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Leg Gives Out? Is This a Warning Sign?

| | Knee

Have you ever been walking and your leg gives out? It can be both surprising and alarming   What would cause your leg to give out?  Can sciatica cause your leg to give out?  How do you treat weak legs?  Let’s dig in.

What Would Cause Your Leg to Give Out?

Weakness in the leg can arise from three principal sources:  nerve problems, muscle weakness, and SI joint dysfunction.  Weakness in the legs may indicate a significant nerve problem.   In many cases, it may be the first indication of a nerve problem.   There are three common causes of nerve injury:  low back disorders, nerve compression as it descends down into the hip, thigh, and shin and medical conditions such as diabetes.

Spinal Causes of Nerve Injury

  • Spinal tumor with irritation or compression of the spinal nerves.
  • Lumbar disc protrusion or herniation with compression of the spinal nerve can result in weakness and the feeling that your leg gives out (1).
  • Slipped disc with compression of the spinal nerve.  This is also referred to as spondylolisthesis (2).
  • Lumbar spinal stenosis with compression of spinal nerves.  Stenosis refers to the narrowing of the spinal canal.  The cardinal symptoms lumbar spinal stenosis are leg pain and weakness brought on with walking and relieved by sitting or flexing forward at the level of the hip (3).

Other Causes of Nerve Injury

  • Direct trauma to a nerve or nerves in the lower extremity can cause weakness.   Contact sports, martial arts, and motor vehicle accidents can all cause direct nerve trauma.
  • Diabetes.  the elevated blood sugars can damage the small nerve fibers (diabetic neuropathy) which is the most common complication of type 1 and 2 diabetes (4).
  • The compression of a nerve as it descends down the leg (entrapment neuropathy) can cause weakness.  Often times your leg gives out.  Common examples include entrapment of the sciatic nerve, common peroneal nerve, and posterior tibial nerve.  The latter is commonly called tarsal tunnel syndrome

Muscle Weakness

Muscle weakness can arise from many sources which include fatigue, infections, dehydration, electrolyte disorders, and medications such as statins (5).  The spinal nerves transmit the electrical signal from the brain to the muscle.  This signal tells the muscle to contract. If the nerve signal to the muscle is compromised the muscle may not respond.  If this continues over time,  the size of the muscle may decrease. A diminished or weak nerve signal with a smaller muscle oftentimes results in muscle weakness. The first sign may be your leg gives out.  It is critical that one understands a larger issue both in the muscle and lumbar spine may be at hand.  If left untreated, the low back, muscle, and nerve injuries can progress.  At some point, nerves and muscles do not recover.

SI Joint image showing where the Sacroiliac Joints are located - between the ilium and sacrum

The sacroiliac joint (SIJ) is where the tailbone (sacrum) connects with the hip (ilium) to form a very important joint.    Each of us has two SI joints, one on the right and one on the left which have thick supporting ligaments.    The two SI joints connect with a small joint in the front, the pubic symphysis.  The two SIJ’s and pubic symphysis form a very important functional unit that transfers the forces between your legs and upper body.  If one or both the SI joints have loose or injured ligaments effective transfer of the forces from the leg to the spine and upper body can be compromised and leg weakness may occur (6). The first warning sign may be when your leg gives out.

Can Sciatica Cause Your Leg to Give Out?

Yes!  When your leg gives out this may be the first signal that there is a problem in your low back.  The sciatic nerve is the largest nerve in the body and provides critical information to all the muscles in the lower extremities.  Sciatica is debilitating lower back, buttock and leg pain that is caused by a herniated disc, protrusion, joint overgrowth or bone spur that compresses the nerve.  Compression of the nerve compromises the nerve signal to the muscle which in turn can result in leg weakness and episodes when your leg gives out.

How Do You Treat Weak Legs?

For the best clinical outcome, it is best to address the underlying cause of leg weakness.  Activity modification, rest and PT are first-line treatment options for mild direct trauma and nerve entrapment.  Optimizing the glucose, and increasing activity may benefit patients with diabetes-related muscle weakness.  SI joint-related leg weakness is frequently missed as it is not well understood or appreciated by doctors.  Steroids are frequently injected into the SI joint and should be avoided as steroids are toxic to the cartilage (7).  In addition, steroids can loosen the injured SI joint ligaments.

At the Centeno-Schultz Clinic, we have extensive experience in the treatment of SI joint pain, instability, and related leg weakness.  PRP and bone marrow-derived stem cells are precisely injected into injured areas utilizing x-ray and ultrasound.   Lumbar disc protrusions, herniations, spinal stenosis, and slippage should not be treated with steroids given their toxicity to orthopedic tissue.  The Centeno-Schultz Clinic demonstrated that PRP is a safer, more effective, and longer-lasting option than steroids in the treatment of lumbar disc and leg pain (8).   To better understand current treatment options for low back and leg pain due to disc injuries please click on the video below.

In Conclusion

When your leg gives out it may a signal that you have problems brewing.  Weakness in the leg can arise from three principal causes: nerve problems, muscle weakness, and SI joint dysfunction.  Treatment is best directed at the underlying problem.  Lumbar disc disorders such as protrusion and herniations can compress the spinal nerve thereby compromising the nerve signal to the muscle.  Loose SI joint ligaments can also result in your leg giving out.  Steroids are toxic and should be avoided.  PRP, and stem cells when needed, are effective treatment options for both SIJ and lumbar disc injuries.  If left untreated the underlying problem can progress, and new injuries may occur as the result of falls when your leg goes out.

Heed the warning signal!  If your leg gives out, get an evaluation that includes muscle strength, low back, and sacroiliac joint integrity.


1.Choi HS, Kwak KW, Kim SW, Ahn SH. Surgical versus Conservative Treatment for Lumbar Disc Herniation with Motor Weakness. J Korean Neurosurg Soc. 2013;54(3):183-8.doi: 10.3340/jkns.2013.54.3.183.

2.Kalichman L, Hunter DJ. Diagnosis and conservative management of degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(3):327-35.doi: 10.1007/s00586-007-0543-3.

3.Egli D, Hausmann O, Schmid M, Boos N, Dietz V, Curt A. Lumbar spinal stenosis: assessment of cauda equina involvement by electrophysiological recordings. J Neurol. 2007;254(6):741-50. DOI: 10.1007/s00415-006-0427-1.

4. Schreiber AK, Nones CF, Reis RC, Chichorro JG, Cunha JM. Diabetic neuropathic pain: Physiopathology and treatment. World J Diabetes. 2015;6(3):432-44. doi: 10.4239/wjd.v6.i3.432.

5. Saguil A. Evaluation of the Patient with Muscle Weakness. Am Fam Physician. 2005 Apr 1;71(7):1327-1336.

6. Laslett M. Evidence-based diagnosis and treatment of the painful sacroiliac joint. J Man Manip Ther. 2008;16(3):142-52. doi: 10.1179/jmt.2008.16.3.142.

7.McAlindon TE, LaValley MP, Harvey WF, et al. Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Patients With Knee Osteoarthritis: A Randomized Clinical Trial. JAMA. 2017;317(19):1967-75. doi: 10.1001/jama.2017.5283.

8. Centeno C, Markle J, Dodson E, et al. The use of lumbar epidural injection of platelet lysate for treatment of radicular pain. J Exp Orthop. 2017;4(1):38. Published 2017 Nov 25. doi:10.1186/s40634-017-0113-5


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