Equis ISSN 2398-2977

Annular ligament: transection - palmar / plantar

Synonym(s): Annular ligament desmotomy

Contributor(s): Stephen Adams, Andy Bathe, Graham Munroe, Vetstream Ltd

Introduction

  • To relieve constriction of the palmar/plantar annular ligament (PAL) → improved circulation and gliding movement of flexor tendons. The PAL may or may not be thickened depending on the specific pathogenesis of each case.
  • There are 3 commonly used techniques:
    1. 'Closed' - minimally invasive surgery.
    2. Open surgery - when adhesions in severe and chronic tenosynovitis preclude the easy insertion of instruments.
    3. Tenoscopic techniques Tenosynovioscopy where the desmotomy is performed abaxially between the proximal sesamoid bone margin and the palmar/plantar reflection of the sheath wall from the PAL to the SDFT. There are two basic techniques - a slotted cannula system and a 'free-hand' division using a variety of instrumentation.

Uses

  • Indicated for the management of DDFT and SDFT tendinitis lesions in the region of the digital flexor tendon sheath (DFTS), where the annular ligament (AL) is impeding movement of these tendons.
  • Specific injuries and tears of the DDFT and/or SDFT within the DFTS including longitudinal linear tears and damage to the manica flexoris.
  • Primary AL desmitis or desmopathy with thickening and subsequent constriction.
  • Complex chronic tenosynovitis Digital sheath: tenosynovitis cases where there is multiple chronic pathology of which PAL constriction is one part. To perform tenoscopy of these cases proficiently often requires PAL desmotomy early on to increase the room within the sheath for full exploration and surgical management.
  • Septic tenosyonvitis - to promote lavage and drainage Digital sheath: tenosynovitis.
  • Rarely desmotomy near its point of insertion is used in the treatment of small avulsion fractures of the palmar border of the proximal sesamoid bone to relieve tension on the fragment/s Proximal sesamoid: fracture.

Advantages

  • The minimally invasive or closed procedure can be performed on a standing Anesthesia: standing chemical restraint, sedated animal, with minimal incision length and easy aftercare.
  • Some care and experience is needed and this is not a procedure for the novice surgeon.
  • The open procedure allows greater examination of the contents of the sheath compared to the closed procedure, but less than the tenoscopic view.
  • Can be performed arthroscopically Joint: arthroscopy - overview with special instrumentation - advantageous because:
    • It is less traumatic, resulting in better and quicker wound healing and earlier return to controlled exercise, limiting adhesion formation and secondary subcutaneous fibrosis.
    • Allows evaluation of the contents of the sheath, and especially the tendons, for surface defects/damage.
    • Ensures accurate transection of only the PAL, avoiding inadvertent damage to the tendons, manica flexoria and other peritendosynovial structures.
    • Better cosmetic result.
    • Additional advantages of the slotted cannula system are mainly evident in the chronic case, and include the more assured, accurate and complete division of the PAL, with more consistent visual guidance.

Disadvantages

  • Effectiveness governed by tendon healing in cases of tendinitis or injuries to the intra-sheath structures.
  • Wound breakdown and subsequently synovial fistulae may form with open approaches, particularly when extended incisions are made.
  • The minimally invasive surgical procedure means that the ligament is transected 'blind', with the possibility of iatrogenic damage to surrounding structures. It is also not applicable to cases where more than the annular ligament is involved as there is no view of the sheath contents and no opportunity to perform any other surgical procedures.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Good - if simple PAL constriction, desmitis of annular ligament or chronic fibrosing synovitis - return to work within 4-6 months of surgery.
  • Guarded - if extensive adhesions or complex pathology at the time of surgery - at least 6-9 months before return to work.
  • Depends on concurrent pathology, but significantly worse where there is tendon pathology.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lacitignola L et al (2018) Palmar annular ligament desmotomy in horses with the Arthrex-Centerline™ : An ex-vivo study. Open Vet J 8 (1), 53-56 PubMed.
  • Espinosa P et al (2017) A novel ultrasonographic assisted technique for desmotomy of the palmar/plantar annular ligament in horses. Vet Surg 46 (5), 611-620 PubMed.
  • McCoy A M & Goodrich L R (2012) Use of a radiofrequency probe for tenoscopic-guided annular ligament desmotomy. Equine Vet J 44 (4), 412-415 PubMed.
  • Owen K R (2008) Retrospective study of palmar/plantar annular ligament injury in 71 horses (2001-2006). Equine Vet J 40 (4), 412-415 PubMed.
  • Fortier L A (2005) Indications and techniques for tenoscopic surgery of the digital flexor tendon sheath. Equine Vet Educ 17 (4), 218-224 VetMedResource.
  • Hawkins J F & Moulton J S (2002) Arthroscope-assisted annular ligament desmotomy in horses. Equine Vet Educ 14 (5), 252-255 VetMedResource.
  • Nixon A J et al (1993) Endoscopically assisted annular ligament release in horses. Vet Surg 22 (6), 501-507 PubMed.
  • Honnas C M et al (1991) Septic tenosynovitis in horses, 25 cases (1983-1989). JAVMA 199 (11), 1616-1622 PubMed.

Other sources of information

  • Cauvin E R J (2011) Tenoscopy of the Digital Flexor Tendon Sheath. In: Diagnosis and Management of Lameness in the Horse. 2nd edn. Eds: Ross M W & Dyson S J. Elsevier, USA. pp 260-262. 
  • Nixon A J (2011) Annular Ligament Transection. In: Equine Surgery. 4th edn. Eds: Auer J A & Stick J A. Saunders, USA. pp 1300.
  • Ross M W (2011) Palmar Annular Desmotomy. In: Diagnosis and Management of Lameness in the Horse. 2nd edn. Eds: Ross M W & Dyson S J. Elsevier, USA. pp 718-719. 


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