On-Bone Fixation of Free Gingival Graft Induces an Osteoinductive Effect in Human Alveolar Bone.

We examined alveolar bone samples in the area of on-bone fixation of a free gingival graft performed during surgery in patients aged 37-55 years with a diagnosis of secondary partial adentia of the upper and lower jaws. Six months after fixation of the graft in the alveolar bone, foci of neoosteogenesis were found in the contact zone. They were characterized by the appearance of appositional lines, cords of basophilic osteoblasts, and growing osteons. An immunohistochemical study revealed an increase in the number of CD44+, CD29+, and osteocalcin+ cells in the layer of the outer circumferential lamellae, primary osteons, and the lining of the Haversian canals. TGF-ß1+ cells were located in the intertrabecular reticular tissue and wall of microvessels. The results indicate activation of mesenchymal stem cells in the area of localization of the graft and differentiating osteoblasts. The observed osteoinductive effect of free gingival graft is associated with its participation in reorganization in MSC and induction of morphogenetic molecules.

Near-infrared spectroscopy for monitoring free jejunal flap.

BACKGROUND: Although the free jejunal graft is commonly used for reconstruction after resection of a tumor of the pharynx or cervical esophagus, adequate monitoring for detecting graft failure is not available. We employed near-infrared spectroscopy to measure regional oxygen saturation (rSO2) in the graft. METHODS: In 25 consecutive cases who underwent reconstructive surgery using a free jejunal graft, the feasibility of postoperative rSO2 monitoring was examined along with the changes in rSO2 values following vascular clamping or reperfusion. RESULTS: No operative mortality occurred, and except for one case of subcutaneous hematoma that necessitated evacuation surgery, no complications related to surgery or graft failure occurred. Postoperative rSO2 monitoring was feasible for >50 hours in most cases. It mostly remained >55% with a stable hemoglobin index (HbI) which reflects tissue hemoglobin density. A marked increase in the HbI was noted in a patient with hematoma. Intraoperatively, the rSO2 of intact jejunal tissue was >60% in every case but dropped within a few minutes after arterial clamping because of decreased oxygenated hemoglobin concentration. With venous clamping, the HbI was elevated while the rSO2 remained unchanged or was slightly decreased. Upon graft reperfusion, the rSO2 rapidly recovered in all 18 cases because of the recovery of oxygenated hemoglobin concentrations. CONCLUSIONS: The near-infrared spectroscopic assessment sensitively and accurately reflected the condition of the jejunal graft. It appears to be a promising postoperative method for monitoring graft perfusion. An rSO2 value of 55% appears to be an adequate criterion for ischemia.

Morphological analysis of ischemia-reperfusion injury in a cold ischemia model of jejunal free flap for hypopharyngeal reconstruction.

BACKGROUND: Jejunal free flap (JFF) reconstruction is a popular treatment option for advanced hypopharyngeal cancer. Several factors including ischemia-reperfusion injury (IRI) can cause mucosal damage and progressive flap necrosis. We investigated the development and time-related progression of morphological and cellular changes in patients with JFF reconstruction including cold preservation of the graft. METHODS: Eleven patients were enrolled. Biopsies were taken during surgery from normally perfused tissue, before loop isolation (T0), at the end of back-table surgery (T1), immediately before reperfusion (T2), 15' after reperfusion (T3), and at the end of the digestive anastomoses (T4) and from the external monitor daily from the 1st to the 5th postoperative day (M1-M5). Histomorphological and immunohistochemical parameters in the intraoperative and postoperative samples were evaluated and compared. RESULTS: Delayed flap necrosis was observed in 2 patients. The cold ischemia phase did not negatively affect mucosal regeneration after reperfusion; morphological and cellular damage parameters returned to normal by the end of surgery or along the early postoperative period. Significant enterocyte replication activity was observed at the end of revascularization, which continued in the postoperative phase, leading to recovery of the epithelial morphological integrity and disappearance of apoptotic cells. An inflammatory infiltrate persisted in the M samples, and in a significant proportion of samples, mucosal fibrosis developed by the end of the postoperative observation. CONCLUSION: Cold perfusion and preservation of the JFF can effectively limit the negative effects of IRI and to prevent short- and medium-term complications that can compromise the final outcome.

