Naoya Kozono

Asymmetric six-strand core sutures enhance tendon fatigue strength and the optimal asymmetry

Under cyclic loading, we recorded the fatigue strength of a six-strand tendon repair with different symmetry in the lengths of suture purchase in two stumps of 120 dental rolls and in 30 porcine tendons. First, the strengths of the repairs with 1, 2, 3, 4 and 5 mm asymmetry were screened using the dental rolls. The asymmetric core suture repairs were then made with a Kessler repair of equal suture purchase (10 mm) in two tendon stumps, and shifting two other Kessler repairs by 1, 3 or 5 mm, respectively, along the longitudinal axis of the tendon in relation to the first (symmetric) Kessler repair. The core repairs with 3 mm or more asymmetry in suture purchases in two tendon ends showed significantly greater fatigue strength and significantly smaller gaps compared with 1 mm asymmetry in core suture repair. Our results support that asymmetric placement of core sutures in two tendon ends favour resisting gapping at the repair site and 3 mm or more asymmetry is needed to produce such beneficial effects.

In vivo dynamic acromiohumeral distance in shoulders with rotator cuff tears

Background: There are no previous studies on the acromiohumeral distance in shoulders with large‐to‐massive full‐thickness rotator cuff tears. In this study, the acromiohumeral distance in rotator cuff tear and healthy shoulders was measured using 3D‐to‐2D model‐to‐image registration techniques. Methods: The dynamic glenohumeral kinematics during scapular plane abduction and axial rotation were analyzed in 11 rotator cuff tear patients and 10 healthy control subjects. Periodic radiographic images of scapular plane abduction and axial rotation were taken using a flat‐panel radiograph image detector. Movements of the shoulder joint were assessed using radiographic images and computed tomography‐derived digitally reconstructed radiographs. The acromiohumeral distance was defined as the shortest 3D distance between the acromion and the proximal humerus. Findings: For scapular plane abduction, the rotator cuff tear group had significantly smaller acromiohumeral distance than the control group at 15°, 30°, 45°, 60°, 75°, 135°, and 150° of humeral abduction (P < 0.05 at each measured angle). For axial rotation in the adducted position, the rotator cuff tear group had significantly smaller acromiohumeral distance than the control group at each point between −20° and 40° of glenohumeral external rotation (P < 0.05 at each measured angle). Interpretation: The minimum measured acromiohumeral distance was 0.9 mm in the rotator cuff tear shoulders and 2.1 mm in the healthy shoulders at 90° of scapular plane abduction. The findings are of clinical relevance because quantitative evaluation of the dynamic acromiohumeral distances in rotator cuff tear and healthy shoulders might provide important insight into subacromial impingement. HighlightsAcromiohumeral distance in rotator cuff tear and healthy shoulders was measured.3D‐to‐2D model‐to‐image registration techniques were performed.Acromiohumeral distance was significantly smaller in rotator cuff tear shoulders.Quantitative evaluation of acromiohumeral distance might provide important insight.

Symmetric Peripheral Running Sutures are Superior to Asymmetric Peripheral Running Sutures for Increasing the Tendon Strength in Flexor Tendon Repair

BACKGROUND The fatigue strength of three peripheral suture techniques for flexor tendon repair was compared by cyclic loading of the repairs in the porcine flexor digitorum tendon. METHODS Thirty-six tendons were sutured using only peripheral sutures with 6-0 Nylon. An initial cyclic load of 10 N for 500 cycles was applied and increased by 10 N for an additional 500 cycles at each new load until rupture. RESULTS The fatigue strength of the symmetric running peripheral suture was 85.0% and 144.8% greater than that of the two kinds of the asymmetric running peripheral sutures. CONCLUSIONS Symmetric running sutures can enhance the suture strength and appears to be a useful technique for increasing the strength of the peripheral suture.