Clinical application of the smallI‐Locinterlocking nail in 30 feline fractures: A prospective study

Abstract

Objective: To describe medium-term functional outcome after nail osteosynthesis in feline traumatology and report clinically relevant recommendations for I-Loc angle-stable interlocking nail use in cats. Study design: Prospective clinical study. Sample population: Client-owned cats (n = 29). Methods: Consecutive cases with femoral, tibial, or humeral fractures were included. Outcome measures included fracture and surgical procedure description, limb alignment, nail size vs body weight (BW), percentage of nail medullary canal (MC) fill, time to limb function at clinical union (CU), and complications. Descriptive statistics were reported and compared with historical data. Results: Bone distribution was 53.3% femora, 30% tibiae, and 16.7% humeri. There were six epimetaphyseal and 24 diaphyseal fractures. Overall, 67% of fractures were comminuted. Open reduction and minimally invasive techniques were used in 73% and 27% of cases, respectively. Seventeen I-Loc 3 (cat mean BW 4.4 ± 2.2 kg) and 13 I-Loc 4 (cat mean BW 5.2 ± 1.2 kg) nails were placed with mean MC fill of ≤50%. Average time to CU was 7.2 weeks. At CU, lameness had resolved or was mild in every cat, and all cats ultimately regained full limb function. No major complications were encountered. Conclusion: Because of improved CU times, excellent functional outcomes, and low complication rate, our results provide evidence that I-Loc nails are safe and effective for feline traumatology. Clinical significance: The I-Loc may be advantageous for fixation of epimetaphyseal fractures. Because of feline bone specific dimensional constraints, I-Loc 3 is likely appropriate for all feline humeri and most tibiae, while I-Loc 4 is well sized for feline femora.

Feline Femoral Fracture Fixation: What are the options?

“…Supracondylar fractures can be surgically challenging as even simple fractures may not have inherent rotational or shearing stability and the distal fragment is inevitably short. 100 While stabilisation with dynamic intramedullary cross-pinning has been described, 101 rigid stabilisation with a bone plate, external skeletal fixator or angle-stable interlocking nail 81 is recommended, with care being taken not to penetrate the stifle joint 99 or impinge patellar tracking.…”

“…89,91 In addition, clinical studies have reported the use of the I-Loc system in a wide variety of feline fracture configurations with good outcomes. 81,92 It should be noted that interlocking nails can be placed without the need for fluoroscopy as palpation of anatomical landmarks while flexing and extending the leg has been shown to be accurate for limb alignment; 22 Although external skeletal fixators are particularly well suited to non-reconstructable fractures, they can be applied to all fracture types. It is important to realise, however, that they tend to result in more intensive postoperative management, including more visits for radiographs as a decision has to be taken as to when to remove them, and they can lead to a series of minor complications, most commonly pin tract infections or pin breakages.…”

“…70 By comparison, the angle-stable interlocking nail appears to be associated with a very low complication rate and rapid achievement of clinical union based on early clinical studies. 81 Other factors can also influence healing, including increasing age, increasing weight and increasing fracture complexity. 70…”

“…21 However, not all interlocking nails are compatible with retrograde placement and more recently normograde placement has been described for these fractures, with positive initial out-comes. 81 If available, fluoroscopic guidance should enable a true MIO approach with closed reduction and stabilisation. Alternatively, an OBDNT approach can be used successfully where fluoroscopy is not available.…”

“…23 However, newer interlocking nail systems have been developed that allow placement in bones with a diameter of only 6.4 mm at the level of the locking screws and, as such, multiple recent papers have described the use of interlocking nails for stabilisation of femoral fractures in cats. 12,21,[81][82][83][84] Interlocking nails are a modification of an intramedullary pin whereby typically one or two holes in the interlocking nail proximally and distally allow the placement of screws or bolts that engage the cis and trans cortex, and hence significantly increase axial and rotational stability of the implant. Intramedullary implants have several advantages.…”