Ch 15-17, 68, 69 Papers

Gillen et al, 2020

Forwarder Knot

Objective: Evaluate the strength and size of Forwarder end knots modified to end continuous suture lines compared with Aberdeen, square, and surgeon’s knots

Results:

• In all suture types and number of throws, Forwarder end knot knot holding capacity (KHC)/Relative knot security (RKS) was 28-66.99% (1.2-1.6 fold) stronger compared with square/surgeon’s knots and 0-8% weaker than Aberdeen knots

• For #2 PDS, Forwarder end knots had 10% (1.1 fold) higher KHC/RKS compared with Abderdeen knots

• In #2 and #3 polyglactin 910, Forwarder end knot KHC/RKS values were not different from those of Aberdeen knots

• Forwarder end/Aberdeen knots failed by suture breakage at the knot, whereas some square/surgeon’s knots unraveled

• Forwarder end knots in #2 and #3 polyglactin 910 were 21.1-44.4% (1.2-1.4 fold) smaller compared with square/surgeon’s knots

• Forwarder end knots in #2 and #3 polyglactin 910 were 40-99% (1.4-2 fold) larger compared with Abderdeen knots

• Forwarder end knots tied in #3 polyglactin 910 had higher KHC compared with Forwarder end knots in both #2 PDS and #2 polyglactin 910

• Forwarder end knots tied in #2 polyglactin 910 had higher KHC compared with #2 PDS

• No difference in RKS between Forwarder end knots tied in different suture materials

• All Forwarder end knots in all types of suture were 13.1-47% (1.1-1.5 fold) heavier than all other knot types in the same suture material

Conclusions: Forwarder end knots provided increased KHC/RKS compared with square/surgeon’s knots but not compared with Aberdeen knots tied in polyglactin 910. Forwarder end knots should be considered for closures when suture is placed under tension

Aberdeen knots had the smallest volume and square and surgeon’s knots had the largest volume. Aberdeen knots had the lowest weight and Forwarder end knots had the highest weight

Hale et al, 2021

Suture Patterns for Tendon Plating

Objective: Determine the influence of suture patterns on resistance to gap formation after tendon plating

Results:

• Constructs prepared with hybrid and figure-8 patterns sustained over 2x higher forces before gap formation compared to those prepared with a simple interrupted pattern

• No difference was identified between tendons whose plate was secured with hybrid or figure-8 suture patterns

• Mode of failure between groups did not differ

Conclusion: The figure-8 and hybrid patterns improved the resistance to gap formation of plated tendons compared to an alternating simple interrupted pattern. Figure-8 and hybrid patterns should be considered over simple interrupted patterns to improve resistance to gap formation in horses undergoing tendon plating.

Martinez-Lopez, Brown, and Werre, 2021

Colic incision closure with n-butyl cyanoacrylate vs staples

Objective: Compare the prevalence of incisional complications after skin closure with n-butyl cyanoacrylate (NBC) or stainless-steel skin staples after ventral midline celiotomy for colic surgery in the horse

Results:

• The skin was closed with staples in 51.8% and NBC in 48.2%

• Incisional complications were recorded in 17.5% of horses including 19.1% of closures with staples and 15.9% of closures with NBC

• Overall prevalence of SSI was 11.7%

• Complications occurred before discharge in 6.4% and after discharge in 9.6%

  • Of the horses with in-hospital complications, 8 were closed with staples and 6 with NBC

  • The most common in-hospital incisional complication was SSI in 78.6%

  • Median time to recognition of SSI was 7 days after surgery

  • Of the horses with post-discharge complications, 9 were closed with staples and 7 were closed with NBC

• Four horses with in-hospital incisional infections developed a hernia after discharge

• Increased PCV at admission was a risk factor for in-hospital incisional complications and in-hospital incisional complications were associated with posthospital discharge incisional complications

  • For every 10% increase in PCV there was a 2.3 fold increase in the odds of developing an in-hospital incisional complication

  • Horses with in-hospital incisional complications had a 12.1 fold increase in the odds of developing a posthopsital discharge incisional complication

• Horses that had skin closure with staples had a longer anesthesia time and were hypotensive during anesthesia

Conclusion: Occurrence of incisional complications did not differ between NBC and SS

Tobias et al, 2020

Tensile Properties of Absorbable Monofilament Suture

Objective: Compare tensile properties of synthetic, absorbable, monofilament suture material before and after incubation in phosphate-buffered saline (PBS)

Results:

• Size, suture material, and size x suture material interaction influenced maximum breaking load, maximum elongation, and modulus of elasticity

• At baseline, 2-0 and 3-0 Maxon had the highest breaking loads for their size, and 2-0 PDSII and 3-0 Securodox had the lowest

• Maxon 2-0 and 3-0 had the greatest elongations for their size, and 2-0 Biosyn and 3-0 Securocryl had the least

