[Bone harvesting from the iliac crest]

[Synthetic bone replacement substances]

Bone substitute materials have been successfully used for bone defects in orthopedics and trauma surgery for a long time; however, there are cases, especially in bone defects with a critical size, in which the treatment is complicated. Nowadays, multiple bone substitute materials are available. Autologous cancellous bone grafts remain the gold standard among the bone replacement materials; however, donor site morbidity and the limited availability of autologous cancellous bone represent restrictions for autologous bone grafting. Allogeneic cancellous bone grafts have also been successfully for years in the treatment of bone defects; however, infection rates of more than 10% have been described for the use of allogeneic cancellous bone. By introducing synthetic bone substitutes further alternatives are currently available to the user for the individual treatment of bone defects. The aim of this study is to demonstrate the advantages and disadvantages of various synthetic bone substitute materials.

Functionalization of Synthetic Bone Substitutes

Bone substitutes have been applied to treat osseous defects for a long time. To prevent implant related infection (IRI) and enhance bone healing functionalized biomaterials, antibiotics and osteoinductive substances have been introduced. This study gives an overview of the current available surface-coated bone substitutes and provides an outlook for future perspectives.

Can polyaryletherketone cage be used to achieve union and maintain correction in anterior calcaneal lengthening osteotomy for treatment of flexible flatfoot?

A structural graft is often used to maintain correction and achieve union after anterior calcaneal lengthening osteotomy for treatment of flexible flatfoot. Autograft, the current gold standard, is limited in availability and configuration and is associated with donor site morbidity in as much as 48%, whereas the alternative allograft carries risks of disease transmission and collapse. Polyaryletherketone cage, with a healing rate similar to that of autograft, high stability, and no donor-site morbidity, has been used in spine surgery. However, its use has not been documented in foot and ankle surgery. We reviewed 15 patients with painful flatfeet after failure of conservative treatment who were treated by anterior calcaneal lengthening osteotomy using polyaryletherketone cage instead of bone graft. Minimum follow-up was 1 year (average, 1.27 years; range, 1-1.5 years). The male-female ratio was 1:1.5 (six males, nine females). Mean age at time of surgery was 10.8 ± 1.7 years (range, 8-13.5 years). Minimum follow-up was 1 year (average, 1.27 years; range, 1-1.5 years). Nine patients had a unilateral procedure and three had a simultaneous bilateral procedure, for a total of 15 operated feet (seven right and eight left). The paired t-test result was statistically significant in comparison of radiographic measurements at presurgery and postsurgery with P value <0.001. All cases showed full union clinically and radiographically at last follow-ups and no complications occurred. Our data suggest that polyaryletherketone cage may be used as a structural graft option for anterior calcaneal lengthening osteotomy.

A large animal model for standardized testing of bone regeneration strategies

Background

The need for bone graft substitutes including those being developed to be applied together with new strategies of bone regeneration such as tissue engineering and cell-based approaches is growing. No large animal model of bone regeneration has been accepted as a standard testing model. Standardization may be the key to moving systematically towards better bone regeneration. This study aimed to establish a model of bone regeneration in the sheep that lends itself to strict standardization and in which a number of substances can be tested within the same animal. To this end the caudal border of the ovine scapula was used as a consistent bed of mineralized tissue that provided sufficient room for a serial alignment of multiple experimental drill holes.

Results

The findings show that for the sake of standardization, surgery should be restricted to the middle part of the caudal margin, an area at least 80 mm proximal from the Glenoid cavity, but not more than 140 mm away from it, in the adult female Land Merino sheep. A distance of 5 mm from the caudal margin should also be observed.

Conclusions

This standardized model with defined uniform defects and defect sites results in predictable and reproducible bone regeneration processes. Defects are placed unilaterally in only one limb of the animal, avoiding morbidity in multiple limbs. The fact that five defects per animal can be evaluated is conducive to intra-animal comparisons and reduces the number of animals that have to be subject to experimentation.

Mid-term outcome following revision surgery of clavicular non- and malunion using anatomic locking compression plate and iliac crest bone graft

Background

Treatment of clavicular non- and malunion is still challenging. Current surgical procedures often result in frustrating functional outcome along with high-grade subjective impairment and increased rates of revision surgery. However, the combination of biological augmentation with vital bone graft and a biomechanically sufficient fixation system seems to be a promising concept of treatment.

Methods

In this retrospective study, 14 patients with a mean age of 44 years (26–67 years) suffering from non-union (n = 11) and/or malunion (n = 3) of the clavicle were enrolled. All patients were surgically treated using an anatomical precontoured locking compression plate (LCP) and autologous iliac crest bone graft. Functional outcome was assessed using the age- and sex-specific relative Constant Score.

