Abstract
Background:
Hindfoot fusion is commonly performed to relieve pain in patients with end-stage ankle and hindfoot arthritis. However, its impact on specific aspects of health-related quality of life (HrQoL) and the trajectory of improvement is not well established. This study aimed to evaluate the effect of hindfoot fusion on HrQoL at both short- and mid-term follow-up.
Methods:
A retrospective review was conducted on a prospective database of patients who underwent hindfoot fusion for severe pain, including ankle, subtalar, and tibiotalocalcaneal arthrodeses. Clinical outcomes were assessed using the visual analog scale (VAS) for pain and the 36-Item Short Form Health Survey (SF-36) scores for HrQoL: Physical Functioning (SFPF), Role Physical (SFRP), Bodily Pain (SFBP), General Health (SFGH), Vitality (SFVI), Social Functioning (SFSF), Role Emotional (SFRE), and Mental Health (SFMH). Patient satisfaction was assessed using a Likert scale. Scores were recorded preoperatively, 6 months postoperatively, and 2 years postoperatively. Although optimal deformity correction was desired, alleviation of pain was the main goal and deformity angles were not analysed in this study.
Results:
At 6 months, ankle fusion patients reported significant improvements in SFPF (+21.00, P < .001), SFRP (+23.33, P < .020), SFBP (+30.73, P < .001) and SFSF (+20.38, P = .022) whereas tibiotalocalcaneal patients reported improvements from baseline SFPF (+28.18, P < .001), SFRP (+43.18, P < .001), SFBP (+42.32, P < .001), and SFSF (+35.25, P < .001). Subtalar fusion patients recorded improvements in SFBP (+17.09, P = .014). All 3 fusion groups demonstrated sustained improvements in HrQoL at 2 years postoperatively. VAS scores reduced by 3.8-5.9 points across all fusion groups. Patient satisfaction was high at both 6 months and 2 years postoperatively.
Conclusion:
Hindfoot fusion was associated with significant gains in functional and pain-specific patient-reported outcomes. Improvements were mainly observed within the first 6 months for ankle and tibiotalocalcaneal fusion, with subtalar fusion demonstrating a slower but comparable trajectory of recovery. High patient satisfaction was reported across all groups at 2 years.
Level of Evidence:
Level III, retrospective cohort study.
Introduction
Hindfoot fusion is commonly performed to relieve pain and restore function in patients with severe ankle and hindfoot arthritis. 1 These conditions can lead to significant physical impairment and become detrimental to one’s quality of life. 2
Traditional surgical options comprise Ankle arthrodesis, Subtalar arthrodesis and Tibiotalocalcaneal arthrodesis. Although these procedures can alleviate pain and correct deformities, they are not without potential drawbacks. For example, ankle arthrodesis reduces ankle mobility, which could limit gait efficiency. 3 Meanwhile subtalar arthrodesis restricts the transverse tarsal joint, thereby impeding smooth progression from heel strike to stance phase. 2 Other possible complications include malunion, non-union, infection, and malalignment. 4 Consequently, although hindfoot fusion might relieve pain, the overall quality of life might be paradoxically reduced.
In view of the potential benefits vs risks outcomes following hindfoot fusion, it is crucial that quality of life be analysed. Other studies have adopted patient-reported measures such as the 36-Item Short Form Health Survey (SF-36) collectively and visual analog scale (VAS) scores for post-operative outcome assessment. 2 However, few studies have analysed the impact of hindfoot fusion on specific aspects of health-related quality of life alongside clinician-reported measures, or reported the trajectory of improvement following surgery.
This study thus aims to evaluate the effect of hindfoot arthrodesis on health-related quality of life (HrQoL) and clinical outcomes at both early and mid-term follow-up.
Methods
This study was approved by our institutional review board (CIRB 2023/2551). A retrospective review of prospectively collected database data was conducted on 75 patients who underwent hindfoot fusion at a single tertiary hospital between January 2004 and December 2024. The inclusion criteria were (1) a diagnosis of end-stage hindfoot or ankle arthritis; (2) having underwent ankle, subtalar, or tibiotalocalcaneal fusion; and (3) availability of preoperative, 6-month, and 2-year postoperative SF-36 and VAS scores. Patients with incomplete data or revision surgeries were excluded. There was a 17.5% loss to follow-up from the original 91 patients.
