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

[Current treatment concepts of the lateral clavicle and the acromioclavicular joint]

Injurie to the lateral clavicle and acromioclavicular joint (ACJ) are frequent events which are relevant to everyday life and particularly affect active adults at the age of 20-40 years. The Rockwood classification has been established for the classification of ACJ injuries. Lateral clavicle fractures are classified according to the Neer classification or the Jäger and Breitner classification. A newly established classification is the Cho classification. Depending on the injury pattern and in particular the presence of instability, various conservative and surgical care strategies are used. This article provides an overview of the various treatment concepts.

Clavicular tunnel widening in chronic acromioclavicular joint instabilities after primary versus revision arthroscopically-assisted acromio- and coracoclavicular stabilization

Purpose

To evaluate joint reduction (loss of reduction [LOR]; dynamic posterior translation [DPT]) and clavicular tunnel widening (cTW) in patients treated with arthroscopically-assisted acromioclavicular joint (ACJ) stabilization after previously failed nonoperative versus surgical treatment.

Methods

Patients undergoing arthroscopically-assisted ACJ stabilization (bidirectional tendon allograft with a low-profile TightRope) after previously failed nonoperative versus surgical treatment were included retrospectively. Bilateral anteroposterior stress views served for evaluating LOR (side-comparative coracoclavicular distance [CCD]) and cTW at a 6-weeks- and 6-months-follow-up (FU) and for evaluating the filling ratio (FR, vertical device insertion depth relative to clavicle height) at the 6-weeks-FU. Postoperative DPT was assessed on Alexander's views.

Results

Twenty-seven patients (20 male, mean age 46.1 ± 14.8 years) were included (prior treatment: nonoperative: n = 15; surgical: n = 12). There were no differences in LOR, DPT or cTW between groups postoperatively. Initial CCD-symmetry at the 6-weeks-FU (CCD: -0.1 mm [95% confidence interval, CI, -2 to 1.4 mm]) was followed by LOR at the 6-months-FU (CCD: -3.5 mm [95% CI, -5.2 to -1.9 mm]; p < 0.001). cTW increased towards the inferior cortex, compared to the superior cortex and the intermediate level (p < 0.001, respectively). cTW at the inferior cortex was associated with more LOR (r = -0.449; p = 0.024) and DPT (r = 0.421; p = 0.036), dependent on a smaller FR (r = -0.430; p = 0.032).

Conclusion

Patients undergoing arthroscopically-assisted ACJ stabilization for chronic bidirectional ACJ instabilities showed comparable radiologic results after previous nonoperative versus surgical treatment. cTW increased towards the inferior cortex and was associated with recurrent vertical and horizontal instability, related to a smaller FR. More research into reduced cTW, for example, by a more filling device, should be performed.

Level of Evidence

Level III, retrospective comparative study.

Acromioclavicular joint dislocation Rockwood type III and V show no difference in functional outcome and 91% recovered well without the need for surgery

PURPOSE

Acromioclavicular (AC) joint dislocations are common injuries, but the indication for and timing of surgery is debated. The objective of the study was to evaluate the results after acute AC joint dislocations Rockwood type III and V treated nonsurgically with the option of delayed surgical intervention.

METHODS

This is a prospective cohort study with clinical, radiological and patient-reported outcome assessment at baseline, 6 weeks, 3 months, 6 months and 1 year after acute AC joint dislocation. Patients aged 18-60 with acute AC joint dislocation and a baseline panorama (Zanca) radiograph with an increase in the coracoclavicular distance of >25% compared to the uninjured side were eligible for inclusion. All patients were treated nonsurgically with 3 months of home-based training and with the option of delayed surgical intervention. The primary outcome was the Western Ontario Shoulder Instability Index (WOSI). Secondary outcomes were surgery yes/no and the Shoulder Pain and Disability Index (SPADI).

RESULTS

Ninety-five patients were included. Fifty-seven patients were Rockwood type III and 38 patients were type V. There were no statistically significant differences in WOSI and SPADI between patients with type III and V injuries at any time point. Nine patients (9.5%) were referred for surgery; seven type III and two type V (ns).

CONCLUSION

Ninety-one percent of patients with acute AC joint dislocation Rockwood type III and V recovered without surgery and there were no differences in outcome scores between type III and V at any time point.

