Evaluation of Figure-of-eight Cerclage Wire Technique for Distal Femoral Physis Fractures (Salter-Harris Type I and Type II) in Cats

Distal femoral fractures account for 20-32% of femoral fractures in cats and commonly involve the physis in immature animals, particularly between 4 and 11 months of age (Gill et al., 2018; Bondonny et al., 2023; McNicholas et al., 2002). Salter-Harris type I and II fractures are most prevalent, representing around 77% of cases (Cağatay et al.  2013; Rubinos et al., 2021; Altuğ et al., 2019). Surgical intervention is typically required to ensure anatomical reduction and protect future growth (Voss et al., 2007), with emphasis on preserving vascular supply and avoiding implant-related compression (Altunatmaz et al., 2017; Dhanalakshmi et al., 2020; Guiot et al., 2017; Roberts et al., 2022). Given the distal femoral physis’s major contribution to limb growth 75% of femoral and 40% of overall limb length physeal-sparing techniques are essential, especially since closure may be delayed in neutered males (Bondonny et al., 2023; Perry et al., 2014).
               
Various osteosynthesis techniques have been employed for distal femoral physeal fractures in cats, including normograde or retrograde intramedullary pinning, open or fluoroscopy-assisted percutaneous pinning and Rush or cross-pinning methods (Cebeci et al., 2021; Gill et al., 2018; Altuğ et al., 2019; Boekhout-Ta et al., 2017; Pravalika et al., 2023). While these approaches have yielded successful outcomes, limitations such as insufficient rotational or distraction stability, unsuitability for chronic fractures and a heightened risk of premature physeal closure particularly with cross-pinning have been reported (Boekhout-Ta et al., 2017; Hudson et al., 2020; Voss et al., 2009; Bondonny et al., 2023). Recent studies suggest that parallel K-wire placement may better preserve longitudinal growth and reduce physeal stress compared to cross-pinning (Inal et al., 2019; Ma et al., 2017). This highlights the potential advantages of techniques that minimize physeal contact. Among them, the figure-of-eight cerclage wire, placed parallel to the distal and proximal fragments, requires further investigation. Initially, clinical outcomes were first reported by Spångberg et al., (2019), with this study aiming to evaluate its efficacy in a larger cohort, assessing short-, medium- and long-term outcomes in treating Salter-Harris type I and II distal femoral fractures in cats.

Study group
 
This study included 30 cats with Salter-Harris type I or II distal femoral fractures, treated with a figure-of-eight cerclage wire at Harran University Veterinary Faculty (2020-2023). Only cases with complete radiographs and regular postoperative follow-ups were included. Clinical evaluations included vital signs (temperature, pulse, respiratory rate; Mindray UMEC12VET), hemogram (pocH-100i^®, Sysmex), serum biochemistry (Spotchem EZ SP 4430, Arkray) and blood gas analyses (GEM Premier Plus 3000). Parameters such as WBC, RBC, MCV, MCH, MCHC, hemoglobin, glucose, creatinine, cholesterol, ALT, AST, bilirubin, albumin and CRP were assessed. Bone palpation, crepitation, soft tissue damage and neurological exams were conducted to monitor recovery and prevent complications. Data collected included breed, sex, age, fracture type (open/closed), cerclage wire diameter, complications and follow-up outcomes (short-, mid- and long-term). The study protocol was approved by the Local Ethics Committee on Animal Experiments, Harran University (session and permit number: 2023-008/07).
 