Results

Mean follow-up was 27 months (range 12–44 months). The relative Constant Score significantly improved from preoperative 61 ± 8 (43–72) to 82 ± 10 (65–100) points at the final follow-up examination (p < 0.05). All patients showed bony union radiographically. One patient presented with a re-fracture of the clavicle nearly 3 years after revision surgery and 5 weeks after implant removal. Secondary fractures at the donor site of the anterior superior iliac spine were recorded in two patients.

Conclusions

Iliac crest bone graft and anatomic locking plate fixation allow for a safe and adequate stabilization and radiographical bony union in non- and malunions of the clavicle with a high degree of patient satisfaction. However, secondary fractures of the anterior superior iliac spine constitute relevant complications and the time of hardware removal should be considered carefully.

Isolated Subtalar Distraction Arthrodesis Using Porous Tantalum: A Pilot Study

BACKGROUND

During reconstructive procedures of the hindfoot, a structural graft is often needed to fill gaps. To eliminate donor site morbidity and limited availability of autografts, porous tantalum was used.

METHODS

Eighteen patients who underwent subtalar joint distraction arthrodesis by means of trabecular metal augment were reviewed retrospectively. The results were evaluated clinically, with the American Orthopaedic Foot & Ankle Society (AOFAS) score and the visual analog scale (VAS) for pain, and were assessed radiologically. The mean follow-up period was 18 months.

RESULTS

Computed tomography showed sound fusion. There was a marked increase in AOFAS scores and a decrease in VAS scores. Arthrodesis was achieved in all cases with no major postoperative complications. Radiographically, there was a marked increase in all measured parameters (talocalcaneal angle, talocalcaneal height, talar declination angle), and the intraoperatively achieved correction was maintained at the last follow-up visit.

CONCLUSION

Our data suggest that porous tantalum may be used as a structural graft option for subtalar arthrodesis.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Mesenchymal stem cells overexpressing Ihh promote bone repair

Background

Indian hedgehog (Ihh) signaling pathway is known to play key roles in various aspects of normal endochondral bone development. This study tested the potential roles of high Ihh signaling in the context of injury-induced bone regeneration.

Methods

A rabbit tibia defect model was established to test the effects of the implant of Ihh/mesenchymal stem cells (MSCs)/scaffold complex. Computed tomography (CT), gross observation, and standard histological and immunohistological techniques were used to evaluate the effectiveness of the treatment. In vitro studies with MSCs and C3H10T1/2 cells were also employed to further understand the cellular and molecular mechanisms.

Results

We found that the implanted Ihh/MSCs/scaffold complex promoted bone repair. Consistently, in vitro study found that Ihh induced the upregulation of chondrocytic, osteogenic, and vascular cell markers, both in C3H10T1/2 cells and MSCs.

Conclusions

Our study has demonstrated that high Ihh signaling in a complex with MSCs enhanced bone regeneration effectively in a clinically relevant acute injury model. Even though the exact underlying mechanisms are still far from clear, our primary data suggested that enhanced chondrogenesis, osteogenesis, and angiogenesis of MSCs at least partially contribute to the process. This study not only has implications for basic research of MSCs and Ihh signaling pathway but also points to the possibility of direct application of this specific paradigm to clinical bone repair.

Electronic supplementary material

The online version of this article (doi:10.1186/s13018-014-0102-7) contains supplementary material, which is available to authorized users.

Donor site reconstruction in iliac crest tricortical bone graft: surgical technique

BACKGROUND AND PURPOSE

Autogenous bone grafts from the iliac crest are frequently harvested for autologous bone transplantation, because this is still the gold standard in the treatment of many bone defects. However, significant donor site morbidity must be considered. We have developed a simple method to treat the bone defect in the donor site in order to reduce some of the morbidity. In this method, the bone defect size and shape determines its application.

METHOD

After the conventional method of tricortical bone harvesting from the iliac crest, bone defect is repaired by means of a transversal fence of appropriate thin tricortical chips obtained from the posterior lateral wall of the bone defect itself. The mechanical stability of this fence results from impactation of the ends of the tricortical chips into both lateral cancellous bone walls of the repaired bone defect. Thus, no hardware is required, and both the bone defect and ilium contour are restored.

RESULTS

This simple method allows ilium bone defect healing and bone contour recovery after graft harvest, by using the same gold standard graft. Although not much time is necessary to reconstruct the donor site, the bone defect size and shape determine its application.

INTERPRETATION

This method may be a recommendable option for bone defect reconstruction after iliac crest tricortical bone graft harvest as the primary procedure. The advantages of this technique are bone defect healing and bone contour restoration with prevention of a visible deformity over the groin, with no foreign material insertion, thus avoiding additional cost.

