I’ve been a physical therapist for over 20 years and whether it’s skiing, basketball, soccer. I hear similar ways of how my clients tore or ruptured their ACL.

“I came down on my leg funny and I felt a ‘pop’.”

“My foot was planted and I got hit on the outside of my knee.”

“I fell skiing and my ski twisted, taking the knee with it.”

Most say they felt and/or heard a distinctive pop. That’s the ACL rupturing or disattaching.

All say that right away, their knee felt unstable, like it wanted to buckle forward. Ruptured ACL? There goes a lot of your knee stability.

That position of the foot planted and the knee buckling inward is called  “valgus” or knock-kneed position, and is the classic position for spraining, tearing or rupturing your anterior cruciate ligament. Applying a lateral, outside force to a valgus-positioned knee further strains the ACL. Think about that football player that gets “clipped” by another player with the cleat firmly planted in the turf. Pop!

Other classic signs of a torn ACL include swelling, often in an inverted “C’ shape beneath the kneecap. 

As far as loss of motion, yes, knee flexion or bending the heal back to the butt, becomes difficult, as the quadricep tries to protect or  “guard” knee flexion because of pain. Full knee extension or hyperextension, is also usually lost. Laying on your back without a towel or pillow beneath your knee may prove uncomfortable, the knee again avoiding extension or “hyperextension.”

ACL Tip:  Suspect an ACL injury? Ere on the side of caution. Brace, crutches and exam…do it! Chronic instability (giving way or buckling) can injure surrounding tissue, weaken leg muscles and drastically throw off your performance due to pain, altered balance and apprehension, always wondering,  “Is it going to buckle again?”

So, clinical symptoms of a ruptured (partial or full) ACL include:

  • The classic “pop” sound
  • Pain deep within the knee joint
  • Swelling around and under the knee
  • Instability of the knee joint
  • Loss of motion at the knee joint

A Physical Therapist’s Perspective on ACLs and Lower Back Pain: 

PROBLEM: “It’s not just my ACL . My lower back is starting to hurt!” Many of my ACL clients complain of lower back pain, usually on the opposite side of the injured knee. This happens because they are weight bearing more on one side of their leg vs. the other, putting more pressure/load on the sacroiliac joint and spine. Basically, they’ve temporarily lost weight bearing symmetry.  

Fix: Take lots of breaks. Stretch the  hips and lower back. Consult a PT who loves knees and treats the entire body to re-establish balance, strength, core control and alignment — and delivers great bodywork (soft and deep tissue massage, stretching) to calm down irritated tissue. 

Knee instability. Contact us. We love knees!

Follow our ACL blog and follow what 4 of our clients when through, from injury to reaching functional milestones.

Next blog: “Why Did I Go Skiing?” Bianca’s Story.