Intra-articular stabilisation of the equine cricoarytenoid joint.

REASONS FOR PERFORMING STUDY The success of laryngoplasty is limited by abduction loss in the early post operative period. OBJECTIVE To determine the efficacy of polymethylmethacrylate (PMMA) in stabilising the cricoarytenoid joint (CAJ) and reducing the force on the laryngoplasty suture. HYPOTHESIS Injection into the cricoarytenoid joint resists the forces produced by physiological laryngeal air flows and pressures thereby reducing the force experienced by the laryngoplasty suture. METHODS Ten cadaver larynges were collected at necropsy and PMMA was injected into one CAJ at selected random. Each larynx was subjected to physiological conditions with with constant (static) or cycling (dynamic) flow. The specimens were tested sequentially in each of 4 conditions: 1) bilateral full abduction (Control 1); 2) transection of the suture on the side without PMMA; 3) bilateral abduction achieved by replacing the suture (Control 2); and 4) cutting the suture on the PMMA side. Tracheal pressure and flow and pressure in the flow chamber were recorded using pressure and flow transducers. The strain experienced by each suture during bilateral abduction (Controls 1 and 2) was measured. Statistical comparison of the 4 conditions was performed using a mixed effect model with Tukey's post hoc test for multiple comparisons. The strain gauge data were analysed by paired comparison of the regression slopes. RESULTS In the static and dynamic states, tracheal pressure increased and tracheal flow decreased when the suture on the non-cement side was cut (P < 0.05). There was no significant difference in any outcome measure between PMMA injected into the CAJ and bilaterally abducted specimens (Controls 1 and 2) for either condition. The rate of increase in strain with increasing translaryngeal pressure was significantly less on the suture with PMMA placed in the CAJ (P = 0.03). CONCLUSIONS These data provide strong evidence that injecting PMMA into the CAJ resists the collapsing effect of physiological airflows and pressures in vitro and reduces the force experienced by the laryngoplasty suture during maximal abduction. POTENTIAL RELEVANCE Augmentation of prosthetic laryngoplasty with this technique may reduce arytenoid abduction loss in the early post operative period.

[1]  J. Hermanson,et al.  In vitro model for testing novel implants for equine laryngoplasty. , 2008, Veterinary surgery : VS.

[2]  J. Hermanson,et al.  Neuroanatomy of the equine dorsal cricoarytenoid muscle: surgical implications. , 2008, Equine veterinary journal.

[3]  J. Lane,et al.  Dynamic obstructions of the equine upper respiratory tract. Part 1: observations during high-speed treadmill endoscopy of 600 Thoroughbred racehorses. , 2010, Equine veterinary journal.

[4]  H. Erb,et al.  A comparison of laryngoplasty and modified partial arytenoidectomy as treatments for laryngeal hemiplegia in exercising horses. , 2006, Veterinary surgery : VS.

[5]  C. Elie,et al.  In vitro comparison of two techniques for suture prosthesis placement in the muscular process of the equine arytenoid cartilage. , 2006, Veterinary surgery : VS.

[6]  S. Scherzer,et al.  Evaluation of a canine cranial cruciate ligament repair system for use in equine laryngoplasty. , 2005, Veterinary surgery : VS.

[7]  W. Hartmann,et al.  Effect of laryngoplasty on respiratory noise reduction in horses with laryngeal hemiplegia. , 2010, Equine veterinary journal.

[8]  B. McGorum,et al.  Long-term survey of laryngoplasty and ventriculocordectomy in an older, mixed-breed population of 200 horses. Part 1: Maintenance of surgical arytenoid abduction and complications of surgery. , 2010, Equine veterinary journal.

[9]  B. M. Kraus,et al.  Laryngoplasty with ventriculectomy or ventriculocordectomy in 104 draft horses (1992-2000). , 2003, Veterinary surgery : VS.

[10]  D. Slone,et al.  Treatment of laryngeal hemiplegia in horses by prosthetic laryngoplasty, ventriculectomy and vocal cordectomy , 2002, Veterinary Record.

[11]  K. Pickles,et al.  Laryngeal paralysis: a study of 375 cases in a mixed-breed population of horses. , 2010, Equine veterinary journal.

[12]  J. Lloyd,et al.  Endoscopic assessment of airway function as a predictor of racing performance in Thoroughbred yearlings: 427 cases (1997-2000). , 2001, Journal of the American Veterinary Medical Association.

[13]  E. Parente,et al.  The effect of recurrent laryngeal neurectomy in conjunction with laryngoplasty and unilateral ventriculocordectomy in thoroughbred racehorses. , 2001, Veterinary surgery : VS.

[14]  I. Titze,et al.  Review of range of arytenoid cartilage motion. , 2005, Acoustics research letters online : ARLO.

[15]  J. R. Mcclure,et al.  Career racing performance in Thoroughbreds treated with prosthetic laryngoplasty for laryngeal neuropathy: 52 cases (1981-1989). , 2000, Journal of the American Veterinary Medical Association.

[16]  A. Wilson,et al.  In vitro evaluation of a novel prosthesis for laryngoplasty of horses with recurrent laryngeal neuropathy. , 2000, Equine veterinary journal.

[17]  J. Kasperbauer.  A biomechanical study of the human cricoarytenoid joint , 1998, The Laryngoscope.

[18]  B. B. Martin,et al.  Videoendoscopic assessment of dynamic laryngeal function during exercise in horses with grade-III left laryngeal hemiparesis at rest: 26 cases (1992-1995). , 1998, Journal of the American Veterinary Medical Association.

[19]  M. Ross,et al.  Laryngoplasty with or without ventriculectomy for treatment of left laryngeal hemiplegia in 230 racehorses. , 1997, Veterinary surgery : VS.

[20]  N. E. Robinson,et al.  Efficacy of prosthetic laryngoplasty with and without bilateral ventriculocordectomy as treatments for laryngeal hemiplegia in horses. , 1996, American journal of veterinary research.

[21]  C. Duncan,et al.  Persistence of bacteria on antibiotic loaded acrylic depots. A reason for caution. , 1996, Clinical orthopaedics and related research.

[22]  Russell Ap,et al.  Performance analysis after prosthetic laryngoplasty and bilateral ventriculectomy for laryngeal hemiplegia in horses: 70 cases (1986-1991). , 1994 .

[23]  H. Erb,et al.  Repeatability and normal values for measurement of pharyngeal and tracheal pressures in exercising horses. , 1994, American journal of veterinary research.

[24]  N. Ducharme,et al.  Measurement of tracheal static pressure in exercising horses. , 1992, Veterinary surgery : VS.

[25]  H. Erb,et al.  Arytenoid cartilage movement in resting and exercising horses. , 1991, Veterinary surgery : VS.

[26]  J. Schumacher,et al.  Effects of age and prosthesis material on in vitro cartilage retention of laryngoplasty prostheses in horses. , 1990, American journal of veterinary research.

[27]  N. E. Robinson,et al.  Effects of ventriculectomy, prosthetic laryngoplasty, and exercise on upper airway function in horses with induced left laryngeal hemiplegia. , 1988, American journal of veterinary research.

[28]  B. Goulden,et al.  Equine laryngeal hemiplegia. Part III. Treatment by laryngoplasty. , 1982, New Zealand veterinary journal.

[29]  D. Marks,et al.  Observations on Laryngeal Hemiplegia in the Horse and Treatment by Abductor Muscle Prosthesis , 1970 .