Comparative clinical outcomes and radiological images of clavicle hook plate versus Scorpion Plate® for unstable distal clavicle fractures.

BACKGROUND: Although various surgical methods are available for unstable distal clavicle fractures, consensus remains lacking on the optimal technique. Therefore, the present retrospective study aimed to compare the clavicle hook plate and Scorpion Plate® in terms of clinical outcomes and radiological findings for unstable distal clavicle fractures. METHODS: Fifty-seven patients with unstable distal clavicle fractures who underwent treatment using a clavicle hook plate (Group H; 28 patients) or Scorpion Plate® (Group S; 29 patients) were included in the present study. No patients received additional augmentation and all were followed-up for >1 year (mean follow-up, 28 months). Clinical outcomes were operation time, bleeding volume, complications, range of motion (ROM) at 6 months after surgery and final follow-up, and clinical scores (Constant-Murley score and University of California, Los Angeles (UCLA) shoulder score). Radiological outcomes assessed were coracoclavicular distance (CCD), difference in CCD between affected and non-affected sides (ΔCCD), and acromioclavicular subluxation ratio (%ACS) from plain X-rays. The χ2 test and Mann-Whitney U test were used to compare each outcome. RESULTS: Complications were seen in 3 shoulders (10.7%) in Group H. ROM was significantly worse in Group H at 6 months postoperatively, but no significant differences between groups were evident at final follow-up. Moreover, no significant differences in clinical outcomes were seen between groups. In terms of radiological results, Group H showed greater improvement in CCD and ΔCCD than Group S. Further, %ACS was significantly worse in Group S. CONCLUSIONS: The clavicle hook plate allows reconstruction of a more anatomical position than the Scorpion Plate®, but carries a greater risk of complications. Conversely, the Scorpion Plate® has a low risk of complications, but acromioclavicular subluxation remains. However, no significant differences in ROM or clinical outcomes were apparent at final follow-up.

Acromioclavicular and coracoclavicular ligamentous insertion distances depend on the scapular tilt and decrease with anterior direction of the inferior scapula angle.

PURPOSE: A variety of reconstruction techniques exist for the operative treatment of a ruptured acromioclavicular and coracoclavicular ligamentous complex. However, the complication rate remains high; between 5 and 89%. The intraoperative distance between the clavicle, acromion and coracoid is important for the refixation quality. In this study, the influence of scapular deflection on coracoclavicular and acromioclavicular distances was analysed. METHODS: The ligamentous insertions of 24 fresh-frozen human scapulae were exposed. The coracoclavicular and acromioclavicular ligaments were referenced and captured in a rigid body system using a three-dimensional (3D) measurement arm. The inferior angle of the scapula was manually pulled into maximum anterior and posterior deflection, simulating a patient positioning with or without dorsal scapular support, respectively. Based on the rigid body system, the distances between the ligamentous insertions were calculated. Statistical evaluation was performed by setting the distances in anterior deflection to 100% and considering the other distances relative to this position. RESULTS: The scapular deflection had a considerable impact on the distance between the ligamentous insertions. Concerning the conoid ligament, the mean distance was almost doubled when the inferior angle pointed posteriorly compared to anterior deflection (195.3 vs 100.0%; p = 0.028). The insertion of the acromioclavicular capsule also showed a significant association with the direction of deflection (posterior = 116.1% vs. anterior = 100%; p = 0.008). CONCLUSION: Dorsal support shifting the inferior angle of the scapula anteriorly reduces the distance between the ligamentous insertions. Therefore, a patient position on a shoulder table with posterior support of the scapula is recommended to reliability reduce the acromioclavicular joint.

Stability, deformity, and fixation of the floating shoulder: a cadaveric biomechanical study.

