Download A Litigation Primer On The Knee

15 No. 4 Prac. Litigator 7
Practical Litigator
July 2004
A LITIGATION PRIMER ON THE KNEE
Samuel D. Hodge, Jr.a1
Copyright © 2004 by the American Law Institute; Samuel D. Hodge, Jr.
WHAT DO Picabo Street, Terrell Davis and Joe Namath have in common? They all suffered
knee injuries that shortened their successful athletic careers. While the news is replete with
stories of professional athletes who suffer devastating knee injuries, the problem is much
more pervasive. The American Academy of Orthopedic Surgeons estimates that almost 11
million people a year visit physicians because of knee problems, and it is the most common
medical issue addressed by orthopedic surgeons. Knee problems can result from a disease
process, a blow to the joint, certain occupations, and the normal wear and tear of daily life.
Even recreational activities such as weight lifting and jogging can have serious ramifications.
Surprisingly, women suffer more knee injuries than men due to a wider pelvis, and hormonal
differences. *8 Knee symptoms in the general population have been estimated to be as high
as 54 percent, with 70 percent of the problems occurring suddenly while playing sports.
Baker et al., Knee Disorders in the General Population and their Relation to Occupation, 60
Occupational & Envtl. Med. (Oct. 2003). Treatment can range from rest to surgery and injuries
can have lifetime implications with continuing knee complaints and future disability. This
article will provide an anatomical overview of this important structure with a discussion of
the tests used to diagnoses knee problems and it will offer tips on litigating a knee injury
claim.
THE ANATOMY • The knee is a hinged joint whose unique anatomical construction makes it
prone to injury. Not only is the knee required to move up and down but it must also rotate
sideways. Because of this four-way movement, the joint has very little stability to allow for
this maximum flexibility.
The Bones
Four bones make up the knee: the femur, the tibia, the fibula, and the patella. The femur is located in
the thigh, is the largest bone in the body and forms the top part of the knee joint. The tibia is the
larger of the two bones in the lower part of the leg and is located on the inside or medial side of the
limb. The top of the tibia meets the bottom of the femur and is responsible for supporting the body's
weight. The fibula is the smaller bone adjacent to the tibia and is on the outer or lateral side of the
leg. The patella or knee cap completes the knee joint. This sesamoid bone is several inches in
diameter, is located at the front of the knee and protects the joint from trauma. It also moves up and
down over the bottom end of the femur or femoral grove as the leg moves back and forth. See
Figure 1.
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Soft Tissues
The ends of the bones are covered with articular cartilage. This slippery substance helps absorb
shock and assists the bones during movement by providing a smooth surface. Ligaments attach
bone to bone and the knee has four such connective bands: two in the center of the joint, the
cruciate ligaments, and one on each side of the knee, the collateral ligaments. The cruciate
ligaments are so named because they criss-cross in the middle of the joint and are crucial to the
primary movements of flexion and extension. The anterior cruciate ligament (“ACL”) is the most
important of the ligaments and originates at the front or anterior part of the tibia and attaches to the
posterior aspect of the femur. The ACL prevents the tibia from moving too far forward or from
hyperextending. By contrast, the posterior cruciate ligament (“PCL”) is a short, thick fiber that
originates at the back or posterior part of the tibia and attaches to the femur. Its function is to prevent
the abnormal backward movement or hyperflexion of the tibia. See Figure 2.
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*9 The collateral ligaments stabilize the knee when it moves sideways. The lateral collateral ligament
(“LCL”) is located on the outside or lateral part of the joint and attaches to the femur and fibula. It
provides stability to that area of the knee. The medial collateral ligament (“MCL”) is on the inner or
medial side of the joint and attaches to the front of the femur and tibia. This ligament provides
stability to the inner side of the lower limb.
