Optimal position of tendon transfer in reverse shoulder arthroplasty with L'Episcopo for better rotation range of motion

Abstract

Background: Reverse total shoulder arthroplasty (rTSA) with the modified L'Episcopo procedure is useful for rotator cuff tear arthropathy with combined loss of elevation and external rotation. However, depending on the location of the tendon graft transfer, external rotation may improve but cause a limitation of internal rotation. The purpose of this study was to investigate the optimal position of tendon transfer in rTSA with the modified L'Episcopo procedure for better range of motion in rotation using fresh frozen cadavers.

Methods: Eight fresh frozen cadaveric shoulders underwent rTSA with the modified L'Episcopo procedure. To investigate the location of tendon transfer that obtains better internal and external rotation, 6 tendon transfer locations were set and the internal and external rotation at each location was measured with the arm at the side position. The 6 locations were divided horizontally into 3 locations of 225°, 270°, and 315° medial to the bicipital groove. In the lateral view, the height was divided into 2 locations which were the lower end level of the insertion of the teres minor muscle and the middle of the original insertion of the latissimus dorsi muscle.

Results: Three positions were significantly better for external rotation: the height of the lower edge of the teres minor insertion at 270° and 315° from the bicipital groove and the middle of the latissimus dorsi insertion at 315° from the bicipital groove compared to the height of the middle of the latissimus dorsi insertion at 225° from the bicipital groove. On the other hand, for internal rotation, the lower edge of the teres minor insertion and middle of the latissimus dorsi insertion at 315° from the bicipital groove significantly limited internal rotation compared to the other transition positions.

Conclusion: The position of tendon transfer 270° from the bicipital groove at the height of the lower end of the teres minor insertion allowed both relatively good external rotation and internal rotation. Significant limitation of internal rotation was found with transfer 315° from the bicipital groove.

Keywords: Biomechanics; L’Episcopo; Optimal position; Reverse total shoulder arthroplasty; Tendon transfer; Tendon transfer position.

Figure 1

(a) Before stripping off the latissimus dorsi and teres major, (b) the disconnected transected end of the teres major and latissimus dorsi from the humeral attachment were combined. (c) The combined tendon was turned posteriorly on the humerus with a baseball suture. Then, a hole was drilled with K-wire at the site of the tendon transfer, the baseball suture was threaded, and the suture was ligated at the bicipital groove using a metal button.

Figure 2

Lateral view of the positions of the tendon transfer.

Figure 3

Top view of the positions of the tendon transfer. 1: Lower level of the teres minor insertion 225° from the bicipital groove. 2: Lower level of the teres minor insertion 270° from the bicipital groove. 3: Lower level of the teres minor insertion 315° from the bicipital groove. 4: Middle of the latissimus dorsi insertion 225° from the bicipital groove. 5: Middle of the latissimus dorsi insertion 270° from the bicipital groove. 6: Middle of the latissimus dorsi insertion 315° from the bicipital groove.

Figure 4

The internal and external rotation angles were measured by manually applying a rotational force of 1 N using a torque wrench.

Figure 5

The range of motion of external rotation (Y-axis) was measured and compared at each graft tendon transfer position (X-axis). The height of the lower level of the teres minor insertion at 270° and 315° from the bicipital groove, and the middle of the latissimus dorsi insertion at 315° from the bicipital groove showed greater external rotation compared to the height of the lower level of the teres minor insertion at 225° from the bicipital groove (P < .001). TM, the lower level of the teres minor insertion; LD, the middle of the latissimus dorsi insertion. TM, teres minior; LD, latissimus dorsi; ER, external rotation.

Figure 6

The range of motion of internal rotation (Y-axis) was measured and compared at each graft tendon transfer position (X-axis). More limited internal rotation occurred at 2 positions: 315° from the bicipital groove at the lower level of the teres minor insertion (P < .01) and the middle of the latissimus dorsi insertion compared to 225° (P < .001) and 270° (P < .01). TM, teres minior; LD, latissimus dorsi; IR, internal rotation.

Figure 7

The total arc, the sum of the angles of external and internal rotation (Y-axis) was compared at 6 locations (X-axis). The position of the lower level of the teres minor insertion at 270° from the bicipital groove had the best result with a total arc of 60°, but there was no significant difference in the comparison among the 6 locations. TM, teres minior; LD, latissimus dorsi; ER, external rotation; IR, internal rotation.