Anterior Cable Tears in Arthroscopic Rotator Cuff Repairs

Abstract

Purpose: To determine whether anterior cable tears could be identified at the time of arthroscopic rotator cuff repair and determine the characteristics of the anterior cable tears identified.

Methods: From 2016 to 2017 all shoulder arthroscopies had data collected prospectively at the time of surgery, specifically including injury to the capsular and tendon zones of insertion on the greater tuberosity. Anterior cable position and degree of injury and medialization were recorded, as well as complete findings of the diagnostic arthroscopy. The inclusion criterion was primary shoulder arthroscopy. The exclusion criterion was any revision shoulder arthroscopy. All arthroscopic rotator cuff repairs (ARCR) were grouped together and all other nonarthroscopic rotator cuff repair surgeries (non-ARCR) were grouped together.

Results: In total, 118 shoulder arthroscopies had data collected prospectively at the time of surgery: 90 primary shoulder arthroscopies met the inclusion criteria; 28 were excluded because they were revision surgeries. There were 42 patients in the ARCR group (Group 1). Six of these were partial tears, and 36 were full-thickness tears. There were 48 patients in the non-ARCR group (Group 2). The non-ARCR Group 2 served as an anatomic baseline for ARCR Group 1. In all 90 shoulders, the rotator cable and anterior cable were identified. Group 1 (ARCR) incidence of anterior cable tears with abnormal position was 71.4% compared to 2.1% in group 2 (non-ARCR) (P < .001) Group 1 (ARCR) incidence of anterior cable tears with normal anterior cable position (n = 12) was compared to abnormal anterior cable position (n = 30). Injury to the anterior footprint capsular and tendon zones were compared. Normal anterior cable position correlated with no or low-grade injury to anterior footprint capsular zone. (Nimura zone C1). Abnormal anterior cable displacement graded as moderate (n = 20) and severe (n = 10) were compared for injury to the anterior footprint. Moderate displacement correlated with complete or high grade injury to C1 in 85% and complete injury to R1 in 45% (P < .001 and .049). In severe displacement complete C1 injury was 100%, and complete R1 injury was 100% (P < .001 and .001).

Conclusions: Anterior cable tears are universally identified in ARCR. Three patterns of medial displacement severity correlated with injury to a crucial insertion zone (C1) at the anterior footprint. The degree of anterior cable disruption at the anterior footprint and displacement was commonly disproportionately greater than the injury to the supraspinatus.

Level of evidence: Level III, diagnostic study.

Fig 1

(A) Superior aspect of the humerus. (B) Anterior footprint 2 anatomical zones : C1 measures 5.6 mm ± 1.6 mm (red capsular zone); R1 measures 3.5 mm ± 2.3 mm (blue tendon zone); D1 measures 10.9 mm ± 3.1 mm. Area of capsular zone 60 mm² , Area of tendon zone 40 mm² (approximately). (C1, width of the attachment of the articular capsule at the anterior margin of the greater tuberosity; C2, minimum width of the attachment of the articular capsule; C3, width of the attachment of the articular capsule at the posterior margin of the supraspinatus; C4, width of the attachment of the articular capsule at the point of maximum width of the infraspinatus; D1, distance from anterior margin of the greater tuberosity to the point of minimum width of the articular capsule. D2, distance from point of minimum width of the articular capsule to the posterior margin of the supraspinatus; GT, greater tuberosity; HH, humeral head; LT, lesser tuberosity; R1, width of the footprint of the supraspinatus at the anterior margin of the greater tuberosity; R2, width of the footprint of the supraspinatus and infraspinatus at the point of the minimum width of the articular capsule; R3, width of the footprint of the infraspinatus at the posterior margin of the supraspinatus; R4, maximum width of the footprint of the infraspinatus. Reproduced with permission from K. Nimura et al. The superior capsule of the shoulder joint complements the insertion of the rotator cuff. Journal of Shoulder and Elbow Surgery 2012;21:867-872.

Fig 2

Surgical checklist and data sheet.

