Indications,Associated Procedures,and Results of Ankle Plafond-Plasty for Varus Ankle Osteoarthritis: A Systematic Review and Meta-Analysis

Abstract

Backgrounds

Plafond-plasty is a joint-preserving procedure to treat varus ankle osteoarthritis (OA) with asymmetrical joint involvement. The aim of this systematic review and meta-analysis was to evaluate indications, different surgical techniques, associated procedures, and results of plafond-plasty in varus ankle OA and to analyze the level of evidence (LOE) and quality of evidence (QOE) of the included studies.

Methods

A systematic review of the literature was performed using MEDLINE, Embase, and Cochrane.

Results

Five studies evaluating 99 ankles were included. A non-rigid varus ankle deformity and an ankle OA Takakura stage 3b or less were the most recommended pre-operative indications. Meta-analysis showed a significant post-operative improvement in clinical and radiological parameters. Many associated surgical procedures have been reported, the most frequent being medial additional supramalleolar osteotomy and lateral ankle ligament reconstruction. The level of evidence and methodological quality assessment of the included studies showed an overall low quality.

Conclusion

Plafond-plasty seems to be a promising surgical option when managing varus ankle OA with asymmetrical joint involvement, extending the indications for joint sparing surgery. Additional associated procedures should be carefully evaluated case-by-case.

Levels of Evidence:

Keywords

joint-preserving surgery ankle arthritis varus ankle intra-articular osteotomy

Plafond-plasty seems to be a promising surgical option when managing varus ankle osteoarthritis with asymmetrical joint involvement, extending the indications for joint sparing surgery.”

Introduction

Post-traumatic ankle osteoarthritis (OA) is frequently asymmetrical, predominantly affecting the medial or lateral cartilage compartments.¹ This condition is often associated with persistent instability secondary to lateral ligament injury.^2,3

Asymmetric varus ankle OA is more common than its valgus counterpart.^4,5 This discrepancy can be attributed to the subtalar joint’s ability to better compensate for valgus deformities, and the association with ankle instability.^6,7

In case of varus ankle OA with asymmetrical joint involvement, joint-preserving realignment surgery is a promising therapeutic option for unloading the pathological articular area. Among the various surgical techniques available, medial opening-wedge SupraMalleolar Osteotomy (SMO) stands as the most frequently employed, constituting 65.5% of cases.⁸ Despite being an extra-articular procedure, SMO is effective in realigning the mechanical axis. However, long-term outcomes indicate a propensity for relapse in the medial articular depression.⁹

As a matter of fact, Lee et al¹⁰ stipulated that SMO is indicated for cases with minimal talar tilt (<7.3°) and a neutral or varus heel alignment in the presence of ankle OA. Similarly, Tanaka et al¹¹ recommended restricting SMO to cases of varus-type ankle OA classified as Takakura-Tanaka stage 2 to 3a. The talar tendency to relapse into the intra-articular defect may be due to the fact that SMO alone may not suffice to reorient the talus due to the persistence of the tibial plafond defect.^12,13

In 2009, Becker et al¹⁴ were the first authors to describe an intra-articular osteotomy for passive-correctable varus ankle OA cases exhibiting medial joint line indentation. This technique, termed “plafond-plasty,” aimed to realign the intra-articular surface by performing an osteotomy directed at the Center of Rotation and Angulation (CORA), which is identifiable at the level of the intra-articular step-off. The osteotomy procedure was carried out through a medial approach, guided by fluoroscopy, employing a single Kirschner (K)-wire as a plane guide (Figure 1).

Subsequently, numerous authors have adopted plafond-plasty for the correction of varus ankle OA, often in conjunction with soft-tissue procedures or other surgical interventions such as SMO or infra-articular osteotomies (IAOs).^12,15-18 The aim of this systematic review and meta-analysis was to evaluate the indications, various surgical techniques, associated procedures, and results of plafond-plasty in varus ankle OA and to analyze the level of evidence (LOE) and quality of evidence (QOE) of the included studies.

