Distal Clavicle Osteolysis Impormasyon In-depth

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

• Clinical signs and symptoms for atraumatic distal clavicular osteolysis are not distinguishable from other shoulder pathologies [1].
• In appropriately selected patients, open or arthroscopic distal clavicle resection is necessary to relieve symptoms [6].
• Arthroscopic distal clavicle resection has provided more 'good or excellent' results than the open procedure [4].
• Among patients undergoing distal clavicle excision for acromioclavicular joint pathology, those having an arthroscopic procedure through the direct approach can expect a faster return to activities while obtaining similar long-term outcomes compared with the open procedure [3].
• A well-performed distal clavicle excision will likely perform better than a poorly performed one, regardless of whether an open or arthroscopic approach is chosen [9].
• Routine distal clavicle excision is not absolutely necessary, even in patients with symptomatic acromioclavicular joint osteoarthritis [25].
• Clavicular resection reliably produced significant improvement in patients with persistent pain or posttraumatic arthritis [5].
• For chronic symptomatic injuries, partial claviculectomy is believed to be the best procedure, offering negligible morbidity and rapid return to function [16].
• Excision of the outer end of the clavicle is preferred for old dislocations, while open reduction and internal fixation are not recommended due to complications and poor functional results [15].
• Total claviculectomy yielded good results for patients with chronic osteitis and malignancy but unsatisfying results for those with chronic posttraumatic pain, despite full range of motion being regained in all cases [32].
• Total claviculectomy is a possible treatment option for chronic clavicular dislocation with excellent outcomes and high patient satisfaction [27].
• The combination of distal clavicle resection and antibiotics halted the osteolysis in a case of Propionibacterium acnes–mediated distal clavicular osteolysis, with the patient remaining symptom free at 10 months after surgery [2].

Anatomy & Pathophysiology

Bony Anatomy

• The clavicle is the only long bone to ossify by intramembranous ossification [21].
• The clavicle serves as the primary stabilizer between the axial skeleton via the sternoclavicular joint and the appendicular skeleton via the acromioclavicular joint [21].
• The clavicle forms a unique S-shaped curve on the axial view [21].
• The distal clavicle is flat in the AP plane [21].
• The clavicle is a relatively straight bone when anteriorly viewed, whereas in the transverse plane, it resembles an italic S [44].
• The greater radius of curvature occurs at the medial curve of the clavicle, which is anteriorly convex [44].
• The smaller lateral curve of the clavicle is posteriorly convex [44].
• The bone is somewhat rounded in its midsection and medially and relatively flat laterally [44].
• DePalma described an inverse relationship between the degree of downward facing of the lateral portion of the clavicle and the radius of curvature of the lateral curve of the clavicle [44].
• The medial end of the clavicle has a 30% incidence of a rhomboid fossa on its inferior surface where the costoclavicular ligaments insert [44].
• The medial end of the clavicle has a 2.5% incidence of an actual articular surface facing inferiorly toward the first rib [44].
• The middle portion of the clavicle contains the subclavian groove where the subclavius muscle has a fleshy insertion [44].
• The lateral portion of the clavicle has the coracoclavicular process when present [44].
• The clavicle has three bony impressions for attachment of ligaments [44].
• At the medial side of the clavicle is an impression for the costoclavicular ligaments, which at times may be a rhomboid fossa [44].
• At the lateral end of the clavicle is the conoid tubercle [44].
• The trapezoid line lies in an anteroposterior direction just lateral to the conoid tubercle on the posterior portion of the lateral curve of the clavicle [44].
• The conoid ligament attaches to the clavicle at the conoid tubercle [44].
• The trapezoid ligament attaches at the trapezoid line [44].
• The distance from the lateral edge of the clavicle to the medial edge of the conoid tubercle in male and female specimens was approximately 45 mm [44].
• The distance from the lateral edge of the clavicle to the center of the trapezoid tuberosity was approximately 25 mm [44].
• The trapezius muscle inserts on the posterosuperior surface of the distal end of the clavicle [44].
• The subclavius muscle has a fleshy insertion on the inferior surface of the middle third of the clavicle [44].
• The deltoid originates on the anterior portion of the inner surface of the lateral curve of the clavicle [44].
• The pectoralis major originates from the anterior portion of the medial two-thirds of the clavicle [44].
• The sternocleidomastoid largely originates on the posterior portion of the middle third of the clavicle [44].
• The sternohyoid originates on the clavicle just medial to the origin of the sternocleidomastoid [44].
• The primary blood supply to the clavicle is periosteal, and there is no nutrient blood supply [21].
• The clavicle is subcutaneous, and its muscular envelope includes the platysma, pectoralis major, deltoid, and some of the strap muscles of the neck [21].
• The clavicle is one of the first bones to ossify, beginning from two primary ossification centers (medial and lateral) by 5 to 6 weeks of gestation [38].
• By 7 to 8 weeks of gestation, the clavicle has already assumed its overall contour and “S” shape [38].
• Most growth (80%) of the clavicle occurs from the medial physis [38].
• The lateral epiphysis of the clavicle forms and fuses in a remarkably short time at around 18 to 19 years of age [38].
• The medial epiphysis is the last in the body to ossify, at the age of 18 to 20 years [38].
• The medial epiphysis is the last to complete ossification, at the age of 23 to 25 years [38].

