Feasibility for Immediate Targeted Muscle Reinnervation Based on Lower Extremity Amputations Trends

Targeted muscle reinnervation has been adopted as a strategy for the management and prevention of phantom limb pain and symptomatic neuroma formation for patients undergoing lower extremity amputation. The procedure is often performed by surgeons different from those performing the amputation, creating scheduling dilemmas. The purpose of this study was to analyze historic trends in lower extremity amputation scheduling in a single hospital system to evaluate if offering routine immediate targeted muscle reinnervation is practical.

Methods

De-identified data over a five-year period for all patients undergoing lower extremity amputation were collected. The data gathered included the specialty performing the amputation, weekly distribution of cases, start time, and end time, among others.

Results

A total of 1549 lower extremity amputations were performed. There was no statistically significant difference in average number of below-the-knee amputations (172.8) and above-the-knee amputations (137.4) per year. Top specialties performing amputations were vascular surgery (47.8%), orthopedic surgery (34.5%), and general surgery (13.85%). No significant difference was noted in the average number of amputations across the week, per year. Most cases started between 6 am and 6 pm (96.4%). The average length of stay after surgery was 8.26 days.

Conclusions

In a large, nontrauma hospital system, most lower extremity amputations are performed during typical working hours and are evenly distributed throughout the week. Understanding peak timing of amputations may allow for targeted muscle reinnervation to be performed concurrently with amputation procedure. Data presented will be a first step to optimizing amputation scheduling for patients in a large nontrauma health system.

Deep venous thrombosis in a 41-year-old female with May–Thurner syndrome following abdominoplasty and medial thigh lift

Deep venous thrombosis (DVT) is a feared occurrence following body contouring surgery as it can result in pulmonary embolism. Acute presentation can range from lower extremity edema and pain to being totally asymptomatic. Surgical literature reports reveal many risk factors for developing DVT, and surgeons must risk stratify their patients to best prevent this outcome. However, there are conditions which place patients at risk that are difficult to account for when making such decisions as they can be undiagnosed and are not a part of standard screening protocols. We present a case of DVT in a 41-year-old female with undiagnosed May–Thurner syndrome following abdominoplasty and medial thigh lift for massive weight loss. The authors discuss the current literature as well as challenges faced by surgeons who strive to appropriately risk stratify their cosmetic surgery patients to avoid complications such as venous thromboembolism.

Does Complexity Always Correlate With Compensation? An Analysis of Work Relative Value Units in 3 Common Nerve Decompression Syndromes

BACKGROUND

Work relative value units (wRVUs) are part of Resource Based Relative Value Scale system. It is expected that a more difficult and time-consuming procedure would yield higher wRVUs. Brachial plexus nerve decompression surgery is a more time-consuming procedure compared with carpal and cubital tunnel procedures. The aim of this study was to analyze physician reimbursement in upper limb decompression procedures by comparing mean operative times, wRVUs per minute, and dollars per minute.

METHODS

A retrospective cohort study was conducted from June 2016 to June 2019, including all patients who underwent carpal tunnel, cubital tunnel, and brachial plexus release procedures. Operating time was collected, and calculations of mean operative time, wRVUs per minute, and dollars per minute were performed and compared between groups.

RESULTS

A total of 209 cases were included. Carpal tunnel accounted for 75.1% of the cases, followed by cubital tunnel and brachial plexus releases. Brachial plexus release had the highest median operative time (147 minutes), followed by cubital tunnel (57 minutes) and carpal tunnel release (16 minutes, P < 0.0001). Carpal tunnel release procedures had a significantly higher wRVUs per minute (0.310) when compared with cubital tunnel and brachial pleaxus release procedures, 0.127 and 0.077, respectively (P < 0.0001). Same was true for dollars per minute; carpal tunnel procedures yielded significantly more compensation than cubital tunnel and thoracic outlet procedures (P < 0.0001).

CONCLUSIONS

More complex and time-consuming procedures yielded a lower reimbursement for physicians. The current work relative unit system does not account adequately for the time spent in each procedure.

