Comparison of collagen membranes and polydioxanone for reconstruction of the orbital floor after fractures

The Use of Functional Biomaterials in Aesthetic and Functional Restoration in Orbital Surgery

The integration of functional biomaterials in oculoplastic and orbital surgery is a pivotal area where material science and clinical practice converge. This review, encompassing primary research from 2015 to 2023, delves into the use of biomaterials in two key areas: the reconstruction of orbital floor fractures and the development of implants and prostheses for anophthalmic sockets post-eye removal. The discussion begins with an analysis of orbital floor injuries, including their pathophysiology and treatment modalities. It is noted that titanium mesh remains the gold standard for orbital floor repair due to its effectiveness. The review then examines the array of materials used for orbital implants and prostheses, highlighting the dependence on surgeon preference and experience, as there are currently no definitive guidelines. While recent innovations in biomaterials show promise, the review underscores the need for more clinical data before these new materials can be widely adopted in clinical settings. The review advocates for an interdisciplinary approach in orbital surgery, emphasizing patient-centered care and the potential of biomaterials to significantly enhance patient outcomes.

The Statistical Fragility of Orbital Fractures: A Systematic Review of Randomized Controlled Trials

BACKGROUND

The P value has often been used as a tool to determine the statistical significance and evaluate the statistical robustness of study findings in orthopedic literature. The purpose of this study is to apply both the fragility index (FI) and the fragility quotient (FQ) to evaluate the degree of statistical fragility in orbital fracture literature. We hypothesized that the dichotomous outcomes within the orbital fracture literature will be vulnerable to a small number of outcome event reversals and will be statistically fragile.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), the authors identified all dichotomous data for randomized controlled trials (RCTs) in orbital fracture literature and performed a PubMed search from 2000 to 2022. The FI of each outcome was calculated through the reversal of a single outcome event until significance was reversed. The FQ was calculated by dividing each FI by study sample size. The interquartile range (IQR) was also calculated for the FI and FQ.

RESULTS

Of the 3,329 studies screened, 28 met the criteria with 10 RCTs evaluating orbital fractures included for analysis. A total of 58 outcome events with 22 significant (P < .05) outcomes and 36 nonsignificant (P ≥ .05) outcomes were identified. The overall FI and FQ for all 58 outcomes was 5 (IQR: 4 to 5) and 0.140 (IQR: 0.075 to 0.250), respectively. Fragility analysis of statistical significant outcomes and nonsignificant outcomes had an FI of 3.5 with no IQR and 5 (IQR 4-5), respectively. All of the studies reported a loss to follow-up data, where 20% (2) was greater than the overall FI of 5.

CONCLUSION

The orbital fracture literature provides treatment guidance by relying on statistical significant results from RCTs. However, the RCTs in the orbital fracture peer-reviewed literature may not be statistically stable as previously thought. The sole reliance of the P value may depict misleading results. Thus, we recommend standardizing the reporting of the P value, FI, and FQ in the orbital fracture literature to aid readers in reliably drawing conclusions based on fragility outcome measures impacting clinical decision-making.

Polydioxanone Membrane Compared with Collagen Membrane for Bone Regeneration

Guided bone regeneration (GBR) is an approach that induces osteopromotion through the regenerative membranes. These barriers exhibit bioactive behavior and mechanical function. Polydioxanone is a synthetic option, already used in medicine and dentistry, with good results in bone regeneration. This study aimed to evaluate bone repair in critical defects in rat calvaria using a polydioxanone membrane (Plenum^® Guide) compared with a commercially available collagen-based membrane (Bio-Gide^®). The bone defects were filled with Plenum^® Osshp, a synthetic bone graft, hydroxyapatite:β-tricalcium phosphate, 70:30%, Group PG (Plenum^® Guide + Plenum^® Osshp), and Group BG (Geistlich Bio-Gide^® + Plenum^® Osshp). The specimens were submitted to immunohistochemical (RUNX2 and OPN), gene expression (RUNX2, IBSP, and VEGF), histometric, and microtomography analyses after 07, 15, 30, and 60 days postoperative. PG group showed greater immunolabeling area for RUNX2 and OPN, higher gene expression of VEGF (3.15 ± 0.85), and IBSP (24.9 ± 0.59). However, there was no statistical difference between groups in the histometric analysis regarding the percentage of connective tissue PG (0.83 ± 0.45), BG (0.70 ± 0.34), neoformed bone PG (0.60 ± 0.4), BG (0.65 ± 0.51), and remaining biomaterial PG (0.84 ± 0.31), BG (0.91 ± 0.33). In addition, there was no statistical difference between groups by micro-CT analysis. The absorbable-synthetic membrane, Plenum^® Guide, is an effective membrane for guided bone regeneration.

