Efficacy evaluation and systematic review of supramalleolar osteotomy for treatment of varus-type ankle arthritis

Abstract

Background

The current surgical treatment plan for medium-term varus-type ankle arthritis is primarily supramalleolar osteotomy (SMOT), but the reliability of this procedure still lacks high-quality evidence-based medical studies, such as randomized controlled clinical trials and meta-analyses of comparative studies.

Objective

The current study explored whether significant differences were present in the clinical effect, reoperation rate, complications, and failure rate of this type of surgery.

Method

Two researchers searched the relevant literature in seven databases, including PubMed, Cochrane Library, EMBASE, the China Biomedical Literature Database, the China Academic Journals Full-text Database, the Wanfang database, and the Weipu Chinese Science and Technology Journal Database. The retrieval time spanned the establishment of the specific database up to September 2020, and the literature was screened to determine their final inclusion in the study.

Results and conclusions

A total of 20 studies were included, including one Chinese and 19 English language studies. The primary indicators included a definitive effect of SMOT on the treatment of medium-term varus-type ankle arthritis. Concerning secondary indicators, although the surgery effect was satisfactory, some patients may require follow-up surgery, which may be unsuccessful with complications. The study results showed that, based on existing literature reports, the effect of SMOT for varus-type ankle arthritis was a satisfactory surgical method with some clinical value for correcting the ankle force line and relieving or even reversing ankle arthritis. However, its risk of complications and failure rate were comparatively high and, accordingly, requires good preoperative planning and close communication with patients. Due to the limited sample size of this study, more data and longer follow-up times involving this type of surgery should be reviewed to confirm this conclusion.

Keywords

varus-type ankle arthritis supramalleolar osteotomy treatment meta-analysis

Introduction

According to statistics, nearly 1% of adults worldwide suffer from ankle osteoarthritis (OA).¹ Several pathogenic factors are involved in this condition, including congenital abnormalities of the tibia, deformed healing following a distal tibial fracture, distal tibial epiphysis injury, infection, ankle instability, and neuromuscular disease.² Ankle varus and valgus deformities are the primary manifestations of common ankle malalignment.³ In patients with symptomatic ankle osteoarthritis, it has been reported that varus and valgus ankles account for 70%–80%³ of symptomatic ankle osteoarthritis. Valderrabano et al.⁴ found that 55% of ankle OA patients had combined ankle varus and 8% had combined ankle valgus.

In 1936, Speed and Boyd⁵ published a clinical study on designing a method for treating post-ankle trauma deformity and identified three key targets for supramalleolar readjusted surgical procedures as follows: (1) restore the proper force line; (2) restore the proper arrangement of the tibial pitch joint surface; 3) restore the physiological and pain-free activity range of the tibiotalar joint. Subsequently, Takakura and colleagues⁶ were the first to systematically report the application of SMOT in 1995 and proposed the classification of varus ankle OA. This was mainly classified into four types as follows: stage (1) the joints are parallel, without joint space stenosis, early subchondral osteosclerosis or osteophyte formation; stage (2) the medial joint space is narrow without subchondral bone contact; stage (3) (a) the medial ankle space is occluded, and the subchondral bone contact is medial; (b) subchondral bone contact extends to the fornix of the talus; stage (4) a varus ankle joint with complete bone contact.^6,7

In the reports of these scholars, the effect of SMOT on the treatment of medium-term ankle arthritis was predictable.⁴ Nonetheless, there are currently no systematic reports that confirm these results. Supramalleolar osteotomy for ankle arthritis still lacks high-quality evidence-based ST, e.g. randomized controlled clinical trials and meta-analyses of comparative studies. Meta-analysis is increasingly being recognized as a key tool for obtaining high-quality evidence.^8,9,10 Accordingly, this study adopted a meta-analysis approach to perform a comparative investigation of existing studies to determine whether there were significant differences in clinical scores and reoperation rates. The aim of doing so was to better understand the application of SMOT in varus-type ankle arthritis.

Data and methods

Search strategy

The current study was conducted according to the Preferred Reporting Items of Systematic Review and Meta-Analysis set. Two researchers conducted searches for the relevant literature in seven databases, i.e. PubMed, Cochrane Library, EMBASE, the China Biomedical Literature Database, the Chinese Journal Full Text Database, the Wanfang database, and the Weipu Chinese Science and Technology Journal Database. The retrieval time spanned the establishment of the specific database up to September 2020.

