Knee hooks and hangs and how the knee engages.
Initial idea of exploration:
I'd like to explore more about torsion in knees and how the joint interacts in various hanging capacity focusing on which muscles are in use to keep the hang healthy.
· I don't know what information exists currently, but I've got a book on Applied Anatomy of Aerial Arts, as well as Pole Anatomy and I would bet they cover hanging from a trapeze or bar of sorts, lyra, silks, or pole. Question one: what information readily exists?
· I'm curious how things change when going from a purely vertical hang to slanted/horizontal contact. Question two: how is the knee intended to work in pole knee holds, hooks, etc?
I think these questions complement what we've learned in Invert Ready by exploring what happens after we get upside down a little more.
The Knee
Anatomy basics
The primary bones involved in the joint are the femur, the patella, and the tibia. The fibula isn’t weight bearing and doesn’t move much, so I’m choosing to ignore it (see video: Knee Anatomy). The knee cap is intended to shield the joint from traumatic impacts. All surfaces that articulate (move) against another bone are covered in cartilage, and there is a sack of synovial fluid around the knee joint structures for additional insulation and lubrication (ease of movement). The two C-shaped menisci (soft cartilage) are the great equalizing agents that spread the weight load evenly around the tibial plateau surface (preventing damage to the hard cartilage surfaces, and potentially the bones) and assists in absorbing impact to project the joint.
The medial collateral ligament and lateral collateral ligaments keep the femur and tibia stabilized and aligned against too much side-to-side translation. The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) form a cross when viewed from the front and their function is aligning and stabilizing the femur and tibia from too much forward or backward translation.
The quadriceps and hamstrings are responsible for straightening and bending the knee. A series of tendons connect the muscles to the bones: the quadricep tendon connects to the patella, and the patella tendon connects the patella to the tibia: these are utilized in straightening the knee. The hamstring tendon connects the hamstring to the back of the tibia, and is utilized in bending the knee.
I was surprised that none of the muscles of the lower leg take an active role in bending or straightening the knee. Upon further reflection, this makes sense that any sensations I feel in “my knee settling into place” doesn’t really change if I activate my calf muscles: but activating my quads in opposition to my hamstring in a bent position will affect how my knee feels overall in a bent position.
How the knee moves
Skimming various articles, general consensus in the medical and PT world is that the knee is a hinge and it’s not good when the ligaments are asked to accommodate torsion in the knee joint. Aditionally, the knee does not “bend and separate” or “bend and crush”: it simply only bends. This means that pulling the knee into a deeper bend than can be achieved just using muscles might strain the ligaments by forcing simultaneous crushing on the posterior side and stretching/separation on the anterior side.
Hangs, hooks, and what is my “knee” doing on the pole?
Initial thoughts
Before opening up my books, it seems to me that whatever the knee is “doing,” it’s important that the other leg, a hand, or someone spotting a body through transitions into poses does not cause the upper and lower legs to twist through the knee: security in a knee grip must come from the quadriceps and hamstrings moving and holding the knee into any amount of bend.
Aerial knee hangs
Emily Sherb, PT states “to execute a proper knee hang position, aerialists need to be able to fully open their hips so they are straight,” (Sherb, E. p.67) meaning that hanging from a horizontal apparatus the leg is in 180 degree extension. While the hamstring is responsible for initiating and keeping the bend in the knee(s) while pulling the hips into extension, pointing the feet(toes) assists in bending the knee by flexing the calf and gastrocnemius which crosses both the knee joint and ankle. Aerialists (pole dancers) run into issues when they’re not recruiting their core muscles (primarily the transverse abdominis) and glutes to stabilize the pelvis and spine to counter the posterior tilt and pull from the hamstring on the pelvis. The quadriceps should be relatively relaxed when hanging from both knees from a horizontal apparatus is order to maintain an open hip position. Using the quads will pull the person into a slightly piked position by causing an anterior pelvic tilt because the quads overpower the hamstrings, and may also unintentionally straighten the legs.
With regard to single knee hangs (and easiest to translate to pole), keeping the pelvis in a neutral position, as well as hips level, allows the athlete to have the greatest hold in their knee hang (Sherb, E. p.74).