LEVEL OF EVIDENCE

Level IV.

The ISAKOS subclassification of Rockwood type III AC joint dislocations in a stable type A and an unstable type B is not clinically relevant

PURPOSE

The treatment of Rockwood type III AC joint dislocations has been debated for decades. In 2014, the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Upper Extremity Committee suggested a subclassification of the injury into type A, considered stable and best treated nonsurgically, and type B, considered unstable and best treated surgically. Type B is defined by the presence of scapular dyskinesis and overriding of the clavicle to the acromion on a modified lateral radiograph. The objective of the study was to investigate if this subclassification is clinically relevant.

METHODS

This was a prospective cohort study. Inclusion criteria were patients aged 18-60 years with acute AC joint dislocation and a baseline Zanca radiograph with an increase in the CC distance of >25% compared to the uninjured side. All patients were treated nonsurgically with 3 months of home-based training and with the option of delayed surgical intervention. Patients were assessed at baseline and at follow-ups 6 weeks, 3 months, 6 months and 1 year after the injury. At the 6-week follow-up, patients were graded as stable and unstable according to the ISAKOS criteria. Outcomes were the Western Ontario Shoulder Instability Index (WOSI) and referral for surgery.

RESULTS

At 6 weeks of follow-up, 20 patients were classified as stable type A and 69 were classified as unstable type B. The ISAKOS subclassification was not clinically relevant, but patients graded as stable had statistically significantly better WOSI scores at 6 months compared to the unstable group (p = 0.03) but not at 3 months or 1 year. Nine patients (9.5%), all from the unstable group, were referred for surgery. No patients from the stable group underwent surgery (n.s).

CONCLUSION

The ISAKOS subclassification of Rockwood type III in a stable type A and an unstable type B is not clinically applicable.

LEVEL OF EVIDENCE

Level II.

Patient-reported, clinical and radiological factors associated with the result after non-surgical management of acute AC joint dislocation Rockwood type III and V

PURPOSE

The treatment of Rockwood type III and V acromioclavicular (AC) joint dislocations is controversial, and an individualized treatment algorithm is yet to be developed. The objective of this study was to investigate the association of demographical, clinical, patient-reported and radiological variables with the Western Ontario Shoulder Instability Index (WOSI) score and risk of surgery.

METHODS

Inclusion criteria for this prospective cohort study were patients aged 18-60 with an acute AC joint dislocation with >25% increase in the coracoclavicular distance on bilateral Zanca radiographs. Patients were treated non-surgically with 3 months of home-based training and the option of delayed surgical intervention. The outcomes were the WOSI score and surgery yes/no. Demographical, clinical, patient-reported (WOSI and Shoulder Pain and Disability Index [SPADI]) and radiological variables were collected at baseline and 6 weeks after the injury and investigated for association with the outcomes at 3 months, 6 months and 1 year.

RESULTS

Ninety-five patients with Rockwood type III/V AC joint dislocation were included. Pre-injury participation in overhead/collision sports was a risk factor for surgery with an odds ratio of 5 (p = 0.03). Reduced range of motion (ROM) at baseline was associated with reduced WOSI scores and increased risk of surgery. At 6 weeks, reduced ROM, increased SPADI and increased pain during cross-over were associated with the outcomes. Radiological measurements were not correlated with the result. At the 6 weeks follow-up, patients eventually requiring surgery could be detected with a sensitivity of 100% and a specificity of 94% based on a SPADI score of >30 and a ROM ≤ 140° in shoulder flexion or abduction.

CONCLUSION

ROM was the only variable consistently associated with both WOSI and risk of surgery. Six weeks after the injury, it was possible to detect patients in need of surgery based on ROM and SPADI with a sensitivity of 100% and a specificity of 94%.

LEVEL OF EVIDENCE

Level II.

The V angle compliments radiographic assessment of acute acromioclavicular joint dislocations by differentiating between Rockwood types III versus V and by considering dynamic horizontal translation in coronal radiographs

PURPOSE

Acromioclavicular joint (ACJ) dislocations are usually graded radiographically according to Rockwood, but differentiation between Rockwood types III and V may be ambiguous. The potentially clinically relevant horizontal instability is barely addressed in coronal radiographs. It was hypothesized that a new radiologic parameter (V angle) would complement ACJ diagnostics on anteroposterior radiographs by differentiating between cases of Rockwood III and V while also considering the aspect of dynamic horizontal translation (DHT).

