Objectives:
i.
ii.
iii.
iv.
v.
vi.
Describe and be able to perform a physical examination of the knee
List the differential diagnoses for knee pain
Describe the incidence and consequences of knee injuries in the
female athlete
Describe the symptoms and signs of Lyme Disease
Describe the laboratory evaluation of knee pain and be able to
apply this to the clinical presentation of a patient with knee pain.
Describe treatment options for Chondromalacia Patella
USC Case # 8: Knee Pain
History of Present Illness (HPI):
Scarlet O’Hara is a 19 yo black female college student who presents to your office with
right knee pain. She denies any trauma but frequently participates in recreational sports
activities such as basketball, running and tennis. She describes her pain as being “around
my kneecap” and rates it a 4 or 5 on a scale of 10. She notes that her knee doesn’t really
swell up with fluid but is sometimes a little “puffy”. She has had no locking or giving out
but notes that climbing or descending stairs makes her pain worse. She does note an
occasional “grinding” sensation behind her kneecap. Prolonged sitting in class makes the
pain worse when she first gets up but after a few steps the pain usually gets better. She’s
been taking advil over the last few weeks with some temporary relief of symptoms.
Past Medical History:
Immunizations are up to date. She denies fevers or rashes. There is no family history of
lupus or rheumatoid arthritis. Father is diabetic. Mother is hypertensive. Grandmother has
had a hip replacement for arthritis. She has had a previous tonsillectomy. She has had a
previous ACL reconstruction during her junior year of High School on the left knee. This
summer she worked as a camp counselor and on one of the hikes she thinks she was
bitten by something, maybe a tick but she is not sure. It was some type of bite that was
“red for a few days but got better on its own”.
Question: What is the importance of the previous ACL reconstruction on the left
(asymptomatic) knee?
Answer: Previous joint injuries or operations are always a relevant part of the
musculoskeletal history. Regarding this injury it is unlikely that there is a “cause and
effect” relationship unless she is still symptomatic or has some weakness in the
previously operated knee resulting in an “overload” of the right knee.
Question: Is gender an issue in knee injuries?
Answer: There is a four-fold to eight-fold higher incidence of knee injuries in females than
males in jumping and cutting sports including basketball, soccer, volleyball and others. In
female athletes knee injuries account for up to 91% of season ending injuries and 94% of
those injuries requiring surgery. Season ending knee injuries occur at a rate as high as 1 in
10 female athletes annually at the intercollegiate level (i.e. 15,000 female athletes lost each
year to athletic participation). At a rate of approximately 1 in 65 ACL injuries per participant
annually, approximately 7000 ACL ruptures occur in high school female basketball players
alone in the United States on an annual basis. Higher rate of injury in female athletes
combined with dramatic increase in female participation since Title IX in 1972 has led to a
geometric increase in the number of musculoskeletal injuries in female athletes over the last
three decades.
Question: Is the possible tick bite relevant?
Answer: Maybe. Her history is pretty sketchy here but we will need to consider this in
the differential. A tick bite with joint pain may indicate a Lyme arthritis. Lyme disease is
an inflammatory disease characterized by a skin rash, joint inflammation, and flu-like
symptoms, caused by the bacterium Borrelia burgdorferi transmitted by the bite of a deer
tick. Lyme disease was first described in the United States in the town of Old Lyme,
Connecticut in 1975, but has now been reported in most parts of the United States.
Early localized disease refers to a red rash in the area of the tick bite. This rash shows up
within a month of infection. The bite itself is usually found near the waist or belt line, or
in other warm, moist areas of the body. The bite may burn, itch, or hurt. The rash usually
grows over a period of days and may be in a "bulls eye" pattern, red with a white spot in
the middle, or completely red.
__________
While she doesn’t describe the “classic” rash she does remember the bite area as being a
little red.
Physical Examination:
She is alert, oriented and cooperative and shows appropriate concern for her injury. She is
dressed in gym shorts and sneakers. You ask her to take her shoes off and watch her walk
briefly in the hall. She has no limp but you note that she is “flat-footed”. You also note
that she has a somewhat “valgus” knee alignment with an increased “Q” angle. Her mom
states that she has been that way all of her life. When she was a toddler she wore “special
shoes”. They tried some over the counter arch supports a few years ago but she found
them too uncomfortable to play in. She complains that her hamstrings are “tight”.