Brass Monkey hang
Just like hanging from a horizontal apparatus, the hamstrings and gastrocnemius are flexing the knee around the pole, a position which is strengthened by the pointed foot (Wilby, N. p.113). It’s noted that a small amount of hip flexion can create an additional grip point on the outside of the hip. The staying power in this hang, though, comes from hip abductors and adductors contracting to maintain tensions around the grip points while the hip rotators stabilize the legs in an external rotation. The outside leg can be positioned to create symmetry, extended up the pole, or explore other positions. Eros is an example of a position where everything but the hanging leg rotates around to a create a completely different look. Sometimes the foot of the floating leg crosses over the hooked leg’s ankle for an added sense of stability, however too much pressure from this bind can damage the ligaments in the knee. This is because the knee does experience mild twist in the brass monkey knee hang and additional force may cause them damage.
Outside leg (knee) hang (p. 121)
The hip flexors (iliopsoas and rectus femoris) bring the outside knee toward the torso while the hip adductors bring the leg across the midline of the body. Once the leg is past the pole, the hamstring bends the knee while the hip rotators stabilize the leg in an externally rotated position hooked on the pole. The gastrocnemius and soleus point the foot, while also creating firm tissue to squeeze the pole. The core musculature is recruited to rotate the abdomen away from the pole creating tension between the pole and the transverse abdominis muscles that are against the pole. There is room to explore various shapes with the other leg, twist of the chest, and arm placement while the knee hook and side body maintain the grip points.
Jasmine (p.129)
Similar to an outside knee hang, the hooked leg is utilizing all the same muscles and positioning. However, the pelvis is closer to and rotated toward the pole putting the leg in an adducted position and usually bringing the pole to rest in or near the crease created by the inside leg.
Inside leg (knee) hang (p. 134)
The hamstring bends the knee while the iliopsoas and rectus femoris bring the knee toward the chest. The hip abductor and hip rotators externally rotate the leg and allow the bent leg to cross the midline of the body to hook the pole. If these muscles aren’t recruited enough for the duration of the hang, the grip on the pole is lost.
Conclusion
The hamstring does the work to keep the knee in a hook position. The glutes, hip rotators, core musculature, and sometimes the hip flexors dictate where the body positions in relation to the hook, but has no bearing on the quality of the hook itself. The hip adductors and abductors play a role in squeezing the pole more or less as desired by the dancer. Pointing one’s foot is the simplest way to create firm tissue against which the pole can sit, similar to the hamstring being firm when bending and maintaining the bend of the knee.
Brass Monkey seems like the most likely hang in which knee injury can happen since it has the most inherent twist of the joint, however applying too much tension (crossed ankles, a hand, etc) to the ankle of the bent leg can also cause injury by applying too much tension on the ligaments as well. Recruiting one’s quads will hinder the quality of the hook because its purpose is extending the lower leg into a straighter position.
While not explored above, a cross knee layback could cause a dancer damage to their knee ligaments if they lack the mobility to externally rotate their hips enough to create and maintain the bent cross-legged bind without twisting the knee with too much tension applied to pulling on the bent leg’s foot.
Overall, the answer I was seeking for what makes a healthy bent knee “wrapped” around a pole seems to be this: by using the hamstring and the gastrocnemius and soleus to support the knee bend, the less-flexible ligaments that align and stabilize the knee can be protected from undue point-pressure or tension by creating a “flexed muscle barrier” between the ligaments and the pole. As well, knees are fascinating and their “rotating power” comes from manipulating the hips and pelvis.
References:
Scherb, E. Applied Anatomy of Aerial Arts. North Atlantic Books, California, USA. 2018.
Wilby, N. Pole Anatomy. (volume 1). Lancashire, UK. 2022.
YPO Orthopedic Surgeons, “Your Practice Online: Patient Education Library,” Knee Anatomy. 2022. https://www.ypo.education/orthopaedics/knee/knee-anatomy-t194/video/
International Association for Dance Medicine and Science, (blog) “Introducing the knee: anatomy and biomechanics,” Anatomy of the Knee Joint. 2016. https://iadms.org/resources/blog/posts/2016/november/introducing-the-knee-anatomy-and-biomechanics/ and specifically https://youtu.be/_q-Jxj5sT0g