Accelerated versus standard Ponseti method for idiopathic congenital talipes equinovarus: a systematic review and meta-analysis

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One of the most common congenital deformities, congenital talipes equinovarus (CTEV) — commonly known as clubfoot — affects 1–6.8 out of every 1000 live births [1]. If left untreated, this pathology can result in stiffness, weakness, and chronic pain, condemning patients to permanent disability in the absence of a series of revision surgeries [2]. Early detection and holistic care are surely important contributors to the successful management of CTEV. However, its treatment has also evolved immensely since it was first mentioned circa 400 BC in a work of Hippocrates. Later, in 1743, the condition was recognized by Nicholas Andry, the father of orthopaedics, as “pedes equinus”, denoting the deformity’s resemblance to the foot of a horse. Plaster of Paris casts were the first advance in the nonoperative treatment of clubfoot, introduced by M. Jules Guérin in 1836 [3]. Surgical intervention was preferred at the time, because it was believed to achieve best therapeutic outcomes; however, the evidence from long-term follow-up showed disappointing clinical, radiographic, and kinematic outcomes. Furthermore, when performed in infants, corrective surgery often results in adolescent pain, functional deficits, and decreased strength [4]. The next breakthrough in the field was Ponseti casting, invented by Dr. Ignacio Ponseti in the 1940s as a conservative approach to clubfoot based on the fundamental pathoanatomy and kinematics of the deformity. After refining it for over a decade, Ponseti first published his conservative method in 1963, providing evidence that it yielded satisfactory outcomes in 90% of patients. The method — which can be applied as early as 1 day old — has been proven to realign clubfoot in infants while avoiding extensive and major surgeries. Ever since, weekly corrective manipulation and long-leg casting has been chosen as the standard care of treatment in the modern era, as the best option to gradually correct all components of clubfoot deformity [1, 3].

On the other hand, even though the Ponseti casting method is considered cost- effective and safe to perform, it takes approximately 4–5 weeks to correct all deformity components [2, 5], making compliance a challenge for patients with limited economic resources and difficulty accessing care [6]. Some literature has researched the efficacy of accelerated Ponseti casting, in which the plasters are applied identically to the original protocol but changed more frequently, usually about three times a week. However, few studies have reviewed these two procedures systematically, and none at all has compared them statistically using meta-analysis. Here, we aim to objectively compare the outcomes of the accelerated and standard Ponseti method for the CTEV pathology.

Materials and methods

The study design was a systematic review and meta-analysis of relevant randomized controlled trials as well as nonrandomized comparative studies. A systematic search was conducted from December 2018 to September 2019 to identify relevant studies through PubMed, Google Scholar, and Cochrane Database based on PRISMA guidelines (Fig. 1). The keywords used were: “Accelerated” AND “Standard” AND “Ponseti” AND (“Congenital Talipes Equinovarus” OR “Clubfoot”).

Fig. 1. Flowchart showing article selection based on PRISMA guidelines

Those studies were then manually scanned and reviewed by all authors according to the following inclusion criteria: (1) the accelerated and standard Ponseti methods were interventions under comparison; (2) the population included patients aged less than 3 years old with diagnosed CTEV/clubfoot; (3) at least one of the following outcomes was reported: post-procedure Pirani score, duration of treatment, number of casts needed, relapse rate, and/or tenotomy rate, (4) the study was published in English, and (5) applied a randomized controlled trial (RCT) or prospective cohort study (PCS) design. The exclusion criteria were: (1) neglected clubfoot (i.e. first treated after 3 years of age), (2) less than 6 months of follow-up, and (3) comorbid infectious disease or malignancy. Surgical treatment and conservative approaches other than accelerated and standard Ponseti were excluded from the analysis. Non-comparative, non-human in vivo and in vitro studies were also excluded. Table 1 presents the inclusion and exclusion criteria according to the PICO method (Population, Intervention, Comparison, and Outcome).

Table 1

PICO table describing inclusion and exclusion criteria

From each included study, data related to patient and study characteristics (e.g. age, sex, baseline Pirani score) and outcomes were extracted and aggregated. Continuous variables — post-procedure Pirani score, number of casts needed, and duration of treatment — were compared in terms of weighted mean difference (WMD). Dichotomous variables — tenotomy rate and relapse rate — were assessed in terms of odds ratio (OR) and 95% confidence intervals (CI). Calculations were performed using Review Manager (RevMan) software (Version 5.3. Copenhagen: The Nordic Cochrane Centre, the Cochrane Collaboration, 2014). A fixed-effect model was used when heterogeneity (I2) was < 50%, whereas a random-effect model was used when it was > 50%.

Results

A total of seven studies (324 patients, 408 feet) were included in the meta-analysis. Five studies were RCTs (Level I evidence), while 2 articles were PCSs (Level II evidence) (Table 2). Critical appraisal of all studies based on the Joanna Briggs Institute Scoring System showed that none failed to meet more than two validity criteria (Table 3).

