Clinical and radiological evaluation of Titanium Tie-In Fixation (TTIF) for Tibiotarsus fracture repair in pigeon

Introduction

Tibiotarsus fractures are the most frequently encountered long bone injury in domestic pigeons, accounting for 51% (Kayikci et al., 2019) [9] , 50% (Kothamdi and Shilpa, 2016) [11] , and 43.82% (Sindhu et al., 2023) [13] . The avian tibiotarsus is anatomically vulnerable because of its thin cortices, large medullary cavity, relative paucity of surrounding musculature in the distal two-thirds, and load-bearing role during perching and locomotionpredisposes it to high-energy trauma (Westfall and Egger, 1979; Coles, 2007) [18,4] . Successful fracture management in birds demands a construct that is lightweight, rigid enough to allow early weight-bearing and easily removable without secondary surgery. Tiein fixation, combining an intramedullary (IM) pin with an external skeletal fixator (ESF), achieves multi-planar stability and has been demonstrated to yield good functional outcomes in raptors (Bueno et al., 2015) [3] and pigeons (Kaya and Ozsoy, 2017) [8] . The substitution of stainless steel with titanium alloy implants offers additional biomechanical benefits: a modulus of elasticity approximately half that of stainless steel reduces stress shielding, while superior biocompatibility and osseointegration potential reduce peri-implant reactivity (Uhthoff et al., 1981; Disegi, 2000; Skripitz and Aspenberg, 1998) [16,6,14] . The present study evaluated the clinical and radiological efficacy of titanium tie-in fixation (TTIF) using a PMMA connecting bar moulded within a commercial endotracheal tube for the management of tibiotarsus fractures in six domestic pigeons.

Materials and Methods

Six pigeons presenting to the Department of Veterinary Surgery and Radiology, Veterinary College, Hebbal, Bengaluru, with clinically and radiographically confirmed tibiotarsus fractures were enrolled. Cases were included regardless of age, sex, fracture morphology, or duration of illness. The study was conducted following institutional ethical guidelines. Complete physical examination was performed in all cases. Pre-operative orthogonal radiographs (cranio-caudal and medio-lateral views) of both the affected and contralateral tibiotarsus were obtained. Radiometric data from the contralateral limb: mean tibiotarsus length 5.30 ± 0.9 cm; mid-diaphyseal bicortical diameter 0.33 ± 0.01 cm; medullary canal diameter 0.23 ± 0.01 cm. These measurements guided implant selection. Case anamnesis is summarised in Table 1.

Pre-operative Preparation and Anaesthesia

On the day of surgery, feed was withheld for 3 hours and water for 1 hour. Enrofloxacin (10 mg/kg IM) and butorphanol (0.1 mg/kg IM) were administered into the pectoral muscles as pre-medication. General anaesthesia was induced with midazolam (0.5 mg/kg IM) followed by ketamine (30 mg/kg IM) five minutes later; maintenance was achieved with supplemental ketamine at half the induction dose as required. Induction was achieved within 2-3 minutes in all cases. Recovery was smooth, with all birds alert within 45-120 minutes of the last ketamine dose.

No anaesthetic complications were recorded. Feathers over the fracture site and below the hock were manually plucked following induction. A sterile bandage was applied to the hock, and the bird was positioned in lateral recumbency with the affected limb uppermost on a heating pad. The surgical field was prepared with 5% povidone-iodine scrub followed by sterile draping.

Implant Selection

Intramedullary K-wire diameter was selected to occupy approximately 50% of the medullary canal (≤ 1.

Post-operative Care and Staged Implant Removal

Post-operative care comprised daily antiseptic dressing (5% povidone-iodine) of K-wire entry points for one week, extended to alternate-day dressing thereafter. Enrofloxacin (10 mg/kg, SID, orally for 5 days), meloxicam (0.2 mg/kg, SID, orally for 3 days), oral calcium, and multivitamin supplementation (one drop daily for 14 days) were administered. Alternate-day passive physiotherapy was initiated 72 hours post-operatively to prevent knuckling, muscular spasticity, and joint rigidity. On day 14 th postoperative day, staged destabilisation was performed: the PMMA-IM K-wire link was severed and both transcortical K-wires were removed following radiological confirmation of adequate callus. The IM K-wire was removed by manual traction on day 21 th post-operative day after confirming sufficient consolidation (Fig 3).

Clinical and Radiological Evaluation

Clinical parameters (body weight, swelling, wound condition, lameness) were recorded pre-operatively and on 0 th , 7 th , 14 th , 21 th , and 30 th post-operative days. Weightbearing was graded using the Fox et al. (1995) [7] four-point scale (Excellent = full weight-bearing; Good = slight lameness only after exercise; Fair = slight to moderate lameness but consistent weight-bearing; Poor = intermittent or consistent non-weight-bearing). Lameness was scored on the Kestin gait scale (0 = no detectable abnormality; 5 = complete lameness, bird cannot walk) (Kestin et al., 1992) [10] . Radiological evaluation followed the Tunio et al. (2014) [15] scoring system using orthogonal views. Data were analysed using one-way ANOVA.