General principles for the regeneration of bone and cartilage

For the regeneration of bone and cartilage, mesenchymal stem cells are currently used invitro and in-vivo. For bone, the existence of viable cells, scaffolds, mechanical environment, growth factors and vascularization are of paramount importance. Mesenchymal stem cells can be harvested from the bone marrow using minimally invasive techniques. Centrifugation can increase the number of transplanted cells per volume. The use of cell therapy is under current clinical investigation and the benefit from these systems has to be proven in level I studies. For cartilage, current techniques recruiting stem cells from the subchondral bone have been demonstrated to be nearly as effective as autologous chondrocyte transplantation, requiring less invasive surgery. The efficacy of mesenchymal stem cell concentrates remains to be proven. There is high potential for tissue engineered joint surfaces to become an option for joint surface defects and degeneration.

Evaluation of autologous platelet concentrate for intertransverse lumbar fusion

INTRODUCTION

The aim of the study was to analyze if the adding of autologous platelet concentrate (APC) to a mixture of local autograft plus tricalcium phosphate and hidroxiapatite (TCP/HA) would improve the fusion rate in posterolateral lumbar fusion.

MATERIALS AND METHODS

A prospective, controlled, blinded, non-randomized clinical trial was carried out in 107 patients affected by degenerative lumbar pathology. The study group consisted of 67 patients, in which autologous platelet concentration was added to a mixture of autologous local bone graft and TCP/HA. A control group of 40 patients with same pathology and surgical technique but without APC addition was used to compare the fusion mass obtained. By means of plain X-rays, a blinded evaluation of the intertransverse fusion mass quality at twelve and twenty-four months was made according to type A (bilateral uniform mass), type B (unilateral uniform mass) and type C (irregular or lack bilateral mass). Patients with type C were regarded as pseudoarthrosis.

RESULTS

In the study group 17 patients had lack or irregular fusion mass (25.4%) versus three patients in the control group (7.5%), which was statistically significant.

CONCLUSIONS

This study shows that the adding of autologous platelet concentration to a mixture of autologous bone graft plus TCP/HA has decreased our rates of posterolateral lumbar fusion.

Biphasic bone substitute and fibrin sealant for treatment of benign bone tumours and tumour-like lesions

PURPOSE

Bone defects resulting from tumour resection or curettage are most commonly reconstructed with autologous bone graft which is associated with limited availability and donor site morbidity. Recent research has focussed on synthetic biomaterials as bone graft substitutes. The aim of this study was to assess the safety and efficiency of a bone substitute as an alternative for autologous bone in the treatment of benign bone tumours and tumour-like lesions.

METHODS

In the present study, a biphasic ceramic (60% HA and 40% β-TCP) combined with a fibrin sealant was used to reconstruct defects in 51 patients after curettage of benign bone tumours or tumour-like lesions. Patient age ranged from eight to 68 years (mean 29.7), defect size from 2 cm(3) to 35 cm(3) (mean 12.1), and time of follow-up from one to 56 months (mean 22.7).

RESULTS

Radiologic analysis showed complete bony defect consolidation in 50 of 51 patients after up to 56 months. No postoperative fractures were observed. Revision surgery had to be performed in one case. Histological analysis showed new bone formation and good biocompatibility and osseointegration of the implanted material.

CONCLUSION

In summary, the biphasic ceramic in combination with fibrin sealant was proven an effective alternative to autologous bone grafts eliminating the risk of donor site morbidity for the patient.

Spinning around or stagnation - what do osteoblasts and chondroblasts really like?

Objective

The influcence of cytomechanical forces in cellular migration, proliferation and differentation of mesenchymal stem cells (MSCs) is still poorly understood in detail.

Methods

Human MSCs were isolated and cultivated onto the surface of a 3 × 3 mm porcine collagen I/III carrier. After incubation, cell cultures were transfered to the different cutures systems: regular static tissue flasks (group I), spinner flasks (group II) and rotating wall vessels (group III). Following standard protocols cells were stimulated lineage specific towards the osteogenic and chondrogenic lines. To evaluate the effects of applied cytomechanical forces towards cellular differentiation distinct parameters were measured (morphology, antigen and antigen expression) after a total cultivation period of 21 days in vitro.

Results

Depending on the cultivation technique we found significant differences in both gen and protein expression.

Conclusion

Cytomechanical forces with rotational components strongly influence the osteogenic and chondrogenic differentiation.

