clinical applications of bioabsorbable materials inzygomatico-orbital fractures: 7 years experience

Vol. 21, No: 2 April -June 2009 267

JBMSJournal of the Bahrain Medical Society

Case Reports

IntroductionThe golden standard for rigid fixation in the maxillofacial region remains the use of titanium osteosynthesis systems1. Their applications have been since the late 19th century and remains2. It is well documented that titanium has several advantages to supports its use. This includes their tissue biocompatibility, adaptability, stress tolerance and fractures stability3. However, titanium poses some

Ghassan Dhaif, FFDRCsI1, Isa Mattar, Mfds RCsI2, Nadia Al-sekri, BDs3

Clinical Applications of Bioabsorbable Materials in Zygomatico-orbital Fractures: 7 years experience

امللخ�ص

الهدف من الدرا�سة: تهدف هذه الدرا�سة اإىل التقييم ال�سر يري والثبات اجلراحي ال�ستخدام املواد املثبتة لك�سور عظمة الوجه

وعظام احلجاج با�ستخدام طريقتني خمتلفتني.

املواد والطرق:مت فح�ض 107 مري�ض م�ساب بك�سور يف عظمة الوجه وعظام احلجاج خالل الفرتة مابني يناير 2001 لغاية

دي�سمرب 2007 والذين مت عالجهم با�ستخدام PDLLA Martin �سفائح قابلة لالمت�سا�ض. وقد مت تق�سيم احلاالت اإىل جمموعتني.

املجموعة االأوىل )45( واملجموعة الثانية )62(. عمل تقييم للعالج وامل�ساعفات لكلى املجموعتني.

اأ�سيبوا بالتهابات مري�ض )6.6 %( 2 اآية م�ساعفات, مقابل النتائج:يف املجموعة االأوىل هناك 41 )%93.4( مت عالجهم دون

ب�سيطة يف االأن�سجة املحيطة. وقد مت ا�ستخدام 72 �سفيحة تثبيت مع 300 براغي جراحية, وقد اأنك�سر منهم 55 )%18.4 ( براغي

اإ�سافة اإىل 4)%5.6( �سفيحة تثبيت قد مت تغيريهم.

يف املجموعة الثانية, مت عالج 70 ك�سر وذلك با�ستخدام 570 براغي باالأ�ستعانه بجهاز املوجات فوق ال�سوتية, اإ�سافة اإىل 135

�سفيحة تثبيت. وقد مت تغيري 2)%1.5( �سفيحة تثبيت نتيجة االنحناء ال�سديد اإ�سافة اإىل )%1.7(10 براغي مت تثبيتهم بطريقة

خاطئة.

اال�ستنتاج: اإن ال�سفائح القابلة لالمت�سا�ض من املمكن ا�ستخدامها بنجاح تام يف ك�سور عظمة الوجه وعظام احلجاج ومب�ساكل

ب�سيطة فيما بعد العالج, كما اأننا ن�ستطيع اال�ستعا�سة بهذا كبديل ل�سفائح التيتانيوم.

AbstractPurpose: A retrospective study to review the clinical outcome and stability of biodegradable materials for the fixing zygomatico-orbital fractures using two different methods.

Materials and Methods: One hundred and seven consecutive patients with zygomatico-orbital fractures during the period of January 2001 to December 2007 were treated using PDLLA Martin biodegradable hardware. They were included into two groups. Study group 1)n=45( in which predrilling and tap was done before screw insertion. Study group 2)n=62( where sonicweld pin were used. It was done in accordance with the development of new hardware. Treatment outcome and complications recorded for both groups.

Results: In group 1, forty-two )93.4%( patients had uneventful healing while three)6.6%( patients developed mild soft tissue reaction. Seventy-two plates and 300 tapped screws used. Fifty-five)18.4%( screws were broken and 4)5.6%( plates replaced for margin shear. In group 2, 62 patients had seventy fractures were treated using 570 sonic weld pins and 135 plates. There were 2)1.5%( plates replaced due to excessive bending and 10)1.7%( screws improperly welded.

