Arthroscopic single anchor repair techniques for upper third subscapularis tears provide sufficient biomechanical stability

Abstract

PurposeUpper third tears of the subscapularis tendon can be repaired successfully with a single anchor according to previous literature. The aim of the present study was to compare three single anchor repair techniques regarding fixation strength, footprint coverage and contact pressure in a biomechanical test set‐up on human cadaveric shoulders. MethodsEighteen human cadaveric shoulders were randomized in three groups with respect to the repair technique; group 1: knotted lasso‐loop mattress, group 2: knotted mattress and group 3: knotless tape repair. Upper third tears of the subscapularis tendon (Lafosse type 2) were created and repairs were performed with additional contact pressure and area measurement using a pressure mapping system. Cyclic testing was performed by loading the subscapularis from 10 to 100 N for 300 cycles. A position‐controlled ramp protocol up to 30 and 50 N was used to allow for pressure measurements. Finally, specimens were loaded to failure and failure modes were recorded. ResultsThe three groups were not significantly different regarding age, gender, bone mineral density at the lesser tuberosity, subscapularis footprint size and defect area created at the upper subscapularis insertion. A significant difference was detected between group 1 (48.6 ± 13.8%) and group 2 (25.9 ± 5.7%) regarding pressurized footprint coverage (p = 0.028).Ultimate load to failure was 630.8 ± 145.3 N in group 1, 586.9 ± 220.7 N in group 2 and 678.2 ± 236.5 N in group 3, respectively. Cyclic displacement was similar in all three groups with an average displacement of 1.2 ± 0.6 mm. The highest stiffness was found in group 1 with 88 ± 30.3, which was not statistically significantly different to group 2 (65 ± 27 N/mm) and group 3 (83.9 ± 32.9 N/mm).The most common mode of failure was suture cut‐through at the suture–tendon interface (44%). Failures in group 3 were less common associated with suture cut‐through (33% vs. 50% in group 1 and 2), but no significant differences were found. ConclusionsAll three tested single anchor repair techniques of upper third subscapularis tears were able to provide sufficient biomechanical stability. Knotted lasso‐loop mattress and knotless tape repair were superior regarding pressurized footprint coverage compared to a knotted horizontal mattress technique and are, therefore, preferable techniques for upper subscapularis repair.

Limited Biomechanical Evidence Behind Single Row Versus Double Row Repair of Subscapularis Tears: A Systematic Review

“…Sgroi et al 32 compared knotted and knotless single-row repair for Fox-Romeo III subscapularis tears and found no significant differences in biomechanical properties for both constructs. Likewise, Borbas et al 31 compared 3 different single-row constructs (knotted lasso-loop mattress, knotted mattress, and knotless suture tape) for Lafosse II subscapularis tears and found that the constructs resulted in similar ultimate load, gap formation, and stiffness. The authors did report a significantly higher pressurized footprint coverage for the knotted lasso-loop mattress and knotless construct compared to the knotted mattress repair.…”

“…Of these, 12 articles underwent full text review, resulting in six articles that were included and analyzed (Fig 1). [28][29][30] According to the QUACS, three studies were excellent (>11/13), 28,31,32 and 3 studies were of substantial (9/13 or 10/13) quality. 29,30 The number of specimens per study ranged from 6 to 18 for a total of 63 specimens and 104 shoulders included in this review.…”

“…The mean age of the cadaveric specimens ranged from 62.4 to 78 years. The average native subscapularis footprint area was reported in three studies, 28,30,31 and it ranged from 295 mm 2 to 631.5 mm 2 (Table 1).…”

“…Three studies 28,32,33 used the Fox-Romeo 34 classification system to recreate type II (complete tear of the upper 25%) and III (complete tear of the upper 50%) tears of the subscapularis, 1 study 31 used the Lafosse classification 8 to recreate type II tears (complete tear of the upper 1/3), and 2 studies created complete fullthickness tears 29,30 (Table 2). Of the included studies, two 28,29 compared single-row and double-row repair, one 30 compared single-row to transosseous repair, and 3 studies [31][32][33] used only single-row suture anchor constructs. Two studies compared knotted and knotless single-row repairs.…”

“…Two studies compared knotted and knotless single-row repairs. 31,32 The 4 studies 28,[31][32][33] published most recently used bioabsorbable suture anchors, whereas titanium suture anchors were used in the other 2 studies (Table 2). 29,30 Double-row repairs used three 28 or four 29 suture anchors.…”