Thomas Scholz

Peripheral Nerve Injuries: An International Survey of Current Treatments and Future Perspectives

Peripheral nerve injuries are a serious health concern and leave many patients with lifelong disabilities. There is little information about incidences, current practice, outcomes, and type of research that may help delineate new strategies. A questionnaire was designed to determine characteristics of peripheral nerve injuries and the need for alternative strategies and sent to 889 plastic, hand, trauma, and orthopedic surgeons in 49 countries; 324 completed surveys were collected and analyzed (total response rate of 36.45%). The majority of institutions treat more than 3000 patients annually. Trauma was the leading cause of injury with the majority located on the upper extremity. In most cases, a primary repair was achieved, but 2.52% were unrepairable. The overall outcome was linked to their Sunderland classification (SCL). A grade 1 nerve injury (SCL-1) reached a maximum outcome after 7.15 months. SCL-2, -3, -4, and -5 needed 10.69, 14.08, 17.66, and 19.03 months, respectively. Tissue engineering was considered the most important research field, resulting in a visual analogue scale of 8.6. Despite marked advances in the treatment of peripheral nerve injuries, clinical outcomes still appear unsatisfactory. The importance of research in the field of tissue engineering should be emphasized as a pathway toward improving these outcomes.

Postoperative quantitative assessment of reconstructive tissue status in a cutaneous flap model using spatial frequency domain imaging

Background: The purpose of this study was to investigate the capabilities of a novel optical wide-field imaging technology known as spatial frequency domain imaging to quantitatively assess reconstructive tissue status. Methods: Twenty-two cutaneous pedicle flaps were created on 11 rats based on the inferior epigastric vessels. After baseline measurement, all flaps underwent vascular ischemia, induced by clamping the supporting vessels for 2 hours (either arteriovenous or selective venous occlusions); normal saline was injected into the control flap and hypertonic-hyperoncotic saline solution was injected into the experimental flap. Flaps were monitored for 2 hours after reperfusion. The spatial frequency domain imaging system was used for quantitative assessment of flap status over the duration of the experiment. Results: All flaps demonstrated a significant decline in oxyhemoglobin and tissue oxygen saturation in response to occlusion. Total hemoglobin and deoxyhemoglobin were increased markedly in the selective venous occlusion group. After reperfusion and the administration of solutions, oxyhemoglobin and tissue oxygen saturation in those flaps that survived gradually returned to baseline levels. However, flaps for which oxyhemoglobin and tissue oxygen saturation did not show any signs of recovery appeared to be compromised and eventually became necrotic within 24 to 48 hours in both occlusion groups. Conclusions: Spatial frequency domain imaging technology provides a quantitative, objective method of assessing tissue status. This study demonstrates the potential of this optical technology to assess tissue perfusion in a very precise and quantitative way, enabling wide-field visualization of physiologic parameters. The results of this study suggest that spatial frequency domain imaging may provide a means for prospectively identifying dysfunctional flaps well in advance of failure.

Neuronal differentiation of human adipose tissue-derived stem cells for peripheral nerve regeneration in vivo.

OBJECTIVE To evaluate the ability of a tissue-engineered nerve construct composed of a nerve guidance channel and neurally differentiated human adipose tissue-derived stem cells (hASCs) to enhance peripheral nerve regeneration in a rat sciatic nerve model. DESIGN A 13-mm sciatic nerve gap was bridged with silastic conduits in 64 athymic nude rats, and differentiated hASCs were implanted into the nerve gap. The effect of repetitive renewal of differentiation medium on days 14 and 28 was further tested. Adequate negative controls and isograft controls were used. SETTING Academic research. PATIENTS The hASCs were isolated from human adipose tissue of patients undergoing liposuction procedures. MAIN OUTCOME MEASURES Direct measurements of nerve function included sciatic functional index score, extensor postural thrust, and sensory evaluation. Indirect measurements included gastrocnemius and soleus muscle atrophy. Histomorphometric evaluation included the number and diameter of axons and fibers, nerve fiber density, myelin thickness, g-ratio (axon diameter-total fiber diameter ratio), and myelin thickness-axon diameter ratio. RESULTS The use of hASCs demonstrated significantly improved functional recovery as measured by the sciatic functional index, extensor postural thrust, sensory evaluation, and gastrocnemius and soleus muscle weight after 14 days and 1, 2, 3, and 4 months. Groups with their medium renewed also demonstrated further enhanced functional recovery compared with their counterparts that did not have their medium renewed. CONCLUSION This tissue-engineered nerve construct using hASCs was able to improve functional recovery during the first 4 months, comparable with nerve isografts.

