Evaluation and Management of Knee Injuries

2007 Update

Courtesy of John Whiteside, MD


Knee is not the most commonly injured joint (ankle), but it has…

Greatest susceptibility to wear and tear, inflammatory and septic arthritis


Differential Diagnosis of Knee Pain:

1.   Internal derangement (Meniscus, Ligament, etc)

2.   Fracture

3.   Patellofemoral Pain Syndrome

4.   Cartilage loss (osteoarthritis or synovitis)

5.   Bursitis, tendonitis, friction syndromes (ITB, medial plica)

6.   Synovitis, inflammatory arthritidies

7.   Gout, pseudogout

8.   Referred pain from hip, spine, etc.



Any trauma or acute injury?

      Yes:     Mechanism of injury?

                        Direct blow?

                        Foot planted?



                        Hyperextension?  (consider ACL)

                  Hear or feel “pop”? (noises are non-specific)

                  Injury stop play?


Swelling immediate (within 2 hours) or after several hours (next day)?

                  Lock or give-way?


      No:      Any new activities?

                  Increased volume?

                  Increased intensity?

                  Increased hills?

                  Increased weight-lifting?

                  Increased jumping?

                  Increased explosive movements (pylometrics)?


      Onset insidious or rapid?

      Where does it hurt? Most?  Use one finger!

      When does it hurt?  Rest, activity, up or down stairs?

      Cinema sign?


Physical Exam of the Knee

1.   Patients must be comfortable and relaxed for exam

      a.   Inform patients what you are doing and that goal is not to cause pain

      b.   Reassure that testing will not hurt (and mean it!)

      c.   Avoid or skip tests that cause pain.  (I never do a Patellar Grind Test.)

      d.   Test the uninjured joint first--both for your comparison and to reassure patient.

      e.   Use an exam table that solidly supports patient, neither narrow nor flimsy.

Any quadriceps and/or hamstring tension will mask knee instability and invalidate your exam.


2.   Look for concomitant injuries.  Any force significant enough to produce damage to one tissue will likely damage others


3.   You must have a mental picture of the anatomy (some knees are chubby).  The exam is a deliberate process of considering each anatomic component of the joint and evaluating it for pain and integrity.


4.   The knee exam is stepwise:

      1.   Survey visually

      2.   Check for effusion

      3.   Palpate structures (use your MRI)

      4.   Stress:

            a.   Collateral ligaments

            b.   Cruciate ligaments

            c.   Menisci


A.  Survey Visually

      1.   Contusion.  Asymmetrical swelling, bruising, and abrasion

      2.   Bursitis.  Focal, extra-articular swelling and tenderness

            a.   Prepatellar - kneeling

            b.   Superficial Infrapatellar - kneeling

            c.   Pes Anserine - often in the setting of Osteoarthritis

      3.   VMO atrophy?

      4.   “J” sign

      5.   Gait.  Some authors recommend “duck waddle” and squat as components of every exam.  These are effective for quick, global screening of knee function (e.g. during preparticipation sports physicals), but are not particularly helpful in the patient who presents with knee injury.


B.  Check for Effusion

Effusion = fluid collected within the synovial membrane of the knee joint.  Therefore, consider what is inside the synovial membrane.


      Effusion implies injury to one of 3 structures:           

            Cruciate ligaments


            Articulating cartilage/bone



      Effusion:  Differential Diagnosis:

            Normal (~ 15% of population)

            Intraarticular derangement (hemarthrosis)




Seronegative spondyloarthropathies (IBD, psoriasis, Reiter’s)

Rheumatoid arthritis  (and other Connective Tissue Disorders)




Large effusion:      “ballotable patella”

Small effusion:      milk the suprapatellar pouch and feel/watch for infrapatellar fluid                                              shift





      1.   Medial joint line Ž                             Fracture of tibial plataeu

                                                                        (frequency of lateral > medial fx’s)

                                                                  Medial compartment osteoarthritis

                                                                  Medial meniscal tear


2.   Medial collateral ligament Ž              MCL tear or strain


3.   Pes anserine bursa Ž                          Bursitis


4.   Medial plica (RARE!) Ž                    Medial plica syndrome



1.   Superior-lateral aspect of patella Ž    PFPS


2.   Prepatellar bursa Ž                             Bursitis


3.   Inferior pole of the patella Ž             Patellar tendonitis, “jumper’s knee”


4.   Medial border of patella Ž                Patellar subluxation or dislocation


5.   Tibial tubercle Ž                                Osgood-Schlatter disease


6.   Diffuse B/L knee pain & swelling

                              Not hot, red Ž           OA in multiple compartments

                              Hot, red, tender Ž     Inflammatory arthritis

                                                                  (rheumatoid, crystalline)

                                                                  Septic arthritis



1.   Lateral joint line
Ž                             Fracture of tibial plateau

                                                                  Lateral compartment Osteoarthritis

                                                                  Lateral meniscal tear


2.   Lateral collateral ligament Ž              LCL tear or strain


3.   Lateral femoral condyle Ž                 ITB friction syndrome



      Popliteal pain and pressure is usually due to effusion and can be associated with any injury to structures within the synovial capsule.




