Orthotics are specialized shoe inserts designed to alter the mechanical forces acting on the foot and lower leg. These devices, which can be custom-made or purchased over-the-counter, primarily aim to correct abnormal foot mechanics, such as excessive rolling inward or outward. The body functions as a unified system known as the kinetic chain, where the alignment of the feet directly influences the ankles, knees, hips, and even the lower back. While orthotics are intended to relieve existing pain by improving alignment, they introduce a significant mechanical change that can transfer stress and create new discomfort, including knee pain.
The Foot-Knee Connection
The foot acts as the foundation for the entire leg, and its alignment is directly linked to the rotation of the tibia and femur, which form the knee joint. When the foot excessively pronates, or rolls inward, it causes the lower leg to rotate internally. This rotational force increases stress on structures within the knee, particularly the patellofemoral joint and the surrounding soft tissues. This misalignment is a common factor in conditions like patellofemoral pain syndrome, often called “runner’s knee,” and can also contribute to tension in the iliotibial (IT) band. Conversely, excessive supination, where the foot rolls outward, can reduce the body’s natural shock absorption, leading to greater impact forces traveling up the leg to the knee. Correcting the foot’s position is intended to reduce this detrimental rotation and force.
Factors That Lead to Orthotic-Induced Knee Pain
The primary reason an orthotic causes new knee pain is that the device introduces an unintended mechanical error into the kinetic chain. One common issue is overcorrection, where the orthotic pushes the foot too aggressively into a corrected position. If a device is designed to curb excessive pronation but is too forceful, it can shift the stress from the medial (inner) side of the knee to the lateral (outer) side. This shift can overload tissues that were previously unstressed, leading to new localized pain.
The physical design and fit of the device are also frequent sources of problems. An orthotic that is poorly contoured, too rigid, or does not match the specific biomechanical needs of the user will not provide optimal support. An improper fit can create localized pressure points that force the entire leg to compensate, resulting in an unnatural gait and subsequent knee strain. Over-the-counter devices, which lack the precise measurements of custom orthotics, are particularly susceptible to this issue.
Incompatibility with footwear can further undermine the orthotic’s function. An orthotic requires a shoe with adequate depth and a stable base to seat correctly and maintain the intended alignment. If a thick orthotic is placed in a shoe with insufficient volume, the foot can be pushed too high or tilted laterally. This improper seating disrupts the device’s corrective geometry and can create a destabilizing effect, causing the knee to work harder to maintain balance.
Distinguishing Normal Adjustment from Harmful Pain
When starting to wear new orthotics, some minor discomfort is expected as the body adapts to the new alignment. The initial period requires muscles, tendons, and joints to adjust to the corrected biomechanical position, often engaging muscle groups in new ways. This normal adjustment phase typically involves a mild, generalized muscle fatigue or a feeling of “tiredness” in the feet, calves, or shins.
For most people, this minor discomfort should gradually subside within a two to four-week break-in period. It is recommended to introduce the orthotics gradually, increasing wear time by an hour or two each day. The presence of sharp, intense, or highly localized pain, however, should be viewed as a warning sign.
Pain concentrated around the kneecap, on the sides of the knee joint, or pain that increases in severity is not part of a normal adjustment. If generalized discomfort persists beyond four to six weeks, or if it immediately manifests as sharp new knee pain, it suggests the orthotic is causing a harmful alignment. In these instances, the device requires professional evaluation.
Corrective Measures and Professional Guidance
If an orthotic is causing significant knee pain, the immediate step is to reduce wear time and temporarily revert to more comfortable footwear. This allows the aggravated tissues around the knee to calm down. Users should also ensure the orthotic is correctly seated within the shoe, fully pushed back against the heel counter, and that the shoe itself is laced securely.
The next action is to return to the prescribing specialist, such as a podiatrist, pedorthist, or orthopedist. The goal is rarely to discard the device, but rather to modify it. Specialists can adjust the orthotic’s geometry by grinding down material in areas of overcorrection or adding padding to support the foot’s contours. These modifications are often subtle but can dramatically change the force vectors traveling up to the knee.
Custom orthotics are dynamic medical devices that require follow-up appointments because the body’s response to the initial correction cannot be perfectly predicted. Achieving optimal alignment and pain relief frequently involves one or more minor adjustments. Working with a professional who can assess the interaction between the orthotic, the foot, and the knee is the most effective way to achieve successful treatment.