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. 2024 Aug 30;18(S1):S16-S23.
doi: 10.14444/8637.

Predictability in Achieving Target Intervertebral Lordosis Using Personalized Interbody Implants

Saeed S Sadrameli  1 , Donald J Blaskiewicz  2 , Jahangir Asghar  3 , Christopher P Ames  4 , Gregory M Mundis  5 , Joseph A Osorio  6 , Justin S Smith  7 , Chun-Po Yen  7 , Sigurd H Berven  8 , Ashvin I Patel  9 , Michele Temple-Wong  10 , Rodrigo J Nicolau  10 , Roland S Kent  11
Affiliations

Predictability in Achieving Target Intervertebral Lordosis Using Personalized Interbody Implants

Saeed S Sadrameli et al. Int J Spine Surg. .

Abstract

Background: Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment. Recently, personalized spine surgery has witnessed significant advancements, including 3D-printed personalized interbody implants, which are customized to the surgeon's treatment and alignment goals. This study evaluates the reliability of 3D-printed patient-specific interbody implants to achieve the planned postoperative intervertebral alignment.

Methods: This is a retrospective study of 217 patients with spinal deformity or degenerative conditions. Patients were included if they received 3D-printed personalized interbody implants. The desired intervertebral lordosis (IVL) angle was prescribed into the device design for each personalized interbody (IVL goal). Standing postoperative radiographs were measured, and the IVL offset was calculated as IVL achieved minus IVL goal.

Results: In this patient population, 365 personalized interbodies were implanted, including 145 anterior lumbar interbody fusions (ALIFs), 99 lateral lumbar interbody fusions (LLIFs), and 121 transforaminal lumbar interbody fusions. Among the 365 treated levels, IVL offset was 1.1° ± 4.4° (mean ± SD). IVL was achieved within 5° of the plan in 299 levels (81.9%). IVL offset depended on the approach of the lumbar interbody fusion and was achieved within 5° for 85.9% of LLIF, 82.6% of transforaminal lumbar interbody fusions and 78.6% of ALIFs. Ten levels (2.7%) missed the planned IVL by >10°. ALIF and LLIF levels in which the plan was missed by more than 5° tended to be overcorrected.

Conclusions: This study supports the use of 3D-printed personalized interbody implants to achieve planned sagittal intervertebral alignment.

Clinical relevance: Personalized interbody implants can consistently achieve IVL goals and potentially impact foundational lumbar alignment.

Keywords: cage; device; interbody; intervertebral; lordosis; lumbar fusion; personalized; pre-operative planning.

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Conflict of interest statement

Declaration of Conflicting Interests : Saeed S. Sadrameli discloses that he receives consulting fees from Carlsmed. Donald J. Blaskiewicz discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Christopher P. Ames discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Jahangir Asghar discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Gregory M. Mundis discloses that he receives consulting fees from Carlsmed. Joseph A. Osorio discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Justin S. Smith discloses that he is a shareholder and receives consulting fees from Carlsmed. Sigurd H. Berven discloses that he receives consulting fees from Carlsmed. Chun-Po Yen discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Ashvin I. Patel discloses that he is a clinical investigator and receives consulting fees from Carlsmed. Michele Temple-Wong discloses that she is an employee of Carlsmed. Rodrigo J. Nicolau discloses that he is an employee of Carlsmed. Roland S. Kent discloses that he is a clinical research investigator and receives consulting fees from Carlsmed.

Figures

Figure 1
Figure 1
The focus of this study was on the intervertebral lordosis angle (IVL) as prescribed by the operating surgeon for the personalized device. It is defined as the angle between a tangent line to the upper (cranial) endplate of the lower vertebrae and a tangent line to the lower (caudal) endplate of the upper vertebrae.
Figure 2
Figure 2
Example of vertebral endplate irregularity (left). Prevalence and distribution of endplate defects in the lumbar spine. Data presented are prevalence rates in percent, referring to the total samples studied for that specific disc level (right).
Figure 3
Figure 3
The fit of a stock interbody device against the endplate (left) is compared with the fit of a personalized device (right).
Figure 4
Figure 4
Intervertebral lordosis (IVL) offset for all levels treated (A) and for levels treated with anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), or transforaminal lumbar interbody fusion (TLIF) with personalized interbody implants (B).
Figure 5
Figure 5
Distribution of the magnitude of the intervertebral lordosis (IVL) offset for all levels treated with personalized interbody implants of 217 adults who underwent spinal deformity surgery.
Figure 6
Figure 6
Distribution of the magnitude of intervertebral lordosis (IVL) offset stratified by implant type.
Figure 7
Figure 7
Distribution of intervertebral lordosis (IVL) offset stratified by implant type.
See this image and copyright information in PMC

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