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Use of a circular external skeletal fixator to treat comminuted metacarpal and tibial fractures in six calves
  1. H. Bilgili, DVM, PhD1,
  2. B. Kurum, DVM, PhD1 and
  3. O. Captug, DVM1
  1. 1 Department of Surgery, Faculty of Veterinary Medicine, Ankara University, 06110 Diskapi, Ankara, Turkey

Abstract

A circular external skeletal fixator system was used to fix long-bone fractures in six calves, three with tibial fractures and three with metacarpal fractures. An Ilizarov apparatus of appropriate diameter, depending on the calves' bodyweight, was used. In the postoperative period, clinical and radiological examinations were carried out to assess fracture healing, the stability of the fixator and when the calves could make full use of the limb. The fixator was tolerated well, the fractures healed and the fixators maintained rigid stability. The calves were able to use their limbs fully after between 15 and 27 days.

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FRACTURES of the metacarpus and metatarsus are common in calves and account for approximately 50 per cent of fractures (Tulleners 1986, Auer and others 1993). Fractures of the metacarpus are twice as common as metatarsal fractures (Ferguson 1982), and their incidence exceeds the total incidence of radial and tibial fractures (Steiner and others 1993). The other long bone with a significant fracture rate in calves is the tibia. Tibial fractures generally occur in the diaphysis and tend to develop into an open fracture. The trauma may also cause injury to the growth plates that may result in a fracture in the epiphysis, or epiphysiolysis (Ferguson 1982, Tulleners 1986, Auer and others 1993, Nuss and others 1996). Long-bone fractures may occur as a result of the force applied during parturition, trauma caused by the dam or other animals, during transportation (Ferguson and others 1990, Steiner and others 1993) or as a result of falls or traffic accidents (Aithal and others 2004, 2007).

Different internal and external fixation methods may be used to fix long-bone fractures in calves, depending on the type of fracture and the bodyweight of the calf. A coaptation cast is the most frequently used method for simple transverse bone fractures and mid-diaphyseal bone fractures (Ferguson 1982, Tulleners 1986). Other options are transfixation pinning (Nemeth and Numans 1972, Ferguson 1982, Nemeth and Back 1991), intramedullary pinning (St-Jean and others 1992, Auer and others 1993), bone plates and intrafragmental compression screws (Ferguson 1982, Aslanbey and others 1997). However, problems such as osteomyelitis, and non-union and angular deformity reduce the success rate of these treatments in comminuted, open and infected fractures (Pistani and others 1997, Bilgili and others 1999a, Olcay and others 1999).

The Ilizarov method is an alternative method for treating comminuted fractures (Kurum and others 2002, Aithal and others 2004, 2007, Bilgili and others 2006, 2007) that allows earlier mobility in the whole limb and joints (Olcay and Bilgili 1999) and makes it possible to compress or distract the fragments (Ilizarov 1989, Ferretti 1991, Elkins and others 1993, Pistani and others 1997), giving it advantages over the other methods.

In this study, metacarpal and tibial fractures in six calves were treated by the application of the Ilizarov method and a circular external skeletal fixator.

MATERIALS AND METHODS

Three of the calves had comminuted fractures of the metacarpus and three had comminuted fractures of the tibia. The characteristics of the calves are shown in Table 1. They ranged in age from nine days to 5·5 months, and their bodyweights ranged from 65 to 140 kg.

Anaesthesia

The calves were premedicated with 0·1 mg/kg xylazine hydrochloride (XylazineBio 2%; Bioveta) administered intravenously, and general anaesthesia was induced and maintained with isoflurane (Taymed) administered by mask.

Preoperative planning

The affected limb was examined carefully. The digital arterial pulse and vascularisation of the part distal to the fracture line were evaluated by digital podometer. Anterioposterior and mediolateral radiographs of the affected and intact limbs were taken (Figs 1, 2, 3). The diameters of the rings of the Ilizarov circular external skeletal fixation system, number of rings (Taylor 1990), number and diameter of the appropriate Kirschner pins (Bilgili and others 1999b, 2006, 2007), vascular distribution, and innervations and anatomical cross-section of the region were determined from the radiographs. The fixator was assembled and tried on the fractured limb to determine its suitability.

FIG 1

Preoperative anterioposterior radiographic view of a tibial fracture in a four-month-old calf (case 2)

FIG 2

Preoperative mediolateral radiographic view of the tibial fracture in case 2

FIG 3

Preoperative anterioposterior radiographic view of a metacarpal fracture in a nine-day-old calf (case 5)

Operation

The metacarpal fractures (cases 1, 4 and 5) were stabilised using an apparatus configured with either two full rings (cases 1 and 5) or one half ring (case 4) for the proximal fragments of the fracture, and either one full ring (cases 1 and 5) or two full rings (case 4) for the distal fragment (Table 1). The tibial fractures (cases 2, 3 and 6) were stabilised using an apparatus configured with one full and one half ring for the proximal fragments of the fracture and one full ring for the distal fragment (Table 1). In case 3, a hybrid fixation with two Schanz pins was applied in addition.