The Meniscae
As the bones of the back are separated by discs, the knee has two cushions called meniscae that
separate the femur and tibia. Each meniscus serves as a shock absorber and is shaped like a half
moon or horseshoe. It provides stability to the joint, and keeps the femur and tibia from rubbing
against each other. The meniscus also supplies the knee with lubrication and is named based upon
its anatomical orientation. The medial meniscus is located on the inside part of the joint and attaches
to the medial collateral ligament. The lateral meniscus serves as the outer cushion of the knee joint
and is the larger of the two fibrocartilages. Because it is more mobile, the lateral meniscus is injured
less frequently than the medical meniscus. Campbell's, Operative Orthopaedics 1133 (S. Terry
Canale ed., Mosby 9th ed.1998). See Figure 3.
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Limited Vascular Area Of Meniscus
Blood is critical to the healing process and only a small part of the meniscus is vascularized. In fact,
less than 30 percent of the outer edge of the medial meniscus and less than 25 percent of the outer
part of the lateral meniscus has a direct blood supply. The remaining portion of the cartilage receives
its nourishment from synovial fluid. Timothy Brindle et al., The Meniscus: Review of Basic Principles
with Application to Surgery and Rehabilitation, 36 J. Athletic Training 160 (Apr.-June 2001). This
distinction is important in the prognosis of a meniscal injury. Tears at the outer perimeter of the
meniscus tend to heal nicely. Since the remaining portion of the cartilage lacks a blood supply, it
does not heal well, either by itself or through surgical intervention. Meniscus Tear--An Overview,
Web MD, http:// aolsvc.health.webmd.aol.com/hw/sports_and_fitness/te7349.asp. See Figure 4.
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Basic Musculature
The knee has several muscle groups that provide for movement allowing the leg to move up, down,
and sideways. The quadriceps muscles are the largest muscles in the leg and allow a person to walk
by providing for knee extension. It is generally understood that the quadriceps muscles and extensor
apparatus is the key *10 element in allowing individuals to maintain the upright position. John J.
Garthland, Fundamentals of Orthopedics 406 (W. B. Saunders, 3d ed. 1979). They are located in the
anterior part of the thigh and consist of four individual muscles that power the leg in forward
motion. These muscles are the rectus femoris, vastus lateralis, vastus medialis, and vastus
intramedius muscles. The hamstring is located in the back of the thigh and runs from the hip to just
below the knee. This muscle allows the leg to flex or to be brought backwards. See Figure 5.
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THE INJURY • Many times the mechanism of trauma is opposite of what would seem logical.
This is readily apparent in injuries to the collateral ligaments which occur when the knee is
abnormally forced sideways. A blow to the outside of the knee, such as a clip in football, will
injure the opposite side or the medial collateral ligament. On the other hand, an injury to the
lateral collateral ligament requires a blow to the inside of the knee. See Figure 6.
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The ACL can be hurt by a force to the back of the leg that drives the tibia forward. The ACL can also
be injured in deceleration, twisting, and hyperextension. Cruciate Ligament, Amersham Health,
www.amershamhealth.com/medcyclopaedia. For example, this ligament can be torn when the foot is
planted during a sudden stop but the knee continues to change direction. The posterior cruciate
ligament may be injured by a blow to the front of the knee that causes the tibia to be driven
backwards. This may occur in a car accident when the shin strikes the dashboard or during football
when a frontal tackle is made. See Figures 7 and 7a.
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*11 Sprains And Strains
The terms “sprain” and “strain” are frequently used in the diagnosis of a knee injury but the words
mean very different things. A sprain describes a stretching or tearing of a ligament. A strain, on the
other hand, refers to a comparable injury to a tendon or muscle.
Grading
A sprain to either the cruciate or collateral ligaments is assigned a grade from one to three
depending upon the severity of the injury. A Grade I sprain involves a stretching of the ligament but it
does not involve a tear. A Grade II sprain refers to a partial tear of the ligament. A Grade III sprain
deals with a complete tearing and loosening of the ligament causing the joint to become unstable.