Intraosseous microdialysis for bone free flap monitoring in head and neck reconstructive surgery: A prospective pilot study.

BACKGROUND: Although some researchers have positioned microdialysis catheters in the soft tissue surrounding bone, the results did not accurately reflect bone metabolism. The present study's objective was to establish the feasibility of microdialysis with a catheter positioned directly in bone. METHODS: Thirty-four patients (19 males, 15 females; median age: 59) were included in a prospective, nonrandomized clinical trial in the Department of Maxillofacial Surgery at Amiens-Picardie University Hospital (Amiens, France). Fibula or iliac crest free flaps were used in reconstructive head and neck surgery (for cancer, osteoradionecrosis, trauma, or ameloblastoma) and monitored with microdialysis catheters positioned in a hole drilled into the bone. Glucose, lactate, pyruvate, and glycerol concentrations were analyzed for 5 days. RESULTS: All catheters were positioned successfully, and thrombosis did not occur during the monitoring. In two patients, an increase in the lactate concentration and a glucose level close to 0 were associated with signs of flap necrosis, with removal on Days 9 and 50. In viable flaps, the mean glucose level was 2.02 mmol/L, the mean lactate level was 8.36 mmol/L, and the mean lactate/pyruvate ratio was 53. Forty percent of the glucose values were below 1 mmol/L, and 50% of the lactate/pyruvate ratio values were above 50-suggesting a specific metabolic pattern because these values would be considered as alert values in soft tissue. CONCLUSION: Monitoring bone free flaps with intraosseous microdialysis is feasible. This technique specifically assesses bone viability, and further studies are now necessary to define the alert values in bone.

Retrospective evaluation of diagnostic accuracy of free flap monitoring with the Cook-Swartz-Doppler probe in head and neck reconstruction.

The Cook-Swartz-Doppler probe is an easy to handle and reliable tool for free flap monitoring. In the head and neck region different confounders can affect the read out. We therefore analyzed the use of the Doppler probe regarding these potential difficulties and to compare the diagnostic accuracy in arterial or venous monitoring of free flaps in the head and neck region. A retrospective study was performed in which all patients were included who underwent free flap surgery in the head and neck region in the Department of Plastic Surgery and the Department of Maxillofacial Surgery of our institution between 2010 and 2018 and were monitored with an implanted Doppler probe. 147 free tissue transfers were included. No significance was found for arterial and venous placement of the Doppler probe for sensitivity (artery 83.3%; vein 84.6%; p = 0.87), specificity (artery 89.2%; vein 96.1%; p = 0.17) and negative predictive value (artery 96.7%; vein 94.2%; p = 0.55). A better positive predictive value for placing the Doppler probe around the artery (82.7%) than the vein (61.1%) was found in our study (p = 0.056). The better positive predictive value in arterial monitoring suggests that this is the more reliable measuring method to assess flap perfusion in the head and neck region.

Free Flap Transfer for Pediatric Head and Neck Reconstruction: What Factors Influence Flap Survival?