Evidence-based value of subcutaneous surgical wound drainage: the largest systematic review and meta-analysis.

Background: The purpose of this study was to determine the evidenced-based value of prophylactic drainage of subcutaneous wounds in surgery. Methods: An electronic search was performed. Articles comparing subcutaneous prophylactic drainage with no drainage were identified and classified by level of evidence. If sufficient randomized controlled trials were included, a meta-analysis was performed using the random-effects model. Fifty-two randomized controlled trials were included in the meta-analysis, and subgroups were determined by specific surgical procedures or characteristics (cesarean delivery, abdominal wound, breast reduction, breast biopsy, femoral wound, axillary lymph node dissection, hip and knee arthroplasty, obesity, and clean-contaminated wound). Studies were compared for the following endpoints: hematoma, wound healing issues, seroma, abscess, and infection. Results: Fifty-two studies with a total of 6930 operations were identified as suitable for this analysis. There were 3495 operations in the drain group and 3435 in the no-drain group. Prophylactic subcutaneous drainage offered a statistically significant advantage only for (1) prevention of hematomas in breast biopsy procedures and (2) prevention of seromas in axillary node dissections. In all other procedures studied, drainage did not offer an advantage. Conclusions: Many surgical operations can be performed safely without prophylactic drainage. Surgeons can consider omitting drains after cesarean section, breast reduction, abdominal wounds, femoral wounds, and hip and knee joint replacement. Furthermore, surgeons should consider not placing drains prophylactically in obese patients. However, drain placement following a surgical procedure is the surgeon’s choice and can be based on multiple factors beyond the type of procedure being performed or the patient’s body habitus. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Early Detection of Complete Vascular Occlusion in a Pedicle Flap Model Using Quantitation Spectral Imaging

Background: Vascular occlusion after tissue transfer is a devastating complication that can lead to complete flap loss. Spatial frequency domain imaging is a new, noncontact, noninvasive, wide-field imaging technology capable of quantifying oxygenated and deoxygenated hemoglobin levels, total hemoglobin, and tissue saturation. Methods: Pedicled fasciocutaneous flaps on Wistar rats (400 to 500 g) were created and underwent continuous imaging using spatial frequency domain imaging before and after selective vascular occlusion. Three flap groups (control, selective arterial occlusion, and selective venous occlusion) and a fourth group composed of native skin between the flaps were measured. Results: There were no statistically significant differences between the control flap group and the experimental flap groups before selective vascular occlusion: oxyhemoglobin (p = 0.2017), deoxyhemoglobin (p = 0.3145), total hemoglobin (p = 0.2718), and tissue saturation,(p = 0.0777). In the selective arterial occlusion flap group, percentage change in total hemoglobin was statistically different from that of the control flap group (p = 0.0218). The remaining parameters were not statistically different from those of the control flap: percentage change in oxyhemoglobin (p = 0.0888), percentage change in deoxyhemoglobin (p = 0.5198), and percentage change in tissue saturation (p = 0.4220). The selective venous occlusion flap group demonstrated changes statistically different compared with the control flap group: percentage change in oxyhemoglobin (p = 0.0029) and deoxyhemoglobin, total hemoglobin, and tissue saturation (p < 0.0001). Conclusions: Spatial frequency domain imaging provides two-dimensional, spatially resolved maps of tissue oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation. Results presented here indicate that this can be used to quantify and detect physiologic changes that occur after arterial and venous occlusion in a rodent tissue transfer flap model. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative patients.