Materials and Methods

In June 2023, a systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review encompassed an exhaustive search of the MEDLINE, EMBASE, and Cochrane Library databases.

The search terms used were as follows: (((varus OR medial)) AND ((ankle) OR (tibiotalar OR tibio-talar)) AND (osteoarthritis OR osteoarthritic OR arthritis)) OR (plafondplasty OR plafond-plasty) OR (((intra-articular OR intraarticular) OR (supramalleolar) OR (distal tibial)) AND (osteotomy)). Inclusion criteria encompassed the following: (1) case series with (2) more than 12 months follow-up, (3) clinical and (4) radiographic outcomes of patients treated with intra-articular osteotomy procedures for (5) intra-articular varus ankle arthritis with (6) medial intra-articular defect, potentially associated with other surgical procedures. Exclusion criteria involved (1) case report or narrative reviews, (2) less than 12 months of follow-up, (3) intra-articular osteotomy performed to correct intra-articular defects in the sagittal plane, and (4) non-English language study.

Duplicates were systematically removed, and records not meeting the eligibility criteria were excluded during the initial screening. Studies involving animal models and in vitro investigations were also excluded, along with case reports. All articles identified as potentially relevant through the electronic search underwent full-text retrieval, supplemented by a meticulous hand-search of their bibliographies to capture any studies that might have been overlooked by the electronic search.

After retrieving the data, 2 independent reviewers meticulously screened the studies based on their titles, abstracts, and full-text articles, applying the aforementioned eligibility criteria. In cases where discrepancies emerged, a senior author was consulted to reach a consensus.

Level of Evidence and Methodological Quality Assessment

To assess the LOE, the criteria established by The Journal of Bone & Joint¹⁹ were employed.

The methodological QOE²⁰ was evaluated using the Modified Coleman Methodology Score (MCMS). Studies were categorized as excellent if they scored between 85 and 100 points, good if they scored between 70 and 84 points, fair if they scored between 55 and 69 points, and poor if they scored less than 55 points.

The potential for bias in the design, conduct, and analysis of each included study was systematically evaluated using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Series. This tool comprises a 10-item questionnaire designed to assess the methodological quality of studies.

Data Extraction and Evaluation

For each included article, the following data were extracted:

Study characteristics, including the assessment of the level of evidence and methodological quality.

Patient demographics.

Indications for plafond-plasty.

Surgical planning details.

Specific plafond-plasty surgical techniques employed.

Type of bone graft used.

Hardware characteristics used in the procedures.

Indications for any associated surgical procedures.

Clinical and radiological outcomes.

Complications.

All clinical scores were collected. The radiological parameters taken into account were the talar tilt angle (TTA), the tibial anterior surface (TAS) angle, and the tibial lateral surface (TLS) angle on the anteroposterior (AP) and latero-lateral weight-bearing images.

Talar tilt angle is measured on AP radiographs of the ankle. Talar tilt is the angle between the articular surface of the talar dome and the articular surface of the tibial plafond on a weight-bearing AP image.³ The tilt may be either varus or valgus.^21,22

Tibial anterior surface is the angle between tibial axis and distal tibial articular surface measured on a weight-bearing AP image.²² Tibial lateral surface is the angle between tibial axis and distal tibial articular surface measured on a weight-bearing lateral image.²²

In instances where complementary or supplementary angle measurements were reported, such as the tibial ankle surface angle (TSA), the corresponding TAS angle was calculated as needed. In cases involving subsequent ankle arthroplasty or ankle arthrodesis, it is important to note that the radiological parameters considered were those reported by the authors before proceeding with more definitive surgical procedures.

Statistical Analysis

Statistical analysis was conducted using the Jamovi project software (version 2.3, 2022), which was obtained from https://www.jamovi.org.

