Reliability of radiographic measurements for acromioclavicular joint separations

Quality and stability of reduction of operated acromioclavicular dislocation using dual acromioclavicular and coracoclavicular stabilization

INTRODUCTION

Dual stabilization is advocated in acute acromioclavicular dislocation (ACD), but has been little assessed.

OBJECTIVE

This preliminary study performed clinical and radiological assessment of dual acromioclavicular (AC) and coracoclavicular (CC) stabilization in acute ACD. The study hypothesis was that dual stabilization allows satisfactory reduction that remains stable over time.

MATERIALS AND METHODS

A button was used under endoscopy for CC stabilization. For AC stabilization, a short approach was used; the joint was cleansed then stabilized by an anchored tape between the acromion and the clavicle to promote ligament healing. Clinical assessment was based on a visual analog pain scale (VAS), joint range of motion and Quick-DASH and Constant scores. Radiological reduction was assessed on the ratio of CC distance between the operated and healthy sides on two views. MRI was used in follow-up to screen for ligament healing: thickening and continuity.

RESULTS

Thirty-five patients with stage 3-5 acute dislocation were included. At a minimum 24 months' follow-up, mean clinical scores were very satisfactory, with recovery of motion and pain relief. Radiography showed 94% stable reduction in both vertical and horizontal planes. MRI confirmed CC and AC ligament healing. Postoperative complications mainly comprised 4 cases of reduction loss (11%). One clavicle fracture occurred, at 6 months.

CONCLUSION

Dual AC-CC stabilization provided very good radiographic reduction in both horizontal and vertical planes. Functional results were very satisfactory, and complications were few, with some cases of reduction loss. These good results encourage us to continue with dual stabilization in acute ACD.

LEVEL OF EVIDENCE

II; prospective cohort.

Conservative treatment of Rockwood type III acromioclavicular joint separation: a randomized controlled trial sling vs. brace

Background

Management of Rockwood III acromioclavicular joint separations is a matter of ongoing debate, with nonoperative treatment being favored in recent literature. The aim of this study is to compare clinical and radiological outcomes of nonoperative treatment with a brace, which elicits a direct reduction force to the distal clavicle, to a sling. We hypothesized the brace might yield in better acromioclavicular joint (ACJ) reduction and cosmesis.

Methods

In this dual center prospective randomized controlled trial, all patients sustaining an acromioclavicular joint separation Rockwood III between July 2017 and August 2020 were included. Patients with previous ipsi- or contralateral ACJ injury or surgery were excluded. Randomization occurred in the emergency department to either the sling or brace group. Patients were followed up at 1, 6, and 12 weeks. Patient-reported outcome measures included subjective shoulder value (SSV) and American Shoulder and Elbow Surgeons (ASES) score at each follow-up and Constant Score at 6 and 12 weeks. Vertical distal clavicle displacement was assessed on bilateral non-weighted panoramic anteroposterior radiographs using coracoclavicular (CC) distance to calculate the CC-index.

Results

Thirty-five consecutive patients were included across the 2 sites, 18 (all male) in the brace and 17 (14 male) in the sling group. Baseline characteristics did not differ significantly between groups, the average age was 40 years, and body mass index 25.5 kg/m². Analysis revealed no statistical difference in CC-index between groups at the time of injury, 6 weeks and 12 weeks postinjury (P = .39, P = .11, and P = .21). SSV improved from 30 and 35 postinjury to 81 and 84 at 12 weeks in the sling and brace group, respectively (P = .59). ASES improved from 48 and 38 to 82 and 83, respectively (P = .84). Similarly, Constant Score improved from 64 and 67 to 82 and 81, respectively (P = .90). One patient in the brace group underwent ACJ stabilization with hamstring autograft at 4 months due to persistent pain.

Conclusion

This randomized controlled trial shows no statistically significant difference between the brace and sling group in clinical (SSV, ASES, Constant Score) or radiological (CC-index) outcomes after conservative treatment of Rockwood III injuries.

Subject-specific computational modeling of acromioclavicular and coracoclavicular ligaments

BACKGROUND

Disruption of the acromioclavicular joint is a common injury. Despite the different surgical procedures described for treating this injury, complications such as loss of reduction and failure of fixation remain unacceptably high. We developed a computer model of the acromioclavicular joint to better understand the biomechanical contributions of the ligaments that are typically injured.

METHODS

Six fresh frozen human cadaveric shoulders were tested on an AMTI VIVO 6-degree of freedom test platform to measure force-displacement in inferior translation, anteroposterior translation, and internal rotation before and after sequentially transecting the coracoclavicular and acromioclavicular ligaments. These data were used to construct computer models of each specimen. Three-dimensional computed tomographic scans were used to generate a rigid-body dynamics model using the AnyBody Modeling System. The scapula and clavicle were connected by the acromioclavicular joint capsule, the conoid ligament, and the trapezoid ligament. Subject-specific ligament properties were calculated by matching computer predictions to experimental force-displacement data.

RESULTS

The calculated free lengths of the conoid, trapezoid, and acromioclavicular ligaments were 13.5 (±3.2), 11.8 (±2.4), and 11.0 (±2.7) mm, respectively. The calculated stiffnesses of the conoid, trapezoid, and acromioclavicular ligaments were 34.3 (±6.3), 28.4 (±3.2), and 33.8 (±8.2) N/mm, respectively. Root mean square deviation (RMSD) of predicted force-displacement curves relative to experimental force-displacement curves (during inferior and anteroposterior translation) was less than 1 mm. For validation of subject-specific models, after ligament properties were calculated, the RMSD of the predicted torque over 15° of internal rotation was 12% of maximum rotational torque (average for 6 specimens).

DISCUSSION AND CONCLUSION

Acromioclavicular disruption results in multidirectional instability, which requires careful consideration of the individual contributions of the injured ligaments. In addition, variations in patient anatomy can significantly affect the biomechanical stability of the reconstruction. Subject-specific models can enhance our understanding of the individual and collective biomechanical contributions of the injured soft tissues to the multiaxial stability of the acromioclavicular joint. These models may also be useful for analyzing and assessing biomechanical stability after various types of surgical reconstruction.

Acromioclavicular joint injuries at a Colorado ski resort

BACKGROUND

Acromioclavicular joint (ACJ) injuries are among the most common injuries in contact and non-contact sports. As winter sports become more popular, there has been an increase in shoulder injuries among recreational skiers and snowboarders.

