Spare-Part Vascularized Bone Flap in the Management of Ulnar Ray Deficiency

The term spare-part flap in limb reconstruction indicates the utilization of a flap from the amputated part of the limb to aid in the reconstruction of the same limb. To our knowledge, this concept has not been previously utilized in patients with ulnar ray deficiency. The author reports on a child with ulnar ray deficiency, presenting with hypoplastic floating little finger and soft-tissue deficiency of the ulnar border of the hand. The soft-tissue defect was reconstructed with a vascularized bone flap from the littler finger, utilizing the spare-part principle.

A 1-year-old boy presented to the author with unilateral left ulnar ray deficiency ([Fig. 1A, B]). The little finger was floating and hypoplastic with no metacarpal. The ring finger had camptodactyly. Immediately proximal to the little finger, there was soft-tissue deficiency at the ulnar border of the hand. There was mild deviation of the wrist; however, wrist flexion and extension were good. Reconstruction was done under general anesthesia and tourniquet control. The nail and the distal part of the distal phalanx were removed first from the floating little finger. The skin was then de-epithelized from the remaining part of finger, preserving its blood supply ([Fig. 1C]). The finger was supplied with a single neurovascular bundle on the radial side. A longitudinal incision was made on the ulnar border of the hand just proximal to the little finger. The tourniquet was released, and bleeding was noted from the de-epithelized finger flap indicating a good blood supply ([Fig. 1D]). The bone flap (which included the dermis as well as the bones and the surrounding flexor/extensor apparatus) was flipped into the soft-tissue defect on the ulnar border of the hand. Primary skin closure over the bone flap was obtained by undermining the dorsal and volar skin. There were no postoperative complications. At final follow-up (2 years later), the cosmetic appearance was acceptable, and the parents were happy with the result ([Fig. 2A]). X-rays showed preservation of the bone flap with no evidence of bone resorption ([Fig. 2B]). Surgery for the camptodactyly was planned. Wrist function remained the same with no worsening of wrist deviation.

Fig. 1 (A) Preoperative clinical appearance. Note the hypoplastic floating little finger and the soft-tissue deficiency at the ulnar border of the hand at the base of the finger. (B) X-ray with an arrow pointing to the soft-tissue deficiency. (C) Intraoperative view showing the de-epithelized little finger after excision of the nail and the distal part of the distal phalanx. (D) The tourniquet has been released and there was good bleeding from the bone flap.

Fig. 2 (A) Clinical appearance 2 years after surgery. (B) X-ray showing the bone flap in place with no evidence of bone resorption.

Our case represents the first description of utilizing the spare-part principle in ulnar ray deficiency in the literature. The spare-part principle is commonly used in the surgical management of other congenital abnormalities such as thumb duplication and synpolydactyly.[1] [2] Another indication for using the spare-part principle is hand trauma. The bones from a crushed finger is removed, preserving the blood supply the skin envelope. The “fillet” finger flap is then utilized to reconstruct dorsal or volar hand defects.[3] The finger “fillet” flap may also be utilized to reconstruct a complex skin defect in an adjacent finger in a spare-part cross-finger flap fashion.[4] Finally, the spare-part principle may also be utilized in sarcoma surgery. For example, sarcoma of shoulder girdle frequently requires forequarter amputation. The resulting large soft-tissue defect at the stump is best reconstructed using a spare-part forearm free flap harvested from the amputated limb.[5]

There are many advantages of the spare-part principle in upper limb reconstruction such as simplicity, providing a vascularized flap, possibility of providing a sensate flap and, most importantly, avoiding additional donor site morbidity. The hand surgeon should always keep in mind the possible use of this principle in various congenital, traumatic, and oncologic upper limb surgeries.

Publication History

Article published online:
17 September 2020

• References

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