Surgical techniques were categorised into 3 main groups for comparison: ankle fusion (AF), subtalar fusion (ST), and tibiotalocalcaneal (TTC) fusion. AF fusions used screws whereas TTC fusions used intramedullary nails. Primary outcome measures focused on the 8 SF-36 subdomains: Physical Functioning (SFPF), Role Physical (SFRP), Bodily Pain (SFBP), General Health (SFGH), Vitality (SFVI), Social Functioning (SFSF), Role Emotional (SFRE) and Mental Health (SFMH). SF-36 is a widely validated and predominantly patient-based measurement of objective and subjective outcomes post-surgery. It utilises 36 questions, and the results are usually split into higher order summary scores: physical and mental components. For this study, the individual aspects of SF-36 were analysed separately so as to identify specific areas of improvement relevant to functional recovery and perception of physical well-being. 5 VAS scores were used to assess pain intensity. VAS is a continuous linear scale that ranges from 0 to 10 (no pain to worst pain), aiming to identify pain intensity. 6
Satisfaction rates were assessed using a Likert scale, with scores ranging from 1 to 6: 1 = excellent, 2 = very good, 3 = good, 4 = fair, 5 = poor, 6 = terrible. The individuals scoring 1 to 3 were categorised as satisfied whereas those scoring 4 to 6 were categorised as unsatisfied.
Statistical Analysis
Statistical analysis was performed with SPSS 20.0 (IBM Corp).
Simple descriptive analysis was performed for the demographic population. Paired t tests were then performed for each of the 3 fusion groups comparing individual preoperative SF-36 domains against 6-month and 2-year postoperative SF-36 outcomes (Tables 2-4). Similarly, paired t tests were performed to assess for statistically significant changes in mean VAS hindfoot scores between preoperative, 6-month postoperative, and 2-year postoperative (Tables 2-4). Simple descriptive analysis was added to assess how satisfaction rates changed at the different time periods (Supplemental Table 1).
Independent t tests via pairwise comparisons were performed at 6 months, comparing mean SF-36 domain and VAS scores between all 3 fusion types (Supplemental Table 2). Outcomes at 2 years were not compared because of initial outcomes being overwhelmingly statistically insignificant. In view of the multiple outcomes and risk of false positives, a covariate-adjusted multivariate analysis of variance was performed (Supplemental Table 3). With fusion type as the primary independent variable, all 8 SF-36 domains were analysed as a single dependent variable at 6 months and 2 years while accounting for age, body mass index (BMI), and diabetes mellitus status as potential confounders.
Results were presented as mean differences with corresponding P values and 95% CIs, with P value <.05 being considered statistically significant.
Results
Preoperative patient demographics are shown in Table 1. The mean age of the study subjects was 60 years, whereas the mean BMI was 27.83. There was a near equal ratio of male-female patients. In addition, 6.7% of patients were smokers and 24% had type 2 diabetes mellitus. Further, 27 patients underwent AF, 23 underwent ST, and 25 underwent TTC.
Preoperative Characteristics of the Cohort (N = 75). a
Abbreviation: BMI, body mass index.
Unless otherwise noted, values are n (%).
On the whole, AF and TTC groups had the greatest improvements in SF-36 (Tables 2 and 3). Six months postoperatively, AF patients reported significant improvements from baseline SFPF (+21.00, P < .001), SFRP (+23.33, P = .020), SFBP (+30.73, P < .001), and SFSF (+20.38, P = .022). Similarly, TTC patients reported significant improvements from baseline SFPF (+28.18, P < .001), SFRP (+43.18, P < .001), SFBP (+42.32, P < .001), and SFSF (+35.25, P < .001). Comparing 2 years postoperatively to the 6-month data, both AF and TTC patients reported sustained improvements in SFPF, SFRP, SFBP, and SFSF. ST patients, on the other hand, only showed significant improvement in baseline SFBP at 6 months (+17.09, P = .014) and at 2 years, SFRP (+24.99 from baseline, P = .036), and SFSF (+18.48 from baseline, P = .021) (Table 4).
