Promotion of peripheral nerve regeneration and prevention of neuroma formation by PRGD/PDLLA/β-TCP conduit: report of two cases

Abstract

In the field of nerve repair, one major challenge is the formation of neuroma. However, reports on both the promotion of nerve regeneration and prevention of traumatic neuroma in the clinical settings are rare in the field of nerve repair. One of the reasons could be the insufficiency in the follow-up system. We have conducted 33 cases of nerve repair using PRGD/PDLLA/β-TCP conduit without any sign of adverse reaction, especially no neuroma formation. Among them, we have selected two cases as representatives to report in this article. The first case was a patient with an upper limb nerve wound was bridged by PRGD/PDLLA/β-TCP conduit and a plate fixation was given. After nearly 3-years' follow-up, the examination results demonstrated that nerve regeneration effect was very good. When the reoperation was performed to remove the steel plate we observed a uniform structure of the regenerated nerve without the formation of neuroma, and to our delight, the implanted conduit was completely degraded 23 months after the implantation. The second case had an obsolete nerve injury with neuroma formation. After removal of the neuroma, the nerve was bridged by PRGD/PDLLA/β-TCP conduit. Follow-up examinations showed that the structure and functional recovery were improved gradually in the 10-month follow-up; no end-enlargement and any other abnormal reaction associated with the characteristic of neuroma were found. Based on our 33-case studies, we have concluded that PRGD/PDLLA/β-TCP nerve conduit could both promote nerve regeneration and prevent neuroma formation; therefore, it is a good alternative for peripheral nerve repair.

Keywords: PRGD/PDLLA/β-TCP conduit; clinical case; neuroma formation; peripheral nerve regeneration.

Figure 1

Gross image of PRGD/PDLLA/β-TCP conduit and photographs taken during the operation. (A) Gross image of PRGD/PDLLA/β-TCP conduit; (B) 20-mm-long nerve defect was bridged with PRGD/PDLLA/β-TCP nerve conduit (25 mm in length and 5 mm inner diameter) (C).

Figure 2

Follow-up examination of patient 1. (A) Monofilament touch test was conducted 13 months after the operation. The measurement was 300 g in tiger mouth area, and 0.4 g in proximal phalanx of index and middle finger; (B) Photographs showing the appearance and functional recovery 13 months after the operation. Wrist stretch and finger stretch of left hand has almost returned to the normal level. Myodynamia reached level 4, and (C) the patient could stretch wrist and fingers in the presence of strong resistance; (D) Electrophysiology results 13 months after the operation. As measured by EMG, the motor nerve conduction velocity was 65.8 m/s, which was close to the normal level; (E, F) High Frequency B Ultrasonography 13-months after the operation. The defects have been bridged with the regenerated nerve. The regenerated nerve fibers appeared healthy with whole lumen and a clear appearance. The blood flow to the nerve was abundant, and no swelling was observed in the conjunction area; (G) Photograph taken during the surgery to remove the Jefferson-fracture reduction plate 23 months after the implantation. The nerve was completely regenerated and reconnected to the both ends of the defects; the structure appeared uniformly without any abnormal expansion. The conduit material was not visible, presumably has degraded completely.

Figure 3

Photographs taken during the operation. (A) Obsolete nerve injury with neuroma formation; (B) Nerve was bridged by PRGD/PDLLA/β-TCP conduit after removal of the neuroma.

Figure 4

Follow-up examinations of patient 2. (A) Monofilament touch test 10 months after the operation. Photograph shown that monofilament touch pressure test was given to the patient; (B, C) Photographs showing the appearance and functional recovery 6 months post-operation. (B) Pen picking was demonstrated; (C) Wrist bending was done with little assistant; (D, E) High Frequency B Ultrasonography taken 6 months after the operation. (D) The triangle arrow pointed to the nerve fibers tract located in the conduit; (E) the nerve between the distal and proximal ends has been connected, red arrow indicated the blood flow in median nerve located at the distal end of the conduit; (F) The amyotrophy of thenar muscles at the left have greatly improved 10 months after the operation; (G, H) Functional Recovery at 10 months after the operation. (G) The left thumb can hold a pen firmly with another finger in fluent and coherent action. (H) Demonstrated that the finger can hold a coin (fine objects) with another finger with less smooth action.