A toenail flap based on the fibro-osseous hiatus branch for fingernail reconstruction.

This study included two parts: 1) cadaver dissection to elucidate the perfusion of toenail flaps by the fibro-osseous hiatus branch (FHB), and 2) clinical application of the toenail flap for reconstruction of a fingernail defect. Four second toes of two fresh Korean cadavers were dissected. The plantar digital artery (PDA) and terminal segment branch (TSB) were ligated, and red latex was injected distally into the ligated PDA. Perfusion of the dye into the toenail bed through the FHB was observed. From Oct 2004 to Sep 2009, eight toenail flaps based on the FHB pedicle with or without the distal phalanx and pulp were applied to seven patients for finger nail reconstruction. The toenail flap was marked at 5 mm distal to the nail fold and 5 mm lateral to the paronychium. The toenail complex based on the FHB was elevated and transferred to the finger. The nail and matrix were elevated with or without including the distal phalanx. The results of perfusion study showed that one side of the unilateral FHB was identified and traced proximal to the PDA, which was ligated. The distal toenail bed was perfused by the dye through the FHB. In clinical application, all the toenail flaps flourished and survived. We suggest that the toenail flap based on the FHB may be useful for fingernail reconstruction with minimal donor morbidity.

Arterial anatomy of the second toe nail bed related to toenail transfer.

The aim of this study was to elucidate the exact course of the terminal branches of the plantar digital artery (PDA) to the nail bed of the second toe. Thirteen second toes from seven fresh Korean cadavers were dissected (age range 74-92 years, four men and three women). The terminal segmental branches (TSB) branched off from the PDA at 7.6 ± 0.7 mm proximal to the nail fold. The fibro-osseous hiatus branch (FHB) branched off from the PDA at 3.3 ± 0.7 mm from the nail fold. They were 3.8 ± 1.0 mm lateral to the paronychium. Diameters of TSB and FHB were 0.8 ± 0.2 mm and 0.7 ± 0.1 mm, respectively. Diameter of PDA was 1.4 ± 0.2 mm. Surgeons should stay at least 4 mm proximal to the nail fold to avoid injury to the terminal branch. We believe that second toenail with minimum amount of soft tissue may be transferred using FHB-based vascularized toenail flap. Perfusion study and clinical application should be followed.

Flexor tendon tissue engineering: bioreactor cyclic strain increases construct strength.

Mutilating injuries of the hand and upper extremity result in tendon losses too great to be replaced by autologous grafts. The goal of this study was to use tissue engineering techniques to produce additional tendon material. We used a custom bioreactor to apply cyclic mechanical loading onto tissue-engineered tendon constructs to study ultimate tensile stress (UTS) and elastic modulus (E). Constructs used were acellularized rabbit hindpaw flexor digitorum profundus equivalents reseeded with tenocytes or left unseeded. Tendon constructs were subjected to a stretch force of 1.25 N over a 5-day course. Seeded tendon constructs that were exposed to bioreactor loading had a significantly increased UTS (71.17 +/- 14.15 N) compared to nonloaded controls (35.69 +/- 5.62 N) (p = 0.001). Similarly, seeded constructs exposed to bioreactor loading also had a significantly higher E (1091 +/- 169 MPa) compared to nonloaded controls (632 +/- 86 MPa) (p = 0.001). This study shows that cyclic loading of tendon constructs increases the UTS and elastic modulus of seeded constructs. The use of the bioreactor may therefore accelerate the in vitro production of strong, nonimmunogenic tendon material that can potentially be used clinically to reconstruct significant tendon losses.

Flexor tendon tissue engineering: temporal distribution of donor tenocytes versus recipient cells.

BACKGROUND: Tissue-engineered tendon material may address tendon shortages in mutilating hand injuries. Tenocytes from rabbit flexor tendon can be successfully seeded onto acellularized tendons that are used as tendon constructs. These constructs in vivo exhibit a population of tenocyte-like cells; however, it is not known to what extent these cells are of donor or recipient origin. Furthermore, the temporal distribution is also not known. METHODS: Tenocytes from New Zealand male rabbits were cultured and seeded onto acellularized rabbit forepaw flexor tendons (n = 48). These tendon constructs were transplanted into female recipients. Tendons were examined after 3, 6, 12, and 30 weeks using fluorescent in situ hybridization to detect the Y chromosome in the male donor cells. One unseeded, acellularized allograft in each animal was used as a control. RESULTS: The donor male tenocytes populate the epitenon and endotenon of the grafts at greater numbers than the recipient female tenocytes at 3 and 6 weeks. The donor and recipient tenocytes are present jointly in the grafts until 12 weeks. At 30 weeks, nearly all cells are recipient tenocyte-like cells. CONCLUSIONS: Donor male cells survive in decreasing numbers over time until 30 weeks. The presence of cells in tissue-engineered tendon grafts has been shown in prior studies to add to the strength of the constructs in vitro. This study shows that recipient cells can migrate into and repopulate the tendon construct. Cell seeding onto tendon material may create stronger constructs that will allow the initiation of motion earlier.