Mechanics of Interbody Spinal Fusion

Closkey, Robert F.; Parsons, J. R.; Lee, C. K.; Blacksin, Marcia F.; Zimmerman, Mark C.

doi:10.1097/00007632-199306150-00010

Cited by 172 publications

(33 citation statements)

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“…5,9 Posterior approaches for interbody fusion (TLIF and PLIF) use 1 or 2 small intervertebral cages, typically covering between 13% and 25% of the endplate, respectively, and rarely covering the stronger posterior and lateral borders of the apophyseal ring. 9,19 Although interbody cage subsidence is common with posterior approaches (up to 22% 25,26 ), it is less clinically and radiographically relevant, because direct decompressions are used and alignment is corrected by compressive posterior instrumentation.…”

Section: Discussionmentioning

confidence: 99%

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

Malham

Parker²,

Blecher

et al. 2015

SPI

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OBJECT Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF. METHODS A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores. RESULTS Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049). CONCLUSIONS The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

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Section: Discussionmentioning

confidence: 99%

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

Malham

Parker²,

Blecher

et al. 2015

SPI

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“…Deeply concave or other forms of irregularly shaped endplates as well as a small cage size reduce the contact area between the cage and the bone surface. The smaller the surface contact area, the higher the stress on the endplate [7,[10][11][12]18]. A cadaveric study demonstrated significant higher failure loads when the cages covered 40% of the endplate surface area opposed to 20% [23].…”

Section: Discussionmentioning

confidence: 99%

The influence of cage positioning and cage type on cage migration and fusion rates in patients with monosegmental posterior lumbar interbody fusion and posterior fixation

et al. 2009

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In posterior lumbar interbody fusion, cage migrations and lower fusion rates compared to autologous bone graft used in the anterior lumbar interbody fusion procedure are documented. Anatomical and biomechanical data have shown that the cage positioning and cage type seem to play an important role. Therefore, the aim of the present study was to evaluate the impact of cage positioning and cage type on cage migration and fusion. We created a grid system for the endplates to analyze different cage positions. To analyze the influence of the cage type, we compared ''closed'' box titanium cages with ''open'' box titanium cages. This study included 40 patients with 80 implanted cages. After pedicle screw fixation, 23 patients were treated with a ''closed box'' cage and 17 patients with an ''open box'' cage. The follow-up period averaged 25 months. Twenty cages (25%) showed a migration into one vertebral endplate of \3 mm and four cages (5%) showed a migration of C3 mm. Cage migration was highest in the medio-medial position (84.6%), followed by the postero-lateral (42.9%), and the postero-medial (16%) cage position. Closed box cages had a significantly higher migration rate than open box cages, but fusion rates did not differ. In conclusion, cage positioning and cage type influence cage migration. The medio-medial cage position showed the highest migration rate. Regarding the cage type, open box cages seem to be associated with lower migration rates compared to closed box cages. However, the cage type did not influence bone fusion.

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“…Approximately, 30% of endplate to endplate bridging bone surface was required to consider the interbody fusion to be radiologically fused [8]. For posterior and posterolateral fusion mass, a modification of Christensen's classification was used [7] (Table 2).…”

Section: Tlif Techniquementioning

confidence: 99%

Clinical and radiological outcome of anterior–posterior fusion versus transforaminal lumbar interbody fusion for symptomatic disc degeneration: a retrospective comparative study of 133 patients

Faúndez¹,

Schwender

Safriel³

et al. 2009

Eur Spine J

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Abundant data are available for direct anterior/ posterior spine fusion (APF) and some for transforaminal lumbar interbody fusion (TLIF), but only few studies from one institution compares the two techniques. One-hundred and thirty-three patients were retrospectively analyzed, 68 having APF and 65 having TLIF. All patients had symptomatic disc degeneration of the lumbar spine. Only those with one or two-level surgeries were included. Clinical chart and radiologic reviews were done, fusion solidity assessed, and functional outcomes determined by pre-and postoperative SF-36 and postoperative Oswestry Disability Index (ODI), and a satisfaction questionnaire. The minimum follow-up was 24 months. The mean operating room time and hospital length of stay were less in the TLIF group. The blood loss was slightly less in the TLIF group (409 vs. 480 cc.). Intra-operative complications were higher in the APF group, mostly due to vein lacerations in the anterior retroperitoneal approach. Postoperative complications were higher in the TLIF group due to graft material extruding against the nerve root or wound drainage. The pseudarthrosis rate was statistically equal (APF 17.6% and TLIF 23.1%) and was higher than most published reports. Significant improvements were noted in both groups for the SF-36 questionnaires. The mean ODI scores at follow-up were 33.5 for the APF and 39.5 for the TLIF group. The patient satisfaction rate was equal for the two groups.

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Mechanics of Interbody Spinal Fusion

Cited by 172 publications

References 0 publications

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

The influence of cage positioning and cage type on cage migration and fusion rates in patients with monosegmental posterior lumbar interbody fusion and posterior fixation

Clinical and radiological outcome of anterior–posterior fusion versus transforaminal lumbar interbody fusion for symptomatic disc degeneration: a retrospective comparative study of 133 patients

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