By Anna Juzwiak
I. Description of Motion:
Knee Extension occurs when the concave tibia rolls and slides anteriorly on the convex femoral condyles.
Primary muscles: Quadriceps- Rectus Femorus, Vastus Lateralis, Vastus Medialis, Vastus Intermedius.
Knee extension is innervated by femoral nerve L2-L4.
II. Mobilizing – Increasing Range of Motion:
1. Long sitting gastrocnemius stretch: Patient is long sitting with one leg on the table and the other leg off the table. Strap is placed around forefoot of leg on table. Knee is kept in extension. Patient pulls on the strap to increase the stretch on the gastrocnemius.
To progress this stretch: Patient keeps erect posture and bends forward at the hips to increase stretch on hamstrings, while continuing to pull the ankle into dorsiflexion to stretch the gastrocnemius.
Hold this stretch for 30-60 seconds, 3 times. Repeat with opposite leg. Repeat this stretch 3 times per day to increase knee extension range of motion.
2. Standing gastrocnemius wall stretch: Patient stands facing the wall with hands at shoulder height. Patient places one foot back, with knee fully extended while keeping hips and feet facing forward. Patient should feel a stretch in their gastrocnemius. To increase intensity of the stretch, patient presses hips closer to the wall. This will increase the intensity of the stretch in their gastrocnemius.
Hold this stretch for 30-60 seconds, 3 times. Repeat with opposite leg. Repeat this stretch 3 times per day to increase knee extension range of motion.
3. Knee extension in supine: Patient is supine with one leg bent on the table. Hold the other leg behind knee, patient then extends the leg they are holding at the knee until a stretch is felt through the hamstrings. To include the gastrocnemius, patient can repeatedly dorsiflex the foot to feel an added stretch in the posterior leg.
Hold this stretch for 30-60 seconds, 3 times. Repeat with opposite leg. Repeat this stretch 3 times per day to increase knee extension range of motion.
III. Indications for Stretching:
Normal Knee Extension ROM is 120-0 degrees1. Knee extension muscle limitations may be due to tight hamstrings (Biceps Femoris, Semitendinous, Semimembranous), and Gastrocnemius2. Muscle weakness limiting knee extension may be due to weak quadriceps muscles. Joint limitations may be due to a total knee replacement, poor patella tracking, weak vastus medialis oblique, or a meniscal injury.
IV. Strengthening:
1. SAQ: Patient is supine with a bolster under knees. Patient keeps knee on bolster but slowly raises leg until straight. Patient then lowers foot back to table. Repeat exercise 10 times for 3 sets.
To increase intensity progress to long arc quads.
Patient is short sitting. Patient keeps leg on table but straightens knee out. Patient slowly lowers leg back to starting position. Do 3 sets of 10.
2. Quad Set: Patient is supine with towel roll behind knee. Patient contracts their quads and presses knee into towel roll. Hold for 10 seconds then relax. Repeat 10 times.
To increase intensity perform a Quad Set followed by a straight Leg Raise. Raise the leg off the table with knee in full extension. Slowly lower leg back down to table. Perform 3 sets of 10.
3. Deep squat: Patient is standing shoulder width apart and sits back as if sitting in a chair keeping their chest up and head forward. Patient attempts to get their knees parallel to the floor. Patient then extends knees to return to starting position.
To progress this exercise, wrap a resistance band around the patient’s knees. The band can either be held or tied to a table. The band is being pulled in an anterior direction and repeat the deep squat.
V. Potential Clinical Syndromes or Etiologies:
Clinical syndromes that these techniques may be appropriate for are an anterior cruciate ligament injury, hamtrsing strain, medial collateral ligament knee strain, meniscal tear, petallofemoral pain syndrome, posterior cruciate ligament injury, or a total knee injury3.
VI. Additional Web Based Resources:
VII. References (AMA format)
1. Available at: http://www.merckmanuals.com/professional/special_subjects/rehabilitation/physical_therapy_pt.html. Accessed December 3, 2014.
2. Lim K, Nam H, Jung K. Effects on hamstring muscle extensibility, muscle activity, and balance of different stretching techniques. JPhys Ther Sci. February 2014; 26(2):209-13.
3. Available at: http://morphopedics.wikidot.com/clinical-syndromes. Accessed December 3, 2014.
