1. Early ACL rehabilitation programs should focus on closed kinetic chain exercises to initiate muscle activation and range of motion recovery. 2. As strength returns, programs should incorporate proprioception and landing mechanics training to reduce reinjury risk when returning to sport. 3. Most successful programs are comprehensive, last 9-12 months, and progress from basic strength and range of motion exercises to sport-specific training.

1. 1
ASCA LEVEL 2 MAJOR PROJECT- CURRENT REHABILITATION
PRACTICES FOLLOWING ANTERIOR CRUCIATE LIGAMENT
RECONSTRUCTION - A LITERATURE REVIEW
By Bennett D Tucker AES, AEP, ESSAM
72 Langdale Drive Croydon Hills Vic 3136
Ph: 0419 159 903
Email: bennett_tucker@hotmail.com

2. 2
BLUF
Anterior cruciate ligament tears require carefully considered and appropriate exercise
programs including closed kinetic chain strength exercises as well as proprioception and
landing mechanics retraining in order to be successful in returning the athlete back to sport.
ABSTRACTAND KEYWORDS
After back complaints, knee injuries are the most frequent problems of the musculoskeletal
system reported in primary care. In the United States, more than 200, 000 ACL injuries occur
each year and approximately 65% of these injuries are treated with reconstructive surgery.
There is a high degree of muscle atrophy and weakness in the operated leg (e.g. the
quadriceps and hamstring muscle groups) as well as abnormal movement patterns and
below normal knee function The purpose of this study was to investigate the current
practices used in the rehabilitation of athletes who have undergone ACL reconstruction, in
order to establish the most appropriate method for success in return to sport.
A search of the relevant journal databases, as well as google scholar, was made of relevant
literature relating to strength training and proprioception after ACL reconstruction and
rehabilitation. Early on in the rehabilitation process, an effective ACL rehabilitation program
should include closed chain exercises to initiate muscle activation and range of motion.
Further closed chain exercises that allow the body to regain functional strength should be
undertaken to restore the limb as close to pre-injury strength as possible. Once the athlete
is pain-free and has appropriate strength levels, proprioception and landing/jumping
training/re-training activities should be included to reduce the risk of further ACL tears.

3. 3
Keywords: Rehabilitation, ACL, knee, reconstruction, strength, athlete
INTRODUCTION
After back complaints, knee injuries are the most frequent problems of the musculoskeletal
system reported in primary care [1,2]. Within these knee injuries, anterior cruciate ligament
(ACL) injuries are common, with a reported incidence of 30 cases per 100,000 [3]. In the
United States, more than 200, 000 ACL injuries occur each year and approximately 65% of
these injuries are treated with reconstructive surgery [4]. Female subjects have roughly 3
times greater incidence of ACL tears in soccer and basketball compared to males, with a
year-round ACL tear rate of approximately 5% [1]. Most ACL ruptures occur during sports
activities in the age group of 15-to-25-year old athletes [5]. Analysis of injury descriptions
for ACL injuries indicated that 58% involved a non-contact mechanism of injury. This data
showcases the high level of short-term disability associated with knee ligament injuries,
especially ACL injuries that require surgery [2].
Because the ACL is a primary stabiliser of the knee, a rupture can lead to functional
instability (i.e., giving-way episodes) [3, 5] and proprioception impairment [6]. Conservative
or surgical treatment of this instability is generally suggested for regaining the pre-injury
level of function [5]. Two-thirds of primarily conservative treated patients opt for an ACL
reconstruction after rehabilitation, with the younger and more active athletes generally
choosing earlier surgical reconstruction [5]. Arthroscopically assisted ACL reconstruction
using a hamstring or patella tendon to replace the old ACL is the standard surgical

