Knee Pain
Answer: D
This man is suffering from patellofemoral pain syndrome (PFPS), found to be the etiology in up to 25% of acute knee pain cases (D). Although the pathophysiology is not completely clear, it is thought to be due to overload (over-training or overexertion), malalignment (abnormal patellar tracking), or trauma (usually a direct blow to the anterior knee). Pain may be in both knees, and is often described as “achiness” around the patella. Patients may describe a “buckling” or “giving out” of the affected knee, probably due to pain inhibiting the full contraction of the quadriceps. This is distinct from true instability from a patellar dislocation or subluxation or ligamentous injury of the knee. A genuine “locking” of the knee or a significant effusion are not consistent with PFPS. Pain typically worsens with running, squatting, or using the stairs.
An examination should include the typical knee exam, in addition to a few special tests:
Palpate the patellar tendon: tenderness directly over the patellar tendon is more likely to be caused by patellar bursitis, not PFPS.
Compress the patella: with the leg extended, compress the patella directly posterior (into the trochlear groove) – pain is consistent with PFPS.
Displace the patella: with the leg extended, press on the medial patella, displace laterally – at the same time, palpate the lateral facet of the patella – tenderness is consistent with PFPS.
Glide the patella: with the knee extended, gently displace the patella back and forth, medially and laterally. You should be able to displace a normal patella approximately one-half of its width. Minimal displacement (less than ¼) is consistent with a tight retinaculum. Excessive displacement (more than ¾) defines a hypermobile patella.
Patellar apprehension: with the knee flexed at 90 degress, apply pressure to medial patella laterally (as above, but with knee flexed). Watch the patient for grimace or anxiety/apprehension – if present or if the patient attempts to straighten the leg during the maneuver, this is consistent with PFPS.
Examine the hamstrings: tight hamstrings are adaptive to PFPS but also contribute to increased compressive forces on the knee. You may also have the patient flex the knee to 90 degrees and extend until the patient is uncomfortable. If unable to extend the knee fully, this is consistent with PFPS (popliteal angle of 20 degrees or greater).
In a meta-analysis by Nunes et al, the patellar tilt test had a LR + of 5: with the knee in extension, grasp the superior and inferior poles of the patella; “tilt” the lateral aspect of the patella above the horizontal plane (“tilt up”) – this is possible in a normal knee; in a patient suffering from PFPS, the tendon will be too stiff and the tilt is not possible.
In addition, you may observe the patient’s gait and performing a squat to contribute to making the diagnosis.
Treatment includes curtailing training/rest, NSAIDs, and ice (one tip is to have the patient freeze water in a Styrofoam cup, peel away some of the Styrofoam as the patient “massages” the ice around the patella for 10-15 minutes at a time, up to twice per day).
PFPS is a peri-articular condition; signs or symptoms consistent with an intraarticular lesion make the diagnosis much less likely (A). There is no need to immobilize the joint, as there is no intraarticular damage (B, C). Simply modifying activity will contribute to recovery.
Patients who do not respond to rest, NSAIDs, and ice need close follow-up and physical therapy (stretching regimen, core strengthening) or possibly orthotics.
Nunes GS, Stapait EL, Kirsten MH, de Noronha M, Santos GM. Clinical test for diagnosis of patellofemoral pain syndrome: Systematic review with meta-analysis. Phys Ther Sport. 2012; [Epub ahead of print: 8 Dec 12] doi: 10.1016/j.ptsp.2012.11.003.
Wishing you a Merry Christmas and Happy New Year!
This man is suffering from patellofemoral pain syndrome (PFPS), found to be the etiology in up to 25% of acute knee pain cases (D). Although the pathophysiology is not completely clear, it is thought to be due to overload (over-training or overexertion), malalignment (abnormal patellar tracking), or trauma (usually a direct blow to the anterior knee). Pain may be in both knees, and is often described as “achiness” around the patella. Patients may describe a “buckling” or “giving out” of the affected knee, probably due to pain inhibiting the full contraction of the quadriceps. This is distinct from true instability from a patellar dislocation or subluxation or ligamentous injury of the knee. A genuine “locking” of the knee or a significant effusion are not consistent with PFPS. Pain typically worsens with running, squatting, or using the stairs.
An examination should include the typical knee exam, in addition to a few special tests:
Palpate the patellar tendon: tenderness directly over the patellar tendon is more likely to be caused by patellar bursitis, not PFPS.
Compress the patella: with the leg extended, compress the patella directly posterior (into the trochlear groove) – pain is consistent with PFPS.
Displace the patella: with the leg extended, press on the medial patella, displace laterally – at the same time, palpate the lateral facet of the patella – tenderness is consistent with PFPS.
Glide the patella: with the knee extended, gently displace the patella back and forth, medially and laterally. You should be able to displace a normal patella approximately one-half of its width. Minimal displacement (less than ¼) is consistent with a tight retinaculum. Excessive displacement (more than ¾) defines a hypermobile patella.
Patellar apprehension: with the knee flexed at 90 degress, apply pressure to medial patella laterally (as above, but with knee flexed). Watch the patient for grimace or anxiety/apprehension – if present or if the patient attempts to straighten the leg during the maneuver, this is consistent with PFPS.
Examine the hamstrings: tight hamstrings are adaptive to PFPS but also contribute to increased compressive forces on the knee. You may also have the patient flex the knee to 90 degrees and extend until the patient is uncomfortable. If unable to extend the knee fully, this is consistent with PFPS (popliteal angle of 20 degrees or greater).
In a meta-analysis by Nunes et al, the patellar tilt test had a LR + of 5: with the knee in extension, grasp the superior and inferior poles of the patella; “tilt” the lateral aspect of the patella above the horizontal plane (“tilt up”) – this is possible in a normal knee; in a patient suffering from PFPS, the tendon will be too stiff and the tilt is not possible.
In addition, you may observe the patient’s gait and performing a squat to contribute to making the diagnosis.
Treatment includes curtailing training/rest, NSAIDs, and ice (one tip is to have the patient freeze water in a Styrofoam cup, peel away some of the Styrofoam as the patient “massages” the ice around the patella for 10-15 minutes at a time, up to twice per day).
PFPS is a peri-articular condition; signs or symptoms consistent with an intraarticular lesion make the diagnosis much less likely (A). There is no need to immobilize the joint, as there is no intraarticular damage (B, C). Simply modifying activity will contribute to recovery.
Patients who do not respond to rest, NSAIDs, and ice need close follow-up and physical therapy (stretching regimen, core strengthening) or possibly orthotics.
Nunes GS, Stapait EL, Kirsten MH, de Noronha M, Santos GM. Clinical test for diagnosis of patellofemoral pain syndrome: Systematic review with meta-analysis. Phys Ther Sport. 2012; [Epub ahead of print: 8 Dec 12] doi: 10.1016/j.ptsp.2012.11.003.
Wishing you a Merry Christmas and Happy New Year!