1.   Patellar grind test (Clarke’s sign)

      Not always useful or necessary.  Can be falsely positive and is quite painful in patients with PFPS.


2.   Stress the collateral ligaments

      Apply valgus and varus stress to the knee at 30° flexion and at 0° flexion.  Look and feel for joint laxity and feel the character of end points.  Test can be falsely positive in the setting of osteoarthritis (or another cause of cartilage wear).


Grade 1 Strain = Tenderness at ligament with NO laxity at 30°

Grade 2 Strain = Minimal 30° laxity (NO 0° laxity).  Solid end-point. 

Grade 3 Strain = Significant 30° laxity (minimal to no 0° laxity).  Soft, mushy or no end-point.  Joint space opens > 1 cm.  Grade 3 = complete collateral ligament rupture.

Grade 4 Strain = Positive 0° laxity!  Must consider ACL and/or PCL tear.


3.   Stress the cruciate ligaments

      a.   ACL (least to most sensitive)

            1.   Anterior drawer test

?  Patient supine and relaxed.  Hamstring muscles relaxed.

?  Hips flexed, knees at 90°.                  

?  Examiner sits on patient’s feet with thumbs on tibial plateau.

2.   Lachman’s test

?  Patient supine (not watching) and relaxed (let the hips externally rotate).  Knee at 20° -30° flexion(can place over examiner’s knee).

?  Feel for increased laxity and soft, mushy end-point.  Changes can be subtle; asymmetric laxity >1 cm can be associated with complete ACL tear.

?  The Lachman’s test done on the sideline is often the most accurate due to the lack of  reflexive muscle spasm and hemarthrosis that occurs within hours after the injury.

            3.   Pivot shift test

?  Fully extend knee and internally rotate foot.

?  Flex knee while applying a valgus stress.

?  Watch & feel for clunk of tibia on femur.

?  More specific but difficult to perform when patient guarding.

The composite of all 3 tests is the most sensitive and specific for detecting ACL injury.  In one review: 74% sensitivity, 95% specificity. (Ref 1)


      B.  PCL

            1.   Posterior Drawer

?  Exactly like anterior drawer testing.              

            2.   Sag sign

?  In position for drawer testing, note the “sag” of the tibia posterior (watch for loss of the anterior skin-ridge associated with the tibial plateau!)

?  Sag corrects with extension of knee against resistance.



4.   Stress the Menisci

The medial meniscus is injured far more commonly than the lateral.  The lateral meniscus is attached only to the popliteus muscle and is more mobile than the medial meniscus, which is attached to both the capsule and the medial collateral ligament.  Recall “unhappy triad”.


      McMurray Test:

?  Patient supine and relaxed.

?  Pain may prohibit flexion of the knee.  If considering meniscal tear based on history and joint line tenderness, try internal/external rotation of extended knee first.

?  Start with knee fully flexed; stress applied during extension of the knee.

?  Hands are at the heel and joint line.  Evaluate for pain and palpable click.

?  Medial meniscus: Varus stress with internal rotation of foot.  RECALL that the toes and the knees point in different directions.

?  Lateral meniscus: Valgus stress with external rotation of the foot.

?  McMurray’s test can result in entrapment of posterior horn tears and result in palpable clunk.  While unable to entrap anterior horn tears (hence, no clunk), the test usually exacerbates joint line pain.

?  Classically, a palpable clunk at the joint line was considered positive.  Now, a reproduction of the patient’s pain during testing is also considered positive.  (Ref.  2)




Who needs an X-ray?

