Jersey Finger – Causes, Symptoms and Treatment

Last Updated on November 3, 2025

Jersey finger refers to an avulsion of the flexor digitorum profundus (FDP) tendon from its insertion on the volar base of the distal phalanx. The injury results from a forceful hyperextension of the distal interphalangeal joint while the tendon is actively contracting during flexion. This shearing force overcomes the tensile strength of the tendon-bone interface, pulling the FDP away from its attachment.

Jersey finger represents a zone I flexor tendon injury (see below), and the term “jersey finger” arose from contact sports (particularly rugby and American football), where the injury commonly occurs as a player grasps an opponent’s jersey that is suddenly pulled away [1]. It is also known as sweater finger or rugby finger, highlighting its sports-related mechanism.

The ring finger is affected in nearly 75% of cases.

Relevant Anatomy

The flexor apparatus of each digit comprises the flexor digitorum profundus (FDP) and the flexor digitorum superficialis (FDS) tendons. Both originate in the forearm, traverse the carpal tunnel, and enter the fibro-osseous digital sheath at the level of the metacarpophalangeal joint. The FDS tendon splits into two slips to allow the FDP tendon to pass through—a configuration that led to the FDP being termed the “perforator” muscle, while the FDS is referred to as the “perforatus.”

The FDP tendon inserts on the volar base of the distal phalanx, acting as the sole flexor of the DIP joint. Its slips to the index and middle fingers are supplied by the anterior interosseous nerve (branch of the median), whereas those to the ring and little fingers receive innervation from the ulnar nerve.

The blood supply of the FDP tendon is derived from branches of the digital arteries through the vincula longa and vincula brevia. These vincula play a vital role in maintaining tendon viability after injury. When both are torn as in severe retraction injuries, the tendon rapidly becomes avascular and undergoes degeneration, necessitating urgent repair.

The tendons are contained within a pulley system comprising five annular (A1–A5) and three cruciform pulleys. The A4 pulley, located over the middle phalanx, is particularly important in jersey finger because it often halts the retracted tendon in Type III injuries when an avulsed bone fragment is present. Preservation or careful reconstruction of this pulley during surgery is crucial to prevent bowstringing and maintain efficient flexion mechanics.

Anatomically, the FDP muscle belly arises from the upper three-fourths of the ulna and interosseous membrane and transitions into tendon form approximately 5 cm proximal to the wrist. Its muscle belly is broad and powerful, enabling strong finger flexion. However, this bulk also contributes to the injury. During the sudden forced extension that produces jersey finger, the contracted muscle mass exerts maximal tension on the tendon, which fails at its distal insertion, where tensile and shear stresses are greatest.

Pathophysiology and Mechanism of Injury

The jersey finger results from a sudden forced extension of the distal interphalangeal joint while the flexor digitorum profundus is actively contracting. This usually occurs when a player clutches an opponent’s jersey and the opponent suddenly jerks away. The strong extensor moment leads to an avulsion of the FDP tendon from its insertion at the distal phalanx.

The injury sequence begins with a sudden eccentric loading of the FDP tendon. If this force exceeds the structural limits of the insertion, detachment occurs. The extent of this detachment depends on the angle of applied force, tendon condition, and vincular integrity. [1]

In pure soft-tissue avulsion, the tendon may retract as far as the palm (Type I injury), especially when vincular continuity is lost. In cases involving a small bony fragment, the fragment itself may impede proximal migration by snagging against the pulley system, often at the A2 or A4 pulley.

Why Ring Finger Most Commonly Involved?

The ring finger is particularly susceptible for two key anatomic reasons [3].

• During flexion, it projects approximately 5 mm farther than adjacent digits, exposing it to greater traction forces during any pull-away event.
• Its tendon slip is anchored between two lumbricals. One is shared with the middle finger and the other with the little finger, creating a tethered configuration. This bilateral constraint magnifies longitudinal stress transmission.

The junction between the flexor digitorum profundus (FDP) tendon and the distal phalanx forms a fibrocartilaginous enthesis, a graded interface that transitions from soft tendon to hard bone. When a sudden traction force acts on the finger, this zone fails by shearing through the fibrocartilage rather than detaching cleanly from the bone.

If the injury is not repaired promptly, the tendon retracts, forms scar tissue, and the tiny vincular vessels at the stump resorb, changes that make later reattachment difficult and reduce the chance of full recovery. Retraction patterns are clinically important because they dictate both timing and approach to repair (discussed in classification).

Additionally, the energy of injury correlates with concomitant damage to the flexor sheath and pulleys. High-energy avulsions can tear the sheath and produce partial pulley rupture, increasing the risk of postoperative bowstringing if not addressed at the time of repair.

