Flexor Tendon Injuries - Hand (2023)

Updated: Aug 10 2022


Leah Ahn MD


Deborah Allen MD

Flexor Tendon Injuries


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Flexor Tendon Injuries - Hand (16)

Flexor Tendon Injuries - Hand (17)

  • summary

    • Flexor Tendon Injuries are traumatic injuries to the flexor digitorum superficialis and flexor digitorum profundus tendons that can be caused by laceration or trauma.

    • Diagnosis is made clinically byobserving the resting postureof the hand to assess the digital cascade andthe absence of the tenodesis effect.

    • Treatment is usually direct end-to-end tendon repair.

  • Epidemiology

    • Incidence

      • rare

        • occurs in 4.83 per 100,000

  • Etiology

    • Pathophysiology

      • mechanism of injury

        • commonly results from volar lacerations and may have concomitant neurovascular injury

      • pathophysiology

        • tendon healing

          • occurs via 2 pathways

            • intrinsic

              • produced by tenocytes within the tendon

            • extrinsic

              • stimulated by surrounding synovial fluid and inflammatory cells

              • implicated in the formation of scarring and adhesions

          • occurs in 3 phases

          • Phases of Tendon Healing

          • Phase

          • Days

          • Histology

          • Strength

          • Inflammatory

          • 0-5

          • Cellular proliferation

          • None

          • Fibroblastic

          • 5-28

          • Fibroblastic proliferation with disorganized collagen

          • Increasing

          • Remodeling

          • >28 days

          • Linear collagen organization

          • Will tolerate active range of motion

  • Anatomy

    • Muscles

      • flexor digitorum profundus (FDP)

        • functions as a flexor of the DIP joint

        • assists with PIP and MCP flexion

        • shares a common muscle belly in the forearm

        • has dual innervation

          • index and long fingers are innervated by the AIN of the median nerve

          • ring and small fingers are innervated by the ulnar nerve

      • flexor digitorum superficialis (FDS)

        • functions as a flexor of the PIP joint

        • assists with MCP flexion

        • individual muscle bellies exist in the forearm

          • FDS to the small finger is absent in 25% of people

        • innervated by the median nerve

      • flexor pollicis longus (FPL)

        • located within the carpal tunnel as the most radial structure

        • innervated by the AIN of the median nerve

      • flexor carpi radialis (FCR)

        • primary wrist flexor

        • inserts on the base of the second metacarpal

        • closest flexor tendon to the median nerve

        • innervated by the median nerve

      • flexor carpi ulnaris (FCU)

        • primary wrist flexor

        • inserts on the pisiform, hook of hamate, and the base of the 5th metacarpal

        • innervated by the ulnar nerve

    • Camper chiasm

      • located at the level of the proximal phalanx where FDP splits FDS

    • Pulley system

      • digits 2-5 contain

        • 5 annular pulleys (A1 to A5)

          • A2 and A4 arise from the periosteum

            • most important pulleys to prevent flexor tendon bowstringing

          • A1, A3, and A5 arise from the volar plate

        • 3 cruciate pulleys (C1 to C3)

          • collapsible and flexible

            • allows the annular pulleys to approximate each other during digital flexion

      • thumb contains

        • 3 annular pulleys (A1, Av, A2)

          • A2 contributes least to arc of motion of thumb

        • 1 interposed oblique pulley

          • most important pulley to prevent flexor tendon bowstringing (along with A1 pulley)

    • Blood supply

      • 2 sources exist

        • diffusion through synovial sheaths

          • occurs when flexor tendons are located within a sheath

          • it is the more important source distal to the MCP joint

        • direct vascular perfusion

          • nourishes flexor tendons located outside of synovial sheaths

          • supplied by

            • vincular systemosseous bony insertions, reflected vessels from the tendon sheath, and longitudinal vessels from the palm

            • osseous bony insertionsreflected vessels from the tendon sheath, and longitudinal vessels from the palm

            • reflected vessels from the tendon sheath

            • longitudinal vessels from the palm

  • Classification

      • Flexor Zones of Injury

      • Zone

      • Definition

      • Characteristics

      • Treatment

      • I

      • Distal to FDS insertion

      • Jersey finger

      • Direct tendon repair

      • II

      • FDS insertion to distal palmar crease/proximal A1 pulley

      • Zone is unique in that FDP and FDS in same tendon sheath (both can be injured within the flexor retinaculum).

