10.25241stomaeduj.2023.10(1-4).art.6 – STOMATOLOGY EDU JOURNAL

The objectives of this 5-year retrospective study were to evaluate the indications and risk factors for the removal of titanium miniplates following osteosynthesis in orthognathic surgery.

Methodology

The records of 1252 consecutive patients (5779 plates) undergoing orthognathic surgery between January 2015 and July 2020 were reviewed. The risk factors considered in the study included age, sex, smoking habits, jaw movement and rotation, third molar removal at the time of the surgery, plate location and plate manufacturer.

Results

681 patients had bimaxillary surgery, 466 patients had a bilateral sagittal split osteotomy and 105 patients had a Le Fort I osteotomy. In total, 341 genioplasties were performed. 78 patients required plate removal (6,2% of all patients). A total of 107 plates were removed (1,9% of all plates). All patients had their plates removed within a year. Infection is the most important reason for plate removal in 71,8% of the patients (56 patients, 68 plates). 12 patients had their plates removed because of subjective complaints (15,4%, 20 plates). The average time between surgery and plate removal was 73 days.

Conclusion

Age, thirdmolarremovalduringsurgery, mandibleplatesandmandibularrotationweresignificant predictors for plate removal. These factors should be taken into consideration for every orthognathic patient. This study reports a low incidence of plate removal compared with previously published reports.

Keywords: Orthognathic Surgery; Titanium miniplates; Plate removal; Risk factors; Infection;

^TF4-1Abbreviations: BM = bimaxillary surgery; BSSO = bilateral sagittal split osteotomy; LF1 = Le Fort 1 osteotomy; G = genioplasty.

1. INTRODUCTION

Orthognathic surgery is a common procedure for correcting dentofacial anomalies and occasionally for obstructive sleep apnea. Nowadays, fixation of these osteotomies with miniplates and screws is common practice and replaced intermaxillary fixation. Internal fixation with titanium plates and screws has been accepted as the gold standard in orthognathic surgery to achieve rigid immobilization of bony segments [1]. When the technique with miniplates was introduced, postoperative removal of the plates and screws after bone healing was standard procedure [2]. However, the introduction of titanium miniplates has led to the routine removal of miniplates becoming obsolete in Belgium and many parts of the world so plates are only removed in case of complications [3,4]. These complications may vary: plate infection, plate exposure, plate fracture, screw loosening, postoperative instability, malunion at the fracture lines or subjective complaints (Fig. 1).

A meta-analysis showed that 13.4% of the patients required the removal of at least one titanium plate after orthognathic surgery [5]. To date, risk factors for plate removal are not clear and are varying according to different studies. Some of these factors, such as perioperative removal of third molars, mandibular rotation or plate manufacturer have not been analyzed. Furthermore, the existing studies had small sample sizes, and some were only including single jaw osteotomies [6–8]. Standardized criteria to document reasons and risk factors for plate removal are lacking. The objectives of this study are to investigate the incidence and reasons of postsurgical removal of titanium fixation plates in orthognathic surgery, identify the risk factors that result in plate removal and compare it with the rates and reasons described in the literature.

METHODS AND MATERIALS

2.1 Data collection and study design

The case records and radiographs of 1252 consecutive patients who had undergone routine orthognathic surgery between January 2015 and July 2020 for dentofacial anomalies were reviewed retrospectively. All patients had undergone either a bimaxillary, Le Fort I, or bilateral sagittal split ramus osteotomy (BSSO) with or without genioplasty performed by 1 of the senior staff members of the Department of Oral and Maxillofacial Surgery at AZ Nikolaas in Sint-Niklaas, Belgium. Ethical approval for this restrospective analysis was given by the institution’s Ethical committee. The same operative technique was applied in alternating surgical teams with two surgeons. Patients were excluded if they had undergone jaw surgery for other reasons than dentofacial anomalies, i.e. trauma, reconstruction or tumor- related. No patients with craniofacial syndromes were treated in our department. All fixation plates used were manufactured by either DePuy Synthes (MatrixORTHOGNATHIC, DePuy Synthes, Zuchwil, Switzerland) or Titamed (BETA-system, Titamed, Kontich, Belgium). For the genioplasties KLS Martin plates were used (KLS Martin Group, Tuttlingen, Germany). All plates were inserted and, if necessary, removed intra-orally. The main outcome variable was the removal of osteosynthesis material. Secondary outcomes were indication for plate removal and risk factors. The patients’ records were reviewed for patient demographics including age, gender and smoking status. The following intraoperative variables were evaluated: hardware manufacturer, plate size and presence of maxillary or mandibular third molars during surgery. When a difference in plate size of more than two mm was noted between the mandibular plates, the BSSO was categorized as rotation (to correct the asymmetry). The following parameters were recorded for patients requiring plate removal: indication for removal, location (upper/lower jaw, left/ right side), simultaneously removal of third molars during the time of surgery, the time between insertion and removal and size of the plate (as an indicator for advancement). A minimum follow-up period of 6 months was used to be included in the study. No patients were lost in the follow-up. Furthermore, this retrospective study was conducted in compliance with the Helsinki Declaration guidelines.