Surgical procedure
 
Anesthesia was induced with propofol (3 mg/kg, IV) following premedication with xylazine HCl (0.1 ml/kg, IM). Sevoflurane (2-3%) and 100% oxygen maintained anesthesia throughout the procedure. The surgical site was disinfected with benzalkonium chloride and povidone-iodine and intraoperative fluid therapy (NaCl 0.9%, 10 ml/kg/h) was provided. The cats were positioned in lateral recumbency, with the affected leg on top. The distal femur was exposed via arthrotomy, using a lateral or medial parapatellar approach and the patella was displaced to access the fracture site (Hudson et al., 2004) (Fig 1A). A unilateral approach was employed, following the method described by Spångberg et al., (2019). After cleaning the fracture fragments and ensuring a clear operative field, cranial traction was applied to the proximal tibia for reduction. Two parallel holes were drilled into the fracture fragments using a 1 mm Kirschner wire. Cerclage wires (1.25 -1.5 mm diameter, 10 cm length) (Fig 1B) were threaded through these holes and alternately tightened from both the lateral and medial sides to stabilize the fracture (Fig 1C). The distal and proximal holes were positioned to optimize fixation and prevent caudal displacement of the distal fragment. The wires were placed in a figure-of-eight configuration, ensuring the intersection point was slightly proximal to the fracture site to avoid patellar interference. After tightening the wires with a cerclage wire tool (Greatlh Betterhealh®, China), the excess wire was trimmed, leaving approximately three folds on each side (Fig 1D). The patella was repositioned and the joint was irrigated with saline. Crystalline penicillin (Vetimycin, Vetas, Turkey) was administered to reduce infection risk and the joint capsule was closed with absorbable Polyglycolic Acid sutures (Alcasorb, Katsan, Turkey). The surgical field was closed in layers, with no intraoperative complications observed. Postoperative radiographs confirmed fracture stability. The cats were recommended six weeks of cage rest, with Robert Jones bandaging for two weeks. Meloxicam (0.03 mg/kg, SC) was given for 3 days and amoxicillin-clavulanic acid (12.5 mg/kg, PO) was prescribed for 7 days (closed fractures) or 3-6 weeks (open fractures). Short-term physiotherapy started after bandage removal. Radiographs were taken every two weeks for 6-8 weeks to monitor healing.


 
Follow-up assessment
 
Postoperative assessments were carried out at 2 weeks, 6-8 weeks and at mid-term (6-12 months) and long-term (>1 year) through telephone interviews. Veterinarians and owners were asked about lameness or pain in the treated limb, with further care or diagnostics provided as needed.
       
Outcome evaluation involved grading lameness on a 5-point scale (0 = normal, 1 = mild limping with partial weight bearing, 2 = severe limping with partial weight bearing, 3 = severe limping with intermittent weight bearing and 4 = no weight bearing), a validated owner questionnaire and radiographic assessments of both the treated and healthy limbs (Cook et al., 2010). Functional outcomes were categorized as complete, acceptable, or  unacceptable, based on the return to pre-fracture status. Complications were classified as destructive, major, or minor, with destructive complications leading to permanent dysfunction or euthanasia, major requiring further intervention and minor resolving without additional treatment (Arkader et al., 2007). All complications and treatments were documented.
 
Radiographic assessment
 
Orthogonal radiographs of the fractured femur were taken preoperatively, postoperatively and at follow-ups (2^nd, 4^th, 6^th and 8^th weeks). Three observers, including the surgeons, evaluated the radiographs. Preoperative fractures were classified according to the Salter-Harris system and categorized by displacement severity as described by Arkader et al., (2007). Degree 1= <1/3 of bone width; degree 2= 1/3 to 2/3 of bone width; degree 3= >2/3 of bone width. (Fig 2) postoperative radiographs confirmed correct placement of cerclage wires and satisfactory alignment. Wire positioning was considered satisfactory if placed correctly in the distal and proximal fragments, with the intersection point slightly proximal to the fracture site, arranged in a figure-of-eight to prevent interference with patellar function. Cortical alignment was also assessed, with slight overreduction in the mediolateral view deemed acceptable. Bone healing was evaluated using a scoring system from Cook et al., (2010), based on the presence of a step between the metaphysis and physis at the fracture site. Fracture reduction was classified as. Grade 0= Anatomical reduction, grade 1= Minimal malreduction (<1 mm), grade 2= Moderate malreduction (1-3 mm), grade 3= Severe malreduction (>3 mm). Bone healing was assessed based on bone bridging or the disappearance of radiolucent areas in the fracture line, with healing judged as satisfactory or unsatisfactory by the surgeons. The growth plate was monitored for closure at each follow-up, with partially closed plates considered closed. Complications related to bone healing were recorded. Orthogonal radiographs from both the affected and contralateral limbs were used to measure bone length differences. Measurements were made with standardized positioning and a 10 cm calibration mark for accuracy (Boekhout-Ta et al., 2017).

