Trapeziectomy

The radial styloid and proximal metacarpal are outlined and an incision mark is drawn.
This procedure can be performed under general anaesthetic or regional block.
Once the patient is supine with their arm on an arm board, the anaesthetic is checked and tourniquet inflated to 250mmHg, the incision is marked.
The incision is located from 5mm distal to the 1st CMCJ to the tip of the radial styloid.
It is useful to have the pre-operative radiographs available when planning the incision particularly if there is marked subluxation of the joint.

Skin is incised and blunt dissection through fat performed.Skin hooks can be used initially in to reveal the cutaneous nerves (branches of the superficial radial nerve and lateral cutaneous nerve of the forearm) allowing safe further dissection and placement of deeper retractors.
A self retainer is placed in the skin avoiding traction on cutaneous nerve branches. The overlying fat is divided in the line of the incision.

The APL and EPB tendons are exposed.Often the tendons of the first extensor compartment – APL and extensor pollicis brevis (EPB) – are then clearly visible.

Thin superficial fascia over tendons is divided.Occasionally however they can be covered by a thin fascial layer and may require a little more dissection to identify. There may also be a similar fascial layer beneath the tendons over lying the fat pad protecting the joint.

The deep fat on the capsule is bluntly dissected and capsule is exposed.Once exposed, the self retainer can now be placed between the two tendons which will avoid traction on the cutaneous nerves. The tendons are then mobilised a little distally to avoid them being under tension at the distal end of the wound and risking injury.
The capsule of the 1st CMCJ may be clearly visible or covered in a fat layer which needs mobilising.
At this point it is useful again identify the level of the radial styloid and the CMCJ referencing the pre-operative radiograph to recall the level of joint subluxation if any.
The CMCJ is usually easily identifiable by palpation and using the movement of the 1st metacarpal to delineate its distal extent. If this is proving difficult a hypodermic needle can be used to identify the joint or in difficult cases an image intensifier can be used although this is almost never required.
Once happy with the joint level the dorsal capsule of the joint is closely followed with scissors in blunt dissection to expose it deeper and more proximally. The dissection needs to be undertaken with care as during this process the dorsal branch of the radial artery is elevated off the capsule.

The proximal and dorsal path of the deep branch of the radial artery is exposed and protected.There are often small branches which enter the joint (pointed to on the picture) and will need coagulating as they can bleed easily if stretched and torn from careless dissection.

Pre-operative radiograph showing marked 1st CMCJ sclerosis and mild joint subluxation.

Lateral pre-operative radiograph showing 1st CMCJ sclerosis

The line drawing shows how vertical the CMCJ dorsal capsule and distal trapezium is and if this steepness is underestimated a surgeon can easily find themselves exposing or damaging the radial artery rather than leaving it in a cuff of fat.

A Watson-Cheyne elevator is placed into the Scapho-trapezium joint.Once the plane is created between the artery and the capsule a Ragnell retractor can be used to hold the artery proximally and allow a Hohmann retractor to be pushed into the scapho- trapezium joint.
Care must be taken when finding the joint as there is a groove in the centre of the dorsal trapezium (seen on previous slide line drawing) between the capsular attachments of the 1st CMCJ and Scaphotrapezium joint which the Hohmann can easily be pushed into in osteoporotic bone.

The 1st CMCJ capsule is incised in a distally based U flap around 1cm wide and lifted off the trapezium.Once the Hohmann is in place check the position of the self retainer as it can often rotate during dissection. Then proceed in elevating the fat off the rest of the capsule and periosteum of the 1st CMCJ and trapezium.
Be careful during this process of the artery which runs up over the dorsum of the trapezium and trapezial-trapezoid joint.
A retractor is then placed in the joint.