METHODS

This was a retrospective analysis of all patients who presented to the Denver Health Winter Park Medical Center with ACJ injury from 2012 to 2017. We examined the incidence of ACJ injuries, the injury mechanism, demographics, and type of ACJ injuries among skiers and snowboarders treated at the clinic.

RESULTS

A total of 341 ACJ injuries (6.7% of total visits) were encountered during the study period. The majority of ACJ injures were type I (41.3%) and mainly occurred in men (86.5%). Most (96.8%) of the cases were primary ACJ injuries on the right shoulder (56.9%). The average age of patients with ACJ injuries was 30.0 years (range 10-72). More than half (62.2%) of ACJ injuries occurred while snowboarding. The most common mechanism of injury (93.5%) was fall to the snow while skiing/snowboarding. Women were more likely to have a type I ACJ injury than men (80.4% vs 35.4%; P < 0.001). Women with ACJ injuries were more likely to suffer the injury while skiing than snowboarding (71.7% vs 28.3%; P < 0.001), compared to men who were more likely to suffer the injury while snowboarding than skiing (67.5% vs 32.5%; P < 0.001).

CONCLUSIONS

Most of the ACJ injuries were type I and occurred mostly in men. Snowboarders were more likely to have an ACJ injury than skiers.

LEVEL OF EVIDENCE

Level IV, Epidemeiology Study.

Reliability of Upright Chest Radiography as a Diagnostic Screening Tool for Acromioclavicular Joint Dislocations

Background

The standard radiographic view for diagnosing acromioclavicular joint (ACJ) dislocations is the Zanca view of both shoulders to assess superior displacement of the distal clavicle by measuring the coracoclavicular distance (CCD) and comparing it with the uninjured shoulder; however, there is no consensus on a gold standard for diagnostic measures to classify acute ACJ injuries.

Purpose

To compare the CCD from an upright chest radiograph with a standard Zanca view of both shoulders in patients with an ACJ dislocation.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

We reviewed the records of 70 patients with an ACJ dislocation between 2010 and 2021 who had both an upright chest radiograph and a Zanca view. An ACJ dislocation was classified as low grade (Rockwood types 1-3) or high grade (Rockwood type 5). The CCD was measured on the upright chest radiograph and the Zanca view by 2 independent reviewers, and the percentage of the CCD difference compared with the unaffected side (ΔCCD) was calculated and compared between the upright chest radiograph and the Zanca view. Interrater and intrarater reliability were determined using the intraclass correlation coefficient.

Results

Included were 70 patients (55 male and 15 female; mean age, 46 years). There were 29 patients (41.43%) with a low-grade injury and 41 patients (58.57%) with a high-grade injury. In the overall analysis, the ΔCCD on the upright chest radiograph and Zanca view was significantly different (130.25% ± 88.42% vs 152.69% ± 106.56%, respectively; mean difference, 22.44% [95% CI, 2.40% to 42.48%]; P = .029). The subgroup analysis revealed that the ΔCCD on the upright chest radiograph and Zanca view was significantly different for patients with a low-grade injury (60.71% ± 25.79% vs 91.46% ± 68.54%, respectively; mean difference, 30.76% [95% CI, 7.18% to 54.33%]; P = .012) but not different for patients with a high-grade injury (179.45% ± 83.87% vs 196.00% ± 107.97%, respectively; mean difference, 16.56% [95% CI, -14.06% to 47.18%]; P = .281). The intraclass correlation coefficients for the ΔCCD measurements indicated good to excellent interrater and intrarater reliability.

Conclusion

The study findings indicated that upright chest radiography can be used as a diagnostic screening tool for high-grade ACJ dislocations, but not for low-grade ACJ injuries, compared with the Zanca view.

Current concepts in acromioclavicular joint (AC) instability - a proposed treatment algorithm for acute and chronic AC-joint surgery

BACKGROUND

There exists a vast number of surgical treatment options for acromioclavicular (AC) joint injuries, and the current literature has yet to determine an equivocally superior treatment. AC joint repair has a long history and dates back to the beginning of the twentieth century.

MAIN BODY

Since then, over 150 different techniques have been described, covering open and closed techniques. Low grade injuries such as Type I-II according to the modified Rockwood classification should be treated conservatively, while high-grade injuries (types IV-VI) may be indicated for operative treatment. However, controversy exists if operative treatment is superior to nonoperative treatment, especially in grade III injuries, as functional impairment due to scapular dyskinesia or chronic pain remains concerning following non-operative treatment. Patients with a stable AC joint without overriding of the clavicle and without significant scapular dysfunction (Type IIIA) may benefit from non-interventional approaches, in contrast to patients with overriding of the clavicle and therapy-resistant scapular dysfunction (Type IIIB). If these patients are considered non-responders to a conservative approach, an anatomic AC joint reconstruction using a hybrid technique should be considered. In chronic AC joint injuries, surgery is indicated after failed nonoperative treatment of 3 to 6 months. Anatomic AC joint reconstruction techniques along with biologic augmentation (e.g. Hybrid techniques, suture fixation) should be considered for chronic high-grade instabilities, accounting for the lack of intrinsic healing and scar-forming potential of the ligamentous tissue in the chronic setting. However, complication and clinical failure rates remain high, which may be a result of technical failures or persistent horizontal and rotational instability.

CONCLUSION

Future research should focus on addressing horizontal and rotational instability, to restore native physiological and biomechanical properties of the AC joint.

Does the choice of the optic portal influence the radiographic and early functional results in acute acromioclavicular disjunctions?

