Treatment Strategies for Distal Clavicle Fractures: A Narrative Review

Introduction

Distal clavicle fractures, a common traumatic injury encountered in emergency rooms, account for approximately 10%–30% of all clavicle fractures and represent 2.6%–3.3% of all fractures.^1–3 Distal clavicle fractures typically result from direct or indirect trauma to the shoulder region. The most common injury mechanism reported was a simple fall (57%), followed by a high-energy fall (29%).⁴ Allman classified clavicle fractures into medial, distal, and proximal types based on the anatomic location.⁵ Among all clavicle fractures, those involving the distal segment are often controversial. Distal clavicle fractures are less common than medial clavicle fractures but are more susceptible to high non-union rate (10%-44%) compared with other subtypes, due to the combination of bony and ligamentous injury and the subsequent instability.⁶

The controversy between operative and non-operative treatments for distal clavicle fractures stems from differing perspectives on optimal healing outcomes, risk management, and patient-specific considerations. Multiple studies on distal clavicle fractures have emerged in recent years, and there is an urgent need to summarize these results to guide clinical decisions. In this review, we summarize the updated evidence comparing operative and non-operative approaches for distal clavicle fractures.

Anatomy and Classification

Understanding the precise anatomy and classification of distal clavicle fractures is essential for guiding treatment. The distal clavicle, which articulates laterally with the acromion forming the acromioclavicular (AC) joint, is anatomically thin and biomechanically vulnerable. Due to its structural characteristics, it is particularly susceptible to fractures when subjected to downward or compressive forces. Its vulnerability directly impacts the stability and function of the shoulder joint, influencing treatment decisions for distal clavicle injuries. The structures that maintain the stability of the AC joint include the AC capsule, the AC ligament, coracoclavicular (CC) ligaments, and coracoacromial (CA) ligaments⁷ (Figure 1). The horizontal stability of the AC joint is mediated by the AC ligament while vertical stability is mediated by the CC ligaments (ie the conoid and trapezoid ligaments).^8,9 However, the CC ligaments act as a substitute in resisting horizontal forces when the AC ligaments are ruptured.¹⁰

Figure 1 The composition of stability structures of acromioclavicular (AC) joint. (A) shows the clavicular structure under X-ray; (B) shows the related structures of the clavicular ligament on the cadaveric specimen. AC ligament contributes to vertical stability and coracoclavicular (CC) ligaments contribute to horizontal stability. The conoid and trapezoid ligaments compose of the CC ligaments.

In the 1960s, Neer et, al. categorized distal clavicle fractures based on the relationship between fracture line and CC ligaments on plain X-Ray radiographs, and over two decades later Craig et, al modified the Neer classification by considering two additional conditions, ie, periosteal sleeve avulsions and comminuted fractures.^11,12 Several classification systems for distal clavicle fractures have been described, including the AO classification, Jäger classification, Edinburgh classification, Cho classification, and Xue classification.^13–16 A summary of these classification methods is provided in Table 1. However, given the widespread use and validation, the modified Neer classification remains the preferred choice for guiding treatment and prognosis.

Table 1 The Classifications of Distal Clavicle Fracture

Radiographic Evaluation of Distal Clavicle Fractures

Standard radiographs, including anteroposterior, axial, and Zanca views, are essential for visualizing the fracture pattern, displacement, and comminution. The Zanca view, a specialized anteroposterior projection with 10–15 degrees of cephalic tilt, offers a clear image of the AC joint and distal clavicle, aiding in precise fracture classification.²⁰ Fractures are classified based on their location relative to the CC ligaments, the degree of displacement, presence of comminution, and intra-articular involvement. CT scanning provides better present better visual of shortening, displacement, and progression of union. MRI provides detailed evaluation of soft tissues and fracture stability, aiding accurate diagnosis and optimal treatment planning. However, MRI is not routinely indicated for all distal clavicle fractures but may be valuable in specific circumstances. Indications for MRI evaluation include: (1) suspicion of ligamentous injuries, particularly when clinical or radiographic findings suggest instability not clearly defined by plain radiographs,²¹ and (2) assessment of associated soft-tissue injuries, such as rotator cuff tears, labral tears, or capsular injuries.

Considerations and Complications of Surgical Treatment

Distal clavicle fractures may be treated conservatively or surgically, and the decision in their management is primarily centered around bone healing effectiveness, functional recovery, and complication risks. Generally accepted surgical indications for distal clavicle fractures include unstable fractures without bony contact and all open fractures involving skin compromise or associated neurovascular injury.^11,22,23

Neer type II and type V distal clavicle fractures are commonly recognized as indications for surgical treatment. Neer type II fractures are unstable due to detachment of the CC ligaments from the medial fragment, causing unstable displacement. Similarly, Neer type V fractures, characterized by comminution with only a small inferior fragment remaining attached to the CC ligaments, also demonstrate significant instability.²⁴ The primary benefit of surgical intervention is the direct anatomical reduction of the fracture, which can accelerate the bone healing process, facilitate earlier mobilization, and improve the appearance of the shoulder. Evidence reveals that the union rate of surgical intervention is 95%-98.6% for Neer types II and V distal clavicle fractures, significantly higher than that of conservative treatment (69%-70%).^25–28

