Long‐term prognosis for return to athletic function after interspinous ligament desmotomy for treatment of impinging and overriding dorsal spinous processes in horses: 71 cases (2012–2017)

Abstract

Objective To determine the long‐term return to performance of horses with impinging and/or overriding dorsal spinous processes (ORDSP) treated with interspinous ligament desmotomy (ISLD) and to determine the prognostic value of radiographic and scintigraphic grades. Study design Retrospective study. Animals Seventy‐one horses with ORDSP treated with ISLD. Methods Medical records were reviewed for signalment, physical examination, gait evaluation, and number of interspinous spaces treated. Preoperative radiographic and scintigraphic images were evaluated with grading scales. Follow‐up was obtained with a telephone questionnaire. Prognostic value of the number of affected interspinous spaces, radiographic grading, and scintigraphic grading was tested by using a χ2 test. Results A median follow‐up of 35 months (range, 8–64) was available for 56 horses. Fifty‐one of 56 (91.1%) horses returned to some level of performance, with 27 of 51 (52.9%) horses achieving equivalent or higher level of performance. Achieving a lower level of performance was attributed to recurrent back pain in nine of 24 (37.5%) horses and to unassociated lameness in nine of 24 (37.5%) horses. Owners of 44 of 56 (78.6%) horses were satisfied with the postoperative performance level, and owners of 46 of 56 (82.1%) horses would recommend the procedure. None of the variables tested influenced the return to performance. Conclusion Interspinous ligament desmotomy allowed horses with ORDSP to return to some level of performance, although fewer returned to an equivalent or higher level of performance than had previously been reported. Clinical significance Interspinous ligament desmotomy allows affected horses to return to some level of performance, regardless of the severity of radiographic and scintigraphic findings.

Long‐term outcome and effect of diagnostic analgesia in horses undergoing interspinous ligament desmotomy for overriding dorsal spinous processes

“…The success rate of ISLD in horses that underwent and improved with diagnostic analgesia in the study population (9/10 [90%]) is similar to the success rate achieved in other studies and with other surgical methods, for which diagnostic analgesia was also a criteria for case inclusion (81%-86%). 11,20 Horses that did not undergo diagnostic analgesia prior to ISLD achieved a lower success rate (4/8 [50%]) than previously reported (91%-95%) 21,22 in studies for which diagnostic analgesia was not a criteria for case inclusion. The small case number in the current population or differences in case selection between the two studies may account for the discrepancy between success rates.…”

“…While 91% to 95% of horses in previous studies of outcome after ISLD reportedly improved in signs of back pain, 38% to 46% of horses had signs of lameness postsurgery, which may indicate that determination of cause of poor performance was not achieved and true surgical success was overestimated . In addition, only 53% of horses achieved a similar or higher level of performance in one study . There is substantial overlap in diagnostic imaging findings in horses that are symptomatic and those that are asymptomatic for thoracolumbar pain .…”

“…In the study by Coomer et al, although 95% of horses were considered to have successful outcomes, 46% of horses were lame at subsequent evaluation. In addition, although 91% of horses returned to work after ISLD in the study by Prisk et al, only 53% of horses returned to an equivalent or higher level of performance, 38% of which were lame. Diagnosis of clinically relevant ORDSP based on clinical findings and radiographic evidence alone without diagnostic analgesia can lead to misdiagnosis, particularly because diagnostic imaging correlates poorly to clinical disease.…”

“…7,[11][12][13][14][15][16][17][18] Surgical management is undertaken when the severity of disease is considered marked or the horse is unresponsive to medical management. 5,11,[19][20][21][22][23] Minimally invasive, standing surgical approaches such as interspinous ligament desmotomy (ISLD) have recently come into favor, with a reported success rate of 91%-95% in two studies. 21,22 However, diagnostic analgesia preoperatively to confirm a radiographic diagnosis of ORDSP as the source of clinical signs was not used as a criteria for case inclusion in either study.…”

“…5,11,[19][20][21][22][23] Minimally invasive, standing surgical approaches such as interspinous ligament desmotomy (ISLD) have recently come into favor, with a reported success rate of 91%-95% in two studies. 21,22 However, diagnostic analgesia preoperatively to confirm a radiographic diagnosis of ORDSP as the source of clinical signs was not used as a criteria for case inclusion in either study. In the study by Coomer et al, 21 although 95% of horses were considered to have successful outcomes, 46% of horses were lame at subsequent evaluation.…”