METHODS

Ninety-five patients with acute ACJ dislocations (Rockwood types III and V) were included retrospectively between 2017 and 2020. On anteroposterior views (weightbearing: n = 62, non-weight-bearing: n = 33), the coracoclavicular (CC) distance and the newly introduced V angle for assessing scapular orientation were measured bilaterally. This angle is referenced between the spinal column and a line crossing the superior scapular angle and the crossing point between the supraspinatus fossa and the medial base of the coracoid process, reported as the side-comparative difference (non-injured side *minus* injured side). DHT on Alexander views was divided into stable, partially unstable or completely unstable.

RESULTS

The V angle on the injured side alone (mean 50.0°; 95% confidence interval (CI), 48.6°-51.3°) showed no correlation with the side-comparative CC distance [%] (r = - 0.040; n.s.). Thus, the V angle on the non-injured side was considered, displaying a normal distribution (n.s.) with a mean of 58.0° (95% CI, 56.6°-59.4°). The side-comparative V angle showed a correlation with the side-comparative CC distance (r = 0.83; p < 0.001) and was able to differentiate between Rockwood types III (4.7°; 95% CI, 3.9°-5.5°; n = 39) and V (10.3°; 95% CI, 9.7°-11.0°; n = 56) (p < 0.001). A cut-off value of 7° had a 94.6% sensitivity and an 82.1% specificity (area under curve, AUC: 0.954; 95% CI, 0.915-0.994). The side-comparative V angle was greater for cases with complete DHT (8.7°; 95% CI, 7.9°-9.5°; n = 78) than for cases with partial DHT (4.8°; 95% CI, 3.3°-6.3°; n = 16) (p < 0.001). A cut-off value of 5° showed a sensitivity of 84.6% and a specificity of 66.7% (AUC 0.824; 95% CI, 0.725-0.924).

CONCLUSION

The scapular-based V angle on anteroposterior radiographs distinguishes between Rockwood types III and V as well as cases with partial or complete DHT.

STUDY DESIGN

Diagnostic study.

LEVEL OF EVIDENCE

Level II.

Management of Acute High-Grade Acromioclavicular Joint Dislocations: Comparable Clinical and Radiological Outcomes After Bidirectional Arthroscopic-Assisted Stabilization With the Single Low-Profile Suture Button Technique Versus Double-Suture Button Technique

PURPOSE

To compare the 2-year clinical and radiological outcomes of an arthroscopic-assisted bidirectional stabilization procedure using a single low-profile (LPSB) or double-suture button (DSB) technique with additional percutaneous acromioclavicular (AC) cerclage fixation for patients with acute high-grade AC joint dislocation.

METHODS

This retrospective cohort study compared male patients aged between 18 and 56 years with acute high-grade AC joint dislocation fixed with either a LPSB or DSB technique. Patients were examined at least 24 months after surgery. Subjective Shoulder Value (SSV), Taft (TF), and Acromioclavicular Joint Instability (ACJI) scores were evaluated. Coracoclavicular difference, ossification, AC joint osteoarthritis, and dynamic posterior translation (DPT) were assessed on bilateral anteroposterior stress radiographs and modified Alexander views. The revision rate due to implant conflict and duration of surgery were reported. Group outcome differences were analyzed using standardized hypothesis tests.

RESULTS

28 patients aged 39.2 (LPSB) and 36.4 years (DSB) (P = .319; CI: -2.77-8.34) were eligible per cohort. The follow-up was 30.5 (LPSB) and 37.4 months (DSB) (P = .02; CI: -12.73-1.08). LPSB patients rated a significantly higher SSV (93.2% vs 81.9% [DSB]; P = .004). TF and ACJI scores were similar between the groups. Coracoclavicular difference markedly decreased from 12 mm to 3 mm for both cohorts (P < .001). Ossification was identified in over 85% in both cohorts (P = .160; CI -0.77-0.13) and osteoarthritis in 21.4% (LPSB) and 39.3% (DSB) (P = .150). Persistent DPT was found in around 30% for both cohorts (P = .561; CI -0.26-0.48). The revision rates were 0% (LPSB) and 7% (DSB) (P = .491). LPSB surgery was shorter (59.7 vs 71.5 mins [DSB]) (P = .011).

