The Combined Suture Bridge With Mason-Allen Technique Is Superior to the Conventional Suture Bridge Technique for Arthroscopic Rotator Cuff Repair.

PURPOSE: To compare clinical results and retear rates between the combined suture bridge with Mason-Allen (SBMA) technique and the conventional suture bridge (SB) technique in patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair. METHODS: One hundred two patients who underwent arthroscopic rotator cuff repair using the SB technique (n = 50) or SBMA technique (n = 52) for a full-thickness rotator cuff tear and had at least 2 years of follow-up were retrospectively analyzed. Magnetic resonance imaging was performed before surgery and 2 years after to determine preoperative tear size, Goutallier stage, and presence of retear after surgery. Patients were clinically evaluated using the Japanese Orthopaedic Association (JOA) score. RESULTS: The groups did not significantly differ in terms of follow-up period, age, sex, tear size, Goutallier stage, or number of suture anchors. The retear rate was significantly lower in the SBMA group (7.7% vs 28.0%; P < .01). The JOA score was significantly higher at last follow-up than before surgery in both groups (P <.01). The JOA score at last follow-up was significantly higher in the SBMA group (P = .02). CONCLUSIONS: Arthroscopic rotator cuff repair using the SBMA technique may provide better clinical and anatomical outcomes than the conventional SB technique. LEVEL OF EVIDENCE: Level III, retrospective cohort design; treatment study).

Shear wave elastography correlates to degeneration and stiffness of the long head of the biceps tendon in patients undergoing tenodesis with arthroscopic shoulder surgery.

BACKGROUND: Tendinopathy of the long head of the biceps (LHB) tendon causes degeneration and changes its stiffness. However, a reliable means of diagnosis has not been established. Shear wave elastography (SWE) provides quantitative tissue elasticity measurements. In this study, the relationship of preoperative SWE values with biomechanically measured stiffness and degeneration of the LHB tendon tissue was investigated. METHODS: LHB tendons were obtained from 18 patients who underwent arthroscopic tenodesis. SWE values were measured preoperatively at 2 sites, proximal to and within the bicipital groove of the LHB tendon. The LHB tendons were detached immediately proximal to the fixed sites and at their superior labrum insertion. Tissue degeneration was histologically quantified using the modified Bonar score. Tendon stiffness was determined using a tensile testing machine. RESULTS: The SWE values of the LHB tendon were 502.1 ± 113.6 kPa proximal to the groove and 439.4 ± 123.3 kPa within the groove. The stiffness was 39.3 ± 19.2 N/mm. The SWE values displayed a moderate positive correlation with the stiffness proximal to the groove (r = 0.80) and within it (r = 0.72). The SWE value of the LHB tendon within the groove showed a moderate negative correlation with the modified Bonar score (r = -0.74). CONCLUSIONS: These findings suggest that preoperative SWE values of the LHB tendon correlate moderately positively with stiffness and moderately negatively with tissue degeneration. Therefore, SWE may predict LHB tendon tissue degeneration and changes in stiffness caused by tendinopathy.

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography.

PURPOSE: To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing. METHODS: Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1 month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis. RESULTS: Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing. CONCLUSIONS: The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Arthroscopic Bankart repair with additional footprint fixation using the double-row technique at the 4 o'clock position anatomically restored the capsulolabral complex and showed good clinical results.

