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AC Joint Stabilisation

Surgical reconstruction for high-grade AC joint dislocation (Rockwood III-VI).

Overview

AC joint separation is a common injury, typically caused by direct trauma from a fall on the point of the shoulder, resulting in progressive ligamentous disruption from the capsular ligaments to the coracoclavicular (CC) ligaments [4]. Clinical presentation includes localized bruising, swelling, and tenderness, with higher-grade injuries marked by distal clavicle prominence [4]. Diagnosis requires evaluation of the sternoclavicular joint, neurologic status, and scapular kinematics, alongside plain radiographs including AP, caudal tilt, and axillary views to assess for posterior translation and normal CC distances of 11 to 13 mm [4]. Weighted views may distinguish Type II from Type III injuries but are rarely indicated [4].

Management is stratified by injury grade: Type I and II injuries are treated nonsurgically with sling immobilization followed by gradual rehabilitation, yielding full function in 4 to 6 weeks but carrying a risk of residual pain in 30% to 50% of young, active patients [4]. Type III management is controversial; while nonsurgical treatment offers quicker recovery and fewer complications, surgical intervention is considered for younger, active patients, manual laborers, or those with horizontal instability (Type IIIB) or displacement exceeding 2 cm [4]. Type IV, V, and VI injuries generally require acute surgical stabilization due to irreducible deformity and the high likelihood of substantial residual pain with nonoperative care [4].

Surgical outcomes for high-grade dislocations are supported by techniques such as anatomic CC/AC reconstruction, which provides superior stability compared to CC-only fixation [9]. Arthroscopic approaches offer satisfactory long-term results with reduced morbidity and cosmetic benefits, though mechanical failure rates of approximately 16% have been reported [3, 24]. Early surgical intervention (within 3 to 4 weeks) allows for reliable CC ligament healing without graft augmentation if adequate reduction is achieved [4].

Anatomy & Pathophysiology

AC joint separation is a common injury constituting 9% of shoulder injuries, typically resulting from direct trauma via a fall on the point of the shoulder, while indirect mechanisms are rare [4][26]. Younger, physically active athletes, particularly those in contact sports, extreme sports, skiing, and cycling, face increased risk [26]. The injury initiates with capsular ligament disruption, progressing to the coracoclavicular (CC) ligaments [4]. Normal CC distance between the superior coracoid and inferior clavicle measures 11 to 13 mm on AP radiographs [4][18].

Rockwood Classification: * Type I: AC ligament sprain with intact CC ligaments and normal radiographic CC distance [4]. * Type II: Complete AC ligament rupture with sprained but intact CC ligaments, normal radiographic CC distance, AC joint widening, and CC distance increase <25% compared to the contralateral shoulder [4][17]. * Type III: Disruption of both AC and CC ligaments with increased CC distance and superior clavicle displacement up to 100% of clavicle width; CC distance increases 25% to 100% compared to the contralateral shoulder [4][17]. A modification proposes Type IIIA (horizontally stable) and Type IIIB (horizontally unstable) [4]. * Type IV: Disruption of AC and CC ligaments with posterior clavicle displacement, increased CC distance, and herniation of the distal clavicle into or through the deltotrapezial fascia; diagnosed when the distal clavicle is displaced posteriorly into the trapezius muscle [4][17]. * Type V: Disruption of AC and CC ligaments with >100% superior clavicle displacement, markedly increased CC distance (100% to 300% compared to contralateral shoulder), and deltotrapezial fascia disruption, potentially causing skin tenting [4][17]. * Type VI: Rare injury involving inferior clavicle displacement into the subcoracoid space, where the distal clavicle lies under the acromion or coracoid process [4][17].

Horizontal plane stability is provided by the AC ligaments, specifically the posterior and superior portions [18]. Large kinematic differences exist between the intact state and a Rockwood V lesion during humerothoracic and scapulothoracic movements in both clinical and cadaveric models [42][44]. Scapular dyskinesis is associated with inferior results in AC joint injuries [47]. The scapular-based V angle on anteroposterior radiographs distinguishes between Rockwood types III and V while considering dynamic horizontal translation in coronal radiographs [56]. Coracoid position relative to the lateral clavicle edge correlates most strongly with clavicle length [52].

Osteoarthritis of the AC joint is more common with advanced age following intra-articular disk degeneration, starting in early middle age [18]. It is more prevalent in patients engaged in repetitive overhead or lifting activities and can result from previous low-grade AC joint separations [18]. Distal clavicle osteolysis involves localized hyperemia, inflammation, bone resorption, microfractures, and secondary arthritis; it is more common in males, younger patients, and those associated with heavy lifting or repetitive motions [18].

Biomechanically, the pectoralis minor tendon provides sufficient tissue length, excursion, and width for AC joint reconstruction and is as strong as the coracoacromial ligament [38]. Coracoclavicular ligament reconstruction using the pectoralis minor tendon demonstrates strength comparable to the coracoacromial ligament [38]. Anatomic AC joint reconstructions are biomechanically superior to nonanatomic techniques such as the Weaver-Dunn procedure [18]. ST CC ligament reconstruction demonstrates biomechanical properties comparable to the intact state [51]. Independent AC ligament repair, disregarding routine CC reconstruction, demonstrated significant translational stability in anterior–posterior and superior–inferior planes, restoring stability comparable to native ligaments [31]. The transacromial technique showed the most translation and rotation compared to other methods [7]. The CE and TR techniques led to similar biomechanical performances in AC joint reconstruction [43]. All four construct groups in a study of suspensory fixation with internal brace demonstrated biomechanical noninferiority regarding dynamic creep, translation, displacement, or stiffness [40]. Biomechanical testing of two suspensory cortical button fixation constructs showed similar fixation stability after cyclical axial loading and similar loads to failure [55]. Side-to-side suturing provides equivalent initial biomechanical strength compared with interference screw fixation for graft fixation in AC joint reconstructions [54].