OBJECTIVES: The objective of this study was to identify the factors that influence free flap survival after head and neck reconstructive surgery in pediatric patients. METHODS: One hundred thirty consecutive cases of head and neck reconstruction with free flaps in pediatric patients at the Department of Oral and Maxillofacial Surgery at Peking University School and Hospital of Stomatology, Beijing, People's Republic of China, between 1999 and 2017 were reviewed. A single head and neck surgical team performed all the included surgeries. Demographic and surgical patient data with possible associations with free flap survival were recorded. Relevant influencing factors were determined using the χ2 test and logistic regression analysis. RESULTS: There were 135 free flap transfers performed in the patients, with an overall success rate of 95.6%. Free flap failure occurred in six flaps (4.4%). Arterial crisis was the main cause of flap failure. The overall complication rate was 7.0%. Patient age (5-9 years old; odds ratio, 13.397; 95% confidence interval, 1.167-153.838; P = 0.037) was a statistically significant risk factor influencing free flap survival. Donor site, defect region, recipient vessel, and surgery time were not associated with free flap outcome. CONCLUSION: Free flap transfer for head and neck reconstruction in pediatric patients is safe and reliable. However, special attention should be paid to pediatric patients under 9 years of age when performing head and neck reconstruction. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:1915-1921, 2019.

Effect of Segment Length and Number of Osteotomy Sites on Cancellous Bone Perfusion in Free Fibula Flaps.

BACKGROUND: Indocyanine green (ICG) videoangiography is routinely used to evaluate skin and organ perfusion and to assess patency rates of microvascular anastomoses. This study uses ICG angiography as a novel approach to qualitatively and quantitatively evaluate bone perfusion of microvascular fibula grafts intraoperatively and to assess the effect of fibula segment length and number of osteotomies on bone perfusion. METHODS: All patients planned for mandible reconstruction using a microvascular fibula graft between January 2013 and May 2017 were considered for this study. ICG videoangiography of cancellous bone perfusion was performed using a handheld ICG camera. Videos were analyzed, and a perfusion curve was generated. Peak enhancement, time to peak, slope, and wash-in area under the curve were extracted; rise time, wash-in rate (WiR), and wash-in perfusion index were calculated. Results were statistically analyzed with regard to distal fibula segment length and number of osteotomy sites. RESULTS: Thirty-nine patients (age 59 ± 8 years) were included in the study. Mandible reconstruction was achieved with 1 (n = 15), 2 (n = 13), or 3 (n = 11) fibula segments. The WiR was 6.4 ± 2.3 and 4.4 ± 0.2 before and after proximal osteotomy, respectively. The wash-in perfusion index was 114.2 ± 48.4 before and 84.4 ± 20.0 after proximal osteotomy. Bone perfusion was significantly reduced after additional proximal osteotomies. Both the segment length and number of proximal osteotomies correlated with bone perfusion, with longer segments and fewer osteotomies showing higher perfusion. CONCLUSION: This study demonstrates the feasibility of cancellous bone perfusion analysis using ICG and can serve as a basis for future bone perfusion studies. Additional osteotomies and short segment length negatively affects cancellous bone perfusion of the distal fibula segment in free fibula flaps. The extent to which the observed decrease in arterial inflow to the distal fibula segment affects the further course of healing needs to be addressed in future studies.

Free Flap Head and Neck Reconstruction with an Emphasis on Postoperative Care.

Microsurgical free tissue transfer represents the mainstay of care in both ablative locoregional management and the simultaneous reconstruction of a defect. Advances in microsurgical techniques have helped balance the restoration of both form and function-decreasing the significant morbidity once associated with large ablative, traumatic, or congenital defects-while providing immediate reconstruction enabling early aesthetic and functional rehabilitation. There are a multitude of perioperative measures and considerations that aim to maximize the success of free tissue transfer. These include nutritional support, tight glycemic control, acknowledgment of psychological and psychiatric factors, intraoperative surgical technique, and close postoperative monitoring of the patients' hemodynamic physiology. While the success rates of free tissue transfer in experienced hands are comparable to alternative options, the consequences of flap failure are catastrophic-with the potential for significant patient morbidity, prolonged hospital stay (and associated increased financial implications), and increasingly limited options for further reconstruction. Success is entirely dependent on a continuous arterial inflow and venous outflow until neovascularization occurs. Flap failure is multifactorial and represents a dynamic process from the potentially reversible failing flap to the necrotic irreversibly failed flap-necessitating debridement, prolonged wound care, and ultimately decisions concerned with future reconstruction. The overriding goal of free flap monitoring is therefore the detection of microvascular complications prior to permanent injury occurring-identifying and intervening within that critical period between the failing flap and the failed flap-maximizing the potential for salvage. With continued technique refinement, microvascular free flap reconstruction offers patients the chance for both reliable functional and aesthetic restoration in the face of significant ablative defects. The caveat to this optimism is the requirement for considered perioperative care and the optimization of those factors that may offer the difference between success and failure.