Meniscus Injuries
A meniscus cannot be injured while the knee remains straight. Rather, a tear can only occur when
the joint is first rotated in a flexed position thereby catching the meniscus and then extended to
produce the tearing force on the tissue. Fundamentals of Orthopaedics, supra at 414. For example,
a tear can occur when a person turns to hit a tennis ball or by dribbling a basketball around an
opponent. Questions and Answers about Knee Problems, National Institute of Arthritis and
Musculoskeletal and Skin Diseases, May 2001, NIH Publication No. 01-4912, http://
www.niams.nih.gov/hi/topics/kneeprobs/kneeqa.htm. See Figure 8.
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Trauma to the knee can result in multiple abnormalities with the most devastating combination being
the “terrible triad.” This injury consists of a torn meniscus, an ACL injury, and a sprain of the medial
collateral ligament-- all from a single blow. This combination injury usually requires surgery. Causes
of Knee Pain, Park Nicolett Health Advisor,
www.parknicollet.com/healthadvisor/conditions/kneepain_2.cfm.
Investigative Factors
From an investigative point of view, a person's age and location of the tear are important factors to
examine. Meniscal injuries in individuals under 30 are usually the result of a forceful twisting of the
knee occurring during recreational activity. In older people, the meniscus weakens making it prone to
degeneration. Generally, there isn't one specific incident of trauma that results in a degenerative
tear. Rather, tears occur from osteoarthritis of the knee in aging adults caused by the normal wear
and tear of daily life. A Patient's Guide to Knee *12 Anatomy, Medical Multimedia Group,
www.medicalmultimediagroup.com. See Figure 9.
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A traumatic tear tends to be vertical and is located at the edge of the meniscus. Degenerative tears
are usually horizontal and arise in the back part of the meniscus. Torn Meniscus: Information,
Harvard Medical School's Consumer Health Information, E-Health Forum,
http://ehealthforum.com/health/subject38_ 309624_what.html.
Chondromalacia
Chondromalacia is a softening or loss of articular cartilage on the underside of the patella resulting in
dull pain and crepitus (clicking) in the knee cap area. Instead of gliding smoothly across the lower
end of the femur, the undersurface of the patella rubs against the bone causing a roughening of the
cartilage underneath the knee cap. Questions and Answers about Knee Problems, National Institute
of Arthritis and Musculoskeletal and Skin Diseases, supra. As the condition worsens, the damaged
cartilage begins to fray and bits of tissue can float inside the joint space causing additional irritation.
This pain seems to worsen with stair climbing and is most prevalent in young adults and workers
who spend a lot of time kneeling. This condition can result from trauma to the knee, overuse of the
joint, arthritis, and improper alignment of the bones and muscles around the knee. Chondromalacia
is common in athletes who repeatedly bend their knees such as runners and cyclists.
Chondromalacia: What Is It? Harvard Medical School's Consumer Health Information, E-Health
Forum, http://ehealthforum.com/health/subject38_344926_what.html. See Figure 10.
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The patella may be fractured by a direct blow to that area which might occur by falling on the knee or
by the knee hitting the dashboard. It can also be damaged by sudden and violent contraction of the
quadriceps muscles. Fundamentals of Orthopaedics, supra at 411.
*13 THE DIAGNOSIS • The diagnosis of a knee injury is made by physical examination,
diagnostic imaging, or surgery. Examination of the knee will include a visual observation of
the limb for swelling, bruising, and anatomical abnormalities. The knee will be palpated,
undergo range of motion testing, and the patient will be requested to walk, stand, squat, and
bend the joint. The physician will then administer one or some combination of the following
specifically designed tests depending upon the patient's complaints.
Drawer Sign
The integrity of the cruciate ligaments can be tested by having the patient recline in a supine
position. While the leg is bent and the foot is planted on the ground, the tibia is pulled forward and
pushed backward. Laxity in the joint will demonstrate a tear or sprain. If the tibia can be pulled
forward beyond its normal anatomical position, an ACL injury is suspected. If the tibia can be pushed
backward beyond its normal position, a PCL tear is assumed.