Classification

Rockwood Classification: This system classifies AC joint separations based on ligamentous disruption and clavicular displacement, initially defined in 1963 to include types I, II, and III, and expanded in 1984 to include types IV, V, and VI [17]. Type I: Involves an AC ligament sprain with intact CC ligaments, normal radiographic CC distance, and no AC joint widening or clavicular displacement [4][17]. Type II: Involves AC ligament rupture and sprained but intact CC ligaments, resulting in a normal radiographic CC distance, widening of the AC joint, and an increase in CC distance by less than 25% compared with the contralateral shoulder [4][17]. Type III: Involves disruption of the AC and CC ligaments, increased CC distance (25% to 100% compared with the contralateral shoulder), and superior displacement of the clavicle of up to 100% of the clavicle width; the deformity is reducible [4][17]. A modification of Type III injuries has been proposed consisting of Type IIIA (horizontally stable) and Type IIIB (horizontally unstable) [4]. Type IV: Involves disruption of the AC and CC ligaments with posterior displacement of the clavicle, which is herniated into or through the deltotrapezial fascia; the deformity is not reducible [4][17]. Type V: Involves disruption of the AC and CC ligaments with greater than 100% superior displacement of the clavicle due to disruption of the deltotrapezial fascia, characterized by a markedly increased CC distance and tenting of the overlying skin; the deformity is usually not reducible [4][17]. Type VI: Involves disruption of the AC and CC ligaments with inferior clavicle displacement, where the distal clavicle lies under the acromion or coracoid process; these injuries are rare [4][17].

Other Considerations: Rockwood Type III is the most common type of AC joint dislocation, constituting 55.7% of injuries [39]. The Kraus system was slightly more reliable than the Rockwood system for classifying AC joint injuries both between assessor groups and overall [37]. Plain radiographs for AC joint evaluation include an AP view of the clavicle, a caudal tilt view, and an axillary view to rule out posterior translation of the distal clavicle [4]. In a normal AC joint, the anterior aspect of the clavicle should lie in the same plane as the anterior aspect of the acromion, and the normal coracoclavicular distance between the superior aspect of the coracoid and the inferior clavicle should be between 11 to 13 mm [4]. A Zanca view is a modified, underpenetrated AP view with a cephalic tilt of 10° to 15° that gives excellent detail of the distal clavicle [4]. Weighted views include bilateral AP views with weights tied to the wrists in relaxed standing; they help distinguish between type II and type III separations but are rarely indicated and often not clinically helpful [4]. A fracture of the base of the coracoid process should be ruled out as it can result in superior displacement of the clavicle with an intact CC distance [4]. Ninety-one percent of patients with acute AC joint dislocation Rockwood Type III and V recovered without surgery, with no differences in outcome scores between Type III and V at any time point [45].

Clinical Presentation

AC joint separation is a common injury with an unknown incidence, typically resulting from direct trauma via a fall on the point of the shoulder [4]. Indirect injuries are rare [4]. The mechanism initiates progressive ligamentous disruption, beginning with capsular ligaments and advancing to the coracoclavicular (CC) ligaments [4]. Acute presentations feature localized bruising, swelling, and tenderness [4]. The sternoclavicular joint must be evaluated for swelling, deformity, and tenderness [4]. A complete neurologic examination of the upper extremity is required to rule out brachial plexus injuries [4].

Inspection and Palpation: Higher grade injuries manifest as prominence of the distal clavicle [4]. Scapular dyskinesis may be present and requires careful assessment of scapular motion [4]. In chronic AC joint injuries, range of motion and rotator cuff strength are typically normal, though limited in acute cases secondary to pain [4]. Patients with osteoarthritis report activity-related pain localized to the AC joint, occasionally radiating anteriorly or along the trapezius [18]. Pain with heavy lifting or sleeping on the affected side is common in osteoarthritis [18]. Point tenderness is seen at the AC joint in osteoarthritis [18]. Distal clavicle osteolysis presents with localized pain, swelling, and tenderness similar to symptomatic AC joint arthritis [18].

Stability and Special Tests: The ability to reduce the deformity with manual pressure helps differentiate nonsurgical versus surgical treatment in higher grade injuries [4]. Horizontal plane translation of the distal clavicle should be assessed manually and compared with the opposite shoulder [4]. Horizontal stability is provided by the AC ligaments, specifically the posterior and superior portions [18]. Selective injection of anesthetic into the AC joint can confirm the diagnosis of osteoarthritis [18].

Imaging: Plain radiographs include an AP view of the clavicle, a caudal tilt view, and an axillary view [4]. An axillary view is necessary to rule out posterior translation of the distal clavicle [4]. In a normal shoulder, the anterior aspect of the clavicle lies in the same plane as the anterior aspect of the acromion [4]. The normal CC distance between the superior coracoid and inferior clavicle is 11 to 13 mm [4]. A Zanca view is a modified, underpenetrated AP view with a cephalic tilt of 10° to 15° providing excellent detail of the distal clavicle [4]. Weighted views include bilateral AP views with weights tied to the wrists in relaxed standing [4]. These views help distinguish between type II and type III separations but are rarely indicated and often not clinically helpful [4]. Radiographs for osteoarthritis include an AP view and/or a Zanca view [18]. Osteophyte formation, sclerotic reaction, and bone cysts are common radiographic findings in osteoarthritis [18]. Bone and joint edema on MRI correlate with AC joint pain [18].

