Gerber and colleagues measured how suture material, tendon‑grasping stitch and bone anchorage each affect the strength of rotator cuff tendon‑to‑bone repair.
Bench study: 159 sheep infraspinatus tendons (80 sheep) for 9 tendon‑grasping techniques, and 18 osteoporotic human cadaver humeral heads (age 65 to 80) for bone fixation.
Methods
Model
159 normal sheep infraspinatus tendons for tendon grasping
18 osteoporotic cadaver humeral heads (15 with complete supraspinatus tears) for bone fixation
Nine tendon‑grasping techniques, including simple and modified Mason‑Allen stitches
Single and double transosseous sutures
Mitek G II suture anchor
Double transosseous sutures augmented by a 2.0 mm absorbable poly(L-/D‑lactide) membrane
Sutureless fixation: plate with cortical graft, metallic brush
1.4 mm membrane augmentation of tendon‑grasping stitches
Loading
Load to failure
Grasping pull‑out under 30 N preload
Cyclic loading to 250 N, up to 1000 cycles
Two 7 cm suture loops loaded to 200 N
Outcome measures
Ultimate tensile strength
Stiffness
Elongation under load
Key Findings
Two modified Mason‑Allen stitches held 359 N, vs 184 N for two simple stitches and 208 N for four, and failed only by suture rupture, never by pulling out of the tendon.
The modified Mason‑Allen stitch was the only grasping technique to survive 1000 load cycles in every test.
Membrane augmentation was the only bone fixation that was significantly stronger (p < 0.05), and its failure was then limited by the strength of the Ethibond 3 suture.
Braided polyester, polyglactin and polyglycolic acid sutures gave the best mix of strength and stiffness.
At 200 N on two 7 cm loops, PDS II size 1 stretched 10.2 mm and Surgilon 1 stretched 7.4 mm, vs 2.2 mm for Ethibond size 3.
Augmenting the grasping stitches with an absorbable membrane did not improve holding strength, because the membrane acted as a gliding plane.
Board pearl
The modified Mason‑Allen stitch never pulled out of the tendon: it failed by suture rupture, so the suture, not the grasp, limited its strength.
Authors' conclusion
The mechanical properties of many current repair techniques are poor and can be greatly improved by using good materials, an improved tendon-grasping suture, and augmentation at the bone attachment.
Gerber and colleagues measured how suture material, tendon‑grasping stitch and bone anchorage each affect the strength of rotator cuff tendon‑to‑bone repair.
Bench study: 159 sheep infraspinatus tendons (80 sheep) for 9 tendon‑grasping techniques, and 18 osteoporotic human cadaver humeral heads (age 65 to 80) for bone fixation.
Methods
Model
159 normal sheep infraspinatus tendons for tendon grasping
18 osteoporotic cadaver humeral heads (15 with complete supraspinatus tears) for bone fixation
Nine tendon‑grasping techniques, including simple and modified Mason‑Allen stitches
Single and double transosseous sutures
Mitek G II suture anchor
Double transosseous sutures augmented by a 2.0 mm absorbable poly(L-/D‑lactide) membrane
Sutureless fixation: plate with cortical graft, metallic brush
1.4 mm membrane augmentation of tendon‑grasping stitches
Loading
Load to failure
Grasping pull‑out under 30 N preload
Cyclic loading to 250 N, up to 1000 cycles
Two 7 cm suture loops loaded to 200 N
Outcome measures
Ultimate tensile strength
Stiffness
Elongation under load
Key Findings
Two modified Mason‑Allen stitches held 359 N, vs 184 N for two simple stitches and 208 N for four, and failed only by suture rupture, never by pulling out of the tendon.
The modified Mason‑Allen stitch was the only grasping technique to survive 1000 load cycles in every test.
Membrane augmentation was the only bone fixation that was significantly stronger (p < 0.05), and its failure was then limited by the strength of the Ethibond 3 suture.
Braided polyester, polyglactin and polyglycolic acid sutures gave the best mix of strength and stiffness.
At 200 N on two 7 cm loops, PDS II size 1 stretched 10.2 mm and Surgilon 1 stretched 7.4 mm, vs 2.2 mm for Ethibond size 3.
Augmenting the grasping stitches with an absorbable membrane did not improve holding strength, because the membrane acted as a gliding plane.
Board pearl
The modified Mason‑Allen stitch never pulled out of the tendon: it failed by suture rupture, so the suture, not the grasp, limited its strength.
Authors' conclusion
The mechanical properties of many current repair techniques are poor and can be greatly improved by using good materials, an improved tendon-grasping suture, and augmentation at the bone attachment.