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L5 S1 Fusion Surgery

Indications, Complications, & Alternative Treatments

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Your low back pain is crippling and has failed to respond to conservative treatments.  Your doctor recommended an L5 S1 surgery.  What is L5 S1 Fusion?  What are the indications for L5 S1 Fusion?  Is L5/S1 fusion major surgery? What is the success rate of fusion surgery?  What are the complications?  Are there regenerative alternative treatments?  Let’s dig in.

What is L5 S1 Fusion Surgery? l5 s1 fusion

Spinal fusion is a major surgery where one or more spinal bones (vertebrae) are fused together using screws, bolts, and or plates.  The hardware may be placed in the front (anterior) or the back (posterior) of the spine. The disc between the spinal bones is often times removed and replaced with bone or a spacer.  L5 S1 Fusion refers to the level of the surgery.

L5 S1 Fusion

There are 5 spinal bones in the low back which are numbered from top to bottom L1, L2, L3, L4, and L5.  Sandwiched between each of the spinal bones is a disc.  The disc is named for the two spinal bones it is sandwiched between.  For example, the lowest disc in the low back is the L5/S1 disc. The L5/S1 disc is sandwiched between the L5 and S1 spinal bones.  Therefore, L5 S1 fusion surgery involves the surgical removal of the L5/S1 disc and fusing the L5 and S1 spinal bones together. Different surgical techniques and approaches exist.  PLIF, posterior lumbar interbody fusion is a case in point that has been reviewed in detail in a prior blog.

What Are the Indications for L5 S1 Fusion?

Lumbar fusion is a popular surgery.  Between 1998 and 2008, the yearly number of lumbar fusion surgeries performed in the United States increased from 77,682 to 210,407 (1).  Lumbar fusion can be used to treat a number of painful and degenerative conditions in the low back.  The most common indications for L5 S1 fusion include: Low back disc degeneration Slipped disc (spondylolisthesis) Spinal Bone Fracture Recurrent  Disc Herniation Pain radiating down leg (Sciatica ) Curvature (Scoliosis) Narrowing of the Canal (Stenosis) Failed Spine Surgery with Instability.

Is a Spine Fusion Major Surgery?

Absolutely!  The surgery involves cutting through important muscles,  ligaments, and tendons to access the targeted disc.  The disc is then removed and the area is packed with bone and often times a spacer. To stabilize the spine, screws are placed into the spinal bones above and then below the disc that is removed.  The screws are stabilized by additional hardware including plates and rods.

What Is the Success Rate of Spinal Fusion Surgery?

Success, as it relates to spinal fusion surgery, is difficult to judge. Why?  Because there are a significant number of variables involved including the specific surgical approach, preoperative MRI, and x-ray finding, the results from pressuring the disc, patient’s age, medical history, and the parameters studied.  Consider the following results: In one study 53 patients were followed for an average of 20 months after fusion surgery.  In those patients with normal MRIs prior to surgery, only 50 % were improved after surgery. (2) 2 years after lumbar fusion 40% of patients were unsure/dissatisfied with the outcomes reporting ongoing back pain and limited daily function (3) Another study demonstrated that the overall failure rate of lumbar spine surgery was estimated to be 10%–46% (4). So, l5 s1 surgery success rates would reflect in those statistics.

Can Screws Come Loose After Spinal Fusion?

Yes!  There are a number of complications arising from L5 S1 fusion.  The most common include failed fusion where the bones do not properly fuse.  Why would this occur? Learn more about the long-term effects of spinal fusion here.


Non-union occurs when the spinal bones that are bolted together fail to fuse or grow together.  Rates vary depending upon the specific type of lumbar spinal fusion procedure.  For procedures that require more bone, like a posterior fusion, the non-union rates are as high as 26-36% (5,6,).

Hardware Breaking

spinal fusion complications years later

Broken Screws in Lumbar Fusion

Lumbar fusion involves screws, bolts, and plates that stabilize the spinal bones.  There are significant forces placed on the low back and the hardware.  Regrettably, as a result of these forces, the hardware can break creating spinal instability and pain. The incidence of hardware failure in one study was an alarming 36% (7).  Treatment of hardware failure often requires additional surgery to remove the broken hardware and replace it.

Hardware Becomes Loose

Screws are used in lumbar fusion to stabilize the spine.  The same forces that can cause the hardware to break can also cause the screws to become loose.  This, in turn, can create spinal instability and pain. Collectively about 1 in 10 patients who have a low back fusion will need a second surgery to fix non-union or hardware failure (8).

Additional Complications from L5 S1 Lumbar Fusion

There are a number of problems that arise as a direct result of lumbar fusion itself.  The two that you most need to know about are Adjacent Segment Disease and Spinal Muscle Injury.

Adjacent Segment Disease

The disc is an important shock absorber.  Fusion surgery removes this important shock absorber placing additional stress and forces on the discs and facet joints above and below the level of the fusion. This additional force in turn can lead to injury of these facet joints and discs leading to degeneration and arthritis.  This is a real problem, with an incidence of 9% (9).  This can lead to additional surgeries including fusions.  To learn more about this tragic complication please click on the video below.

