The knee is a synovial, hinge joint. The primary function of the knee is mobility and stability. The femur and tibia are two long lever arms which cause great forces at the knee joint and potential for ligamentous and cartilage injuries. Compressive forces while weight bearing also provide stability to this joint. Mechanisms of injury can be sudden,traumatic injury or microtrauma over a longer time period. Excessive torsional, valgus/varus loads often compromise the meniscus, ligamentous system, and patellar dislocation. Microtrauma over longer periods of time tend to damage articular cartilage of the patella, chondral defects, iliotibial band syndrome, tendonitis, and synovitis.
"Advanced Knee Rehabilitation" video clip
Windows Media Video file, 1.1 MB
Open versus Closed Kinetic Chain
- Open kinetic chain (OKC) defined as terminal segment is free to move i.e. kicking your leg.
- Closed kinetic chain (CKC) defined as terminal segment is fixed i.e. squatting.
Clinical models have reported that CKC exercises are more functional and reported that CKC exercise should be the primary source for knee rehabilitation.
IS CLOSED KINETIC CHAIN MORE FUNCTIONAL?
Mann et al.AJSM 1980. reported swing phase in running 70%, and stance phase 30%. Swing phase 80%, 20% stance phase with sprinting. This rapid succession of OKC-CKC concept with gait, translated into the clinic with the plyometric training.
"Closed Kinetic Chain Knee Rehabilitation" video clip
Windows Media Video file, 4.1 MB
Anterior/posterior tibiofemoral shear forces(Wilk):
- Knee extension(OKC): 100-45 degrees load PCL ligament until 40-0 degrees which is ACL load
- Knee flexion (OKC): 0-40 degrees ACL load
- Squat and leg press (CKC): peak PCL load at knee flexion 90 degrees, no load on ACL
Escamilla 1995 Squat and leg press comparison foot placement high versus low and wide versus narrow reported:
- 40-65% increased compression at the knee joint with squat
- 20% more quadriceps, 10-15% increased PCL load with leg press with feet low
- 20% more compression with leg press feet high versus feet low
- 5-10% more PCL shear leg press feet narrow
- 10-30% increased Hamstring/ gluteus maximus recruitment squat feet wide
- 5-20% increased gastroc/quadriceps recruitment squat feet narrow
Hamstring peak activity Squat ascend from 88-102 degrees>leg press>seated knee extension(Wilk).
Hamstring > quadriceps recruitment with retrostairclimber. Zimmerman JOSPT 1999.
Quad to Hamstring ratio 2.6 to 1 with lateral step up. Brask Phys Ther 1984.
Quad recruitment lateral step > stairclimber. Cook Phys Ther 1992.
Rehabilitation programs design should take into consideration treatment goals and precautions when implementing exercise and not CKC exercises only. CKC exercises produce greater compressive load which promotes stability but can compromise meniscal repairs, chondral defect repairs if implemented to early. If PCL deficit knee, leg press would cause adverse loads to the PCL but would be key exercise for ACL deficit knee. Leg press> squat for VMO to Vastus lateralis ratio in recruitment which is desirable for patellofemoral dysfunction. VMO EMG study (Simonean, Wilk) displayed higher
VMO/VL ratio with quad set>lateral step up>leg press>TKE>squat.
ACL reconstruction leg press utilized @ 0-30 degrees due to
co-contraction of quad and hamstring. Patellofemoral compression peak:
TKE 40-0 degrees, exercise safely @90-40 degrees.
Squat 70-90 degrees, exercise safely 0-50 degrees
MANUAL THERAPY CONSIDERATIONS for THE KNEE:
The iliotibial band(ITB) inserts onto the head of the fibula. The ITB tendon glides as the knee flexes and extends. It acts as a secondary knee extension from 30-0 degrees and secondary knee flexion 40-135 degrees. Tibiofemoral screwhome mechanism at 30-40 degrees and ITB no influence.The proximal and distal tibiofibular joint can be become dysfunction and be a pain generator. Common posterior subluxed fibular head with tibial external torsion and inversion ankle sprains. Very common to have proximal posterior tibiofibular restriction and an anterior subluxed distal tibiofibular restriction which responds well to manual therapy. Not uncommon to require taping/strapping to stabilize the joint between manual therapy sessions especially if chronic condition.
"Fibula is the Link to the Foot and Ankle"
Common Mechanical Dysfunctions that will influence the knee joint:
Manual therapy can indirectly influence to the knee joint by restoring the pelvis (iliosacral, sacroiliac, and pubic symphysis) if mechanical faults exists. Mechanical SIJ dysfunction can cause an apparent leg length discrepancy causing a compensatory effect throughout the lower extremity influencing the knee and ankle/foot complex.
Common Inhibition Patterns that will influence the knee joint:
Inhibition of the gluteus medius, hip external rotators due to hip capsular tightness can cause increased femoral internal rotation, excessive tibial external rotation, calcaneal eversion and foot supination. Manual therapy mobilization of the tight hip capsule will allow recruitment and specific strengthening to these muscles and eliminate subsequent compensatory patterns.
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