Jan-Philipp Stromps

Improvement of facial scar appearance and microcirculation by autologous lipofilling

BACKGROUND Autologous lipofilling has become a standard procedure for many indications in plastic surgery. Single-case studies have reported improvements in scars, especially in burn patients, after autologous lipofilling. Despite its widespread use, little is known about the mechanisms responsible for this improvement. It is hypothesized that the mesenchymal stem cells and numerous growth factors contained in the lipoaspirate contribute to the skin and scar remodeling. MATERIAL AND METHODS Between 2008 and 2012, 35 facial scars (n=35) on 26 patients (n=26) were treated by autologous lipofilling. The preoperative examinations and postoperative follow-up included use of the patient and observer scar assessment scale (POSAS), photo documentation, and laser Doppler spectrometry (O2C) measurements of tissue oxygen saturation, hemoglobin levels, and microcirculation on the second, seventh, and ninetieth postoperative days. RESULTS The scar quality improved in all cases, leading to a high patient satisfaction rate at the final follow-up examination. The POSAS scores were significantly increased for pain (p=0.0331), color (p=0.0007), stiffness (p=0.0030), irregularity (p=0.0039), pigmentation (p=0.0282), and pliability (p=0.0404). In addition, we observed increased hemoglobin levels in the early postoperative period (second day) and a reduction in the microcirculation, which normalized to the preoperative values after 7-90 days. CONCLUSIONS We demonstrated that autologous lipofilling represents a valuable technique for the treatment of facial scars. Further prospective observational studies are needed to better understand the mechanisms leading to scar enhancement and to make this procedure more reliable and predictable for patients.

Chondrogenic Differentiation of Human Adipose-Derived Stem Cells: A New Path in Articular Cartilage Defect Management?

According to data published by the Centers for Disease Control and Prevention, over 6 million people undergo a variety of medical procedures for the repair of articular cartilage defects in the U.S. each year. Trauma, tumor, and age-related degeneration can cause major defects in articular cartilage, which has a poor intrinsic capacity for healing. Therefore, there is substantial interest in the development of novel cartilage tissue engineering strategies to restore articular cartilage defects to a normal or prediseased state. Special attention has been paid to the expansion of chondrocytes, which produce and maintain the cartilaginous matrix in healthy cartilage. This review summarizes the current efforts to generate chondrocytes from adipose-derived stem cells (ASCs) and provides an outlook on promising future strategies.

Computer-assisted zygoma reconstruction with vascularized iliac crest bone graft.

The reconstruction of zygoma is a challenge with regard to aesthetic and reconstructive demands.

Retrograde tracing and toe spreading after experimental autologous nerve transplantation and crush injury of the sciatic nerve: a descriptive methodological study.

Evaluation of functional and structural recovery after peripheral nerve injury is crucial to determine the therapeutic effect of a nerve repair strategy. In the present study, we examined the relationship between the structural evaluation of regeneration by means of retrograde tracing and the functional analysis of toe spreading. Two standardized rat sciatic nerve injury models were used to address this relationship. As such, animals received either a 2 cm sciatic nerve defect (neurotmesis) followed by autologous nerve transplantation (ANT animals) or a crush injury with spontaneous recovery (axonotmesis; CI animals). Functional recovery of toe spreading was observed over an observation period of 84 days. In contrast to CI animals, ANT animals did not reach pre-surgical levels of toe spreading. After the observation period, the lipophilic dye DiI was applied to label sensory and motor neurons in dorsal root ganglia (DRG; sensory neurons) and spinal cord (motor neurons), respectively. No statistical difference in motor or sensory neuron counts could be detected between ANT and CI animals. In the present study we could indicate that there was no direct relationship between functional recovery (toe spreading) measured by SSI and the number of labelled (motor and sensory) neurons evaluated by retrograde tracing. The present findings demonstrate that a multimodal approach with a variety of independent evaluation tools is essential to understand and estimate the therapeutic benefit of a nerve repair strategy.

