Arthroscopic reduction and hollow screw internal fixation for Eyres Type IIIA scapular coracoid fracture: a case report.

BACKGROUND: A coracoid process fracture combined with an acromioclavicular (AC) joint dislocation is an uncommon injury that typically causes significant pain and limits shoulder movement. Open reduction and internal fixation have been the traditional treatment approach. However, arthroscopic techniques are emerging as a promising alternative for managing these injuries. CASE REPRESENTATION: A 35-year-old woman presented with right shoulder pain following an accidental fall. Imaging studies revealed a coracoid process fracture along with an AC joint dislocation. The fracture was classified as an Eyres Type IIIA, which warranted surgical intervention. Our team performed arthroscopic coracoid fracture reduction and internal fixation surgery, as well as AC joint dislocation repair using Kirschner wires. Six months after surgery, the patient demonstrated a satisfactory functional outcome with complete bone healing. CONCLUSION: This case report highlights the potential of arthroscopic reduction and fixation as a novel treatment option for fractures of the coracoid base.

Inlay structure can improve bone graft stability in the Bristow procedure.

BACKGROUND: Compared with the Latarjet procedure, the Bristow procedure has a lower screw-related complication rate but poor bone healing. A modified Inlay Bristow procedure has been reported to significantly improve the bone healing rate, but the biomechanical mechanism is unclear. The aim of this study was to evaluate the biomechanical stability of the bone graft between a modified Inlay Bristow procedure and the classic Bristow procedure. METHODS: Sixteen left scapula models (Sawbones, Composite Scapula, and fourth generation) were randomly divided into 2 groups (8:8). The bone graft in the first group was fixed with a 3.5 mm screw using the Inlay structure. The bone graft in the second group was fixed with a 3.5 mm screw via the traditional method. The maximum cyclic displacement, ultimate failure load and stiffness were evaluated biomechanically. The failure type was recorded for each model. RESULTS: Cyclic loading tests demonstrated that the maximum cyclic displacement of the Inlay procedure was significantly smaller (P = .001) than that of the classic procedure. The Inlay Bristow technique resulted in a significantly higher (P = .024) ultimate failure load than the classic Bristow technique. The stiffness of the classic group was 19.17 ± 4.01 N/mm and that of the inlay group was 22.34 ± 5.35 N/mm (P = .232). Failure was mainly due to bone graft fractures through the drill hole or glenoid bone fractures. CONCLUSION: Inlay Bristow fixation of the bone graft in a Sawbones model provides significantly stronger fixation and better time point zero stability than classic Bristow fixation, suggesting a higher likelihood of graft union.

Stability of novel cow-hitch suture button coracoid bone graft fixation in Latarjet procedures: a biomechanical study.

BACKGROUND: The Latarjet procedure is widely used to address anterior shoulder instability, especially in case of glenoid bone loss. Recently, cortical suture button fixation for coracoid transfer has been used to mitigate complications seen with screw placement. The aim of this biomechanical study was to evaluate the stability of a novel and cost-effective cow-hitch suture button technique, designed to be performed through a standard open deltopectoral approach, and compare this to a well-established double suture button technique. MATERIALS AND METHODS: We randomly assigned 12 fresh frozen cadaveric shoulders to undergo the Latarjet procedure with either 4 suture button (S&N EndoButton) fixations (SB group; n = 6, age 72 ± 9.8 years) or cow-hitch suture button technique using a 1.7-mm FiberTape looped sequentially in 2 suture buttons (Arthrex Pectoralis Button) placed from anterior on the posterior glenoid (CH-SB group; n = 6, age 73 ± 9.3 years). After fixation, all shoulders underwent biomechanical testing with direct loading on the graft via a material testing system. Cyclic loading was performed for 100 cycles (10-100 N) to determine axial displacement with time; each graft was then monotonically loaded to failure. RESULTS: The maximum cyclic displacement was 4.3 ± 1.6 mm for the cow-hitch suture button technique and 5.0 ± 1.7 mm for the standard double suture button technique (P = .46). Ultimate load to failure and stiffness were, respectively, 190 ± 82 N and 221 ± 124 N/mm for the CH-SB technique and 172 ± 48 N and 173 ± 34 N/mm for the standard double SB technique (P = .66 and .43). The most common failure mode was suture cut-through at the anteroinferior aspect of the glenoid for both fixation groups. CONCLUSIONS: The cow-hitch suture button technique resulted in a similar elongation, stiffness, and failure load compared to an established double suture button technique. Therefore, this cost-effective fixation may be an alternative, eligible for open approaches, to the established double suture button techniques.