Ligaments and Soft Tissue

• The coracoclavicular ligaments consist of the conoid (medial) and trapezoid (lateral) components [21].
• The coracoclavicular ligaments are the primary stabilizers to superior (vertical) translation of the distal clavicle [21].
• The trapezoid and conoid ligaments have unique functions in normal shoulder kinematics because of their anatomic attachments [42].
• The acromioclavicular joint ligamentous system contributes to clavicular strut function [46].
• The coracoacromial ligament provides sufficient tissue length, excursion, and width, and is biomechanically as strong as the coracoacromial ligament [51].

Biomechanics and Kinematics

• The superior shoulder suspensory complex (SSSC) is a bone–soft-tissue ring that provides a stable connection of the glenoid and scapula to the clavicle [21].
• The SSSC is composed of four bony landmarks—distal clavicle, acromion, coracoid process, and glenoid neck—and the supporting ligamentous complexes of the AC joint and the CC ligaments [21].
• The SSSC plays an important role in shoulder stability and biomechanics [36].
• Kinematic changes in the shoulder with AC joint dislocation could be a potential source of pain and dysfunction [43].
• Scapular and clavicular kinematics were affected in AC separation models [46].
• Despite technology innovations, a precise, easy to use and low-cost non-invasive method able to draw and analyze the kinematics of the shoulder complex has not been developed yet [35].
• The inconsistency of AC joint testing parameters and the lack of thorough translation studies indicate a necessity for increased attention in the overall assessment of shoulder stability to close the gap in the foundational biomechanical research [50].
• At 150 to 200 N of loading, coracoacromial ligament excision and acromioplasty increase the rotator cuff force required to maintain normal glenohumeral biomechanics by 25% to 30% [61].