Exposure of the coracoid process during arthroscopic stabilization of acute acromioclavicular disjunctions (ACDs) can be achieved either by passing an extra- articular optical portal through the subacromial space or by an intra-articular optical route through the glenohumeral joint with opening of the rotator interval. The objective of our study was to compare the impact on the functional results of these two optical routes. This was a retrospective, multicentre study that included patients operated on for an acute acromioclavicular disjunction arthroscopically. The treatment consisted of surgical stabilization under arthroscopy. The surgical indication was retained for an acromioclavicular disjunction of grade 3, 4 or 5, according to the Rockwood classification. Group 1, which consisted of 10 patients, was operated on with an extra-articular subacromial optical route, and group 2, which consisted of 12 patients, was operated on with an intra-articular optical route with opening of the rotator interval according to the habits of the surgeon. A follow-up of 3 months was performed. The functional results were evaluated for each patient using the Constant score, Quick DASH, and SSV. The delays in returning to professional and sports activities were also noted. A precise postoperative radiological analysis made it possible to analyse the quality of the radiological reduction. No significant difference between the two groups was found between the Constant score (88 vs. 90; p = 0.56), Quick DASH (7 vs. 7; p = 0.58), or SSV (88 vs. 93; p = 0.36). The times to return to work (6.8 weeks vs. 7.0 weeks; p = 0.54) and sports activities (15.6 weeks vs. 19.5 weeks; p = 0.53) were also comparable. The quality of the radiological reduction was satisfactory in the two groups and did not depend on the approach. No clinically or radiologically significant differences between the extra-articular and intra-articular optical portals in the surgical treatment of acute ACDs were found. The optical route can be chosen according to the habits of the surgeon.

The “Chiang Mai Lean Forward” Radiographic View for Acromioclavicular Joint Injuries: A Cadaveric Study

Background:

Operative treatment is suggested for unstable type 3 acromioclavicular (AC) joint injuries; however, there is no clear consensus regarding the definition of an unstable type 3 injury. We propose a new radiographic method, the “Chiang Mai lean forward” view, to verify horizontal displacement in an unstable AC joint injury.

Hypothesis:

A radiograph taken with the torso leaning forward would allow the detection of a higher proportion of AC joint injuries.

Study Design:

Descriptive laboratory study.

Methods:

A total of 20 shoulders from 10 fresh whole-body cadaveric specimens (mean age, 68.8 years) were tested at 3 different torso leaning angles (30°, 45°, and 60°) to determine the best position for projecting the x-ray beam. The shoulders were dissected sequentially starting with the AC ligament (stage 1), then additional sectioning of the partial coracoclavicular (CC) ligament with either the trapezoid ligament cut first (stage 2A) or the conoid ligament cut first (stage 2B), and finally complete sectioning of the CC ligament (stage 3). Radiography was performed after each stage to evaluate the degree of displacement of the anterior border of the acromion relative to the anterior border of the clavicle. Paired t tests were used to compare the degree of displacement at each stage to that of the shoulder before cutting.

Results:

Leaning at an angle of 30° provided better visualization of the AC joint in the “Chiang Mai lean forward” view. Compared with the intact condition, complete isolated cutting of the AC ligament produced 5.21 mm of horizontal displacement of the AC joint (P < .0001), complete tearing of the AC ligament and partial cutting of the CC ligament resulted in a displacement of <12 mm (7.91 mm at stage 2A [P = .0003] and 8.10 mm at stage 2B [P = .0013]), and complete tearing of both the AC and the CC ligaments resulted in a displacement of 26.37 mm (P < .0001).

Conclusion:

The “Chiang Mai lean forward” radiographic view is a potentially useful tool for determining the degree of the injury and the stability of the AC joint.

Imaging Review of Hockey-Related Upper Extremity Injuries

Ice hockey is a fast-paced contact sport with a high incidence of injuries. Upper extremity injury is one of the most common regions of the body to be injured in hockey. This imaging review will equip the radiologist with a knowledge of the more common and severe upper extremity injuries that occur in this sport.

Low rate of substantial loss of reduction immediately after hardware removal following acromioclavicular joint stabilization using a suspensory fixation system

PURPOSE

To evaluate immediate loss of reduction in patients undergoing hardware removal after arthroscopically assisted acromioclavicular (AC) joint stabilization using a high-tensile suture tape suspensory fixation system and to identify risk factors associated with immediate loss of reduction.

MATERIALS AND METHODS

Twenty-two consecutive patients with a mean age of 36.4 ± 12.6 years (19-56), who underwent hardware removal 18.2 ± 15.0 months following arthroscopically assisted stabilization surgery using a suspensory fixation system for AC joint injury between 01/2012 and 01/2021 were enrolled in this retrospective monocentric study. The coracoclavicular distance (CCD) as well as the clavicular dislocation/acromial thickness (D/A) ratio were measured on anterior-posterior radiographs prior to hardware removal and immediately postoperatively by two independent raters. Loss of reduction, defined as 10% increase in the CCD, was deemed substantial if the CCD increased 6 mm compared to preoperatively. Constitutional and surgical characteristics were assessed in a subgroup analysis to detect risk factors associated with loss of reduction.

RESULTS

Postoperatively, the CCD significantly increased from 12.6 ± 3.7 mm (4.8-19.0) to 14.5 ± 3.3 mm (8.7-20.6 mm) (p < 0.001) while the D/A ratio increased from 0.4 ± 0.3 (- 0.4-0.9) to 0.6 ± 0.3 (1.1-0.1) (p = 0.034) compared to preoperatively. In 10 cases (45%), loss of reduction was identified, while a substantial loss of reduction (> 6 mm) was only observed in one patient (4.5%). A shorter time interval between index stabilization surgery and hardware removal significantly corresponded to immediate loss of reduction (11.0 ± 5.6 vs. 30.0 ± 20.8 months; p = 0.007), as hardware removal within one year following index stabilization was significantly associated with immediate loss of reduction (p = 0.027; relative risk 3.4; odds ratio 11.67).

CONCLUSIONS

Substantial loss of reduction after hardware removal of a high-tensile suture tape suspensory fixation system was rare, indicating that the postoperative result of AC stabilization is not categorically at risk when performing this procedure. Even though radiological assessment of the patients 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.

LEVEL OF EVIDENCE

IV.

A relook at the reliability of Rockwood classification for acromioclavicular joint injuries

BACKGROUND

Controversies for treatment of acromioclavicular joint injuries in particular type III injuries may be partially attributed to the lack of a standardized method of radiography and measurement technique. Previous studies looking at the Rockwood classification showed poor inter- and intraobserver reliability (Kappa value approximately 0.20-0.50). We hypothesized that the use of unilateral instead of bilateral acromioclavicular joint radiographs was the cause of this finding. In this article, we standardized the methodology to perform the radiograph and to measure the coracoclavicular distances. We designed the study to focus on the reliability of differentiating type III and type V injuries.

