Hypothenar hammer syndrome after radial forearm flap harvest: a case report

A case of acute hypothenar hammer syndrome (HHS) in a high-risk laborer in whom the radial artery had been surgically removed during a prior radial forearm flap harvest is reported. Studies estimating the true incidence of HHS among laborers are reviewed to define the risk of this complication. Two major risk factors must be considered in the assessment of a patient for radial forearm flap harvest. First, the risk for immediate vascular compromise is determined by using a standard Allen's test to assess ulnar artery contribution to hand perfusion. Second, the risk for future vascular compromise is determined. When patients at high risk for HHS are recognized the surgeon should consider other reconstructive alternatives. If the superficial palmar arch is patent and complete and a radial forearm flap is performed, postoperative activity modification and risk counseling should be provided.     

The bottom-up approach to the suprafascial harvest of the radial forearm flap

Suprafascial radial forearm flaps cause far less donor morbidity compared with the conventional method of including the deep fascia. Here we describe our technique of harvesting the flap with a bottom-up approach, which simplifies flap elevation and is safe and expedient. The radial artery pedicle is ligated distally and secured to the flap. Gentle traction on the pedicle presents the inferior surface of the pedicle, facilitating dissection. The superficial layer of the deep fascia is taken with the flap, together with a generous cuff of subcutaneous tissue above the pedicle in which vessels nourishing the flap are located. It is crucial to preserve the conjoin of the deep layer of the deep fascia to the fascia covering the brachioradialis laterally and flexor carpi radialis medially. This fascial layer prevents bow-stringing of the tendons during wrist and finger flexion and allows the use of a full-thickness skin graft to close the donor site. The latter delivers superior cosmetic results than can be achieved with a split-thickness skin graft.     

The radial forearm flap

Described in 1981 by the Chinese authors Yang Kuofan et al. [1] as a free flap, then in 1982 by Lu et al. [2] as a retrograde flow pedicle flap, this fasciocutaneous flap is designed at the level of the anterior and external faces of the forearm, and vascularized by the radial artery via a network of septal arteries. Prior to utilization it must be reversed on its distal pedicle. This flap allows repairing cutaneous substance loss of the whole hand and fingers. The emergence of the Chinese flap in the 1980’s resulted in a regression of the Mac Gregor groin flap that was widely used at this time [3,4]. Nevertheless, other forearm flaps, less “expensive” in terms of vascular involvement [5–9] have reduced its indications. The Chinese flap however keeps two essential indications: the multi-finger important defect that no other forearmflapmay cover; and composite substance loss of the thumb (despite the fact that the Chinese flap shares these indications with interosseous artery composite flaps).     

Reestablished circulation after free radial forearm flap transfer

New circulation in the free flap reestablished at the recipient site is the key to successful microvascular reconstructive surgery. This study is the first evaluation of long-term circulatory changes in nine free radial forearm flap transfers. Postoperatively, color Doppler studies revealed that the flow volume through the arterial pedicle increased rapidly during the first 3 days, gradually increased until day 14 (exceeding flow volume through the facial artery of the unoperated contralateral side), then decreased slightly until the sixth month. The pulsatility index, representing vascular resistance downstream, decreased successively. Ohm's law explains that this flow increase is caused by reduced vascular resistance downstream, attributed to changes in the vascularity of the transferred flap and in the recipient bed. The authors believe the circulatory changes are determinants of the clinical properties of the flap. This study addresses the importance of clarifying the events that transpire at the macroscopic circulatory level in the transferred free flap.     

Suprafascial compared with subfascial harvest of the radial forearm flap: an anatomic study

PURPOSE: Inclusion of the deep fascia within the radial forearm flap is conventionally thought to be essential for flap viability. Angiography and dissection studies were used in this study to elucidate the role of the deep fascia in perfusion of the radial forearm flap. METHODS: Twenty-four radial forearm flaps were harvested from 12 fresh cadavers. Ten paired suprafascial and subfascial flaps were harvested, the radial arteries were cannulated, and methylene blue dye was injected into the radial artery followed by a barium sulfate/gelatin mixture. The flaps were digitally radiographed, and the vascular territory was measured using software. The cutaneous dye staining patterns for paired flaps were recorded photographically. Computed tomography scans were performed for 3 paired flaps to evaluate the vascular pattern within the flap. Two pairs of forearms were subjected to intravascular injection with colored latex through the brachial artery prior to flap harvest, and microdissection of the flap and fascia was performed. RESULTS: No significant difference was found in the vascular territory measured for the flap when harvested using the subfascial or the suprafascial technique. Flap dissection studies confirmed that this is because of the poorly developed subfascial plexus in the forearm, with preservation of the deep fascia not contributing to the mechanism of flap perfusion. CONCLUSIONS: Inclusion of the deep fascia during flap harvest does not contribute to the perfusion of the radial forearm flap and therefore the deep fascia does not need to be included to maintain flap vascularity.     

