Evaluation of a Canine Cranial Cruciate Ligament Repair SystemR for Use in Equine Laryngoplasty

Variations in the application of equine prosthetic laryngoplasty: A survey of 128 equine surgeons

OBJECTIVE

To document variations in the application of equine prosthetic laryngoplasty among equine surgeons.

STUDY DESIGN

Cross-sectional survey.

SAMPLE POPULATION

Six hundred and seventy-eight equine surgeons performing prosthetic laryngoplasty.

METHODS

An online questionnaire was sent to equine surgeons, including diplomates of the American College of Veterinary Surgeons and European College of Veterinary Surgeons. Questions focused on participant profile, surgical technique, antimicrobial therapy, and concurrent procedures. Descriptive statistical analysis was performed on the survey output.

RESULTS

Complete responses were received from 128/678 individuals, mostly from experienced surgeons. Most participants used 2 prostheses (106/128, 82.8%) and a single loop was the most common method used to anchor the prosthesis in the cricoid (95/128, 74.2%) and arytenoid (125/128, 97.7%) cartilages. Use of general anesthesia was common, although 46/128 (35.9%) participants now performed most laryngoplasty surgery with standing sedation. The material used as a prosthesis varied among surgeons, although participants typically aimed to achieve grade 2 intraoperative arytenoid abduction. Participants most commonly administered perioperative systemic antimicrobial therapy for 1-3 days (57/128, 44.5%) and 48/128 (37.5%) used local antimicrobial therapy.

CONCLUSION

Most surgeons performed laryngoplasty with 2 prostheses, a single loop construct at the muscular process of the arytenoid cartilage and systemic antimicrobial therapy. There was variation in the preferred method of surgical restraint, prosthesis material selection, and use of local antimicrobial therapy.

CLINICAL SIGNIFICANCE

Long-established techniques remain popular in clinical practice despite evidence that variations offer advantages, particularly in relation to biomechanics. Other factors are also likely to influence technique selection in a clinical context.

In vitro evaluation of the effect of a prototype dynamic laryngoplasty system on arytenoid abduction

OBJECTIVE

To determine the effect of a prototype dynamic laryngoplasty system (DLPS) on arytenoid abduction.

STUDY DESIGN

In vitro experimental.

STUDY POPULATION

Ten equine larynges.

METHODS

Dissected larynges were mounted, and the right arytenoid was maximally abducted for testing. A left-sided laryngoplasty (LP) was performed by using a strand of No. 2 FiberWire and a FASTakII anchor. Phase 1 involved tightening the suture, without the DLPS device in place, in 1-mm increments and acquiring a digital image of the rima glottidis at each increment. Phase 2 involved tying the suture with the DLPS in place at a left to right quotient (LRQ) of 0.7. Digital images were subsequently taken at 3 stages of DLPS activation (0, 25, and 50 or maximal psi) and analysed to calculate LRQ.

RESULTS

All tests were completed for 9 larynges. In phase 1, a total shortening of 25.89 ± 1.27 mm was possible, which increased the LRQ from 0.59 ± 0.02 to 1.07 ± 0.12. In phase 2, activation of the DLPS increased the LRQ from 0.70 ± 0.05 to 0.97 ± 0.09. This change in LRQ equated to 18.7 mm of shortening on the basis of phase 1 results. The maximum psi of the DLPS achieved was 37.33 ± 5.96.

CONCLUSION

The DLPS increased the degree of arytenoid abduction in vitro. This change in LRQ equated to 18.7 mm of shortening of the LP suture based on phase 1 results.

CLINICAL IMPACT

These results support further evaluation of the DLPS to determine the effect of changes in DLPS on airway resistance.

In vitro comparison of 3 techniques of prosthesis attachment to the muscular process of the equine arytenoid cartilage

OBJECTIVE

To determine the degree and ease of arytenoid abduction achieved with abaxial placement of a FASTak II suture anchor compared to 2 suture patterns with different directions of insertion-caudomedial to craniolateral and medial to lateral.

STUDY DESIGN

Ex vivo experimental.

STUDY POPULATION

Cadaveric larynges from 10 Standardbred racehorses.

