Open Treatment with Ultrasound Activated Resorbable Pins Versus Closed Treatment of Adult Mandible Condylar Head Fractures

Abstract

Purpose

The purpose of the study was to investigate whether open reduction and internal fixation (ORIF) with ultrasound activated resorbable pins (UARPs) is superior to closed treatment of condylar head (CH) fractures. The investigators hypothesized that fixation with UARPs is superior to closed treatment of CH fracture.

Methods

It was a prospective pilot study on CH fracture patients. Patients in closed group were managed conservatively with arch bar fixation and elastic guidance. Fixation in open group was done with UARPs. Assessment was done for primary objective of stability of fixation by UARPs and secondary objectives of functional outcome and complications.

Results

The study sample included 20 patients (10 in each group). 10 patients (11 joints) in closed group and 9 patients (10 joints) in open group were available for final follow-up. 5 joints showed re-dislocation of fractured segment, 1 joint showed slightly imperfect but adequate fixation and 4 joints showed adequate fixation in open group. In the closed group, displaced fragment was fused with mandible at displaced position in all the joints. All the joints showed resorption of medial condylar head at 3 months follow-up in open group. There was minimal resorption of condyle in closed group. Occlusion was deranged in 3 patients in open group and 1 patient in closed group. MIO, pain scores and lateral excursions were equal in both the groups.

Conclusion

The results of the present study rejected the hypothesis that fixation of CH with UARPs was superior than closed treatment. There was resorption of medial CH fragment in open group as compared to closed group.

Introduction

Condylar head (CH) fractures of the mandible are defined as those in which the fracture line starts in the articular surface and may extend outside the capsule [1]. These fractures are challenging to treat. Size and fragility of CH segments pose difficulty in achieving reduction and fixation of fractured condyle. Both closed treatment and ORIF of CH fractures have been advocated, but its management remains a topic of controversy. In a review of systematic reviews for condylar fractures, it was found that surgical treatment is better than conservative treatment [2]_. The limitations of closed treatment like inappropriate reduction, ramus height shortening and intermaxillary fixation may be avoided by open reduction method. Once it has been decided to go for ORIF, then appropriate method of fixation must be chosen. Osteosynthesis of CH fracture demands stability of reduced fragments, which can be better achieved by metallic plates and screws. However, application of metallic screws and plates in CH fracture has a disadvantage of inducing stresses and protrusion of screw beyond condyle for which another surgery may be required for its removal. This disadvantage can be avoided by use of UARPs (Sonic weld, KLS Martin®, Tuttlingen, Germany). These pins liquefy and run into the medullary bone and upon solidification can anchor together the reduced fragments of mandible. A few studies exist that have tested the stability of pin osteosynthesis in CH fracture [3, 4]. Literature lack evidence for the stability of pin osteosynthesis in CH fractures. This study attempts to answer the question “Do UARPs provide adequate fixation for CH fracture management?

The purpose of the study was to investigate whether ORIF with UARPs is superior to closed management of CH fractures. The investigators hypothesized that fixation of CH with UARPs is superior to closed treatment of condylar head fracture. The specific aims of the study were to: (1) find out the stability of fixation provided by resorbable pins. (2) Compare functional outcome in terms of occlusion, MIO, excursive movements, pain, complications of surgical procedure and resorption at follow-up.

Patients and Methods

Study Design

To address the research question, the investigator designed and implemented a prospective randomized controlled, pilot study. The study was approved by the Institute Ethical Committee. Figure 1 represents the consort flow diagram of the present study. The study sample was composed of all the patients presenting for management of CH of mandible from March 2017 to September 2018. Adult patients (≥ 18 years) with unilateral or bilateral CH fractures showing lost partial or lost vertical apposition (partial vertical apposition means some contact between the fragments at the fracture plane is maintained and lost vertical apposition indicates no contact between the fracture plane remains) on cone beam computed tomography (CBCT) (Fig. 2) as per AOCMF classification [5] were included in the study. The patients were excluded as study subjects, if they had comminuted (more than 2 fragments) CH fractures and the patients who were edentulous. The patients were randomized into open group and closed group using computer generated random number. Allocation concealment was done using sealed opaque envelop.

Fig. 1.

Consort flow diagram of the present study

Fig. 2.

Preoperative cone beam computed tomography showing fractured condylar head segment with lost vertical apposition

The preoperative CBCT was taken in both groups for assessment of position (displaced/dislocated) of fractured condylar segment. The stability of fracture segments (whether the proximal fractured condyle maintained its position achieved at the time of surgery) was checked by taking postoperative CBCT at 24 h for open group patients. Final CBCT for assessment of morphological changes (resorption and remodeling of fractured condyle) in condyle was taken at 3 months follow-up in both the groups.