2.2 Operative technique

Bilateral sagittal split osteotomies were performed according to the Hunsuck modification of the Obwegeser–Dal Pont method [9]. Le Fort I osteotomies were performed according to the method described by Bell [10], and genioplasties were performed according to the method described by Chan [11]. Our surgical protocol consists of four plates for maxillary fixation (two L-shaped fixation plates lateral to the nose aperture, and two L-shaped fixation plates at the zygomaxillary buttress) and two plates for the mandible. Each plate was fixated with 4 mono-cortical screws. Genioplasties were fixated with one chin plate and 4 monocortical screws. Third molar removal was performed at least 6 months preoperatively to achieve sufficient bone healing, or they were removed during the osteotomy. Suturing was performed with polyglactin (Vicryl 3–0) for the mucosa and Vicryl 4-0 for the periosteum of the maxilla. All patients received perioperative intravenous antibiotics (cefazolin sodium 1.0 g) and during the postoperative period (cefazolin sodium 1.0 g every 12 h); antibiotics were not continued after being discharged from hospital. Also, all patients were administered intravenous steroids (methylprednisolone 125 mg) during surgery and a second and third dose at 12h and 24h post- surgery respectively. No patients were discharged with steroids. An intra-oral drain was inserted at the surgical sites of the mandible until the first postoperative day to minimize postoperative hematoma. Generally, patients were hospitalized for 1 day. Light guiding elastics on surgical hooks were used for one week postoperatively in most cases. Guiding elastics during the next follow-up period were only used if the occlusion deviated from the desired result. No occlusal splints were used. Normal chewing function was allowed after six weeks when bone healing was completed. Follow-up appointments were planned after 1 week (with radiological assessment), 3 weeks, 6 weeks and after completing the orthodontic treatment. From then on, follow-up appointments were only planned on the patients’ request.

2.3 Indications for plate removal

In our department the decision for postoperative plate removal was based on the patient’s complaints regarding discomfort and on clinical appearance such as infection, inflammatory reaction, or plate exposure. An infectious reaction was considered to be present whenever wound dehiscence over the plates, granulation tissue at the plate site, or an intraoral fistula with pus at the plate site was observed (Fig. 2). Infection was a clinical diagnosis; no wound cultures were obtained. Pain, tenderness over the plates and sensory disturbances were categorized as clinical irritation. When an immediate postoperative occlusal instability or relapse was noted the patient was planned for redoing the surgery and the removed plates were included in this study. Surgical removal of plates in the upper and lower jaw was performed on the side with infection or clinical irritation only. Most plate removals of the mandible were performed under local anesthesia or procedural sedation instead of general anesthesia. This resulted in reduced hospitalization time and costs. For the removal of plates in the upper jaw general anesthesia was used for the patients’ comfort.

2.4. Statistical analysis

The data were collected into a database using Microsoft Excel (Microsoft Inc., Redmond, WA, USA). Statistical analyses were performed using the statistical package SPSS (IBM SPSS Statistics for Windows, version 25.0, (IBM Corp., Armonk, N.Y., USA)). For the descriptive analysis, percentages were used for qualitative variables and associations were tested by the t-test and Pearson chi-square test. P-values of <0.05 were considered statistically significant.