BACKGROUND: Floating shoulder injuries cause instability and deformity due to disruptions of the scapula, clavicle, and superior shoulder suspensory complex ligaments (SSSC). Resulting deformity of the glenopolar angle (GPA) has not previously been established, nor has the impact on stability and deformity when surgical fixation is performed. This study sought to quantify stability and deformity for multiple injury patterns and the improvement to these parameters provided by clavicle and coracoclavicular (CC) ligament fixation. METHODS: Fourteen cadaveric specimen upper extremities were used, which included the entire upper extremity, scapula, clavicle, and cranial-most ribs. After being mounted upright, a scapular neck fracture was created, followed by either a midshaft clavicle fracture or sectioning of the acromioclavicular and coracoacromial ligaments. Subsequent sectioning of the other structure(s) followed by the CC ligaments was then performed. In all specimens, the clavicle was then plated, followed by a CC ligament repair. At each step, a radiograph in the AP plane of the scapula was taken to measure GPA and displacement of the glenoid fragment using radiopaque markers placed in the scapula. These radiographs were taken both unloaded and with a 100-N applied medializing force. RESULTS: When evaluating deformity related to sectioning, the GPA was reduced when the CC ligaments were sectioned compared to an isolated scapula fracture (P = .022) and compared to a combined scapula and clavicle fracture (P = .037). For stability, displacement with a 100-N force was significantly increased when the CC ligaments were sectioned compared to an isolated scapula fracture (P = .027). In cases of an ipsilateral scapula neck and clavicle fracture with intact ligaments, fixation of the clavicle alone provided a statistically significant improvement in the GPA (P = .002); but not in reduction of displacement (P = .061). In cases of an ipsilateral scapula neck and clavicle fracture with concomitant disruption of the coracoacromial, acromioclavicular, and CC ligaments, the GPA was improved by clavicle fixation (P < .001) and increasingly so by subsequent CC ligament repair (P < .001). Displacement was also improved in these 2 states (P < .001, P = .008, respectively). DISCUSSION: This biomechanical study confirmed the importance of the acromioclavicular, coracoacromial, and CC ligaments in conferring stability in SSSC injuries. Disruption of the CC ligaments created significant deformity of the GPA and instability with a medializing force. Clinical treatment should consider the integrity of these ligaments and their repair in conjunction with clavicle fixation, knowing that this combination should restore a biomechanical state equivalent to an isolated scapula fracture.

Triple Endobutton technique for the treatment of Neer type II lateral clavicle fractures: 2-year findings.

BACKGROUND: Although various kinds of operative procedures have been reported in the literature, there is still no undisputed gold standard technique for the treatment of Neer type II lateral clavicle fractures. This trauma is classified as a bone fracture, but it is primarily a ligamentous problem due to the instability it generates. This study analyzed the clinical and radiological results of treatment for Neer type II lateral clavicle fractures using the triple Endobutton (Smith & Nephew) technique in 20 patients with at least 2 years of follow-up. METHODS: This study enrolled 20 patients with Neer type II distal clavicle fractures who underwent the triple Endobutton technique using 3 Endobuttons (1 with a closed loop and 2 without) and 3 No. 5 Ethibond sutures (Ethicon Inc.) from October 2017 to May 2020. Patients were assessed with clinical and radiological follow-up at 3, 6, 12, and 24 months postoperatively. Clinical assessments consisted of the visual analog scale and the Constant score. Radiological evaluation was achieved by measuring the coracoclavicular distance. RESULTS: The mean follow-up was 35 ± 9 months (range, 24-55 months). The visual analog scale and Constant scores revealed significant improvements from 6 ± 1 (range, 4-8) and 42 ± 4 (range, 35-48) scores preoperatively to 1 ± 1 (range, 0-1) and 94 ± 2 (range, 90-98) scores at the final evaluation, respectively (P < .001). The coracoclavicular distance of the injured side was an average of 9 ± 1 mm (range, 7-12 mm) at the final follow-up radiograph which was not significantly different from that of the contralateral side (P = .75). CONCLUSIONS: In this study, the triple Endobutton technique was a safe, reliable, and novel surgical technique that yielded good to excellent short-term clinical and radiological outcomes for the treatment of Neer type II distal clavicle fractures.

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.