Latarjet procedure: biomechanical evaluation of 2-screw coracoid fixation.

BACKGROUND: Coracoid nonunion is a relevant complication following the Latarjet procedure and is influenced by multiple factors, including the method of graft fixation. The purpose of this study was to evaluate and characterize the biomechanical properties of various two-screw fixation constructs used for coracoid graft fixation in the Latarjet procedure. METHODS: Forty model scapulae (Sawbones Inc., Vashon, WA, USA) were used for this study. A 15% anterior inferior glenoid bone defect was created. The coracoid was osteotomized at the juncture of the vertical and horizontal aspects, transferred to the anterior-inferior edge of the glenoid, and fixed with either two 3.5 mm fully threaded cannulated cortical screws, two 3.5 mm fully threaded solid cortical screws, two 3.5 mm partially threaded cannulated screws, or two 4.5 mm partially threaded malleolar screws (MS). Biomechanical testing was performed with an Instron material testing machine (Instron Corp., Norwood, MA, USA) by applying loads to the lateral aspect of the transferred coracoid graft. The constructs were preconditioned with nondestructive cyclical loading (0N-20N) to determine construct stiffness. After 100 cycles of dynamic loading, the construct was loaded to failure to determine ultimate failure load, yield displacement, and mode of failure. RESULTS: All failures were associated with plastic deformation of the screws and coracoid graft fracture. There was a significantly lower initial stiffness for partially threaded cannulated screws compared to MS (186 ± 49.3 N/mm vs. 280 ± 65.5 N/mm, P = .01) but no significant differences among the other constructs. There was no difference in ultimate failure load (P = .18) or yield displacement (P = .05) among constructs. CONCLUSION: Two screw coracoid fixation of the coracoid in a simulated classic Latarjet procedure with 3.5 mm fully threaded cortical and cannulated screws is comparable to 4.5 mm MS in strength, stiffness, and displacement at failure. On the other hand, partially threaded 3.5 mm cannulated screws provide inferior fixation stiffness and could potentially affect clinical outcomes.

Risk of suprascapular nerve injury in open Trillat procedure: an anatomical study.

PURPOSE: The open Trillat Procedure described to treat recurrent shoulder instability, has a renewed interest with the advent of arthroscopy. The suprascapular nerve (SSN) is theoretically at risk during the drilling of the scapula near the spinoglenoid notch. The purpose of this study was to assess the relationship between the screw securing the coracoid transfer and the SSN during open Trillat Procedure and define a safe zone for the SSN. METHODS: In this anatomical study, an open Trillat Procedure was performed on ten shoulders specimens. The coracoid was fixed by a screw after partial osteotomy and antero-posterior drilling of the scapular neck. The SSN was dissected with identification of the screw. We measured the distances SSN-screw (distance 1) and SSN-glenoid rim (distance 2). In axial plane, we measured the angles between the glenoid plane and the screw (α angle) and between the glenoid plane and the SSN (ß angle). RESULTS: The mean distance SSN-screw was 8.8 mm +/-5.4 (0-15). Mean α angle was 11°+/-2.4 (8-15). Mean ß angle was 22°+/-6.7 (12-30). No macroscopic lesion of the SSN was recorded but in 20% (2 cases), the screw was in contact with the nerve. In both cases, the ß angle was measured at 12°. CONCLUSION: During the open Trillat Procedure, the SSN can be injured due to its anatomical location. Placement of the screw should be within 10° of the glenoid plane to minimize the risk of SSN injury and could require the use of a specific guide or arthroscopic-assisted surgery.

Ipsilateral fractures of the acromion and coracoid processes of the scapula.