3. RESULTS

During the 5-year period of the study, 1252 patients underwent orthognathic surgery at Vitaz Hospital. This group consisted of 501 males and 751 females (giving a 1–1.5 male-female ratio, 40% vs 60%). At the time of the osteotomy, the age range was 13–64 years with an average of 21.8 years (Fig. 3). 681 patients had bimaxillary surgery, 466 patients had a bilateral sagittal split osteotomy and 105 patients had a Le Fort I osteotomy. The average follow-up interval for the included patients was 344 days.

In total, 341 genioplasties were performed (Table 1). It was calculated that a total of 5779 plates were placed out of which 3144 were in the maxilla and 2294 in the mandible.

For each genioplasty one plate was used, in total 341 plates. The average time of hospitalization was 1.08 days (range 0-4 days). 78 patients required plate removal (6.2% of all patients) of which 54 were female and 24 were male (7.2% of all female patients and 4.8% of all male patients (P=.085, table 2). A total of 107 plates were removed (1.9% of all plates). 69 patients required mandibular plate removal (83 plates – 3.6% of the mandibular plates) and 9 patients required plate removal from the maxilla (24 plates – 0.8% of the maxillary plates). The plate removal ratio between the lower and the upper jaw was statistically significant (P<.001). None required removal of plates from both jaws, none of the chin-plates were removed. Removal of plates was slightly more common on the left side: 45 patients had plates removed on the left side (lower or upper jaw) and 33 patients had plates removed on the right side (P=.171). None of the patients who went through plate removal had any significant underlying medical conditions that might predispose plate removal (i.e. diabetes mellitus, steroid therapy). The mean age of the patients who had plates removed was 24.8 years, versus 21.6 years for the patients without removal of plates (Table 2). The patients were categorized into the following age categories: 18 years and younger, between 18-29 years old, and 30 years and older. Plate removal incidence in the oldest group is significantly higher compared to the other two age categories (P<0.001).

The mean time to removal of metalwork was 73 days (range 6–330 days). No plates were removed before bony healing was completed, except for cases with postoperative instability (8 cases). Hence, all patients had removal within a year of placement (Fig. 4).

Infection was the most important reason for plate removal in 71.8% of the patients (56 patients, 68 plates). 12 patients had plates removed because of subjective complaints (15.4%, 20 plates). Of these 12 patients, the reason for removal was discomfort in 7 patients (9%, 13 plates), and palpability of the plates in 5 patients (6.4%, 6 plates).

Noteworthy: 11/12 patients with subjective com- plaints were female. In 8 cases the plates were removed due to postoperative occlusal instability or relapse (10.3%, 12 plates). 1 patient wanted removal because of moving abroad (1.4%, 4 plates), and 1 patient had plate removal because the adjacent teeth needed extraction (1.4%, 4 plates). No plate fractures were observed (Fig. 5).

In 930 patients the manufacturer was Synthes (74.3% of the patients, 4014 plates), 322 patients received Titamed plates and screws (25.7% of the patients, 1424 plates). 23 of the 78 patients required Titamed plate removal (29.5% of the patients with plate removal), 55 Synthes plates (70.5%). A total of 74/4014 Synthes plates were removed (1.8%) and 33/1424 of the Titamed plates (2.3%, P=0.432) (Table 3).

Simultaneously, removal of the third molars happened in 214 of 1252 patients (17.1%). Of these 214 patients, 21 needed post-surgical plate removal (9.8%). Plate- removal incidence in patients without third molar removal is 5.5% (P=.017).

The length of the plates in the mandible was used as an indicator for the advancement of the lower jaw. A BSSO with plate lengths of 8 mm or less was considered as a small advancement (574 patients), while plate lengths of more than 8 mm were considered as a big advancement (573 patients). In the patient group with a small advancement 31 patients needed plate removal, 41 patients in the big advancement group (P=.221). Of the 1147 patients with a lower jaw osteotomy, 86 patients had a rotation of the mandible. Patients with a rotation of the lower jaw had more plates removed than patients with a symmetrical osteotomy (P=.010).

According to the patient files 47 out of 1252 patients smoked (3.8%). Only 2 of these 47 patients had plates removed (2.6%, P=.965). Smoking was more frequent among female patients (70.2%), versus 29.8% for male patients.

