Tenon(R) Medical Announces Second Peer-Reviewed Catamaran Mainsail(TM) Study Publication, Underscores Robust and Sustainable Clinical Outcomes Out to 12 Months

~ Clinically Significant Patient Outcomes Demonstrate Improvements in Pain (VAS) and Disability (ODI), Along with High Patient Satisfaction and Safety Profile at 12-Month Analysis ~

~ 83% of Patients Reaching 12 Month Radiographic CT Follow-up Showed Unequivocal Evidence of Fusion with Bridging Bone Across the SI Joint as Identified by an Independent Radiology Reviewer ~

~Compelling Clinical Data from Catamaran Mainsail Study and Recently Acquired SiVantage Technology Portfolio Expected to Drive Exponential Growth in Rapidly Expanding Sacro-Pelvic Fusion Market ~

LOS GATOS, CA / ACCESS Newswire / September 4, 2025 /Tenon Medical, Inc. (NASDAQ:TNON) ( "Tenon " or the "Company "), a company transforming care for patients suffering with certain sacro-pelvic disorders, today announced the second interim analysis publication from its ongoing MAINSAIL^™ study, a prospective, single-arm, multi-center, post-market clinical trial evaluating clinical and radiographic outcomes in adult patients with sacroiliac (SI) joint disruptions or degenerative sacroiliitis treated with the Catamaran^®SI Joint Fusion System.

The Mainsail study is designed to enroll up to 50 patients, each followed for up to 24 months. This second interim analysis reports on the first 24 consecutive patients treated across six U.S. clinical sites, with both primary and secondary clinical endpoints assessed at 12 months. Additionally, radiographic CT fusion assessments were performed by an independent radiologist to ensure objective evaluation.

Key findings from this second interim analysis continue to show robust and durable outcomes out to 12 months.

Statistically Significant Reduction in SIJ Pain (VAS) and Disability (ODI) Scoring at 12 months:

• Mean VAS SIJ pain intensity scores (0-100) significantly decreased from pre-operative levels of 78.8mm to 23.0mm (p<0.001).

• ODI scores, measuring a patient 's perceived disability, showed a significant improvement from pre-operative values of 51.6% to 20.8% (p<0.001).

• 83.3% of subjects demonstrated an improvement in ODI by more than 15%.

Robust Safety Profile:

• No serious adverse events, no re-operations, and no re-interventions reported.

• No vascular or nerve injuries associated with the use of the inferior-posterior surgical approach used to deliver the Catamaran implant.

High Patient Satisfaction Throughout All Follow-Up Timepoints:

• 83.3% of patients reported high satisfaction with their treatment at 12 months.

Continued Definitive Evidence of Fusion Response at 12 months:

• 23 of 24 subjects reached 12 months follow-up with CT radiographic imaging for fusion.

• 19 of the 23 (83%) patients showed unequivocal evidence of fusion with bridging bone across the SI joint and no radiolucency as identified by an independent radiology reviewer.

Efficient Surgical Technique and Procedural Workflow:

• 45.7% of procedures were completed in under 45 minutes, with the shortest procedural time recorded as 24 minutes.

• All procedures were performed in an outpatient setting.

The authors of this study note that patient-reported outcome measures, particularly ODI and VAS for SI joint pain, have been widely used to assess clinical success in prior studies of minimally invasive SI joint fusion. In a comprehensive review, Martin et al.¹ reported weighted mean improvements of 48.1 points in VAS and 21.8% in ODI at 12 months, based on 18 VAS and 10 ODI studies across lateral and posterior approaches. More recently, Xu et al.² analyzed 48 studies focused on VAS, demonstrating average 12-month improvements of 50 points for lateral, 38 points for posterior lateral, and 49 points for intra-articular SI Joint fusion techniques. Although variability exists in study design, follow-up duration, inclusion criteria, and statistical methods, these reviews provide useful benchmarks for expected clinical improvement. In this context, the 12-month results from the MAINSAIL Study, 57.8 points improvement in VAS and 30.4% in ODI-demonstrate substantial benefit with the novel inferior-posterior approach, exceeding the averages reported in prior literature or studies.

The Catamaran® SI Joint Fixation Device is a robust, single-piece titanium implant with two pontoons connected by an osteotome bridge, engineered to transfix the SI joint along its longitudinal axis for immediate stabilization and long-term fusion. Developed in line with AO principles of arthrodesis - joint preparation, rigid fixation, and bone graft augmentation - it is placed via a minimally invasive inferior-posterior approach into the dense cortical bone of the sacrum and ilium. More than 1,000 devices have been implanted to date for primary SI joint dysfunction, sacroiliitis, revision of failed alternative implants, and to stabilize the SI joint beneath lumbar long constructs, underscoring its versatility and proven clinical performance.