Lachman Test
This test is considered the most accurate in ascertaining the integrity of the ACL. While the physician
holds the bottom portion of the patient's femur, the upper end of the tibia is pulled forward while the
doctor's thumb is placed on the tibial portion of the joint. An injury will be demonstrated by increased
laxity in the knee.
McMurray Test
Injuries to the meniscus may be confirmed by twisting the knee as the leg is being extended. Pain,
clicking, or a grinding sound may demonstrate a tear to this soft tissue structure.
Apley's Compression Test
While the patient lies flat on the examining table, the lower limb is raised to 90 degrees. The
physician then applies pressure to the back of the heel as the tibia is turned to ascertain if joint pain
is produced.
Compression Test
The medial and lateral ligaments may be checked by flexing and extending the leg while the
physician places pressure on the opposite sides of the knee joint. The bottom portion of the leg may
also be extended over the end of a table while it is moved sideways in valgus (away from the
midline) and varus (towards the midline) movement. The severity of an injury to the collateral
ligaments may be ascertained by measuring the opening in the joint line.
Imaging
A number of diagnostic tests are available for confirming a suspected knee injury. These procedures
can range from the traditional x-ray to actually looking inside the knee with a lighted fiber optic
scope. They include:
• X-ray. An x-ray allows for the visualization of anatomical abnormalities such as fractures, loose
bodies, bone tumors, and osteoarthritis;
• CT-Scan. With the aid of a computer, an x-ray beam can be angled as it passes through the knee
thereby producing three-dimensional views of fractures and the soft tissues such as ligaments;
• MRI. By combining a powerful magnet with radio waves, exquisite images of the internal structures
of the knee can be produced revealing injuries to the ligaments and meniscus. This test is noninvasive, and is the gold standard in the diagnosis of a knee injury;
• Bone Scan. By the use of a radioactive tracer that is injected into the bloodstream, tumors, subtle
fractures, and infections can be identified on x-ray examination;
• Arthroscopy. This invasive procedure involves the insertion of a small tube equipped *14 with a
camera and light into the knee joint allowing for the visualization, diagnosis, and repair of the
ligaments and meniscus;
• Arthrogram. Water and air are injected into the joint providing for a more sophisticated x-ray
examination of the knee. This procedure is able to visualize tears in the meniscus and cruciate
ligaments but the test has been generally replaced by the MRI; and
• Arthrocentesis. A needle is inserted into the knee joint and synovial fluid is removed for analysis
and to remove pressure caused by an excessive accumulation of fluid. The color of the fluid is
diagnostic with blood tinged fluid indicating an acute injury such as a recent tear of a cruciate
ligament and yellow fluid demonstrating an infection.
LITIGATION TIPS • The prevalence of knee complaints in the general population requires a
proper investigation of a personal injury claim to ascertain the cause of the problem. Special
attention should be paid to pre-accident knee problems, a person's occupation, weight, and
the location of the knee abnormality.
Prior Medical Records
At a minimum, the records of the claimant's family doctor should be examined to see if the patient
had prior knee complaints, since these individuals are statistically at risk in developing knee
problems later in life. For example, a study funded by the National Institute on Aging discovered that
knee injuries in individuals under 22 had a higher rate of developing osteoarthritis later in life than
the general population. Another study determined that individuals who have documented meniscal
tears in one knee have an advanced degree of meniscal degeneration in the opposite, asymptomatic
knee which predisposes them to traumatic or spontaneous tears of that meniscus. Negendank et al,
Magnetic Resonance Imaging of Meniscal Degeneration in Asymptomatic Knees, 8 J. Orthopaedic.
Res. 311 (May 1990).