A Self-Calibrated Tissue Viability Sensor for Free Flap Monitoring.

In fasciocutaneous free flap surgery, close postoperative monitoring is crucial for detecting flap failure, as around 10% of cases require additional surgery due to compromised anastomosis. Different biochemical and biophysical techniques have been developed for continuous flap monitoring, however, they all have shortcoming in terms of reliability, elevated cost, potential risks to the patient, and inability to adapt to the patient's phenotype. A wearable wireless device based on near infrared spectroscopy has been developed for continuous blood flow and perfusion monitoring by quantifying tissue oxygen saturation (). This miniaturized and low-cost device is designed for postoperative monitoring of flap viability. With self-calibration, the device can adapt itself to the characteristics of the patients' skin such as tone and thickness. An extensive study was conducted with 32 volunteers. The experimental results show that the device can obtain reliable measurements across different phenotypes (age, sex, skin tone, and thickness). To assess its ability to detect flap failure, the sensor was tested in a pilot animal study. Free groin flaps were performed on 16 Sprague Dawley rats. Results demonstrate the accuracy of the sensor in assessing flap viability and identifying the origin of failure (venous or arterial thrombosis).

Systematic review: Early versus late dangling after free flap reconstruction of the lower limb.

INTRODUCTION AND AIMS: Dangling regimes after free flap surgery to the lower limb vary between centres and clinicians. There is currently no accepted gold standard. This review examines the evidence for early versus late post-operative dangling after free flap reconstruction of the lower limb. The secondary aim is to evaluate the regimes used. MATERIAL AND METHODS: Medline, Embase and the Cochrane library were searched for all studies on dangling or rehabilitation after free flap reconstruction in the lower limb (December 2015). All studies outlining a clear dangling regime were included. Data were extracted by two authors independently and analysed using the software package Review Manager (RevMan 5). All authors were contacted for further information. RESULTS: 197 patients were included from 8 studies: 1 randomized, 6 cohort and 1 case-series. Although some studies did not state the aetiology, of those that did; 42% were trauma, 31% oncology, 20% complex wounds and 7% infection. The majority of flaps were latissimus dorsi, 18% parascapular, 15% anterolateral thigh and the remainder was mixed. Forty-eight percent of patients dangled on post-operative day (POD) 7, 29% on day 6, 4% on day 5 and 18% on day 3, with varying regimes. A meta-analysis of comparable studies showed circulatory benefit after 4 days of dangling using tissue oxygen saturation as a measure. Four flap failures (2.0%) were reported. CONCLUSIONS: There is physiological benefit in post-operative dangling. A 3-day flap training regime is sufficient for physiological training. However, the optimal flap training regime remains unclear. It may be appropriate to start dangling as early as POD 3. More research is needed to determine the optimal time to start dangling and the regime.

Studying the blood pressures of antegrade and retrograde internal mammary vessels: Do they really work as recipient vessels?