Locked minimally invasive plating versus fourth generation nailing in the treatment of AO/OTA 31A2.2 fractures: A biomechanical comparison of PCCP® and Intertan nail®☆

INTRODUCTION Locked minimally invasive plating and fourth generation nailing potentially could reduce the complication rate in the treatment of trochanteric femur fractures by its rotational stability and providing better lateral cortical support. The purpose of this study was (1) to compare the biomechanical properties of the Percutaneous compression plate (PCCP) and the Intertan nail (IT) with regards to implant failure and (2) to assess dynamic stability coefficients in an unstable AO/OTA 31A2.2 fracture model. METHODS In paired femurs, a standardised unstable trochanteric femur fracture was induced by an oscillating saw. The fractures were stabilised by either the PCCP (Orthofix, McKinney, TX, USA) or the IT (Smith & Nephew, Memphis, TN, USA). All femurs were loaded with 300N, followed by an increase in load until failure using 300N each time (2000 cycles each, 0.5Hz). After every load step the samples were assessed visually and radiographically. We measured migration and performed a survival analysis. RESULTS 16 fractures were induced in 8 paired human specimens (mean age: 84 years, 61-100 years). The mean stiffness (PCCP vs. IT: 249±124N/mm vs. 273±153N/mm; p=0.737) was comparable. The IT proved superior to the PCCP with regard to the number of cycles reached before failure occurred (PCCP vs. IT: 12,691±4733 vs. 15,313±4875 cycles; p=0.023). Except for a higher axial migration of the IT at failure point (PCCP vs. IT: 1.3mm vs. 4.3mm; p=0.028) there were no differences between the intra- and extramedullary implants, not even in terms of rotational stability along the femoral neck axis. A fracture of the femoral neck caused test abortion in both implants in most cases. CONCLUSION This study showed a superiority of the IT compared with the PCCP with regards to number of cycles achieved under sequential load increases for unstable trochanteric femur fractures. The stiffness was comparable. Both implants showed a high rotational stability and a support of the lateral wall. STUDY TYPE Biomechanical study.

Intraalveolar TNF-α in combined burn and inhalation injury compared with intraalveolar interleukin-6.

The objective of this study was to evaluate the role of intraalveolar tumor necrosis factor-&agr; (TNF-&agr;) and interleukin-6 (IL-6) in a combination of skin burn and smoke inhalation injuries because this combined trauma is associated with an increased morbidity and mortality compared with either of these traumas alone. We used a standardized small animal model (rats n = 84) to investigate the early intraalveolar excretion of TNF-&agr; during the first one, three, and six hours after a singular skin burn injury, singular smoke inhalation injury, and a combination involving both the traumas. The data were compared with the data from control rats that only received preparation and mechanical ventilation. The TNF-&agr; serum levels and intraalveolar IL-6 concentrations were also measured. One hour after trauma, there was a significant difference in the TNF-&agr; concentration between the controls and both the singular traumas (control vs burn P < .0444 and control vs smoke P < .005) and between the inhalation injury and the combined trauma (smoke vs burn + smoke P < .0084). After three and six hours, no significant differences among the groups were observed. Compared with the controls, both the singular skin burn and smoke inhalation injuries led to increased intraalveolar TNF-&agr; excretion, whereas the combined trauma showed the least intraalveolar TNF-&agr; levels at three and six hours post-trauma. These findings differed from the serum TNF-&agr; levels. Compared with the IL-6 levels, we observed a negative correlation within the intraalveolar cytokine concentrations after one hour (r = −.809), three hours (r = −.627), and six hours (r = −.746). This study confirms the importance of the intraalveolar cytokine reaction in the early posttraumatic stage after a combined burn and inhalation injury. The differences between the combined and singular traumas indicate that TNF-&agr; plays a role in the immunologic hyporesponsiveness of the lung and therefore in the systemic pathophysiological pathway, that often leads to patient mortality. In addition, an inverse correlation between TNF-&agr; and IL-6, both classical markers of inflammation, in the intraalveolar space was observed.

Multidimensional approach to teaching anatomy—Do gender and learning style matter?

