Shoulder dislocations are common events in the medical emergency setting, with anterior dislocation being the most prevalent, accounting for approximately 80-97% of all cases. ^{1 , 2} These dislocations, where the humeral head is displaced in front of the glenohumeral joint, typically cause severe pain, and restricted movement, and can significantly impact the patient’s quality of life.

A glenohumeral joint, known for its wide range of motion, is prone to dislocations, occurring at an annual rate of 11 to 51 per 100,000 people. These dislocations often result in chronic instability, with over 50% of cases experiencing recurrent episodes. ³ Traumatic dislocations can cause structural injuries like Bankart and Hill-Sachs lesions, leading to recurrence rates of anterior shoulder instability as high as 85 to 92%. ^{2 , 4}

Hill-Sachs lesions are bone defects of the humeral head typically associated with anterior shoulder instability. The incidence of these lesions in the context of glenohumeral instability is high, approaching 100% in individuals with recurrent anterior shoulder instability. ⁴ Recurrences of glenohumeral dislocation cases are commonly associated with glenoid injuries, including both osseous-cartilaginous and labral lesions known as Bankart lesions, as well as impaction lesions of the humeral head, Hill-Sachs lesions. ^{3 , 4}

The treatment of acute shoulder dislocation depends on various factors, including subjective and objective findings of instability, radiological results, and individual patient considerations. ^{3 , 4} Surgical intervention is recommended in specific cases, such as recurrent dislocations, significant Hill-Sachs lesions, or in young athletes engaged in high-risk sports. ^{3 , 4}

Following dislocation reduction, non-surgical management includes rehabilitation, which can involve a variety of interventions, including thermal modalities, electrophysical resources, manual therapy, kinesiotherapy, and guidance. ⁵ Photobiomodulation therapy (PBM) using lasers and LEDs has been employed to promote healing, alleviate pain, and reduce inflammation in musculoskeletal conditions. ^{6 – 10}

Studies highlight the beneficial effects of Photobiomodulation (PBM) on the bone repair process and cellular regeneration. ^{6 – 8} However, there is a lack and controversy in clinical trials presenting protocols for fracture and/or dislocation treatment with PBM. Therefore, the main objective of this study is to outline the case of a patient presenting with acute traumatic anterior shoulder dislocation concomitant with a Hill-Sachs lesion, who received a conservative treatment regimen incorporating the PBM using the low-level Laser.

The methodology of this case study was approved by the Ethics Committee for Research in Human at UNINOVE (6.296.665), and the patient consented to participate by signing a written Informed Consent Form (ICF), and the study adheres to the Declaration of Helsinki. Additionally, consent to publish the details has been obtained from the patient. Patient A. Q, a 48-year-old male with a regular physical activity routine, experienced a fall from a 1.5-meter height while skateboarding. This fall resulted in intense pain, deformity, and restricted movement in his right arm. He received immediate assistance and was referred for hospital care on February 1, 2020.

The initial physical examination at the hospital revealed severe pain, limited range of motion (ROM) in the shoulder, and the presence of the military crest sign, indicating a loss of the rounded contour of the shoulder due to humeral head displacement. The patient was clinically diagnosed with acute traumatic anterior shoulder dislocation of the right shoulder, and closed reduction of the dislocation was performed in the emergency department.

Following the closed reduction of the dislocation, a Magnetic Resonance Imaging (MRI) study was conducted, revealing findings consistent with a Hill-Sachs lesion, characterized by impaction of the humeral head, bone contusion and edema, rupture of the joint capsule and inferior glenohumeral ligament, and anteroinferior glenoid labral tear (Bankart lesion), suggestive of associated ligamentous injuries ( Figure 1A and B). The T2-weighted MRI image highlights the bony shoulder lesion (hyperintensity), Hill-Sachs fracture with deformity and impaction of the humeral head in the posterosuperior and lateral region, bone contusion and edema represented by the yellow arrow ( Figure 1A). This examination also revealed hyperintensity at the anteroinferior glenoid labrum, suggesting a tear, along with a moderate glenohumeral joint effusion with fluid extravasation into the arm, related to the capsule and inferior glenohumeral ligament rupture.

The orthopedic physician in charge of the patient immobilized the patient’s shoulder with a sling for 10 days and initiated conservative treatment using only Photobiomodulation (PBM) with Low-Level Laser Therapy (LLLT) on the same day. Considering that the patient in the study was undergoing treatment for nephropathy, with a contraindication for the use of any anti-inflammatory medication for pain control, only Dipyrone was prescribed at a dose of 1g every 6 hours orally if the pain was not fully controlled with PBM using a laser cluster.

