Titanium Elastic Stable Intramedullary Nailing for the Repair of Long Bone Fractures in Dogs

Bone is a metabolically active connective tissue composed of an extracellular matrix and bone cells (osteocytes) that provides structural support, protects vital organs and facilitates movement (Sayed et al., 2020). Long bone fracture is a common orthopaedic condition found in dogs (Harasen, 2001). The primary aim of any method of fracture fixation is to achieve the fastest possible healing by regeneration of mineralized tissue at fracture site and enabling the patient to function normally by allowing early mobility (Aron, 1998; Shahar, 2000; Marsell and Einhorn, 2011). Any internal fixation device is used to transmit the loads from one end of the bone to the other and to maintain alignment of the fractured fragments during the healing process (Gozna, 1982).

Elastic stable intramedullary nailing (ESIN) has become a well-accepted method of osteosynthesis of diaphyseal fractures in children and adolescents in medical sciences (Lascombes et al., 2006). Advantages of ESIN are minimal invasiveness, avoidance of growth plate injury, ability for direct mobilization to maintain joint movement and muscle tone as well as normal circulation, early bridging of callus and rapid restoration of bone continuity which leads to early limb function (Ligier et al., 1988; Mazda et al., 1997; Flynn et al., 2001; Flynn et al., 2004; Hunter, 2005; Lascombes et al., 2006). Titanium and stainless steel are commonly used as elastic nails and both of these metals result in adequate stabilization of the fractured bone (Perez et al., 2008; Wall et al., 2008; Gyaneshwar et al., 2016; Mohamed and Rajeev, 2017) but the use of titanium alloys has been increasing because of their appropriate mechanical properties, excellent biocompatibility and good corrosion resistance (Uhthoff et al., 1981; Cui et al., 2011). The titanium nails are more flexible, with a Young’s modulus of ~110 GPa, compared to stiffer stainless nails (~200 GPa). Despite a lower modulus of elasticity, titanium nails provided greater fracture stability than stainless steel nails in fixing femoral shaft fractures in a synthetic bone model (Mahar et al., 2004).

Ten dogs having long bone diaphyseal fracture (transverse, short oblique or comminuted) were selected (with the consent of owner) irrespective of their age, sex, breed and body weight for the repair of the fractures with ESIN technique by using titanium elastic nails (TENs). Thorough clinical, orthopaedic and radiographic evaluations were performed in all the animals at different time intervals i.e., at pre-operative, just post-operatively and at 15^th, 30^th and 60^th post-operative days. Selection of diameter of the nail was based on the pre-operative radiographic evaluation of diameter of the isthmus of the fractured bone (one-third diameter of the isthmus was taken as the diameter of the titanium elastic nail) (Fig 1). The surgical procedure was performed under general anaesthesia by using Inj. Atropine Sulphate @ 0.04 mg per kg b.wt (pre-anaesthetic) 10 minutes before the induction with a combination of Inj. Xylazine hydrochloride @ 1 mg per kg b.wt and Inj. Ketamine hydrochloride @ 5 mg per kg b.wt intramuscularly followed by maintenance of anaesthesia with isoflurane. Reduction of the fracture fragments was done by using closed method in one case of tibial fracture or open surgical method in other cases followed by passing of the nails from one fracture fragment to the other via the pre-drilled hole at the metaphyseal cortex (Fig 2). The hole at the metaphyseal cortex was created at an oblique angle by using a bone awl. For the open surgical method different approaches according to the long bone involved were used as per the technique explained by Piermattei and Greeley (1979). After achieving adequate fixation, the exposed portion of the nail was bent slightly away from the bone to decrease chances of nail migration and also to aid in pulling out of the nail at the time of nail removal, before cutting it near the surface of the bone with the help of nail cutter. Full cerclage wiring was used along with the titanium elastic nails in one case of comminuted fracture having three fracture fragments to hold the butterfly fragment along with the two fracture fragments. To facilitate removal of the nail, around 1-2cm of the exposed portion of the nail was left outside the bone and was covered with the subcutaneous tissue followed by a single horizontal mattress or simple interrupted suture with silk (# 1) for the closure of the skin wound. Once the fracture has been healed, removal of the nail was performed by making stab skin incision at the nail insertion site followed by pulling the nail with the help of extraction plier for TEN system. The skin wound at the nail removal site was closed by applying simple interrupted suture with silk (#1). For pre-emptive analgesia and prophylactic antibiotic, Inj. Meloxicam @ 0.3 mg per kg b.wt and Inj. Cefotaxime @ 20-25 mg per kg b.wt respectively, were injected intramuscularly for 5days. The intra-operative radiographic examinations were done using C-arm system (Allengers®-HF49R, Chandigarh, India) and for pre and post-operative radiographic examination, Siemens® X-ray machine and Konika Minolta® Computerized Radiographic System were used. Titanium elastic stable intramedullary nailing instrument set along with the titanium elastic nails having different diameters (2 mm, 2.5 mm, 3 mm and 3.5 mm) were used for the fracture repair in the study. Post-operative scoring for the bone union and bone formation were performed on the basis of extent of bridging callus formation and disappearance of the fracture line as per Lane and Sandhu (1987) (Table 1 and 2). Radiographic staging system given by Hammer et al., (1985) was used for the evaluation of the different stages of bone union at different time intervals (Table 3). Post-operative functional limb usage was evaluated on the basis of degree of lameness and graded by using classification system developed by Fox et al., (1995) on 60th post-operative day.







