ACL TEAR1 (1).ppt

DR.NAIF S. ALAFFARI

S.V DR. AMRO ALHIBSHI

The exact incidence of ACL injuries is unknown; however, it has been estimated that 200,000 are torn each year, and 100,000 ACL reconstructions are done each year in the United States .

The controversy for managing this injury now centers more on the choice of graft selection for reconstruction instead of whether surgery is necessary .

The ACL inserts on the tibial plateau, medial to the insertion of the anterior horn of the lateral meniscus .

The tibial attachment site is larger and more secure than the femoral site .

The ligament is 31 to 35 mm in length and 31.3 mm2 in cross section .

The primary blood supply to the ligament is from the middle geniculate artery, which pierces the posterior capsule and enters the intercondylar notch near the femoral attachment.

Additional supply comes from the retropatellar fat pad via the inferior medial and lateral geniculate arteries.

The osseous attachments of the anterior cruciate ligament contribute little to its vascularity.

The posterior articular nerve, a branch of the tibial nerve, innervates the ACL.

Mechanoreceptors also have been identified on the surface of the ligament, mostly at the insertions of the ligament (especially femoral), well beneath the external synovial sheath.

From anterior and central tibia

to posterior and medial aspect of LFC

ACL

L

Femoral insertion

on LFC along the cartilage contour

18 mm long (± 2 mm)

9 mm wide (± 1 mm)

Just medial to the anterior horn of the lateral meniscus

17 mm long (± 2 mm)

9 mm wide (± 2 mm)

Tibial Insertion

Anteromedial bundle

Posterolateralbundle

2 major bundles: anteromedial (AM) posterolateral(PL)

AM

PL

AM

PL

Femoral insertion AM: anterior and proximal

PL: posterior and distal

The ACL is the primary restraint to anterior tibial displacement, accounting for approximately 85% of the resistance to the anterior drawer test when the knee is at 90 degrees of flexion and neutral rotation.

The anteromedial band is tight in flexion, while the posterolateral portion is tight in extension.

Tension in the ACL is least at 30 to 40 degrees of knee flexion.

The ACL also functions as a secondary restraint on tibial rotation and varus-valgus angulation at full extension.

It has proprioceptive function as evidenced by the presence of mechanoreceptors in the ligament. These nerve endings may provide the afferent arc for postural changes of the knee through deformations within the ligament.

The exact contributions of the receptors have not been clearly defined.

Noyes, in a comprehensive biomechanical study, determined the ultimate load to be 1725 ± 269 N; the stiffness, 182 ± 33 N/mm; and the energy absorbed to failure, 12.8 ± 2.2 N-m.

The classic history of an ACLinjury begins with a noncontact deceleration, jumping, or cutting action.

Obviously, other mechanisms of injury include

external forces applied to the knee.

The patient often describes the knee as having been hyperextended or popping out of joint and then reducing. A pop is frequently heard or felt.

Resumption of activity usually is not possible, and walking is often difficult. Within a few hours, the knee swells, and aspiration of the joint reveals hemarthrosis 70% .

The Lachman test is the most sensitive test for anterior tibial displacement (95% sensitivity

The pivot shift test requires a relaxed patient

Knee ligament arthrometers such as the KT-1000/2000 can assist in the diagnosis but are more effective in evaluating patients with chronic ACL disruption when pain and associated muscle guarding are absent.

These devices also are useful for documentation of surgical results both intraoperatively and postoperatively.

With a manual maximal anterior displacement, the right-left difference is less than 3 mm in 95% of normal knees. The right-left difference is 3 mm or more in 90% of knees with an ACL ligament injury.

Plain radiographs often are normal; however, a tibial eminence fracture indicates

an avulsion of the tibial attachment of theACL.

The Segond fracture, or avulsion fracture of

the lateral capsule, is pathognomonic of an anterior cruciate ligament tear 70-100%.

Avulsion fracture of the tibia (Segond fracture) with anterior cruciate ligament tear.

AP STANDINGLATMERCHANT VIEWFULL LENGTH STANDING AP

MRI is the most helpful diagnostic radiographic technique.

The reported accuracy for detecting tears of the anterior cruciate ligament has ranged from 70% to 100%.

More recent investigators reported that the

accuracy for MRI in evaluating injuries to the anterior cruciate ligament approaches 95% to 100%.

The method chosen for treating an ACLtear is influenced by

the natural history of the injury, patients' ages and activity levels, extent of injury, resultant instability,follow-up duration and evaluation.

