Cylinder-Shaped Bone Graft for Scaphoid Nonunion.

BACKGROUND: Wedge-shaped bone grafts that are internally fixed by a Herbert-type screw are a well-established surgical treatment for scaphoid nonunion. A procedure using cylinder-shaped bone grafts was also reported, but preoperative wrist functions were not assessed. In addition, it was not reported whether the humpback deformity of the scaphoid nonunion was corrected. The purpose of the current study was to compare preoperative wrist functions in cases of scaphoid nonunion with those observed at final follow-up, using cylinder-shaped bone grafts The humpback deformity of the scaphoid nonunion was also evaluated. METHODS: We conducted a retrospective study to examine operative outcomes from 2008 to 2015. Twelve wrists in 12 patients (average age, 41 years; range, 17-67), with a mean follow-up of 19 months, were included in the current study. Cylinder-shaped bone grafts were obtained from the iliac crest with a newly designed trephine and fixed with a Herbert-type screw. We reviewed both the preoperative wrist functions and those obtained at final follow-up. RESULTS: Union was achieved in 11 of 12 nonunion cases. Preoperative wrist functions, except for the range of wrist motion, significantly improved by final follow-up. CONCLUSIONS: We conclude that the use of cylinder-shaped bone grafts improves preoperative wrist functions in cases of scaphoid nonunion.

Optimum suture material for locking technique in tendon repair: effects of suture friction in mobilization.

BACKGROUND: The 2-strand side-locking loop technique allows secure locking formation easily, yielding maximum tensile force. However, not all suture materials are suitable for this technique. METHODS: The bovine gastrocnemius tendons were transected and repaired end-to-end by the side-locking loop technique using USP2 braided polyblend, braided polyester, monofilament nylon, braided nylon, or monofilament absorbable polydioxanone sutures. A repetitive loading protocol from 10N to 100N was used, and the loading was repeated 10,000 times. In ruptured samples during the repetitive loading test, the number of loading was recorded. In samples which did not rupture, the ultimate tensile strength was measured after repetitive loading. After testing, ruptured sutures were examined microscopically. For comparison of ultimate tensile strength before and after repetitive loading, we performed a one-time loading test on samples which did not undergo the repetitive loading. FINDINGS: With monofilament nylon, braided nylon, or monofilament absorbable polydioxanone, suture rupture occurred during repetitive loading. In contrast, no suture rupture occurred with braided polyblend or braided polyester. Microscopic observation showed abrasion of the surface in braided polyester, though the friction effects were not seen with braided polyblend. The mean ultimate tensile strength before and after repetitive loading was 395N and 399N, respectively, for braided polyblend. For braided polyester, they were 208N and 174N, respectively. INTERPRETATION: Braided polyblend suture material has an excellent resistivity to friction and is suitable for the side-locking loop technique.

Optimally strong tendon repair using braided polyethylene strand: 2-strand heavy-gauge locking technique vs. multiple-strand technique.

BACKGROUND: We conducted an in vitro study to investigate the strongest tensile force for tendon repair using a braided polyblend suture strand material, employing a 2-strand heavy-gauge side-locking loop technique, comparing it with other multiple-strand repair techniques. METHODS: Using the United States Pharmacopeial Convention (USP) 2 and 5-sized braided polyblend strands, 3 repair techniques were evaluated after suturing transacted bovine gastrocnemius tendons: 2-strand side-locking loop, 4-strand Savage, and 6-strand Yoshizu-1 techniques. Ultimate tensile force and mode of failure at strand rupture were examined (n=5 for each combination). FINDINGS: The ultimate tensile forces was observed with USP2-side-locking loop (mean 402 N), USP5-side-locking loop (mean 748 N), USP2-Savage (mean 552 N), and USP2-Yoshizu-1 Groups (mean 598 N). The USP5-side-locking loop Group had proportionally greater ultimate tensile force than the USP2-side-locking loop Group. However, with the number of strands doubled or tripled, resulting strengths were only 1.4 times or 1.5 times greater. The mode of failure was rupture at the locking loop portion in all side-locking loop Group samples, pull-through of the strand from the tendon in all Savage Group samples, and either pull-through of the strand from the tendon (40%) or rupture at the knot (60%) in the Yoshizu-1 Group samples. INTERPRETATION: Greater numbers of strands do not achieve proportionally greater strong tensile force in the repaired tendon. When employing the side-locking loop technique for secured locking formation, the heavier strand yields markedly greater tensile force even with only 2 strands, and thus greater holding ability.

