Our study showed that the painful apprehension test occurred in 25.8% of patients (40/155 patients) with bankart lesions that underwent arthroscopic repair, of which two-thirds (26/40 patients) were in the purely painful form. Importantly, arthroscopic stabilisation achieved excellent clinical outcomes in this subgroup of patients with the painful apprehension test, with significant improvements in the Constant, ASES and SF-36 scores, similar to patients with apprehension alone in the treatment of shoulder instability.
The anterior apprehension test of the shoulder performed with the shoulder in 90o of abduction and maximal external rotation, with the elbow in 90o of flexion has traditionally been used to clinically diagnosis anterior shoulder instability with great reliability[3, 5, 6]. Several authors have also reported that apprehension, rather than pain as the key criterion for the accurate diagnosis of instability using this clinical test[2, 8, 9].
Farber et al reported 93% overall accuracy of the anterior apprehension test when apprehension was used as the positive test criterion, which dropped to 55% when pain was used as the positive test criterion. However, a closer look at the diagnostic value of an apprehensive apprehension test would reveal that despite the excellent specificity of the test of 96%, its sensitivity in picking up positive cases is only 72% in that study. We postulate that a proportion of these “missed” cases might belong to the group with a purely painful apprehension test. While it may be true that doing MRI for all patients with a painful apprehension would lead to a high rate of negative scans, completely ignoring the purely painful apprehension test would lead to a significant rate of missed lesions that would have been managed appropriately with surgery. In our study of bankart lesions managed with arthoscopic stabilisation over where satisfactory outcomes were achieved, 16.8% of patients demonstrated apprehension tests in the purely painful form, involving patients with and without a prior history of traumatic shoulder dislocation.
The patient profile of the group with the purely painful apprehension test was similar to those with apprehension in terms of age, gender distribution, hand dominance and involvement in high risk occupations or competitive sports, with the majority having a history of prior traumatic dislocation (80.8%). With the majority of our patients with the purely painful apprehension test presenting with shoulder pain as a significant symptom at their first clinical visit (61.5% versus 30.4%) and lower rates of recurrent dislocation (23.1%% versus 47.8%) compared to patients with a purely apprehensive apprehension test, surgeons should have a high clinical suspicion for shoulder instability as the cause of the pain in the presence of a bankart lesion especially if other findings on imaging were deemed insignificant or asymptomatic with bedside tests. In this group of patients, pain was likely the protective mechanism limiting their shoulder range of motion before the shoulder could exceed its arc of stability. As such, rather than instability, they would more likely present with persistent shoulder pain and activity limitation instead. The abduction, external rotation (ABER) maneuver translates the humeral head anteroinferiorly causing it to “roll over” the Bankart lesion, which may not be extensive enough to destabilize the shoulder but adequately disrupted to cause pain. The universal arthroscopic finding in our series in patients with a painful shoulder was focal capsular synovitis around the frayed torn edges of the labrum which was the likely pain generator. Repetitive ABER motion might potentially perpetuate this “roll-over synovitis” leading to the predominant symptom of pain which may distract patients from a sensation of instability. We found no significant difference in the incidence of Bankart lesions, cuff pathology or SLAP lesions between patients with and without pain on apprehension test, making these other pathologies less likely causes of pain. Interestingly, the rates of Hill-Sachs lesions found in patients with apprehension only (49.6%) was higher than patients with who had pain (30.8%). This provided circumstantial evidence supporting our postulation that pain during the ABER maneuver might be protective against frank shoulder dislocations resulting in impaction fractures of the humeral head.
Furthermore, the proportion of patients with a preceding traumatic dislocating event in the group with a painful apprehension test was higher than the group with a purely apprehensive test (80.8% vs 69.9%), and the latter group was also nearly twice as likely to have ligamentous laxity than the former (14.8% vs 7.7%). This suggested a greater role of trauma, rather than ligamentous laxity, as the underlying etiology for patients with a painful “roll-over” lesion, with predominant symptoms of pain rather than instability. These associations were not statistically significantly and this is likely due to the underpowered nature of our study but they were certainly clinically relevant.
Boileau et al emphasized the importance of recognising UPS early in the young, hyperlax athlete complaining of deep, anterior shoulder pain as soft tissue or bony lesions indicative of instability may be found in the absence of an apparent history of shoulder subluxation or dislocation which were amenable to surgery with excellent outcomes . 20 patients were identified over a 5-year period with data collected prospectively, and followed up for a minimum of 2 years (mean 38 months, range 24–76 months). Abeit small numbers, the painful apprehension test was reproducible in all 20 patients (100%) involved, with 3 patients (15%) demonstrating both pain and apprehension with the test. 85% of patients in this group demonstrated purely painful apprehension tests. Apprehension alone was not elicited. Future studies to identify specific circumstances or in subgroups of patients with unique characteristics may be useful in increasing the specificity of this test for shoulder instability.
Numerous clinical tests have been developed to assess anterior shoulder instability. In van Kampen et al’s study of six of these clinical tests (apprehension, relocation, release, anterior drawer, load and shift, and hyperabduction tests) for traumatic anterior
shoulder instability, the relocation test was the most sensitive (96.7%), the anterior drawer test was the most specific (92.7%), and the release test showed the best overall accuracy (86.4%) , all of which were dependent on whether apprehension or pain was reproduced or relieved with the manouvre. Lafosse et al assessed instability by comparing of the range of motion in the abnormal shoulder with the normal side using the hyper extension-internal rotation (HERI) test . Isolated inferior gleno-humeral ligament (IGHL) section in the cadaveric arm of the study produced an mean increase of 14.5° in gleno-humeral extension, similar to their clinical arm of 50 patients with chronic unilateral anterior gleno-humeral instability when comparing the normal and abnormal sides . Although this test does not induce apprehension most of the time, allowing accurate measurements of the extension angles and assessments of gleno-humeral laxity, this test requires a normal contralateral shoulder for side-to-side comparison as a prerequisite. With no single clinical test being both highly sensitive and specific to date, using multiple clinical tests combined may be required to avoid underdiagnosing subtle shoulder instability and delayed treatment.
Instability of the shoulder can exist in the purely painful form, with or without a history of traumatic shoulder dislocation, recurrent dislocation or ligamentous laxity. Our study shows that the painful apprehension test is common in shoulder instability, particularly in patients presenting with pain as their main symptom despite a history of traumatic shoulder dislocation. These patients tend to have lower rates of recurrent dislocation but can achieve predictable, satisfactory outcomes with arthoscopic stabilisation of their bankart lesions.
The strengths of our study are: (i) having 2 fellowship-trained shoulder surgeons who work closely with each other ensures uniformity in clinical assessments, patient selection and quality of surgeries performed, thereby reducing the number of variables from poor standardization, and (ii) utilisation of multiple outcome measures provides a more holistic assessment. Our study limitations include: (i) the retrospective design of the study limiting collection of more comprehensive data, and (ii) relatively small sample size.