Biomechanical comparison of two new atlantoaxial fixation techniques with C1–2 transarticular screw–graft fixation

2006 ◽  
Vol 5 (4) ◽  
pp. 336-342 ◽  
Author(s):  
Roger Härtl ◽  
Robert H. Chamberlain ◽  
Mary S. Fifield ◽  
Dean Chou ◽  
Volker K. H. Sonntag ◽  
...  
Keyword(s):  
Gold Standard ◽  
Screw Fixation ◽  
Axial Rotation ◽  
Lateral Mass ◽  
Lateral Bending ◽  
Transarticular Screw ◽  
New Techniques ◽  
Transarticular Screw Fixation ◽  
Atlantoaxial Fixation ◽  
Lateral Mass Screws

Object Two new techniques for atlantoaxial fixation have been recently described. In one technique, C-2 intra-laminar screws are connected with C-1 lateral mass screws; in the second, C-1 and C-3 lateral mass screws are interconnected and C-2 is wired sublaminarly. Both techniques include a C1–2 interspinous graft. The authors compared these techniques with the gold-standard, interspinous graft–augmented C1–2 transarticular screw fixation and with a control C1–2 interspinous graft fixation procedure alone. Methods In six human cadaveric occiput–C4 specimens, nonconstraining 1.5-Nm pure moments were applied to induce flexion, extension, lateral bending, and axial rotation during which three-dimensional angular motion was measured optoelectronically. Each specimen was tested in the normal state, with graft alone (after odontoidectomy), and then in varying order after applying each construct with a rewired graft. All three constructs allowed significantly less angular motion at the C1–2 junction than the wired interspinous graft alone during lateral bending and axial rotation (p < 0.01, paired Student t-test) but not during flexion or extension. Transarticular screw fixation with an interspinous graft allowed less motion at the atlantoaxial junction than the two new constructs in several conditions. Differences were greater between the transarticular screw construct and the intralaminar screw construct than between the transarticular screw construct and the C1–3 lateral mass screw construct. During lateral bending and axial rotation, the C1–3 construct allowed less motion at the atlantoaxial junction than the intralaminar screw construct. Conclusions Biomechanically, the gold-standard C1–2 transarticular screw fixation outperformed the two new techniques during lateral bending and axial rotation. Wiring C-2 to C1–3 rods provided greater stability than C1–2 laminar screws, but it sacrificed C2–3 mobility. It is unknown whether the small differences observed biomechanically would lead to clinically relevant differences in fusion rates.

Biomechanical Comparison of Four C1 to C2 Rigid Fixative Techniques: Anterior Transarticular, Posterior Transarticular, C1 to C2 Pedicle, and C1 to C2 Intralaminar Screws

Neurosurgery ◽  
2006 ◽  
Vol 58 (3) ◽  
pp. 516-521 ◽  
Author(s):  
Samir B. Lapsiwala ◽  
Paul A. Anderson ◽  
Ashish Oza ◽  
Daniel K. Resnick
Keyword(s):  
Pedicle Screw ◽  
Screw Fixation ◽  
Axial Rotation ◽  
Lateral Bending ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Flexion Extension ◽  
Fixation Techniques ◽  
Biomechanical Comparison ◽  
Cable Fixation

