Minimal incision palatoplasty with or without muscle reconstruction in patients with isolated cleft palate: a cast and medical records analysis

Summary

Objectives

To compare the minimal incision (MI) technique with the minimal incision including muscle reconstruction (MMI) technique regarding surgical complications and dentoalveolar status at 5 years of age.

Subjects and method

A consecutive series of 202 Caucasian non-syndromic children (apart from Pierre Robin Sequence) born with isolated cleft palate between 1987 and 2007 and treated with MI (n = 78) or MMI (n = 102) palatoplasty at a mean age of 12.7 (SD = 1.43) months in Stockholm. Twenty-two patients did not fulfill the inclusion criteria. The patients were divided into two subgroups: clefts within the soft palate only (small cleft, n = 50) and clefts within the hard and soft palate (big cleft, n = 130). Dental relations, structure of the palatal mucosa, and height of the palatal vault at 5 (mean age 5.3, range: 4.4–6.9) years of age were studied using plaster models. Time for surgery, blood loss, complications in the immediate postoperative period, frequency of fistulas, and additional pharyngeal flap surgery were evaluated. Student’s t-test, chi-square test and 95 per cent confidence intervals were calculated.

Results

MMI compared to MI technique result in statistically significant increased operation time, less need for pharyngeal flap surgery, and to shallower palatal vault. Big clefts result in statistically significant increased operation time and need for pharyngeal flap surgery. Dental relations were the same in all groups.

Limitations

Retrospective single centre study, limited sample size, more than one surgeon.

Conclusions

The muscle reconstruction results in a reduced subsequent need for pharyngeal flap surgery, but to shallower palatal vault and demand for almost double operation time. The dental relations were the same in all groups.

Introduction

Several techniques for palatal closure have been developed for babies born with an isolated cleft in the palate (1, 2). The palate can be operated in a one- or two-stage procedure. When performing one-stage palatoplasty, the hard and soft palate is closed in one stage (3–6). When performing two-stage palatoplasty, the soft palate is closed in one stage and the hard palate in a second, later stage (7–9). The timing and technique varies between care centres and countries for both procedures.

Previous studies, regarding patients born with cleft lip and palate, have shown anterioposterior and transversal restriction of dentoalveolar development in surgically treated children with a cleft in the palate (10–13). Areas of bone left nude after the operation for secondary healing, developed scar tissue which was blamed for the restriction of the maxillary growth when closing the hard palate (14).

The minimal incision (MI) technique (15–17) is a one-stage palatoplasty which aimed to minimize areas of denuded bone. When this operation was compared with the Veau–Wardill–Kilner (VWK) technique studying dental casts at 5 years, MI provided better width at the upper jaw and a palatal mucosa with less scar tissue and pits (18). When investigating the medical records in the same study, blood loss was less using the MI method but time for surgery was increased for the MI technique in the extensive clefts. Concerning craniofacial development, no main differences were found between MI and VWK techniques studying lateral cephalograms at 5 and 10 years (19).

To improve speech development, a modification was introduced by reconstructing the muscles of the soft palate during the surgery; minimal incision with muscle reconstruction (MMI) technique (20). Whether this addition provides better speech was recently investigated and the MMI technique was not significantly superior to the MI technique, but had fewer velopharyngeal flaps. An important factor on quality of speech was the length of the cleft, as patients having a big cleft (extended in the hard palate) showed worse speech results (20). No data exists on dentoalveolar development with the MMI method.

As recent techniques seem more effective in minimizing alteration in growth and outcome in speech, one should take into consideration, before selecting the most effective operation, the complications during an operation as well. Methods vary significantly in required surgical time, in amount of blood loss, frequency, and severity of postoperative complications and in appearance of fistulas and possibility of later need for velopharyngeal flap surgery to improve speech.

To investigate dentoalveolar development in patients with clefts, various indexes have been developed (21). Today the most used indexes for isolated cleft palate are the Huddart and Bodenham (HB) scoring system (22) and its modification, the Modified Huddart and Bodenham index (MHB) (23, 24).

Only a few studies exist concerning patients born with isolated cleft palate as most investigations have focused on children born with cleft palate combined with cleft lip.

The aim of this study was to compare the MI technique with the MMI technique repair of isolated clefts of the hard and soft palate regarding surgical complications and dentoalveolar outcome at 5 years of age. The null hypothesis was that there is no difference regarding surgical complications and dentoalveolar outcome between the MI and the MMI technique at 5 years of age.

Material and methods

This study has been approved by the ethical committee in Stockholm nr 2011/1303–31/1.

