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肩锁关节骨关节炎

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AC joint osteoarthritis causes localized shoulder pain with cross-body movements; treatment ranges from activity modification to surgery.

Updated Aug 2026
一幅手绘插图，展示了肩部顶端磨损的骨关节炎性肩锁关节（AC joint）。
左肩前视图，显示锁骨与肩胛骨肩峰相接的肩锁（AC）关节，以及周围的韧带和更深层的盂肱关节。 Kieran Hirpara 4.0

本页面由机器翻译，尚未经临床医生审核。英文版本为权威版本。

您的感受

您可能会在肩膀顶部感到尖锐或钝痛。这是锁骨与肩胛骨相接的位置。按压该区域时会有压痛。您可能会注意到该区域有肿胀或一个小肿块。

当您将手臂横过身体时，疼痛通常会加重。简单的日常任务可能会变得困难。将手伸到背后扣文胸或塞衬衫可能会引起疼痛。将物体举过头顶或从高处架子上取物可能会引发不适。患侧卧位睡眠通常会引起疼痛，并可能干扰您的休息。

您醒来时可能会感到僵硬。这种僵硬通常在白天活动时缓解。然而，在长时间活动后，酸痛可能会再次出现。有些人发现休息手臂有帮助，而另一些人发现轻微活动能提供更多缓解。

重要的是要知道，并非所有X线片上有改变的人都会感到疼痛。事实上，在7年期间，90%的无症状退行性关节炎患者保持无症状。如果您没有症状，您的外科医生可能不会建议手术。即使您正在进行其他肩部手术，如肩袖修复术，未治疗的无痛性关节炎与较低的失败率相关。

您的外科医生将专注于治疗您实际感受到的疼痛，而不仅仅是影像上显示的内容。有症状和无症状的影像学改变之间的区别是不必要的，因为无论X线表现如何，患者对注射等治疗的满意度是相同的。如果保守治疗无效，您的外科医生可能会讨论手术选项。开放性和关节镜下切除技术均能为有症状的病例提供可预测的疼痛缓解。

实际情况

您的肩锁关节位于肩部顶端，即锁骨与肩胛骨相接处。可将其视为一个坚固的小铰链，使您的手臂能够平滑运动。随着时间的推移，骨端的光滑覆盖层——称为软骨——可能会磨损。这就是骨关节炎，也称为退行性关节炎。当这层保护性结构变薄时，骨骼可能会相互摩擦，导致疼痛和僵硬。

这种退行性过程非常常见。它往往在毫无预警的情况下发生。事实上，在7年的观察期内，90%的无症状肩锁关节骨关节炎（AC-OA）患者仍保持无症状。这意味着对于大多数人来说，X光片上可见的变化并不会自动引起疼痛或限制活动。您可能在影像检查中发现关节炎，但自身感觉毫无异样。

有时，这种关节问题是在治疗其他肩部问题时发现的。例如，在关节镜下肩袖修复术中遇到的未治疗的肩锁关节（ACJ）骨关节炎，无论是否有症状，其失败率均较低。这表明该关节存在关节炎通常不会破坏其他肩部手术的效果。然而，在某些情况下，严重的肩锁关节骨关节炎与反式肩关节置换术后的肩峰应力性骨折有关。您的外科医生会在任何手术前评估这些风险。

当该关节确实引起症状时，通常是因为其周围结构承受了压力。关节囊是包裹肩部并将所有结构固定在一起的袖状组织。如果稳定该区域的韧带被拉伸或受损，关节可能会发生轻微移位。这种错位会改变肩胛骨的运动方式，从而导致疼痛和功能障碍。

您的外科医生理解，并非所有关节炎都需要手术。开放性和关节镜下切除成形术技术均能为有症状的肩锁关节骨关节炎提供可预测的疼痛缓解。这些手术涉及切除一小部分骨骼以创造更多空间。这有助于减少摩擦并允许更平滑的运动。其目标是在保持肩部功能的同时缓解您的疼痛。

我们能做什么

在罗克汉普顿 Mater 私人医院，Kieran Hirpara 医生根据您的具体症状和生活方式为您匹配治疗方案。我们从创伤最小的选项开始，尝试在不进行手术的情况下管理您的疼痛。这种循序渐进的方法有助于您避免不必要的程序，同时让肩部获得最好的自然愈合机会。