PURPOSE: To investigate the clinical outcome and magnetic resonance imaging (MRI) findings after arthroscopic Bankart repair with additional double anchor footprint fixation (DAFF) at the 4 o'clock position, where the native footprint is widest anatomically, for recurrent anterior shoulder instability. METHODS: Forty-two patients (mean age 27.0 years) with recurrent anterior shoulder instability and without severe glenoid bone defects underwent arthroscopic Bankart repair with additional DAFF at the 4 o'clock position. Using three standard portals, single-row repair was performed at the 2, 3, and 5 o'clock positions, and DAFF with the suture bridging technique was conducted at the 4 o'clock position. MRI was performed preoperatively and at 6 months postoperatively. Patients with follow-up periods of ≥1 year were included in the present study and clinically evaluated at the final follow-up. The morphology at the 2 and 4 o'clock positions on radial MRI slices was compared between the preoperative and 6-month postoperative scans, and the footprint of the repaired capsulolabral complex at 6 months postoperatively was compared between the 2 and 4 o'clock positions. RESULTS: The average follow-up period was 19.5 ± 6.2 months. The rates of dislocation recurrence and positive apprehension test results were 2.4 and 4.8%, respectively. External rotation was restricted by 3.5°. The University of California at Los Angeles and Rowe scores at the final follow-up were 34.5 ± 1.0 points and 97.2 ± 5.7 points, respectively, representing significant improvements over the preoperative scores (p < 0.01). Although the capsulolabral complex at 6 months postoperatively was firmly repaired at both the 2 and 4 o'clock positions compared to its preoperative state, the footprint of the restored capsulolabral complex was wider at the 4 o'clock position than at the 2 o'clock position (p < 0.01). CONCLUSIONS: Additional DAFF at the 4 o'clock position improved the glenohumeral stability and function of the shoulder joint. This study suggests that this technique is a reliable and useful treatment for shoulder instability. LEVEL OF EVIDENCE: IV.

Editorial Commentary: Human Granulocyte-Stimulating Factor Increases the Leukocyte Richness of Platelet-Rich Plasma.

Platelet-rich plasma (PRP) is the most common treatment in orthobiologis, because PRP is safe, low cost, and minimally invasive and could be used to promote the tissue-repair process. The systemic mobilization with human granulocyte-stimulating factor increased concentrations of white blood cells and monocyte but not platelets in PRP. It may enhance the efficacy of PRP therapy via monocytes/macrophages. Improving the efficacy of PRP therapy, bone marrow aspirate, mesenchymal stems cells, or other orthobiologics is not simple because there are many variations in products and patient factors.

Anatomic Analysis of the Attachment of the Posteroinferior Labrum and Capsule to the Glenoid: A Cadaveric Study.

PURPOSE: To measure the height of the posteroinferior glenohumeral ligament (PIGHL) attachment to the labrum and the depth of the posteroinferior labrum to the glenoid, macroscopically, and to investigate the morphology of the attachment of the posteroinferior labrum to the glenoid, histologically. METHODS: Fifty cadaveric shoulders without exposed subchondral bone on the glenoid and detached posterior labrum were used. We examined the frequency of the heights of the PIGHL attachments to the labrum and the length of the labral attachment on the glenoid rim at the 7, 8, 9, and 10 o'clock positions, macroscopically. According to morphology of the histological labral attachments, it was divided into 3 groups. Labra attached on the articular surface and the glenoid neck were defined as the SN type, while labra attached only to the glenoid neck constituted labra attached to the bone and side of the articular cartilage (Nc type) and labra attached only to bone (Nb type). RESULTS: The PIGHL attached from 7 o'clock to 9 o'clock in 48 shoulders (96%). The mean labral attachment at the 7 o'clock position was 6.3 ± 1.0 mm (range, 4.6-9.4 mm), which was significantly longer than at the other positions (P < .05). Histologically, the frequency of SN type attachment was 49 (98%) shoulders at the 7 o'clock position. CONCLUSIONS: The PIGHL attached between 7 and 9 o'clock in 96% of the shoulders. In 98% of the shoulders, the labrum did not attach to the articular surface, but attached to both the articular cartilage and the bone of the glenoid neck at 7 o'clock. CLINICAL RELEVANCE: The posteroinferior labrum should be repaired widely at the 7 o'clock position and not on the articular surface because the labrum attached anatomically to the glenoid neck.

Reconstruction of the Acromioclavicular Ligament Complex Using Dermal Allograft: A Biomechanical Analysis.

