Anterior-inferior Portal for Shoulder Arthroscopy at Anatomical Risk in Comparison Between the Inside-outand Outside-in Techniques

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1 Anterior-inferior Portal for Shoulder Arthroscopy at Anatomical Risk in Comparison Between the Inside-outand Outside-in Techniques Masahito Yoshida 1, Hideyuki Goto, MD, PhD 2, Masahiro Nozaki, MD, PhD 3, Yasuhiro Nishimori 4, Atsunori Murase 4, Tetsuya Takenaga, MD 4, Yuko Nagaya 4, Masaaki Kobayashi, MD, PhD 3, Takanobu Otsuka 3. 1 Nagoya City University, Graduate School of Medical Science Nagoya, Nagoya, Japan, 2 Nagoya City University, Graduate School of Medical Science, Nagoya, Japan, 3 Nagoya City University, Nagoya, Japan, 4 Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan. Disclosures: M. Yoshida: None. H. Goto: None. M. Nozaki: None. Y. Nishimori: None. A. Murase: None. T. Takenaga: None. Y. Nagaya: None. M. Kobayashi: None. T. Otsuka: None. Introduction: Arthroscopic repair techniques usinga suture anchor have become more common recently as a treatment for Bankart lesions, which is caused by traumatic shoulder dislocation..a Bankart lesion involves the detachment of the labrum from the glenoid bone in the anterior-inferior area, especially from 3-o-clock to 6-o-clock at the edge of the glenoid rim in the right shoulder. Anterior portals have been used for the repair of such lesions based on their anatomical safety, as demonstrated in previous studies. Common arthroscopic Bankart repairs involvethe insertion of a suture anchor at the 5-o -clock position as the mostinferior position through the anterior portal. For a successful outcome of arthroscopic surgery with the rigid fixation of a suture anchor, it isnecessary to insert a suture anchor inside the bone. However, in some cases,such as humeral avulsion of glenohumeral ligament (HAGL) lesionand bony Bankart lesion, an additional anterior portal should be necessary to make in order to insert a suture anchor into the optimal position of the humerus or glenoidbone. In these cases, the accessory portal, known as the anterior-inferior(5-o -clock) portal, could be optimal for the direct approach tothe inferior region of the glenoid rim and the neck of the humerus. However, the creation of this portal risks neurovascular injury.previously, Davidson andtibone demonstrated an inside-to-outside (I-O) method for creating an anterior-inferior portal using anatomical and clinical studies, and Resch andcolleague reported on anterior-inferior portal creation using an outside-to-inside(o-i) technique. However, few studies have compared the anatomical risk of these techniques in the creation of 5-o -clock portals in a lateral decubitus position. The present study compared the neurovascular structures at risk during the establishment of5-o -clock portals using I-O and O-I procedures. Methods: Twenty two embalmed cadaveric shoulder joints were dissected including 11 right and 11 left shoulders (four male and 18 female). The age of cadavers ranged from 78 to 100 years (mean 87.5 years). The cadavers with shoulder scares and severe arthritis were excluded from this study. Cadavers were installed in a lateral decubitus position. The arms were fixed at 20 of flexion, neutral rotation, and two different abduction positions: 0 (ADD) and 30 (ABD). 2 mm Kirschner wires (K-w) were used to create anterior-inferior portal, using established inside-to-outside (I-O) and outside-to-inside (O-I) techniques (Fig.1, 2). At dissection, the shortest distances from K-w to the (1) axillary nerve, (2) axillary artery (3) musclocutaneous nerve, (4) cephalic vein, and (5) anterosuperior circumflex artery were measured by digital caliper. Each distance was measured three times and we recorded the average of those 3 measurements asthe final distance (Fig. 3). For statistical comparisons between the two techniques on each arm position, data were analyzed using repeated-measures analysis ofvariance (ANOVA) with a mixed effect model. Values of P < 0.01 were considered statistically significant. All data analyses were performed using open-source statistical computing software (Rpackage; Results: The average distances to the neurovascular structures at the ADD and ABD arm positions using both the I-O and O-I techniques are shown in Table 1. There was no significant difference between both techniques in relation to the anteriorsuperior circumflex artery. The average distances to the axillary nerve, axillary artery, and musculocutaneous nerve were significantly shorter using the I-O technique than the O-I technique without relation to the arm positions (P < 0.01). By contrast, the I-O technique showed a significantly longer distance for the cephalic vein (P < 0.01). For the I-O procedure in the ADD arm position, the cephalic vein, musculocutaneous nerve, axillary artery, and axillary nerve were either pierced by or came into contact with the K-w in 5% (1/20), 15% (3/20), 10% (2/20), and 15% (3/20) of cases, respectively; for the same procedure in the ABD arm position, the musculocutaneous nerve and axillary artery were either pierced by or came into contact with the K-w in 40% (5/20) and 15% (3/20) of cases, respectively. Regarding the O-I procedure in both arm positions, the K-w injured only the cephalic vein in 25% (5/20) of cases.the intraobserver correlation coefficient for the measurement of distance between neurovascular structures and the K-w was (95% confidence interval, ), demonstrating excellent reproducibility. Discussion: An anterior-inferior portal, which is called 5 o clock portal, provides more direct access to thecapsulolabral

2 detachment from the glenoid rim at anterior-inferior area. Previous studies have described the risk of neurovascular structure injury in the process of 5 o clock portal creation with inside-to-outside and outside-to-inside techniques respectively. However, few previous studies have compared the anatomical risks between O-I and I-O techniques in the creation of 5-o -clock portals in a lateral decubitus. Our present work found that the musculocutaneous nerve, axillarartery, and axillary nerve were at higher risk of serious complications using the I-O technique irrespective of the abduction angle of the h umerus. Bycontrast, the cephalic vein was at greater risk using the O-I technique compared with the I-O technique. Moreover, the average distances to the neurovascular structures, with the exception of the cephalic vein, were more than 10 mm in the arm positioned at ABD. Thus, the present study showed that 5-o -clock portals can be established using the O-I technique with minimal risk to the axillar nerve, musculocutaneous nerve, axillar artery, andanterior-superior circumflex artery. Significance: The axillar nerve, axillar artery, and musculocutaneous nerve were shown to be at a higher risk of injury using the I- O technique than the O-I technique without relation to shoulder abduction, although the cephalic vein was at a lower risk of injury. The outside-to-inside technique in the abduction arm position could be safer procedure in the creation of 5 o clock portal than the inside-to-outside technique. Acknowledgments: References: 1. Davidson PA, et al. Arthroscopy., 1995; 11(5): Resch H, et al. Arthroscopy., 1996; 12(3):

4 ORS 2014 Annual Meeting Poster No: 1914

Capsulolabral reattachment was first advocated by

Capsulolabral reattachment was first advocated by A Comparison of Risk Between the Lateral Decubitus and the Beach-Chair Position When Establishing an Anteroinferior Shoulder Portal: A Cadaveric Study Pablo Eduardo Gelber, M.D., Francisco Reina, M.D.,