Classification of Jersey Finger

Leddy and Packer classification (1977) is based on the level of tendon retraction, integrity of the vincular system, and presence or absence of an associated bony fragment. It correlates directly with the vascular status of the tendon, the surgical approach, and the expected outcome. [1,2,3]

Type I

• The most severe form involves high-energy mechanisms with forceful extension and complete vincular disruption.
• FDP tendon retracts into the palm after complete rupture of both the long and short vincula. As a result, the tendon loses all vascular supply and undergoes rapid ischemic necrosis.
• No associated bony fragment, and the retracted tendon may be palpable in the distal palm.
• Urgent surgical repair within 7–10 days is required. Delay beyond this period results in fibrosis, shortening, and an increased likelihood of requiring staged tendon reconstruction.

Type II

• The most common variant
• The tendon retracts to the level of the proximal interphalangeal (PIP) joint. The long vinculum remains intact, providing limited vascular continuity and preventing further retraction.
• No bony fragment is typically present, although small flakes may be seen on radiographs.
• Because vascularity is partly preserved, surgical repair can be delayed for a few weeks without compromising the result.
• Generally carries a good prognosis when repaired anatomically.

Type III

• A large bony fragment is avulsed from the volar base of the distal phalanx along with the tendon
• Retraction is limited by the A4 pulley at the middle phalanx, where the bony fragment becomes lodged.
• As the vincula and tendon attachment to bone remain intact, the vascularity of the tendon is usually preserved.
• Repair involves fixation of the bony fragment (usually by mini-screw, Kirschner wire, or suture anchor) without the need for tendon advancement.
• Outcomes are typically excellent if treated within several weeks.

Type IV

• Called “double avulsion” injury
• FDP tendon avulses a bony fragment from the distal phalanx but then separates from that fragment, leaving both free within the sheath.
• The tendon stump retracts proximally (often to the palm), while the bony fragment remains caught at the level of the A4 pulley.
• The bone fragment must be reduced and fixed, followed by reattachment of the tendon to the distal phalanx.
• Failure to recognize the double component can lead to nonunion of the bone fragment or incomplete restoration of tendon function.

Type V

• Include complex avulsion injuries involving bony comminution of the distal phalanx or intra-articular fracture–dislocations of the DIP joint.
  • Type Va – extra-articular bony avulsion with comminution
  • Type Vb – intra-articular fracture–dislocation associated with FDP avulsion
• As the tendon attachment is disrupted and bone integrity compromised, these injuries require combined fixation and tendon repair
• Bone grafting may be needed
• DIP arthrodesis if reconstruction is unfeasible.

Clinical Presentation

Patients with jersey finger typically present with pain and swelling after an acute traction injury to the finger. The patient may recall the snap or immediate loss of grip strength at the time of trauma. The usual mechanism is an attempted grasp that is suddenly resisted.

On examination, there is swelling and tenderness along the volar aspect of the affected finger, particularly over the distal phalanx. The digit often appears slightly extended at the distal interphalangeal (DIP) joint compared with neighboring fingers.[3]

There is loss of active flexion at the DIP joint, although passive flexion remains full and painless unless associated with a fracture. In acute settings, swelling or ecchymosis may obscure deformity.

The absence of active DIP motion is a reliable indicator of FDP detachment.

Palpation may reveal a gap or thickened cord along the flexor sheath corresponding to the retracted tendon. The location of this palpable mass can help infer the level of tendon retraction:

• A bulge near the PIP joint suggests Type II,
• A lump in the mid-palm indicates Type I,
• And absence of a palpable mass with tenderness over the middle phalanx may correspond to Type III.

Isolated FDP Function Test

Accurate examination requires isolation of the FDP from the flexor digitorum superficialis (FDS). To test FDP integrity, the examiner stabilizes the patient’s PIP joint in extension and asks for active flexion at the DIP joint. Failure to flex confirms FDP rupture or avulsion.

In contrast, to test the FDS, other digits are held in extension while the patient flexes the PIP of the affected finger.

These tests help to distinguish jersey finger from partial flexor injury, tendon adhesion, or central slip lesions that may mimic reduced flexion.

Differential Diagnosis

The most common clinical mimic is mallet finger, which also presents with DIP extension deformity. However, in mallet finger, the extensor tendon is avulsed from the dorsal base of the distal phalanx, leading to an inability to extend, not flex, the DIP joint.
Other differential considerations include:

• Volar plate avulsion at the PIP joint,
• Distal phalanx fracture without tendon detachment
• Flexor sheath rupture from penetrating trauma
• Zone II or III tendon injuries may masquerade as more distal lesions.

