Can clinical tests accurately diagnose chronic acromioclavicular joint pain?

The first 20 consecutive participants will be included the inter-rater reliability component. These participants will undergo a standardised interview and physical examination with either the orthopaedic surgeon or an experienced physiotherapist (based on current practice). For each of the physical tests, the participant will grade the intensity of their pain using the Numeric Pain Rating Scale. Following this examination, the patient will be given a minimum of a 30 minute interval before a second clinician repeats the physical examination. All patients will be given standard care management after this assessment. The next consecutive patients will be recruited into the diagnostic accuracy arm and examined using the standardised assessment as above by either the physiotherapist or an orthopaedic surgeon. The physical assessment however will differ from the reliability study as the it will only include tests that meet a threshold of 70% agreement and 04.1 PABAK in the reliability section. As a result we have included 17 physical tests instead of 22. If they fit the inclusion criteria and have consented, they will be offered a diagnostic sub-acromial anaesthetic injection. 10 minutes following the injection participants will undergo the physical examination a second time to rate their pain scores. The 3 most painful tests from the first examination will be compared at the second assessment and the change will be calculated. Patients with an 80% or greater reduction in pain intensity following this injection will be considered to have sub-acromial pain. Patients who have less than an 80% reduction in pain intensity will offered an appointment (within 1-2 weeks) for an image guided anaesthetic injection into their ACJ. The lead researcher will call all Maaori participants the day before their radiology appointment to check if they have any questions or concerns and to encourage them to bring a support person should they wish. At this second appointment, the standardised physical examination will be repeated to establish baseline pain intensity prior to the ACJ injection. The injection will be performed by a radiologist or radiology registrar who will be blinded to the findings of the physical examination. Thirty minutes after this injection, the physical examination will be repeated so that any change in pain scores can be determined and recorded. Those participants with 80% or more relief of their pain following the ACJ injection will be diagnosed with ACJ pain. All sessions will last 1.5-2 hours, this includes the reliability component and the 1st and 2nd appointments for the diagnostic accuracy component. For the reliability component participants will fill out the questionnaires initially then the standardised assessment (interview, physical testing) will take 30 minutes, they will then be asked to wait in the waiting room for 30minutes before undergoing the physical assessment again (15minutes). Following this they will be offered standard management (15minutes). In the diagnostic accuracy component participants will fill out their questionnaires, undergo their assessment (30 minutes) then have their subacromial injection and wait in the waiting room for a further 30 minutes. After this they will be taken through the physical assessment a second time (15 minutes). If they have a positive subacromial anaesthetic response they will then be offered standard management (15minutes). If they do not they will be booked in for a second appointment for an ACJ injection. At the second appointment the physical assessment will be undertaken (15minutes), participants will have their anaesthetic injection into the ACJ performed by the radiologist and then wait 10minutes before repeating the physical assessment (15minutes). They will then be offered standard management options. This process reflects standard care management which is being assessed then offered a diagnosis. The patient is then given treatment options which can include physiotherapy, a steroid injection, surgical management (not likely in this cohort) or perhaps further investigation i.e. imaging or blood tests. 5 examples of the physical tests are acromioclavicular palpation, active\passive range of motion and resisted flexion, abduction, external and internal rotation, paxinos test, resisted AC extension and the O’Briens compression test. For a full list of the tests please see the appendix of the PGR1 attached. The first injection into the subacromial space will not be image guided. The decision to perform this injection without image guidance is a pragmatic one. This is standard practice at the outpatient clinic and it is not appropriate to change this component of their diagnostic workup. Research by Kane and Koski (2016) demonstrates the accuracy rate for a blind subacromial injection is 70-91%. This compares favourably to blind ACJ injections which have only 24% accuracy (Javed et al., 2017). Should the blind SAI be inaccurate participants are very unlikely to demonstrate a positive anaesthetic response and therefore still go on to have a guided ACJ injection. The subacromial injection will be performed in the clinic. Participants will be seated with their arm relaxed by their sides and the posterior shoulder exposed. Under aseptic conditions, a 22-gauge needle will inserted into the subacromial space using a direct posterior approach. Approximately 5 mL of 1% lidocaine hydrochloride (xylocaine™) will be administered. The ACJ injection will be administered by a radiologist under ultrasound guidance. Subjects will be positioned supine with the arm in external rotation. Under aseptic conditions, a 22-gauge needle will be inserted into the ACJ using a direct anterior approach. Approximately 5 mL of 1% lidocaine hydrochloride (xylocaine™) will then injected into the ACJ. The radiologist will record whether the ACJ is successfully infiltrated, whether the joint was difficult to access, whether the patient had a painful response and whether the injectate was contained within the joint. 4 experienced clinicians with a minimum of 10 years’ experience will be performing the assessments. Should the participant not perform the physical test correctly this will be repeated. If they are too sore or are unable to complete the test this will be recorded as “unable to complete the test” and a reason will be recorded. Should there be an indeterminate result this will also be recorded. Counties Manukau DHB has a central computer database which records patients attendance and the participant’s outcomes will then be recorded in Redcap (data collection tool). Should they not attend they will be contacted and offered another appointment. If they wish to withdraw from the study their data will be marked as incomplete and a reason will be recorded.