Study Variables

Patients with at least a follow-up of 3 months were included in the study. Evaluation of stability of fixation achieved by resorbable pins was the primary objective. Secondary objective included comparison of outcome in terms of occlusion, maximal incisal opening (MIO), lateral excursion, pain, complications of surgical procedure and resorption.

Surgical Technique

The preoperative CBCT was taken for the assessment of position and location of fractured condylar segment. Erich’s arch bars were placed. The CH segment was approached through modified preauricular incision under general anesthesia. Reduction was achieved by manipulating medial fractured segment with help of periosteal elevators. Reduction was maintained with help of hook or small bone clamp. It was attempted to preserve the attachment of lateral pterygoid to maintain vitality. After satisfactory reduction of CH segments, a drill hole of depth equal to mesiodistal width of CH was made through both these segments with 2 mm diameter drill. The hole in the outer segment was drilled to 2.2 mm so that the pins could pass passively. 1–2 sonic weld pins were (diameter of 2.1 and length 15 or 17 mm) inserted passively into the hole, and the sonic probe was then activated to allow liquefaction of the pin. The other associated fractures of mandible were treated by standard ORIF techniques. In postoperative, period elastic guidance was used for preventing exogenous stress. CBCT evaluation was done at 24 h and at 3 months follow-up.

In closed group, conservative treatment was provided with application of Erich’s arch bar and occlusion was achieved by elastic guidance. The patients were kept on regular follow-up at one week, one month and 3 months. The arch bars were removed when patients were able to close in normal occlusion without any guidance. Final evaluation with CBCT was done at 3 months follow-up.

Data Analysis

Descriptive statistics was performed by calculating mean and standard deviation for the continuous variables. Categorical variables are presented as absolute numbers and percentage. The software used for the statistical analysis was SPSS (statistical package for social sciences) version 18 (IBM Corporation, SPSS Inc., Chicago, IL, USA). Inferential statistics like Chi-square test/Fischer exact test and Man–Whitney U test was used to check the difference between the groups. The p value was taken significant when less than 0.05 (p < 0.05), and confidence interval of 95% was taken.

Results

20 patients were recruited for the study. The baseline data were similar in both the groups. Nine patients (10 Joints) in open group and 10 (11 joints) in closed group were available for final follow-up. Summary of results given in Table 1. There were 16 male and 3 female patients with mean age of 38.9 ± 17.07 years in closed group and 29.11 ± 9.64 years in open group. There was no statistically significant difference between age in both the groups (p = 0.10). Gender distribution was homogenous and was statistically non-significant (p = 0.9) between both the groups.

Table 1.

Summary of observations of study sample (n = 19)

Study variables		Open group	Closed group
Sample size		9 patients (10 joints)	10 patients (11 joints)
Age		29.11 ± 9.64 years	38.9 ± 17.07 years
Sex	Male	8	8
	Female	1	2
Side	Bilateral	1	1
	Right	2	2
	Left	6	7
Pain	Preoperative score	8.44 ± 1.13	7.40 ± 1.26
	Follow-up score	1.44 ± 2.00	1.90 ± 1.45
Stability of fixation	Adequate	4	NA
	Partial	1	NA
	Re-dislocation	5	NA
Resorption	10 joints	0
Occlusion	Satisfactory	6	9
	Unsatisfactory	3	1
Mouth opening	Preoperative	20.33 ± 6.16	25.70 ± 6.24
	Follow-up	31.56 ± 5.92	31.65 ± 5.33
Excursive movements at 3 month follow-up		5.11 ± 3.41	5.90 ± 2.73

NA: not applicable

In open group, on 24 h postoperative CBCT out of 10 joints: 4 joints had good anatomic reduction (Fig. 3a and b), 1 joint showed slightly imperfect reduction and 5 joints did not maintain position of fractured segments achieved during surgery and showed re-dislocation (Fig. 4a and b). In 2 joints, loss of fixation was seen intraoperatively. These patients were managed by using titanium screw. Resorption of fractured segment was seen at 3-month follow-up CBCT in all the cases managed by open technique (either by UARPs or titanium screws) (Fig. 3b). There was union and remodeling with minimal resorption of medially displaced fracture segment in all the cases treated with closed method (Fig. 5a and b).

