My knee still won't straighten fully weeks after ACL surgery. Is that normal?

Why full straightening matters so much

A knee that stays even slightly bent makes you limp, overloads the front of the knee and the thigh muscle, and can cause lasting aching. Full extension is the first priority of rehabilitation because it is harder to regain the longer it is missing. Bending usually comes back more easily later.

Common reasons the knee will not straighten

• Swelling and pain, which make the thigh muscle switch off and the hamstrings tighten
• Sleeping or resting with a pillow under the knee
• Not doing extension exercises often enough through the day
• A cyclops lesion, a small nodule of scar tissue at the front of the graft that blocks the last degrees
• Generalised scar tissue in the joint, sometimes called arthrofibrosis
• Rarely, graft position or a meniscus problem

What you can do now

Lie on your back with the heel resting on a rolled towel and the back of the knee unsupported, for several minutes at a time, many times a day. Tighten the thigh muscle to push the back of the knee down. Control swelling with ice and elevation, and keep up the quadriceps exercises your physiotherapist has given you.

Tell your physiotherapist and the surgical team early if progress stalls. Do not force painful stretching on your own.

When review is needed and what it involves

Arrange a review if the knee is still clearly bent at six weeks, if extension is getting worse, or if you feel a block with a clunk at the end of straightening. At Aman Hospital, Dr. Gelber measures the range of movement, checks the graft and may request an MRI.

Most cases improve with focused physiotherapy. If a cyclops lesion or scar tissue is the cause, a short arthroscopic procedure to clear it is sometimes needed.