Chapter 10 Medial and Lateral Collateral Ligament Injuries
Introduction
Epidemiology: (San Diego Kaiser Knee Injury Clinic)
n = 500
Isolated MCL:
ACL-MCL:
Isolated LCL:
football
10%
9%
baseball
11%
2%
18%
basketball
4%
5%
soccer
7%
14%
6%
skiing
13%
19%
6%
other sports
9%
13%
12%
vehicle
10%
14%
6%
miscellaneous
36%
25%
53%
54% of isolated MCL injuries occurred in sports while only 41% of isolated LCL injuries were sports related
incidence of MCL 14x that of LCL
Pertinent anatomy & biomechanics
Static:
MCL ligament consists of the tibial collateral ligament & the mid one-third medial capsule (deep portion)
medial capsule is subdivided into a: thin anterior third, strong mid-third, and
moderately strong posterior third
mid-third medial capsule has menisco-femoral and menisco-tibial components
posteromedial capsule is also termed the posterior oblique ligament
tibial collateral ligament is primary restraint to valgus stress
mid-third medial capsule is the secondary restraint
ACL/PCL also provide some secondary stability
tibial and femoral insertions are quite different; the subperiosteal (indirect) insertion into the tibia is
made up of a superficial layer in which fibers of the MCL joint with the periosteum, and a deep layer with
fibers obliquely anchored into bone; the femoral insertion passes directly through zones of fibrocartilage,
mineralized fibrocartilage and bone
MCL taut at full extension, relaxes at 20-30 degrees, and begins to tighten between 60 and 70 degrees
lateral anatomy includes the: lateral collateral ligament, lateral capsule, popliteus tendon, biceps
femoris tendon, iliotibial tract; the thickened posterior third of the lateral capsule is called
the arcuate complex (because it forms an arc over the popliteus tendon)
LCL is primary restraint to varus stress
taut in extension, lax as it moves into flexion
the above-mentioned soft tissues are the secondary restraints; ACL/PCL provide some secondary stability,
although the PCL provides less restraint to varus stress than valgus stress
Dynamic:
pes anserine muscles
semimembranous
VMO
medial head of gastroc
popliteus
lateral head of gastroc
vastus lateralis
biceps femoris
Mechanism of injury
MCL: often a contact injury at the lateral or posterolateral knee imparting a valgus stress to the knee;
also injured in skiing or other sports where the foot is caught and the knee collapses medially over it
LCL: contact or noncontact hyperextension varus stress
Diagnosis
history, subjective exam
localized swelling and tenderness over ligament
± palpable defect
effusion/hemarthrosis indicates secondary injury
palpate along entire length
may be difficult to distinguish MMT/LMT if tenderness occurs at joint line
laxity at 30 degrees
laxity at 0 degrees indicates additional ACL/PCL tear
look for associated injury
Grading (McCue)
Grade I: microscopic tearing with no measurable loss of function; no laxity
Grade II: partial disruption or stretching of the ligament with some loss of function
(1/3 to 2/3 tear); 0-5 mm opening with good end point
Grade II+: 6-10 mm opening with soft end point
Grade III: 2/3 to complete tearing of the ligament with continuity with >10 mm opening
Grade III+: complete failure with loss of continuity
Treatment of MCL injuries
Surgical versus Non-surgical:
historically, all ligament injuries were treated with plaster casting
in 1939, Palmer published a paper advocating surgical treatment, and O'Donoahue popularized
this approach in a 1959 publication
Ellsasser reported excellent results with nonoperative
treatment of Grade II MCL and LCL injuries in professional FB injuries
in 1974 (JBJS); no braces or casts were used; however, he felt that
a well-muscled thigh was a prerequisite for the early mobilization
program, and those with poor strength should be casted for 3-4 weeks
(10/69 were LCL)
in 1978, Fetto treated MCL injuries with 4-6 weeks of casting
for Grade II injuries, and 6-10 weeks for Grade III injuries; another
group had surgical repair; non op treatment of Grade II injuries were
as good as those who underwent surgery (86% good-excellent results);
Grade III had 64% good-excellent results
Indelicato published his classic study on non-operative
treatment of Grade III MCL injuries in 1983, demonstrated that those
with non-operative treatment fared as well as those having surgery;
additionally, the non-op group regained their strength faster (op:
casted x 6 weeks; non-op, casted x 2 weeks, then hinge brace WBAT x 4 wks)
Jones took Indelicato's study one step farther; there was no
surgical repair or EUA; they were immobilized x 1 week, then in a
hinge brace which was increased weekly, WBAT; athletes returned to
practice in a mean of 34 days (2 cases were LCL)
Woo, 1987 (AJSM) studied the effects of: no repair with cage
and farm activities, repair with 3 weeks immobilization or repair with
6 weeks immobilization in dogs with surgical transection of their MCL;
the group with no repair did the best, suggesting early mobilization;
The study also found the mechanical properties of the MCL to
be incomplete, even at 48 weeks; tensile values were 49% of the
controls in the no repair group at 12 weeks
Effects of Immobilization/remobilization:
effects of immobility on the bone, ligament insertion sites and
the ligament substance are all separate but important issues
immobilization for 9 wks resulted in a clear disruption of the
deep fibers inserting into bone at the tibial insertion; osteoclast
activity lead to resorption of subperiosteal bone and disruption of
the attached ligament fibers; there were minimal changes at the
femoral insertion; failure occurred exclusively by avulsion of the
MCL at the tibial insertion site (Woo, JBJS, 1987)
decreases in the tensile strength were found for the rabbit MCL
following 9 wks immobilization; histologic changes included widely
spaced irregular collagen fascicles, GAG degradation, decreased
cytoplasmic and mitochondrial enzymatic activity
18 wks of remobilization were required to restore the
structural properties of the FMTC following 6 wks of immobilization
(Laros)
ligament substance seems to return quickly (within 9 wks
following 9 wks immobilization); structural properties were inferior,
with ultimate load and energy absorbed at failure only 80% of
controls; failure occurred at insertion sites (incomplete
organization at these sites)
Woo states that a remobilization period of up to sixfold that
of the time of immobilization may be required for recovery
Grades I & II:
Acute care:
RICE
immobilization for comfort only
crutches if abnormal gait pattern
Early:
rehab limited by pain and knowledge of ligament biomechanics
ROM
CV - bike, rowing erg, Nordic track
PRE - avoid valgus stress across knee
balance & proprioception exercises
Intermediate:
progress PRE program
begin loading ligament under controlled conditions; work patient in
the frontal plane; work both WB & NWB frontal plane activities
progress CV training (intervals, etc.)
progress balance and proprioception training
Late:
progress loading in frontal plane
progress CV training to running program
provocative program
More severe injuries: PROGRESSION of rehab is the same; only the time
frame changes
Grade II+:
treatment is symptomatic; rehab as above, with the exception of
brace immobilization for acute symptoms, and controlled, increased
motion with protection for 3-6 weeks
Grade III:
treatment is symptomatic with a protective brace, allowing controlled motion
last 15 degrees of extension is limited early, while varus/valgus motion is protected for 5-6 weeks
may use valgus brace on return to activity depending upon activity of the patient
Grade III+:
treatment as for Grade III
Surgery may be indicated acutely or later with functional loss
Treatment of LCL injuries
relatively infrequent
shape of LCL makes primary repair less effective
be aware of peroneal nerve and cruciate injuries
Grade I: conservative management as above
Grade II: conservative management with mild to moderate lateral
instability peristing
Grade III: conservative management usually results in persistent
functional disability which may progress; surgical repair or
reconstruction is the treatment of choice