BACKGROUND: The proximal ends of internal mammary (IM) vessels are now the most common recipient vessels for breast reconstruction. On the other hand, bilateral deep inferior epigastric artery perforator (DIEP) flaps are often needed according to the territory and the volume required for reconstruction. The usefulness of retrograde IM vessels as second recipients has recently been reported, but there are very few quantitative studies on the hydrodynamics of the retrograde IM vessels. Because the flow is dependent on the pressure differential, the blood pressures of the antegrade IM artery (AIMA), antegrade IM vein (AIMV), retrograde IM artery (RIMA), retrograde IM vein (RIMV), and recirculated intraflap vein (FV) were investigated to solve this question and to confirm the reliability and usefulness of the retrograde IM vessels. METHODS: Ten free flap breast reconstructions were included in this study. The IM vessels were exposed, and the pressures were measured. After recirculation, the FV pressures were measured when the flap was not ischemic or congestive. Systemic blood pressure was also recorded during the whole measurement period. RESULTS: The AIMA and RIMA pressures were 70.4 ± 8.2 mmHg and 54.0 ± 8.6 mmHg (p = 0.000003), respectively, while the systemic pressure was 65.1 ± 10.0 mmHg. The AIMV pressure was always smaller than the RIMV pressure; the mean AIMV pressure was 5.3 ± 1.6 mmHg. In addition, the FV pressure was greater (p = 0.03) than the RIMV pressure (17.7 ± 9.9 mmHg), while the RIMV pressure was 8.7 ± 2.0 mmHg. CONCLUSIONS: Both the RIMA and RIMV are useful and reliable as second recipients for bipedicled free flap transfers. This is a great benefit because it would provide two recipients in one surgical site and would be especially useful in thin patients or patients with previous abdominal scars requiring double pedicled DIEP flaps. LEVEL OF EVIDENCE: Therapeutic Study, Level IV.

Breast oedema following free flap breast reconstruction.

OBJECTIVES: Breast oedema causes significant morbidity and is historically difficult to quantify. The aim of this study was to identify changes in breast tissue water content from pre-operative levels in the native breast to post-operative levels in mastectomy skin flaps and free flaps in the reconstructed breast. MATERIALS AND METHODS: One hundred patients undergoing unilateral mastectomy and immediate free flap breast reconstruction were examined pre-operatively and at three post-operative appointments. A validated moisture meter was used to record dermal water percentages of each breast quadrant and areola in both breasts pre-operatively, then four quadrants of both breasts plus the unaffected areola and free flap at each post-operative review. RESULTS AND CONCLUSION: Native skin of the reconstructed breast showed significant, persistent increase in MWC from 45.6% ± 0.5% to 72.8% ± 0.9% at 1st follow up (p < 0.001), decreasing only to 67.6% ± 0.8% by 3rd follow up. There was a marked difference (p < 0.001) in the mean water content (MWC) of the initial free flap (39.7% ± 0.6%) compared to 61.8% ± 1.7% at 1st follow up, then 55.1% ± 1.4% at 2nd and 53.7% ± 1.3% at 3rd follow ups. The unaffected breast showed a small but significant increase in MWC of all quadrants at subsequent follow up (greatest difference 3.1% at 1st follow up). This patient group demonstrates significant, persistent oedema of the reconstructed breast, which can be monitored using a non-invasive moisture meter.

The Concepts of Propeller, Perforator, Keystone, and Other Local Flaps and Their Role in the Evolution of Reconstruction.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the history and physiology of perforator flaps. 2. Understand the concept of "free-style" perforator flaps and principles in design and harvest. 3. Understand the uses of perforator flaps in reconstruction and applications in new settings. 4. Understand new principles in single and multiple perforator flap harvest and adjunct techniques that can be used in perforator flaps. 5. Highlight pertinent anatomy and techniques for selected perforator flaps described. SUMMARY: Extended knowledge of vascular anatomy has propagated the development of perforator flaps, which preserve muscle function and reduce morbidity. This has been achieved through the exemplary works of Manchot, Salmon, Milton, Taylor, and many others. With over 350 clinically relevant perforators in the body, this has created new flap options and a sense of creative freedom for reconstruction tailored toward a specific defect, without constraints of specific landmarks and using a "free-style" approach. Dominant perforators may be found in zones of high perforator density or "hot spots," which can help to conceptualize local flap options and aid flap design. This article aims to outline the history, physiology, and principles of flap design and harvest, and highlight traditional and evolving concepts and modifications of contemporary and traditional flaps that are changing reconstructive practice. This is a broad overview focusing on clinical applications, highlighting key concepts in a selection of new or evolving flaps being used in clinical practice and providing source references to acquire detailed flap descriptions.