      • Tendons can retract if vincula are disrupted.

      • Direct tendon repairfollowed by early ROM (Duran, Kleinert).

      • This zone historically had very poor results but results have improved due to advances in postoperative motion protocols.

      • III

      • Palm (A1 pulley to distal aspect of carpal ligament)

      • Often associated with neurovascular injury which carries a worse prognosis.

      • Direct tendon repair.

      • Good results from direct repair can be expected due to absence of retinacular structures (if no neurovascular injury).

      • May require A1 pulley release to avoid impingement of the repaired tendon on the pulley.

      • IV

      • Carpal tunnel

      • Often complicated by postoperative adhesions due to close quarters and synovial sheath of the carpal tunnel.

      • Direct tendon repair.

      • Transverse carpal ligament should be repaired in a lengthened fashion if tendon bowstringing is present.

      • V

      • Carpel tunnel to forearm

      • Often associated with neurovascular injury which carries a worse prognosis.

      • Direct tendon repair

      • Thumb

      • TI, TII, TIII

      • Outcomes different than fingers.

      • Early motion protocols do not improve long-term results and there is a higher re-rupture rate than flexor tendon repair in fingers.

      • Direct end-to-end repair of FPL is advocated. Try to avoid Zone III to avoid injury to the recurrent motor branch of the median nerve. Oblique pulley is more important than the A1 pulley; however both may be incised if necessary. Attempt to leave one pulley intact to prevent bowstringing

  • Presentation

    • Symptoms

      • loss of active flexion strength or motion of the involved digit(s)

    • Physical exam

      • inspection

        • observe resting posture of the hand and assess the digital cascade

          • evidence of malalignment or malrotation may indicate an underlying fracture

        • assess skin integrity to help localize potential sites of tendon injury

        • look for evidence of traumatic arthrotomy

      • motion

        • passive wrist flexion and extension allows for assessment of the tenodesis effect

          • normally wrist extension causes passive flexion of the digits at the MCP, PIP, and DIP joints

          • maintenance of extension at the PIP or DIP joints with wrist extension indicates flexor tendon discontinuity

        • active PIP and DIP flexion is tested in isolation for each digit

      • neurovascular

        • important given the close proximity of flexor tendons to the digital neurovascular bundles

  • Imaging

    • Radiographs

      • may have associated fracture

    • Ultrasound

      • used to assess suspected lacerations

  • Treatment

    • Nonoperative

      • wound care and early range of motion

        • indications

          • partial lacerations < 60% of tendon width

        • outcomes

          • may be associated with gap formation or triggering

    • Operative

      • flexor tendon repair and controlled mobilization

        • indications

          • lacerations > 60% of tendon width

      • flexor tendon reconstruction and intensive postoperative rehabilitation

        • indications

          • failed primary repair

          • chronic untreated injuries

      • FDS4 transfer to thumb

        • single stage procedure

        • indications

          • chronic FPL rupture

  • Techniques

    • Flexor tendon repair

      • indications

        • > 75% laceration

        • ≥ 50-60% laceration with triggering

          • epitendinous suture at the laceration site is sufficient

          • no benefit of adding core suture

      • fundamentals of repair

        • easy placement of sutures in the tendon

        • secure suture knots

        • smooth juncture of the tendon ends

        • minimal gapping at the repair site

        • minimal interference with tendon vascularity

        • sufficient strength throughout healing to permit application of early motion stress to the tendon

      • timing of repair

        • perform repair within three weeks of injury (2 weeks is ideal)

          • delayed treatment leads to difficulty due to tendon retraction

      • approach

        • incisions should always cross flexion creases transversely or obliquely to avoid contractures (never longitudinal)