Parastomal Hernia Repair Using a Silo Biologic Mesh

BACKGROUND

A parastomal hernia (PSH) is an enlargement of the stoma's original opening through the abdominal wall's musculature around a colostomy, ileostomy, or urostomy. Its incidence can be up to 48%. The described methods for its repair have high recurrence rate.This article presents a 3-dimensional silo technique for PSH repair (PSH-R). The aims of this technique are to enhance the structural strength of the tunnel wall, to reinforce both the sidewalls and the fascia above and below the muscular opening, and to maintain a stable stoma opening.

METHODS

All consecutive patients undergoing PSH-R with the silo technique between January 2009 and May 2018 by 2 plastic surgeons were included. The outcome parameters of interest were hernia recurrence and wound-related complications.

RESULTS

This study reports 22 patients (9 male, 13 female) with a mean age of 66.7 years and an average body mass index of 29.2. The variety of ostomy types included 10 colostomies, 7 ileostomies, and 5 urostomies. Postoperatively, there were 3 surgical site infections, 1 seroma, and 2 wound healing delays. Six patients were readmitted, 3 of those because of small bowel obstruction. These 3 cases all required reoperation, in addition to 1 operative revision for stoma retraction. During our average follow-up of 19.9 months, 3 cases of PSH recurrence were diagnosed for a recurrence rate of 13.6%.

CONCLUSIONS

This silo technique is associated with favorable complication and low recurrence rates compared with the available techniques in surgical literature. In our practice, it has established itself as a new and safe technique for complex or recurrent PSHs and should be considered in a surgeon's armamentarium. This technique has become our standard for treatment of recurrent PSHs.

Static Suspension of the Paralyzed Face Utilizing the Midfacial Corridor: Anatomic Evaluation and Surgical Technique

INTRODUCTION

 Fascia lata and tendon grafts are frequently utilized to support the paralyzed midface and to extend muscular reach in McLaughin style, orthodromic temporalis transfers. The grafts are frequently placed in a deep subcutaneous positioning that can lead to the development of a, bowstring deformity in the cheek. This paper describes insertion of tendon grafts into the midfacial corridor collectively formed by the buccal, submasseteric and superficial temporal spaces.

METHODS

 Over a seven-year period, all patients that underwent insertion of facia lata and tendon grafts in the midfacial corridor were included. Demographic information, perioperative variables and clinical outcomes were collected and analyzed.

RESULTS

 A total of 22 patients were included with a mean age of 64.3 years (33-86). There were multiple etiologies for the facial weakness including acoustic neuroma (9.1%), Bell's palsy (13.6%), facial nerve schwannoma (9.1%), temporal bone fracture (4.6%) and malignancy (22.7%). Midfacial corridor grafts were utilized in combination with nerve transfers (V-VII and XII-VII) in nine patients, McLaughin style temporalis transfers in 12 and as a standalone procedure in one individual. During the study period, no patients exhibited a tethering, or concave deformity in the midface. Additionally, no impingement, difficulties with mastication, parotitis or hematoma were encountered. One patient developed a postoperative infection, that was successfully managed.

CONCLUSION

 Placement of tendon or fascia grafts for static support or tunneling of an orthodromic temporalis transfer through the midfacial corridor can be performed rapidly while providing midfacial support and avoiding the creation of visible cutaneous deformities.

Refining the Rib-sparing Approach in Microsurgical Breast Reconstruction: Keys to Success

BACKGROUND

 Free tissue transfer using microsurgical techniques is a popular option for breast reconstruction, and the internal mammary vessels remain the most popular recipient vessels for the anastomosis. Traditionally, ribs were resected for better access to these vessels in the intercostal space. However, rib resection has the potential for complications and adds a surgical step. Here, the authors evaluate and compare both techniques in a retrospective study as well as offer technical pearls.

