Background: Management of painful neuromas continues to challenge clinicians. Controlling axon growth to prevent neuroma has gained considerable traction. A logical extension of this idea is to therefore develop an approach to control and arrest axon growth. Given the limits in axonal regeneration across acellular nerve allografts (ANAs), these constructs could provide a means to reliably terminate axon regeneration from an injured nerve. The purpose of this study was to determine if attaching an ANA to an injured nerve could provide a means to control and limit axon regeneration in a predictable manner. Methods: Twenty (20) adult rats received a sciatic nerve transection, where only the proximal nerve was repaired using an ANA of variable length (0.5, 2.5, and 5.0 cm) or left unrepaired (control). The nerves were harvested 5 weeks post-operatively for gross and histomorphometric analysis. The extent of myelinated axons in regenerated tissue was quantified. Results: At 5 weeks, limited axon regeneration within the ANAs was observed. All lengths of ANAs lead to reduced myelinated axon numbers in the most terminal tissue region compared to untreated injured nerve ( P = .002). Additionally, ANA length 2.5 cm or greater did not contain any axons at the most terminal tissue region. Conclusions: This study demonstrates a proof of concept that ANAs attached to the proximal end of an injured nerve can limit axon growth in a controlled manner. Furthermore, the extent of axon growth from the injured nerve into the ANA is dependent on the ANA length.
Background: Traumatic brachial plexus injuries (BPIs) disproportionately affect young, able-bodied individuals. Beyond direct costs associated with medical treatment, there are far-reaching indirect costs related to disability and lost productivity. Our objective was to estimate per-patient indirect cost associated with BPI. Methods: We estimated indirect costs as the sum of (1) short-term wage loss, (2) long-term wage loss, and (3) disability payments. Short-term (6-month) wage loss was the product of missed work days and the average earnings per day. The probability of return to work was derived from a systematic review of the literature, and long-term wage loss and disability payments were estimated. Monte Carlo simulation was used to perform a sensitivity analysis of long-term wage loss by varying age, sex, and return to work simultaneously. Disability benefits were estimated from U.S. Social Security Administration data. All cost estimates are in 2018 U.S. dollars. Results: A systematic review of the literature demonstrated that the patients with BPI had a mean age of 26.4 years, 90.5% were male, and manual labor was the most represented occupation. On the basis on these demographics, our base case was a 26-year-old American man working as a manual laborer prior to BPI, with an annual wage of $36,590. Monte Carlo simulation estimated a short-term
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