CLINICAL RESULTS OF RECONSTRUCTIVE NEUROSURGICAL INTERVENTIONS FOR THE SKULL USING COMPUTER MODELING AND THREE-DIMENSIONAL PRINTING Koporushko N. A., Mishinov S.V., Stupak V.V.

Tsivyan Research Institute of Traumatology and Orthopedics, Novosibirsk, Russia

Each year, patients with various pathology of central nervous system receive surgical interventions with craniectomy and formation of big and gigantic cranial defects [1-5]. Such patients complain of disfiguring defect, headache and protrusion of intracranial contents. Moreover, they have some rough focal neurological symptoms and epileptic onsets of various origin [6]. It is associated with increasing number of such patients in the general structure of traumatic brain injuries [7], and disease with neurooncologic and vascular pathology. For medical and cosmetic purposes, they receive reconstructive surgical interventions for closure of posttrepanation defect. Commonly, patients with cranial defects are persons of working age who are disabled owing to consequences [10-12]. Therefore, fast rehabilitation and return to professional activity present the important social and economic task of medicine.

Currently, in the world-wide practice of clinical studies, it is generally believed that patients' life quality is important, and, in some cases, it presents the main criterion of efficiency of treatment. It is generally accepted that life quality is the multi-aspect term. It is the integral feature and determines changes in physical, emotional and social well-being under influence of disease or its treatment [13-15].

Presence of extensive and, sometimes, disfiguring bone defects cause a significant decrease in life quality and disability. Therefore, realization of reconstructive surgery for the skull with closure of cranial defects should improve the clinical picture of a disease, and emotional and social well-being.

Objective − to study the clinical results of reconstructive interventions in patients with skull bone defects using individual titanium implants made using three-dimensional printing and standard titanium plates.

MATERIALS AND METHODS

The study corresponds to ethical standards of Helsinki Declare − Ethical Principles for Medical Research with Human Subjects 2000, and the Rules for Clinical Practice in the Russian Federation confirmed by the Order of Health Ministry of RF on April 1, 2016, No. 200n. The study was approved by the biomedical ethical committee of Tsivyan Research Institute of Traumatology and Orthopedics (the protocol No. 094/15, December 28, 2015).

The clinical materials were presented by 161 patients with bone defects of the skull who were operated in Tsivyan Research Institute of Traumatology and Orthopedics. A prospective analysis (2017-2019) with historical control (2009-2019) of results of reconstructive surgeries for closure of bone defects was conducted.

Among 161 patients, 81 patients (the comparison group) received the standard implant made of perforated titanium sheet, 80 patients (the study group) − the individual implant produced with the use of modern 3D computer and additive technologies of powdered titanium (the table 1).

Table 1

General characteristics of patients with acquired cranial defects, n (%)

Studied parameters	Groups		Total
	Study group	Comparison group
Total amount of patients	80 (49.69 %)	81 (50.31 %)	161
Mean age (years), M ± m	43.63 ± 1.69	41.25 ± 1.81	42.44 ± 1.24
Men	44 (55 %)	48 (59,26 %)	92 (57.14 %)
	P_ТМФ> 0.05 P_FET> 0.05
Women	36 (45 %)	33 (40.74 %)	69 (42.86 %)
	P_ТМФ> 0.05 P_FET> 0.05
Postsurgical follow-up terms (months), M ± m	24.66 ± 1.43	53.44 ± 3.82	39.14 ± 2.34
	P_u< 0.001

Note: P_U – Mann-Whitney test; differences are reliable with p ≤ 0.05, P_FET – Fisher's exact test, * – for P_FET>0.05, no statistical difference.

According to the classification used in Burdenko Neurosurgery Center, the patients were distributed according to causes of defects, their location in relation to cranial vault and base, according to lateralization, location, sizes, cerebral tissues alterations identified with CT and MRI, and clinical syndromes which form the clinical picture of a disease [6].

As result, estimation of clinical results of reconstructive interventions was based on the time course of clinical syndromes of a disease, changes in cerebral substrate in CT and MRI, and postsurgical complications, time of surgical intervention and mortality.