Subjects

The material consisted of a consecutive series of 202 Caucasian, non-syndromic [apart from Pierre Robin Sequence (PRS)], children born with isolated cleft palate between 1987 and 2007 and treated with one of the two investigated palatoplasties (MI 1987–1996; MMI 1997–2007) in Stockholm (Figure 1). Twenty-two children had to be excluded due to late surgery (n = 1; age at the time of operation 39 months), few palatoplasties performed by a surgeon (n = 3; one patient by one surgeon performing MI and two patients by another surgeon performing MMI), death before the age of 5 years (n = 4), moved from the area (n = 8), and missing records (n = 6). The material to be analysed was from 180 children.

Medical records

Medical records of 180 patients were analysed retrospectively (Table 1). The patients were treated surgically using MI (n = 78) or MMI (n = 102) palatoplasty at a mean age of 12.7 (SD = 1.43, range: 6.8–18.5) months. According to the length of the cleft, confirmed during the operation, the material was divided into two subgroups: clefts within the soft palate only and a notch less than 3 mm in the posterior border of the hard palate (small cleft (1) MI n = 26 and MMI n = 24) and clefts within the hard and soft palate (big cleft (2) MI n = 52 and MMI n = 78).

Children in group MI were operated on by three surgeons and children in group MMI by two of the surgeons at the department (two main surgeons performed all the operations with the addition of one more at the MI surgical group).

Dental casts

A retrospective analysis of 128 dental casts at the age of 5 years (mean 5.3 years, 4.4–6.9 years, SD = 0.42), taken according to the national care system, was performed (Table 1).

Methods

Surgical procedure

Medical records presenting background and surgical data were analysed from birth until adulthood. Five factors were investigated in the medical records: time of surgery (minutes), blood loss (mm), complications in the immediate postoperative period (postoperative bleeding, respiratory problem, feeding problem), frequency of fistulas, and additional pharyngeal flap surgery. Complete data (n = 180) were available for all factors apart from time of surgery where 173 records were available (one missing from the MI2 group and six missing from the MMI2 group).

Dental occlusion

Plaster models at the age of 5 years were used for measuring sagittal, transversal, and vertical relations, structure of the palatal mucosa, and height of the palatal vault. A hundred and twenty complete casts were available for analysis. In eight cases (two for the MI1 and six for the MI2 groups), only casts of the upper jaw were available. For the palatal measurements the existing casts of the upper jaw were used, and for dental relations in the three dimensions clinical intraoral photos taken at the investigating period were used [very good reliability was previously shown concluding that imaging of dental casts provides a valid alternative for actual study models for rating dental arch relationships (25)]. Two researchers (ML, AK) measured the models and the mean values were used.

Sagittal relations

The occlusion was characterized as normal, postnormal, or prenormal (Angle classes I, II, or III, respectively). Migrations of teeth and missing teeth were taken into consideration and deviation of a whole cusp was considered. The overjet was measured in millimetres.

Vertical relations

The occlusion was characterized as normal bite, open bite (<0 mm), and deep bite (≥3 mm). The overbite was measured in millimetres.

Transversal relations

In the upper and lower casts, widths between the cusp tips of the deciduous canines (U3, L3) and mesiolingual cusps of the first (U4, L4) and second (U5, L5) deciduous molars were measured in millimetres. Then a contrast c = (U3 – L3) + (U4 – L4) + (U5 – L5) was formed.

MHB index

Scores according to the MHB index (23, 24) were recorded for the incisors, canines, first, and second deciduous molars. The scores for the incisors (anterior score; range −6 to 2), left canines and molars (left posterior score; range −9 to 3), right canines and molars (right posterior score; range −9 to 3), and all teeth (total score; range −24 to 8) were summed.

Height of the palatal vault

The height of the palatal vault was measured with the use of a digital calliper in the midline of the palate from a plane parallel to the occlusal plane at the distal surfaces of the first and second deciduous molars with the aid of a hard grid with the thickness of 2 mm having a hole for the end of the calliper (Figure 2). The width of the grid was subtracted from the measurements before statistical evaluation.

Structure of the palatal mucosa

The structure was recorded by the plastic surgeon (OL) as normal or minor scar tissue, a visible ridge of the vomer in the midline, or heavy scar tissue with pits according to Karsten et al. (18).

Statistics

For continuous variables, the student’s t-test was used for calculating statistical significance and 95 per cent confidence interval were calculated. For comparison of differences in proportions, a chi-square test was performed. Multiple regression analysis was performed for continuous variables and multiple logistic regression for binary variables, applying type of surgery, type of cleft, age at operation, and surgeon as covariables. Due to multiple testing, the significance level instead of 0.05 was set to 0.01.

The intra-observer method errors S_i were calculated by remeasuring 10 pairs of casts twice with a three weeks interval and applying the formula $Si=+−Σd22n$⁠, where d is the difference between the first and second measurement and n the number of double registrations (26). The inter-observer method errors were also checked using the intra class correlation coefficient for continuous data and the Cohen’s Kappa coefficient for categorical data (27, 28), varying between 0.926 and 0.988.

