ACL tear — assessment and treatment— full professional article

What is the anterior cruciate ligament (ACL)?

The bony knee has little intrinsic stability.

Stability comes primarily from ligaments within and around the joint that link femur to tibia across motion planes.

The ACL runs within the knee and chiefly limits excessive anterior tibial translation relative to the femur.

The ACL is the most commonly torn knee ligament.

The classic mechanism is a non-contact or contact pivoting injury with valgus and internal rotation, producing anterior tibial shift.

ACL tears are common in football, basketball, tennis, skiing, and related sports. Associated injuries include meniscal tears and chondral damage.

What does an ACL tear mean clinically?

After the acute painful swollen phase, many patients improve functionally, but the dominant long-term complaint is often instability—the knee “gives way” with cutting, uneven ground, or return to sport.

Some patients feel fine day to day until sport attempts, when recurrent instability and effusion recur.

Chronic instability also increases risk of secondary meniscal and cartilage injury.

What is non-operative treatment of an ACL tear?

Rehabilitation focuses on strengthening and neuromuscular control. In young athletes, conservative care often does not restore high-level rotational stability, and reconstruction may be discussed.

Shared decisions weigh age, sports demands, occupation, baseline laxity, and the presence of meniscal or articular cartilage lesions. Persistent pivot-shift instability despite diligent rehab usually favors operative stabilization in active patients.

What happens in ACL reconstruction?

The goal is to restore anterior stability by reconstructing the torn ligament, which is not primarily repaired in the acute adult athletic setting.

A graft substitutes for the native ACL.

Graft tissue can be autograft or allograft from several sources.

Common graft sources for ACL reconstruction:

Hamstring tendons (medial thigh/knee).

Bone–patellar tendon–bone (central third patellar tendon).

Quadriceps tendon autograft.

Allograft tendon from a screened donor—analogous in concept to other transplant tissues.

The graft is fashioned to appropriate length and diameter.

Tunnels are drilled in femur and tibia; the graft is passed and fixed at both ends to recreate the ligament line of action.

Graft selection balances autograft donor-site morbidity, fixation strength, revision risk, and patient preference: hamstring, bone–patellar tendon–bone, quadriceps tendon, and allograft each have established indications; the choice should follow an informed discussion with your surgeon.

Rehabilitation after ACL reconstruction:

Recovery is prolonged, with extensive physiotherapy for range of motion, strength, and return-to-sport criteria.

As a rule of thumb, cutting/pivot sport often requires roughly 9–12 months before safe return.

Early postoperative pain is expected—analgesia and cryotherapy help.

Some surgeons brace in full extension briefly to protect terminal extension; others mobilize immediately—protocols vary.

Many protocols allow full weight-bearing as tolerated early when isolated ACL reconstruction is performed; protected weight-bearing may be required when osteotomy, multiligament repair, or complex meniscal work is added.

If a meniscal repair is performed concurrently, weight-bearing and brace protocols may be more restrictive for several weeks with slower progression.