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Statistical analysis
 
Statistical analyses were performed using SPSS 22.1. Mean and standard deviation were calculated for continuous variables (e.g., age, clinical and laboratory results) and frequency and percentage values for categorical variables (e.g., fracture type and sex). The chi-square test assessed the relationship between fracture type and complications. The Independent T-Test was used to examine the relationship between fracture type and severity of postoperative lameness. One-way ANOVA evaluated postoperative radiographic findings and fracture healing. Pearson Correlation Analysis assessed the relationship between postoperative complications and recovery time. The Intraclass Correlation Coefficient (ICC) determined the agreement between the surgeons’ radiographic evaluations. Statistical significance was set at p<0.05.

Study group
 
This study included 30 cats (30 femurs) with salter-harris type I (56.7%, 17/30) or type II (43.3%, 13/30) femur fractures. No cases of open reduction or fixation were excluded. The hematological, biochemical and blood gas values of all cats, including those with open fractures, were within the reference ranges (Table 1). The sex distribution was: neutered male (MC) 20% (6/30), neutered female (FN) 23.3% (7/30), non-neutered male (M) 40% (12/30) and non-neutered female (F) 16.7% (5/30). Breeds included domestic short-haired (DSH) 33.3% (10/30), Scottish Fold 16.7% (5/30), British Shorthair 16.7% (5/30), Van Cat 13.3% (4/30), Siamese 16.7% (5/30) and Angora 3.3% (1/30). The mean age at surgery was 8.1±2.2 months (range 4-11 months), with a mean weight of 4.5±0.5 kg. Most fractures (73.3% [22/30]) were caused by falls from height, while the cause remained unknown in 26.7% (8/30). The average perioperative fracture duration was 2.4±1.3 days. Two open fractures were noted in 6.7% (2/30): Case 23 (British shorthair, 11 months, salter-harris type II) and case 27 (scottish fold, 10 months, salter-harris type II).


 
Preoperative radiographic assessment
 
Inter-surgeon agreement in the preoperative radiographic assessment was high (ICC=0.89 (89%), p=0.002). In the preoperative fracture displacement evaluation, degree 3:70.0% (21/30) of these cases were cats falling from a height. In other cats, Degree 2:20.0% (6/30) were Degree 1:10.0% (3/30).
 
Surgical findings
 
In this study, two 10 cm long cerclage wires (1.25 mm in 70% [21/30] and 1.5 mm in 30% [9/30]) were safely used in all cases. Intraoperatively, except in cases with fracture displacement degree 1, the holes in both the proximal and distal fragments were pre-drilled before starting the fracture reduction. This method was considered more practical in cases with degrees 2 and 3. The average operative time was 37±5 minutes, excluding anesthesia time. No intraoperative complications were observed.
 
Postoperative radiographic and outcome evaluation
 
The total follow-up period averaged 16.8±5.1 months, ranging from 10 to 26 months. All 30 cats were evaluated clinically and radiographically. Inter-surgeon agreement on radiographic evaluation was high (ICC = 0.91, 91%, p = 0.011). Bone healing was observed in 83.3% (25/30) of cases by 6 weeks postoperatively and in 16.7% (5/30) by 8 weeks (Fig 3 A-G, Fig 4 A-F). Growth plates were visible in 16.7% (5/30) of the femurs, with open growth plates noted in all patients younger than five months preoperatively. Postoperative fracture displacement was classified as degree 0 in 13 cases, degree 1 in 10 cases, degree 2 in 5 cases and degree 3 in 2 cases. No significant difference in bone healing was found with respect to fracture type (p = 0.11). Anatomical or minimal malreduction occurred in 85% of cases (Fig 5 A-D).

