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An anatomic study of the coracoid process as it relates to bone transfer procedures
J Shoulder Elbow Surg (2011) 20, 497-501
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An anatomic study of the coracoid process as it relates to bone transfer procedures Christopher M. Dolan, MD, Sanaz Hariri, MD, Nathan D. Hart, MD, Timothy R. McAdams, MD* Department of Orthopaedics and Division of Sports Medicine, Stanford University, Palo Alto, CA, USA Introduction: The Latarjet and Bristow procedures address recurrent anterior shoulder instability in the context of a significant bony defect. However, the bony and soft tissue anatomy of the coracoid as they relate to coracoid transfer procedures has not yet been defined. The purpose of this study was to describe the soft tissue attachments of the coracoid as they relate to the bony anatomy and to define the average amount of bone available for use in coracoid transfer. Methods: Ten paired fresh frozen shoulders from deceased donors were dissected, exposing the coracoid, lateral clavicle, and acromion, along with the coracoid soft tissue attachments. The bony dimensions of the coracoid and the locations and sizes of the soft tissue footprints of the coracoid were measured. Results: The mean maximum length of the coracoid available for transfer (ie, distance from the coracoid tip to the anterior border of the coracoclavicular ligament) was 28.5 mm. The mean distance from the coracoid tip to the anterior pectoralis minor was 4.6 mm, to the posterior pectoralis minor was 17.7 mm, to the anterior coracoacromial ligament was 7.8 mm, and to the posterior coracoacromial ligament was 25.7 mm. Conclusion: Average dimensions of the bony coracoid and average locations and sizes of coracoid soft tissue footprints are provided. This anatomic description of the coracoid bony anatomy and its soft tissue insertions allows surgeons to correlate the location of their coracoid osteotomy with the soft tissue implications of the coracoid transfer as the native anatomy is manipulated in these nonanatomic procedures. Level of evidence: Basic Science Study, Anatomic Study. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Coracoid; anatomy; Latarjet; Bristow; coracoid transfer
A significant bony defect (defined as an engaging Hill-Sachs lesion or an inverted-pear glenoid) in the setting of anterior shoulder instability compromises the effectiveness of arthroscopic Bankart repairs. In their study of 194 arthroscopic Bankart repairs, Burkhart and De Beer2 reported a 4% recurrence rate in patients without significant bony defects compared with a 67% recurrence rate in *Reprint requests: Timothy McAdams, MD, 450 Broadway St MC:6342, Redwood City, CA 94063. E-mail address: [email protected] (T.R. McAdams).
those with a significant bony defect (7% vs 89% in contact athletes, respectively). Tauber et al16 reported that 51% of their patients presenting with recurrent anterior instability after surgical repair had a bony Bankart lesion that was >2 mm thick. In a cadaveric study, shoulders with an osseous defect involving at least 21% of the glenoid width were still unstable after a Bankart repair.5 A coracoid transfer can address anterior instability in the setting of a significant glenohumeral bone defect. In 1958, Helfet4 described the Bristow procedure, transferring the terminal ‘‘half-inch’’ of the coracoid
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2010.08.015
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Figure 1 View of the superior aspect of the coracoid. The numbers correlate to Table I: 1, coracoid length (distance from tip to base); 2, coracoid tip width; 4, distance from the coracoid tip or base to the coracoid midpoint; 5, midpoint width.
process (onto which the conjoint tendon attaches) to the scapular neck just medial to the anteroinferior edge of the glenoid rim. Helfet described making the bony cut immediately distal to the insertion of the pectoralis minor. In May’s modified Bristow, the osteotomy is performed just proximal to the coracobrachialis origin.11,12,15 An arthroscopic Bristow has also been described, involving transfer of a 15-mm coracoid fragment.1 In all of these Bristow procedures, the coracoid osteotomy is performed distal to the pectoralis minor origin. The Latarjet procedure involves transfer of a larger piece of the coracoid.8,9 The pectoralis minor is detached from the coracoid, and the bony cut is made proximal to the angle/elbow of the coracoid (at the junction between the horizontal and vertical parts), just distal to the coracoclavicular (CC) ligament insertions.2 The description by Lafosse et al7 of an arthroscopic Latarjet involves a coracoid osteotomy 2 to 2.5 cm proximal to the coracoid tip, also at the coracoid elbow. The Bristow and Latarjet technique papers describe the osteotomy site either as an estimated distance from the coracoid tip or in relationship to an anatomic structure (ie, the coracoid elbow or proximal/distal to a soft tissue attachment). The purpose of this study was (1) to describe the soft tissue attachments onto the coracoid as they relate to the bony anatomy and (2) to define the average amount of bone available for use in a coracoid transfer. Some of these measurements have been reported in other articles, but to our knowledge, this is the first study defining both the bony and soft tissue anatomy of the coracoid as it relates to coracoid transfer surgeries. These data may be beneficial in preoperative planning and intraoperative decision making
for coracoid osteotomy and transfer, in particular, as it elucidates the soft tissue implications of various coracoid osteotomy sites.
