From the Department of Peripheral Nerve Surgery, Queen Elizabeth Hospital.
HaPPeN Research Fellow, Institute of Translational Medicine.
Ann Plast Surg. 2022 Jul 1;89(1):63-71. doi: 10.1097/SAP.0000000000003055. Epub 2021 Dec 6.
Acellular nerve allograft (ANA) occupies an increasingly prominent role in the treatment of peripheral nerve reconstruction. There is demonstrable efficacy; however, some grafts fail to support axonal regrowth and the reasons for this are unclear. This study examines the ANA experience in a specialized peripheral nerve surgery department to discuss the clinical and histological findings in failed cases.
Failed ANA grafts were identified from a prospective database using Medical Research Council Classification (MRCC) S3 and M3 as thresholds for success. Cases in which ANA grafting was indicated for nerve related pain and dysesthesia but where no subjective improvement in symptoms occurred were also included. Patients requiring revision surgery after ANA grafting were also considered failures. Cases were then examined in conjunction with a literature review to identify possible mechanisms of failure, including detailed histological analysis in 2 cases.
Eight failed procedures were identified from a database of 99 separate allograft records on 74 patients. This included procedures for 2 tibial nerves, 2 superficial radial nerves, 2 median nerves, 1 digital nerve and a lateral cord brachial plexus injury (male/female, 5:3; age range, 24-54 years). Allograft length range 25 to 120 mm. One postoperative infection was identified. Histological findings in 2 cases included adequate vascularization of allograft material without subsequent axonal regeneration, a reduction of large myelinated fibers proximal to a tibial nerve allograft in the setting of a chronic injury, and a preference for small rather than large fiber regeneration.
This article reports instances of ANA graft failure in a variety of contexts, for which the primary reasons for failure remain unclear. The etiology is likely to be multifactorial with both patient, graft and surgeon factors contributing to failure. Further clinical and histological analysis of ANA failures will improve our understanding of the mechanisms of graft failure.
去细胞神经同种异体移植物（ANA）在外周神经重建治疗中占据着越来越重要的地位。它具有明显的疗效，但有些移植物不能支持轴突再生，其原因尚不清楚。本研究通过对专门的外周神经外科部门的 ANA 经验进行检查，讨论了失败病例的临床和组织学发现。
使用医疗研究委员会分类（MRCC）S3 和 M3 作为成功的阈值，从前瞻性数据库中确定失败的 ANA 移植物。在 ANA 移植被认为与神经相关的疼痛和感觉异常有关，但症状没有主观改善的情况下，也包括了这种情况。ANA 移植后需要进行修正手术的患者也被认为是失败的。然后，结合文献复习对这些病例进行了检查，以确定可能的失败机制，包括 2 例详细的组织学分析。
从 74 名患者的 99 例单独同种异体记录的数据库中确定了 8 例失败的手术。这包括 2 例胫骨神经、2 例浅桡神经、2 例正中神经、1 例指神经和 1 例外侧束臂丛损伤（男/女，5:3；年龄范围，24-54 岁）。同种异体移植物的长度范围为 25-120 毫米。发现 1 例术后感染。2 例的组织学发现包括同种异体材料有足够的血管化，但没有随后的轴突再生，在胫骨神经同种异体的慢性损伤背景下，大有髓纤维减少，小纤维而非大纤维再生偏好。
本文报告了各种情况下 ANA 移植物失败的情况，其主要失败原因仍不清楚。病因可能是多因素的，包括患者、移植物和外科医生的因素都会导致失败。对 ANA 失败的进一步临床和组织学分析将提高我们对移植物失败机制的理解。
