Lunate Resection and Vascularized Pisiform Transfer in Kienböck Disease
Several techniques of resection–interposition have been described in the literature for Lichtman stage III Kienböck disease:
Interposition of the head of capitate in Graner′s technique1
A metal or Silastic lunate prosthesis
Other techniques have used the pisiform as a graft4 or have used a vascularized bone graft5 or a vascular pedicle implantation for stage II. In 1982 we proposed replacement of the collapsed lunate by a living bone: the vascularized pisiform6 ( Fig. 31.1 ).
This technique is indicated in Lichtman stages IIIa (i.e., a normal 45-degree radioscaphoid angle) and IIIb Kienböck disease (when the bone is collapsed or fragmented with an increased radioscaphoid angle, 60 degrees or more).
It is preferably performed for patients under 45 years of age.
Manual workers may benefit from this procedure.
This procedure should not be performed at stage I (i.e., normal X-ray images or a linear fracture through the lunate) or II (i.e., increased density on plain X-ray images but no lunate collapse) of this disease, when lunate vascularization may be stabilized or improved by other procedures.
It should not be performed for other diseases that are frequently misdiagnosed as Kienböck disease, such as intraosseous synovial cysts or osteoid osteomas.
It is contraindicated in Lichtman stage IV, when there is complete lunate collapse associated with radiocarpal and midcarpal osteoarthritis.
The relevant anatomy has been discussed by Heymans and Koebke.7
The pisiform is not a sesamoid.
The arterial blood supply of the pisiform bone comes from three pedicles, which form an arterial circle ( Fig. 31.2 )8: an upper pedicle arising from the dorsal carpal artery, a lateral pedicle arising from the ulnar artery, and a lower pedicle arising from the deep palmar branch of the ulnar artery, which was used in the pisiform transposition described by Beck.4
We transfer the pisiform based on the upper pedicle, which is the cubitodorsal artery, a dorsal branch of the ulnar artery. This artery originates 4 cm proximal to the proximal crease of the wrist and may have two patterns: (a) a single vertical artery running distally, reaching the proximal end of the pisiform, and connecting the periosseous vascular circle around the pisiform ( Fig. 31.3 ); (b) a horizontal artery that irrigates the ulnar skin of the distal forearm and from which originate two or three arteries, branching perpendicularly and running distally to the pisiform and its periosseous vascular circle.
From an evolutionary point of view, the pisiform was fused with the triquetrum, but with the emergence of forearm pronosupination in Homo sapiens, it became a separate bone covered by the flexor carpi ulnaris (FCU) tendon.
Considering the relative sizes of the pisiform and triquetrum, the height of the two bones is relatively similar, but the width, length, and volume of the pisiform are less than in the triquetrum ( Table 31.1 ).7 The articular surface of the pisiform that articulates with the triquetrum is relatively flat; therefore, there is less congruity with the head of the capitate after transfer. The proximal pole of the pisiform, however, is congruent with the lunate fossa of the radius.
Plain X-ray images are taken to stage the disease and to determine whether there is radiocarpal or midcarpal osteoarthritis.
Magnetic resonance imaging (MRI) is used to assess the bone vascularity, and hand arthro computed tomography (CT) scan is performed to assess the articular cartilage of the distal radius.
Wrist arthroscopy may also be useful to assess the chondral surfaces of the distal radius and of the midcarpal joint.
A pisiform view is obtained positioning the forearm in 30 degrees of supination from neutral and the tube perpendicular to the film to measure the real size of the pisiform ( Fig. 31.4 ).
The patient is in the supine position and a tourniquet is used. Axillary brachial plexus block anesthesia is recommended.
Approach and Dissection of the Pisiform
The incision is made parallel to the FCU tendon at the anteromedial aspect of the forearm, beginning 4 cm proximal to the distal wrist crease. At the level of the distal wrist crease, it is curved radially and continued distally for 2 cm into the palm ( Fig. 31.5 ).
The FCU tendon is retracted radially or ulnarly. The cubitodorsal artery, which branches off of the ulnar artery, becomes apparent ( Fig. 31.6a,b ). A vessel loop is placed around the ulnar nerve, which is protected throughout the procedure. The cubitodorsal artery is dissected with its veins and subcutaneous tissues distally until it reaches the pisiform. Any other horizontal branches are ligated. The pisiform is then detached from the triquetrum, cutting the capsule between the two bones, taking care to preserve the periosseous arterial circle coming from the cubitodorsal artery ( Fig. 31.7 ). The pisi-unciform ligament underneath the ulnar nerve is preserved and harvested with the pisiform. The FCU tendon is detached from the pisiform along with the tissue covering this bone and sutured to the capsule of the triquetrum or the abductor digiti minimi tendon.