Materials and methods This anatomic laboratory study did not require Investigational Review Board or Ethical Committee approval. The study used 10 fresh frozen shoulders from deceased donors (3 paired men, 2 paired women) who were an average age of 83.8 years (range, 81-86 years). The skin, subcutaneous tissue, deltoid, and overlying soft tissue were removed, exposing the coracoid, lateral clavicle, and acromion. The footprints of each ligament and tendon attaching to the coracoid were preserved. The footprint insertion areas were clearly marked circumferentially with a pen while the ligament/tendon footprint was intact; the ligament/tendon was then incised leaving a short stump. Measurements were independently recorded by 2 of the authors, blinded to each others’ measurements, using a digital caliper (Mitutoyo America Corp, Aurora, IL) accurate to 0.1 mm. The average of the 2 measurements are reported. The following bony dimensions of the coracoid were measured: (1) distance from the coracoid tip (hereafter termed ‘‘tip’’) to the coracoid base (length), (2) tip width, (3) tip height, (4) distance from the coracoid tip or base to the coracoid midpoint (hereafter termed ‘‘midpoint’’), (5) midpoint width, and (6) midpoint height (Figures 1 and 2) The following soft tissue footprints on the coracoid were studied: pectoralis minor, coracoacromial (CA) ligament, trapezoid coracoclavicular (CC) ligament, and conjoint tendon. The distance between these soft tissue footprints and their distance from the bony landmarks above was measured (Figure 3) The distance from the coracoid tip to the anterior CC ligaments was measured. This bony area anterior to the CC ligaments is
An anatomic study of the coracoid
Figure 2 View of the lateral aspect of the coracoid. The numbers correlate to Table I: 1, coracoid length (distance from tip to base); 3, coracoid tip height; 4, distance from the coracoid tip or base to the coracoid midpoint; 6, midpoint height. often described as the ‘‘knee’’ or ‘‘elbow’’ of the coracoid. The dimensions and location of the trapezoid CC ligament were measured rather than the conoid CC ligament because the trapezoid footprint is more anterior on the coracoid. Given that the length of coracoid available for transfer is the bone span from the coracoid tip to the most anterior CC ligament footprint, the trapezoid is the more clinically relevant CC ligament in osteotomy and transfer of the coracoid.
Results The anatomic dimensions of the coracoid bony anatomy are reported in Table I, which correlates to Figures 1 and 2. The mean coracoid length (1) was 45.6 4.2 mm, the mean coracoid tip width (2) was 18.3 1.8 mm, and the mean coracoid tip height (3) was 11.5 0.9 mm. The maximum length of the coracoid available for transfer (ie, the bone segment between the tip of the coracoid and the anterior extent of the trapezoid CC ligament or tip to ‘‘knee’’ or ‘‘elbow’’ of the coracoid) was 28.5 5.1 mm. The midpoint of the coracoid (4) was 22.8 2.1 mm from the tip/base. The midpoint mean width (5) was 16.1 2.3 mm, and the midpoint mean height (6) was 13.5 1.6 mm. The dimensions of and relationships between the soft tissue coracoid insertions on the coracoid are reported in Table II, which correlates to Figure 3. The mean distance from the coracoid tip to the anterior pectoralis minor (A) was 4.6 2.9 mm and to the posterior pectoralis minor (B) was 17.7 4.2 mm. The mean pectoralis minor footprint anteroposterior width (C) was 11.8 2.8 mm. The mean distance from the coracoid tip to the anterior CA ligament (D) was 7.8 3.6 mm and to the posterior CA ligament (E) was 25.7 4.4 mm. The CC ligament footprint anteroposterior width (F) was 17.9 3.6 mm. The mean
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Figure 3 View of the superior aspect of the coracoid with soft tissue footprints marked. Letters correlate to Table II: A, coracoid tip to anterior pectoralis minor; B, coracoid tip to posterior pectoralis minor; C, pectoralis minor insertion anteroposterior width; D, coracoid tip to anterior coracoacromial (CA) ligament; E, coracoid tip to posterior CA ligament; F, CA ligament insertion anteroposterior width; G, coracoid tip to anterior coracoclavicular (C-C) trapezoid ligament; H, posterior CA ligament to anterior C-C ligament.
