Minimally Invasive Microscope-Assisted Stand-Alone Transarticular Screw Fixation without Gallie Supplementation in the Management of Mobile Atlantoaxial Instability

Abstract

Study Design Retrospective study.PurposeTo evaluate the clinico-radiological efficacy of stand-alone minimally invasive transarticular screw (MIS-TAS) fixation without supplemental Gallie fixation in the management of mobile C1–C2 instability.Overview of LiteratureData evaluating the efficacy and feasibility of MIS-TAS in the literature is scanty.MethodsPatients with mobile atlantoaxial instability and >2 years follow-up were included and managed by stand-alone TAS fixation using the Magerl technique and morselized allograft without additional fixation. Patient demographics and intra-operative parameters were noted. Clinical parameters (Visual Analog Scale [VAS] and Oswestry Disability Index [ODI]), neurology (modified Japanese Orthopaedic Association [mJOA]), and radiological factors (anterior atlanto-dens interval and space available for cord) were evaluated pre and postoperatively. Computed tomography (CT) was performed in patients who did not show interspinous fusion on X-ray at 1 year, to verify intra-articular fusion. Statistical analysis was performed using IBM SPSS ver. 20.0 (IBM Corp., Armonk, NY, USA); the Student t-test and analysis of variance were used to assess statistical significance (p <0.05).ResultsA total of 82 consecutive cases (three males, one female; mean age, 36.26±5.78 years) were evaluated. In total, 163 TASs were placed. Significant improvement was noticed in clinical (mean preoperative VAS=7.2±2.19, postoperative VAS=3.3±1.12; mean preoperative ODI=78.3±4.83, postoperative ODI=34.05±3.26) and neurological features (mean preoperative mJOA=14.73±2.68, postoperative mJOA=17.5±2.21). Radiological evidence of fusion was noted in 97.5% cases at final follow-up. Seventeen patients were found to have no interspinous fusions upon X-rays, but CT revealed facet fusion in all patients except in two. Inadvertent vertebral artery injury was noted in three cases.ConclusionsStand-alone TAS fixation with morselized allograft provides excellent radiological and clinical outcomes. The addition of a supplementary tension band and structural graft are not essential. This provides the opportunity to avoid the complications associated with graft harvesting and wiring.

The limitations of fully threaded screws in isolated percutaneous transarticular screw fixation of C1/C2

“…For a patient population as mentioned above, IPTSFC1/C2 may represent a safe surgical treatment option with the smallest possible surgical trauma to enable rapid remobilization and dehospitalization. Our data agree with those found in the literature on this subject 12 – 14 . The advantage of percutaneous transarticular screw fixation over the classic transarticular screw fixation of C1 and C2 as an open approach is the significantly lower surgical invasiveness 10 .…”

“…The IPTSFC1/C2 as another minimally invasive therapy option available, seems to be quite worthwhile. Furthermore, it has been shown that minimally invasive percutaneous transarticular screw fixation of C1/C2 combined with a mini open technique to establish spinal fusion resulted in fusion rates of 97.5 to 98% 12 , 13 . These rates were similar to spinal fusion rates achieved with classic transarticular screw fixation with dorsal bone grafting between C1 and C2 3 , 17 .…”

“…The technique described by Magerl et al has frequently been modified and techniques for performing the procedure in a minimally invasive manner have been developed 10 – 14 . In some of the minimally invasive procedures, in addition to percutaneous screw fixation, dorsal spondylodesis is established in a mini open procedure 10 , 12 , 14 . However, some authors have demonstrated isolated percutaneous techniques without an additional spinal fusion 11 , 14 .…”

Learning Curve of Minimally Invasive C1-C2 Trans-articular Screw Fixation (MIS-TAS): Over A Period of Five Years

“…The reason we arrived at this hypothesis was because of multiple literature reporting that a sustained excellent outcome is possible despite wire failure. In our previous study we found a fusion rate of 97.5% without the use of wires 10) . Matsumoto et al and Ito et al in their articles mentioned a fusion rate of 95% and 100% respectively despite their cases having confirmation of wire loosening 4,6) .…”