对于许多人来说，简单的改变就能带来显著差异。您可能需要调整会引起疼痛的活动，例如提重物或向上伸手。物理治疗是这一过程的关键部分。我们的治疗师将指导您进行锻炼，以增强肩胛骨和上臂周围肌肉的力量。这种支撑可以减轻关节的压力。我们通常建议尝试一段时间的保守治疗，以观察是否能减轻您的不适。如果您患有磨损性关节炎，调整手臂的使用方式可以帮助更长时间地控制症状。

如果自我管理和治疗未能提供足够的缓解，我们可能会讨论医疗选项。止痛药和抗炎药可以帮助控制肿胀和酸痛。我们还提供关节内注射。这些注射将药物直接送达疼痛源，以减轻炎症。研究表明，这些注射在肩锁关节骨关节炎患者中的1年成功率为47%。这意味着近一半的患者在一年内找到显著的缓解，尽管结果因人而异。我们使用这些注射来帮助您可以保持活跃并继续进行康复。

只有在保守治疗未能带来足够改善时，才会考虑手术。最常见的程序是远端锁骨切除术。在此手术中，我们切除锁骨末端的一小部分，以防止其摩擦肩胛骨。这创造了更多空间并减轻疼痛。我们推荐给那些尽管尝试其他治疗但疼痛持续存在的患者。对于韧带撕裂的急性损伤或慢性脱位，我们可能会建议重建以恢复稳定性。我们会与您讨论所有选项，以确保选择符合您的目标和健康需求。

预期情况

您的预后主要取决于症状是处于活动期还是静止期。如果您在肩锁关节（AC joint）存在磨损性关节炎但无疼痛，这种情况通常会保持不变。在90%的患者中，无症状的关节炎在7年随访期间仍保持无症状。如果它没有给您带来困扰，您可能不需要任何治疗。

如果您确实有疼痛，保守治疗通常是第一步。注射治疗可以提供帮助，但并非永久性的解决方案。肩锁关节注射的1年成功率为47%。这意味着近一半的患者能获得一年的缓解，而其他患者可能需要进一步的治疗选择。如果休息和药物治疗后疼痛仍然持续，手术是一个可选方案。

手术旨在去除锁骨受刺激的部位。这可为有症状的肩锁关节骨关节炎提供可预测的疼痛缓解。在中期随访中，开放技术和关节镜技术均能有效减轻疼痛并改善肩部功能。您可以预期疼痛减轻且活动更加自如。然而，在翻修病例中，持续性疼痛和骨关节炎进展仍是需要关注的问题。

重要的是要知道，关节炎可能会影响其他肩部手术。在进行关节镜下肩袖修复术时，无论是否有症状，未治疗的肩锁关节骨关节炎均与较低的失败率相关。此外，骨关节炎还与肩袖修复术后较差的最终临床结果相关。未愈合或再次撕裂的肩袖会增加发生骨关节炎的风险。

如果您患有严重关节炎，还有额外的风险需要考虑。严重的肩锁关节骨关节炎与反向肩关节置换术后肩峰应力性骨折相关。接受此类手术的患者中，影像学显示的肩锁关节骨关节炎很常见。您的外科医生在制定治疗方案时会权衡这些因素。

总体而言，病程因人而异。许多人无需手术即可良好控制病情。另一些人则在切除问题骨骼后获得持久的缓解。您的外科医生将帮助您决定哪种路径最适合您的生活状况和症状。

何时就医

若您的肩部顶部出现持续性疼痛且休息后未改善，请咨询您的全科医生（GP）。若发现无力、不稳感，或有卡住或突然无力的感觉，请要求专科医生进行会诊。若症状影响您的睡眠或工作职责，或疼痛突然加重，请及时就医。尽管许多退行性关节炎病例在多年内无明显疼痛，但持续不适仍需进行评估。您的外科医生可帮助判断是否需要进一步治疗以有效控制您的症状。

Reviewed by Dr Kieran Hirpara · 7 August 2026.

Talk to your treating clinician for advice specific to you.

For an appointment with the CQ Hand + Upper Limb team, ask your GP about a referral or visit www.cqupperlimb.com.

