Sensory reinnervation of muscle free flaps for foot reconstruction

Microvascular Muscle vs. Fascio-Cutaneous Free Flaps for Reconstruction of Plantar Load-Bearing Foot Defects-An International Survey

Background: The reconstruction of plantar load-bearing foot defects faces many plastic surgeons with a major challenge. The optimal patient- and defect-oriented reconstructive strategy must be selected. Methods: To analyze the current trends and recommendations in reconstruction of plantar load-bearing foot defects, we conducted an international survey among plastic surgeons querying them about their recommendations and experiences. Results: The survey revealed that the most common strategies for reconstruction of the foot sole are locoregional and microvascular free flaps, emphasizing the relevance of plastic surgery. Among microvascular free flaps, muscle and fascio-cutaneous free flaps are by far the most frequently used. The target qualities of the reconstructed tissue to be considered are manifold, with adherence being the most frequently mentioned. We observed a noteworthy correlation between the utilization of muscle flaps and a preference for adherence. In addition, we identified a substantial correlation between the usage of fascio-cutaneous free flaps and further target qualities, such as good skin quality and sensitivity. Conclusions: Our findings provide insights into the clinical reality and highlight important aspects that must be considered in reconstruction of the weight-bearing areas of the foot providing support in the selection of the appropriate therapy.

RB. Outcome Analysis Comparing Muscle and Fasciocutaneous Free Flaps for Heel Reconstruction: Meta-Analysis and Case Series

Background Choosing the components of free flap (fasciocutaneous or muscle) is one of the crucial but controversial decisions in heel reconstruction. This meta-analysis aims to provide an up-to-date comparison of fasciocutaneous flaps (FCFs) and muscle flaps (MFs) for heel reconstruction and to ascertain if one flap has an advantage over the other.

Methods Following the Preferred Reporting Item for Systematic Reviews and Meta-Analyses guidelines, a systematic literature review was performed identifying studies on heel reconstruction with FCF and MF. Primary outcomes were survival, time of ambulation, sensation, ulceration, gait, need for specialized footwear, revision procedures, and shear. Meta-analyses and Trial Sequential Analysis (TSA) were performed to estimate the pooled risk ratios (RRs) and standardized mean difference (SMD) with fixed effects and random effects models, respectively.

Results Of 757 publications identified, 20 were reviewed including 255 patients with 263 free flaps. The meta-analysis showed no statistically significant difference between MF and FCF in terms of survival (RR, 1; 95% confidence interval [CI], 0.83, 1.21), gait abnormality (RR, 0.55; 95% CI, 0.19, 1.59), ulcerations (RR, 0.65; 95% CI, 0.27, 1.54), footwear modification (RR, 0.52; 95% CI, 0.26, 1.09), and revision procedures (RR, 1.67; 95% CI, 0.84, 3.32). FCF had superior perception of deep pressure (RR, 1.99; 95% CI, 1.32, 3.00), light touch, and pain (RR, 5.17; 95% CI, 2.02, 13.22) compared with MF. Time to full weight-bearing (SMD, –3.03; 95% CI, –4.25, –1.80) was longer for MF compared with FCF. TSA showed inconclusive results for comparison of the survival of flaps, gait assessment, and rates of ulceration.

Conclusion Patients reconstructed with FCF had superior sensory recovery and early weight bearing on their reconstructed heels, hence faster return to daily activities compared with MFs. In terms of other outcomes such as footwear modification and revision procedure, both flaps had no statistically significant difference. The results were inconclusive regarding the survival of flaps, gait assessment, and rates of ulceration. Future studies are required to investigate the role of shear on the stability of the reconstructed heels.