• Biosyn 2-0 and 3-0 had the highest modulus of elasticity

• With incubation, 2-0 Maxon, 2-0 and 3-0 PDSII, and 2-0 and 3-0 Securodox maintained or gained strength over 4 weeks

• Strengths of 2-0 and 3-0 Biosyn and 3-0 Maxon were maintained for 2 weeks while Monocryl and Securocryl lost 20-44% of baseline strength within 1 week and 60-72% within 2 weeks

• Day 7 strengths of 2-0 Biosyn and 2-0 Monocryl were greater than strength of Monocryl at days 7 and 14 and greater than strenght of 3-0 PDS II, 3-0 Securodox, and 3-0 Securocryl at baseline and days 7 and 14

• Initial baseline strength must be considered when comparing percentage strength retention of sutures over time

Conclusion: Suture tensile properties varied with suture size, composition, and brand. At baseline, Maxon suture had the greatest strength and elongation, and Biosyn had the greatest stiffness

Wetherall et al, 2020

Self-locking and Surgeon’s Knots

Objective: Compare the biomechanical properties and healing of ventral midline celiotomies closed with a self-locking knot combination and forwarder start and Aberdeen end (F-A) vs a traditional knot combination and surgeon’s start and end (S-S)

Results:

• Forwarder start and Aberdeen end and S-S horses had less tensile strength compared with control horses

• No differences were detected between treatment groups for any variable evaluated, including tensile strength, location of failure, and histologic healing at the knot

• The probability of having worse incisional edema did not differ between the groups

• No difference in drainage location or probability of worse discharge character between the two groups was observed

Conclusion: Closure of ventral midline celiotomies with self-locking knots resulted in biomechanical and healing features similar to those with a traditional closure technique, with neither restoring the tensile strength of the linea alba. No difference in incisional complications in the early postoperative period.

Fowler et al, 2019

Acellular Equine Amniotic Allografts

Objective: To characterize the growth factors contained in equine amniotic membrane allograft (eAM;StemWrap scaffold and StemWrap+ injection) and to evaluate the effect of eAM on equine distal limb wound healing

Results:

• StemWrap+ contained moderate concentrations of TGF-B1, VEGF, and PGE2

• Treatment of wounds with eAM did not affect time to healing or histologic quality of the healing compared with other groups but was associated with increased granulation tissue production early in the study, particularly on day 7

Conclusion: Application of eAM resulted in increased granulation tissue production with maintaining appropriate healing of experimental wounds. Use of eAM is likely most beneficial for substantial wounds in which expedient production of large amounts of granulation tissue is desirable

McCoy et al

Preparation and Storage of Equine Amnion

Objective: Determine the influence of tissue preparation and long-term storage methods on structural integrity and risk of bacterial contamination of equine amnion

Results:

• Baseline bacterial levels ranged from <200 to >150,000 cfu/mL

• None of the potentially pathogenic bacteria in baseline samples were subsequently cultured throughout the study

• Nonpathogenic bacteria (median 20 cfu/mL), most commonly Bacillus sp (71%), were cultured sporadically across storage conditions

  • 28.7% of samples were culture positive

• Tissue architecture was minimally affected histologically by processing protocol, storage temperature, or storage duration

• Storage temperature was not significantly associated with risk of bacterial contamination in any model

• Storage solution was significantly associated with the risk of bacterial contamination, samples that were stored in saline were more likely to be culture positive compared with those stored in chlorhexidine or acetic acid

• Samples that were stored in chlorhexidine were more likely to be culture positive compared with those that were stored in acetic acid

• Samples stored in saline were more likely to show autolysis and have a higher total histopathology score compared with samples that were stored in chlorhexidine or acetic acid

Conclusion: The processing protocols in this study (0.05% chlorhexidine or 2% iodine/0.25% acetic acid) resulted in minimal bacterial contamination or loss of structural integrity of equine amnion stored for up to 12 months at 4*C, -20*C, or -80*C. Amnion collected during the foaling season may be stored for up to 12 months without significant bacterial contamination or structural alterations

Noll et al, 2021

PHMB impregnated gauze

Objective: Determine the ability of 0.2% polyhexamethylene biguanide (PHMB) impregnated gauze to inhibit the growth of bacteria isolated from equine infected sites

Results:

• 0.2% PHMB impregnated gauze inhibited the growth of Staphylococcus spp by 33-83.1% and E. coli by 6.5-37%.

• There was no inhibition of growth of PSeudomonas aeruginosa or either Enterococcus spp

Conclusion: The 0.2% PHMB-impregnated dressing inhibited the growth of staphylococcal and E. coli isolates but the magnitude of inhibition varied between strains.

