Acromioclavicular Joint Stabilization Research Articles

Using Dynamic Stereo X-ray Imaging for In Vivo Acromioclavicular Joint Kinematics Assessment: A Preliminary Investigation.

Acromioclavicular joint (ACJ) disruption occurs frequently in athletes engaged in contact sports. However, the current understanding of ACJ biomechanics during muscle-driven functional activities and the influence of different treatment approaches (eg, reconstruction surgery vs nonoperative methods) on ACJ kinematics and stability remains limited. The absence of precise in vivo biomechanical measurement modalities for scapular and clavicular kinematics contributes significantly to this lack of understanding. The purposes of this study were to determine whether dynamic stereo x-ray (DSX) imaging can be used to evaluate the in vivo kinematics of the ACJ and to provide preliminary comparative data on ACJ kinematics, range of motion, and isometric strength of surgically reconstructed or nonoperatively treated ACJ shoulders and their uninjured contralateral shoulders. It was hypothesized that ACJ kinematics could be measured successfully using DSX and that surgically and nonoperatively treated shoulders would show abnormal 3-dimensional (3-D) ACJ kinematics compared with the uninjured contralateral. Controlled laboratory study. In this cross-sectional study, 11 participants who had undergone unilateral ACJ reconstruction surgery and 3 patients who received nonoperative treatment were enrolled. ACJ kinematics were assessed during active forward flexion, scaption, and abduction through high-speed DSX imaging, complemented by 3-D bone models obtained via computed tomography (CT) scans. To gauge kinematic differences, a 1-dimensional statistical parametric mapping method was employed, which compared outcomes in the index limb to those in the uninjured counterpart. In addition, the range of motion and isometric strength at various abduction angles were analyzed, employing a repeated-measures analysis of variance to compare the affected and uninjured sides. Leveraging a combination of DSX imaging and patient-specific CT bone models, ACJ kinematics was measured successfully during movements along anatomic planes. Preliminary findings from this investigation revealed no detectable differences between the surgically reconstructed and uninjured sides in ACJ biomechanics, shoulder range of motion, and isometric strength outcomes. However, on average, the nonoperatively treated shoulders demonstrated increased internal rotation, upward rotation, and posterior tilting of the scapula relative to the clavicle (no statistical analyses were performed due to the small sample size). DSX imaging is a promising tool for evaluating potential in vivo kinematic abnormalities in the ACJ during muscle-driven activities, laying the groundwork for further investigations in both ACJ-reconstructed and nonreconstructed patients. This study furnished essential data for conducting power analyses and designing future studies with an adequate sample size to investigate the impact of different treatment approaches on shoulder girdle mechanics. With its potential for accurately characterizing shoulder girdle kinematics post-ACJ injury, DSX imaging can offer valuable insights for future clinical studies, facilitating informed decisions regarding the short- and long-term impacts of treatment choices on shoulder health and function.

Use of the pectoralis minor and coracoacromial ligament for a biplanar coracoclavicular and acromioclavicular reconstruction: A cadaveric feasibility study.

The aim of this study was to evaluate the feasibility of a novel technique that focuses on vertical and horizontal stabilization of the acromioclavicular joint using two local autologous grafts, the pectoralis minor (Pm) and the coracoacromial ligament (CAL). Ten fresh-frozen shoulder cadaveric pieces were dissected. Length and width of the Pm and CAL were measured in their anatomical position and anatomical variants were noted. The Pm tendon was harvested at the myothendinous junction keeping the insertion at the coracoid process. The CAL was detached from the coracoid process keeping the acromial insertion. The free limbs of both grafts were prepared with the Krackow technique and the Arthrex SpeedWhip technique, respectively. The primary coracoclavicular reduction and fixation were with the button system or with two subcoracoid ultrahigh-strength suture cerclage through and around the clavicle. The Pm graft was fixed inside a clavicular tunnel by a cortical button and the CAL was transferred and fixed to the lateral clavicle using a knotless anchor or intramedullary when lateral clavicle resection was performed. The median length of the Pm was 50 mm (interquartile range [IQR]: 50-54), and the median length of the CAL was 36.5 mm (IQR 34-40) which decreased by 15% and 23% once were prepared with the Krackow and Arthrex SpeedWhip techniques to 44.5 mm (IQR: 30-65) and 30 mm (IQR: 22-32), respectively. The diameter of the prepared Pm graft was 5 mm (IQR: 4.5-6) and the CAL graft 5.5 mm (5-6). All grafts were able to reach the fixation points. The procedure was feasible in 100% of the cases. A biplanar reconstruction using autologous Pm and CAL appears feasible in restoring the acromioclavicular joint stability. Level IV. Basic science, anatomy, cadaveric dissection.

