Can Genu Recurvatum Cause Sporadic Unilateral Posterior Knee Buckling During Non-Athletic Activities?

Recently, I have noticed an interesting phenomenon with my right knee that is not present in the left knee. When seated with my feet on the floor and my legs at a 90-degree angle, I extended my knees one by one while keeping the other leg straight. Both knees had a click at full extension, but the right knee exhibited significant external rotation, with the lower leg/foot moving toward the midline. The left knee extended without any rotation, and both knees exhibited crepitus in the lateral patellotibial ligaments without any pain, either at rest or during activity. This observation raises several questions about the underlying mechanisms and potential conditions. Given my background in health science, especially in anatomy, myology, and physiology, I am keen to understand the root cause of this issue.

Background and Mechanisms

I recently acquired a bicycle for the first time since childhood, and I have been riding it about 5-7 times a month, each session lasting 30-40 minutes in both directions, during the spring and fall seasons. During this period, I wonder if the seat height might have been too low, especially given my disproportionately long legs. Initial expert advice during the bike purchasing process indicated that my knees could become an issue at some point, but due to lack of bike stock and inadequate seat adjustments, this hypothesis remains unverified. It is intriguing to consider if this suggests that the knee buckling might be related to the bicycle, though logically, one side would be far worse if this were the case, given that my right side is the non-dominant one.

Understanding Genu Recurvatum

Genu recurvatum, often referred to as knee hyperextension, is a condition in which the knee is unable to fully extend. It can be either functional or pathological. In the case of functional genu recurvatum, it is usually a postural issue that can be corrected by exercises or braces. However, in pathological cases, it can be associated with certain medical conditions or structural abnormalities in the knee, such as ligament laxity or patellar instability. The condition can lead to mechanical changes, including altered load distribution and alignment issues that may contribute to various symptoms, including knee buckling.

Causes of Sporadic Unilateral Posterior Knee Buckling

Your observation of sporadic unilateral posterior knee buckling might be linked to genu recurvatum if the hyperextension is causing the tibia to shift inward and twist the knee toward the midline, especially if there is increased stress or strain on one side. This could occur during specific activities, such as riding a bicycle with an improper seat height, leading to abnormal stress patterns on the knee joints. Symptoms like clicking (crepitus) and posterior knee buckling could indicate changes in joint mechanics, such as ligament laxity or meniscal issues.

Seeking Specialist Advice

To gain a better understanding of the underlying cause of knee buckling and to rule out any potential medical conditions, a visit to a specialist would be advisable. Given the complexity of knee issues, consulting an orthopedic surgeon or a physical therapist would be the ideal choice. Orthopedic surgeons specialize in musculoskeletal conditions, including joint problems, while physical therapists can provide detailed assessments of knee mechanics and recommend appropriate treatments or exercises to address the condition.

Conclusion

The observed phenomenon with my knee, although not painful, is concerning given the mechanical differences observed in each leg. Understanding the root cause may require specialized medical assessment. Considering the factors, such as the recent engagement in cycling and the history of genu recurvatum, may provide valuable insights. By seeking advice from specialist orthopedists or physical therapists, further diagnostic evaluations can be performed to address the issue effectively.