Abstract OBJECTIVE: We performed a biomechanical comparison of several C1 to C2 fixation techniques including crossed laminar (intralaminar) screw fixation, anterior C1 to C2 transarticular screw fixation, C1 to 2 pedicle screw fixation, and posterior C1 to C2 transarticular screw fixation. METHODS: Eight cadaveric cervical spines were tested intact and after dens fracture. Four different C1 to C2 screw fixation techniques were tested. Posterior transarticular and pedicle screw constructs were tested twice, once with supplemental sublaminar cables and once without cables. The specimens were tested in three modes of loading: flexion-extension, lateral bending, and axial rotation. All tests were performed in load and torque control. Pure bending moments of 2 nm were applied in flexion-extension and lateral bending, whereas a 1 nm moment was applied in axial rotation. Linear displacements were recorded from extensometers rigidly affixed to the C1 and C2 vertebrae. Linear displacements were reduced to angular displacements using trigonometry. RESULTS: Adding cable fixation results in a stiffer construct for posterior transarticular screws. The addition of cables did not affect the stiffness of C1 to C2 pedicle screw constructs. There were no significant differences in stiffness between anterior and posterior transarticular screw techniques, unless cable fixation was added to the posterior construct. All three posterior screw constructs with supplemental cable fixation provide equal stiffness with regard to flexion-extension and axial rotation. C1 lateral mass-C2 intralaminar screw fixation restored resistance to lateral bending but not to the same degree as the other screw fixation techniques. CONCLUSION: All four screw fixation techniques limit motion at the C1 to 2 articulation. The addition of cable fixation improves resistance to flexion and extension for posterior transarticular screw fixation.

Subaxial sagittal alignment and adjacent-segment degeneration after atlantoaxial fixation performed using C-1 lateral mass and C-2 pedicle screws or transarticular screws

2010 ◽  
Vol 13 (4) ◽  
pp. 443-450 ◽  
Author(s):  
Go Yoshida ◽  
Mituhiro Kamiya ◽  
Hisatake Yoshihara ◽  
Tokumi Kanemura ◽  
Fumihiko Kato ◽  
...  
Keyword(s):  
Sagittal Alignment ◽  
Screw Fixation ◽  
Adjacent Segment ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Significant Difference ◽  
Atlantoaxial Fixation ◽  
The Mean ◽  
The Difference

Object The purpose of this study was to evaluate the effect of a fixed atlantoaxial angle on subaxial sagittal alignment, and that of atlantoaxial fixation on adjacent-segment motion and degeneration. Methods The authors retrospectively reviewed 65 patients in whom atlantoaxial instability was treated with atlantoaxial fixation by C-1 lateral mass and C-2 pedicle screw fixation (30 patients, Goel-Harms [GH] group) or a combination of transarticular screw fixation and posterior wiring (35 patients, Magerl-Brooks [MB] group). Angles of Oc–C1, C1–2, C2–3, and C2–7 were determined based on an upright lateral radiograph in flexion, neutral, and extension positions. The range of motion (ROM) at Oc–C1 and C2–3 was also determined. All patients were examined before and 2 years after surgery. Results The mean preoperative atlantoaxial angles in the GH and MB groups were 20.9 ± 8.3° and 18.3 ± 7.2°, respectively, and the mean postoperative atlantoaxial angles in the same groups were 23.5 ± 5.6° and 29.7 ± 6.3°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The mean preoperative angles of C2–7 in the GH and MB groups were 15.4 ± 7.8° and 13.7 ± 9.5°, respectively, and after surgery, the angles were 11.8 ± 12° and 2.48 ± 12°, respectively, with a statistically significant difference between the 2 groups (p < 0.05). The postoperative angle of C1–2 showed a negative correlation with the extent of change observed in the C2–7 angle preand postoperatively in each of these 2 surgical procedures. The Oc–C1 ROM increased after surgery in both groups, but the difference was not statistically significant (p = 0.38). The C2–3 ROM decreased after surgery in both groups, and the difference was statistically significant (p < 0.05). Conclusions Atlantoaxial fixation in a hyperlordotic position produced kyphotic sagittal alignment after surgery in both GH and MB groups. Reduction of the atlantoaxial joint can be easily achieved through screw fixation at an optimal angle, thereby ameliorating the risk for subsequent subaxial kyphosis. Degeneration of lower adjacent segments appeared to be less with this procedure compared with using a combination of transarticular screw fixation and posterior wiring.