distance from the coracoid tip to the anterior CC ligament (G) was 28.5 5.1 mm. The mean distance from the posterior extent of the CA ligament footprint to the anterior extent of the CC ligament footprint (H) was 2.8 6.0 mm. The posterior extent of the CA ligament was proximal to the anterior extent of the trapezoid CC ligament in both shoulders of 1 female specimen and only a single shoulder in 1 male specimen. The mean pectoralis minor footprint height (I) was 3.7 0.8 mm. The mean width of the conjoint tendon footprint (J) was 15.5 1.8 mm.
Discussion In the context of glenohumeral bone loss, coracoid transfer procedures have resulted in a lower dislocation recurrence rate compared with soft tissue procedures. Wellman et al17 demonstrated in a biomechanical study that the Latarjet procedure significantly reduced humeral head translation by 354% at 30 of abduction and by 374% at 60 of abduction. Using a modified Latarjet, Burkhart et al3 reduced their recurrent dislocation rate from 67% to 5% in patients with significant bone defects. The current literature does not provide a comprehensive report of the amount of bone available for transfer and the soft tissue implications of various coracoid osteotomy sites. The aim of our study was to define the bony and soft tissue attachment anatomy of the coracoid to assist in more informed surgical planning and execution of coracoid transfers. Other anatomic studies have defined various pieces of this data set as they relate to other procedures, namely, CC ligament reconstruction for acromioclavicular
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Table I
Bony anatomy dimensions of the coracoid
Variable 1. 2. 3. 4. 5. 6.
Mean (mm)
Coracoid length Tip width Tip height Distance from tip/base to midpoint Midpoint width Midpoint height
45.6 18.3 11.5 22.8 16.1 13.5
SD (mm) 4.2 1.8 0.9 2.1 2.3 1.6
Range Min (mm)
Max (mm)
40.8 16.1 10.0 20.4 12.1 11.7
53.0 22.2 12.6 26.5 18.9 17.3
Min, minimum value; Max, maximum value; SD, standard deviation.
Table II
Dimensions of and relationships between the soft-tissue footprints on the coracoid)
Variable Pectoralis minor A. Tip to anterior pectoralis minor B. Tip to posterior pectoralis minor C. Pectoralis minor insertion AP width Coracoacromial (CA) ligament (lig) D. Tip to anterior CA lig E. Tip to posterior CA lig F. CA lig insertion AP width (calc) Coracoclavicular (CC) trapezoid ligament G. Tip to anterior CC lig H. Posterior CA lig to anterior CC lig (calc) I. Height of pectoralis minor insertion Conjoint tendon J. Width of conjoint footprint
Mean (mm)
SD (mm)
Range Min (mm)
Max (mm)
4.6 17.7 11.8
2.9 4.2 2.8
0.0 11.5 6.8
8.8 25.7 16.7
7.8 25.7 17.9
3.6 4.4 3.6
2.9 16.3 13.4
13.8 29.9 24.5
28.5 2.8 3.7
5.1 6.0 0.8
22.9 e6.2 2.5
36.8 9.3 4.9
15.5
1.8
11.4
18.2
AP, anteroposterior; Max, maximum value; Min, minimum value; SD, standard deviation. ) Of note, the posterior insertion of the coracoacromial (CA) ligament was proximal to the trapezoid coracoclavicular (CC) ligament in both shoulders of a female specimen and in 1 shoulder of a male specimen.
