chapter 3: History and Physical Examination
Reproducing the Patient's Pain
Soft‑Tissue Palpation. Systematic palpation of peripatellar soft tissues should focus on soft‑tissue static restraints and the tendinous insertions of each portion of the quadriceps muscle. Place the soft‑tissue structures under tension before palpation. This will help to limit the pressure transmitted to underlying structures and help the examiner to know that the painful structure is most likely the one under tension. (Fig. 3.9). Palpate the medial and lateral retinacular tissues, the medial femoral condyle in the region of the medial parapatellar plica, each of the quadriceps tendon insertions and the patellar tendon in each patient. Palpate deep to the patellar tendon for evidence of increased density and/or reproduction of the patient's pain. Palpation of the quadriceps muscle bellies can occasionally reveal tenderness. Palpate all scars for neuromata, especially if the history suggests this diagnosis. Reproducing symptoms by palpation of the adductor hiatus suggests saphenous nerve entrapment. In patients with suspected acute lateral dislocation, palpate the adductor tubercle for tenderness at the origin of the medial patellofemoral ligament. Medial and lateral joint lines should also be examined for tenderness, which may suggest meniscal problems or tibiofemoral arthrosis.
Remember that a primary goal of examination is to reproduce and localize the patient's pain. Innervated tissues of the patellofemoral joint, which could generate anterior knee pain, include the subchondral bone of the patella and trochlea, synovium (including plicae), patellar and quadriceps tendons, and retinacular soft‑tissue restraints medially and laterally. Tenderness is very common in the medial and lateral patellar retinacula and the patellar tendon, all of which rank high among the most densely innervated soft tissues in the knee (46). Tenderness is common in the peripatellar tissues that are overly tight and have been chronically overloaded. This tenderness may result from the neuromatous degeneration found in such retinacular tissues excised at the time of lateral release (47, 48).
Precise diagnoses in acute injuries and chronic pain are often made by careful mental visualization of the specific structures that are most tender. Particular attention should be paid to the medial femoral condyle area where the medial parapatellar plica can often be readily palpated. Tenderness as the plica is rolled underneath a finger is diagnostic of medial plica irritation and medial plica syndrome. Patients with soft‑tissue pain secondary to excessive lateral patellar tilt commonly have tenderness in the vastus lateralis insertion, the lateral retinacular insertion and the inferior portion of the medial retinaculum just above the patellar tendon origin. Quadriceps muscle belly tenderness occurs in severe overuse syndromes and more unusual situations such as peripatellar hemangioma. Patellar tendon tenderness diagnoses patellar tendinitis/tendinosis.
Postsurgical neuroma is a physical examination diagnosis. Discovery of hypersensitive scar, which reproduces patient complaints, is not rare and should be sought in patients with previous surgery. Characteristic patterns of numbness or hypesthesia are often present in patients with symptomatic neuromata or nerve entrapment (Fig. 3.10). Postsurgical, post‑traumatic or idiopathic saphenous nerve entrapment near the adductor canal is an unusual cause of anterior knee pain. If palpation over the adductor canal replicates the patient's complaint, injection of local anesthetic can confirm the diagnosis. Effective treatment by decompression or neurectomy is possible, but only if persistent palpation leads to the correct diagnosis (49‑51).
In acutely injured knees, palpation of the medial parapatellar structures helps differentiate acute lateral patellar instability and medial collateral ligament sprain. Sallay et al reported seventy percent of their patients were maximally tender over the adductor tubercle after acute lateral dislocation (37). Acute evaluation of possible extensor injuries must also include palpation for defects in the quadriceps and patellar tendons.
Supine Articular Examination. Evaluate the knee joint for effusion by milking the suprapatellar pouch with one hand and checking to see if the patella is ballotable with the other. Compress the patella directly into the trochlea with your thenar eminence (Fig. 3.11a - b, c ). Be careful to not touch any peripatellar tissues during compression. Compress the patella at various angles of flexion from full extension to full flexion. Beware of patients who have prepatellar bursitis that may cause pain with this test. Hold your hand over each patella during active and passive knee flexion observing for crepitus and pain. Note carefully which knee flexion angles are associated with pain or crepitus.
