Problems at the L4 and L5 vertebrae are among the most common spinal causes of hip and buttock pain. The nerves that exit the lower lumbar spine travel directly through the pelvis and into the hip region, so a herniated disc, bone spur, or degenerative narrowing at L4-L5 or L5-S1 can produce pain that feels as though it originates in the hip itself. This overlap between spinal and hip symptoms is so well recognized that it has its own clinical label, and it is also a frequent source of misdiagnosis.
How L4 and L5 Problems Send Pain to the Hip
The L4 and L5 nerve roots emerge from the spinal column in the lower back and feed into the lumbar and sacral plexus, a web of nerves that supplies sensation and motor control to the buttock, groin, outer thigh, and leg. When a disc bulges, herniates, or when the bony canal narrows around these nerve roots, the resulting irritation can produce pain anywhere along the nerve’s path. Because that path runs through and around the hip, the pain frequently registers in the buttock, the side of the hip, or the groin rather than in the back itself.
This is not a rare quirk. One study found that among patients with lumbar disc herniation at the L4/5 level, about 79% experienced gluteal pain, while only about 16% of those with herniation at the L5/S1 level had the same complaint. No patients with herniation at L3/4 reported gluteal pain at all. The L4/5 level accounted for roughly 95% of gluteal pain cases in the study population, making it by far the dominant spinal source of buttock-area symptoms.1PubMed Central. Which level is responsible for gluteal pain in lumbar disc hernia?
The pain does not always follow the classic “sciatica” pattern of shooting down the back of the leg to the foot. It can stop at the buttock or lateral hip, mimic a hip joint problem, or present as a deep ache in the groin. This variability is what makes L4/L5 problems a persistent diagnostic puzzle.
Why the Hip and Lumbar Spine Are So Easily Confused
Clinicians use the term “hip-spine syndrome” to describe patients who have symptoms that could plausibly come from either the hip joint or the lumbar spine, or from both simultaneously. The concept has three layers. In its simplest form, a person has disease in both areas but only one is actually causing pain, and a careful exam can sort it out. In its secondary form, disease in one region has caused or worsened disease in the other, such as a stiff hip altering gait and overloading the lower spine. In its most challenging form, both the hip and the spine are genuinely painful, and telling which is contributing what share of the symptoms is not straightforward.2Interdisciplinary Neurosurgery. Hip spine syndrome – A case series and literature review – Section: 1. Introduction
Research on people presenting with low back pain highlights just how intertwined these regions are. In one study, 80% of low-back-pain patients had reduced hip flexion, and 75% had reduced hip internal rotation. Those with reduced hip movement scored worse on both back-related and hip-related function questionnaires, and those who tested positive on provocative hip tests reported more intense pain overall.3Journal of Orthopaedic & Sports Physical Therapy. Hip and Lumbar Spine Physical Examination Findings in People Presenting With Low Back Pain, With or Without Lower Extremity Pain – Section: Results In other words, the two areas are not just anatomically neighboring; they are functionally coupled, and dysfunction in one reliably shows up as measurable limitation in the other.
The Sacroiliac Joint Adds Another Layer
Sitting between the lumbar spine and the hip is the sacroiliac joint, the connection between the base of the spine and the pelvis. It can produce pain in the buttock, low back, and even the groin that looks almost identical to either a hip problem or a lumbar nerve problem. Making things harder, sacroiliac dysfunction commonly coexists with lumbar disc disease. Studies have found that roughly a third of patients with confirmed lumbar disc herniation also have evidence of sacroiliac joint dysfunction.4PubMed Central. Radiculopathy with concomitant sacroiliac dysfunction and lumbosacral degenerative disease: illustrative case – Section: Discussion
This crossover means that when someone walks into a clinic with hip-area pain, the pain generator could be the L4/L5 disc, the hip joint itself, the sacroiliac joint, or some combination. All three structures share overlapping nerve supply and can produce remarkably similar symptoms. A clinician who fixes on one of these without checking the others risks missing the actual source.
When Misdiagnosis Leads to the Wrong Surgery
The stakes of getting this wrong are real. A review of patients who eventually received hip replacements found that about 8% had previously undergone spinal surgery. Of those who had spinal surgery first, roughly a quarter said their leg pain was never relieved by the back operation. Their pain resolved only after they finally had a hip replacement, suggesting that the original spinal surgery may have targeted the wrong site entirely. Many of these patients had endured multiple MRI scans, repeated epidural injections, and even repeat back surgeries before someone identified the hip as the true pain source.5SA Orthopaedic Journal. Misdiagnosis of hip pain could lead to unnecessary spinal surgery – Section: Results
The reverse also happens: a person whose real problem is a pinched L5 nerve root may be told they need a hip replacement because their imaging shows hip arthritis. Hip arthritis is common enough in middle-aged and older adults that it often appears on X-rays as an incidental finding, not necessarily as the thing causing their specific pain complaint. Without a deliberate effort to test both the spine and the hip, imaging alone can mislead.
