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Editorial Commentary: Size Matters: Biomechanical Analysis of All-Suture Suture-Anchor Fixation Compared to Conventional Suture Anchors and Interference Screws for Biceps Tenodesis

      Abstract

      Anchors and screws demonstrate similar fixation properties for shoulder biceps tenodesis allowing healing, but anchors requiring smaller drill holes reduce the risk of postoperative fractures under torsional stress. Clinicians could create the smallest possible holes in the humerus, especially in throwing athletes who create large torsional stresses.
      My first thought as I began reading “Biomechanical Analysis of All-Suture Suture Anchor Fixation Compared With Conventional Suture Anchors and Interference Screws for Biceps Tenodesis” by Frank, Bernardoni, Veera, Waterman, Griffin, Shewman, Cole, Romeo, and Verma
      • Frank R.
      • Bernardoni E.D.
      • Veera S.
      • et al.
      Biomechanical analysis of all-suture sutureanchor fixation compared with conventional suture anchors and interference screws for biceps tenodesis.
      was, “I'm so bored with time 0 mechanical strength studies for biceps tenodesis constructs… Let's please talk about something that actually matters.” Fortunately, I kept reading and was rewarded with clinically relevant torsional fracture data. The authors performed a well-designed cadaveric study that adds tremendously to the existing body of literature. They demonstrated that size does matter: smaller diaphyseal holes may decrease torsional fracture risk following subpectoral biceps tenodesis.
      Biceps tenodesis fixation constructs provide temporary secure fixation during the first 6 postoperative weeks for healing. Ultimate strength depends on tendon healing to or into bone. As such, it is likely that time 0 fixation strength cadaveric studies for biceps tenodesis have little bearing on clinical outcomes. The long head of the biceps tendon accounts for 0% to 25% of the muscle's strength.
      • Deutch S.R.
      • Gelineck J.
      • Johannsen H.V.
      • Sneppen O.
      Permanent disabilities in the displaced muscle from rupture of the long head tendon of the biceps.
      • Shank J.R.
      • Singleton S.B.
      • Braun S.
      • et al.
      A comparison of forearm supination and elbow flexion strength in patients with long head of the biceps tenotomy or tenodesis.
      • McGough R.L.
      • Debski R.E.
      • Taskiran E.
      • Fu F.H.
      • Woo S.L.
      Mechanical properties of the long head of the biceps tendon.
      • Sturzenegger M.
      • Béguin D.
      • Grünig B.
      • Jakob R.P.
      Muscular strength after rupture of the long head of the biceps.
      In vivo stresses on biceps tenodesis constructs are exposed to submaximal loads tested by previous biomechanical studies. Further, it is likely that the postoperative patient in a sling generates cyclic loading conditions far lower than those tested by various investigators.
      • Chiang F.L.
      • Hong C.-K.
      • Chang C.-H.
      • Lin C.-L.
      • Jou I.-M.
      • Su W.-R.
      Biomechanical Comparison of all-suture anchor fixation and interference screw technique for subpectoral biceps tenodesis.
      • DeAngelis J.P.
      • Chen A.
      • Wexler M.
      • et al.
      Biomechanical characterization of unicortical button fixation: A novel technique for proximal subpectoral biceps tenodesis.
      • Golish S.R.
      • Caldwell P.E.
      • Miller M.D.
      • et al.
      Interference screw versus suture anchor fixation for subpectoral tenodesis of the proximal biceps tendon: a cadaveric study.
      • Kaback L.A.
      • Gowda A.L.
      • Paller D.
      • Green A.
      • Blaine T.
      Long head biceps tenodesis with a knotless cinch suture anchor: a biomechanical analysis.
      • Mellano C.R.
      • Frank R.M.
      • Shin J.J.
      • et al.
      Subpectoral biceps tenodesis with PEEK interference screw: A biomechanical analysis of humeral fracture risk.
      • Papp D.F.
      • Skelley N.W.
      • Sutter E.G.
      • et al.
      Biomechanical evaluation of open suture anchor fixation versus interference screw for biceps tenodesis.
      • Sethi P.M.
      • Rajaram A.
      • Beitzel K.
      • Hackett T.R.
      • Chowaniec D.M.
      • Mazzocca A.D.
      Biomechanical performance of subpectoral biceps tenodesis: A comparison of interference screw fixation, cortical button fixation, and interference screw diameter.
      • Tashjian R.Z.
      • Henninger H.B.
      Biomechanical evaluation of subpectoral biceps tenodesis: Dual suture anchor versus interference screw fixation.