METHODS

 The 400 most recent consecutive patients who underwent microsurgical breast reconstruction by a single surgeon were retrospectively reviewed. 54 patients underwent the traditional rib-resecting approach. 346 patients underwent the rib-sparing approach, which was the preferred approach of the senior author, when possible. Patients requiring the rib-resecting approach were distributed evenly throughout the series. Primary outcomes were any immediate post-operative complications.

RESULTS

 Between the two clinical groups, there was no difference between demographic or clinical details, the flap type, history of previous radiation, or timing of reconstruction. Complications of any kind as well as the subset of complications were significantly more frequent in the rib resection than in the rib-sparing group. Specifically, the rate of reanastomosis was higher in the rib resection group [10.6 vs 2.7%, p < 0.001] as was the frequency of return to the OR in the immediate post-operative setting [3.0 vs 0.3%, p < 0.001]. There is a 4.50 odds ratio of having a complication in a rib resection case versus rib sparing [CI: 1.97-10.30, p < 0.001]. All cases were initiated with the intent to perform a rib-sparing approach if possible, and they were converted to a rib-resection approach as needed.

CONCLUSION

 In the largest reported series to date, the rib-sparing approach is demonstrated to be both safe and efficacious in microsurgical breast reconstruction.

Dual Innervation of Free Functional Muscle Flaps in Facial Paralysis

Dual innervation in free muscle flap facial reanimation has been used to create a functional synergy between the powerful commissure excursion that can be achieved with the masseter nerve and the spontaneity that can be derived from a cross-face nerve graft. The gracilis has been the most frequently used muscle flap, and multiple combinations of neurorrhaphies have been described, including the masseter to the obturator (end-to-end) combined with a cross-face nerve graft to the obturator (end-to-side) and vice versa. Single and staged approaches have been reported. Minimally, dual innervation is as effective as using the motor nerve to masseter alone.

Comparing plastic surgery and otolaryngology surgical outcomes and cartilage graft preferences in pediatric rhinoplasty: A retrospective cohort study analyzing 1839 patients

ABSTRACT

Rhinoplasty in children has raised concerns about its safety in the pediatric population. There is scarcity of evidence describing outcomes and surgical techniques performed in pediatric rhinoplasty. We analyzed post-operative complications and cartilage preferences between plastic surgeons and otolaryngologists.Data was collected through the Pediatric National Surgical Improvement Program from 2012 to 2017. Current Procedure Terminology codes were used for data extraction. Patients were grouped according to type of rhinoplasty procedures (primary, secondary, and cleft rhinoplasty). A comparison between plastic surgeons and otolaryngologists was made in each group in terms of postoperative complications. Additionally, a sub-group analysis based on cartilage graft preferences was performed.During the study period, a total of 1839 patients underwent rhinoplasty procedures; plastic surgeons performed 1438 (78.2%) cases and otolaryngologists performed 401 (21.8%) cases. After analyzing each group, no significant differences were noted in terms of wound dehiscence, surgical site infection, readmission, or reoperation. Subgroup analysis revealed that plastic surgeons prefer using rib and ear cartilage, while otolaryngologists prefer septal and ear cartilage.The analysis of 1839 pediatric patients undergoing three types of rhinoplasty procedures showed similar postoperative outcomes, but different cartilage graft utilization between plastic surgeons and otolaryngologists.

Monte Carlo simulation of a LSC based on stacked layers of fiber arrays with core-coating different absorbing properties

In this work, a Monte Carlo ray-tracing model for the simulation and optimization of a fiber Luminescent Solar Concentrator (LSC) based on stacked layers of fiber arrays is developed and validated. The fiber LSC efficiency improvements are compared against a conventional planar LSC. We developed a new model to analyze the performance of different configurations of bulk-doped fibers and fibers constituted by a doped coating and a passive core. These configurations are analyzed also varying fiber packing geometry diameters, and length. Due to the exceptionally low absorption coefficient of the silica fibers (α_wg ≈ 10^-4 cm^-1), concentration factors of up to 1.9 are predicted when dimensions are scaled over 1 m², which improve more than twice the maximum concentration factor ever reported. These results serve as a preliminary theoretical study for the future development of a new LSC design based on flexible silica micro-fibers coated with Si-QDs doped poly(lauryl methacrylate) (PLMA) layers.

