Examination of the Knee for Common Sports Medicine Injuries

Gary Podolsky MD

Goals :

To present a systematic approach to examining the knee and adjacent areas.

Discuss and demonstrate specific examination techniques used in Sports medicine for specific musculoskeletal injuries.

Introduction

The knees are integral joints for locomotion and are subject to much stress in activities of daily living, occupation, and sport.

Arthritis may occur idiopathically in some individuals with no history of traumal.

Goals for treatment for all those afflicted with knee injuries are to maintain function, alleviate pain, and allow them to have a productive lifestyle and continue with their pursuit of sport.

Sports medicine recognizes that many of the same principles that are used to rehabilitate knee injuries may also be applied to athletes preparticipatory to strengthen their knees and prevent future knee injuries (prehabilitation).

Keeping athletes with early knee injuries physically active will strengthen muscles and ligaments and prevent osteoporosis all of which will prevent further injury.

This is recognized for all populations of athletes- from the very young to the very old.

Elderly patients with arthritis are encouraged to remain active as this has a positive effect on the arthritis knee. Functional proprioception and strong knee ligaments will protect the knee and prevent worsening of arthritic disability.

Examination of The Knee

Evaluation of the knee starts with inspection, palpation, and documenting range of motions. Specialized tests for cartilage and ligament injuries are used for specific conditions

Inspection of the Knee

Comparison with the opposite limb will help identify variations of normal form from pathology.

For example some individuals may have prominent tibila plateaus that could be confused with Osgood Schlatter disease in others.

Assessing the quadracept bulk is useful as atrophy of the medial portion- vastus medialis oblique gives evidence that a knee injury has been chronic enough to cause disuse atrophy. Clinicians may wish to quantitate this with circumferential measurements of muscle girth or with a functional review by having the patient perform a squat maneuver.

Effusion may be observed in the patellar compartments or be formally palpated later on. If severe an effusion may restrict the full extension of the knee and the patient with have a slightly flexed knee. The joint space has a larger capacitance for an effusion in in this flexed position.

Before moving to the remainder of the knee examination it is important to not exclude other injuries. It is important to always consider the joints above and below an injury, which in this case include the back and hip; and the thigh and ankle. Coexistant injuries may exist or other areas may serve as the true source of pathology with radiation of pain to the knee. This is more confusing in patients with multiple aches that are poorly localized. These patients should have all related systems examined on the initial visit in a systematic fashion so as not to be 'led down the garden path' to an incorrect premature diagnosis.

Hip Pathology

Hip pain may be referred into the knee because of the cross over of the L3 dermatome. Documenting pain free range of movement of the hip is useful in ruling out referred pain. X-rays may be necessary to rule out fractures or intrarticular lesions if clinical suspicion warrants this.

Discogenic Back Pain Radiating Into the Knee

Discogenic back pain despite being a distinct clinical entity from knee pain sometimes will still be confused with knee pathology. Normal range of movement and tests for dural tension should be adequate to exclude this.

Figure 10 Straight leg raising for discogenic back ain

Palpation of the Knee

Physical palpation may guided by the mechanism of injury as reported by the athlete. Often a patient may have had only incidental trauma, be unable to remember how they were hurt, or present months to years after their original insult so a reliable history may not be available. Systematically evaluating the important stabilizing structures ensures that no pathology is missed.

Patella

The kneecap may be first gently palpated. Anterior posterior pressure will give generalized tenderness to many conditions as the bursae of the knee are compressed.

Lateral squeezing the patella will be more specific for boney tenderness.

Palpation while the knee is flexed will give the examiner the sensation of crepitus found in patellofemeral maltracking.

Clark's test involves the patient contracting their quadracepts while the examiner pushes down on the superior patella. Pain is found in patellofemeral problems.

Pain when the patient is kept sitting with the knee at 90 degrees "the theatre sign" is also suggestive for patellofemeral pain.

Medial Joint Line

The medial meniscus may be directly palpated. Meniscus cysts and plica may also be felt.

The medial collateral ligament is a broad ligament and easily felt. Varus stress of the knee joint will identify medial collateral tears.

Figure 11 Palpating the medial joint line

The insertion of the pes anserine is felt more distally and when inflamed this bursae will become tender.

Figure 12 Pes anserine bursitis

Lateral Joint Line

The lateral joint line may be easier palpated with the knee in internal rotation.

Figure 13 Palpating lateral joint line. This also may be done with the hip internally rotated

More proximally the tensor fascia latae may also be palpated

Anterior Structures

The Anterior tibial spine is easily palpated and will be tender in Osgood Schlatter disease.

Figure 14 Anterior Tibial spine

Posterior Structures

Palpating the posterior fossa, examiners may feel bake's cysts and inflamed tendons of the semimembranosis and semitendinosis. Popliteal aneurisms although rare if suspected should be referred for ultrasound studies.

Other Causes of Pain Around Knee

Acute lower leg pathology sometimes presents to sports medicine clinics and although not a part of the knee is often declared by some patients as a problem with their knee.

Large tears of the gastrocnemius and achilles tendon may be felt as a gap initially but later as blood and fibrin reorganize in the tear this may not be felt.

Achilles tendon rupture must be diagnosed and referred quickly.

Observation with the patient prone, of the normal ankle will show a slight dorsiflexion due to the resting tone of the intact achilles tendon. When this is ruptured the ankle will become more dorsiflexed.

The Thomas test demonstrates an intact achilles mechanism as grasping the gastrocnemius muscle will make the ankle plantar flex.