Pathophysiology and Injury Mechanisms

• Clinical signs and symptoms for atraumatic distal clavicular osteolysis (ADCO) were not distinguishable from other shoulder pathologies [1].
• A direct blow on the point of the shoulder is the commonest reported mechanism of injury that produces a midshaft fracture of the clavicle [48].
• As the shoulder girdle is subjected to compression force directed from laterally, the main strut maintaining position is the clavicle and its articulations [48].
• When force exceeds the capacity of the clavicular strut to withstand it, failure can occur in the acromioclavicular articulation, the clavicle may break, or the sternoclavicular joint may dislocate [48].
• Most (85%) clavicle fractures occur in the midshaft of the bone where the bone is narrowest and enveloping soft tissue structures are most scarce [48].
• The direction of the initial deforming force, and both gravitational and muscular forces on the clavicle result in the typical deformity seen after fracture, with the distal fragment being translated inferiorly, anteriorly, and medially (shortened), and rotated anteriorly [48].
• Simple falls from a standing height are unlikely to produce a displaced fracture in a healthy young person, but can result in injury in elderly, osteoporotic individuals [48].
• Fractures resulting from trivial mechanisms in elderly, osteoporotic individuals are typically seen in the distal third of the clavicle [48].
• Type I acromioclavicular injuries involve intra-articular damage of the acromioclavicular joint alone, without ligamentous instability either of the joint capsule or of the coracoclavicular ligaments [74].
• Type II acromioclavicular injuries consist of dislocation of the acromioclavicular joint and disruption of its capsule and ligaments without disruption of the coracoclavicular ligaments [74].
• Type III acromioclavicular injuries consist of acromioclavicular separation with disruption of the coracoclavicular ligaments as well as of the acromioclavicular ligaments, leaving the clavicle grossly unstable [74].
• In Type I acromioclavicular injuries, there is a direct lateral impact on the acromion with crushing of the acromioclavicular joint surfaces [74].
• In Type II and III acromioclavicular injuries, forces are delivered in a more superolateral direction [74].
• In Type II and III acromioclavicular injuries, forces first produce external rotation of the scapula, which pivots on the coracoclavicular ligaments, disrupting the acromioclavicular ligaments [74].
• In Type III acromioclavicular injuries, as forces are continued, the scapula and clavicle move downward, and the clavicle abuts against the first rib causing disruption of the coracoclavicular ligaments [74].
• A type I acromioclavicular injury is an isolated sprain of the AC ligaments with no clinical deformity and normal radiographs [76].
• A type II acromioclavicular injury consists of a complete tear of the AC ligaments and a sprain of the CC ligaments [76].
• In a type II acromioclavicular injury, the radiograph shows a more vertical translation of the CC interval (<25%) compared with that of the uninjured shoulder [76].
• The normal coracoclavicular distance measures approximately 1.1 to 1.3 cm [76].
• In a type II acromioclavicular injury, there is AP instability of the AC joint, which has biomechanically been shown to cause an increase of 3.6 mm in anterior and 6.4 mm in posterior translation [76].
• In a type III acromioclavicular injury, AC joint dislocation occurs secondary to complete disruption of the AC and CC ligaments [76].
• In a type III acromioclavicular injury, there is increased vertical translation of the CC distance (25% to 100%) compared with that of the uninjured shoulder and an obvious clinical deformity [76].
• Type I and II acromioclavicular joint disruptions impair long-term shoulder function in about half of patients 10 years after injury [60].

Classification

• The ISAKOS Upper Extremity Committee suggests adding grade IIIA and grade IIIB injuries to a modified Rockwood classification to distinguish between stable type III injuries and unstable grade III injuries with therapy-resistant scapular dysfunction and overriding clavicle [78].
• According to the Rockwood classification, the diagnosis of type I was established when 0% to <10% superior displacement of the distal clavicle was found [70].
• According to the Rockwood classification, type II was present if the affected side differed by 10% to ≤25% superior displacement compared with the contralateral side [70].
• According to the Rockwood classification, a type III dislocation was defined as a coracoclavicular distance difference (CCD) of >25% to ≤100% compared with the contralateral side [70].
• According to the Rockwood classification, a CCD of >100% compared with the contralateral side indicated an RW type V separation [70].
• A new classification of AC joint instability defined Group 1 as having a CCD ≤30%, which included all RW type I, type II, and borderline low-grade type III patients [70].
• A new classification of AC joint instability defined Group 2 as having a CCD >30%, which represented high-grade AC joint dislocations including all RW type V patients and the majority of the RW type III patients [70].
• Grade I acromioclavicular sprains are the result of a mild force with only a few fibers of the acromioclavicular ligament and capsule involved, with no laxity of the acromioclavicular joint [28].
• Grade II acromioclavicular sprains are usually the result of a moderate force which causes rupture of the capsule and acromioclavicular ligament, without rupture of the coracoclavicular ligaments [28].
• Roentgenograms for Grade II acromioclavicular sprains reveal the clavicle riding higher than the acromion to an extent usually less than the width of the clavicle [28].
• Methods to diagnose both superior and posterior translation of the clavicle need further debate [17].
• The assessment of the presence of any horizontal plane instability in acromioclavicular joint dislocations remains clinical [23].
• There is no clear consensus on the true definition of an axial radiograph projection for assessing horizontal plane deformity of the acromioclavicular joint [23].

