Pain and Function After Orthopedic Surgery

Primary indications for major joint surgery include limited joint function and pain. Although joint replacement or repair surgery is usually remarkably effective, in some cases pain and function are worse or not improved after surgery. Chronic pain after some surgical procedures, e.g., phantom limb pain after extremity amputation, has been long recognized, but more recent investigations suggest that chronic pain after physical injury including that of major surgery is not uncommon. The purpose of this study is to provide preliminary data for a Program Project Grant to the National Institutes of Health to examine specific hypotheses regarding identifying patients at risk for chronic pain after surgery and probing mechanisms which may be manipulated to decrease this risk.

Methods:

Patients who are undergoing elective orthopedic surgery: unicompartmental knee replacement or a total knee replacement will be approached and asked to provide consent to participate in 6 months of observation after their surgery. During this time, participants will not alter their usual treatment in any way (i.e., no treatment algorithms will be altered for this study), but will complete diaries and survey instruments at numerous intervals.

Objectives:

1. To demonstrate the feasibility of conducting this protocol in this clinical population. The execution of this study will allow us to identify expected enrollment rates, patient drop-out rates, and other threats to the accurate assessment of the course of pain after major joint surgery.
2. To estimate the individual variability in pain trajectories over time and to obtain effect size estimates for factors that predict pain trajectory.

Interventions:

The proposed study is a prospective longitudinal observational study. All patients will complete written informed consent.

The following questionnaires will be completed:

Daily Stress Inventory Multidimensional Pain Inventory Catastrophizing Scale of the Coping Strategies Questionnaire Center for Epidemiological Studies Scale of Depression Stait-Trait Anxiety Inventory Pain Anxiety Symptom Scale Pain Medication Attitudes Questionnaire Pain Disability Index Pain Locus of Control Scale Pain Self-Efficacy Scale Marital adjustment test Job Satisfaction Survey Tampa Scale of Kinesiophobia

At Home Diary Assessments Each of the following measures listed below are programmed into an electronic diary (iPod touch) that has been especially programmed for the current study using Pendragon Forms VI.

All participants will complete the assessments in a sequence using one of several methods:

1. Inpatient evaluation (surgery to discharge): Nursing staff will inquire about the patients pain levels using standard of care methods and assessment tools (e.g., numerical rating scale 0 - 10).
2. Ecological Momentary assessment (discharge to day 14): The diary is programmed to emit an alarm at three random times throughout a 12-hour day (i.e., during the patients wake cycle). The patient will then have 10 minutes to complete an entry for that entry to be considered valid (i.e., waiting 2 hours to make an entry is not capturing the random assignment of assessment times).
3. Once daily (day 15 to day 28): The patient is instructed to complete a diary entry at the end of their day, just prior to going to sleep.
4. Once weekly (day 29 to day 85): The patient will be called at their home and participate in a brief interview.
5. Once monthly (day 86 to day 168): The patient will be called at their home and participate in a brief interview once each month.

In addition, information from the postoperative care from the orthopedic surgery division will be recorded, including range of joint motion and functional limitations, if any, at the times of routine postoperative clinic visits. The iPod touch will be returned at the postoperative visit following surgery.

Outcome measures: The primary outcome measure for this study is self-reported pain intensity. To obtain estimates of pain intensity, we will use the McGill Pain Questionnaire - Short Form (MPQ). This instrument has been extensively used to assess pain in a wide variety of settings, and is uniquely suited to our present study in that the items can be completed while in a post-operative setting as well as a daily diary setting.