DISCUSSION

This retrospective study reports the incidence and reasons for titanium miniplate removal in a series of 1252 consecutive orthognathic surgery cases. The reasons and risk factors for plate removal were investigated by different authors in the past, however they are still subject to debate [4,6,7,12]. In previous studies the patient population consisted of patients who had undergone plate fixation for an osteotomy or facial trauma. Only a limited number of studies investigated solely orthognathic patients. An overview of the papers that have been published about plate removal in orthognathic surgery is shown in table 4. Orthognathic patients received planned surgery and the surgical environment is well controlled and standardized, so we excluded all other types of surgery with internal plate fixation. Our sample distribution is the same as in the literature with more female patients than male patients: 60% in our study, on average 64% in the literature [5]. The average age of surgery (21,8 years) is lower in comparison to other studies [4,13– 15]. The incidence of plate removal after orthognathic surgery varies widely in the literature, ranging from 1% to 27.5% [4,13]. This study showed an incidence of 6.2% plate removal, which is lower than the average of 13.4% in orthognathic patients [5]. 1.8% of the plates were removed, however in literature 9.7% of the plates required removal [5]. A possible explanation is that some surgeons will remove plates bilaterally when only one side is symptomatic, therefore increasing the percentage of plates removed.

More mandibular plates were removed than maxillary plates (3.5% versus 0.5%). This is similar to other studies in the literature and is possibly due to better blood supply and thinner cortical bone of the maxilla and greater masticator forces on the lower jaw, however this is not scientifically proven. We found that in many of the patients in whom the plate was removed in the lower jaw, the screw in the proximal segment closest to the osteotomy was often loose and associated with a fragment of loose bone (Fig. 6).

Screw loosening can be explained due to ischemic necrosis of the cortical bone when the screw is inserted too close to the superior border, and this particular screw is subject to the greatest mandibular forces [16, 17]. Another explanation is that the manual tightening of this first screw was too tight, resulting in microfractures around the osteotomy. In cases of interference of the lingual bone plate of the proximal segment, due to mandibular rotation, a secondary lingual osteotomy was performed to avoid strain on the plates. Plate removal occurred more on the left side than on the right side. According to Falter et al. righthandedness of the surgeon could be a reason [4]. We did not notice a difference in plate removal between the right- and left-handed surgeons because the surgeon sitting on the right side of the patient operated the right side and vice versa. Women presented a higher rate of plate removal than men: 91% of the patients with plate removal due to subjective complaints were female. This was also noted in a similar study, suggesting that higher body awareness in women is attributed to this difference [18].

The exact movements of the jaws were not available in all medical records. Therefore, we used the length of the plates as an indicator for jaw movement. No statistically significant difference was found between the different plate lengths and the risk for plate removal, similar to the previous studies [4,6,7]. However, patients with a mandibular rotation to correct the asymmetry showed significant more risk for plate removal than patients with a symmetrical osteotomy of the lower jaw. Rotational forces can result in more strain on the plate.

Most of the literature reported infection as the major reason for plate removal [4,6,7,12]. One possible reason for the infection rate in our study could be the use of intraoral drains. To prevent hematoma, in our unit we use intraoral drains which are removed on the first postoperative day. The use of drains at the surgical sites of the mandible is controversial, because there is a temporary connection between the oral cavity and the osteotomy segments, which conceptually can result in higher risk of plate infection.

In this study plates were removed relatively early with a 73-day average. It is hypothesized that early infections leading to removal of the plates within the first months may be associated with the distance to the incision [1]. All of the patients who required plate removal had removal within 1 year after surgery which is consistent with the literature. The role of antibiotics in post-surgical care in orthognathic surgery remains questionable. Exposure of bony segments to the contaminants of the oral and nasal cavity is for many surgeons the reason to give prophylactic antibiotic treatment, however the evidence is inconclusive [19]. All orthognathic patients in our unit received intraoperative antibiotics and every 12 hours during the postoperative period in hospital. With an average hospitalization of 1,08 days patients received two doses of antibiotics. Remarkably, we reported a lower infection rate in comparison with studies were patients received antibiotics for a 7-day postoperative period [1,4,6,7,13]. Bacterial sampling when infection was present was not commonly performed. The second most frequent reason for plate removal is plate exposure, however none of the patients had plate exposure in our study [5]. It is unclear if wound closure in two layers in the lower jaw is beneficial to one layer in preventing plate exposure and infections, so in our unit we used single layer wound closure [4]. Bhatt et al. [20] had more plate exposure when high profile plates were used. These plates were not used in our department. Fixation of the mandibular osteotomy was performed with a single plate bilaterally. The use of more mandibular plates per side increases the risk of removal and should be avoided if possible [1,4]. Several studies have reported other causes for plate removal, such as sensitivity to temperature change, sinusitis, interference with dental implants and nerve and dental injuries. These causes were not found in the present study. We investigated two risk factors not mentioned in other studies: third molar removal during surgery and the manufacturer of the plates. The plates and screws used in our orthognathic patients are from two different manufacturers and were used according to the surgeon’s preference. However, we noted a small (non-significant) difference in plate removal between the two different plate systems. The reason for this is unclear. In both systems the plate thickness and screws are similar. Titamed plates could also be used upside down, which can result in less torque resistance. To our knowledge, we were the first study groups to investigate the relation between plate removal and manufacturer. Based on our data the brand of the plates and screws should not be considered as a risk factor.