Efficacy of Closed Incision Negative Pressure Wound Therapy on Abdominal Donor Site After Free Flap Breast Reconstruction

INTRODUCTION

Negative pressure wound therapy (NPWT) has been used to treat acute and chronic wounds in a variety of scenarios. Specifically, in autologous breast reconstruction, studies investigating the use of closed incision NPWT (ciNPWT) in breast surgery are lacking.

OBJECTIVE

The aim of this study was to analyze the use of ciNPWT at the abdominal donor site following deep inferior epigastric perforator (DIEP) flap breast reconstruction.

MATERIALS AND METHODS

A retrospective cohort study was conducted over a 15-month period including patients who underwent abdominally based microsurgical breast reconstruction. Patients were divided into 2 groups: (1) a control group that underwent standard abdominal donor site closure and (2) an experimental group that underwent standard abdominal donor site closure plus ciNPWT. Groups were compared in terms of demographic characteristics, perioperative variables, and abdominal donor site complications.

RESULTS

A total of 42 patients were identified. Of these, 18 were included in the control group and 24 in the ciNPWT group. No cases of seroma, abdominal bulge, or abdominal hernia were reported. Wound dehiscence developed in 2 patients (11.1%) in the control group and in 3 patients (12.5%) in the experimental group (P = 1.000). One patient (5.6%) in the control group had an infection of the donor site compared with none in the ciNPWT group (P = .429). Interestingly, 3 patients developed hyperpigmentation where the ciNPWT plastic drape was placed.

CONCLUSIONS

The use of ciNPWT on the abdominal donor site following DIEP flap breast reconstruction did not lower the incidence of wound dehiscence and wound infection. Different approaches are needed to decrease the incidence of donor site complications in abdominally based postmastectomy breast reconstruction.

Reoperative Cervical Endocrine Surgery: Appropriate Valuation for the Time and Effort?

BACKGROUND

Controversies currently exist regarding the best way to appropriately quantify complexity and to benchmark reimbursement for surgeons. This study aims to analyze surgeon reimbursement in primary and redo-thyroidectomy and parathyroidectomy using operative time as a surrogate for complexity.

METHODS

A retrospective analysis using the National Surgical Quality Improvement Program database was performed to identify patients who underwent primary and redo-thyroidectomy and parathyroidectomy. Calculations of median operative time work relative value units per minute and dollars per minute were compared between primary and redo procedures.

RESULTS

Thyroidectomy cases represented 53.5% (22,521 cases), and the other 46.5% (19,596 cases) were parathyroidectomy cases. The median dollars per minute in primary thyroidectomy was $4.97 and for redo-thyroidectomy was $8.12 (P < 0.0001). By the same token, dollars per minute were higher in the redo cases with $15.40 when compared with primary parathyroidectomy cases with $13.14 dollars per minute (P < 0.0001).

CONCLUSIONS

By Current Procedural Terminology codes, surgeons appear to be appropriately reimbursed for redo-thyroid and parathyroid procedures indexed to first time parathyroidectomy based on the compensated operative time of these procedures calculated using a nationally representative sample.

How to Maximize Aesthetics in Autologous Breast Reconstruction

With continuous technical and functional advances in the field of breast reconstruction, there is now a greater focus on the artistry and aesthetic aspects of autologous reconstruction. Whereas once surgeons were most concerned with flap survival and vessel patency, they are now dedicated to reconstructing a similarly or even more aesthetically pleasing breast than before tumor resection. We discuss the approach to shaping the breast through the footprint, conus, and skin envelope. We then discuss how donor site aesthetics can be optimized through flap design, scar management, and umbilical positioning. Each patient has a different perception of their ideal breast appearance, and through conversation and counseling, realistic goals can be set to reach optimal aesthetic outcomes in breast reconstruction.