Evidence & references

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

  • Asymptomatic AC-OA remained asymptomatic in 90% of patients over a 7-year period [2].
  • Untreated ACJ osteoarthritis, whether symptomatic or not, encountered during arthroscopic rotator cuff repair is associated with a low percentage of failure [3].
  • Radiographic ACJ osteoarthritis is common in patients undergoing reverse shoulder arthroplasty [7].
  • Severe acromioclavicular joint osteoarthritis is associated with acromial stress fractures after reverse shoulder arthroplasty [7].
  • Both open and arthroscopic resection arthroplasty techniques provide predictable pain relief for symptomatic AC osteoarthritis [8].
  • Open and arthroscopic resection arthroplasty techniques have unique sets of potential complications that may be minimized with improved understanding of anatomy, biomechanics, and meticulous surgical technique [8].
  • Limited distal clavicle excision reduced pain and improved shoulder function at midterm follow-up in patients with AC joint osteoarthritis resistant to conservative treatment [9].
  • A distinction between symptomatic and asymptomatic radiographic AC OA is unnecessary as all patients were equally satisfied with the outcome of preoperative acromioclavicular injection [6].
  • Further characterisation of patients in whom mild arthroscopic findings of OA of the AC joint are clinically significant and warrant resection is needed [1].
  • Acromioclavicular joint arthritis is not an indication for routine distal clavicle excision in arthroscopic rotator cuff repair [3].
  • Clinicians should consider overreduction of the AC joint because it may lead to favorable radiological results [5].
  • The authors recommend anatomic reconstruction procedures for the treatment of chronic complete AC dislocations [21].

Anatomy & Pathophysiology

  • Anatomic techniques that address both coracoclavicular ligaments and the AC capsule are recommended to restore horizontal and vertical stability while allowing physiological rotation [10].
  • None of the reconstruction strategies completely restored the shoulder girdle to its preinjured state [26].
  • Kinematic changes resulting from AC joint dislocation could be a potential source of pain and dysfunction in the shoulder [27].
  • Scapular and clavicular kinematics were affected in AC separation models [28].
  • The position of the hook portion of a clavicle hook plate can predispose anatomic structures to post-operative complications of subacromial impingement and bony erosion [29].
  • Future research should focus on addressing horizontal and rotational instability to restore native physiological and biomechanical properties of the AC joint [35].
  • Coracoclavicular reconstruction with augmentation of the acromioclavicular joint provides improved horizontal stability compared to isolated coracoclavicular reconstruction [41].
  • Adding a fixation of the AC joint minimizes lateral tilting of the scapula and maintains a more anatomic reposition result over time [45].

Classification

  • Asymptomatic acromioclavicular osteoarthritis diagnosed by MRI remained asymptomatic in 90% of patients over a 7-year period [2].
  • Untreated acromioclavicular joint osteoarthritis, whether symptomatic or not, encountered during arthroscopic rotator cuff repair is associated with a low percentage of failure [3].
  • Mild arthroscopic findings of acromioclavicular joint osteoarthritis may be clinically significant and warrant resection, but further characterization of such patients is needed [1].
  • Radiographic acromioclavicular joint osteoarthritis is common in patients undergoing reverse shoulder arthroplasty [7].
  • Osteolytic changes in the acromioclavicular joint seemed to be associated with incongruity of the joint but did not correlate with clinical results [11].
  • The acromial center line to dorsal clavicle radiographic measurement and the use of the Alexander view provide a more realistic appreciation of true acromioclavicular joint displacement, especially in defining watershed cases (Rockwood types IIIA, IIB, and IV) [12].
  • Evaluating the integrity of the capsuloligamentous structures stabilizing the acromioclavicular joint is reproducible and provides additional information on the severity of the injury [24].
  • Injuries to the sternoclavicular joint are uncommon, and recognition and classification are critical to proper management to minimize long-term sequelae [16].
  • Some persistent pain and osteoarthritis progression remain concerns in the arthroscopic revision of failed open anterior stabilization of the shoulder [4].

Clinical Presentation

  • Preventive arthroscopic distal clavicle resection is not recommended in patients with radiological but asymptomatic ACJ arthritis [19].
  • Osteolytic changes seemed to be associated with incongruity of the AC joint, but did not correlate with clinical results [11].
  • Additional research is needed to determine the main cause of pain in isolated acromioclavicular osteoarthritis and to compare clinical outcomes of intra-articular versus extra-articular injections [13].
  • Risk factors for subsequent distal clavicle excision after rotator cuff repair include tenderness to palpation at the AC joint, female sex, and surgery on the dominant side [18].
  • Subsequent distal clavicle excision was performed in 40% of cases with a combination of the three identified risk factors (tenderness to palpation, female sex, dominant side surgery) [18].
  • Recurrence of the initial dislocation after arthroscopically assisted reduction appears to be related to the onset of degenerative ACJ arthropathy [14].
  • Some persistent pain and osteoarthritis progression remain concerns in the revision of failed open anterior stabilization of the shoulder [4].