Clinical Outcomes of Ankle Fusion (AF) (n = 27).
Abbreviations: SFBP, Bodily Pain; SFGH, General Health; SFMH, Mental Health; SFPF, Physical Functioning; SFRE, Role Emotional; SFRP, Role Physical; SFSF, Social Functioning; SFVI, Vitality; VAS, visual analog scale.
Boldface indicates statistical significance (P < .05).
Clinical Outcomes of Tibiotalocalcaneal Fusion (n = 25).
Abbreviations: SFBP, Bodily Pain; SFGH, General Health; SFMH, Mental Health; SFPF, Physical Functioning; SFRE, Role Emotional; SFRP, Role Physical; SFSF, Social Functioning; SFVI, Vitality; VAS, visual analog scale.
Boldface indicates statistical significance (P < .05).
Clinical Outcomes of Subtalar Fusion (n = 23).
Abbreviations: SFBP, Bodily Pain; SFGH, General Health; SFMH, Mental Health; SFPF, Physical Functioning; SFRE, Role Emotional; SFRP, Role Physical; SFSF, Social Functioning; SFVI, Vitality; VAS, visual analog scale.
Boldface indicates statistical significance (P < .05).
In all 3 fusion groups, VAS Hindfoot showed significant improvement (all P < .001; Table 4). For AF, VAS improved from 7.50 preoperatively to 2.04 at 6 months (P < .001) and 1.29 at 2 years (P < .001). For ST patients, VAS decreased from 5.96 to 2.13 (P < .001) and 2.35 (P < .001) over the same aforementioned time period. Likewise, TTC patients showed consistent improvement from the preoperative period until 2 years postoperatively, with VAS decreasing from 7.24 to 1.38 (P < .001) then 1.05 (P < .001).
When performing pairwise comparisons between AF, ST, and TTC fusion groups at the 6-month postoperative mark, there were no significant differences (P value > .05) (Supplemental Table 2). Similar statistical insignificance was noted for VAS scores. Furthermore, covariate-adjusted multivariate analysis of variance failed to demonstrate any statistically significant difference in SF-36 domains between fusion types at both 6 months (P = .544) and 2 years (P = .536) (Supplemental Table 3). However, age (P = .044) and diabetes (P = .016) were noted to be independently significantly associated with SF-36 outcomes at 6 months, whereas BMI (P = .029) had similar significant association at 2 years. This reflects that patient-related factors might have a greater influence on outcomes than fusion type.
At 6 months, AF demonstrated a satisfaction rate of 86.96%, ST had 65.0%, and TTC had 90.48%. ST had further improvement in satisfaction rates to 77.8% at 2 years, whereas AF and TTC satisfaction maintained. Although TTC patients appeared to have the greatest satisfaction, χ2 analysis results between the 3 fusion groups were not statistically significant at 6 months and 2 years (Supplemental Table 1).
Although the main objective of fusion was to relieve pain, concurrent analysis of hindfoot malalignment revealed significant improvements in AF (−2.86°, P = .013) and TTC (−8.61°, P < .001) groups (Supplemental Table 4).
Discussions
Hindfoot fusion was associated with significant pain relief and improved physical function in severe ankle and/or subtalar arthritis, as evidenced by improvements in multiple SF-36 physical component scores (PCS) (SFPF, SFRP, SFBP, and SFSF) and VAS hindfoot scores across all 3 fusion groups (Tables 2-4) with sustained satisfaction rates through the 2-year observation period postoperatively. Most of the improvement in scores was experienced by the 6-month mark, with continued improvement up to 2 years postoperatively for certain domains.