Clinical Presentation

• Patients with distal clavicular osteolysis present with isolated pain at the distal clavicle and acromioclavicular joint that tends to worsen with activity [64].
• Distal clavicular osteolysis exists in two forms: posttraumatic distal clavicular osteolysis caused by direct traumatic injury, and atraumatic distal clavicular osteolysis attributable to repetitive stress [64].
• In adults, the most common risk factor for stress-induced distal clavicular osteolysis is weightlifting [64].
• Radiographic findings for distal clavicular osteolysis may range from mild osteopenia to overt osteolysis [64].
• The bilateral Zanca view is helpful in diagnosing distal clavicular osteolysis as it profiles the acromioclavicular joint and allows for comparison with the contralateral side [64].
• Magnetic resonance imaging characteristics of distal clavicular osteolysis include distal clavicular bone marrow edema that is out of proportion to the edema at the acromion, as well as subchondral cystic change [64].
• In advanced cases of distal clavicular osteolysis, periostitis may be observed at the distal clavicle on magnetic resonance imaging [64].
• Patients presenting with massive osteolysis after shoulder surgery should be evaluated for Gorham-Stout disease [7].
• Retaining a clavicular hook-plate indefinitely carries a potential risk of developing osteolysis and fracture around the implant [12].
• Subacromial osteolysis following hook plate fixation for acromioclavicular dislocation has a relatively high and variable incidence [19].
• The primary factor influencing the reported incidence of subacromial osteolysis is the radiological assessment method [19].

Investigations

Clinical Presentation and Diagnosis

• Fractures of the outer third of the clavicle are easily mistaken for acromioclavicular injuries [66].
• Segmental fractures of the clavicle are easily missed [26].
• A high index of suspicion is needed to diagnose bone osteolysis following acromioclavicular joint reconstruction using synthetic ligament early before irretrievable bone loss [81].
• The need to consider Gorham-Stout disease exists in patients presenting with massive osteolysis after shoulder surgery [7].

Imaging and Radiographic Assessment

• Simple anteroposterior (AP) radiographs are usually sufficient to establish the diagnosis of a clavicle fracture [57].
• A single AP chest radiograph may be used to evaluate the deformity of the involved clavicle relative to the normal side and to look for associated skeletal injuries such as rib, glenoid, and scapular fractures [57].
• Shortening of 2 cm or more on a chest radiograph represents a relative indication for primary fixation [57].
• To best delineate a clavicular fracture, a radiograph should be taken in the upright position where gravity demonstrates maximal deformity [57].
• The radiographic beam for the AP radiograph of the clavicle should be angled 20 degrees superiorly to eliminate the overlap of the thoracic cage and show the clavicle in profile [57].
• If the torso is internally rotated a similar 20 degrees, the scapula and shoulder girdle are placed parallel to the cassette for a true AP film [57].
• CT scanning of midshaft clavicular fractures is rarely performed in the clinical setting but can demonstrate the complex three-dimensional deformity affecting the shoulder girdle [57].
• CT is useful for evaluating fractures of the medial third of the clavicle and the remainder of the shoulder girdle, such as the glenoid neck in cases of a “floating shoulder” [57].
• Outer-third clavicle injuries need special views to define any fracture [66].
• Weighted stress radiographs significantly increased the measured elevation of the clavicle and the coracoclavicular distance compared to non-weighted views [75].
• Subacromial osteolysis has a relatively high and variable incidence, and the primary factor influencing the reported incidence is the radiological assessment method [19].

Anatomical and Biomechanical Context

• The superior shoulder suspensory complex is a bone–soft-tissue ring that provides a stable connection of the glenoid and scapula to the clavicle [21].
• The superior shoulder suspensory complex is composed of four bony landmarks—distal clavicle, acromion, coracoid process, and glenoid neck—and the supporting ligamentous complexes of the AC joint and the CC ligaments [21].
• The primary blood supply to the clavicle is periosteal; there is no nutrient blood supply [21].