Truly anatomic coracoclavicular ligament reconstruction with 2 EndoButton devices for acute Rockwood type V acromioclavicular joint dislocations: 5-year findings.

BACKGROUND: To date, mid-term clinical and radiologic outcomes of treatment for acute Rockwood type V acromioclavicular (AC) joint dislocations using 2 EndoButton devices (Smith & Nephew, Andover, MA, USA) have not been reported in the literature. METHODS: We reviewed 25 patients (15 men and 10 women) with acute AC joint separations who were treated with truly anatomic coracoclavicular ligament reconstruction using 2 EndoButton devices between May 2013 and October 2015. Clinical assessments consisted of the visual analog scale score and the Constant score. Radiologic evaluation was achieved by measuring the coracoclavicular distance and AC distance. Previously, this same patient cohort was reviewed after 2 years of follow-up using similar methods. RESULTS: All 25 patients were available for mid-term follow-up 5 years after the operation. The mean duration of follow-up was 76 ± 7 months (range, 66-90 months). Of the patients, 23 (92%) continued to be satisfied or very satisfied with the treatment results. The visual analog scale score and Constant score improved significantly when compared with the baseline scores (0 ± 0 and 96 ± 3, respectively, at 5-year follow-up vs. 5 ± 1 and 45 ± 6, respectively, postoperatively) and remained essentially unchanged when compared with the 2-year follow-up data (0 ± 0 and 96 ± 3, respectively, at 5-year follow-up vs. 0 ± 1 and 95 ± 3, respectively, at 2-year follow-up). On the 5-year radiographs, 3 patients (12%) demonstrated loss of reduction and 5 patients (20%) had calcifications noted. There was, however, no significant difference in clinical outcomes or patient satisfaction when comparing patients with radiographically abnormal findings vs. patients with anatomic reduction. CONCLUSION: Truly anatomic coracoclavicular ligament reconstruction using 2 EndoButton devices results in satisfactory functional outcomes at 5 years postoperatively. In contrast to baseline, all cases improved significantly.

Acromioclavicular joint stabilization with a double cow-hitch technique compared to a double tight-rope: a biomechanical study.

INTRODUCTION: The aim of the present biomechanical study was to evaluate the stability of a novel simple and cost-effective mini-open double cow-hitch suture button technique of acromioclavicular (AC) joint stabilization in comparison to a well-established double tight-rope technique. MATERIALS AND METHODS: A total of 12 fresh-frozen cadaveric shoulders were randomized into two treatment groups. In either a coracoclavicular stabilization with a standard double tight-rope technique (Group 1; n = 6, age 78 years ± 10) or a double cow-hitch with two No. 5 FiberWire strains looped in a bicortical button placed at the bottom of the coracoid process (Group 2; n = 6, age 80 years ± 13). Both techniques were equally augmented with an AC joint cerclage using a FiberTape. All shoulders were tested in a servo-hydraulic material testing machine for elongation/cyclic displacement (in mm) after cyclic loading (70 N cyclical load, 1500 cycles), stiffness (N/mm) and ultimate load to failure (N). The mechanism of failure was recorded. All tests were performed in a previously published testing setup. RESULTS: After 1500 cycles, group 2 showed a cyclic displacement of 1.67 mm (SD 0.85), compared to 1.04 mm (SD 0.23) cyclic displacement in group 1 (p = 0.11). The cyclic displacement after AC reconstruction in group 1 was 0.36 mm lower than in the native state with intact ligaments (p = 0.19), whereas the cyclic elongation in group 2 was 0.05 mm higher compared to the native situation (p = 0.87). Stiffness after reconstruction was significantly higher in group 1 compared to the native specimen (p = 0.001), in group 2 it was similar as before the reconstruction (p = 0.64). Ultimate load to failure and stiffness were higher in group 1 with 424 N (SD 237) and 68.6 N/mm (SD 8.2), compared to 377 N (SD 152) and 68 N/mm (SD 13.3) in group 2, without reaching statistical significance (p = 0.69 and 0.89). The most common failure modes were clavicular fractures at the tight rope drill holes (n = 2) and clavicular fractures medially at the fixation site (n = 2) in group 1, and coracoid button break-through (n = 3) and clavicular fractures medially at the fixation site (n = 2) in group 2. CONCLUSIONS: Stabilization of the AC joint with a novel mini-open double cow-hitch suture button technique resulted in a similar low elongation, high stiffness and ultimate load to failure compared to a double tight-rope technique. This cost-effective technique for AC joint stabilization could demonstrate a sufficient biomechanical stability with especially high stiffness and load-to-failure. LEVEL OF EVIDENCE: Biomechanical study.