The search was performed in strict accordance with the PICOS (population, intervention, comparison, outcome, study) design principles, and the remaining relevant literature was searched manually. Subject-related terms were combined with free words; the English search terms were ‘supramalleolar osteotomy’, ‘osteotomy’, ‘low tibial osteotomy’ and ‘ankle’, ‘ankle arthritis’, ‘ankle osteoarthritis’, ‘varus ankle’, ‘varus ankle arthritis’, ‘varus ankle osteoarthritis and/or ‘treatment’. The Chinese search terms included ‘supramalleolar osteotomy’, ‘ankle arthritis’, ‘varus’ and ‘treatment’. The literature search results were not limited in terms of time, country or region. Following an initial electronic search, the authors searched other relevant articles by scanning the bibliographies of all the selected full-text articles.

Selection criteria

Inclusion criteria

The study’s inclusion criteria were as follows: (1) the literature study reported on patients diagnosed with varus ankle arthritis who were treated with SMOT; (2) the study reported on the treatment efficacy of SMOT, preoperative and postoperative effect comparisons, and provided a complete description of various pre-and post-surgery; (3) the study included American Orthopaedic Foot and Ankle Society (AOFAS) scores; (4) the study included pain scores.

Exclusion criteria

The study’s exclusion criteria were as follows: (1) repeated studies; (2) case reports, reviews, meta-analyses, editorials, letters, non-English studies, non-human study cohorts/cadaver experimental studies; (3) studies from which data could not be extracted; 4) literature that was not relevant to the current study.

Data extraction

The data extracted by the researchers included the following: (1) the name of the first author, the publication date, the average age of participants, sample size, patient gender, follow-up time, and the primary indicators (SMOT, varus ankle arthritis) and secondary indicators (complete preoperative and postoperative description, AOFAS score, pain score, postoperative complications elaboration). If disagreement occurred among the researchers during the data extraction process, they sought the help of corresponding authors.

Statistical analysis

Statistical analysis was performed using the SPSS Statistics 21.0 software program. Measurement data were expressed as $\bar{x}$ ± s, and a paired t-test was used for group comparison; p < 0.05 was considered to indicate a statistically significant difference.

Results

Literature screening process

Using the electronic system search, a total of 1591 Chinese documents and 3725 foreign language documents were retrieved. Subsequently, reviews, meta-analyses, case reports, books and repeated literature were excluded. Following additional review of the article’s title and abstract, 1590 Chinese documents and 3705 foreign language documents were excluded. After further reading of the full article, one article with incomplete data was excluded. Finally, 20 retrospective study articles that met the study criteria were selected for analysis (see Figure 1).

Figure 1.

Literature screening process.

Characteristics of the included studies

The included papers were all retrospective studies. All 20 studies were published between 2006 and 2019 and included 686 cases of varus ankle arthritis. Follow-up procedures were performed between 27.2 and 97 months. Basic information regarding the included literature is shown in Table 1.

Table 1.

Basic information of literature.