Acute Injury Classification

The Rockwood classification was initially defined in 1963 to include types I, II, and III [17] and expanded in 1984 to include types IV, V, and VI [17]. Type I involves an AC ligament sprain with intact CC ligaments and normal radiographic CC distance [4]. Type II involves AC ligament rupture with sprained but intact CC ligaments and normal radiographic CC distance [4]; it consists of complete AC rupture, CC sprain, AC widening, and a CC distance increase of less than 25% compared with the contralateral shoulder [17]. Type III involves disruption of AC and CC ligaments with increased CC distance and superior clavicle displacement up to 100% of the clavicle width [4]; the AC joint is widened and CC distance increases 25% to 100% compared with the contralateral shoulder [17]. The deformity in type III injuries is reducible [4]. A modification proposes type IIIA (horizontally stable) and type IIIB (horizontally unstable) [4]. Type IV involves disruption of AC and CC ligaments with posterior clavicle displacement into the trapezius muscle [17]; the distal clavicle is herniated into or through the deltotrapezial fascia [4]. The deformity in type IV injuries is not reducible [4]. Type V involves disruption of AC and CC ligaments with greater than 100% superior clavicle displacement [4]; it is characterized by a markedly increased CC distance [4] and increased CC distance by more than 100% compared with the contralateral shoulder due to deltotrapezial fascia disruption [17]. Tenting of the overlying skin can result in type V injuries [17]. The deformity in type V injuries is usually not reducible due to herniation through the deltotrapezial fascia [4]. Type VI involves disruption of AC and CC ligaments with inferior clavicle displacement into the subcoracoid space [17]; these are rare, resulting in the distal clavicle lying under the acromion or coracoid process [4], with only 24 cases reported to date [28]. A fracture of the base of the coracoid process must be ruled out as it can cause superior clavicle displacement with an intact CC distance [4]. Authors recommend grading acute AC joint lesions by digital measurement rather than visual diagnosis due to higher intra- and interobserver reliability [27].

Chronic Arthropathy and Osteolysis

Osteoarthritis of the AC joint is more common with advanced age following degeneration of the intra-articular disk [18]. Arthritic deterioration starts in early middle age [18]. AC joint osteoarthritis is more common in patients engaged in repetitive overhead or lifting activities [18]. Previous low-grade AC joint separations can result in painful arthritis [18]. The radiographic severity of AC joint arthritis does not always correlate with patient symptoms [18]. Pain at the AC joint with terminal elevation and cross-body motion is often seen in osteoarthritis [18]. Horizontal stability should be assessed in patients with AC joint osteoarthritis [18]. Distal clavicle osteolysis is more common in males [18], seen in younger patients [18], and associated with heavy lifting or repetitive motions [18].

Investigations

Plain radiography: Evaluation begins with an AP view of the clavicle, a caudal tilt view, and an axillary view [4]. An axillary view is essential to rule out posterior translation of the distal clavicle; in a normal view, the anterior aspect of the clavicle lies in the same plane as the anterior aspect of the acromion [4]. A Zanca view, a modified underpenetrated AP view with a 10° to 15° cephalic tilt, provides excellent detail of the distal clavicle [4]. Weighted views, consisting of bilateral AP views with weights tied to the wrists in relaxed standing, help distinguish between type II and type III separations but are rarely indicated and often not clinically helpful [4]. The normal coracoclavicular (CC) distance between the superior aspect of the coracoid and the inferior clavicle should be between 11 to 13 mm [4]. A fracture of the base of the coracoid process must be ruled out as it can result in superior displacement of the clavicle with an intact CC distance [4]. For osteoarthritis evaluation, an AP view and/or a Zanca view provides good visualization, revealing osteophyte formation, sclerotic reaction, and bone cysts [18].

Classification and Clinical Correlation: Higher grade AC joint injuries result in prominence of the distal clavicle [4]. Type I injuries involve an AC ligament sprain with intact CC ligaments and normal radiographic CC distance [4]. Type II injuries involve AC ligament rupture with sprained but intact CC ligaments and normal radiographic CC distance [4]. Type III injuries involve disruption of the AC and CC ligaments characterized by increased CC distance and superior displacement of the clavicle of up to 100% of the clavicle width [4]. A modification of type III injuries proposes type IIIA (horizontally stable) and type IIIB (horizontally unstable) [4]. Type IV injuries involve disruption of the AC and CC ligaments with posterior displacement of the clavicle, increased CC distance, and a deformity that is not reducible [4]. Type V injuries involve disruption of the AC and CC ligaments with greater than 100% superior displacement of the clavicle, a markedly increased CC distance, and a deformity usually not reducible due to herniation through the deltotrapezial fascia [4]. Type VI injuries involve disruption of the AC and CC ligaments with inferior clavicle displacement, where the distal clavicle lies under the acromion or coracoid process [4]. RW type VI AC dislocations remain exceedingly rare, with only 24 cases reported to date [28].

Physical Examination: Localized bruising, swelling, and tenderness are present in acute AC joint injuries [4]. The sternoclavicular joint should be evaluated for swelling, deformity, and tenderness during AC joint examination [4]. Range of motion and rotator cuff strength are typically normal in chronic AC joint injuries but may be limited in acute injuries secondary to pain [4]. The ability to reduce the deformity with manual pressure is important for differentiating nonsurgical versus surgical treatment in higher grade AC joint injuries [4]. Horizontal plane translation of the distal clavicle should be assessed manually and compared with the opposite shoulder [4]. A complete neurologic examination of the upper extremity should be performed to rule out brachial plexus injuries in AC joint trauma [4]. Scapular motion should be carefully assessed as scapular dyskinesis can be seen with AC joint injuries [4]. For osteoarthritis, examination findings include point tenderness at the AC joint, pain with terminal elevation and cross-body motion, and activity-related pain localized to the AC joint with occasional radiation anteriorly or along the trapezius [18]. Pain with heavy lifting or when sleeping on the affected side is reported in AC joint osteoarthritis [18]. Horizontal stability should be assessed in patients with AC joint osteoarthritis [18]. Selective injection of anesthetic into the AC joint can confirm the diagnosis of AC joint osteoarthritis [18].