Successful Free Tissue Transfer in the Profoundly Hypercoagulable Glioblastoma Multiforme Patient: Surgical Experience and Anticoagulation Protocol

Background Glioblastoma multiforme (GBM) produces a hypercoagulable environment and is associated the highest rates of deep venous thrombosis (DVT) and pulmonary emboli (PE) of any malignancy. The use of postoperative radiation in this generally compromised patient group is associated with the development of complex scalp wounds. Free tissue transfer reconstruction will be essential in selected cases despite the presence of an underlying hypercoagulable state.

Methods A 67-year-old female with a history of previous DVT presented with osteoradionecrosis and infected scalp wound following GBM treatment. She underwent reconstruction with a free vastus lateralis flap and skin graft. Initial anticoagulation was provided with intravenous heparin and transitioned to oral apixaban. Wound cultures demonstrated coagulase-negative Staphylococcus, Actinomyces neuii, and Peptoniphilus harei and were treated with a 6-week course of intravenous cefepime and vancomycin.

Results Despite the initial failure of a local scalp rotation flap, successful wound healing was achieved with a free muscle flap and a course of culture specific antibiotics. The patient succumbed to recurrent disease 22 months after surgery, underscoring the importance of limiting hospitalization and maximizing quality of life in this group of patients.

Conclusion Free tissue transfer can be successfully achieved in the hypercoagulable GBM patient. Heparin and apixaban were employed successfully in the prevention of thrombotic events. Antiplatelet therapy should also be considered to counteract platelet aggregation induced by the transmembrane glycoprotein (podoplanin) that is expressed on GBM tumor cells. Enzyme-linked immunosorbent assay testing (ELISA) of blood soluble podoplanin may help determine the degree of hypercoagulability and guide therapy.

Role of CTA in Women with Abdominal Scars Undergoing DIEP Breast Reconstruction: Review of 1,187 Flaps

Background This study examines the effect of prior abdominal surgery on flap, donor-site, and overall complications in women undergoing deep inferior epigastric artery perforator (DIEP) flap breast reconstruction and assesses whether preoperative computed tomography angiography (CTA) affects outcomes.

Methods All DIEP flaps performed at our institution between 2004 and 2015 were identified retrospectively. Patients were stratified based on a history of prior abdominal surgery and whether or not they underwent a preoperative CTA. A subgroup analysis was performed to compare operative times and incidence of complications using adjusted odds ratios (ORs).

Results Over a 12-year period, 425 patients (640 flaps) had prior abdominal surgery, and 393 patients (547 flaps) had no prior abdominal surgery. Of the patients with previous abdominal surgery, 67 (15.7%) underwent preoperative CTA and 333 (78.4%) did not. Patients with prior abdominal surgery were more likely to have donor-site wound complications (OR: 1.82, 95% confidence interval [CI]: 1.15–2.87, p = 0.01), fat necrosis ≥2cm of the transferred flap (OR: 1.39, 95% CI: 1.0–1.94, p = 0.05), and were more likely to have bilateral DIEP flap reconstruction (OR: 1.61, 95% CI: 1.22–2.12, p < 0.001). Preoperative CTA did not reduce the risk of complications and did not affect operative times.

Conclusion DIEP flap reconstruction can be safely performed in women with prior abdominal surgery. However, these patients should be counseled that they are at an increased risk for donor-site wound breakdown and fat necrosis of the reconstructed breast. Preoperative CTA does not reduce complication rate, overall operative time, or time needed to dissect perforators in women with abdominal scars.

Readability and Understandability Analysis of Online Materials Related to Abdominal Aortic Aneurysm Repair

Background:

Patients commonly use online materials as a source of health information. Since poor health literacy has been shown to correlate with negative outcomes, it is recommended that patient-directed materials be written at a sixth-grade reading level. This study evaluates the readability and understandability of commonly accessed online materials pertaining to both endovascular and open repair of abdominal aortic aneurysm.

