Clavicle fractures nonunions were traditionally considered to be rare, with prevalence rates reported to be less than 1% by both Neer and Rowe [16, 17]. Surgical intervention at that time was believed to place patients at a greater risk of nonunion due to periosteal soft tissue stripping [16]. Fractures that have stable alignment and minimal soft tissue disruption typically progress to union and a normal return of function. A variety of techniques have been described for closed reduction of displaced clavicle fractures, but these have not demonstrated reliability in counteracting the deforming forces present and maintaining reduction [4, 18]. Recent studies have demonstrated a nonunion rate of 25%, which is higher than previously reported [3] (Fig. 14.2a–d).

A variety of risk factors can inhibit clavicle healing but typically involve high energy mechanisms in a young active population. These fractures are typically comminuted and displaced, which are risk factors associated with the development of nonunion, and can result in the disruption and possible interposition of surrounding soft tissues [3, 9, 18]. Zlowodzki et al. performed a systemic review on acute midshaft clavicle fractures and reported an overall nonunion rate of 5.9%; in the subset of clavicle fractures with displacement, the risk of nonunion increased nearly threefold to 15.1% [19]. Operative treatment of these fractures with either plate osteosynthesis or intramedullary fixation resulted in a reduction in relative risk of fracture nonunion. Robinson et al. found that patients with displaced, comminuted midshaft clavicle fractures had a nonunion rate of 21% in young males [9]. The risk of nonunion has been demonstrated by meta-analysis to be reduced with the use of plate fixation for primary treatment (15.1% vs. 2.2%) and the higher incidence in nonunion from earlier studies may have been the result of improper fixation techniques and selection of operative intervention on more severe fracture patterns [19]. Both plate fixation and intramedullary fixation have demonstrated improved union rates as compared to nonoperative management of clavicle fractures [20, 21]. Studies comparing these fixation techniques though have not demonstrated any difference in both short- and long-term functional outcomes, as well as no difference in the ability to obtain union for displaced, non-comminuted fractures [13].

The location of clavicle fractures can also affect bone healing with a higher incidence of nonunions reported in distal third clavicle fractures [22]. Distal clavicle fractures typically occur as the result of high energy trauma in a younger population or a fall from height in elderly patients. These fractures were originally classified by Neer into three types by the relationship of the fracture line to the coracoclavicular (CC) ligaments. Type I and III fractures are lateral to these ligaments, typically involve only minimal displacement, and are treated conservatively with a sling. Type II fractures though leave the ligaments attached to the distal fragment and result in an unopposed trapezial muscle force displacing the medial fragment proximally while the distal fragment is counteracted by the weight of the arm [23]. Indications for surgical treatment are based on stability of CC ligaments, fracture displacement, and patient age. Although elderly patients are at risk for nonunion, they are typically asymptomatic and do not require treatment. Injuries in younger patients though are the result of severe trauma and reduction can be difficult to maintain without surgical intervention. This can result in pain and reported rates of nonunion following conservative treatment as high as 44% [22]. If sufficient bone is present laterally, then fixation can be accomplished with plate fixation. If the fracture pattern or bone quality precludes distal fixation, then fracture stability can be obtained with concurrent CC ligament fixation . Hook plates have also been described as a possible fixation option but have been associated with subacromial erosion, rotator cuff tears, periprosthetic fractures, implant failure and require a secondary procedure for removal following bony union [24, 25].

Nonunions can be confirmed by failure to show radiographic progression of healing at 4–6 months. The ends of the bone may demonstrate atrophic, eutrophic, or hypertrophic changes that are confirmed by computed tomography to lack bridging callous. Clinically, nonunions can result in pain, restriction of movement, weakness, cosmetic deformity, neurologic symptoms, and thoracic outlet syndrome. The patients may have crepitus or prominence at the fracture site and neurovascular symptoms of the ipsilateral extremity due to abundant callous formation or fracture displacement. Fracture nonunion can have a significant effect on quality of life and daily activities and can be treated with internal fixation and bone grafting (Fig. 14.3a–c).