In each case, two 2·0 mm diameter Kirschner wires were used for each ring in divergent positions (Fig 4). Holes for the wires were drilled through the bone with a low-speed drill (150 rpm). Tension was applied to the wires on the half rings with a force of 50 kgf and on the full rings with a force of 90 kgf, by means of a dynamometric pin tensor machine (Tensiometer; Tipsan cef). The wire placed in the distal fragment in cases 3, 4, 5 and 6 was passed through the metaphysis, but in cases 1 and 2 it was passed through the epiphysis owing to the smaller size of the distal fragment in these cases. In cases 1, 2, 3, 5 and 6 the fixation was maintained by limited open reduction and the Ilizarov apparatus. In case 4, the fracture fragments were stabilised by closed reduction and the Ilizarov apparatus.

FIG 4

Postoperative anterioposterior radiographic view of the tibial fracture in case 2

Cases 1, 2, 3, 4 and 6 were operated on within 24 hours of the fracture occurring, but case 5 was operated on nine days after the fracture. This delay occurred because the case had been treated with a cast applied by a different veterinarian. Samples were collected from the open fracture area of this case for an antibiogram test, which revealed Staphylococcus epidermidis.

Postoperative follow-up

Radiographs were taken immediately after the operation, and its success was evaluated by checking the position of the fracture fragments of the stabilised bones and the levels and directions of the wires (Figs 4, 5). During postoperative care, rifamycin (Rif Amp; Kocak Pharma) and nitrofurazone (Furacine soluble dressing ointment; Eczacibasi) absorbed on gauze sponges were applied to each pin track daily for seven days to prevent infections (Paley 1990, Bilgili and others 1999b). Cases 1, 2, 3, 4 and 6 were treated daily for 10 days with 48 mg/kg trimethoprim-sulfadimethylpyrimidine (Richter Pharma), both administered intramuscularly, and case 5 was treated for another five days owing to the nature of the open fracture. For pain relief, 3·0 mg/kg ketoprofen (Profenid; Eczacibasi) was administered intramuscularly once a day for three days. To evaluate any interference with local circulation, the fracture site and the limb distal to it were evaluated regularly for colour change, digital pulse, temperature increase, oedema, swelling and haematoma.

FIG 5

(a) Anterioposterior and (b) mediolateral radiographic views taken after the repair of the metacarpal fracture in case 5

The whole apparatus on the fracture site was covered completely to prevent the animal licking it and to protect it from the animal's surroundings. The owners were advised to restrict the animal's exercise and to contact the clinic if there was any unusual drainage from the pin tracks or any failure of the apparatus. The stabilised fractures were checked by routine clinical and radiological examinations at two-week intervals for between 65 and 340 days. Any pin track drainage was scored by Paley's classification (Paley 1990).

RESULTS

All the calves tolerated the apparatus well and all the fractures healed completely (Fig 6). During the postoperative clinical and radiological examinations (Fig 7) no changes in the configuration of the apparatus, deformation or loosening of the wires, or bone lysis were observed. There was no evidence of deformity in the contralateral limb due to excess weight bearing, and no evidence of damage to nerves or blood vessels. In case 3 there was a second degree serous drainage in two pin tracks, and in case 4 a third degree serous drainage in three pin tracks. These problems were overcome within a week by appropriate care of the pin tracks. There was no evidence of a periosteal reaction around the fracture site except in case 5. No major complications such as osteomyelitis were encountered. In all the cases, oedema was observed in regions distal to the operation sites during the first two days after the operation, but it had resolved by the third day without any intervention.

FIG 6

View of case 5 as it began to use its treated limb

FIG 7

(a) Anterioposterior and (b) mediolateral radiographic views of the metacarpal fracture of case 5 after it had healed completely

The calves had their operated limbs touching the ground by the second to the eighth day (average four days) and they began weight-bearing after 15 to 27 days (average 21 days). The fractures had healed radiologically after 35 to 48 days (average 42 days) and the apparatus was removed after 45 to 63 days (average 57 days) to ensure that the bone did not refracture. No casts were applied after the removal of the apparatus, and the owners were recommended to keep the calves in their boxes for a week. No refractures or deviations at the fracture site were observed.

DISCUSSION

Over the past three to four decades, new fracture fixation techniques have been introduced, but there has been no consensus on the fixator and implant that can provide the most suitable conditions for fracture healing (Caulhon and others 1992). In the past, rigid fixation of the fracture after anatomical reduction has been considered the ‘gold standard’. In contrast, the Ilizarov circular external skeletal fixation system allows a limited degree of axial movement at the ends of the fracture, and this movement has been shown to stimulate callus formation and healing (Goodship and Kenwright 1985, Kenwright and others 1986).

