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Open in situ subtalar arthrodesis (ISTA) has been a standard procedure for treating subtalar arthritis for varied etiologies with good outcomes. There has been a paradigm shift from ISTA to arthroscopic subtalar arthrodesis (ASTA) over the past two decades due to increase in number of surgeons performing arthroscopy worldwide. However, there is only limited evidence in the existing literature to substantiate the benefit of this change with regards to patient benefit. To our knowledge, there are also no systematic reviews comparing the results of the two techniques for subtalar arthrodesis (STA).
Aim
Our systematic review aims to determine the superior technique for performing STA by comparing the outcomes, union rates, and complications between open and arthroscopic approach for in situ STA. We hypothesised that both procedures would have similar outcomes, union rates, time to union, and complication rate for in-situ STA.
Evidence review
Three databases, MEDLINE/PubMed, the Cochrane Library, and Google Scholar, were searched using predefined inclusion and exclusion criteria to compare the two procedures. Risk of bias assessment was done using The Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I) tool for assessing the risk of bias in the included studies. Weighted mean averages were computed for all parameters and tabulated separately for ASTA and ISTA.
Findings
We included a total of 22 studies with a total of 978 (ASTA-310, ISTA-668) patients in the review. The most common indication for both techniques was post traumatic subtalar arthritis due to malunited calcaneal fracture in both groups (54.5%). The American Orthopaedic Foot & Ankle Society score was better in the ASTA group with a weighted average improvement of 43.4, while the weighted average improvement was 31.1 in the ISTA group, respectively. Patients undergoing ASTA had a weighted average union rate of 95.5% (standard deviation [SD]-3.6) with a weighted average time to union of 12.2 weeks (SD-2.4) while the ISTA group reported 90.7% (SD-6) union rate with a weighted average time to union of 15.5 weeks (SD-8.4). The weighted overall average complication rate was 13.1% (SD-8.9) in ASTA group and 20.3% (SD-16.2) in the ISTA group with hardware-related complications being the most common in both the groups.
Conclusion
From the existing literature, our review suggests that both ASTA and ISTA techniques are effective procedures for STA. However, there is no conclusive evidence to recommend one technique over another. High quality randomised studies may be further required to clearly define the superiority of one technique over another
Previously done retrospective studies indicate similar outcomes and union rates with shorter time to union and return to sports and activities of daily living with arthroscopic subtalar arthrodesis (ASTA) in comparison to open in situ subtalar arthrodesis (ISTA).
What are the new findings?
•
This is the first systematic review to compare data on arthroscopic versus open approach for performing ISTA.
•
From the existing literature, our review suggests that both ASTA and ISTA techniques are effective procedures for STA. However, there is no conclusive evidence to recommend one technique over another. High quality randomised studies may be further required to clearly define the superiority of one technique over another
Introduction
Subtalar arthritis is a commonly encountered problem in the outpatient clinic that can be secondary to malunited calcaneal fractures most commonly while inflammatory joint disease, tarsal coalitions, and primary osteoarthritis are less common causes [
Is distraction bone block Arthrodesis better than subtalar arthrodesis for malunited calcaneal fractures with subtalar arthritis? A retrospective case series.
]. Open ISTA is an effective strategy in managing subtalar arthritis that relieves pain and improves function of the affected hind foot though gross malalignment and significant bone loss at talus/calcaneum may limit its use in all cases of subtalar joint pathologies [
]. Over the past two decades, there has been a paradigm shift from ISTA to ASTA as the preferred technique for performing subtalar arthrodesis (STA) due to advantages like preservation of blood supply of the involved bones and proprioceptive input for the foot and also due to lesser perioperative morbidity and its minimal invasive nature [
]. However, there is only limited evidence in existing literature to substantiate the benefit of this change with regards to patient outcomes, union rates, and complications. To our knowledge, there are also no systematic reviews comparing the results of the two techniques for STA. Our systematic review aims to determine the superior technique for performing STA by comparing the outcomes, union rates, and complications between open and arthroscopic approach for ISTA. We hypothesized that both procedures would have similar outcomes, union rates, time to union, and complication rate for ISTA.