Treatment

Non-Operative Management

• Initial treatment for primary acromioclavicular joint osteoarthritis consists of oral analgesia, physiotherapy, and joint injection [68].
• Non-operative treatments for acromioclavicular joint pain include analgesics, physiotherapy, injections, and immobilisation in a sling [63].
• Patients presenting with isolated acromioclavicular joint pain who did not respond to at least 6 months of nonoperative measures (including cryotherapy, nonsteroidal anti-inflammatory drugs, activity modification, and other treatment modalities) were eligible for surgical inclusion in a randomized trial [24].
• In the next 5 years, there will be more effective improvements in nonoperative treatments for Rockwood Type III acromioclavicular joint dislocations [67].
• A clinical trial comparing a sling versus the Acromion 2.0 brace for Rockwood Type III acromioclavicular joint dislocations was completed in the past year relative to the 2023 publication [67].
• Physical therapy programs that are functionally based and focused on restoring dynamic acromioclavicular, scapular, and shoulder motion could further improve the results of nonoperative treatment [67].
• A subgroup of patients in the nonoperative arm of randomized controlled trials for Rockwood Type III acromioclavicular joint dislocations had persistent pain or shoulder dysfunction and crossed over to operative treatment [67].
• Patients who crossed over to operative treatment from the nonoperative arm for Rockwood Type III acromioclavicular joint dislocations continued to have lower outcome scores [67].

Operative Management

• Arthroscopic distal clavicle resection has provided more 'good or excellent' results than the open procedure, but is comprised of low-level evidence [4].
• Simple excision of the outer end of the clavicle has yielded satisfactory results in patients with complete dislocation and subluxation of the acromioclavicular joint, with no residual upward displacement disturbing the patients [8].
• The combination of distal clavicle resection and antibiotics halted osteolysis in a patient with Propionibacterium acnes–mediated distal clavicular osteolysis, and the patient remained symptom free at 10 months after surgery [2].
• Excellent clinical results were achieved with acromioclavicular joint reconstruction using coracoacromial ligament transfer with the docking technique, decreasing the risk of recurrent distal clavicle instability [29].
• Satisfactory outcome for a fracture clavicle with acromioclavicular dislocation depends upon restoring the stability of the clavicle as well as the acromioclavicular joint [30].
• Surgical management options for acromioclavicular joint pain include open acromioclavicular joint reconstruction, arthroscopic acromioclavicular joint reconstruction, open excision, arthroscopic excision, and arthroscopic debridement [63].
• In a prospective randomized study of 17 patients undergoing open or indirect arthroscopic distal clavicle resection, preoperative magnetic resonance imaging was performed on all patients [24].
• In a prospective randomized study of 17 patients undergoing open or indirect arthroscopic distal clavicle resection, patients with concomitant shoulder pathology identified either clinically or radiographically before surgery were excluded [24].
• In a prospective randomized study of 17 patients undergoing open or indirect arthroscopic distal clavicle resection, patients with previous ipsilateral shoulder surgery or metabolic or neoplastic conditions of the shoulder were excluded [24].
• In a case of arthroscopic distal clavicle excision, an occult type I superior labrum anterior-posterior tear and a partial articular-side rotator cuff tear were seen and debrided [24].
• In a case of arthroscopic distal clavicle excision, a 7-mm probe was inserted into the acromioclavicular interval to assess the adequacy of bone resection [24].

Complications and Contraindications

• The primary factor influencing the reported incidence of subacromial osteolysis following hook plate fixation is the radiological assessment method [19].
• Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate [71].
• The case of Gorham-Stout disease as a complication of posterior shoulder capsulorrhaphy highlights the need to consider this diagnosis in patients presenting with massive osteolysis after shoulder surgery [7].

Complications

Diagnostic and Etiologic Considerations

• Propionibacterium acnes infection has been identified as a mediator of distal clavicular osteolysis [2].
• Gorham-Stout disease should be considered in patients presenting with massive osteolysis after shoulder surgery [7].
• Post-traumatic osteolysis of the pubic bone can simulate a malignant lesion, and the history of trauma may not be volunteered by the patient or may be elicited only by direct questioning [73].
• In post-traumatic osteolysis, radiographs made at the time of the original injury may be normal or unavailable, and the process of bone destruction may obscure the underlying fracture [73].