Conclusion: Biodegradable osteosynthesis materials can be safely used for treatment of zygomatico-orbital factures with minimal postoperative complications and can replace titanium hardware.

1. Oral & Maxillofacial Surgery Department, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.2, 3. Dental Department, Salmaniya Medical Complex, Kingdom of Bahrain, Manama, Bahrain.

concern among investigators due to their side effects. It includes interference with growth when used in pediatric population, high potential for infection, thermal sensitivity, titanium tissue deposition, palpable or prominent hardware, wound dehiscence, interference with future radiographic imaging and need for subsequent second operation for hardware removal4,5. These concerns necessitate the development of materials with similar advantages of titanium but avoid the drawbacks.

268 Vol. 21, No: 2 April -June 2009


Ghassan Dhaif, Isa Mattar, Nadia Al-Sekri

Recent developments in biodegradable osteosynthesis materials and polymers have made significant improvement in their mechanical properties which expanded its applications in Craniomaxillofacial region6. These include fractures of the facial bones, mandible, pediatric population and orthognathic surgery7,8.

However, biodegradable still have posed some concerns about their expanded applications8. Most of these concerns arise from their inherent weak mechanical properties and inability to withstand the heavy occlusal forces especially if used in the lower third of the facial skeleton. Recent developments in the commercially available biodegradable hardware have overcome these concerns to some extent but future research in this field will further enhance the quality of these materials to expand their usage.

The zygomatic and orbital region is non-load bearing area with minimal muscle pull, thus making it favorable for biodegradable hardware. Furthermore, the skin overlying these structures is very thin, thus making any hardware palpable and the need for second operation for implant removal. This is contradictory to the case with biodegradable plates where the hardware will be absorbed, avoiding the need for further surgical intervention.

This is a retrospective study of 107 consecutive patients with facial fractures who treated at the Department of Oral & Maxillofacial Surgery, Salmaniya Medical Complex, Bahrain during the period 2001-2007 using biodegradable fixation material to analyze its clinical outcome and fracture stability.

Materials And MethodsOne hundred and seven consecutive patients who were treated at the department with zygomatico-orbital fractures between the period January 2001 and December 2007 using biodegradable fixation material were retrospectively analyzed. Exclusion criteria were the presence of comminuted fracture and the presence of infection in the fracture site. Cases with zygomatico-orbital fractures with other associated injuries e.g. frontal bone or nasal bone fractures were included in the study group but no considerations were given to their surgical outcome.

Patients were divided into two groups: Group 1 )n = 45( who had Martin resorbable plates and screws coplolymer of poly-D-Lactide acid )Poly D,L-Lactic acid( base material which needs predrilling and tap prior to the insertion of the screw.

Group 2 )n = 62( had same resorbable plating system but with the use of sonicweld pin made of pure coplolymer of poly-D-Lactide acid )Poly D,L-Lactic acid( that avoids the complexity of tapping and screw breakage.

All patients had conventional radiographic assessment using Occipito-mental view, Water’s view and coronal computerized tomography )CT( scans.

The treatment commenced within 24-72 hours of presentation depending on the head injury status of the patient.

Biodegradable HardwareThe KLS-Martin® resorbable plates and screws consisted of self reinforced PDLLA, an amorphous complex polymer chains material

composed of 50% D-lactide and 50% L-lactide. These implants are biologically compatible and do not initiate irritation, inflammation or foreign body reactions. Implant degradation takes place through hydrolysis. It initiates the process by water absorption of the surrounding tissue fluids “hydrolysis”. The degradation process is then initiated by continuous breakdown of the long polymer chains into shorter and simpler molecules9. Subsequently, the metabolic process transforms the D-lactides and L-lactides into carbon dioxide and water, which is excreted by the kidneys. The complete degradation process is highly predictable and leaves no residues in the body. The initial tensile strength of the biodegradable implants is 1700±200 MPa, as reported by the manufacturer. These mechanical strength properties are retained for eight to ten weeks. This will ensure uneventful fracture healing and bone regeneration. The material has been reported to resorb slowly, maintaining nearly 80% of their initial strength for eight to ten weeks. The bulk resorption takes 18-30 weeks and is completely resorbed by 12-18 months. The plates are flexible and can be bent and adapted to conform to the fixed bone by the use of the Xcelsior® water bath.