The ligamentous injury pattern in acute acromioclavicular dislocations and its impact on clinical and radiographic parameters.

BACKGROUND: Acromioclavicular (AC) joint dislocations are classified according to the Rockwood (RW) classification, which is based on radiographic findings. Several authors have suggested magnetic resonance imaging (MRI) for visualization of the capsuloligamentous structures stabilizing the AC joint. The aim of this study was to describe the ligamentous injury pattern in acute AC joint dislocations by MRI and investigate associations with clinical and radiographic parameters. METHODS: This prospective study included 45 consecutive patients (5 women and 40 men; mean age, 33.6 years [range, 19-65 years]) with an acute AC joint separation (RW type I in 5, RW type II in 8, RW type III in 18, and RW type V in 14). All patients underwent physical examination of both shoulders, and clinical scores (Subjective Shoulder Value, Constant score, Taft score, and Acromioclavicular Joint Instability Score) were used to evaluate the AC joint clinically as well as radiographically. Post-traumatic radiography included bilateral anteroposterior stress views and bilateral Alexander views to evaluate vertical instability and dynamic posterior translation. MRI was performed for assessment of the AC and coracoclavicular (CC) ligaments and the delto-trapezoidal fascia. RESULTS: Radiographic and MRI classifications were concordant in 23 of 45 patients (51%), whereas 22 injuries (49%) were misjudged; of these, 6 (13%) were reclassified to a more severe type and 16 (36%), to a less severe type. The integrity of the CC ligaments was found to have a clinical impact on vertical as well as horizontal translation determined by radiographs and on clinical parameters. Among patients with an MRI-confirmed complete disruption of the CC ligaments, 68% showed a radiographic CC difference > 30% and 75% showed complete dynamic posterior translation. Inferior clinical parameters were noted in these patients as compared with patients with intact CC ligaments or partial disruption of the CC ligaments (Constant score of 67 points vs. 49 points [P < .05] and Acromioclavicular Joint Instability Score of 51 points vs. 23 points [P < .05]). The inter-rater and intra-rater reliability for assessment of the ligamentous injury pattern by MRI was fair to substantial (r = 0.37-0.66). CONCLUSION: The integrity of the CC and AC ligaments found on MRI has an impact on clinical and radiographic parameters.

Stand-alone coracoclavicular suture repair achieves very good results in unstable distal clavicle fractures at a minimum follow-up of 1 year.

BACKGROUND: The treatment of unstable (Neer type IIB and V) extra-articular distal clavicle fractures remains challenging, especially when encountering a small lateral fragment which does not allow for sufficient screw purchase. It was the purpose of this study to present the clinical and radiologic outcome of a consecutive series of patients treated by a stand-alone coracoclavicular stabilization using a so-called cow-hitch technique with a suture anchor. METHODS: Nineteen patients were treated with a specific surgical technique for distal clavicle fractures (11 left, 8 right) with either rupture or bony avulsion of the coracoclavicular ligaments. Fourteen patients were examined in our outpatient clinic for the purpose of this study after a mean follow-up of 5 years (1-12.2 years). The examination included scoring according to Constant Murley score (CMS), the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), the Subjective Shoulder Value (SSV), and follow-up radiographs. Two additional patients were amenable to a telephone interview. RESULTS: All patients reported very good subjective results, with a mean SSV of 92% and a mean ASES score of 96%. The CMS resulted in average absolute values of 92 points. Fractures consolidated in 95% of cases. One patient developed an asymptomatic pseudarthrosis. The coracoclavicular distance was restored from 21 mm preoperatively to 11 mm at the final follow-up and finally showed an average side-to-side difference of +1.8 mm. Sports activities were fully resumed after an average of 4.7 months. CONCLUSION: The coracoclavicular stand-alone cow-hitch suture repair for unstable distal clavicle fractures is a minimally invasive fixation technique without prominent hardware that allows for an anatomic reduction and stable fixation with a low complication and high bony union rate. Both radiographic and clinical long-term results are very satisfactory.