Imaging

Plain Radiographs

Anteroposterior, lateral, and oblique views of the affected digit are the initial investigations. In pure soft-tissue avulsion, X-rays may appear normal. However, when an osteotendinous fragment is present (Type III–V), a small triangular or rectangular bony fragment can be seen on the volar aspect of the distal phalanx near the DIP joint. Radiographs also help exclude intra-articular fracture–dislocations or comminuted avulsions that alter surgical planning.

Ultrasound

High-frequency ultrasound is a useful, low-cost modality to visualize the tendon stump and its level of retraction. It can also assess tendon integrity, vincular continuity, and surrounding sheath fluid.

MRI

MRI provides the most detailed evaluation of flexor tendon injuries. It enables accurate determination of tendon continuity, retraction distance, and sheath disruption. It is able to differentiate different types of avulsions, thus aiding in treatment planning.

CT

CT is rarely required but may be indicated in complex bony avulsions or intra-articular comminution to define the geometry of the distal phalanx fragment before fixation.

Management of Jersey Finger

The management of jersey finger is primarily surgical, as spontaneous healing of a retracted flexor digitorum profundus (FDP) tendon is virtually impossible. The goals of treatment are to restore the tendon’s anatomic insertion, preserve pulley integrity, and prevent flexion contracture of the distal interphalangeal (DIP) joint. [2,4]

The ideal window for repair is within 7–10 days for Type I injuries and within 2–3 weeks for other types where vascularity is preserved. After this period, tendon contraction and scarring limit direct reinsertion, necessitating grafting or arthrodesis. [1]

Non-operative management is rarely appropriate and reserved only for chronic, low-demand, or medically unfit patients, with the understanding that permanent loss of active DIP flexion will persist.

Surgical Options

Direct Tendon Repair or Re-insertion

This is the preferred technique for acute soft-tissue avulsions (Type I–II). Through a volar Bruner or mid-lateral incision, the retracted tendon is identified, mobilized, and advanced distally under controlled tension. The distal phalanx point is decorticated to bleeding bone, and the tendon is reattached using one of the following fixation methods. The following techniques are commonly applied

• Pull-out wire or button technique: A non-absorbable suture is passed through the tendon and out the nail dorsum, tied over a button for 3–4 weeks. [1]
• Suture anchor fixation: Now widely favored, anchors eliminate the need for dorsal hardware and permit early mobilization.
• Mini-screw with washer or bone tunnel fixation: Used when a small bony shell is available for re-approximation.

Excessive advancement beyond 1 cm is avoided, as it can produce a quadriga effect, where shortening of one FDP slip limits flexion in adjacent fingers due to shared muscle belly tension.

Open Reduction and Internal Fixation (ORIF) of Bony Avulsion

In Type III, the avulsed bone fragment with attached tendon is reduced and fixed directly to the distal phalanx using a countersunk mini-screw, Kirschner wire, or suture anchor. The fixation must be rigid enough to permit controlled early motion while avoiding joint penetration.

In Type IV (double avulsion), both lesions are addressed. The bone fragment is first stabilized, followed by tendon reattachment to the bone base. The procedure requires meticulous handling to prevent loss of fragment alignment and ensure smooth tendon gliding under the A4 pulley.

Two-Stage Flexor Tendon Reconstruction

This is used for chronic or neglected injuries (usually > 3 months old) where the distal stump is scarred and retracted, or passive distal interphalangeal motion is still preserved.

• Stage 1: A silicone (Hunter) rod is implanted to maintain the tendon sheath and create a pseudotendon channel.
• Stage 2: It is done 6–8 weeks later. The rod is replaced with an autologous tendon graft (commonly palmaris longus or plantaris) sutured proximally to the FDP muscle and distally to the distal phalanx base with an anchor or pull-out technique.

Good outcomes depend on joint suppleness, intact pulleys, and disciplined postoperative therapy.

Distal IP Joint Arthrodesis

In cases of painful stiffness, irreparable avulsion, or advanced arthritic change, DIP fusion provides a functional and painless digit. Arthrodesis is positioned in 15–20° of flexion, allowing optimal pinch function. It is a salvage option for chronic or multiply operated fingers.

References

• Elzinga KE, Chung KC. Finger Injuries in Football and Rugby. Hand Clin. 2017 Feb;33(1):149-160. [PubMed]
• Goodson A, Morgan M, Rajeswaran G, Lee J, Katsarma E. Current management of Jersey finger in rugby players: case series and literature review. Hand Surg. 2010;15(2):103–7. [DOI]
• Abrego MO, Shamrock AG. Jersey Finger. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545291/
• Freilich AM. Evaluation and treatment of jersey finger and pulley injuries in athletes. Clin Sports Med. 2015 Jan;34(1):151-66. [PubMed]