Comparative study of femoral diaphyseal fracture repair using intramedullary pin and intramedullary horn peg in dogs

Introduction

Femoral fractures accounted for 37.83% of canine fractures at the Veterinary College Hospital, Bengaluru (July 2024-June 2025), mostly diaphyseal (56.64%) in males under 1 year (58.02%) and frequently due to automobile trauma (59.26%). Rising pet ownership and vehicular activity have increased long-bone fractures in small animal practice (Piermattei et al., 2006; Kushwaha et al., 2011) [8,9] . While some fractures heal conservatively, inadequate treatment risks malalignment, contracture and chronic dysfunction, and articular injuries often progress to osteoarthritis (Anderson et al., 1993) [1] . Open reduction and internal fixation (ORIF) with intramedullary devices remain the standard for femoral diaphyseal fractures because it restores anatomical alignment and provides stable fixation that permits early mobilization (Beale, 2004) [3] . Conventional stainless-steel intramedullary pinning (IMP) with Steinmann pins provides rigid stabilization but carries risks such as pin migration and infection; consequently, Interest has therefore turned to local biological alternatives: studies of bovine and buffalo horn implants show promising results, and buffalo horn pegs provide semi-rigid support, radiolucency for easier radiographic assessment, biocompatibility and low cost (Singh & Singh, 1990b; Dubey, 1991; Kulkarni, 2000) [10,11,12] . This study compares clinical efficacy, healing and complications of intramedullary buffalo horn pegs versus conventional Steinmann pins in 12 dogs to assess horn peg as a practical, affordable option for field practice.

The animals were randomly divided into two groups of six each: Group A underwent open reduction and internal fixation using intramedullary Steinmann pin, while Group B underwent repair using intramedullary horn peg prepared from buffalo horn. Femoral fractures were recorded over a 12-month period from July 2024 to June 2025, and case history including breed, age, gender, duration of fracture, concurrent illness and aetiology was documented for all animals. The design of the study is summarized in Table 1and 2.

Preparation of intramedullary horn peg

Buffalo horns were collected from cadavers, and the compact upper third was used to prepare the pegs. The horn was cut longitudinally, shaped into rectangular strips, and ground into intramedullary pegs with one-pointed end for retrograde insertion and one blunt end. (Fig 1234).

. [5] and functional limb use evaluated according to Vasseur et al. (1995) [15] .

Pre-operative preparation and surgical procedure

The dogs were fasted for 12 hours for food and 6 hours for water before surgery. The surgical site was prepared aseptically with spirit and 7.5% povidone iodine. Premedication included ceftriaxone, meloxicam, atropine sulphate and xylazine, followed by thiopentone sodium (12.5 mg/kg IV) for induction and maintenance of anaesthesia. The dogs were positioned in lateral recumbency with the affected limb uppermost (Fig. 5), and the limb was suspended briefly before surgery; the operative field was then repainted and draped aseptically. A craniolateral incision was made from the greater trochanter to the patella, the tensor fascia lata was incised (Fig. 6), the biceps femoris was retracted caudally and the vastus lateralis was exposed to visualize the femur (Fig. 7). In Group A, a Steinmann pin equal to about 70% of the narrowest medullary canal diameter was inserted retrogradely and advanced into the distal fragment, with cerclage wires applied when necessary.

In Group B, a horn peg of similar size was prepared, the proximal fragment was pre-drilled (fig. 15), and the peg was inserted retrogradely (Fig. 16) and advanced into the distal fragment, with zap straps used as needed for ancillary fixation (Fig. 17).

Surgical procedure of group a dogs

Post-operative care and management

Owners were advised to use an Elizabethan collar until suture removal. Cephalexin (20 mg/kg BID) was given for 7 days and carprofen (2 mg/kg SID, oral) for 3 days, with the wound dressed using povidone iodine ointment on alternate days. Skin sutures were removed on day 10 after assessing wound healing. Movement was restricted for 15 days, followed by short leash walks, limb flexion-extension exercises and massage for the next few weeks to support recovery and prevent muscle atrophy.

Results And Discussion

Physiological, haematological and biochemical results (pre-op, 0, 7, 15, 30, 45 and 60 days) for rectal temperature, heart rate and respiratory rate remained within normal limits in both groups these findings align closely with Tembhurne et al. (2010) [14] and Srinivas (2022) [13] . Haematological (TEC, Hb, TLC, PCV, differential counts) and biochemical (serum creatinine, ALT, ALP, calcium, phosphorus) values remained within reference ranges throughout follow-up these findings align closely with Yadav et al. (2021) [16] . Statistically significant within-group changes (p<0.05) were limited and included intermittent neutrophilia, transient lymphopenia and modest increases in ALP and phosphorus at time points consistent with bone healing this aligns with Mahendra et al. (2007) [6] .

Post-operative function and weight bearing both groups showed progressive improvement. In Group A most dogs achieved partial weight bearing by 15-30 days, attempted weight bearing by day 30 and full weight bearing by day 45; one dog reached Grade I lameness only by day 60. In Group B early recovery was faster most dogs were Grade III by day 15 and Grade II by day 30; one dog remained Grade II until day 45. All dogs in both groups reached Grade I lameness by day 60. These findings align with Badigera (2013) [2] .

Functional limb usage in group a dogs

Before Surgery 0 th Day 60 th Post-op Day

Radiographic observations

Pre-op and serial radiographs (0, 7, 15, 30, 45, 60 days)

showed initial anatomical alignment in all cases; Steinmann pins were radiopaque, horn pegs radiolucent. By day 7 fracture margins had blurred with early demineralisation. Day 15 showed periosteal reaction and early callus with maintained alignment. At day 30 Group A had limited feathery callus at fracture ends; Group B had more extensive callus extending ~1 cm beyond the fracture this finding aligns with the Nagaraja et al. (2003). By day 45 Group A showed denser callus and advancing union; Group B showed larger irregular callus and one case with cortical lysis. At day 60 Group A demonstrated near-complete union with a smaller, remodeled callus; Group B showed larger callus and increased medullary density. These observations are in concurrence with Dubey et al. (1993) [4] .

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