What Patients Look for When Choosing a Plastic Surgeon: An Assessment of Patient Preference by Conjoint Analysis

The knowledge of patient preference is crucial for plastic surgeons to determine optimal marketing strategies. Conjoint analysis is a statistical technique whereby research participants make a series of trade-offs. Analysis of these trade-offs reveals the relative importance of component attributes. This study will evaluate the relative importance of attributes that influence the selection and decision-making process when choosing a plastic surgeon. A questionnaire consisting of 18 plastic surgeon profiles was rated by 111 patients. Attributes analyzed were as follows: travel distance, number of years in practice, board certification status, method of referral, office décor, and procedure cost. A traditional full-profile conjoint analysis was performed. Subjects consisted of 10 men and 101 women (n = 111). Median age was 51 years (range, 19–72). The “mean importance” of the attributes are as follows: board certification status, 39.7%; method of referral, 23.5%; distance from home to office, 13.2%; office décor, 9.0%; number of years in practice, 7.5%; and cost of procedure, 7.2%. Internal validity checks showed a high correlation (Pearson ρ = 0.995; P < 0.001). This pilot study demonstrates that conjoint analysis is a very powerful tool for market research in the health care system. The level of importance for each attribute reliably helps plastic surgeons to understand the preferences of their patients, thus being able to improve marketing strategies for private practices and institutions. The present study indicates that the most important attributes were board certification and method of referral.

Quantitative assessment of partial vascular occlusions in a swine pedicle flap model using spatial frequency domain imaging

The use of tissue transfer flaps has become a common and effective technique for reconstructing or replacing damaged tissue. While the overall failure rate associated with these procedures is relatively low (5-10%), the failure rate of tissue flaps that require additional surgery is significantly higher (40-60%). The reason for this is largely due to the absence of a technique for objectively assessing tissue health after surgery. Here we have investigated spatial frequency domain imaging (SFDI) as a potential tool to do this. By projecting wide-field patterned illumination at multiple wavelengths onto a tissue surface, SFDI is able to quantify absolute concentrations of oxygenated and deoxygenated hemoglobin over a large field of view. We have assessed the sensitivity of SFDI in a swine pedicle flap model by using a controlled vascular occlusion system that reduced blood flow by 25%, 50%, 75%, or 100% of the baseline values in either the vein or artery. SFDI was able to detect significant changes for oxygenated hemoglobin, deoxygenated hemoglobin, or tissue oxygen saturation in partial arterial occlusions of at least 50% and partial venous occlusions of at least 25%. This shows SFDI is sensitive enough to quantify changes in the tissue hemoglobin state during partial occlusions and thus has the potential to be a powerful tool for the early prediction of tissue flap failure.

Orbital Floor Fractures: A Retrospective Review of 45 Cases at a Tertiary Health Care Center

The purpose of this retrospective study was to investigate treatment options for orbital floor fractures at a Level 1 Trauma Center in Southern California. A review of 45 cases of isolated orbital floor fractures treated at the University of California at Irvine between February 2004 and April 2007 was done. Patients were retrospectively analyzed for gender, age, mechanism of injury, associated facial injuries, presenting symptoms, method of treatment, and postoperative complications. Thirty-six male patients and nine female patients were treated. Motor vehicle collision (26/45) was the most common cause of injury, and the mean age of the patients was 35.5 years (range: 15—81 years). Ecchymosis surrounding the orbital tissue was the most common presentation (38/45). Diplopia was present in 8 of 45 patients, with 1 patient requiring urgent decompression for retrobulbar hematoma. Forty-three patients underwent surgical repair; 40 underwent transconjunctival approach with lateral canthotomy; 17 underwent reconstruction with porous polyethylene Medpor (Porex Surgical, Inc., College Park, GA.); and 26 underwent reconstruction with a titanium mesh plate. Immediate postoperative complications included 12 patients with infraorbital numbness, 3 with diplopia, 1 with cellulitis, and 1 with ectropion with a subcilliary approach. Average timing of surgery of our study was 4.94 days (range, 1—20 days). Orbital floor fracture management has changed significantly over the past few decades with the introduction of new internal fixation methods and new materials for reconstructing orbital floor defects. Recommendations for surgical intervention on orbital floor fractures mostly depend on clinical examination and imaging studies. Consequences of inadequate repair of orbital floor fractures can lead to significant facial asymmetry and visual problems. Both porous polyethylene and titanium plates are effective tools for reconstructing the orbital floor. Our review demonstrates that orbital floor fractures can be repaired safely with minimal postoperative complications and confirms that transconjunctival approach to orbital floor is an effective way for exposure and prevention of ectropion that can be seen with other techniques.