METHODS

A standardized radiographic protocol for bilateral Zanca view was established in our institution. All patients who underwent this radiographic examination over a 3-year period were reviewed. Radiographs of 55 patients with significant (type III or V) injury met the inclusion criteria. For the interobserver reliability, a retrospective radiographic review was performed by 6 orthopedic surgeons and graded as either type III or V. For intraobserver reliability, a similar process was repeated by 3 observers after a period of 6 weeks.

RESULTS

Going by the majority agreement of the 6 reviewers, there were 34 type III injuries and 19 type V injuries. The Fleiss kappa for interobserver reliability was calculated to be 0.624. The Cohen kappa for intraobserver reliability was calculated to be 0.696.

DISCUSSION

The use of a standardized radiographic protocol-taking bilateral Zanca views on the same radiographic plate-would help eliminate a significant amount of variability and improve the reliability of classifying acromioclavicular joint injuries using the Rockwood classification, which uses a relative measure to the contralateral site as its definition criteria. Other possible sources of poor reliability may include the masking of injuries by muscle spasm, resulting in a misdiagnosis of a high-grade injury as a lower-grade one and the possible need to subclassify type III injuries.

CONCLUSION

Reliability of the Rockwood classification can be improved through the use of a standardized radiographic protocol to improve the detection of vertical instability. Similar to Rockwood dividing up Tossy grade 3 injuries when he noted the differential outcome and intervention, Rockwood type III injuries would likely require further subclassification as it remains an anomalous tool with high variability. Further studies are required to understand the pathologic basis of transition of type III into type V injury.

Weighted or internal rotation radiographs are not useful in the classification of acromioclavicular joint dislocations

BACKGROUND

Weighted radiographs are performed to classify acromioclavicular joint dislocations; however, the evidence regarding their usefulness is conflicting. Laboratory studies suggest that internal rotation views can replace weighted radiographs, but this has not been clinically evaluated.

PURPOSE

To evaluate whether weighted or internal rotation radiographs uncovers more high-grade acromioclavicular joint dislocations than non-weighted radiographs.

MATERIAL AND METHODS

A total of 162 patients with acromioclavicular joint dislocations were prospectively included. After applying exclusion criteria, 140 remained. Three panorama radiographs, including both coracoclavicular intervals, were completed of each participant: first, a weighted radiograph with 5-kg weights suspended from the wrists; second, a non-weighted radiograph; and third, an internal rotation radiograph. The coracoclavicular intervals were measured by two radiologists independently, and measurements were translated into Rockwood classifications. The classifications and measurements derived from the different radiographic views were compared.

RESULTS

Weighted radiographs caused no significant changes in classification. For the internal rotation views, there was a significant change in classification for radiologist 2; however, the reason was that more injuries were downgraded compared to the non-weighted views. Relative to the non-weighted radiographs, the mean increase of the coracoclavicular interval on the injured side in the weighted view was 0.5 mm (95% confidence interval [CI] 0.37-0.65) and in the internal rotation view 0.2 mm (95% CI 0.04-0.33). While these changes were statistically significant, they were small and not clinically important.

CONCLUSION

This study does not support the use of weighted and internal rotation radiographs in the classification of acromioclavicular joint dislocations.

Evaluation of the Circles Measurement and the ABC Classification of Acromioclavicular Joint Injuries

BACKGROUND

Acromioclavicular joint (ACJ) injuries are common. Despite this, it remains unclear how best to assess, classify, and manage these cases. A simple, reliable, valid, and accurate radiographic parameter to measure ACJ displacement would allow improved consistency of diagnosis and subsequent treatment pathways.

PURPOSE

To evaluate "the circles measurement" and associated "ABC classification" as a tool for assessing ACJ displacement and injury classification.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The circles measurement is taken from a lateral Alexander radiograph of the shoulder. The measurement is the center-to-center distance between 2 circles drawn to define the lateral extent of the clavicle and the anteromedial extent of the acromion; it is independent of the displacement plane, judging total ACJ displacement in any direction rather than trying to quantify vertical and/or horizontal displacement. When utilized clinically, the circles measurement is a single measurement calculated as the difference between values recorded for the injured and uninjured sides. Validation of the circles measurement was performed using lateral Alexander radiographs (including ±20° projection error in all planes) and computed tomography of standardized ACJ injury simulations. We assessed inter- and intrarater reliability, convergent validity, and discriminant validity of the circles measurement and subsequently generated a classification of ACJ injury based on displacement.

RESULTS

Reliability and validity of the circles measurement was excellent throughout. Interrater reliability (ICC [intraclass correlation coefficient] [2,1], 95% CI; n = 78; 4 observers) was 0.976 (0.964-0.985). Intrarater reliability (ICC [2,1]; 95% CI; n = 78; 2 measures) was 0.998 (0.996-0.998). Convergent validity (Pearson correlation coefficient, r) was 0.970 for ideal radiographs and 0.889 with ±20° projection error in all planes. Discriminant validity, with 1-way analysis of variance, showed a P value of <.0001 and effect size (η²) of 0.960, with the ability to distinguish between the previously defined stable (Rockwood IIIA) and unstable (Rockwood IIIB) injuries. The results permitted objective, statistically sound parameters for the proposed ABC classification system.

CONCLUSION

The circles measurement is a simple, reliable, valid, accurate, and resilient parameter for assessing ACJ displacement and can be used in conjunction with the proposed ABC classification to define ACJ injuries more accurately and objectively than previously described.

CLINICAL RELEVANCE

This novel parameter has the potential to standardize the initial assessment and possibly the subsequent clinical management of ACJ injuries, in addition to providing a standardized measure for future research.

Ultrasound Evaluation of Anterior Acromioclavicular Relationship in the Horizontal Plane on 40 Healthy Subjects. A New Possibility for Differential Diagnosis of Acromioclavicular Disjunctions Rockwood Stage 3 and 4? A Pilot Study

OBJECTIVE

To evaluate the repeatability and reproducibility of an ultrasound examination of the acromioclavicular joint (ACJ) performed by an orthopaedic surgeon to analyze anterior ACJ relationship in the horizontal plane.

DESIGN

Prospective observational study on healthy subjects.

SETTING

The study was conducted in 2017 in a university department of orthopaedic surgery and traumatology.

LEVEL OF EVIDENCE

III.