The statistical tests were performed using the software SPSS 23.0 (IBM Corp., New York, USA).

Results

Surgical procedure

Time of surgery

When comparing the operation time among the two surgical techniques, a statistically significant difference was found (P < 0.001) (Table 2). As a mean, more time was spent for the operation applying the MMI (mean = 103, range = 30–180, SD = 27 minutes) than the MI technique (mean = 61, range = 33–110, SD = 18 minutes) (Figure 3). Additionally a statistically significant difference was found (P < 0.01) between big clefts (mean = 89, range = 30–180, SD = 31 minutes) and small clefts (mean = 74, range = 33–139, SD = 29 minutes).

Blood loss, complications in the immediate postoperative period, and frequency of fistulas

Regarding blood loss, complications in the immediate postoperative period and frequency of fistulas, no statistically significant differences were found between the different surgical techniques or the length of the cleft (Table 2).

Additional pharyngeal flap surgery

It was found that pharyngeal flap surgery was performed from the age of three until the age of 9 years. Between small and big cleft groups, the big group exhibited increased need for pharyngeal flap operation (25.4 versus 4%; P < 0.001) (Table 2). Concerning the surgical techniques, the addition of muscle reconstruction decreased the need for pharyngeal flap (12.7 versus 28.2%; P < 0.01).

Dental occlusion

Sagittal, vertical, and transversal relations

Regarding sagittal, vertical, and transversal relations no statistically significant differences were found (Table 3).

MHB index

Regarding MHB index no statistically significant differences were found (Table 3).

Height of palatal vault

The height of the palatal vault distal to the first and second primary molars is presented in Table 3 with mean value, standard deviation, and range. At the statistical evaluation of the measurements of the height of the palatal vault, the MI cleft groups showed higher values (13.1 ± 2 mm) than the MMI cleft groups (11.8 ± 1.6 mm) only at first primary molars (P < 0.001), showing a higher palate at the area distal of the first deciduous molars.

Structure of the palatal mucosa

Regarding structure of the palatal mucosa no statistically significant differences were found (Table 3).

Regression analysis

When applying the regression analyses the same results as above were revealed concerning type of cleft and type of surgery. For the covariable age at the time of operation, no statistically significant result was found. For the covariable surgeon, the only difference found was at the additional flap surgery where one surgeon, who operated only the MI group, showed increased percentage (P < 0.05).

Excluding patients with PRS

When excluding the 24 patient with PRS (Table 1), the statistical evaluation provided the same statistically significant results as when including them in the material (Tables 2 and 3).

Discussion

In the Stockholm Craniofacial Team palatoplasty for an isolated cleft in the palate was after 1986 shifted from VWK to MI which provided better transversal development of the palate (18). In 1997, a muscle reconstruction was added to MI leading to a modification of the technique (MMI) aiming to improve the speech and dentofacial growth. In this study, surgical complications and dentoalveolar outcome at 5 years of age has been investigated after two different one-stage palatoplasties.

Treatment needs to be cost-effective for the individual patient and for the society. The time for surgery was almost double when the muscle reconstruction was applied and was increased for the big comparing to the small cleft group. This was an expected finding as it is a more extensive and detailed operation. When investigating the material of the MMI technique, there was found no difference in the operation time during the investigated period (11 years). After the shift of the used technique, the first palatoplasty was used at the end of the seventh month on an investigated patient with isolated cleft in the palate, allowing a learning period for the surgical technique of about 6 months. The palatoplasties were performed using magnifying loops × 2.5 and not using a microscope as instructed by Sommerlad (15, 16). This may influence the results as the use of higher magnificaction and better lighting may lead to a more precise dissection and reconstruction of the muscles of the soft palate. Extra surgical time may increase scar tissue and complications, and at the same time additional resources (surgeons, nurses, operation room, materials etc.) are spent. In our study, postoperative complications did not seem to differ. In the beginning, a new surgical technique always takes more time to perform, but still as the time needed to perform the MMI technique is double, it is a variable to take into consideration when evaluating the two techniques.

It is important to avoid formation of fistulas after palatoplasty as this requires a second operation and consequently more scar tissue. The percentage of fistulas after the two palatoplasties seems to be low and in agreement with another study presenting the existence of fistulas in 5 per cent of cases after Sommerlad palatoplasty in a Swedish population (29).