The resorbable system uses 1.0 mm thick plates and the sonic pins are available in diameters of 1.6 mm and 2.1 mm. The screws are self-retaining and can be conveniently picked up with the tip of the sonotrode. The sonicweld technology utilizes the principle of ultrasonic bone saw whereby micro-vibration generated by a defined ultrasonic frequency. This in turn will melt the pin’s outer surface. The end result will be sonic pin screw gliding into the predrilled hole.

The advantages of the utilization of sonic welder are the avoidance of tapping which can produce larger hole or can cause screw fracture. This is quite common occurrence in the previous system. This will usually complicate the procedure.

surgical ProcedureAll surgical procedures were done under general anesthesia. All zygomatic fractures were initially approached through standard Gillies temporal approach for zygomatic bone elevation. Subciliary incision used to approach infraorbital rim and orbital floor, and lateral eyebrow incision utilized if deemed necessary for Fronto-Zygomatic )FZ( suture fixation )Figure 3(. Supraorbital rim and medial orbital wall fractures are usually exposed via hemi-coronal or bicoronal flap.

Reduction of the fracture is achieved by the use of Gillies elevator and stabilization is done with biodegradable plates and screws. Most patients with zygomatico-orbital fractures were stabilized with 2-point fixation at the FZ-suture and infraorbital rim. Four holes plate is used at the FZ-suture and curved orbital rim plate with a minimum of 4 holes, two on each side of fracture were used.

In case of orbital floor fracture, which necessitates reconstruction, an autogenous bone graft from outer calvarium is applied to the orbital floor. The calvarial bone graft were fixed using L-shaped biodegradable plates after being bend suitable to conform with the shape of the calvarial bone and orbital floor.

All patients received intravenous antibiotic therapy of )Cefurixime 1.5gm three times daily for 3 days( and dexamethazone 8 mg three times daily and gradually tapered.




Figure 3. An-8-year-old girl sustained severely dislocated zygomatico-orbital fracture as a result of RTA with large orbital floor defect. Sonic weld pins and biodegradable osteosynthesis were used

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Ghassan Dhaif, Isa Mattar, Nadia Al-Sekri

The patients seen postoperatively for assessment at 1 week, after 1, 3, 6, and 12 month periods. Immediate postoperative conventional radiographs were taken after surgery and at 3, 6 and 12 months postsurgery.

ResultsOne hundred and seven patients 102 )95.3%( male; 5)4.7%( female( with 122 orbito-zygomatic fractures enrolled into the study. The patient’s age ranged from 2 to 55 years, with a mean of 35 years of age. Road traffic accident was the most common cause of injury, 90)84.1%( patients, followed by industrial falls, 12)11.2%( patients and interpersonal violence 5)4.7%( patients.

Group 1 consisted of 45 patients )40 males and 5 females( and age ranged from 2 to 49 years, with a mean of 29.5 years of age. There were 52 fractures included in this group.

The total number of resorbable plates used for this group was 72, and the number of screws was 300. There were 55)18.4%( screws broken during insertion into the predrilled and tapped hole. Four plates )5.6%( were replaced due to margin shear.

In this group, uneventful healing during the entire follow-up period was observed in 42 patients )93.4%(, whereas 3 patients )6.6%( developed mild soft tissue reaction which resolved by antibiotic therapy.

Group 2 consisted of 62 male patients and age ranged from 5 to 55 years with a mean of 32.5 years of age. There were 70 fractures.

One hundred and thirty five resorbable plates used in this group with 570 sonic pins. Two plates )1.5%( had to be replaced due to fractures from excessive bending. Ten screws )1.7%( were improperly welded resulting in bending. No sonic pin break reported in this group.

