Code 25447
Code 25447, Arthroplasty, interposition, intercarpal or carpometacarpal joints, represents an interposition arthroplasty of either intercarpal or carpometacarpal joints. It is performed by excising part of one or more of the respective bones and then inserting soft tissue, such as an anchovy of tendon or a piece of fascia, between them. The interposition tissue acts as a spacer to maintain the space between the bones and create a fibrous ankylosis between them. The following two examples provide descriptions of (1) carpometacarpal (CMC) arthroplasty of a nonthumb joint followed by (2) a CMC joint arthroplasty of the thumb.
CMC Excluding Thumb
Through a linear skin incision, the carpometa-carpal joint capsule is exposed and then incised transversely. Either the distal surface of the carpal bone or the proximal surface of the metacarpal bone is removed. The donor tendon or fascia is rolled and placed between the two bones. A Kirschner wire is inserted through the metacarpal and the adjacent metacarpal for fixation. The joint capsule is closed with sutures. The hand and wrist are immobilized in a splint.
CMC Including Thumb
A CMC joint arthroplasty of the thumb is a commonly performed procedure. The base procedure described by 25447 is as follows. A curvilinear incision is made over the radial aspect of the proximal first metacarpal extending proximally over the trapezium and trapezio-scaphoid joint. The interval between the slips of the abductor pollicis longus is developed and the periosteum over the base of the first metacarpal and trapezium is elevated along with dorsal and palmar flaps of the first CMC and scaphotrapezial capsules. The trapezium is carefully removed, taking care not to injure the adjacent radial artery and flexor carpi radialis. (Some surgeons will remove the base of the first metacarpal.) The interposition material chosen by the surgeon is placed in the defect created by removal of the trapezium. Usually an autologous tendon is used though other tissues such as fascial lata and allografts have been used. The interposition material is secured in the trapezial defect. A temporary Kirschner wire is often used to stabilize the arthroplasty. The capsule is closed and a splint applied.
If the surgeon chooses a tendon graft as the interposition material, and if the tendon is harvested at a different site through a separate incision(s), the harvesting of the tendon graft should be coded separately with 20924, Tendon graft, from a distance (eg, palmaris, toe extensor, plantaris). If, on the other hand, the surgeon harvests a local tendon (ie, flexor carpi radialis or abductor pollicis longus) through the same incision as that used for the arthroplasty, it is included in the basic procedure and is not reported separately. While the harvesting of local tendons can require counter-incisions to free the tendon graft proximally, such accessory incisions would not be coded in addition to the arthroplasty.
Variation: Suspension Arthroplasty
Dr Richard Burton popularized a variation of the basic CMC joint arthroplasty of the thumb procedure in which the first metacarpal is suspended to the second metacarpal to inhibit the proximal migration of the first metacarpal that often occurs after simple excisional arthroplasty of the first CMC joint. This suspension arthroplasty requires additional surgical maneuvers. Typically, one half (or all) of the FCR is used to create the new intercarpal ligament between the first and second metacarpals. To accomplish this, the FCR is exposed through a series of transverse forearm incisions. One half of the tendon is detached from the muscle belly proximally and brought into the distal trapeziectomy wound. The tendon is dissected to its insertion on the base of the second metacarpal. A hole is drilled in the radial aspect of the base of the first metacarpal and the liberated half of the FCR is passed through this hole and secured to the lateral aspect of the first metacarpal with a suture. The remaining free FCR is woven around the intact FCR (still attached to the muscle belly proximally and second metacarpal distally) and/or abductor pollicis longus and sutured into the trapeziectomy defect. A Kirschner wire can be used for temporary stabilization.
The transfer of the FCR to the base of the first metacarpal is not a part of the basic first CMC arthroplasty procedure and must be coded in addition to 25447 with either 26480, Transfer or transplant of tendon, carpometacarpal area or dorsum of hand; without free graft, each tendon, or 25310, Tendon transplantation or transfer, flexor or extensor, forearm and/or wrist, single; each tendon, as appropriate. Modifier 51 would be appended to the secondary procedure in either the 2544 7 + 26480 or 25310 code pairs.
The work involved with the suspension arthroplasty is similar to that of a tendon transfer. In both the tendon transfer and suspension, a tendon is harvested and transferred to a different site. In addition, both procedures require exact tensioning of the tendon transfer. In an active tendon transfer, the proper tension is needed to provide motion; in the suspension, the proper tension is needed to permit motion of the first ray (thumb) but inhibit proximal migration of the first metacarpal.
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Dr.Mohd Ali Hadi CPC, CPC-H