Perez-Nogues et al, 2018

Effects of Water Temperature and Curing Time on Fiberglass Casts

Objective: Determine the effects of water temperature and cure time on cast strength

Results:

• Mean time to complete the construct was 2.2 minutes for warm water and 2.3 minutes for cold water

• Warm water and longer cure times produced constructs with greater stiffness (6% greater), bending moment (14% greater), and cumulative energy at yield (11% greater) and failure (20% greater)

  • 10% greater yield bending moments

• Longer cure time significantly increased angular deformation of rods at failure, however water temperature did not

• The strongest casts were produced with warm water and after curing for 24 hours

• Significant differences between warm and cold water were typically seen at 0.5 and 1 hour but not at 24 hours

• At 0.5 hours (typical recovery time for horses) only 66% (cold water) and 74% (warm water) of the total cast strength reached at 24 hours was achieved

Conclusion: Fiberglass casts continued to gain strength for at least 24 hours. Use of warm water increased the rate of curing, resulting in stronger constructs at earlier time points

Plunkett et al, 2019

Pressure generated by wide-rubber tourniquets

Objective: To determine the influence of location and movement on subtourniquet pressure (STP) generated by application of a wide-rubber tourniquet (WRT) on equine limbs

Results:

• Mean STP did not change with time and exceeded systolic blood pressure by 163 mmHg at the antebrachium, 185 mmHg at the gaskin, and 402 mmHg at the midmetacarpus respectively

• Mean STP at each location exceeded the target STP in 81% of the trials

• Limb movements affected STP generated by tourniquets at the antebrachium and midmetacarpus but not at the gaskin

Conclusion: Wide-rubber tourniquets applied at the antebrachium, gaskin, and midmetacarpus generated STP >100 mmHg above systolic blood pressure for 30 minutes in standing, sedated horses. Wide-rubber tourniquets can achieve and maintain the current recommended STP (systolic blood pressure + 100 mmHg) for equine IVRLP. Number and magnitude of limb movement can decrease STP over time, potentially reducing the efficacy of the wide rubber tourniquet

Stewart et al, 2020

Effects of Long-Term Distal Limb Immobilization

Objective: Describe the effects of distal limb immobilization and remobilization in the equine metacarpophalangeal joint

Results:

• Distal limb immobilization resulted in persistent lameness, effusion, and decreased range of motion as well as radiographically visible fragments in the cast forelimb

• Bone density was decreased in MC3 according to CT, and trabecular bone fluid was increased according to MRI in the cast forelimb

• The cast forelimbs had a change in the appearance of the deep digital flexor tendon according to MRI immediately after removal of the cast

• There was a 24-fold increase in the likelihood of lameness after placement of the limb in a cast

  • Lameness and positive response to distal limb flexion tests persisted throughout the remobilization period

Conclusion: Eight weeks of cast immobilization induced changes in bone, cartilage, and periarticular soft tissues that were not reversed after 12 weeks of remobilization

Davis et al, 2019

Radiocontrast of the Caudal Epigastric Arteries

Objective: Determine the location of the deep and superficial caudal epigastric arteries in relation to 3 midline positions and the relationship between the location of these arteries, body circumference, and body condition score

Results:

• The location of the deep caudal epigastric artery correlated with body circumference and body condition score at the umbilicus, midpoint landmark, and prepubic tendon attachment

• Arteries of heavier condition horses tended to be farther from midline

• The course of the deep caudal epigastric artery could be estimated by multiplying body circumference by 0.04 at the umbilicus, 0.07 at the midpoint landmark, and 0.03 at the prepubic tendon attachment

• Orientation of the deep caudal epigastric artery to the umbilicus had the most variation in lateral distanec of the 3 midline landmarks

• The course of the superficial caudal epigastric artery did not correlate with anatomic landmarks

• Course of the superficial caudal epigastric artery can be established as a parasagittal line 16-53% of the distance from the midline to the most lateral aspect of the deep caudal epigastric artery path

Conclusion: The course of the deep caudal epigastric artery could be estimated at 3 midline landmarks on the basis of body circumference and body condition score in equine cadavers. Predicting the course of the caudal epigastric arteries may prevent iatrogenic damage during creation of laparoscopic portals

Peeters et al, 2023

Foot placement for navicular skyline radiographs

Objectives: To determine optimal foot placement and beam angle for obtaining palmaroproximal-palmarodistal oblique (PaPr-PaDiO) views

Results:

• Diagnostic quality and compacta-spongiosa demarcation was graded higher for feet positioned caudally and angle between 40* and 45*

• Elevation of the toe significantly decreased the navicular bone palmar border angle but seemed to have no obvious positive influence on radiographs

Conclusions: Caudal foot placement seems to improve the image quality of the navicular skyline view. The widely used standard beam angle of 45* appears to be the favorable angle for acquisition with a varied range of -5*. Elevation of the toe, standard in most commercially available navicular skyline cassette holders, does not influence the obtained image quality