First author	Research type	Publication time (year)	Average age (years)	Sex ratio male/female, n		Mean follow-up time (months)	Number of cases/ankle, n		Remarks
First author	Research type	Publication time (year)	Average age (years)	Male	Female	Mean follow-up time (months)	Number of people	Ankle number	Remarks
Y. Tanaka⁷	Retrospective	2006	54	0	25	99	25	26
Krähenbühl N¹¹	Retrospective	2019	54.5	31	11	40	44	44	1 person lost
Hongmou Z12	Retrospective	2016	50.7	13	28	36.6	41	41	2 person lost
Xu Y13	Retrospective	2019	53.7	3	18	87.7	21	21
Zhao HM14	Retrospective	2019	SMOT53.4; SMOT WITH MDA56.2	SMOT5; SMOT WITH MDA6	SMOT11; SMOT WITH MDA12	SMOT61.4; SMOT WITH MDA35.6	SMOT16; SMOT WITH MDA18	SMOT16; SMOT WITH MDA18
Qu W15	Retrospective	2019	56.5	13	4	32.2	17	17
Colin F16	Retrospective	2014	50	44	18	42	62	62
ZHAO Hongmou17	Retrospective	2017	TOT48.8; TFOT52.4	TOT 8; TFOT 5	TOT 11; TFOT 17	36.6	41	41
Krähenbühl N18	Retrospective	2017	50.22	73	26	60	99	99
Koo JW19	Retrospective	2019	58.6	2	13	46.3	15	15
Lee WC20	Retrospective	2011	55.2	7	9	27.6	16	16
Kim YS21	Retrospective	2014	52.2	8	21	27.4	29	31
Colin F22	Retrospective	2014	55	41	11	NR	52	52
Hintermann B23	Retrospective	2017	44	NR	NR	48	20	20
Knupp M24	Retrospective	2011	49	NR	NR	43	31	33
Scheidegger P25	Retrospective	2019	47	27	12	21	39	39
Ahn TK26	Retrospective	2015	57	3	15	34	18	18
Kobayashi H27	Retrospective	2016	63	6	19	27.2	25	27
Mann HA28	Retrospective	2012	47	14	5	59	19	19
Choi JY29	Retrospective	2020	61.5	17	14	48.9	31	31

Note: SMOT: supramalleolar osteotomy; SMOT WITH MDA: supramalleolar osteotomy with medial distraction arthroplasty; TOT: tibia osteotomy; TFOT: tibia and fibula osteotomy

Results of the meta-analysis

The correction effect of supramalleolar osteotomy

All of the included literature data were screened. Three data perspectives were included, i.e. tibial articular surface angle (TAS), tibial lateral surface angle (TLS), and talar tilt angle (TT) data were recorded for comparison. Table 2 shows the differences that were found between these categories (relevant data were not recorded in some of the studies and were automatically screened out in the SPSS software).

Table 2.

Corrective effect of supramolecular osteotomy (SMOT).

Paired sample statistics
	mean value	N	Standard value	Standard error of mean
Right 1 Preoperative TAS	84.2050	20	3.67086	0.82083
Postoperative TAS	91.4950	20	3.26295	0.72962
Right 2 PreoperativeTLS	79.7333	18	3.22071	0.75913
PostoperativeTLS	82.1500	18	2.11639	0.49884
Right 3 Preoperative TT	9.5500	20	4.49110	1.00424
Postoperative TT	4.7750	20	3.35416	0.75001

	N	Standard value	Sig.
Paired sample correlation coefficient
Right 1 Preoperative TAS	20	0.041	0.863
Postoperative TAS
Right 2 PreoperativeTLS	18	0.523	0.026
PostoperativeTLS
Right 3 Preoperative TT	20	0.584	0.007
Postoperative TT

	Pairwise difference					t	df	Sig(bilateral)
Paired sample test
	Mean value	Standard value	Standard error of mean	95% confidence interval of difference
	Mean value	Standard value	Standard error of mean	Upper limit	Lower limit
Right 1 Preoperative TASPostoperative TAS	-7.29000	4.80963	1.07547	-9.54098	-5.03902	-6.778	19	0.000
Right 2 PreoperativeTLSPostoperativeTLS	-2.41667	2.77918	0.65506	-3.79872	-1.03461	-3.689	17	0.002
Right 3 Preoperative TTPostoperative TT	4.77500	3.72006	0.83183	3.03396	6.51604	5.740	19	0.000

According to the statistical software results, the three perspectives noted above showed significantly better postoperative results compared with before surgery. The TAS improved from 84.2° preoperatively to 91.5° postoperatively (p < 0.001), TLS improved from 79.7° preoperatively to 82.15°, (P < 0.002) and TT improved from 9.55° preoperatively to 4.78° (p < 0.001). It was concluded that the effect of supramolecular osteotomy on varus ankle arthritis had been clearly indicated.

Ankle function score

The AOFAS scores in the literature data were included for statistical analysis (the relevant data were not recorded in selected papers and were automatically screened out in the SPSS software) (see Figure 2).

Figure 2.

Score of ankle function.

According to the statistical analysis results using the SPSS 21.0 software, the AOFAS score improved from 54.05 preoperatively to 79.67 postoperatively (p <0.001), inferring the conclusion that supramolecular osteotomy benefitted functional improvement in patients with varus ankle arthritis.

