EQUINE VETERINARY EDUCATION Equine vet. Educ. (2018) 30 (5) 229-236 doi: 10.1111/eve.12608


Case Report


Carpal arthrodesis using a minimally invasive approach and locking compression plates: Three cases


O. Brandenberger†‡, F. Rossignol‡*, S. Bartke§, T. van Bergen¶ and A. Vitte† †Clinique V


et Alfort, Maisons Alfort, France; §Tier€ arztliche Praxis f€


erinaire de Grosbois, Boissy St Leger; ‡Clinique Equine de l’Ecole Nationale V erinaire de Maisons ur Pferde, Warendorf-Milte, Germany; and ¶Department of Surgery


et


and Anesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. *Corresponding author email: fabricerossignol94@orange.fr.


Keywords: horse; carpal arthrodesis; minimal invasive; carpal instability; locking compression plate


Summary Three horses with carpal instability due to comminuted second carpal bone fractures (Cases 1 and 3), fracture of the head of the second metacarpal bone (Case 1) or comminuted fractures of the fourth carpal bone, ulnar and intermediate carpal bones (Case 2) were treated by minimally invasive approach for partial (Cases 1 and 3) or pancarpal (Case 2) joint arthrodesis, using locking compression plates. The joint cartilage was removed by either an arthroscopic approach (middle carpal joint and antebrachiocarpal joint) or a percutaneous drilling technique (carpometacarpal joint). Two or 3 locking compression plates were contoured to the dorsolateral, dorsomedial and dorsoaxial aspects of the carpal joints using a custom-made tunnelling tool and a minimally invasive tunnelling technique, and the screws were positioned through stab incisions. All cases recovered well, were lame free at the walk, were able to trot and gallop and could be used for leisure and pasture activities (partial carpal arthrodesis) and breeding (pancarpal arthrodesis). Post-operative x-rays showed progressive joint fusion after 12 months (Case 1), 5 months (Case 2) and 10 months (Case 3). Case 2 with a pancarpal arthrodesis showed a mechanical lameness at the walk due to the inability to flex the carpus. Carpal flexion after carpometacarpal and middle carpal arthrodesis in Case 1 was calculated to be 42.6° and 44° in Case 3.


Introduction


Comminuted or displaced fractures of the carpal bones are not common in horses and are often associated with major carpal instability (Auer and Lischer 2012). If accurate anatomical reconstruction of the fractured bone is impossible, the only treatment to restore weightbearing and to prevent deformity, severe osteoarthritis or opposite forelimb laminitis is joint arthrodesis. Two types of carpal arthrodesis have been described (Barr 1994; Carpenter et al. 2008; Auer and Lischer 2012). If one of the 3 carpal joints (carpometacarpal [CMC], middle carpal [MC] joint or antebrachial carpal [ABC] joint) or 2 (CMC and MC) are involved then partial carpal arthrodesis is appropriate. For partial joint arthrodesis, the CMC joint alone, the MC and CMC joint together, and the ABC joint alone can be fused. Range of movement after partial carpal arthrodesis is limited to the non-used joint (e.g. after ABC joint arthrodesis the range of flexion depends on the range of flexion of the MC joint) (Tulloch et al. 2015). However, if both MC and ABC


joints are affected, pan-carpal arthrodesis is recommended with complete loss of joint movement (McIlwraith et al. 2015; Tulloch et al. 2015). In high motion joints such as the metacarpophalangeal or ABC joints, arthrodesis is essentially a salvage procedure, the aim being to allow comfortable locomotion at pasture or to save the animal for breeding purposes. According to Lewis (2001), the long-term prognosis for salvage was good (81%) but complications included implant failure and contralateral laminitis. The standard approach is a slightly curved incision over the dorsal aspect of the distal radius (in the case of a pancarpal arthrodesis or partial ABC joint arthrodesis), carpus and proximal metacarpus (Barr 1994; Carpenter et al. 2008; Auer and Lischer 2012). Carpenter et al. (2008) described use of one 16- hole and one 14-hole large fragment locking compression plates (LCPs) for pancarpal arthrodesis, with a single 40 cm long vertical skin incision made on the dorsal aspect of the limb. The main disadvantages of a large incision include the higher exposure to contamination and the difficulties for closure of the incision, especially over one or more voluminous osteosynthesis plates. Minimally invasive plate fixation, keeping the skin over the plate intact and making small incisions over the plate holes to allow screw insertion, was described by James and Richardson in 2006, who employed this minimally invasive technique in 22 cases of incomplete distal third metacarpal/metatarsal condylar fractures, and 6 fetlock and 4 pastern arthrodeses (James and Richardson 2006). Here, we report our experiences with a minimally invasive approach for partial and pan-carpal arthrodesis, in which either 2 or 3 LCP were applied in 3 horses.


Case histories


Case 1 A 10-year-old Warmblood gelding was referred to the clinic with a radiographic diagnosis of an acute, displaced comminuted fracture of the second carpal bone (C2) and head of second metcaparpal bone (MCII) of the right front limb of unknown cause. The horse was referred immediately after injury with a large Robert Jones full leg bandage and a caudally-applied splint.


Case 2 A 10-year-old Arabian mare was referred due to the sudden occurrence of severe left forelimb lameness during an endurance race. The referring veterinarian diagnosed multiple fractures of the proximal row of carpal bones based


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