CONCLUSIONS

The results of the LPSB and DSB techniques with additional percutaneous AC cerclage fixation showed comparable outcomes with excellent clinical and satisfactory radiological results. The assessment of the subjective patient satisfaction was in favor of the LPSB technique and no postoperative revision event was observed following this procedure.

LEVEL OF EVIDENCE

Level III, retrospective comparative therapeutic trial.

Mini-open vs. arthroscopic double tight-rope reconstruction after acute AC-joint dislocation: a comparison in functional outcome and sports activity

INTRODUCTION

In athletes, acromioclavicular joint disruptions account for up to 50% of all shoulder injuries. In high-grade injuries, surgery is favored to ensure a correct restoration of the joint, especially in young athletes. The aim of this study was to compare the clinical, radiological and sport related outcomes of the arthroscopic stabilization with the fixation of the AC joint in a mini-open approach.

MATERIALS AND METHODS

19 patients treated arthroscopically (ASK) and 26 patients with an acute AC-joint dislocation Rockwood V who had undergone the mini-open (MO) surgery were included. Constant Murley Score (CMS), Taft Score (TS) and the Simple Shoulder Tests (SST) were evaluated. The sports activity level was determined according to Valderrabano and the athlete's recovery of their athletic activity level after surgery according to Rhee. Furthermore, all available X-ray images were analyzed.

RESULTS

Patients in the ASK group achieved an average score of 11.7 ± 0.6 points in the SST, 10.3 ± 1.8 points in the TS and 91.2 ± 11.8 points in the CMS. On average, patients in the MO group achieved results of 10.5 ± 1.4 points in the SST, 11.7 ± 0.7 points in the TS and 91.6 ± 9.8 points in the CMS. The ASK group showed significant difference regarding the CC distance in side comparison (Δ = 3.6 mm), whereas no significant difference was found in the MO group (Δ = 0.8 mm). In comparison of both groups, the posterior as well as the combined translation were significantly greater in the ASK group than in the MO group (posterior: ASK: 24.8 mm, MO: 19.3 mm, combined: ASK: 29.1 mm, MO: 20.9 mm). Residual horizontal instability was greater in the ASK group (43%) than in the MO group (32%). Similar results were achieved in sports activity and the recovery of athletic activity (Valderrabano: ASK: 2.8, MO: 2.6; Rhee: ASK: 1.6, MO: 1.5).

CONCLUSIONS

Both techniques prove to be effective for the stabilization of high-grade AC-joint disruptions in athletes and showed excellent clinical results. From a radiographic standpoint, the mini-open procedure appears superior to the arthroscopic technique. After mini-open surgery postoperative loss of correction is less common and greater horizontal stability is achieved. The results also suggest the mini-open technique is superior to the arthroscopic procedure when aiming to restore the athlete's original level of sports activity.

LEVEL OF EVIDENCE: 1

[Minimally Invasive Techniques for the Treatment of Acute and Chronic Acromioclavicular Joint Instabilities]

Acromioclavicular joint instabilities are one of the most common injuries of the shoulder girdle. Diagnostic measures include the vertical and horizontal components of instability. The main goals of treatment include pain reduction, joint stabilization, and return to physical activity. For operative treatment, there are numerous techniques available. Recently, minimally-invasive techniques were developed and showed equal results as with open approach. These procedures facilitate simultaneous treatment of concomitant shoulder lesions and reduce soft tissue trauma as well as the risk of infection. This article presents an overview of such minimally-invasive techniques for both acute and chronic instabilities. Both techniques address the aspect of horizontal instability, which was found to compromise clinical results. For an acute injury, we describe the use of a low-profile button system combined with an additional acromioclavicular cerclage. In the chronic setting with a bidirectional (vertical and horizontal) instability, a free tendon graft combined with a single TightRope augmentation is recommended.

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.

The Reliability of Acromioclavicular Joint Dislocation Classification Systems: A Comparison Between the Rockwood and Kraus Classifications

Background

The Rockwood system for the classification of acute acromioclavicular (AC) joint dislocations has been associated with a lack of reliability. A novel system has been proposed (Kraus classification) that is based on dynamic posterior translation of these injuries.

Purpose

To assess the interobserver and intraobserver reliability of the Rockwood and Kraus classification systems and also to examine the impact of surgeon experience on the assessments.

