Arthrodesis of the MP joint and Finger Joints : Wheeless' Textbook of Orthopaedics

- Thumb MP Joint: Tension Band Technique:

- needs to be fused in 10-20 deg flexion, 20 deg pronation, and 20 deg of abduction;

- tension band can neutralize the distraction force of the finger flexors (which are stronger than extensors and therefore cause distraction);

- dorsal incision is made over the joint;

- extensor tendon is split longitudinally and halves are retracted;

- joint surfaces are molded into opposition;

- because of the cam shape of the phalangeal (or metacarpal heads) more molding is required on the volar surface (where visualization is difficult);

- transverse drill hole is made thru dorsal surface of distal bone segment;

- stainless steel wire is then inserted thru the hole;

- it is easier to perform this now, rather than after transected bone surfaces have been reduced and fixed;

- two parallel K wires are placed across the joint to provide rotational stability;

- wires are first inserted retro-grade thru the proximal bone segment's dorsal bone surface at the mid point;

- joint is reduced in desired position of flexion;

- wires are then driven down meduallary canal of distal fragment;

- angle is fusion is controlled by flexing the digit (to appropriate level) and driven wires parallel to dorsal phalangeal surface;

- tension band wire is then figure of 8 wrapped over dorsal surface of bone, and wrapped around protruding K wires of proximal fragment;

- K wires are bent, cut, and rotated;

- tension wire is tensioned w/ needle driver;

- wire is cut, and bent;

- after one week, the other digits can resume normal ROM;

- fusion usually occurs at 4-6 weeks;

- PIP Joint Fusion:

- place the PIP joint in maximal flexion, and remove the distal end of the proximal phalanx w/ a volar slope;

- articular cartilage is removed from the base of the middle phalanx;

- as the finger is brought from a hyperflexed to a slightly flexed position, the transected bone ends are brought under tension;

- position of fusion:

- 20-25 deg of flexion in the index finger;

- 30 deg of flexion in the long finger;

- 40 deg of flexion in the ring finger;

- 40-50 deg of flexion in the little finger;

- fixation:

- longitudinal K wire is placed across the joint;

- oblique K wire is placed across the joint;

- DIP Joint Fusion:

- usually DIP joints of the lesser fingers are fused in a straight position (or slight flexion);

- use an H shaped incision w/ the vertical limbs placed as mid lateral incisions;

- this exposure allows access to the distal portion of the collateral ligaments;

- the distal flap should be full thickness down to extensor tendon inorder to ensure viability;

- DIP joint is distracted, joint surface is removed, and the bone ends are made congruous (either flat or cup in cone);

- use 0.035 inch K wire to drill hole for 26 guage (or No. 0) stainless steel wire;

- hole is inserted 5 mm from bone ends, dorsal to the mid-axis;

- wire loop is made but is not tightened down until after a longitudinal K wire is inserted retrograde across the joint;

- wire is tightened down, and end is placed into intra-osseous hole;

- controversies: intentional fibrous union:

- based on the observation that many "failed" DIP joint fusions (fibrous union) remain pain free and yet maintain some motion;

- procedure is best indicated in the little and ring fingers, but is less indicated in the thumb, index, and long fingers (where a stable pinch is more important);

- technique involves excision of the joint and insertion of 2 K wires for 2 weeks;

- after 2 weeks, the wires are removed and the joint is splinted for an additional 2 weeks;

- complications:

- quadriga

- result of quadriga is decreased grip strength;

- may be most pronounced in the index and long fingers;

- may be prevented by fusion w/ DIP flexion;