PURPOSE: To analyze the posterior translational and rotational stability of the acromioclavicular (AC) joint following reconstruction of the superior acromioclavicular ligament complex (ACLC) using dermal allograft. METHODS: Six fresh-frozen cadaveric shoulders were used (mean age of 65.3 ± 6.9 years). The resistance force against posterior translation (10 mm) and torque against posterior rotation (20°) was measured. Specimens were first tested with both the intact ACLC and coracoclavicular ligaments. The ACLC and coracoclavicular ligaments were then transected so simulate a Type III/V AC joint dislocation. Each specimen then underwent 3 testing conditions, performed in the following order: (1) ACLC patch reconstruction alone, (2) ACLC patch with an anatomic coracoclavicular reconstruction (ACCR) using semitendinosus allograft, and (3) the transected ACLC with an ACCR only. Differences in posterior translational and rotational torque across testing conditions were analyzed with a one-way repeated analysis of variance analysis. RESULTS: Mean resistance against posterior translation in the intact condition was 65.76 ± 23.8 N. No significant difference found between the intact condition compared with specimens with the ACLC-patch only (44.2 ± 11.3 N, P = .06). The ACCR technique, when tested alone, had significantly less posterior translational resistance compared with the intact condition (38.5 ± 8.94 N, P = .008). ACLC patch in combination with an ACCR was closest in restoring native posterior translation (57.1 ± 19.2 N, P = .75). For rotational resistance, only the addition of the ACLC patch with an ACCR (0.51 ± 0.07 N-m) demonstrated similar torque compared with the intact joint (0.89 ± 0.5 N-m, P = .06). CONCLUSIONS: The ACLC-patch plus ACCR technique was able to closest restore the percent of normal posterior translational and rotational stability. CLINICAL RELEVANCE: Recurrent posterior instability of the AC joint is a potential complication after coracoclavicular reconstruction surgery. In the in vitro setting, this study demonstrated increased AC joint stability with the addition of an ACLC reconstruction using dermal allograft.

Intraoperative and In Vitro Classification of Subacromial Bursal Tissue.

PURPOSE: To classify subacromial bursal tissue using intraoperative and in vitro characteristics from specimens harvested during arthroscopic shoulder surgery. METHODS: Subacromial bursa was harvested over the rotator cuff from 48 patients (57 ± 10 years) undergoing arthroscopic shoulder surgery. Specimens were characterized intraoperatively by location (over rotator cuff tendon or muscle), tissue quality (percent of either fatty or fibrous infiltration), and vascularity before complete debridement. Nucleated cell counts were determined after 3 weeks incubation and histological sections were reviewed for degree of fatty infiltration and vascularity. Mesenchymal stem cell surface markers were counted via flow cytometry (n = 3) and cellular migration was observed using a fluoroscopic assay (n = 3). RESULTS: Intraoperatively, muscle bursa was found most often to have >50% fatty infiltration (n = 39), whereas tendon bursa showed majority fibrous tissue (n = 32). Cellular proliferation did not significantly differ according to intraoperative tissue quality. Intraoperative vascularity was associated with greater proliferation for highly vascular samples (P = 0.023). Tendon bursa demonstrated significantly greater proliferation potential than muscle bursa (P = 0.00015). Histologic assessment of fatty infiltration was moderately correlated with gross tissue fattiness (ρ = -0.626, P = 7.14 × 10-11). Flow cytometry showed that 90% to 100% of bursal cells were positive for MSC surface markers. Peak cellular migration rates occurred between 18 and 30 hours' incubation. CONCLUSIONS: Intraoperative and in vitro subacromial bursa characteristics were not found to reliably correlate with the degree of cellular proliferation. However, the anatomic location of subacromial bursa was consistently predictive of increased proliferation potential. Bursa-derived nucleated cells were confirmed to include mesenchymal stem cells with migratory potential. CLINICAL RELEVANCE: The anatomic distinction between muscle and tendon bursa provides a simple classification for predicting cellular activity.