Smoking results in reduced oxygenation of the oral tissues which impairs wound and bone healing and leads to more infections. Smokers showed a higher risk of plate removal than non-smokers according to most studies (up to 3,4 times higher risk) [7], whereas others did not [21]. In Belgium, 19% of the population smoke [22]. Our study presented a remarkably low percentage of smokers: 47 patients (3,8%). In general, orthognathic patients are young, healthy and highly motivated patients which results in a lower percentage of smokers. Thus, smoking is in our study not a significant risk factor, however smoking cessation should be emphasized at the presurgical intake.

In literature, age as a risk factor is unclear. Age was a statistically significant risk factor for plate removal according to different authors [6,18]. However, Widar et al. [1] and Kuhlefelt et al. [7] found no significant difference. In our study patients aged over 30 had a significant higher risk of plate removal.

CONCLUSION

One of the main limitations of our study is the lack of information about the quantity and type of bone during surgery. Another limitation is the lack of standardized documentation in the follow-up period, i.e. information about bruxism or limited mouth opening is missing. The duration of the surgery was not registered in the patient files, so this parameter was excluded. These factors should be investigated in further studies because they could influence the need for plate removal.

The authors conclude that significant risk factors for plate removal are age, mandibular plates, mandibular rotation and third molar removal during surgery, hence patients should be informed about these factors before the surgery. If plate removal is necessary, it is likely to occur within a year after surgery.

AUTHOR CONTRIBUTIONS

Setting up the concept of this article was done by authors RS, VL, DG, SO and KB. Data gathering and analysis were carried out by RS. All authors contributed to the interpretation in the discussion of this article. Critically revising the manuscript was performed by RS and JB.

ACKNOWLEDGMENTS

This research project did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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Robin SNEL

MD, DDS Department of Oral and Maxillofacial Surgery Vitaz Hospital Sint-Niklaas, Belgium

Dr. Robin Snel is a Maxillofacial Surgeon at the Department of Oral and Maxillofacial Surgery, Vitaz Hospital, Sint-Niklaas, Belgium. He obtained his master in Dentistry and Medicine at the University Hospitals of Leuven, Belgium. His main topics of interest are orthognathic surgery and implantology.

Questions

Which of the following is a significant risk factor for plate removal in this study?
1. Gender;
2. Age;
3. Plate manufacturer;
4. Smoking.
In which period were most plates removed?
1. 0-2 months post-operatively;
2. 3-4 months post-operatively;
3. 5-6 months post-operatively;
4. 11-12 months post-operatively.
Which of the following factors was the main reason for plate removal?
1. Subjective complaints: palpability;
2. Subjective complaints: discomfort;
3. Relapse;
4. Infection.
Which of the following locations had a significant higher incidence of plate removal?
1. Right side;
2. Left side;
3. Upper jaw;
4. Lower jaw.

Figure 1 Postoperative panoramic tomograph showing miniplates in place after bimaxillary surgery and genioplasty.

A: Immediate postoperative. B: six months after orthognathic surgery the screws on the left mandibular side were loose which resulted in pain complaints. Plate removal was performed under procedural sedation.