Figure 15 Normal tone of Achilles endon compared with simulated ruptured Achilles tendon

Figure 16 Thomas test Normal plantar flexion responce to compression of gastrocnemius

Deep Vein Thrombosis

This injury is also frequently referred to sports medicine clinics and is also more common in postoperative orthopedic clinics. It should be suspected until ruled out. High risk individuals include smokers, oral birth control use, malignancy, and history of recent prolonged air travel (even up to 3 weeks later). Even low risk individuals must be carefully scrutinized for this condition

The classical description for deep vein thrombosis- pain, redness, and a positive Homan's Sign may be missing. If another condition can not plausibly explain deep thigh pain definitive studies such as venograom or ultrasound must be performed.  A careful examination may support alternate diagnosese such as superficial phlebitis, mild muscle tears but this should be used only when the history supports this. Because of the high degree of uncertainty formal tests are recommended.

Homan's sign involves the forced plantar flexion of the ankle and may be positive for pain. The classical description for deep vein thrombosis- pain, redness, and a positive Homan's sign are inconsistently found and cannot be solely relied on.

Figure 17 Homan's test for Deep Vein Thrombosis

Range of Movement of the Knee

Documenting flexion and Extension in the injured and opposite knee is helpful.

Figure 18 Knee extension and Flexion

Special Tests for Examining the Knee

McMurray Test

This test for meniscus pathology involves externally rotating the hip, flexion of the knee and knee extension with the examiner's hand at the medial joint line.

Palpation of the joint line will allow the examiner to feel a sometimes audible clunk. Pain alone with this maneuver is suspicious for meniscus pathology but this is less specific.

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Figure 19 Mcmurray Test Demonstration

A knee that is 'locked' (where a 'bucket handle' shaped portion of the torn meniscus has become jammed in the joint, may become unlocked by a careful and gentle McMurrays Maneuvre. The joint should never be forced especially into extension as this may further tear the meniscus.

Reverse McMurray's Test

A reversed McMurray's test that flexes, internally rotates the knee with pressure on the lateral joint line during extension will similarly detect lateral meniscus pathology.

Figure 20 Apley's Grind and Distraction tests ( hands placement for exaggerated emphasis of direction of force)

Anterior Drawer Test

This is used to detect Anterior Cruciate Ligament injury.

The patient is supine with knee flexed to 90 degrees and the tibia is grasped with observation of foreward translation of the tibia.

In acute injuries there may be significant pain and spasm so it is best to perform this test carefully the first time as subsequent tests will be les accurate. Compare the laxity with the opposite knee. Many young women have normally lax ligaments and this should be differentiated from pathology.

Figure 21 Anterior Drawer test

Lachman Test

The patient is supine. The examiner grasps the distal femur with one hand and proximal tibia with another and knee is flexed to 15-20 degrees. Anterior force is applied to proximal tibia. A positive  test shows anterior translation of the tibia.

Figure 22 Lachman's Test (Right hand on distal femur not seen)

Posterior Drawer Test

The examiner pushes the knee posteriorly to challenge the posterior ligaments.

Figure 23 Posterior drawer test

A knee with a posterior lag (where the PCL is torn and the tibia is sitting in a depressed fashion) may appear to have a positive Anterior drawer sign when it is really a positive Posterior drawer test but the reference from the start of the test is wrongly assumed to be normal.

Pivot Shift Test

This is used for demonstrating ACL deficiency.

Patient is supine and knee is examined in full extension. Tibia is internally rotated with one hand of examiner grasping the foot and the other applying valgus (abduction) stress at the knee joint. With flexion of the knee at 30 degrees a jerk is placed at the anterolareal corner of the proximal tibia. A positive test is when a shift occurs as the lateral tibia condyle will sublux laterally.

Valgus and Varus Challenge

Strain is applied to forleg to stress the MCL and LCL respectively. Laxity of joint is noted.

Ober's Test

Patient is in decubitus position with injured side up. The examiner will take leg that is flexed and abduct. Examiner releases leg. In instances of tight iliotibial band there will be a resistance to normal falling. (This is exaggerated in Fig 15.)

Figure 24 Ober's test for Iliotibial Band a.set up before release b. positive. c negative (normal) for iliotibial band tightness

In Summary

When presented with an acute knee injury the examiner must make some quick decisions.

History may not be complete but if detailed this can guide the physical examination. Specialized examination techniques are very useful in confirming specific soft tissue injuries.

An accurate diagnosis is not absolutely necessary but severe injuries that have to be recognized and treated early should be sought (fractures, instability to the knee, as well as unrelated problems such as deep vein thromboses).

Regardless of the definitive diagnosis clinicians must begin to put together a treatment plan for the injured athlete.

Early use of PRICE (Protection, Rest, Ice, Compression and Elevation) is essential.

Even with out a specific diagnosis if a patient is in severe pain Crutches, Splinting or Bracing may be considered.

Early referral to orthopedic surgery should be initiated early especially given the long waiting times to see such specialists. The need for physiotherapy and early start of rehabilitation should also be started.

When a diagnosis is unclear, repeat examination may also help

Appendix:

Crutches

Measuring crutches for proper fit:

The height of the crutches should be up to 3 fingerwidths below the axilla when patient is standing straight. The wrist grasp should be set so that the elbow is about 15-20 degrees of flexion

References

Hoppenfield S Physical Examination of the Spine and Extremities, Norwalk, Appleton-Century-Crofts, 1976

Photographs Skylark Medical Studio 264 Tache Winnipeg MB ã .2005

Sports Medicine Secrets Morris B Mellion Philadelphia Mosey 1994 s

The Knee: Normal Anatomy and Function Jason Taito and Michael Yergler ACSM Team Physician Course 2001

Examination of the Knee Mary Ireland ACSM Team Physician Course San Diego Feb 8,2001.