summary Jersey Finger is a traumatic flexor tendon injury caused by an avulsion injury of the FDP from the insertion at the base of the distal phalanx. Diagnosis is made clinically with a finger that lies in slight extension at the DIP relative to other fingers in the resting position. Radiographs may show a bony avulsion if present. Treatment is usually direct tendon repair or open reduction and internal fixation depending on the presence and size of a bony avulsion. Epidemiology Anatomic location ring finger involved in 75% of cases during grip ring fingertip is 5 mm more prominent than other digits in ~90% of patients therefore ring finger exposed to greater average force than other fingers during pull-away Etiology Pathophysiology FDP muscle belly in maximal contraction during forceful DIP extension Anatomy Muscles Flexor Digitorum Profundus (ulnar n. and AIN n.) Flexor zones zone I extends from insertion of FDS distally Classification Leddy and Packer classification (based on level of tendon retraction and presence of fracture) Type Description Treatment Type I FDP tendon retracted to palm. Leads to disruption of the vascular supply Prompt surgical treatment within 7 to 10 days Type II FDP retracts to level of PIP joint Attempt to repair within several weeks for optimal outcome Type III Large avulsion fracture limits retraction to the level of the DIP joint Attempt to repair within several weeks for optimal outcome Type IV Osseous fragment and simultaneous avulsion of the tendon from the fracture fragment ("Double avulsion” with subsequent retraction of the tendon usually into palm) If tendon separated from fracture fragment, first fix fracture via ORIF then reattach tendon as for Type I/II injuries Type V Ruptured tendon with bone avulsion with bony comminution of the remaining distal phalanx (Va, extraarticular; Vb, intra-articular) Presentation Physical exam pain and tenderness over volar distal finger finger lies in slight extension relative to other fingers in resting position no active flexion of DIP may be able to palpate flexor tendon retracted proximally along flexor sheath Imaging Radiograhs may see avulsion fragment Treatment Operative direct tendon repair or tendon reinsertion with dorsal button or suture anchor indications acute injury (< 3 weeks) technique advancement of > 1 cm carries risk of a DIP flexion contracture or quadrigia postoperative rehab should include either early patient assisted passive ROM (Duran) or dynamic splint-assisted passive ROM (Kleinert) ORIF fracture fragment indications types III and IV (for type IV then repair as for Type I/II injuries) techniques with K-wire, mini frag screw or pull out wire examine for symmetric cascade once fixation completed two stage flexor tendon grafting indications chronic injury (> 3 months) in patient with full PROM of the DIP joint DIP arthrodesis indicated as salvage procedure in chronic injury (> 3 months) with chronic stiffness Complications Quadrigia advancement of > 1 cm carries risk of a DIP flexion contracture or quadrigia