Methods:

Searches for “endovascular repair abdominal aortic aneurysm” and “open repair abdominal aortic aneurysm” were performed on both Google and Bing, and the top 10 websites from each search engine were identified. Relevant websites (total N = 28, endovascular n = 15, open n = 15, and 2 redundant sites) with patient-directed content were analyzed. Readability was assessed using 9 established methods, and understandability was assessed using the Patient Education Materials Assessment Tool scoring system.

Results:

The average reading grade level for all sites was 12.8. Endovascular sites averaged a reading grade level of 13.6 with a range from 11.5 to 15.6. Open-repair websites had a grade-level average of 12.1 with a range from 9.9 to 14.1. Readability was found to be inversely related to understandability, with a Pearson correlation coefficient of −0.551 ( P = .003). No website was written at or below the recommended sixth-grade reading level.

Conclusions:

Patient-directed online health information pertaining to open and endovascular repair of abdominal aortic aneurysm exceeds the recommended sixth-grade reading level. Increasing complexity of health literature correlates with poor understandability. Modifications such as shorter sentences, fewer words with more than 6 letters, and increasing usage of clear visual aids can increase readability and understandability.

Evaluating Patient Outcomes in Breast and Abdominal Cosmetic Plastic Surgery Procedures Involving Residents

BACKGROUND

Hands-on training and exposure to cosmetic surgery is an integral part of plastic surgery residency. However, resident participation in cosmetic surgical cases is often limited in many training programs. Furthermore, the effect of resident participation in cosmetic surgery is poorly defined.

OBJECTIVES

The aim of this study was to analyze the impact of resident involvement on outcomes in cosmetic plastic surgery procedures, with a focus on breast and abdominal surgeries.

METHODS

A retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Program database was performed to identify all patients undergoing cosmetic breast and abdominal surgical procedures by plastic surgeons over a 4-year period (2009-2012). Multivariate regression models were constructed to determine any association between resident participation and surgical outcomes.

RESULTS

A total of 6982 patients were included in the analysis. Cases with resident involvement had higher rates of superficial surgical site infection (P < 0.0001), wound dehiscence (P = 0.014), and an increase in mean length of hospital stay (P = 0.001). Multivariate analysis revealed that the increased rate of superficial surgical site infection was associated with a higher body mass index and with the involvement of a resident during the surgical procedure.

CONCLUSIONS

This study provides further evidence to support the claim that resident involvement in cosmetic surgery is safe, with little effect on the rates of major complications. Any increase in minor complication rates must be critically analyzed with respect to the valuable surgical experience gathered by the next generation of surgeons.

LEVEL OF EVIDENCE: 2

A Comparative Multimetric Assessment of English and Spanish Carpal Tunnel Syndrome Materials

BACKGROUND

Spanish-speaking Hispanics living in the United States utilize the internet as a primary means to obtain health information. Accurate, accessible information is important for English speakers; however, it could have even greater utility for Spanish speakers who have lower health literacy levels. The aim of this study was to evaluate and compare online English and Spanish carpal tunnel surgery materials provided by using a multimetric approach.

MATERIALS AND METHODS

A web search using the English term "carpal tunnel surgery" was performed. The first 10 institutional/organizational websites that provided carpal tunnel surgery information in English and Spanish were included. All relevant online materials were evaluated using the Patient Education and Materials Assessment Tool (PEMAT), Cultural Sensitivity Assessment Tool (CSAT), and Simplified Measure of Gobbledygook, Spanish (SOL) to assess understandability and actionability, cultural sensitivity, and readability, respectively.

RESULTS

There were no statistically significant differences in understandability or actionability scores between Spanish and English materials. Average cultural sensitivity scores for Spanish materials were significantly lower than English materials (P = 0.015). The average reading grade level of online English materials was greater than that for Spanish materials (P = 0.011). Both mean values were above the recommended sixth-grade reading level.

