Analysis of risk factors for failure of arthroscopic ankle fusion in a series of 52 ankles

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FAS-833; No. of Pages 6 Foot and Ankle Surgery xxx (2015) xxx–xxx

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Analysis of risk factors for failure of arthroscopic ankle fusion in a series of 52 ankles Sumit Kumar Jain MBBS, MS (Ortho), MCh*, David Tiernan MB, BAO, BCh, Stephen R. Kearns MD, FRCS (Trauma and Orthopaedics) Galway University Hospitals, Galway, Ireland

A R T I C L E I N F O

A B S T R A C T

Article history: Received 18 February 2015 Received in revised form 5 May 2015 Accepted 11 May 2015

Background: The purpose of this retrospective study is to analyze the effect of different variables on union rate and functional outcome in patients who underwent arthroscopic ankle fusion for end-stage arthritis of ankle. Methods: Clinical records and radiographs were reviewed to evaluate the variables that could predispose patients to non-union and poor functional outcome. Union and functional outcomes were correlated with different variables. Results: Fifty patients had arthroscopic ankle fusion on 52 ankles. The mean age at the time of surgery was 59.4 (27–80) years and mean length of follow up was 32.1 (8–78) months. Forty-eight out of 52 ankles (92.3%) achieved radiographic and clinical union. The average time to fusion was 12.2 (8–28) weeks. The time taken for union was significantly higher in smokers as compared to non-smokers (p < 0.001). All the patients in this series who had non-union shared one common factor – neuromuscular imbalance. Age, gender, smoking, diabetes, steroid, bisphosphonates, neuropathy, frontal and sagittal plane alignment and tibial-axis-to-talus (T:T) ratio did not significantly affect the union rate and functional outcome. Conclusion: Smokers should refrain from smoking before surgery and patients with neuromuscular problems may require more rigid fixation and a longer period of immobilization to achieve more consistent union rates. ß 2015 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

Keywords: Arthroscopic technique Ankle joint Arthrodesis

1. Introduction The formal goal of an ankle fusion is to achieve painless, plantigrade foot of the degenerated ankle joint [1]. Since Edward Albert’s first description of ankle arthrodesis in 1879 [2], more than 40 techniques of performing arthrodesis have been described in literature. Although most open techniques have achieved a high fusion rate, they have however been associated with complications including infection, wound-healing problems, fracture, neurovascular injury, mal-union and non-union [1,3,4]. The high complication rates of open ankle fusion resulted in the development of less invasive techniques [4]. Arthroscopic ankle fusion, introduced by Schneider in 1983 [5], became popular over open techniques due to its faster time to union, lower morbidity; lower blood loss; faster rehabilitation and shorter hospital stay [6–8]. The literature reported a mean time to union of 12 (6–40) weeks [8–10], with a

union rate ranging from 85% to 97% [8–13]. High fusion rates following arthroscopic ankle fusion are probably because periosteal stripping is not necessary, and the local circulation remains intact, creating a more favourable environment for fusion to occur. This has allowed the indications for ankle fusion to be extended to patients with both poor skin and impaired wound healing potential [13]. There are several studies showing the good outcome of arthroscopic ankle fusion but only few studies have investigated causes of poor functional outcome and non-union [12,18]. We hypothesized that there were identifiable patient and surgical factors that could predict an increased rate of non-union and poor functional outcome in patients undergoing arthroscopic ankle fusion. The aim of this retrospective study is to analyze the clinical and radiographic factors associated with non-union and poor functional outcome in patients undergoing arthroscopic ankle fusion for arthritis of ankle. 2. Materials and methods

* Corresponding author. Tel.: +91 8447863876. E-mail addresses: [email protected] (S.K. Jain), [email protected] (D. Tiernan), [email protected] (S.R. Kearns).

