Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level

Hallager, Dennis Winge; Gehrchen, Martin; Dahl, Benny; Harris, Jonathan; Gudipally, Manasa; Jenkins, Sean; Wu, Ai-Min; Bucklen, Brandon

doi:10.1097/brs.0000000000001282

Cited by 75 publications

(71 citation statements)

References 27 publications

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“…The highest rod fracture rates reported in literature are with the classic PSO techniques, and the lowest reported are those with satellite rods and interbody supplementation. [ 14 15 2 17 ] This was consistent with the results of our FEA study. Rod failure is thought to result from stress-fatigue due to the severe angulation required to maintain a great degree of lordosis.…”

Section: Discussionsupporting

confidence: 92%

“…[ 13 26 27 ] Pedicle screw fixation two levels above and below the interbody has been shown to provide adequate biomechanical stabilization. [ 14 ] Traditional PSOs have been supplemented with a variety of construct techniques to help improve their biomechanical stability and minimize rod fracture. One such technique is the use of cobalt chrome rods over traditional titanium rods.…”

Section: Discussionmentioning

confidence: 99%

“…Another technique is the use of accessory rods or satellite rods that bridge across the PSO. [ 14 15 16 28 ] Lastly, some surgeons have supplemented with an interbody cage at the superior disc space of the PSO to create a longer fusion construct and lessen the long-term burden on the rods. [ 11 ]…”

Section: Discussionmentioning

confidence: 99%

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Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

et al. 2017

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Background:In an effort to minimize rod fractures and nonunion in pedicle subtraction osteotomy (PSO) constructs, surgeons have adopted multirod constructs and interbody cages. Anterior column realignment (ACR) with posterior column osteotomies is a minimally invasive alternative to PSO in sagittal balance correction, however, there is a paucity of evidence with respect to rod survival.Methods:Three-dimensional (3D) finite-element-model of a T12-sacrum spine segment was used to compare a 25° PSO at L3 and an ACR with a posterior column osteotomy and 30° hyperlordotic interbody cage at L3–4. The amount of overall T12–S1 lordosis correction was the same for each condition. Each simulation included cobalt chromium alloy primary rods with: (1) PSO; (2) PSO with an interbody cage (IB) at L2–3 (PSO+IB); (3) PSO with accessory (A) rods and IB at L2–3 (PSO+IB+A); (4) PSO with satellite (S) rods and IB at L2–3 (PSO+IB+2S); (5) ACR; 6) ACR with satellite rods (ACR + 2S). A 400 N follower preload was simulated for each condition.Results:PSO condition had the largest rod stress of 286 MPa in flexion. Adding interbody support reduced the rod stress by 15%. The 4-rod constructs further reduced rod stress, with the satellite rod condition facilitating the largest reduction. The rod stress in the ACR+2S was equivalent to the PSO+2S, with 50% reduction in rod stress.Conclusion:The rod stress with an ACR was comparable to a PSO coupled with interbody support. These results suggest an ACR is a viable MIS alternative to a PSO without the need for a large posterior osteotomy.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

et al. 2017

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“…Of course, many researchers [14,15] have found from measurements of dry bone that all vertebral diameters vary with race, height, sex, and age. Therefore, to determine ideal vertebral screw placement parameters, CT scanning should be performed for the patient’s affected segments, and measurements and preoperative simulations should be conducted using software with powerful post-processing functions, such as Mimics, to develop an individualized surgical plan.…”

Section: Discussionmentioning

confidence: 99%

Digital Anatomical Measurement for Anterolateral Fixation of Middle and Lower Thoracic Vertebrae