BACKGROUND The aim of this study was to assess the impact of two teaching interventions (ultrasound and arthroscopy) in a peer teaching (PT) environment on anatomy examination scores and also to examine the influence of gender and learning style on these scores. METHODS We randomly assigned 484 second year medical students to one of three groups: musculoskeletal ultrasound (MSUS), arthroscopy (ASC) and control (CON). The MSUS- and the ASC-group attended two additional training sessions in ultrasound or arthroscopy; the CON-group received no additional lessons. Students were asked to complete Kolbs Learning Style Inventory test. We assessed differences in anatomical knowledge (multiple choice (MC) exam) and subjective evaluation with respect to gender and learning style. RESULTS There were no relevant differences between the three groups regarding the MC exam. Acceptance of the peer teaching concept was good. All students preferred ultrasound to arthroscopy and thought that they learned more from ultrasound despite the fact that they rated the instructors as less competent and needed more time to gain in-depth knowledge. There was no significant effect of gender on evaluation results. Arthroscopy was best enjoyed by accommodators according to Kolbs Inventory and least by divergers, who found that they had learned a lot through ultrasound. The improvement in spatial conceptualization was greatest for accommodators and worst for assimilators. CONCLUSION Gender and learning style had no impact on quantitative parameters. Qualitative analysis, however, revealed differences for learning style and further evaluation is warranted to assess the impact on medical education.

Development of a biomechanical model of the wrist joint for patient-specific model guided surgical therapy planning: Part 1

An enhanced musculoskeletal biomechanical model of the wrist joint is presented in this article. The developed computational model features the two forearm bones radius and ulna, the eight wrist bones, the five metacarpal bones, and a soft tissue apparatus. Validation of the model was based on information taken from the literature as well as own experimental passive in vitro motion analysis of eight cadaver specimens. The computational model is based on the multi-body simulation software AnyBody. A comprehensive ligamentous apparatus was implemented allowing the investigation of ligament function. The model can easily patient specific personalized on the basis of image information. The model enables simulation of individual wrist motion and predicts trends correctly in the case of changing kinematics. Therefore, patient-specific multi-body simulation models are potentially valuable tools for surgeons in pre- and intraoperative planning of implant placement and orientation.

Impact of scapholunate dissociation on human wrist kinematics

Neither the complex motions of the scapholunate joint, nor the kinematic changes that occur as a result of injury to it, are fully understood. We used electromagnetic tracking within affected bones to evaluate the physiologic motions in the planes of flexion and extension, and of radial and ulnar deviation of human cadaver wrists, before and after complete transection of the scapholunate ligaments. Despite individual variance between each wrist, we were able to establish a pattern in the changes that occurred after scapholunate ligament injury. During the motions examined, the scaphoid showed an increase in translational deviation in almost all motion axes. In contrast, the movement of the lunate seemed to be impaired, especially in radial-ulnar deviation.

A biomechanical model of the wrist joint for patient-specific model guided surgical therapy: Part 2.

An enhanced musculoskeletal biomechanical model of the wrist joint is presented in this article. The computational model is based on the multi-body simulation software AnyBody. Multi body dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to wrist joint degeneration and restoration. In this study, the simulation model of the wrist joint was used for investigating deeper the biomechanical function of the wrist joint. In representative physiological scenarios, the joint behavior and muscle forces were computed. Furthermore, the load transmission of the proximal wrist joint was investigated. The model was able to calculate the parameters of interest that are not easily obtainable experimentally, such as muscle forces and proximal wrist joint forces. In the case of muscle force investigation, the computational model was able to accurately predict the computational outcome for flexion and extension motion. In the case of force distribution of the proximal wrist joint, the model was able to predict accurately the computational outcome for an axial load of 140 N. The presented model and approach of using a multi-body simulation model are anticipated to have value as a predictive clinical tool including effect of injuries or anatomical variations and initial outcome of surgical procedures for patient-specific planning and custom implant design. Therefore, patient-specific multi-body simulation models are potentially valuable tools for surgeons in pre- and intraoperative planning of implant placement and orientation.