Biomechanical comparison of occipitoatlantal screw fixation techniques

2008 ◽  
Vol 8 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Nicholas C. Bambakidis ◽  
Iman Feiz-Erfan ◽  
Eric M. Horn ◽  
L. Fernando Gonzalez ◽  
Seungwon Baek ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Axial Rotation ◽  
Segmental Motion ◽  
Lateral Mass ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Improved Stability ◽  
Fixation Techniques ◽  
Structural Graft ◽  
Lateral Mass Screws

Object The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]–C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. Methods Seven human cadaveric specimens received transarticular screws and 7 received occipital keel–C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. Results Application of Oc–C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel–C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p < 0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. Conclusions Assuming the presence of mild C1–2 instability, Oc–C1 transarticular screws and occipital keel–C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.

Atlantoaxial stabilization with the use of C1–3 lateral mass screw fixation

2006 ◽  
Vol 5 (2) ◽  
pp. 172-177 ◽  
Author(s):  
Eric M. Horn ◽  
Jonathan S. Hott ◽  
Randall W. Porter ◽  
Nicholas Theodore ◽  
Stephen M. Papadopoulos ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Intraoperative Complications ◽  
Atlantoaxial Instability ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Cervical Orthosis ◽  
Atlantoaxial Stabilization

✓ Atlantoaxial stabilization has evolved from simple posterior wiring to transarticular screw fixation. In some patients, however, the course of the vertebral artery (VA) through the axis varies, and therefore transarticular screw placement is not always feasible. For these patients, the authors have developed a novel method of atlantoaxial stabilization that does not require axial screws. In this paper, they describe the use of this technique in the first 10 cases. Ten consecutive patients underwent the combined C1–3 lateral mass–sublaminar axis cable fixation technique. The mean age of the patients was 62.6 years (range 23–84 years). There were six men and four women. Eight patients were treated after traumatic atlantoaxial instability developed (four had remote trauma and previous nonunion), whereas in the other two atlantoaxial instability was caused by arthritic degeneration. All had VA anatomy unsuitable to traditional transarticular screw fixation. There were no intraoperative complications in any of the patients. Postoperative computed tomography studies demonstrated excellent screw positioning in each patient. Nine patients were treated postoperatively with the aid of a rigid cervical orthosis. The remaining patient was treated using a halo fixation device. One patient died of respiratory failure 2 months after surgery. Follow-up data (mean follow-up duration 13.1 months) were available for seven of the remaining nine patients and demonstrated a stable construct with fusion in each patient. The authors present an effective alternative method in which C1–3 lateral mass screw fixation is used to treat patients with unfavorable anatomy for atlantoaxial transarticular screw fixation. In this series of 10 patients, the method was a safe and effective way to provide stabilization in these anatomically difficult patients.

Biomechanical Comparison of Two Stabilization Techniques of the Atlantoaxial Joints: Transarticular Screw Fixation versus Screw and Rod Fixation

2005 ◽  
Vol 56 (suppl_1) ◽  
pp. ONS-151-ONS-159 ◽  
Author(s):  
Hiroshi Kuroki ◽  
Setti S. Rengachary ◽  
Vijay K. Goel ◽  
Scott A. Holekamp ◽  
Ville Pitkänen ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Axial Rotation ◽  
Biomechanical Stability ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Sufficient Stability ◽  
Degree Of Stability ◽  
Angular Displacements ◽  
Biomechanical Comparison ◽  
Flexion And Extension

Abstract OBJECTIVE: To compare the biomechanical stability imparted to the C1 and C2 vertebrae by either transarticular screw fixation (TSF) or screw and rod fixation (SRF) techniques in a cadaver model. METHODS: Ten fresh ligamentous human cervical spine specimens were harvested from cadavers. The specimens were tested sequentially in the intact state, after injury and stabilization (unilateral left side and bilateral), and after fatiguing to 5000 cycles (0.5 Hz) at ±1.0 N·m of flexion and extension. The specimens were stabilized by use of TSF in 5 spines or SRF in the other 5 spines. The data were converted to angular displacements, and the stabilized cases were compared with intact states for evaluating the efficacies of the two techniques in stabilizing the C1–C2 segments. RESULTS: In the TSF group, the unilateral fixation using one screw imparted a significant stability in only the axial rotation mode. The unilateral procedure in the SRF group was effective in stabilization in all modes except in extension. The bilateral procedure in both of the groups was effective across the C1–C2 segment. However, the SRF group afforded higher stability than the corresponding TSF group in the flexion and extension modes. The degree of stability did not change after fatigue compared with the prefatigue data. CONCLUSION: In general, a surgeon should undertake a bilateral fixation to achieve sufficient stability across the atlantoaxial complex, and either technique will provide satisfactory results, although the SRF technique may be better in the flexion and extension modes. One should use the SRF procedure while trying to achieve stability with a unilateral system.