The deltotrapezial fascia stabilizes the AC-Joint and its reconstruction restores the horizontal stability in AC-joint separations—a biomechanical comparison

BackgroundVarious techniques are available for the reconstruction of acromioclavicular joint (ACJ) dislocations, with the main focus being on restoration of the AC capsule or coracoclavicular (CC) ligaments. Recent research has underlined the significance of the deltotrapezial fascia (DTF) and related muscles as dynamic stabilizers of the ACJ. HypothesisReconstruction of the DTF increases the stability of the ACJ in the horizontal plane more than a complete transection of the fascia, while not restoring the stability of the native state. MethodsFive pairs of human cadaveric shoulders including the torsos were included in the study and underwent cyclic anterior-posterior loading using an electromechanical testing machine. The shoulders were put into three groups: group N (n = 10): native ACJ; group T (n = 10): ACJ with transected DTF; group R (n = 10): ACJ with reconstruction of the DTF after transection. The dislocation was recorded with an 3D optical measuring system. ResultsGroup N showed a mean horizontal displacement of 2.94 mm (± 1.26), group T showed a mean anterior displacement of 3.33 mm (± 1.37) and group R showed a mean anterior displacement of 2.95 mm (± 1.08). The mean anterior displacement for group T was significantly higher after every measured number of cycles compared with groups N and R. There was no significant difference in mean anterior displacement between groups N and R. ConclusionThe transection of the DTF results in significantly reduced stability in the horizontal plane of the ACJ. A reconstruction of the DTF restores the stability of the native ACJ in the horizontal plane. Further clinical and biomechanical investigations should focus on reconstruction techniques of the DTF.

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

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. 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. 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). 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 III, retrospective comparative study.

An In Vitro Study Demonstrating the Significance of Acromioclavicular Ligament Repair in Restoring Horizontal and Rotational Acromioclavicular Joint Stability.

The principle of joint reconstruction surgery is to try to recreate the native joint biomechanics and stability. With respect to acromioclavicular joint (ACJ) surgery, much focus to date has been on restoring the superoinferior stability. There is concern that persistent horizontal instability following ACJ reconstruction could lead to poorer patient outcomes; therefore, we evaluated whether acromioclavicular (AC) ligament repair offers improved horizontal stability in conjunction with ACJ reconstruction. A whole-body human cadaver was used. The ACJ was exposed and subjected to a constant 70N load on the lateral end of the clavicle to test the anteroposterior (AP), superoinferior (SI), and horizontal pivot angle (HPA) around the ACJ. The AC and coracoclavicular (CC) ligaments were subsequently divided, and the above three parameters were re-tested. Ligament augmentation and reconstruction system (Corin Group, Cirencester, UK), LockDown (LockDown Medical Limited, Redditch, UK), Endobutton (Smith and Nephew Inc.,London, UK), and Neoligament implant (Xiros Ltd., Leeds, UK) were used to reconstruct the CC ligaments and tested with and without AC repair. The native ACJ allowed an average 2.48 mm AP and 3.88 mm SI translation with a 27° HPA. All synthetic implants significantly improved the vertical stability of the ACJ but allowed up to a four-fold increase in AP translation. Coupled with ACJ repair, all the reconstructions were far superior, especially in restoring horizontal stability. The implants varied in their approach to fixation and concentrated primarily on the reconstruction of CC ligaments. Our study was able to demonstrate that AC repair significantly improves the stability of the construct and significantly reduces vertical and horizontal instability.

Coracoclavicular and acromioclavicular ligament reconstruction with a double-bundle semitendinosus autograft and cortical buttons for chronic acromioclavicular joint dislocations: clinical and imaging outcomes