The rest of the capsule and periosteum are elevated palmarly and dorsally off the trapezium.Once the 1st CMCj is exposed by elevating the U flap, further confirmation of the correct location can be made by viewing the saddle shape of the joint and expected arthritic changes.
While completing these deeper dissections always cut away from the artery as the blade can easily jump if it catches on an osteophyte. Regularly ensure the self retainer has not moved – especially if the surgeon begins to struggle with a clear view during the dissection.
The saddle shape of the trapezium means that there is a prominence on the either side of the distal aspect of the bone. Protecting the tendons and artery these two prominences are dissected around to release the tension across the CMCJ and speed the dissection.
To make this process safer and easier it is essential to only sharp dissect under direct vision and the use a periosteal elevator to progress around the bone.
The elevator is kept close to the bone with a second hand on the skin overlying it pressing onto the instrument during dissection and once good progress is made in one area the elevator used like a Homann retractor and leant away from the bone will allow a better view of tissues under tension for further sharp dissection.
NOTE – The trapezium-trapezoid joint is often difficult to identify due to its orientation lying at a 45 degree angle dorso-ulnar to palmar-radial . This makes it easy to dissect further than necessary around the dorsum of the carpus.

The trapezium is split in half using an osteotome.It is difficult and unnecessary to remove the bone whole from this approach and can easily risk injury to the flexor carpi radialis (FCR) tendon in deep dissection if attempted. Therefore the bone is removed in pieces. Once the bone is adequately exposed, the final checks are completed before the osteotome is used.
Checks and occasions the check may fail:
Move metacarpal and the next proximal bone along is trapezium – good unless marked subluxation of 1st CMCJ (level of subluxation should be checked on pre-operative radiograph)
Saddle shaped joint- May be flattened in marked osteoarthritis (OA).
Dorsal branch of Radial artery overlying or proximal to bone – anatomy may vary
Whole bone being excised is distally to tip of radial styloid – fool proof check as long as there is not a scaphoid non-union (this should be noted on pre-operative radiographs).
The 10mm osteotome is placed in line with with the centre of the bone / deepest point of the distal trapezium joint surface and driven through the centre of the bone. The bone is split in half and the palmar half removed.

The trapezium is removed in pieces with a combination of blunt and sharp dissection.At this point it is useful to imaging the line the FCR tendon will take in the base of the wound from volar proximal, where it is palpable, to dorsal distal inserting on the 2nd metacarpal.
With this in mind the bone nibbles should never be used in deeper dissection perpendicular to the line of the tendon until the tendon can be seen and protected as they are easily sharp enough to divide or damage the tendon.
The FCR tenson and its direction can be seen in the photograph.

The trapezial-trapezoid joint need to be exposed to mobilise the dorsal half of the bone.
A probe can be seen in the joint and the FCR tendon can be seen in the top third of the wound.

The void created is felt for any remaining large bony fragments.It is not essential to removed every fragment of bone and often those flakes attached to the flexor retinaculum either side of the proximal end of the FCR are left in place. Large or sharp fragments are removed.
Once the bone is removed you should have a clear view of the FCR, the distal scaphoid and the trapezoid (as seen in the photograph). You may also have a view of the second metacarpal where it articulated with the trapezium.
Before closure a few areas need to be reviewed:
Place a finger around the volar tip of the metacarpal to make sure no large osteophytes or loose bodies remain.
Assess Scapho-trapezoid joint for OA – see next slide
Remove self retainer and check no bony fragments are held on the walls of the incision.

The scapho-trapezoid joint is examined for arthritis.The photograph shows how the Scapho-trapezoid joint is viewed using a McDonalds retractor and applying traction on the Index finger.
If arthritic a 3mm sliver of trapezoid can be removed to allow scar interposition between the bones to reduce pain.

The joint is washed out and the capsule is closed.This is made easier if the thumb is extended and safer if the needle is passed through the proximal capsule first directed away from the radial artery dorsal branch.

One deep dermal stitch is used to appose the skin.

The skin is closed with 4/0 monocryl with knots tied outside the skin on either end.

An adherent dressing is used.

Wool is wrapped around the hand leaving the fingers free to the MCPJs with thick padding in the first web space and the end of the roll of wool seated in the web to encourage extension and abduction. The thumb is covered to the level of the nail.

A dorsal plaster slab is applied.The plaster is gently moulded around the thumb and held in place with a bandage and tape.