The crank arm test: why and how symptoms develop

2021-01-26 12:00 AM

Any disturbance of open structures for a rotary arm therapy in positive patients and general malaise

The crank arm test tries to determine if the shoulder joint is currently unstable. For patients sitting or lying on their backs, the shoulders are moved passively into a fully rotated and outward rotating position. Apply a back-to-forward force to the back sections of the brachial head (see figure). The test is positive if the patient is afraid that the shoulder may be removed. Negative if the test produces only pain.

Figure. The crank arm test

Arms fixed in an outward rotating position. Note that the examiner's right arm is pulled forward on the arm bone, pulling the back of the brachial head forward. Similar tests can be performed from the back, with the patient sitting and the examiner pushing forward the upper and rear ends of the arm bone.


Common - trauma

Mild shoulder joint dislocation or dislocation.

Shoulder ligament damage.

Damage to the front bank of the pans.

Separate the synovial sac from the ligament.

Rarely - not due to injury

Ehlers – Danlos syndrome.

Marfan's Syndrome.

Lack of congenital pans.

Defect of the shoulder or arm bone.


The main cause of the positive forearm test is damage or dysfunction of the sheath, cartilage, ligaments or muscles that maintain stability in the shoulder joint. Pre-joint errors occur in 95% of joint mismatches.

The average person has a certain degree of shoulder joint laxity or instability, allowing the shoulder joint to work with a wide range of action. The main factors for maintaining shoulder joint stability are:

Ligament of the shoulder joint - a major stabilizing factor.

Shoulder muscles - the muscles under the shoulder have an important stabilizing role.

Cartilage and rim cartilage.

Any disturbance of open structures for a rotary arm therapy in positive patients and general malaise.

In the forearm test, the 'level' rotates the brachial apex forward and, with the assistance of the examiner, pushes the head of the brachial forward. If there are any (or more) defects in the general stabilization media, the arm cap will move forward - or shrink the ability to even leave the pan. This causes discomfort and "fear" of imminent misalignment.


The test is reasonable for shoulder joint instability, with particularly high specificity but with only moderate sensitivity.

Rowe's initial report had 100% specificity that predicted general malaise of the shoulder joint. A follow-up study of 46 patients found a modest sensitivity of only 52.78% but a specificity of 98.91%. The specific C is further improved when the method is combined with other methods including the 're-arm' method.