Distribution of cranial defects in dependence on a cause of occurrence is presented in the table 2. Among 165 defects, 98 (59.4 %) ones appeared as result of decompressive trepanations for correction of brain compression in patients with traumatic brain injury. The causes of 51 (30.9 %) defects were operations for removal of big and gigantic convexital and basal supratentorial meningiomas which impacted bone structures. 11 (6.7 %) defects appeared as result of extensive craniotomy in patients after endovascular interventions for arterial aneurysm and arteriovenous malformations, which were complicated by cerebral perfusion disorder and evident brain edema in the postsurgical period. The causes of 5 (3 %) defects were decompressive trepanations in patients who received removal of cerebral abscesses.

Table 2

Distribution of cranial defects in dependence on a cause of appearance

Groups

A cause of occurrence, and amount of post-trepanation defects

Traumatic brain injury, amount (%)

Neurooncology, amount (%)

CNS cerebrovascular pathology, amount (%)

CNS pyoinflammatory lesion, amount (%)

Total, amount (%)

Study group

(29.7 %)

(12.7 %)

(4.9 %)

(2.4 %)

(49.7 %)

Comparison groups

(29.7 %)

(18.2 %)

(1.8 %)

(0.6 %)

(50.3 %)

Total

(59.4 %)

(30.9 %)

(6.7 %)

(3.0 %)

165

(100 %)

Note: comparative intergroup analysis was not conducted.

In our series of 161 patients, bone defects were to the left in 82 (50.9 %) patients (41 (25.5 %) and 41 (25.45 %) in the comparison group and in the study group, correspondingly). 62 patients (38.5 %) had right-sided defects: 32 (19.9 %) and 30 (18.6 %) in the study group and in the comparison group correspondingly. 17 (10.6 %) patients had some cranial defects on both sides: 7 (4.4 %) defects in the study group, 10 (6.2 %) defects in the comparison group. 17 (10.6 %) patients had some defects involving jugal-orbital-facial region: 5 (3.1 %) patients with individual implants, 12 (7.5 %) with standard implants.

The isolated analysis of craniectomy zones showed the highest amount of bone defects in parietal (n = 123, 41 %) and temporal (n = 117, 39 %) regions, as well as 84 defects (28 %) in the frontal region, and 6 (2 %) defects in the occipital region.

The table 3 shows the distribution of defects according to sizes in compliance with the accepted classification accepted by the Association of Neurosurgeons of Russia in 2015 [16], depending on square and amount.

Table 3

Distribution of cranial defects in groups depending on their square and number

Parameters of defects	Groups of patients	Sizes of bone defects, M ± SD
		Small defects, amount (%)	Average defects, amount (%)		Big defects, amount (%)		Extensive defects, amount (%)
Number of defects	Study group	-	5 (3.0 %)	P_FET_<_0.01	20 (12.1 %)	P_FET₌_0.2	57 (34.5 %)	P_FET<0.01
	Группа сравнения Comparison group	5 (3.0 %)	25 (15.2 %)		28 (17.0 %)		25 (15.2 %)
	Total number of defects	5 (3.0 %)	30 (18.2 %)		48 (29.1 %)		82 (49.7 %)
Mean square of defect (cm²)	Study group	-	19.4 ± 6.0	P_U = 0.3	47.3 ± 9.6	P_U = 0.07	105.9 ± 42.3	P_U = 0.7
	Comparison group	7.2 ± 2.2	20.85 ± 5.3		42.25 ± 7.6		105.3 ± 42.4
	Mean square of al defects	7.2 ± 2.2	20.6 ± 5.3		44.4 ± 8.8		105.7 ± 42.1
Minimal square of defect (cm²)	Study group	-	12.6		32.9		62.8
	Comparison group	3.53	13.7		30.2		62.8
Maximal square of defect (cm²)	Study group	-	27.5		56.5		245.0
	Comparison group	9.42	28.3		56.7		219.9

Note: statistically significant differences with P_FET< 0.05, the values are presented as the mean and error of the mean (M ± SD); P_U – Mann-Whitney test, statistically significant differences with p ≤ 0.05.