        • meticulous atraumatic tendon handling minimizes adhesions

      • technique

        • core sutures

          • # of suture strands that cross the repair site is more important than the number of grasping loops

            • linear relationship between strength of repair and # of sutures crossing repair

            • 4-6 strands provide adequate strength for early active motion

          • high-caliber suture material increases strength and stiffness and decreases gap formation

          • locking-loops decrease gap formation

          • ideal suture purchase is 10mm from cut edge

          • core sutures placed dorsally are stronger

        • circumferential epitendinous suture

          • improves tendon gliding by reducing the cross-sectional area

          • improves strength of repair (adds 20% to tensile strength)

          • allows for less gap formation (first step in repair failure)

          • simple running suture is recommended

            • produces less gliding resistance than other techniques

        • sheath repair

          • theoretically improves tendon nutrition through synovial pathway

          • controversial

            • clinical studies show no difference with or without sheath repair

            • most surgeons will repair if it is easy to do

        • pulley management

          • historically believed to be critical to preserve

            • A2pulleys in digits

            • A4 pulleys in digits

            • oblique pulley in thumb

          • however recent biomechanical studies have shown

            • 25% of A2can be incised with little resulting functional deficit

            • 100% of A4 can be incised with little resulting functional deficit

        • FDS repair

          • in zone 2 injuries, repair of one slip alone improves gliding

          • compared to repair of both slips

      • outcomes

        • repair failure

          • tendon repairs are weakest between postoperative day 6 and 12

          • repair usually fails at suture knots

          • repair site gaps > 3mm are associated with an increased risk of repair failure

        • adhesion formation

          • increased risk with zone 2 injuries

    • Wide-awake flexor tendon repair

      • anesthesia

        • performed under tumescent local anesthesia using lidocaine with epinephrine

          • dosing

            • usually epinephrine 1:100,000 and 7mg/kg lidocaine

            • from 1:400,000 to 1:1000 is safe

            • if < 50cc is needed

              • 1% lidocaine with 1:100,000 epi for a 70kg person

            • if 50-100cc is needed

              • dilute with saline (50:50) to get 0.5% lidocaine, 1:200,000 epi

            • if 100-200cc is needed for large fields (tendon transfer, spaghetti wrist)

              • dilute with 150cc saline to get 0.25% lidocaine and 1:400,000 epi

            • for longer surgery > 2 hours

              • add 10cc of 0.5% bupivacaine with 1:200,000 epi

          • location

            • proximal and middle phalanges, use 2ml

            • distal phalanx, use 1ml

            • palm, use 10-15ml

        • no tourniquet, no sedation

      • 4 advantages

        • allows intraoperative assessment for repair gaps by getting awake patient to actively flex digit

        • reduces need for postop tenolysis by allowing intraoperative assessment of whether repair will fit through pulleys

          • allows on-the-spot debulking of bunched repairs

          • allows division of A4 pulley and venting (partial division) of A2 pulleys

        • allows repair of tendons inside tendon sheaths as patients can demonstrate that the inside of the sheath has not been inadvertently caught

        • facilitates postop early active motion

          • immobilize for 3 days

          • begin active midrange motion after day 3 (form a partial fist with 45 degree flexion at MP, PIP and DIP joints, or "half a fist 45/45/45 regime")

    • Flexor tendon reconstruction

      • requirements

        • supple skin

        • sensate digit

        • adequate vascularity

        • full passive range of motion of adjacent joints

      • techniques

        • single-stage procedures

          • only perform if the flexor sheath is pristine and the digit has full ROM

        • two-stage procedures

          • Hunter-Salisbury

            • Stage I - SR is placed to create a favorable tendon bed

            • Stage II (3-4 months) - SR is retrieved and a tendon graft is placed through the mesothelium-lined pseudosheath

              • pulvertaft weave proximally and end-to-end tenorrhaphy distally

          • Paneva-Holevich

            • Stage I

              • SR is placed in the flexor sheath, pulleys are reconstructed (as needed), and a loop between the proximal stumps of FDS and FDP is created in the palm