Critical time for neovascularization/angiogenesis to allow free flap survival after delayed postoperative anastomotic compromise without surgical intervention: A review of the literature.

BACKGROUND: The aim of this study is to determine the minimal postoperative time required that may allow free flap survival after occlusion or ligation of the microsurgical anastomosis without surgical intervention. METHODS: All reports describing free flap survival and failure after delayed postoperative vascular compromise (after postoperative day 3); including thrombosis and ligation, without revision of the microsurgical anastomoses were reviewed. The type of flap, recipient site, vessel of occlusion, postoperative compromise day, and nonsurgical treatment were analyzed. RESULTS: 22 reports (32 flaps) detailed 16 arterial, 6 venous, and 10 simultaneously arterial and venous (vascular pedicle) compromise in 16 head and neck, 10 lower extremity, 4 breast, and 2 upper extremity free tissue transfers. 12 flaps survived without any intervention, 6 survived with conservative therapy (anticoagulation or leeches), and 14 survived despite pedicle ligation. The range of critical day of occlusion did not differ significantly among vessel types. 75% of arterial compromise occurred between 6 and 15 days. 75% of vascular pedicle compromise occurred between 8.5 and 18 days. When compared to jejunal flaps, skin flaps survived after earlier postoperative occlusion (10.2 vs. 20.8 days; P = 0.01). CONCLUSION: This analysis suggests that free flaps compromised by vascular thrombosis or pedicle ligation may survive with only conservative therapy when the event occurs after a minimal critical time period. Flap survival is more probable when arterial occlusion or pedicle ligation occurs after postoperative day 12, but this minimal critical period may be as low as 6 days for arterial occlusion. © 2016 Wiley Periodicals, Inc. Microsurgery 36:604-612, 2016.

Impact of active thermoregulation on the microcirculation of free flaps.

BACKGROUND: While it is a known fact that warming increases blood flow in healthy tissue, little is known about the impact of active thermoregulation on the altered microcirculation of free flaps. The objective of the study was to identify the impact of postoperative active thermoregulation on free flap microcirculation. METHODS: Tissue temperature was assessed in 25 free perforator flaps using an implanted probe. Active thermoregulation was achieved using a water circulation based system. Changes in microcirculation were evaluated at the day of surgery and throughout the first three postoperative days after passive cooling (room temperature), passive warming (wound dressing), active warming (38 °C) and active cooling (15 °C) using laser Doppler flowmetry and remission spectroscopy. RESULTS: Active warming increased flap temperature by 7.7% to 36.4 °C ± 0.5 °C in comparison to the initial values of flaps without dressing (P < 0.001). As a result, the blood flow increased by 77.7% of the base value (P < 0.001). A significant correlation between all microcirculation parameters and tissue temperature was observed with a 5.52 AU blood flow increase per degree temperature increase (r = 0.7; P < 0.001). All microcirculation parameters showed a statistically significant increase after both passive and active warming, whereby active warming showed significantly higher values than passive warming. CONCLUSIONS: Active thermoregulation using water-based circulation is an effective and safe procedure to improve microcirculation in free flaps and is superior to conventional passive warming strategies.

The evaluation of flap growth and long-term results of pediatric mandible reconstructions using free fibular flaps.