Optimum location of knot for tendon surgery in side-locking loop technique.

BACKGROUND: Although various tendon repair techniques have been reported to achieve stronger repair, suture failures tend to occur near the knot. We experimentally investigated whether the location of a single core suture knot affects the biomechanical properties of the repair. METHODS: Transected bovine tendons (male Japanese black cattle, 24 months old) of the medial gastrocnemius (9-11 x 14-16 mm in diameter) were sutured with the side-locking loop technique using a USP2-sized polyethylene and polyester multifilament suture or polyester multifilament suture. The knot was made using 7 simple square ties (a surgeon's knot plus 5 ties) at three locations; on the loop, between the tendon stumps, or between the loops burying the knot in a tendon slit using a scalpel. A cyclical loading protocol from 10N to 100N was used and the loading was repeated 10,000 times. FINDINGS: The gap was most decreased and the ultimate strength was most increased when the knot was located between the loops when using a polyethylene and polyester multifilament suture. Cross-sectional area of the tendon showed the ratio of the buried knot relative to the tendon was only 1.6-2.3%, and the polyethylene and polyester multifilament suture was very durable against frictional abrasion. INTERPRETATION: We found that the knot between the loops, buried in the bovine tendon provided the optimum results.

Biomechanical differences resulting from the combination of suture materials and repair techniques.

BACKGROUND: Many suture materials and repair techniques have been applied in clinical tendon surgery. However, no recommendation is available concerning the choice of suture materials and repair techniques except in a few experimental studies. The purpose of the current study is to show the biomechanical difference resulting from the combination of suture materials and repair techniques. METHODS: The gastrocnemius tendons of 24-week-old cattle (diameter 14-16x9-11 mm) were repaired with application of a single locking, multiple locking, single grasping, or multiple grasping technique using a USP2 suture thread of either braided polyblend polyethylene, polyester, polydioxanone, or nylon. Therefore, a total of 16 combinations were made, with eight specimens for each combination. The specimen was set in an Instron tensiometer to measure the gap length after repetitive tensile loading 500 times (10-100 N). RESULTS: The single locking technique using braided polyblend polyethylene provided the smallest gap (4.5+/-0.5 mm). Other techniques using the same material resulted in a large gap (10.0-11.8 mm). The polyester provided a relatively smaller gap length, irrespective of the repair technique (7.4-8.8 mm). Polydioxanone and nylon tended to result in a large gap (9.3-12.3 mm and 8.4-10.6 mm, respectively). CONCLUSIONS: Mechanical properties of each tendon suture depended on the particular combination of suture materials and repair techniques. The combination of braided polyblend polyethylene and single locking technique provided the highest antigap strength.

Aggressive active mobilization following zone II flexor tendon repair using a two-strand heavy-gauge locking loop technique.

In vitro and in vivo experimental studies have shown that a new two-strand technique increases the tensile strength of flexor tendon repair and eliminates gap formation at the healing repair site. The purpose of the current study was to clinically evaluate the new technique, followed by an aggressive active mobilization program. Seven digits with zone II flexor tendon lacerations were treated using the technique, employing a heavy (2-0) braided polyester suture. The patients were encouraged to perform active mobilization of the injured digits by themselves with almost a full range of flexion and extension after they were instructed by the surgeon for few days from the first postoperative day. All patients were followed up for at least 6 months, except for one, with whom contact was lost in 14 weeks postoperatively. Six of the seven digits were evaluated as excellent in 6 months by the original Strickland criteria, thus showing that the combination of the new repair technique and aggressive active mobilization is effective for zone II flexor tendon repair.