Polydioxanone-Based Membranes for Bone Regeneration

Resorbable synthetic and natural polymer-based membranes have been extensively studied for guided tissue regeneration. Alloplastic biomaterials are often used for tissue regeneration due to their lower immunoreactivity when compared with allogeneic and xenogeneic materials. Plenum^® Guide is a synthetic membrane material based on polydioxanone (PDO), whose surface morphology closely mimics the extracellular matrix. In this study, Plenum^® Guide was compared with collagen membranes as a barrier material for bone-tissue regeneration in terms of acute and subchronic systemic toxicity. Moreover, characterizations such as morphology, thermal analysis (Tm = 107.35 °C and crystallinity degree = 52.86 ± 2.97 %, final product), swelling (thickness: 0.25 mm ≅ 436% and 0.5 mm ≅ 425% within 24 h), and mechanical tests (E = 30.1 ± 6.25 MPa; σ = 3.92 ± 0.28 MPa; ε = 287.96 ± 34.68%, final product) were performed. The in vivo results revealed that the PDO membranes induced a slightly higher quantity of newly formed bone tissue than the control group (score: treated group = 15, control group = 13) without detectable systemic toxicity (clinical signs and evaluation of the membranes after necropsy did not result in differences between groups, i.e., non-reaction -> tissue-reaction index = 1.3), showing that these synthetic membranes have the essential characteristics for an effective tissue regeneration. Human adipose-derived stem cells (hASCs) were seeded on PDO membranes; results demonstrated efficient cell migration, adhesion, spread, and proliferation, such that there was a slightly better hASC osteogenic differentiation on PDO than on collagen membranes. Hence, Plenum^® Guide membranes are a safe and efficient alternative for resorbable membranes for tissue regeneration.

Incorporation of a polydioxanone absorbable plate in the successful repair of an iatrogenic oronasal fistula in a dog

CASE DESCRIPTION

A 10-year-old castrated male Siberian Husky that had undergone complete excision of an oral plasmacytoma was evaluated because of development of a large oronasal fistula following failure of primary defect repair.

CLINICAL FINDINGS

Clinical examination findings for the dog were unremarkable. The dog was receiving nutrition via an esophagostomy tube, which had been placed at the time of mass excision. The dog was notably head shy. Intraoral examination following sedation revealed a large (approx 25 × 20-mm) oronasal fistula, which was oriented craniocaudally in the long axis and located at the rostral aspect of the soft palate. Maturation of tissues had been allowed following failure of the primary repair, and an epithelialized border was identified circumferentially.

TREATMENT AND OUTCOME

10 weeks after mass excision, revision surgery involving 2-layer closure augmented with a polydioxanone plate was performed. At a recheck examination 21 days after revision surgery, near-complete healing of the closure site with no repair compromise was evident, and the dog had returned to oral food intake. A follow-up evaluation 40 weeks later revealed complete healing, with a single 1-mm defect at the medial aspect of the left maxillary dental arcade, as a result of suspected repeated trauma at the level of teeth 209 and 210. This defect was not associated with any clinical abnormalities.

CLINICAL RELEVANCE

The outcome for this dog indicated that use of a polydioxanone plate offers a means of robust, long-lasting, and absorbable augmentation of a traditional 2-layer repair of an oronasal fistula in this species.