Clinical syndromes in operated patients

The presurgical clinical examination identified 167 syndromes in 80 patients with individual implants. 39 (48.8 %) patients had only single syndrome, 41 (51.2 %) patients − several ones. Among 39 patients with one leading syndrome, 15 (38.5 %) had pyramid syndrome, 9 (23.1 %) − psychopathologic syndrome, 12 (30.8 %) − epileptic syndrome, and 3 (7.6 %) − afatic syndrome. Among 41 persons with combination of 128 clinical syndromes in the clinical picture of a disease, 16 (39 %) patients had asthenic (n = 16 among 128 syndromes, 12.5 %), meteorotropic (n = 16, 12.9 %) and psychopathological (n = 14, 10.9 %) syndrome; 15 patients (36.5 %) had asthenic (n = 14, 10.9 %), pyramidal (n = 14, 10.9 %) and meteorotropic syndrome (n = 15, 11.7 %); 10 patients (24.3 %) had afatic (n = 10, 7.8 %), pyramidal (n = 9, 7 %), asthenic (n = 10, 7.8 %) and meteorotropic (n = 10, 7.8 %) syndrome.

Clinical examinations showed 153 presurgical syndromes in 81 patients in the comparison group. 36 (44.4 %) patients had only single syndrome, 45 (55.6 %) patients − 2-3. Among 36 patients with a single leading syndrome, 13 ones (36.1 %) had pyramidal, 9 (25.1 %) − psychopathological, 10 (27.7 %) − epileptic and 4 (11.1 %) − afatic syndrome. Among 45 patients with 117 clinical syndromes in the clinical picture, 17 (37.8 %) has asthenic (n = 16 among 117 clinical syndromes, 13.7 %), meteorotropic (n = 16, 13.7 %) and psychopathological (n = 15, 12.8 %) syndrome; 16 patients (35.6 %) had asthenic (n = 16, 13.7 %), pyramidal (n = 13, 11.1 %) and meteorotropic syndrome (n = 13, 11.1 %); 12 patients (26.6 %) had afatic (n = 9, 7.7 %), pyramidal (n = 7, 6.0 %) and asthenic syndrome (n = 12, 10.3 %). The statistical analysis of the data showed the absence of differences (p value for Fisher's exact test = 0.4; the table 4).

Table 4

Distribution of patients with various syndromes of the disease depending on size of a bone defect over time

Before surgery

Amount of clinical syndromes

Small defects, amount (%)

Average defects, amount (%)

Big defects, amount (%)

Extensive defects, amount (%)

General number of syndromes, amount (%)

Study group

(11.6 %)

(12.5 %)

(28.1 %)

P_FET = 0.4

167

(52.2 %)

Comparison group

(3.5 %)

(10.9 %)

(10.6 %)

(22.8 %)

153

(47.8 %)

Total

(3.5 %)

(22.5 %)

(23.1 %)

163

(50.9 %)

320

(100 %)

After surgery

Study group

(9.0 %)

(13.2 %)

(23.7 %)

P_FET = 0.3

(46.4 %)

Comparison group

(4.5 %)

(11.3 %)

(11.4 %)

(25.6 %)

113

(53.6 %)

Total

(4.5 %)

(20.3 %)

(23.6 %)

114

(51.6 %)

211

(100 %)

Note: statistically significant differences with P_FET< 0.05.

Cerebral tissue changes in operated patients

Among 80 persons with 144 dura mater alterations identified with neurovisualization techniques in the study group, 16 (19.8 %) patients had a single type of tissue abnormality − hydrocephalus (11.1 %). 65 (90.2 %) patients had a combination of several types identified in CT and MRI. They had combinations of 128 tissue changes in the brain: 27 patients had hydrocephalus (n = 22 cases among 144 tissue syndromes, 17.2 %), cystic (n = 18, 14.1 %) and scar adhesive process (n = 17, 13.3 %); 21 patients (32.3 %) had hydrocephalus (n = 20, 15.6 %), scar-adhesive alterations (n = 14, 10.9 %); 17 (26.2 %) patients had hydrocephalus (n = 10, 7.8 %), diffuse-atrophic changes (n = 17, 13.3 %) and porencephalia (n = 10, 7.8 %).

