Plate design

The AOTK approved LCP Equine T-Plate 4.5 is indicated for the treatment of physeal fractures of the proximal tibia in foals. The plate is made of 316L stainless steel, is compatible with the Large Fragment system, and available in the following sizes (Fig 2):

• 4-hole plate (91 mm)
• 6-hole plate (127 mm)
• 8-hole plate (163 mm)
• 10-hole plate (199 mm)

The screw trajectory is designed to optimize bony purchase. Furthermore, cortex screws can be applied through the plate in lag fashion to compress the metaphyseal fracture common in type 2 physeal fractures of the proximal tibia in foals. Additional wire holes allow temporary fixation with K-wires in the epiphysis, and combi-holes allow cortex screw and locking screw fixation at the discretion of the surgeon (Figs 3 and 4):

• Stacked combi-holes in the head of the plate accept locking and cortex screws
• Standard combi-holes in the straight portion of the plate allow screw selection as well as the opportunity to provide dynamic compression between fracture segments with cortex screws
• Incorporation of locking technology permits a fixed-angle device to increase construct stability and augment fixation in soft, immature bone.

Versatility

The Equine T-Plate, which incorporates locking technology, is intended to enhance fixation in short fracture segments where traditional plate fixation would be inadequate. Although the plate has been designed to treat physeal fractures of the foals proximal tibia, there are a wide variety of other applications including physeal or metaphyseal fractures of other long bones as well as partial carpal and tarsal arthrodesis.

The two cases presented here demonstrate the utility of the Equine T-Plate to provide solid fixation in short fracture segments. Specifically, the T-portion of the plate can be used to engage up to 3 locking screws in fracture segments where standard plate fixation would be inadequate. In addition, case 2 also shows that even in neonatal bone, where the holding power of standard cortex screws can be a limitation, multiple locking screw fixation provides a strong, stable construct. Case 1 demonstrates that the Equine T-Plate has application in other locations, where fixation is limited by close proximity to a joint. Many additional indications exist where the ability to provide multiple locking screw fixation is limited by proximity to a joint or physis and the Equine T-Plate will provide a useful solution.

Case 1: Elective partial carpal arthrodesis in a warmblood broodmare

(Case provided by Fabrice Rossignol, Paris, France)

A 4-year-old French warmblood broodmare weighing 570 kg presented with a 5-day history of severe right forelimb lameness following an unwitnessed paddock accident. The limb had been stabilized in a Robert-Jones bandage with caudal and lateral splints prior to referral. The radiographs confirmed a slab fracture of the third carpal bone as well as a comminuted biarticular fracture of the fourth carpal bone (Fig 5). An arthrodesis of the carpometacarpal and middle carpal joint was elected.

The day after admission, the mare was placed under general anesthesia in dorsal recumbency for a partial carpal arthrodesis of the right carpometacarpal and middle carpal joints. The middle carpal joint was examined arthroscopically, and all visible articular cartilage was removed by using a combination of manual (bone curette) and motorized (shaver/burr) instrumentation (Fig 6). A 4.5 mm drill bit was used to drill across the carpometacarpal joint surfaces. A cancellous bone graft harvested from the sternum was loosely packed into the repair through an arthroscopic portal with the leg in flexion. Following graft insertion, implants were placed using a minimally invasive technique, tunneling the plate under the skin and joint capsule, and stab incisions for screw insertions. A 6-hole LCP Equine T-plate 4.5 was applied to the dorsal aspect of the limb deep to the extensor tendons and joint capsule through an enlarged arthroscopic portal between the extensor carpi radialis and common digital extensor tendon using a plate passer. A 4.5 mm cortex screw was placed in the first hole of the shaft of the plate to compress the plate to the bone. Two 5.0 mm locking screws were placed in the holes of the horizontal portion of the plate to engage the intermediate carpal bone. A third 5.0 mm locking screw was placed into the radial carpal bone using the last hole of the horizontal portion of the plate (Fig 7). All remaining holes were filled with 5.0 mm locking screws except the second hole, which was left empty because the hole was directly over the carpometacarpal joint. A 6-hole narrow LCP 4.5 was applied dorsolaterally and a 6-hole narrow LCP 4.5 was placed dorsomedially in a similar manner. The skin incisions were closed in routine fashion, and a sterile dressing and full limb cast were applied. The mare recovered uneventfully from anesthesia with head and tail assistance.

The cast was removed 24 hours postoperatively, and a Robert- Jones bandage with caudal and lateral splints was maintained for 1 month. The mare made excellent postoperative progress with immediate full weightbearing on the operated leg. At 5 months postoperatively, radiographic evaluation confirmed excellent healing of the fracture and almost complete fusion of the middle carpal and carpometacarpal joints with preservation of the radiocarpal joint (Fig 8). At one year postoperatively, the mare showed a very good cosmetic aspect of the carpus, as well as an excellent locomotion at three gates, with only minor mechanical lameness due to reduction of carpal flexion (Fig 9).

Case 2: Complete distal radial fracture in a 4-hour old foal

(Case provided by Thijs de Bont, Brussels, Belgium)

A 68 kg Warmblood foal was presented for evaluation and treatment of a complete open fracture of the left distal radius sustained during parturition 4 hours earlier. The fracture had occurred when the mare laid down against the wall of the stables while the foal was partially through the birth canal. The foal had been recumbent since birth. The limb had been partially stabilized with a full limb bandage and lateral splint prior to admission. The radiographs confirmed the presence of a complete slightly oblique (proximomedial to distolateral) open fracture, just proximal of the distal radial physis (Fig 10). Extensive maceration of the medial soft tissues just proximal of the carpus was noted, with a 0.5 cm full thickness skin laceration. The foal was stabilized and was taken to surgery a few hours following admission.

The foal was anesthetized and placed in dorsal recumbency. The left forelimb was placed in extension, clipped, prepared, and draped for aseptic surgery. A cranial approach to the distal aspect of the radius was made. The fracture was reduced, and a 6-hole LCP Equine T-Plate 4.5 was placed beneath the extensor carpi radialis (Fig 11). Two 5.0 mm locking screws were placed in the horizontal portion of the plate to engage the distal portion of the radius, just proximal of the distal radial physis. A 4.5 mm cortex screw was then placed into the second hole of the shaft of the plate, to provide interfragmentary compression and compress the plate to the proximal portion of the bone. The remaining holes were filled with 5.0 mm locking screws. The presurgical planning had included placing a second lateral LCP plate, however, the foals physiological status deteriorated. Further fracture fixation was therefore abandoned, and the surgery site was closed. A tube cast was placed from the level of the fetlock to the proximal radius. The foot and pastern were left free to minimize flexor tendon laxity. The foal was placed in sternal recumbency and required 2 hours of assisted ventilation before she started to breath spontaneously. Following surgery, she stood unassisted and was able to ambulate and suckle.

The cast was changed every 7 days and was replaced with a two-layer full limb bandage 28 days postoperatively. Carpal hyperextension was counteracted with an elastic band taped to the palmar aspect of the limb under tension, to prevent hyperextension when the limb was loaded (Fig 12). Tensions were adjusted depending on the increasing weight and strength of the foal. Once the cast was removed, the foal was hand walked daily.

Postoperatively, the foal was noted to have a moderate carpus valgus deformity. Radiographic assessment, however, showed that the lateral deviation was not due to malalignment of the fracture. A gradual improvement in the degree of valgus deformity has been seen with growth as the foal has matured (Fig 13). Radiographic healing of the fracture has proceeded quickly with very little callus formation (Fig 14).