A fracture of the acromion and coracoid processes of scapula is rarely seen in the outpatient clinic, due to the acromion's anatomical position and shape, as well as the strong ligaments and muscles that are attached to it. These fractures are caused by either direct or indirect high-energy trauma injuries to the shoulder joint, leading to severe pain and a grossly restricted range of motion. Several acromial classifications were reported, but this type of longitudinal plane fracture of the acromion process in our case is yet to be described in the current literature. We present a rare combination of the coracoid process and unstable acromion bony projection fractures that have not previously been noted for this type of fracture. The closest to this is Kuhn's type III classification. A 51-year-old male presented to our emergency department complaining of the right shoulder pain and difficulty raising his arm following a 2-wheeler accident. The patient was managed by open reduction and internal fixation with 3 cannulated cancellous screws fixation and progressed well with no postoperative complications. He was asymptomatic postoperatively and regained full range of motion after 4 months.

Risk factors and incidence of short-term complications following open reduction and internal fixation of scapula fractures.

PURPOSE: To determine the short-term complication rates following open reduction and internal fixation of scapula fractures, factors affecting the development of adverse events, and complication rates based on the anatomic location of the fracture. METHODS: Thirty-day complication rates for patients who underwent open reduction and internal fixation of the scapula were compared between glenoid, body, coracoid, and acromion fracture locations, as identified by International Classification of Disease codes. Possible adverse events included postoperative surgical site infection, renal insufficiency, intubation, pneumonia, deep vein thrombosis, pulmonary embolism, urinary tract infection, wound dehiscence, stroke, and blood transfusion. RESULTS: A total of 251 scapula fractures were identified, with 161 having known fracture locations: 105 glenoid, 20 body, 9 coracoid, and 27 acromial fractures. The rate of any adverse event for all scapular fractures was 2.0%, with no significant difference between anatomic locations (p = 0.79). The overall rates of transfusion, surgical site infection, and return to OR were 0.4%, 0.8%, and 3.98%. Steroid use associated with a significantly increased risk of any adverse event (OR: 55.57, p = 0.038) and outpatient status demonstrated a protective effect on reoperation (OR: 0.11, p = 0.014). There were no significant differences in the rates between groups [transfusion (p = 0.91); surgical site infection (p = 0.17); reoperation (p = 0.85)]. CONCLUSION: Complication rates within thirty days of ORIF for scapula fracture were low. Reoperation was the most common complication, followed by surgical site infection, wound dehiscence, stroke, transfusion, and pneumonia. Steroid use was a risk factor for developing any adverse event, and outpatient status was protective against reoperation. The 30-day complication profile of glenoid, body, coracoid, and acromial fractures was not significantly different. The low complication rates support the relative short-term safety of operative intervention with internal fixation. LEVEL OF EVIDENCE: Level III.

Coracoid strength as an indicator of wing-beat propulsion in birds.

Birds generate a propulsive force by flapping their wings. They use this propulsive force for various locomotion styles, such as aerodynamic flight, wing-paddle swimming and wing-assisted incline running. It is therefore important to reveal the origin of flapping ability in the evolution from theropod dinosaurs to birds. However, there are no quantitative indices to reconstruct the flapping abilities of extinct forms based on their skeletal morphology. This study compares the section modulus of the coracoid relative to body mass among various extant birds to test whether the index is correlated with flapping ability. According to a survey of 220 historical bird specimens representing 209 species, 180 genera, 83 families and 30 orders, the section modulus of the coracoid relative to body mass in non-flapping birds was significantly smaller than that of flapping birds. This indicates that coracoid strength in non-flapping birds is deemphasised, whereas in flapping birds the strength is emphasised to withstand the contractile force produced by powerful flapping muscles, such as the m. pectoralis and m. supracoracoideus. Therefore, the section modulus of the coracoid is expected to be a powerful tool to reveal the origin of powered flight in birds.

Morphometric studies on the appendicular bony skeleton of the ostriches (Struthio Camelus).

