Clinical Outcomes of Lumbar Fusion Using a Truss Technology Based Interbody Fusion Cage

^Plano Orthopedic and Sports Medicine Center, Plano, Texas *Texas Back Institute Research Foundation, Plano, Texas

Introduction Spinal fusion is a complex process with intricate relationships between loading, structural support, and bone cell growth. Fusion devices should incorporate these factors into design. Trusses composed of triangular units provide strong structural support with load transferred throughout a multiplanar truss structure. This loading should stimulate bone cell growth with trusses providing scaffolding for bone growth. The purpose of this study was to evaluate the clinical outcome of patients undergoing lumbar fusion using a truss technology based interbody fusion cage.

Figures 4A and B. Incorporation through the truss implant and into a solid fusion mass was demonstrated.

Discussion This study found that patients had significantly improved pain and function scores following fusion. All patients reaching 6 month follow-up were fused based on CT scan evaluation. This early experience, suggests that the truss technology based interbody device is associated with good clinical outcomes. The favorable fusion rate may be related to truss design that was established in earlier pre-clinical studies as a loading and scaffold environment favorable for cellular bone growth. Certainly more patients and longer follow-up are needed to fully evaluate this technology,.

Cameron Carmody, M.D.^; Donna D. Ohnmeiss, Dr.Med.*

Presenter’s Disclosure Consulting: 4-Web; Stock options: 4-Web; Royalties Globus

Results A description of the operative data is provided in Table 2. All procedures were performed between L3 and S1.

Methods The study was based on the consecutive series of 29 patients beginning with first case experience using the ALIF Spinal Truss System (Figure 1, 4WEB Medical, Inc.) combined with supplemental fixation. Graft material used was bone marrow aspirate combined with allograft or a bone graft extender. No BMP was used. !

Fusion was assessed from radiographs and CT scans made at 6 months after surgery (missing for one patient).!

Figure 1. Truss-based technology interbody fusion cage.

All patients were classified as fused based on plain films and CT evaluation at the 6 month follow-up (Figures 4 and B). !

# of levels operated: 1 level 14 (48.3%) 2 levels 12 (41.4%) 3 levels 3 (10.3%) Mean blood loss (cc) 136.5 Mean hospital stay (days) 3.3

Gender:! Male! 12 (41.4%)! Female! 17 (58.6%)!Age (yrs):! Mean! 46.7! Range! 21-74!BMI (kg/cm2):! Mean! 29.6! Range! 17.0-42.8!

All patients had failed to gain adequate relief from non-operative care. The most common diagnoses were painful disc degeneration and spondylolisthesis. A description of the patients is provided in Table 1. The mean follow-up was 11.4 months ranging from 6 to 24 months.!

Table 1. Description of the study group.

Table 2. Description of operative data.

There was one re-operation in the series which was undertaken to perform a laminotomy four weeks after the index operation for persistent leg pain.!

As seen in Figures 2 and 3 the mean pain scores and the mean Oswestry Disability Index (ODI) scores improved significantly when comparing the pre- to post-op values through 12 months (p<0.05). At the time of most recent follow-up, a minimum 15 point improvement in ODI scores was noted in 71.4% of patients.

Figure 2. The mean pain scores improved significantly.

Figure 3. The mean ODI scores improved significantly.

0!

10!

20!

30!

40!

Pre*op!(n=28)!

6!wk!!!!(n=28)!

3!mo!!!!!(n=25)!

6!mo!!!!!(n=28)!

12!mo!!!!!(n=20)!

24!mo!!!!!(n=3)!

39.4%

30.2%

22.5%

17.3% 16.1%

22.7%

0!

1!

2!

3!

4!

5!

6!

7!

Pre*op!(n=28)!

6!wk!!!!(n=28)!

3!mo!!!!!(n=25)!

6!mo!!!!!(n=28)!

12!mo!!!!!(n=20)!

24!mo!!!!!(n=3)!

6.1!

2.8!2.4! 2.3!

2.6!2.3!