In the comparison group including 81 patients, 128 cases of tissue pathology were identified: 17 patients had a single type of dura mater − hydrocephalus (11.8 %). 64 (79.1 %) patients had 111 combinations of such types (2-3 in each patient); CT and MRI showed hydrocephalus in 24 (37.5 %) patients (n = 18 cases among all 111 tissue changes, 16.2 %), scar-adhesive process (n = 17, 15.3 %) and cystic process (n = 18, 16.2 %); 25 patients (39.1 %) had hydrocephalus (n = 22, 19.8 %), scar-adhesive changes (n = 18, 16.2 %); 15 patients (23.4 %) had diffuse-atrophic alterations (n = 15, 13.5 %) and porencephalia (n = 3, 2.7 %).

Before cranioplasty, all cases of tissue changes according to MRI and CT were classified as followed: mild changes in 35 (21.7 %), average changes in 64 (39.8 %) and severe changes in 62 (38.5 %). The intergroup distribution according to degrees of cerebral changes did not find any reliable differences: p value for Fisher's exact test for mild changes = 1.0, for average changes − 0.8, for severe changes − 0.7 (the table 5).

Table 5

Distribution of patients depending on degree of tissue changes in the brain

Before surgery
Groups	Mild tissue changes, amount (%)		Average tissue changes, amount (%)		Severe tissue changes, amount (%)		Total number (%)
Study group	17 (10.6 %)	P_FET = 1.0	31 (19.3 %)	P_FET = 0.8	32 (19.9 %)	P_FET = 0.7	80 (49.7 %)
Comparison group	18 (11.2 %)		33 (22.4 %)		30 (16.8 %)		81 (50.3 %)
Total number	35 (21.7 %)		64 (41.6 %)		62 (36.6 %)		161 (100.0 %)
After surgery
Groups	Mild tissue changes, amount (%)		Average tissue changes, amount (%)		Severe tissue changes, amount (%)		Total number, (%)
Study group	17 (10.6 %)	P_FET=1.0	31 (19.3 %)	P_FET=0.5	32 (19.9 %)	P_FET=0.4	80 (49.7 %)
Comparison group	18 (11.2 %)		36 (22.4 %)		27 (16.8 %)		81 (50.3 %)
Total number	35 (21.7 %)		67 (41.6 %)		59 (36.6 %)		161 (100.0 %)

Note: statistically significant differences with P_FET < 0.05.

Therefore, patients of the study group with cranial defects were basically comparable with the operated patients of the comparison group according to amount of patients, gender, average age, number, sizes and location of bone defects, number of clinical syndromes in the clinical picture of a disease and number of cerebral tissue changes (p > 0.05). There were statistically significant differences in amount of extensive and average defects in the study group as compared to the comparison group (p < 0.05).

Statistical analysis

Mann-Whitney's test and Fisher's exact test were used for estimation of statistical significance. The level of statistical differences was p ≤ 0.05. Statistical analysis of the data was conducted with Statistica 10.

RESULTS

Some positive time trends in clinical condition of the patients were noted after realization of reconstructive surgical interventions for the skull and for closure of bone defects. It is associated with the fact that the patients became less meteo-dependent. In 80 patients treated with individual implants, the clinical postsurgical examination showed a decrease in total amount of main clinical syndromes from 167 to 98 (58.7 %). Among 39 (48.8 %) patients with a single syndrome, 15 (38.5 %) had pyramidal, 10 (25.6 %) patients psychopathological, 9 (23.1 %) − epileptic and 5 (12.8 %) − afatic syndrome. Among 41 patients (51.2 %) with several syndromes, the total amount decreased from 128 to 59 (60 %). 16 patients had asthenic (n = 3 cases among 59 clinical syndromes, 5.0 %), meteorotropic (n = 2, 3.4 %) and psychopathological (n = 13, 22.0 %); 15 patients (36.5 %) had asthenic (n = 5, 8.5 %), pyramidal (n = 13, 22.0 %) and meteorotropic (n = 1, 1.7 %) syndrome; 10 (24.3 %) patients had afatic (n = 9, 15.3 %), pyramidal (n = 8, 13.6 %), asthenic (n = 3, 5.0 %) and meteorotropic (n = 2, 3.4 %) syndrome.

