Managing Proximal Suspensory Desmitis: fore & hind limbs

Summary

My current treatment regime involves a combination of the techniques described below. Extracorporeal shockwave therapy is used in persistent lameness due to proximal suspensory desmitis in the forelimb and low-grade cases of hindlimb proximal suspensory desmitis. In hindlimb proximal suspensory desmitis a plantar metatarsal neurectomy and fasciotomy is employed if the block pattern is appropriate. In cases with marked hypoechogenicity this is combined with a PRP injection. With aggressive surgical management I would consider that the prognosis is dramatically improved in a large number of cases. Follow-up of these cases during the rehabilitation period is important in optimising the outcome.

Conservative and medical management

Management of acute injuries should involve rest, anti-inflammatory therapy and controlled exercise under serial ultrasound monitoring. One-off regional infiltration with corticosteroids (e.g. 10mg triamcinolone in 3mls of local anaesthetic) can be beneficial in decreasing the inflammation in acute cases. It can also be useful in managing low-grade chronic/active cases in the short term. This is often the most appropriate form of treating flat racing Thoroughbreds, as there is not time in their short careers for the lay-off associated with surgery.

Platelet rich plasma (PRP) is the currently favoured biological product for the treatment of PSD. It contains a number of anabolic growth factors, and there are a number of commercially available systems that allow the product to be easily used in practice. It can be used on its own in cases of acute desmitis, especially in forelimbs, but in hindlimbs it is most commonly employed along with other forms of treatment – for the reasons outlined above that lead to the chronic pain state. I prefer to use autologous conditioned serum (Irap) in marginal lesions in the mid-body and branches, as it is less fibrinogenic and should be less likely to cause adhesions. Intravenous infusion of bisphosphonates has been useful in some cases of enthesis-related pain.

Extracorporeal Shockwave Therapy (ESWT)

ESWT has now been employed for a number of years in the treatment of proximal suspensory desmitis. In my experience it has been extremely helpful in the management of chronic active cases of proximal suspensory desmitis in the forelimb. Crowe et al (2004) reported on a series of cases of hindlimb PSD treated with radial ESWT, and improved the prognosis to around 41%. This is significantly better than with conservative treatment, but still poorer than the surgical treatments that will be described. Lischer et al (2006) reported on 22 cases of hindlimb PSD treated with focused ESWT, which also had a 41% success rate at six months. This supports my clinical impression that there does not seem to be any difference between radial and focused machines in the outcome following treatment. In the hindlimb I tend to use it in either mild, acute cases or for the management of low-grade, chronic cases, and continued treatments may be necessary. Clinically there does not seem to be any difference between radial and focused machines in the outcome following treatment. I now use higher settings for the hindlimb than the forelimb: with the EMS Swiss DolorClast Vet 2500 pulses at 3.5 bar with a 10mm applicator versus 2000 pulses at 3 bar. I would normally combine this with medical management.

Plantar metatarsal neurectomy and fasciotomy

This treatment was developed as the surgical option for the management of proximal suspensory ligament desmitis in the hindlimb. This procedure combines decompressive fasciotomy of the deep laminar plantar metatarsal fascia with neurectomy of the deep branch of the lateral plantar nerve. This nerve branch is the common origin of the medial and lateral plantar metatarsal nerves, which apply sensory innervation to the origin of the suspensory ligament. Surgery should be restricted to those cases that have had a very good response to a block of the deep branch of the lateral plantar nerve. Long term follow-up has yielded a long term success rate of 75% returning to normal function. The surgical technique will be described, and approximately 4-5cm of nerve is removed through a 3.5cm incision. The same procedure has also been used successfully in forelimb cases, but there is generally less need for this.

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