Comparison of Outcomes after Atlantoaxial Fusion with Transarticular Screws and Screw-Rod Constructs

OBJECTIVE: The purpose of this study was to compare the radiological and neurological outcomes between two atlantoaxial fusion method for atlantoaxial stabilization; C1 lateral mass-C2 pedicle screws (screw-rod constructs, SRC) versus C1-2 transarticular screws (TAS). METHODS: Forty-one patients in whom atlantoaxial instability was treated with atlantoaxial fixation by SRC group (27 patients, from March 2005 to May 2011) or TAS group (14 patients, from May 2000 to December 2005) were retrospectively reviewed. Numeric rating scale (NRS) for pain assessment, Oswestry disability index (ODI), and Frankel grade were also checked for neurological outcome. In radiologic outcome assessment, proper screw position and fusion rate were checked. Perioperative parameters such as blood loss during operation, operation time, and radiation exposure time were also reviewed. RESULTS: The improvement of NRS and ODI were not different between both groups significantly. Good to excellent response in Frankel grade is shown similarly in both groups. Proper screw position and fusion rate were also observed similarly between two groups. Total bleeding amount during operation is lesser in SRC group than TAS group, but not significantly (p=0.06). Operation time and X-ray exposure time were shorter in SRC group than in TAS group (all p<0.001). CONCLUSION: Both TAS and SRC could be selected as safe and effective treatment options for C1-2 instability. But the perioperative result, which is technical demanding and X-ray exposure might be expected better in SRC group compared to TAS group.

Repeated Complication Following Atlantoaxial Fusion: A Case Report

A patients with atlantoaixial instability and osodontoideum underwent atlantoaixial fusion (Harms and Melcher technique) with demineralized bone matrix. But, unfortunately, the both pedicle screws in C2 were fractured within 9 weeks follow-up periods after several suspected episode of neck hyper-flexion. Fractured screws were not contact to occipital bone in several imaging studies, but it could irritate the occipital bone when neck extension because the relatively close distance between the occipital bone and C1 posterior arch. The patient underwent revision operation with translaminar screw fixation with autologus iliac bone graft. Postsurgical course were uneventful except donor site pain, but the bony fusion was not satisfied after 4 months follow-up. The patient re-underwent revision operation in other hospital. Continuous complication after atlantoaixial fusion is rare, but the clinical course could be unlucky to patients. Postoperative immobilization could be important to prevent the unintended clinical course of patients.

Evaluation of Spinal Fusion Using Bone Marrow Derived Mesenchymal Stem Cells with or without Fibroblast Growth Factor-4

OBJECTIVE: In this study, the authors assessed the ability of rat bone marrow derived mesenchymal stem cells (BMDMSCs), in the presence of a growth factor, fibroblast growth factor-4 (FGF-4) and hydroxyapatite, to act as a scaffold for posterolateral spinal fusion in a rat model. METHODS: Using a rat posterolateral spine fusion model, the experimental study comprised 3 groups. Group 1 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite only. Group 2 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite containing 1 x 10(6)/ 60 microliter rat of BMDMSCs. Group 3 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite containing 1 x 10(6)/ 60 microliter of rat BMDMSCs and FGF-4 1 microgram to induce the bony differentiation of the BMDMSCs. Rats were assessed using radiographs obtained at 4, 6, and 8 weeks postoperatively. After sacrifice, spines were explanted and assessed by manual palpation, high-resolution microcomputerized tomography, and histological analysis. RESULTS: Radiographic, high-resolution microcomputerized tomographic, and manual palpation revealed spinal fusion in five rats (83%) in Group 2 at 8 weeks. However, in Group 1, three (60%) rats developed fusion at L4-L5 by radiography and two (40%) by manual palpation in radiographic examination. In addition, in Group 3, bone fusion was observed in only 50% of rats by manual palpation and radiographic examination at this time. CONCLUSION: The present study demonstrates that 0.08 gram of hydroxyapatite with 1 x 10(6)/ 60 microliter rat of BMDMSCs induced bone fusion. FGF-4, added to differentiate primitive 1 x 10(6)/ 60 microliter rat of BMDMSCs did not induce fusion. Based on histologic data, FGF-4 appears to induce fibrotic change rather than differentiation to bone by 1 x 10(6)/ 60 microliter rat of BMDMSCs.