            • Stage II

              • SR is retrieved, FDS is cut proximally and reflected distally through the pseudosheath and either attached directly to FDP stump or secured with a button

            • advantages

              • graft (FDS) size is known at the time of silicone rod selection

                • less graft diameter-rod diameter mismatch

              • FDS graft is intrasynovial

                • fewer adhesions than extrasynovial grafts

              • relies on only 1 tenorrhaphy site (distal or proximal) to heal at any one time (vs. Hunter technique where 2 tennoprhaphy sites are healing simultaneously)

            • disadvantages

              • graft tensioning is at the distal end during stage II

                • the proximal end has already healed after stage I

        • graft selection

          • palmaris longus (absent in 15% of population)

            • most common

          • plantaris (absent in 19%)

            • indicated if longer graft is needed

          • extensor digitorum longus to 2nd-4th toes

          • extensor indicis proprius

          • flexor digitorum longus to 2nd toe

          • FDS

        • pulley reconstruction

          • one pulley should be reconstructed proximal and distal to each joint

          • pulley reconstruction should occur first if a tendon graft is being used

          • methods

            • belt loop method

            • FDS tail method

      • outcomes

        • subsequent tenolysis is required more than 50% of the time

    • Tenolysis

      • indications

        • localized tendon adhesions with minimal to no joint contracture and full passive digital motion

        • may be required if a discrepancy between active and passive motion exists after therapy

      • timing of procedure

        • wait for soft tissue stabilization (> 3 months) and full passive motion of all joints

      • technique

        • careful technique to preserve A2 and A4 pulleys

      • postoperative care

        • follow with extensive therapy

  • Postoperative Rehabilitation

    • Postoperative controlled mobilization has been the major reason for improved results with tendon repair

      • especially in zone II

      • leads to improved tendon healing biology

      • limits restrictive adhesions and leads to increased tendon excursion

    • Protocols

      • Immobilization

        • indicated for children and non-compliant patients

        • casts/splints are applied with the wrist and MCP joints positioned in flexion and the IP joints in extension

      • Early passive motion

        • Duran protocol

          • low force and low excursion

          • active finger extension with patient-assisted passive finger flexion and static splint

        • Kleinert protocol

          • low force and low excursion

          • active finger extension with dynamic splint-assisted passive finger flexion

        • Mayo synergistic splint

          • low force and high tendon excursion

          • adds active wrist motion which increases flexor tendon excursion the most

      • Early active motion

        • moderate force and potentially high excursion

        • dorsal blocking splint limiting wrist extension

        • perform “place and hold” exercises with digits

  • Complications

    • Tendon adhesions

      • most common complication following flexor tendon repair

      • higher risk with zone 2 injuries

      • treatment

        • physical therapy

        • tenolysis

          • perform if 4-6 months after tendon repair and significant loss of excursion

    • Rerupture

      • 15-25% rerupture rate

      • treatment

        • if < 1cm of scar is present, resect the scar and perform primary repair

        • if > 1cm of scar is present, perform tendon graft

          • if the sheath is intact and allows passage of a pediatric urethral catheter or vascular dilator, perform primary tendon grafting

          • if the sheath is collapsed, place Hunter rod and perform staged grafting

    • Joint contracture

      • rates as high as 17%

    • Swan-neck deformity

    • Trigger finger

    • Lumbrical plus finger

    • Quadrigia

Technique Guide Zones I-III Repair Orthobullets Team Hand - Flexor Tendon Injuries


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Flexor Tendon Injuries - Hand (33)

Private Note


Flexor Tendon Injuries - Hand? ›

Flexor tendon injuries typically occur from a cut on the palm side of your fingers, hand, wrist, or forearm. Flexor tendons can also be injured when a finger or thumb is violently pulled away from you while you are attempting to grasp something, such as the jersey of an opposing player in sports.

How long does flexor tendon injury take to heal? ›

The repaired tendon will usually be back to full strength after about 12 weeks. But, it can take up to 6 months to regain the full range of movement. In some cases, it may never be possible to move the affected finger or thumb as much as before it was damaged.