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.

Synthetic coracoclavicular ligament vs. coracoclavicular suspensory construct for treatment of acromioclavicular dislocation: a biomechanical study.

BACKGROUND: A synthetic ligament (LockDown, Worcestershire, England) has become available to treat complete acromioclavicular dislocation with promising clinical results and potential benefit to avoid postoperative loss of reduction. We investigated the biomechanics of this synthetic ligament in a simulated immediate postoperative rehabilitation setting, hypothesizing that the synthetic ligament would demonstrate less superior coracoclavicular displacement to cyclic loading and higher ultimate load-to-failure values than a coracoclavicular suspensory construct. METHODS: Seven matched-pair cadaveric shoulders (mean age at time of death, 79 years) were loaded cyclically and to failure. One specimen in each pair was randomly assigned to the synthetic ligament or coracoclavicular suspensory construct. Superiorly directed 70-N cyclic loading for 3000 cycles at 1.0 Hz was applied through the clavicle in a fixed scapula simulating physiologic states during immediate postoperative rehabilitation, followed by a load-to-failure test at 120 mm/min. RESULTS: After 3000 cycles, the superior displacement of the clavicle in the synthetic ligament (9.2 ± 1.1 mm) was 225% greater than in the coracoclavicular suspensory construct (2.8 ± 0.4 mm, 95% confidence interval [CI] 3.4, 8.3; P < .001). Average stiffness of the synthetic ligament (32.8 N/mm) was 60% lower than that of the coracoclavicular suspensory construct (81.9 N/mm, 95% CI 43.3, 54.9; P < .001). Ultimate load-to-failure of the synthetic ligament was 23% (95% CI 37.9, 301.5; P = .016) lower than the coracoclavicular suspensory construct (580.5 ± 85.1 N and 750.2 ± 135.5 N, respectively). CONCLUSION: In a simulated immediate postoperative cadaveric model, the synthetic ligament demonstrated poorer biomechanics than the coracoclavicular suspensory construct. These findings suggest that a coracoclavicular suspensory construct may be preferable to a synthetic ligament if early rehabilitation is intended.

Truly anatomic coracoclavicular ligament reconstruction with 2 Endobutton devices for acute Rockwood type V acromioclavicular joint dislocations.

BACKGROUND: Truly anatomic coracoclavicular ligament reconstruction (TACCR) according to the original insertions is a creative new method for the treatment of severe acromioclavicular separation. This research analyzed the clinical and radiologic results of TACCR in 25 patients with at least 2-year follow-up. METHODS: The study enrolled 25 patients with Rockwood type V acromioclavicular joint dislocations who underwent TACCR using 2 Endobutton (Smith & Nephew Inc., Andover, MA, USA) devices from May 2013 to October 2015. Patients were assessed with clinical and radiologic follow-up at 3, 6, 12, 18, and 24 months postoperatively. The clinical assessments consisted of the visual analog scale and the Constant score. The radiographic evaluations were performed by measurements of the coracoclavicular distance. RESULTS: The mean follow-up was 34 ± 6.8 months (range, 24-48 months). The visual analog scale and Constant scores revealed significant advancements from 5 ± 0.9 (range, 4-7) and 45 ± 5.6 (range, 30-54) scores preoperatively to 0 ± 0.5 (range, 0-2) and 95 ± 2.9 (range, 91-98) scores at 24 months postoperatively, respectively. The coracoclavicular distance significantly decreased from 23 ± 5.4 mm (range, 16-34 mm) preoperatively to 8 ± 0.9 mm (range, 7-10 mm) at the final follow-up. CONCLUSIONS: TACCR represents a safe, reliable and creative surgical technique that yields good to excellent clinical and radiologic outcomes in the treatment of severe acromioclavicular separation.