·         2 Decision Rules: Pittsburgh Knee Rule and Ottawa Knee Rule (more extensively validated)

·         In 3/2005, Dr Mark Ebell (AFP Editor) sited a 2001 study and said the Ottawa Knee Rule “should not be used in pediatric populations.”  (Ref. 3)  However, a 2003 multicenter study of the Ottawa rule in children concluded, “The Ottawa Knee Rules are valid in children and have the potential to decrease the use of radiography in children with knee injuries.” (Ref. 4)


      Pittsburgh Knee Rule

      Obtain radiograph if:

1.      Younger than 12yo or older than 50yo.

2.      Unable to take 4 steps in E.D./office.


      Ottawa Knee Rule

      Obtain radiograph if:

1.      Age 55 or older.

2.      Tenderness at fibula head.

3.      Isolated tenderness at patella.

4.      Inability to flex knee to 90 degrees.

5.      Inability to bear weight for 4 steps BOTH immediately and in office.


“The Ottawa knee rule is a valid tool to guide the use of x-rays for excluding fractures in people with acute knee injuries in an emergency department setting.”

Robb G, Reid D, Arroll B, et al. General Practitioner diagnosis and management of acute knee injuries: summary of an evidence-based guideline.  Journal of the New Zealand Medical Association 2007;120(1249)  (Ref 5)



Causes and Treatment of Knee Pain


A.  Osteoarthritis

?  3 Compartments in the knee.  Medial compartment is most susceptible to age-related degeneration

?  3 of 6 clinical characteristics:

1.   Greater the 50 years old

2.   Morning stiffness less than 30 min

3.   Crepitis

4.   Bony tenderness

5.   Bony enlargement

6.   No warmth

?  4 radiographic finding of OA:

1.   Asymmetrical joint space narrowing

2.   Bone sclerosis

3.   Osteophytes, “spurring”

4.   Subchondral cysts





?  Achy pain for weeks or months

?  Onset of symptoms may be precipitated by minor injury or usual use of joint

?  Increased pain after activity

?  Increased stiffness after rest (<30min in morning) 



?  Anterior/Posterior pain with decreased ROM suggests effusion. 

?  MTP at joint line. 

?  Positive crepitus and palpable spurring. 

?  Weight-bearing radiographs are positive for changes listed above.



?  Relative rest (weight loss, cane)

?  Moist heat

?  Activity modification (decreased weight bearing)

?  Muscle strengthening

?  Glucosamine sulfate

?  Tylenol / NSAIDs

?  Steroid or synvisc joint injection

?  Ice for flares

?  Quadricep strengthening


B. Bursitis

?  Pes Anserine bursitis is usually due to OA

?  Prepatellar bursitis is usually due to trauma, “housemaid’s knee”

?  Differential includes infection (Septic Bursitis) and Gout



?  Focal tenderness and swelling at bursa.  Otherwise, knee exam is normal.

?  Radiographs normal except for soft tissue swelling.

?  Completely extra-articular!



?  Aspirate! 

?  If crystals, treat underlying gout (can consider instilling steroid through needle). 

?  If infection, needs drainage and antibiotics. 

?  If clear (trauma), may consider steroid injection. 

?  Approximately 95% of cases (noninfectious) will resolve with patience, heat or ice, rest, and NSAIDs.


E. Synovitis

?  Synovitis is NOT a result of trauma, overuse injury, joint degeneration or structural injury.


Synovitis: Differential Diagnosis:

?  Infectious

?  Reactive arthritis (Reiter’s, IBD)

?  Rheumatoid arthritis

?  Vasculitis

?  Lupus

?  Crystalline arthritis



?  Joint pain, warmth, swelling, pain with weight-bearing

?  No trauma, activity change, etc.



?  Aspirate!  (see Table)

?  Joint tenderness, warmth, swelling, and erythema



?  Depends upon cause of synovitis.


C.  Septic Joint

?  Medical emergency

?  Gonococcal vs. non-gonococcal (which is usually Staph. aureus)


?  Joint pain, warmth, swelling, pain with weight-bearing



?  Aspirate!

?  Joint tenderness, warmth, swelling, and erythema

?  Swelling and tenderness extend beyond joint

?  Fever and high WBC’s may be present



?  Gonococcal: IV antibiotics

?  Non-gonococcal: Emergent surgical or open drainage, parenteral antibiotics


D.  Crystalline Arthropathy (Gout vs. Pseudogout)

?  Gout arthopathy is akin to bad fudge

?  Normal serum urate approximately 3 to 8

?  Acute attack can occur in anyone with urate >6 (So, some attacks occur in pt’s with normal urate!)

?  Most with hyperuricemia never have attack.  (So, high urate does not make a diagnosis of Gout.)

?  Acute flares are separated by asymptomatic intercritical periods.

?  Recurrence is the rule as is insidious joint destruction.

?  Tophi appear after 12 years on average.



?  Joint pain, warmth, swelling, pain with weight-bearing

?  Escalation of pain to maximum within hours

?  Acute attacks in single joint account for 80% of cases (Therefore, 20% of cases involve 2 or more joints—don’t get fooled.)




