Three-dimensional morphological analysis of acromioclavicular joint in patients with and without subacromial erosion after hook plate fixation

In Vivo Analysis of Acromioclavicular Kinematics and Distance During Multiplanar Humeral Elevation

BACKGROUND

Knowledge of acromioclavicular (AC) joint kinematics and distance may provide insight into the biomechanical function and development of new treatment methods. However, accurate data on in vivo AC kinematics and distance between the clavicle and acromion remain unknown.

PURPOSE/HYPOTHESIS

The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared.

RESULTS

Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001).

CONCLUSION

Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased.

CLINICAL RELEVANCE

These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.

The correlation between acromial osteolysis and acromion types in the treatment of acromioclavicular joint dislocation with hook plate

This study aimed to radiologically evaluate the effect of hook plates used in the treatment of acromioclavicular joint (ACJ) dislocations on the development of subacromial osteolysis (SAO) according to acromion types. A total of 43 patients with mean age of 38.5 (19-77) years who were diagnosed with AC dislocation and applied neutral clavicular hook plate between 2013 and 2020 were retrospectively evaluated. Acromion types were determined by measuring acromion slope angle on lateral shoulder radiography and 3-dimensional (D)-CT of the patients. Presence of SAO was classified according to the severity of erosion in the subacromial region (grade I: minimal osteolysis, grade II: subacromial erosion <2 mm, grade III: subacromial erosion >2 mm, grade IV: cut-through of the acromion) on postoperative 3D - CT and correlation with acromion types was analyzed. Incidence of SAO was significantly higher among type 1 acromion compared to type 2 and type 3 acromion (P = .003). While osteolysis was observed in 21 patients, no osteolysis was observed in 22 patients. Osteolysis occurred in all patients with type 1 acromion, 7 patients with type 2 acromion, and 5 patients with type 3 acromion. Since the hook tip in the sagittal plane passes posterior to the center of the acromion and the concavity of the subacromial surface is inadequate in the type 1 acromion, we believe that the increased pressure applied by the hook tip on the subacromial cartilage increases the risk of SAO. We predict that the use of hook plates with an angle of 15-20 degrees, similar to the patient's AC angle, rather than neutral hook plate, will reduce the risk of osteolysis in patients with type 1 acromion.

Clinical and radiological outcome of acute high-grade acromioclavicular joint dislocation: A retrospective cohort study on Hook plate versus arthroscopic assisted single coracoclavicular tunnel with DogBone™ button dual FiberTape® construct

Purpose

Hook plate (HP) is a popular implant of choice in the management of highgrade acute acromioclavicular joint (ACJ) dislocations. Recently, suspensory loop systems have drawn significant interest with comparable results and additionally does not warrant implant removal. However, no studies have compared the outcomes of HP vis-a-vis Dog Bone TM Button with dual FiberTape® (DB).

Methods

38 patients who underwent HP or Arthroscopic assisted single tunnel DB fixation to stabilize high-grade ACJ dislocations were retrospectively included in study for clinically and radiological evaluation at a minimum follow up of one year. American Shoulder and Elbow Society and Constant Murley scores were used for clinical assessment. The radiological evaluation was done by assessing quality of reduction, measuring coracoclavicular distance (CCD), and extent of subacromial erosion.

Results

For final follow up evaluation, both HP and DB group had 16 patients each. The mean follow-up was 55.38 ± 10.9 and 32.88 ± 14.0 months in HP and DB group, respectively. No significant difference in mean ASES (p=0.71) and CM score (p=0.62) was found between the two groups. The DB group revealed higher CCD at the final follow-up compared to the HP group (p=0.01). Although statistically insignificant, there were more subluxations and dislocations in the DB group (37.5%) compared to the HP group (25%). The subacromial erosion was noted in all cases of the HP group at time of implant removal.

Conclusion

Both groups revealed satisfactory functional and radiological outcome. However, the DB group showed a higher tendency of loss of reduction.

Is coracoclavicular reconstruction necessary in hook plate fixation for acute unstable acromioclavicular dislocation?

