Knee Instability After ACL Reconstruction: Causes and Solutions

Knee instability after anterior cruciate ligament reconstruction?

Dear Doctor, Happy New Year! I underwent anterior cruciate ligament reconstruction surgery on December 12, 2018, and it has been nearly 9 weeks since the procedure.
My knee joint is still somewhat swollen.
Currently, I can bend my knee to over 140 degrees, but when trying to straighten it, I need to exert force from my thigh and endure pain to get close to zero degrees.
I have been following my rehabilitation program, although I was a bit lazy during the Lunar New Year period.
My thigh muscles seem to be gradually forming, but I still feel a looseness and instability in my knee joint, similar to what I experienced before the surgery.
I am concerned whether this is due to insufficient muscle strength, poor healing of the reconstructed ligament, or an inadvertent rupture (I have not engaged in any intense collisions or pulls post-surgery).
I feel very anxious about this and kindly ask for your advice.
Thank you!

Luo Dai Wang Zi, 40~49 year old female. Ask Date: 2019/02/11

Dr. You Dianqi reply Orthopedics

Happy New Year, Prince Lode! You underwent reconstruction surgery for your right knee anterior cruciate ligament on December 12, 2018.
There is still some swelling in your knee joint, and your main concern is the persistent feeling of looseness, which is similar to what you experienced before the surgery.
I believe that you are currently feeling quite anxious, which is affecting your daily life.
My personal suggestion is to discuss this situation with your physician and actively participate in the rehabilitation program.
If this condition gradually improves, you can feel more at ease.
However, if the same degree of looseness continues to persist, and your physician's physical examination confirms that your knee remains unstable after the normal postoperative recovery period and the swelling has subsided, it may be worth discussing with your attending physician the possibility of undergoing a more detailed imaging study.
I hope you recover soon.

Reply Date: 2019/02/11

More Info

Knee instability after ACL reconstruction can be a concerning issue for many patients, especially when they experience persistent swelling, pain, and a feeling of looseness in the knee joint. Understanding the potential causes of this instability and exploring solutions is crucial for recovery.

Firstly, it’s important to recognize that the feeling of instability can stem from several factors. One common cause is inadequate muscle strength around the knee. After ACL reconstruction, the surrounding muscles, particularly the quadriceps and hamstrings, may take time to regain their strength and coordination. Weakness in these muscle groups can lead to a lack of support for the knee joint, resulting in a sensation of instability. Engaging in a structured rehabilitation program that focuses on strengthening these muscles is essential. Exercises such as leg presses, squats, and step-ups can help improve muscle strength and stability.

Another potential cause of knee instability is the quality of the surgical reconstruction itself. While ACL reconstruction aims to restore stability to the knee, factors such as graft placement, tension, and healing can affect the outcome. If the graft is not properly integrated into the bone or if there is excessive laxity in the graft, it may not provide the necessary stability. In some cases, patients may experience a re-tear of the ACL, even without significant trauma. This can lead to a return of instability symptoms. If you suspect that your graft may not be healing properly, it is crucial to discuss this with your orthopedic surgeon. They may recommend imaging studies, such as an MRI, to assess the integrity of the graft.

Additionally, the presence of swelling in the knee can contribute to feelings of instability. Swelling often indicates inflammation, which can affect joint mechanics and lead to discomfort during movement. Managing swelling through rest, ice, compression, and elevation (RICE) can be beneficial. If swelling persists, it may be worthwhile to consult with your physician to rule out any underlying issues, such as joint effusion or synovitis.

In terms of rehabilitation, it’s important to adhere to a progressive program that gradually increases the intensity of exercises. While it’s understandable that holiday periods may disrupt routine, consistency is key to recovery. Incorporating balance and proprioception exercises, such as single-leg stands or using a balance board, can also enhance stability and coordination.

Lastly, psychological factors can play a role in the perception of knee instability. Anxiety about re-injury or the fear of movement can lead to guarded behavior, which may further exacerbate feelings of instability. Engaging in mental conditioning or working with a sports psychologist can help address these concerns.

In summary, knee instability after ACL reconstruction can be attributed to muscle weakness, graft integrity, persistent swelling, and psychological factors. A comprehensive approach that includes strength training, proper management of swelling, adherence to rehabilitation protocols, and addressing any psychological barriers will be essential for improving knee stability. If concerns persist, it is advisable to follow up with your orthopedic surgeon for further evaluation and tailored recommendations.

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