Capsular Contracture in Implant-Based Breast Reconstruction: Examining the Role of Acellular Dermal Matrix Fenestrations.

Background: Acellular dermal matrices have been proposed to decrease the incidence of capsular contracture in implant-based breast reconstructions. The authors have modified acellular dermal matrices with fenestrations to facilitate greater lower pole expansion and improve contour. The effect of fenestrations on the ability of matrices to suppress capsule formation, however, has not been examined. Methods: A retrospective review of all fenestrated acellular dermal matrix–assisted, implant-based breast reconstructions performed by the two senior authors, with a minimum of 1-year follow-up after permanent implant placement, was completed. Patient demographics, details of extirpative and reconstructive procedures, and complications were examined. Capsular contractures were scored according to the Baker grading scale and compared to those reported in the literature. Results: Thirty patients (50 breasts) underwent fenestrated acellular dermal matrix–assisted reconstruction, with mean follow-up times of 3.3 and 2.6 years after expander placement and implant exchange, respectively. Seven patients (23 percent) had a body mass index greater than 30 kg/m2, three (10 percent) were active smokers, and six breasts (12 percent) were irradiated. Complications included one infection (2 percent), six cases (12 percent) of incisional superficial skin necrosis, and one (2 percent) tissue expander extrusion. Zero breasts had clinically significant Baker grade III/IV capsular contracture. The average Baker grade was 1.1. Conclusions: Fenestrated acellular dermal matrices decrease capsular contracture to rates similar to what is seen with nonfenestrated matrices. Further research is necessary to determine whether this observation is a result of decreased need for inferolateral acellular dermal matrix coverage to achieve these effects or modified physical interaction of acellular dermal matrices with surrounding soft tissues. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Release Kinetics of Polymer-bound Bone Morphogenetic Protein-2 and Its Effects on the Osteogenic Expression of Mc3t3-e1 Osteoprecursor Cells

Background: In an effort to augment scaffold performance, additives such as growth factors are under investigation for their ability to optimize the “osteopotential” of synthetic polymer scaffolds. In parallel research, bone morphogenetic protein-2 (BMP-2), a growth factor that initiates bone formation, has been locally delivered to augment fracture healing and spinal fusion. The authors hypothesize that BMP-2 can be covalently bound to a polymer substrate, increasing its concentration and bioavailability over longer periods, thus improving the efficacy of the growth factor and subsequently the bony matrix production. It would remain bound longer when compared with published controls. This prolonged binding would then increase the bioavailability of the growth factor and thus increase bony matrix production over a longer interval. Methods: Mouse preosteoblast MC3T3-E1 cells were cultured on poly(lactic-co-glycolic acid) and polycaprolactone polymer disks covalently bound with BMP-2 to assess the progression and quality of osteogenesis. Covalent binding of BMP-2 to each polymer was visualized by immunohistochemical analysis of polymer-coated microscope slides. The quantity of covalently bound BMP-2 was determined using enzyme-linked immunosorbent assay. Results: Polymerase chain reaction results showed elevated expression levels for alkaline phosphatase and osteocalcin genes. BMP-2 was released from polycaprolactone over 2 weeks, with 86 percent remaining covalently bound, in contrast to 93 percent retained by poly(lactic-co-glycolic acid). Conclusions: BMP-2, proven to alter polymer osteogenicity, remained bound to poly(lactic-co-glycolic acid), which may render poly(lactic-co-glycolic acid) an ideal choice as a polymer for scaffold-based bone tissue engineering using growth factor delivery.