With respect to the knee evaluation you examine the uninvolved knee first and there is no
specific abnormality noted. When examining the right knee you note no ligamentous
laxity, no joint line tenderness and no effusion. She has audible and palpable subpatellar
crepitation with knee flexion and extension. She has a positive “patellar grind” test and
tenderness to palpation over the lateral patellar facet. Leg lengths are equal. She has
bilateral hamstring tightness. With knee extension in the seated position she has a
positive “inverted J sign”.
The distal neurovascular status is intact. There are no rashes or skin changes noted.
Question: What is your differential diagnosis?
Answer: 1) Bilateral Pes Planus 2) Lyme Arthritis 3) Chodromalacia Patella 4) Patellar
Tendonitis 5) Osgood Schlatter Disease
Bilateral pes planus is a correct diagnosis based on your careful observation. It is likely
related to the primary diagnosis but is not the only reason for her knee pain. Her previous
orthotics were uncomfortable so you recommend custom orthotics which should have a
better fit than the over-the-counter type that she previously tried.
Lyme arthritis is a possibility based on her history of possible tick bite. She does not
describe the “classic” bulls eye rash but does remember having a “red spot”. You order a
Lyme a titer blood test which is negative making this diagnosis unlikely.
Chondromalacia Patella is a correct diagnosis and is likely the major cause of her knee
pain. She has a number of positive historical clues including: grinding behind the
kneecap, pain with stair climbing, and pain after prolonged sitting. Biomechanical risk
factors include bilateral pes planus and increased “Q” angle (see above). From the
perspective of her examination she has pain over the lateral patellar facet, subpatellar
crepitation and an “inverted J sign”. This sign is characterized by lateral subluxation of
the patella during terminal knee extension and can be indicative of weakness of the vastus
medialis oblique muscle.
Patellar tendonitis is an incorrect diagnosis but a common cause of anterior knee pain in
young athletes. This diagnosis would not cause subpatellar crepitation or an “inverted J
sign”. You would also generally note pain with palpation and tenderness with direct
palpation over the patellar tendon which was not present in this case.
Osgood Schlatter Disease is an incorrect diagnosis but also a common cause of anterior
knee pain in young athletes. It is more common in males than females (7 to 1 ratio) and
generally occurs in the 10-14 year old age group. The most characteristic finding is
localized pain and swelling at the tibial tuberosity secondary to inflammation at this
apophysis (growth plate).
Further Discussion and Treatment Recommendations:
Mom wants to know if an MRI is needed to make this diagnosis. You indicate to her that
90% of non-traumatic knee pain can be diagnosed based on history, physical examination
and plain x-rays. MRI is seldom needed but often requested. History alone will allow an
accurate diagnosis up to 70% of the time.
Mom is satisfied with that answer but wants to know what needs to be done to “get this
knee fixed”. Your recommendations include: 1) a period of “relative rest” with emphasis
on non-impact aerobic activity, 2) quadriceps strengthening with emphasis on the vastus
medialis oblique muscle, 3) hamstring flexibility exercise, 4) custom orthotics to address
her “flat feet” and knee alignment issues, 5) icing especially after activity, 6) a short
course of anti-inflammatory medication (such as ibuprofen for 10-14 days), and 7) you
discuss the possible use of a knee sleeve as a temporary measure to improve her patellar
tracking.
Finally, you schedule a follow up visit for two weeks to monitor her progress.
SUMMARY AND RECOMMENDATIONS
●The history is critical to understanding the cause of an athlete or active adult’s knee pain.
Important elements of the history include distinguishing between acute and chronic knee
pain, identifying any trauma that may have caused the knee pain, learning the mechanism
of injury if trauma was involved, and understanding what activities the patient participates in
that may contribute to their symptoms. A review of useful questions to elicit the history is
provided in the text.
●The physical examination of any joint is classically divided into inspection, palpation, range
of motion testing, strength and neurovascular testing, and special maneuvers to assess for
specific diagnoses. Special tests are selected based upon the most likely diagnostic
category, which is based in turn upon the history, including the mechanism of any injury and
the chronicity (acute or chronic) of pain. The knee examination is described in detail
separately.