BackgroundThere are few clinical and radiographic studies of coracoclavicular (CC) ligament reconstruction in chronic acromioclavicular (AC) joint dislocation. Additionally, reported AC joint reduction rates vary. HypothesisArthroscopically assisted double-bundle semitendinosus tendon autografts with CC and AC ligament reconstruction for AC joint reconstruction provide AC joint stability and improved function at the final visit. MethodsIn this retrospective study of prospectively collected data, 21 patients surgically treated for chronic AC joint dislocation (Rockwood III–V) were assessed clinically and radiographically preoperatively, and at day 1, 3 months, 12 months, and at a final visit (> 24 months) postoperatively. Clinical assessments included Constant and ASES scores. The CC vertical distance (CCD) on the affected and unaffected sides [CCD ratio (%)] on the anterosuperior view were measured. AC joint vertical reduction loss was defined as an increase in the CCD ratio of > 25%. Horizontal AC joint instability was evaluated on axillary views. Pearsons’ correlation coefficients were generated to examine the relationships among postoperative clinical scores, CCD ratio, interval from injury to surgery, and age at the time of surgery. ResultsTwenty-one shoulders in 21 patients (mean age, 40.0 years at the time of surgery; 16 men, 5 women) were evaluated with a mean 31.7-month follow-up period. The mean Constant scores, ASES scores, and CCD ratios significantly improved from preoperatively to the final visit [57.4 ± 10.1, 49.1 ± 12.1, 101.6 ± 64.1 preoperatively; 89.6 ± 5.3, 96.5 ± 4.2, 9.9 ± 34.5 at the final visit, respectively (P < 0.001 for all)]. Vertical AC and horizontal AC joint instability were observed in four shoulders (19.0%) and in one shoulder (4.8%), respectively. However, there was no significant correlation between the increase in CCD and clinical scores at the final visit (Constant score; r = 0.179, P = .438: ASES score; r = -0.260, P = .256) or the interval from injury to surgery (r = 0.099, P = .669) or age at the time of surgery (r = 0.019, P = .935). No clinical complications were associated with clinical symptoms. ConclusionsPatients who underwent the index procedure achieved significant improvement in shoulder function without complications related clinical symptom after a mean follow-up interval of 31.7 months. In contrast, the rates of total ACJ instability in the vertical and horizontal planes were unsatisfactory but compatible with those in previous studies.

Anatomic acromioclavicular and Coracoclavicular ligament reconstruction with allograft is effective for the management of non-acute acromioclavicular dislocations

Objectiveto analyze the short-term outcomes of an anatomical technique that reconstructs both the acromioclavicular and coracoclavicular ligaments with the help of a tendon allograft for the management of non-acute acromioclavicular dislocations. Methodsthis is a prospective longitudinal study of a case series of subjects with symptomatic non-acute (>3 weeks) acromioclavicular dislocations surgically managed with an anatomical reconstruction of both the acromioclavicular and coracoclavicular ligaments using tibial tendon allografts. Outcomes were assessed with simple standardized radiographs and with the Constant-Murley, American Shoulder and Elbow Surgeons (ASES)-shoulder and Quick-DASH (Disabilities of the Arm, Shoulder and Hand) scales; also, the acromioclavicular joint stability and the scapulothoracic kinematics were assessed. Resultsa total of 19 subjects were assessed. There were no intraoperative or early postoperative complications. After a minimum two year follow-up (mean 3.12 years, [standard deviation 1.10 years]), there were significant improvements in all three of the scales: The Constant-Murley score increased from 65.4 (13.0) preoperatively to 92.6 (11.2) at the end of follow-up (p<0.001); the Quick-DASH score improved from 21.3 (6.73) to 13.0(4.58) (p<0.001); and the ASES-shoulder score increased from 56.6 (14.6) to 91.0 (9.86) (p<0.001). The AC joint was stable in both the vertical and the horizontal plane, without residual scapulothoracic dysfunction in 18/19 subjects at the end of follow-up. Only one patient presented a poor functional outcome, with loss of reduction, instability and persistent symptoms. Another subject suffered loss of reduction, though without functional repercussions. Two subjects had asymptomatic distal clavicle osteolysis and two developed radiographic osteoarthritis and were also asymptomatic. Moderate widening of the tunnels was observed in most patients: tunnel size after surgery was 5.1 (0.3) mm versus 5.8 (1.1) mm at the end of follow-up (p = 0.001) but widening was not correlated to final function. Conclusionsthe anatomical reconstruction of the acromioclavicular and coracoclavicular ligament complexes with a tendon allograft yields excellent clinical outcomes when used in subjects with symptomatic non-acute acromioclavicular dislocations. Secondary tunnel widening, distal clavicle osteolysis and osteoarthritis might be of concern but do not affect clinical outcomes.