The Effect of Glenohumeral Fixation Angle on Deltoid Function During Superior Capsule Reconstruction: A Biomechanical Investigation.

PURPOSE: To evaluate the effect of dermal allograft fixation at different angles of glenohumeral abduction on deltoid forces during superior capsule reconstruction (SCR). METHODS: Fifteen cadaveric specimens were tested using a dynamic shoulder simulator. Following testing in the native state, shoulders underwent SCR in 2 of 5 possible fixation angles; 0°, 15°, 30°, 45°, or 60° of glenohumeral abduction, allowing for 6 specimens per group. Angles were measured radiographically with the glenoid fixed perpendicular to the floor. Maximum mean deltoid abduction force was compared among 5 separate conditions within each angle group: (1) native shoulder, (2) complete supraspinatus (SSP) and superior capsule tear, (3) SCR alone, (4) SCR with posterior margin sutured, and (5) SCR with anterior and posterior margins sutured. RESULTS: SSP tears significantly increased the maximum deltoid forces for all 5 fixation angles compared with the native state (P < .05). Specimens repaired at 0°, 30°, and 45° were unable to restore deltoid forces compared with the native state in any condition (P < .05). SCR at 15° with anterior and posterior margin convergence showed similar abduction forces compared with the native state (P = .19). When fixed at 60° abduction, SCR alone significantly reduced deltoid forces compared to SSP (Δ143N, P < .001) and native (Δ48N, P < .001). No significant differences were found between the 3 repair subtypes (SCR ± anterior/posterior margin repair) in the 60° group. CONCLUSIONS: SCR with anterior and posterior margin convergence tensioned at 15° of glenohumeral abduction showed similar deltoid abduction force requirements compared with the native state, whereas graft fixation in 60° significantly reduced deltoid force in all SCR conditions. CLINICAL RELEVANCE: Increased graft tension with a greater abduction angle may provide greater functional outcome by placing less load on the deltoid. In contrast, graft fixation in lower abduction angles may require additional margin convergence to reproduce native forces.

Biomechanical Effect of Superior Capsule Reconstruction Using a 3-mm and 6-mm Thick Acellular Dermal Allograft in a Dynamic Shoulder Model.

PURPOSE: To biomechanically compare the effect of superior capsule reconstruction (SCR) using a 3- and 6-mm thick acellular dermal allograft for the treatment of irreparable rotator cuff tears. METHODS: Eight fresh-frozen cadaveric shoulders were tested using a dynamic shoulder model. Maximum abduction angle (MAA), glenohumeral superior translation (ghST), subacromial peak contact pressure (sPCP), and cumulative deltoid force (cDF) were compared among 4 conditions: (1) intact shoulder, (2) simulated irreparable rotator cuff tear (RCT), (3) SCR using a 3-mm-thick acellular dermal allograft, (4) SCR using a 6-mm-thick acellular dermal allograft. RESULTS: Compared with the intact state, simulated irreparable RCTs significantly decreased MAA (P < .001), while significantly increasing ghST (P = .001), sPCP (P < .001), and cDF (P < .001). SCR with a 3-mm-thick graft significantly increased MAA (P = .01) and decreased ghST (P = .01) compared with the RCT state, however, showed similar sPCP and cDF. Compared with the torn state, SCR with a 6-mm-thick graft significantly increased MAA (P < .001) and significantly decreased ghST (P < .001), sPCP (P < .001), and cDF (P = .001). Using a 6-mm-thick graft demonstrated similar MAA, ghST, sPCP, and cDF compared with the intact state. When comparing the 3-mm to the 6-mm thick graft, significant differences were found in ghST (P = .03), sPCP (P < .001), and cDF (P = .02). CONCLUSIONS: SCR with a 6-mm-thick acellular dermal allograft better restored normal glenohumeral joint position and forces compared with a 3-mm-thick graft for the treatment of irreparable RCTs. CLINICAL RELEVANCE: Graft thickness may affect the clinical success following SCR with commercially available dermal allografts. Using a thicker (>3 mm) graft was able to biomechanically better restore native glenohumeral joint properties.