METHODS

Each larynx was sequentially instrumented with all 3 arytenoid suture attachment in random order: (1) abaxial placement of a FASTak II suture, (2) caudomedial to craniolateral suture, and (3) medial to lateral suture placement. Each construct was abducted at 5N increments from 0 to 25N and the left to right quotient angle ratio (LRQ) measured from digital pictures acquired at each sequential increment.

RESULTS

Arytenoid abduction (higher LRQ) was greater with FASTak II construct than either of the suture patterns. The largest difference occurred at 5N. Approximately 50% less force was required to achieve an LRQ of 1.0 with the FASTak II anchor compared to the suture patterns. No difference was detected between the 2 suture constructs throughout the study.

CONCLUSION

Use of the FASTak II suture anchor improved arytenoid abduction compared to 2 suture patterns and minimized the suture loads required to achieve maximum arytenoid abduction.

CLINICAL RELEVANCE

Use of the FASTak II anchor may decrease the suture load required to achieve arytenoid abduction in clinical cases. This may reduce the load placed on the laryngoplasty, thereby, minimizing postoperative loss of abduction.

Ex Vivo Mechanical Evaluation of a Sternal ZipFix(®) Implant for Prosthetic Laryngoplasty in Horses

OBJECTIVE

To evaluate the properties of a ZipFix(®) (ZipFix) implant in equine laryngeal cartilages.

STUDY DESIGN

Ex vivo biomechanical study.

SAMPLE POPULATION

Equine arytenoid (n=36) and cricoid cartilages (n=18).

METHODS

Suture bites were placed in arytenoid or cricoid cartilages using a ZipFix(®) implant or a single strand of USP 5 braided polyester (TiCron™), and arytenoid and cricoid cartilages were separately subjected to single load to failure (25 N preload) or cyclic loading for 1,000 cycles, followed by single load to failure. Load, distraction, and stiffness were recorded.

RESULTS

Four arytenoid-ZipFix cartilages fractured on implant placement. Under single load, arytenoid-ZipFix (n=9) failed at a greater mean load (359.01 ± 57.98 N) than arytenoid-Ticron (159.11 ± 22.98 N; n=12; P<.001). Arytenoid-ZipFix stiffness (31.32 ± 4.26 N/mm) was significantly greater than arytenoid-Ticron (13.18 ± 2.60 N/mm; P<.001). Cricoid-ZipFix stiffness (20.83 ± 3.37 N/mm) was significantly greater than cricoid-Ticron (13.6 ± 3.82 N/mm; n=6; P=.006). Under cyclic load, arytenoid-ZipFix distraction (2.53 ± 0.63 mm; n=5) was significantly less than arytenoid-Ticron (5.06 ± 1.37 mm; n=6, P=.006). After cyclic load, arytenoid-ZipFix failure load (295.16 ± 54.95 N) was significantly greater than arytenoid-Ticron (127.69 ± 32.67 N; P=.002). Arytenoid-ZipFix stiffness (35.59 ± 1.58 N/mm) was significantly greater than arytenoid-Ticron (24.10 ± 6.85 N/mm; P=.019).

CONCLUSION

In arytenoid cartilages, the sternal ZipFix(®) implant was significantly stronger and stiffer compared to a single strand of Ticron. During placement of the ZipFix(®) implant, frequent arytenoid cartilage failure occurred before testing, suggesting the implant is not suitable for clinical application.

Mechanical comparison of 3 anchoring techniques in the muscular process for laryngoplasty in the equine larynx

OBJECTIVE

To compare mechanical properties of 2 techniques with a conventional technique for anchoring the muscular process in a laryngoplasty procedure.

STUDY DESIGN

Experimental ex vivo study.

SAMPLE POPULATION

Equine larynges (n = 60).

METHODS

A single loop (SL), a screw (SC), and a double loop technique (DL) were compared. Constructs were subjected to cyclic loading, oscillating from 5 to 50 N for 3000 cycles, followed by a single cycle to failure test. Mean distraction, load at failure, stiffness, and failure mode were compared between groups.

