Single-lumen and multi-lumen poly(ethylene glycol) nerve conduits fabricated by stereolithography for peripheral nerve regeneration in vivo.

BACKGROUND: The use of nerve conduits to facilitate nerve regrowth after peripheral nerve injury is limited to defects less than 3 cm. The purpose of this study is to determine the capability of novel single and multi-lumen poly(ethylene glycol) (PEG) conduits manufactured by stereolithography to promote peripheral nerve regeneration. MATERIALS AND METHODS: Eight Sprague Dawley rats with sharp transection injuries of the sciatic nerve were randomly assigned to receive single-lumen or multi-lumen PEG conduits to bridge a 10-mm gap. Sciatic nerve and conduit samples were harvested after 5 weeks, and axon number, myelin thickness, fiber diameter, and g-ratio were analyzed. The contralateral intact nerve was also harvested for comparison. RESULTS: Partial nerve regeneration was observed in three out of four single-lumen conduits and one out of four multi-lumen conduits. Axon number in the single-lumen regenerated nerve approached that of the contralateral intact nerve at 4,492 ± 2,810.0 and 6,080 ± 627.9 fibers/mm(2), respectively. The percentage of small fibers was greater in the single-lumen conduit compared with the intact nerve, whereas myelin thickness and g-ratio were consistently greater in the autologous nerve. Axon regrowth through the multi-lumen conduits was severely limited. CONCLUSION: Single-lumen stereolithography-manufactured PEG nerve conduits promote nerve regeneration, with regenerating axon numbers approaching that of normal nerve. Multi-lumen conduits demonstrated significantly less nerve regeneration, possibly due to physical properties of the conduit inhibiting growth. Further studies are necessary to compare the efficacy of the two conduits for functional recovery and to elucidate the reasons underlying their differences in nerve regeneration potential.

Surgical techniques for spinopelvic reconstruction following total sacrectomy: a systematic review.

PURPOSE: To identify all available reconstruction methods for a total sacrectomy. Secondarily, we aimed to evaluate outcomes based on different interventions. METHODS: We searched PubMed to identify sacral resections for tumors requiring internal fixation for stabilization. Demographic information, fixation techniques and postoperative outcomes were abstracted. RESULTS: Twenty-three publications (43 patients) met inclusion criteria from an initial search of 856 (κ 0.93). Mean age was 37 years and follow-up was 33 months. Fixation methods included a combination of spinopelvic fixation (SPF), posterior pelvic ring fixation (PPRF), and/or anterior spinal column fixation (ASCF). For the purposes of analysis, patients were segregated based on whether they received ASCF. Postoperative complications including wound/instrument infections, GI or vascular complications were reported at a higher rate in the non-ASCF group (1.63 complications/patient vs. 0.7 complications/patient). Instrument failure was seen in 5 (16.1 %) out of the 31 patients with reported outcomes. Specifically, 1 out of 8 patients (12.5 %) with ASCF compared with 4 out of 23 patients (17.4 %) without ASCF had hardware failure. At final follow-up, 35 of 39 patients were ambulating. CONCLUSION: While surgical treatment of primary sacral tumors remains a challenge, there have been advances in reconstruction techniques following total sacrectomy. SPF has shifted from intrapelvic rod and hook constructs to pedicle and iliac screw-rod systems for improved rigidity. PPRF and ASCF have adapted for deficiencies in the posterior ring and anterior column. A trend toward a lower rate of hardware failure emerged in the group utilizing anterior spinal column support. Despite a more involved reconstruction with ASCF, surgical complications such as infection rates and blood loss were lower compared to the group without ASCF. While we cannot definitively say one system is superior to the other, based on the data gleaned from this systematic review, it is our opinion that incorporation of ASCF in reconstructing the spinopelvic junction may lead to improved outcomes. However, most importantly, we recommend that the treating surgeon operate on patients requiring a total sacrectomy based on his or her level of comfort, as these cases can be extremely challenging even among experts.

Fixation techniques for complex traumatic transverse sacral fractures: a systematic review.

STUDY DESIGN: Systematic review. OBJECTIVE: To identify and describe reconstruction methods for the treatment of transverse sacral fracture (TSF) and to evaluate outcomes based on treatment interventions. SUMMARY OF BACKGROUND DATA: A variety of surgical interventions for stabilization of TSFs exist, yet the optimal management remains unclear. Although there are many individual case reports and series describing techniques to stabilize TSF, prior reviews fail to provide a comprehensive summary of current and past surgical techniques and their individual outcomes. METHODS: Our systematic review searched the PubMed database using keywords identifying sacral fractures with a transverse component, requiring internal fixation for stabilization as well as a review of bibliographies and archives from meeting proceedings. RESULTS: Our search located 417 publications for abstract review, of which 27 (109 patients) with TSF were included. Average follow-up was 22 months (range, 0-82 mo). Thirty-eight patients (34%) underwent spinopelvic fixation (SPF), 53 (49%) underwent posterior pelvic ring fixation (PPRF), and 18 (17%) underwent both. PPRF included iliosacral screws (37 patients), transiliac screws (11 patients), transiliac screws with plating (3 patients), posterior plating (1 patient), and transiliac bar (1 patient). Additional injuries causing lumbosacral instability were seen in 8 patients (42%) who underwent SPF, 2 patients (18%) treated with PPRF, and 5 patients (45%) who were treated with both SPF and PPRF. Of those who presented with a neurological deficit, 5 patients (45%) with SPF, 9 (39%) with PPRF, and 3 (30%) with SPF and PPRF experienced full neurological recovery. Five patients (45%) with SPF, 7 (30%) with PPRF, and 5 (50%) with both regained partial neurological function. One patient (9%) with SPF, 7 (30%) with PPRF, and 2 (20%) with both experienced no neurological recovery. CONCLUSION: PPRF seems to be effective for stabilization of TSF. However, in the setting of further injuries causing additional lumbosacral instability, SPF should be used to ensure effective stabilization.