Surgical Complications and Outcomes

• Incomplete excision and regrowth of the distal clavicle are the most common causes of revision after acromioclavicular joint resection [11].
• Horizontal instability of the clavicle is evident with distal clavicle resection of greater than 10 mm [14].
• Clavicular tunnel widening was observed in 70% of patients at final follow-up after coracoclavicular stabilization surgery, with a higher prevalence in chronic than in acute cases [18].
• Asymptomatic ossification of the coracoclavicular ligaments was observed in patients with maintained anatomic reduction 15 years postoperatively [20].
• The minimally invasive TightRope system is associated with a reduced risk of subacromial distal clavicle osteolysis compared to the hook plate [79].

Recovery

• The combination of distal clavicle resection and antibiotics halted osteolysis in a patient with Propionibacterium acnes–mediated distal clavicular osteolysis [2].
• The patient with Propionibacterium acnes–mediated distal clavicular osteolysis remained symptom-free at 10 months after surgery [2].
• Patients undergoing arthroscopic distal clavicle excision through the direct approach can expect a faster return to activities compared with the open procedure [3].
• Arthroscopic distal clavicle excision through the direct approach obtains similar long-term outcomes compared with the open procedure [3].
• Late loss of reduction was common in patients with dislocation of the acromioclavicular joint [5].
• Simple excision of the outer end of the clavicle yielded satisfactory results in patients with complete dislocation and subluxation of the acromioclavicular joint [8].
• No residual upward displacement disturbing the patients was observed after simple excision of the outer end of the clavicle [8].
• Incomplete excision and regrowth of the distal clavicle are the most common causes of revision [11].
• Patients with displacement greater than 100% of the thickness of the distal clavicle had poorer postoperative clinical outcomes after acromioclavicular joint dislocation treated with the endobutton device [13].
• Partial claviculectomy is believed to be the best procedure for chronic symptomatic acromioclavicular joint injuries [16].
• Partial claviculectomy offers negligible morbidity for chronic symptomatic acromioclavicular joint injuries [16].
• Partial claviculectomy offers rapid return to function for chronic symptomatic acromioclavicular joint injuries [16].
• Clavicular tunnel widening was observed in 70% of patients at final follow-up after coracoclavicular stabilization surgery [18].
• The prevalence of clavicular tunnel widening was higher in chronic than in acute cases [18].
• Good clinical results persisted 15 years postoperatively after arthroscopically assisted 2-bundle anatomic reduction of acute acromioclavicular joint separations [20].
• Anatomic reduction was overall maintained 15 years postoperatively after arthroscopically assisted 2-bundle anatomic reduction of acute acromioclavicular joint separations [20].
• Asymptomatic ossification of the coracoclavicular ligaments was often observed 15 years postoperatively after arthroscopically assisted 2-bundle anatomic reduction of acute acromioclavicular joint separations [20].
• Satisfactory outcome for fracture clavicle with acromioclavicular dislocation depends upon restoring the stability of the clavicle as well as the acromioclavicular joint [30].
• Excellent radiologic and clinical results were observed in short-term follow-up of 15 patients treated with minimally invasive coracoclavicular ligament augmentation for total acromioclavicular joint dislocation [31].
• No subluxations or dislocations of the acromioclavicular joint were noted in the short-term follow-up of 15 patients treated with minimally invasive coracoclavicular ligament augmentation [31].
• Total claviculectomy yielded good results for patients with chronic osteitis and malignancy [32].
• Total claviculectomy yielded unsatisfying results for patients with chronic posttraumatic pain [32].
• Full range of motion was regained in all cases of total claviculectomy [32].
• Radiological assessment showed a statistically significant immediate superior clavicular displacement after hardware removal following acromioclavicular joint stabilization using a suspensory fixation system [33].
• There was an increased incidence of immediate superior clavicular displacement in the first year following stabilization [33].
• Immediate superior clavicular displacement after hardware removal may not negatively influence the results of acromioclavicular joint stabilization in a clinically relevant way [33].
• A majority of patients with untreated acute grade III acromioclavicular separation will do well without any formal treatment [82].
• A small percentage of patients with untreated acute grade III acromioclavicular separation may require delayed surgical intervention [82].

