3-loop Pulley Research Articles

Biomechanical Comparison of a 3-Loop Pulley and a 4-Loop Pulley Suture for Tenorrhaphy in the Canine Gastrocnemius Tendon.

The aim of this study was to compare a 3-loop pulley (3LP) suture pattern with a 4-loop pulley (4LP) suture pattern for the tenorrhaphy of the canine gastrocnemius tendon STUDY DESIGN: Randomized, cadaveric, biomechanical study of 30 canine gastrocnemius tendons. Tendons were transected and repaired with either 3LP or 4LP suture pattern with 2-0 polypropylene. A tensile load was applied at 25 mm/min until construct failure. The load required to form a 1 mm gap, 3 mm gap and maximum load at failure was recorded and compared between groups. The estimated mean load to form a 1 mm gap for the 3LP and 4LP was 28.4 N (95% confidence interval [CI]: 24.0-32.6N) and 45.5 N (95% CI: 40.7-50.1N) respectively. The 4LP mean load to form a 1 mm gap was 17.1 N (95% CI: 11.7-22.5N) greater than the 3LP. The estimated mean load to form a 3mm gap for the 3LP and 4LP was 39.7 N (95% CI: 34.1-45.4N) and 55.0 N (95% CI: 49.3-60.9N) respectively. The mean load to form a 3mm gap was 15.3 N (95% CI: 8.5-21.9N) greater in the 4LP than the 3LP. The estimated mean load for failure in the 3LP and 4LP was 41.2 N (95% CI: 35.6-46.9 N) and 54.3 N (95% CI: 48.7-60.3 N) respectively. A 4LP pattern was biomechanically superior to a 3LP pattern, as demonstrated by a greater load required to form both a 1 and 3 mm gap and a greater load for failure CLINICAL SIGNIFICANCE: A 4LP suture pattern better resists gap formation and requires greater load prior to construct failure compared with a 3LP, in this canine gastrocnemius model.

Ex vivo biomechanical characteristics and effects on gap formation of using an internal fixation plate to augment primary three-loop pulley repair of canine gastrocnemius tendons.

To evaluate the effects of using an internal fixation plate to augment primary 3-loop pulley (3LP) repair of canine gastrocnemius tendons (GTs). 48 cadaveric GTs from 24 adult dogs. GTs were dissected free from other tissues, transected, and randomly assigned to 4 groups (n = 12/group). GTs were repaired with 2-0 polypropylene with a 3LP repair alone or a 3LP repair augmented with a 3-hole veterinary cuttable plate (3VCP), a 5-hole veterinary cuttable plate (5VCP), or a 7-hole veterinary cuttable plate (7VC P). Biomechanical loads, construct stiffness, gap formation, and failure modes were compared between groups. Yield, peak, and failure loads were all significantly increased for the 5VCP and 7VCP groups, compared with the 3LP alone group. Increasing plate length from 3VCP to 5VCP and from 3VCP to 7VCP increased yield, peak, and failure loads. No differences were found between the 3LP and 3VCP groups with regard to yield and peak loads, but failure load was increased in the 3VCP group. Loads to create 1-mm and 3-mm gaps were significantly greater for the 5VCP and 7VCP groups, compared with the 3LP alone and 3VCP groups. Mode of plate attachment failure differed among groups. Tendon plate augmentation may be a viable surgical option to increase the strength of the tenorrhaphy in dogs. However, in vivo studies evaluating the effects of plate augmentation on the tendon blood supply and progression of healing are needed prior to clinical application.

Ex-Vivo Evaluation of a Modified Teno Fix(®) Device Repair Pattern Versus a 3-Loop Pulley for Repair of Equine Flexor Tendons.