PATIENTS (OR PARTICIPANTS)

Forty consecutive volunteers aged 18 to 40 years were involved. INTERVENTIONS (OR ASSESSMENT OF RISK FACTORS OR INDEPENDENT VARIABLES):: The ultrasound examination was performed by 2 orthopaedic surgeons with a SonoSite M-Turbo portable ultrasound machine (Fujifilm, Japan). Distance measurement between the anterior edge of the clavicle (AECL) and the anterior edge of the acromion (AEAC) was done on the right side, then on the left one and repeated by the same examiner.

MAIN OUTCOME MEASURES

The intra- and interexaminer reproducibility of measurements was analyzed as primary outcome. Concordance of distance measurements between the right and left sides on the same subject was evaluated, as well as the "typical morphology" of the ACJ in the horizontal plane.

RESULTS

The intra- and interexaminer reproducibility for AECL-AEAC distance measurements was, respectively, 0.95 (0.93-0.97) and 0.87 (0.84-0.90). The correlation between the right and left sides was significant (P < 0.001), with a reproducibility of 0.86 (0.83-0.89). Twenty-seven (67.5%) volunteers were considered to have a "perfect alignment" of the AECL and AEAC.

CONCLUSIONS

This study confirms that it is possible to evaluate with good reproducibility the anterior AC relationship in the horizontal plane and that both sides are similar on the same subject.

Restoring Horizontal Stability of the Acromioclavicular Joint: Open Acromioclavicular Ligament Reconstruction and Repair With Semitendinosus Allograft

Injuries to the acromioclavicular (AC) joint are common and comprise ∼12% of shoulder injuries. Stability to the AC joint depends on the coracoclavicular (CC) ligaments for vertical stability and AC ligaments and capsular structures for horizontal stability. Injuries to the AC ligaments can lead to horizontal instability of the AC joint. There is no gold standard technique for treating these injuries surgically, and many of the described procedures focus on vertical instability rather than horizontal instability. This article describes an open AC ligament reconstruction with semitendinosus allograft to restore horizontal stability of the AC joint.

Imaging of the Acromioclavicular Joint: Anatomy, Function, Pathologic Features, and Treatment

The acromioclavicular joint is an important component of the shoulder girdle; it links the axial skeleton with the upper limb. This joint, a planar diarthrodial articulation between the clavicle and the acromion, contains a meniscus-like fibrous disk that is prone to degeneration. The acromioclavicular capsule and ligaments stabilize the joint in the horizontal direction, while the coracoclavicular ligament complex provides vertical stability. Dynamic stability is afforded by the deltoid and trapezius muscles during clavicular and scapular motion. The acromioclavicular joint is susceptible to a broad spectrum of pathologic entities, traumatic and degenerative disorders being the most common. Acromioclavicular joint injury typically affects young adult males and can be categorized by using the Rockwood classification system as one of six types on the basis of the direction and degree of osseous displacement seen on conventional radiographs. MRI enables the radiologist to more accurately assess the regional soft-tissue structures in the setting of high-grade acromioclavicular separation, helping to guide the surgeon's selection of the appropriate management. Involvement of the acromioclavicular joint and its stabilizing ligaments is also important for understanding and classifying distal clavicle fractures. Other pathologic processes encountered at this joint include degenerative disorders; overuse syndromes; and, less commonly, inflammatory arthritides, infection, metabolic disorders, and developmental malformations. Treatment options for acromioclavicular dysfunction include conservative measures, resection arthroplasty for recalcitrant symptoms, and surgical reconstruction techniques for stabilization after major trauma.

Surgical techniques for management of acromioclavicular joint separations: review and update for radiologists

Imaging plays a central role in the postoperative management of acromioclavicular (AC) joint separations. There are more than 150 described techniques for the surgical management of AC joint injuries. These procedures can be categorized as varying combinations of the following basic techniques: a) soft-tissue repair, b) trans-articular AC joint fixation, c) coracoclavicular (CC) fixation, d) non-anatomic reconstruction of the CC ligaments, e) anatomic reconstruction of the CC ligaments, f) distal clavicle resection, and g) dynamic muscle transfer. The goals of this article are to describe the basic techniques for the surgical management of AC joint separations with an emphasis on technique-specific complications and postoperative imaging assessment.

Improved identification of unstable acromioclavicular joint injuries in a clinical population using the acromial center line to dorsal clavicle radiographic measurement

BACKGROUND

Accurate classification and subsequent management of acromioclavicular (AC) joint injuries remains a contentious topic. The updated Rockwood classification acknowledges "stable IIIA" and "unstable IIIB" injuries, a watershed accepted by ISAKOS and important in guiding clinical management. Traditionally, the coracoclavicular distance is used to classify these injuries, despite well-documented limitations. This study aimed to evaluate displacement in AC joint injuries by measuring both coracoclavicular (CC) distance and the newly proposed acromial center line to dorsal clavicle (AC-DC) distance, in a cohort of patients, and correlate the results between the 2 measurements and relationship to Rockwood grade.

MATERIALS AND METHODS

Ninety consecutive cases of AC joint injury were evaluated radiographically for Rockwood classification, CC distance on anteroposterior radiographs, and AC-DC distance on Alexander view radiographs. Inter- and intraobserver reliability for each measurement was calculated as well as correlation between the 2 measurement types and the degree to which each measurement accurately represented the Rockwood classification.

RESULTS

Although both CC and AC-DC measurements showed very high inter- and intraobserver reliability, the CC distance systematically underestimated the degree of AC joint displacement when compared with the AC-DC measurement as the severity of injury increased, particularly in the presence of posterior horizontal displacement such as that seen in Rockwood IV injuries.

CONCLUSION

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.

Modified Weaver-Dunn Procedure for Type 3 Acromioclavicular Joint Dislocation: Functional and Radiological Outcomes

Background

Controversy surrounds the indication for treatment of type 3 acromioclavicular joint dislocation, and the optimal reconstructive technique has not yet been defined. Since the first description of the Weaver-Dunn procedure, several studies have described the clinical and radiological results that can be expected postoperatively; however, few studies have evaluated the outcomes of this technique for chronic type 3 acromioclavicular joint dislocation.

Purpose/Hypothesis

The purpose of this study was to evaluate the functional and radiographic mid- to long-term outcomes of a modified Weaver-Dunn procedure for chronic Rockwood type 3 acromioclavicular joint dislocation. We hypothesized that (1) functional outcomes comparable with sex- and age-matched healthy individuals could be achieved with the modified Weaver-Dunn procedure and (2) joint stability could be restored after surgery.