?  Aspirate!

?  Joint tenderness, warmth, swelling, and erythema

?  Swelling and tenderness extend beyond joint

?  Fever and high WBC’s may be present




?  Steroid injection

?  Colchicine

?  Allopurinol



F. Medial Collateral Ligament Strain or Tear

?  Often injured by valgus stress in dirt-biking and in football (“clipping”)

?  Recall, 1st degree strain has tenderness but no instability while 3rd degree strain (MCL rupture) has gross instability at 30° flexion.



?  Valgus stress to knee



?  Tenderness along MCL +/- instability



?  Rest

?  Ice

?  Protection with hinged brace

?  Physical Therapy


G. Lateral Collateral Ligament Strain

?  Less common than MCL injuries



?  Varus stress to knee

?  Usually occurs in setting of large trauma to knee (MVA, etc.)



?  Tenderness at LCL +/- instability



?  Surgical repair of severe LCL tears

?  Rest

?  Ice

?  Hinged brace

?  Physical Therapy


H. Anterior Cruciate Ligament Injury

?  Common in trauma, but 70% of ACL injuries are NONCONTACT

?  Usually a cutting, deceleration or hyper-extension movement

?  Hemarthosis yields rapid swelling (severe within 2 hours)

?  female:male ratio is 4-6:1 (Injuries increased dramatically after Title IX)



?  Often feel “pop” and immediate pain

?  Acute injury that stops play

?  Describes instability, laxity, “giving-out”



?  Effusion (about 70% of patients presenting with hemarthosis)

?  Anterior drawer sign

?  Lachman’s test

?  Pivot shift

?  SKIP THE MRI!  In one study, the overall accuracy of MRI for detecting ACL tear was 91% while the accuracy of clinical diagnosis was 90%!!!!    (Ref 6)



?  Surgical reconstruction recommended for adolescents and young adults.

?  Non-surgical “conservative” therapy often leads to meniscal injuries, unstable knee (“giving-out”) and accelerated osteoarthritis—particularly in patients active in jumping or cutting sports.

?  Elderly with sedentary, low-impact life-style may consider non-operative management (physical therapy, bracing)

?  Physical Therapy for proprioceptive training is well supported by evidence for both post-reconstruction and ACL-deficient knees.  (Ref 5)


NOTE: In a recent trial of conservative treatment of ACL ruptures, almost two thirds of those patients primarily treated conservatively eventually returned for operative reconstruction.  (Ref 7)


I. Posterior Cruciate Ligament Injury

?  Less commonly injured than ACL

?  Usually injured in the setting of a large trauma to knee with posterior blow to the tibia(consider concomitant injuries!).  Common settings: MVA (tibia hits dashboard), contact sports.

?  Less commonly occurs with forced hyperextension



?  Rarely feel tear or “pop”

?  Instead report vague discomfort and unsteadiness



?  Posterior drawer test is the most sensitive (90%) and specific (99%) for PCL injury (Ref 8)



?  Non-operative vs surgical reconstruction?  Clear indications for surgical reconstruction of PCL do not exist.(Ref 8)



J. Meniscal Tear

?  Menisci (2) cushion and stabilize the knee

?  Meniscal tear is the most common knee injury

?  Usually, injury is due to twisting on a planted foot

?  Nourished by synovial fluid, so free bodies remain viable.  But, tears often do not heal due to poor vascular supply.

?  Medial injuries are 10 times more common than lateral injuries because medial meniscus is less mobile (attached to MCL).



?  Often, no twisting injury is recalled (Getting out of car-- esp. in elderly)

?  May feel pop or tear

?  Pain at medial or lateral joint line

?  Effusion develops over hours (often reaches maximum on day 2)

?  May “lock”



?  Effusion

?  Tender joint line

?  McMurray test positive

?  Try treatment before MRI!  Overall accuracy of MRI for detecting meniscal tears was 68% for medial and 86% for lateral tears.  Accuracy of clinical exam was 64% for mensical tears.  (Ref 6)



?  One third to one half will “heal” to become asymptomatic without surgery

?  Meniscectomy may accelerate osteoarthritis

?  Rest: first no weight, then no twisting (consider crutches and then brace)

?  Ice

?  Crutches

?  MAYBE Physical Therapy (quadriceps strengthening).  BUT:

?  “Physiotherapy should not be routinely advocated following menisectomy.”  (Ref 5)

?  Swimming

?  Surgery if true locking or persistent pain


MRI: Before ordering a test, question whether the result of the test will change your management.  Greater than 1/3 of meniscal tears will become asymptomatic without intervention.  In addition, surgical repair of tears occurring in the setting of DJD does not significantly improve symptoms.  Finally, MRI is positive for meniscal tear in up to 1/3 of asymptomatic individuals! (Ref 9)


