Knee Range of Motion (Knee ROM)

Knee Range of Motion (Knee ROM) should include assessment of knee flexion and extension, tibial internal and external rotation.

Normal knee ROM has been described as 0 degrees of extension to 140 degrees of flexion, although hyperextension is frequently present to varying degrees.

The best way to ascertain normal Knee ROM is to examine the contralateral knee, provided that it has no abnormal conditions. The Knee ROM testing can often be diagnostic and provides the clinician with some clues as to the cause of the problem.

Examining the uninvolved knee first allays a patient’s fears and helps to determine what the normal ROM is. In addition, observation of the uninvolved knee can afford the clinician information about the patellofemoral joint and the tracking of the patella.

Full active range of knee motion requires the following:

1. Congruent articular surfaces
2. Adequate muscle function
3. An articular capsule with suitable capacity and flexibility
4. Effective space in the medial and lateral articular recesses, intercondylar notch, and suprapatellar pouch
5. Sufficient meniscal motion

Motion	Knee Range of Motion (degrees)	End-Feel
Flexion	0-140	Tissue approximation or tissue stretch
Extension	0-15	Tissue stretch
External rotation of tibia on femur	30-40	Tissue stretch
Internal rotation of tibia on femur	20-30	Tissue stretch

See Also: Knee Meniscus Tear

How to test for Knee Range of Motion?

Knee Flexion:

The amount of knee flexion should be assessed to see if the motion is restricted by tight structures. If no restriction is suspected, tests are required for generalized ligament laxity and for abnormally loose patellar retinacula.

The primary flexors of the knee are the:

1. Three hamstring muscles,
2. The gracilis, sartorius, popliteus, and gastrocnemius muscles: assist in knee flexion.
3. The tensor fascia latae (TFL): in 45–145 degrees of flexion.

• Knee flexion ROM is done with the patient lies in the supine position.
• Using one hand, the clinician grasps the anterior aspect of the patient’s lower leg, just proximal to the malleoli, while the other hand grasps the anterior aspect of the patient’s thigh, just above the patella.
• The patient’s hip is flexed to about 90 degrees and stabilized with one hand, while the clinician flexes the knee with the other hand.
• At the end of the ROM, the clinician exerts slight overpressure.

The normal end-feel is usually one of soft tissue approximation.

A flexion limitation other than soft tissue approximation is usually the result of:

1. an articular lesion, such as arthritis or arthrosis (capsular pattern),
2. a lesion of one of the menisci,
3. a loose body.

Rotation of the tibia relative to the femur is possible when the knee is flexed and non–weight-bearing, with rotational capability greatest at approximately 90 degrees of flexion.

Knee Extension:

The primary extensors of the knee are:

• the quadriceps muscles consisting of: the rectus femoris, Vastus Lateralis, vastus medialis, and vastus intermedius.
• The Ilio-Tibial Band and tensor fascia latae (TFL): Also assisting with knee extension in the 0–30-degree flexion range.

The patient extends the knee, and the clinician applies overpressure by stabilizing the thigh and pulling the ankle up to the ceiling, while allowing the conjunct external rotation of the tibia.

Under normal conditions, the end-feel is usually hard.

A limitation of active knee motion can have a number of causes:

1. The patient may have a neurologic deficit from a lumbar intervertebral disk (IVD) herniation, with loss of knee motion as the primary symptom.
2. Any acute injury causing pain may limit active knee motion as a result of muscle inhibition.

Knee Passive Range of Motion:

Passive movements can determine the amount of available motion, the presence or absence of a capsular pattern, and the end-feel.

At the tibiofemoral joint, the end-feel of flexion should be tissue approximation, whereas the end-feel of extension and medial and lateral rotation of the tibia on the femur is tissue stretch.

Passive hyperextension of the knee with overpressure is performed to assess (from the end-feel) whether the knee extension is limited as a result of an articular disorder. Such articular disorders include arthritis or arthrosis, a lesion of one of the menisci, or a loose-body involvement.

According to the osteopathic theories of somatic dysfunction, the following guidelines are used:

1. If the restriction to movement is opposite to the direction that the bone seems to have traveled (e.g., the tibia has a reduced joint glide), a mobilization or a manipulation is the intervention of choice.
2. If the restriction to movement is in the same direction that the bone seems to have moved and the opposite movement seems to be excessive (a change has occurred in the overall starting position), a muscle imbalance should be suspected, and a muscle energy technique used.
3. If the patient demonstrates normal range but pain with movement, the joint cannot be at fault.
4. If a muscle is very hypertonic, a spinal dysfunction may be present (unless trauma is involved), producing a hypermobility.

Loss of Flexion / Extension:

Even minor losses of knee motion may have adverse effects. It is common to lose both flexion and extension; however, loss of extension is usually more debilitating.