Pain score

The visual analogue scale (VAS) scores in the literature data were included for statistical analysis.

(the relevant data were not recorded in some literature and were automatically screened out in the SPSS software) (see Figure 3).

Figure 3.

Pain score.

Based on the statistical analysis conducted using the SPSS software, the VAS pain score decreased from 5.82 preoperatively to 2.45 postoperatively (p < 0.001), inferring the conclusion that supramolecular osteotomy is conducive to pain relief in patients with varus ankle arthritis.

Complications

A total of 69 patients had related complications in the 12 studies, accounting for 10.35%; these included 9 infections (1.3%), 17 cases with delayed fracture healing (2.5%); 42 cases with symptoms (hematoma, pain, impact, joint fibrosis, tarsus syndrome) (6.1%), 1 case with thrombosis and one patient with an internal fixation fracture. The remaining six articles had no reported complications. Table 3 shows the details in this regard.

Table 3.

Complications of supramolleolar osteotomy (SMOT).

The first author	Published date	complications
Krähenbühl N¹¹	2019	One case developed the infection and improved after dressing change and antibiotics. Three fractures showed delayed healing at an average of 4.8 months(Intersection fill is a bone allogeneic graft)
Hongmou Z¹²	2016	Three fractures had delayed healing of up to an average of 6 months (The filling isβ-tricalcium phosphate)
Xu Y¹³	2019	none
Zhao HM¹⁴	2019	Two cases of needle tract infection occurred in the group of osteotomy combined with medial ankle arthroplasty, and improved after dressing change and antibiotics
Qu W¹⁵	2019	One case had incision infection, which was improved with dressing change and antibiotics. One patient developed venous thrombosis after surgery, and received relevant symptomatic treatment
Colin F¹⁶	2014	Ankle fusion was performed in four cases due to persistent arthritis, overcorrection and infection
Zhao H¹⁷	2017	Due to pain, one patients received AA and the other TAR.
Krähenbühl N¹⁸	2017	Two cases developed infection after surgery and improved after symptomatic treatment.Three fractures showed delayed healing at an average of 4.8 months(Intersection fill is a bone allogeneic graft)
Koo JW¹⁹	2019	None
Lee WC²⁰	2011	None
Kim YS²¹	2014	None
Colin F²²	2014	None
Hintermann B²³	2017	None
Knupp M²⁴	2011	None
Scheidegger P²⁵	2019	Two patients developed infection and underwent symptomatic treatment. Four patients had delayed fracture healing, two of whom were smokers, and these two patients were renovated and all healed. Eight patients developed ankle fibrosis. Three patients had ankle impact, and underwent surgery for revision
Ahn TK²⁶	2015	Nine patients indicated that the pain originated from the internal fixation device and was removed, and six patients indicated the presence of an ankle impact and performed secondary surgery
Kobayashi H²⁷	2016	Three cases had internal fixation-associated pain and two cases had subcutaneous hematoma. One incision infection was reported. Due to incision infection to remove internal fixation to external fixation, the postoperative recovery was satisfactory, one person developed tarsal syndrome followed by tarsal loosening, and one person developed internal fixation fracture. After removing internal fixation, the degree was lost by 6°
Mann HA²⁸	2012	Four patients had persistent pain symptoms, 2 cases underwent AA and 2 cases TAR
Choi JY²⁹	2020	None
Y. Tanaka³⁰	2006	Four cases showed bone nonunion, and secondary surgery was performed for improvement

Revision rate

Six studies reported 32 patients who underwent amendment surgery (4.7%). The remaining 14 articles reported no such surgeries. The details in this regard are shown in Table 4.

Table 4.

Revision rate of supramolecular osteotomy (SMOT).