4. 4
treatment, particularly for those who are unable to perform jumping and cutting
manoeuvres in sports due to knee instability [3].
There is a high degree of muscle atrophy and weakness in the operated leg (e.g. the
quadriceps and hamstring muscle groups) [7], as well as abnormal movement patterns and
below normal knee function [8, 9] following ACL reconstruction [3]. Currently, success after
ACL reconstruction is measured using return-to-sport rates, but second ACL injuries are not
only common, but devastating, and have worse outcomes than primary ACL reconstruction
[8]. Successful outcomes have been consistently achieved with the rehabilitation principles
of early weight bearing, a combination of weight-bearing and non–weight-bearing exercise
focused on quadriceps and lower limb strength, and meeting specific objective
requirements for return to activity [4]. There is a general consensus for the effectiveness of
a postoperative ACL reconstruction rehabilitation program, however, there is little
consensus regarding the optimal components of such a program with one study stating that
injury-reduction programs were effective for soccer but not basketball [4].
The purpose of this study was to investigate the current practices used in the rehabilitation
of athletes who have undergone ACL reconstruction, in order to establish the most
appropriate method for success in return to sport.
METHODS
A search of the PUBMED/MEDLINE, CINAHL, SportDiscus, Rehabilitation and Sports Medicine
Source and Rehabilitation Reference Center databases, as well as google scholar, was made
of relevant literature relating to strength training and proprioception after ACL
reconstruction and rehabilitation. The database search was based on relevant medical

5. 5
subject headings terms strength/resistance/weight training, anterior cruciate ligament
reconstruction/rehabilitation and proprioception. The literature was reviewed and only
articles from the last 15 years were used as this reflects current day practices. A total of 26
papers were located using these parameters.
DISCUSSION
Rehabilitation exercises following ACL reconstruction are receiving attention from many
experts in sports medicine. Current programs emphasise full passive knee extension,
immediate weight bearing as tolerated, and functional exercises [10]. Traditional
rehabilitation exercise methods restrict the range of motion, do not apply weight bearing at
the beginning and are composed of only low-intensity exercises [4, 6]. However, accelerated
rehabilitation programs are composed of immediate and active rehabilitation exercises after
surgery, and have been reported to enable a return to sport activities in approximately six
months after the ACL reconstruction [10, 11]. There is varying literature in the design of
rehabilitation programs, with some studies showing that rehabilitation following ACL
reconstruction is commonly divided into 4 phases [5, 7]. Phase 1 (1-week post-surgery),
Phase 2 (week 2- 9), Phase 3 (Week 9-16), Phase 4 (16-22) [5]. While other researchers
suggest 3 stages, stage 1 (3-7 days), stage 2 (2-3 weeks), stage 3 (4-12 weeks) [11]. This is
due to the conjecture between accelerated programs and more traditional, longer
rehabilitation programs. The best form of treatment has been studied and surgical
operations have been designed to provide stability of the joint in all directions [12].
Accelerated Programs vs Traditional Programs

6. 6
The speed with which an individual returns to their pre-injury level of sport and activity is
mostly dependent on the type of rehabilitation protocol they receive [3, 5]. Considering the
large differences in clinical and outpatient protocols, there is no clear consensus regarding
the content of such a rehabilitation program [5]. Conservative approaches of six-week cast
immobilisation, followed by knee extensor resistive exercises, and a slow return to activity
have been superseded by more aggressive programs which emphasise earlier strength and
range of motion (ROM) retraining and time to return to activity [3].
Traditional rehabilitation exercise methods restrict the range of motion, do not allow weight
bearing at the beginning and are composed of only low-intensity exercises [4, 10]. As such,
9–12 months of rehabilitation is required before returning to sport activities [11]. While
accelerated rehabilitation, composed of immediate and active rehabilitation exercises after
surgery have long been suggested as optimal and reported as safe following ACL
reconstruction [9]. Using accelerated methods, some athletes have reportedly been able to
return to sport activities in approximately 6 months after ACL reconstruction programs [11].
Some authors suggest the traditional programs focus too much on the low-intensity and
general exercises, and suggest that this intensity is too low to increase muscle strength to
pre-injury/ satisfactory levels [6, 10].
A paper by Zhu et al investigated the above theory by using 45 untrained subjects (25 male,
20 female) who were randomly divided into three groups. Each group had a different
rehabilitation procedure; an accelerated program, an aggressive program and a program
built by the facility [13]. During the accelerated program, the athletes lay in bed for 4 weeks
while a brace was fixed. During this time, knee flexion ranged from 0-60°, up to 90° after 8
weeks. Closed chain exercises (such as half crouch and leg pressing) began 8 weeks after the