All consecutive patients with end stage arthritis of ankle due to any cause and with any degree of deformity, who underwent

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Please cite this article in press as: Jain SK, et al. Analysis of risk factors for failure of arthroscopic ankle fusion in a series of 52 ankles. Foot Ankle Surg (2015), http://dx.doi.org/10.1016/j.fas.2015.05.007

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arthroscopic ankle fusion from June 2007 to February 2013, were included in this series. Patient’s charts were reviewed and the data collected included; age, gender, height, weight, smoking history, history of diabetes mellitus, use of steroids, use of bisphosphonates, peripheral neuropathy, aetiology of arthritis, frontal plane alignment, sagittal plane alignment, tibial-axis-to-talus (T:T) ratio, time taken for clinical and radiographic union, follow up time, final outcome and complications. There were 57 patients who underwent arthroscopic ankle fusions on 59 ankles. All the patients were operated by single surgeon with standardized surgical technique. Two patients died during follow-up due to other illness and 5 patients were lost during the follow-up. The remaining 50 patients had arthroscopic ankle fusion on 52 ankles (48 unilateral and 2 bilateral). There were 39 male and 11 female. Twenty-eight patients were less than or equal to 60 years of age whereas 22 were above 60 years with mean age of 59.4 (27–80) years. The body mass index (BMI) of 17 patients was more than 30 kg/m2 and 33 patients had BMI less than or equal to 30 kg/m2. The mean body mass index (BMI) was 29.1 (21.8–43.6) kg/m2. Five patients were smokers who continued to smoke after surgery, 5 patients were on treatment for type-II diabetes mellitus and only one patient had neuropathy due to diabetes mellitus, 2 patients were on bisphosphonates for the treatment of osteoporosis and two patients were on steroids for psoriasis. The aetiology of ankle arthritis was traumatic in 38 patients whereas in 12 patients (14 ankles) the aetiology was nontraumatic. Four patients (5 ankles) had idiopathic arthritis, two patients had psoriatic arthropathy, two patients had old healed osteomyelitis, one had gouty arthritis, one had arthritis due to long standing tibialis posterior dysfunction, one was lateral border walker due to central lesions and one patient (2 ankles) had arthritis due to long standing parkinsonism. The alignment in frontal plane was determined on anteroposterior radiograph of the ankle by measuring the superomedial angle (a), defined by the long axis of tibia (CD) against the line defining the trochlear surface of the talus (AB) [6] (Fig. 1). The angle is considered normal from 908 to 938 i.e. up to 38 valgus. The ‘sagittal alignment angle (b)’ was measured by drawing a line from the inferior aspect of the posterior tubercle of the talus to the most inferior aspect of the neck of talus (AB) and intersected with a line drawn along the anatomical axis of the tibia (CD) [14] (Fig. 2). The normal mean angle is considered to be 1068, with the ankle in neutral [6]. The antero-posterior tibio-talar alignment was quantified by measuring the tibial-axis-to-talus (T:T) ratio from the lateral preoperative and postoperative radiographs [15]. The intersection of the distal tibial axis (CD) with the talar reference line (AB) was defined as point D. The part of length AD to length AB represents tibial axis-to-talus ratio (AD/AB  100) (Fig. 3). The normal limit of tibial-axis-to-talus (T:T) ratio was considered as 27–42% [16].

Fig. 1. Antero-posterior radiograph of the ankle showing the measurement of frontal plane alignment. Supero-medial angle (a), formed by the line intersecting the long axis of tibia (CD) against the line defining the trochlear surface of the talus (AB), represents the frontal alignment angle.

2.2. Post-operative protocol At 2 weeks wound inspection was performed and a below knee non-weight bearing cast was applied for 4 weeks. After 6 weeks, patients were given air cast (CAM walker) boot and allowed

2.1. Operative technique A standard arthroscopic fusion technique was used and two parallel screws (partially threaded cancellous cannulated screws of 7.5 mm or 6.5 mm) were placed medially from the tibia into the talus percutaneously (Fig. 4). We aimed to place the screws parallel on both AP and lateral views where possible. Care was taken to avoid penetration of the subtalar joint which was checked by clinical examination and radiographic screening. A below-knee backslab was applied and patient was mobilized non-weight bearing for two weeks.