The first author	Published date	Revision rate
Krähenbühl N¹¹	2019	Four patients underwent a secondary revision surgery after the operation
Hongmou Z¹²	2016	None
Xu Y¹³	2019	None
Zhao HM¹⁴	2019	None
Qu W¹⁵	2019	None
Colin F¹⁶	2014	None
Zhao H¹⁷	2017	None
Krähenbühl N¹⁸	2017	None
Koo JW¹⁹	2019	None
Lee WC²⁰	2011	None
Kim YS²¹	2014	None
Colin F²²	2014	None
Hintermann B²³	2017	None
Knupp M²⁴	2011	None
Scheidegger P²⁵	2019	Two cases with bone nonunion underwent bone repair surgery.Twelve secondary surgeries were performed, including eight cases with joint fibrosis, three with impact, and one case with progressive OA;
Ahn TK²⁶	2015	Six cases had an ankle impact, and secondary surgery was performed
Kobayashi H²⁷	2016	One case had incision infection, which was transferred to external fixation, with satisfactory postoperative recovery. One person developed tarsal syndrome followed by tarsal release, and one case showed an internal fixation fracture, and the internal fixation was removed.
Mann HA²⁸	2012	None
Choi JY²⁹	2020	One person cases underwent repair surgery
Y. Tanaka³⁰	2006	Four cases showed bone nonunion, and secondary surgery was performed for improvement

Failure rate

The total failures included 62 cases in 13 studies (9%). One of the reasons for these failures was the progression of ankle arthritis; a second reason involved persistent symptoms and serious ankle dysfunction. The remaining seven articles did not report any failure rates. Table 5 shows the details in this regard.

Table 5.

Failure rate of supramolleolar osteotomy (SMOT).

The first author	Published date	Failure rate
Krähenbühl N¹¹	2019	Ten operations eventually failed. Eight underwent TAR at an average of 28.8 months, and two had AD within an average of 7.2 months
Hongmou Z¹²	2016	Two cases underwent AD at 17 and 26 months
Xu Y¹³	2019	One case underwent TAR 3 years later
Zhao HM¹⁴	2019	Three cases (SMOT) underwent AD at 17,26, and 61 months
Qu W¹⁵	2019	None
Colin F¹⁶	2014	Four cases underwent AD
Zhao H¹⁷	2017	Due to pain, one patient received AA and the other TAR.
Krähenbühl N¹⁸	2017	Seventeen operations failed, 3 cases underwent AD and 14 cases underwent TAR
Koo JW¹⁹	2019	None
Lee WC²⁰	2011	None
Kim YS²¹	2014	None
Colin F²²	2014	None
Hintermann B²³	2017	One surgery failed, and TAR was performed
Knupp M²⁴	2011	Ten surgeries failed, and TAR or AD was performed
Scheidegger P²⁵	2019	Nine cases underwent TAR or AD at 21 months
Ahn TK²⁶	2015	One case underwent TAR
Kobayashi H²⁷	2016	None
Mann HA²⁸	2012	Due to persistent pain, 2 cases underwent AA and 2 cases TAR
Choi JY²⁹	2020	None
Y. Tanaka³⁰	2006	Two cases failed, and underwent AD

Discussion

In the 20 literature studies on varus ankle arthritis, the bulk reported on the progression of ankle arthritis slowing, maintaining its current state, or even indicating reversal. A study by Zhao¹² showed that at an average follow-up of 36.6 months, a total of 22 (57%) cases indicated slowed varus ankle arthritis, 13 (33%) cases remained unchanged, and 4 (10%) cases indicated a worsening condition. A study conducted by Qu¹⁵ showed a mean follow-up time of more than 32.2 months; the arthritis stage was improved in 11 (65%) cases, in which 2 cases ranged from stage 2 to 1, 7 cases ranged from stage 3a to 2, and 2 ranged from stage 3b to stage 3a. Six cases indicated no changes, and there was no aggravated cases. A study conducted by Hintermann²³ had an average follow-up of 4 years, during which time 3 ankles deteriorated by one stage (1 ankle, phase I–Ⅱ; 2 ankles, phase Ⅱ–Ⅲ), 11 ankles improved by one stage (3 ankles, phase Ⅱ–I; 7 ankles, phase Ⅲ–Ⅱ; one ankle, phase Ⅳ–Ⅲ) and 6 ankles were unchanged. In these reports, more than 50% of ankle arthritis showed improvement, and a small number of patients had made progress.