Eligibility for meta-analysis was determined based on clear reporting of the mean and standard deviation of the collected parameters within a given study. Meta-analysis was undertaken when applicable to 4 or more studies, employing the standardized mean difference as the outcome measure.

Results

The search yielded a total of 3836 results, and after applying the inclusion and exclusion criteria, 5 studies were ultimately included in the review (Figure 2).

All 5 of the included studies were LOE IV case series: 1 study had a prospective design, whereas 4 were retrospective.

Level of Evidence and Methodological Quality Assessment

The average MCMS was 52. Four of the studies were classified as “poor,” whereas 1 was classified as “fair”¹² (Table 1).

Table 1.

Modified Coleman Methodology Score.

MCMS questions	Authors
MCMS questions	Mann et al¹⁵	Hintermann et al¹²	Guo et al¹⁶	Xu et al¹⁷	Ma et al¹⁸
1. Study size—number of patients	0	4	4	5	0
2. Mean follow-up (months)	5	5	5	0	5
3. Number of different surgical procedures included in each reported outcome	0	0	0	0	0
4. Type of study	0	10	0	0	0
5. Diagnostic certainty	5	5	5	5	5
6. Description of surgical procedure given	5	5	5	5	5
7. Description of post-operative rehabilitation	3	3	0	3	3
8. Outcome criteria	2 + 6	2 + 2 + 6	2 + 2 + 6	2 + 6	2 + 6
9. Procedure for assessing outcomes	5	5 + 4	5	5 + 3	5 + 4
10. Description of subject selection process	5 + 5 + 5	5 +5 + 5	5 +5 + 5	5 + 5 + 5	5 + 5 + 5
Total	46	66	49	49	50

Abbreviation: MCMS, Modified Coleman Methodology Score.

The JBI Critical Appraisal Tools for the 5 studies are reported in the Table 2.

Table 2.

Joanna Briggs Institute 2017 Critical Appraisal Checklist for Case Series (CASP).

Quality assessment checklist:	Mann et al¹⁵	Hintermann et al¹²	Guo et al¹⁶	Xu et al¹⁷	Ma et al¹⁸
1. Were there clear criteria for inclusion in the case series?	✔	✔	✔	✔	✔
2. Was the condition measured in a standard, reliable way for all participants included in the case series?	✔	✔	✔	✔	✔
3. Were valid methods used for identification of the condition for all participants included in the case series?	N/A	N/A	N/A	N/A	N/A
4. Did the case series have consecutive inclusion of participants?	✔	✔	✔	✔	✔
5. Did the case series have complete inclusion of participants?	✔	✔	✔	✔	✔
6. Was there clear reporting of the demographics of the participants in the study?	✔	✔	✔	✔	✔
7. Was there clear reporting of clinical information of the participants?	✔	✔	✔	✔	✔
8. Were the outcomes or follow-up results of cases clearly reported?	✔	✔	✔	✔	✔
9. Was there clear reporting of the presenting site(s)/clinic(s) demographic information?	✔	✔	✔	✔	✔
10. Was statistical analysis appropriate?	✔	✔	✔	✔	✔
Yes (%)	60	60	80	80	80
Overall appraisal	Included	Included	Included	Included	Included

Patients’ Demographic

The total population of the 5 studies included 99 patients, for a total of 99 ankles. The weighted mean age was 46.81 years (range = 17-76 yrs). Fifty-four patients (54.5%) were male.

Across the studies, when reported, the most prevalent etiology for ankle OA was post-traumatic. The weighted mean post-operative follow-up time was 57.73 months (range = 14-134.4 months). Pre-operative and post-operative clinical scores are reported in Table 3.

Table 3.

Clinical Outcomes.