Study Design

Case series; Level of evidence, 4.

Methods

Out of 30 patients who sustained a chronic type 3 acromioclavicular joint dislocation, 27 had a minimum 12-month follow-up and were included in the study. All patients underwent a modified Weaver-Dunn procedure. The Constant-Murley score was used to assess patient postoperative function. Subjective evaluation of patient satisfaction with surgery was also recorded. Radiological assessment was performed postoperatively to evaluate superoinferior and anteroposterior joint stability.

Results

After a mean follow-up period of 51.6 months, the mean Constant-Murley score was 90.1, which was 97.2% that of a group of sex- and age-matched healthy individuals. In the multivariate analysis, higher Constant-Murley score was associated with male sex (β = 0.385; P = .043) and higher subjective satisfaction scale (β = 0.528; P = .003). All patients returned to their previous work and sport activity levels having high satisfaction with surgery. Successful vertical acromioclavicular joint reduction was obtained in all but 1 patient; however, horizontal joint stability was not completely restored with the modified Weaver-Dunn procedure. No intraoperative complications occurred, and the postoperative complication rate was 7.4%.

Conclusion

In patients with chronic type 3 acromioclavicular joint dislocation, the modified Weaver-Dunn procedure is an effective technique to restore vertical but not horizontal joint stability 4 years after surgery. High levels of satisfaction with surgery and functional outcomes comparable with sex- and age-matched healthy individuals can be achieved.

Horizontal Instability of the Acromioclavicular Joint: A Systematic Review

BACKGROUND

Injuries to the acromioclavicular (AC) joint are common and should be suspected in patients who have shoulder pain in the region of the acromion and clavicle. Injuries to the AC ligament can cause horizontal instability and are often neglected or underdiagnosed, which can lead to poor patient outcomes.

PURPOSE

To perform a systematic review of the literature on the diagnosis and treatment of horizontal instability of the AC joint.

STUDY DESIGN

Systematic review.

METHODS

The authors performed a systematic review using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed and EMBASE were searched for studies that investigated diagnosis, treatment, and failure of operative management of acute and chronic AC separations. Studies that did not specifically evaluate AC joint injuries, were not written in English, or were specific only to vertical instability of the AC joint were excluded.

RESULTS

Overall, 23 articles met the inclusion criteria and were therefore included in this systematic review. Diagnosing horizontal AC instability is difficult using plain radiographs; dynamic views were shown in some cases to better detect horizontal instability than with static views. More than 60 procedures for treating AC joint injuries have been published, but many focus on vertical rather than horizontal instability. Modifications to current surgical procedures to incorporate reconstruction of the horizontal component showed improved patient outcomes. Such modifications included additional AC joint suture cord cerclage, combined AC and coracoclavicular ligament reconstruction, and the Twin Tail TightRope triple button technique. Failure after surgical stabilization of AC joint separation has been reported to occur in 15% to 80% of cases.

CONCLUSION

No consensus is available regarding the best practices for diagnosis, evaluation, and treatment of acute or chronic horizontal instability of the AC joint. Moreover, horizontal instability injuries are often neglected or poorly understood, making diagnosis difficult, which may lead to high complication rates and failure after surgical stabilization.

Clavicle Elevation or Shoulder Girdle Depression in Acromioclavicular Joint Dislocation: A Radiological Investigation

Background:

The side-comparative coracoclavicular (CC) distance is used to describe the vertical instability component of acute acromioclavicular (AC) joint dislocations. Elevation of the clavicle or a depression of the shoulder girdle can lead to an increased CC distance. The dislocation direction has not yet been investigated and is not included in common classification systems.

Hypothesis:

Clavicle elevation is primarily responsible for vertical dislocation in AC joint separation.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Weighted and nonweighted bilateral plain anteroposterior views of the shoulder girdles of patients with AC joint dislocations (Rockwood [RW] types III and V), diagnosed in our trauma department between 2001 and 2018, were included in this study. After determining the CC distance, a side-comparative determination of the positions of both the clavicle and shoulder girdle, with reference to the spinal column, was conducted.

Results:

In total, 245 bilateral plain anteroposterior views were evaluated (RW III, n = 116; RW V, n = 129). All patients showed a side-comparative clavicle elevation (mean ± SD: RW III, 5 ± 14 mm; RW V, 11 ± 17 mm) in weighted and nonweighted views. While no depression of the shoulder girdle was measured in RW III injuries (weighted and nonweighted views, 0 ± 11 mm), dropping of the shoulder girdle in RW V lesions on nonweighted views was observed (–5 ± 11 mm).

Conclusion:

Vertical dislocation is mostly associated with clavicle elevation in RW III injures, while in high-grade AC joint dislocations (RW V), a combination of clavicle elevation and shoulder girdle depression is present. A significantly greater superior displacement of the clavicle in RW V injuries was seen in weighted views, while a depression of the shoulder girdle could be detected in nonweighted views. For the first time, these results include the dislocation direction in the classification of an AC joint injury. Further studies are needed to investigate the extent to which dislocation types differ in optimal therapy and outcome.

Dynamic instability of the acromioclavicular joint: A new classification for acute AC joint separation

Background

Acute acromioclavicular (AC) dislocation is classified according to Rockwood (RW). Although of clinical relevance, dynamic horizontal translation (DHT) is not listed in this classification or in frequently used clinical evaluation tools. The aim of this study was (a) to evaluate vertical and horizontal AC joint instabilities and assess their combined occurrence and clinical appearance in a consecutive group of patients, as well as (b) to develop a new classification of acute AC joint dislocation.

Method

A consecutive group of 61 patients (seven female, 54 male) with a mean age of 34.5 years (18.9–60.1) were included in the study. All patients underwent posttraumatic clinical—Taft Score (TF), Acromioclavicular Joint Instability Score (ACJI), Constant Score (CS), Subjective Shoulder Value (SSV)—and radiological (bilateral anteroposterior stress and bilateral Alexander views) evaluation.

Results

According to the RW classification, the following AC dislocations were present: eight (13.1%) type I, nine (14.8%) type II, 22 (36.1%) type III, and 22 (36.1%) type V. Based on the clinical and radiographic results, a new classification is proposed: Type I instabilities show only a partial vertical displacement (≤30% coracoclavicular distance [CCD]) and type II a complete vertical displacement (>30% CCD). Both type I and II are further graded into none or partial (A) and complete DHT (B) as seen on bilateral Alexander views.