Improvements in mean SF-36 PCS and VAS scores are in keeping with wider studies related to hindfoot fusion that observe improvements in pain and physical function. 7 When comparing outcomes of fusion groups, Ajis et al 8 demonstrated that there was no statistically significant difference in satisfaction rates between TTC and TT/ST fusion groups. This falls in line with our own results (Supplemental Table 1). Ajis et al concluded that although TTC fusion patients have greater restrictions in mobility postoperatively, TTC patients were counseled heavily on the expected ankle stiffness and activity limitations preoperatively, resulting in equivalent satisfaction rates as AF and ST patients, despite worse functional outcomes (Tables 2-4). Furthermore, TTC patients had lower baseline SF-36 scores, as seen from Tables 2 to 4, possibly correlating with reduced expectations postoperatively and greater satisfaction consequently, thereby achieving similar satisfaction rates as AF and ST fusion groups.
Interestingly, when analysing SF-36, ST patients demonstrated significant improvements only in SFBP and SFRP without any improvements in SF-36 mental component scores (MCS) (SFGH, SFVI, SFRE, and SFMH). The most common causes of subtalar arthritis is trauma, which is frequently associated with additional injuries to the midfoot or ankle joint. The trauma could have created a psychological barrier with reduced confidence in recovery, thereby leading to insignificant changes in the SF-36 mental components. 9 Regarding SFRP, significant improvement was only noted at the 2-year mark. It is possible that the 2-year follow-up period provided patients with sufficient time to acclimatise with their hindfoot fusion.
It should be noted that postoperation, the normative data of SF-36 outcomes were reported to be similar to that of age-matched populations averaging 40-60 years in the Physical domains and 60-80 years in the Mental domains. 10 Post-fusion patients having similar SF-36 results as age-matched populations could be due to SF-36 having generic measures of HrQoL compared with ankle/hindfoot-specific questionnaires. Nonetheless, this tells us that regaining function and reducing pain in the ankle are important aspects in regaining one’s quality of life. The generally low SF-36 outcomes could be attributed to older age, which is associated with an accumulation of chronic diseases that are progressive or recurrent. Sareen et al 11 demonstrated that the presence of chronic physical and/or psychiatric morbidity resulted in worse SF-36 outcomes, particularly in the SFRP, SFBP, SFRE, and SFSF. It is likely that such chronic morbidity led to a limit on the maximum SF-36 results any such individual could achieve despite hindfoot fusion.
SF-36 MCS has been commonly used to predict surgical outcomes for other surgeries, for example, hip and knee arthroplasty, with significant improvements. 12 However, our study showed largely insignificant improvements in SF-36 MCS. This indicates that although surgery might have successfully alleviated pain-related and mechanical deficits, there might be other unmeasured concomitant factors that influence one’s perception of health and energy that have not been addressed, such as chronic diseases or psychosocial stressors. For example, the majority of end-stage ankle arthritis etiologies are post-traumatic, which predispose patients to post-traumatic depression, possibly influencing mental outcome scores.13,14 Additionally, other factors such as pain catastrophising and anxiety could have contributed. Incidentally, TTC patients did show significant improvements in SFSF and SFMH at 6 months postoperatively (Table 4), which could be due to TTC arthrodesis indications being broader than trauma such as Charcot arthropathy, neuromuscular disorders, or rheumatoid arthritis. 8 The reduced burden of trauma on TTC patients could have resulted in slightly better SF-36 MCS scores. Nonetheless, further research could investigate possible causes of insignificant changes in SF-36 MCS.
Covariate-adjusted multivariate analysis of variance accounted for age, BMI, and diabetes as potential confounders, revealing that fusion type is not an independent predictor of functional outcomes. 8 However, age and diabetes were independent predictors of SF-36 at 6 months, suggesting that early postoperative recovery might be associated with patient baseline health. 15 Meanwhile BMI was an independent predictor at 2 years, indicating that metabolic health might have greater influence on longer-term functional recovery. 16 These highlight the importance of optimisation of comorbidities rather than focusing on surgical construct alone, in achieving the best postoperative outcomes post hindfoot fusion.