Authors	Clinical score	Pre-op values	Post-op values	Statistical significance
Mann et al¹⁵	AOFAS	46	78	Yes
Hintermann et al¹²	VAS	7.9 ± 1.3 (6-10)	1.3 ± 1.6 (0-7)	Yes
	AOFAS	49 ± 15 (36-68)	86 ± 12 (66-96)	Yes
Guo et al¹⁶	Olerud and Molander	56.4 (95% CI, 53.6-59.1)	7.0 (95% CI, 74.3-79.8)	Yes
	VAS	6.7 ± 0.8	3.1 ± 0.6	Yes
Xu et al¹⁷	VAS	5.5 ± 1.6	2.3 ± 1.9	Yes
	AOFAS	47.7 ± 15.7	75.8 ± 12.0	Yes
	SF-36	41.6 ± 14.0	67.7 ± 14.6	Yes
Ma et al¹⁸	AOFAS	56.2 ± 7.6 (45.0-74.0)	80.6 ± 4.6 (73.0-89.0)	Yes
	VAS	5.3 ± 0.6 (4.0-6.0)	2.7 ± 0.7 (2.0-4.0)	Yes

Abbreviations: AOFAS, American Orthopaedic Foot and Ankle Society; CI, confidence interval; VAS, Visual Analogue Scale.

Pre-operative and post-operative radiological parameters are reported in Table 4.

Table 4.

Radiological Outcomes.

Authors	Radiological parameters	Pre-op values (range) [95% CI]	Post-op values (range) [95% CI]	Statistical significance (P < .05)
Mann et al¹⁵	TAS	90° (82-97)	90° (86-102)	No
	TLS	84° (78-89)	84° (75-90)	No
	Varus tilt angle	18.7° (5-25)	10.7° (0-20)	Yes
Hintermann et al¹²	TAS	92.8° ± 3.5 (91-96)	88.2° ± 2.8 (86-91)	Yes
	TLS (complementary angle)	19.2° ± 8.5 (8-30)	11.9° ± 3.5 (7°-15)	Yes
	Varus tilt	19.4° ± 8.2 (6-32)	6.9° ± 3.9 (1°-12)	Yes
Guo et al¹⁶	TAS	87.1° ± 1.5 [85.6-88.7]	92.5° ± 0.7 [ 91.7-93.3]	Yes
	TLS	81.0° ± 2.6	82.5° ± 1.8	No
	TTA	2.5° ± 0.76 [1.74-3.15]	3.2° ± 0.7 [2.49-3.94]	Yes
Xu et al¹⁷	TAS	83.4° ± 2.6	90.7° ± 2.3	Yes
	TLS	77.5° ± 2.3	78.6° ± 2.2	No
	TTA	14.3° ± 5.0	5.3° ± 4.0	Yes
Ma et al¹⁸	TAS	84.1° ± 4.6 (70.7-91.2)	86.2° ± 2.6 (81.2-90.4)	Yes
	TLS	79.5° ± 7.3 (65.6-94.29)	79.8° ± 4.2 (73.3-86.8)	No
	TTA	15.5° ± 6.4 (4.6-29.3)	5.0° ± 2.9 (1.1-9.7)	Yes

Abbreviations: CI, confidence interval; TAS, tibial anterior surface; TLS, tibial lateral surface; TTA, talar tilt angle.

Surgical Indications for Plafond-Plasty

The main operative indication for 3 authors^12,15,16 was a manually correctable varus deformity, with 2 of them^12,15 verifying it through fluoroscopy.

Hintermann et al¹² additionally considered an intra-articular deformity greater than 5° and a deformity reducible to less than 2° of varus when applying valgus stress as surgical indications. Ma et al¹⁸ excluded rigid deformities without further specifications.

Guo et al¹⁶ employed an intra-articular step-off greater than 2 mm on pre-operative computed tomography (CT) scans as a surgical indication. All authors used the Takakura-Tanaka radiological classification for categorizing the severity of ankle OA based on weight-bearing ankle X-rays.¹¹ Hintermann et al¹² excluded patients with stage 3 and 4, Guo et al¹⁶ excluded patients with stage 3b to 4, whereas Mann et al¹⁵ and Ma et al¹⁸ only excluded patients with stage 4. Xu et al¹⁷ included only Takakura stage 3b patients.