Biomechanical comparison of C1–2 posterior fixation techniques

2005 ◽  
Vol 2 (2) ◽  
pp. 175-181 ◽  
Author(s):  
Jonathan S. Hott ◽  
James J. Lynch ◽  
Robert H. Chamberlain ◽  
Volker K. H. Sonntag ◽  
Neil R. Crawford
Keyword(s):  
Screw Fixation ◽  
Graft Fixation ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Content Type ◽  
Transarticular Screw Fixation ◽  
Significant Difference ◽  
Pars Interarticularis ◽  
Flexion And Extension ◽  
Fine Print

Object. In a nondestructive, repeated-measures in vitro flexibility experiment, the authors compared the acute stability of C1–2 after placement of C-1 lateral mass and C-2 pars interarticularis (LC1—PC2) instrumentation with that of C1–2 transarticular screw fixation. Methods. The effect of C-1 laminectomy and C1–2 interspinous cable/graft fixation on LC1—PC2 stability was studied. Screw pullout strengths were also compared. Seven human cadaveric occiput—C3 specimens were loaded nondestructively with pure moments while measuring nonconstrained atlantoaxial motion. Specimens were tested with graft alone, LC1—PC2 alone, LC1—PC2 combined with C-1 laminectomy, and graft-augmented LC1—PC2. Interspinous cable/graft fixation significantly enhanced LC1—PC2 stability during extension. After C-1 laminectomy, the LC1—PC2 construct allowed increased motion during flexion and extension. There was no significant difference in lax zone or range of motion between LC1—PC2 fixation and transarticular screw fixation, but graft-assisted transarticular screws yielded a significantly smaller stiff zone during extension. The difference in pullout resistance between C-1 lateral mass screws and C-2 pars interarticularis screws was insignificant. The LC1—PC2 region restricted motion to within the normal range during all loading modes. Atlantal laminectomy reduced LC1—PC2 stability during flexion and extension. Conclusions. The instrumentation-augmented LC1—PC2 construct performed biomechanically similarly to the C1–2 transarticular screw fixation. The LC1—PC2 construct resisted flexion, lateral bending, and axial rotation well. The weakness of the LC1—PC2 fixation in resisting extension can be overcome by adding an interspinous graft to the construct.

Radiological and anatomical evaluation of the atlantoaxial transarticular screw fixation technique

1997 ◽  
Vol 86 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Ali Abou Madawi ◽  
Adrian T. H. Casey ◽  
Guirish A. Solanki ◽  
Gerald Tuite ◽  
Robert Veres ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Screw Placement ◽  
Transoral Surgery ◽  
Spinal Instability ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Content Type ◽  
Posterior Surgery ◽  
Transarticular Screw Fixation ◽  
Fine Print