      Frank et al.
      • Frank R.
      • Bernardoni E.D.
      • Veera S.
      • et al.
      Biomechanical analysis of all-suture sutureanchor fixation compared with conventional suture anchors and interference screws for biceps tenodesis.
      reported greater elongation for the suture anchor constructs than interference screw fixation. The advantage of construct stiffness is tempered by 2 negatives: early tendon tearing during cyclic testing and the creation of a torsional stress riser.
      There are several reports of humeral fractures following open subpectoral biceps tenodesis,
      • Dein E.J.
      • Huri G.
      • Gordon J.C.
      • McFarland E.G.
      A humerus fracture in a baseball pitcher after biceps tenodesis.
      • Reiff S.N.
      • Nho S.J.
      • Romeo A.A.
      Proximal humerus fracture after keyhole biceps tenodesis.
      • Sears B.W.
      • Spencer E.E.
      • Getz C.L.
      Humeral fracture following subpectoral biceps tenodesis in 2 active, healthy patients.
      with some occurring during a torsional stress such as throwing.
      • Dein E.J.
      • Huri G.
      • Gordon J.C.
      • McFarland E.G.
      A humerus fracture in a baseball pitcher after biceps tenodesis.
      Euler et al.
      • Euler S.A.
      • Smith S.D.
      • Williams B.T.
      • Dornan G.J.
      • Millett P.J.
      • Wijdicks C.A.
      Biomechanical analysis of subpectoral biceps tenodesis: Effect of screw malpositioning on proximal humeral strength.
      reported that eccentric placement of an 8-mm tenodesis hole resulted in 25% reduction of humeral shaft strength against a compressive load compared with the concentrically placed hole. Although this was helpful information, the greater concern is effect on torsional strength. Beason et al.
      • Beason D.P.
      • Shah J.P.
      • Duckett J.W.
      • Jost P.W.
      • Fleisig G.S.
      • Cain E.L.
      Torsional Fracture of the Humerus after Subpectoral Biceps Tenodesis with an Interference Screw: A Biomechanical Cadaveric Study.
      investigated the effect of 6.25- and 8.0-mm holes drilled in cadaveric humeri on their torsional strength. Although there was no difference between the 2 experimental groups, both demonstrated a significant reduction in torsional strength compared with the nondrilled contralateral humeral control. Mellano et al.
      • Mellano C.R.
      • Frank R.M.
      • Shin J.J.
      • et al.
      Subpectoral biceps tenodesis with PEEK interference screw: A biomechanical analysis of humeral fracture risk.
      also reviewed the impact of subpectoral tenodesis technique on torsional strength and found that drilling of an 8-mm hole causes a 20% to 30% reduction in torsional strength compared with the contralateral control.
      Building on the Mellano et al.
      • Mellano C.R.
      • Frank R.M.
      • Shin J.J.
      • et al.
      Subpectoral biceps tenodesis with PEEK interference screw: A biomechanical analysis of humeral fracture risk.
      study, Frank et al.
      • Frank R.
      • Bernardoni E.D.
      • Veera S.
      • et al.
      Biomechanical analysis of all-suture sutureanchor fixation compared with conventional suture anchors and interference screws for biceps tenodesis.
      took their investigation to the next level. They looked at the size of the hole and its effect on torsional strength. All interference screw constructs fractured through the 8-mm stress riser that the hole created and at significantly smaller amounts of rotational displacement (3°, P = .001) than the 2 anchors tested. Although no differences were identified between the 2 anchor constructs regarding rotational displacement or maximum torsional load, they did observe that 57% of the fractures on failure testing traversed the 2.9-mm hole created for conventional suture anchors and that this occurred in only 29% the specimens with 1.9-mm pilot hole for all-suture suture anchors.
      Frank et al.
      • Frank R.
      • Bernardoni E.D.
      • Veera S.
      • et al.
      Biomechanical analysis of all-suture sutureanchor fixation compared with conventional suture anchors and interference screws for biceps tenodesis.
      showed me that fixation properties are similar and clinically adequate to allow healing, but that using smaller holes likely reduces the risk of postoperative fractures under torsional stress. Their study argues makes a compelling argument to place the smallest holes in the humerus as possible, especially in throwing athletes who see large torsional stresses.

      Supplementary Data

      References

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