Can a Knee Injury Cause Hip Pain?

Knee injuries can and frequently do cause hip pain, even when nothing is structurally wrong with the hip itself. The connection runs through several channels: your body compensates for a damaged knee by shifting load to the hip, muscles around the hip weaken or shut down reflexively after knee trauma, and shared nerve pathways can relay pain signals from the knee into the hip region. The relationship is well documented in the research literature, and understanding it matters because treating the hip alone will fail if the knee is the actual source of the problem.

Your Leg Works as One Connected Unit

The hip, knee, and ankle together form what researchers call the lower extremity kinetic chain, meaning force and motion at one joint directly influence what happens at the others.¹ When you walk, energy transfers continuously between these three joints in a coordinated sequence. If one link in that chain is injured, stiff, or painful, the adjacent joints have to pick up the slack. The hip sits directly above the knee in the chain, so it tends to absorb the brunt of any compensation for knee problems.

This is not just a theoretical concept. Researchers have repeatedly measured how a single knee problem ripples upward and downward through the leg, altering joint angles, muscle activation timing, and the distribution of force during ordinary walking. The hip is especially vulnerable because it controls so much of what happens during each stride: it stabilizes the pelvis, absorbs shock during heel strike, and generates the power that propels you forward. When it is forced to do all of this differently because of a knee issue, pain is a predictable result.

How a Bad Knee Changes the Way You Walk

One of the most studied pathways from knee injury to hip pain is altered gait. When your knee hurts, you instinctively modify your walking pattern to reduce load on it. You might shorten your stride, avoid fully straightening the leg, or lean your trunk to one side. These adjustments feel protective in the moment, but they redistribute mechanical stress in ways the hip was not designed to handle long-term.

People with knee osteoarthritis, for example, walk with measurably different hip mechanics compared to people with healthy knees. Research has shown that the forces acting on the hip in the side-to-side plane change in the presence of knee arthritis, and that the abnormal loading moment at the knee correlates with altered hip loading during walking.² Separately, studies have found that people with knee osteoarthritis experience increased loading rates across all the joints in the affected leg, not just the knee, and that this elevated loading may accelerate the onset of arthritis in joints adjacent to the knee.³

People with more severe knee disease also tend to develop a noticeable lateral trunk lean, where the upper body tilts toward the affected side during each step. This lean reduces the load on the inner compartment of the knee but forces the hip abductor muscles to work harder to keep the pelvis level. Over weeks and months, that extra demand can produce pain around the outer hip, deep in the groin, or in the buttock.⁴

ACL Tears and Persistent Hip Changes

Anterior cruciate ligament injuries are among the most common serious knee injuries, especially in young, active people. What many patients do not realize is that an ACL tear changes hip mechanics in ways that persist even after surgical reconstruction and months of rehabilitation. Research following ACL-injured patients over several years found that those who went on to develop knee osteoarthritis within five years walked with smaller hip motion and lower hip forces on the injured side, both before and after surgery.⁵

These are not dramatic, visible changes. A person walking after ACL reconstruction usually looks fairly normal. But the subtle shifts in hip angles and forces add up. The hip works slightly differently on every step, thousands of steps per day, and those accumulated differences can produce pain in the hip joint, in the muscles surrounding it, or in the tendons that attach to the pelvis. The fact that these changes survive surgery and rehabilitation suggests they are deeply ingrained in the nervous system’s motor patterns, not just a short-term protective response.

When Hip Muscles Shut Down After Knee Injury

One of the more surprising pathways from knee injury to hip pain involves a phenomenon where muscles around the hip become inhibited, essentially turning down their activation, in response to damage at the knee. This is not a conscious decision to avoid using a muscle. It is an automatic neurological response, similar to how the quadriceps muscle on the front of the thigh weakens reflexively after knee surgery.

A systematic review examining the gluteus medius, the key muscle that stabilizes your pelvis during single-leg stance and walking, found clear signs of inhibition after ACL injury or reconstruction. Multiple studies showed reduced muscle activation and weakness in this muscle, with altered neuromuscular recruitment patterns suggesting an involuntary inhibitory mechanism at work.⁶ When the gluteus medius is not doing its job, the pelvis drops on the opposite side during walking, the hip joint takes on uneven loads, and the tendons around the greater trochanter (the bony bump on the side of the hip) get irritated. The result is lateral hip pain that can be quite persistent, and the person often has no idea it traces back to the knee.