Methodology
A literature search was conducted as per the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [
]. A comprehensive search was conducted for studies-related to STA in 3 databases including MEDLINE/PubMed, the Cochrane Library, and Google Scholar. Search terms were broad to encompass all studies involving STA and included the following combination of keywords and Boolean operators: ‘talocalcaneal’ OR ‘subtalar’ AND ‘arthrodesis’ OR ‘fusion’. All studies in English language reporting functional outcomes or union rates of isolated in-situ subtalar fusion were included.
Screening
The search results were exported to the systematic review software Rayyan [
], to eliminate duplicates and to screen the title and abstracts for relevant studies by applying the inclusion and exclusion criteria. The screening process included two reviewers (Author 2) (Author 4) with initial Blind-on for individual assessment and with Blind-off subsequently for collaboration and sorting conflicted articles.
Inclusion and exclusion criteria
Patients with post-traumatic subtalar arthritis, primary arthritis, infective/inflammatory arthritis, talocalcaneal coalitions, isolated STA for pes planovalgus were included in the review. Distraction arthrodesis, primary arthrodesis for displaced intra-articular calcaneal fractures, arthrodesis in combination of other procedures or adjacent joint fusions, skeletally immature patients with extra-articular STA, fusions for deformities in cerebral palsy, polio and Charcot's arthropathy were excluded from the review. Cadaveric and biomechanical studies, animal studies, review articles, technical notes, conference proceedings, and case reports were also excluded.
Risk of bias assessment
Risk of bias (ROB) assessment was done using ROBINS-I tool [
] as advocated by the Cochrane group for assessing ROB in non-randomised studies of interventions by (Author 2) (Author 3) (Author 4). This is a tool comprising of 7 domains assessing bias from confounding (D1), selection of participants (D2), classification of intervention (D3), deviations from intended intervention (D4), missing data (D5), measurement of outcomes and reporting results (D6 and D7). Each domain and eventually overall ROB was graded as low, moderate, serious, critical, and no information.
Data extraction and analysis
Each article was analysed in detail by (Author 1) (Author 2) (Author 3) (Author 4) and the data was tabulated systematically by (Author 2) (Author 4). Author followed by year of publication, Level of evidence (LOE), Portals/Approach for STA, number of patients/feet included in the study, duration to surgery (months), age, sex ratio, follow-up (months) was tabulated for ASTA, ISTA, and for comparative studies under demographic details (Table I). Functional scores, union rates, time to union, modality used for the assessment of union were tabulated for all studies (Table II). Complications were classified under hardware-related; non-union, wound healing/infection, and nerve related complications and analysed separately (Table III). Weighted mean values were calculated by multiplying the average mean value of a parameter with number of patients in that study. Values from each study were then added and divided by the total number of patients.
Table IDemographic details.
Author (year)
LOE
Portals/Approach
No. of patients
No. of feet
Mean age (years)
Sex ratio (M:F)
Duration to surgery (months)
Follow-up (m)
ASTA
1. Coulomb 2019 (20)
IV
P2P
22
22
49.5
16:6
67.7 (8–468)
24.1 (12–38)
2. Aldahshan 2018 (21)
IV
P2P
15
15
38
13:2
24 (6–36)
36 (30–38)
3. Walter 2018 (26)
IV
Sinus tarsi/lateral 2 portals
74
77
53.4
44:30
NR
15.3
4. Rico 2017 (22)
III
P2P
65
65
50
38:27
NR
57.5 (24–105)
5. Oliva 2017 (23)
IV
P2P
19
19
50.9
12:7
NR
42.9 (15.5–68)
6. Albert 2011 (24)
IV
P2P
10
10
37.8
6:4
NR
21.5 (12–31)
7. Lee 2010 (25)
IV
P2P
16
16
44
16:0
NR
30 (20–46)
8. El shazly 2009 (13)
IV
Lateral- 3portal
10
10
42
8:2
NR
28.4 (24–32)
9. Amendola 2007 (5)
IV
P3P
10