Figure 2 Status after orthognathic surgery in two different patients, both with signs of infection which indicated plate removal

A: Granulation and swelling at the site of the plate at the left lower jaw (marked with arrow) B: Fistula with purulent discharge on the left lower jaw (marked with arrow).

[Figure ID: F3]

Figure 3 Age distribution of the study group according to gender, resulting in a 1–1.5 male-female ratio. Male patients are situated on the left side of the graph, female patients on the right side.

Figure 4 Time to plate removal in months. All 78 patients had plate removal within a year of placement.

Figure 5 Reasons for plate removal. Infection was the most frequent reason for plate removal, followed by subjective complaints.

Figure 6 Time to plate removal in months. All 78 patients had plate removal within a year of placement.

Table 1 Patients requiring plate removal according to type of surgery.

	BSSO	Le Fort 1	Bimaxillary	Total
Not removed	433	99	642	1174
Removed	33	6	39	78
Total	466	105	681	1252

Table 2 Analysis of risk factors considered for removal.

		Patients with plates removed		Patient with no plates removed		Total	P-value
		N	%	N	%	Total	P-value
Age	<18y	29	4,9%	568	95,1%	597	P<.001
	18-29y	24	5,4%	420	94,6%	444
	≥ 30y +	25	11,8%	186	88,2%	211
Gender	Male	24	4,8%	477	95,2%	501	P=.085
Gender	Female	54	7,2%	697	92,8%	751	P=.085
M3 removal	Yes	21	9,8%	193	90,2%	214	P=.017
M3 removal	No	57	5,5%	981	94,5%	1038	P=.017
Plate manufacturer	Synthes	55	5,9%	875	94,1%	930	P=.432
Plate manufacturer	Titamed	23	7,1%	299	92,9%	322	P=.432
Mandibular plate length	≤ 8mm	31	5,4%	543	94,6%	574	P=.221
Mandibular plate length	≥ 8mm	41	7,2%	532	92,8%	573	P=.221
Mandibular rotation	Yes	11	12,8%	75	87,2%	86	P=.010
Mandibular rotation	No	61	5,7%	1000	94,3%	1061	P=.010
Smoking	Yes	3	6,4%	44	93,6%	47	P=.965
Smoking	No	75	6,2%	1130	93,8%	1205	P=.965
Plate location	Mandible	72	6,3%	1075	93,7%	1147	P<.001
Plate location	Maxilla	45	5,7%	741	94,3%	786	P<.001
Plate location	Right	45	3,6%	1207	96,4%	1252	P=.171
Plate location	Left	33	2,6%	1219	97,4%	1252	P=.171

Table 3 Differences between the plates manufacturers.

	Patients (%)	Plates	Removed plates (%)
Synthes	930 (74,3%)	4014	74 (1,8%)
Titamed	322 (25,7%)	1424	33 (2,3%)
KLS Martin	341 (27,2%)*	341	0 (0%)
Total	1252	5779	107 (1,8%)

^TF3-1Genioplasty always in combination with bimaxillary surgery, BSSO or Le Fort 1 osteotomy.

Table 4 Overview of papers that have been published about plate removal in orthognathic surgery.

First author	Year	No patients	Type of surgery	Patients with plates removed		Plates
First author	Year	No patients	Type of surgery	N	%	No plates inserted	No plates removed	% plates removed
Snel	2023	1252	BM, BSSO, LF1, G	78	6,2%	5779	107	1,9%
Sukegawa	2018	240	BSSO, LF1, G	71	29,6%	717	236	32,9%
Shin	2018	153	BSSO, LF1, G	57	37,3%	394	142	37%
Widar	2017	323	BM, BSSO, LF1, G	50	15%	–	–	–
Verweij	2016	150	BM, LF1, LF1 + G	3	2%	600	7	1,2%
Little	2015	202	BM, BSSO, LF1	21	10,4%	854	27	3,2%
Baas	2015	29	BM, BSSO	2	6,9%	–	–	–
Van Bakelen	2013	90	BM, BSSO, LF1	13	14,4%	–	–	–
Falter	2011	570	BM, BSSO, LF1	157	27,5%	3197	27	19,5%
Kuhlefelt	2010	153	BSSO	29	19%	308	56	18%
Haraji	2009	142	LF1	15	10,6%	–	–	–
O’Connell	2009	101	BM, BSSO, LF1	1	1%	447	1	0,2%