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 by observing the resting posture of the hand to assess the digital cascade and the 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 login to view 7 more bullets 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 login to view 2 more bullets flexor digitorum superficialis (FDS) functions as a flexor of the PIP joint assists with MCP flexion individual muscle bellies exist in the forearm login to view 1 more bullet 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) login to view 4 more bullets 3 cruciate pulleys (C1 to C3) login to view 2 more bullets thumb contains 3 annular pulleys (A1, Av, A2) login to view 1 more bullet 1 interposed oblique pulley login to view 1 more bullet Blood supply 2 sources exist diffusion through synovial sheaths login to view 2 more bullets direct vascular perfusion login to view 6 more bullets 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 repair followed 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 login to view 1 more bullet 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 login to view 2 more bullets 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 login to view 1 more bullet outcomes login to view 1 more bullet Operative flexor tendon repair and controlled mobilization indications login to view 1 more bullet flexor tendon reconstruction and intensive postoperative rehabilitation indications login to view 2 more bullets FDS4 transfer to thumb single stage procedure indications login to view 1 more bullet Techniques Flexor tendon repair indications > 75% laceration ≥ 50-60% laceration with triggering login to view 2 more bullets 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) login to view 1 more bullet approach incisions should always cross flexion creases transversely or obliquely to avoid contractures (never longitudinal) meticulous atraumatic tendon handling minimizes adhesions technique core sutures login to view 7 more bullets circumferential epitendinous suture login to view 5 more bullets sheath repair login to view 4 more bullets pulley management login to view 7 more bullets FDS repair login to view 2 more bullets outcomes repair failure login to view 3 more bullets adhesion formation login to view 1 more bullet Wide-awake flexor tendon repair anesthesia performed under tumescent local anesthesia using lidocaine with epinephrine login to view 15 more bullets 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 login to view 2 more bullets 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 login to view 2 more bullets Flexor tendon reconstruction requirements supple skin sensate digit adequate vascularity full passive range of motion of adjacent joints techniques single-stage procedures login to view 1 more bullet two-stage procedures login to view 18 more bullets graft selection login to view 8 more bullets pulley reconstruction login to view 5 more bullets 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 login to view 2 more bullets Kleinert protocol login to view 2 more bullets Mayo synergistic splint login to view 2 more bullets 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 login to view 1 more bullet 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 login to view 2 more bullets Joint contracture rates as high as 17% Swan-neck deformity Trigger finger Lumbrical plus finger Quadrigia