Conclusion

DHT can be found in low-grade instabilities and lead to inferior clinical results in the posttraumatic situation.

Arthroscopically assisted reduction of acute acromioclavicular joint dislocation using a single double-button device: Medium-term clinical and radiological outcomes

INTRODUCTION

Double-button devices for endoscopic management of acute acromioclavicular joint dislocation (ACJD) provide satisfactory short-term functional and radiological results. However, little exists in the literature regarding the long- and medium-term results of these implants, especially regarding the evolution of the acromioclavicular joint (ACJ).

HYPOTHESIS

Satisfactory and steady long- and medium-term outcomes can be achieved in patients with acute ACJD undergoing endoscopically assisted ACJ repair using a single double-button device.

MATERIAL AND METHOD

A retrospective single-center study was conducted in patients with acute Rockwood III and IV ACJD treated endoscopically with a single double-button device from October 2008 to October 2010, allowing a minimum 5-year follow-up. Functional evaluation used Constant and Quick-DASH scores. Clinical evidence of dislocation recurrence was combined with bilateral Zanca views to assess coracoclavicular distance. Acromioclavicular osteoarthritis was evaluated on the Paxinos test and Zanca views.

RESULTS

Nineteen of the 25 operated patients were seen at a mean 76.9±8.5 months' follow-up. Mean age was 34.4±8.3 years. Mean Constant and Quick-DASH scores were 96.2±5.1 and 0.9±1.6 points, respectively. Four patients had a recurrence of their initial dislocation, 3 of whom had positive Paxinos test, whereas the 15 patients without recurrence had a negative test (p=0.004). Five patients had radiological evidence of ACJ osteoarthritis: all 4 patients with recurrence and 1 without (p=0.001).

CONCLUSION

Long- and medium-term radioclinical outcome of endoscopically assisted management of acute ACJD using a single double-button device seems to be satisfactory and steady over time. Recurrence of the initial dislocation appears to be related to onset of degenerative ACJ arthropathy.

LEVEL OF EVIDENCE

Therapeutic type IV-Retrospective case series.

New quantitative radiographic parameters for vertical and horizontal instability in acromioclavicular joint dislocations

PURPOSE

The aim of this study was to identify the most accurate and reliable quantitative radiographic parameters for assessing vertical and horizontal instability in different Rockwood grades of acromioclavicular joint (ACJ) separations. Furthermore, the effect of projectional variation on these parameters was investigated in obtaining lateral Alexander view radiographs.

METHODS

A Sawbone model of a scapula with clavicle was mounted on a holding device, and acromioclavicular dislocations as per the Rockwood classification system were simulated with the addition of horizontal posterior displacement. Projectional variations for each injury type were performed by tilting/rotating the Sawbone construct in the coronal, sagittal or axial plane. Radiographic imaging in the form of an anterior-posterior Zanca view and a lateral Alexander view were taken for each injury type and each projectional variation. Five newly defined radiographic parameters for assessing horizontal and vertical displacement as well as commonly used coracoclavicular distance view were measured. Reliability, validity and the effect of projectional variation were investigated for these radiographic measurements.

RESULTS

All radiographic parameters showed excellent intra- and interobserver reliability. The validity was excellent for the acromial centre line to dorsal clavicle (AC-DC) in vertical displacement and for the glenoid centre line to posterior clavicle (GC-PC) in horizontal displacement, whilst the remaining measurements showed moderate validity. For AC-DC and GC-PC, convergent validity expressed strong correlation to the effective distance and discriminant validity demonstrated its ability to differentiate between various grades of ACJ dislocations. The effect of projectional variation increased with the degree of deviation and was maximal (3 mm) for AC-DC in 20° anteverted malpositioning and for GC-PC in 20° retroverted malpositioning.

CONCLUSIONS

AC-DC and the GC-PC are two novel quantitative radiographic parameters of vertical and horizontal instability in ACJ dislocations that demonstrate excellent reliability and validity with reasonable inertness to malpositioning. The use of AC-DC for assessing vertical displacement and GC-PC for assessing horizontal displacement in a single Alexander view is recommended to guide the appropriate management of ACJ dislocations. A better appreciation of the degree of horizontal instability, especially in lower Rockwood grades (II, III) of ACJ dislocations, may improve management of these controversial injuries.

The acutely injured acromioclavicular joint - which imaging modalities should be used for accurate diagnosis? A systematic review

Background

The management of acute acromioclavicular (AC) joint injuries depends on the degree of injury diagnosed by the Rockwood classification. Inadequate imaging and not selecting the most helpful imaging protocols can often lead to incorrect diagnosis of the injury. A consensus on a diagnostic imaging protocol for acute AC joint injuries does not currently exist. Therefore we conducted a systematic review of the literature considering three diagnostic parameters for patients with acromioclavicular (AC) joint injuries: 1) Assessment of vertical instability; 2) Assessment of horizontal instability; 3) Benefit of weighted panoramic views.

Methods

Internet databases were searched in March 2016 using the terms (“AC joint” OR “acromioclavicular joint”) AND (MRI OR MR OR radiograph OR X-ray OR Xray OR ultrasound OR “computer tomography” OR “computed tomography” OR CT). Diagnostic, prospective, retrospective, cohort and cross- sectional studies were included to compare their use of different radiological methods. Case reports, cadaveric studies, and studies concerning chronic AC injuries and clinical outcomes were excluded.

Results

This search returned 1359 citations of which 1151 were excluded based on title, 116 based on abstract and 75 based on manuscript. 17 studies were included for review and were analyzed for their contributions to the three parameters of interest mentioned above. The inter- and intra-observer reliability for diagnosing vertical instabilities of the clavicle using x-ray alone show a high level of reproducibility while for horizontal instabilities the values were much more variable. In general, digitally measured parameters seem to be more precise and reliable between investigators than visual classification alone. Currently, evidence for the value of weighted views and other additional diagnostic imaging to supplement standard x-rays is controversial.

Conclusion

To date there is no consensus on a gold standard for diagnostic measures needed to classify acute AC joint injuries. The inter- and intra-observer reliability for diagnosing vertical instabilities of the clavicle using bilateral projections show a high level of reproducibility while for horizontal instabilities the results are much more inconsistent. There is currently no clear consensus on a protocol for image-based diagnosis and classification of acute AC joint injuries, leading to a lack of confidence in reproducibility and reliability.