How Doctors Sort Out the Source
The single most reliable tool for distinguishing hip pain from spine pain is a diagnostic injection. An injection of local anesthetic directly into the hip joint can temporarily eliminate hip-generated pain. If the patient’s symptoms vanish, the hip is the likely culprit. If the pain persists unchanged, the spine or sacroiliac joint becomes the more probable source. About a third of patients receiving hip injections in one large series were getting them specifically to determine whether their pain was actually coming from the hip or from somewhere else, such as the lumbar spine or knee.6PubMed Central. Assessing Patient Characteristics That Prolong the Need for Total Hip Arthroplasty Following Surgeon-Administered Intra-articular Corticosteroid Injections – Section: Results
The same principle works in the other direction. Selective nerve root blocks, where a small amount of anesthetic is delivered around a specific spinal nerve, can confirm whether a particular nerve root is the one generating pain.7PubMed Central. Diagnostic and therapeutic spinal interventions: Epidural injections – Section: Abstract If numbing the L5 nerve root eliminates your hip pain, the diagnosis is fairly clear. If it does not, the search shifts to the hip joint or the sacroiliac joint.
Physical examination also provides clues. Provocative hip tests that stress the hip joint in specific positions can reproduce hip-origin pain, while straight-leg raise and nerve-tension tests can reproduce nerve-root pain. Neither set of tests is perfectly reliable on its own, which is why experienced clinicians tend to use them in combination with the patient’s history and, when needed, diagnostic injections.
The Imaging Trap
MRI and X-ray findings in the lower lumbar spine are surprisingly common in people who have no pain at all. A study of asymptomatic young adults found that 56% had some form of disc abnormality on MRI, and the most frequently affected level was L4-L5, where 38% showed signs of disc degeneration, followed by L5-S1 at 30%.8PubMed Central. Disc Degeneration in Lumbar Spine of Asymptomatic Young Adults: A Descriptive Cross-Sectional Study – Section: Results
This is a crucial point for anyone who has been told their hip pain is caused by a “bad disc at L4-L5.” Disc degeneration at that level is the most common finding on any lumbar MRI, symptomatic or not. The mere presence of a bulging or degenerated disc does not prove it is the thing causing your pain. The disc finding needs to match the clinical picture: the location of your symptoms, the pattern of nerve involvement on exam, and ideally a positive response to a targeted injection. Without that correlation, treating the disc is a gamble.
The Biomechanical Link Between Spine and Hip
Beyond direct nerve compression, L4/L5 problems can affect the hip through altered body mechanics. When the lower lumbar spine stiffens from degeneration, the pelvis loses some of its ability to tilt backward when you sit down. This reduced pelvic motion changes the angle of the hip socket relative to the thighbone, which can lead to impingement at the front of the hip and increase the risk of hip joint instability. Research on patients with spinal degeneration and flatback deformity has shown that lower lumbar stiffness significantly decreases the pelvis’s protective range of motion, creating a mechanical pathway from spinal disease to hip damage.9The Journal of Arthroplasty. Primary Arthroplasty Lumbar Spine Degeneration and Flatback Deformity Alter Sitting-Standing Spinopelvic Mechanics—Implications for Total Hip Arthroplasty – Section: Abstract
This is the secondary form of hip-spine syndrome in action: the spine problem comes first, and the hip problem develops as a downstream consequence of abnormal loading. In these cases, addressing only the hip without acknowledging the spinal stiffness can lead to ongoing problems, including higher dislocation rates after hip replacement.
Why the Lower Lumbar Spine Is So Vulnerable
The concentration of problems at L4-L5 and L5-S1 is not random. The evolutionary transition to upright walking required the human lumbar spine to curve inward (lordosis), which shifts the body’s center of gravity backward over the hips. This adaptation makes bipedal walking efficient, but it also concentrates high compressive and shearing forces on the lowest lumbar vertebrae and their discs. The same pelvic shape that stabilizes the trunk during single-leg stance interacts with lumbar curvatures in ways that generate chronic mechanical stress at those levels.10PubMed Central. Lower back pain
In practical terms, the L4-L5 and L5-S1 segments bear the largest share of the body’s weight during standing, bending, and twisting. They are also the segments with the greatest range of motion in the lumbar spine. That combination of high load and high mobility is why these levels degenerate earlier and more often than the levels above them, and why they are the levels most likely to produce symptoms that radiate into the hip and leg.