Fig. 3.

a Postoperative cone beam computed tomography of the case shown in Fig. 2 showing adequate fixation with ultrasound activated resorbable pins. b Cone beam computed tomography of same patient showing resorption after 3 months follow-up

Fig. 4.

a Preoperative cone beam computed tomography showing condylar head fracture and b Postoperative cone beam computed tomography of the same patent showing re-dislocation of condylar head segment post fixation

Fig. 5.

a Preoperative cone beam computed tomography showing condylar head fracture b Follow-up cone beam computed tomography of same patient managed with closed treatment showing union and remodeling of condylar head segment and no resorption

Derangement of occlusion was seen in 3 patients in open group and in 1 patient in closed group. MIO, pain scores and lateral excursions were equal in both the groups. There was improvement in MIO in both the groups. MIO at 3 months follow-up was 31.56 ± 5.92 and 31.65 ± 5.33 in open group and closed group, respectively. No significant difference was seen in MIO at 3 months follow-up. Mean excursive movement was 5.11 ± 3.41 and 5.90 ± 2.73 in open group and closed group, respectively. No significant difference was observed in excursive movements in open and closed group. The pain decreased in both closed and open group at 3 months follow-up. Preoperative pain scores were 8.44 ± 1.13 and 7.40 ± 1.26 in open and closed group, respectively. Pain score decreased to 1.44 ± 2.00 and 1.90 ± 1.45 in open and closed group, respectively, with no significant difference at 3 months follow-up.

All the joints showed resorption at 3 months follow-up in open group. When morphological changes were compared between closed and open group, more resorption of medially displaced segment was observed in open group cases. There was minimal resorption in closed group DC fractures. In open group, 4 patients had temporary weakness of temporal branch of facial nerve which resolved completely at 3 months follow-up. There was statistically significant difference between the two groups for facial nerve paresis (p = 0.07). 2 patients had complication of infection of surgical site and parotid fistula. Both the cases resolved with conservative management.

Discussion

Initially, conservative management of CH fractures was preferred but now the trend is changing and there are studies which favor ORIF. In literature, UARPs have been used in only few studies with small sample size for fixation of CH. The use of resorbable pins for fixation of CH fractures certainly warrants further study. The purpose of the study was to find out which technique is superior in the management of CH fractures. We hypothesized that the bioresorbable pins made of polymer would adequately fix CH fracture and maintain its anatomic reduction. But there were poor results as resorbable pins did not provide adequate fixation for CH fractures.

In the present study, out of 10 joints in open group: 5 joints had re-dislocation of the fracture segment, 1 joint showed slightly imperfect but adequate fixation and 4 joints had adequate fixation. There was loss of primary stability in two joints intraoperatively. Because of loss of primary stability in intraoperative time, these two joints were managed with titanium screw fixation. There was loss of fixation in 3 joints postoperatively as seen on postoperative CBCT. The reason for this failure could be fracture of the pin due to load. The other possible reason for failure of pins to hold on to fracture segments could be technical challenges for placing these 15–17 mm long pins. Ideally the pin should start melting at the far end and should engage the far segment. It could be possible that far end of pin did not engage the far segment. It was observed the pins started melting at its head, so it was difficult to push it into the far segment. Elastic guidance was given to prevent exogenous stress. McLeod and Saeed [6] used resorbable pins in 17 joints and found good reduction in 8 joints and partial reduction in 9 joints. Our study showed results in contradiction with Schneider et al [7] in which the use of UARPs fixation provided adequate strength and stability. Richter et al [8] used resorbable pins in 4 joints and found re-dislocation of fractured segment in 1 joint and slightly imperfect fixation in 1 joint. Galil and Loukota [9] used these pins in 1 patient and found satisfactory outcome in terms of repositioning of fracture segment. There was union and remodeling of medially displaced CH segment in closed group patients.

Postoperative occlusion is one of the most important criteria for the success of the reduction procedure. Deranged occlusion was seen in 3 patients in open group and in 1 patient in closed group at 3 months of follow-up. The disturbance in occlusion might be attributable to the malposition and resorption of CH segment. The resorption of condyle on operated side leads to loss of condylar height on ipsilateral side which further leads to open bite on contralateral side and anterior open bite in bilateral cases. Similarly, McLeod and Saeed [6] used resorbable pins in 15 patients and found derangement of occlusion in 4 patients. In contrary to this, Richter et al [8] used resorbable pins in 3 patients and found satisfactory occlusion in all 3 patients. Galil and Loukota [9] used pins in one patient with bilateral condylar head fracture and found satisfactory occlusion. Hlawitschka et al [10] in their study compared the closed and open treatment of intracapsular fracture. They found that 30% cases in closed group had disturbance in occlusion, and there was stable occlusion in open group patients. Other studies are there which found satisfactory occlusion after use of resorbable pins. In a multivariate retrospective study, Zhang et al [11] found satisfactory outcome in ORIF group in CH fractures.

