Peter Scougall

Influence of Locking Stitch Size in a Four-Strand Cross-Locked Cruciate Flexor Tendon Repair

PURPOSE The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation. METHODS We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined. RESULTS All repairs failed by suture breakage; we noted no suture pullout. There was no difference in load to failure (71.7-71.1 N; p = .89) or stiffness (4.1-4.6 N/mm; p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55-62.2 N; p = .07). CONCLUSIONS Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.

Performance of a knotless four-strand flexor tendon repair with a unidirectional barbed suture device: a dynamic ex vivo comparison

With increased numbers of reports using barbed sutures for tendon repairs we felt the need to design a specific tendon repair method to draw the best utility from these materials. We split 30 sheep deep flexor tendons in two groups of 15 tendons. One group was repaired with a new four-strand barbed suture repair method without knot. The other group was repaired with a conventional four-strand cross-locked cruciate repair method (Adelaide repair) with knot. Dynamic testing (3–30 N for 250 cycles) and additional static pull to failure was performed to investigate gap formation and final failure forces. The barbed suture repair group showed higher resistance to gap formation throughout the test. Additionally final failure force was higher for the barbed suture group compared with the conventional repair group. When used appropriately, barbed suture materials could be beneficial to use in tendon surgery, especially with regard to early loading of the repair site and gap formation.

Cross-Sectional Area and Strength Differences of Fiberwire, Prolene, and Ticron Sutures.

PURPOSE Flexor tendons should be repaired with suture material strong enough to permit early motion and small enough for the resulting knot to allow unimpeded tendon glide and healing. This study sought to define differences in cross-sectional area and knotted tensile strength among Fiberwire, Prolene, and Ticron sutures. METHODS Five strands, each of 3-0 and 4-0 Prolene, Ticron, and Fiberwire sutures, were embedded in polymethylmethacrylate and sectioned in a linear precision saw to obtain 10 cross-sections of each material and size. These were examined by scanning electron microscopy and digitally analyzed for cross-sectional areas. Ten strands of each suture material and size had a single throw knot placed, and they were loaded to failure in a micromechanical tester. RESULTS Prolene and Ticron cross-sections were circular. Fiberwire was noncircular. The 3-0 Fiberwire sutures had greater cross-sectional area than the 3-0 Ticron sutures (p < .001), which in turn were larger than 3-0 Prolene (p < .05). The 4-0 Fiberwire cross-sectional area was also greater than that of 3-0 Ticron and Prolene (p < .05). After relating knotted tensile strength to cross-sectional area, Fiberwire was 10% stronger than Prolene, and 25% stronger than Ticron. CONCLUSIONS Fiberwire is not only stronger, but also larger than other sutures in the same or even higher suture size category. Failure to meet the United States Pharmacopeia standards for suture diameter is declared in the product information sheet, although surgeons may not be aware of these size variations. Suture size definitions are currently based on diameter, a consistent measure for circular monofilament sutures, but not for braided or noncircular sutures.

Lunate trabecular structure: a radiographic cadaveric study of risk factors for Kienböcks disease

The aetiology of Kienböcks disease is unknown. Ulnar variance and lunate shape are possible mechanical risk factors. This study assessed the trabecular structure in 29 cadaveric lunates using microCT and correlated this with ulnar variance and lunate shape on plain radiographs and with bone density assessed using conventional CT. The bony trabeculae within the lunate were shown to run almost perpendicular to the proximal and distal joint surfaces in the coronal plane; these trabeculae met the subchondral bone at an angle between 72–102°. In lunates whose proximal and distal articular surfaces are not parallel, the trabecular orientation may be less able to resist compressive forces and more susceptible to fracture.

Lunate trabecular structure: a cadaveric radiograph study of risk factors for Kienböck's disease

The aetiology of Kienböcks disease is unknown. Ulnar variance and lunate shape are possible mechanical risk factors. This study assessed the trabecular structure in 29 cadaveric lunates using microCT and correlated this with ulnar variance and lunate shape on plain radiographs and with bone density assessed using conventional CT. The bony trabeculae within the lunate were shown to run almost perpendicular to the proximal and distal joint surfaces in the coronal plane; these trabeculae met the subchondral bone at an angle between 72–102°. In lunates whose proximal and distal articular surfaces are not parallel, the trabecular orientation may be less able to resist compressive forces and more susceptible to fracture.