Treatment Sequencing When Both Are Involved
For patients who genuinely have both a lumbar spine problem and a hip problem, the question of which to treat first has no universal answer. Surveys of spine and hip surgeons show that treatment order depends on which condition is deemed more dominant. In scenarios where the spine symptoms are more prominent, a spine-first approach is favored. When the hip is clearly the bigger contributor, surgeons tend to recommend hip replacement first.11PubMed Central. What would you do first? A survey of treatment priorities for patients with hip-spine syndrome among spine and hip surgeons – Section: Results
There has been concern that the order of surgery affects the risk of complications, particularly hip dislocation after hip replacement. If the lumbar spine is fused first, it can change pelvic tilt and affect the mechanics of an artificial hip joint. However, a study examining dislocation rates after hip replacement found no significant difference whether the lumbar spine fusion happened before or after the hip replacement. Dislocation rates were about 3.6% for those who had spine surgery first and 4.0% for those who had hip surgery first.12PubMed Central. Is Timing of Total Hip Arthroplasty and Lumbar Spine Fusion Associated With Risk of Hip Dislocation? – Section: RESULTS That finding is somewhat reassuring, though the overall dislocation rate in patients who need both surgeries is still higher than in those who only need a hip replacement, reflecting the underlying mechanical complexity.
What to Do If You Suspect Your Hip Pain Comes from Your Spine
If you have been told you have a hip problem but the diagnosis does not fully explain your symptoms, or if hip treatment has not relieved your pain, it is worth asking whether the lower lumbar spine has been evaluated. A few patterns suggest a spinal origin rather than a pure hip-joint problem:
- Pain with sitting: Hip-joint arthritis often feels worst with weight-bearing activities like walking and improves with rest, while nerve-root pain from the spine frequently worsens with prolonged sitting or bending forward.
- Radiating patterns: Pain that travels below the knee, produces numbness or tingling in the foot, or follows a stripe down the side or back of the leg is more suggestive of a nerve root than a hip joint.
- Back stiffness: If your hip pain is accompanied by significant morning stiffness in the low back, limited ability to bend, or pain that worsens with coughing or sneezing, the spine becomes a stronger suspect.
- Failure to respond: Hip pain that does not improve after a diagnostic hip injection, or that persists after hip surgery, should prompt a re-evaluation of the lumbar spine.
None of these patterns is absolute. Some people with hip arthritis do experience groin pain with sitting, and some people with nerve compression have pain mainly with standing. The value of these clues is in guiding which diagnostic tests to pursue, not in making the diagnosis on their own.
The Role of Physical Therapy and Conservative Treatment
Not every case of L4/L5-related hip pain requires surgery or injections. Many disc bulges and mild to moderate nerve irritation improve with time, targeted exercise, and activity modification. Strengthening the muscles around the hip and pelvis can reduce the mechanical load on the lower lumbar spine, and improving hip mobility can take stress off the spine as well, since the two move as a functional unit. Physical therapy programs that address both the hip and the lumbar spine simultaneously tend to reflect the clinical reality better than programs that focus on one region in isolation.
For persistent or severe cases, epidural steroid injections can reduce inflammation around the affected nerve root and provide temporary relief, sometimes enough to allow rehabilitation to gain traction. Surgery on the lumbar spine, whether decompression or fusion, is typically reserved for cases where conservative measures have failed and where there is a clear match between the imaging findings, the clinical examination, and the pattern of pain. Getting that match right, especially when the hip is also a potential contributor, is the hard part and the reason the diagnostic injection approach described earlier exists.
When Both Conditions Are Real but One Matters More
The existence of hip-spine syndrome means that “both” is a legitimate diagnosis, but it does not mean both problems always need aggressive treatment at the same time. In many patients, one condition is the primary pain driver and the other is a secondary or even incidental finding. A degenerative disc at L4-L5 on MRI alongside moderate hip arthritis on X-ray does not automatically mean both are causing symptoms. The clinical task is to figure out which one is doing the heavy lifting in terms of pain and disability, treat that one first, and then re-evaluate.
This stepwise approach is what experienced clinicians favor. It avoids the trap of overtreating both areas simultaneously when only one needs intervention, and it respects the fact that resolving the primary pain source sometimes improves the secondary one as well, since altered gait, muscle guarding, and compensatory movement patterns can resolve once the dominant problem is addressed.