ACL Tear or Injury

A tear or injury to your anterior cruciate ligament (ACL) means you’ve damaged or ruptured the ligament that helps stabilise your knee joint and connects the femur (thighbone) to the tibia (shinbone).

ACL injuries are serious because they immediately compromise knee function, and the ligament lacks a blood supply to heal.

A partial ACL tear has different outcomes depending on where it occurs in the ligament. Partial tears – especially mid-substance tears, have limited healing potential but can be very manageable, provided you’re willing to potentially modify your activities to protect the joint.

Physiotherapy and lifestyle adjustments can be effective treatment options, particularly if you experience minimal knee instability or maintain a less active lifestyle.

Complete or more serious ACL tears usually require surgery. If you’re an athlete or want complete strength in your knee, surgery is typically recommended to restore stability and allow a return to total activity.

Even partial ACL tears may require surgery if they involve other ligaments, tendons, or your kneecap. Only a thorough evaluation by an experienced orthopaedic surgeon can determine the best treatment approach for your specific injury.

Symptoms of ACL tears and injuries

• A “pop” sound at the moment of injury, followed by immediate pain
• Rapid swelling within the first few hours after injury
• Severe pain that may force you to stop activity immediately
• A feeling of knee instability or “giving way” during movement
• Limited range of motion and difficulty straightening your knee
• Tenderness along the joint line and inability to bear weight

Similar injuries

MCL (Medial Collateral Ligament) injuries mirror ACL symptoms but typically heal without surgery. This ligament runs along the inner side of your knee and, when strained or partially torn, can create similar pain and instability – though usually much less severe than ACL damage.

You won’t typically hear the characteristic “pop” of an ACL tear, and the instability feels different with an MCL injury – more of a side-to-side wobble rather than the front-to-back instability of ACL damage.

Causes of ACL injuries

The ACL typically tears during sudden directional changes or awkward landings that force the knee beyond its normal range of motion. Common scenarios include:

Sports movements

Quick pivoting or cutting manoeuvres in sports like netball, football, basketball, and rugby place enormous strain on the ACL. When athletes plant their feet and rapidly change direction, the force can overwhelm the ligament’s capacity to stabilise the knee.

Landing mechanics

Poor landing technique from jumps or falls – especially with the knee straight or knocked inward – creates dangerous torque through the joint. Female athletes face a higher risk due to anatomical differences affecting landing biomechanics.

Contact injuries

Direct blows to the knee, particularly from the side, can immediately tear the ACL and damage other surrounding tissues. Tackles in football or collisions in skiing produce this injury mechanism through violent joint displacement.

Poor conditioning

Inadequate strength in the quadriceps, hamstrings, and core muscles places extra strain on knee ligaments. Athletes returning to sport without proper fitness levels risk their ACL compensating for weak supporting muscles during explosive movements.

Other contributing factors

• Weight
• Age
• Poor mobility
• Previous injuries

What to do if you suspect an ACL injury

• Stop activity immediately and avoid putting weight on the injured leg
• Apply ice packs for 15-20 minutes every 2-3 hours to reduce swelling
• Compress the knee with an elastic bandage, leaving room for circulation
• Elevate your leg above heart level while resting
• Seek immediate medical attention, especially if you can’t bear weight
• Don’t try to “walk it off” or continue activity – this risks further damage

Physiotherapy treatment

Whether you have surgery or not, you will need some physiotherapy to restore full strength, function, and movement to your knee.

Physiotherapy will also reveal the true weakness of your knee and range of motion, giving you a clearer picture of your injury’s severity.

Your physiotherapy programme will be similarly to this:

Initial phase treatment

Early rehabilitation prioritises swelling management and movement restoration with gentle manual therapy to maintain joint mobility.

Electrical stimulation and soft tissue massage help activate dormant quadriceps muscles, preventing the rapid weakness that often follows ACL injuries.

Protected range-of-motion exercises within pain limits ensure your knee doesn’t stiffen during recovery, and regular icing after activity helps manage any reactive swelling.

Progressive strengthening

Strengthening starts with initial treatment but is bolstered with isometric exercises targeting the quadriceps and hamstrings to build foundational strength.

Balance training and proprioception is crucial alongside strengthening to restore your knee’s natural position, while core stability work supports lower limb function.

Advanced rehabilitation

The final phase prepares you for return to activity through carefully progressed training. Your physiotherapist introduces plyometrics and agility work matched to your sport’s demands to help you return from injury.

Sport-specific movement patterns gradually reintroduce the challenges your knee will face during competition. For instance, running programmes could start with straight lines before adding directional changes under close supervision.

Recovery timeline for ACL tears and injuries

It takes nine to twelve months for your ACL to recover from injury – nine months is the benchmark for your ligament to provide 90% functionality.

At the nine-month mark, you should have no pain or swelling and a full range of motion in the knee. Some weakness is expected under heavy load, but your muscles should compensate (hence the importance of strengthening exercises).

The initial four weeks after surgery are the most important for healing time – you should rest and only move in ways your physiotherapist recommends.

Re-injuring your ACL during recovery could lead to a more severe injury that is only partially restorable with surgery.

Summing up

An ACL injury will spell the end of your immediate activities but not the end of your journey back to the sports and life you love.

Your treatment requirements depend on the severity of the tear, plus your activity demands following recovery. Surgery is necessary for high-level tears, but minor ACL tears and injuries are sometimes treatable with just physiotherapy.

We are always available to help. For more information, get in touch today.