It has been well documented that an individual with an ACL–deficient knee who resumes athletic activities and has repeated episodes of instability will sustain meniscal tears and osteochondral injuries that eventually lead to arthrosis.,

Several investigators reported the incidence of meniscal tears with acute ACL injuries to range from 50% to 70%.

The lateral meniscus is more commonly injured with the initial incident

Most late meniscal tears occur in the medial meniscus because of its firm attachment to the capsule

Osteochondral damage also influences prognosis.

The reported incidence ranges from 21% to 31% in patients examined after the initial injury.

most resolve between 6 and 12 months.

Osteochondral abnormalities identified on MRI may be precursors of osteoarthritis.

 Magnetic resonance image shows bone bruise after ACL tear

Much current research is focused on the biochemical environment of the knee after ACL injury.

Cameron et al. found that in chronic ACL–deficient knees, the levels of proinflammatory cytokines such as interleukin-1 and tumor necrosis factor-a are markedly elevated,

whereas protective, antiinflammatory proteins such as interleukin receptor antagonist protein are significantly decreased.

They speculated that the increased release may be associated with the frequent development of posttraumatic osteoarthritis.

the surgeon must determine which therapy is most appropriate for a specific patient.

The treatment options include nonoperative

management, repair of the anterior cruciate ligament (either isolated or with augmentation), and reconstruction with either autograft or allograft tissues or synthetics.

Nonoperative treatment is a viable option for a patient who is willing to make lifestyle changes and avoid the activities that cause recurrent instability

Acute repair is appropriate when a bony avulsion occurs with the ACL attached.

The avulsed bone fragment often can be replaced and fixed with sutures or passed through transosseous drill holes or screws placed through the fragment into the bed.

ACL avulsions usually occur from the tibial insertion.

  Repair of avulsion of tibial attachment of anterior cruciate ligament with fragment of bone.

ExtraarticularIntraarticular

delay the reconstruction until after the patient has recovered from the initial injury .

Resolution of inflammation around the knee and return of full motion reduce the incidence of postoperative knee stiffness.

Intraarticular reconstruction of the ACL is a technique that attempts to reconstruct the anatomy as well as the function of the ligament.

Extraarticular reconstruction does not reconstruct the anatomy, but focuses on the two main aspects of ACL function: resisting anterior drawer, and internal rotation of the tibia.

Biomechanical studies have shown that extraarticular reconstruction alone leaves a significant deficit from the normal tibial rotation and anterior drawer.

Combined reconstruction of intraarticular

plus extraarticular has been shown to provide no additional stability over that achieved by intraarticular reconstruction alone with an isolated ACL rupture.

Extraarticular reconstruction can frequently cause over constraint of the joint, and increase lateral compartment contact pressures.

Most lateral extraarticular procedures use the iliotibial band.

The advances made in arthroscopy have led to the development of arthroscopic techniques for ACL reconstruction.

Simultaneously, our increased understanding of technical issues of graft selection, placement, tensioning, and fixation as well as of postoperative rehabilitation led to dramatically improved results compared with previous intraarticular reconstructions.

Graft Selection Graft Placement Graft Tension Graft Fixation

Autografts have the advantages of low risk of adverse inflammatory A, but initially a 50% loss of graft strength occurs after implantation.

Therefore, it is desirable to begin with a graft stronger than the tissue to be replaced

The most common current graft choices are bone–patellar tendon–bone graft and the quadrupled hamstring tendon graft.

The bone–patellar tendon–bone graft usually is an 8- to 11-mm-wide graft taken from the central third of the patellar tendon, with its adjacent patella and tibial bone blocks.

This graft's attractive features include its high ultimate tensile load (approximately 2300 N), its stiffness (approximately 620 N/mm), and the possibility for rigid fixation with its attached bony ends.

The use of the hamstring tendon graft has increased in recent years because of its relatively low donor site morbidity.

Use of a single strand of the semitendinosus or gracilis tendon is inadequate because the semitendinosus tendon has only 75% and the gracilis tendon only 49% the strength of the anterior cruciate ligament.

Now, surgeons are using either a triple- or quadruple-stranded semitendinosus graft or a quadruple-stranded semitendinosus-gracilis tendon graft with both ends folded in half and combined. This latter graft has an ultimate tensile load reported to be as high as 4108 N.

This quadruple-stranded graft also provides a multiple-bundle replacement graft that may better approximate the function of the two-bundle anterior cruciate ligament.