Clinical Outcome Following Surgical Repair of Small Versus Large Orbital Floor Fractures Using Polyglactin 910/Polydioxanone (Ethisorb®)

The aim of this retrospective study was to evaluate the clinical outcome of surgical management of small versus large, isolated orbital floor fractures (OFFs) using polyglactin 910/polydioxanone (Ethisorb^®). Covering a four-year period (2010-2013), all records concerning midfacial fractures with involvement of the orbit were screened. Isolated fractures of the orbital floor as well as combined injuries of the orbital floor and medial wall that had been treated surgically using polyglactin 910/polydioxanone (Ethisorb^®) were included. Patients underwent a preoperative, a postoperative, and a late ophthalmologic assessment. The clinical outcomes of surgically managed small OFFs up to 2 cm² were statistically analyzed and compared to clinical results in larger defects. The final sample included 61 patients (25 women, 36 men). Fractures up to 2 cm² were found in 33 patients (54.1%), whereas 28 patients (45.9%) suffered from OFFs larger than 2 cm². The clinical outcomes did not significantly differ between both sample categories, and statistical analysis showed a power of 0.91 to detect a potentially existing difference. On final examination, 52 patients were free of any clinical symptoms, whereas minor issues were found in seven subjects, and two patients suffered from severe impairment. In conclusion, polyglactin 910/polydioxanone (Ethisorb^®) seems to be a suitable material for surgical repair of both small and large OFFs.

Factors Influencing Postsurgical Diplopia in Orbital Floor Fractures and Prevalence of Other Complications in a Series of Cases

PURPOSE

We conducted a review of orbital fractures treated in our hospital over a period of 4 years. We reviewed several complications of such fractures, especially the relationship of postsurgical diplopia with different presurgical variables: age, gender, type of fracture, fracture area, coronal and sagittal diameter of fracture, fractured floor area, time to surgery, presence of muscle herniation, and presence of muscle entrapment.

PATIENTS AND METHODS

Fractures involving the orbital floor remain a controversial issue in terms of surgical treatment and the time from trauma to surgery. Surgical indications are divided into esthetic and functional, and they greatly differ from one medical center to another. We observed that the variables that influence postoperative complications varied in the different studies reviewed. Postsurgical diplopia is one of the most important complications, and its relationship with presurgical variables was the focus of this study. For the purpose of this study, we performed bivariate and multivariate analyses, accepting P < .05 as significant.

RESULTS

According to the multivariate analysis, postsurgical diplopia was only associated with trapdoor fractures, regardless of all other variables, especially if these fractures were operated on after 48 hours. In addition, the bivariate analysis showed that fractures involving muscle herniation resulted in less diplopia and a better prognosis if operated on before 48 hours. However, these results were not statistically significant.

CONCLUSIONS

Surgery performed within 48 hours of trauma statistically improves fractures with true muscle entrapment and also, fractures with muscle hernation (although in this fractures, the improvement is not statistically significant).

[Facial trauma and injury in children]

Facial traumas are common in children but often unconsidered. Facial injury is responsible of impressive bleeding because of the rich vascularization of the face; this bleeding is often underestimated because of the immediate arterial vasoconstriction that is very strong for children. The blood volume is 80ml/kg for a newborn, with a total of 250ml, reaching 70ml/kg at one year of age. The evaluation must be rigorously performed due to the risk of a sudden decompensation. Regarding the wounds, the primary repair must be performed directly neat or optimal in case of damaged tissues. The rule is to keep maximum of the integrity and to limit debridement. Careful repair often requires general anesthesia, especially in young children, to facilitate a perfect joining of the edges and of the mucocutaneous lines. Losses of substance should be treated by directed cicatrization. Flaps are never performed in children as a first intention for reasons developed below. Given the elasticity of the facial skeleton, fractures require a brutal shock to occur, but the clinical signs can be misleading. For instance, too specific and sometimes ignored, fractures can show weakly symptomatic signs : the fractures of the condylar and the orbital floor, with their respective complication that are temporomandibular bone ankylosis and definitive diplopia. Possible children abuse should be suspected in case of different age lesions and discrepancies between the told story and types of injuries. Once the vital urgency is eliminated, the orbital emergency should be first considered in facial traumas within the ophthalmology specialty because wounds and contusions of the globe are often under-evaluated and threaten the vision. The second emergency is the orbital floor fracture in its 'trapdoor' type, specific to the child. Combined with a motionless eye and uncontrollable vomiting, this is the second true urgency because it involves the prognosis of the oculomotricity and requires emergency surgery. Finally, dental trauma should not be overlooked because of their functional and aesthetic consequences. Primary cicatrization is usually rapid but scars remain inflammatory during a long time. The risk of hypertrophy exists in case of contusions and lacerations associated with wounds but also during puberty and in some locations. Age interfere with the result because growth will either improve or worsen the initial result, depending on the location and mechanism. The secondary specialized and prolonged managing and monitoring is capital on the functional, aesthetic and psychological points of view.