Fig 3

The anterior footprint on the greater tuberosity 2 zones are the C1 capsular zone (red) and the R1 supraspinatus tendon zone (blue). The results of the data demonstrate the following: (1) The anterior cable position is dependent first on the capsular zone at C1. When the anterior cable tears away from the crucial zone, it begins to medialize. Injury to the C1 zone correlated with the anterior cable position. The results indicate that the C1 zone is “crucial” for maintaining the anterior cable position and preventing medialization of the anterior cable. (2) The R1 tendon zone of the anterior footprint supports the C1 “crucial zone” and helps maintain the anterior cable position. As injury extends into the R1 zone from the crucial zone (C1), the anterior cable tear moderately medializes away from the footprint toward the glenoid. The LRI-biceps pulley supports the crucial zone (C1) and the tendon zone (R1). Injury that extends into the biceps pulley and includes the roof or medial biceps sling allows the anterior cable to severely retract medially to the glenoid. The results indicate that the C1 zone is a “crucial” zone for maintaining anterior cable position and preventing medialization of the anterior cable. The crucial zone (C1) is further stabilized by the R1 zone (supraspinatus tendon) and the biceps pulley of the lateral rotator interval. (C1, capsular zone [red]; GT, greater tuberosity; HH, humeral head; LRI, lateral rotator interval [yellow]; LT, lesser tuberosity; R1, tendon zone [blue]; SSP, supraspinatus).

Fig 4

Anterior cable tear characteristics: Superior view and lateral cross-section of supraspinatus and cable with clinical picture demonstrating cable and anterior cable position. Clinical pictures: Arthroscopic views from posterior medial portal. (Lateral position with arm in 40° abduction and 20 FF and scope rotated 90° to bring the shoulder upright). (A) Normal cable and anterior cable position with no injury. (B) ACT 1, anterior cable tear with no or minimal medial displacement (<1 cm). Minimal change in shape of the cable; typically found in pasta tears and bursal tears. Partial to complete disruption of crucial zone (C1) or complete disruption of supraspinatus tendon zone (R1). (C) ACT 2, Anterior cable tear with moderate medial displacement (>1 cm from crucial zone laterally and superior labrum medially) Distinct change in shape of cable can be noted; Usually to a “U” or arch; Typically found in full-thickness tears that expose the biceps partially with disruption of the lateral biceps sling. Complete disruption of crucial zone (C1), plus partial to complete disruption of supraspinatus tendon zone (R1). (D) ACT 3, Anterior cable tear with severe medial displacement (<1 cm from superior labrum). Usually a complete loss of shape from a broken cable, like the handle of a bucket breaking free from its attachment. The biceps is completely exposed with complete disruption of the lateral biceps sling and a partial to complete disruption of the medial biceps sling. Complete disruption of crucial zone (C1), plus complete disruption of supraspinatus tendon zone (R1), plus at least partial injury to biceps pulley (lateral and medial pulley). (ACT, anterior cable tear; BT, biceps tendon; GT, greater tuberosity; HH, humeral head; LRI; lateral rotator interval; LT, lesser tuberosity; SSP, supraspinatus; X(red), injury to zone.

Fig 4

Anterior cable tear characteristics: Superior view and lateral cross-section of supraspinatus and cable with clinical picture demonstrating cable and anterior cable position. Clinical pictures: Arthroscopic views from posterior medial portal. (Lateral position with arm in 40° abduction and 20 FF and scope rotated 90° to bring the shoulder upright). (A) Normal cable and anterior cable position with no injury. (B) ACT 1, anterior cable tear with no or minimal medial displacement (<1 cm). Minimal change in shape of the cable; typically found in pasta tears and bursal tears. Partial to complete disruption of crucial zone (C1) or complete disruption of supraspinatus tendon zone (R1). (C) ACT 2, Anterior cable tear with moderate medial displacement (>1 cm from crucial zone laterally and superior labrum medially) Distinct change in shape of cable can be noted; Usually to a “U” or arch; Typically found in full-thickness tears that expose the biceps partially with disruption of the lateral biceps sling. Complete disruption of crucial zone (C1), plus partial to complete disruption of supraspinatus tendon zone (R1). (D) ACT 3, Anterior cable tear with severe medial displacement (<1 cm from superior labrum). Usually a complete loss of shape from a broken cable, like the handle of a bucket breaking free from its attachment. The biceps is completely exposed with complete disruption of the lateral biceps sling and a partial to complete disruption of the medial biceps sling. Complete disruption of crucial zone (C1), plus complete disruption of supraspinatus tendon zone (R1), plus at least partial injury to biceps pulley (lateral and medial pulley). (ACT, anterior cable tear; BT, biceps tendon; GT, greater tuberosity; HH, humeral head; LRI; lateral rotator interval; LT, lesser tuberosity; SSP, supraspinatus; X(red), injury to zone.