instability,13-14 but to our knowledge, none has investigated the coracoid soft tissue insertion sites and bony anatomy as it relates to coracoid transfers. Measurements of total coracoid length in the literature vary: 43.1 2.2 mm (Salzmann et al,14 23 fresh cadavers), 45.2 4.1 mm (Rios et al,13 120 dry osteology cadavers), and 45.6 4.2 mm (our study, 10 fresh frozen cadavers). However, the more relevant anatomic measurement for the Latarjet procedure is the maximum length of coracoid that can be transferred, defined as the distance from the coracoid tip to the anterior extent of the CC ligament. The CC ligaments must be preserved to maintain acromioclavicular stability. We found the mean amount of coracoid available for transfer (ie, distance from the coracoid tip to the anterior CC ligament) was 28.5 5.1 mm. Using the data from Salzmann et al,14 the mean coracoid length available for transfer is 23.5 2.1 mm [(center of trapezoid to tip) e (footprint trapezoid AP/2)].13 Other studies have also measured the mean coracoid tip and base width and height. The reported mean coracoid tip widths are 13.6 2.1 mm (Salzman et al14), 15.9 2.2 mm (Lo et al,10 5 fresh frozen cadavers), and 18.3 1.8 mm
(this study). The reported mean coracoid tip heights are 8.2 1.0 mm (Salzman et al14), 10.4 1.4 mm (Lo et al10), and 11.5 0.9 mm (this study). As expected, men have a significantly longer coracoid, greater coracoid tip width and height, and greater coracoid base width and height than women.13,14 Kesmezacar et al6 reported that the CA ligament has a varied and often broad insertion onto the coracoid. Similarly, we found that in 3 cadavers, the CA ligament’s footprint overlapped with the CC ligament footprint on the coracoid. Therefore, care must be taken when releasing the CA ligament during coracoid transfers so that the CC ligaments and coracoclavicular biomechanics are not compromised.
Conclusions The purpose of this study was to assist surgeons during preoperative planning and intraoperative decision making when performing a Bristow or Latarjet procedure to address recurrent anterior glenohumeral
An anatomic study of the coracoid instability in the context of glenohumeral bone loss. This anatomic description of the coracoid bony anatomy and its soft tissue insertions allows surgeons to correlate the location of their coracoid osteotomy with the soft tissue implications of the coracoid transfer as the native anatomy is manipulated in these nonanatomic procedures. Future biomechanical research can establish an algorithm for the minimum amount of coracoid required to achieve stability according to the degree of glenoid bone loss. The data reported in our study would help define what tendons and ligaments are most likely affected in each scenario.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article. No financial biases exist for these authors.
References 1. Boileau P, Bicknell RT, El Fegoun AB, Chuinard C. Arthroscopic Bristow procedure for anterior instability in shoulders with a stretched or deficient capsule: the ‘‘belt-and-suspenders’’ operative technique and preliminary results. Arthroscopy 2007;23:593-601. doi:10.1016/j. arthro.2007.03.096 2. Burkhart SS, De Beer JF. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: significance of the inverted-pear glenoid and the humeral engaging HillSachs lesion. Arthroscopy 2000;16:677-94. 3. Burkhart SS, De Beer JF, Barth JR, Cresswell T, Roberts C, Richards DP. Results of modified Latarjet reconstruction in patients with anteroinferior instability and significant bone loss. Arthroscopy 2007;23:1033-41. doi:10.1016/j.arthro.2007.08.009
501 4. Helfet AJ. Coracoid transplantation for recurring dislocation of the shoulder. J Bone Joint Surg Br 1958;40:198-202. 5. Itoi E, Lee SB, Berglund LJ, Berge LL, An KN. The effect of a glenoid defect on anteroinferior stability of the shoulder after Bankart repair: a cadaveric study. J Bone Joint Surg Am 2000;82:35-46. 6. Kesmezacar H, Akgun I, Ogut T, Gokay S, Uzun I. The coracoacromial ligament: the morphology and relation to rotator cuff pathology. J Shoulder Elbow Surg 2008;17:182-8. doi:10.1016/j.jse. 2007.05.015 7. Lafosse L, Lejeune E, Bouchard A, Kakuda C, Gobezie R, Kochhar T. The arthroscopic Latarjet procedure for the treatment of anterior shoulder instability. Arthroscopy 2007;23:1242.e1-5. doi:10.1016/j. arthro.2007.06.008 8. Latarjet M. Surgical technics in the treatment of recurrent dislocation of the shoulder (antero-internal). Lyon Chir 1965;61:313-8. 