Longitudinally-split radial forearm flap.

We have applied the split flap concept to a distally-pedicled radial forearm flap to cover separate dorsal defects of the fingers in two cases. The rationale is that there are the vascular plexuses inside and around the sensory nerve that permit surgical splitting of the flap. In the split design, the first segment is supplied by the radial artery itself. The second segment is supplied by the neurocutaneous artery of the medial cutaneous nerve.     

Oblique radial forearm reverse-flow flap

A modifed design for the distally-based radial forearm flap is presented, in an oblique direction rather than longitudinally, based on the existence of skin laxity in the proximal forearm region. The skin paddle of the flap is designed in an oblique fashion pedicled on one of the proximal-row septocutaneous perforators, and elevated in the usual manner supplied by the distal radial artery. The oblique radial forearm flap thus created was successfully utilized for reconstruction of seven dorsal hand defects. Results showed that all the flaps could easily be transposed to the defect through a wide arc of rotation and all survived totally, with direct closure of the donor site in five cases, and significant reduction in size in the remaining two cases. It was concluded that the oblique design for the skin island of the reverse radial forearm flap could allow creation of a flap that has a smaller donor defect and yet presents a longer pedicle length, with a wider arc of rotation and better adaptation to a dorsal hand defect, than a conventional longitudinal-design radial forearm flap.     

Hemodynamic changes of the hand after radial forearm flap harvesting

After radial forearm flap harvesting, there is some risk for hand circulatory disorders. To reveal the changes in circulatory dynamics in the hand after harvesting this flap, the authors compared blood pressure and flow by color Doppler ultrasonography in the donor and nondonor hands, and evaluated the long-term changes in these factors in 40 patients undergoing this operation. Blood pressure and flow of the index finger in the donor hands were lower than those in the nondonor hands during the first 2 months postoperatively, but they virtually returned to the level of those in the nondonor hands within 1 year of the operation. These results suggest that after harvesting the radial artery, collateral circulation in the hand developed during a short postoperative period. Therefore, the authors can predict the long-term safety of forearm flap harvesting by evaluating the hemodynamic changes of the digits caused by acute occlusion of the radial artery preoperatively, which would reflect the hemodynamics at an early postoperative stage.     

Haemodynamics of the radial forearm flap

An electromagnetic blood flow meter was used to study blood flow to the radial forearm flap intra-operatively in 20 patients. Blood flow correlated more significantly with surface area than with weight. Both antegrade and retrograde flow were measured and showed no significant difference. Temperature affected blood flow significantly (P less than 0.01) as did sympathetic block (P less than 0.01). The venous drainage of the flap was studied in five cases. Both superficial and deep systems were equally capable of draining the flap.     

Analysis of flow changes in forearm arteries after raising the radial forearm flap: a prospective study using colour duplex imaging.

The purpose of this study is to assess the changes in flow patterns of forearm arteries produced by excision of the radial artery when harvesting the radial forearm flap, in order to clarify its vascular morbidity rationally. Eleven patients with elective surgery using the radial flap were included in this investigation. A prospective study was designed using colour duplex imaging for quantitative flow measurement in two stages: a few days before the operation, a first colour duplex scanning examination was done recording flow velocity and vessel section area from the radial, ulnar, posterior interosseous and anterior interosseous arteries around the wrist. Volumetric parameters and relative blood flow percentages were calculated and compared to those obtained from a second similar vascular investigation accomplished in the same limb 4-5 months after the operation. Statistical analysis was done using the Wilcoxon matched pairs test. After raising the radial forearm flap there was a trend for increased overall forearm flow (from 162 to 215 ml/min, P = 0.09 N.S.), the ulnar (P = 0.04), the posterior interosseous (P = 0.004) and the anterior interosseous (P = 0.003) arteries being responsible for this tendency. The anterior interosseous artery showed the greatest increase in blood (from 8.2 to 67.7 ml/min), reaching a relative flow percentage (33%) close to that of the radial artery before its excision (39%). Results of this study indicate that another 'major vascular axis' based on the anterior interosseous artery develops after sacrificing the radial artery and that global arterial inflow to the hand is not impaired.     