Table 2

Studies included in the analysis

Table 3

Critical appraisal of all studies included

The sample size for standard Ponseti was 207 feet, while for accelerated Ponseti it was 201 feet. The age at presentation seemed similar between the two procedures, ranging from 7–161 days for standard Ponseti and 14–182 days for accelerated Ponseti. Males were more commonly affected than females; deformity was more commonly unilateral than bilateral. In all studies, casts were uniformly changed once per week in the standard interventions, while the interval adopted for accelerated Ponseti varied from every 2 days to every 5 days. Pre-procedure Pirani score seemed comparable between the two procedures; the follow-up period ranged from 6 to 71 months. Sample characteristics and outcomes of the included studies are tabulated separately in Table 4–6.

Table 4

Patient characteristics

Note. F, female; M, male; Right, right foot; Left, left foot; Bilateral, bilateral deformity; Unilateral, unilateral deformity; NA, not available.

Table 5

Outcomes analyzed (1)

Table 6

Outcomes analyzed (2)

Note. NA, not available.

Of the five outcomes analyzed, accelerated Ponseti was statistically superior to standard Ponseti in terms of mean duration of treatment (24.25 days v. 41.54 days, p < 0.00001; Fig. 2). In addition, it achieved comparable efficacy to the standard protocol in terms of post-procedure Pirani score (1.01 v. 0.87, p = 0.19; Fig. 3), total number of casts needed (4.94 v. 5.05, p = 0.76; Fig. 4), tenotomy rate (73.29% v. 65.27%, p = 0.07; Fig. 5), and relapse rate (27.72% v. 25.23%, p = 0.56; Fig. 6).

Fig. 2. Forest Plot analysis for duration of treatment

Fig. 3. Forest Plot analysis for post-procedure Pirani Score

Fig. 4. Forest Plot analysis for number of casts needed

Fig. 5. Forest Plot analysis for tenotomy rate

Fig. 6. Forest Plot analysis for relapse rate

Discussion

Since its invention in the 1940s by Dr. Ignacio Ponseti, serial Ponseti casting has been widely adopted around the world as a non-operative approach to the treatment of clubfoot. The weekly frequency of manipulation and cast application allows the correction — as well as collagen relaxation and atraumatic remodelling of joint surfaces — to take place gradually, while reducing the risk of fibrosis associated with surgical release. Ponseti demonstrated that if this correction method is applied within the first month of life, the need for posterior medial and lateral release can be avoided in up to 95% of cases. Some reports claim its success rate is lower in older infants (7 to 10 months old) than in younger ones; however, contradictory evidence was reported by Alves, et al. (2009), who showed similar relapse rate and other outcomes regardless of the age of patients at initial treatment [10, 11].

To stretch the ligaments and gradually correct the deformity, the foot is first manipulated to correct each component in a specific sequence, following the acronym “CAVE” (cavus, adductus, varus, equinus), then immobilized by a plaster cast extending from the toes to the upper third of the thigh, with the knee at 90° flexion. The cast is traditionally changed weekly; five or six cast corrections are usually sufficient to correct most clubfeet.

In a sprawling and geographically diverse country like Indonesia, travelling long distances can be bothersome for some patients for social and financial reasons, especially those living in remote areas. Distance to provider is a barrier to healthcare access and a leading cause of treatment failure. In this case, accelerated Ponseti casting should be considered as a solution. Children and their families do not need to travel long distances frequently back and forth for each cast change; instead, they can stay in local accommodation for a shorter period, therefore reducing their overall financial burden. These benefits are hoped to improve patients’ compliance and maximize functional improvement [3, 10].

The Pirani scoring system is one of the most commonly used methods for assessing deformity severity in clubfoot. It includes six components: posterior crease, emptiness of the heel, equinus rigidity, medial crease, curvature of the lateral border of the foot, and the reducibility of the lateral talar head. Each item is given a score of 0 for no abnormality, 0.5 for moderate abnormality, or 1.0 for severe abnormality, and summed for a total score (Total Foot Score: TFS) of 0–6 points, where a higher score indicates severer deformity. Furthermore, TFS is divided into two subtotal scores (range: 0–3 pts), respectively representing contracture of the midfoot (Mid Foot Score: MFS) and hindfoot (Hind Foot Score: HFS). MFS is the sum of item scores for medial crease, lateral curvature and reducibility of talus, whereas HFS is the corresponding sum for posterior crease, empty heel and rigid equines [12, 13]. Based on this meta-analysis, we can conclude that accelerated Ponseti casting can achieve comparable Pirani scores — and therefore reductions in deformity severity — to standard Ponseti casting.

Other advantages that practitioners should note when considering the accelerated approach are its lower risk for osteopenia and pressure sores related to prolonged casting. Even though it mostly resolves naturally within a few months after plaster removal, osteopenia has been documented after immobilization in above-knee plasters in the treatment of clubfoot. Patients may benefit from the overall shorter duration of treatment of accelerated casting by avoiding or limiting harms from this condition [7, 14]. Pressure sores, skin rashes, and disuse atrophy are other commonly found complications of prolonged casting that can be minimized by the accelerated protocol [1]. The frequent changing of plasters allows practitioners to routinely monitor for these and other possible complications, while at the same time keeping the plaster dry and clean to avoid correction loss due to accumulated moisture [7].