These interim results from the MAINSAIL Study deliver compelling evidence of the Catamaran SI Joint Fusion System 's safety and efficacy, reinforcing its potential as a breakthrough, minimally invasive solution for patients living with debilitating SI joint dysfunction.

Matthew Davies, MD, a board-certified neurosurgeon at Orthopaedic Associates of Duluth in Duluth, MN, and principal investigator and lead author of the publication, commented, "I am extremely encouraged by the ongoing clinical outcomes we are seeing at 12 months with the Catamaran SI Joint Fusion System, as demonstrated in the MAINSAIL Study. Patients in the study continue to achieve clinically meaningful reductions in both VAS pain and ODI disability scores, and the high fusion rates observed at 12 months further validate the Catamaran as a reliable, minimally invasive solution for treating SI joint dysfunction. I look forward to the completion of the study and further analysis of the data to deepen our understanding of the Catamaran SI Joint Fusion System 's impact on patients living with debilitating SI joint disease. "

"The enduring positive outcomes from this second interim analysis of the MAINSAIL Study continues to reinforce the clinical value of the Catamaran SI Joint Fusion System, " said Steven M. Foster, President and CEO of Tenon Medical. "These results highlight our ability to deliver consistent, reliable fusion with the Catamaran Fixation Device using the inferior posterior approach, while offering physicians a solution that combines ease of use, safety, and meaningful patient outcomes. Coupled with our recent acquisition of SiVantage 's innovative technology, Tenon is now uniquely positioned to lead the sacro-pelvic market with a comprehensive, multi-approach portfolio that addresses the full spectrum of patient needs and physician techniques. "

To read the full study publication please click the following link to the Catamaran 12-month MAINSAIL Study Outcomes.

References

1. Martin CT, Haase L, Lender PA, et al. Minimally invasive sacroiliac joint fusion: the current evidence. Int J Spine Surg. 2020;14(Suppl 1):S20-S29. doi: 10.14444/6072

2. Whang PG, Patel V, Duhon B, et al. Minimally invasive SI joint fusion procedures for chronic SI joint pain: systematic review and meta-analysis of safety and efficacy. Int J Spine Surg. 2023;17(6):794-808. doi: 10.14444/8543

About Tenon Medical, Inc.

Tenon Medical, Inc., a medical device company formed in 2012, has developed The Catamaran SI Joint Fusion System that offers a novel, less invasive approach to the SI joint using a single, robust titanium implant. The system features the Catamaran™ Fixation Device which passes through both the axial and sagittal planes of the ilium and sacrum, stabilizing and transfixing the SI Joint along its longitudinal axis. The angle and trajectory of the Catamaran surgical approach is also designed to provide a pathway away from critical neural and vascular structures and into the strongest cortical bone. Tenon is focused on three commercial opportunities with its System in the SI Joint market which include: 1) Primary SI Joint procedures, 2) Revision procedures of failed SI Joint implants and 3) Augmenting spinal fusion. For more information, please visit www.tenonmed.com.

The Tenon Medical logo shown above, and Catamaran^®, PiSIF^®, CAT PiSIF^®, ETAD^®, Posterior Inferior Sacroiliac Fusion^®, CAT SIJ Fusion System^®, Catamaran SIJ Fusion System^®, Catamaran Inferior Posterior Fusion System^®, Catamaran Transfixation Fusion System^®, Catamaran Transfixation Fusion Device^®, SImmetry^® are registered trademarks of Tenon Medical, Inc. MAINSAIL^TM, Catamaran Mainsail^™ Study, and SImmetry+^™are also trademarks of Tenon Medical, Inc.

Safe Harbor

This press release contains "forward-looking statements, " which are statements related to events, results, activities, or developments that Tenon expects, believes, or anticipates will or may occur in the future. Forward-looking often contains words such as "intends, " "estimates, " "anticipates, " "hopes, " "projects, " "plans, " "expects, " "seek, " "believes, " "see, " "should, " "will, " "would, " "target, " "aims, " and similar expressions and the negative versions thereof. Such statements are based on Tenon 's experience and perception of current conditions, trends, expected future developments and other factors it believes are appropriate under the circumstances, and speak only as of the date made. Forward-looking statements are inherently uncertain, and actual results may differ materially from assumptions, estimates or expectations reflected or contained in the forward-looking statements as a result of various factors. For details on the uncertainties that may cause our actual results to be materially different than those expressed in our forward-looking statements, please review our Annual Report on 10-K on file with the Securities and Exchange Commission at www.sec.gov, particularly the information contained in the section entitled "Risk Factors ". We undertake no obligation to publicly update or revise any forward-looking statements to reflect new information or future events or otherwise unless required by law.

IR Contact:

Shannon Devine
203-741-8811
MZ North America
tenon@mzgroup.us

SOURCE:Tenon Medical, Inc.

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