Study Design

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

Methods

Included were 45 patients with acute AC joint injuries who underwent a radiographic examination using standard bilateral AP and modified Alexander views. For interobserver reliability, 6 shoulder surgeons (expert group) and 6 orthopaedic residents (novice group) reviewed the radiographs to classify injuries according to the Rockwood and Kraus classifications; for each categorization, the participants chose between nonoperative management and surgical treatment. The evaluation was repeated 6 weeks later to determine intraobserver reliability. Kappa (κ) coefficients and their 95% CIs were used to compare interobserver and intraobserver reliability for each classification system according to assessor experience. Statistical differences were considered significant when the upper and lower boundaries of the 95% CI did not overlap.

Results

The overall interobserver agreement for diagnosis (both novice and expert groups) was moderate (κ = 0.52 [95% CI, 0.51-0.54]) for the Rockwood classification and substantial (κ = 0.62 [95% CI, 0.53-0.65]) for the Kraus classification; however, no significant differences were observed between the κ values. The overall interobserver agreement for treatment selection was substantial when using both the Rockwood (κ = 0.78 [95% CI, 0.72-0.81]) and Kraus (κ = 0.77 [95% CI, 0.66-0.87]) classifications. The overall intraobserver agreement for diagnosis was substantial using both the Rockwood (κ = 0.65 [95% CI, 0.61-0.67]) and Kraus (κ = 0.73 [95% CI, 0.69-0.75]) classifications. There were no significant differences between the novice and expert groups on any of the evaluations.

Conclusion

The Kraus system was slightly more reliable than the Rockwood system for classifying AC joint injuries both between assessor groups and overall. The level of surgeon experience had no impact on the evaluations.

The stress and strain pattern in the ligaments of the acromioclavicular joint using a quasi-static model

BACKGROUND

The precise role of the acromioclavicular and coracoclavicular ligaments during shoulder motion is unclear. We evaluate changes in the stress-strain distribution of the acromioclavicular joint's ligaments during different shoulder passive motion positions.

METHODS

A 3D acromioclavicular joint model was reconstructed. A constitutive hyperelastic model was used for the ligaments. The kinematics of the shoulder girdle was taken to simulate shoulder abduction (Motion 1) and horizontal adduction (Motion 2). A computer-generated quasi-static and non-linear finite element model was used to predict the 3D stress-strain distribution pattern of the acromioclavicular ligament and the coracoclavicular ligament complex.

FINDINGS

In motion 1, from 20 to 90° the peak von Mises stress was found in the conoid (4.14 MPa) and the anteroinferior bundle (2.46 MPa), while from 90 to 120° it was found in the conoid and the trapezoid. However, there were no significant differences between the mean stress values between anteroinferior bundle and trapezoid throughout the motion (p = 0.98). In Motion 2, from 20 to 80° the maximum equivalent elastic strain was found in the anteroinferior bundle (0.68 mm/mm) and the conoid (0.57 mm/mm), while from 80 to 100° it was higher in the conoid (0.88 mm/mm) than in the anteroinferior bundle (0.77 mm/mm).

INTERPRETATION

The coracoclavicular ligament complex demonstrated a high stress-strain concentration during simulated passive shoulder abduction. Additionally, it was shown that the acromioclavicular ligament plays an important role in joint restraint during passive horizontal adduction, changing the primary role with the trapezoid and conoid at different motion intervals.

Combination of Surgical Techniques Restores Multidirectional Biomechanical Stability of Acromioclavicular Joint

PURPOSE

To measure the multiaxial stability of the acromioclavicular joint before and after transection of the acromioclavicular capsule and coracoclavicular ligaments and after sequential repair of acromioclavicular and coracoclavicular ligaments.

METHODS

Biomechanical testing was performed on fresh-frozen human cadaveric shoulders (N = 6). Translational and rotational stability in the vertical and horizontal planes was measured in intact specimens, after transecting the acromioclavicular and coracoclavicular ligaments, and after sequentially performing the following procedures: single-bundle coracoclavicular repair (CCR), modified Weaver-Dunn procedure (WD), and acromioclavicular stabilization (ACS).