A loss of extension of more than 5 degrees may cause patellofemoral pain and a limp during walking, whereas restricted flexion does not severely affect gait as long as the knee can be flexed to at least 60 degrees.

Diminished running speed is associated with loss of flexion of 10 degrees or more, whereas an extension deficit of more than 10 degrees is poorly tolerated by active people. A loss of more than 20 degrees of extension may cause a significant functional limb-length discrepancy.

Patellar Motion Tests

Probably the most important part of the patellofemoral examination is the observation of the dynamics of patellar tracking in weight-bearing and non–weight-bearing.

A unilateral squat (Waldron test) can be used to assess patellofemoral function:

• The patient stands on the involved leg, and the clinician sits or squats next to the patient.
• Using the entire surface of the palm, the clinician exerts slight pressure in an anteroposterior direction against the patient’s patella.
• From this position, the patient is asked to bend the knee slowly, if possible, to about 90 degrees, while the
  clinician palpates for crepitus and locking of the patella and assesses the course of movement of the patella.
• Crepitus or locking can indicate the presence of patellofemoral chondropathy or patellofemoral arthrosis.

In patellar malalignment or pathologies of the corresponding femoral joint surface, movement of the patella can be disturbed.

The patella is observed while the patient initiates flexion of the knee to see if it engages smoothly at the proximal end of the trochlea or more distally than normal.

Lateralization of the patella can occur during flexion, particularly when the Q-angle is excessive.

Tibiofemoral Distraction

The patient lies in the prone position. The clinician is beside the patient. Using one hand to stabilize the thigh, the clinician uses the other hand to grip the distal tibia from the medial and lateral sides. The clinician then applies a force perpendicular to the tibial joint surface.

Proximal Tibiofibular Joint

The proximal tibiofibular joint can be assessed with the patient in the supine position and the knee flexed to approximately 90 degrees. The clinician stabilizes the tibia using one hand and uses the other hand to grasp the fibular head and to assess the anterolateral and posteromedial glides.

Passive Tibial External Rotation

The patient lies in the supine position. Using one hand, the clinician grasps the patient’s foot and brings the ankle into
maximal plantar flexion. The other hand is positioned to monitor the joint space. The patient’s knee is flexed to 90 degrees and the hip to approximately 45 degrees. The distal hand performs an external rotation of the tibia while maintaining the ankle in maximum plantar flexion.

At the end of the ROM, the clinician exerts slight overpressure. Under normal conditions, the end-feel is firm. The clinician notes whether the pain is provoked or whether there is a hypermobility or hypomobility:

1. Pain with passive external rotation of the tibia can be the result of a lesion of the medial meniscotibial ligament,
   medial meniscus, MCL, or the posteromedial capsuloligamentous complex.
2. Hypermobility with this maneuver can be the result of a lesion of the posteromedial capsuloligamentous complex,
   often in combination with lesions of the MCL and the ACL. Hypermobility may also be seen in ballet dancers.
3. Hypomobility of passive tibial external rotation is seen only in severe articular disorders with significant capsular
   limitations of motion.

Passive Tibial Internal Rotation

The patient lies in the supine position. Using one hand, the clinician grasps the patient’s foot and brings the ankle into maximal plantar flexion. The other hand is positioned to monitor the joint space. The patient’s knee is flexed to 90 degrees and the hip to about 45 degrees. The distal hand performs an internal rotation of the tibia while maintaining the ankle in maximum plantar flexion.

At the end of the ROM, the clinician exerts slight overpressure. Under normal conditions, the end-feel is firm. The clinician notes whether pain is provoked or whether there is hypermobility or hypomobility:

1. Pain can be the result of a lesion of the lateral meniscotibial ligament, lateral meniscus or posterolateral capsuloligamentous complex.
2. Hypermobility can be the result of a lesion of the posterolateral capsuloligamentous complex.
3. Hypomobility is seen only in severe articular disorders with significant capsular limitations of motion.

Patellofemoral Joint Mobility Tests

The patient lies in the supine position with the involved knee supported in slight flexion. The clinician moves the patella superiorly, inferiorly, medially, and laterally.

Caution must be used with the lateral glide in case the joint is hypermobile, as this is the most common direction for patella dislocations.

To assess the various tilts of the patella, both hands are wrapped around the patella and the thumbs are used to tilt the patella medially and laterally. The findings are compared with the contralateral side.

Knee ROM Test Accuracy

A number of studies have demonstrated that goniometric measurements of knee ROM performed in a clinical setting can be highly reliable.

Rothstein et al. showed that intratester and intratester reliability for flexion of the knee was high (r = 0.91–0.99 and r = 0.88–0.97, respectively).

Watkins et al. showed that the intertester reliability for measurements of knee ROM obtained by visual estimation was 0.83 for flexion and 0.82 for extension.

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