3D C-arm navigated acromioclavicular joint stabilization

IntroductionSurgical treatment options for acromioclavicular joint separations are varied. Frequently, suspension devices (SD) are inserted for stabilization under arthroscopic view. This study investigates the feasibility and accuracy of three-dimensional (3D) digital-volume-tomography (DVT) C-arm navigated implantation with regard to the general trend toward increasingly minimally invasive procedures.Materials and methodsThe implantation of a TightRope® suture button system (SD) via a navigated vertical drill channel through the clavicle and coracoid was investigated in 10 synthetic shoulder models with a mobile isocentric C-arm image intensifier setup in the usual parasagittal position. Thereby, in addition the placement of an additive horizontal suture cerclage via a navigated drill channel through the acromion was assessed.ResultsAll vertical drill channels in the Coracoclavicular (CC) direction could be placed in a line centrally through the clavicle and the coracoid base. The horizontal drill channels in the Acromioclavicular (AC) direction ran strictly in the acromion, without affecting the AC joint or lateral clavicle. All SD could be well inserted and anchored. After tensioning and knotting of the system, the application of the horizontal AC cerclage was easily possible. The image quality was good and all relevant structures could be assessed well.ConclusionIntraoperative 3D DVT imaging of the shoulder joint using a mobile isocentric C-arm in the usual parasagittal position to the patient is possible. Likewise, DVT navigated SD implantation at the AC joint in CC and AC direction on a synthetic shoulder model. By combining both methods, the application in vivo could be possible. Further clinical studies on feasibility and comparison with established methods should be performed.

Acromioclavicular joint Stabilization: Our experience with the lockdown technique

BackgroundAcromioclavicular joint (AC joint) disruption is a common injury with considerable variation with regards to surgical management. The Lockdown™ procedure (previously known as Surgilig™), Modified Weaver-Dunn procedure, Arthroscopic AC joint stabilization and Ligament Augmentation and Reconstruction system (LARS) procedure have all been described for treatment of this injury with varying outcomes. PurposeTo measure the functional and radiological outcomes following all cases of AC joint reconstruction using the Lockdown™ technique over the last 10 years at Medway Maritime Hospital. MethodsData on a total of 53 patients who underwent AC joint reconstruction between 2012 and 2021 were collected. Electronic records were used to extract data regarding patient characteristics, surgery details, and duration of follow-up. Telephonic interviews of patients were conducted to collect data on hand dominance, surgical complications, and responses to Oxford shoulder score (OSS) and QuickDASH score questionnaires. Hospital PACS data were reviewed to record preoperative injury severity and postoperative acromioclavicular joint reduction. ResultsResults for 42 patients were available and analysed as 10 could not be contacted and 1 patient sadly passed away. Of the patients reviewed, 92.9% were males with a mean age of 42.2 years (Range 16–67 years) and mean follow up of 68 months (12–119.1 months). The injury involved the dominant arm in 59.5%cases. Majority of the cases were Rockwood type V injuries (71.43%) while the rest were either type III(19.05%) or type IV(9.52%).The mean preoperative OSS was 21.3/48 which improved to 44.3/48 in the postoperative period. Similarly, the mean QuickDASH score was 50.6 preoperatively, that improved to 9.1 postoperatively.The most common patient reported complication was prominent metalwork seen in 5 cases (11.6%) followed by stiffness seen in 3 cases (7%) and superficial infection seen in 1 case (2.3%). The AC joint remained reduced radiologically in 81% of cases, while a resubluxation between 50 and 100% was seen in the rest of the cases. Patients with radiological resubluxation did not report this as a complication in 87.5% of the cases. Overall, 38 patients reported their outcome as excellent, 2 patients rated it good while 1 patient reported it as fair and 1 as poor. ConclusionThe Lockdown™ technique for stabilization of AC joint has excellent or good patient satisfaction in 95.2% of cases in long term follow up of more than 5.7 years. Prominent metalwork and stiffness are the commonest clinical complications. Radiological resubluxation can be seen in a fifth of the cases but does not directly lead to patient dissatisfaction. Level of evidenceLevel IV Retrospective case series.

Prospective Multicenter Randomized Controlled Trial of Surgical Versus Nonsurgical Treatment for Acute Rockwood Type 3 Acromioclavicular Injury.

Evidence for the superiority of surgical versus nonsurgical treatment of Rockwood type 3 acromioclavicular joint (ACJ) dislocation is still lacking. It was hypothesized that surgical treatment will outperform nonsurgical treatment. Randomized controlled trial; Level of evidence, 1. A prospective randomized trial involving 4 study centers was performed from January 1, 2011, to March 31, 2016. A total of 85 patients with acute Rockwood type 3 ACJ dislocations were allocated randomly to receive either nonsurgical or surgical treatment. A total of 70 patients were treated as allocated, and 8 patients made an early crossover from nonsurgical to surgical treatment, leaving 47 patients treated surgically and 31 patients nonsurgically. All patients were followed up longitudinally, including clinical evaluation using the Constant score and standardized radiographic evaluation, with final follow-up after 2 years. At no follow-up time point was there a significant difference in Constant score between the surgically and nonsurgically treated patients. Radiographic analysis showed not only an inferior coracoclavicular distance at all follow-up points for surgical treatment but also a higher incidence of posttraumatic osteoarthritis and heterotopic ossifications, without any negative clinical correlation. With regard to complications, 1 patient (3%) in the nonsurgical group underwent secondary surgical ACJ stabilization. The revision rate after surgical treatment was 17% (P < .001). Neither primary horizontal instability nor younger age were associated with inferior clinical outcomes after nonsurgical treatment. Surgical treatment of ACJ Rockwood type 3 injuries did not lead to superior functional outcomes. Neither younger age nor horizontal instability were associated with inferior outcomes after nonsurgical treatment. Surgical treatment led to a slower recovery and to higher complication and revision rates. ISRCTN registry (study ID: ISRCTN92265154).

