Meniscal Anatomy/Biomechanics Print

Treatment: The treatment of ACL injuries should be tailored to the individual patient. Risk factors that may be used to determine treatment include age, activity level, willingness to modify activities, laxity of the joint, number of giving way episodes, and presence of associated ligament, articular cartilage, or meniscal injuries. Patients who participate in strenuous activities and have concomitant ligament or meniscal pathology are poor candidates for conservative treatment. Patients who have a greater degree to laxity or repeated episodes of giving way are also poor candidates for conservative treatment. The status of the menisci is a key determinent of long term function in the ACL deficit knee. Meniscectomy leads to decreased function with increased risk of degenerative changes. Because meniscal injury associated with ACL deficiency is in large part related to giving way episodes, treatment is directed toward eliminating functional instability.

Non Surgical Treatment

Initial nonsurgical treatment is directed at regaining range of motion, decreasing swelling, and maintaining strength. The use of functional knee braces is a part of conservative treatment for ACL insufficiency; approximately two thirds of patients feel more stable, but a substantial number of knees give way in the brace. Proprioception training using balance boards may be of benefit in a non surgical program.

Surgical Treatment

A myriad of surgical techniques for stabilizing the ACL deficient knee have been described and popularized. Extraarticular, intraarticular and combined intra and extraarticular techniques have been used. The results of ACL reconstruction have improved substantially since the 1980's. Current arthroscopic assisted techniques emphasize anatomic placement of high strength grafts using rigid fixation techniques.

The middle one third of the patellar tendon, (bone patellar tendon bone graft), is the gold standard to which other grafts are compared. A 10 mm. wide patellar tendon graft has initial strength of more than 150% of the normal ACL. Interference screw fixation is the most popular technique for fixation of bone patellar tendon bone grafting.

Three Slides in Avoiding Complications

Quadrupled hamstring tendon is another graft with wide popularity and an increasing body of literature supports its use. Doubled looped semitendinous and gracilis tendons have been reported to be one and a half to two times as strong as the ACL. A strong graft is important because the graft loses up to 50% of its strength 6 months after surgery. By one year the graft strength increases to approximately 80% of its original strength.

Allograft (donor) tendons are occasionally used to reconstruct the ACL. The major advantage of allografts is that there is no donor site morbidity. The major disadvantages are delayed healing of the graft, a slightly lower success rate, an immunogenic response, and a slight possibility of infectious disease transmission.

Post Operative Treatment

Delaying surgery until the patient regains full knee extension and flexion to 120 degrees and obtaining full extension with early ROM after surgery has reduced the incidence of stiffness after ACL reconstruction to less than 3%. Several studies have revealed no benefit from the use of continuous passive motion. Cryotherapy (cooling) devices reduce swelling and pain but they provide no long lasting effects.

Early rehabilitation programs should protect the graft from excessive strain. Partial weight bearing progressing to full weight bearing in two weeks is recommended. Fixation of the graft is the weak link for the first six weeks after surgery. Therefore, during initial rehabilitation, stress on the graft should not exceed fixation strength (approximately 450 to 600 newtons). Three months after surgery the graft is the weakest link. Closed kinetic chain exercises are beneficial because they decrease stress on the graft from joint compression and simultaneous hamstring contraction. A randomized, controlled study showed decreased laxity, decreased anterior knee pain, and more rapid return to function when closed kinetic chain exercises were used. Several studies have confirmed that early return to athletics (by six months) can occur with no increased risk of failure, if return is based on recovery of quadriceps muscle strength (>50% for jogging, >65% for sports specific agility training, >80% for full athletics). Functional braces may decrease the strain on the graft, but inhibit the protective effect of hamstring contracture.

Proprioceptive re-education and sports specific training are the final plan of rehabilitation.

© Allen F. Anderson, M.D. 2017