9. Latarjet M. Technic of coracoid preglenoid arthroereisis in the treatment of recurrent dislocation of the shoulder. Lyon Chir 1958;54:604-7. 10. Lo IK, Burkhart SS, Parten PM. Surgery about the coracoid: neurovascular structures at risk. Arthroscopy 2004;20:591-5. doi:10.1016/j. arthro.2004.04.060 11. Lombardo SJ, Kerlan RK, Jobe FW, Carter VS, Blazina ME, Shields CL Jr. The modified Bristow procedure for recurrent dislocation of the shoulder. J Bone Joint Surg Am 1976;58:256-61. 12. May VR Jr. A modified Bristow operation for anterior recurrent dislocation of the shoulder. J Bone Joint Surg Am 1970;52:1010-6. 13. Rios CG, Arciero RA, Mazzocca AD. Anatomy of the clavicle and coracoid process for reconstruction of the coracoclavicular ligaments. Am J Sports Med 2007;35:811-7. doi:10.1177/ 0363546506297536 14. Salzmann GM, Paul J, Sandmann GH, Imhoff AB, Schottle PB. The coracoidal insertion of the coracoclavicular ligaments: an anatomic study. Am J Sports Med 2008;36:2392-7. doi:10.1177/ 0363546508322887 15. Schroder DT, Provencher MT, Mologne TS, Muldoon MP, Cox JS. The modified Bristow procedure for anterior shoulder instability: 26year outcomes in Naval Academy midshipmen. Am J Sports Med 2006;34:778-86. doi:10.1177/0363546505282618 16. Tauber M, Resch H, Forstner R, Raffl M, Schauer J. Reasons for failure after surgical repair of anterior shoulder instability. J Shoulder Elbow Surg 2004;13:279-85. doi:10.1016/j.jse.2004.01.008 17. Wellmann M, Petersen W, Zantop T, Herbort M, Kobbe P, Raschke MJ, et al. Open shoulder repair of osseous glenoid defects: biomechanical effectiveness of the Latarjet procedure versus a contoured structural bone graft. Am J Sports Med 2009;37:87-94. doi:10. 1177/0363546508326714
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An anatomic study of the coracoid process as it relates to bone transfer procedures Christopher M. Dolan, MD, Sanaz Hariri, MD, Nathan D. Hart, MD, Timothy R. McAdams, MD* Department of Orthopaedics and Division of Sports Medicine, Stanford University, Palo Alto, CA, USA Introduction: The Latarjet and Bristow procedures address recurrent anterior shoulder instability in the context of a significant bony defect. However, the bony and soft tissue anatomy of the coracoid as they relate to coracoid transfer procedures has not yet been defined. The purpose of this study was to describe the soft tissue attachments of the coracoid as they relate to the bony anatomy and to define the average amount of bone available for use in coracoid transfer. Methods: Ten paired fresh frozen shoulders from deceased donors were dissected, exposing the coracoid, lateral clavicle, and acromion, along with the coracoid soft tissue attachments. The bony dimensions of the coracoid and the locations and sizes of the soft tissue footprints of the coracoid were measured. Results: The mean maximum length of the coracoid available for transfer (ie, distance from the coracoid tip to the anterior border of the coracoclavicular ligament) was 28.5 mm. The mean distance from the coracoid tip to the anterior pectoralis minor was 4.6 mm, to the posterior pectoralis minor was 17.7 mm, to the anterior coracoacromial ligament was 7.8 mm, and to the posterior coracoacromial ligament was 25.7 mm. Conclusion: Average dimensions of the bony coracoid and average locations and sizes of coracoid soft tissue footprints are provided. This anatomic description of the coracoid bony anatomy and its soft tissue insertions allows surgeons to correlate the location of their coracoid osteotomy with the soft tissue implications of the coracoid transfer as the native anatomy is manipulated in these nonanatomic procedures. Level of evidence: Basic Science Study, Anatomic Study. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Coracoid; anatomy; Latarjet; Bristow; coracoid transfer
A significant bony defect (defined as an engaging Hill-Sachs lesion or an inverted-pear glenoid) in the setting of anterior shoulder instability compromises the effectiveness of arthroscopic Bankart repairs. In their study of 194 arthroscopic Bankart repairs, Burkhart and De Beer2 reported a 4% recurrence rate in patients without significant bony defects compared with a 67% recurrence rate in *Reprint requests: Timothy McAdams, MD, 450 Broadway St MC:6342, Redwood City, CA 94063. E-mail address: [email protected] (T.R. McAdams).