Distal clavicle fracture radiography and treatment: a pictorial essay.

Fractures of the distal clavicle represent 15-30% of all clavicle fractures. The local osseoligamentous anatomy and deforming forces result in increased risk of delayed union and nonunion than fractures in other parts of the clavicle. These factors also contribute to challenges in fracture repair. Understanding these injuries and their imaging features enhances care and ensures patients are directed to appropriate management. We review the anatomy of the distal clavicle and surrounding ligaments, options for radiographic evaluation, relevant classification systems, and current concepts in management. Illustrative examples of specialized views are provided. Pediatric acromioclavicular joint pseudosubluxation is also reviewed, with findings specific to that injury.

Management of chronic unstable acromioclavicular joint injuries.

The acromioclavicular joint represents the link between the clavicle and the scapula, which is responsible for the synchronized dynamic of the shoulder girdle. Chronic acromioclavicular joint instability involves changes in the orientation of the scapula, which provokes cinematic alterations that might result in chronic pain. Several surgical strategies for the management of patients with chronic and symptomatic acromioclavicular joint instability have been described. The range of possibilities includes anatomical and non-anatomical techniques, open and arthroscopy-assisted procedures, and biological and synthetic grafts. Surgical management of chronic acromioclavicular joint instability should involve the reconstruction of the torn ligaments because it is accepted that from three weeks after the injury, these structures may lack healing potential. Here, we provide a review of the literature regarding the management of chronic acromioclavicular joint instability. LEVEL OF EVIDENCE: Expert opinion, Level V.

Acromioclavicular joint biomechanics: a systematic review.

Background: The aim of this systematic review was to investigate the available literature on the biomechanical characteristics of the acromioclavicular (AC) joint to identify trends in translational parameters and contributions of the various ligamentous structures supporting the joint. Methods: A comprehensive literature search was conducted in the Web of Science, Scopus, and PubMed databases until October 2023 to identify articles reporting on the biomechanical characteristics of the AC joint. Non cadaveric or projects involving reconstruction were excluded. Consistent parameters evaluated were anterior, posterior, superior, and inferior translation. The data were extracted from the included articles and summarized. Results: 11 biomechanical papers were reviewed from six different countries - United States (n = 6), France (n = 1), Austria (n = 1), Thailand (n = 1), United Kingdom (n = 1), and Japan (n = 1). The total number of specimens included across the reviewed papers was 141. All 11 papers reported the data on an intact model (coracoclavicular and AC ligaments intact). Seven papers assessed the translational results of the AC sectioned condition, finding a greater increase in anterior-posterior (AP) laxity relative to SI. 3 papers evaluated coracoclavicular ligament sectioning, finding increased superior-inferior laxity relative to AP. Only one study involved ligament sectioning isolating the anterior-inferior bundle of the AC joint. Conclusion: This review highlights the key AP and superior-inferior constraints of both the intact and ligament sectioned AC joint. The inconsistency of AC joint testing parameters and the lack of thorough translation studies indicate a necessity for increased attention in the overall assessment of shoulder stability to close the gap in the foundational biomechanical research.

Biomechanical evaluation of fixation of the coracoclavicular stand-alone cow-hitch suture reconstruction in comparison to two established techniques for highly unstable distal clavicle fractures (Neer type V).

