Knee instability — the feeling that the knee buckles, shifts, or gives way — usually points to a problem with the structures that stabilize the joint. The most common cause is an ACL tear, but meniscus injury and kneecap instability can also be responsible. Treatment ranges from physical therapy to ligament reconstruction, matched to your injury and goals.
What is knee instability?
Knee instability is the sensation that the knee buckles, shifts, or gives way — most noticeably when pivoting, cutting, or changing direction. It reflects a loss of the normal restraints that keep the knee stable, and it can range from occasional, subtle shifting to repeated episodes that limit activity and risk further damage to the cartilage and meniscus.
Common causes
- ACL tear: the most common cause — the ACL is a key restraint against the knee shifting during pivoting. See ligament surgery
- Other ligament injuries: MCL, PCL, or combined ligament injuries can contribute to instability
- Meniscus tears: certain tears cause catching and a feeling of buckling. See meniscal procedures
- Patellar instability: a kneecap that slips out of place. See patellofemoral pain & instability
Common symptoms
- The knee buckling or "giving way," especially on uneven ground or when pivoting
- A feeling that the knee will not hold your weight
- Swelling or catching after episodes of instability
- Avoiding cutting, pivoting, or sports because the knee feels unreliable
Treatment options
- Non-surgical care: physical therapy and bracing can stabilize the knee for some patients, particularly with partial injuries or lower activity demands
- Ligament reconstruction or repair: ACL reconstruction (or the BEAR repair for select tears) restores the primary restraint against giving way
- MPFL (medial patellofemoral ligament) reconstruction: similar to ACL reconstruction, MPFL reconstruction utilizes a graft to restore stability, in this case to address patellar instability and dislocation.
- Meniscal repair: when a meniscus tear is contributing to mechanical instability
- Combined procedures: instability with malalignment or cartilage damage may be addressed alongside osteotomy or cartilage repair
Frequently asked questions
What does knee instability mean?
Knee instability is the sensation that the knee buckles, shifts, or "gives way," especially when pivoting, cutting, or changing direction. It usually reflects a problem with the structures that stabilize the knee — most often the ligaments (such as the ACL), but also the meniscus or the kneecap.
What causes a knee to give way?
The most common cause is an ACL tear, which removes a key restraint to the knee shifting during pivoting. Other causes include other ligament injuries, meniscus tears that cause catching and buckling, and patellar (kneecap) instability. Identifying the specific cause is the first step in treatment.
Does knee instability always need surgery?
Not always. Some patients — particularly lower-demand individuals or those with partial injuries — are managed with physical therapy and bracing. Active patients who want to return to cutting and pivoting sports, or who have recurrent giving-way episodes, often benefit from reconstruction or repair. Dr. Gomoll tailors the recommendation to your injury and goals.
How is the cause of instability diagnosed?
Diagnosis combines your history (how and when the knee gives way), a physical examination testing the ligaments and meniscus, and imaging — typically MRI — to identify which structures are injured. The findings guide whether reconstruction, repair, or non-surgical care is best.
Who treats knee instability in New York?
Dr. Andreas Gomoll evaluates and treats knee instability at the Hospital for Special Surgery in New York, with a focus on restoring stability while preserving the natural joint.
Dr. Gomoll evaluates knee instability at the Hospital for Special Surgery, 523 East 72nd Street on Manhattan's Upper East Side. See our location and directions or request an appointment.
Medical disclaimer
This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a board-certified orthopedic surgeon who has reviewed your imaging, history, and physical examination. Individual outcomes vary.