Investigations

  • Preventive arthroscopic distal clavicle resection (DCR) is not recommended in patients with radiological but asymptomatic ACJ arthritis [19].
  • Further characterization is needed to determine which patients with mild arthroscopic findings of AC joint OA are clinically significant and warrant resection [1].
  • Radiographic ACJ osteoarthritis is common in patients undergoing reverse shoulder arthroplasty (RSA) [7].
  • Severe ACJ osteoarthritis is associated with acromial stress fractures after reverse shoulder arthroplasty [7].
  • Osteolytic changes in the AC joint seemed to be associated with incongruity but did not correlate with clinical results [11].
  • Patients with edema on MRI were more likely to present with pain than patients without edema [43].
  • Subchondral bone edema on histologic examination was more frequent in patients with pain [43].
  • The outcomes of a preoperative AC injection suggest that a distinction between symptomatic and asymptomatic radiographic AC OA is unnecessary, as all patients were equally satisfied with the outcome [6].
  • Additional research is needed to determine the main cause of pain and to compare clinical outcomes of intra-articular versus extra-articular steroid injections for isolated AC osteoarthritis [13].
  • Subsequent distal clavicle excision was performed in 40% of cases with a combination of the three identified risk factors (tenderness, female sex, dominant side) [18].
  • The arthroscopic approach offers an advantage in diagnosing and treating occult intra-articular pathology during distal clavicle excision [20].
  • Some persistent pain and osteoarthritis progression remain concerns in the revision of failed open anterior stabilization of the shoulder using arthroscopy [4].
  • Evaluating the integrity of the capsuloligamentous structures stabilizing the AC joint is reproducible and provides additional information on injury severity, which may influence treatment decisions [24].
  • The AC-DC measurement and use of the Alexander view provide a more realistic appreciation of true AC joint displacement, particularly in defining watershed cases (IIIA/IIB/IV) [12].
  • Radiological failures were observed in 41% of cases in a prospective multicenter study of arthroscopic acute AC dislocation fixation [50].

Treatment

Non-Operative Management

  • Conservative therapy is a valid initial treatment option for Rockwood Type V acromioclavicular dislocations [15].
  • Non-operative reduction and stabilization is a valuable treatment option for acute high-grade acromioclavicular joint separations [33].
  • Nonoperative treatment is helpful for most patients with painful conditions of the acromioclavicular joint, although those with osteolysis may need to modify their activities [44].
  • Conservative and surgical treatments are both effective in the management of acromioclavicular joint osteoarthritis [17].
  • Acromioclavicular injections offer a 1-year success rate of 47% in patients with acromioclavicular osteoarthritis [22].
  • Additional research is needed to determine the main cause of pain and to compare clinical outcomes of intra-articular versus extra-articular steroid injections for isolated acromioclavicular osteoarthritis [13].

Operative Management

  • Both open and arthroscopic resection arthroplasty techniques provide predictable pain relief for symptomatic acromioclavicular osteoarthritis [8].
  • Limited distal clavicle excision reduces pain and improves shoulder function at midterm follow-up in patients with acromioclavicular joint osteoarthritis resistant to conservative treatment [9].
  • Further characterization is needed to identify patients in whom mild arthroscopic findings of acromioclavicular joint osteoarthritis are clinically significant and warrant resection [1].
  • Conversion to anatomic coracoclavicular ligament reconstruction shows similar clinical outcomes compared to successful non-operative treatment in chronic primary type III to V acromioclavicular joint injuries at a minimum 5-year follow-up [49].
  • The authors recommend anatomic reconstruction procedures for the treatment of chronic complete acromioclavicular dislocations [21].
  • Osteoarthritis is associated with poorer final clinical outcomes after rotator cuff repair, and an unhealed or re-torn cuff increases the risk of osteoarthritis [23].

Diagnostic Considerations

  • A distinction between symptomatic and asymptomatic radiographic acromioclavicular osteoarthritis appears unnecessary, as all patients were equally satisfied with the outcome of preoperative acromioclavicular injection [6].
  • Asymptomatic acromioclavicular osteoarthritis diagnosed by MRI remained asymptomatic in 90% of patients over a 7-year course [2].
  • Some persistent pain and osteoarthritis progression remain concerns following arthroscopy in the revision of failed open anterior stabilization of the shoulder [4].