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Lameness, assessed after removal of the Robert Jones bandage in the second postoperative week, showed a mean score of 0.11±0.07 for type I fractures and 0.21±0.03 for type II fractures, with no significant difference (p = 0.43). Shortening of the affected bones was observed in 90% (27/30) of neutered male and female cats (Fig 6 A-D). Bone elongation occurred in only 10% (3/30), but this was not clinically or radiographically significant (p = 0.068).

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In terms of complications, 73.3% (22/30) of cases had no complications. Mild edema was observed in 23.3% (7/30), resolving with two weeks of rest. One case (3.3%, 1/30) experienced mild infection, which resolved with local povidone iodine treatment. No significant correlation was found between fracture type and postoperative complications (p = 0.15), but a significant positive correlation was found between postoperative complications and recovery time (r = 0.62, p = 0.022).
       
Owner and veterinarian satisfaction was high, with all participants reporting full functional recovery. Mid-term follow-up (6-12 months) showed a full function rate of 83.3% (25/30), with mild limping in 16.7% (5/30). Long-term follow-up (>1 year) revealed that 96.6% (28/29) had full function, with only one case (3.4%, 1/29) showing acceptable intermittent limping. Case 6, which was adopted by another owner, was excluded from the long-term evaluation but was reported to have no complications.
       
Salter-Harris type I and II fractures in cats are critical due to their involvement with growth plates, affecting bone development (Rubinos et al., 2021; Bondonny et al., 2023). While traditional methods like cross-pinning and intramedullary fixation are common (Cağatay et al., 2013; Boekhout-Ta et al., 2017), the figure-of-eight cerclage wire technique offers a practical, minimally invasive alternative. This study shows a 96.6% functional recovery rate, comparable to or exceeding conventional methods (Cebeci et al., 2021; Spångberg et al., 2019; Bondonny et al., 2023). The technique’s simplicity, shorter operative time and stability against shear forces make it particularly advantageous for cases involving muscular traction and chronic fractures. These results align with prior research emphasizing the biomechanical benefits of tension band principles in managing physeal fractures (Spångberg et al., 2019; Altuğ et al., 2019), supporting its viability as a primary treatment option for Salter-Harris I/II fractures in feline patients.
       
Femoral physeal fractures in cats predominantly involve salter-harris types I and II, with a male predisposition (73.3% in this cohort) linked to behavioral traits that increase trauma risk (Cağatay et al., 2013; Gill et al., 2018; Haq et al., 2024). Falls from heights are the primary cause (Brioschi et al., 2016), which aligns with this study’s population treated using the figure-of-eight cerclage wire. This technique showed similar efficacy for both salter-harris I and II fractures, with comparable healing times (median: 6.2 weeks) and complication rates (23.3%), supporting its biomechanical suitability for uniplanar fractures under shear forces (Rubinos et al., 2021). The prevalence of salter-harris I/II fractures likely results from physeal vulnerability to bending stresses rather than gender-specific biological factors.
       
Conventional techniques for Salter-Harris I/II femoral fractures in cats, such as cross-pinning and intramedullary fixation, offer favorable outcomes (93% success) but come with risks like pin migration, articular damage and joint pathology if not placed correctly (Cağatay et al., 2013; Bondonny et al., 2023). While cross-pinning is biomechanically robust against rotation, it requires precise placement to avoid complications (McNicholas et al., 2002). Intramedullary fixation, though less invasive, lacks rotational stability and can damage cartilage in comminuted fractures (Cebeci et al., 2021). In contrast, the figure-of-eight cerclage wire technique, utilized in this study, offers superior adaptability, using tension band principles to counter muscular forces and allowing gradual reduction, especially beneficial for chronic cases. This technique optimizes compression and stability (Spångberg et al., 2019) and smaller-diameter wires (1.25-1.5 mm) proved effective in younger cats (6-11 months), suggesting age- and weight-based customization improves safety). Unlike pinning methods, cerclage wires minimize cartilage trauma and procedural complexity, while achieving high functional recovery rates (96.6%), positioning the technique as a reliable alternative where traditional methods may be limited.
       
