8 Causes of Knee Hyperextension in Neurology

Knee recurvatum, or knee hyperextension during the stance phase, is a gait alteration that we frequently observe in adult neurological rehabilitation. Visible to the naked eye, this phenomenon is not a pathology in itself, but rather the observable effect of an underlying cause, which is essential to identify in order to propose an effective correction strategy.

In this article, we review 8 causes or contributing factors of knee recurvatum, derived from 22 years of clinical experience in neurology.

What is Knee Recurvatum?

During the stance phase of the step, instead of remaining slightly flexed, the knee locks in hyperextension. This posture can be forced (physical effect) or voluntarily adopted (functional compensation). Recurvatum is often a multifactorial symptom.

4 “Mechanical” Causes of Recurvatum (Physical Effect)

These first causes correspond to biomechanical constraints that force the knee to hyperextend to allow progression.

1. Limitation of Ankle Dorsiflexion

• Possible origins: hypertonia of the triceps surae, muscle stiffness, tendon retraction, joint limitation (e.g., arthrodesis).
• Consequence: the leg cannot advance properly over the foot, the knee moves backward to compensate. (limits pivoting on the ankle)

2. Quadriceps Hypertonia

• The knee extensor muscle pushes excessively into extension.

3. Hamstring Weakness

• The flexor muscles no longer sufficiently brake the knee extension.

4. Foot Dorsiflexor Deficit

• The foot dorsiflexor action allows the forward movement of the tibia and knee during the early stance phase.

4 “Functional” Causes of Recurvatum (Useful Compensations)

In these cases, hyperextension is a functional strategy adopted by the patient to secure support.

5. Cerebellar Syndrome

• To limit degrees of freedom and stabilize the leg, the patient voluntarily locks their knee.

6. Weakness of Knee Extensors

• Recurvatum allows the knee to “lock” without muscular effort, thus ensuring stable support despite quadriceps weakness.

7. Pain in the Forefoot

• The patient avoids anterior support and places weight on the rear, promoting knee backward movement.

8. Fear of Knee Failure

• The patient, fearing a fall, locks the knee in hyperextension to secure the stance phase even if strength is normal.

Why Identifying the Cause is Essential

Understanding the cause of recurvatum allows for choosing a targeted therapeutic approach:

• Joint mobility work (ankle, knee)
• Muscle strengthening (hamstrings, quadriceps)
• Gait pattern education
• Postural and proprioceptive correction
• Adapted technical aids, such as the Wheeleo®, which promote smoother and more symmetrical progression, limiting certain inappropriate compensations.

Conclusion

Knee recurvatum is never trivial: it reflects an imbalance that needs to be analyzed carefully. Whether it is the consequence of a deficit, hypertonia, or an adaptation strategy, it is essential to understand the cause to better support the patient towards a more functional and secure gait.

What about you? What causes of recurvatum have you encountered in your practice?
Share your observations in our LinkedIn group for Wheeleo professionals or join our user community on Facebook.