The Interlocking Modification of the Cross Locked Cruciate Tendon Repair (Modified Adelaide Repair): A Static and Dynamic Biomechanical Assessment.

The 4-strand cross-locked cruciate flexor tendon repair technique (Adelaide technique) has been shown to have comparably high resistance to gap formation and ultimate tensile strength. This study aimed to determine whether an interlocking modification to the Adelaide repair would impart improved biomechanical characteristics. Twenty four sheep flexor tendons were harvested, transected and repaired using either standard or modified Adelaide techniques. Repaired tendons were cyclically loaded. Gap formation and ultimate tensile strength were measured. Additionally, suture exposure on the tendon surface was determined. There was a statistically significant increase in resistance to gap formation in the early phase of cyclic loading within the modified Adelaide group. In the later stages of testing no significant difference could be noted. The average final load to failure in the modified group was higher than the standard group but this did not achieve statistical significance. Interlocking suture techniques in four strand tendon repair constructs can improve gapping behavior in the early phase of cyclic loading.

Animal Models for Tendon Repair Experiments: A Comparison of Pig, Sheep and Human Deep Flexor Tendons in Zone II

BACKGROUND This laboratory study compared pig, sheep and human deep flexor tendons in regards to their biomechanical comparability. METHODS To investigate the relevant biomechanical properties for tendon repair experiments, the tendons resistance to cheese-wiring (suture drag/splitting) was assessed. Cheese-wiring of a suture through a tendon is an essential factor for repair gapping and failure in a tendon repair. RESULTS Biomechanical testing showed that forces required to pulling a uniform suture loop through sheep or pig tendons in Zone II were higher than in human tendons. At time point zero of testing these differences did not reach statistical significance, but differences became more pronounced when forces were measured beyond initial cheese-wiring (2 mm, 5 mm and 10 mm). The stronger resistance to cheese-wiring was more pronounced in the pig tendons. Also regarding size and histology, sheep tendons were more comparable to human tendons than pig tendons. CONCLUSIONS Differences in tendon bio-properties should be kept in mind when comparing and interpreting the results of laboratory tendon experiments.

Huckstep Titanium Locking Compression nail for femoral fractures in Paget’s disease

Objectives Closed or open reduction of femoral fractures, delayed or nonunion secondary to Paget’s disease. Internal fixation without or with compression using the Huckstep Titanium Locking Compression nail. Bone grafting.

Behandlung von Femurfrakturen beim Paget-Syndrom mit dem Verriegelungsnagel nach Huckstep

ZusammenfassungOperationszielOffene oder geschlossene Reposition von Femurfrakturen bei Patienten mit Paget-Syndrom. Stabilisierung mit einem Titan-Kompressionsverriegelungsnagel nach Huckstep mit oder ohne interfragmentäre Kompression. Fakultative Spongiosatransplantation.IndikationenFemurfrakturen, einschließlich Trümmerbrüchen des Schaftes und subtrochantären Frakturen, verzögerte Frakturheilung und Pseudarthrosen des Femur beim Paget-Syndrom.KontraindikationenAbsolute: Allgemeine Operationsunfähigkeit.Relative: Starke Femurkrümmung.OperationstechnikLateraler Zugang für proximale Femurfrakturen, anterolateraler Zugang für Frakturen im mittleren und distalen Drittel. Aufbohren des Markkanales. Einbringen des Nagels und Verriegelung mit oder ohne Kompression. Ein besonderer Nagel wird zur Stabilisierung von Frakturen des Femurschaftes und Schenkelhalses angewandt. Spongiosatransplantation.ErgebnisseBericht über 25 Frakturen bei 23 Patienten (14 Frauen, neun Männer), von denen 15 schon früher erfolglos operativ behandelt worden waren. 21 Frakturen bei 19 Patienten wurden nachuntersucht. Zwölf Frakturen heilten innerhalb von sechs Monaten und weitere fünf innerhalb eines Jahres. Die Heilung von drei Frakturen dauerte länger als ein Jahr. Eine Pseudarthrose wurde beobachtet.