Hintermann et al¹² also excluded patients with a bipolar subchondral cyst formation and with an ankle range of motion less than 30°.

Planning

Four authors^12,15-17 used pre-operative X-rays for surgical planning.

Ma et al¹⁸ employed pre-operative ankle CT scans, using the contralateral ankle, if it was deformity-free, or reference values reported in the literature (TAS = 90°, TLS = 80°) as target parameters for surgical planning. A patient-specific surgical guide was designed to match the bone surface.

Guo et al¹⁶ conducted a pre-operative CT scan to more accurately locate joint incongruities, whereas only Xu et al¹⁷ performed an magnetic resonance imaging (MRI) to assess cartilage condition.

Plafond-Plasty Surgical Technique

All the authors performed the intra-articular osteotomy through a medial approach.

The technique described by 3 authors^12,15,23 did not involve any violation of the articular cartilage. Two or 3 K-wires, differing from authors, were inserted in the subchondral bone, parallel to the joint surface, from medial to lateral, to prevent any cartilage damage during the osteotomy, as well as to act as a hinge during deformity correction. In addition, a K-wire was inserted aiming at the apex of the intra-articular deformity to act as a guide for the osteotomy plane. After performing the osteotomy, Hintermann et al¹² used a 2.5 mm K-wire–based distraction (Hintermann distractor, Integra, Plainsboro, New Jersey) to open the osteotomy site, until the desired correction was achieved according to the pre-operative plan. Mann et al¹⁵ used a wide osteotome for this purpose, whereas a lamina spreader was inserted into the cortical gap to temporarily maintain the correction. Xu et al¹⁷ did not specify the technique used to open the osteotomy gap (Figure 1).

In contrast, Guo et al¹⁶ performed a complete medial malleolar osteotomy to directly assess the intra-articular step-off, with the aim of reducing it and achieving articular congruity under direct visual inspection.

Ma et al¹⁸ applied a patient-specific instrumentation (PSI). The distal holes of the 3D printed surgical guide were used to direct the insertion of K-wires, preventing the saw blade from penetrating the joint and serving as a hinge during the correction process. Even the sawing depth was monitored by referencing the previously measured results from the pre-operative virtual simulation plan. Osteotomy gap opening was achieved by sequentially introducing 2 osteotomes until the K-wires aligned with the screw holes in the plate. Subsequently, the distracted wedge was maintained using a lamina spreader.

Type of Bone Graft

Hintermann et al¹² and Xu et al¹⁷ applied a wedged bone allograft, whereas Mann et al¹⁵ used allograft cancellous bone chips. Guo et al¹⁶ and Ma et al¹⁸ were the sole researchers to employ bone autograft from the iliac crest, although they also reported the use of bone allograft.

Hardware Characteristics

All authors used a locking plate to secure the osteotomy and act as a buttress to support the allograft. Only Mann et al¹⁵ employed 3 cannulated screws, inserted perpendicularly into the tibia, to stabilize the osteotomy in the initial 6 cases. Ma et al¹⁸ used a TI6AL4V alloy patient-matched plate designed to conform to the bone surface following the corrective osteotomy.

Indication for Associated Procedures

Different associated procedures were documented (Table 5).

Table 5.

Associated Procedures.