Is there an ideal implant for orbital reconstructions? Prospective 64-case study

The aim of this study was to compare the effectiveness of porous polyethylene, titanium mesh, and castor oil-derived biopolymer randomized in orbital reconstructions of defects larger than 1 cm in length on the inferior and medial walls. A total of 63 patients (64 orbits) were evaluated to determine the presence of diplopia, enophthalmos ocular motility, and infraorbital nerve paraesthesia in both the preoperative and postoperative periods. The surgeons' opinions of the ease in handling the implants were also obtained after each procedure. The patients were divided into 3 groups: 17 received porous polyethylene, 21 received castor oil-derived biopolymer, and 26 received titanium mesh. In the preoperative period, 30 patients experienced enophthalmos, 11 experienced diplopia, and 12 experienced ocular motility. Ninety days after the orbital reconstruction, 6 cases of enophthalmos persisted, as did 2 cases of diplopia and 2 cases of ocular motility. Ten patients developed some type of postoperative complication. Material removal was required in only 1 case. Regardless of the size of the defect, the materials used were found to be effective for reconstructing orbital volume; they were also found to offer ease in handling and stabilization.

Controversies in the Management of the Trauma Patient

Facial trauma is a significant cause of morbidity in the United States. Despite the large volume of trauma surgeries at most academic institutions, there is still controversy regarding management of many traumatic injuries. The literature lacks clear-cut best practices for most fractures. In orbital trauma, there is debate about the optimal timing of repair, preferred biomaterial to be used, and the utility of evaluation afterward with intraoperative computed tomographic scan. In repair of mandible fractures, there is debate regarding open versus closed reduction of subcondylar fractures, or alternatively, endoscopic repair.

Mechanical properties of collagen membranes modified with pores--are they still sufficient for orbital floor reconstruction?

Adequate mechanical strength is essential for materials used to reconstruct the orbital floor, and collagen membranes have recently been suggested for the repair of isolated fractures of the orbital floor. However, their mechanical properties after modification with pores for increased drainage of blood into the sinus have not been sufficiently investigated. We have tested the mechanical resistance of polydioxanone foils (PDS) to distortion and compared it with that of 3 resorbable collagen membranes (Smartbrane(®), Bio-Gide(®), and Creos(®)) in mint condition and when artificially aged (3 weeks, 6 weeks, and 8 weeks) after modification with pores (diameter 2mm) in a standard configuration (n=12 in each group). PDS and Creos(®) had comparable initial values for mechanical resistance of about 2.3N/mm(2), and Bio-Gide(®) and Smartbrane(®) had about 20% and 80% lower initial mechanical resistance, respectively. All materials tested had lower values after artificial ageing. After eight weeks of ageing, PDS lost about 99% of its initial mechanical resistance, Creos(®) about 66%, Bio-Gide(®) about 30%, and Smartbrane(®) about 95%. After 3 weeks the mechanical resistance in all groups was significantly less than the initial values (p=0.05), but there was no difference between samples aged artificially for 6 compared with 8 weeks. The mechanical resistance of the tested materials was not influenced by the presence of pores in a standard configuration and was in the appropriate range for moderate fractures of the orbital floor. We recommend further clinical investigations of collagen membranes modified with pores.

Reconstruction of the orbital floor with polydioxanone: a long-term clinical survey of up to 12 years

Fractures of the orbital floor are common in injured patients, who often require operation to prevent complications and, among other materials, polydioxanone is widely used. The aim of this study was to evaluate the long-term outcomes of fractures of the orbital floor that had been reconstructed with polydioxanone foil. A total of 101 patients (73 men and 28 women) who had reconstruction of the orbital floor for defects of 2cm(2) or smaller with polydioxanone implants, over a mean (SD) time period of 8 (2) years were evaluated. Sensitivity of the infraorbital nerve, ocular motility, and diplopia were evaluated and correlated with perioperative values. Persistent hyperaesthesia was found in 15 patients, whereas in another 15 the hyperaesthesia recovered completely over time. Three patients had double vision during follow-up. Twenty patients with preoperative diplopia had no persistent double vision postoperatively, and 15 patients with disturbed ocular motility recovered completely. Two patients had persistently disturbed motility, and one patient had enophthalmos. There was a significant association between hyperaesthesia preoperatively and postoperatively (p= 0.005). In most patients reconstruction of the orbital floor with polydioxanone was successful. Long-term complications such as diplopia, compromised bulbar motility, and hyperaesthesia of the cheek were seen in a few cases, but might not have been solely related to the use of polydioxanone.

