Expandable interbody cages have earned their place in modern lumbar fusion—not because they’re trendy, but because they’ve genuinely changed what surgeons can accomplish. The ability to restore disc height and segmental lordosis through controlled, in‑situ expansion has reshaped surgical strategy in meaningful ways. Add to that the smaller insertion profiles, reduced endplate disruption, and the ability to fine‑tune alignment right on the table, and it’s easy to see why these implants have become so widely adopted.
But with time and experience, one truth has become impossible to ignore: expansion alone doesn’t guarantee lasting lordosis.
Recent regulatory actions involving Medtronic’s Catalyft™ PL and PL40 systems have brought renewed attention to this point. The implants themselves still meet all design and manufacturing standards and remain available, but the situation highlights something bigger—a biomechanical challenge that spans the entire category, not just one manufacturer.
A Category-Wide Biomechanical Challenge
Loss of lordosis, cage subsidence, and loss of disc height aren’t tied to a single implant or company. These issues have been documented across expandable systems from multiple major players—Globus Medical, NuVasive, and others who helped shape this space.
The pattern is clear: the limiting factor isn’t the manufacturer—it’s the biomechanics.
Expandable cages are designed to create alignment through expansion. But if that expansion isn’t paired with strong endplate engagement, proper compressive loading, and a supportive posterior construct, the correction achieved in the OR may not hold up over time.
Why Expansion Alone Falls Short
Biomechanically, expandable cages are excellent at creating shape. What they don’t inherently create is load.
Long‑term lordosis depends on several fundamentals:
- Solid contact with the anterior apophyseal ring
- Adequate compressive forces across the implant
- Endplate preparation that avoids over‑violation
- Posterior instrumentation that actively supports sagittal alignment
Without these elements working together, even a perfectly expanded cage can settle, subside, or gradually lose its intended correction.
Across platforms, many cases of lordosis loss show up only on imaging and never cause symptoms. But when symptoms do arise, they can lead to pain, pseudoarthrosis, or even revision surgery—turning a biomechanical nuance into a clinical problem.
Biomechanics Beyond Expansion
The updated surgical guidance highlighted in recent regulatory communications reinforces widely recognized biomechanical principles—but that deserve renewed emphasis:
- Proper anterior spine positioning and adequate implant loading are important biomechanical considerations.
- Adequate compressive loading, posterior support, and sufficient implant footprint contribute to stable load distribution over time.
These aren’t manufacturer‑specific recommendations. They’re universal truths.
Implant design enables correction, while long-term alignment depends on how forces are distributed across the construct over time. Long-term maintenance of the correction depends on multiple biomechanical conditions.
A Broader Question for the Spine Community
As expandable technology becomes more common, a larger question emerges:
Are we sometimes asking expandable cages to compensate for unfavorable loading environments or construct conditions?
Expandable implants are powerful tools, but they’re not shortcuts. When loading conditions are insufficient, loss of lordosis may occur despite appropriate implant use.
Final Perspective
The renewed attention on lordosis loss in expandable cages shouldn’t be seen as a flaw in any one device. It’s a reminder of the fundamentals that have always governed spinal biomechanics.
As expandable technologies continue to evolve, their long-term success depends not only on implant design, but also on biomechanical conditions and construct behavior over time.
Restoring lordosis doesn’t end with expansion.
It starts there.
References
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Subsidence after minimally invasive transforaminal lumbar interbody fusion.
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Expandable versus static interbody cages in minimally invasive lumbar fusion.
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Sagittal balance and lumbar interbody fusion.
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Editorial and Medical Disclaimer
This article is intended for educational and informational purposes only. It does not constitute medical advice, clinical guidance, or recommendations for the use of any specific medical device or surgical technique. Clinical decisions should always be made by qualified healthcare professionals based on individual patient conditions, official product documentation, and applicable clinical guidelines.
References to specific devices or manufacturers are provided solely for contextual and informational clarity and do not represent evaluation, comparison, endorsement, or criticism of any commercial product.