Other Considerations: The authors recommend grading acute AC joint lesions by performing a digital measurement instead of a sole visual diagnosis due to higher intra- and interobserver reliability [27]. Bone and joint edema on MRI correlate with AC joint pain [18].

Treatment

Non-Operative

Nonsurgical management is the first-line treatment for Rockwood type I and II AC joint injuries, utilizing an arm sling for immobilization and pain control [19]. The sling is typically worn for approximately 1 week in type I injuries and 2 to 3 weeks in type II separations [19]. Most patients regain full shoulder function within 4 to 6 weeks, though 30% to 50% of young, very active patients may experience mild to moderate residual pain at the AC joint [4]. Patients with type I or II injuries are at increased risk for painful AC joint arthritis and osteolysis of the distal clavicle [4, 30]. Retrospective studies report persistent symptoms in up to 40% to 50% of patients at 1, 6, and 10 years after type I and II injuries, with 27% eventually undergoing surgical intervention at a mean of 26 months [19]. Distal clavicle resection can provide a solution for persistent inflammation or osteoarthritis following these injuries [19].

For Rockwood type III injuries, the initial management is controversial, though a 2007 survey indicated 86.3% of members preferred an initial trial of nonsurgical management for uncomplicated cases [19]. Meta-analyses and systematic reviews demonstrate similar outcomes for type III separations managed nonsurgically versus surgically, with nonsurgical treatment resulting in quicker recovery and return to work [4, 19]. A prospective randomized trial showed better results with nonsurgical treatment for type III and V injuries when clavicle displacement was less than 2 cm [4]. Noninvasive bracing is not superior to early functional rehabilitation and does not result in sustainably improved reduction compared to early functional rehabilitation in Rockwood type III and V injuries [21]. However, nonsurgical treatment for Rockwood type IV, V, and VI injuries likely results in substantial residual pain and limited function [4].

Operative

Indications: Surgical treatment is recommended for most patients with acute Rockwood type IV, V, and VI separations due to the high likelihood of persistent shoulder pain, dysfunction, and substantial deformity [4, 19]. Surgery is often recommended for patients with type IIIB (horizontally unstable) separations [4]. Acute surgery can be performed in selected type III separations in younger, physically active patients, manual laborers, patients with cosmetic concerns, or those with chronic injuries who have persistent symptoms [4]. A prospective randomized trial showed better results with surgical management for type III and V injuries when clavicle displacement was more than 2 cm [4]. Type V AC dislocations may be given a trial of conservative therapy, but surgery is generally indicated for high-grade separations [15, 19]. Surgical indications for distal clavicle excision include persistent pain and failure of nonsurgical treatment [18].

Surgical Approach / Technique: Proximal extension of the deltopectoral approach with a 'bra-strap' incision offers a safe and efficient solution for AC joint stabilization by combining reliability with improved visualization and reduced soft tissue trauma [1]. Arthroscopic stabilization for acute AC joint dislocations offers satisfactory clinical and radiographic outcomes with long-term reliability [3]. Arthroscopic AC joint reconstruction offers an attractive alternative with less morbidity, excellent cosmetics, no need to remove an implant, and minimal complications from breakage or migration of metal implants [23]. Acute AC joint dislocation requires stabilization in both the coracoclavicular junction and the acromio-clavicular joint planes [11]. CC/AC reconstruction surgical techniques yielded better shoulder stability than CC ligament alone reconstruction, potentially better maintaining reduction of the AC joint [9]. Anatomic AC joint reconstructions are biomechanically superior to nonanatomic techniques, such as the Weaver-Dunn procedure [18]. Reconstruction of AC dislocations using one or two TightRopes leads to stable results with higher stiffness than native joints [5]. Only sutures plus buttons reconstruction restored all stability measures (anterior, posterior, superior, inferior) to native values, while tape implants wrapped around the bones anteriorized the clavicle [49]. The AC joint capsule is a robust anatomical structure that contributes significantly to AC joint stability, especially in the anterior-posterior plane [6]. The AC ligaments play an essential function in posterior stability, providing scientific justification for comprehensive reconstruction approaches [16]. The transacromial technique showed the most translation and rotation compared to other direct AC ligament repair methods [7].

Timing: Early and delayed surgical interventions for high-grade AC joint dislocation provide equivalent clinical scores when combined coracoclavicular (CC) and AC joint fixation is used [2]. Acute surgery (less than 3 to 4 weeks following injury) for high-grade AC joint separations can be successfully performed with various fixation options without the use of tendon graft [18, 30]. Early surgical repair of type III AC joint injuries with or without augmentation seems to result in better patient satisfaction and clinical outcomes compared with delayed reconstruction [19]. A 2016 systematic review found superior functional outcomes in the early surgical group compared with delayed surgery for complete AC joint dislocation [19]. Partial dislocations or redislocations were found in 26% of cases in the early treatment group compared with 38.1% of cases in the delayed group [19]. Delayed reconstruction of AC joint separations requires biologic augmentation, either ligament transfer or tendon grafting, in addition to CC stabilization [18].