Maintaining reduction of clavicle fractures through conservative management can be difficult and a certain amount of deformity is to be expected due to the unequal distribution of forces placed on the fracture fragments. Patients who are skeletally mature are unable to remodel these deformities and the final fracture reduction will remain unchanged. Depending on the amount of displacement of the fracture, varying degrees of shortening and angulation can be visualized on radiographs but was originally thought to be of radiographic interest only with no major residual impairment [4]. The typical malunion pattern can be complex, effecting the clavicle three dimensionally and resulting in the lateral fragment being inferior, medially translated, and anteriorly rotated in relation to the medial shaft [26] (Fig. 14.4a–d).

Recent studies have countered conventional opinion and have demonstrated that functional outcomes may be adversely impacted by a malunion [27]. Specifically, long-term follow-up studies have revealed complications such as chronic pain, brachial plexus impingement, weakness, and cosmetic dissatisfaction [3, 4, 28]. Hill et al. reported that 31% of 52 patients had unsatisfactory results following evaluation of clavicular malunions and that fractures with greater than 2 cm of shortening were more likely to have a poor outcome [3]. Mckee et al. reported diminished patient-reported outcome scores, as well as significant reduction in strength with objective muscle strength testing, most notably arm abduction, and increased fatigability following nonoperative treatment when clavicle fractures healed with shortening [4]. Clavicle shortening can alter the scapular–humeral relationship, resulting in a decrease in the length–tension relationship of the muscle-tendon unit and producing scapular dyskinesis with diminished mechanical efficiency of the shoulder girdle muscles [3] (Fig. 14.5a–d). This has been correlated by increased displacement or shortening demonstrating worse subjective outcome scores and a higher prevalence of patient dissatisfaction [3, 4, 6]. Corrective osteotomy with internal fixation and bone grafting can restore clavicular length and result in improvement of subjective outcome scores and patient satisfaction (Fig. 14.6) [7, 18, 23, 29]. Due to the complex deformity that may be present and proximity to vascular structures, preoperative evaluation of vascular structures with imaging should be considered and the presence of a vascular or thoracic surgeon should be requested.

The proximity of the clavicle to neurovascular structures makes a thorough examination of the affected extremity necessary to rule out additional injuries [30, 31]. Fractures that result in posterior displacement of the medial aspect of the clavicle can injure the major vessels located posterior to the mediastinum. Computed tomography of the chest should be obtained to evaluate traumatic medial clavicle injuries due to its rapid availability. This situation is rare but does require urgent operative intervention with the assistance of a cardiothoracic surgeon [32, 33]. For patients who are under the age of 21 or still skeletally immature, an MRI should be obtained to distinguish between a physeal injury and sternoclavicular dislocation [45].

Fractures of the shaft that have significant deformity or abundant callous formation can place pressure on either the brachial plexus or subclavian vessels in the costoclavicular space [10, 30]. The subclavian vessels can be compressed between the clavicle and the first rib, resulting in thoracic outlet syndrome. Injuries to the brachial plexus can occur from early traction injuries or develop from late compression neuropathies from atrophic nonunion. Intraoperative neurologic injury can also result from drill penetration, retractors, excessive fracture mobilization or with intramedullary fixation [11]. The diagnosis of neurovascular injury can be identified by physical examination and history and aided by electromyography, nerve conduction velocities, and advanced imaging such as MRI.

Various techniques have been reported for clavicle fracture fixation but the most common surgical options currently utilized are either plate or intramedullary fixation [34]. Intramedullary fixation was developed as an alternative to traditional plate fixation and offers several advantages including a cosmetically favorable incision, minimal disruption of the periosteum, and diminished hardware prominence [35, 36]. Various intramedullary implants have been described, including pins (Hagie, Knowles, Rockwood) and titanium elastic nails [16, 37]. Despite the proposed advantages, these implants have been associated with pin migration, pin breakage, cortical perforation, superficial and deep infections, refracture following pin removal, hardware prominence, and skin erosion from pin exposure [16]. Studies have also demonstrated inferior biomechanical properties for rotational and torsional strength with intramedullary fixation when compared to plate fixation which can potentially result in hardware failure , nonunion, or malunion [33, 37, 38]. These complications have been reduced with improved modern implant designs that allow load sharing fixation and promotion of callous formation, as well as increased surgeon experience with these implants.