Complications

  • Osteoarthritis is associated with poorer final clinical outcomes after rotator cuff repair [23].
  • An unhealed or re-torn rotator cuff increases the risk of developing osteoarthritis [23].
  • Severe AC joint osteoarthritis is associated with acromial stress fractures after reverse shoulder arthroplasty [7].
  • Some persistent pain and osteoarthritis progression remain concerns following arthroscopy in revision of failed open anterior stabilization of the shoulder [4].
  • Recurrence of the initial dislocation after arthroscopically assisted reduction of acute AC joint dislocation appears to be related to the onset of degenerative ACJ arthropathy [14].
  • Treatment of acute grade III and IV AC dislocations by synthetic ligament reconstruction carries a risk of significant early osteolysis [25].
  • Open and arthroscopic AC joint reconstruction techniques have no differences in loss of reduction, complication rate, or revision rate [38].
  • Both open and arthroscopic resection arthroplasty techniques provide predictable pain relief for symptomatic AC osteoarthritis but each has a unique set of potential complications [8].

Recovery

  • Limited distal clavicle excision for acromioclavicular joint osteoarthritis resistant to conservative treatment reduced pain and improved shoulder function at midterm follow-up [9].
  • A preoperative acromioclavicular injection study suggested that distinguishing between symptomatic and asymptomatic radiographic acromioclavicular osteoarthritis is unnecessary, as all patients were equally satisfied with the outcome [6].
  • Osteolytic changes in the acromioclavicular joint seemed to be associated with incongruity but did not correlate with clinical results [11].
  • Recurrence of initial acromioclavicular joint dislocation appears to be related to the onset of degenerative acromioclavicular joint arthropathy [14].
  • Treatment of acute grade III and IV acromioclavicular dislocations using synthetic ligament reconstruction gave satisfactory results in terms of recovery of strength, but evolution is not risk-free due to the onset of significant early osteolysis [25].
  • Arthroscopic coracoclavicular ligament reconstruction with double-bundle soft tissue allograft for chronic type V acromioclavicular dislocations showed sustained and statistically significant improvements in functional outcomes, high rates of return to sport, and maintenance of active-duty military status at minimum 10-year follow-up [39].
  • Minimally invasive coracoclavicular ligament augmentation with a flip button/polydioxanone repair for total acromioclavicular joint dislocation revealed excellent radiologic and clinical results with no subluxations or dislocations noted in short-term follow-up [48].
  • Type V acromioclavicular dislocations may be given a trial of conservative therapy [15].