RESULTS

Resecting the acromioclavicular and coracoclavicular significantly reduced translational stiffness in the inferior and anteroposterior directions, as well as rotational stiffness about the vertical and anteroposterior axes. All 3 surgical procedures increased inferior translational stiffness relative to the intact condition (Intact: 38 ± 9 N/mm, CCR: 54 ± 23 N/mm (P = .03), CCR+WD 52 ± 20 N/mm (P = .07), CCR ± WD+ACS 50 ± 21 N/mm (P = .17)). However, the combination of CCR, modified WD, and ACS resulted in the greatest increase in stiffness in internal rotation (Intact: 12.5 ± 7.4 cNm/deg, CCR: 1.2 ± 1.1 cNm/deg, CCR+WD 7.2 ± 3.0 N∗m/deg [P = .023], CCR+WD+ACS 11.6 ± 4.9 cNm/deg [P = .055]).

CONCLUSIONS

The cumulative stability of CCR, WD reconstruction, and ACS appears to be additive. Our findings provide a biomechanical justification for combining all three techniques. Biomechanical studies assessing the performance of various acromioclavicular repairs and reconstructions should therefore incorporate multiaxial testing in their protocols.

CLINICAL RELEVANCE

Multiple points of fixation that provide multidirectional stability have the potential to improve clinical outcomes and reduce failure rates of acromioclavicular joint repair or stabilization.

Arthroscopically assisted single tunnel reconstruction for acute high-grade acromioclavicular joint dislocation with an additional acromioclavicular joint cerclage

PURPOSE

Purpose of this study was to demonstrate that a single tunnel reconstruction of high-grade acromioclavicular (AC) joint instabilities with implants of the second generation is sufficient for stabilisation, especially in combination with an AC cerclage.

METHODS

Patients with an acute AC-joint dislocation type Rockwood III-B and V were included. Besides clinical follow-up examination, radiographs were analysed. The functional outcome measures were Constant Score (CS), Taft score (TS), ACJI score and patient's satisfaction. Horizontal instability was evaluated by clinical examination and radiological with an Alexander view.

RESULTS

Thirty-five patients with a mean follow-up of 29 months were included. Ninety-seven per cent were satisfied with their result, with an average Subjective Shoulder Value of 90%. The CS averaged at 90 ± 10 points, TS at 11 ± 1 points and ACJI at 78 ± 18 points. Radiologically, 3 of 29 patients (10%) showed a persisting horizontal instability. The coracoclavicular (CC) distance improved from 22 preoperative to 10 mm postoperative, which was comparable to the contralateral side (10 mm, p = 0.103). At follow-up the CC distance increased to 13 mm (p = 0.0001).

CONCLUSION

AC-joint stabilisation with a single tunnel reconstruction using a second-generation implant results in good to excellent clinical results with high patient satisfaction. The additional AC augmentation improves stability in horizontal instable AC-joints and is recommended in all high-grade AC joint stabilisations. Nonetheless, reduction was slightly lost over time due to an elongation or suture failure of the coraco-clavicular fixation.

LEVEL OF EVIDENCE

IV.

Clinical and radiological outcomes of acute Rookwood type IIIB acromioclavicular joint dislocation: Mini-open tightrope technique versus hook plate

OBJECTIVE

Treatment of acute Rookwood type III AC joint dislocation is still controversially discussed. ISAKOS suggested to subdivide type III AC joint injuries into type IIIA (stable) and type IIIB (unstable). The aim of this study was to compare clinical and radiographic outcomes between hook plate fixation and mini-open tightrope for the treatment of acute Rookwood type IIIB acromioclavicular joint dislocation.

METHODS

We conducted a retrospective clinical study of 112 patients with acute Rookwood type IIIB acromioclavicular joint dislocation who were treated surgically using either mini-open TightRope or hook plate from 2013 to 2019. All patients were followed up for 12 months. Clinical outcomes were evaluated using Visual Analogue Scale (VAS) and the Constant-Murley Score (CMS). Radiological results were assessed with the coracoclavicular distance (CCD), the change in clavicular elevation (ΔCE) and horizontal translation.