11
41
5:5
45 (11–168)
34 (24–48)
ISTA
10. Paiva 2019 (32)
III
Lateral
80
80
47.6
63:17
NR
23.2 (14.8–54.1)
11. Jangir 2019 ((9)
IV
Lateral
12
12
39
9:3
NR
22 (20–24)
12. Perez 2015 (28)
III
Lateral
33
33-Total 17(screws), 16(staples)
57
26:7
NR
43 (24.5–84.3)
13. Romeo 2015 (29)
III
Lateral
33
33
41.5
22:11
NR
44 (14–70)
14. Yuan 2014 (27)
III
A: Lateral, B: Sinus tarsi, C: Posterolateral
102
102
43.2
64:38
38 (1–360)
NR
15. Joveneaux 2010 (30)
IV
Lateral
26
28
48
19:16
NR
NR
16. Decarbo 2010 (33)
IV
Lateral
113
113
49
54:59
NR
24
17. Diezi 2008 (31)
IV
Lateral
12
15
45.3
6:6
NR
33 (24–47)
18. Haskell 2004 (34)
III
Lateral
100
101
52
48:52
NR
NR
19. Mann 1998 (3)
III
Lateral
44
48
41
18:26
42 (12–156)
59.5 (24–177)
20. Kitaoka 1997 (35)
IV
Lateral
21
21
60
18:3
NR
36 (24–60)
21. Mangone 1997 (42)
IV
Lateral
32
34
53
16:16
NR
30.8 (16–55)
ASTA VERSUS ISTA
22. Rungprai 2016 (2)
III
PASTA/Lateral
69/60
60/69
47.6
67:54
66.8 (6–126)
23.7 (6–126)
Abbreviations: ASTA-Arthroscopic subtalar arthrodesis, ISTA-open in situ subtalar arthrodesis, LOE-Level of evidence,P2P-Posterior two portal, P3P-Posterior three portal, NR-Not Reported.
The initial search identified 800 articles, all of which were screened to exclude duplicates (n = 294). Among the 506 patients, the title and abstracts were screened by two reviewers to exclude those not relevant to the review (n = 463), leaving 43 articles for detailed analysis. Full text retrieval was attempted for these filtered 43 articles. 21 articles were excluded due to non-availability of full text/other language (n = 2), those including distraction arthrodesis/primary arthrodesis/combination of other procedures, extra-articular arthrodesis (n = 12), STA using minimally invasive techniques/using trephine (n = 4), duplicates (n = 2), and one being a Level V study, which left a total of 22 articles (9-ASTA, 12-ISTA, and one retrospective study comparing both the techniques) for this systematic review with a total of 978 (ASTA-310, ISTA-668) patients. The PRISMA flowchart depicting the results of screening and selection has been outlined in Fig. 1. The highlight of the screening process was a lack of Level I and Level II studies between the two methods for STA.
Fig. 1Flow chart depicting the results of screening and selection.
ROB assessment revealed majority studies included were prospective/retrospective level III/IV studies. 12 studies had only moderate ROB in at least one domain making them comparable to a well conducted non-randomised study. One study by Jangir et al. [
] was analysed to have serious bias in measuring outcomes and reporting results. 9 out of 22 studies had a low ROB, making them comparable to a well conducted randomised trial. These results were plotted graphically as “traffic light” plots for each study using the Robvis tool [
Fig. 2Risk of bias assessment using ROBINS-I (Risk of bias in non-randomised studies of interventions) and ROBVIS TOOL (Visualisation tool for risk of bias assessments in a systematic review).
]. Both techniques included patients undergoing isolated STA for varied indications without additional procedures. American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scoring system [
] were the outcome measures reported across the studies. However, AOFAS modified with a maximum score of 94 (compensation for the loss of subtalar joint function) [
] was the most commonly used scoring system for reporting the outcomes. However, both preoperative and postoperative AOFAS scores were reported only in 12 studies [
There was a lack of single modality for analysing union with plain radiographs being employed most commonly with the use of CT scans utilised when in doubt of union.
ASTA
The ASTA technique is broadly categorised depending on the portals employed for STA. The initial approach was by using anterolateral-posterolateral (AL/PL) portals as described by Tasto in 1992 [
] that employed the lateral approach while the rest employed the PASTA technique for STA.
