Since the first description by Moskowitz and colleagues, numerous studies have been conducted to define the time of onset, the most appropriate diagnostic methods, and the pathophysiology of AWS.
Although many studies have contributed to underlining the importance of starting physiotherapy as early as possible once AWS has been diagnosed, there is still no unanimous consent regarding the most effective treatment, nor are there other studies that assess the efficacy of a rehabilitation protocol [6–8, 11–20]. Our study aim was to test the superiority of a manual treatment protocol compared with the established and standardized stretching exercises used for treatment of AWS.
As extensively described by many authors, one of the main symptoms of AWS is the reduction of shoulder ROM, especially during abduction [1, 8, 9]. Accordingly, patients enrolled in this study also presented with a reduction of shoulder ROM, as confirmed by the values measured at the beginning of the treatment (Table 2). After the treatment, SMM patients displayed a slightly higher abduction gain in comparison to ESS patients, with an average gain of 32.7° and 21.5° respectively. This therefore suggested that the additional manoeuvre might be associated with a higher efficiency; but these improvements were not statically significant. However, ROM values measured one month after the first treatment appeared to be very similar between the two groups, pointing to the possibility that the two management protocols might have the same efficiency over a longer time period. A reduction of ROM values was subsequently reported in both groups between the first and the second treatment sessions (8.9° for SMM group one and 8.1° for the ESS group). The possibility that the treatment undertaken at home was insufficient or not performed correctly, as well as the influence of still-ongoing AWS pathophysiological processes, might account for the reduced mobility observed in the patients between the two sessions. However, after the second session, all patients displayed a complete recovery of the shoulder ROM at the one-month follow-up.
Pain during shoulder movement appears to be another symptom caused by AWS [1, 30]. Indeed, pain reduction is intimately linked to the resolution of the syndrome. The SMM treatment did not lead to increased pain over the long term, despite being perceived as painful when performed (Table 3). Reduction of pain occurred in both groups with similar trends, allowing greater mobility to the affected upper limb (Table 2, Fig. 2). Importantly, after one month, a periodic follow-up aimed at assessing the AWS resolution in both groups was not performed in this study, but the three year follow-up did confirm that all patients had a complete regression of the syndrome.
Patients were subsequently re-examined three years after initial enrolment in order to evaluate the incidence of lymphedema in both groups, although previous studies had already ruled out that AWS and its management could be a risk factor for lymphedema . Accordingly, the results obtained in our cohort appear to be in line with that published in the literature  and show an incidence of lymphedema in 13% of the patients (Table 4), with no clinically and statistically significant differences between the two treatment groups. We therefore concluded that the additional SMM treatment does not represent a risk factor for lymphedema. Notably, the incidence of lymphedema increases to 33% when taking into account the data obtained with the TDC method, a method that allows detection of subclinical lymphedema in the absence of clinical manifestations and could be an additional assessment tool in the surveillance of BCRL overtime.
As our study is the first randomized clinical trial to assess the efficacy of protocol in this syndrome, certain weaknesses were present. Unfortunately, our research suffered somewhat from loss of patients to the follow-up examinations. A total of 6 patients of the SSE group could not be evaluated at the one month follow-up, but the more substantial loss occurred at our three year follow-up in which a total of 19 patients were lost. As this last follow-up was necessary to assess the incidence of lymphedema, the patients needed to be evaluated in our hospital and as some of them lived outside the region in which our hospital is located (Lombardy), we were unable to perform this second end point evaluation in these patients. Nevertheless our data is consistent with the published literature regarding the incidence of lymphedema after AWS treatment.
Another weakness arises from the lack of verification that the exercises were correctly (indeed, if at all) performed at home by the patients. As there is no valid instrument to assess compliance with our protocol, the data presented here were collected in good faith, under the assumption that all the patients complied correctly with the proposed program. Nevertheless, our research and the results bear relevance, especially in terms of assisting other institutions and physiotherapists how to address treatment options in these populations. Moreover, our study could represent an initial step to incentivize others to replicate our protocol or to study the effects in other ALND populations such as those who undergo surgery for sarcoma or melanoma, or patients with AWS after SLNB.
In conclusion, the addition of the manual snapping manoeuvre to a rehabilitation protocol may bring about an immediate improvement of shoulder mobility. However, it was not found to be better than a stretching exercise protocol overall. Whether or not to employ this technique to speed up recovery will be for the therapist to decide, safe in the knowledge that this manoeuvre does not appear to be a risk factor for lymphedema. Further studies are still warranted to compare the effectiveness of our protocol with other treatment methods.