81 patients of the comparison group showed a decrease in the amount of main syndromes from 153 to 113. 30 patients had only a single syndrome in the clinical picture: 12 (40 %) patients had pyramidal, 12 (40 %) patients − psychopathological and 6 (20 %) − afatic syndrome. 30 (37 %) patients had only a single syndrome in the clinical picture: 9 (30 %) − pyramidal, 9 (30 %) − psychopathological, 6 (20 %) − afatic, 6 (20 %) − epileptic syndrome. 51 (62.9 %) patients had several clinical syndromes, but their general amount decreased from 113 to 83: 19 (37.3 %) patients − asthenic (n = 9 cases among 83 clinical syndromes, 10,8 %), meteorotropic (n = 6, 7.2 %) and psychopathological (n = 15, 18.1 %); 18 patients (35.3 %) − asthenic (n = 6, 7.2 %), pyramidal (n = 12, 14.5 %) and meteorotropic (n = 8, 9.6 %); 14 (27.5 %) − afatic (n = 10, 12 %), pyramidal (n = 8, 9.6 %) and asthenic syndrome (n = 9, 10.8 %).

In the late postsurgical period (2 years after surgery), it was found that a type of the used implant did not influence significantly on a decrease in total amount of main clinical symptoms in the whole series and in two groups. Moreover, we could observe a decrease in amount of clinical syndromes in the study group as compared to the comparison group: 98 and 113, correspondingly (p = 0.3).

The number of clinical syndromes depends on sizes of a bone defect. The increase in size of a postsurgical defect worsens the clinical picture of a disease, resulting in occurrence of the above-mentioned syndromes (the table 4).

The conducted reconstructive interventions for the skull lead to only slight changes in quantitative cases and qualitative values of cerebral tissue injuries in view of stabilization of progression of hydrocephalus and atrophic processes determined by vascular disorders in the brain in protruding and retracting defects of the skull. In 3 cases of severe cerebral tissue injuries, where individual implants were used, we observed positive time trends in view of decreasing degree of hydrocephalus and recovery of brain symmetry.

2 years after surgical management of all (161) patients, mild changes persisted in 35 (21.7 %), average tissue changes increased by 3 (67 cases, 41.6 %), and severe changes decreased by 3 (59 patients, 36.6 %) (the table 5).

By this moment, it was found that the amount of tissue changes did not depend on features of a used implant, but their amount still depended on a size of a cranial defect. The highest amount of severe and average tissue injuries were in patients with big and, especially, with extensive bone defects formed during surgery for adequate brain decompression (the table 6).

Table 6

Distribution of patients with tissue injuries to the brain depending on size of bone defect over time

До операции / Before surgery

Tissue changes

Small defects, amount (%)

Average defects, amount (%)

Big defects, amount (%)

Extensive defects, amount (%)

Total number of tissue changes, amount (%)

Number of mild tissue changes in brain

Study group

(1.8 %)

(2.6 %)

(3.3 %)

(7.7 %)

P_FET = 0.7

Comparison group

(1.1 %)

(2.6 %)

(2.2 %)

(1.8 %)

(7.7 %)

Total number

(1.1 %)

(4.4 %)

(4.8 %)

(5.1 %)

(15.4 %)

Number of average tissue changes in brain

Study group

(4.8 %)

(4.4 %)

(8.5 %)

(17.7 %)

P_FET = 0.7

Comparison group

(0.7 %)

(4.0 %)

(3.0 %)