CONCLUSIONS

Online patient-directed information regarding carpal tunnel surgery exceeded the recommended reading grade level for both English and Spanish-speaking populations. Most Spanish materials were often direct translations and were not contoured to the elevated literacy needs of this demographic. Institutions must caution their authors to tailor their web material in a way that is sensitive to their target population to optimize understanding.

A Multicenter Analysis Examining Patients Undergoing Conversion of Implant-based Breast Reconstruction to Abdominally based Free Tissue Transfer

BACKGROUND

 Breast implant placement is the most common method for postmastectomy reconstruction. For patients who develop complications associated with implant-based reconstruction, additional surgeries may be challenging. This study examined implant-based reconstruction failure in patients undergoing salvage with abdominal free tissue transfer.

METHODS

 We conducted an Institutional Review Board approved, multicenter retrospective study of patients with implant-based primary breast reconstruction followed by implant removal and subsequent abdominal free tissue transfer between 2006 and 2016. Patient demographics, treatment details, and complications were evaluated. Severity of implant failure was graded as either (1) not severe (delayed salvage reconstruction) or (2) severe (immediate salvage reconstruction).

RESULTS

 Between 2006 and 2016, 115 patients with 180 mastectomy defects underwent primary implant-based reconstruction with subsequent implant removal and abdominally based free tissue reconstruction. Of these, 68 were delayed and 47 were immediate salvage reconstruction. Factors leading to elective removal were capsular contracture, asymmetry, and implant malposition. Factors leading to obligatory removal were infection, delayed wound healing, and implant extrusion. Postmastectomy radiation was significantly associated with immediate salvage reconstruction (p < 0.001, odds ratio = 3.9) as were large volume implants (p = 0.06). Deep inferior epigastric perforator flaps comprised 78.3% of all abdominally based free tissue reconstructions, while muscle-sparing transverse rectus abdominus myocutaneous flaps comprised 18.3%. Overall flap failure rate was 2.6% (2.94% delayed and 2.13% immediate salvage reconstruction; p = 1.0).

CONCLUSION

 Our findings suggest that abdominal free tissue transfer remains a safe and effective salvage modality for implant-based breast reconstruction failure. Patients with severe implant failure were more likely to have received radiation. Surgeons should remain cognizant of this during care of patients.

Three-dimensional Fourier transform evaluation of sequences of spatially and temporally modulated speckle interferograms

Phase evaluation methods based on the 2D spatial Fourier transform of a speckle interferogram with spatial carrier usually assume that the Fourier spectrum of the interferogram has a trimodal distribution, i. e. that the side lobes corresponding to the interferential terms do not overlap the other two spectral terms, which are related to the intensity of the object and reference beams, respectively. Otherwise, part of the spectrum of the object beam is inside the inverse-transform window of the selected interference lobe and induces an error in the resultant phase map. We present a technique for the acquisition and processing of speckle interferogram sequences that separates the interference lobes from the other spectral terms when the aforementioned assumption does not apply and regardless of the temporal bandwidth of the phase signal. It requires the recording of a sequence of interferograms with spatial and temporal carriers, and their processing with a 3D Fourier transform. In the resultant 3D spectrum, the spatial and temporal carriers separate the conjugate interferential terms from each other and from the term related to the object beam. Experimental corroboration is provided through the measurement of the amplitude of surface acoustic waves in plates with a double-pulsed TV holography setup. The results obtained with the proposed method are compared to those obtained with the processing of individual interferograms with the regular spatial-carrier 2D Fourier transform method.

Enhancing the sensitivity to small phase changes in double-exposure stroboscopic television holography

We present a new technique for enhancing the sensitivity of double-exposure stroboscopic television holography (TVH) to detect and measure vibrations of small amplitude. The technique is based in the modulation of the phase of the reference beam in synchronism with the vibration of the measurand and derives from a former technique that we originally contrived for phase evaluation. We propose two variants, characterized by the demodulation process used to generate the secondary correlograms, with different behaviors in terms of the sensitivity to the sign of the measurand and of the ease in detecting the presence and shape of the vibration. We have implemented this new technique in an electronic speckle-pattern interferometer and compared its performance with standard TVH techniques; vibrations with amplitudes as small as 8 nm have been observed with this setup.