those with a significant bony defect (7% vs 89% in contact athletes, respectively). Tauber et al16 reported that 51% of their patients presenting with recurrent anterior instability after surgical repair had a bony Bankart lesion that was >2 mm thick. In a cadaveric study, shoulders with an osseous defect involving at least 21% of the glenoid width were still unstable after a Bankart repair.5 A coracoid transfer can address anterior instability in the setting of a significant glenohumeral bone defect. In 1958, Helfet4 described the Bristow procedure, transferring the terminal ‘‘half-inch’’ of the coracoid
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2010.08.015
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Figure 1 View of the superior aspect of the coracoid. The numbers correlate to Table I: 1, coracoid length (distance from tip to base); 2, coracoid tip width; 4, distance from the coracoid tip or base to the coracoid midpoint; 5, midpoint width.
process (onto which the conjoint tendon attaches) to the scapular neck just medial to the anteroinferior edge of the glenoid rim. Helfet described making the bony cut immediately distal to the insertion of the pectoralis minor. In May’s modified Bristow, the osteotomy is performed just proximal to the coracobrachialis origin.11,12,15 An arthroscopic Bristow has also been described, involving transfer of a 15-mm coracoid fragment.1 In all of these Bristow procedures, the coracoid osteotomy is performed distal to the pectoralis minor origin. The Latarjet procedure involves transfer of a larger piece of the coracoid.8,9 The pectoralis minor is detached from the coracoid, and the bony cut is made proximal to the angle/elbow of the coracoid (at the junction between the horizontal and vertical parts), just distal to the coracoclavicular (CC) ligament insertions.2 The description by Lafosse et al7 of an arthroscopic Latarjet involves a coracoid osteotomy 2 to 2.5 cm proximal to the coracoid tip, also at the coracoid elbow. The Bristow and Latarjet technique papers describe the osteotomy site either as an estimated distance from the coracoid tip or in relationship to an anatomic structure (ie, the coracoid elbow or proximal/distal to a soft tissue attachment). The purpose of this study was (1) to describe the soft tissue attachments onto the coracoid as they relate to the bony anatomy and (2) to define the average amount of bone available for use in a coracoid transfer. Some of these measurements have been reported in other articles, but to our knowledge, this is the first study defining both the bony and soft tissue anatomy of the coracoid as it relates to coracoid transfer surgeries. These data may be beneficial in preoperative planning and intraoperative decision making
for coracoid osteotomy and transfer, in particular, as it elucidates the soft tissue implications of various coracoid osteotomy sites.
Materials and methods This anatomic laboratory study did not require Investigational Review Board or Ethical Committee approval. The study used 10 fresh frozen shoulders from deceased donors (3 paired men, 2 paired women) who were an average age of 83.8 years (range, 81-86 years). The skin, subcutaneous tissue, deltoid, and overlying soft tissue were removed, exposing the coracoid, lateral clavicle, and acromion. The footprints of each ligament and tendon attaching to the coracoid were preserved. The footprint insertion areas were clearly marked circumferentially with a pen while the ligament/tendon footprint was intact; the ligament/tendon was then incised leaving a short stump. Measurements were independently recorded by 2 of the authors, blinded to each others’ measurements, using a digital caliper (Mitutoyo America Corp, Aurora, IL) accurate to 0.1 mm. The average of the 2 measurements are reported. The following bony dimensions of the coracoid were measured: (1) distance from the coracoid tip (hereafter termed ‘‘tip’’) to the coracoid base (length), (2) tip width, (3) tip height, (4) distance from the coracoid tip or base to the coracoid midpoint (hereafter termed ‘‘midpoint’’), (5) midpoint width, and (6) midpoint height (Figures 1 and 2) The following soft tissue footprints on the coracoid were studied: pectoralis minor, coracoacromial (CA) ligament, trapezoid coracoclavicular (CC) ligament, and conjoint tendon. The distance between these soft tissue footprints and their distance from the bony landmarks above was measured (Figure 3) The distance from the coracoid tip to the anterior CC ligaments was measured. This bony area anterior to the CC ligaments is
An anatomic study of the coracoid
Figure 2 View of the lateral aspect of the coracoid. The numbers correlate to Table I: 1, coracoid length (distance from tip to base); 3, coracoid tip height; 4, distance from the coracoid tip or base to the coracoid midpoint; 6, midpoint height. often described as the ‘‘knee’’ or ‘‘elbow’’ of the coracoid. The dimensions and location of the trapezoid CC ligament were measured rather than the conoid CC ligament because the trapezoid footprint is more anterior on the coracoid. Given that the length of coracoid available for transfer is the bone span from the coracoid tip to the most anterior CC ligament footprint, the trapezoid is the more clinically relevant CC ligament in osteotomy and transfer of the coracoid.