The anterior borders of the clavicle and the acromion are not always aligned in the intact acromioclavicular joint: a cadaveric study

BACKGROUND

The aim of this study was to find reliable anatomic landmarks of the normal acromioclavicular joint (ACJ) that could enable the precise evaluation of the horizontal displacement of the clavicle after dislocation. The hypothesis was that the anterior borders of the acromion and the clavicle are always aligned in intact ACJs.

MATERIALS AND METHODS

In 30 cadaveric specimens, the anterior and posterior borders of the ACJ's articular facets and the most prominent anterior and posterior bony landmarks of the acromion and the clavicle were identified. The anterior and posterior overhang of the acromion and the clavicle was measured in relation to the borders of the articular facets. Therefore, the possible anterior and posterior alignment of the ACJ was evaluated.

RESULTS

Anteriorly, only 18 ACJs (60%) were aligned whereas 7 (24%) had major overhang of the acromion and 3 (10%) had major overhang of the clavicle. Similarly, 18 cases (60%) were posteriorly aligned, whereas 6 (20%) had major clavicular overhang and 4 (14%) had major overhang of the acromion. In 78% of these cases, the ACJ was aligned as well anteriorly as posteriorly (P < .001). Finally, the larger the width of the acromion (P = .032) or the clavicle (P = .049), the better the posterior joint alignment.

CONCLUSION

Our hypothesis was not verified. The acromion and clavicle are not perfectly aligned in a significant number of specimens with intact ACJs (40% of cases). The most reliable landmarks remain their articular facets.

Comparative study on the treatment of Rockwood type III acute acromioclavicular dislocation: Clinical results from the TightRope® technique vs. K-wire fixation

BACKGROUND AND HYPOTHESIS

The aim of this study was to address the inconsistency regarding the operative treatment of Rockwood type III acromioclavicular joint separation. We compared results after single- and double TightRope^® reduction with results after acromioclavicular transfixation via K-wires only and additional ligament augmentation in acute acromioclavicular (AC) joint separations graded Rockwood type III, and hypothesized that the TightRope^® technique leads to better clinical and radiological results.

MATERIALS AND METHODS

We conducted a retrospective clinical cohort study and included 42 consecutive patients (mean age 43 years [24-66]) diagnosed and operatively treated between 2004 and 2012 (mean follow-up was 54.6 months [15-118]). Specific shoulder scores as well as scores reflecting the patients' overall mental and physical health status were used. Radiological evaluation was also performed.

RESULTS

The SF12 test revealed comparability between all subgroups. Specific shoulder tests and a visual analogue scale demonstrated comparable results. Radiographic measurements showed a significant reduction in the AC distance and CC distance after surgery in all subgroups. The early complication rate was 9.5% for all patients, while late complications occurred in 14.3% of all cases.

CONCLUSIONS

Compared to the established methods, the operative TightRope^® procedures represent a safe alternative in Rockwood III injuries. All investigated techniques predominantly led to good and excellent clinical results in acute Rockwood type III AC joint instabilities. Avoidance of material removal and shorter hospital stays appear to speak in favour for the TightRope^® technique.

LEVEL OF EVIDENCE

IV.

Functional Outcomes of Type V Acromioclavicular Injuries With Nonsurgical Treatment

INTRODUCTION

This study investigated nonsurgical management of type V acromioclavicular (AC) injuries to determine functional outcomes and to attempt to identify factors associated with positive results.

METHODS

In a retrospective chart review, patients with radiographic and clinical evidence of type V AC injuries per the Rockwood classification were included in the study. Patients treated nonsurgically for ≥6 months were considered eligible for analysis. Functional outcomes were assessed using Disabilities of the Arm, Shoulder, and Hand (DASH) and American Shoulder and Elbow Surgeons (ASES) scores.

RESULTS

Twenty-two patients with a mean age of 42.2 ± 12.8 years were included in the study. The average coracoclavicular distance at the time of presentation was 26.3 mm (+199%). Mean DASH and ASES scores were 27.8 ± 17.7 and 62.8 ± 17.1, respectively, at an average of 34 months from the time of injury. Patients with normal DASH (≤10) and ASES (>92) scores were younger than those with abnormal scores. At final assessment, 77% of the patients were currently working, with nine patients performing manual labor.

CONCLUSION

Following nonsurgical management of type V AC injuries, most patients are able to return to work but have limited functional outcome scores. A small subset of patients with type V AC injuries can achieve normal functional outcomes with nonsurgical management.

LEVEL OF EVIDENCE

Level IV, Case Series.

Long-term outcomes of tension band wiring with a single K-wire in Rockwood type IV/V acute acromio-clavicular dislocations: 25 cases

BACKGROUND

Our objective was to evaluate the long-term functional and radiological outcomes of tension band wiring with a single K-wire for acute Rockwood types IV and V acromio-clavicular dislocation (ACD).

METHODS

Single-centre cross-sectional non-randomised observational cohort study of 25 shoulders treated surgically between January 2002 and December 2004, in 25 patients, 23 males and 2 females, with a mean age of 35±11years (24-46). The evaluation criteria were the absolute and weighted Constant scores, QuickDASH score, subjective shoulder value (SSV), visual analogue scale (VAS) pain score at rest and during activities, and radiographic features in clinically symptomatic patients.

RESULTS

Mean values were as follows: follow-up, 150±17months (133-167); absolute Constant score, 88±17 (71-105); weighted Constant score, 92.5±12.5 (80-105); QuickDASH, 15.5±7 (8.5-22.5); SSV, 88±17% (71-105); VAS pain score at rest, 0.2±0.7 (0-0.9); and VAS pain score while active, 1.4±2.3 (0-3.7). The weighted Constant score was less than 70% in only 8% of patients. Of the 17 patients for whom radiographs were obtained, 8 had acromio-clavicular osteoarthritis. Mean coraco-clavicular distance was 12.3±4.3mm (8-16.6) and mean acromio-clavicular distance was 5±5mm (0-10). The recurrence rate was 8%.

CONCLUSION

Tension band wiring with a single K-wire for acute acromio-clavicular dislocation reliably provides good long-term functional outcomes. Recurrences are uncommon and few patients experience symptoms (8%).

LEVEL OF EVIDENCE

IV, retrospective study.