Comparison of Preparation Techniques for Isolating Subacromial Bursa-Derived Cells as a Potential Augment for Rotator Cuff Repair.

PURPOSE: To identify an effective, nonenzymatic method for maximizing the yield of subacromial bursa-derived nucleated cells for augmenting rotator cuff repair. METHODS: Subacromial bursa (minimum 0.2 g) was collected prospectively over the supraspinatus from patients (n = 7) with at least one full-thickness tendon tear undergoing arthroscopic primary rotator cuff repair. Samples were processed and analyzed prospectively using 4 different methods: (1) mechanical digestion with scissors (chopping), (2) collagenase digestion, (3) mechanical digestion with a tissue homogenizer, and (4) whole tissue with minimal manipulation. Tissue from each method were plated and cultured in a low oxygen tension, humidified incubator for 7 days. Following incubation, cellularity was assessed with nucleated cell count using a Coulter Counter. Flow cytometry was performed on the non-enzymatic method that demonstrated the greatest cell count to confirm the presence of mesenchymal stem cells (MSCs). The Kruskal-Wallis H test and post hoc Dunn's test were used for statistical analysis. RESULTS: Following incubation, mean nucleated cell counts (cells/mL) were (1) 102,681 ± 73,249 for chopping, (2) 76,190 ± 66,275 for collagenase, (3) 31,686 ± 29,234 for homogenization, and (4) 11,162 ± 4016 for whole tissue. There was no significant difference between chopping and collagenase (P = .45) or between homogenization and collagenase (P = .52). Both chopping (P = .003) and collagenase (P = .03) produced significantly more cells when compared with whole tissue. Flow cytometry confirmed the presence of MSC markers on samples processed by chopping. CONCLUSIONS: Mechanical isolation of subacromial bursa-derived cells using a chopping technique demonstrated similar nucleated cell count compared with collagenase, along with the confirmed presence of MSCs. CLINICAL RELEVANCE: This study demonstrated a nonenzymatic, mechanical method for isolating subacromial bursa-derived cells to potentially augment rotator cuff repair. Further clinical studies are required to assess its possible advent in the tendon-bone healing process.

LUCL internal bracing restores posterolateral rotatory stability of the elbow.

PURPOSE: Posterolateral rotatory instability (PLRI) of the elbow occurs from an insufficient lateral collateral ligament complex (LCLC). For subacute LCLC injuries, lateral ulnar collateral ligament (LUCL) internal bracing rather than reconstruction may be a viable option. The purpose of the study was to compare the stabilizing effects of LUCL internal bracing to triceps tendon graft reconstruction in simulated PLRI. METHODS: Sixteen cadaveric elbows were assigned for either LUCL internal bracing (n = 8) or reconstruction with triceps tendon graft (n = 8). Specimen were mounted and a valgus rotational torque was applied to the ulna to test posterolateral rotatory stability. Posterolateral rotation was measured at 0°, 30°, 60°, 90° and 120° of elbow flexion. Cyclic loading was performed for 1000 cycles at 90° of elbow flexion. Three conditions were compared in each specimen: intact elbow, LUCL and radial collateral ligament (RCL) transected, and then either LUCL internal bracing or reconstruction with triceps tendon graft. RESULTS: Transection of the LUCL and RCL significantly increased posterolateral rotation in all degrees of elbow flexion compared to the intact condition (P < 0.05). Both LUCL internal bracing and reconstruction restored posterolateral rotatory stability to the native state between 0° and 120° of elbow flexion, with no significant difference in improvement between groups. Similarly, LUCL internal bracing and reconstruction groups showed no significant difference in posterolateral rotation compared to the intact condition during cyclic loading. CONCLUSIONS: At time zero, both LUCL internal bracing and reconstruction with triceps tendon graft restored posterolateral rotatory stability. As such, this study supports the use of internal bracing as an adjunct to primary ligament repair in subacute PLRI.