This connection also runs in the other direction for patellofemoral pain, the common condition where the kneecap hurts during stairs, squatting, or prolonged sitting. Systematic review evidence has shown that patellofemoral pain is associated with decreased hip abductor and external rotator strength, along with faulty hip mechanics during movement.⁷ In this case the hip weakness may contribute to the knee problem, but the resulting pain cycle means the knee injury and hip dysfunction feed each other. Strengthening the hip is a standard part of treating patellofemoral knee pain precisely because the two joints are so tightly coupled.

Referred Pain and Shared Nerve Pathways

Not all hip pain from a knee injury comes from mechanical overload or muscle weakness. Sometimes the pain is neurological, carried from one area to another along shared nerve highways. The femoral nerve, the largest nerve of the lumbar plexus, controls both major hip flexor muscles and the knee extensors, and carries sensory information from both regions.⁸ Other nerves, including the obturator nerve and branches of the sciatic nerve, also serve both joints. Because these nerves overlap in their territory, the brain can misinterpret where a pain signal is coming from. A problem at the knee can produce a sensation of pain in the hip, groin, or front of the thigh, even though no damage exists in those areas.

This referred-pain phenomenon is especially important in children and adolescents. A condition called slipped capital femoral epiphysis, where the growth plate at the top of the thighbone shifts out of position, commonly presents as knee pain rather than hip pain. Every child who shows up with unexplained knee, thigh, or hip pain needs a thorough hip examination, because the knee complaint may be referred pain from a hip problem that requires urgent treatment.⁹ The nerve-sharing works both ways: just as a hip problem can masquerade as knee pain in a child, a knee injury in an adult can project discomfort into the hip region. A clinician evaluating hip pain should always ask about the knee, and vice versa.

Balance and Proprioception Problems

When a knee is injured, the joint’s ability to sense its own position in space, called proprioception, deteriorates. This is not just about pain; the injury disrupts sensory receptors within the joint capsule and surrounding tissues. People with knee osteoarthritis show much poorer joint position sense than people with healthy knees, and this deficit correlates with measurable problems in balance and stability. In one study, people with bilateral knee osteoarthritis had nearly twice the reaction time on balance tests and significantly reduced ability to control the direction and extent of their body sway compared to an asymptomatic group.¹⁰

When your knee cannot accurately report where it is during movement, the hip and trunk muscles have to compensate by making constant micro-adjustments to keep you upright. This extra stabilization work is invisible to the person doing it, but it fatigues the hip musculature and can produce an aching soreness around the hip that worsens as the day goes on or after prolonged standing. The connection is indirect but real: the knee’s damaged sensors force the hip to work overtime as a stabilizer, and the hip eventually protests.

When the Nervous System Amplifies Everything

In some people, chronic knee pain triggers a broader change in how the nervous system processes pain signals, a phenomenon called central sensitization. Instead of pain being limited to the injured tissue, the nervous system becomes hyper-reactive, amplifying normal sensory input from nearby areas into pain. This helps explain why some people with chronic knee problems develop widespread pain in the hip, thigh, lower back, or even the opposite leg.

Nociplastic pain, the clinical term for pain driven by altered nervous system processing rather than ongoing tissue damage, has been identified in more than a third of patients presenting for evaluation of hip and knee arthritis.¹¹ For these patients, the hip pain is genuine, but it does not correspond to any structural damage in the hip. Imaging may look clean or show only age-related changes. The problem lives in the pain-processing system itself, and it was often set in motion by a knee injury months or years earlier. Recognizing this pattern matters because these patients tend to respond poorly to surgical interventions aimed at the hip and often benefit more from approaches that address the sensitized nervous system, such as graded exercise, pain education, and sometimes medication that modulates nerve signaling.