BACKGROUND: Morphometric study of the bony elements of the appendicular skeleton in the ostrich was fully described and identified. The appendicular skeleton included the bones of the pectoral girdle, the wing, the pelvic girdle and the pelvic limb. RESULTS: The shoulder girdle of the ostrich included the scapula and coracoid bones. The scapula appeared as a flattened spoon-like structure. The coracoid bone appeared quadrilateral in outline. The mean length of the scapula and coracoid (sternal wing) were 15.00 ± 0.23 and 10.00 ± 0.17 cm, respectively. The wing included the humerus, ulna, radius, radial carpal bone, ulnar carpal bone, carpometacarpus and phalanges of three digits. The mean length of the humerus, radius, and ulna were 33.00 ± 0.46, 10.50 ± 0.40 and 11.50 ± 0.29 cm respectively. The carpometacarpus was formed by the fusion of the distal row of carpal bones and three metacarpal bones. Digits of the wing were three in number; the alular, major and minor digits. Os coxae comprised the ilium, ischium and pubis. Their mean lengths were 36.00 ± 0.82 cm, 32.00 ± 0.20 and 55.00 ± 0.2.9 cm, respectively. The femur was a stout short bone, that appeared shorter than the tibiotarsus. The mean length of the femur, tibiotarsus, and tarsometatarsus were 30.00 ± 0.23, 52.00 ± 0.50 and 46.00 ± 0.28 cm. Tibiotarsus was the longest bone in the pelvic limb. The fibula was a long bone (44.00 ± 0.41 cm) lying along the lateral surface of the tibiotarsus. The tarsometatarsus was a strong long bone formed by the fusion of the metatarsal (II, III, IV) and the distal row of tarsal bones. It was worth mentioning that metatarsal II was externally absent in adults. CONCLUSIONS: In the appendicular skeleton of ostrich, there were special characteristic features that were detected in our study; the clavicle was absent, the coracoid bone was composed of a sternal wing and scapular wing, the ulna was slightly longer in length than the radius. The coupled patellae i.e., the proximal and distal patella were observed; and the ostrich pedal digits were only two; viz., the third (III) and fourth (IV) digits.

Physeal injuries of the clavicle: pediatric counterparts to adult acromioclavicular and sternoclavicular joint separations.

The epiphyses at the medial and lateral ends of the clavicle are small, ossify relatively late, and may not fuse until early adulthood. Because of this unique anatomy, pediatric and young adult injuries that involve the clavicle often differ from the patterns typically seen in older adults. Clavicular trauma that affects the acromioclavicular joint laterally or sternoclavicular joint medially often results in a physeal fracture and as such, can go unrecognized or be mistaken for a joint dislocation. Radiographic assessment is challenging, particularly when the epiphysis is not yet ossified. However, MR imaging allows for visualization of the cartilage, periosteum and perichondrium, and ligaments of the affected joints. Lateral clavicle physeal injuries can be categorized by the Dameron and Rockwood system, the pediatric correlate to the Rockwood classification of adult acromioclavicular joint injuries. Medial clavicle physeal fractures, similar to adult sternoclavicular joint dislocations, may result in anterior or posterior displacement. Because of their great ability to heal and remodel, clavicular physeal fractures respond better to conservative management than true acromioclavicular or sternoclavicular joint dislocations. Therefore, it is essential to recognize the true nature of these injuries, as there are implications for successful treatment and appropriate prognosis.

No correlation exists between coracoid tunnel widening and loss of reduction after arthroscopic acromioclavicular fixation using tightrope system.

PURPOSE: To detect the widening of the tunnel of the coracoid process after arthroscopic fixation of acute acromioclavicular joint (ACJ) dislocation using the TightRope system and its correlation with loss of reduction and functional scores. METHODS: From 2016 to 2018, a prospective study was performed on twenty-three patients with acute grade III-V ACJ dislocation. Arthroscopic TightRope repair of the ACJ was performed. Coracoid tunnel widening was measured by CT, and the coracoclavicular distance was measured on the radiographs immediately postoperatively and at 12 months. The Constant Shoulder Score, Oxford Shoulder Score, Nottingham Clavicle Score and Visual analog scale were used as outcome measures at 12 months. RESULTS: The coracoid tunnel diameter to horizontal coracoid diameter ratio increased from 22.8 ± 3.7% immediately postoperatively to 38.5 ± 5.5% at 12 months (p < 0.001). The coracoclavicular (CC) distance showed an increase from a mean of 10.8 ± 1.7 mm to a mean of 11.8 ± 2.5 at 12 months (p < 0.001). There was no correlation between the increase in the coracoclavicular distance and the patients' functional clinical scores or coracoid tunnel widening. CONCLUSION: Coracoid tunnel widening and radiological loss of reduction occur after arthroscopic fixation of acute ACJ dislocation with the TightRope system. However, they do not correlate with each other or with the functional scores of the patient. LEVEL OF EVIDENCE: Level IV.