Acellular dermal matrix augmentation significantly increases ultimate load to failure of pectoralis major tendon repair: a biomechanical study.

BACKGROUND: Biomechanical studies have demonstrated that standard pectoralis major tendon (PMT) repairs have inferior strength compared with native tendon. HYPOTHESIS: Augmentation of PMT repair with an acellular dermal matrix (ADM) will increase the ultimate load to failure. METHODS: Eighteen cadaveric specimens were allocated to 3 repair groups: standard repair (SR); augmented repair (AR) with ADM; and intact, native tendon (NT). Specimens were tested for cyclic elongation, linear stiffness, load to 5 mm displacement, maximum load to failure, and method of failure. RESULTS: Maximum load to failure in AR (1450 ± 295 N) was significantly higher than SR (921 ± 159 N; P = .0042) and equivalent to NT (1289 ± 240 N; P = .49). NT required the highest load to displace 5 mm (709 ± 202 N), which was higher than AR (346 ± 95 N; P < .001) and SR (375 ± 55; P = .0015). NT stiffness (125 ± 42 N/mm) was greater than the AR (69 ± 19 N/mm; P = .0073) or SR (75 ± 11 N/mm; P = .015). The mode of failure for SR was suture pullout from the PMT as opposed to button pullout from the humerus (fracture) for AR. CONCLUSION: ADM augmentation of PMT repair significantly increases ultimate load to failure.

Examining the Potency of Subacromial Bursal Cells as a Potential Augmentation for Rotator Cuff Healing: An In Vitro Study.

PURPOSE: To compare the potency of mesenchymal stem cells between the cells derived from the subacromial bursa to concentrated bone marrow aspirate (cBMA) taken from patients undergoing rotator cuff (RC) repair. METHODS: Subacromial bursa and cBMA were harvested arthroscopically from 13 patients (age 57.4 ± 5.2 years, mean ± standard deviation) undergoing arthroscopic primary RC repair. Bone marrow was aspirated from the proximal humerus and concentrated using an automated system (Angel System; Arthrex). Subacromial bursa was collected from 2 sites (over the RC tendon and muscle) and digested with collagenase to isolate a single cellular fraction. Proliferation, number of colony-forming units, differentiation potential, and gene expression were compared among the cells derived from each specimen. RESULTS: The cells derived from subacromial bursa showed significantly higher proliferation compared with the cells derived from cBMA after 5, 7, and 10 days (P = .018). Regarding colony-forming units, the subacromial bursa had significantly more colonies than cBMA (P = .002). Subacromial bursal cells over the RC tendon produced significantly more colonies than cells over both the RC muscle and cBMA (P = .033 and P = .028, respectively). Moreover, when compared with cBMA, cells derived from subacromial bursa showed significantly higher differentiation ability and higher gene expression indicative of chondrogenesis, osteogenesis, and adipogenesis. CONCLUSION: The subacromial bursa is an easily accessible tissue that can be obtained during RC repair, with significant pluripotent stem cell potency for tendon healing. Compared with cBMA taken from the proximal humerus, bursal cells showed significantly increased differentiation ability and gene expression over time. CLINICAL RELEVANCE: Failed RC repairs have been partly attributed to a poor healing environment. Biologic augmentation of the repair site may help increase healing potential and incorporation of the cuff at the tendon-bone interface.

Repair of the entire superior acromioclavicular ligament complex best restores posterior translation and rotational stability.