Studies	Associated procedures
Studies	Fibula osteotomy (indication)	Hindfoot osteotomies (indication)	Lateral ligament reconstruction (indication)	Medial ligament procedures (indication)	Tendon procedures (indication)	Ankle debridement (indication)
Mann et al¹⁵	\	- 12/19 (63%) calcaneal osteotomies(if persistent hindfoot varus after the plafond-plasty)	- 18/19 (94.7%)(indication not reported)	- 2/19 (10.5%) deltoid ligament releases(indication not reported)	- 3/19 (15.7%) peroneal tendon repairs- 1/19 (5.3%) posterior tibial tendon transfer(indication unreported)	- 14/19 (73.6%) debridement and cheilectomies(indication unreported)
Hintermann et al¹²	- 3/20 (15%) fibular shortening osteotomy- 2/20 (10%) fibular angulation osteotomy	- 2/20 (10%) calcaneal osteotomies(patients with remaining varus malalignment of the heel)	- 14/20 (70%)(indication not reported)	\	- 6/20 (30%) peroneus longus to brevis transfer(peroneus brevis tendon incompetence)	- (if talar neck osteophyte >2 mm with limited dorsiflexion)
Guo et al¹⁶	- 8/24 (33%)(post-traumatic malunited fibula or fibula restricting the deformity correction, typically for varus ankle deformity > 10°)	\	- 8/24 (33%)(if tibiotalar tilt on the varus stress > 9° or if anterior displacement on the anterior drawer test > 10 mm)	- 2/24 (8.3%) deltoid repair(if the medial clear space was >3 mm)	- 10/24 (41.6%) achilles tendon lengthening(if contracted with a neutral position heel and a flexed or extended knee)	\
Xu et al¹⁷	\	- 10/17 (58.8%) calcaneal osteotomies(indication unreported)	- 17/17 (100%)(When the talus could return to normal [position] during operation)	- Deltoid ligament release(If the varus talus could not return to normal)	\	- (if anterior distal tibial osteophyte impingement)
Ma et al¹⁸	\	\	- 9 /19 (47.4%)(indication not reported)	- 4/19 (21%) deltoid ligament release(If contracture of the medial structures)	- 2/19 (10.5%) posterior tibial tendon transfer- 1/19 (5.3%) Achilles tendon lengthening (if contracture)	- 19/19 (100%)(if an osteophyte > 2 mm on the talar neck or anterior fibula)

Specifically, 2 authors^12,16 always associated SMO. Hintermann et al¹² pre-operatively determined the second osteotomy site with respect to CORA. In cases where the TLS angle exceeded 15° and/or in instances of anterior extrusion of the talus leading to subsequent overloading of the anterior tibiotalar joint, the osteotomy was opened more anterior than posterior.

Guo et al¹⁶ located the SMO site 5 cm above the tip of the medial malleolus. The osteotomy was executed using a wide saw positioned perpendicular to the AP axis of the tibia, stopping 5 mm short of the lateral cortex to maintain bone stability.

Clinical and Radiological Outcomes

The American Orthopaedic Foot and Ankle Society (AOFAS) score was the most frequently employed patient-related outcome measure (PROM), in 4 out of 5 studies,^12,15,17,18 along with the Visual Analogue Scale (VAS) score.^12,16-18 Both the AOFAS and VAS scores exhibited significant improvement in all 4 studies following surgery (Table 3).

Radiological parameters consistently reported were the TTA, the TAS angle, and the TLS angle on the weight-bearing AP and latero-lateral images (Table 4).

Complications

Ma et al¹⁸ reported intra-operative hinge fractures in 15.7% of the cases (Table 6).

Table 6.

Complications.

Studies	Complications
Studies	Intra-operative complications	Hardware removal (cause)	Long-term related
Mann et al¹⁵	Unreported	Unreported	- 2/19 (10.5%) ankle arthrodesis after 7 and 36 months- 2/19 (10.5%) ankle replacement after 30 and 48 months
Hintermann et al¹²	- 0/20	- 5/20 (25%) after 12 months (local discomfort)	Unreported
Guo et al¹⁶	Unreported	- 10/24 (41.6%)(unreported)	- 1/22 (4.5%) ankle arthrodesis after 22 months- 1/22 (4.5%) ankle joint distraction after 15 months
Xu et al¹⁷	Unreported	Unreported	- 0/17 (0%)
Ma et al¹⁸	3/19 (15.7%) hinge fractures	- 2/19 (10.5%)(personal reasons)	- 0/19 (0%)

Further surgical treatments were required in 23.2% of the patients. When reported, hardware removal was described in 27% of the patients, whereas 3 cases of ankle arthrodesis, 2 cases of ankle arthrodiastasis, and 1 case of total ankle replacement were described (Table 6).