Although numerous surgical techniques have been described, plate osteosynthesis using either a locking plate or a hook plate—with or without ligament reconstruction—remains the predominant approach. Currently, there is no consensus regarding the superiority of locking plates versus hook plates. A UK nationwide survey indicated a preference among most surgeons for locking plates (68%), while another nationwide review by Raval et al found greater utilization of hook plates (43%) compared to locking plates (21%).^4,29 Both locking plates and hook plates demonstrate high fracture union rates, but hook plates have a significantly higher complication rate (40.7%-76.6%) compared to locking plates (23.3%).^30,31 Additionally, hook plates are associated with inferior functional outcomes and a higher implant removal rate (86.9% versus 27% for locking plates).^30,32,33 One significant limitation of locking plate systems is the biomechanical requirement for a minimum distal fragment size of 10 mm to ensure secure fixation. This restricts their clinical applicability in fractures characterized by high comminution or osteoporotic bone, especially in periarticular regions where fragment sizes frequently fall below this threshold.³⁴

Conversely, hook plates provide robust mechanical stability by hooking beneath the acromion, allowing fixation of smaller lateral fragments and enhancing vertical stability in cases with associated AC joint dislocation.³⁵ Thus, hook plates have broader indications compared to locking plates. Hook plates also demonstrate lower incidences of AC joint subluxation and implant reduction loss.³⁶ However, hook plates carry substantial drawbacks. The hook frequently irritates subacromial structures, leading to a high incidence of acromial erosion (50%), subacromial impingement syndrome (37.5%), and potential rotator cuff injury (15%).³⁷ Therefore, routine hardware removal is required, making hook plates less suitable for individuals with high functional demands.

Other fixation methods include Kirschner wire fixation combined with CC repair, intramedullary screw fixation, interfragmentary suture fixation, and arthroscopic fixation employing cortical button coracoclavicular stabilization. Additionally, distal augmentation techniques such as distal wire augmentation are utilized.³⁸ These methods, either independently or in conjunction with traditional plate fixation, have demonstrated effectiveness in promoting bone union and reducing complication rates.^39–41

Considerations on Conservative Treatment

The operative approach has its drawbacks. A systematic review by Thurston et al reported complications in surgically treated patients, including implant-related pain (14.4%), hardware failure (2.1%), infection (2.1%), scar sensitivity (6.4%), wound issues (8%), nonunion (3.7%), and sensory deficits (2.7%). The overall complication rate was 41.2%, with a reoperation rate of 40.1%.⁴² Even for endoscopic treatment, two meta-analyses showed that the complication rate of arthroscopic intervention for distal clavicle fracture can be up to 27.4%-28.6%.^43,44 Additionally, there is an inherent risk associated with any surgical procedure, including reactions to anesthesia and the potential for blood loss. Therefore, the decision regarding surgical treatment should be made with caution, taking into consideration factors including age, activity level, comorbidities, and overall health of the patient.

If surgery can be avoided, patients with distal clavicle fractures may benefit from conservative treatment by reducing economic burdens and avoiding surgical complications. Most Neer types III and I distal clavicle fractures, and non-displaced Neer II distal clavicle fractures may be considered for initial conservative treatment.^6,45 However, whether the non-displaced Neer types II distal clavicle fractures should be conservatively or surgically treated remains controversial.⁴⁵

Recently, evidence has emerged that despite high non-union rate, nonoperative treatment achieves similar functional outcomes and strength to that of surgical procedures.^25,46–48 Additionally, the meta-analysis by Uittenbogaard et, al. showed that only half of the non-unions was symptomatic.⁴⁹ Nonunion in displaced distal clavicle fractures seems to cause minimal functional deficit in some populations, such as elderly sedentary individuals. A simple sling is sufficient for nonoperative management for two weeks for pain control of the fracture, and to initiate passive range of motion exercises simultaneously. Figure-of-eight bracing is not recommended.^50,51 Radiography may be conditionally repeated within 1 to 2 weeks if fracture stability is uncertain, and routinely repeated at 6 weeks for assessing bony union. Strengthening exercises can be incorporated into physical therapy if signs of radiographic union are captured.⁴⁵

We again emphasize that the choice between operative and non-operative treatment is influenced by patient-specific factors. Younger, more active patients or those with high functional or cosmetic demands might benefit more from surgical intervention due to the importance of quickly restoring function and appearance. In contrast, older patients or those with lower functional demands might be better candidates for non-operative treatment. Common complications of conservative treatment include symptomatic nonunion (15%), osteoarthritis (12%), and impingement syndrome (8%).⁴⁹

Conclusion

In summary, the management of distal clavicle fractures can be challenging because of difficulty in identifying potential fracture instability and balancing the risks and benefits of each approach, tailored to the individual patient’s needs. Ongoing studies and advancements in both surgical techniques and conservative management strategies continue to shape the landscape of treatment options, aiming to optimize outcomes for patients suffering from this common orthopedic injury.