Fig. 2. Lateral radiograph of the ankle showing measurement of sagittal plane alignment. The ‘sagittal alignment angle (b)’ formed by intersecting the line drawn from the inferior aspect of the posterior tubercle of the talus to the most inferior aspect of the talar neck (AB) with a line drawn along the anatomical axis of the tibia (CD).

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eversion) and ankle-hindfoot stability (antero-posterior, varus– valgus). Criteria for union included a clinically stable ankle, painless on manipulation and weight bearing, with radiographic evidence of bridging trabeculae and/or callus without failure of internal fixation or change in position [17]. The functional outcome score was measured by American Academy of Orthopaedic Surgeons (AAOS) ‘‘Foot and ankle outcome Instrument (FAI)’’ core scale and American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale. The functional outcome score of less than 60 was rated as poor. Radiographs were reviewed for measurement of alignment, final outcome and time to union by senior author. Ankle fusion was confirmed by the presence of unequivocal trabeculation across the tibiotalar joint space, typically most apparent on the lateral ankle view. Serial radiographs were used to determine time to union. Whenever union was doubtful on radiographs, computerized tomographic (CT) examination was performed to confirm union. 2.3. Statistical analysis

Fig. 3. Lateral radiograph of the ankle showing measurement of tibial axis-to-talus (T:T) ratio. The intersection of the distal tibial axis (CD) with the talar reference line (AB) was defined as point D. The part of length AD to length AB represents tibial axis-to-talus (T:T) ratio (AD/AB  100).

progressive weight bearing until 12 weeks after the operation, or until clinical and radiographic union. Patients were followed up post-operatively in the Foot and Ankle clinic at intervals of 2 weeks, 6 weeks and 12 weeks and clinical and radiographic assessment was performed. Patients, who showed signs of clinical and radiographic union at 12 weeks, were followed up at 6 months and one year while those ankles which still did not show signs of satisfactory union, were followed up every 6 weeks until they have united or a decision to revise was made. All the patients were assessed and evaluated clinically and radiographically by the senior author during their postoperative visit in the clinic. The clinical examination included sagittal motion (plantar flexion, dorsiflexion), hindfoot motion (inversion,

Fig. 4. Antero-posterior and lateral views of the ankle (post-operative) showing the orientation of screw placement.

Statistical testing was conducted with the statistical package for the social science system (version SPSS 17.0). Continuous variables are presented as mean  SD, and categorical variables are presented as absolute numbers and percentage. Data analysis compared patients who achieved ankle union with those who did not and those with good functional outcome with poor functional outcome scores (AOFAS ankle hind-foot score and FAI core scale). Fisher’s exact test was used to determine if there were significant differences between the two categorical variables and Student t-test was used to determine significant difference between the two continuous variables with respect to age, gender, body mass index (BMI), influence of smoking, diabetes mellitus, steroid or bisphosphonates intake, peripheral neuropathy, aetiology of ankle arthritis, pre-operative and post-operative frontal and sagittal plane alignment and tibial-axis-to-talus (T:T) ratio on union rate and functional outcome scores. The level of significance was set at p < 0.05.

3. Results The mean length of follow-up was 32.1 (8–78) months. Arthroscopic ankle fusion produced union in 92.3% of the ankles (48 out of 52 ankles). Four ankles (3 patients) had non-unions which were revised. In non-union group, 2 ankles (one patient) had parkinsonism and pre-operative frontal plane alignment was more than 158 varus (298 and 308) which could not be entirely corrected by the procedure, one patient was lateral border walker due to central lesion and one patient had large lateral talar dome osteochondral defect with foot drop. The average time taken for clinical and radiographic union was 12.2 (8–28) weeks. There were two-delayed union, which took around 28 weeks to heal. One of them was previously operated pilon and talus fracture with talar dome defect and the other patient had an open ankle fracture 30 years before. Both of them were heavy smoker who continued to smoke even after surgery. The mean pre-operative frontal plane alignment shows that arthritis was mainly of varus type. The values of pre-operative and post-operative frontal plane alignment, sagittal plane alignment and tibial-axis-to-talus ratio are given in Table 1. The mean AOFAS ankle-hindfoot score was 74.5 (0–96) and mean FAI core scale was 77.7 (21–100). The two functional outcome score were compared by using Student t-test and no statistically significant difference was found between two scoring systems (p = 0.409). The results of subjective evaluation showed that 90% (45 patients with 46 ankles) of the patients were satisfied or

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Table 1 The values of pre-operative and post-operative frontal plane alignment, sagittal plane alignment and tibial-axis-to-talus ratio.