PBM treatment began on the first day, the day of the accident, and continued with daily applications for 30 days. After the initial 30 days, the PBM protocol continued with twice-weekly applications for 33 months. The PBM was consistently performed by the same healthcare professional using the Quantum Laser Cluster IV - a Phototherapy device by Ecco Fibras (São Paulo, Brazil), for irradiation in three different positions, as shown in Figure 1C, D and E.

The irradiation was in continuous mode, wavelength of 808 nm, power of 120 mW, irradiance of 120 mW/cm ², beam spot of 1 cm ², exposition time of 42 s, radiant exposition 5 J/cm ², 4 lasers in the cluster and a total of 3 regions irradiated being the total radiant energy of 60 J in each session.

The patient’s right shoulder remained immobilized in a sling for ten days. Starting from the 11th day, he began moving his right upper limb only for performing daily tasks, without engaging in any sports activities for the first 30 days.

This present study describes a case of a physically active patient who suffered an acute anterior shoulder dislocation with associated Hill-Sachs and Bankart lesions from a skateboarding accident. After a successful closed reduction, the patient started a conservative treatment with PBM using a LLL cluster. Although there is no existing literature on this particular treatment approach, several studies indicate that PBM shows promise in the field of regenerative medicine, offering benefits such as pain reduction, swelling and inflammation mitigation, and acceleration of the bone and joint repair process ^{6 – 10}

Generally, PBM is often combined with other forms of therapy and rehabilitation. ⁶ In this study, due to the COVID-19 pandemic restrictions and the patient’s contraindication for anti-inflammatory medication due to nephropathy, conservative treatment with PBM using LLL was chosen for rehabilitation. The patient had a complete adherence to the conservative treatment with no adverse effects receiving daily PBM with LLL for the first 30 days after the accident, followed by twice-weekly treatments for 33 months. Within the initial 30 days, there was a gradual improvement in pain, and by the end of this period, the patient had fully regained limb functionality, was pain-free, and showed no signs of swelling or hematomas. Imaging exams conducted on the 28th day revealed a bone healing process without edema or bone loss in the glenoid joint facet ( Figure 1F and G), which had been evident in the initial imaging exams taken on the day of the accident ( Figures 1A and B).

During a 33-months eleven-days follow-up, the patient experienced no shoulder instability or pain and regained full functionality for daily and sports activities. Clinical shoulder mobility assessments ( Table 1) and imaging exams ( Figure 1H and I) performed at this point indicated the complete healing of the Hill-Sachs lesion and significant repair of the Bankart lesion. PBM using LLL therapy played a crucial role in achieving this successful rehabilitation by reducing inflammation, managing pain, controlling edema, promoting tissue regeneration, and expediting the healing process, as previously documented in the literature ^{7 – 10} PBM is associated with several mechanisms of action, including increased production of endogenous opioids, neurotransmitters, elevated thermal pain threshold, improved local blood circulation, changes in oxygen consumption, enhanced cellular ATP production, and the production of anti-inflammatory cytokines. Light emitted during irradiation can interact with cytochrome c oxidase, a mitochondrial enzyme, leading to increased ATP production, reduced reactive oxygen species levels, and aiding in inflammation reduction and cell survival. ^{7 , 8} In this case report, PBM using LLL appeared to stimulate bone regeneration, particularly in addressing Hill-Sachs lesions, which are typically associated with glenoid bone loss. This treatment may have contributed to maintaining joint stability and reducing the risk of shoulder dislocation recurrence. Additionally, Hill-Sachs lesions can limit shoulder mobility due to bone deformity, impacting range of motion, especially internal rotation and arm abduction. Such limitations can affect shoulder function and mobility and increase the long-term risk of joint degeneration. ^{1 , 2 , 4} However, in this study, the patient recovered shoulder ROM, as evidenced by the results in Table 1, and did not experience recurrent dislocations after PBM using LLL treatment.

Therefore, it is plausible that PBM stimulated bone cell activity, including osteoblasts responsible for bone formation and osteoclasts responsible for bone resorption. ^{9 , 10} This potential stimulation might have accelerated the bone repair process while reducing inflammation and edema, as illustrated in Figure 1. Additionally, it is suggested that PBM may have expedited callus formation. Light has been shown to activate bone cells, increasing collagen production and promoting cell differentiation, resulting in faster bone consolidation. ^{9 , 10}

In summary, PBM with LLL had positive effects on inflammation, pain, and edema management in both acute injury and rehabilitation phases, supporting shoulder regeneration and functional recovery. These benefits are linked to increased collagen synthesis, growth factor production, and pain relief. PBM also aids in tissue repair processes by enhancing local vascularization. While this study showcased the effectiveness and safety of using photobiomodulation as the primary rehabilitation strategy for acute traumatic anterior shoulder dislocation with Hill-Sachs and Bankart lesions, it’s important to note that this is a single case report, and further research is needed to bolster the evidence.

All listed authors should have contributed to the manuscript substantially and have agreed to the final submitted version