Implant Selection: Coracoclavicular reconstruction using LARS artificial ligament is an effective and safe method to treat grade III and more AC joint dislocations [10]. Satisfactory clinical outcomes were obtained after CC fixation using a single adjustable-loop-length suspensory fixation device for acute AC joint dislocation [13]. Kirschner wires and pins are not advised due to risks of implant failure and migration [30]. Subacromial erosion can occur with the use of a hook plate, and implant failure and migration resulting in vascular or neurologic injuries have been reported with hook plates [30]. Painful implants related to hook plates or CC screws usually require a second procedure for implant removal [30]. Aseptic foreign body reaction and erosion of the coracoid or clavicle have been reported with the use of synthetic suture loops [30]. Intrasubstance failure of synthetic grafts has been reported [30].

Complications: Surgical treatment for type III injuries results in an increase in complications compared to nonsurgical treatment [4]. The rates of complication were 12.5% in the early surgical group and 17.7% in the delayed surgical group, though differences did not reach statistical significance [19]. Surgical treatment for Rockwood type III AC joint dislocation may offer early benefits in pain relief and coracoclavicular distance improvement but does not enhance long-term functional outcomes and is associated with higher specific complication rates [34]. Loss of AC joint reduction, persistent pain, and instability can potentially complicate surgical outcomes [30]. Early or late fractures of the clavicle or coracoid process have been reported, especially with surgical techniques involving tunnels through the coracoid and/or clavicle [30]. Ossification of the CC space has been reported as a complication following surgery [30]. Neurologic injuries are rare but can involve nerve root injuries secondary to traction, direct injury to the suprascapular nerve, or injury to the brachial plexus with techniques passing grafts or suture loops under the coracoid process [30]. Other complications such as adhesive capsulitis, osteomyelitis of the AC joint, and upper extremity deep vein thrombosis have been reported [30]. A large asymptomatic pneumothorax has been reported following arthroscopic-assisted AC joint reconstruction after ultrasound-guided interscalene block [57]. Both surgical and anesthesia teams should be cognizant of the risk of pulmonary complications associated with shoulder arthroscopy performed with and without interscalene nerve blockade [57].

Distal Clavicle Excision: Distal clavicle excision for painful AC joint arthritis has a higher failure rate in patients with a history of previous low-grade AC joint separations [18]. Resection of the distal clavicle for AC joint arthritis should be limited to 5 to 10 mm of bone [18]. Biomechanical evidence suggests a resection of 5 mm is needed to prevent contact between the clavicle and the acromion in the absence of instability [18]. Pain relief from distal clavicle excision is reliable in greater than 90% of patients in the absence of instability [18]. Previous traumatic instability is associated with persistent pain in 30% to 40% of cases following distal clavicle excision [18]. Relative contraindications for distal clavicle excision include a previous low-grade separation with persistent horizontal plane instability [18]. Between 5 and 10 mm of the distal clavicle should be resected in open distal clavicle resection (Mumford procedure) [18]. Meticulous repair of the deltotrapezial fascia is important in open distal clavicle resection [18]. Surgery for distal clavicle osteolysis is successful in more than 90% of patients [18]. One systematic review showed slightly better results with arthroscopic excision than with open distal clavicle excision [18]. Direct comparison studies have shown similar or better results with arthroscopic excision than with open techniques [18].

Outcomes and Rehabilitation: Nonoperative treatment produced more prominent or unstable and radiographically wider ACJs than operative treatment, but clinical results were equally good at 18- to 20-year follow-up [14]. Patients should refrain from returning to contact sports or heavy lifting for approximately 2 to 3 months until restoration of full, painless shoulder ROM [19]. There is substantial variability in publicly accessible AC joint rehabilitation protocols, including a wide range in recommendations for time to return to sport [12]. Patients in the nonsurgical group had a faster return to work and sports, although with an inferior cosmetic appearance [19]. A recent prospective randomized trial found no statistical differences in validated outcome scores or return to preinjury sporting activity between surgical and nonsurgical management of acute type III and IV AC joint separations at 1 year follow-up [19]. Five patients (16%) in the nonsurgical group required surgery for persistent symptoms at a mean of 8.7 months in a recent prospective randomized trial [19]. No evidence supports early surgical management for type I or type II AC joint separations [19]. Complications associated with nonsurgical management include persistent pain, crepitus, deformity, swelling at the AC joint, late arthrosis, and persistent instability [30].

Complications

Instability: Persistent symptoms and residual pain are common following non-operative management of Type I and II AC joint injuries, with 30% to 50% of young, very active patients reporting mild to moderate pain [4]. Retrospective data indicate persistent symptoms in up to 40% to 50% of these patients at 1, 6, and 10 years [19], leading approximately 27% to undergo surgical intervention at a mean of 26 months [19]. In acute Type III dislocations, surgical intervention adds the risk for complications while improving joint reduction [65], though a systematic review found no enhancement in long-term functional outcomes compared to nonsurgical treatment [34]. Surgical treatment for Type III separations is specifically associated with an increased complication rate compared to nonsurgical care [4]. Partial or redislocation rates are significant, occurring in 26% of early surgical cases and 38.1% of delayed surgical cases for complete dislocations [19]. Overreduction of Type V dislocations during acute fixation improves postoperative Rockwood classification but is associated with a high percentage of patients still losing reduction [22]. Loss of AC joint congruity remains unacceptably high after stabilization with cortical suspensory devices, where tunnel widening and loss of reduction may be inevitable [63]. Anatomic reconstruction carries a 16% mechanical failure rate in one series [24], while LARS ligament reconstruction showed a 2% failure (re-dislocation) rate at 2-year minimum follow-up [33].

