BY: Mohammad Wahdan
I. Description of Motion: Knee Flexion1
Primary Muscles Involved: Hamstring Muscles ( Biceps Femoris, Semitendinous, Semimembranous)
Secondary Muscles Involved: Sartorius, Gracilis, Popliteus, Gastrocnemius
Nerve Roots Involved: Sciatic Nerve L4-S3
II. Mobilizing: Increasing Range of Motion
Seated Heel Slides: Seated in a chair you slide the involved LE back under the chair as far as you can go until you feel a tolerable stretch (should not feel intense pain). Hold it for 5 seconds and perform 3 sets of 10 repetitions. Rest one minute between each set and remember not to hold your breath with this activity. Note: This exercise should be done on smooth non-carpeted area and you can use the opposite LE to assist in the motion as well.3
Prone Quad Stretch With Belt: Begin by attaching a long belt or dog leash around the ankle of the involved leg; lie facing down on a safe surface and grab the belt and slowly pull the ankle towards buttocks until you feel a stretch which should not feel painful and hold for 30 seconds; slowly release and repeat; you should perform 1 set of 4 repetitions with a one minute break in between each set. Remember not to hold your breath with this activity.4
Thomas Test Stretch: Begin lying on a foot of a firm table or bed with legs hanging off the edge while pulling the opposite knee up towards your chest; keep your involved leg flat on the bed so that you can use gravity to help stretch out the tight muscles. You should feel a stretch but not pain with this stretch. Let it hang for 30secs. Perform 1 sets of 5 repetitions. Rest a minute between each repetition and remember not to hold your breath with this activity.5
III. Indications for Stretching:6
Normal Knee Flexion ROM is (135-150 degrees) with a Soft End Feel: possible factors that could limit knee flexion include:7
o Possible Muscle Limitations May Include: Tight Articularis Genu, Vastus Lateralis, Vastus Intermedius, Vastus Medialis and Rectus Femoris.
o Possible Muscle Weakness May Include: Weak hamstrings, gastrocnemius
o Possible Joint Limitations May Include: Effusion (most common) because swelling fills up anterior capsule which limits knee flexion, patella alta secondary to tight rectus femoris and proximal tib/fib joint.
o Possible Fascia Limitations May Include: Anterior Fascia Lata
o Other Causes: Gastrocnemius bulk/hypertrophy can also limit knee flexion.
Most common conditions/indications that are supported by literature that require mobilizing or stretching.
Seated Knee Flexion (leg curls): Secure the appropriate elastic “thera-band” around a secure object; sit in a chair and attach elastic “thera-band” around the ankle of the involved leg; pull heel under the chair through available pain free range and slowly return to the stating position; Perform 3 sets of 10 repetitions; rest one minute between each set; To progress this activity increased this exercise increase the elastic “thera-band” resistance and/or use ankle weight.8
Knee Flexion Using Rolling Stool (AROM): Begin by safely sitting on a rolling stool on a smooth surface. Extend the involved knee and firmly place the foot on the floor. Pull back with the extended knee to propel forward ensuring that the foot stays firmly in place. Next extend the involved knee and return to your starting position. Perform 3 sets of 5 repetitions. Remember not to hold your breath with this activity. Rest one minute between each set.
To progress this activity alternate using both legs to propel forward firmly planting each foot on the floor before moving. Continue propelling forward 20 steps across the floor. Increase sets and repetitions accordingly.
Supine Hamstring Knee Bends: Begin by lying on a firm surface with knees bent up on an exercise ball, take a deep breath in and roll the exercise ball closer to buttock as far as you can keeping your trunk on the floor. Exhale and slowly and safely return to the starting position. Perform 3 sets of 10 repetitions. Remember not to hold your breath with this activity and rest one minute between each set. To progress this activity place feet on an exercise ball. Take a deep breath in and lift buttocks up, and then work to roll the exercise ball towards your buttock. Exhale and slowly lower the trunk returning to the starting position. Increase sets and repetitions accordingly.10
V. Potential Clinical Syndromes or Etiologies:
• These techniques are ideal for any post-surgical procedures of the knee, especially pre/post total knee arthroplasty, because of all the inflammation that occurs limiting knee flexion.
• Click on the link below to access addition lecture materials about potential clinical syndromes or etiologies.