What is the difference between a partial and a complete ACL tear?

How the two injuries differ

The ACL is made of two bundles of fibres that work together. A partial tear damages part of one or both bundles, while the rest continues to hold the knee. A complete tear, sometimes called a rupture, separates the ligament fully, and the ends do not usually reconnect.

Complete tears are much more common than true partial tears. Some injuries that look partial on an early scan turn out to behave like complete tears once the swelling settles.

Side-by-side comparison

• Stability: partial tears are often stable on examination; complete tears usually show clear looseness
• Symptoms: both can swell and hurt at first; giving way with turning is more typical of complete tears
• First treatment: partial tears usually start with physiotherapy; complete tears may be treated with physiotherapy or reconstruction depending on goals
• Return to sport: partial tears often return within a few months after rehabilitation; complete tears treated with surgery usually take around 9 to 12 months
• Follow-up: a partial tear needs re-checking, because some progress to functional instability

Why the examination decides

What matters is how much the remaining fibres control the knee. Dr. Gelber compares the injured knee with the other side using the Lachman and pivot-shift tests. A partial tear with a firm end point and no pivot shift usually does well with rehabilitation. A so-called partial tear with a clear pivot shift behaves more like a complete one.

What to do if you have been told it is partial

Follow a structured rehabilitation programme, avoid pivoting sports until strength and control tests are passed, and report any episode of the knee giving way. A review at Aman Hospital after several weeks of rehabilitation helps confirm that the knee is behaving like a stable partial tear.