Before the hindfoot is corrected to a neutral position, if full dorsiflexion is not possible with stretching alone (for example, in cases of atypical clubfoot), a tenotomy is sometimes required to ‘unlock’ the os calcis from beneath the talus. In such cases, further stretching and casting are performed afterwards to achieve complete correction [15]. In their protocol, Mageshwaran et al. (2016) performed tenotomy when cavus, adductus, and varus were fully corrected but ankle dorsiflexion remained less than 10° above neutral after serial casting; before doing so, the authors made certain that abduction was adequate [6]. Even though Achilles tenotomy can be performed surgically or percutaneously, all studies included in this meta-analysis chose the latter option, which is superior to open surgery in preventing scarring due to its simpler and sutureless technique [16]. In our study, tenotomy rate between the two procedures does not differ significantly, though it is slightly higher in accelerated Ponseti method. This might be due to slightly higher initial Pirani score in accelerated group as mentioned by Mageshwaran et al. (2016) [6], as well as the difference in the severity of deformity or technical error in casting as mentioned by Elgohary et al. (2015) [5].

We observed comparable relapse rates between the two procedures in this meta- analysis, over a wide range of follow-up periods from 6 to 71 months. However, some studies have also linked this outcome to bracing compliance and the educational level of patients’ families. Relapse risk can be prevented by stressing the importance of bracing to family members during regular follow-up, while at the same time clearly teaching them how to correctly fit the orthotics and supervising as they practice their first attempts [6, 17, 18].

This study has several limitations:

(1) Some of the analyses had high study heterogeneity, especially for Pirani score and number of casts needed.

(2) Due to the limited number of available studies, it was decided to include patients who were older than 1 month of age (but not “neglected”). This may bias our results, as some literature has claimed that the age of presentation can affect outcome.

(3) Cast-changing interval was highly variable among the studies included, ranging from every 2 to 5 days, which might have increased heterogeneity in our statistical analysis.

However, this study also has several advantages:

(1) To our knowledge, it is the first meta-analysis on the relative merits of the accelerated versus standard Ponseti method.

(2) The literature included in this study consisted of higher levels of evidence (Level I or II); five of the seven were well-designed RCTs. This feature supports the accuracy and reliability of our meta-analysis.

(3) Outcomes were thoroughly assessed, in terms of several outcome measures, offering more-nuanced implications for the different dimensions of clubfoot therapy.

This study could serve as an influential bridge to future research with larger sample sizes and less heterogeneity, as well as analysis of the financial benefits afforded by the reduced treatment duration: namely, lower travel expenses due to shorter and fewer stays in accommodations near treatment centres away from patients’ homes.

Conclusion

The present meta-analysis supports the conclusions that the accelerated Ponseti method can achieve comparable efficacy to the standard technique in terms of post-procedure Pirani score, number of casts needed, tenotomy rate, and relapse rate. Furthermore, accelerated Ponseti seems to offer shorter duration of treatment, increasing the likelihood of patient compliance.

Additional information

Source of funding. The authors did not receive any funding

Conflict of interests. Authors declare no explicit and potential conflicts of interests associated with the publication of this article.

Author contributions. Both authors performed literature selection to be involved in the study, performed systematic and meta-analysis, and discussed with each other to sort out differences, formulate discussion and conclusion.

All authors made a significant contribution to the research and preparation of the article, read and approved the final version before publication.

Acknowledgements. The authors would like to thank Mark Streer of “Uni-Edit: English Editing and Translation Service” for assistance with revision and manuscript preparation.

About the authors

Sherly Desnita Savio

Author for correspondence.
Email: sherlydsavio@gmail.com
ORCID iD: 0000-0003-4269-1156

MD, Orthopaedic Resident, Orthopaedics and Traumatology Department, Faculty of Medicine Udayana University, Sanglah General Hospital

Made Agus Maharjana

Email: agusmaharjana@yahoo.com
ORCID iD: 0000-0002-3953-2798

MD, Consultant of Orthopaedics and Traumatology Department, Faculty of Medicine Udayana University, Sanglah General Hospital

References

Supplementary files

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2. Figure: 6. Forest diagram of the results of the analysis of the number of relapses

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3. Fig. 1. Flowchart showing article selection based on PRISMA guidelines

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4. Fig. 2. Forest Plot analysis for duration of treatment

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5. Fig. 3. Forest Plot analysis for post-procedure Pirani Score

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6. Fig. 4. Forest Plot analysis for number of casts needed

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7. Fig. 5. Forest Plot analysis for tenotomy rate

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8. Fig. 6. Forest Plot analysis for relapse rate

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9. Critical appraisal of all studies included

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