Scheker DRUJ Prosthesis Surgical Demonstration Images From Two Cases for Clarity

Demonstrating unstable DRUJ

Demonstrating unstable DRUJ

Demonstrating unstable DRUJ

Forearm in full pronation, 8-9 cm long hockey stick incision along ulnar border of distal forearm, turning radially just distal to the head of the ulna for additional 2 cm.

Ioban steridrape or comparable alternative is recommended to reduce contact between the skin and implant.

Dissection between subcutaneous tissue and the forearm fascia.

Barrier flap design of soft tissue incorporating both fascia and proximal retinaculum based ulnarward & extending radially to the second compartment.

Flap elevated from radial to ulnar, incorporating the capsule present over the head of the ulna for extra cushion.

The ECU Tendon Sheath is Released to Its Distal Origin The ECU is elevated and it’s tendon sheath is released to it’s distal insertion. This prevents possible tethering of the tendon against the prosthesis.

The ECU is elevated and it’s tendon sheath is released to it’s distal insertion. This prevents possible tethering of the tendon against the prosthesis.

EDQM and EIP are elevated from the ulna and interosseous membrane. Extensor mass is elevated to expose the interosseous crest of radius. The distal posterior interosseous nerve is divided to prevent avulsion from the extensor mass.

Neck of the ulna is being prepared for osteotomy after the interosseous membrane is released.

Arthritic Ulnar Head

Interosseous membrane is divided from the crest of the radius.

An elevator is placed volar to the radius and the ulna is levered volarly to allow exposure of the entire ulnar side of the radius.

The Area of the Sigmoid Notch is Identified and Any Osteophytes in the area are excised

Volar Lip often requires contouring for proper radial plate placement Improper Dorsally Angulated Position Proper Position

Reducing volar lip of radius by means of a saw blade

A Burr can also be used to Contour the Radius for the Radial Plate Trial

The Radial Plate Trial is Positioned on the Ulnar border of the Radius in the Area of the Sigmoid Notch. Its Volar Facing Edge is aligned with the Volar Surface of the Radius. Using .045” K-wires the Trial is temporarily fixed to the Radius

The Volar Surface of the Radius is Visualized to Ensure Proper Placement of the Radial Plate Trial

The Trial’s position is checked using an image intensifer. The PA view confirms distal clearance and general alignment. The lateral view ensures the plate is neither dorsally or volarly angulated

The center oval guide hole is drilled first to allow optional final adjustments. Care is taken to ensure the hole passes transversely through the radius without violating the dorsal or volar cortex.

The Hole is then Tapped Prior to Introduction of a 3.5 mm Cortical Bone Screw Self Tapping Screws are NOT used to Allow the Interchanging of Screws if Necessary

With the center screw in place and proper positioning confirmed, the radial peg drill bit can be passed through the trials distal guide hole. The bit is typically inserted until its stopping plate contacts the trial. Care should be taken to ensure the peg bit

Does Not

violate the dorsal or volar cortex or pass through the radius.

The proximal k-wire is removed and radiographic confirmation used to confirm final positioning. The profile of the trial with the radial peg bit in place will mimic what should be seen when it is replaced by the actual prosthesis.

Trial alignment, screw direction - length, radial peg bit direction and depth are confirmed. If the dorsal or volar cortex is violated by the peg or screws they should be removed and redirected.

The Radial Plate is Introduced by first inserting the Radial Plate Peg into the pre drilled hole. Care is taken to ensure no tissues are trapped between the plate the the radius.

A Plastic Impactor is provided to protect the Radial Plate when using a mallet for insertion

The screw for the oval hole is first applied followed by up to 4 additional fixation screws

Radial plate positioning checked. Excessive screw length should be avoided as well as contact between the peg and the distal screw.

The forearm is placed in full pronation (radius at its shortest relative length), and the ulnar resection guide is inserted along the ulna and into the hemi socket of the radial plate. The ulna is then juxtaposed against the guide

.

With the forearm in full pronation, the proximal edge of metal lip below the ball indicates the appropriate level of resection for a standard length ulnar stem. Should additional ulna be missing, the resection guide is marked in 1 cm increments allowing the selection of the appropriate extended ulnar stem.

The osteotomy is made transversely through the ulna

2 mm guide wire is inserted into the ulna’s medullary canal to act as a centralizing guide.

A cannulated drill bit is inserted over the guide wire, the medullary canal is drilled to a depth of 11 cm from the distal end of ulna. Care should be taken to ensure the bit remains within the medullary canal. This is regardless of the ulnar stem length selected.

A reamer, rounded proximally to prevent misdirection, is inserted into the canal to cut a Bevel in the distal ulna.

The Reamer is inserted until its Stopping Plate contacts the Distal Ulna

Reaming Complete

Contact with the Ulnar Stem is kept to a minimum during Its insertion

During insertion the ulnar stem will meet resistance as the plasma spray engages the ulna. A plastic impactor is then used to protect the distal polished peg of the ulnar stem

Periodically the impactor should be removed and the relationship between the radial plate and the ulnar stem checked.

Care should be taken not to over insert the Ulna Stem. Regardless of the Ulnar Stem length used, the distal end of stem should be no more proximal than the distal end of the Radial Plate. This relationship will provide full support of the UHMWP ball.

The distal Radial Plate and the distal Ulnar Stem should be at the same level when the stem is fully inserted Standard Length Ulnar Stem 1 cm Extended Length Ulnar Stem

The UHMWP ball is placed over the Distal Peg of Ulnar Stem affectively replacing the function of the articular surface of the Ulna Head

Demonstrating Range Of Motion

Placement of the Radial Plate Cover, ensuring the mating surfaces are free of any interposing material and securing it with two small screws completes the Prosthesis. Care should be taken to firmly secure the screws with out stripping them. If there is any doubt, replace with new screws. The secured cover stabilizes the artificial Joint as would an intact TFC in regards to a normal DRUJ.

Adequacy of overall positioning and Screw Length is Confirmed

The Fascial-Retinacular Flap dissected during the approach is identified. This flap is to be positioned under the ECU and used as a barrier between the prosthesis and the ECU.

The Fascial-Retinacular Flap under the ECU and over the prosthesis provides a cushioning barrier for the tendon.

Barrier Flap sutured into position under the ECU tendon and the EDQM.

With the implant rigidly in place, the skin is closed in a normal manner, bulky soft tissue dressings are used. Should any doubt exist as to the implants fixation, a short arm splint should be applied.