(7.0 %)

(14.7 %)

Total number

(0.7 %)

(8.8 %)

(7.4 %)

(15.5 %)

(32.4 %)

Number of severe tissue changes in brain

Study group

(1.1 %)

(6.6 %)

(19.9 %)

(27.6 %)

P_FET = 0.9

Comparison group

(0.7 %)

(7.0 %)

(16.9 %)

(24.6 %)

Total number

(1.8 %)

(13.6 %)

100

(36.8 %)

142

(52.2 %)

Total

(1.8 %)

(15.0 %)

(25.8 %)

156

(57.4 %)

272

(100 %)

After surgery

Number of mild tissue changes in brain

Study group

(1.8 %)

(2.6 %)

(3.3 %)

(7.7 %)

P_FET = 0.7

Comparison group

(1.1 %)

(2.6 %)

(2.2 %)

(1.8 %)

(7.7 %)

Total number

(1.1 %)

(4.4 %)

(4.8 %)

(5.1 %)

(15.4 %)

Number of average tissue changes in brain

Study group

(4.8 %)

(4.4 %)

(8.5 %)

(17.7 %)

P_FET = 0.7

Comparison group

(0.7 %)

(4.0 %)

(3.0 %)

(7.0 %)

(14.7 %)

Total number

(0.7 %)

(8.8 %)

(7.4 %)

(15.5 %)

(32.4 %)

Number of severe tissue changes in brain

Study group

(1.1 %)

(7.7 %)

(18.8 %)

(27.6 %)

P_FET = 0.9

Comparison group

(0.7 %)

(7.0 %)

(16.9 %)

(24.6 %)

Total number

(1.8 %)

(14.7 %)

(35.7 %)

142

(52.2 %)

Total

(1.8 %)

(15.0 %)

(26.9 %)

153

(56.3 %)

272

(100 %)

Note: statistically significant differences with P_FET <0.05.

19 (11.2 %) complications of soft tissues developed after 169 surgical interventions in the postsurgical period. They were presented by detachment of wound borders, superficial contamination of soft tissues and marginal necrosis of the skin. None of them cause occurrence of intracranial purulent processes. Lethal cases were absent. Soft tissue purulence appeared in the postsurgical suture site in 5 (3 %) patients. Conservative management was inefficient, resulting in additional intervention and removal of implants. The group of individual implants received 84 surgical interventions, including complications in 4 cases (4.8 %). The implants were removed in 2 patients (2.3 %) owing to progression of a complication. 15 (17.6 %) complications developed after use of standard implants among 85 surgeries. Among them, development and progression of purulent process occurred in 3 (3.5 %) cases in the postsurgical suture site, resulting in removal of implants. The incidence of postsurgical complications was associated with extensive square of a defect and prevailed in the groups with standard titanium plates.

We analyzed the duration of surgical interventions for closure of extensive cranial defects in cases of complications. The results are presented in the table 7. It shows that duration of surgery with use of individual implants demonstrates lower statistical significance as compared to standard implants. It is associated with the fact that the individual implant is produced before surgery, and it does not require for formation in compliance with anatomical features of the skull in the site of an extensive defect. Placement of the standard implant takes more time for opened surgical wound.

Table 7

Duration of surgical intervention in closure of extensive cranial defects

Groups of patients	Number of complications	Minimal time (min.)	Maximal time (min.)	Average time, M ± m (min.)
Study group	4	100.0	150.0	125.0 ± 10.4
Comparison group	15	100.0	400.0	209.0 ± 18.6
Total	P_U = 0.01
Total	19	100.0	400.0	191.3 ± 16.7

Note: differences in level of a sing in the compared groups are statistically significant, P_U− Mann-Whitney test, p < 0.05.

A common error appears in some patients during closure of extensive cranial defects. It consists in incomplete closure of a defect. In our clinical materials, it was found in only operated patients with use of standard titanium implants in 5 (6.2 %) among 81 patients. There were not postsurgical lethal cases.