Sensory nerve regeneration and reinnervation in muscle following peripheral nerve injury

Sensory afferent fibers are an important component of motor nerves and compose the majority of axons in many nerves traditionally thought of as "pure" motor nerves. These sensory afferent fibers innervate special sensory end organs in muscle, including muscle spindles that respond to changes in muscle length and Golgi tendons that detect muscle tension. Both play a major role in proprioception, sensorimotor extremity control feedback, and force regulation. After peripheral nerve injury, there is histological and electrophysiological evidence that sensory afferents can reinnervate muscle, including muscle that was not the nerve's original target. Reinnervation can occur after different nerve injury and muscle models, including muscle graft, crush, and transection injuries, and occurs in a nonspecific manner, allowing for cross-innervation to occur. Evidence of cross-innervation includes the following: muscle spindle and Golgi tendon afferent-receptor mismatch, vagal sensory fiber reinnervation of muscle, and cutaneous afferent reinnervation of muscle spindle or Golgi tendons. There are several notable clinical applications of sensory reinnervation and cross-reinnervation of muscle, including restoration of optimal motor control after peripheral nerve repair, flap sensation, sensory protection of denervated muscle, neuroma treatment and prevention, and facilitation of prosthetic sensorimotor control. This review focuses on sensory nerve regeneration and reinnervation in muscle, and the clinical applications of this phenomena. Understanding the physiology and limitations of sensory nerve regeneration and reinnervation in muscle may ultimately facilitate improvement of its clinical applications.

Plantar reconstruction using the medial sural artery perforator free flap

Free flaps are usually required rather than local flaps for large plantar defects, due to a lack of locally available tissue. The medial sural artery perforator free flap, recently introduced clinically by several authors, is a noticeable option for soft tissue coverage, but it has still not been widely used for the reconstruction of various large plantar defects. Between 2005 and 2007, medial sural artery perforator free flaps were used to reconstruct soft tissue defects in plantar areas in 11 patients at our institute. Patient ages ranged from 10 to 68 years (mean, 43 years), and follow-up periods ranged from 7 to 22 months (mean, 13 months). Flap sizes ranged from 10 to 14 cm in length and from 5 to 7 cm in width. Flaps survived in all patients. Marginal loss over the distal flap region was noted in 1 patient, and this was treated successfully with a subsequent split-thickness skin graft. In another one case, venous insufficiency developed, but salvage was successful with leech application. Long-term follow-up showed good flap durability with a protective sensation. The medial sural artery perforator flap provides sufficient durability for weight-bearing areas, even though it is a thin cutaneous flap. The authors recommend that this flap be considered as a reliable alternative for the reconstruction of large plantar defects.

Microsurgical free flap transfer to amputation sites: indications and results

A series of microsurgical free flap reconstructions to amputation stumps of the upper as well as the lower extremities was reviewed in 7 male and 2 female patients. Indications included preservation of length after trauma in 6 patients and cure of local infection in 2 patients. In 1 patient an extensive defect after resection of a recurrent shoulder sarcoma required use of a complete arm fillet free flap for tumor reconstruction. Microvascular free flaps used included four scapular flaps, two fillet flaps from the amputated extremity, one anterolateral thigh flap, and one lateral arm flap. Seven of 9 patients were fitted with a prosthesis and underwent occupational therapy resulting in ambulatory and improved functional status. Microvascular reconstruction is indicated in emergency settings as well as for elective reconstruction of amputation sites. Using uninjured "spare parts" of the amputated extremity should be considered. Elective reconstruction is performed preferably with free flaps based on the subscapular vascular system.

