All-Inside ACL Reconstruction, Internal Brace and LET

All-inside ACL reconstruction replaces the full-length bone tunnels of traditional surgery with short sockets drilled only as deep as the graft requires, with fixation on the outer surface of the bone. It preserves bone, suits knees with poor bone stock or revision surgery, and, combined with a fibre tape internal brace, lets patients bear weight and walk from the first day after surgery.

For Dr. Vipin Maheshwari, Sr. Consultant - Orthopaedics, Artemis Hospitals, Gurugram, India, the anterior cruciate ligament (ACL) is where the evolution of arthroscopy is easiest to see: from tunnels to sockets, from a graft working alone to a graft protected by an internal brace, and from a single central reconstruction to one backed by lateral extra-articular tenodesis (LET) for rotational control. This article follows that evolution, explains why ACL reconstructions fail, and sets out the recovery timeline. It belongs to a series whose complete guide to knee and shoulder arthroscopy gives the overview; the meniscus and cartilage article covers the structures most often injured alongside the ACL.

From tunnels to anatomical ACL reconstruction

The ACL is the ligament in the centre of the knee that stops the shin bone sliding forward on the thigh bone. When it tears, it is usually reconstructed with a graft, a tendon that takes the ligament's place.

Early reconstructions drilled the tibial tunnel first and passed through it to the femur, taking an "over the top" route. That approach did not reproduce the native ligament's anatomy. Anatomical ACL reconstruction followed: the femoral tunnel moved lower and further back on the side wall of the notch, so that the anteromedial bundle, the part of the ligament reconstructed in most operations, sits where the native fibres attach.

What is all-inside ACL reconstruction?

All-inside reconstruction does not drill complete tunnels through the bone. Instead:

1. Two independent sockets are cut, one in the femur and one in the tibia, using a retrograde drill that creates a socket just large enough for the graft, rather than a tunnel running through and through.
2. Each socket is tailored to the graft, so the surgeon can individualise its length on both sides.
3. The graft is prepared and passed through the joint, then pulled into the femoral and tibial sockets.
4. Fixation is cortical, with buttons resting on the hard outer layer of bone rather than screws in the soft marrow; sutures hold the graft inside the sockets.

The first advantage is less bone loss. The second, which Dr. Maheshwari stresses, is timing. ACL injuries are usually accompanied by bone marrow oedema, swelling within the spongy bone, and many surgeons wait three to six weeks, some up to three months, for it to settle before reconstructing. In his view, that wait puts the meniscus at risk. Because all-inside fixation sits on the cortex rather than in the marrow, poor bone quality does not loosen the graft, and surgery need not be delayed. The same reasoning makes the technique valuable in revision surgery and wherever bone stock is doubtful.

How internal bracing protects the ACL graft

An internal brace is a strong synthetic fibre tape placed alongside the graft. Dr. Maheshwari's technique:

1. The fibre tape is loaded into the femoral button and brought out on the tibial side alongside the graft.
2. The tendon graft is fixed first.
3. The knee is taken into full extension, the fibre tape is tightened further, and it is fixed to the tibia with a separate suture anchor.

Because the tape is tighter than the graft, it becomes the primary restraint. The first stress falls on the tape, not on the healing tendon. Over roughly the first three months, while bone grows around the graft, the brace prevents the graft from loosening, stretching or cutting through.

Dr. Maheshwari describes the brace as a load-sharing device that helps early healing, increases the strength of the construct and prevents elongation of the graft. He uses it particularly in high-risk patients: those who may not follow restrictions, and athletes who want to return to sport early. His closing advice to surgeons makes the same point: if a patient is a sportsperson who will not wait before returning to very active sport, reinforce the reconstruction with fibre tape.

The hybrid construct and rotational augmentation

The reconstruction can be built as a hybrid, combining a tendon graft with synthetic augmentation, and extended with rotational augmentation outside the joint (LET, below). Each element addresses a different way the reconstruction can fail.

Synthetic grafts for ACL reconstruction

Graft supply is a real constraint. Patients with multiligament injuries need several grafts, and the body's sources are limited. Some patients are also reluctant to have a tendon harvested.

For these patients Dr. Maheshwari considers synthetic ACL grafts made of polyethylene terephthalate a sound option. The advantages he described:

• Strength: testing has shown them equal to, or stronger than, the usual hamstring, peroneus longus or quadriceps tendon grafts.
• No harvest: no tendon is taken, so there is no donor-site morbidity and the operation is markedly shorter.
• Tissue ingrowth: the graft has a mesh-like structure into which the patient's tissue slowly grows.
• Little elongation: as an artificial material, it stretches far less than a tendon.
• Rapid recovery.

Synthetic ligaments remain more debated in the wider literature than tendon autografts, and long-term evidence is more limited, which is why they are generally reserved for selected cases such as multiligament reconstruction or a shortage of graft.

Which graft is best for ACL reconstruction?

Hamstring tendons have been the graft of choice since the early days of arthroscopy, and Dr. Maheshwari still regards them as a major option. For multiligament reconstruction, the peroneus longus tendon or the quadriceps tendon can be used. He does not usually advise the tensor fascia lata for ACL reconstruction. Where graft options are limited, for example because of an injury to the other leg, a synthetic graft is the alternative.