The medical records were investigated until adulthood concerning pharyngeal flap surgery, as it is vital to have all surgeries performed even after the age of 5 years when evaluating a surgical technique. As this is an investigation lasting over a long-time period decisions when to perform velopharyngeal flap may differ. There was a decreased need for pharyngeal flap surgery in the MMI as well as in the small cleft groups. These findings are in accordance with a previous study investigating the same techniques at a similar population concerning speech outcome where additionally no better results were found for MI or MMI technique concerning speech (19). At a recent investigation of two-stage palatoplasties, a decreased need for pharyngeal flap surgery was found in the small cleft group (9).

All children born with an isolated cleft palate meet a team consisting of a plastic surgeon who reconstructs the palate, a speech pathologist who follows and treats speech and an orthodontist who checks the occlusion and treats malocclusions. Comparing the MI with or without the reconstruction of the muscles of the soft palate, no differences were found concerning sagittal, transversal, or vertical relations on dental occlusion at 5 years. This means that the need for orthodontic treatment was the same for both groups at 5 years.

A goal for the plastic surgeon when performing a palatoplasty is to minimize scar tissue and to achieve a long well-functioning palate with a high palatal vault. In this study, a statistically significant higher palatal vault distal to the first deciduous molars was revealed at the MI group. That could be explained by the omission of muscle reconstruction and consequently the less repositioning of the muscles of the soft palate and the less stress of the soft tissue.

A normal Swedish material at the age of 5 years was investigated regarding the palatal height at the area distal to deciduous second molars. A mean height of 14.2 ± 1.9 (range 12–16) mm and 14.1 ± 1.67 (range 12.5–17) mm for boys and girls respectively was found (30). In the present study, the values for palatal height distal to deciduous second molars were very close to that study, especially for the MI group. This indicates that the findings from the palatal height, measured distal to deciduous first molars, with MMI technique is slightly shallower than those expected with normal growth. However, a big range was found in our material especially for the big cleft groups (Table 3). The structure of the palatal mucosa did not vary between the two studied palatoplasties. In a previous study, comparing the MI with the VWK technique, the MI method guided to less scar tissue and pits (18). No further improvement was found with the addition of the muscle reconstruction.

The application of the regression analysis provided the same results as when applying the t-test and the chi-square test. It elucidated that the age of the child at the time of the operation did not influence the results. The covariable surgeon did not seem to alter the results, apart from the need for additional flap surgery, where one of the surgeons was found to be an important factor (P < 0.05). That surgeon operated only the MI group which was found to need more velopharyngeal flap surgery. He also performed the least surgeries and it is not known if there was a selection of patients to be operated by the surgeons.

Twenty-four patients with PRS were included in the investigation of the medical records and sixteen in the measurements of the casts (Table 1). When excluding the children with PRS, similar differences were found among the groups as when including them. The results from this material were not influenced by the addition of children with PRS, or perhaps the fact that the smallest group (MMI) did not include any individual with PRS could have contributed to the similarity of the results. This is in accordance with a previous study comparing radiographically the growth at 5 and 10 years of children operated with VWK or MI surgical method (19).

This was a retrospective study retrieving data from a single centre collecting all the patients born with isolated cleft palate in the area (representing 1/4 of country’s patients) in a period of 20 years on a Caucasian population. All cases were operated by the same few surgeons (two same experienced main surgeons for both techniques with the addition of one more for the MI operation) following the same protocol. The material was investigated by the same investigators as in a previous article comparing medical records and casts between VWK and MI palatoplasties (18). The same surgeon went through the medical records. The same orthodontists measured all the casts. A new observer who was not involved in the treatment conducted the analysis. The application of strict criteria lead to a limited number of individuals and perhaps a larger sample of children may reveal hidden differences from the present study.

A question that arises is if 5 years is a good age to start to evaluate dentoalveolar development. It seems as this can be an appropriate age as the patients are still in primary dentition and no orthodontic intervention is involved. According to our findings, dentoalveolar outcome in 5 years of age was similar among the two surgical techniques, not providing any advantage of the addition of muscle reconstruction during the palatoplasty. A longitudinal follow-up is needed to further evaluate the two surgical methods. Additional data from a cephalometric investigation concerning dentoalveolar growth is needed to conclude if the muscle reconstruction is beneficial.

Conclusion

The modification of the MI technique, including muscular reconstruction of the soft palate, was introduced in order to improve speech. Concerning surgical complications and dentoalveolar outcome at 5 years of age, the muscle reconstruction has been shown to result in a demand for almost double operation time, a slightly decreased height of the palatal vault, but to a reduced subsequent need for pharyngeal flap surgery. The dental relations were the same in all groups. The null hypothesis that there is no difference regarding surgical complications and dentoalveolar outcome between the MI and the MMI technique at 5 years of age was rejected.

Conflict of interest

None to declare.

Acknowledgements

We would like to thank Liisi Raud Westberg, Stockholm Craniofacial Team for the illustrations, and Elisabeth Berg for her precious help in the statistical evaluation.

References