Open surgical implantation of a viable cryopreserved placental membrane after decompression and neurolysis of common peroneal nerve: a case series

Following expedited institutional review board approval, Saint Joseph Hospital Protocol #2016-30, data were obtained through a retrospective medical record review of patients who underwent secondary CPN decompression and neurolysis by a single surgeon at the Department of Surgery at Chicago Foot & Ankle Deformity Corrections Center. A total of seven subjects (four males, three females) who had undergone previously failed CPN decompression were identified for analysis. The collection of de-identified data sets included the primary mechanism of injury, severity of symptoms at time of referral, pre-operative and post-operative evaluations on edema with ultrasound, Medical Research Council (MRC) scale for motor strength, range of motion, nerve conduction velocity (NCV), and electromyography (EMG). Descriptive statistics (mean, standard deviation, etc) were used for data analysis.

vCPM is a point-of-care allograft that retains an intact extracellular matrix, resident growth factors, and endogenous neonatal mesenchymal stem cells, fibroblasts, and epithelial cells native to the fresh tissue through a proprietary cryopreservation method [9‐11]. vCPM is fully tested according to FDA and AATB requirements and has a 2-year shelf life at −80 °C [12]. vCPMs are ~100-μM-thin membranes that are conforming and self-adherent to other tissues. Human placental membranes have been reported to support natural tissue repair and to reduce inflammation, pain, and scar formation [13, 14]. These properties, make them attractive for various soft tissue reconstructive procedures including microsurgical CPN repairs where minimizing postoperative inflammation, pain, and adhesion formation are critical for successful clinical outcome (Fig. 1a).

All procedures were carried out after induction of general anesthesia with surgeon’s utilization of 3.5 loupe magnification for appropriate field visualization. The patients were positioned in lateral decubitus with the affected limb flexed at approximately 35°. After site preparation and draping, a 3-cm lazy “S” shaped transverse incision was made 3 cm distally and 2 cm medially to the fibular head with a 10-blade scalpel. Using Metzenbaum scissors, the incision was carried down to the subcutaneous tissue while protecting vital structures and nerves. Careful blunt dissection by Metzenbaum scissors was performed to separate the muscular fascia and expose the CPN. The CPN was traced around the fibular neck while excising the fascia of the anterior and lateral compartments to decompress the deep peroneal and superficial nerves. A portable nerve stimulator (Checkpoint®; NDI Medical), set at 0.02–2 mA for 2–3 s, was used to locate areas of severe nerve scarring. Microsurgical instruments were used to perform longitudinal and circumferential epineurotomy. Internal and external neurolysis was performed until the bands of Fontana were observed in the fascicles. Over the area of fascicular damage, vCPM allograft was applied (Fig. 1a). Then, the CPN was wrapped with a collagen nerve conduit (Fig. 1b) (NeuraGen®; LifeSciences Corporation). Additional nerve stimulation was performed to ensure no compression was caused by the graft or the conduit. The conduit was transposed laterally and was sutured to the adjacent lateral subcutaneous tissue. The subcutaneous tissue was re-approximated in a layered fashion using a 3-0 Vicryl sutures, and the skin was closed using skin staples. A semicompressive dressing was applied over the incision site, and affected lower extremity was placed in surgical shoe. Patients were placed into immobilization of the affected lower extremity and were provided with post-operative instructions for gradual progression into full weight-bearing ambulation as tolerated.