Spinal Muscle Injury

The spinal muscles provide critical stability and support for the spine.  Unfortunately, lumbar fusion significantly compromises the health and integrity of these muscles. This is in turn can lead to spine instability and additional injuries including degeneration and arthritis.  VA is a recent patient seen in the clinic who experienced this complication.  VA underwent lumbar fusion several years ago for severe low back pain.  Unfortunately, after the surgery, the pain never changed.  His low back MRI is below and is most significant for the death of the critical low back muscles.  The MRI is a cross-section image.  On the right, the yellow arrows point to dark healthy spine muscles that were present prior to the surgery.  The image on the left is after the surgery.  The yellow arrows point to the muscles that were injured and now are dead as a result of the fusion surgery.

Is There an Alternative to L5 S1 Fusion Surgery? What Non Surgical Options Exist?

Absolutely.  At the Centeno-Schultz Clinic, we believe in a comprehensive approach to the treatment of spinal pain.  We view and approach the spine as a Functional Spinal Unit.  This functional unit includes discs, facet joints, ligaments, fascia, and muscles.  These structures work with one another in a highly specialized and dependent manner.  Therefore for the very best results, the spine and all its parts need to be evaluated and treated together.  This novel, comprehensive approach can help you avoid lumbar fusion and its complications.  Treatment options include PRP and your own bone marrow-derived stem cells.  PRP is rich in growth factors that can increase blood flow and healing.  To better understand how to avoid lumbar fusions by using precisely guided PRP and stem cell injections please click on the video below.

In Conclusion: Lumbar Spinal Fusion Is Not the Only Option Your Back Pain

L5 S1 fusion is major surgery whereby the L5/S1 disc is removed and the L5 and S1 spinal bones are stabilized by hardware.  Indications for L5 S1 fusion are debilitating pain and dysfunction arising from degenerative disc disease, slipped disc, fractures, recurrent herniation, sciatica, scoliosis, and spinal canal narrowing.  Success rates vary depending upon the parameters examined.  Patient satisfaction is low.  Complications include failed fusion due to non-union, hardware breaking, and hardware becoming loose.  Adjacent Segment Disease and injury of spinal muscles are additional complications from fusion surgery.  These complications can be avoided by avoiding fusion surgery in the first place.

Consider the Perc-FSU Procedure

The functional spinal unit is the comprehensive approach utilized at The Centeno-Schultz Clinic, in Broomfield, Colorado – right between Boulder and Denver. It views the spine and all its moving parts as a whole.  Treatment options for back pain include PRP and a patient’s own bone marrow-derived stem cells.  Don’t let your low back pain limit your future.  Schedule a Telemedicine consultation with a board-certified, fellowship-trained physician who can discuss your regenerative options.  PRP and stem cell treatment options can accelerate your healing and do not have the complications or significant downtime associated with L5 S1 fusion surgery.\


1. Rajaee SS, Bae HW, Kanim LE, Delamarter RB. Spinal fusion in the United States: analysis of trends from 1998 to 2008. Spine (Phila Pa 1976) 2012;37:67–76.

2..Gill K, Blumenthal SL. Functional results after anterior lumbar fusion at L5-S1 in patients with normal and abnormal MRI scans. Spine. 1992;17(8):940-2.

3.Greenwood J, McGregor A, Jones F, Hurley M. Evaluating rehabilitation following lumbar fusion surgery (REFS): study protocol for a randomised controlled trial. Trials. 2015;16:251.

4. Thomson S. Failed back surgery syndrome: definition, epidemiology and demographics. Br J Pain. 2013;7:56–59.

5.Tsutsumimoto T, Shimogata M, Yoshimura Y, Misawa H. Union versus nonunion after posterolateral lumbar fusion: a comparison of long-term surgical outcomes in patients with degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(8):1107–1112. doi: 10.1007/s00586-008-0695-9.

6.Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991 Jul; 73(6):802-8.

7.Harris IA, Traeger A, Stanford R, Maher CG, Buchbinder R. Lumbar spine fusion: what is the evidence. Intern Med J. 2018;48(12):1430-4.

8.Greiner-Perth R, Boehm H, Allam Y, Elsaghir H, Franke J. Reoperation rate after instrumented posterior lumbar interbody fusion: a report on 1680 cases. Spine (Phila Pa 1976). 2004 Nov 15;29(22):2516-20. 9..Okuda S, Yamashita T, Matsumoto T, et al. Adjacent Segment Disease After Posterior Lumbar Interbody Fusion: A Case Series of 1000 Patients. Global Spine J. 2018;8(7):722-7.

Am I a Candidate?

To answer this question, fill out the candidate form below to request a new patient evaluation, and a patient advocate will reach out to you to determine your next steps. Your one-hour, in-office or telemedicine evaluation will be with one of the world’s experts in the field of Interventional Orthopedics.

Insurance may cover office visits, consultations, diagnostic testing, examinations and bracing. However, most insurance does not currently cover Regenexx Procedures at this time.