Background
Rehabilitation after anterior cruciate ligament reconstruction has changed drastically within the last 10-15 years and still varies widely. Protocols have shifted from from longer, time-based progressions to accelerated programs with emphasis meeting criteria for progression. ACL Reconstruction has been shown to be effective at restoring functional stability to the knee. It also has good long-term outcomes, allows return to pre-injury or near pre-injury level of sports participation, and sequels degenerative changes that would normally occur in a ligament deficient knee. Protocols vary by physician philosophy, type of graph, patient variables (i.e. age), and equipment available.
Graft Healing
Early on in rehabilitation, the fixation site is more vulnerable to failure regardless of graft material used. Later, after the the fixation site has healed, the graft becomes the weak link. The graft undergoes the process of ligamentization, where it undergoes stages on it's way to becoming the new ligament. The graft is weakest at post-operative week 12, and thereby crucial the knee has sufficient strength and neuromuscular stability to provide protection of the graft.
Weight Bearing Status
Weigth bearing stats varied between protocols, surgeons, concomittant procedures, and patient variables. Most protocols permit immediate partial or full-weight bearing after surgery.
Exercise and its affects on the graft
Passive Range of Motion: No strain occurs in the ACL during passive range of motion from 0 degrees to 120 degrees of knee flexion (Manal et al Current Concepts of Orthopaedic Phys Ther 2006).
Henning et al (AJSM 13:22 1985) reported on strain on the ACL after sprain during various activities relative to strain of 80-lb Lachman test (Activity: Strain listed below)
- Running Downhill at 5 MPH: 125%
- Isometric quad contraction at 22 degrees flexion against 20 lb weight: 62-121%
- Isometric quad contraction at 0 deg flexion against 20 lb weight: 87-107%
- Jog on floor: 89%
- Leg lift with 22 deg of knee flexion: 12-79%
- Jog 5 mph treadmill: 62-64%
- Isometric quad contraction at 45 deg flexion against 20 lb weight 50%
- Walk without assistive device: 36%
- Half-squat one leg: 21%
- Quad set 18%
- Walk with crutches, WB at 50 lbs: 7%
- Stationary cycle: 7%
- Isometric hamstring contraction: -7%
Beynnon et al (AMSM 23:24 1995): Measured ACL strain on normal ligaments and concluded that:
- Open chain exercises that produced low or no strain on the ACL: isometric contraction of hamstrings at 15, 30, 60, and 90 degrees; isometric contraction of quadriceps at 60 and 90 degrees; Co-contraction of quad and hams at 30, 60 and 90 degrees; Active knee flexion and extension between 35-90 deg flexion; knee flexion and extension with 10-lb weight between 45-90 degrees.
- Open chain exercises that produced significant strain on the ACL: knee extension with 10-lb weight (particularly at 10 and 20 deg of knee flexion); isometric quadriceps contractions (at 15 at 30 degrees); isometric co-contraction of the quad and hams a 15 degrees.
Beynnon et al (AJSM 25:823 1997) compared closed chain to open chain exercises for peak ACL strain. Peak ACL strain for 150-N Lachman test was 3.7% and 1.7% for stationary bicycling
Open-chain active knee flexion-extension with no load: 2.8%
Squatting: 3.6 %
- Open-chain knee flexion-extension with 10 lbs weight: 3.8%
- Squatting with Sport cord: 4.0%
- 30 Nm isometric quadriceps contractions at 15 degrees: 4.4%
Kvist and Gillquist (AJSM 29:72 2001 )measured anterior tibial translation during knee extension exercises and several types of squats.
- Active knee extension: as load increased, so did translation. Eccentric phased produced more translation than concentric phase. Greatest anterior translation occurred between 15 and 20 degreees knee flexion.
- Squat conditions produced less translation than all loaded active extension exercise for knees with deficient ACL's
- Similar results have been reported elsewhere (Yack HJ et al AJSM 21:49 1993; Yack et al JOSPT 20:247 1994)
Complications
Decreased post-operative function is significantly correlated with long-standing quadriceps weakness and loss of knee extension range of motion (Graf Orthopedics 17:909 1994). Early focus should be on quadriceps strengthening as hamstring strength appears to recover without focused intervention regardless of graft material (Manal et al Current Concepts of Orthopaedic Phys Ther 2006; Snyder-Mackler L et al JBJS Am 73:1025 1991; Vegso JJ et al Med Sci Sports Exerc 17:376 1985). Lack of passive and active extension will manifest during gait, as the most common gait deviation is ambulation with the knee in flexion and never reaching terminal extension (Snyder-Mackler L et al JBJS Am 77:1166 1995).
Post-operative Bracing
- Long-leg brace: The patient may present with a long-leg brace locked at 0 degrees to maintain extension and bilateral axillary crutches. Most surgeons permit opening the brace within the patient's available range of motion in one or two weeks once the patient has good knee stability in stance phase of gait. The patient is weaned off the crutches as he or she is able to ambulate with a normal gait pattern.
- Functional Bracing: The use and timing of functional bracing is at the discretion of the surgeon. These can be custom of off the shelf. Research has shown that the braces do NOT control shearing forces at the joint under physiologic loads (Beynnon BD et al JBJS Am 74:1298 1992; Vaitlas JC et al Sports Med 15:210 1993). The functional braces have been proposed to provide a proprioceptive role and some athletes have subjectively reported feeling more stable while wearing them (Weber et al Knee Rehabilitation. In Physical Rehabilitation of the Injured Athlete, 2004). It has been reported though that patients ambulated with a more erect gait pattern including greater knee extension when wearing a brace (DeVita et al AJSM 26:778 1998). Risberg et al reported improved functional outcomes at 3 months post-op in those wearing a functional brace, but no difference at the 1 and 2 year follow ups (Risberg et al AJSM 27:76 1999).
Electrical Stimulation
Much work has been performed on post-operative neuromuscular stimulation of the quadriceps after as part of rehabilitation after ACL reconstructive surgery. Snyder-Mackler et al (JBJS Am 77:1166 1995) regained quadriceps strength at a faster rate when applying electric stimulation at 65 degrees of knee flexion in a closed-chain position compared those who just performed closed-chain exercises alone. The electrical stimulation group acheived 70% recovery of the quadiceps strength by 6 weeks post-op compared to only 57% in the closed-chain only group.
Protocols (Add yours here)