Postoperative bandaging, though common, can cause skin lesions and morbidity, especially with prolonged use (Miraldo et al., 2020). This study advocates for a shorter 2-week immobilization period, which aligns with Cebeci et al., (2021), showing no adverse effects. Extended bandaging (>3 weeks) can worsen conditions like coccyfemoral luxation (Altuğ et al., 2019). The 2-week protocol effectively balanced fracture stabilization and soft-tissue protection, highlighting the importance of monitoring bandage duration based on fracture stability and patient needs (Miraldo et al., 2020; Valk et al., 2020).
       
Traditional methods like cross-pinning and intramedullary fixation for salter-harris fractures carry risks such as pin migration, infection and osteoarthritis (Cağatay et al., 2013; Bondonny et al., 2023). In contrast, the figure-of-eight cerclage wire technique in this study showed only minor complications lameness (23.3%) and mild infection (3.3%) which resolved with conservative management. Abaxial wire placement effectively prevented patellar irritation, enhancing safety. These findings support the technique’s reliability and lower morbidity compared to conventional approaches, consistent with previous research (Spångberg et al., 2019; Cebeci et al., 2021).
       
Early growth plate closure and limb shortening are common after physeal fractures, but their clinical impact in cats is minimal. In this study, early closure occurred in 90% of cases without affecting long-term function, consistent with previous findings (Spångberg et al., 2019; Rubinos et al., 2021). Younger cats (<5 months) showed delayed closure, supporting age-related physeal resilience (Bondonny et al., 2023). Despite frequent limb shortening, mobility remained excellent, suggesting that early closure does not compromise functional outcomes. Further research is needed on age-specific physeal healing.
       
Preoperative fracture displacement significantly influences treatment strategies in physeal fractures. This study found that 70% of cases required open reduction due to severe displacement, aligning with previous veterinary and human studies (Gill et al., 2018; Boekhout-Ta et al., 2017). The figure-of-eight cerclage wire technique provided anatomical or near-anatomical alignment in most cases (76.7%), demonstrating its effectiveness in complex fractures. Compared to fluoroscopy-assisted methods, it offered a practical alternative with shorter anesthesia time (Boekhout-Ta et al., 2017), supported by high inter-surgeon agreement in postoperative evaluations.
               
Although long-term follow-up of physeal fracture management is limited in veterinary literature, the figure-of-eight cerclage technique in this study demonstrated excellent short-term radiographic healing (6-8 weeks) and a 96.6% rate of long-term functional recovery. These outcomes are comparable to those reported for cross-pinning and intramedullary fixation methods (Bondonny et al., 2023; Spångberg et al., 2019). Mild lameness observed in 16.7% of cases at intermediate follow-up largely resolved by the long term, with only 3.4% showing intermittent limping. The larger cohort and extended follow-up enhance the reliability of these findings, although telephone-based assessments may introduce bias. Overall, the results underscore the efficacy of the cerclage wire technique and the need for standardized, objective protocols for long-term functional evaluation.

To conclude, the figure-of-eight cerclage technique may be used as an alternative treatment modality to conventional applications in Salter-Harris type I and II fractures of the distal femoral physis commonly encountered in cats. Findings based on a larger number of cases (30 cats), preoperative and postoperative radiographic evaluations and long-term functional results confirmed the safety of this technique.

Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the Harran University of Animal Care Committee. (session and permit number: 2023-008/07).

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.