Traditional methods of management after ACL reconstruction included a lengthy period of non-weight-bearing and knee immobilization. Early muscle activity around the knee joint was discouraged due to concerns regarding the integrity of the graft and its fixation. This program led to weakness and stiffness around the knee joint with impaired proprioception and poor function. A fixed flexion deformity was common due to the prolonged extension block, while there was usually prolonged loss of full flexion. Patellofemoral joint problems were also common during the rehabilitation process.
Management principles have changed dramatically in recent years, resulting in greatly accelerated rehabilitation after ACL reconstruction. These management principles have changed as surgical techniques have changed. There is now a better understanding of the strengths of grafts and the strength of fixation techniques. There is no difference in joint laxity or clinical outcome between those who underwent accelerated rehabilitation compared to those with a non-accelerated program at two years’ post surgery.
Rehabilitation must commence from the time of injury, not from the time of surgery, which may be days, weeks or months later. Pre-operative management aims to reduce pain, swelling and inflammation, thus reducing the amount of intra-articular fibrosis and resultant loss of range of motion, strength and function. Immediately after injury, treatment should commence, including interferential stimulation, ultrasound and TENS, as well as strengthening exercises for the quadriceps, hamstring, hip extensor, hip abductor and calf muscles. Pain-free range of motion exercises should also be performed.
Rehabilitation techniques after anterior cruciate ligament reconstruction with evidence of effectiveness:
- Immediate weight-bearing.
- Closed kinetic chain exercises selecting knee joint motions of less than 60 degree
- Open kinetic chain exercises with knee angles greater than 40 degree of flexion
- High-intensity neuromuscular electrical stimulation (MMES) in addition to voluntary exercises for improving isometric quadriceps muscle strength.
Problems Encountered During ACL Rehabilitation
Apart from surgical complications (e.g. infection, deep venous thrombosis), a number of secondary problems may occur during the rehabilitation process.
Patella Problems
Patellofemoral pain may occur on the injured or the uninjured side. Patients may present with typical symptoms of patellofemoral pain but often will not comment on the presence of anterior knee pain as they assume that it is part of the normal process following surgery. The patient should always be asked about symptoms at the front of the knee and the patellofemoral joint should be examined at each visit.
Low Back Pain
Low back pain is not uncommon in the early stages of the rehabilitation program when it may be due to the use of crutches and to altered gait patterns. It usually occurs in patients who have a prior history of low back pain.
Lower Limb Stiffness
Stiffness in the foot and ankle commonly occurs as a result of a period of non-weight-bearing and the wearing of a brace. Tightness of the Achilles tendon is common. These problems typically present on return to running. Fun range of motion of these joints should be maintained early in the rehabilitation program with mobilization and stretching in addition to active plantar flexion/dorsiflexion exercises.
Soft Tissue Stiffness (Arthrofibrosis)
The rehabilitation program and its rate of progression will be influenced by the intrinsic tissue stiffness or laxity of the patient.. Patients with stiff soft tissues may develop a large bulky scar with adhesions after ACL reconstruction. These patients are usually slow to regain full flexion and extension, and the knee may require passive mobilization by the therapist. Patients tend to have tight lateral structures around a stiff patellofemoral joint. This is known as arthrofibrosis.
Treatment Involves:
- Encouraging active movement.
- Early passive mobilization.
- Massage and encouraging early activity.
- Efforts to control swelling are critical.
- It may be helpful to remove the brace earlier than usual in these patients.
- Severe cases may require arthroscopic scar resection as well as a vigorous rehabilitation program..
Outcomes after ACL Treatment
While the general consensus among the surgical and sporting communities is that those sustaining an ACL injury make a full recovery after ACL reconstructive surgery, research findings suggest that is not always the case. Three main outcome measures are used to determine the success or otherwise of ACL treatment:
- Return to sport
- Re-injury rate
- Prevalence of osteoarthritis.
Return to Sport
The majority of those who have an ACL reconstruction have good to excellent knee function and most (65-88%) are able to return to sport within the first year. Thus, surgery is effective in allowing injured athletes to resume their sports career.
Although the initial return to sport rate is high, previously injured athletes retire at a higher rate than athletes without previous ACL injury. The reason for this may be that many of the athletes who return to sport experience significant knee problems such as instability, reduced range of motion and/or pain.
Re-injury Rate
The incidence of graft failure is generally of the order of 3-6% in most studies. There is some evidence from a meta-analysis that the failure rate may be lower in patellar tendon autografts, although another systematic review falled to show a difference. There also appears to be an increased risk of rupturing the contralateral ACL in patients who have already had an ACL injury. There may also be an increased risk of other knee injuries (e.g. meniscal, articular cartilage injury) after ACL injury, particularly in those managed non-operatively. Re-injury appears to be most likely in the first 12 months after surgery.
Osteoarthritis
ACL rupture is associated with a significant risk of development of osteoarthritis (OA); it may be that the initial injury itself may influence the development of OA irrespective of what treatment is used or how the knee is loaded during subsequent years. Whereas previously it was thought that an isolated ACL injury was quite common, we now know that bone bruising (as seen on MRI) occurs in more than 80% of cases of ACL tears. Bone bruising is highly associated with articular cartilage damage. Meniscal injury is found in 75% of cases of ACL tears and this also predisposes to the development of OA.
We and others propose that athletes who have undergone an ACL reconstruction should receive advice about the likelihood of developing OA, and the possibility that returning to active sports participation will accelerate its development. Many professional and dedicated athletes may decide to continue their sport in spite of that advice, but it is the duty of health professionals to enable them to make an informed decision.
Prevention of ACL injury
As 60-80% of ACL injuries occur in non-contact situations, it seems likely that the appropriate prevention efforts are warranted in ball sports two common mechanisms cause ACL tears:
- A cutting maneuver
- One leg landing.
Cutting or sidestep maneuvers are associated with dramatic increases in the varus-valgus and internal rotation moments. The ACL is placed at greater risk with both varus and internal rotation moments. The typical ACL injury occurs with the knee externally rotated and in 10-30 degree of flexion when the knee is placed in a valgus position as the athlete takes off from the planted foot and internally rotates with the aim of suddenly changing direction.
High-speed activities such as cutting or landing maneuvers require eccentric muscle action of the quadriceps to resist further flexion. It may be hypothesized that vigorous eccentric quadriceps muscle action may play a role in disruption of the ACL. Although this normally may be insufficient to tear the ACL, it may be that the addition of a valgus knee position and/or rotation could trigger an ACLrupture.
Mechanisms of ACL Injury
The mechanisms of ACL injury in skiing are different from that in jumping, running and cutting sports such as football and basketball. In skiing ,most ACL injuries result from internal rotation of the tibia with the knee flexed greater than 90 degree, a position that occurs when a skier who is falling backwards catches the inside edge of the tail of the ski. Intervention programs in skiing are aimed at increasing the skier’s awareness of patterns that are injurious to the knee, and giving alternative strategies in the hope of avoiding these patterns altogether.