Paper 55: Kinematic Abnormalities in the Shoulder Girdle after Conservative or Surgical Treatment of the High-grade Acromioclavicular Joint Disruption

Objectives: Acromioclavicular joint (ACJ) injury is one of the most prevalent shoulder girdle injuries among young contact athletes, disrupting shoulder mechanics, which can adversely affect long-term joint health. However, there is considerable controversy regarding treatment selection and its role in the health of the shoulder complex over time. While there is some consensus that surgical treatment is needed when both AC and CC (coracoclavicular) ligaments are disrupted (Rockwood grades III-V), in practice distinguishing between high-grade injuries is challenging, and grading is not highly consistent among surgeons. Clinical studies comparing surgical and conservative treatment have reported comparable patient outcomes. However, they often have included outdated surgical approaches with known high complication rates (e.g., k-wire, hook-plate), undermining their current validity. Overall, data on the efficacy of conservative vs. surgical treatment for restoring ACJ stability and the impact of ACJ instability on shoulder girdle biomechanics is lacking, impairing optimal decision-making for ACJ injury treatment. This cross-sectional biomotion study aims to characterize the extent of biomechanical abnormalities of the shoulder girdle after surgical or conservative treatments in individuals treated for high-grade ACJ injury. Hypothesis: The kinematics of the shoulder girdle will remain abnormal regardless of the treatment type, but the abnormality will be more pronounced in the conservatively treated group. Methods: Subjects: Individuals with a unilateral ACJ injury (Rockwood Grade ³ III; 2-5 years post- treatment) consented and participated in this IRB-approved cross-sectional study. Thus far, in this ongoing study, six subjects (one female, Height: 175 (12) cm, Weight: 81 (18) kg), BMI 26.1(3.1) kg/m2) who were treated surgically using suspensory fixation, and three subjects (179 (10.4) cm, 99.4 (13.6) kg, 30.9 (2.4) kg/m2) who were treated non-operatively were consented and tested. Measurements: A high-resolution 3D shoulder CT scan was acquired bilaterally for each subject. The patient-specific 3D bone models of the humerus and clavicle were created. The 3D in-vivo shoulder kinematics was measured bilaterally (with the contralateral shoulder serving as an internal control) using a Dynamic Stereo X-ray (DSX) system during three repetitions of the scapular plane arm elevation while subjects followed a metronome beat for consistent moving rhythm. Post-processing: The 3D poses of the scapula and clavicle were estimated according to validated methods in DSX-Suite (C-Motion, USA) by simultaneous aligning the bone-model contours acquired through CT to DSX images in both views in each frame. In addition, an anatomical coordinate system was determined for each bone, and joint rotations/translations were calculated according to the methods described elsewhere, which considers the abilities of DSX and CT-based bone models while adhering to ISB standards when relevant. Outcomes: The horizontal and vertical ACJ displacements were calculated in Visual 3D (C- Motion, USA). Also, ACJ separation was defined as an instantaneous Euclidean distance between acromion and clavicle centers, characterizing the ACJ subluxation during movements. The rotational stability of the ACJ was measured by calculating the instantaneous axial rotation of the scapula relative to the clavicle using the helical axis method. These outcomes can substantiate how the mechanical constraint of the shoulder girdle is maintained in surgically and conservatively ACJ-treated individuals during in-vivo muscle-driven activities. Results: Figure (A)-(E) demonstrates the ACJ kinematic results normalized to the movement percent (mean±SE). No difference was noted in the axial rotation of the scapula relative to the clavicle between the study groups (Fig . B). The nonoperative group demonstrated a larger magnitude and range of ACJseparation (Fig. C), while the surgical cohort demonstrated smaller but comparable ranges and variations to controls. Fig. D shows that both treatment groups show increased posterior claviculartranslations, with the conservative group showing poorer ACJ instability in the posterior direction. Also, an increase in superior clavicle translation (Fig. E) was detected in both groups but more significantly in the conservative group, indicating an inferior reduction of the CC ligaments. Conclusions: To our knowledge, this is the first DSX study reporting the ACJ instabilities 2-5 years post ACJ reconstruction surgery during in-vivo muscle-driven activity. Our preliminary results indicated that the operated side demonstrates increased horizontal and vertical instabilities compared to the uninjured contralateral. Also, ACJ separation remains abnormal, suggesting that the surgery may not fully restore the normative ACJ kinematics mid-to-long term. Furthermore, the ACJ kinematics of the few conservative participants in this study demonstrate extensive ACJ instabilities, potentially implying inferior kinematic outcomes in the conservative group compared to the surgical group. Especially the increased posterior clavicular instability in the conservative group is concerning since it was related to inferior long-term outcomes. While no definitive conclusion can be drawn at this stage due to the sub- optimal sample size , the current findings demonstrate the feasibility of addressing the study aim using the current method, supporting the study hypothesis and providing ample motivation to continue this line of research.