Controversies in orbital reconstruction--I. Defect-driven orbital reconstruction: a systematic review

In the 1980s, computed tomography was introduced as an imaging modality for diagnosing orbital fractures. Since then, new light has been shed on the field of orbital fracture management. Currently, most surgeons are likely to repair orbital fractures based on clinical findings and particularly on data obtained from computed tomography scans. However, an important but unresolved issue is the fracture size, which dictates the extent and type of reconstruction. In other fields of trauma surgery, an increasing body of evidence is stressing the importance of complexity-based treatment models. The aim of this study was to systematically review all articles on orbital reconstruction, with a focus on the indication for surgery and the defect size and location, in order to identify the reconstruction methods that show the best results for the different types of orbital fractures.

A technique to correct severe lateral crural concavity: adjunctive use of a polydioxanone plate during lateral crural reverse plasty

BACKGROUND

Severe lateral crura concavity (LCC) can lead to an important deformity of the nasal tip and to external nasal valve insufficiency. The lower lateral crural reverse plasty represents a valuable technique for the correction of severe LCC, but often requires additional cartilage to gain more alar rim support.

METHODS

We describe a modified version of the reverse plasty, in which a polydioxanone plate is sutured as a strut at the dome junction to increase alar rim support. We report our experience with this technique in 10 women (age range 24-56 years).

RESULTS

The procedure was performed in eight primary rhinoplasties and in two cases alone without rhinoplasty. All patients had aesthetic complaints, whereas three had obstructive symptoms. Eight patients had unilateral problems. A one-year follow-up was completed in 100 % of patients. There were no surgical complications and all patients had optimal short and long-term aesthetic and functional results.

CONCLUSION

Acikel C (Aesthetic Plast Surg 36:862-865, 2012) The adjunctive use of a polydioxanone plate during lateral crural reverse plasty was feasible and led to satisfying functional and cosmetic long-term results in patients with severe LCC. This surgical maneuver appears reproducible and emerges as an alternative way of gaining stronger support during lateral crura reverse plasty while avoiding additional tissue.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Mechanical properties of collagen membranes: are they sufficient for orbital floor reconstructions?

INTRODUCTION

The most common reconstruction materials for orbital floor fractures are PDS (polydioxanone) foil and titanium meshes. These materials have advantages and disadvantages. Therefore, new materials are needed to improve surgical outcomes.

MATERIALS AND METHODS

Three resorbable collagen membranes (Smartbrane(®), BioGide(®), Creos(®)) were tested for their mechanical properties (puncture strength) in mint and artificially aged (3, 6, 8 weeks) conditions and were compared to PDS foil, titanium meshes (0.25 mm, 0.5 mm) and human orbital floors (n = 7).

RESULTS

The following puncture strengths were evaluated: human orbital floor, 0.81 ± 0.49 N/mm(2); 0.25 mm titanium mesh, 5.36 ± 0.25 N/mm(2); 0.5 mm titanium mesh, 16.08 ± 5.17 N/mm(2); Smartbrane, 0.74 ± 0.31 N/mm(2); BioGide, 1.65 ± 0.45 N/mm(2); and Creos, 2.81 ± 0.27 N/mm(2). After artificial aging, the puncture strengths were significantly reduced (p ≤ 0.05) at 3, 6 and 8 weeks as follows: Smartbrane, 0.05 ± 0.03 N/mm(2), 0.03 ± 0.02 N/mm(2), and 0.01 ± 0.01 N/mm(2), respectively; BioGide, 0.42 ± 0.06 N/mm(2), 0.41 ± 0.12 N/mm(2), and 0.32 ± 0.08 N/mm(2), respectively; and Creos, 2.02 ± 0.37 N/mm(2), 1.49 ± 0.42 N/mm(2), and 1.36 ± 0.42 N/mm(2), respectively.

