The core of all learning is the identification of similarities and differences. One of the four methods of identifying similarities and differences that has proven to be highly effective is classification. I have developed a classification of shoulder locking techniques.
A joint is where two bones meet. The glenohumeral (GH) joint, or shoulder joint, is where the head of the humerus of the upper arm meets the glenoid fossa of the scapula. The bony arrangement of the shoulder joint consists of a shallow socket (glenoid fossa) to which is joined the one-half-spherical head of the humerus. It has been likened to a golf ball (head of the humerus) on a golf-tee (glenoid fossa). Less than half of the humerus is in the socket at any one time, and the bony arrangement is therefore weak.
A mobility-stability continuum has been proposed for joints. The stability refers to the amount of force required to dislocate the joint. The shoulder is the most mobile joint in the body and is therefore the least stable joint in the body.
What do hammer lock, figure four lock, reverse figure four lock, key lock, reverse key lock, kimura, ude garami, gyaku ude garami, ude garami henka waza, stappado and 'Palistinian hanging' have in common? They are all techniques that are designed to move a subject's shoulder joint towards or beyond the limits of its range of motion. What are the differences between these techniques? This is where classification comes in.
The classification of shoulder locking techniques is based on the intended movement of the humerus. The initial principle of division is rotation or extension. Rotation refers to the turning of a bone around its own long axis. Extension refers to moving the arm straight back behind the body. The rotation locks can be subdivided into internal and external rotation. Internal rotation refers to rotary movement towards the midline of the body. External rotation refers to rotary movement away from the midline of the body. The internal rotation locks can be further subdivided into adducted and abducted arm positions. Adduct refers to movement towards the midline of the body. Abduct refers to movement away from the midline of the body.
Jan de Jong was not a fan of the abovementioned shoulder lock because of the flexibility of some people. Some people can reach up behind their back and touch their hair line without experiencing pain. In addition, the method of holding a person in this technique is relatively insecure.
As it turns out, De Jong's ude garami henka waza is relatively unique within the martial arts world. The more common technique is a variation of this technique taught by Jan de Jong but which was little understood in his school.
In both variations of ude garami henka waza, the forces applied encourage uke to move in a particular way. Rotate back towards tori in the original version and to bend over in the variation. In both cases, additional forces are applied to resist this tendency and maximally stress uke's shoulder joint.
The abovementioned gyaku ude garami is similar to De Jong's ude garami henka waza in that both techniques result in internal rotation of the humerus in the shoulder joint. They are different in that in the former uke's arm is abducted while in the latter their arm is adducted.
When teaching these techniques in my 'shoulder lock master class', I have found it useful to use a maglite torch to simulate the humerus. The bulb represents the head of the humerus and cupping the bulb represents the shoulder joint. I then move the torch in the direction of the internal or external rotation, or extension, to illustrate the intention of the technique to the students. I have found this visualisation assists the students in applying the forces correctly when they execute the technique.
Four further things to note. Firstly, judo competition rules forbid any kansetsu waza (joint-locking technique) that targets any joint other than the elbow joint. They consider these techniques too dangerous for competition. They specifically allow ude garami and suggest it targets the elbow joint. Given the same arm configuration and force application is used by clinicians of various disciplines to test shoulder flexibility, it would appear the technique is designed to target the shoulder joint and not the elbow joint.
Secondly, there have been some, relatively few, who have attempted to anatomically describe certain locks. They incorrectly refer to hyper-flexion as being a mechanism of dislocation of the shoulder and/or elbow.
Thirdly, the classification is an ideal. When the techniques are applied, they may include both extension and rotation.
Lastly, other injuries other than shoulder dislocation have been reported. The kimura is named after a famous judoka who beat one of the founders of Gracie jiu-jitsu using this technique (gyaku ude garami). It is said that he broke Gracie's radius and ulna, and dislocated his elbow using this technique. Antonio Rodrigo Nogueira's humerus was reported to have been fractured by Frank Mir in a UFC match when the latter applied a kimura to the former. A person trained in Jan de Jong jujutsu engaged in security work applied the variation of the ude garami henka waza which resulted in a fractured humerus in the subject.
The last point is intended to head off criticism of the above classification and description based on reported injuries other than shoulder dislocations. Unfortunately, accurate and detailed reporting of injuries while executing these techniques has not been forthcoming to date. Given the shoulder flexibility tests, it is safe to assume the shoulder joint is the target of these techniques. It is open to correction, based on future studies, if other injuries are more likely when executing these techniques.