●Using information from the history, key symptoms, and findings from the basic knee
examination, the clinician can usually select one of three common diagnostic categories that
best fits the patient. The three major categories are:
•Acute knee pain, either from trauma or associated with overuse
•Chronic knee pain associated with overuse
•Knee pain without trauma or overuse, possibly associated with systemic symptoms
●A history of acute knee pain associated with trauma is usually clear-cut, although the
precise mechanism may be difficult to establish. Such a history allows the clinician to focus
on the knee-related structures most likely to have been injured. These include the collateral
and anterior cruciate ligaments and the menisci. Testing the stability of these structures,
identifying points of focal tenderness and the presence of an effusion, and performing
special tests to confirm suspicions about the structures involved comprise the core of the
initial evaluation of acute trauma-related knee pain.
●Chronic knee pain associated with overuse has typically persisted for approximately six
weeks or longer and is not associated with any sudden inciting trauma. Chronic knee pain
associated with overuse is progressive, becoming more painful with increasingly less
intense activity over time. Typically, the knee examination reveals no structural instability.
Many such patients suffer from patellofemoral pain or another condition related to the
patella or surrounding soft tissues (eg, pes anserine, iliotibial band). In older patients, a
degenerative meniscus or osteoarthritis must be considered.
●Patients with knee pain that developed or increased abruptly after excessive activity but
who clearly have not sustained trauma of any kind often suffer from acute-on-chronic pain
related to overuse (“overuse trauma”). The pain associated with overuse trauma often
arises towards the end of an activity that exceeds what the athlete has trained to do or
follows some change in training.
●Chronic or acute knee pain in an adult without inciting trauma or a history of overuse is a
“red flag” that a more extensive evaluation is required, particularly if the pain is associated
with constitutional symptoms, such as fever. The cause of such pain is much less likely to
be musculoskeletal.
Uptodate.com
Readings: Rakel’s Textbook of Family Medicine pp 669 - 677
References:
Andrews JR and Axe MJ. The classification of knee ligament instability. Orthop Clin North Am
1985;16:69-82.
Arendt E and Dick R. Knee injury patterns among men and women in collegiate basketball and
soccer. NCAA data and review of literature. Am J Sports Med 1995;23:694-701.
Boden BP, Dean GS, Feagin JA, Jr., and Garrett WE, Jr. Mechanisms of anterior cruciate
ligament injury. Orthopedics 2000;23:573-8.
Chandy TA and Grana WA. Secondary School Athletic Injury in Boys and Girls: A Three-Year
Comparison. Physician Sportsmed 1985;13:106-11.
Chappell JD, Yu B, Kirkendall DT, and Garrett WE. A comparison of knee kinetics between
male and female recreational athletes in stop-jump tasks. American Journal of Sports
Medicine 2002;30:261-7.
Cox JS and Lenz HW. Women midshipmen in sports. Am J Sports Med 1984;12:241-3.
DeHaven KE and Lintner DM. Athletic injuries: comparison by age, sport, and gender. Am J
Sports Med 1986;14:218-24.
Ferber R, Davis IM, and Williams DS. Gender differences in lower extremity mechanics during
running. Clinical Biomechanics 2003;18:350-7.
Ford KR, Myer GD, and Hewett TE. Valgus knee motion during landing in high school female
and male basketball players. Medicine and Science in Sports and Exercise 2003;35:174550.
Gray J, Taunton JE, McKenzie DC, Clement DB, McConkey JP, and Davidson RG. A survey of
injuries to the anterior cruciate ligament of the knee in female basketball players. Int J
Sports Med 1985;6:314-6.
Griffin LY, Agel J, Albohm MJ et al. Noncontact anterior cruciate ligament injuries: risk factors
and prevention strategies. J Am Acad Orthop Surg 2000;8:141-50.
Hewett TE, Lindenfeld TN, Riccobene JV, and Noyes FR. The effect of neuromuscular training
on the incidence of knee injury in female athletes - A prospective study. American
Journal of Sports Medicine 1999;27:699-706.
Hutchinson MR and Ireland ML. Knee Injuries in Female Athletes. Sports Med 1995;19:288-302.
Loudon JK, Jenkins W, and Loudon KL. The relationship between static posture and ACL injury
in female athletes. J Orthop Sports Phys Ther 1996;24:91-7.
van Eijden TM, de Boer W, and Weijs WA. The orientation of the distal part of the quadriceps
femoris muscle as a function of the knee flexion-extension angle. J Biomech
1985;18:803-9.
Zillmer DA, Powell JW, and Albright JP. Gender-Specific Injury Patterns in High School Varsity
Basketball. J.Women's Health 1992;1:69-76.