RESULTS

The length of incision was significantly shorter in the mini-open TightRope group than that in hook plate group (6.62±0.60 vs. 2.58±0.43 p <0.001). Duration of surgery was significantly shorter in the mini-open TightRope group than that in hook plate group (30.12±6.65 vs. 53.33±12.03; p < 0.001). Total blood loss volume was significantly less in the mini-open TightRope group than in the hook plate group. (23.85±7.88 vs. 70.67±24.62, p < 0.001). VAS and CMS in mini-open TightRope group were better than that in hook plate group at 2 weeks after surgery (VAS: 2.19±0.92 vs. 3.30±1.51, p = 0.002 and CMS 69.80±5.61 vs. 57.53±9.24, p<0.001) and 3 month after surgery (VAS: 1.19±0.48 vs. 3.07±1.36, p<0.001 and CMS 89.30±4.47 vs. 83.20±12.11, p = 0.205). There was no statistically significant difference between two groups at 12 months follow-up including VAS, CMS, the CC distance,ΔCE and the degree of dynamic horizontal translation. There were 2 complications in the hook plate group including 1cut out and 1 superficial wound infection.

CONCLUSION

The mini-open tightrope has better function and relieves pain in the early postoperative period compared to hook plate, and at the last follow up two groups have similar clinical and radiological outcomes. Mini-open TightRope fixation is a good option for the treatment of acute Rockwood types ⅢB AC joint dislocation.

Sonographic Measurement of Dynamic Horizontal Instability in Acromioclavicular Joint Instability: Description of a Simple Technique and Correlation to Radiographic Parameters

OBJECTIVE

Dynamic horizontal instability is considered to be the main reason for poor outcome after treatment for acromioclavicular (AC) joint instability. In this study, we describe a simple technique to quantify this pathology via sonography.

METHODS

Thirty-six shoulders from 18 patients with ac joint instabilities were examined using modified Alexander views and a standardized sonographic examination. On the Alexander views, overlap of acromion and clavicle (OLAC), glenoid center to posterior clavicle distance (GCPC), and lateral extension (LE) were measured. Afterwards, the results were analyzed and compared with sonography. Posterior translation of the clavicle and the difference of translation between healthy and injured shoulder were evaluated.

RESULTS

The mean age of the patients was 39 ± 14 years (range 19-61 years). We included 4 (22%) Rockwood type 3, 1 (6%) Rockwood type 4, and 13 (72%) Rockwood type 5 lesions. Four (22%) patients were female and 14 (78%) male patients. Posterior clavicle translation of the injured shoulder correlated strongly between OLAC and sonography (r = -0.514, P = .029), and the difference of translation between healthy and injured shoulder correlated very strongly between LE and sonography (r = 0.737, P < .001).

CONCLUSION

The sonographic measurement technique for horizontal instability presented in this work could help detect horizontal instabilities. While the observation of dynamic horizontal displacement is a strength of this technique, measurements are hindered in cases of high coracoclavicular distances.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Clavicular Tunnel Complications after Coracoclavicular Reconstruction in Acute Acromioclavicular Dislocation: Coracoid Loop versus Coracoid Tunnel Fixation

Background

The purpose of this study was to compare clavicular tunnel complications after coracoclavicular (CC) reconstruction between a coracoid loop fixation group and a coracoid tunnel fixation group. We hypothesized that clavicular tunnel complications would be more common in the coracoid loop group.

Methods

This retrospective study evaluated 24 patients who underwent CC reconstruction using coracoid tunnel fixation (n = 14) and coracoid loop fixation (n = 10). Radiographic measurements included the CC distance and clavicular tunnel diameter. Clavicular tunnel complications such as tunnel widening and clavicular tunnel fractures were investigated. Clinical outcomes were assessed using the American Shoulder and Elbow Surgeons Shoulder score and the University of California at Los Angeles Shoulder score.

Results

The mean follow-up period was 17.5 months (range, 11–38 months). The final clavicular tunnel diameter and the increase in the clavicular tunnel diameter in millimeter and percentage were significantly greater in the coracoid loop group than in the coracoid tunnel group (all p < 0.05). Clavicular tunnel widening more than 100% was found in 5 patients, all belonging to the coracoid loop group. Clavicular tunnel fractures occurred in 3 patients (all in the coracoid loop group). Fracture was associated with severe tunnel widening (more than 100% increase). The mean value of the final clavicular tunnel diameter in patients with fractures was significantly larger than that in patients without (12.7 ± 3.3 mm vs. 8.4 ± 1.5 mm, p = 0.016).