Pre-operative Mean  SD* Range Post-operative Mean  SD* Range *

Frontal plane alignment

Sagittal plane alignment

Tibial-axis-to-talus ratio

858  108 608–1058

1198  98 938–1408

29%  9% 12–50%

898  38 808–938

1118  58 1038–1258

29  7% 14–45%

p < 0.001 suggests that the difference in time taken for union in smokers and non-smokers was statistically significant. Analysis of age, gender, body mass index, influence of smoking, diabetes mellitus, steroid intake, bisphosphonate treatment, peripheral neuropathy, aetiology of arthritis, preoperative and post-operative alignments and tibial-axis-totalus (T:T) ratio was performed with union rate and functional outcome scores (AOFAS ankle hind-foot score and FAI core scale). p > 0.050 in each group and subgroup showed that above mentioned variables did not significantly alter the union rate and functional outcome scores (Tables 2 and 3). The complications other than non-union included subtalar arthritis (six), talo-navicular joint degeneration (two), long screw in subtalar joint (one) which was subsequently removed, tenderness at the site of proximal screw head (one) which was removed after union, severe complex regional pain syndrome (one), sloughing at distal screw incision site (one).

Mean + SD values are rounded off.

satisfied with reservation while 10% (5 patients with 6 ankles) of patients were not satisfied. The mean time taken for union in non-smokers was 11.45 (8–18) weeks whereas in smokers it was 19.0 (9–28) weeks.

Table 2 Analysis of different variable with union and functional outcome score. AOFAS ankle hindfoot score

Fusion

Age 60 years >60 years Gender Male Female BMI (kg/m2) 30 >30 Smoking Diabetes Bisphosphonate Steroid Neuropathy Aetiology Traumatic Non-traumatic

FAI core scale

Union (n)

Non-union (n)

p-value

<60

60

p-value

<60

60

p-value

27 20

1 2

NS

8 2

20 20

NS

7 1

21 21

NS

37 10

2 1

NS

9 1

30 10

NS

7 1

32 10

NS

32 15 5 4 2 2 1

1 2 0 1 0 0 0

NS

5 5 2 1 0 0 0

28 12 3 4 2 2 1

NS

5 3 1 1 0 0 0

28 14 4 4 2 2 1

NS

37 11

1 3

0.055

7 4

31 10

NS

7 2

31 12

NS

NS NS NS NS NS

NS NS NS NS NS

NS NS NS NS NS

‘‘NS, not significant (p > 0.05)’’. BMI; body mass index.

Table 3 Analysis of frontal and sagittal plane alignment and tibial-axis-to-talus ratio with union and functional outcome score. Fusion Union (n) Pre-operative frontal plane alignment 908  108 36 >908  108 12 Post-operative frontal plane alignment 908–938 34 >938 and <908 14 Pre-operative sagittal plane alignment 1068  58 3 >1068  58 45 Post-operative sagittal plane alignment 1068  58 26 >1068  58 22 Pre-operative Tibial-axis-to-talus ratio 27–42% 23 <27% and >42% 25 Post-operative Tibial-axis-to-talus ratio 27–42% 29 <27% and >42% 19

AOFAS Ankle-Hindfoot scale

FAI Core Scale

Non-union (n)

p-value

(n)

Mean  SD

p-value

(n)

Mean  SD

p-value

1 3

NS

37 15

75  20 73  23

NS

37 15

78  18 77  24

NS

1 3

NS

35 17

78  19 76  21

NS

35 17

78  19 76  21

NS

1 3

NS

4 48

76  27 74  21

NS

4 48

78  29 78  19

NS

2 2

NS

28 24

71  23 79  18

NS

28 24

75  21 80  17

NS

2 2

NS

25 27

70  23 78  19

NS

25 27

76  20 80  18

NS

2 2

NS

31 21

74  22 76  19

NS

31 21

80  18 74  21

NS

NS; not significant (p > 0.05).