PURPOSE: The acromioclavicular ligament complex (ACLC) is the primary stabilizer against horizontal translation with the superior ACLC providing the main contribution. The purpose of this study was to evaluate the specific regional contributions in the superior half of ACLC, where the surgeon can easily access and repair or reconstruct, for posterior translational and rotational stability. METHODS: The superior half of ACLC was divided into three regions; Region A (0°-60°): an anterior 1/3 region of the superior half of ACLC, Region B (60°-120°): a superior 1/3 region of the superior half of ACLC, and Region C (120°-180°): a posterior 1/3 region of the superior half of ACLC. Fifteen fresh-frozen cadaveric shoulders were used. Biomechanical testing was performed to evaluate the resistance force against passive posterior translation (10 mm) and the resistance torque against passive posterior rotation (20°) during the following the four conditions. (1) Stability was tested on all specimens in their intact condition (n = 15). (2) The ACLC was dissected and stability was tested (n = 15). (3) Specimens were randomly divided into three groups by regions of suturing. Stability was tested after suturing Region A, Region B, or Region C (n = 5 per group). (4) Stability was tested after suturing additional regions: Region A + B (0°-120°), Region B + C (60°-180°), or Region A + C (0°-60°, 120°-180°, n = 5 per group). RESULTS: The translational force increased after suturing Region A when compared with dissected ACLC (P = 0.025). The force after suturing Region A + B was significantly higher compared to the dissected ACLC (P < 0.001). The rotational torque increased after suturing Region A or Region B compared with dissected ACLC (P = 0.020, P = 0.045, respectively). The torque after suturing the Region A + C was significantly higher compared to the dissected ACLC (P < 0.001). CONCLUSION: The combined Region A + B contributed more to posterior translational stability than Region B + C or Region A + C. In contrast, combined Region A + C contributed more to posterior rotational stability than Region A + B or Region B + C. Based on these findings, surgical techniques restoring the entire superior ACLC are recommended to address both posterior translational and rotational stability of the AC joint.

Editorial Commentary: The Coracoid Process as the Origin of Several Ligaments: What May Be Cut, What Must Be Refixed?

The coracoid process is the origin of the trapezoid ligament, the deltoid ligament, and the coracoacromial ligament (CAL). Detailed knowledge about their anatomy is crucial for surgical procedures such as the reconstruction of the coracoclavicular ligaments or coracoid transfer. Although the coracoclavicular ligaments are considered important stabilizers of the acromioclavicular joint and are therefore highly protected, the CAL seems less important, which is why it is generally cut during coracoid transfer procedures. However, there is evidence that the CAL contributes to muscular balance and stabilization of the shoulder girdle. Therefore, an individual approach should be considered during coracoid transfer to save at least parts of the CAL.

Higher Critical Shoulder Angle and Acromion Index Are Associated With Increased Retear Risk After Isolated Supraspinatus Tendon Repair at Short-Term Follow Up.

PURPOSE: To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair. METHODS: Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI. RESULTS: Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P = .648), initial tear size (P = .205), or fatty degeneration (P = .508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P = .014). If the CSA was >38°, the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P = .042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P = .049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P = .739). CONCLUSIONS: At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate. LEVEL OF EVIDENCE: III, case control study.

Contribution of oxidative stress to the degeneration of rotator cuff entheses.