Background: Treatment of displaced distal clavicle fractures with bony avulsion of the coracoclavicular (CC) ligaments often warrants surgical fixation, yet a gold standard surgical technique is to be defined. The purpose of this study was to compare the biomechanical fixation strength of a new fixation technique, the CC stand-alone cow-hitch suture reconstruction, and to compare this technique with a clavicle hook plate and a lateral locking plate with CC suture reconstruction. Methods: Simulated Neer type V distal clavicle fractures of the clavicle were created in 18 cadaveric shoulders, which were matched by age and gender in 3 groups: (1) clavicle hook plate (group HP), (2) lateral locking plate fixation with CC suture reconstruction (group LPCC), and (3) CC stand-alone suture reconstruction using the cow-hitch technique (group CH). After preconditioning with 25 N for 10 cycles, the specimens were cycled in the coronal plane for 500 cycles from 10N to 70N. Displacement and ultimate load to failure were documented and analyzed with the data acquisition system. Results: There was a significant difference in the fracture displacement during cyclic loading between the LPCC group and the HP group (0.6 vs. 1.7 mm; P = .02) and between the CH and HP groups (0.5 vs. 1.7 mm; P = .004). Fracture displacement was not different between the LPCC and the CH groups (P = .544). The CH group and the LPCC group showed a significantly higher stiffness compared to the HP group (P < .001 and P = .003, respectively). The CH group showed a significantly higher ultimate load to failure compared with the HP group (429 vs. 172 N; P = .005) and showed a tendency toward higher ultimate load to failure when compared with the LPCC group (429 vs. 258 N; P = .071). Conclusion: The CC stand-alone cow-hitch suture reconstruction and the locking plate with CC reconstruction showed higher fixation strength compared with the hook plate for simulated Neer type V distal clavicle fractures. There was a tendency of higher ultimate load to failure with the cow-hitch technique compared with the lateral locking plate with CC suture reconstruction, and given the potential advantages of less soft tissue stripping, metal-free fixation, low costs, and simple surgical technique, clinical application of the all-suture CC reconstruction using the cow-hitch for Neer type V distal clavicle fractures appears warranted.

Arthroscopic Repair and Reconstruction of Coracoclavicular Ligament.

Acromioclavicular joint separations are common shoulder injuries that require prompt recognition, diagnosis, and treatment. Deciding on a treatment algorithm relies on a detailed knowledge of anatomy and a thorough understanding of the specific functional demands of the patient in question. When a repair or reconstruction is indicated, arthroscopic assistance can be a helpful tool to ensure a safe, anatomic reconstruction that minimizes morbidity and maximizes the potential return to high-level function.

Management of Acromioclavicular Joint Injuries: A Historic Account.

There has been a rapid evolution in best practice management of acromioclavicular (AC) joint injuries. AP, Zanca, scapular Y, and dynamic axillary radiographic views provide optimal visualization of the joint and may assess for the presence of horizontal AC instability. Severity of AC joint pathology is classified according to the 6-tier Rockwood scoring system. Over 160 surgical techniques have been described for AC joint repair and reconstruction in the last decade; as a result, determining the optimal treatment algorithm has become increasingly challenging secondary to the lack of consistently excellent clinical outcomes.

Acromioclavicular Joint Anatomy and Biomechanics: The Significance of Posterior Rotational and Translational Stability.

The shoulder girdle extends from the sternoclavicular joint to the scapular stabilizing muscles posteriorly. It consists of 3 joints and 2 mobile regions. The shoulder girdle is statically stabilized by the acromioclavicular and coracoclavicular capsuloligamentous structures and dynamically stabilized by the trapezius, deltoid, and deltotrapezial fascia. During humerothoracic elevation, the clavicle elevates, protracts, and rotates posteriorly through the sternoclavicular joint while the scapula tilts posteriorly and rotates upward. The purpose of this article is to review the anatomy and biomechanics of the acromioclavicular joint and the shoulder girdle.

Operative Management for Displaced Distal Clavicle Fractures.

This article reviews techniques and outcomes of surgical fixation for distal clavicle fractures. Near 100% union has been reported for several techniques. The most common are locked plating, coracoclavicular fixation and a combination of plating with CC fixation. Hook plates are useful for particular fracture patterns, but there can be complications specific to this implant. Low-profile constructs are favored due to the high rates of symptomatic hardware. Fixation of subacute and chronic injuries can provide reliable functional improvements, but is inferior to acute fixation. Surgery is generally the treatment of choice for displaced fractures in athletes.