In the present study, improvement in MIO was seen in both the groups at 3 months follow-up. Mean MIO at 3 months follow-up in open and closed group was 31.56 ± 5.92 (24–40 mm) and 31.65 ± 5.33 (21–40 mm), respectively. Similar to our study, McLeod and Saeed [6] found a mean MIO of 38 mm with range of 30–45 mm in 15 patients after use of UARPs. Zhang et al [11] in their study evaluated the ORIF with screw in CH fracture and they found that passive mouth opening of 3.43 ± 0.35 cm after 3 months. In the present study, the mean excursive movement was 5.11 ± 3.41 and 5.90 ± 2.73 in open group and closed group, respectively, at 3 month follow-up. Abdel-Galil and Loukota [9] used these pins in one patient and found satisfactory outcome in terms of excursive movement bilaterally.

Pain is one of the important criteria for success of reduction procedure. Pain was measured preoperatively and 3 months postoperatively on visual analog scale. Pain was found to be decreased in both the group at 3 months follow-up. This decrease in pain might be due to anatomical reduction of hard and soft tissues (disk and retrodiscal tissue) that leads to early restoration of function in open group. Outcome in terms of postoperative pain was thoroughly studied by Galil and Loukota [9]. They used pins and found satisfactory outcome in terms of pain. Ying et al [12] in their study found that out of 55 patients of DC fracture (in which 7 patients managed conservatively and 48 patients managed by open reduction), only one patient had a complaint of pain at 6 months follow-up in open group patients.

All the joints showed resorption at 3 months follow-up in open group. This resorption could be due to the loss of vitality of fractured segment during manipulation. Other reason for CH resorption can be an aseptic condylar necrosis that can be due to the result of trauma. An almost complete resorption of the condylar process being observed even following closed functional treatment [13]. Smolka et al [14] observed minimal resorption of CH in 48 cases managed with ORIF. There was minimal resorption in patients managed in closed group in comparison with open group patients in this study. Because of resorption, metallic screws may also not be suitable for management of CH as it will lead to protrusion of screws beyond bony boundaries into joint capsule. Second surgical procedure may be required to remove titanium screws. This disadvantage of second surgical procedure can be avoided by the use of UARPs.

Facial nerve weakness is one of the most clinically visible complication of surgical approach to the temporomandibular joint. In the present study, temporary weakness of temporal branch of facial nerve was seen in 4 patients in open group. Facial nerve weakness was completely resolved at 3 months follow-up. This weakness of facial nerve may be due to greater traction that had been required to expose the fractured segment or may be due to hematoma formation that resolved eventually. By careful dissection throughout the procedure, these complications can be minimized. McLeod and Saeed [6] in their study of 15 patients found facial paralysis in 3 patients. Full recovery was there in 2 patients, but 1 patient was still improving even at one year follow-up. Richter et al [8] in their study used UARPs in 3 patient and found that 1 patient had temporary facial nerve paralysis that resolved completely at follow-up. Zhang et al [15] in their study evaluated the ORIF with screw in condylar head fracture, and they found that out of 7 patients, only 1 patient had facial nerve paralysis which was temporary and that resolved in 3 months follow-up period.

Iatrogenic injury to parotid gland is rare but can happen during surgical approach to condyle. In the present study, 2 patients developed infection and salivary fistula from parotid gland which required prolonged administration of aspiration, anti-sialagogues, antibiotics and repeated pressure dressings. It took around one month for its resolution, thus increasing cost and morbidity associated with surgery. These patients were managed conservatively with pressure bandage and anticholinergic (Glycopyrrolate: 1 mg, twice a day). By careful dissection throughout the procedure, we can minimize these complication. Infection resolved with use of antibiotics and none of the patients required exploration of surgical site and hardware removal.

CH fractures are challenging to treat because of difficulties in reduction and fixation of small displace fragments and there might be steep learning curve. All the cases were operated by a single surgeon in our study. Intraoperative imaging was not used to confirm reduction and fixation as it could be directly seen. The length of screws was also determined intraoperatively with help of depth gauge. The results with open treatment were unsatisfactory, but a long-term review with a large sample size is required.

The present study describes the outcome of use of UARPs in management of CH fracture and comparison of functional outcome and complications of surgical procedure between open and closed group. The results of the present study rejected the hypothesis that the ultrasound activated resorbable pins are superior than conservative management in management for adult mandible condylar head fractures. There was more resorption of medial CH fragment in open group as compared to closed group. The closed treatment group had better outcome. Open treatment poses the patients to the risks and complications of surgery.