Coracoid graft resorption after the Latarjet procedure does not depend on the preoperative glenoid defect.

BACKGROUND: The primary purpose was to compare coracoid graft resorption after the Latarjet procedure in patients without preoperative glenoid bone loss vs. those with more than critical glenoid loss. The secondary purposes were to compare the functional outcomes and to investigate the association of graft position, angle of the screws, preoperative glenoid defect, age at surgery, and smoking status with graft resorption. METHODS: Sixty consecutive patients with recurrent anterior instability were treated by the Latarjet procedure as the index procedure, irrespective of the glenoid bone loss between 2018 and 2021. Fifty-five patients were evaluated via computed tomography scans after a minimum of 1 year after surgery (range: 1-4 years). Twenty-five patients had no prior glenoid defect (No-defect group), 24 patients had preoperative glenoid defects ≥15% (Critical defect group), and 6 patients had glenoid defects between 5% and 15%. The No-defect group (n = 25) was compared with the Critical defect group (n = 24). Multivariate logistical regression was performed to evaluate the association of independent factors with the grade of resorption for all 55 patients in the cohort. RESULTS: Major graft resorption at the level of the superior screw was observed in 72%-84% of patients in the No-defect group (n = 25) and in 75%-83% of patients in the Critical defect group (n = 24) (P = 1, P = 1; no significant difference). No to mild resorption at the level of the inferior screw was observed in 96% of patients in the No-defect group and 100% of patients in the Critical defect group (P = 1; no significant difference). Postoperative Rowe scores (100 [95-100] vs. 100 [95-100]; P = .8) and shoulder subjective value (87 [11] vs. 86 [9]; P = .9) were not significantly different between the 2 groups. None of the independent factors, including the corresponding screw angle, the mediolateral graft positioning, prior glenoid defect, age, and smoking status, were associated with graft resorption in multivariate logistical regression. CONCLUSIONS: Graft resorption after the Latarjet procedure does not depend on the preoperative glenoid defect. The coracoid graft may be mostly resorbed around the superior screw but mildly or none at the level of the inferior screw, but this graft resorption is not dependent on the smoking status, age, prior glenoid defect, mediolateral graft positioning, and the angle of the screws.

A biomechanical analysis of double-screw, double-button, and screw-button fixation constructs in patient-specific instrument-guided Latarjet procedure.

BACKGROUND: The Latarjet coracoid transfer procedure reliably stabilizes the glenohumeral joint for shoulder instability. However, complications such as graft osteolysis, nonunion and fracture continue to affect patient clinical outcomes. The double-screw (SS) construct is regarded as the gold standard method of fixation. SS constructs are associated with graft osteolysis. More recently, a double-button technique (BB) has been suggested to minimize graft-related complications. However, BB constructs are associated with fibrous nonunion. To mitigate this risk, a single screw combined with a single button (SB) construct has been proposed. It is thought that this technique incorporates the strength of the SS construct and allows micromotion superiorly to mitigate stress shielding-related graft osteolysis. AIMS: The primary aim of this study was to compare the failure load of SS, BB, and SB constructs under a standardized biomechanical loading protocol. The secondary aim was to characterize the displacement of each construct throughout testing. METHODS: Computed tomography scans of 20 matched-pair cadaveric scapulae were performed. Specimens were harvested and dissected free of soft tissue. SS and BB techniques were randomly assigned to specimens for matched-pair comparison with SB trials. A patient-specific instrument (PSI)-guided Latarjet procedure was performed on each scapula. Specimens were tested using a uniaxial mechanical testing device under cyclic loading (100 cycles, 1 Hz, 200 N/s) followed by a load-to-failure protocol (0.5 mm/s). Construct failure was defined by graft fracture, screw avulsion, and/or graft displacement of more than 5 mm. RESULTS: Forty scapulae from 20 fresh frozen cadavers with a mean age of 69.3 years underwent testing. On average, SS constructs failed at 537.8 N (SD 296.8), whereas BB constructs failed at 135.1 N (SD 71.4). SB constructs required a significantly greater load to fail compared with BB constructs (283.5 N, SD 162.8, P = .039). Additionally, SS (1.9 mm, IQR 0.87) had a significantly lower maximum total graft displacement during the cyclic loading protocol compared with SB (3.8 mm, IQR 2.4, P = .007) and BB (7.4 mm, IQR 3.1, P < .001) constructs. CONCLUSION: These findings support the potential of the SB fixation technique as a viable alternative to SS and BB constructs. Clinically, the SB technique could reduce the incidence of loading-related graft complications seen in the first 3 months of BB Latarjet cases. The study is limited to time-specific results and does not account for bone union or osteolysis.

