1. Introduction
The talonavicular, talocalcaneal, and calcaneocuboid joints are fused together in the hindfoot. It is commonly used to treat patients who have pain, chronic instability, or gross deformity as a result of hindfoot pathology [1] [2] . Severe post-traumatic conditions, osteoarthritis (OA), neuromuscular disorders, extensive contractures, and longstanding posterior tibial tendon dysfunction are among the causes of this disease [3] [4] . The procedure appears to be effective in terms of pain relief and function improvement [2] .
Non-union is the most common complication of triple arthrodesis, with rates ranging from 0% to 40% in various studies. [1] Although some of these non-unions are asymptomatic, a significant number of them result in significant disability. Non-unions can be caused by early weight-bearing, insufficient bone apposition, and insufficient internal fixation [1] . Although most surgeons advocate internal fixation to maintain correction and reduce the incidence of non-union, there is no agreement on the best internal fixation technique [1] [3] . Furthermore, concerns remain about the long-term functional outcomes of a triple arthrodesis and whether a painless, plantigrade foot can be maintained indefinitely [5] .
In more than half of the cases, degenerative changes in the ankle and midfoot have been reported [6] [7] [8] . Patient satisfaction is an important outcome for determining the procedure’s effectiveness.
The Ankle-Hindfoot Score of the American Orthopedic Foot and Ankle Society (AOFAS) is one of the most commonly used instruments for assessing treatment outcomes in patients who have suffered a complex ankle or hindfoot injury. It combines a clinician-reported and a patient-reported component. According to Philip, V. et al. [9] , the outcome of bilateral AA is independent of the outcome of unilateral AA. They discovered that the Bilateral AA appears to provide patients with a good functional outcome, as well as high patient reported satisfaction in the medium term.
The purpose of this study was to evaluate the functional outcomes of patients who had undergone hindfoot fusion, as well as the complication rate and clinical outcomes.
2. Methodology
2.1. Study Design
This study is a prospective cohort study.
2.2. Study Area
It was conducted in Future Hospital, in Khartoum, Sudan.
2.3. Study Population and Sampling
The study involved adults’ patients who underwent surgical fusion of the ankle joint at future hospital during the period from July 2015-July 2022. It involved 30 patients A total coverage for all the cases was done. The missing report was excluded.
2.4. The Procedure
Patients with severe Charcot arthropathy of the ankle and correctable deformity were included. Optimization of the medical condition is secured before surgery with a multi-disciplinary team. Spinal anaesthesia was utilized except in two patients who asked for general anaesthesia. A tourniquet wasn’t used in this series. Closed reduction of the ankle deformity is performed under fluoroscopy. Short retrograde femur nails are used to fuse the ankle and subtalar joint and are introduced from the sole of the foot after adequate reaming. Two distal locking screws and another two proximal locking screws are applied after ensuring adequate compression of the distal tibia and the talus. Walker boot is applied 2 weeks after the procedure and used for three months. The progress of bone healing is followed regularly with serial X-rays. Partial weight bearing is allowed after six weeks and full weight bearing is considered at three to four months depending on the status of healing. The functional status of the ankle is assessed before surgery and one year after surgery. All surgeries were done by the primary researcher and his team.
2.5. Data Collection and Analysis
Data was collected by the primary researcher using data collection sheet, it includes the patients’ demographics, satisfaction, and AOFAS score.
American Orthopaedic Foot and Ankle Society Score (AOFAS) Each measure is comprised of nine questions and covers three categories: pain (40 points), function (50 points), and alignment (10 points). These give a total of 100 points. Data was cleaned and entered into a Microsoft Excel data sheet before being analysed with SPSS version 28 software.
2.6. Ethical Considerations
Ethical clearance and approval were obtained from MOF in Sudan and administration of Future Hospital.
2.7. Study Limitations
Small sample size and short follow-up period.
3. Results
This study has involved 30 patients underwent hindfoot fusion at Future Hospital from July 2015-July 2022 to determine the functional outcome, surgical complications and patients’ satisfaction. One third of patients (33.3%) are between 51 - 60 years, and another third are more than 60 years of age, 23.3% are between 40 - 50 years, and only 10% are less than 40 years of age. Male: Female ratio equals 1:1. The left side is affected in 56.7% of candidates and the right side is involved in the remaining 43.3%. Only 23.3% developed complications and only three patients required further surgeries. Wound infection is encountered in one patient, non-union in 4 patients and wound dehiscence in 2 patients (Table 1). Most of the patients are fully satisfied (63.3%) from the procedure, (13.3%) fair satisfaction, and (23.4%) are unsatisfied (Figure 1). The mean AOFAS score was found to be 42.06 ± 3.21 before, and 74.93 ± 9.07 after the operation. The p-value is <0.05 which considered a significant correlation (Table 2). A significant correlation between the means of AOFAS score with the complications and the satisfaction of the patients. There are non-significant correlations with the age group, gender, and the side (Table 3).
