Vascularized Joint Flap
Anatomic considerations
Background
Vascularized joint transplantation provides a living joint. Because the tissue is vascularized, this type of joint replacement can last a lifetime, and is not prone to mechanical failure like a silicone or metal implant. Small joint arthroplasty of the metatarsophalangeal (MP) and proximal interphalangeal (PIP) joints can be challenging and is often limited to the low demand patient population. The vascularized joint can in selected cases of trauma or congenital absence offer joint replacement that is permanent and functional. Additionally, because an open epiphysis continues to develop after transplantation, reconstruction in children has the potential for growth. Stiffness can be problematic, but less so in the younger patient population. In addition, the vascularized joint can also provide soft tissue and bone where those have been lost by injury or infection. Tendon can also be included with the joint as a single unit.
Preoperative Assessment
Any traumatic injury or congenital absence requires a thorough preoperative evaluation by the microsurgeon. The hand is thoroughly assessed to determine the anatomy of the loss and the potential requirements for reconstruction. If a vascularized joint transplant is felt to be the reconstruction of choice, the surgeon must evaluate the lower extremity completely. This includes a history of previous injury or surgery, and a complete skeletal, vascular and sensorimotor examination. Particular attention should be paid to the pedal pulses. If arterial inflow is thought to be questionable whether by history or physical examination, then an angiographic study of the lower extremity is performed. We however do not routinely perform angiography of the lower extremity because we have found the vessel spasm of the foot to be particularly problematic in angiography, and this often leads to results that are of no value in determining joint vascular anatomy. In healthy individuals with no clear indication for angiography, the study does not help the surgeon either plan or execute the surgical procedure.
Anatomy
Either the PIP joint of the second toe and the MP joint of the second toe can used for small joint reconstruction. The MP joints of the foot are primarily extension joints with significantly more range of motion in extension. The opposite is true for the PIP joint. When the MP joint is used for reconstruction, it is typically placed with its extensor surface volarly and the flexor surface dorsally, thus maximizing finger flexion at the joint.
A vascularized joint can be constructed from the metatarso-phalangeal (MP) joint or the proximal interphalangeal (PIP) joint of the second toe. The MP joint is primarily an extension joint, while the PIP joint is a flexion joint.