Work-Related Duties
The medical literature notes a significant correlation between knee problems and certain work
related duties so this avenue should be considered when handling a knee injury claim. Individuals
whose occupation involves heavy work, kneeling, or squatting, demonstrate a significantly increased
prevalence of knee osteoarthritis. L. Kirkeskov Jensen & W. Eenberg., Occupation as a Risk Factor
for Knee Disorders, 22 Scand. J. Work, Env't & Health 165 (June 1996). For example, miners,
construction workers and carpenters are at increased risk for developing knee pain. S. C. O'Reilly et
al., Occupation and Knee Pain: A Community Study, 8 Osteoarthritis Cartilage 78 (Mar. 2000).
Carpet and tile layers, gardeners, and maids are also in occupations that predispose them to future
knee problems.
Location Of The Injury
The location of the injury is helpful in ascertaining the cause of the problem. Horizontal tears of the
meniscus are frequently found in asymptomatic knees and may not be related to the patient's
symptoms. However, vertical, complex, or displaced meniscal tears and collateral ligament
abnormalities are generally found on the symptomatic side and appear to be clinically more
meaningful. Marco Zanetti et al., Patients with Suspected Meniscal Tears: Prevalence of
Abnormalities Seen on MRI of 100 Symptomatic and 100 Contralateral Asymptomatic Knees, 181
Am. J. Roentgenology, 635 (September 2003).
The Asymptomatic Population And Diagnostic Imaging
Advancements in diagnostic imaging routinely uncover abnormalities in the asymptomatic
population. These abnormal findings in a *15claims setting are particularly troubling because of the
obvious financial implications. Abnormal findings in the back in the asymptomatic population on
diagnostic imaging have been well documented. See my earlier article, Defending the Back Injury
Case, which appeared in the September 2002 issue of The Practical Litigator. The knee is subject to
similar problems especially on MRI testing.
One study performed to ascertain the prevalence of abnormal MRI scans of the knees of
asymptomatic volunteers determined that almost six percent of the test group had meniscal tears. In
fact, 24.1 percent of these volunteers had Grade II signal changes in the posterior horn of the medial
meniscus. Robert F. LaPrade et al., The Prevalence of Abnormal Magnetic Resonance Imaging
Findings in Asymptomatic Knees: With Correlation of Magnetic Resonance Imaging to Arthroscopic
Findings in Symptomatic Knees, 22 Am. J. Sports Med. (Nov.-Dec. 1994). An investigation at
George Washington University Medical Center discovered that 16 percent of the asymptomatic test
group had tears of the meniscus on MRI testing. The prevalence of meniscal tears increased from
13 percent in people under 45 to 36 percent in those older than 45. The authors concluded that the
high incidence of abnormal MRI findings in the asymptomatic population underscores the danger of
relying on diagnostic imaging without careful correlation with clinical signs and symptoms. S. D.
Boden et al., A Prospective and Blinded Investigation of Magnetic Resonance Imaging of the Knee:
Abnormal Findings in Asymptomatic Subjects, 282 Clin. Orthopaedics (September 1992). See also,
Fukuta et al., Prevalence of Abnormal Findings in Magnetic Resonance Images of Asymptomatic
Knees, 7 J. Orthopaedic Sci. 287 (May 2002).
Obesity
Obesity causes many health problems and knee difficulties are one such risk. A number of research
studies have found a correlation between knee osteoarthritis and obesity. See D. Coggon et al.,
Knee Osteoarthritis and Obesity, 25 Int'l. J. Obesity & Related Metabolic Disorders 622 (May 2001).
CONCLUSION • The knee is a complex mechanism susceptible to injury because of its unique
anatomical design. This joint is required to move in four directions, so it has no inherent
stability and must rely on soft tissues to hold it in place. As a result, knee difficulties are the
most common reason why people visit orthopedic surgeons. A number of factors unrelated
to trauma have been associated with knee problems. Therefore, an attorney handling a knee
injury claim should conduct a careful investigation of the claimant's background to ascertain
the real cause of the problem.
Footnotes
a1
Samuel D. Hodge, Jr. is Professor and Chair of the Department of Legal Studies at Temple
University, in Philadelphia.