Results The anatomic dimensions of the coracoid bony anatomy are reported in Table I, which correlates to Figures 1 and 2. The mean coracoid length (1) was 45.6 4.2 mm, the mean coracoid tip width (2) was 18.3 1.8 mm, and the mean coracoid tip height (3) was 11.5 0.9 mm. The maximum length of the coracoid available for transfer (ie, the bone segment between the tip of the coracoid and the anterior extent of the trapezoid CC ligament or tip to ‘‘knee’’ or ‘‘elbow’’ of the coracoid) was 28.5 5.1 mm. The midpoint of the coracoid (4) was 22.8 2.1 mm from the tip/base. The midpoint mean width (5) was 16.1 2.3 mm, and the midpoint mean height (6) was 13.5 1.6 mm. The dimensions of and relationships between the soft tissue coracoid insertions on the coracoid are reported in Table II, which correlates to Figure 3. The mean distance from the coracoid tip to the anterior pectoralis minor (A) was 4.6 2.9 mm and to the posterior pectoralis minor (B) was 17.7 4.2 mm. The mean pectoralis minor footprint anteroposterior width (C) was 11.8 2.8 mm. The mean distance from the coracoid tip to the anterior CA ligament (D) was 7.8 3.6 mm and to the posterior CA ligament (E) was 25.7 4.4 mm. The CC ligament footprint anteroposterior width (F) was 17.9 3.6 mm. The mean
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Figure 3 View of the superior aspect of the coracoid with soft tissue footprints marked. Letters correlate to Table II: A, coracoid tip to anterior pectoralis minor; B, coracoid tip to posterior pectoralis minor; C, pectoralis minor insertion anteroposterior width; D, coracoid tip to anterior coracoacromial (CA) ligament; E, coracoid tip to posterior CA ligament; F, CA ligament insertion anteroposterior width; G, coracoid tip to anterior coracoclavicular (C-C) trapezoid ligament; H, posterior CA ligament to anterior C-C ligament.
distance from the coracoid tip to the anterior CC ligament (G) was 28.5 5.1 mm. The mean distance from the posterior extent of the CA ligament footprint to the anterior extent of the CC ligament footprint (H) was 2.8 6.0 mm. The posterior extent of the CA ligament was proximal to the anterior extent of the trapezoid CC ligament in both shoulders of 1 female specimen and only a single shoulder in 1 male specimen. The mean pectoralis minor footprint height (I) was 3.7 0.8 mm. The mean width of the conjoint tendon footprint (J) was 15.5 1.8 mm.
Discussion In the context of glenohumeral bone loss, coracoid transfer procedures have resulted in a lower dislocation recurrence rate compared with soft tissue procedures. Wellman et al17 demonstrated in a biomechanical study that the Latarjet procedure significantly reduced humeral head translation by 354% at 30 of abduction and by 374% at 60 of abduction. Using a modified Latarjet, Burkhart et al3 reduced their recurrent dislocation rate from 67% to 5% in patients with significant bone defects. The current literature does not provide a comprehensive report of the amount of bone available for transfer and the soft tissue implications of various coracoid osteotomy sites. The aim of our study was to define the bony and soft tissue attachment anatomy of the coracoid to assist in more informed surgical planning and execution of coracoid transfers. Other anatomic studies have defined various pieces of this data set as they relate to other procedures, namely, CC ligament reconstruction for acromioclavicular
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Table I
Bony anatomy dimensions of the coracoid
Variable 1. 2. 3. 4. 5. 6.