Can porous tantalum be used to achieve ankle and subtalar arthrodesis?: a pilot study

A structural graft often is needed to fill gaps during reconstructive procedures of the ankle and hindfoot. Autograft, the current gold standard, is limited in availability and configuration and is associated with donor-site morbidity in as much as 48%, whereas the alternative allograft carries risks of disease transmission and collapse. Trabecular metal (tantalum), with a healing rate similar to that of autograft, high stability, and no donor-site morbidity, has been used in surgery of the hip, knee, and spine. However, its use has not been documented in foot and ankle surgery. We retrospectively reviewed nine patients with complex foot and ankle arthrodeses using a tantalum spacer. Minimum followup was 1.9 years (average, 2 years; range, 1.9-2.4 years). Bone ingrowth into the tantalum was analyzed with micro-CT in three of the nine patients. All arthrodeses were fused clinically and radiographically at the 1- and 2 year followups and no complications occurred. The American Orthopaedic Foot and Ankle Society score increased from 32 to 74. The micro-CT showed bony trabeculae growing onto the tantalum. Our data suggest tantalum may be used as a structural graft option for ankle and subtalar arthrodesis. All nine of our patients achieved fusion and had no complications. Using tantalum obviated the need for harvesting of the iliac spine.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

[Pain therapy after spinal surgery]

A dorsal approach during spinal surgery offers the possibility to distribute drugs directly to the nerve root or epidurally. This can be done via a single intraoperative dose or by placing an epidural catheter. A safe and effective analgesia can thereby be achieved. As placement is done under visual control, no major complications are to be expected. In nerve root compressions, additional local application of steroids and preoperative gabapentin seems sensible. No advantage of preemptive administration of other analgesics can be determined. Another problem, especially of ventral fusions, is the commonly needed autologous pelvic bone grafts. Here the local application of local anesthetics or opioids makes sense. In transthoracic approaches epidural analgesia is recommended by thoracic surgeons, but this is difficult to perform especially in children with deformities. Furthermore it is generally important not to compromise neuralgic controls by analgesic measures.

Evaluation of donor site pain after anterior iliac crest harvesting for cervical fusion: a prospective study on 50 patients

BACKGROUND

Autologous anterior iliac crest bone graft is still widely considered the gold standard for anterior cervical fusion after discectomy or corporectomy. Postoperative pain at the donor site is one of the main disadvantages to this technique. This prospective study aimed to evaluate pain at the donor site, after careful, standardised bone harvesting.

METHODS

From March 2003 to March 2004, a prospective study was performed in a single neurosurgical department on 50 patients who underwent anterior iliac crest bone harvesting using a standard and careful surgical technique. During a one year follow-up, patient donor site pain was assessed with a Visual Analogous Scale (VAS) at 2, 7 and 60 days from surgery and finally, by a telephone interview, at one year.

FINDINGS

The duration of time in hospital ranged from 4 to 9 days. On the 2(nd) day after surgery, pain, according to the VAS score, was recorded as being >7 by 4 patients (8%), 5-7/10 by 27 patients and >5/10 in 19 cases. On the 7(th) day after surgery, none of the patients reported any VAS > 7, 1 patient's VAS score was 6/10 and 49 patients had a VAS < 5. At 2 month follow-up, 45 patients were completely without pain (VAS 0) and the remaining 5 had a VAS < 5. At one year, 46 patients reported no pain (one patient was lost to follow-up); three continued to have pain <5 in VAS scale.

CONCLUSIONS

After harvesting of bone from the iliac crest, using a standardised approach based on anatomised principles, most patients do not experience persisting pain at the donor site.

Die Überbrückung von posttraumatischen Knochendefekten

Bony defects as a result of injury or disease can be caused by a variety of conditions such as acute injury, fall fractures in osteoporotic patients or tumours and congenital malformations of the musculoskeletal system which necessitate the resection of affected parts of the bone. This results in a multitude of defects concerning localisation and specificity as well as a number of conditions involving both hard and soft tissue structures and various situations of different patients. A reasonable classification of defects which is relevant for practical purposes includes four basic types: defects of the spine, metaphyseal defects as well as partial and complete diaphyseal defects of long bones. A variety of options exists for the treatment of these conditions. The aim of all efforts is to reinstall the integrity of affected structures long-lastingly and dependably and at the same time guarantee the normal function of joints involved. In addition to classical treatment strategies which involve the use of autogenous and allogenous corticocancellous bone grafts a great number of bone substitute materials can also be used. Further options lie in complex reconstructive methods such as the transport of whole segments or the transplantation of vascularised bone grafts. The field of new regenerative strategies including tissue engineering as well as stem cell and gene therapy holds great promise for the future. The aim of this review is to derive a ranking from the evaluation of biological and mechanical characteristics for the treatment of posttraumatic defects.

Regeneration statt Reparation

Autogenous bone transfer is still regarded as the "golden standard" for many indications in oral and cranio-maxillofacial surgery. In this overview, the status of the autogenous bone is re-evaluated under consideration of current research results, clinical long-term studies, risks and safety of the patient as well as the costs. Due to the further development of modern bone substitute materials, which reveal in parts superior long-term results for special indications, the routine use of autogenous bone has to be critically reviewed.