K. Iliotibial Band Friction Syndrome (ITBFS)

?  Overuse injury

?  Exclusive to athletes - usually runners



?  Complain of lateral knee pain that develops during runs



?  Tight ITB

?  Tender at lateral femoral condyle

?  Often have palpable (not audible) click or snap at ITB with knee flexion



?  Reduced mileage

?  ITB/tensor fascia lata stretching

?  Steroid injection

?  Ice, NSAIDs, Physical Therapy


NOTE:  A recent systematic review was attempted to assess interventions for ITBFS.  They found only 4 RCT’s on treatment: NSAIDs, deep friction massage, phonophoresis and corticosteroid injection.  They concluded that “there seems limited evidence to suggest that the conservative treatments that have been studied offer any significant benefit in the management of ITBFS.”  (Ref 10)


L. Patellofemoral Pain Syndrome (PFPS)

?  Anterior knee pain

?  Classically described in untrained females (high Q-angle) who are starting new activity (untrained VMO)

?  However, can occur in very trained athletes due to muscle imbalance


?  Only 20% of PFPS is associated with chondromalacia patella (the pathologic term for cartilage degeneration on the underside of the patellar facets)




?  Similar to OA, but PFPS is the most common cause of pain in individuals under 45 years old

?  Increased Q angle

?  Increased pain with activity

?  Increased stiffness with rest (cinema sign)



?  VMO atrophy

?  Positive J-sign

?  Tender superior-lateral pole of patella

?  Positive patellar grind test (if done)



?  Activity modification

?  VMO strengthening

?  Hamstring, quadricep and ITB stretching

?  Taping and bracing has unproven benefit (Ref 11)

?  Ice, NSAIDs

?  Orthotics

?  Surgery (smooth patella, release lateral retinaculum)

?  Self-limited?????


M. Tendonitis

?  Patellar Tendinitis (“Jumper’s Knee“) much more common than Quadricep Tendinitis

?  Weight lifters and jumping/sprinting athletes--pylometric (a.k.a. explosive) activities.



?  Pain with activity

?  Decreased knee extension

?  Stiffness with rest



?  Tenderness at tendon--usually at its insertion at the patella

?  Pain reproduced by resisted extension of the knee



?  Rest

?  Heat/Ice


?  Stretching

?  Rehab/strengthening of tendon

?  NEVER steroid injection


N. Medial Plica Syndrome

?  Plica are folds of the synovial membrane at the knee

?  Medial plica may become locally inflamed or irritated by trauma or overuse



·         Usually have vague complaints of medial joint pain with activity (but may report acute onset of surprisingly severe pain)



?  Locally tender at media plica (palpate a mobile nodularity noted at the anterior, medial joint space)

?  Tender at medial femoral condyle

?  Palpable snap at 50 – 70 degrees of knee flexion



?  Rest, Ice

?  Physical Therapy (patella mobilization, stretching)

?  Surgery very rarely


O.  Avascular Necrosis

?  Think of AN at the femoral head, humeral head, and talus.  But, AN can occur in many joints.

?  Idiopathic, or

?  Secondary to:  steroid use





?  Stiffness (particularly in morning), limping

?  Vague, poorly-localized pain

?  Gradual onset of pain and swelling

?  Recurrent effusion

?  > 50 yo



?  May be focally tender

?  Diagnosis made with X-ray radiograph



?  Rest and NSAIDs

?  < 50% require joint replacement


      Osteochondritis Dissecans  =      idiopathic avascular necrosis in young adults and                                                                  children (<50yo).  See history and exam above.



P.   Osgood-Schlatter Disease

?  Classified as osteochondritis or aseptic necrosis

?  History of  trauma vs. history of  pylometric activities

?  Occurs while upper tibial epiphyseal plate is open (ages 8-15)

?  Males : Females = 3:1



?  Pain increases with activity, stair climbing, squatting



?  Local tenderness

?  Swelling

?  X-ray usually normal; may see variable separation at physis



?  Rest

?  Stretching

?  NSAIDs, Ice after activity

?  “Cho-Pat” or patellar tendon brace?


Q.  Fractures of the Knee

?  Always secondary to trauma


1.   Tibial plateau (common)

?  Usually traumatic force to lateral knee such as a valgus stress



Displaced fractures require ORIF of depressed plateau fragment


2.   Patella

?  Direct trauma


Table:  Synovial Fluid Findings in Joint Disease

















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