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Case Report: Metatarsal Pad Necrosis secondary to Postoperative Dressing Complications in a Bassett Hound

 
 
History

fig.1 - Initial radiology showed a comminuted, over-ridden diaphyseal fracture of the tibia

fig.2 - caudocranial radiograph on initial presentation

A 12-month-old, entire, female Bassett Hound, body weight 23kg, presented for stabilisation of closed, left tibia and fibula fractures, sustained after jumping from the owner’s car.  The referring veterinarian’s radiographs (figs. 1-3) revealed an over-riding, comminuted, mid-diaphyseal fracture of the tibia, with incomplete, transverse fracture of the fibula. 

fig. 3 - craniocaudal radiograph following closed reduction

 

 

 

 

 

Initial treatment had involved closed reduction and external coaptation with a Robert Jones dressing.

 

 
 
Assessment

fig. 4 - post-op caudocranial radiograph

fig. 5 - four weeks post-op lateral radiograph shows early remodelling across the fracture callus.

General physical examination revealed changes to both external ear canals, consistent with chronic otitis externa.  Orthopaedic examination was consistent with the radiographic findings above.

 

Treatment

The fractures were stabilised with a uniplanar, bilateral, external fixator with two additional half-pins placed in the proximal and distal metaphyses of the tibia respectively (see figs. 4 & 5).  A padded dressing was applied postoperatively, to reduce limb swelling.  A seven day course of amoxiclav 375mg q12h P.O. was dispensed.  The dressing was changed regularly by the referring veterinarian. 

fig. 6 - removal of dressings revealed maceration of the skin with areas of devitalised tissue.

 

 

 

One week later, the patient was re-presented to the referring vet with a wet dressing.  Removal of the dressing revealed cellulitis of the pes with a foul-smelling discharge from several sinus tracts which had opened up on the plantar aspect of the interdigital skin and in several sites around the talocrural joint.  Discolouration of the metatarsal pad indicated areas of devitalised tissue (see fig. 6).  There was no evidence of discharge from the pin-tracts themselves, the dog remained bright and was still weight-bearing on the limb.

fig. 7 - three weeks after serial debridement and lavage

Bacteriology yielded a heavy, mixed growth of S.intermedius and A.hydrophilia, the latter resistant to amoxiclav.  Gram positive rods were also isolated on anaerobic culture.  A seven-day course of marbofloxacin 2mg/kg q24h I.V. was administered.

Serial debridement, lavage and regular dressing changes (with medical grade Manuka honey to coat the contact layer) were used for three weeks to achieve a healthy wound bed.  At this point approximately 25% of the metatarsal pad was left intact (see fig. 7). 

The limb was re-radiographed at four weeks post stabilisation when the fractures were found to have healed (see again, fig. 5).  The external fixator was removed. 

 

 

 

fig. 8 - delayed primary closure achieved with vertical mattress sutures

The plantar skin deficit was managed by partial closure (see fig. 8) using vertical mattress, monofilament nylon sutures to manage wound tension. Additional areas of skin deficit were allowed to heal by second intention.

Sutures were removed 10 days later and the wounds were dressed until epithelialisation was complete.

fig. 9 - appearance of pes 12 weeks after initial presentation. There is early hypertrophy of the metatarsal pad.

Re-examination 12 weeks after the initial fracture repair revealed all skin deficits to have healed with evidence of early hypertrophy of the affected metatarsal pad (see fig. 9).

 

 
 
 
 
 
Discussion

Irrespective of the cause of foot-injury, every effort should be made to salvage viable tissue from weight-bearing pads.  This helps to preserve the footpad cushion, important for diffusion of weight bearing stresses.  It also significantly reduces the surgical morbidity associated with free pad-transfer grafts or digital-filleted pad flaps.  Adjacent skin may also be used via local flaps to cover deficits over weight-bearing surfaces, as this will incite a reactive hypertrophy of the dermis to withstand the inevitable friction forces.  However, this option does carry a higher risk of ulceration during the maturation phase of healing.

The above case demonstrates the effectiveness of intensive, open wound management in addressing peracute, necrotising cellulitis.  The importance of basic dressing care should also be emphasised to owners at every opportunity so as to reduce the risk of such potentially devastating complications.