Key Evidence

  • [L2] Further characterisation of patients in whom mild arthroscopic findings of OA of AC joint are clinically significant and warrant resection is needed. [1] (10.1007/s00167-014-3114-2)
  • [L2] Asymptomatic AC-OA remained asymptomatic in 90% over 7 years. [2] (10.1016/j.jse.2019.04.004)
  • [L2] Untreated ACJ osteoarthritis, symptomatic or not, encountered during arthroscopic RCR is associated with a low percentage of failure. [3] (10.1007/s00167-020-06098-y)
  • [L4] Some persistent pain and osteoarthritis progression remain concerns. [4] (10.1016/j.arthro.2009.04.073)
  • [L3] Clinicians should consider overreduction of the AC joint because it may lead to favorable radiological results. [5] (10.1177/0363546519862850)
  • [L4] The outcomes of this study seem to suggest that a distinction between symptomatic and asymptomatic radiographic AC OA is unnecessary, as all patients were equally satisfied with the outcome. [6] (10.5397/cise.2023.00073)
  • [L3] Radiographic ACJ osteoarthritis is common in patients undergoing RSA. [7] (10.1016/j.jseint.2021.11.008)
  • [L5] Both open and arthroscopic resection arthroplasty techniques provide predictable pain relief for symptomatic AC osteoarthritis, though each has a unique set of potential complications that may be minimized with improved understanding of anatomy, biomechanics, and meticulous surgical technique. [8] (10.1177/0363546513485359)
  • [L4] Limited distal clavicle excision of patients with AC joint osteoarthritis resistant to conservative treatment reduced pain and improved shoulder function at midterm follow-up. [9] (10.1016/j.otsr.2016.01.008)
  • [L5] Anatomic techniques that address both coracoclavicular ligaments and the AC capsule are recommended to restore horizontal and vertical stability while allowing physiological rotation. [10] (10.1016/j.arthro.2019.01.038)
  • [L4] The AC-DC measurement and use of the Alexander view provides the clinician with a more realistic appreciation of true AC joint displacement, especially in defining watershed cases (ie, IIIA/IIB/IV) and may better inform the decision-making process regarding management options and recommendations. [12] (10.1016/j.jse.2019.12.014)
  • [L4] Additional research is needed to determine the main cause of pain and compare clinical outcomes of intra-articular versus extra-articular injections. [13] (10.5397/cise.2023.00311)
  • [L4] Recurrence of the initial dislocation appears to be related to onset of degenerative ACJ arthropathy. [14] (10.1016/j.otsr.2017.11.001)
  • [L4] This suggests that Type V AC dislocations may be given a trial of conservative therapy. [15] (10.1177/2325967115s00017)
  • [L1] Injuries to the SC joint are uncommon, and recognition and classification are critical to proper management to minimize long-term sequelae. [16] (10.1177/0363546513498990)
  • [L4] Conservative and surgical treatments are both effective in acromioclavicular joint osteoarthritis management. [17] (10.1007/s00167-020-06377-8)
  • [L3] Risk factors for subsequent DCE included tenderness to palpation at the AC joint, female sex, and surgery on the dominant side, with subsequent DCE performed in 40% of cases with a combination of these 3 factors. [18] (10.1177/2325967119844295)
  • [L1] Preventive arthroscopic DCR is not recommended in patients with radiological but asymptomatic ACJ arthritis. [19] (10.1177/0363546514547254)
  • [L1] The arthroscopic approach offers a unique advantage in diagnosing and treating occult intra-articular pathology. [20] (10.1016/j.jse.2006.10.006)
  • [L4] The authors recommend this procedure for the treatment of chronic complete AC dislocations. [21] (10.1016/j.injury.2010.09.023)
  • [L4] AC injections offer a 1-year success rate of 47%. [22] (10.5397/cise.2023.00031)
  • [L4] Osteoarthritis is associated with poorer final clinical outcomes, and an unhealed or re-torn cuff increases the risk of osteoarthritis. [23] (10.1016/j.otsr.2017.03.007)
  • [L1] Evaluating the integrity of the capsuloligamentous structures stabilizing the AC joint is reproducible and gives additional information on the severity of the injury, which might also influence the treatment decision. [24] (10.1016/j.jse.2020.10.026)
  • [L4] Treatment of ACD by synthetic ligament reconstruction gave satisfactory results, notably in terms of recovery of strength, but evolution is not risk-free with onset of significant early osteolysis. [25] (10.1016/j.otsr.2010.06.004)
  • [L5] Although each technique was able to restore different elements of the joint kinematics, none of the strategies completely restored the shoulder girdle to its preinjured state. [26] (10.1177/03635465221095231)
  • [L5] The kinematic changes could be a potential source of pain and dysfunction in the shoulder with AC joint dislocation. [27] (10.1177/0363546512458571)
  • [L5] Scapular and clavicular kinematics were affected in AC separation models. [28] (10.1016/j.jse.2013.01.004)
  • [L5] The observed frequency of hook contact with surrounding subacromial structures in a static shoulder confirms that the position of the hook portion of the implant can predispose anatomic structures to the post-operative complications of subacromial impingement and bony erosion. [29] (10.1016/j.injury.2009.12.012)
  • [L4] Non-operative reduction and stabilization of high-grade AC joint separations seems to be a valuable treatment option. [33] (10.1007/s00402-020-03630-0)
  • [L5] Future research should focus on addressing horizontal and rotational instability, to restore native physiological and biomechanical properties of the AC joint. [35] (10.1186/s12891-022-05935-0)
  • [L1] Open and arthroscopic AC joint reconstruction techniques have no differences in loss of reduction, the complication rate, and the revision rate based on the available literature. [38] (10.1177/0363546518795147)
  • [L4] Outcomes after arthroscopic CC reconstruction for chronic, type V AC dislocations in an active-duty military patient population show sustained and statistically significant improvements in functional outcomes as well as high rates of return to sport and maintenance of active-duty military status at long-term follow-up. [39] (10.1016/j.arthro.2025.05.008)
  • [L1] Coracoclavicular reconstruction with augmentation of the acromioclavicular joint has been shown to provide improved horizontal stability in both biomechanical and clinical studies compared to isolated coracoclavicular reconstruction. [41] (10.1007/s00167-018-5152-7)
  • [L4] Patients with edema on MRI were more likely to present pain than patients without edema, and subchondral bone edema on histologic examination was more frequent in patients with pain. [43] (10.1016/j.jseint.2020.03.007)
  • [L5] Nonoperative treatment is helpful for most patients, although those with osteolysis may have to modify their activities. [44] (10.5435/00124635-199905000-00004)
  • [L3] The presented data suggest adding a fixation of the AC joint to minimize lateral tilting of the scapula and maintain a more anatomic reposition result over time. [45] (10.1007/s00402-021-03761-y)
  • [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. [48] (10.1016/j.arthro.2006.12.015)
  • [L4] At a minimum 5-year follow-up, patients with successful non-operative treatment for type III-V ACJ injuries achieved similar clinical outcomes compared to those who were converted to ACCR. [49] (10.1007/s00167-020-06159-2)
  • [L4] Surgery for AC dislocations is difficult with radiological results that must still be improved, as radiological failures were observed in 41% of cases. [50] (10.1016/j.otsr.2015.09.012)