Statistical Analysis

A total of k = 4 studies were included in the VAS analysis. The average outcome differed significantly from zero (z = 4.5038, P < .0001) (Figure 3).

A total of k = 4 studies were included in the TTA analysis. The average outcome differed significantly from zero (z = 2.5188, P = .0118) (Figure 4).

A total of k = 4 studies were included in the TAS analysis. The average outcome differed significantly from zero (z = −4.9955, P < .0001) (Figure 5).

A total of k = 4 studies were included in the TLS analysis. The average outcome did not differ significantly from zero (z = −1.7619, P = .0781) (Figure 6).

Discussion

The aim of this systematic review was to evaluate the indications, various surgical techniques, associated procedures, and results of plafond-plasty in varus ankle OA.

Plafond-plasty technique was first described in 2009¹⁴ to treat intra-articular varus ankle deformities associated with instability. In 2013, Mann et al¹⁵ were the first to report positive results with plafond-plasty in conjunction with lateral ligament reconstruction. The pre-operative average TTA was 18°, which was considered an absolute contraindication for an SMO.

The indications for plafond-plasty remain a matter of controversy. Manual deformity correction was described as essential by 3 authors,^12,15,16 whereas Xu et al¹⁷ were mainly concerned with the intra-operative feasibility of correcting the deformity. However, Xu et al¹⁷ did not specify how to manage the deformity in case it could not be corrected during the surgical procedure, highlighting the necessity for surgeons with advanced skills when dealing with this challenging deformity. More specific pre-operative indications are required.

Patients with a Takakura stage 3b ankle arthritis, formerly considered unsuitable for SMO by Tanaka et al, were actually included in the very first case series published by Mann et al.¹⁵ However, eventually, all of these patients underwent ankle arthrodesis or arthroplasty. Hintermann et al¹² even included 2 patients with Takakura stage 4, whereas Xu et al¹⁷ applied this technique only in Takakura stage 3b patients and reported positive results. This was justified by the fact that not all of the stage 3b ankle arthritis evolve from stage 3a; sometimes, this condition may develop directly from stage 2, as is the case with a stage 3b Takakura ankle in which the lateral half of the TAS is within the normal range.

The majority of the authors agreed about the importance of preserving the tibial plafond cartilage. Two or 3 K-wires, inserted parallel to the subchondral bone, were deemed essential to avoid any cartilage damage and to act as a hinge during the osteotomy gap opening. Only Guo et al¹⁶ performed a complete medial malleolar osteotomy, in order to directly access and correct the impacted medial segment. No statistically significative differences in clinical and radiological outcomes were observed between the 2 techniques.

Several concomitant procedures were associated with plafond-plasty. An additional SMO was performed by 2 authors. Guo et al¹⁶ applied SMO to address associated mortise widening and varus malalignment, whereas Hintermann et al¹² used it to normalize the intra-articular load transfer by shifting the loading axis laterally at the level of the tibiotalar joint.

Calcaneal osteotomies were described in almost 25% of the patients. According to Hintermann et al,¹² calcaneal osteotomies would achieve a shift in the mechanical loading axis comparable to SMO. Nevertheless, shifting the Achilles tendon line of action laterally to the tibia’s mechanical axis would increase the leverage of the triceps surae with respect to the subtalar joint axis, thereby increasing the inversion force on the unstable talus. Furthermore, in vitro studies demonstrated that varus-deformed ankles primarily bear loading in the medial and anterior areas;^24,25 thus an SMO, with its 2-plane correction potential, may enhance the anterior coverage of the talus.