Treatment of coracoid process fractures combined with acromioclavicular joint dislocation using clavicular hook plate.

BACKGROUND: The injury mechanism of acromioclavicular (AC) dislocation combined with coracoid process (CP) fracture is not clear, and there is no consensus on its treatment. This study was performed to evaluate the diagnosis of CP fractures combined with AC dislocation and the effectiveness of operative treatment using a clavicular hook plate. METHODS: Eighteen patients with CP fractures combined with AC dislocation were treated with a clavicular hook plate from May 2012 to June 2021. The patients comprised 10 male and 8 female patients with an average age of 38 years (range, 16-54 years). The injury was caused by falling in 15 patients, traffic accidents in 2 patients, and falling from a height in 1 patient. The Eyres type of CP fracture was type II in 1 patient, type III in 11 patients, type IV in 3 patients, and type V in 3 patients. The Ogawa type of CP fracture was type I in 17 patients and type II in 1 patient. The Rockwood type of AC dislocation was type V in 1 patient, variation type III in 15 patients, and variation type V in 2 patients. The interval from injury to the operation was 3 days (range, 1-7 days). Postoperative complications and CP fracture healing were recorded. Functional assessment at the last follow-up was performed by an independent reviewer using the Constant score and visual analog scale score. RESULTS: All 18 patients were followed up for a mean period of 49 months (range, 12-123 months). Nine patients had acromion osteolysis and 3 patients had CP fracture nonunion (Eyres type II, III, and V in 1 patient each); however, no patients developed shoulder pain, incision infection, limitation of shoulder movement, clinical symptoms of subcoracoid impingement, or AC dislocation relapse. At the last follow-up, the mean Constant score was 99 (range, 94-100). CONCLUSIONS: The possibility of CP fracture should be considered in patients with AC dislocation to avoid a missed diagnosis. Fixation with a clavicular hook plate is a feasible treatment for CP fracture combined with AC dislocation and provides a satisfactory outcome. CP fracture healing may be related to the fracture morphology.

Bone formation of the coracoid bone graft after the Bristow procedure assessed using three-dimensional computed tomography.

BACKGROUND: The Bristow procedure has been shown to be a reliable method to prevent recurrent anterior shoulder instability by compensating for glenoid bone loss and producing the sling effect. The degree of postoperative morphological change in the coracoid bone graft is speculated to influence glenohumeral joint stability; however, the details of these changes after the Bristow procedure remain unknown. This study was performed to quantify the postoperative change in the coracoid bone graft volume as assessed by three-dimensional computed tomography (3D-CT). METHODS: The Bristow procedure was performed on 17 shoulders in 17 patients from August 2018 to January 2020. All patients were men, and their mean age at surgery was 17.9 years. The mean follow-up duration was 21.4 months. Within the first week after the operation (Time 0) and at the final follow-up, 3D-CT was used to determine the total coracoid bone graft volume. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) shoulder score, the University of California Los Angeles (UCLA) shoulder score, and the Western Ontario Shoulder Instability Index (WOSI). RESULTS: The mean volume of the total coracoid bone graft was 1.26 ± 0.29 cm3 at Time 0 and 1.90 ± 0.36 cm3 at the final follow-up (p < 0.0001). The mean JOA score, UCLA score, and WOSI were significantly better at the final follow-up than preoperatively (p < 0.001). No postoperative infection, neurovascular injury, or recurrent instability of the glenohumeral joint occurred. CONCLUSIONS: In the Bristow procedure, the volume of the total coracoid bone graft as shown by 3D-CT was significantly greater at the final follow-up than at Time 0, and bone formation of the coracoid bone graft was found after the Bristow procedure.

Bone tunnel placement influences shear stresses at the coracoid process after coracoclavicular ligament reconstruction: a finite element study and radiological analysis.