Disadvantages of this soft-tissue graft include the concern over tendon healing within the osseous tunnels and the lack of rigid bony fixation.

The quadriceps tendon graft also has attracted interest recently. It can be harvested with a portion of patellar bone or entirely as a soft-tissue graft.

Biomechanical studies have shown the ultimate tensile load of this graft to be as high as 2352 N.

This graft has become an alternative replacement graft, especially for revision ACL surgeries and for knees with multiple ligament injuries.

The next important decision is graft placement. Extensive research has been devoted to identification of the ideal position for graft placement to reproduce the anatomy and function of an intactACL.

errors in the femoral site are more critical because of the proximity to the center of axis of knee motion.

A femoral tunnel that is too anterior will result in lengthening of the intraarticular distance between tunnels with knee flexion.

The practical implications of this anterior location are “capturing” of the knee and loss of flexion or stretching.

Posterior placement of the femoral tunnel or placement of the graft over the top of the lateral femoral condyle produces a graft that is taut in extension but loosens with flexion.

This location produces an acceptable result, since the instability from an ACL deficiency occurs near terminal extension.

Currently, most surgeons advocate placement of the graft at the posterior portion of the ACL tibial insertion site near the posterolateral bundle position for best reproduction of the function of the intactACL.

This location also decreases graft impingement against the roof of the intercondylar notch with knee extension that can occur with anterior placement.

The posterior tibial location requires a minimal notchplasty, if at all, unless the ACL deficiency is chronic and the intercondylar notch has become stenotic with osteophytes.

A bony ridge (“resident's ridge”) anterior to the femoral attachment of the ACL should be removed, if present, since it impairs the proper identification of the femoral attachment site and also hinders the proper placement of the over-the-top guides used to drill the femoral tunnel.

A, Tibial drill guide for anterior cruciate ligament referencing off posterior cruciate ligament. B, Anterior cruciate ligament femoral guide.

A vertical tunnel position high in the intercondylar notch near the 12-o'clock position has been shown to provide stability in the anteroposterior plane but does not restore stability in the rotational direction. With this tunnel placement, the Lachman test result is normal but the pivot shift test result is positive.

Consequently, surgeons are beginning to place the femoral tunnel lower on the lateral wall toward the 10:30- or 1:30-o'clock position, which more accurately reproduces the femoral attachment site of the ACL and provides rotational stability.

Use of transtibial femoral guide systems tends to place the femoral tunnel in a more vertical position. With effort, the surgeon can get the guidewire to approximate the 10:30- or 1:30-o'clock position.

Alternatively, the femoral guide can be placed through a low medial portal hugging the patellar tendon to reach the lower spot on the lateral femoral condylar wall.

The single-bundle technique traditionally used recreates the anteromedial bundle and ignores the posterolateral bundle

The application of tension to the graft at the time of initial fixation can significantly alter joint kinematics and in situ forces in the graft during knee motion. Theoretically, the desired tension in the graft should be sufficient to obliterate the instability (Lachman test).

Too much tension may “capture” the joint, resulting in difficulty in regaining motion, or it may lead to articular degeneration from altered joint kinematics.

The force in the graft may decrease by as much as 30% after fixation of the graft unless the graft has been cyclically preconditioned.

To date, an optimal protocol for applying tension to a graft has not been defined, but overtensioning should be avoided.

In the early weeks after surgery, the weakest links in reconstruction are the fixation sites, not graft tissue itself.

Fixation of replacement grafts can be classified into direct and indirect methods.

Direct fixation devices include interference screws, staples, washers, and cross pins.

Indirect fixation devices include polyester tape–titanium button and suture-post.

Interference screw fixation is the most popular fixation method for bone–patellar tendon–bone grafts.

The screw must parallel the side of the bone

plug and the tunnel wall. This is ensured by the use of a cannulated screw system over a guidewire inserted down the tunnel over which the screw is inserted.

Screw divergence or lack of parallel placement of the screw to the bone plug can significantly affect the ultimate failure load.

screw divergence of more than 15 degrees lowered the ultimate tensile load up to 50%.

The arthroscopically aided approach has the advantages of:

smaller skin and capsular incisions, less extensor mechanism trauma, improved viewing of the intercondylar

notch for placement of the tunnel and attachment sites,

less postoperative pain, fewer adhesions, earlier motion, and easier rehabilitation

the use of hamstring tendon grafts for ACL reconstructions has increased in popularity.