Although SMOT can delay the progression of ankle arthritis, the surgical failure rate is as high as 9% and cannot be ignored. According to the mid-term follow-up results reported by Krahenbuhl,¹⁸ the 5-year survival rate was 75%, while the 5-year survival rate of stage 3b was only 47%, i.e. the patient was very likely to undergo ankle degeneration within 5 years, or persistent symptoms requiring ankle fusion or an ankle replacement. Kim²¹ retrospectively assessed 31 patients who received varus wedge SMOT. In all patients, arthroscopic bone marrow stimulation was performed on the medial cartilage lesions. Secondary arthroscopy revealed progressive ankle degeneration in 13 (42%) patients, while follow-up after 1 year revealed a deterioration in both the VAS and AOFAS scores. For SMOT, cartilage lesions were identified as a risk factor for adverse outcomes.³⁰ Following the failure, the ankle will be sacrificed to improve function.

The statistical method applied in the present study tested the surgical effect of 20 research papers and found that the TAS, TLS and TT angles had been significantly improved, and the AOFAS and VAS pain scores were also significantly improved and with statistical significance. Accordingly, the effect of this surgery on varus ankle arthritis can be considered as positive. However, the procedure also presents common complications, primarily infection, thromboembolism, incision healing problems (including deep infection) and the delayed/non-healing of the fracture, pain and aggravated symptoms.³¹ Complications should be actively treated, based on symptomatic presentation. Early superficial infections can be improved by regular cleaning of the surgery area and dressing changes or the application of antibiotics. However, in the case of deep infections, these should be eradicated; this may require removing internal fixtures and performing surgical debridement to prevent infection.

The reasons for delayed fracture healing or non-healing (up to 22%) included anatomical reduction, periosteal dissection, whether the section was fixed, the osteotomy technique, the bone filling material that was used, and completing early functional exercise. Depending on the patient’s condition, secondary bone grafting surgery should be performed if necessary to accelerate healing of the fracture. If the pain or symptoms worsened and could not improve, final amendment surgery will be required, e.g. joint fusion or replacement.^24,32,33,34

Supramalleolar osteotomy is an ankle-preserving procedure that is conducted in cases of ankle arthritis; it has good short-and medium-term results in terms of pain relief, improved function, and restoring exercise ability, and can also delay and may even reverse the progress of OA. Concurrently, the procedure requires several surgical techniques with high technical requirements. Additionally, surgical complications are not uncommon and are accompanied by surgical failure and the need for amendment procedures.^12,21,35 The current authors considered SMOT to be a viable option when the following symptoms are present: (1) imaging manifestations of varus ankle OA; (2) force line adjustment before and after ankle arthrodesis or joint replacement; (3) distal tibial fracture malunion. Additionally, SMOT can also be used to correct ankle varus caused by ankle instability or congenital ankle varus.

In conclusion, SMOT of the ankle is an effective and reliable ankle-preserving surgery that can correct the displaced ankle force line and the ankle malalignment in the coronal plane. However, we should bear in mind that this procedure cannot relieve the ankle pain completely in varus ankles. Therefore, more high-level studies such as randomized control trials are needed in the future for a more precise assessment of the indications of the procedures to delay or reverse the progress of varus degeneration of the ankle.

Footnotes

Acknowledgements

We would like to express our gratitude to all those who helped us during the writing of this manuscript.

Authors’ contributions

Xue Wang, Conceptualization, Data curation, Project administration, Writing - original draft, Supervision, Writing - review and editing; Tiannan Chen, Conceptualization, Data curation, Writing - original draft, Writing - review and editing; Paerhati Wahafu, Formal analysis, Investigation, Writing - original draft, Writing - review and editing; Fei Li, Formal analysis, Investigation, Methodology, Writing - original draft, Writing - review and editing; Ayiding Xiahatai, Formal analysis, Investigation, Methodology, Writing - original draft, Writing - review and editing; Aikeremu Wufuer, Investigation, Methodology, Writing - original draft, Writing - review and editing; Yanan Tuo, Methodology, Resources, Software, Writing - original draft, Writing - review and editing; Bo Zhao; Methodology, Resources, Software, Writing - original draft, Writing - review and editing; Chengwei Wang, Investigation, Supervision, Validation, Visualization, Writing - original draft, Writing - review and editing.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of The Sixth Affiliated Hospital of Xinjiang Medical University. All participants signed an informed consent form for inclusion in the study.

Availability of data and materials

All data generated or analyzed during this study are included in this published article.

ORCID iD

Chengwei Wang

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