Currently, the free fibular flap is well accepted as the first choice for mandibular reconstruction. Achieving functional results in pediatric patients requires a different approach than that employed for mature patients. Because the pediatric craniofacial skeleton continues to grow, reconstruction is more challenging, and the long-term results can be different from those of adult patients. In this study, we sought to measure flap growth objectively in our series. Ten pediatric patients who underwent reconstruction with free fibular flaps were retrospectively reviewed. Flap growth was evaluated by comparing the intraoperative photographs with photographs of the control panoramic mandibular radiographs taken using photo-anthropometric techniques. The measurements were converted to proportionality indices (PI), and these indices were compared. Subsequent complications and functional results were also evaluated. The mean patient age was 11.8 years, and the mean follow up was 57.7 months. The mean preoperative PI value was 10.74 ± 2.47. The mean postoperative PI value was 12.52 ± 2.34. The mean difference between the preoperative and postoperative PI values was -1.78 ± 0.53. These photo-anthropometric data clearly illustrated the growth of the fibular flaps (P = 0.001). None of these patients exhibited nonunion of the fractures; however, one patient experienced a delayed union, one had chronic temporomandibular joint pain, and one had chronic temporomandibular joint luxation. In two patients, the inter-incisive measurements were below the third percentile, and two additional patients had grade 2 eating abilities, which can be regarded as poor. All of the patients had symmetric mandibular contours. Free fibular flaps continue to grow in pediatric patients. This flap is a "workhorse" flap in children because it adapts to the craniofacial skeleton via its ability to grow, and this ability results in subsequent good cosmetic and functional results.

Variables affecting postoperative tissue perfusion monitoring in free flap breast reconstruction.

Postoperative flap monitoring is a key component for successful free tissue transfer. Tissue oxygen saturation measurement (TOx) with near-infrared spectrophotometry (NIRS) is a method used for this purpose. The aim of this study was to identify external variables that can affect TOx. Patients who had breast reconstruction with free flaps were monitored prospectively and intra-operative details were recorded. Flap TOx was recorded with NIRS pre-extubation, postextubation, and then every four hours for 36 hours. At each of these time points, blood oxygen saturation (SO2), amount of supplemental oxygen, and blood pressure were recorded. Thirty flaps were monitored. Initially, a significant trend over time was detected such that for every increase of 24 hours, TOx decreased on average by 2.1% (P = 0.025). However, when accounting for SO2 levels, this decrease was no longer significant (P = 0.19). An increase by 1% in SO2 produced an increase in TOx reading of 0.36 (P = 0.007). The amount of supplemental O2, systolic blood pressure, and diastolic blood pressure did not have a significant impact on TOx (P > 0.05). The TOx values were highest in the free TRAM flaps and were lower in decreasing order in the muscle-sparing TRAM, DIEP, and SIEA flaps (P > 0.05). The TOx values did not significantly correlate with vessel size, perforator number, or perforator row. Postoperative flap TOx was found to correlate with SO2 and was not significantly dependent on blood pressure, supplemental O2, or surgical variables. Careful interpretation of oximetry values is essential in decision making during postoperative flap monitoring.

Force recovery assessment of functioning free muscle transfers using ultrasonography.

PURPOSE: To evaluate the usefulness of ultrasonography for measurement of functioning free muscle transfer strength and estimate the capacity and potential of ultrasonography measurement. METHODS: Twenty-five patients underwent functioning free muscle transfer for brachial plexus injury. The cross-sectional areas (CSAs) of the transferred muscle and the contralateral gracilis (control) were measured using ultrasonography. First, the reliability and reproducibility of the ultrasonography measurements of the muscle CSA was investigated. Next, force recovery was evaluated by calculating the contraction ratio (CR), which was defined as the value equal to the CSA of the transferred muscle under maximum isometric contraction divided by the CSA value in a complete rest position. The CR of the contralateral gracilis was calculated in the same manner. The CR of the transferred muscle and the control were compared statistically. We also analyzed the correlation between the CR of the transferred muscle and other measurements of muscle strength. The follow-up duration was 24 to 87 months after surgery. RESULTS: The reliability and reproducibility of the ultrasonography measurements was determined statistically. The CR of the transferred muscle (1.30 ± 0.12) was significantly greater than that of the contralateral gracilis (1.22 ± 0.13). Furthermore, the CR of the transferred muscle showed significant correlations with both manual muscle testing and elbow arc of motion. CONCLUSIONS: Ultrasonography measurement of transferred muscle can easily indicate the recovery process of rehabilitation in a quantitative and dynamic manner. This study demonstrated that ultrasonography has the capacity to evaluate force recovery objectively. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Implantable Cook-Swartz Doppler probe versus Synovis Flow Coupler for the post-operative monitoring of free flap breast reconstruction.