310 patients were included in the ASTA group with a weighted mean age of 48 (SD-5.8) years with a mean duration of symptoms of 59.5 (SD-21.9) months. The most common indication was post traumatic arthritis following malunited calcaneum fracture (n = 146) (62%) followed by primary arthritis (n = 31) (13%), adult acquired flat foot (n = 28) (11.8%), Talocalcaneal coalitions (n = 18) (7.6%), and inflammatory arthritis (n = 9) (3.8%), respectively, among 9 studies with 236 patients that reported the indications [
]. Subtalar instability and Talus fracture were other indications for ASTA. Additional procedures for flat foot deformity correction per say were not mentioned among studies that included STA for adult acquired flat foot (AAFD) [
], weighted pre-operative scores improved from 45.4 (SD-5.8) to 93.5 (SD-7.8) post-operatively with a mean improvement of 43.4. Majority, i.e. 5/9 studies [
], employed plain radiographs to assess union and in doubtful cases used CT (computerised tomography). Patients undergoing ASTA had a weighted average union rate of 95.5% (10 studies, 305 patients) with a weighted average time to union of 12.2 weeks (9 studies, 288 patients). The overall weighted average complication rate was 13.1%. Hardware-related complications were the most common complication in patients undergoing ASTA with a weighted average of 8% followed by non-union (weighted average of 4.5%). Wound healing problems/infection (weighted average-1%), nerve injury (weighted average of 1%), flexor hallucis longus rupture, and complex regional pain syndrome (CRPS) were other reported complications.
ISTA
The open technique of arthrodesis can be broadly divided into the traditional lateral approach using a skin incision between the tip of lateral malleolus and the base of 4th metatarsal, the sinus tarsi approach using a parallel incision along the sinus tarsi ,and a posterolateral L approach employing an incision from the base of the 5th metatarsal curving upward along the lateral border of tendoachilles [
]. described the differential efficacy of three approaches.
668 patients underwent ISTA with a weighted average age of 50.2(SD-6.5) years and weighted average symptom duration of 45.4 months. The most common indication was post-traumatic arthritis following malunited calcaneum fracture (n = 347) (52%) followed by primary arthritis (n = 117) (17.5%), adult acquired flat foot (n = 64) (9.5%), talocalcaneal coalition (n = 30) (4%), and inflammatory arthritis (n = 24) (3.5%), respectively, among 13 studies with 668 patients. Infection including tuberculosis, osteochondral lesions of talus and calcaneum, subtalar joint instability and talus fracture were other indications for ASTA.
In 6 studies that included 206 patients that reported the pre-operative and post-operative AOFAS scores, the pre-operative scores improved from a weighted average of 52.2 (SD-4.8) to 84.3 (SD-5.1) post-operatively with a mean improvement of 31.1 [
], majority i.e., 6 studies employed only plain radiographs for assessing bony union. The weighted average union rate in patients undergoing ISTA was 90.7% (11 studies, 603 patients). Among the 7 studies [
] reporting the time to union, the weighted average time to union was 15.5 weeks. The overall weighted average complication rate was 20.3%. Hardware-related complications were the most common complications as in patients undergoing ASTA with weighted average of 9.3%. Wound healing problems/infection (weighted average - 1%), nerve injury (weighted average - 5.9%), CRPS, and painful scar were other reported complications. The weighted mean average values for all parameters in both procedures have been summarised in Table IV.
Table IVWeighted average mean values.
Parameters
Number of patients included for the pooled outcome ASTA:ISTA
] found no difference in outcomes, union rates, and complications between staples and cannulated screws for STA in their series of 33 patients. The use of a second screw did not increase fusion rates in two studies [
]. Though posterior-anterior (PA) screw insertion has been the most prevalent method for fixation across studies two studies employed the anterior-posterior fixation (AP) [
] reported a mean surgical time of 100 min (range, 65–160) for PASTA compared to 93.4 min (range, 47–139) for open ISTA that was statistically significant. The weighted average hospital stay in our review was 1.73 days in the ASTA group among 4 studies [
] reported a range of 0–1 day of hospital stay for ASTA group versus 0.4–4.3 days of hospital stay for ISTA group. One study reported the time to return to activities of daily living as 15.5(SD-2.9) weeks for ASTA and 10.9(SD - 2.5) weeks for ISTA [
] reported that sports participation reached pre-surgery levels; however, there was a shift from high to low impact activities post ISTA.
Discussion
The most important finding of our review is that ASTA results in a better functional outcome, union rate, faster time to union with less complication rate than ISTA Another striking finding is the lack of level I and level II studies and systematic reviews/metanalyses comparing the two procedures previously.