Initially, the semitendinosus tendon and gracilis tendon were used together as two single strands.

Surgeons more recently have chosen to fold the semitendinosus and gracilis tendons on themselves, creating four strands and theoretically doubling the strength of the graft construct.

The goal of rehabilitation after anterior cruciate ligament surgery is to restore normal joint motion and strength while protecting the ligament graft.

Current evidence indicates that intensive rehabilitation can help prevent early arthrofibrosis and restore strength and function earlier.

Perhaps the most important step is the early restoration of full extension.

Knee immobilization in a fully extended brace is started immediately after surgery to prevent development of a flexion contracture

THEN aggressive full range of knee flexion, actively and passively.

After surgery, the thigh muscles atrophy quickly. Studies revealed that maximal thigh atrophy was recorded 6 weeks after surgery.

A tourniquet applied intraoperatively for ACL reconstructions with autogenous bone–patellar tendon–bone grafts decreased the quadriceps strength recovery at 12 weeks after surgery.

However, at 52 weeks, there was no significant difference in thigh girth and quadriceps strength recovery compared with a control group done without a tourniquet.

The early emphasis of strengthening is on the hamstrings, which function in concert with the anterior cruciate ligament to prevent anterior translation of the tibia. Also, their strengthening does not stress the graft.

Early quadriceps strengthening concentrates on quadriceps sets and straight leg raises.

Certain resisted quadriceps exercises are worrisome because they put some strain on the anterior cruciate ligament, especially in the last few degrees of extension of the knee if the limb is not bearing weight, so-called open chain exercises.

In an effort to protect the ACL graft during quadriceps exercises, it has been suggested that the patient stand instead.

The knee joint is thus loaded axially during motion, and perhaps the contours of the joint help stabilize the knee and protect the graft, so-called closed chain exercises.

After isolated ACLreconstruction, partial weight bearing with crutches is allowed immediately.

A straight-leg brace is worn to support the weakened quadriceps.

Certain types of concurrent meniscal repairs or articular cartilage procedures may dictate a different weight bearing status. Crutches usually are discontinued by 3 to 4 weeks postoperatively.

Proprioceptive training also is instituted in the first 2 weeks. Return to full activity requires 80% return of thigh strength and the ability to perform sport-specific agility duties.

usually delay return to sports for at least 6 months after surgery to allow maturation of the graft.

0-2 weeks

1. partial weight bearing 50-75%.2. full extension, active and

passive.3. quadriceps exercises

(isometric).4. straight leg raising (SLR).5. active flexion till 90°.

1. Full weight bearing.2. Full extension.3. SLR with low resistance.4. Active flexion till 120°.5. Active extension 90-60°.

2-4 weeks

1. Active full range of motion.2. Active extension 90-40° with

resistance.3. SLR with resistance.4. Double leg quarter squats.5. Double leg press (light weight

high repetition).

4-8 weeks

1. Progress the above exercises.

2. Active full extension (light weight high repetition).

3. Return to sport at 6 months or more.

8-10 weeks

Complications of anterior cruciate ligament surgery can be caused by :

1)preoperative2)intraoperative3)postoperative factors.

Preoperative factors include appropriate timing of surgery, adequate preoperative conditioning and strengthening, and graft and fixation choices.

Although each of these has been debated, current opinion generally holds that early reconstruction is preferable for early return to sporting activities, better clinical and laxity testing results, and decreased risk of late osteoarthritic changes.

Preoperative criteria for successful ACL reconstruction include minimal or no swelling, leg control, and full range of motion, including full hyperextension.

Intraoperative complications include patellar fracture, inadequate graft length, mismatch between the bone plug and tunnel sizes, graft fracture, suture laceration, violation of the posterior femoral cortex, and incorrect femoral or tibial tunnel placement

The most common postoperative complications are motion (primarily extension) deficits and persistent anterior knee pain.

Preoperative, effusion, limited range of motion, and concomitant knee ligament injuries

Intraoperative factors most often are incorrect tunnel position and inadequate notchplasty, which can result in overtightening or impingement of the graft, leading to loss of extension.

Postoperative factors prolonged immobilization and inadequate rehabilitation.

Anterior knee pain probably is the most common and most persistent complication after ACL reconstruction.

The exact cause has not been determined

In general, current postoperative protocols advocating limited or no immobilization and more aggressive rehabilitation have greatly decreased the frequency of both motion loss and anterior knee pain.

Causes of complications of anterior cruciate ligament reconstruction.