Collectively, most of our patients were satisfied with the outcome of their surgery. Restoration of HrQoL to an age-matched normative data, as seen from our 2-year SF-36 mean values (Tables 2-4), could be a contributing factor for satisfaction in older patients debilitated by end-stage ankle degenerative disease.
Strengths and Limitations
Although our observations show promising improvements in a patient’s quality of life post ankle/hindfoot fusion, this study has its limitations. The retrospective nature of the study might introduce information bias, and its relatively small sample size could have limited the power of the study. Patients lost to follow-up could have had negligible improvements, thereby falsely elevating the general outcomes. Most patients were also older and likely to be less active; thus, the results may not be generalisable to younger patients undergoing similar procedures. Furthermore, our outcome measures focused solely on SF-36 and VAS, without inclusion of foot and ankle–specific outcome measures, potentially limiting the specificity of outcomes measured.
Notably, our study does not compare outcomes between different stages of ankle/hindfoot arthritis nor against other conditions like Charcot arthropathy or neuromuscular disorders. This could influence the final SF-36 results, and patient satisfaction as the main preoperative concern would vary between pain and function. However, end-stage ankle/hindfoot arthritis is the commonest indication for ankle/hindfoot fusion, making up to 70% of all fusions, hence the focus of our paper. 17 We acknowledge that further research could be done to look into comparisons between different pathologies.
The 2-year follow-up period allowed us to observe statistically significant trends that might not have achieved significance at an earlier observation period. Our thorough analysis of each individual SF-36 domain for each fusion group provides us with clear breakdown of how patients’ quality of life change post hindfoot fusion and can serve as the foundation for more expansive research as per the aforementioned limitations. Much of the existing literature analyse outcome data at a fixed time point postoperatively. This study goes beyond and demonstrates the trajectory of recovery following hindfoot fusion and sustainability of early improvements in HrQoL and clinical outcome scores. Longer-term studies will be useful to demonstrate at which point the clinical outcomes may begin to deteriorate from adjacent joint degeneration.
Conclusion
Hindfoot fusion for end-stage ankle/hindfoot arthritis was associated with significant gains in functional and pain-specific patient-reported outcomes, most notably in the ankle and tibiotalocalcaneal fusion groups. Most of the improvement was observed within the first 6 months, with gains sustained at 2 years; further, subtalar fusion demonstrated a more limited and delayed pattern of improvement. No statistically significant difference in outcomes between fusion types was detected, although the study was not powered to establish equivalence. Future studies should compare outcomes across different pathologic indications for hindfoot fusion.
Supplemental Material
sj-pdf-1-fao-10.1177_24730114261446315 – Supplemental material for Early and Mid-term Effects of Ankle and Hindfoot Arthrodesis on Quality of Life
Supplemental material, sj-pdf-1-fao-10.1177_24730114261446315 for Early and Mid-term Effects of Ankle and Hindfoot Arthrodesis on Quality of Life by Yen Chin Jeremy Tan, Jeremy Lim, Ramesh Radhakrishnan, Zongxian Li, Kizher Shajahan Mohamed Buhary, Rui Xiang Toh and Kae Sian Tay in Foot & Ankle Orthopaedics
Footnotes
Appendix
Hindfoot Malalignment Pre- and Post-fusion.
| Fusion Type | Preop. Malalignment (°), |
Postop. Malalignment (°), |
Δ (Pre → Post) | P Value (95% CI) |
|---|---|---|---|---|
| AF | 11.49 ± 8.56 | 8.63 ± 5.86 | −2.86 | .013 (−5.10 to −0.62) |
| ST | 3.46 ± 3.97 | 4.30 ± 4.67 | 0.84 | .244 (−0.61 to 2.29) |
| TTC | 20.39 ± 14.43 | 11.78 ± 7.36 | −8.61 | <.001 (−13.38 to −3.85) |
Abbreviations: AF, ankle fusion; ST, subtalar fusion; TTC, tibiotalocalcaneal fusion.
Ethical Considerations
Ethical approval for this study was obtained from Singapore Institutional Review Board (CIRB 2023/2551).
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.
References
Supplementary Material
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