Many authors performed lateral ligament reconstruction, although clear indications were lacking. Only Guo et al¹⁶ provided a specific criterion, applying it when the TTA on varus stress exceeded 9° or when there was an anterior displacement of more than 10 mm in the anterior drawer test.

Ankle debridement was commonly performed to improve ankle range of motion. All authors except Xu et al¹⁷ highlighted the potential role of tibial-side osteophytes in joint retention, preventing ankle destabilization.

A significant post-operative improvement in the different PROMs, confirmed by the VAS meta-analysis, was reported by all the authors. However, 4 out of 5 patients who eventually underwent either arthrodesis or arthroplasty were excluded from the clinical scores analysis [15]. Regarding the remaining patient who underwent ankle fusion, the author did not explicitly specify whether he was included in the overall assessment of post-operative clinical outcomes [16]. Radiological data should be carefully analyzed. A significant reduction of the TTA was reported by all the authors except Guo et al,¹⁶ who described an increase from 2.5° to 3.2° post-operatively, still considerable within the physiological range. The combined results showed significant TTA reduction, confirming the plafond-plasty potentiality to reduce the talar tilt. Tibial anterior surface significantly improved in all studies except one,¹⁵ which already reported a pre-operative mean value of 90°. The combined results affirmed the effectiveness of plafond-plasty in restoring joint alignment to physiological values. It appears that the 2 authors^12,16 employing an SMO aimed for a slight overcorrection. Even the authors who applied only plafond-plasty achieved a neutral mechanical alignment, except for Ma et al,¹⁸ who reported an undercorrection (average post-operative TAS of 86.2°).

The only authors who reported a significant post-operative modification in the TLS were Hintermann et al.¹² As mentioned earlier, they were the only ones to apply a 2-plane corrective SMO in cases where TLS was less than 75° or there was anterior extrusion of the talus. In contrast, the other authors¹⁶ who performed SMO did not consider the sagittal plane joint orientation. The overall effect size analysis supported the conclusion that plafond-plasty did not have a significant impact on sagittal plane joint alignment.

This systematic review has certain limitations. The innovative surgical technique under analysis has been employed in a limited number of studies, often with a restricted number of patients. Moreover, it has frequently been combined with additional surgical techniques, thereby complicating the comparison between different authors. Nevertheless, the included studies display a relatively homogeneous population, showing numerous similarities in surgical indications, and presenting comparable pre-operative and post-operative radiological outcomes.

Many innovative surgical techniques initially emerge from case series, often retrospective, which inherently possess lower quality standards. However, the purpose of this systematic review was to shed light on these innovative surgical methods. This process aims to encourage the development of more sophisticated scientific studies that will offer a deeper understanding of the genuine potential inherent in this surgical technique.

In conclusion, the indications for plafond-plasty extend those of SMO, broadening the pool of eligible patients for joint-sparing surgery, even in cases of advanced-grade arthritis. Several associated surgical procedures have been described, the most frequent being medial additional SMO and lateral ankle ligament reconstruction, highlighting the complexity of this deformity and the necessity for advanced surgical skills in their treatment.

Despite numerous confounders and variations between studies, which made it challenging to adequately compare outcomes among the different procedures, meta-analysis demonstrated a significant improvement between pre-operative and post-operative clinical (VAS) and radiological (TTA, TAS) parameters, whereas TLS did not exhibit significant differences. This underscores the particular suitability of plafond-plasty for correcting coronal plane deformities.

Nonetheless, the overall LOE and methodological quality assessment of the included studies indicated generally low quality. Therefore, further research is necessary.

Footnotes

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.

Ethical Approval

Not applicable, because this article does not contain any studies with human or animal subjects.

Informed Consent

Not applicable, because this article does not contain any studies with human or animal subjects.

Trial Registration

Not applicable, because this article does not contain any clinical trials.

ORCID iDs

Simone Ottavio Zielli

Antonio Mazzotti

Elena Artioli

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