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Joint Position Sense Regained after Shoulder Surgery

Have you ever wondered how it is that you can move each arm together in exactly the same arc of motion? And how is it that you can do it with the same speed, and end up in the same position every time? The joints have a function called proprioception that makes this all possible.

Part of proprioception is joint position sense. The joint can actually tell where it is in relation to the body and other joints. The nerves in the muscles and ligaments around the shoulder send messages to the nervous system about the joint's location.

In this study, shoulder joint proprioception was measured before and after an operation to repair an unstable shoulder. Fourteen patients were followed for at least five years. Results were measured using a test called the active angle reproduction test. This test shows the patient's ability to put the shoulder in a set position using joint position sense.

Results were compared for the injured shoulder and the uninjured arm in the study patients. Results were also compared to subjects with normal shoulders. At first everyone was allowed to see his or her own movement. Then everyone was blindfolded. This takes away visual control. Patients and control subjects had to move the shoulder into one of 36 different joint positions.

The authors found a big improvement in joint proprioception in the operated shoulder. This result was present after an average of almost six years of follow-up. Shoulder movements away from the body and shoulder rotation improved. Before the operation, patients had worse results compared to the healthy control group. Five years after the operation, the patients had better joint position sense in both shoulders compared to the control group.

Researchers aren't sure why patients get better proprioception than normal subjects after an operation to repair the shoulder. Only a few studies of this topic have been done. It may be that the soft tissues and ligaments around the shoulder regain their tension, or "spring."

There were only 14 patients in this study, and the normal subjects weren't measured five years later. For these reasons, the authors advise a larger study in the future to repeat this test. For now, we know joint position sense can be recovered in some patients after surgery to repair an unstable shoulder.

References: Wolfgang Pötzl, MD, et al. Proprioception of the Shoulder Joint after Surgical Repair for Instability: A Long-Term Follow-up Study. In The American Journal of Sports Medicine. January/February 2004. Vol. 32. No. 1. Pp. 425-430.

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