Mean (mm)
Coracoid length Tip width Tip height Distance from tip/base to midpoint Midpoint width Midpoint height
45.6 18.3 11.5 22.8 16.1 13.5
SD (mm) 4.2 1.8 0.9 2.1 2.3 1.6
Range Min (mm)
Max (mm)
40.8 16.1 10.0 20.4 12.1 11.7
53.0 22.2 12.6 26.5 18.9 17.3
Min, minimum value; Max, maximum value; SD, standard deviation.
Table II
Dimensions of and relationships between the soft-tissue footprints on the coracoid)
Variable Pectoralis minor A. Tip to anterior pectoralis minor B. Tip to posterior pectoralis minor C. Pectoralis minor insertion AP width Coracoacromial (CA) ligament (lig) D. Tip to anterior CA lig E. Tip to posterior CA lig F. CA lig insertion AP width (calc) Coracoclavicular (CC) trapezoid ligament G. Tip to anterior CC lig H. Posterior CA lig to anterior CC lig (calc) I. Height of pectoralis minor insertion Conjoint tendon J. Width of conjoint footprint
Mean (mm)
SD (mm)
Range Min (mm)
Max (mm)
4.6 17.7 11.8
2.9 4.2 2.8
0.0 11.5 6.8
8.8 25.7 16.7
7.8 25.7 17.9
3.6 4.4 3.6
2.9 16.3 13.4
13.8 29.9 24.5
28.5 2.8 3.7
5.1 6.0 0.8
22.9 e6.2 2.5
36.8 9.3 4.9
15.5
1.8
11.4
18.2
AP, anteroposterior; Max, maximum value; Min, minimum value; SD, standard deviation. ) Of note, the posterior insertion of the coracoacromial (CA) ligament was proximal to the trapezoid coracoclavicular (CC) ligament in both shoulders of a female specimen and in 1 shoulder of a male specimen.
instability,13-14 but to our knowledge, none has investigated the coracoid soft tissue insertion sites and bony anatomy as it relates to coracoid transfers. Measurements of total coracoid length in the literature vary: 43.1 2.2 mm (Salzmann et al,14 23 fresh cadavers), 45.2 4.1 mm (Rios et al,13 120 dry osteology cadavers), and 45.6 4.2 mm (our study, 10 fresh frozen cadavers). However, the more relevant anatomic measurement for the Latarjet procedure is the maximum length of coracoid that can be transferred, defined as the distance from the coracoid tip to the anterior extent of the CC ligament. The CC ligaments must be preserved to maintain acromioclavicular stability. We found the mean amount of coracoid available for transfer (ie, distance from the coracoid tip to the anterior CC ligament) was 28.5 5.1 mm. Using the data from Salzmann et al,14 the mean coracoid length available for transfer is 23.5 2.1 mm [(center of trapezoid to tip) e (footprint trapezoid AP/2)].13 Other studies have also measured the mean coracoid tip and base width and height. The reported mean coracoid tip widths are 13.6 2.1 mm (Salzman et al14), 15.9 2.2 mm (Lo et al,10 5 fresh frozen cadavers), and 18.3 1.8 mm
(this study). The reported mean coracoid tip heights are 8.2 1.0 mm (Salzman et al14), 10.4 1.4 mm (Lo et al10), and 11.5 0.9 mm (this study). As expected, men have a significantly longer coracoid, greater coracoid tip width and height, and greater coracoid base width and height than women.13,14 Kesmezacar et al6 reported that the CA ligament has a varied and often broad insertion onto the coracoid. Similarly, we found that in 3 cadavers, the CA ligament’s footprint overlapped with the CC ligament footprint on the coracoid. Therefore, care must be taken when releasing the CA ligament during coracoid transfers so that the CC ligaments and coracoclavicular biomechanics are not compromised.
Conclusions The purpose of this study was to assist surgeons during preoperative planning and intraoperative decision making when performing a Bristow or Latarjet procedure to address recurrent anterior glenohumeral
An anatomic study of the coracoid instability in the context of glenohumeral bone loss. This anatomic description of the coracoid bony anatomy and its soft tissue insertions allows surgeons to correlate the location of their coracoid osteotomy with the soft tissue implications of the coracoid transfer as the native anatomy is manipulated in these nonanatomic procedures. Future biomechanical research can establish an algorithm for the minimum amount of coracoid required to achieve stability according to the degree of glenoid bone loss. The data reported in our study would help define what tendons and ligaments are most likely affected in each scenario.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article. No financial biases exist for these authors.
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