BACKGROUND: Rotator cuff degeneration is one of the multiple factors that lead to rotator cuff tears; however, the precise mechanism of such degeneration still remains unclear. In this study, we investigated the supraspinatus tendon enthesis to clarify the link between rotator cuff degeneration and oxidative stress in antioxidant enzyme superoxide dismutase 1 (Sod1)-deficient mice (Sod1(-/-)). METHODS: The supraspinatus tendon and humeral head were isolated and fixed to prepare histologic sections from wild-type and Sod1(-/-) male mice at 20 weeks of age. Hematoxylin-eosin staining was performed to assess the histomorphologic structure. To investigate the collagen fibers, we examined spatially aligned collagen fibers using a polarizing microscope and assessed the amount of collagen using immunohistochemical staining. To analyze the tissue elasticity, we measured the tissue acoustic properties using scanning acoustic microscopy. RESULTS: The Sod1(-/-) mice showed histologic changes, such as a misaligned 4-layered structure and fragmented tidemark, in the enthesis. Sod1 loss also decreased the amount of brightly diffracted light and type I collagen, indicating collagen downregulation. The scanning acoustic microscopy analysis showed that the speed and attenuation of sound were increased in the nonmineralized fibrocartilage of the Sod1(-/-) mice, suggesting decreased mechanical properties in the supraspinatus enthesis. CONCLUSION: Sod1 deficiency-induced degeneration is associated with impaired elasticity in the supraspinatus tendon enthesis, recapitulating human rotator cuff degeneration. These results suggest that intracellular oxidative stress contributes to the degeneration of rotator cuff entheses.

Arthroscopically Assisted Coracoclavicular (CC) Stabilization Using a Suture Button Device for Lateral Clavicle Fractures with CC Ligament Injury.

Background: Lateral clavicle fractures represent approximately 10-15% of all clavicle fractures. However, controversy exists regarding the optimal surgical treatment because of instability associated with the coracoclavicular (CC) ligament injury and a small lateral fragment. The purpose of this study was to evaluate the radiological and clinical outcomes of arthroscopically assisted CC stabilization using a suture button device for lateral clavicle fractures accompanied by CC ligament injury. Methods: A retrospective observational study involved six patients with modified Neer type IIB fractures, which were treated with the technique and followed for 12 months. Postoperative range of motion (ROM) and X-rays were evaluated every 3 months. Shoulder functional scores (University of California Los Angeles score, Japanese Orthopedics Association score) and visual analog scale (VAS) scores for pain (at rest, at night, and during motion) and for satisfaction were analyzed 12 months after surgery. Results: Early phase ROM recovery and excellent outcomes were achieved. All patients achieved bone union. Slight superior clavicle displacement and bone hole dilation occurred with no critical complications. Conclusions: Arthroscopically assisted CC stabilization with a suture button device for unstable lateral clavicle fractures can produce satisfactory radiological and clinical results.

Chronologic Changes in the Elastic Modulus of a Healing Achilles Tendon Rupture Measured Using Shear Wave Elastography.

BACKGROUND: Shear wave elastography (SWE) has been used to examine the elasticity of a ruptured Achilles tendon; however, the healing process of a ruptured tendon has not been studied yet. This study aimed to detail the change in mechanical properties of a healing Achilles tendon rupture managed conservatively or surgically using SWE. METHODS: Using a prospective cohort study design, we evaluated the patients treated conservatively (conservative group) and surgically (surgical group) with the "gift-box" technique for an isolated index acute Achilles tendon rupture during their healing process. SWE measurements were taken of both the injured and uninjured sides every 4 weeks up to 24, 36, and 48 weeks after treatment. Additionally, tendon thickness and power Doppler (PD) grade were measured at the same time points as SWE measurements. The American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot rating system score and Achilles tendon Total Rupture Score (ATRS) were compared at 24 and 48 weeks. RESULTS: The ruptured Achilles tendon obtained an SWE value comparable with the unruptured side at 12 weeks in the conservative group and at 4 weeks with surgical group. The surgical group had significantly higher SWE values up to 24 weeks compared with the conservative group. Additionally, this group had a significantly larger increase in tendon thickness in nearly all periods. Both treatment groups were comparable regarding the PD grade, AOFAS score, and ATRS. CONCLUSION: SWE is a convenient noninvasive method to determine the progress of the healing process after tendon injury. Our analysis using SWE has revealed the detailed chronologic changes in SWE values and related mechanical properties of a healing Achilles tendon rupture, which can be used for devising appropriate rehabilitation protocols. LEVEL OF EVIDENCE: Level II, prospective cohort study.