Revision and Failure: The rate of revision AC joint stabilization was 14.3% in a cohort with minimum 10-year outcomes following arthroscopically-assisted anatomic coracoclavicular reconstruction [8]. Early surgical repair of Type III injuries results in better patient satisfaction and clinical outcomes compared with delayed reconstruction, though complication rates were 12.5% in the early group and 17.7% in the delayed group [19]. Conversely, a prospective randomized trial found that 16% of patients in the nonsurgical group required surgery for persistent symptoms at a mean of 8.7 months [19].

Other Considerations: Patients with Type I and II AC joint injuries are at increased risk for painful AC joint arthritis [4]. There is substantial variability in publicly accessible AC joint rehabilitation protocols, including a wide range in recommendations for the appropriate time to return to sport [12]. The transacromial technique showed the most translation and rotation compared to other methods for direct acromioclavicular ligament repair [7]. Unconstrained total shoulder arthroplasty has been demonstrated to be a highly successful procedure, though long-term follow-up is lacking [32].

Recovery

Light activity (weeks): Early functional rehabilitation is preferred over noninvasive bracing, which fails to sustainably improve reduction compared to early mobilization [21]. While publicly accessible protocols show substantial variability in recommendations for time to return to sport, early and delayed surgical interventions provide equivalent clinical scores when combined coracoclavicular and AC joint fixation is utilized [2, 12].

Full activity (months): Both hook plate fixation and coracoclavicular reconstruction yield excellent functional outcomes for acute unstable dislocations [25]. Reconstruction using one or two TightRopes results in stable outcomes with higher stiffness than native joints [5], while coracoclavicular reconstruction with LARS artificial ligament is an effective and safe method for grade III and higher dislocations [10]. In young, active populations with Type V dislocations treated acutely, a high percentage of patients lost reduction yet still returned to duty [22].

Complete recovery / outcome plateau (months): Nonoperative treatment results in more prominent or unstable and radiographically wider ACJs than operative treatment, yet clinical results remain equally good at 18- to 20-year follow-up [14]. Arthroscopic stabilization for acute dislocations offers satisfactory clinical and radiographic outcomes that are reliable in the long run [3]. The rate of revision ACJ stabilization was 14.3% in a cohort with minimum 10-year outcomes after arthroscopically-assisted anatomic coracoclavicular reconstruction [8]. Failures with LARS ligament reconstruction occurred in 2% of cases at 2-year minimum follow-up [33].

Rehabilitation protocol: Acute AC joint dislocation requires stabilization in both the coracoclavicular junction and the acromio-clavicular joint planes to address the specific biomechanical deficits [11]. The AC joint capsule contributes significantly to stability, particularly in the anterior-posterior plane [6]. Independent acromioclavicular ligament repair demonstrated significant translational stability in both anterior-posterior and superior-inferior planes, restoring stability to a state comparable to native ligaments [31]. Conversely, the transacromial technique showed the most translation and rotation compared to other methods for direct AC ligament repair [7].

Functional milestones: AC joint reconstruction with LARS ligament did not reveal differences in clinical outcomes between professional and non-professional athletes [33]. Subgroup analyses of return to sport outcomes were not feasible due to methodological heterogeneity between studies [36].

Other Considerations: The choice of fixation must account for the specific stability requirements of the joint planes, as combined fixation is necessary for equivalent clinical scores regardless of timing [2]. While nonoperative management yields good long-term clinical results, it is associated with persistent radiographic widening and instability [14].

