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Mallet Fractures

- See:
      Distal Phalangeal Frx
      Mallet Finger

- Discussion:
    - may result from forceful hyper-extension;
    - displaced frx fragment moves volarly with the distal phalanx w/ DIP flexion
    - diff dx: dorsal DIP dislocation;
    - indications for treatment:
    - it is unclear whether the presence of small frxs will affect results;
    - open reduction w/ suture or pin fixation is necessary, if there is frx displacement of more than 40 % of articular surface or w/ volar subluxation of distal phalanx;
           - however, some orthopaedists will continue to treat these injuries closed, even with palmar subluxation of the joint (noting that a stiff finger treated closed is more preferable than a stiff finger treated open);
    - see: distal phalangeal frx;

- Extension Block K Wire:
    - DIP joint is hyperflexed;
    - a K wire is then inserted into the head of the middle phalanx (positioned dorsal to the mid line and is driven towards volar cortex);
    - the distal phalanx is then extended, until the frx fragment reaches the K wire;
           - the K wire acts as an extension block and facilitates reduction;
    - following reduction, a K wire is driven longitudinally across the DIP joint;
    - if reduction is difficult, consider applying tenaculum clamp applied to the mid-dorsal surface of the proximal fragment and applied to the mid-palmar surface of the distal fragment;
    - alternative:
           - k wire is inserted across the DIP joint;
           - second k wire is inserted through the mallet fragment, and the wire in inserted volarly through the pulp;
           - once inserted through the skin, the tip of the pin is bent and cut, and is then pulled dorsally so that the hook captures the mallet fragment and brings it into a reduced position;
    - controversies:
           - either an 18 gauge needle or a K wire can be inserted just over the dorsal aspect of the distal phalanx and into the middle phalanx;
                  - this can be performed in the ER (rather than the OR);
                  - the needle is removed at 4 weeks;
    - post op
           - the extension block K wire is removed at 4 weeks;
           - the longitudinal K wire is removed at 5-6 weeks;
           - additional splinting can be performed w/ Coband followed by a dorsally applied paper clip;

- Open Reduction:
    - exposure is achieved w/ a dorsal H shaped incision, w/ each longitudinal limb of the H incision made in the mid-axial line;
           - dissection needs to procede down to the tenosynovium before flaps are elevated;
    - mobilize the extensor tendon from side to side, inorder to see the fracture line;    

- Volar Plate Arthroplasty:
    - in the report by Rettig ME, et al, the authors evaluated 10 patients with chronic dorsal fracture subluxation of DIP joint were managed over 5 years with volar plate advancement arthroplasty;
          - mean time from injury to definitive surgical treatment was 8 weeks;
          - injuries were characterized by volar comminution and impaction of the distal phalanx, with associated dorsal subluxation;
          - surgical treatment included volar plate advancement arthroplasty and K-wire fixation of the reduced joint for 4 weeks;
          - all patients were evaluated at an average postoperative duration of 25 months (range, 10-60 months);
          - average arc of motion of the distal interphalangeal joint of the 4 fingers (6) was 42° and of the IP joint of the thumb (4) was 51 deg;
          - all patients had a residual flexion contracture averaging 12 deg
          - Volar plate arthroplasty of the distal interphalangeal joint

Mallet fractures.

Biomechanical analysis of mallet finger fracture fixation techniques.

Surgical treatment of mallet finger fractures by tension band technique.

Closed Reduction of Mallet Fractures Using Extension Block Kirschner Wire.

Volar plate arthroplasty of the distal interphalangeal joint

Modification of the extension block Kirschner wire technique for mallet fractures.

Extension block pinning for large mallet fractures