To compare the load to ultimate failure, load to a 2 mm gap, mode of failure, and gap at failure (mm) of the Teno Fix(®) (TF) to the 3-loop pulley (3LP) for repair of equine tendon lacerations. The use of 4TF devices versus 5TF devices on load to ultimate failure and load to a 2 mm gap was also compared. Ex vivo biomechanical study; unbalanced incomplete block (horse) design. Cadaveric equine forelimb superficial digital flexor tendon (n = 20 paired tendons). Ten tendon pairs were selected randomly and repaired with a 3LP and 4TF pattern, and 10 tendon pairs repaired with a 3LP and 5TF pattern. Load to ultimate failure, load to a 2 mm gap, mode of failure, and gap at failure were obtained using materials testing. The 3LP had a significantly greater ultimate load to failure (P < .001, respectively) and a significantly higher load to a 2 mm gap than both TF repairs (P < .001, respectively). The most frequent mode of failure was suture pull-out for the 3LP and anchor pull-out for the TF. Gap at failure was significantly larger in the 3LP than both TF repairs (P < .001). The ultimate load to failure was significantly higher for the 5TF than the 4TF (P = .004) but there was no significant difference in load to a 2 mm gap, or gap at failure between both TF repairs (P = .11, P = .15, respectively). Neither TF repair was stronger than the 3LP in load to ultimate failure and load to a 2 mm gap. Addition of a fifth TF device significantly increased the load to ultimate failure but did effect the load to a 2 mm gap over the 4TF.

Biomechanical Testing of a Novel Tendon Implant Device for the Repair of Equine Flexor Tendon Lacerations

To compare in vitro strength and failure characteristics of a tendon implant against a 3 loop pulley suture pattern for equine superficial digital flexor tendon (SDFT) laceration repair. Experimental. Cadaveric equine forelimb SDFT (n = 16). One tendon of each of 8 pair of SDFT was randomly selected for repair with either the 3-loop pulley (3LP) suture pattern using 2 polydioxanone or with 4 stainless steel suture and anchor implants (SA). Ultimate load to failure, mode of failure, gap at failure, and load to 2 mm gap were obtained using a materials testing system synchronized with a high-speed camera. Statistical evaluation was made using Student's t-test; significance was set at P ≤ .05. The 3LP failed at a significantly (P = .0001) greater load (363.5 ± 83.7 N) than SA (132.4 ± 26.8 N), but the load to a 2 mm gap (3LP = 164.9 ± 67.7 N, SA = 114.5 ± 21.5 N) was not significantly different (P = .09). Failure mode was by suture pull out and anchor pull out respectively. The gap at failure was significantly larger in the 3LP than in SA repair (P = .000005). Both the SA repair and the 3LP resisted similar tension to 2 mm gap. However, the ultimate load to failure of the SA repair was only 36% that of the 3LP repair.

Biomechanical Testing of a Novel Suture Pattern for Repair of Equine Tendon Lacerations

To compare in vitro biomechanical properties of a novel suture pattern to a current standard for primary repair of equine superficial digital flexor tendon (SDFT) laceration. In vitro randomized, paired design. Cadaveric equine forelimb SDFT (n = 24). The 3-loop pulley (3LP) and 6-strand Savage (SSS) suture patterns were applied to transected equine SDFT. Ultimate failure load, stiffness, mode of failure, and load required to form a 3-mm gap were obtained using a materials testing system and synchronized high-speed video analysis. Statistical comparisons were made using Student's t-test, with significance set at P < .05. The SSS repair failed at a higher ultimate load (421.1 N ± 47.6) than the 3LP repair (193.7 N ± 43.0; P < .001). There was no significant difference in stiffness (P = .99). Failure mode was suture breakage for all SSS repair and suture pull through for all 3LP repair. The maximum load to create a 3-mm gap in the SSS repair (102.0 N ± 22.4) was not significantly different from the 3LP repair (109.9 N ± 16.0; P = .27). SSS tenorrhaphy has improved strength and resistance to pull through compared with 3LP for equine SDFT in a single load-to-failure test. Load required to form a 3-mm gap was not significantly different between SSS and 3LP.