CONCLUSION

The tested materials showed sufficient puncture strength for orbital floor reconstruction in mint condition. Moreover, after artificial aging, the Creos and BioGide membranes showed sufficient resistance, while Smartbrane showed equivocal data after eight weeks. Therefore, collagen membranes have adequate properties for further in vivo investigations for orbital floor reconstructions.

Biomaterials for repair of orbital floor blowout fractures: a systematic review

PURPOSE

To evaluate the reported use and outcomes of implant materials used for the restoration of post-traumatic orbital floor defects in adults.

MATERIALS AND METHODS

A systematic search of the English literature was performed in the databases of PubMed, Cochrane Library, and EMBASE. The study selection process was adapted from the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, and 55 articles complied with the study inclusion criteria. The primary outcome measures were diplopia, enophthalmos, graft extrusion/displacement, and infection related to the graft material. The secondary outcome measures were infraorbital paresthesia, orbital dystopia, orbital soft tissue entrapment, and donor-site complications.

RESULTS

Of 55 articles, 41 (74.5%) evaluated were retrospective case series, 9 (16.4%) were retrospective case-control studies, 3 (5.5%) were controlled trials, and 2 (3.6%) were prospective case series. Autogenous graft materials were predominantly used in 19 studies, alloplastic materials were used in 33 studies, and the remaining 3 articles reported on allogeneic materials. Overall, 19 different types of implant materials were used in 2,483 patients. Of 827 patients with diplopia before surgery, 151 (18.3%) had diplopia postoperatively. Of 449 patients with enophthalmos before surgery, 134 (29.8%) had enophthalmos postoperatively. Only 2 patients (0.1%) and 14 patients (0.6%) had graft extrusion/displacement and infection related to the graft material, respectively; alloplastic biomaterials were used in all of these cases.

CONCLUSIONS

All graft materials used were successful to variable degrees because all studies reported improvement in terms of the recorded outcome measures. A guideline for choice of implant material based on defect size was developed.

[Children orbital floor fracture: retrospective study, about 34 cases]

INTRODUCTION

Orbital fractures represent 30 % of children facial fractures. Nausea and vomiting are more predictive of entrapment than local trauma stigmatisms. Entrapment and diplopia are more frequent in adults. Delay for surgery is unclear in literature varying from 6 hours to days. The aim of this study is to summarise the aspects of orbital floor fractures in children with regard to clinical and radiological presentation, management, and outcomes.

PATIENTS AND METHODS

We conducted a retrospective study including 34 children presenting isolated orbital floor fracture. Clinical, radiological, ophthalmological, surgical data and outcomes were analyzed.

RESULTS

Mean age was 9.4 years. In 15% of cases, no local stigmatism of trauma was present. Entrapment fracture was the most frequent, with 81% of fat or muscles entrapment. In all, 27% of the patient had residual diplopia. Residual diplopia developed after trap-door fracture with muscle entrapment and a more than 24 hours delay for surgery.

CONCLUSION

Trap-door fracture is frequent in childhood population. Clinical diagnosis can be difficult. However, surgical treatment should be considered before 24 hours to avoid complication as residual diplopia.

Biomaterials and implants for orbital floor repair

Treatment of orbital floor fractures and defects is often a complex issue. Repair of these injuries essentially aims to restore the continuity of the orbital floor and to provide an adequate support to the orbital content. Several materials and implants have been proposed over the years for orbital floor reconstruction, in the hope of achieving the best clinical outcome for the patient. Autografts have been traditionally considered as the "gold standard" choice due to the absence of an adverse immunological response, but they are available in limited amounts and carry the need for extra surgery. In order to overcome the drawbacks related to autografts, researchers' and surgeons' attention has been progressively attracted by alloplastic materials, which can be commercially produced and easily tailored to fit a wide range of specific clinical needs. In this review the advantages and limitations of the various biomaterials proposed and tested for orbital floor repair are critically examined and discussed. Criteria and guidelines for optimal material/implant choice, as well as future research directions, are also presented, in an attempt to understand whether an ideal biomaterial already exists or a truly functional implant will eventually materialise in the next few years.