BACKGROUND: The Cook-Swartz Doppler has long been a trusted tool for close monitoring of blood flow after microvascular reconstruction; however, device implantation requires additional operating time. Synovis Life Technologies, Inc. received FDA approval in 2010 for the Flow Coupler, which combines an end-to-end anastomotic coupler with a removable 20 MHz Doppler, allowing both procedures to be performed simultaneously. However, its short history of widespread use necessitates further evaluation in the clinical setting. The authors studied the Synovis Flow Coupler in comparison to the more well-established Cook-Swartz Doppler for effectiveness and reliability in detection of vascular compromise. METHODS: The authors reviewed 220 free flap breast reconstructions in 150 patients over a three-year period in which either the Cook-Swartz Doppler or the Synovis Flow Coupler was implanted to monitor blood flow. Outcomes measured include false-positive or false-negative rates (FPR, FNR); rates of OR take-back and salvage; and flap survival. RESULTS: FPR was 1.0% for the Cook-Swartz Doppler and 1.9% for the Synovis Flow Coupler (p>0.05). FNR was 0.0% for both groups. Take-back rates were 10.1% for the Cook-Swartz, and 4.5% for Synovis (p>0.05). Flap failure rates were 1.8% and 0.9% for the Cook-Swartz and Synovis devices, respectively (p>0.05). CONCLUSIONS: Our study reveals no statistically significant differences in outcomes for free flap breast reconstruction where either the Cook-Swartz Doppler or the Synovis Flow Coupler was used to monitor blood flow to the perforator flap. LEVEL OF EVIDENCE: III.

The effect of topically applied tissue expanders on radial forearm skin pliability: a prospective self-controlled study.

BACKGROUND: The use of pre-operatively applied topical tissue expansion tapes have previously demonstrated increased rates of primary closure of radial forearm free flap donor sites. This is associated with a reduced cost of care as well as improved cosmetic appearance of the donor site. Unfortunately, little is known about the biomechanical changes these tapes cause in the forearm skin. This study tested the hypothesis that the use of topically applied tissue expansion tapes will result in an increase in forearm skin pliability in patients undergoing radial forearm free flap surgery. METHODS: Twenty-four patients scheduled for head and neck surgery requiring a radial forearm free flap were enrolled in this prospective self-controlled observational study. DynaClose tissue expansion tapes (registered Canica Design Inc, Almonte, Canada) were applied across the forearm one week pre-operatively. Immediately prior to surgery, the skin pliability of the dorsal and volar forearm sites were measured with the Cutometer MPA 580 (registered Courage-Khazaka Electronic GmbH, Cologne, Germany) on both the treatment and contralateral (control) arms. Paired t-tests were used to compare treatment to control at both sites, with p < 0.025 defined as statistically significant. RESULTS: There was a statistically significant increase in pliability by a mean of 0.05 mm (SD = 0.09 mm) between treatment and control arms on the dorsal site (95% CI [0.01, 0.08], p = 0.018). This corresponded to an 8% increase in pliability. In contrast, the volar site did not show a statistically significant difference between treatment and control (mean difference = 0.04 mm, SD = 0.20 mm, 95% CI [-0.04, 0.12], p = 0.30). CONCLUSIONS: This result provides evidence that the pre-operative application of topical tissue expansion tapes produces measurable changes in skin biomechanical properties. The location of this change on the dorsal forearm is consistent with the method of tape application. While this increase in skin pliability may account for the improved rate of primary donor site closure reported using this technique, the results did not reach our definition of clinical significance.