RESULTS

Mean ± SD distraction in cyclic loading was greater for DL (2.1 ± 0.7 mm) than for SL (1.9 ± 1.3 mm) and SC (1.539 ± 0.9 mm); however, there was no significant difference between SL and SC or between SL and DL. Mean ultimate failure load was greater for DL (240 ± 44.56 N) than for SC (189.59 ± 46.16 N) and SL (150.93 ± 44.43 N) and greater for SC compared with SL. Failure occurred by cartilage tearing for DL and SL, and by screw pull out (n = 13) or knot slippage (4) for SC.

CONCLUSION

In cyclic loading, SC is more stable than DL and at least as stable as SL. In single cycle to failure, DL is the strongest construct and SC is stronger than SL.

Surgical stabilization of shoulder luxation in a pot-bellied pig

Case Description-A 4.6-month-old pot-bellied pig was evaluated because of non-weight-bearing lameness (grade 5/5) in the right forelimb of 4 days' duration. Clinical Findings-Clinical and radiographic examination revealed a closed, lateral luxation of the right shoulder joint. Treatment and Outcome-Initial attempts at closed reduction failed to provide adequate stability of the shoulder joint. Open reduction and internal fixation by placement of 2 lateral tension sutures with a system designed for canine cranial cruciate ligament repair provided adequate joint stability and a successful outcome. Conclusions and Clinical Relevance-Stabilization of the shoulder joint with lateral tension sutures after open reduction should be considered for management of lateral shoulder luxation in pot-bellied pigs.

Mechanical evaluation of the equine laryngoplasty

OBJECTIVES

Mechanical evaluation of the equine laryngoplasty.

STUDY DESIGN

Experimental.

ANIMAL POPULATION

Cadaveric cricoid (n=36) and arytenoid (46) cartilages.

METHODS

Arytenoid and cricoid cartilage specimens were embedded for testing. Suture material (2 Ethilon, 5 Ethibond, or 5 Fiberwire) was inserted simulating laryngoplasty procedures. Constructs were evaluated in single or cyclic loading. Single cycle tests recorded load at failure and stiffness. Cyclical tests recorded displacement after 10,000 cycles. ANOVA and t-tests were used (significance P<.05).

RESULTS

The arytenoid Ethibond (241.10+/-47.67 N) constructs were stronger in single cycle than Ethilon (133.85+/-27.89 N) and Fiberwire (142.67+/-32.40 N). The cricoid Ethibond (220.39+/-49.11 N) constructs were stronger than Ethilon (171.93+/-21.19). The stiffness of Ethilon constructs was lower in both the arytenoid and cricoid compared with Ethibond and Fiberwire. The arytenoids failed at a lower load than the cricoids for Ethilon and Fiberwire but not Ethibond constructs. In cyclic testing complete failure of either cartilage did not occur. Arytenoid Ethibond constructs (0.43+/-0.21 mm) had less distraction than Ethilon (0.92+/-0.41 mm) and a trend for less compared with Fiberwire (0.83+/-0.43 mm; P=.0513). Cricoid Ethibond constructs (0.45+/-0.18 mm) had less distraction compared with Ethilon (1.04+/-0.30 mm) and Fiberwire (0.97+/-0.45 mm).

CONCLUSIONS

Ethibond was superior to Ethilon and Fiberwire constructs in vitro.

CLINICAL RELEVANCE

Abduction loss after laryngoplasty is a common complication. The results of this study suggest that the use of Ethibond should minimize abduction loss after surgery relative to the other materials tested.

Evaluation of the cranial cruciate ligament repair system(®) in surgery for laryngeal hemiplegia in heavy draft horses

The purpose of this study was to evaluate the effect of the canine cranial cruciate ligament repair system on laryngeal hemiplegia in heavy draft horses. Twenty-four heavy draft horses diagnosed with grade 4 laryngeal hemiplegia were allocated to either the prosthetic laryngoplasty (PL) group (n=14) or a canine cranial cruciate ligament repair system (CCCLRS) group (n=10). Right to left angle quotients (RLQs) of abductions of the arytenoid cartilages were endoscopically evaluated before and after surgery. Post-operative RLQs in the CCCLRS group were significantly lower than those of the PL group (P<0.01). The canine cranial cruciate ligament repair system was revealed to be a good surgical procedure for laryngeal hemiplegia in heavy draft horses.