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Accessory ligament DDFT: desmotomy

ISSN 2398-2977


Synonym(s): Distal check desmotomy, desmotomy of accessory ligament of DDFT, inferior check ligament desmotomy

Introduction

  • Permits effective lengthening of the deep digital flexor tendon and axial realignment of the distal limb.
  • Normal anatomy and function:
    • Distal, or inferior, check ligament arises from palmar carpal ligament to insert on the deep digital flexor tendon in mid-distal metacarpus.
    • The check ligament supports the digit via the deep digital flexor, and prevents over-extension of the muscle bellies.
    Corrective shoeing as well as deep digital flexor tenotomy is a necessity.

Uses

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Advantages

  • Established technique.
  • Medial or lateral approach.
  • Simple procedure.

Disadvantages

  • May be insufficient for severe flexural deformities, (dorsal hoof angle >90°).
  • Some residual scar tissue may persist that reduces value as a show horse.

Alternative techniques

Ultrasound-guided approach to desmotomy

  • An ultrasound–guided approach to desmotomy in 35 cases was published in 2010:
    • In foals and difficult horses this is usually performed under GA, in dorsal or lateral recumbency, but it can be accomplished in the standing sedated horse (plus regional analgesia) in tractable cases.
    • Ultrasonography Ultrasonography: flexor tendon is used to identify the site of surgery in the proximal metacarpal region where there is adequate separation of the ALDDFT and DDFT, usually just distal to the distal extent of the carpal sheath.
    • A 1-1.5 cm incision is made on the proximal third of the metacarpus on the ultrasonographically identified lateral aspect of the ALDDFT.
    • A curved Kelly or Crile forceps is introduced under ultrasound guidance through the incision and between the dorsal aspect of the ALDDFT and the palmar aspect of the suspensory ligament. It is used to separate the fascia between the two structures.
    • A second curved forcep is introduced in the same manner between the palmar ALDDFT and the dorsal aspect of the DDFT and this is used to help retract the ALDDFT.
    • Using both forceps the ALDDFT is isolated and pulled towards the skin. A second surgeon holds the forceps slightly palmarly and grasps the ALDDFT using an Ochsner forceps, thereby allowing the first surgeon to cut the ligament.
    • In some cases Desjardins gall bladder forceps alone were used to isolate and elevate the ALDDFT.
    • Extending the digit before severing the ALDDFT is helpful.
    • Ultrasonography is used to confirm the ALDDFT is fully transected.
    • The subcutaneous tissues and skin are closed routinely and the leg dressed and bandaged.
    • Aftercare is similar to the standard procedure.
    • This minimally-invasive technique has a much smaller incision which reduces scarring and produces superior cosmetic results. In addition the use of ultrasound guidance allows the surgeon to avoid major structures such as vessels and nerves. The Desjardins forceps appear superior to the others and were recommended.

Tenoscopic approach

  • A tenoscopic approach for the desmotomy has been described and may in the future become the approach of choice:
    • In dorsal recumbency a distomedial arthroscopic portal into the carpal sheath is made at the level of the junction of the middle and proximal thirds of the metacarpus with the carpus in approximately 20 degree flexion.
    • A contralateral instrument portal is made at the same level into the sheath.
    • The carpus is then extended for the transection of the ligament to place it under tension.
    • Using a Beaver blade the lateral part of the check ligament is severed before exchanging the arthroscope and instruments in order to divide the remaining medial part.
    • Complete division is confirmed by visualization of the loose areolar tissue overlying the suspensory ligament and the separation of the cut ends on extension of the toe of the foot.
    • This technique is technically demanding but minimally invasive with minimal complications and good post-operative cosmesis.

Time required

Preparation

  • Standard surgical preparation of site: 10-15 min.

Procedure

  • 30 min.

Decision taking

Criteria for choosing test

  • Severity of flexural deformity.

Risk assessment

Requirements

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Preparation

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Technique

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Caldwell F J & Waguespack R W (2011) Evaluation of a tenoscopic approach for desmotomy of the accessory ligament of the deep digital flexor tendon in horses. Vet Surg 40 (3), 266-271 PubMed.
  • Walmsley E A, Anderson G A & Adkins A R (2011) Retrospective study of outcome following desmotomy of the accessory ligament of the deep digital flexor tendon for type 1 flexural deformity in Thoroughbreds. Aust Vet J 89 (7), 265-268 PubMed.
  • Yiannikouris S et al (2011) Desmotomy of the accessory ligament of the deep digital flexor tendon in the forelimb of 24 horses 2 years and older. Vet Surg 40 (3), 272-276 PubMed.
  • Tnibar A, Christophersen M T & Lindegaard C (2010) Minimally invasive desmotomy of the accessory ligament of the deep digital flexor tendon in horses. Equine Vet Educ 22 (3), 141-145 VetMedResource.
  • Becker C K et al (1998) Long-term consequences of experimental desmotomy of the accessory ligament of the deep digital flexor tendon in adult horses. Am J Vet Res 59 (3), 347-351 PubMed.
  • Savelberg H H, Buchner H H & Becker C K (1997) Recovery of equine forelimb function after desmotomy of the accessory ligament of the deep digital flexor tendon. Equine Vet J Suppl (23), 27-29 PubMed.

Other sources of information

  • McIlwraith C W, Nixon A J & Wright I W (2015) Desmotomy of the Accessory Ligament of the Deep Digital Flexor (Inferior Check Ligament). In: Diagnostic and Surgical Arthroscopy in the Horse. 4th edn. Mosby Elsevier, UK. pp 370-372.