Results

The midazolam and ketamine protocol produced reliable induction in 2-3 minutes in all six birds with smooth recovery. All fractures were successfully managed by closed reduction. One intra-operative iatrogenic cortical splinter was noted in Case 2; this was evident on the day-0 radiograph and healed uneventfully by 30 th post-operative day (Fig 7b).

Weight-Bearing

All birds showed poor weight-bearing pre-operatively and on day 0. By day 7, five birds improved to fair weightbearing (one remained poor). By day 14, three birds achieved good and three remained fair. All six birds showed good weight-bearing by day 21 and excellent weightbearing by day 30 (Table 2) (Fig 4).

Lameness Scoring

Mean lameness scores declined progressively and highly significantly (P < 0.01) from 5.00 ± 0.00 pre-operatively to 0.33 ± 0.21 on 30 th post-operative day (Table 3), confirming near-complete restoration of ambulatory function. 2 0 Mean ± SE 5.00 ± 0.00 5.00 ± 0.00 4.00 ± 0.00 3.17 ± 0.31 2.17 ± 0.17

Radiological Evaluation

All four radiological parameters scored by the Tunio et al.

(2014) [15] system showed highly significant improvement (P < 0.01) from pre-operative to day 30 (Table 4). Preoperatively, the fracture line was visible in all cases and no callus was present. On day 7, a partially visible fracture line was noted in three cases, periosteal reaction was evident in all, and minimal callus formation was present. By day 14, four cases had a partially visible fracture line, all showed minimal-to-moderate callus formation, and all had progressed to secondary union. By day 21, four cases showed an absent fracture line and extensive callus, with four achieving primary union. By day 30, the fracture line was absent in five cases, extensive callus was present in all six, and five cases had achieved primary union (Fig 6). [15] Parameter Pre-op Day 0 Day 7 Day 14 Day 21 Day 30 Fracture Line 0.00 ± 0.00 0.00 ± 0.00 0.50 ± 0.22 0.67 ± 0.21 1.67 ± 0.21 1.83 ± 0.17 Callus Formation 0.00 ± 0.00 0.00 ± 0.00 1.00 ± 0.00 1.83 ± 0.17 1.83 ± 0.17 2.00 ± 0.00 Bone Union 0.00 ± 0.00 0.00 ± 0.00 0.17 ± 0.17 1.00 ± 0.00 1.67 ± 0.21 1.83 ± 0.17 Axial Alignment 0.50 ± 0.22 1.00 ± 0.26 1.17 ± 0.17 1.33 ± 0.21 1.33 ± 0.21 1.83 ± 0.17

Implant Performance

The TTIF construct remained stable in five of six birds throughout the study period. No loosening of transcortical K-wires was observed and the 90°-bent IM K-wire maintained secure connection to the external PMMA bar in all intact cases. After staged transcortical K-wire removal on day 14, the adhesive bond between PMMA and the IM Kwire could be overcome with considerable manual force, confirming PMMA integrity until that point. No metallic implant breakage or migration was recorded.

Complications

Complications recorded during the study included one case of intraoperative iatrogenic cortical splinter, which was evident radiographically on day 0 (

Discussion

The midazolam-ketamine protocol used in this study provided reliable induction, adequate surgical depth, and smooth recovery consistent with the recommendations of Atalan. ( 2002) [1] for domestic pigeons. The closed reduction approach preserved periosteal vascularity, which is critical in avian fracture healing (West et al., 1996) [17] , and avoided the iatrogenic trauma associated with open reduction. All six birds achieved excellent weight-bearing by day 30 which is in consistent with Bueno et al. (2015) [3] , who reported 84% clinical success (mean ~38 days) with ESF-IM tie-in fixation in 37 raptors with tibiotarsus fractures, and with Kaya and Ozsoy (2017) [8] , who documented comparable outcomes in tie-in fixation for tibiotarsal fractures in chukar partridges and pigeons. The significant progressive decline in lameness scores (P < 0.01) from 5.00 ± 0.00 to 0.33 ± 0.21 reflects the rapid restoration of weight-bearing mechanics that this construct affords. Radiologically, the pattern of secondary healing, periosteal reaction by day 7, callus bridging by day 14-21, and extensive callus with remodelling by day 30, is consistent with the established avian fracture healing timeline of 3-4 weeks for small birds in accordance with Bennett and Kuzma (1992) [2] and Tunio et al. (2014) [15] . Axial alignment improved to good in five of six birds by day 30, confirming that the TTIF construct maintained adequate fracture reduction despite functional weight-bearing throughout the healing period. The endotracheal tube PMMA bar provides a lightweight, customisable, and easyto-fabricate connecting bar. Its hollow construction reduces overall construct weight, a critical consideration in avian patients where body weight is a major flight parameter. The bar remained rigid and effectively immobilised all implants until day 14, at which point staged removal proceeded without complication in five of six cases. In one case of patient induced pin removal underscores the limitation of smooth (non-threaded) transcortical K-wires in an awake, biting bird; threaded transfixation pins have been recommended (Redig, 2005) [12] and should be considered in future cases. The biomechanical advantages of titanium over stainless steel have been well documented. Uhthoff et al.