Finite element analysis of different reconstruction methods of coracoclavicular ligament for acromioclavicular joint dislocation

This study aims to examine the biomechanical effects of different reconstruction methods, including single-bundle, double-bundle anatomical reconstruction, and double-bundle truly anatomical reconstruction of the coracoclavicular ligament on the acromioclavicular joint using finite element analysis, to provide a theoretical basis for the clinical application of truly anatomical coracoclavicular ligament reconstruction. One volunteer, aged 27 years old, with a height of 178 cm and a weight of 75 kg, was selected for CT scanning of the shoulder joint. Three-dimensional finite element models of single-bundle reconstruction, double-bundle anatomical reconstruction, and double-bundle truly anatomical reconstruction of coracoclavicular ligament were established by using Mimics17.0, Geomagic studio 2012, UG NX 10.0, HyperMesh 14.0 and ABAQUS 6.14 software. The maximum displacement of the middle point of the distal clavicle in the main loading direction and the maximum equivalent stress of the reconstruction device under different loading conditions were recorded and compared. The maximum forward displacement and the maximum backward displacement of the middle point of the distal clavicle in the double-bundle truly anatomic reconstruction were the lowest, which were 7.76 mm and 7.27 mm respectively. When an upward load was applied, the maximum displacement of the distal clavicle midpoint in the double-beam anatomic reconstruction was the lowest, which was 5.12 mm. Applying three different loads forward, backward, and upward, the maximum equivalent stress of the reconstruction devices in the double-beam reconstruction was lower than that in the single-beam reconstruction. The maximum equivalent stress of the trapezoid ligament reconstruction device in the double-bundle truly anatomical reconstruction was lower than that in the double-bundle anatomical reconstruction, which was 73.29 MPa, but the maximum equivalent stress of the conoid ligament reconstruction device was higher than that of the double-bundle anatomical reconstruction. The truly anatomical reconstruction of coracoclavicular ligament can improve the horizontal stability of acromioclavicular joint and reduce the stress of the trapezoid ligament reconstruction device. It can be a good method for the treatment of acromioclavicular joint dislocation.

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

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. 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. 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. 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.

Deltotrapezial Stabilization of Acromioclavicular Joint Rotational Stability: A Biomechanical Evaluation.

Despite advances in surgical management of acromioclavicular (AC) joint reconstruction, many patients fail to maintain sustained anatomic reduction postoperatively. To determine the biomechanical support of the deltoid and trapezius on AC joint stability, focusing on the rotational stability provided by the muscles to posterior and anterior clavicular rotation. A novel technique was attempted to repair the deltoid and trapezius anatomically. Controlled laboratory study. Twelve human cadaveric shoulders (mean ± SD age, 60.25 ± 10.25 years) underwent servohydraulic testing. Shoulders were randomly assigned to undergo serial defects to either the deltoid or trapezius surrounding the AC joint capsule, followed by a combined deltotrapezial muscle defect. Deltotrapezial defects were repaired with an all-suture anchor using an anatomic technique. The torque (N·m) required to rotate the clavicle 20° anterior and 20° posterior was recorded for the following conditions: intact (native), deltoid defect, trapezius defect, combined deltotrapezial defect, and repair. When compared with the native condition, the deltoid defect decreased the torque required to rotate the clavicle 20° posteriorly by 7.1% (P = .206) and 20° anteriorly by 6.1% (P = .002); the trapezial defect decreased the amount of rotational torque posteriorly by 5.3% (P = .079) and anteriorly by 4.9% (P = .032); and the combined deltotrapezial defect decreased the amount of rotational torque posteriorly by 9.9% (P = .002) and anteriorly by 9.4% (P < .001). Anatomic deltotrapezial repair increased posterior rotational torque by 5.3% posteriorly as compared with the combined deltotrapezial defect (P = .001) but failed to increase anterior rotational torque (P > .999). The rotational torque of the repair was significantly lower than the native joint in the posterior (P = .017) and anterior (P < .001) directions. This study demonstrated that the deltoid and trapezius play a role in clavicular rotational stabilization. The proposed anatomic repair improved posterior rotational stability but did not improve anterior rotational stability as compared with the combined deltotrapezial defect; however, neither was restored to native stability. Traumatic or iatrogenic damage to the deltotrapezial fascia and the inability to restore anatomic deltotrapezial attachments to the acromioclavicular joint may contribute to rotational instability. Limiting damage and improving the repair of these muscles should be a consideration during AC reconstruction.

