnar nerve subluxation, synovial plica, loose body, and (less commonly) a snapping medial collateral ligament or anomalous muscle.
Clinical distinction: Snapping triceps produces a palpable tendon or muscle band snapping over the medial epicondyle, often with ulnar nerve symptoms. Isolated ulnar nerve subluxation snaps without a palpable muscle component. A synovial plica or loose body causes catching or locking within the joint rather than a superficial snap over the epicondyle. Medial collateral ligament injury causes valgus instability and pain with throwing, not a mechanical snap.
Imaging distinction: Dynamic ultrasound is the key test. It shows whether the snapping structure is the triceps tendon, the ulnar nerve, or an intra-articular fragment. MRI can show a loose body, ligament injury, or an accessory muscle band. Plain X-ray may show a loose body or osteophyte.
SNAPPING TRICEPS SYNDROME
Clinical summary
What It Is
- •Medial triceps head or accessory band dislocates over medial epicondyle
- •Often carries the ulnar nerve with it
- •Painful snap with elbow flexion; may be audible and palpable
- •Common in overhead throwers, weightlifters, gymnasts
Examination
- •Feel the snap yourself over the medial epicondyle during active flexion
- •Full ulnar nerve examination: Tinel, flexion test, Froment, Wartenberg
- •Look for intrinsic hand wasting if chronic neuropathy
- •Distinguish from isolated nerve subluxation and MCL injury
Investigations
- •Dynamic ultrasound: first-line, shows real-time dislocation
- •MRI: static assessment of nerve and soft tissues; may appear normal
- •X-ray: exclude loose body or bony pathology
- •EMG/NCS: quantify ulnar neuropathy if present
Management
- •Conservative first: activity modification, night splint, NSAIDs, physiotherapy
- •Surgery for failed conservative care or progressive neuropathy
- •Type I (no neuropathy): resection of snapping portion alone
- •Type II (neuropathy): resection plus ulnar nerve decompression/transposition
Operative Pearls
- •Medial approach; identify and protect ulnar nerve throughout
- •Resect the accessory band or dislocating tendon; preserve triceps function
- •Transpose the nerve if unstable or neuropathy is moderate to severe
- •Early mobilisation to prevent stiffness; return to sport at 3 to 6 months
Guidelines, Registries and Global Practice
- Diagnosis: Dynamic musculoskeletal ultrasound is the consensus first-line imaging test across orthopaedic and radiology literature worldwide. Static MRI and plain radiographs play supporting roles. There is no society guideline specific to snapping triceps, but the approach is consistent in sports-medicine and upper-extremity surgery literature from North America, Europe, and Asia.
- Conservative management: Activity modification, night splinting, and physiotherapy are universally accepted as first-line treatment. The duration of conservative trial varies (typically 3 to 6 months) depending on symptom severity and functional demands.
- Surgical approach: Resection of the snapping tendon or accessory muscle band is the standard operative treatment. The addition of ulnar nerve transposition when neuropathy is present is supported by case series and expert consensus, though no randomised trials compare in-situ decompression versus transposition specifically for snapping triceps.
- Athlete populations: Baseball pitchers (USA, Japan, Latin America), javelin throwers (Europe, Africa, Asia), and gymnasts (global) are the most frequently reported populations. Management principles are the same regardless of geographic setting, though access to dynamic musculoskeletal ultrasound and specialist hand/upper-extremity surgeons may vary by region.
- Prognosis: Most patients who undergo appropriate surgery (resection with or without nerve transposition) experience resolution of snapping and improvement in ulnar nerve symptoms. Recovery of chronic neuropathy may be incomplete if axonal loss is advanced.