Effusion signifies serious intra‑articular pathology. A full discussion of the possible causes of knee effusion is beyond the scope of this chapter but causes include meniscal, ligamentous, degenerative and inflammatory pathology. In patients with patellofemoral pathology, effusion suggests moderate to severe patellofemoral arthrosis, osteochondral or chondral loose bodies, or severe plical inflammation. Joint effusion causes reflex quadriceps inhibition. As little as 15 cc of fluid injected into normal knees has been shown to produce marked reflex inhibition (1‑4). The threshold for VMO inhibition is approximately 20 to 30 cc of intra‑articular fluid compared to the 50 to 60 cc required to inhibit the rectus femoris and the vastus lateralis (3). Thus, asymmetrical inhibition may result in some dynamic malalignment even with a small joint effusion. This might help explain the patellofemoral pain so common during rehabilitation after many types of knee surgery.
Compression of the patella into the trochlea often produces pain when significant articular lesions exist on the portion of the patella or trochlea being compressed. The pain produced from articular compression must originate from irritation of the subchondral bone because articular cartilage is devoid of nerve endings. By meticulously avoiding the peripatellar tissues when compressing the patella, one can be certain that any pain produced originates from bony pathology. If the anterior knee appears very swollen, but the patella is not ballotable, suspect that prepatellar bursal swelling is present. When present, such bursitis is generally self‑evident and not easily confused with intra‑articular effusion by experienced examiners.
Worthwhile palpation of "facet tenderness" through the medial retinaculum (52) seems anatomically dubious given the interposition of the densely innervated retinaculum and synovium. Because the patella is not drawn into the trochlea until approximately 10 degrees of flexion, pain on compression of the patella with the knee in full extension is not truly evidence of articular pain. Because the distal patella first contacts the proximal trochlea, compression in early flexion suggests distal patellar pathology. As flexion proceeds the articular surfaces compressed become progressively proximal on the patella and distal in the trochlea.
Although crepitus suggests the possibility of significant articular changes, crepitus is very common in asymptomatic knees and is a more serious discovery when absent or asymmetric in the contralateral knee. Pain with patellar compression when the knee is moving is not an accurate test for articular pain because peripatellar soft tissues stretch as the knee is moving and can contribute to pain during motion. Occasionally, a discrete catch can be produced on examination reproducing the symptom that the patient recognizes as their primary complaint. This is important diagnostically and can correspond to a traumatic chondral flap or a pathologic hypertrophic plica.
McCoy et al quantified crepitus by measuring joint sounds detected by vibration arthrography and found that these correlate with specific intra‑articular pathology (53). Jiang et al also found the degree of patellar crepitus measured by vibration arthrometry correlated well with operative findings of patellar arthrosis (54). Neely and coworkers used laser optic technology to document the "sticking and slipping of the patella" and resultant micro‑vibrations (20‑180 microns) of physiological patellofemoral crepitus in normal knees (55). Although vibration arthrography and related technologies are still research tools, they have potential to quantify crepitus and related "joint noise" in a way that may eventually be clinically useful (56). Because crepitus is frequently found in normal knees, remember that it is clinically important only when it is asymmetric or reproduces symptoms.SUPINE EXAMINATION FOR FLEXIBILITY
Lift each leg independently and measure the popliteal angle as a measure of hamstring tightness (Fig. 3.12). This is also essentially a straight leg raising test and serves as a screening test for lumbar radiculopathy. Measure gastrocsoleus flexibility by ankle dorsiflexion with the knee extended and with the knee flexed 90 degrees (Fig. 3.13). Evaluate hip flexion contracture by flexing the contralateral hip completely and checking to be sure that the ipsilateral thigh can remain flat on the exam table (Fig. 3.14). If the ipsilateral hip cannot lie flat on table, hip flexion contracture is present.
Patellofemoral pain is often associated with flexibility deficits in the lower extremity. Muscle affects patellar alignment actively through contraction and statically through muscular compliance or flexibility. The static effects of antagonist muscles are important because they represent a portion of the force that must be overcome to complete agonist activity. For example, hamstring tightness causes a relative knee flexion contracture that increases the quadriceps force required to extend the knee. Because more quadriceps force is necessary, patellofemoral joint reaction force is also increased. Although "normal" values for hamstring flexibility are unavailable, most young athletic individuals have popliteal angles in the 160‑ to 180‑degree range. As always, contralateral examination is helpful.