Key Evidence

  • [L5] By combining the reliability of a well-established technique with improved visualization and reduced soft tissue trauma, this muscle-sparing, cost-effective approach offers a safe and efficient solution for AC joint stabilization. (10.1016/j.xrrt.2025.06.010)
  • [L3] Early and delayed surgical interventions of high-grade AC joint dislocation provide equivalent clinical scores when combined CC and AC joint fixation is used for stabilization. (10.1016/j.jse.2020.06.026)
  • [L3] Arthroscopic stabilization for acute AC joint dislocations offers satisfactory clinical and radiographic outcomes, and the arthroscopic technique is reliable in the long run. (10.5397/cise.2023.01060)
  • [L5] Reconstruction of AC dislocations with one or two TightRopes leads to stable results with higher stiffness than native joints. (10.1007/s00167-015-3920-1)
  • [L5] The AC joint capsule is a robust anatomical structure that contributes significantly to the AC joint stability, especially in the AP plane. (10.1016/j.jse.2008.08.003)
  • [L5] In contrast, the transacromial technique (group 3) showed the most translation and rotation. (10.1177/0363546514538947)
  • [L4] The rate of revision ACJ stabilization was 14.3%. (10.1177/2325967125s00150)
  • [L2] CC/AC reconstruction surgical technique yielded a better shoulder stability than CC ligament alone reconstruction that may better maintain reduction of the AC joint. (10.1177/17585732211068322)
  • [L4] This procedure was an effective and safe method to treat grade III and more AC joint dislocations. (10.1007/s00167-013-2582-0)
  • [L2] This study demonstrates that acute ACJD requires stabilisation in both planes, i.e., at the coracoclavicular junction and at the acromio-clavicular joint. (10.1016/j.arthro.2016.03.056)
  • [L4] There was substantial variability in publicly accessible AC joint rehabilitation protocols, including a wide range in the recommendations for appropriate time to return to sport. (10.1016/j.asmr.2020.10.007)
  • [L4] Satisfactory clinical outcomes were obtained after CC fixation using the single adjustable-loop-length suspensory fixation device for acute AC joint dislocation. (10.1016/j.arthro.2014.11.013)
  • [L2] Nonoperative treatment was shown to produce more prominent or unstable and radiographically wider ACJs than was operative treatment, but clinical results were equally good in the study groups at 18- to 20-year follow-up. (10.1177/2325967114560130)
  • [L4] This suggests that Type V AC dislocations may be given a trial of conservative therapy. (10.1177/2325967115s00017)
  • [L5] The study provides a scientific justification for comprehensive reconstruction approaches by demonstrating the essential function of AC ligaments in posterior stability. (10.5397/cise.2025.00843)
  • [L3] However, no sustainably improved reduction of the ACJ resulted from bracing, when compared to early functional rehabilitation, thus questioning its utility. (10.1016/j.jse.2024.08.040)
  • [L3] In a young, active population with Type V ACJ dislocation treated acutely, a high percentage lost reduction yet still returned to duty. (10.1177/2325967124s00051)
  • [Abstract] Considering its less morbidity, excellent cosmetics, no need to remove an implant, and minimal complications from breakage or migration of metal implants, this new technique offers an attractive alternative in acromioclavicular joint stabilization. (10.1016/j.jse.2007.02.103)
  • [L4] Anatomic AC joint reconstruction resulted in a 16% mechanical failure rate in this series. (10.1016/j.jse.2014.06.017)
  • [L3] Both fixations yielded excellent functional outcomes. (10.1186/s12891-021-03978-3)
  • [L4] The authors recommend grading acute AC joint lesions by performing a digital measurement instead of a sole visual diagnosis due to higher intra- and interobserver reliability. (10.1007/s00167-014-3436-0)
  • [L5] RW type VI AC dislocations remain exceedingly rare, with only 24 cases reported to date. (10.1016/j.jisako.2025.101042)
  • [L5] The independent acromioclavicular ligament repair, disregarding the routinely reconstructed coracoclavicular ligaments, demonstrated significant translational stability in both the anterior–posterior and superior–inferior planes, restoring stability to a state comparable to the native ligaments of the intact joint. (10.1177/1758573219857685)
  • [L2] AC joint reconstruction with LARS ligament did not reveal differences in clinical outcomes between professional and non-professional athletes, with 2% of failures (re-dislocations) at 2-year minimum follow-up. (10.1007/s00167-014-3231-y)
  • [L1] Surgical treatment may offer early benefits in pain relief and coracoclavicular distance improvement but does not enhance long-term functional outcomes and is associated with higher specific complication rates. (10.1186/s12891-024-08100-x)
  • [L4] However, the level of evidence was low and due to methodological heterogeneity between studies, subgroup analyses of return to sport outcomes were not feasible. (10.1007/s00167-019-05528-w)
  • [L3] The Kraus system was slightly more reliable than the Rockwood system for classifying AC joint injuries both between assessor groups and overall. (10.1177/23259671221149391)
  • [L5] Anatomically, it provides sufficient tissue length, excursion, and width, and biomechanically, it is as strong as the coracoacromial ligament. (10.1016/j.jse.2006.09.007)
  • [L3] Rockwood type III was the most common type of AC joint dislocation constituting 55.7% of the injuries. (10.1177/17585732221123314)
  • [L5] This study demonstrated biomechanical noninferiority of all four construct groups with respect to each other, with no significant differences in dynamic creep, translation, displacement, or stiffness. (10.1016/j.jse.2024.06.020)
  • [L5] There are large kinematic differences between the intact state and a Rockwood V lesion not only during humerothoracic, but also during scapulothoracic movements. (10.1016/j.jse.2022.01.096)
  • [L5] The CE and TR techniques led to similar biomechanical performances. (10.1016/j.jse.2012.01.020)
  • [L5] Large kinematic differences were seen between the intact state and a Rockwood V lesion not only during humerothoracic movements but also during scapulothoracic movements in the cadaveric model. (10.1177/03635465211053016)
  • [L4] Ninety-one percent of patients with acute AC joint dislocation Rockwood type III and V recovered without surgery and there were no differences in outcome scores between type III and V at any time point. (10.1002/ksa.12070)
  • [L2] The presence of scapular dyskinesis was associated with an inferior result. (10.1016/j.jisako.2023.03.318)
  • [L5] Only the sutures + buttons reconstruction restored all stability measures (anterior, posterior, superior, inferior) to native values, while tape implants wrapped around the bones anteriorised the clavicle. (10.1007/s00167-021-06700-x)
  • [L5] In this biomechanical study, ST CC ligament reconstruction demonstrates biomechanical properties comparable to the intact state. (10.1177/0363546517752673)
  • [L3] Coracoid position relative to the lateral edge of the clavicle is correlated with anatomic parameters, most strongly with clavicle length. (10.1177/2325967119893276)
  • [L5] Side-to-side suturing provides equivalent initial biomechanical strength compared with interference screw fixation. (10.1016/j.jse.2011.10.029)
  • [L5] Biomechanical testing of both constructs showed similar fixation stability after cyclical axial loading and similar loads to failure. (10.1177/2325967116674668)
  • [L2] The scapular-based V angle on anteroposterior radiographs distinguishes between Rockwood types III and V as well as cases with partial or complete dynamic horizontal translation. (10.1007/s00167-023-07570-1)
  • [Case_report] Both the surgical and anesthesia teams should be cognizant of the risk of pulmonary complications associated with shoulder arthroscopy performed both with and without interscalene nerve blockade. (10.1016/j.jseint.2020.02.013)
  • [L4] The MINAR® system promises satisfactory functional and radiological results. (10.3390/jcm8101683)
  • [L5] Loss of AC joint congruity remains unacceptably high regardless of whether inset or onlay cortical suspensory devices are used, with tunnel widening and loss of reduction potentially being inevitable. (10.1016/j.arthro.2023.06.039)
  • [L1] While surgical intervention is able to improve joint reduction, it adds the risk for surgical complications. (10.1530/eor-2024-0077)

See Also

References

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[2] Early and delayed acromioclavicular joint reconstruction provide equivalent outcomes. Journal of Shoulder and Elbow Surgery. 2021. DOI: 10.1016/j.jse.2020.06.026

[3] Long-term clinical and radiographic outcomes of arthroscopic acromioclavicular stabilization for acute acromioclavicular joint dislocation. Clinics in Shoulder and Elbow. 2024. DOI: 10.5397/cise.2023.01060

[4] Aaos Comprehensive Orthopaedic Review 3. Disorders of the Acromioclavicular Joint > II. Traumatic Conditions of the AC Joint.