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Figure 1. The satisfaction of the patients underwent hindfoot fusion in Future Hospital. (n = 30).
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Table 1. Demographic characteristics and presence of complications of patients underwent hindfoot fusion in Future Hospital (n = 30).
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Table 2. The correlation between the AOFAS score before and after the operation among patients underwent hindfoot fusion in Future Hospital (n = 30).
*Significant correlation.
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Table 3. The correlation between the AOFAS score POST with the Age, gender, side, complications and satisfaction among patients underwent hindfoot fusion in Future hospital (n = 30).
*Significant correlation.
4. Discussion
Charcot neuroarthropathy presents an enormous challenge for limb salvage in diabetic neuropathic patients. The risk of ulceration and progression of infection is increased in patients in whom the ankle is involved. The instability of the joint that characterizes the initial phase of the disease progressively worsens with weight-bearing forces on an insensate foot. Stabilization by fusion is the best approach with a low risk of complications and allows the patient to walk again. Open ankle fusion is yet the standard procedure but the post-operative wound complication represents a real challenge. The purpose of this study was to look into functional outcomes and patient satisfaction with percutaneous fusion of the ankle with the hindfoot nail. The majority of patients who underwent percutaneous hindfoot fusion are over 50 years old, with a male-to-female ratio of 1:1. The rate of complications is approximately 23.3%, which is significantly lower than that found in open fusion like in the study of Philip V et al. and N. Vasukutty et al. (28%) [9] [10] and also in the study of Chou et al. (25.5%). Chou et al. also found that in 63.3% of candidates were satisfied in comparison 76.6% in this study [11] . Significant statistical association is found between the post-operative AOFAS scale and the satisfaction, which is similar to the finding of Pell et al. [2] . Strong correlation is found between the AOFAS score before and after the procedure indicating significant improvement in the function of the ankle. Before the procedure, the mean AOFAS score was 42.06 ± 3.21, and it has changed to 74.93 ± 9.07 one year after the procedure. In the series of Hani El-Mowafi, et al. [12] the AOFAS scale has improved significantly from 34.6 ± 6.8 to 66.4 ± 4.5 at the last follow-up. K. Mader et al. elaborated that retrograde locked nailing is a reliable minimally invasive procedure to achieve fusion of the ankle and the subtalar joint after failed fusion. They found an average AOFAS of 73.5 points (range, 61 - 81 points) after surgery [13] .
5. Conclusion
Minimally invasive tibio-talo-calcaneal arthrodesis is an alternative surgical technique for severe Charcot arthropathy of the ankle with correctable deformity. The functional outcome is impressive and comparable with the open surgery. However, the post-operative complications are anticipated in less than one fourth of patients. The patient’s satisfaction with the procedure is high.
Acknowledgements
First and foremost, we thank Allah for lighting our path and allowing us to finish this work.
We are grateful to our colleagues who contributed to bringing this work to light.
We are grateful to our families for devoting themselves at this time to provide various forms of assistance.
Thank you very much.
Ethics Approval and Consent to Participate
We declare that we have:
Written permission was obtained from the administrative authority of Future Hospital.
Confidentiality was considered intentionally, data was used anonymously by using code Numbers instead of names to participants’ identities and keep secure, and information was used for research purposes only.
Authors’ Contributions
S.N: Orthopaedics surgeon, conceptualization, methodology, resources, project administration, and writing original draft.
M.H: Orthopedic resident, conceptualization, data collection, methodology, and assisting in writing original draft.
A.K: Orthopedic resident, conceptualization, assist in data collection, and writing original draft.
H.A: Orthopedic surgeon, data curation, resources, validation, review and editing.
M.F: Orthopedic surgeon, resources, visualization, validation, and assisting in analysis & editing.
O.G: House officer, data curation, formal analysis, software, and assisting in writing original draft.
The manuscript has been read and approved by all the authors.
Appendix
Minimally Invasive Hind-Foot Fusion in Charcot Patients Questionnaire
Serial No.: 
PR Number: 
1. Age (Years): 
2. Gender:
Male 
Female 
3. The Side of Operation:
Right 
Left 
Bilateral 
4. Complication:
Infection 
Non-Union 
Wound Dehiscence 
5. Satisfaction
Fair 
Full 
Unsatisfied 