Hip flexion contracture results in increased knee flexion through stance. As an extreme example, consider the crouched gait of patients with spastic diplegia and hip flexion contractures. In the presence of increased hip flexion during stance, the knee is flexed more to keep the foot underneath the center of gravity. Increased knee flexion results in increased patellofemoral joint reaction force.
Tightness of the gastrocsoleus complex limits ankle dorsiflexion. Because the gastrocnemius muscles cross the knee joint, evaluation of dorsiflexion with the knee extended is necessary. Clinically, ankle dorsiflexion is more often limited with the knee extended. If dorsiflexion is limited, the subtalar joint compensates by increased pronation. Increased subtalar pronation causes increased tibial internal rotation, which, as previously discussed, has detrimental effects on patellofemoral mechanics.
Prone Quadriceps Flexibility. With the patient prone, flex each knee with one hand while stabilizing the pelvis (Fig. 3.15). Bring the heel as close as possible to the buttock. Record the distance from the heel to the buttock and any side to side asymmetry. If the patient has discomfort during this test, ask whether the pain is in the knee or thigh.
Treating quadriceps inflexibility is a critical part of restoring efficient extensor function. When flexibility is lacking, a muscle is less able to absorb energy eccentrically. Because the energy must be absorbed somewhere in the extremity, overload elsewhere becomes a possibility. Clinically, it seems that the sites most often subject to secondary overload are the patellar and quadriceps tendons. Active knee flexion also must overcome greater resistance when the quadriceps is relatively tight. Again, joint reaction forces may be increased. Patients with patellar tendinitis and "failed" postoperative patellar pain patients often have large quadriceps flexibility deficits that become obvious when measuring prone knee flexion.
Prone measurement is important because the rectus femoris crosses the hip and the prone position keeps the hip extended. When this test is performed, stabilize the pelvis to prevent compensatory hip flexion that patients attempt in order to allow their heel closer to their buttock. Patients also try to abduct their hip to shorten the distance from the patella to the rectus origin at the anterior inferior iliac spine. A convenient method of measuring the heel to buttock distance is by fingerbreadths of the examiner's hand. Although somewhat inexact, this allows adequate data to assess relative improvements between patient visits. Many young active patients can bring their heels to their buttock or at least within a few fingerbreadths. It is not rare to find patients with prone flexion limited to 110 degrees or less. When the heel comes less than eight fingerbreadths from the buttock, it is more convenient to record quadriceps flexibility as degrees of prone knee flexion.
Prone Hip Rotation. Because the patient is prone for evaluation of quadriceps flexibility, it is a convenient time to assess femoral anteversion. With the knee flexed 90 degrees, rotate the leg internally until the greater trochanter is maximally prominent laterally. At this degree of rotation the femoral neck is parallel to the table and the angle between the vertical and the tibia is the angle of hip anteversion (Fig. 3.16). After noting the anteversion angle, screen for limitations in hip motion by looking at entire range of internal and external rotation bilaterally.
Why to Do It. Examination of anteversion is important to understand its potential influence on patellar mechanics in each patient. Physical examination, as described, is as sensitive as radiographic measurement for femoral anteversion (57). Although femoral anteversion is the most variable component of femoral anatomy (58), normal values are well established. Anteversion is greatest in childhood and decreases during skeletal maturation (59, 60). According to Kingsley and Olmstead who studied 630 cadaver femurs, anteversion averaged 8.02 degrees. Sixty‑six percent of cadavers had anteversion angles between 0 to 15 degrees. Large variations occur between subjects, and side to side differences of 13 to 15 degrees occur in normal subjects (61, 62).
Although increased anteversion has been classically associated with patellofemoral pain and instability, no studies prove an association. Excessive anteversion causes relative internal rotation of the femur during gait. As discussed in the section on hindfoot pronation, internal rotation moves the trochlea medial and the lateral trochlea anterior. Because the quadriceps origin on the pelvis does not rotate internally, the Q angle increases. Careful evaluation of the range of motion is also an important screening tool for hip pathology, especially in the child or adolescent whose complaints of anterior knee pain occasionally represent referred pain from Perthes' disease or other hip pathology. Adults may also present with referred anterior knee pain, most commonly from osteoarthrosis of the hip. Prone hip rotation will usually be limited and painful in such patients.