DISCUSSION

In our work, which is bases on the single center cohort study, the prospective (2017-2019) analysis with historical capture (2009-2016) of clinical results of reconstructive neurosurgical interventions for closure of cranial defects with standard sheet titanium implants and powdered titanium implants made with computer modeling and 3D printing was carried out.

Estimation of clinical results of reconstructive cranial surgeries is mainly based in time course of clinical syndromes and cerebral tissue changes according to CT and MRI of cranial defects of various sizes and location according to the classification developed in Burdenko Neurosurgery Research Center [6]. According to some domestic authors, about 70 % of operated patients with cranial defects resume their professional and educational activity after closure of defects. However, there are not any studies with detailed description of clinical results of such pathology in the postsurgical period. There are some foreign publications, which show results of surgery of patients with cranial defects, but these studies are based on other clinical data [0-5, 17-24].

Our study showed that the clinical picture of a disease and amount of clinical syndromes depended on sizes of a cranial defect both before surgery and in the late postsurgical period. The increasing sizes of postsurgical defects influenced on severity of the clinical picture of a disease and increased the amount of syndromes. A type of the used implant does not influence significantly on a decrease in the general amount of main clinical syndromes in the whole series and in two groups of follow-up. However, a decrease in the amount of clinical syndromes in the clinical picture of a disease was observed in the study group as compared to the comparison one (p = 0.3) that can be statistically significant in increase in sample of patients.

Reconstructive interventions for closure of cranial defects cause only minimal changes in quantitative and qualitative values of cerebral tissues alterations in view of stabilization of atrophic processes determined by vascular disorders in the brain, and by progression of hydrocephalus in protruding and retracting defects. In various time intervals of observation, available disorders does not depend on a type of an implant, but their number still depends on a size of cranial defects. The highest amount of severe and average tissue injuries is observed in patients with big and, especially, with extensive bone defects.

11.2 % of soft tissue complications developed among all operated patients in the postsurgical period. The complications included wound separation, superficial infection of soft tissues and marginal necrosis of the skin. None of complications caused occurrence of purulent intracranial processes, which could cause lethal outcomes. Soft tissue purulence in the surgical suture site appeared in 3 % of operated patients. The amount of such complications is similar with literature data [6, 17-19, 25-27]. The authors report on development of purulent inflammatory complications in these patients in 3.1-16 % of cases in short term and long term periods.

Owing to progression of local purulence in patients with standard powdered titanium implants and standard implants, they were removed in 2.3 % and 3.5 % of cases respectively. Our incidence of removal of implants is lower than in the literature data in patients with such pathology in 4-25 % [20, 26-32].

The purulent process with individual implants was local (only in the site of a skin defect). Such course of soft tissue purulence was noted by Gilardino M.S. et al. (2015) for individual implants made of powdered titanium [20]. Owing to good integration with soft tissues along the whole square of the implant, free space on its external and internal surface was absent. It did not allow distribution of purulent discharge along the graft. Its removal presented the difficult task since it is difficultly detached from surrounding tissues. For the standard titanium implant, the purulent process due to non-intense scar process on the border between the implant and soft tissues distributed along the whole bed. Therefore, its removal was not accompanied by technical difficulties.

The highest amount of postsurgical complications of soft tissues occurs after reconstructive interventions for extensive cranial defects and after use of standard implants. It can be explained by higher injury to soft tissues and by an increase in surgery time. The time of a reconstructive intervention for the standard implant for closure of an extensive cranial defect is 1.5 time higher than for surgery with the individual implant. The individual implant gives appropriate and complete closure of a bone defect of any size and location.

CONCLUSION

1. The best clinical results of reconstructive cranial surgery in view of decreasing amount of clinical syndromes in the disease picture of the late postsurgical period are received with use of the individual implant.

2. The increase in sizes of a cranial defect causes the increase in incidence of disease syndromes and worsens a degree of cerebral tissue injuries identified in CT and MRI.

Information on financing and conflict of interests

The study was conducted without sponsorship. The authors declare the absence of any clear and potential conflicts of interests relating to publication of this article.