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4. Discussion In this series of 50 consecutive patients, who underwent arthroscopic ankle fusion, the rate of clinical and radiographic union was comparable to the published data. Although Collman et al. [12] showed that higher body mass index affects the union rates; no such trend was seen in our study. The mean time taken for clinical and radiographic union in our series was comparable to the other published studies. Two patients in our series, who had delayed union were chronic smokers who continued to smoke even after surgery, which skewed the mean time taken for union somewhat. Cigarette smoking is known to affect bone healing by decreased tissue perfusion [19,20], alteration of cell metabolism [21,22], delayed healing of endothelia [23] and by decreasing the oxygen carrying capacity of haemoglobin [24]. Literature has also demonstrated an increased relative risk of ankle non-union in patients who smoke [3,25]. Although two patients in our series, who continued to smoke after surgery, had delayed union but none of the smokers went on to have non-union. It is possible that the disadvantages of smoking were countered by the minimally invasive approach. The mean time taken for union in non-smokers was significantly less as compared to smokers, which shows that there was a trend for delayed union in smokers. Various studies [26–28] have documented the negative effect of the steroids on bone healing in animal models. Abu et al. [29] have shown that the presence of glucocorticoid receptors GRa on osteoblasts and osteocytes retards the endochondral ossification resulting in poor bone healing. Two patients in our series were on steroids for psoriatic arthropathy and both of them achieved union. Although the number of patients on steroids was very small, no statistically significant effect of steroid intake was seen on the functional outcome scores and union rate in our series (p = 1.000). Systemic treatments that influence osteoclastic function such as, treatments of osteoporosis with bisphosphonates have been shown to adversely affect fracture healing [30]. Osteoclasts are active from the very early phases of bone healing and remain so over the entire course of bone healing [31]. Bisphosphonates act by suppressing osteoclastic activity and inducing apoptosis of the osteoclasts [32,33]. Two patients in this series were on bisphosphonates for the treatment of osteoporosis and both of them achieved union. The mean time taken for union in this group was 11.5 weeks. Although the number patients on bisphosphonates was very small, no significant effect of bisphosphonates treatment was seen on the functional outcome scores and union rate in our series (p = 1.000). The frontal plane alignment was corrected and brought to almost neutral in majority of the patients. The mean position of fusion in the sagittal plane, as seen on the lateral radiograph, was 58 of ankle plantar flexion; and majority of cases were within the range (Table 1). Anterior subluxation of the talus relative to the tibia, defined as a tibial-axis-to-talus (T:T) ratio was achieved within the ‘normal’ limit in 60% of the patients post-operatively. Although the mean correction of tibial-axis-to-talus (T:T) ratio was very small (Table 1), no statistically significant effect was seen on functional outcome scores and union rate (p > 0.05). All the patients in this series who had non-union shared one common factor – neuromuscular imbalance (parkinsonism, central lesion and foot drop). Persistent tremors due to neuromuscular imbalance may have produced abnormal forces and micro-motion around the fusion site resulting in non-union. It may also have reduced the patient’s ability to remain partial and non-weight bearing post-operatively, increasing motion at the fusion site. Six of our patients had subtalar arthritis and 2 had talonavicular joint degeneration of the ipsilateral foot. Long term

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studies following ankle arthrodesis for ankle arthritis [34] have shown that the increased stresses and functional demands placed on the adjacent joints of the ipsilateral foot, secondary to the fused ankle, may result in increased motion and abnormal chronic loading, ultimately leading to the development of osteoarthritis. It is quite possible that they have developed subtalar and talonavicular joint degeneration postoperatively due to increased stresses and functional demand placed on them or that it was not clinically relevant at the time of ankle fusion. As arthritis of the foot is known sequelae of arthrodesis of ankle, it is advisable that preoperative counselling about the potential development of arthritis in the foot should be done prior to ankle arthrodesis [35]. The analysis of risk factors was limited by a small patient population in this study. Since the probability of finding a statistically significant difference between groups was low, it is quite possible that the results only showed the trends among the groups. Statistically insignificant differences between the groups could be due to lack of power rather than lack of association. The significance of different variable on rates of ankle union and functional outcome could have been confirmed in a larger study population. Finally, the retrospective nature of this study depends on clinical chart review, operative reports, and analysis of radiographs.

