What is ACL Reconstruction?

ACL reconstruction is a surgical procedure used to replace a torn anterior cruciate ligament (ACL). The aim is to restore knee stability and enable a return to sports, work, and daily activities.

The surgeon uses a tendon graft from the patient, such as the hamstring, patellar tendon, or quadriceps tendon, or a donor graft. The surgery is performed arthroscopically, using small incisions and a camera to minimise invasiveness, pain, and recovery time.

After the graft is positioned in tunnels drilled through the thigh and shin bones and secured with screws, it functions as the new ACL, restoring knee stability. Recovery is a lengthy process that often involves physiotherapy, typically taking up to a year to achieve a full return to competitive sports.

For many decades, the teaching and belief were that an injured ACL does not heal. Recent publications have challenged this long-held belief, discussing numerous examples of spontaneous healing of the acutely ruptured ACL, which has led to a new non-surgical approach for managing ACL injuries. Known as the “Cros-Bracing Protocol”, this is explored in detail below.

What happens when it occurs?

When the ACL is torn, the knee loses the ability to control the forward movement of the shin bone (tibia) and rotational stability.

This makes cutting, pivoting, or sudden stopping difficult and unsafe.

Reconstruction creates a new ligament using the graft, which is positioned and fixed inside the knee to mimic the natural ACL.

Common causes and risk factors for ACL injury

  • Sudden pivoting or twisting movements
  • Awkward landings from jumps
  • Rapid deceleration while running
  • Contact injuries in sports such as football, rugby, or netball
  • Previous ACL injury or family history of ligament injuries

Who is most affected?

Active young adults, athletes in pivoting sports, and individuals with ongoing instability after an ACL tear.

Some people with less demanding lifestyles may be able to manage without surgery. Still, reconstruction is typically recommended for individuals who wish to return to cutting and pivoting sports.

Typical symptoms before surgery

  • Knee instability or giving way with sport or quick direction changes
  • Difficulty returning to running, jumping, or twisting sports
  • Reduced confidence in the knee

When to consider surgery

  • Persistent instability despite rehabilitation
  • Desire to return to sport that requires pivoting, cutting, or contact
  • Associated injuries such as meniscus, cartilage, or multiple ligaments

How ACL Reconstruction is performed

The surgeon harvests a tendon graft and places it inside the knee using small incisions and arthroscopy, also called keyhole surgery. The graft is anchored into tunnels drilled in the femur and tibia. The procedure typically takes one to two hours, and most patients are discharged the same day or after one night in the hospital.

Graft Options

  • Autograft: A graft taken from your own body, such as the hamstring or patellar tendon.
  • Allograft: A graft from a deceased donor (cadaver).
  • Synthetic Graft: Artificial ligament materials can also be used, though their long-term reliability is still being studied.

Rehabilitation after ACL Reconstruction

Rehabilitation is a crucial factor in achieving a successful recovery. At Spinal and Sports Care, your plan is structured into clear phases:

Phase 1, zero to six weeks: swelling control, full extension, gradual return of flexion, gentle activation of quadriceps and hamstrings, and safe walking without crutches.

Phase 2, six to twelve weeks: progressing strength, balance, and controlled gym-based exercises.

Phase 3, three to six months: running, agility, sport-specific drills, and higher-level strengthening.

Phase 4, six to twelve months: full return to sport, with testing of strength, hop performance, and agility before clearance.

Timeframes vary between individuals. Most return to sport takes nine to twelve months.

Prevention of re-injury

  • Ongoing neuromuscular training
  • Balance and landing technique work
  • Strength maintenance programs
  • Adherence to a structured return to sport plan

Latest insights

Structured rehabilitation alone may be successful for some individuals.

For individuals aiming to pivot into sports, reconstruction combined with comprehensive rehabilitation remains the standard approach.

Newer surgical techniques focus on graft preservation and restoring natural ligament anatomy.

Cross Bracing protocol (CBP)

The Cross Bracing Protocol (CBP) is a non-surgical rehabilitation program for ACL injuries that immobilises the knee at 90 degrees of flexion for several weeks to promote tissue healing between the ruptured ligament remnants. The primary goal is to create a "closed reduction" of the ACL by bringing the ruptured ligament remnants into close proximity. This proximity is thought to create an environment where new tissue can bridge the gap and the ligament can heal.

The protocol then gradually increases the knee's range of motion each week, combined with progressive weight-bearing and physiotherapy, to restore function and enable a return to sport. This approach requires close supervision by sports doctors and treating physiotherapists, as the specific CBP timeline can vary based on individual factors and MRI findings.

A key aspect of the CBP is the initial period of non-weight-bearing, usually for the first six weeks, and the importance of physician supervision to manage risks like deep vein thrombosis (DVT). This treatment option is available to patients for the potential healing of Acute Anterior Cruciate Ligament (ACL) rupture, as classified on MRI.

Frequently Asked Questions

Timeframes depend on the procedure and your starting capacity. We progress when pain is controlled, swelling is down, and movement and strength targets are met. Expect a structured plan and criteria to guide you more than the calendar.

Yes, inside your plan. Keep pain during activity at or below 3 out of 10 and ensure it is no worse than the next morning. Use supports and aids as directed.

Imaging is used in conjunction with surgical decisions or when progress stalls. Your clinician will advise on whether an X-ray, ultrasound, CT scan, or MRI is most useful.

They protect healing tissue in early phases. We reduce support as control and strength improve, then remove them for strengthening and gait retraining. You will be guided by your surgeon and health care practitioner.

Ice helps early when swelling and pain dominate. Heat helps later when stiffness is the main issue.

If the pain is 2 out of 10 or less the next morning, swelling is stable, strength is within 90 per cent of the other side, and you pass your functional tests for the procedure.

Cut the next session’s volume by 20 to 30 per cent, keep your strength work, elevate and ice, then retest the following day.

Most people return in stages. Drive when you can load and move the knee safely and brake firmly without pain, and when medications do not impair you. Your clinician and surgeon will provide guidance.