The association between the COMT haplotypes and the presence or absence of CPSP or CRPS will be assessed stratifying the patients based on the individual categories of trauma or elective surgery.

This will be a prospective association study in which we will recruit patients who have experienced single extremity trauma, or who have scheduled elective surgery on a single extremity. HRQoL will be determined at recruitment. We will identify their haplotypes and genotypes for 4 linked SNPs in the coding region of COMT as described by Diatchenko [2]. Patients will receive follow-up at 3 and 6 months following trauma or surgery. Individuals who report either neuropathic pain or a reduced HRQoL score will be more closely examined, in order to identify CPSP or CRPS. Statistical analyses will be performed to determine whether haplotypes are associated with the development of either condition, and to determine the strength of this association.

Inclusion Criteria:

• Provide written Informed Consent prior to participation in the study
• Be at lease 18, but not more than 80 years of age
• Have the ability to read and understand the study procedures and the use of the pain scales and have the ability to communicate meaningfully with the Study Investigator and staff.
• Be free of other physical, mental, or medical conditions, which, in the opinion of the Investigator, makes Study participation inadvisable
• Is scheduled to undergo open or arthroscopic shoulder surgery
• If the subject is a female of childbearing potential, have a negative pregnancy test on the day of surgery.

Exclusion Criteria:

- Has significant medical disease(s), laboratory abnormalities or conditions(s) that in the Investigator's judgment could compromise the Subject's welfare, ability to communicate with the Study staff, complete Study activities, or would otherwise contraindicate Study participation

Patients undergoing shoulder surgery