Ligament Injuries
The anterior cruciate ligament (ACL) is the most commonly injured ligament. Often more than one ligament is damaged as the result of a single injury.
Anterior Cruciate
Ligament
Anterior cruciate ligament (ACL) injuries occur from both contact
and noncontact mechanisms. The most common contact mechanism is a blow to the
lateral side of the knee resulting in a valgus force to the knee. This
mechanism can result in injury not only to the ACL but to the medial collateral
ligament (MCL) and the medial meniscus as well. This injury is termed the
“unholy triad” injury because of the frequency of these three structures being
injured from a common blow. The most common noncontact mechanism is a
rotational mechanism in which the tibia is externally rotated on the planted
foot. Literature supports that this mechanism can account for up to 78% of all
ACL injuries. The second most common noncontact mechanism is forceful
hyperextension of the knee. With prolonged ambulation on a knee that has a
deficient ACL, the secondary restraints (lateral collateral ligament and
posterolateral joint capsule) are stressed and become lax, and the individual
may develop a “quadriceps avoidance gait.”The quadriceps avoidance gait in ACL deficient
knees was originally documented and described by Berchuck and collegues as a reduction in the magnitude of the flexion
moment about the knee during the limb loading phase of gait due to the
patient’s effort to reduce contraction of the quadriceps.
Posterior Cruciate
Ligament
The posterior cruciate ligament (PCL) is most commonly injured
by a forceful blow to the anterior tibia while the knee is flexed, such as a
blow to the dashboard or falling onto a flexed knee.
Medial Collateral
Ligament
Isolated injuries to the medial collateral ligament (MCL) can
occur from valgus forces being placed across the medial joint line of the knee.
Whereas most injuries to the ACL and PCL are complete tears of the ligament,
injuries to the MCL can be partial or incomplete and are graded utilizing a I,
II, III grading classification of ligament injuries
Lateral Collateral
Ligament
Injuries to the lateral collateral ligament (LCL) are
infrequent and usually result from a traumatic varus force across the knee. It
is not uncommon that more than one ligament, joint capsule, and sometimes the
menisci are damaged as the result of a single injury.
Ligament Injuries in
the Female Athlete
With an increase in the number of female athletes since the passage
of Title IX in 1972, a concurrent increase in the number of injuries to female
athletes has been seen, most significantly an increase in the number of knee
injuries. What is interesting is that when injury to the ACL is sustained in a
noncontact manner, a woman is three times more likely to tear the ACL than a
man. With the increased number of noncontact ACL injuries in female athletes
being reported, the American Academy of Orthopaedic Surgeons published a
consensus paper examining the risk factors and prevention strategies of
noncontact ACL injuries. In addition,
results from a research retreat on “ACL Injuries—The Gender Bias” were
published in the Journal of Orthopaedic and Sports Physical Therapy.
Risk factors fall into four major categories:
environmental, anatomical, hormonal, and biomechanical.
Environmental factors center on the use of
prophylactic knee braces to prevent knee injuries and a shoe-tosurface interface
that may improve performance but may also increase the risk of injury.
Anatomical risk factors include femoral notch size,
ACL size, and lower extremity alignment. Insufficient data relating to each of
these factors have resulted in an incomplete understanding of the influence of
these factors at this time.
Hormonal differences between males and females have also
been postulated to be one possible factor related to the increased incidence of
female ACL injuries. In 1996, hormone receptor sites for estrogen and
progesterone were found in the ACL of humans. Since that time, research has
been conducted to study the effects of such hormones on the mechanical
properties of the ACL and other musculoskeletal tissues. To date, however,
results of multiple studies differ in their conclusions.
Biomechanical
risk factors summarized by
the consensus panel included the effect of the total chain (trunk, hip, knee,
and ankle) on ACL injuries, awkward or improper dynamic body movements,
deceleration and change of direction, and neuromuscular control of the joint.
Common Impairments
and Functional Limitations/Disabilities
• Following trauma,
the joint usually does not swell for several hours. If blood vessels are torn,
swelling
is usually
immediate.
• If tested when the
joint is not swollen, the patient feels pain when the injured ligament is
stressed.
• If there is a
complete tear, instability is detected when the torn ligament is tested.
• When swollen,
motion is restricted, the joint assumes a position of minimum stress (usually
flexed ), and inhibition (shut down) of the quadriceps muscle occurs.
• When acute, the
knee cannot bear weight, and the person cannot ambulate without an assistive
device.
•With a complete
tear, there is instability, and the knee may give way during weight bearing
Ligament Injuries: Nonoperative Management
Acute sprains and
partial ligament tears of the knee can be treated conservatively with rest,
joint protection, and exercise. After the acute stage of healing, exercises
should be geared toward regaining normal ROM, balance control, normalization of
gait, and strengthening of muscles that support and stabilize the joint during
functional activities. The degree of instability with ligament tears affects
the demands the patient can place on the knee when returning to full activity
Nonoperative
Management:
Maximum Protection
Phase
Follow the
principles described for an acute joint lesion If possible, examine before
effusion sets in. Utilize cold and compression with rest and elevation. Protect
the joint during ambulation with use of crutches; partial weight bearing as
tolerated. Teach safe transfer activities to avoid pivoting on the involved
extremity. Initiate quadriceps-setting exercises. The knee may not fully extend
for end-range muscle-setting exercises, so begin the exercises in the range
most comfortable for the patient. As the swelling decreases, initiate ROM
within tolerance and the swelling decreases, examine the patient for
impairments and functional losses. Initiate joint movement and exercises to
improve muscle performance, functional status, and cardiopulmonary conditioning.
Improve Joint
Mobility and Protection
Joint mobility. Use supine wall slides patellar mobilizations, and stationary
cycling; encourage as much movement as possible. Unless there has been an extended
period of immobilization, there should be minimal need to stretch contractures.
Protective
bracing
Bracing may be necessary for weightbearing activities to decrease stress
to the healing ligament or to provide stability where ligament integrity has
been compromised. Bracing can be one of two types: rangelimiting postoperative
type braces that are used to protect healing
tissues and discarded during later phases of rehabilitation or functional
braces that are used during rehabilitation and also when returning to
functional activities. The patient must be advised to modify activities until
appropriate stability is obtained.
Improve Muscle
Performance and Function Strength and endurance
Initiate isometric quadriceps and hamstring exercises and progress to
dynamic strength and muscular endurance training. Neuromuscular control is compromised
when stabilizing muscles fatigue. Utilize both open-chain and closed-chain
resistance. Reinforce quadriceps contractions with high-intensity electrical
stimulation if there is an extensor. Progress muscular endurance and
strengthening exercises using partial squats, step-ups, leg press, and heel-raises
Emphasize neuromuscular control with stabilization and perturbation training in
weight-bearing positions.
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