Thermography of hands after a radial forearm flap has been harvested

To determine the change of blood flow in the hand after radial forearm flap harvest, several studies using thermography or color Doppler ultrasonography have been reported (Iida et al., Ann Plast Surg 49:156, 2002; Suominen and Asko-Seljavaara, Scand J Plast Reconstr Hand Surg 30:307, 1996). One study using Doppler ultrasonography (Iida et al., Ann Plast Surg 49:156, 2002) found reduced blood flow, while another study using thermography (Suominen and Asko-Seljavaara, Scand J Plast Reconstr Hand Surg 30:307, 1996) reported warm digits. However, the thermographic study did not examine the postoperative period. We evaluated temperature changes by thermography during three different postoperative periods: 3, 6, and 12 months. Differences in temperature were measured between the donor hand and the other hand in the resting state and after cold stress at the thenar eminence. The differences in temperature were divided into three grades. The donor hand was classified as being warmer, similar, or cooler than the other hand. There was a tendency for cold stress to accentuate differences in temperature. After cold stress, the percentage for warmer was 75.0% at 3 months, while similar increased to 87.5% at 6 and 12 months. The temperature of the donor hand increased for a limited period after surgery for up to 3 months, and the temperature of the donor hand became similar to that of the nondonor hand. Therefore, circulatory changes in the hand undergoing flap harvest are thought to be minimal. Considering other reports, we think the high temperature at the thenar eminence of the donor hand shortly after surgery is partially explained by sympathetic nerve damage.     

Adipofascial radial forearm flap after failed surgical treatment of lateral epicondylitis

Secondary cases of lateral epicondylitis after failed surgical treatment are a particular therapeutic challenge. Excision of the scar tissue and muscle transposition have been advocated as alternative procedures, although the optimal treatment has yet to be established. We present one desperate case of failed surgical treatment of lateral epicondylitis, where an adipofascial radial forearm flap was used successfully to alleviate the patient's symptoms.     

The shamrock flap: a three-paddle radial forearm flap

The radial forearm flap has been well described for reconstruction of the oral cavity. The flap is most commonly used as a single-paddle flap with or without a segment of vascularised radius. Double-paddle radial flaps may be required to reconstruct defects of intraoral lining and overlying skin following excision of extensive tumours. We wish to report the first described case of reconstruction using a triple-paddle radial forearm flap including a segment of vascularised radius.     

Neural anatomy of the radial forearm flap

Typically the lateral antebrachial cutaneous nerve alone is used to innervate the radial forearm free flap when a sensate flap is required. The authors desired, by means of fresh cadaveric microdissections and by means of local anesthetic injections in living subjects, to map the sensory nerve territories of this flap. Eight radial forearm flaps were elevated and the medial antebrachial cutaneous nerve (MABC), lateral antebrachial cutaneous nerve (LABC), and superficial radial sensory nerve (SRSN) were dissected with the aid of an operating microscope (2.5-10x) and traced to their dermal insertions. In the injection study, the MABC, LABC, and SRSN in eight forearms of 4 subjects were blocked sequentially with 2% lidocaine injections. The resulting sensory deficit from each injection was mapped on the skin and superimposed on the marked radial forearm flap territory. Distribution of the three dissected nerve regions and the sensory deficit after injection were determined by digital images and computer analysis. During flap dissections, mean nerve distributions of total flap area were as follows: LABC, 61.8% (range, 48.3-71.6%); MABC, 33.8% (range, 30.5-38.9%); and SRSN, 34.6% (range, 26.8-44.1%). After nerve block the mapped sensory areas were as follows: LABC, 62.3% (range, 44.5-88.5%); MABC, 19.6% (range, 8.0-35.8%); and SRSN, 19.5% (range, 9.9-26.3%). At least 40% of the total flap area was not innervated by the LABC as identified both by nerve dissection and sensory local anesthetic blockade. By including the LABC, MABC, and SRSN in the radial forearm flap, both the theoretical and the clinically determined useful sensory innervation of the radial forearm flap potentially would be increased.     

Complications of radial forearm flap donor sites

The complications of radial forearm flap donor sites in 15 patients from two centres have been reviewed. The complications included skin graft failure, swelling of the hand, stiffness of joints, reduced strength and sensation, cold-induced symptoms and fractures of the radius. Methods to reduce the incidence of such complications are discussed.