Background

Acromioclavicular joint (ACJ) dislocation is a relatively common shoulder injury. For the treatment of cases of severe ACJ dislocation (Rockwood type III–V), hook plate fixation is an easy-to-master and minimally-invasive approach to surgical intervention. Over stress on the acromion following hook plate fixation often leads to acromial complications such as osteolysis and loss of reduction. We hypothesized that suspensory reconstruction alongside hook plate fixation might provide a superior stability and reduce complications as compared with hook plate fixation alone. The purpose of the study was to assess the clinical and radiographic outcomes of these two surgical modalities.

Methods

We retrospectively enrolled 49 patients with acute ACJ dislocation from May 2010 to December 2018. Among them, 19 patients received hook plate fixation only (HP group), and 19 underwent concomitant hook plate fixation and loop suspension fixation with two mersilene sutures (HM group). The demographic data of the patients were recorded and analyzed. All patients underwent a shoulder X-ray initially, immediately postoperatively, and at 1, 3, 6 and 12 months to measure the relative coracoclavicular distance (rCCD). Clinical assessment of shoulder function outcome was conducted using the Constant Murley Score (CMS); the University of California at Los Angeles (UCLA) Shoulder Score was also measured at the latest follow-up.

Results

There were no significant differences in the demographic data between the two groups. With regards to the CMS and the UCLA score, the HM group and HP group both had excellent outcomes, and no significant differences in scores were observed between groups (CMS: 93.90 ± 6.16 versus 94.47 ± 7.26, p = 0.47; UCLA score: 32.84 ± 2.91 versus 34.32 ± 1.16, p = 0.07). However, the HM group demonstrated substantial superiority in terms of maintenance of the rCCD over the HP group (91.47 ± 27.47 versus 100.75 ± 48.70, p = 0.015). In addition, there was less subacromial osteolysis in the HM group than the HP group (52.6% versus 15.8%, p = 0.038).

Conclusion

Both fixations yielded excellent functional outcomes. However, concomitant hook plate fixation with loop suspensory reconstruction demonstrated the fewer acromion complications and statistical differences in reduction maintenance with less clinical significance.

Relationship between the lateral acromion angle and postoperative persistent pain of distal clavicle fracture treated with clavicle hook plate

Background

The clavicular hook plate is an accepted surgical procedure for distal clavicle fractures. The relationship of the characteristics of the hook plate, acromioclavicular joint and acromion morphology, and clinical outcome has remained poorly understood. We reviewed the clinical records of patients who had distal clavicle fractures with different lateral acromion angles treated using a clavicle hook plate and evaluated their clinical outcomes with respect to shoulder pain and acromial morphology.

Methods

We retrospectively reviewed 102 patients with distal clavicle fractures treated with hook plates at our institution from 2010 to 2017. They were divided into four groups according to lateral acromion angle on shoulder AP view X-rays. The angle was defined as the incline angle between the superior surface of distal clavicle and the inferior facet of acromion on coronal plane. We reviewed their clinical features, including Neer’s impingement sign, MRI findings, and outcomes using Japanese Orthopaedic Association Scores. The mean follow-up was 25.5 months (range, 24 to 28 months).

Results

All patients in group D (large lateral acromion angle (α) > 40°, acromion coronal angle (β) < 60°) complained of postoperative symptoms. Compared to those with common lateral acromion angle, the incidence of postoperative impingement in group D was undoubtedly much higher (100%). Japanese Orthopaedic Association (JOA) scores in group D were worse at 3 months post-surgery, 3 months post plate removal, and at the last follow-up despite a slightly earlier removal in this group.

Conclusion

Lateral acromion angle appears to be an important factor in the development of postoperative pain and worse outcomes (JOA scores) in patients treated with the hook plate. The incidence of subacromial impingement and rotator cuff lesion (RCL) increased with the α angle. Early limited mobility and removal of the implant may improve the prognosis and resolve the postoperative shoulder pain.

Study design

Retrospective review, level of evidence IV.