An Ex Vivo Biomechanical Study Comparing Strength Characteristics of a New Technique with the Three‐Loop Pulley for Equine Tenorrhaphy

To test single cycle to failure tensile strength characteristics of 6 suture material-pattern combinations in equine superficial digital flexor (SDF) tenorrhaphy, specifically to compare a 10-strand modification of the Savage core suture technique with the 3-loop pulley technique. Ex vivo mechanical experiment comparing 3 different suture patterns with 2 different materials. Forelimb and hindlimb SDF tendons (n=48) harvested from adult Thoroughbred and Standardbred horses of mixed age and gender. Six suture material-pattern combinations were evaluated: (1) 10-strand Savage, size 2 polydioxanone (PDS); (2) 10-strand Savage, size 2 polyglactin 910 (PG910); (3) 10-strand Savage, size 2 PDS with Lin-locking epitenon suture, size 2-0 PDS; (4) 10-strand Savage size 2 PG910 with Lin-locking epitenon suture, size 2-0 PDS; (5) 3-loop pulley, size 2 PDS; and (6) 3-loop pulley, size 2 PG910. Maximum load at failure (N), gap at failure (mm), and mode of failure (suture breakage or pull through) were evaluated for each of the 6 suture material-pattern combinations and underwent statistical analysis to determine significance of differences and interactions of the measured data. The 10-strand Savage technique failed at a mean load of 872 (804-939, 95% CI). The 10-strand Savage with Lin-locking failed at a significantly greater mean load of 998 (930-1065, 95% CI). The 3-loop pulley pattern failed with a mean load of 337 (270-405, 95% CI). There were significant interactions between the technique and suture material used. The 10-strand Savage technique for repair of transected cadaver SDF tendons has superior strength characteristics with or without the epitenon suture when compared to the 3-loop pulley. Suture material and pattern interactions were observed with PG 910 conferring higher strength for the 10-strand Savage whereas PDS did so for the 3-loop pulley.

In Vitro Biomechanical Comparison of Polypropylene Mesh, Modified Three‐Loop Pulley Suture Pattern, and a Combination for Repair of Distal Canine Achilles' Tendon Injuries

To compare mechanical stability between a novel polypropylene mesh repair (Mesh), a modified 3-loop pulley suture (Suture), and a combination of the techniques (Suture+Mesh) for the repair of distal canine Achilles' tendon ruptures. In vitro mechanical evaluation. Cadaveric canine Achilles' tendon/calcaneus units (n=34). Constructs were loaded under tension to failure in a materials testing machine with synchronized kinematic analysis. Ultimate load to failure, global construct stiffness, and force required to reach 1 and 3 mm gap formation was recorded. Ultimate load to failure was greatest for the Suture+Mesh group and lowest for the Suture group. The Suture+Mesh technique afforded a significantly greater global stiffness than the Suture or Mesh treatments. Force to generate 1 and 3 mm gap formation was greatest with the Suture group. The Suture+Mesh group had the highest ultimate load to failure and afforded the greatest global stiffness though it had no added benefit to resist local gap formation at the repair. Achilles' ruptures repaired with suture can be augmented with mesh to increase the ultimate load to failure, but as currently tested, there was a decrease in resistance to gap formation At this time we cannot recommend Mesh or the Suture+Mesh techniques without further testing.

Achilles Tendon Repair in Dogs Using the Semitendinosus Muscle: Surgical Technique and Short‐Term Outcome in Five Dogs

To describe augmentation of primary Achilles tendon repair using suture with a semitendinosus muscle flap and report outcome in 5 dogs. Prospective clinical study. Dogs (n=5) with Achilles tendon rupture (n=6). After tendon repair with #2 polypropylene in a 3-loop pulley suture pattern, the lateral one-half of the semitendinosus muscle was transected from the ischium, rotated distally then sutured with #2 polypropylene to the calcaneus in a 3-loop pulley pattern. The epitenon was sutured to the muscle flap fascia with interrupted sutures. All dogs had a bivalved cast for 2 weeks then a cranial splint for 2-6 weeks. Lameness scores (0=stands and walks normally to 4=non-weight-bearing lameness, plantigrade stance on affected pelvic limb) were determined every 2-3 weeks postoperatively for 12 weeks. Outcome was determined from telephone questionnaire of owners. Four had lameness scores of 0, the 5th had a score of 1 at 12 weeks. Three owners were very satisfied with outcome. Minor complications included cast sores (2 dogs), infection (2), and acute swelling (1); 1 major complication occurred (infection resulting in reoperation). Semitendinosus flap augmentation resulted in early return to function without prolonged postoperative immobilization. Three dogs returned to full work/activity after repair. Augmentation of primary Achilles tendon repair with a semitendinosus flap can be considered in dogs with chronic rupture but further investigation of the long-term outcome using this technique is needed.