Key Evidence

• [L4] Clinical signs and symptoms for atraumatic distal clavicular osteolysis (ADCO) were not distinguishable from other shoulder pathologies. [1] (10.1177/17585732261479715)
• [Case_report] The combination of distal clavicle resection and antibiotics halted the osteolysis, and the patient has remained symptom free at 10 months after surgery. [2] (10.1016/j.jse.2015.03.004)
• [L3] Among patients undergoing distal clavicle excision for acromioclavicular joint pathology, those having an arthroscopic procedure, specifically through the direct approach, can expect a faster return to activities while obtaining similar long-term outcomes compared with the open procedure. [3] (10.1016/j.arthro.2009.12.007)
• [L3] Arthroscopic distal clavicle resection has provided more 'good or excellent' results than has the open procedure, but is comprised of low-level evidence. [4] (10.1097/blo.0b013e31802f5450)
• [L3] Late loss of reduction was common, and clavicular resection reliably produced significant improvement in patients with persistent pain or posttraumatic arthritis. [5] (10.2106/00004623-198769070-00013)
• [L5] In appropriately selected patients, open or arthroscopic distal clavicle resection is necessary to relieve symptoms. [6] (10.5435/00124635-199905000-00004)
• [L4] The case highlights the need to consider this diagnosis in patients presenting with massive osteolysis after shoulder surgery. [7] (10.1016/j.jse.2012.05.024)
• [L5] A well-performed distal clavicle excision will likely perform better than a poorly performed one, regardless of whether an open or arthroscopic approach is chosen. [9] (10.1016/j.arthro.2018.03.004)
• [L4] Incomplete excision and regrowth of the distal clavicle are the most common causes of revision. [11] (10.1016/j.arthro.2009.06.010)
• [L5] Retaining the clavicular hook-plate indefinitely carries a potential risk of developing osteolysis and fracture around the implant. [12] (10.1016/j.injury.2004.08.010)
• [L3] Patients with displacement greater than 100% of the thickness of the distal clavicle had poorer postoperative clinical outcomes. [13] (10.1186/s12891-025-09190-x)
• [L4] Horizontal instability of the clavicle is evident with distal clavicle resection of greater than 10 mm. [14] (10.1016/j.xrrt.2021.05.003)
• [L4] Excision of the outer end of the clavicle is preferred for old dislocations, while open reduction and internal fixation are not recommended due to complications and poor functional results. [15] (10.2106/00004623-196345080-00024)
• [L4] Methods to diagnose both superior and posterior translation of the clavicle need further debate. [17] (10.1016/j.jseint.2019.11.006)
• [L1] Clavicular tunnel widening was observed in 70% of patients at final follow-up, with a higher prevalence in chronic than in acute cases. [18] (10.1016/j.jse.2023.09.037)
• [L1] Subacromial osteolysis has a relatively high and variable incidence, and the primary factor influencing the reported incidence is the radiological assessment method. [19] (10.1016/j.jse.2024.03.018)
• [L3] Fifteen years postoperatively, good clinical results persisted and anatomic reduction was overall maintained, often with asymptomatic ossification of the coracoclavicular ligaments. [20] (10.1177/03635465251355958)
• [L4] [23] (10.1177/1758573220905573)
• [L1] [24] (10.1016/j.jse.2006.10.006)
• [L2] Routine distal clavicle excision is not absolutely necessary, even in patients with symptomatic ACJ osteoarthritis. [25] (10.1007/s00167-020-06098-y)
• [Case_report] The case highlights that segmental fractures of the clavicle are easily missed. [26] (10.1177/1758573214564496)
• [Case_report] Total claviculectomy is a possible treatment option for chronic clavicular dislocation with excellent outcomes and high patient satisfaction. [27] (10.1016/j.xrrt.2021.03.007)
• [L4] [28] (10.2106/00004623-196749040-00024)
• [L4] Excellent clinical results were achieved, decreasing the risk of recurrent distal clavicle instability. [29] (10.1186/1471-2474-10-6)