✓ Sixty-one patients treated with C1–2 transarticular screw fixation for spinal instability participated in a detailed clinical and radiological study to determine outcome and clarify potential hazards. The most common condition was rheumatoid arthritis (37 patients) followed by traumatic instability (15 patients). Twenty-one of these patients (onethird) underwent either surgical revision for a previously failed posterior fusion technique or a combined anteroposterior procedure. Eleven patients underwent transoral odontoidectomy and excision of the arch of C-1 prior to posterior surgery. No patient died, but there were five vertebral artery (VA) injuries and one temporary cranial nerve palsy. Screw malposition (14% of placements) was comparable to another large series reported by Grob, et al. There were five broken screws, and all were associated with incorrect placement. Anatomical measurements were made on 25 axis bones. In 20% the VA groove on one side was large enough to reduce the width of the C-2 pedicle, thus preventing the safe passage of a 3.5-mm diameter screw. In addition to the obvious dangers in patients with damaged or deficient atlantoaxial lateral mass, the following risk factors were identified in this series: 1) incomplete reduction prior to screw placement, accounting for two-thirds of screw complications and all five VA injuries; 2) previous transoral surgery with removal of the anterior tubercle or the arch of the atlas, thus obliterating an important fluoroscopic landmark; and 3) failure to appreciate the size of the VA in the axis pedicle and lateral mass. A low trajectory with screw placement below the atlas tubercle was found in patients with VA laceration. The technique that was associated with an 87% fusion rate requires detailed computerized tomography scanning prior to surgery, very careful attention to local anatomy, and nearly complete atlantoaxial reduction during surgery.

scholarly journals Biomechanical evaluation of two alternative techniques to the Goel-Harms technique for atlantoaxial fixation: C1 lateral mass–C2 bicortical translaminar screw fixation and C1 lateral mass–C2/3 transarticular screw fixation

2020 ◽  
Vol 32 (5) ◽  
pp. 682-688
Author(s):  
Yue-Qi Du ◽  
Teng Li ◽  
Chao Ma ◽  
Guang-Yu Qiao ◽  
Yi-Heng Yin ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Industrial Robot ◽  
Rotational Stability ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Flexion Extension ◽  
Translaminar Screw ◽  
Atlantoaxial Fixation ◽  
Alternative Techniques ◽  
Harms Technique

OBJECTIVEThe authors conducted a study to investigate the biomechanical feasibility and stability of C1 lateral mass–C2 bicortical translaminar screw (C1LM-C2TL) fixation, C1 lateral mass–C2/3 transarticular screw (C1LM-C2/3TA) fixation, and C1LM-C2/3TA fixation with transverse cross-links (C1LM-C2/3TACL) as alternative techniques to the Goel-Harms technique (C1 lateral mass–C2 pedicle screw [C1LM-C2PS] fixation) for atlantoaxial fixation.METHODSEight human cadaveric cervical spines (occiput–C7) were tested using an industrial robot. Pure moments that were a maximum of 1.5 Nm were applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). The specimens were first tested in the intact state and followed by destabilization (a type II odontoid fracture) and fixation as follows: C1LM-C2PS, C1LM-C2TL, C1LM-C2/3TA, and C1LM-C2/3TACL. For each condition, the authors evaluated the range of motion and neutral zone across C1 and C2 in all directions.RESULTSCompared with the intact spine, each instrumented spine significantly increased in stability at the C1–2 segment. C1LM-C2TL fixation demonstrated similar stability in FE and LB and greater stability in AR than C1LM-C2PS fixation. C1LM-C2/3TA fixation was equivalent in LB and superior in FE to those of C1LM-C2PS and C1LM-C2TL fixation. During AR, the C1LM-C2/3TA–instrumented spine failed to maintain segmental stability. After adding a cross-link, the rotational stability was significantly increased in the C1LM-C2/3TACL–instrumented spine compared with the C1LM-C2/3TA–instrumented spine. Although inferior to C1LM-C2TL fixation, the C1LM-C2/3TACL–instrumented spine showed equivalent rotational stability to the C1LM-C2PS–instrumented spine.CONCLUSIONSOn the basis of our biomechanical study, C1LM-C2TL and C1LM-C2/3TACL fixation resulted in satisfactory atlantoaxial stabilization compared with C1LM-C2PS. Therefore, the authors believe that the C1LM-C2TL and C1LM-C2/3TACL fixation may serve as alternative procedures when the Goel-Harms technique (C1LM-C2PS) is not feasible due to anatomical constraints.

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