How do I know if I damaged a tendon in my hand? ›

If your extensor tendons are damaged, you'll be unable to straighten 1 or more fingers. If your flexor tendons are damaged, you'll be unable to bend 1 or more fingers. Tendon damage can also cause pain and swelling (inflammation) in your hand.

Can flexor tendon injury heal on its own? ›

Because the cut ends of a tendon usually separate after an injury, it is not likely that a cut tendon will heal without surgery. Your doctor will advise you on how soon surgery is needed after a flexor tendon is cut. There are many ways to repair a cut tendon, and certain types of cuts need a specific type of repair.

What happens if flexor tendon injury is left untreated? ›

No matter the cause of this injury, it is necessary to have a hand doctor examine and treat it. If left untreated, the tendons can remain severed and you can lose the ability to bend your fingers.

How do you know if your flexor tendon is torn? ›

Common signs and symptoms of flexor tendon injuries include: Difficulty bending one or more fingers. Numbness on one or both sides of the finger, which indicates damage to the nerve. Loss of blood flow to the finger when the blood vessel is cut (which would lead to white or purple discoloration of the finger).

What does a torn flexor tendon feel like? ›

Pain may be more pronounced when the finger is bent. Tenderness, bruising, or swelling may be present on the palm side of the hand along the affected digit.

What is the most common hand tendon injury? ›

Mallet Finger

This is the most common closed tendon injury. Mechanism of Injury: Forced flexion of the extended DIP joint, most commonly associated with catching a ball.

Can you move your fingers with a torn tendon? ›

If you do injure the tendons in your hand or wrist, you may have trouble bending or straightening your fingers. Tendon damage can cause pain, stiffness, swelling and tenderness. Your hands are among the most complex parts of your body, which means you need specialized care after a tendon injury in your hand or fingers.

How do you treat a flexor tendon injury? ›

In most cases, a cut or torn tendon must be repaired by a surgeon. Surgery is usually performed within 7 to 10 days after an injury. In general, the sooner surgery is performed, the better recovery will be. If your injury is restricting blood flow to your hand or finger, your doctor will schedule an immediate surgery.

When is it too late to repair a flexor tendon? ›

Late secondary repair is done more than 4 weeks after injury. After 4 weeks it is extremely difficult to deliver the flexor tendon through the digital sheath, which usually becomes extensively scarred.

What are common flexor tendon injuries? ›

Most commonly, a flexor tendon injury results from lacerations (cuts). A laceration to the forearm, hand or wrist can result in injury to the flexor tendons. When a flexor tendon injury happens there can be inability to bend the fingers, thumb or wrist.

What is common flexor tendon pain? ›

Flexor tendinopathy is usually caused by activities that require repetitive use of the muscles that control the wrist, hand and fingers. The problem/pain is felt in the tendons of these muscles, on the inside of the arm. The overuse of these muscles can cause tiny tearing and degeneration or breakdown of the tendon.

How common are flexor tendon injuries? ›

Flexor tendon injuries account for <1% of all hand injuries. Management of these injuries often poses a surgical challenge because the results remain unpredictable results despite the best efforts.

Should you stretch a damaged tendon? ›

Stretching is not indicated for tendon tears or ruptures. You should be properly evaluated prior to starting a stretching program.

When should I see a doctor for a tendon injury? ›

But if your symptoms get worse or if you develop additional symptoms you should call your doctor sooner rather than later. Some warning signs that you probably need medical treatment include: Continuous redness or swelling around the joint accompanied by fever or chills. These may be signs of an infection.

What are the phases of flexor tendon healing? ›

Tendon phases of healing include the inflammatory phase (0 to 2 weeks following repair), the fibroplasia phase, or reparative phase, (approximately 2 to 6 weeks following repair), and the remodeling phase (more than 6 weeks following repair).

How long does a Grade 2 flexor strain arm take to heal? ›

Typical recovery time

A wide range of timetables exists for flexor tendon injuries. Depending on the severity, they can carry a recovery time of anywhere from 1-2 weeks to 1-2 months. If surgery is required, recovery can take upwards of six months.


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