Anatomical acromioclavicular joint stabilization with chemically sterilized tendon allografts: A retrospective study.

The purpose of this retrospective study was to analyze whether chemically sterilized tendon allografts perform as well as other non-sterilized allografts and autografts as described in the literature for anatomical acromioclavicular joint stabilization for the treatment of Rockwood III-V. Allografts are still described as a factor for higher re-rupture rates. Retrospective data were collected from 21 acromioclavicular joint stabilizations performed by a single surgeon and performed between 2011 and 2014 using sterilized semitendinosus allografts. The primary endpoints were re-rupture and complication rates. Secondary endpoints were AC-joint stability, pain level, return to work and sport and the range of motion. No re-ruptures occurred during the mean follow-up time of 33 months. Zero complications occurred directly after surgery, but three complications later than three weeks after surgery. All cases resolved without further surgery. After surgery, stability significantly improved for all patients. Post-surgery, 19 patients had stable acromioclavicular joints and only two patients showed minor instabilities. Range of motion returned to the range of the healthy shoulders for all patients. Chemically sterilized semitendinosus allograft use for anatomic AC-joint stabilization is equivalent to the use of other allografts or autografts and required no hardware removal. No donor age or graft size dependence was observed, due to zero re-ruptures.

The Role of the Trapezius in Stabilization of the Acromioclavicular Joint: A Biomechanical Evaluation.

Background:Acromioclavicular joint (ACJ) injuries are common, and many are adequately treated nonoperatively. Biomechanical studies have mainly focused on static ligamentous stabilizers. Few studies have quantified ACJ stabilization provided by the trapezius.Purpose/Hypothesis:To elucidate the stabilization provided by the trapezius to the ACJ during scapular internal and external rotation (protraction and retraction). It was hypothesized that sequential trapezial resection would result in increasing ACJ instability.Study Design:Controlled laboratory study.Methods:A biomechanical approach was pursued, with 10 cadaveric shoulders with the trapezius anatomically force loaded to normal. The trapezius was then serially transected over 8 trials, which alternated between clavicular defects (CD) and scapular defects (SD); each sequential defect consisted of 25% of the clavicular or scapular trapezial attachment. After each defect, specimens were tested with angle-controlled scapular internal and external rotation (12°) with rotary torque measurements to evaluate ACJ stability.Results:The mean resistance in rotary torque for 12° of scapular internal rotation (protraction) with native specimens was 7.0 ± 2.0 N·m. Overall, internal rotation demonstrated a significant decrease in ACJ stability with trapezial injury (P < .001). Eight sequential defects resulted in the following significant percentage decreases in rotary torque from native internal rotation: 1.5% (25% CD; 0% SD), 5.6% (25% CD; 25% SD), 5.1% (50% CD; 25% SD), 6.5% (50% CD; 50% SD), 3.8% (75% CD; 50% SD), 7.1% (75% CD; 75% SD), 6.7% (100% CD; 75% SD), and 12.3% (100% CD 100% SD) (P < .001). The mean resistance in rotary torque for 12° of scapular external rotation (retraction) with native specimens was 7.1 ± 1.7 N·m. External rotation did not demonstrate a significant decrease in ACJ stability with trapezial injury (P = .596). The 8 sequential defects resulted in decreases in rotary torque from native external rotation of 0%, 3.8%, 4.0%, 3.2%, 3.5%, 3.4%, 4.2%, and 0.7%.Conclusion:Trapezial injury resulted in increased instability in the setting of scapular internal rotation (protraction) of the ACJ.Clinical Relevance:These findings validate the inclusion of deltotrapezial fascial injury consideration in the modified Rockwood classification system. Repair of the trapezial insertion on the ACJ may provide improved outcomes in the setting of ACJ reconstruction.