(1981) [16] demonstrated that titanium plates (modulus of elasticity ~6× cortical bone) produce less stress shielding than stainless steel (~12× cortical bone), thereby preserving periosteal callus formation and facilitating earlier radiological consolidation. Disegi (2000) [6] further established titanium's superior fatigue resistance and biocompatibility. Skripitz and Aspenberg (1998) [14] confirmed enhanced osseointegration at the titanium-bone interface. These properties collectively explain the absence of peri-implant osteolysis and pin tract infections observed in the present study.

Conclusion

Titanium tie-in fixation using a PMMA connecting bar moulded in a commercial endotracheal tube is an effective, lightweight, and well-tolerated method for the repair of tibiotarsus fractures in pigeons. It provides rigid multiplanar stabilisation, supports secondary fracture healing with predictable callus formation, and permits progressive early weight-bearing. The biomechanical advantages of titanium over stainless steel implants, reduced stress shielding, superior biocompatibility, and osseointegration potential make TTIF particularly suited to avian orthopaedics. The use of threaded transcortical pins is recommended to prevent patient-induced implant disruption.

Acknowledgement

AcknowledgementsThe authors are thankful to the Department of Veterinary Surgery and Radiology and the Department of Veterinary Clinical Complex, Veterinary College Hospital, Hebbal, Bengaluru, for providing the diagnostic imaging and surgical facilities used in the management of this case.

References

1. Atalan G, Uzun M, Demirkan I, Yildiz S, Cenesiz M. Effect of medetomidine-butorphanol-ketamine anaesthesia and atipamezole on heart rate and cloacal temperature of domestic pigeons. J Vet Med A. 2002;49(6):281-285.
2. Bennett RA, Kuzma AB. Fracture management in birds. J Zoo Wildl Med. 1992;23(1):5-38.
3. Bueno I, Redig PT, Rendahl AK. External skeletal fixator intramedullary pin tie-in for the repair of tibiotarsal fractures in raptors: 37 cases. J Am Vet Med Assoc. 2015;247(10):1154-1160.
4. Coles BH. Surgery. In: Essentials of avian medicine and surgery. 3rd ed. UK: Blackwell; 2007. p. 142-182.
5. Degernes LA, Roe SC, Abrams CF. Holding power of different pin designs and pin insertion methods in avian cortical bone. Vet Surg. 1998;27(4):301-306.
6. Disegi JA. Titanium alloys for fracture fixation implants. Injury. 2000;31(4):D14-D17.
7. Fox SM, Bray JC, Guerin SR, Burbridge HM. Antebrachial deformities in the dog: Treatment with external fixation. J Small Anim Pract. 1995;36(7):315320.
8. Kaya DA, Ozsoy S. Repair of tibiotarsal rotation in 7 chukar partridges and 12 domestic pigeons with type 2 ESF-IM pin tie-in. J Avian Med Surg. 2017;31(3):206212.
9. Kayikci C, Kuşcu Y, Durmuş A, Aslan L. Fractures and treatment methods in wild avians. Van Vet J. 2019;30(2):115-119.
10. Kestin SC, Knowles TG, Tinch AE, Gregory NG. Prevalence of leg weakness in broiler chickens and its International Journal of Advanced Biochemistry Research https://www.biochemjournal.com relationship with genotype. Vet Rec. 1992;131(9):190194.
11. Kothamdi UY, Parikh PV, Patil DB, Kelawala DN, Tarware VB. Fracture repair in birds: A clinical study. Indian J Vet Surg. 2016;37(1):51-53.
12. Redig P. Orthopedic management of leg fractures. In: Proc NAVC, University of Minnesota. 2005. p.12021204.
13. Sindhu R, Velavan A, Pushkin Raj H. Incidence of long bone fractures in birds: A retrospective study. Int J Vet Sci Anim Husb. 2023;8(6):223-227.
14. Skripitz R, Aspenberg P. Tensile bond between bone and titanium: A reappraisal of osseointegration. Acta Orthop. 1998;69(3):315-319.
15. Tunio A, Abu J, Intan-Shameha AR, Meng GY, Shanthi G. Histological evaluation of transverse fracture healing in pigeon ulna. Res Opin Anim Vet Sci. 2014;3(10):380-386.
16. Uhthoff HK, Bardos DI, Liskova-Kiar M. The advantages of titanium alloy over stainless steel plates for the internal fixation of fractures: An experimental study in dogs. J Bone Surg. 1981;63(3):427-484.
17. West PG, Rowland GR, Budsberg SC, Aron DN. Histomorphometric and angiographic analysis of bone healing in the humerus of pigeons. Am J Vet Res. 1996;57(7):1010-1015.
18. Westfall ML, Egger EL. The management of long bone fractures in birds. Iowa State Univ Vet. 1979;41(2):8187.