Electronic Bone Growth Stimulators for Augmentation of Osteogenesis in In Vitro and In Vivo Models: A Narrative Review of Electrical Stimulation Mechanisms and Device Specifications.

Since the piezoelectric quality of bone was discovered in 1957, scientists have applied exogenous electrical stimulation for the purpose of healing. Despite the efforts made over the past 60 years, electronic bone growth stimulators are not in common clinical use. Reasons for this include high cost and lack of faith in the efficacy of bone growth stimulators on behalf of clinicians. The purpose of this narrative review is to examine the preclinical body of literature supporting electrical stimulation and its effect on bone properties and elucidate gaps in clinical translation with an emphasis on device specifications and mechanisms of action. When examining these studies, trends become apparent. In vitro and small animal studies are successful in inducing osteogenesis with all electrical stimulation modalities: direct current, pulsed electromagnetic field, and capacitive coupling. However, large animal studies are largely unsuccessful with the non-invasive modalities. This may be due to issues of scale and thickness of tissue planes with varying levels of resistivity, not present in small animal models. Additionally, it is difficult to draw conclusions from studies due to the varying units of stimulation strength and stimulation protocols and incomplete device specification reporting. To better understand the disconnect between the large and small animal model, the authors recommend increasing scientific rigor for these studies and reporting a novel minimum set of parameters depending on the stimulation modality.

Recovery and Regrowth After Nerve Repair: A Systematic Analysis of Four Repair Techniques.

BACKGROUND: Outcome assessments that evaluate post-transection nerve repair do not often correlate with one another. The aims of this study were twofold: to compare four nerve repair techniques with each other and incorporate both negative and positive control groups and to identify possible correlations between outcome assessments. MATERIALS AND METHODS: Sciatic nerve transection and repair was performed in Lewis rats using one of the following techniques: interrupted epineural, running epineural, grouped fascicular, epineural with absorbable type I collagen wrap, and high tension for incorporation of a negative control. A sham surgery group was also included as a positive control group. Outcomes were compared using assessments of functional recovery (behavior and electrophysiology) and nerve regrowth (imaging and histomorphometry). Three-dimensional printed custom electrode stabilization and imaging devices were designed and fabricated to provide standardization in assessment between subjects. RESULTS: Nerve repair was performed in 48 male Lewis rats. In all animals, functional testing was performed at week 13. The sham group (n = 7) performed the best on both behavioral assays (P < 0.001) and electrophysiology assessments (P < 0.001). The negative control group (high tension) performed poorest on multiple assessments, and there were no significant differences observed for any of the four repair types. Positive correlations were observed between behavioral and histomorphometric tests. CONCLUSIONS: There was no difference in outcome between the four types of nerve repair. High-tension nerve repair represents an ideal negative control. Not all assessment methods correlate equally, and consistent use of complimentary outcome assessments could allow for improved comparison between studies.

The Surgical Treatment of Adult Acquired Buried Penis Syndrome: A New Classification System.

BACKGROUND: Adult acquired buried penis syndrome may be associated with an inability to void, sexual dysfunction, and recurrent infection. Previously published classification systems rely on intraoperative findings, such as penile skin quality. OBJECTIVES: The purpose of this study was to evaluate outcomes after adult acquired buried penis repair and to develop a classification system based on preoperative assessment. METHODS: The authors reviewed data from patients who underwent buried penis reconstruction at a single institution. Patient history and physical examination guided the development of a classification system for surgical planning. RESULTS: Of the 27 patients included, the mean age was 56 ± 15 years and mean body mass index was 49 ± 14 kg/m2. Patients were classified into 4 groups based on examination findings: (I) buried penis due to skin deficiency, iatrogenic scarring, and/or diseased penile skin (n = 3); (II) excess abdominal skin and fat (n = 6); (III) excess skin and fat with diseased penile skin (n = 16); and (IV) type III plus severe scrotal edema (n = 2). Surgical treatment (eg, excision and grafting, mons suspension, panniculectomy, translocation of testes, and/or scrotectomy) was tailored based on classification. Complications included wound breakdown (n = 3), cellulitis (n = 4), and hematoma (n = 1). Nearly all patients (96%) reported early satisfaction and improvement in their symptoms postoperatively. CONCLUSIONS: Classifying patients with buried penis according to preoperative examination findings may guide surgical decision-making and preoperative counseling and allow for optimized aesthetics to enhance self-esteem and sexual well-being.

Quantification of Collagen Organization after Nerve Repair.

BACKGROUND: Clinical outcomes after nerve injury and repair remain suboptimal. Patients may be plagued by poor functional recovery and painful neuroma at the repair site, characterized by disorganized collagen and sprouting axons. Collagen deposition during wound healing can be intrinsically imaged using second harmonic generation (SHG) microscopy. The purpose of this study was to develop a protocol for SHG imaging of nerves and to assess whether collagen alignment can be quantified after nerve repair. METHODS: Sciatic nerve transection and epineural repair was performed in male rats. The contralateral nerves were used as intra-animal controls. Ten-millimeter nerve segments were harvested and fixed onto slides. SHG images were collected using a 20× objective on a multiphoton microscope. Collagen fiber alignment was calculated using CurveAlign software. Alignment was calculated on a scale from 0 to 1, where 1 represents perfect alignment. Statistical analysis was performed using a linear mixed-effects model. RESULTS: Eight male rats underwent right sciatic nerve repair using 9-0 Nylon suture. There were gross variations in collagen fiber organization in the repaired nerves compared with the controls. Quantitatively, collagen fibers were more aligned in the control nerves (mean alignment 0.754, SE 0.055) than in the repairs (mean alignment 0.413, SE 0.047; P < 0.001). CONCLUSIONS: SHG microscopy can be used to quantitate collagen after nerve repair via fiber alignment. Given that the development of neuroma likely reflects aberrant wound healing, ex vivo and/or in vivo SHG imaging may be useful for further investigation of the variables predisposing to neuroma.