Lateral extra-articular tenodesis: adding rotational stability

The ACL is a central structure and contributes relatively little rotational stability. LET adds a restraint on the outside of the knee that controls rotation, protecting the ACL reconstruction inside.

Who needs LET?

Not every ACL patient does. Dr. Maheshwari adds LET when:

• The pivot shift test is high grade, grade three, a sign of marked rotational instability.
• The knee hyperextends.
• The patient is a high-demand, pivoting athlete, such as a footballer or badminton player, especially with a grossly positive anterior drawer test in which the tibia can be moved freely forwards and backwards.
• The tibial slope is steep on X-ray. A steeper slope increases the strain on the ACL, and he considers this a strong reason to add rotational control.
• The patient is a child whose growth plates are open. When there is too little room in the epiphysis to drill without crossing the physis, LET alone gives the knee considerable stability until the child is skeletally mature and the growth plates are about to close; the ACL can then be reconstructed. Current consensus cautions against prolonged delay in a child with an unstable knee, because a deficient knee accumulates meniscal and cartilage damage, and favours physeal-sparing reconstruction where instability persists.

His message to surgeons is direct: in an active patient going into contact sport, always think about rotational stability. Without it, no matter how good or strong the graft, reconstructions tend to fail.

The modified Lemaire technique

Dr. Maheshwari uses the modified Lemaire technique. A strip of the iliotibial band, the thick band of fibrous tissue on the outer thigh, is passed deep to the lateral collateral ligament and fixed to the femur. The result is a rotational restraint outside the joint that complements the ACL graft inside it.

Why ACL reconstructions fail

Failure analysis is, in his words, the biggest thing sports injury surgeons look at. He highlighted six causes:

1. Tunnel position. In a single-bundle reconstruction the femoral tunnel must be posterior and inferior, and the tibial tunnel posterior; an anterior tibial tunnel that runs into the intermeniscal ligament is a mistake.
2. A missed meniscal tear. He identifies meniscal injury as the most common cause of pain after ACL reconstruction. Root tears and ramp lesions are easily missed on MRI and examination; patients remain unhappy, report that they are still in pain despite surgery, and can return later with a large bucket handle tear.
3. A steep tibial slope left without rotational protection; an LET should be considered.
4. Graft choice.
5. No rotational stability in an active athlete.
6. Returning too early. Patients who return to pivoting sport before about nine months, and before strength and function have recovered, put even a strong graft at risk.

The meniscal tears that lie behind the second cause, and the routine posteromedial portal Dr. Maheshwari uses to find them, are described in the meniscus and cartilage article.

ACL repair versus reconstruction: keeping the patient's own ligament

The direction of travel, Dr. Maheshwari said, is from replacing ligaments to stitching them back. If a patient with a fresh ACL tear reaches a surgeon within two to three weeks of injury, the ligament can often be repaired rather than reconstructed, and the patient keeps the ACL they were born with, which he considers the best ligament a patient can have. Primary ACL repair is generally suited to tears close to the ligament's attachment on the femur with good tissue quality; reconstruction remains the standard treatment for most ACL tears. Speed of diagnosis therefore matters: a high-energy injury with severe pain warrants an early MRI rather than a wait-and-see approach.

PCL reconstruction

The posterior cruciate ligament (PCL) prevents the tibia from sliding backwards. Dr. Maheshwari treats ACL and PCL surgery as close relatives: the evolution of implants and grafts has been the same for both, and he quoted the same cost and success figures for a single-ligament reconstruction of either.

Recovery after ACL reconstruction

With an all-inside reconstruction and fibre tape augmentation, Dr. Maheshwari described this timeline:

• Day one: the patient bears full weight and walks.
• The first three to four days: a walking stick until the pain settles, then normal walking.
• The following weeks: structured physiotherapy and rehabilitation, which he insists are part of the operation rather than optional extras; every case differs.
• About six weeks: the graft becomes solidly incorporated into bone.
• Three months: running and jogging can begin, and not before then. Return to pivoting or contact sport is generally deferred until at least nine months and until objective strength and hop tests are passed, because earlier return sharply increases the risk of re-injury.

Rehabilitation planning and costs are covered on the physiotherapy and rehabilitation cost page.

ACL reconstruction success rate and cost

Dr. Maheshwari put the success rate of ACL or PCL reconstruction at about 98 to 99%, defining success as a return to the patient's condition before the injury. Published series report that about two in three patients return to their pre-injury level of sport after ACL reconstruction, so outcomes vary with the patient, the sport and rehabilitation. He gave an approximate all-inclusive cost of USD 4,000 to 4,500 for a single-ligament reconstruction at Artemis Hospitals; the complete guide sets out costs across procedures, and benchmarks are on the ACL reconstruction cost page. The questions doctors raised in the session, including recovery after ligament surgery, are answered in the Live Discussion. Dr. Rohit Lamba's guide to orthopaedic disorders places ligament injuries in the wider spectrum of bone and joint conditions.