The Imaging Trap

When someone with a knee injury develops hip pain, a natural next step is to get an MRI of the hip. This can be helpful, but it also introduces a real risk of overdiagnosis. A landmark study that performed MRI scans on completely asymptomatic volunteers, people with no hip pain or hip problems whatsoever, found abnormalities in nearly three out of four hips. Labral tears appeared in roughly seven out of ten pain-free hips, cartilage defects in about a quarter, and various other findings including bone edema and cysts were common, with rates climbing steeply after age 35.¹²

The clinical implication is sobering. If you scan enough hips, you will find something that looks abnormal, whether or not it has anything to do with the person’s pain. A patient whose hip pain is actually caused by gait compensation from a knee injury might get an MRI showing a labral tear, undergo hip surgery to repair it, and find that the pain does not improve, because the labral tear was incidental and the real driver was a dysfunctional walking pattern originating at the knee. Good clinicians look at the whole picture, examining the knee, watching the person walk, testing hip muscle strength, and considering timing (did the hip pain start after the knee injury?) before concluding that an imaging finding is the explanation.

Long-Term Risk of Hip Arthritis After Knee Injury

Beyond the immediate and medium-term pain, there is a longer-term concern. Joint injury in young adults substantially increases the risk of developing osteoarthritis at the injured joint. One large study found that a knee injury increased the risk of subsequent knee osteoarthritis by roughly five-fold, and although the data for hip osteoarthritis after hip injury was less precise, the elevated risk at the hip was estimated at about three and a half times normal.¹³ The mechanism likely involves both the direct damage from the original injury and the years of subtly altered mechanics that follow. Every step taken with compensated gait represents a slightly abnormal load distributed across all the joints in the chain, and that cumulative burden can eventually cross the threshold into arthritis at the hip even though the original injury was at the knee.

What Rehabilitation Looks Like

If your hip pain traces back to a knee problem, the rehabilitation strategy needs to address both joints simultaneously. Simply stretching or strengthening the hip in isolation will provide limited relief if the underlying gait dysfunction or knee instability persists. Evidence supports gait retraining as one effective approach. In runners with patellofemoral pain, for instance, programs that modified either foot-strike impact or running cadence produced large improvements in pain and knee function compared to controls.¹⁴ By correcting how the leg moves during running or walking, these programs reduce the compensatory demands placed on the hip.

Hip strengthening, especially targeting the gluteus medius and the deep external rotators, remains a cornerstone of treatment for people whose hip pain stems from knee-related muscle inhibition. The goal is not just to make the hip muscles stronger in a gym setting but to retrain the nervous system so those muscles activate properly during functional movement. This often takes longer than patients expect. Reflexive inhibition that developed over months or years does not resolve in a few weeks of exercises, and people who stop rehabilitation too early tend to see the hip pain return.

Foot orthotics have also been investigated as a way to alter lower-limb mechanics from the bottom of the kinetic chain. Research on medially wedged foot orthoses in runners found that they produced small changes in knee and hip joint mechanics, a modest increase in knee abduction moment and a slight decrease in hip adduction movement, but the effects were minimal overall.¹⁵ Orthotics may help some individuals, but they are not a reliable standalone solution for hip pain caused by knee dysfunction. The more consistently effective approach remains targeted exercise and, when appropriate, gait retraining supervised by a physical therapist who evaluates the entire lower extremity rather than one joint at a time.

When to Suspect the Knee Is Behind Your Hip Pain

A few patterns suggest that hip pain may be secondary to a knee problem rather than a primary hip issue. The timing is often the biggest clue: if hip pain appeared weeks or months after a knee injury, surgery, or the onset of knee symptoms, the connection is worth investigating. Pain that worsens with walking but improves with rest can point toward a gait-compensation mechanism, since the abnormal loading only occurs during movement. Lateral hip pain, the kind felt along the outside of the thigh or near the bony prominence at the side of the hip, frequently reflects overworked hip abductors compensating for a knee that cannot share the load properly.

On the other hand, hip pain that preceded the knee injury, deep groin pain that worsens with hip rotation, or mechanical symptoms like clicking and catching within the hip joint itself are more suggestive of a primary hip problem. In practice, the two can coexist: someone may have an age-related labral change that was painless for years, only to become symptomatic once a knee injury altered their gait enough to load the hip differently. Sorting out what needs treatment and what is incidental is one of the trickier aspects of managing lower-extremity pain, and it is why a thorough physical examination that includes both the knee and the hip remains more valuable than any single imaging study.