Transient Deformation Measurement by Double-Pulsed-Subtraction TV Holography and the Fourier Transform Method

We report the measurement of transient bending waves with double-pulsed-subtraction TV holography. The correlation fringe patterns are automatically quantitatively analyzed by the application of Fourier methods. A novel optical setup with two different object-beam optical paths is demonstrated for the generation of carrier fringes. The proposed system is highly immune to environmental disturbances because the optical setup imposes no lower limit on the time separation between laser pulses. One removes the linear phase distribution due to the spatial carrier in the spatial domain by subtracting the phase of the undeformed carrier fringes from the phase of the modulated fringes. Experimental results obtained with an aluminum plate excited by the impact of a piezoelectric translator are presented.

Multiplicative moiré two-beam phase-stepping and fourier-transform methods for the evaluation of multiple-beam fizeau patterns: a comparison

A phase-evaluation method of multiple-beam Fizeau patterns that combines two-beam phase-stepping algorithms with the moiré effect was previously reported [Appl. Opt. 34, 3639-3643(1995)]. The method is based on a multiplicative moiréimage-formation process obtained by the direct superposition of high-frequency multiple-beam Fizeau carrier fringes upon a transmission grating (working as a phase modulator). We present a comparison between this multiplicative moiré two-beam phase-stepping method and the well-known Fourier-transform method for the topographic measurement of an undoped silicon wafer. The discrepancy between the two methods yields a rms phase-difference value of the order of(~2pi/90).

Measurement range analysis in moiré evaluation Fizeau interferometry

Fizeau interferograms are evaluated by two-beam phase-stepping algorithms. The sinusoidal intensity profile pattern needed for the application of these algorithms is obtained by low-pass filtering the moiré pattern provided by the superposition of the interferogram onto a Ronchi grid. The phase modulation is performed by the in-plane displacement of the grid by means of a motorized stage. In this research the measurement range of the evaluation method as a function of the maximum derivative of height surfaces is calculated. A spherical surface is measured in different configurations in order to verify the obtained results.

Study of transient deformations with pulsed TV holography: application to crack detection

We report the measurement of reproducible transient deformations with single-pulsed-subtraction and double-pulsed-addition TV holography with both in-plane and out-of-plane optical configurations. An original synchronization system (controlling mechanical excitation of the object, firing the laser pulses, and image acquisition) used to obtain the subtraction and the addition correlation fringes is described. Experimental results are presented for the propagation of mechanical shock waves in a cantilever specimen and their subsequent diffraction by a crack in the specimen. These preliminary results show that the technique may be used for crack detection.

Phase error calculation in a Fizeau interferometer by Fourier expansion of the intensity profile

The spectrum of the intensity profile of multiple-beam Fizeau interferograms is presented. Knowledge of this spectrum provides valuable information about the characteristics of Fizeau interferograms, allowing one to calculate the phase error when the Fizeau profile is evaluated by means of two-beam phase-stepping algorithms, as is usual for low-reflectivity coefficients.

Fizeau phase-measuring interferometry using the moiré effect

The automation of the fringe pattern analysis in Fizeau interferometry combining the moiré effect with the phase-stepping evaluation method is presented. In this case the phase modulator is a Ronchi grid placed at the interferometer image plane yielding a moiré image, and the necessary phase steps are obtained, simply translating the grid in its own plane, perpendicular to the optical axis. A detailed description of the moiré image formation as an incoherent superposition is developed. Measurements were carried out in a Fizeau interferometer built by the authors, and rms repeatabilities of less than 3 deg in the phase-difference values were attained.

Annulling parasitic fringes in real time holographic interferometry: a new method

A method for annulling parasitic fringes in real time holographicin terferometrya nd its theoreticalj ustification is presented. The main advantage relates to cancellation of nondesired object motions or deformations with experimental simplicity.