Combined Vertical, Horizontal, and Rotational Acromioclavicular Joint Stabilization: “Closing the Circle” Technique

The biomechanical and anatomical complexity of the acromioclavicular joint makes its repair techniques particularly challenging. High rates of reduction subsidence and construction failures transversally affect both anatomic and nonanatomic repair techniques. The importance of addressing both vertical and horizontal instability has been highlighted in recent years. The authors aim to describe a surgical technique that combines vertical, horizontal, and rotational stabilization, in an attempt to restore the coracoacromioclavicular circle of stability.

Horizontal instability after acromioclavicular joint reduction using the two-hole technique is preferred over the loop technique: a single-blind randomized clinical trial.

BackgroundMost acromioclavicular joint (ACJ) injuries are caused by direct trauma to the shoulders, and various methods and techniques are used to treat them; however, none of the options can be considered the gold standard. This study examines the horizontal stability of the ACJ after a complete dislocation was repaired using one of two Ethibond suture techniques, the loop technique and the two holes in the clavicle technique.MethodsIn this single-blind, randomized clinical trial, 104 patients diagnosed with complete ACJ dislocation type V were treated using Ethibond sutures with either the loop technique or the two holes in the clavicle technique. Horizontal changes in the ACJ were radiographically assessed in the lateral axial view, and shoulder function was evaluated by the Constant (CS) and Taft (TS) scores at intervals of 3, 6, and 12 months after surgery. ResultsThe horizontal stability of the ACJ was better with the two-hole technique than the loop technique at all measurement times. CS and TS changes showed a significant upward trend over time with both techniques. The mean CS and TS at the final visit were 95.2 and 11.6 with the loop technique and 94.0 and 11.9 with the two-hole technique, respectively. The incidence of superficial infections caused by the subcutaneous pins was the same in the two groups.ConclusionsDue to the improved ACJ stability with the two-hole technique, it appears to be a more suitable option than the loop technique for AC joint reduction.

Kinematic and Radiographic Evaluation of Acromioclavicular Reconstruction with a Synthetic Ligament.

Purpose The optimal surgical technique for unstable acromioclavicular (AC) and coracoclavicular (CC) joint injuries has not yet been established. The biomechanical and radiographic effect of the LockDown device, a synthetic ligament for AC joint reconstruction, was evaluated to assess the optimal surgical technique for unstable AC and CC joint injuries. It was hypothesized that the LockDown device would restore AC joint kinematics and radiographic stability to near native values. Methods Three fresh frozen cadaveric torsos (6 shoulders) modelled CC joint motion in their “native,” “severed,” and “reconstructed” states. The effects of stressed and unstressed native, severed, and reconstructed conditions on AC separation and CC distances in anteroposterior, mediolateral, and inferosuperior directions during shoulder abduction, flexion, and scaption were assessed. The analysis of variance (p, 0.05) was used to compare CC distance and peak AC distance in anteroposterior, mediolateral, and inferosuperior directions during shoulder flexion, abduction, and scaption measurements among native, severed, and reconstructed states with unstressed and stressed Zanca radiographic views. Results From radiographic analyses, the CC distance was significantly greater (p=0.001) across the surgical state in stressed versus unstressed views. Mean difference between stressed and unstressed views was 1.8 mm in native state, 4.1 mm in severed state, and 0.9 mm in reconstructed state. The CC distance was significantly greater in the “severed” state (10.4 mm unstressed; 14.5 mm stressed) compared to the “native” state (p=0.016) (6.5 mm unstressed; 8.3 mm stressed) and compared to the “reconstructed” state (p=0.005) (3.1 mm unstressed; 4.0 mm stressed) and significantly less (p=0.008) in the “reconstructed” state compared to the “native” state. CC distances decreased from native to reconstructed, an average of 3.3 mm for unstressed and 4.3 mm for stressed. On average, peak AC joint separation distance in anteroposterior, mediolateral, and inferosuperior directions during shoulder-abduction, flexion, and scaption was shown to be restored to 11.5 mm of native values after reconstruction with LockDown device. Conclusion Reconstruction of AC joint with LockDown synthetic ligament restores motion of clavicle and acromion to near native values, thereby decreasing scapular dyskinesis and enhancing AC joint stability.

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

PurposeTo 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 methodsTwenty-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.ResultsPostoperatively, 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).ConclusionsSubstantial 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 evidenceIV.