Limb salvage for soft-tissue malignancies of the foot: an evaluation of free-tissue transfer

Free flaps may safely allow meaningful ambulation, durable limb preservation, and better quality of life in patients undergoing resections of soft-tissue cancers of the foot. To prove this, the records of a series of patients at The University of Texas M. D. Anderson Cancer Center (n = 67) who underwent limb salvage following tumor-related resection (n = 71 procedures) from 1989 to 1999 were retrospectively reviewed. Eighteen patients who were not candidates for local flaps or skin grafts received a total of 20 free flaps to preserve their limbs. Most defects (mean size, 78 cm2; range, 20 to 150 cm2) were on a weight-bearing surface of the foot (nine on a weight-bearing heel, three on a plantar foot); the remainder were on a non-weight-bearing surface (six on dorsum, two on a non-weight-bearing heel). Melanoma was diagnosed in nine cases (50 percent); soft-tissue sarcoma, in seven (39 percent); and squamous cell carcinoma, in two (11 percent). Fasciocutaneous and skin-grafted muscle flaps were used on both weight-bearing and non-weight-bearing surfaces. Free-tissue transfer was successful in 17 of 20 cases (85 percent); the three flap losses occurred in two patients. Minor complications (i.e., small hematoma, partial skin graft loss, and delayed wound healing) occurred in five patients. In all cases of successful free-tissue transfer, patients began partial weight bearing at a mean of 7.4 weeks (range, 2 to 12 weeks), and all ultimately achieved full weight bearing. Sixty-seven percent still required special footwear. In one patient, an ulceration on the weight-bearing portion of the flap resolved after a footwear adjustment. Only one patient was lost to follow-up (mean, 23 months). In the 17 remaining patients, limb salvage succeeded in 15 (88 percent). Of these, nine (60 percent) were alive without evidence of disease, three (20 percent) were alive with disease, and three (20 percent) had died of disease. Local recurrence developed in two patients but was successfully treated by excision and closure. No late amputations were required for local control. Thus, it seems that free flaps help facilitate limb salvage and that they may preserve meaningful limb function in patients who undergo resection of soft-tissue malignancies of the foot.

Innervation of skin grafts over free muscle flaps

Skin grafts regain their sensory innervation from the graft bed by the regeneration of nerve endings. Although some clinical studies report sensory recovery in skin grafts implanted on free muscle flaps, the mechanism of recovery is obscure. The purpose of this study was to investigate nerve regeneration in experimental skin grafts on free muscle flaps to elucidate this phenomenon. Thirty-eight male Sprague-Dawley rats, weighing 450-550 g were used in the study. The rat gracilis muscle flap was the free flap model transferred from one groin to the other using microvascular anastomoses. Full-thickness skin grafts harvested from the abdomen were used to cover the free muscle flaps after transfer. Four study groups were formed: Group I (n = 10): Free muscle flaps were transferred without any nerve anastomosis; Group II (n = 10): Free flaps transferred with the anastomosis of the muscle's motor nerve to a sensory nerve at the recipient site; Group III (n = 10): Free flaps transferred with the anastomosis of the muscle's motor nerve to a motor nerve at the recipient site; Group IV (n = 8): Skin grafts were placed directly on the fascia layer over the medial hindlimb muscles and served as controls. The specimens were harvested for histologic examination after 12 weeks. Histologic examination was performed to visualise regenerating nerve endings using H&E, S100, Luxol Fast Blue and tyrosine hydroxylase staining. The specimens were categorically scored according to the staining pattern of neural structures around pilosebaceous units and statistical comparisons were performed by using paired t-test. Skin grafts in both Group II and Group III markedly received tyrosine hydroxylase at the base of their pilosebaceous units in many of the specimens and functional nerve twigs could also be traced from the muscle layer to the overlying skin graft. In contrast, the skin grafts in Group I did not show any nerve function in the central parts. The overall staining scores of Groups II, III and IV were significantly higher than Group I (P < 0.05; P < 0.001; P < 0.05, respectively). There was no statistically significant difference between other groups. No myelinated nerve fibres could be detected in any of the skin grafts with Luxol Fast Blue technique. It was concluded in the present study that skin grafts over reinnervated free muscle flaps can develop significantly better innervation than skin grafts over non-innervated muscle flaps. However, the activity in skin appendages indicating nerve regeneration may only imply a gross sensation and in the absence of any myelinated nerve fibres transmission of finer sensation cannot be expected in any of the study groups.