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[12] Publicly Accessible Rehabilitation Protocols for Acromioclavicular Joint Reconstruction Are Widely Variable. Arthroscopy, Sports Medicine, and Rehabilitation. 2021. DOI: 10.1016/j.asmr.2020.10.007

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[22] Paper 39: Overreduction of Type V Acromioclavicular Joint Dislocations During Acute Fixation is Associated with Improved Postoperative Rockwood Classification. Orthopaedic Journal of Sports Medicine. 2024. DOI: 10.1177/2325967124s00051

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[34] Comparative efficacy of operative versus conservative treatment for Rockwood type III acromioclavicular joint dislocation: a systematic review and meta-analysis of randomized controlled trials. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-08100-x

[36] Return to sport after surgical treatment for high‐grade (Rockwood III–VI) acromioclavicular dislocation. Knee Surgery, Sports Traumatology, Arthroscopy. 2019. DOI: 10.1007/s00167-019-05528-w

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[38] Anatomy of the pectoralis minor tendon and its use in acromioclavicular joint reconstruction. Journal of Shoulder and Elbow Surgery. 2007. DOI: 10.1016/j.jse.2006.09.007

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[40] The TightRope study: a cadaveric, biomechanical comparison of generations of suspensory fixation with internal brace for Rockwood grade V acromioclavicular joint injuries. Journal of Shoulder and Elbow Surgery. 2025. DOI: 10.1016/j.jse.2024.06.020

[42] Kinematic Alterations In The Shoulder Complex In Rockwood V Acromioclavicular Dislocations During Humerothoracic And Scapulothoracic Movements. Journal of Shoulder and Elbow Surgery. 2022. DOI: 10.1016/j.jse.2022.01.096

[43] Acromioclavicular joint reconstruction: a comparative biomechanical study of three techniques. Journal of Shoulder and Elbow Surgery. 2013. DOI: 10.1016/j.jse.2012.01.020

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[45] Acromioclavicular joint dislocation Rockwood type III and V show no difference in functional outcome and 91% recovered well without the need for surgery. Knee Surgery, Sports Traumatology, Arthroscopy. 2024. DOI: 10.1002/ksa.12070

[47] The ISAKOS Subclassification of Rockwood Type III AC Joint Dislocations in a Stable Type A and an Unstable Type B Is Not Clinically Relevant. A Prospective Cohort Study of 95 Patients Primarily Treated Non-Surgically. Journal of ISAKOS. 2023. DOI: 10.1016/j.jisako.2023.03.318

[49] Acromioclavicular joint reconstruction implants have differing ability to restore horizontal and vertical plane stability. Knee Surgery, Sports Traumatology, Arthroscopy. 2021. DOI: 10.1007/s00167-021-06700-x

[51] Biomechanical Evaluation of a Single- Versus Double-Tunnel Coracoclavicular Ligament Reconstruction With Acromioclavicular Stabilization for Acromioclavicular Joint Injuries. The American Journal of Sports Medicine. 2018. DOI: 10.1177/0363546517752673

[52] Sex-Based Differences in Optimal Tunnel Placement for Acromioclavicular Joint Reconstruction. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967119893276

[54] Biomechanical evaluation of graft fixation techniques for acromioclavicular joint reconstructions using coracoclavicular tendon grafts. Journal of Shoulder and Elbow Surgery. 2012. DOI: 10.1016/j.jse.2011.10.029

[55] Axial-Plane Biomechanical Evaluation of 2 Suspensory Cortical Button Fixation Constructs for Acromioclavicular Joint Reconstruction. Orthopaedic Journal of Sports Medicine. 2016. DOI: 10.1177/2325967116674668

[56] The V angle compliments radiographic assessment of acute acromioclavicular joint dislocations by differentiating between Rockwood types III versus V and by considering dynamic horizontal translation in coronal radiographs. Knee Surgery, Sports Traumatology, Arthroscopy. 2023. DOI: 10.1007/s00167-023-07570-1

[57] Large asymptomatic pneumothorax following arthroscopic-assisted acromioclavicular joint reconstruction after ultrasound-guided interscalene block: a case report. JSES International. 2020. DOI: 10.1016/j.jseint.2020.02.013

[58] Minimally Invasive AC Joint Reconstruction System (MINAR®) in Modified Triple-Button Technique for the Treatment of Acute AC Joint Dislocation. Journal of Clinical Medicine. 2019. DOI: 10.3390/jcm8101683

[63] Editorial Commentary: Tunnel Widening and Loss of Reduction May Be Inevitable After Acromioclavicular Stabilization With Cortical Suspensory Devices Whether Inset (Top Hats) or Onlay (Buttons). Arthroscopy. 2023. DOI: 10.1016/j.arthro.2023.06.039

[65] Surgical vs conservative: what is the best treatment of acute Rockwood III acromioclavicular joint dislocation? A systematic review and meta-analysis. EFORT Open Reviews. 2025. DOI: 10.1530/eor-2024-0077

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b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.