7. 7
surgery while open chain exercises began 12 weeks after surgery. They began running and
swimming practices half a year after the surgery [13]. The aggressive program consisted of
walking with the support of brace 2 weeks post-surgery, which was removed after 8 weeks.
Closed chain training began 2 weeks after surgery, open chain training began 4 weeks after
surgery, and running and swimming began 8 weeks after surgery. Sports activities became
normal 3 months after the surgery. Finally, during the clinic designed program, closed chain
practice began 4 weeks after surgery with open chain practice began 8 weeks after surgery
with increased flexibility practice. Sports activities became normal 6 months after the
surgery [13]. The results show that early (especially in 2 weeks after the surgery) recovery is
advantageous in preventing muscle atrophy, and that there was a significant difference
(p<0.05) in thigh diameter in favour of the traditional program. In regards to bone health
flowing surgery, the authors found that the extent of damage for the aggressive recovery
group is larger, which means that an aggressive approach may not necessarily be better.
Thus, a more moderate and longer procedure might be most appropriate [13].
One study, using 5 male and 5 female subjects, all of whom had the same surgeon,
considered that 12-week duration rehabilitation exercises are incapable of improving knee
joint extension muscle functions in females, but are capable of partially recovering extensor
muscle functions in males [11]. This is further examined by Silva et al, who, using an ACL
group (6 males and 1 female with a history of ACL injury) vs a control group ( 7 males 2
females) found that there was a significant difference (p<0.05) between the groups for leg
extensor muscle strength as well as finding that the function of this muscle, in terms of
muscle sense, was still inhibited in the injured leg, following an accelerated program [6]. The
authors suggest that this predisposes the athlete to re-injury and therefore, a longer

8. 8
program, at least 6 months+, should be utilised [6]. For full recovery of knee joint muscle
functions after surgery, rehabilitation exercises of 9-12 months are necessary [11].
Strength Training
Strength training has become an integral part of most post-operative ACL rehabilitation
programs with early initiation of muscle training such as isometrics/setting exercises being
crucial to prevent muscle atrophy [14].
In the literature, studies on strength training during rehabilitation following ACL
reconstruction are scarce, with studies that have attempted to compare the effect of
different strength training regimes (e.g. by comparing training intensity, volume or
frequency) somewhat lacking [7].
Although many studies have been published concerning strength training after ACL
reconstruction [3, 6, 14-16], few of these studies provided the specific details of the
strength training (e.g. training frequency, intensity, volume, progression and the duration of
the training period) and the training protocols [7].
The specific role strength training plays and the amount of resistance that is possible to use
at a particular phase without athlete’s suffering injury or other setbacks during the course of
the rehabilitation program, is not clear. It could, however, be argued that strength training
using heavy resistance (80 % of 1 repetition maximum [1 RM]) that optimises maximal
strength increases and leg muscle mass improvement is not possible until at least 5 or 6
months post-operatively, or, during the late phases of the rehabilitation [7].
Open Kinetic Chain vs Closed Kinetic Chain

9. 9
Open kinetic chain (OKC) exercises refer to any exercise where the distal segment of the leg
is fixed, such as the leg extension machine [17]. Closed kinetic chain exercises (CKC), refer to
exercises where the distal segment of the leg is fixed to the floor, such a squat [17]. Closed
kinetic chain exercises have been favoured over open kinematic chain exercise after ACL
reconstruction, due to the co-contraction of quadriceps and hamstrings seen during such
exercises [14]. This co-contraction has been found to produce a protective effect which
further helps minimize the strain on the ACL [14]. Although CKC exercises are favoured, it
should be noted that that walking, running, stair climbing and jumping all involve
combinations of OKC and CKC components [14] so OKC exercises should not be forgotten.
During the initial stages of the rehabilitation process (weeks 4-6), OKC exercises must not be
introduced as the fixation of the graft is not stable and, therefore, dynamic extension should
be avoided [14]. There have been numerous studies that have investigated the use of OKC
vs CKC in short-term rehabilitation [3, 17-19]. Four Randomized Controlled Trails (RCT’s)
comparing OKC exercises versus CKC exercises found no significant difference between
groups for knee laxity, pain and function in the short term (6-14 weeks) [16-19].
Proprioception
Proprioception is defined as the culmination of all neural inputs originating from joints,
tendons, muscles and associated deep tissue proprioceptors [10]. More recently, the
definition of the proprioceptive system has been expanded to include the complex
interaction between the sensory pathways and motor pathways [12]. Altered
proprioception has been reported to reduce the effectiveness of the individual to protect
the knee and perhaps predispose the ACL to repetitive micro trauma and ultimately failure