Conclusions

Clavicular tunnel complications such as significant tunnel widening and fractures after CC reconstructions in acromioclavicular dislocations were common with the coracoid loop fixation technique. A greater clavicular tunnel widening and resultantly enlarged tunnel diameter might increase the risk of fracture through the clavicular tunnel.

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.

Better Radiographic Reduction and Lower Complication Rates With Combined Coracoclavicular and Acromioclavicular Ligament Reconstruction Than With Isolated Coracoclavicular Reconstruction

PURPOSE

To determine whether combined acromioclavicular (AC) ligament reconstruction and coracoclavicular (CC) ligament reconstruction without bone tunnels would improve radiographic reduction maintenance and complication rates for type III to V AC dislocations.

METHODS

This single-institution retrospective study analyzed all patients who underwent a hybrid synthetic/graft wrap CC reconstruction without tunnels with additional AC reconstruction/repair from January 2013 to August 2019. This 26-patient cohort was compared with a 1:1 sex- and age-matched control group who underwent CC reconstruction without AC reconstruction. CC distances on postoperative radiographs were compared with normal contralateral shoulders.

RESULTS

Of the 93 patients who underwent AC reconstructive surgery during this time period, 26 patients (96% male) met the inclusion criteria. The AC/CC cohort had 23.5% type III injuries, 23.1% type IV injuries, and 53.8% type V injuries, similar to the control group. Final radiographs of the operative shoulder's CC distance were (mean ± standard deviation) 0.9 ± 4.0 mm greater than that of the contralateral shoulder (9.6 ± 8.7 mm) in the AC/CC cohort. Final radiographs of the operative shoulder's coracoclavicular distance were 4.0 ± 4.7 mm greater than that of the contralateral shoulder (13.3 ± 9.3 mm) in the CC control group, a significant difference (P = .014). The AC/CC reconstruction group had fewer patients with a loss of reduction >5 mm (11.5% versus 38.5%, P = .025). The complication rate in the CC control group was higher than in the AC/CC cohort (30.7% versus 7.7%, P = .035). The reoperation rate was also greater in the CC control group (8 versus 1, P = .010).

CONCLUSION

This cohort study shows that the addition of AC reconstruction to CC reconstruction using synthetic tapes/grafts or allograft tissues without bone tunnels significantly improves durable radiographic outcomes, diminishes complication rates, and improves reoperation rates.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Acromioclavicular joint reconstruction: an additional acromioclavicular cerclage does not improve horizontal stability in double coraco-clavicular tunnel technique

PURPOSE

Horizontal instability-especially in the posterior plane-is a common problem after acromioclavicular joint injuries. The purpose was to compare the stability of a single coraco-clavicular tunnel technique and a double coraco-clavicular tunnel technique for coraco-clavicular ligament reconstruction and to examine the influence of an additional acromioclavicular cerclage on the horizontal stability in the acromioclavicular joint.

METHODS

21 acromioclavicular joints of human cadaveric shoulders were randomly assigned to the following groups: single coraco-clavicular tunnel technique with horizontal augmented acromioclavicular cerclage (SCT + AC); double coraco-clavicular tunnel technique (DCT); double coraco-clavicular tunnel technique and acromioclavicular cerclage (DCT + AC). The specimens underwent cyclic horizontal testing and were recorded using a 3D optical measuring system.

RESULTS

The displacement and the increase in displacement in relation to the displacement after precondition for SCT + AC were significantly higher after every measured amount of cycles than for DCT (p₁₀ = 0.0023; p₅₀₀₀ = 0.0012) and DCT + AC (p₁₀ = 0.0006; p₅₀₀₀ = 0.0012). There was no significant difference in the total displacement, or in the increase in total displacement between double coraco-clavicular tunnel reconstructed groups with and without additional acromioclavicular cerclage.

CONCLUSION

Double coraco-clavicular tunnel technique with and without additional acromioclavicular cerclage results in a significant higher stability regarding the horizontal plane in comparison to single coraco-clavicular tunnel technique with acromioclavicular cerclage. Based on the results of this biomechanical in vitro study, the use of an additional acromioclavicular cerclage with single coraco-clavicular tunnel technique may not be indicated in most cases. The effect of an additional acromioclavicular cerclage seems to be negligible, at least in presence of a double-coraco-clavicular tunnel technique reconstruction. Techniques of AC joint reconstruction should focus on the use of double coraco-clavicular tunnel devices.

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.