5. Conclusion Arthroscopic ankle fusion is most widely used method of ankle fusion to relieve arthritic ankle pain with minimal complications, excellent union rates and reduced time for union. The variables like age, gender, BMI, diabetes, steroid, bisphosphonates, aetiology of arthritis pre-operative alignment does not significantly affect the functional outcome or rate of union. Smokers should be encouraged to stop smoking before going for surgery as smoking can significantly increase the time taken for union. Patients with neuromuscular problems may require more rigid fixation and a longer period of immobilization to achieve more consistent union rates. Acknowledgement None. References [1] Thordarson DB. Fusion in posttraumatic foot and ankle reconstruction. J Am Acad Orthop Surg 2004;12(September–October (5)):322–33. [2] Albert E. Beitrage zur operative Chirurgie. Zur resection des kniegelenkes, vol. 20. Wien Med Press; 1879. p. 705–8. [3] Frey C, Halikus NM, Vu-Rose T, Ebramzadeh E. A review of ankle arthrodesis: predisposing factors to non-union. Foot Ankle Int 1994;15(11):581–4. [4] Mann RA, Rongstad KM. Arthrodesis of the ankle: a critical analysis. Foot Ankle Int 1998;19(1):3–9. [5] Schneider DA. Arthroscopic ankle fusion. Arthrosc Video J 1983;3:35–47. [6] O’Brien TS, Hart TS, Shereff MJ, Stone J, Johnson J. Open versus arthroscopic ankle arthrodesis: a comparative study. Foot Ankle Int 1999;20(June (6)):368–74. [7] Myerson MS, Quill G. Ankle arthrodesis: a comparison of an arthroscopic and an open method of treatment. Clin Orthop Relat Res 1991;268:84–95. [8] Winson IG, Robinson DE, Allen PE. Arthroscopic ankle arthrodesis. J Bone Jt Surg Br 2005;87(3):343–7. [9] Pierre A, Hulet C, Locker B, Souquet D, Jambou S, Vielpeau C. Arthroscopic tibiotalar arthrodesis: limitations and indications in 20 patients. Rev Chir Orthop Reparatrice Appar Mot 2003;89(2):144–51. [10] Ferkel RD, Hewitt M. Long term results of arthroscopic ankle arthrodesis. Foot Ankle Int 2005;26(4):275–80. [11] Dannawi Z, Nawabi DH, Patel A, Leong JJ, Moore DJ. Arthroscopic ankle arthrodesis: are results reproducible irrespective of pre-operative deformity? Foot Ankle Surg 2011;17(4):294–9. [12] Collman DR, Kaas MH, Schuberth JM. Arthroscopic ankle arthrodesis: factors influencing union in 39 consecutive patients. Foot Ankle Int 2006;27(12): 1079–85.

Please cite this article in press as: Jain SK, et al. Analysis of risk factors for failure of arthroscopic ankle fusion in a series of 52 ankles. Foot Ankle Surg (2015), http://dx.doi.org/10.1016/j.fas.2015.05.007