The operative time differs significantly with group 2 taking less time compared to group 1 irrespective of the experience of the operator. This is merely due to the complexity of the hardware application process and breakage of the hardware. The time taking, however, varies between cases according to the difficulty of the case and number of resorbable plates used.

The follow-up period for this group was free from any postoperative complications. Three patients experienced objectionable plate projection on palpation in the first 3 months which resolved afterwards.

In both groups, satisfactory radiographic evidence of bone healing was registered in all patients after 1 year. There was no case of malunion or nonunion observed and facial appearance was satisfactory in all patients. None of the studied patients needed scar revision or secondary cosmetic surgery.

Discussion Conventional osteosynthesis techniques in oral and maxillofacial surgery remain the use of titanium implants despite its inherent limitations10. Around 20%-45% of titanium plates are routinely removed for a variety of reasons including infection, plate exposure, soft tissue reaction, screws loosening, wound dehiscence, thermal sensitivity and interference with growth11.

The development of biodegradable hardware sought to overcome the drawbacks of titanium hardware. Despite their advantages, titanium hardware remains superior in some aspects including its tensile strength and stress tolerance especially in the high load-bearing areas.

The resorbable fixation materials carry major advantages including lack of interference with skeletal growth i.e. can be used safely for paediatric facial skeleton, lack of interference with radiographic imaging, lack of thermal conductivity, low infection rate, lack of tissue deposition12.

A variety of resorbable fixation materials have been developed with different composition. The most commonly used resorbable fixation materials are Poly-L-lactic acid )PLLA(, Poly-D-Lactide plates )PDLA( and Poly Glycolic Acid )PGA( plate screws13.

The use of the resorbable plating system is increasing in various Craniomaxillofacial surgeries including paediatric facial fractures, fracture mandible, midface fractures, orbit, and frontal bone fractures, and orthognathic surgery14.




The degradation process of the biodegradable hardware takes place in two stages. Initially, water will penetrate the polymer, thus attacking the chemical bond in the amorphous phase. This will lead to conversion of the long polymer into water soluble chain. Later, the macrophages will release certain enzymes which will result in degradation of the short chain polymer. The resultant product will be excreted as water and carbon dioxide15. This gradual hydrolysis and metabolic process takes place in the liver.

The process of the degradation of the biodegradable hardware gives the advantages of minimal or insignificant inflammatory reaction, therefore, minimizing the production of an infection. Therefore, a lower complication rate as compared to titanium fixation16, 17.

In our presented data, there were several disadvantages of PDLLA biodegradable hardware; they were larger and bulkier in comparison with their titanium counterpart. The operative time for the group 1 was somewhat longer than group 2. This is partly due to the fact that tapping was not needed and the screws were sonic weld without the need for screw insertion. This has minimized the operating time as well as the breakage of the screws and the cost of the hardware. In addition, in group 1 tapping may cause disturbance and displacement of the fracture.

It should bear in mind that the application of biodegradable hardware is still controversial especially in load bearing areas and areas of great muscle pull18. However, promising results in the literature still supports the application of this product in mandibular fractures and orthognathic surgery with claimed stability comparable to titanium hardware19.

selected cases of mandibular fractures especially paediatric, and areas of minimal muscle pull and displacement, and selected cases of orthognathic surgery cases were treated in our department utilizing PDLLA biodegradable hardware but were not included in our study. We can’t generalize its use prior to long-term clinical study to support this hypothesis. Furthermore, patient’s compliance is essential in order to minimize failure and plate breakage.

The handling of this material requires special precaution as they are mechanically softer and weaker compared to titanium. Unlike titanium, where firm pressure is required during screw insertion, biodegradable sonic weld pin needs only gentle touch without any forces. Care must be taken when fixing thin bone to minimize displacement. In group 1, screw head were broken due to learning curve and application of excessive torque.

ConclusionBiodegradable osteosynthesis hardware can be safely applied for fixing zygomatico-orbital fractures with minor postoperative complications which can resolve spontaneously or with minimal interventions.

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clinical applications of bioabsorbable materials inzygomatico-orbital fractures: 7 years experience

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