References

[1] Outcome of distal clavicle resection in patients with acromioclavicular joint osteoarthritis and full‐thickness rotator cuff tear. Knee Surgery, Sports Traumatology, Arthroscopy. 2014. DOI: 10.1007/s00167-014-3114-2

[2] Seven-year course of asymptomatic acromioclavicular osteoarthritis diagnosed by MRI. Journal of Shoulder and Elbow Surgery. 2019. DOI: 10.1016/j.jse.2019.04.004

[3] Acromioclavicular joint arthritis is not an indication for routine distal clavicle excision in arthroscopic rotator cuff repair. Knee Surgery, Sports Traumatology, Arthroscopy. 2020. DOI: 10.1007/s00167-020-06098-y

[4] The Role of Arthroscopy in Revision of Failed Open Anterior Stabilization of the Shoulder. Arthroscopy. 2009. DOI: 10.1016/j.arthro.2009.04.073

[5] Factors Predicting the Outcome After Arthroscopically Assisted Stabilization of Acute High-Grade Acromioclavicular Joint Dislocations. The American Journal of Sports Medicine. 2019. DOI: 10.1177/0363546519862850

[6] Diagnostic value of a preoperative acromioclavicular injection for symptomatic acromioclavicular osteoarthritis: a retrospective study of cross-sectional midterm outcomes. Clinics in Shoulder and Elbow. 2024. DOI: 10.5397/cise.2023.00073

[7] Severe acromioclavicular joint osteoarthritis is associated with acromial stress fractures after reverse shoulder arthroplasty. JSES International. 2022. DOI: 10.1016/j.jseint.2021.11.008

[8] Degenerative Joint Disease of the Acromioclavicular Joint. The American Journal of Sports Medicine. 2013. DOI: 10.1177/0363546513485359

[9] Limited distal clavicle excision of acromioclavicular joint osteoarthritis. Orthopaedics & Traumatology: Surgery & Research. 2016. DOI: 10.1016/j.otsr.2016.01.008

[10] Editorial Commentary:

                Why We Have To Respect The Anatomy In Acromioclavicular Joint Surgery And Why Clinical Shoulder Scores Might Not Give Us The Information We Need!. *Arthroscopy*. 2019. DOI: 10.1016/j.arthro.2019.01.038

[11] Surgical treatment of acromioclavicular dislocation: A review of 39 patients. Injury. 1983. DOI: 10.1016/0020-1383(83)90092-x

[12] Improved identification of unstable acromioclavicular joint injuries in a clinical population using the acromial center line to dorsal clavicle radiographic measurement. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2019.12.014

[13] Isolated acromioclavicular osteoarthritis and steroid injection. Clinics in Shoulder and Elbow. 2023. DOI: 10.5397/cise.2023.00311

[14] Arthroscopically assisted reduction of acute acromioclavicular joint dislocation using a single double-button device: Medium-term clinical and radiological outcomes. Orthopaedics & Traumatology: Surgery & Research. 2018. DOI: 10.1016/j.otsr.2017.11.001

[15] Successful Conservative Therapy in Rockwood Type V Acromioclavicular Dislocations. Orthopaedic Journal of Sports Medicine. 2015. DOI: 10.1177/2325967115s00017

[16] Instability and Degenerative Arthritis of the Sternoclavicular Joint. The American Journal of Sports Medicine. 2013. DOI: 10.1177/0363546513498990

[17] No differences between conservative and surgical management of acromioclavicular joint osteoarthritis: a scoping review. Knee Surgery, Sports Traumatology, Arthroscopy. 2021. DOI: 10.1007/s00167-020-06377-8

[18] Preoperative Factors Associated With Subsequent Distal Clavicle Resection After Rotator Cuff Repair. Orthopaedic Journal of Sports Medicine. 2019. DOI: 10.1177/2325967119844295

[19] Is Arthroscopic Distal Clavicle Resection Necessary for Patients With Radiological Acromioclavicular Joint Arthritis and Rotator Cuff Tears?. The American Journal of Sports Medicine. 2014. DOI: 10.1177/0363546514547254

[20] Arthroscopic versus open distal clavicle excision: Comparative results at six months and one year from a randomized, prospective clinical trial. Journal of Shoulder and Elbow Surgery. 2007. DOI: 10.1016/j.jse.2006.10.006