The Ilizarov system does not have a standard configuration as in other systems, and its configurations are determined on a case-by-case basis; furthermore, modifications or corrections to the configuration of the apparatus can be made during or after surgery (Kurum and others 2002, Bilgili and others 2007). In this study, the fixation system was assembled in accordance with the clinical and radiological data for each case, to minimise the potential failure rate of the operation.

There are situations in which the Ilizarov method has advantages over the other fixation techniques (Bilgili and others 1999a, 2006, 2007, Olcay and others 1999). Unlike conventional fixators, the Ilizarov system has a non-linear load-deformation curve; as a result, Ilizarov fixators maintain stability more efficiently by resisting destructive forces more strongly until the plastic deformation point (Gasser and others 1990), a characteristic that is beneficial in the fixation of long-bone fractures in calves. It is well known that crossbreed calves gain more weight in a short period of time. Two mixed-breed calves, aged three months and four months and weighing 65 and 75 kg, respectively, were included in the study. Holstein calves gain 40 to 50 kg during the first two to four months of their lives. The fixator was removed after 45 to 63 days (average 57 days). Considering the potential weight gained during this period, it is possible that the limits of rigidity of the fixator would have been overcome. For this reason, the Ilizarov system is ideal for fixing fractures in growing animals such as calves.

The Ilizarov system can easily be applied to comminuted fractures and fractures with epiphyseal or metaphyseal fragments. Kirschner wires of small diameter can maintain rigid fixation with minimum traumatic effect (Bilgili and others 1999b, 2006, Olcay and Bilgili 1999). The Ilizarov system also has a unique biomechanical property called axial microelasticity (Ilizarov 1989) that has a positive influence on fracture healing without reducing the rigidity of the system (Ilizarov 1989, Ferretti 1991, Kurum and others 2002). The results of this study exemplify the successful use of the Ilizarov system in comminuted or open fractures of the long bones of calves.

In dogs, there have been many reports of the use of the Ilizarov system in the treatment of fractures (Ferretti 1991, Bilgili and others 1999b, 2006, 2007, Olcay and Bilgili 1999), the correction of deformities, bone lengthening and distraction osteogenesis (Elkins and others 1993). There have been only a limited number of studies of the use of the Ilizarov system in large animals (Ferretti 1991, Pistani and others 1997, Olcay and others 1999, Bilgili and others 1999a, Aithal and others 2004, 2007, Rubio-Martinez and others 2007). Compared with cats and dogs, calves live in relatively dirty surroundings and have almost no ability to groom themselves (Bilgili and others 1999a, Olcay and others 1999). In this respect, the Ilizarov system is easy to clean, and makes it possible to dress the limb during the postoperative period and clean the pin tracks daily. Postoperative complications are relatively rare, and the fracture heals and becomes weight-bearing more quickly. However, it is important to disinfect the pin tracks to prevent pathogens reaching the bone tissue and causing osteomyelitis (Bilgili and others 1999a, Olcay and others 1999).

With the Ilizarov system, complications such as neurovascular damage, pin track infection, pin loosening or breaking, non-union, malunion, insufficient callus, compartment syndrome, muscle and joint contractures, pain, and oedema may occur (Paley 1990, Bilgili and others 1999a, b, Olcay and Bilgili 1999, Olcay and others 1999). In this study, pin track infection was observed in only two cases controlled easily by daily care.

The tension applied to the pins in the Ilizarov system is important in maintaining the stability of the fracture. The diameter of the pins is determined according to the animal's bodyweight. However, investigators have applied different tensions to pins of different diameters and have all considered that these different values were appropriate (Ferretti 1991, Kurum and others 2002, Aithal and others 2004, 2007). It is commonly agreed that pins 1·8 mm in diameter and 70 to 90 kgf tension would be sufficient for a medium-sized dog (25 to 30 kg). Paley (1991) found that the average bending values of Ilizarov apparatus using Kirschner wires 1·2 mm, 1·5 mm and 1·8 mm in diameter were 120 kgf/mm2, 210 kgf/ mm2 and 305 kgf/mm2, respectively, and suggested that the tension applied to the wires should not be more than half the bending value. In this study, 50 to 90 kgf tension was applied to pins 2·0 mm in diameter, and these values were considered sufficient for a calf weighing approximately 140 kg.

This study describes the successful and safe use of Ilizarov's circular external skeletal fixation system for the treatment of comminuted, open and oblique long-bone fractures in six calves. Owing to its biomechanical properties, the Ilizarov system should be considered as an alternative method for treating fractures in farm animals and horses.

References

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