G Model

FAS-833; No. of Pages 6 6

S.K. Jain et al. / Foot and Ankle Surgery xxx (2015) xxx–xxx

[13] Gougoulias NE, Aggathangelidis F, Parsons SW. Arthroscopic ankle arthrodesis. Foot Ankle Int 2007;28(6):695–706. [14] Buck P, Morrey BF, Chao EY. The optimum position of arthrodesis of the ankle: a gait study of the knee and ankle. J Bone Jt Surg 1987;69(7):1052–62. [15] Tochigi Y, Suh JS, Amendola A, Pedersen DR, Saltzman CL. Ankle alignment on lateral radiographs. Part 1: sensitivity of measures to perturbations of ankle positioning. Foot Ankle Int 2006;27(2):82–7. [16] Tochigi Y, Suh JS, Amendola A, Saltzman CL. Ankle alignment on lateral radiographs. Part 2: reliability and validity of measures. Foot Ankle Int 2006;27(2):88–92. [17] Monroe MT, Beals TC, Manoli A. Clinical outcome of arthrodesis of the ankle using rigid internal fixation with cancellous screws. Foot Ankle Int 1999;20(4):227–31. [18] Saragas NP. Results of arthroscopic arthrodesis of the ankle. Foot Ankle Surg 2004;10(3):141–3. [19] Reus WE, Robson MC, Zachary L, Heggers JP. Acute effects of tobacco smoking on blood flow in the cutaneous microcirculation. Br J Plast Surg 1984;37(April (2)):213–5. [20] Nadler JL, Velasco JS, Horton R. Cigarette smoking inhibits prostacyclin formation. Lancet 1983;1(June (8336)):1248–50. [21] Chamson A, Frey J, Hivert M. Effects of tobacco smoke extracts on collagen biosynthesis by fibroblast cell cultures. J Toxicol Environ Health 1982;9(5– 6):921–32. [22] Mosely LH, Finseth F. Cigarette smoking: impairment of digital blood flow and wound healing in the hand. Hand 1977;9(2):97–101. [23] Effeney DJ. Prostacyclin production by the heart: effect of nicotine and carbon monoxide. J Vasc Surg 1987;5(2):237–47. [24] Birnstingl MA, Brinson K, Chakrabarti BK. The effects of short-term exposure to carbon monoxide on platelet stickiness. Br J Surg 1971;58(11):837–9.

[25] Cobb TK, Gabrielsen TA, Campbell 2nd DC, Wallrichs SL, Ilstrup DM. Cigarette smoking and non-union after ankle arthrodesis. Foot Ankle Int 1994;15(2):64–7. [26] Waters RV, Gamradt SC, Asnis P, Vickery BH, Avnur Z, Hill E, et al. Systemic corticosteroids inhibit bone healing in a rabbit ulnar osteotomy model. Acta Orthop Scand 2000;71(June (3)):316–21. [27] Blunt JW, Plotz CM, Lattes R, Howes EL, Meyer K, Ragan C. Effect of cortisone on experimental fractures in the rabbit. Proc Soc Exp Biol Med 1950;73(4): 678–81. [28] Sissons HA, Hadfield GJ. The influence of cortisone on the repair of experimental fractures in the rabbit. Br J Surg 1951;39(September (154)):172–8. [29] Abu EO, Horner A, Kusec V, Triffitt JT, Compston JE. The localization of the functional glucocorticoid receptor alpha in human bone. J Clin Endocrinol Metab 2000;85(2):883–9. [30] Fleisch H. Bisphosphonates: mechanisms of action. Endocr Rev 1998;19(1):80–100. [31] Schell H, Lienau J, Epari DR, Seebeck P, Exner C, Muchow S, et al. Osteoclastic activity begins early and increases over the course of bone healing. Bone 2006;38(April (4)):547–54. [32] Kleerekoper M. Prevention of postmenopausal bone loss and treatment of osteoporosis. Semin Reprod Med 2005;23(2):141–8. [33] Neviaser AS, Lane JM, Lenart BA, Edobor-Osula F, Lorich DG. Low-energy femoral shaft fractures associated with alendronates use. J Orthop Trauma 2008;22(May–June (5)):346–50. [34] Coester LM, Saltzman CL, Leupold J, Pontarelli W. Long-term results following ankle arthrodesis for post-traumatic arthritis. J Bone Jt Surg Am 2001;83A(February (2)):219–28. [35] Nihal A, Gellman RE, Embil JM, Trepman E. Ankle arthrodesis. Foot Ankle Surg 2008;14(1):1–10.

Please cite this article in press as: Jain SK, et al. Analysis of risk factors for failure of arthroscopic ankle fusion in a series of 52 ankles. Foot Ankle Surg (2015), http://dx.doi.org/10.1016/j.fas.2015.05.007