[21] Surgical treatment of chronic acromioclavicular dislocation: Comparison between two surgical procedures for anatomic reconstruction. Injury. 2010. DOI: 10.1016/j.injury.2010.09.023

[22] Mid- to long-term success rate and functional outcomes of acromioclavicular injections in patients with acromioclavicular osteoarthritis. Clinics in Shoulder and Elbow. 2023. DOI: 10.5397/cise.2023.00031

[23] Osteoarthritis after rotator cuff repair: A 10-year follow-up study. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2017.03.007

[24] The ligamentous injury pattern in acute acromioclavicular dislocations and its impact on clinical and radiographic parameters. Journal of Shoulder and Elbow Surgery. 2021. DOI: 10.1016/j.jse.2020.10.026

[25] Acute grade III and IV acromioclavicular dislocations: Outcomes and pitfalls of reconstruction procedures using a synthetic ligament. Orthopaedics & Traumatology: Surgery & Research. 2010. DOI: 10.1016/j.otsr.2010.06.004

[26] Differences between Coracoclavicular, Acromioclavicular, or Combined Reconstruction Techniques on the Kinematics of the Shoulder Girdle. The American Journal of Sports Medicine. 2022. DOI: 10.1177/03635465221095231

[27] The Function of the Acromioclavicular and Coracoclavicular Ligaments in Shoulder Motion. The American Journal of Sports Medicine. 2012. DOI: 10.1177/0363546512458571

[28] Acromioclavicular joint ligamentous system contributing to clavicular strut function: a cadaveric study. Journal of Shoulder and Elbow Surgery. 2013. DOI: 10.1016/j.jse.2013.01.004

[29] Subacromial morphometric assessment of the clavicle hook plate. Injury. 2010. DOI: 10.1016/j.injury.2009.12.012

[33] Can an acute high-grade acromioclavicular joint separation be reduced and stabilized without surgery? A surgeon’s experience. Archives of Orthopaedic and Trauma Surgery. 2020. DOI: 10.1007/s00402-020-03630-0

[35] Current concepts in acromioclavicular joint (AC) instability – a proposed treatment algorithm for acute and chronic AC-joint surgery. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-05935-0

[38] Current Concepts in the Operative Management of Acromioclavicular Dislocations: A Systematic Review and Meta-analysis of Operative Techniques. The American Journal of Sports Medicine. 2018. DOI: 10.1177/0363546518795147

[39] Arthroscopic Coracoclavicular Ligament Reconstruction With Double‐Bundle Soft Tissue Allograft for Chronic Type V Acromioclavicular Dislocations Shows Excellent Patient Outcomes and Return to Duty and Sport at Minimum 10‐Year Follow‐Up. Arthroscopy. 2025. DOI: 10.1016/j.arthro.2025.05.008

[41] Acromioclavicular joint augmentation at the time of coracoclavicular ligament reconstruction fails to improve functional outcomes despite significantly improved horizontal stability. Knee Surgery, Sports Traumatology, Arthroscopy. 2018. DOI: 10.1007/s00167-018-5152-7

[43] Histologic and magnetic resonance image evaluation in acromioclavicular joint osteoarthritis. JSES International. 2020. DOI: 10.1016/j.jseint.2020.03.007

[44] Painful Conditions of the Acromioclavicular Joint. Journal of the American Academy of Orthopaedic Surgeons. 1999. DOI: 10.5435/00124635-199905000-00004

[45] Additional acromioclavicular cerclage limits lateral tilt of the scapula in patients with arthroscopically assisted coracoclavicular ligament reconstruction. Archives of Orthopaedic and Trauma Surgery. 2021. DOI: 10.1007/s00402-021-03761-y

[48] Minimally Invasive Coracoclavicular Ligament Augmentation With a Flip Button/Polydioxanone Repair for Treatment of Total Acromioclavicular Joint Dislocation. Arthroscopy. 2007. DOI: 10.1016/j.arthro.2006.12.015

[49] Conversion to anatomic coracoclavicular ligament reconstruction (ACCR) shows similar clinical outcomes compared to successful non‐operative treatment in chronic primary type III to V acromioclavicular joint injuries. Knee Surgery, Sports Traumatology, Arthroscopy. 2020. DOI: 10.1007/s00167-020-06159-2

[50] Complication rates and types of failure after arthroscopic acute acromioclavicular dislocation fixation. Prospective multicenter study of 116 cases. Orthopaedics & Traumatology: Surgery & Research. 2015. DOI: 10.1016/j.otsr.2015.09.012

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