Ex Vivo Strength Comparison of Bioabsorbable Tendon Plates and Bioabsorbable Suture in a 3‐Loop Pulley Pattern for Repair of Transected Flexor Tendons from Horse Cadavers

To test the failure strength and energy of 2 bioabsorbable implants applied to transected deep digital flexor tendons (DDFT) from adult horses. Ex vivo biomechanical experiment. Twelve pairs of deep digital flexor tendons harvested from the forelimbs of fresh equine cadavers. Poly-L-lactic acid tendon plates were custom manufactured for application to the cylindrical surface of an adult equine deep digital flexor tendon. Twelve pairs of DDFTs were transected 2 cm distal to the insertion of the distal check ligament of the deep digital flexor tendon. One tendon of each pair was randomly selected for repair with a biodegradable plate or a 3-loop pulley method. Size 2 polydioxanone suture was used in both repairs. Repairs were tested in tension to failure, with peak force (PF) and total energy (TE) at repair failure recorded in Newtons (N) and Joules (J), respectively. A paired t-test was used for statistical evaluation with a significant level set at P< or = .05. Mean+/-SD PF for failure of plated tendons (1507.08+/-184.34 N) was significantly greater than for sutured tendons (460.86+/-60.93 N). TE was also significantly greater for failure of plated tendons versus sutured tendons. Plate fixation of transected cadaver DDFTs appear to have superior immediate failure strength than 3-loop pulley repairs. Whereas in vivo testing is required, a bioabsorbable tendon plate may provide initial increased strength to support tendon healing and decrease external coaptation requirements.

Biomechanical and Clinical Evaluation of a Modified 3‐Loop Pulley Suture Pattern for Reattachment of Canine Tendons to Bone

To describe a modified 3-loop pulley suture pattern for the reattachment of canine tendons to bone along with a biomechanical comparison with the locking-loop suture. In vitro biomechanical study and clinical case report. Biomechanical study: 10 paired gastrocnemius tendons and calcaneii harvested from 5 canine cadavers. a Doberman with avulsion of the gastrocnemius tendon of insertion. Biomechanical study: paired tendons were reattached to the calcaneus with either a modified 3-loop pulley pattern or a locking-loop pattern. Tensile loading to failure was performed. A direct, non-contact, method of gap measurement, using digital video, was used to measure gap formation. Load required to initiate gap formation (defined as load at a 1 mm gap) and to produce a 3 mm gap was evaluated in addition to maximum load and gap at failure. Mean (+/-SEM) 1 mm gap loads were 31.0+/-4.2 and 17.2+/-2.5 N, mean 3 mm gap loads were 49.1+/-2.4 and 28.9+/-3.2 N, and mean maximum loads were 72.9+/-4.3 and 55.8+/-2.2 N for the modified 3-loop pulley suture and the locking-loop suture, respectively. These differences were statistically significant (P<.05). The gap at failure was similar for both repairs. The clinical case remained sound 7 months postoperatively. A modified 3-loop pulley pattern is biomechanically superior to a locking-loop pattern for reattachment of the canine gastrocnemius tendon to bone and may be suitable for clinical use. Tendon repairs with a gap >3 mm are reported to be at increased risk of rupture during the first 6 weeks postoperatively. A modified 3-loop pulley pattern resists gap formation better than a locking-loop pattern.