• [L4] Satisfactory outcome depends upon restoring the stability of the clavicle as well as the acromioclavicular joint. [30] (10.1111/j.1758-5740.2010.00102.x)
• [L4] The short-term follow-up of 15 recently operated patients reveals excellent radiologic and clinical results, with no subluxations or dislocations of the acromioclavicular joint noted. [31] (10.1016/j.arthro.2006.12.015)
• [L4] Total claviculectomy yielded good results for patients with chronic osteitis and malignancy but unsatisfying results for those with chronic posttraumatic pain, despite full range of motion being regained in all cases. [32] (10.1016/j.jse.2006.07.007)
• [L4] Although radiological assessment showed a statistically significant immediate superior clavicular displacement after this rarely required procedure, with an increased incidence in the first year following stabilization, this may not negatively influence the results of ACJ stabilization in a clinically relevant way. [33] (10.1007/s00167-022-06978-5)
• [L5] Despite technology innovations, a precise, easy to use and low-cost non-invasive method able to draw and analyze the kinematics of the shoulder complex has not been developed yet. [35] (10.1177/17585732221090226)
• [L5] The trapezoid and conoid ligaments have unique functions in normal shoulder kinematics because of their anatomic attachments. [42] (10.1016/j.arthro.2009.12.031)
• [L5] The kinematic changes could be a potential source of pain and dysfunction in the shoulder with AC joint dislocation. [43] (10.1177/0363546512458571)
• [L5] Scapular and clavicular kinematics were affected in AC separation models. [46] (10.1016/j.jse.2013.01.004)
• [L4] The inconsistency of AC joint testing parameters and the lack of thorough translation studies indicate a necessity for increased attention in the overall assessment of shoulder stability to close the gap in the foundational biomechanical research. [50] (10.1016/j.xrrt.2024.06.009)
• [L5] Anatomically, it provides sufficient tissue length, excursion, and width, and biomechanically, it is as strong as the coracoacromial ligament. [51] (10.1016/j.jse.2006.09.007)
• [L4] Type I and II acromioclavicular joint disruptions impair long-term shoulder function in about half of patients 10 years after injury. [60] (10.1177/0363546508319047)
• [L5] At 150 to 200 N of loading, CAL excision and acromioplasty increase the rotator cuff force required to maintain normal glenohumeral biomechanics by 25% to 30%. [61] (10.1016/j.jse.2015.10.022)
• [L2] [63] (10.1177/1758573217700839)
• [L1] [67] (10.1097/corr.0000000000002545)
• [L4] [68] (10.1177/17585732231157090)
• [L1] [70] (10.1016/j.jse.2020.10.026)
• [L4] Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate. [71] (10.1186/s12891-021-04841-1)
• [L4] [73] (10.2106/00004623-198466070-00034)
• [L4] [74] (10.2106/00004623-197254060-00005)
• [L4] Weighted stress radiographs significantly increased the measured elevation of the clavicle and the coracoclavicular distance compared to non-weighted views. [75] (10.1016/j.jseint.2023.06.011)
• [L5] [76] (10.1016/j.jse.2010.10.030)
• [L5] The ISAKOS Upper Extremity Committee suggests adding grade IIIA and grade IIIB injuries to a modified Rockwood classification to distinguish between stable type III injuries and unstable grade III injuries with therapy-resistant scapular dysfunction and overriding clavicle. [78] (10.1016/j.arthro.2013.11.005)
• [L3] However, the minimally invasive TightRope system showed further benefits such as reduced reoperation for implant removal and reduced risk of subacromial distal clavicle osteolysis. [79] (10.1155/2022/8706638)
• [L4] A high index of suspicion is needed to diagnose such complications early before irretrievable bone loss to osteolysis. [81] (10.1111/sae.12035)
• [L2] A majority of patients with untreated acute grade III acromioclavicular separation will do well without any formal treatment, though a small percentage may require delayed surgical intervention. [82] (10.1177/03635465010290060401)

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