INTRODUCTION: Coracoid fractures after arthroscopic treatment of acromioclavicular (AC) joint separations lead to poor clinical outcomes. In this study, different configurations of bone tunnels in the lateral clavicle and coracoid were examined concerning the amount of stress induced in the coracoid. METHODS: An authentic 3D finite element model of an ac joint was established. Three 2.4 mm bone tunnels were inserted in the lateral clavicle, which were situated above, medially and laterally of the coracoid. Then, two 2.4 mm bone tunnels were inserted in the latter, each simulating a proximal and a distal suture button position. Von Mises stress analyses were performed to evaluate the amount of stress caused in the coracoid process by the different configurations. Then, a clinical series of radiographs was examined, the placement of the clavicle drill hole was analyzed and the number of dangerous configurations was recorded. RESULTS: The safest configuration was a proximal tunnel in the coracoid combined with a lateral bone tunnel in the clavicle, leading to an oblique traction at the coracoid. A distal bone tunnel in the coracoid and perpendicular traction as well as a proximal tunnel in the coracoid with medial traction caused the highest stresses. Anatomical placement of the clavicle drill hole does lead to configurations with smaller stresses. CONCLUSION: The bone tunnel placement with the smallest amount of shear stresses was found when the traction of the suture button was directed slightly lateral, towards the AC joint. Anatomical placement of the clavicle drill hole alone was not sufficient in preventing dangerous configurations. LEVEL OF EVIDENCE: Controlled laboratory study.

The anatomy and variation of the coracoid attachment of the subclavius muscle in humans.

The functions of the subclavius muscle (SM) are described as stabilization of the sternoclavicular joint (SCJ) and resisting elevation of the lateral end of the clavicle. During systematic cadaveric dissections, we observed additional fibrous structures, previously described as variants of the anatomy, extending from the SM and inserting into the coracoid process (CP). Due to the high incidence of these structures in our dissections, we hypothesized that the attachment at the CP is more common than appreciated and that, as a corollary, the function of the SM was (or has been) more complex than simply depressing the clavicle and generating stability at the SCJ. For our investigation, fifty-two upper extremities of 26 human cadavers were dissected. The SM was demonstrated from costal to clavicular attachment. We documented additional fibrous structures apparently derived from the SM inserting into the CP. Measurements of the length of the SM, the length of its attachment, and the length of the clavicle were taken in situ, with the specimens supine and the upper extremity in the anatomical position. Variations in the anatomy of the SM and its coracoidal attachment were recorded, and potential correlations were investigated. For documentation purposes photographs and video sequences of passive motion of the shoulder girdle of the specimens were taken. In 49 of the 52 specimens we found additional fibrous structures passing from the SM to the CP. We differentiated three types: (1) a strong cord-like structure; (2) a small or thin cord-like structure or structures; and (3) a planar twisted sheet-like structure. The SM and its extension to the CP appears to contribute to a 'functional scapular suspension system' together with the other muscles enveloped by the clavipectoral fascia (pectoralis minor, coracobrachialis and the short head of the biceps brachii). This system assists in the control of the position of the scapula in relation to the thorax, particularly in elevated positions of the upper extremity. We speculate that the differentiation of the fibrous structure depends on the functional demands of the individual. Level of Evidence: Basic science study.

Transfer of the coracoid and conjoined tendon for failed, unstable, short clavicle following excessive outer clavicle resection.

Nineteen patients presented with an unsightly deformity of the shoulder, pain or discomfort at the medial scapular border, pseudo nonparalytic scapular winging, and thoracic outlet symptoms after excessive resection of the clavicle for either complete acromioclavicular separation or displaced fracture of the outer clavicle, which allows the scapula and shoulder to rotate anteriorly and inferiorly on the chest creating traction on the medial scapular muscles and the brachial plexus resulting in pseudo nonparalytic winging and thoracic outlet symptoms. RESULTS: All underwent transfer of the coracoid process with the attached conjoined tendon to the end of the clavicle, restoring length and alignment. Eighteen patients were evaluated at a mean of 13.3 years. Seventeen had resolution of symptoms, restored alignment of the clavicle with the shoulder, improved appearance, healed transfer, and were pleased with the outcome. One patient was lost to follow-up but was considered a failure at his last visit. In a second patient, the transfer healed in a tilted position and the patient was dissatisfied with the appearance but otherwise had resolution of his symptoms. The mean American Shoulder and Elbow Surgeons Outcome Score improved from 53.2 preoperatively to 87.4 postoperatively (P < .02). CONCLUSION: This is the first report of using this transfer to restore length and alignment of an excessively short, unstable clavicle. The transfer succeeded in improving the appearance and symptoms in this complication of an excessively short, unstable clavicle.