There was a significant improvement in AOFAS scores post ASTA and ISTA; however, the mean weighted difference between post-operative and pre-operative scores was 43.4 in ASTA and 31.21 in ISTA groups, respectively. Patients undergoing STA have been previously reported to have a high satisfaction rate with almost 90% of them recommending the procedure to friends and family [
]. Our review included STA for various indications that have employed different outcome measures for the assessment of functional outcome at varied intervals. Though better functional outcomes were observed in patients undergoing ASTA, a conclusive opinion cannot be based on existing evidence due to lack of statistical analysis. Though the outcomes were not analysed based on aetiology in most studies, Mann [
] et al. reported better functional outcomes when STA is done for patients with primary arthritis followed by patients with posterior tibialis tendon dysfunction followed by those undergoing STA for malunited calcaneal fracture. Malunited calcaneal fractures maybe associated with problems such as varus malunion, loss of heel height, lateral calcaneofibular impingement, ankle impingement which maybe better addressed by distraction arthrodesis than ISTA [
]. Hence, careful patient selection especially while dealing with post-traumatic arthritis for ASTA or ISTA is necessary to obtain a high satisfaction rate.
The overall fusion rate and time to fusion was also better in the ASTA group than in the ISTA group. Jones et al. [
] concluded that CT scans were a better modality to assess fusion and that non-unions would be picked up only half the time on plain radiographs. Dorsey et al. devised the CT fusion ratio and divided non-union as < 33% fusion, incomplete fusion as 34–66% and complete fusion as 67–100% [
]. 11 studies in our review have employed plain radiographs, using CT scans only in case of doubt to assess union. This result could have been validated better if there was uniformity in the usage of plain radiographs or CT scans across the studies for reporting union. Union rate was not affected by using an additional screw as probably this decreased the contact surface for fusion that neutralised the actual mechanical superiority gained without any real benefit [
A direct comparison of the PASTA and lateral portal technique for STA was not possible due to paucity of studies employing the lateral approach in our review [
] reported a better functional outcome, lower complication rate with a lower union rate with PASTA than lateral portal approach to STA. In the open ISTA group, one study by Yuan et al. [
] studied the differential efficacy of open ISTA with three approaches and found that surgical area exposed was least in sinus tarsi approach while time for exposure, intraoperative bleeding volume, and complications are higher in PL approach while there was no difference in fusion rate/time to fusion with the three approaches.
The overall complication rate was more in patients undergoing ISTA than ASTA. Majority of the complications were due to the screws used for fixation irrespective of the technique. Wound-related complications were 1% in both techniques, indicating that wound healing problems are not an actual concern in patients undergoing ISTA. Nerve-related numbness/paresthesia due to either sural nerve/superficial peroneal nerve involvement were more in patients undergoing ISTA than ASTA probably due to the more invasive nature of the technique.
Though the weighted average mean of the pooled data is better for ASTA than ISTA with respect to functional outcome, time to union and overall complications, conclusive recommendation to prefer one technique over another cannot be made due to lack of statistical analysis. It should be noted that ASTA can only be used in cases of isolated STA without significant deformities/malalignment. Also, most of the studies have included patients with varied indications consisting of post-traumatic and non-traumatic cases. Thus, a careful patient selection is recommended for achieving optimal outcomes especially while employing ASTA for ISTA.
Limitations
This review has taken level III/IV studies into consideration due to paucity of prospective randomised studies. As only one study had a comparative analysis [
] while others were either retrospective or prospective studies/series studying either of the techniques separately, variable reporting of data, variable lengths of follow-up, different modalities used for the analysis of union made direct comparison and statistical analysis difficult. Future directives for research would be to include large scale randomised studies comparing both the techniques with the utilisation of CT for assessing union with standardised outcomes measures.
Conclusion
From the existing literature, our review suggests that both ASTA and ISTA techniques are effective procedures for STA. However, there is no conclusive evidence to recommend one technique over another. High quality randomised studies may be further required to clearly define the superiority of one technique over another.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
Rajasekaran S.
Sundararajan S.R.
Ramakanth R.
Shreeram V.
Joseph J.B.
Is distraction bone block Arthrodesis better than subtalar arthrodesis for malunited calcaneal fractures with subtalar arthritis? A retrospective case series.
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