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In this study, six dogs were having body weight of more than 15kg, three were between 10-15 kg and one was having body weigh of less than 10 kg. Etiology of fracture, affected bone, location of fracture and type of fracture for all the cases are given in Table 4. For the confirmation of proper placement of the titanium elastic nail and proper anatomical reduction of the fracture fragments, C-arm radiography was performed intra-operatively which revealed satisfactory anatomical reduction and proper placement of titanium elastic nails in the present study (Fig 3). All the cases had shown gradual improvement in weight bearing on the operated limb starting from 4^th to 7^th post-operative day followed by complete weight bearing on 30^th post-operative day in seven cases and on 60^th post-operative day all the dogs had shown complete weight bearing without lameness while moving (Fig 4 and 5). Scoring for weight bearing on the operated limb while standing and walking was done at different time intervals of examination as per the scoring system given by Sahu et al., (2017) (Table 5 and 6). Postoperative radiographic examinations at 15^th, 30^th and 60^th days after the surgery showed satisfactory fracture alignment (Fig 6). On radiographic examination, evaluation of bone formation score and bone union score was done as per the scoring system given by Lane and Sandhu (1987). Mean±S.E. of bone formation score (BFS) and bone union score (BUS) increased from 0±0.00 at 0^th day to 3.7±0.15and 3.7±0.32 at 60^th post-operative day respectively (Table 7). Stages of bone union at different time intervals of all the dogs were recorded as per Hammer et al., (1985) which had shown achievement of bone union in 70% cases on 30^th post-operative day while on 60^th post-operative day it was achieved in all the cases (Table 8).



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All the cases had shown full range of motion of both in the proximal and distal joints on 60^th post-operative day on clinical examination. In the present study, satisfactory surgical wound healing was observed on clinical examination in nine cases within two weeks of surgery while in one case there was infection in sutures leading to delayed wound healing (18-20 days) due to owner negligence. On clinical examination, it was observed that there was slight migration of the nails at site of insertion in four cases (Fig 7) which were easily managed by cutting the extra length of the nail outside the skin along with regular antiseptic dressing with povidone iodine solution. The nail migration could be prevented be avoiding sudden rapid or jerky movements especially in highly active and medium to large size dogs for the initial 15 post-operative days. The nails were removed at 60^th day after assessment of fracture healing status on radiographic examination and weight bearing on clinical examination (Fig 8). Grading of functional limb usage was found to be excellent in seven cases, good in two cases and fair in one case.

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On the basis of clinical, orthopaedic and radiographic evaluations, it was concluded that Titanium elastic stable intramedullary nailing for the treatment of long bone fractures in dogs had good efficacy with respect to weight bearing and functional limb usage, however, migration of the nail at the insertion site was the main complication.