ILIOTIBIAL BAND FLEXIBILITY
Ober's Test (Fig. 3.17AB, CD, EF). To evaluate iliotibial band flexibility, have patient lie on their side. For examination of the right leg stand behind the patient who lies with their left hip down and fully flexed to eliminate lumbar lordosis and stabilize the pelvis. Flex the right knee and hip 90 degrees each. Then abduct the hip and extend it to neutral.
If the hip cannot extend to neutral consider the possibility of hip flexion contracture. Do not allow the pelvis to rotate externally during this maneuver. During positioning of the tested hip into full extension, stabilize the pelvis with your left hand to maintain neutral femoral rotation. Once the upper leg is maximally abducted and extended, allow it to drop (adduct) by gravity while gently maintaining the knee flexion and femoral rotation. This position places the ITB on stretch and flexibility is assessed by observing how much adduction is possible. Comparison to the asymptomatic side is important, but generally the thigh should adduct to a position at least parallel to the exam table. Palpation of the ITB just lateral to the patella during maximal stretch usually reproduces pain in patients with excessive ITB / lateral retinacular tightness.
Excessive tension in the ITB can result in malalignment and also in soft‑tissue pain. The importance of the ITB inpatients with lateral retinacular tightness cannot be overemphasized. Melchione and Sullivan showed excellent intratester and good intertester reliability of Ober's test in patients with anterior knee pain using a fluid filled inclinometer to quantify thigh adduction (63). Iliotibial band inflexibility as documented by Ober's test was correlated with lateral knee pain and anterior hip pain in ballet dancers (64). Although Ober initially described this test as part of an investigation into low back pain (65), tightness is very common in patients with patellofemoral pain. The iliotibial band links the pelvis and the tibia. When ipsilateral hip abductor weakness allows the contralateral ilium to drop during weightbearing, tension is also increased in the ITB. When examining the ITB, remember that hip pathology, including hip abductor weakness, flexion contracture and rotational limitations can affect patellofemoral forces. Such problems, if detected should be addressed in the rehabilitation plan.
EVALUATION OF SYSTEMIC HYPERMOBILITY
Screen for knee and elbow hyperextension greater than 10 degrees. If fifth finger metacarpophalangeal hyperextension and thumb‑forearm apposition are also present, the patient fits criteria for hypermobility as described by Beighton and Horan (66).
Rünow showed that patellar dislocation was six times more frequent in hypermobile patients compared with age‑matched controls (67). Both Rünow and Stanitski (68) found that hypermobile patients are less than half as likely to sustain articular injury during patellar dislocation. Stanitski also found that none of his hypermobile patellar dislocation patients suffered medial patellar avulsions compared with one third of patients without hypermobility. Because the pathoanatomy of patellar instability is different in patients with hypermobility, screening examination is important. Ehlers‑Danlos or Marfan syndromes should be suspected in patients with marked hypermobility and appropriate referrals considered when serious systemic manifestations are suspected.
KNEE LIGAMENT STABILITY
Check each knee for evidence of anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and rotatory instability. Include Lachman's test, posterior drawer and pivot shift maneuvers (Fig. 3.18).
Patients with ligament insufficiency often complain of pain and "giving way," which can be confused with patellofemoral pain and instability. Chronic ACL deficiency is associated with a 20 to 27% incidence of anterior knee pain (69, 70). Up to 90% of patients with PCL tears have complaints of knee pain with activity (71). Parolie and Bergfeld reported that 48% of their chronic PCL deficient patients had stiffness following prolonged sitting (ie, the classic patellofemoral "movie‑theater sign") (72). Posterior cruciate tears increase patellofemoral joint reaction forces by posterior displacement of the tibial tuberosity. This effect is exactly the opposite of the beneficial unloading accomplished by tubercle anteriorization. Because cruciate ligament injuries occur commonly, knee ligament stability examination is important to identify factors that may contribute to knee pain in each patient. If cruciate ligament deficiency is discovered, treatment must be modified accordingly.
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