Scapula revisited: new features identified and denoted by terms using consensus method of Delphi and taxonomy panel to be implemented in radiologic and surgical practice.

BACKGROUND: The scapular structures that have not yet been assigned anatomic terms generate a challenge in clinical diagnostics and surgical application, as well as in scientific observation. The aim of this study was to solve the lack in terminology concerning the scapula and the scapular region. METHODS: Observation and description of 29 structures were carried out on both dry scapulae and radiographs of the shoulder joint. In addition, several terms commonly encountered throughout the literature concerning the scapula were revised. A degree of consensus was reached by using the Delphi method surveying the opinions of 21 invited experts in the field. Taxonomy panels and etymology of anatomic terminology were considered in the generation of the proposed terms. RESULTS: The scapula was redefined as a lamina with projecting processes, and several landmarks demarcating certain newly defined topographic spaces were highlighted via 2 rounds of Delphi systematic voting and discussion. The overall level of the peer nominees' consensus was high. Few terms received a neutral opinion. CONCLUSIONS: This study communicates a proposal of 16 new terms defining grossly visible structures on the scapula that have not yet been described by officially recognized terms, including a call to unify 13 previously contributed terms that have not been codified and are often used interchangeably within different surgical and scientific fields. Incorporating these terms into the anatomic nomenclature would facilitate communication accuracy and eliminate ambiguity among clinicians, surgeons, and anatomists.

Morphology of the coracoid process as a predictor of articular-side tear at the upper border of the subscapularis.

BACKGROUND: Articular-side tear at the upper border of the subscapularis (SSC-AST) is often detected during shoulder arthroscopic surgery, although its exact pathology remains unknown. The purpose of this study was to investigate the correlation between various characteristics of the coracoid process, including classification of the morphology of the coracoid process tip, and the presence of SSC-AST. METHODS: This retrospective, case-controlled study included patients who underwent arthroscopic subacromial decompression with or without rotator cuff repair between January 2018 and September 2021. A total of 130 shoulders in 124 patients, including 77 male and 53 female shoulders (mean age at surgery, 64 years [range, 39-88 years]), were included in this study. Three-dimensional (3D) computed tomography examination was performed preoperatively, and the following indices were measured: coracoid proximal length, coracoid distal length, coracoid angle, coracoglenoid angle, offset of the coracoid process and glenoid (anterior, lateral, and superior offset), and coracoid base angle. The morphology of the tip of the coracoid process was classified into 3 types according to 3D reconstructed views: flat type, round type, and beak type. The presence of SSC-AST was intraoperatively evaluated arthroscopically via a posterior glenohumeral portal. Morphologic risk factors for SSC-AST were evaluated between SSC-AST cases (group T) and non-SSC-AST cases (group N) by multivariable logistic analysis. In addition, the correlation between the incidence of SSC-AST and classification of the tip of the coracoid process was analyzed. RESULTS: SSC-AST was present in 53 shoulders (40.8%). Group T patients were significantly older than group N patients (68.4 ± 10.0 years vs. 61.5 ± 11.8 years, P < .001). No sex difference was detected between the 2 groups (28 male and 25 female shoulders in group T vs. 49 male and 28 female shoulders in group N, P = .28). Multivariate analysis of morphologic parameters between the 2 groups detected a smaller superior offset as a risk factor for SSC-AST (odds ratio, 0.91; 95% confidence interval, 0.84-0.98; P = .01). No significant differences were found in the other parameters. Regarding classification of the tip of the coracoid process, round- and beak-type coracoid tips had a significantly higher rate of SSC-AST than flat-type tips (flat type, 21.8%; round type, 64.7%; and beak type, 46.3%) (P < .001). CONCLUSIONS: Evaluation of the correlation between the morphology of the coracoid process on 3D computed tomography and the presence of SSC-AST visualized during arthroscopy indicated a significant association between SSC-AST and the morphology of the coracoid process.