10. 10
[10]. Injury to the ACL results in mechanical instability of knee with different athletes
showing different symptoms and instabilities post injury [12]. Proprioception may play a
significant role in this and needs to be enhanced [12]. The best way to enhance this is to
complete exercises that require higher brain centre control, such as those exercises that are
repetitive positioning activities which maximize sensory input to reinforce proper joint
stabilisation activity [14], such as jumping and landing exercises. Unconscious control is
developed by incorporating distraction techniques into the exercise protocol [14].
Balance exercises are aimed at improving proprioception and train the brain to recognise
the body’s segment position at every moment [12]. This can be done by giving the athlete
specific balance exercises early in rehabilitation and for a long period after ACL
reconstruction [12]. It is very important to realise that proprioception is closely correlated
with both the functional outcome and the athlete’s recovery satisfaction especially in sport
[12].
Neuromuscular training focusing on restoring limb symmetry and improving knee function
using sports-related movements may reduce aberrant movement patterns which are
predictive of second injury risk [8].
CONCLUSION AND PRACTICAL APPLICATIONS
This review shows that following an ACL reconstruction, it is important for the athlete to
regain lower limb strength, especially in the quadriceps. Most successful programs are those
that last for 12 months as this is the length of time needed to include all aspects of a
program. Early on in the rehabilitation process, an effective ACL rehabilitation program
should include closed chain exercises to initiate muscle activation and range of motion.

11. 11
Further closed chain exercises that allow the body to regain functional strength should be
undertaken to restore the limb as close to pre-injury strength as possible. Once the athlete
is pain-free and has appropriate strength levels, proprioception, and landing/jumping
training/re-training activities should be included to reduce the risk of further ACL tears.
Once able to run again, the athlete should be on an incremental running-based program to
ensure they are capable of returning back to the sport. Table 1 shows an example training
plan for ACL reconstruction rehabilitation over 9 -12 months. It is important that each
athlete be considered on an individual basis and should be developed in conjunction with
their surgeon. In the early stages it is important that the athlete manage their pain and not
do too much as this can have negative impact on progress.

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Table 1- Sample exercise program based on a typical ACL reconstruction.
Stage (weeks) Training Goal/s Exercises Intensity/ sets
/reps
0-4 weeks Facilitate Healing
Regain basic range
of motion (ROM)
Muscle re-
education
1. Non weight
bearing quad
and hamstring
setting
(promote
extension)
2. Glute Setting
3. Knee flexion
to promote
movement
1 x 10
1 x 10
1 x 10
6-8 weeks
8-10 weeks
10-12 weeks
Restore full pain
free ROM
Improve
strength/endurance
Step ups/downs
SB supported
wall sits (0-30°)
All of above
Calf raise
Leg press
Seated
Hamstring curls
(after 10 weeks)
½ squats
All of above
SB hamstring
curls
SL balance
Rebounder
jogging
3 x 10
3 x10
All 3 x 10
2x10
15 secs
30 secs
3 -4 months All of above
Lunges
Back squats
All 3 x 10 60%

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4-5 months
5-6 months
Improve strength
Improve
proprioception
Initiate power
activity
Clock lunges
SL balance
wobble board
Start running in
straight lines at
low speeds
Forward
Jumping/landing
(2 legs)
Side to side
jumping/landing
(2 legs)
Glutes- hip
hitch/ lateral
band walks
Lateral bounds
Agility drills-
shuttles/around
cones ‘ s
curves’. Figure
8’s
Acceleration-
start stop drills
30secs
5 mins max
3 x 5
3 x 5
3 x 15
3 x 5
2 x 10
2 x 5
6- 8 months
8-9 months
Increase power
Sports specific
training
Return to drills
training
Maintain gym
program as
above,
Increased depth
in landing drills
Box jumps
SL jump/landing
Increase running
distance
Increase sport
specific running/
training
Non-contact
team drills
3 x 10 at 90%
2 x 5
3 x 5
2 x 10
10-15 mins
15-20 mins
1hr

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9 months +
Return to full
training/ game
If confident-
return to sport
Continue to
maintain
strength and
power
Proprioception
exercises

15. 15
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