Zhang

et al. 2016

Med Sci Monit

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BackgroundThe key to its successful application is to determine the best entry point for the vertebral screw(s). This study aimed to provide a reference for clinical anterolateral fixation through digital measurement of computed tomography (CT) data to identify relevant anatomical positions in the middle and lower thoracic vertebrae (T4–T12) of 30 adults.Material/MethodsWe performed digital measurement of anatomical positions in the middle and lower thoracic vertebrae (T4–T12) of 30 adults. Abbreviations: Left height of vertebral body, LHV; Right height of vertebral body, RHV; Anterior height of vertebral body, AHV; Middle height of vertebral body, MHV; Posterior height of vertebral body, PHV; Superior sagittal diameter of vertebral body, SSDV; Superior transverse diameter of vertebral body, STDV; inferior sagittal diameter of vertebral body, ISDV; Inferior transverse diameter of vertebral body, ITDV; (1) Left (right) height of vertebral body, [L(R)HV]; Anterior (middle, posterior) height of vertebral body [A(M,P)HV]; Superior (inferior) sagittal diameter of vertebral body, [S(I)SDV]; Superior (inferior) transverse diameter of vertebral body, [S(I)TDV].ResultsThe transverse diameters of vertebral bodies were always larger than the sagittal diameter for 3~4 mm. The distance between 2 vertebrae (interval of 1 vertebra) range were (52–56) mm for T4–T7 and (44–48) mm for T8–T12, and the surgeons could collate these data to choose a suitable stick length.ConclusionsBone graft should prune into laterigrade cuboid, it can recover A-P and bilateral physiological functions load, and the height of the vertebral body increased from T4 to T12.

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“…По данным литературы, такая фиксация при выполнении PSO связана с большой частотой осложнений -до 37% (из них до 87% на уровне PSO), в первую очередь -переломов элементов металлоконструкции и последующим формированием псевдоартроза в зоне остеотомии [15,[19][20][21][22][23][24][25][26][27]. Разными авторами предпринимались попытки предотвратить развитие осложнений за счет применения стержней из более прочного металла и дополнительных стержней, проведения дополнительного межтелового спондилодеза и сведения к минимуму угла деформации стержней в зоне остеотомии [12,[28][29][30][31][32].…”

Section: Introductionunclassified

Еffectiveness of Four-Rod Fixation for Pedicle Subtraction Spinal Osteotomy

Пантелеев

Mironov

Bukhtin

et al. 2018

Traumatology and Orthopedics of Russia

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Introduction.Pedicle subtraction osteotomy (PSO) provides for significant segmental correction of the sagittalbalance of the spine. At the same time, the technique is associated with a high risk of complications, with rod fracture at the osteotomy site being the most common. The purposeof this study — to assess the effectiveness of four-rod fixation compared to literature data on standardtwo-rod fixation in patients undergoing PSO. Materials and Methods.The study is a retrospective analysis of 47 consecutive patients with rigid spinaldeformities, who underwent pedicle subtraction osteotomy at the lumbar level. The average age of the patients (33 females and 14 males) was 59.7 years. In all cases spinal fixation carried out using a four-rod construct with additional short rods at the osteotomy site. The minimal postoperative follow-up was 2 years. A detailed analysis of the radiographic data was carried out with calculation of the global sagittal balance and spinopelvic parameters. A detailed assessment of complications in the early and late postoperative periods was also performed. After an exhaustive review of literature, a comparative analysis was made of the four-rod fixation technique with current literature data on the frequency of complications (in particular, rod fractures in the osteotomy zone) after two-rod fixation. Results.In all cases the osteotomy was performed at one level, most often at L3 (49%). The average length offixation was 9.8 segments. The average angle of segmental correction was 27.1°. In most cases, it was possible to achieve adequate correction of spinopelvic parameters. Among complications, bone resorption around screws was most prevalent (23.4% of cases). Proximal junctional kyphosis occurred in 12.8% of cases, neurologic deficit — in 14.9% of cases, infectious complications — in 10.6% cases. Asymptomatic pseudarthrosis, confirmed by CT data, was observed in 12.8% of patients. Rod fracture at the PSO site and adjacent segments was not observed in any of the cases. Rod fractures of other localization were observed in 10.6% of patients. Conclusion. According to the literature, the frequency of rod fractures at the osteotomy site is the most frequentcomplication of PSO. The results of this study showed that four-rod fixation in PSO significantly reduces the incidence of pseudarthrosis and rod fracture rate in the long-term follow-up and provides greater control over the process of osteotomy closure.

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Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level

Abstract: N/A.

Cited by 75 publications

References 27 publications

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

Digital Anatomical Measurement for Anterolateral Fixation of Middle and Lower Thoracic Vertebrae

Еffectiveness of Four-Rod Fixation for Pedicle Subtraction Spinal Osteotomy

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