Summary Statement

Supercritical fluid (SCF) sterilization produces clean and osteoconductive allograft bone capable of healing a critical-sised bony defect. SCF treated graft induces an increased anabolic response and decreased catabolic reponse compared to gamma irradiated graft.

Introduction: diaphyseal bone defect is one of the most difficult challenge in Orthopaedic and Traumatologic Surgery. One of the techniques for reconstruction of bone defect described by Masquelet is a two-stage procedure: induction of a membrane around a ciment spacer and autologous cancellous bone graft with external fixator. The aim of the study is to evaluate a modified technique with intramedullary nailing for tibial bone defect.

Materials and Methods: between 2001 and 2006, 13 patients presented important tibial bone defect. On radiological examination, the mean size was 18,5 cm³ (12–30 cm³). Initially, there were 12 opened fractures (1 Gustilo 1, 2 Gustilo II, 9 fractures Gustilo III), and one osteomyelitis following a compartment syndrome. The mean age of the patients at the procedure was 41 years old (18–74). Our modified technique was as follows:

several debridment and stabilization of bone fragments with a temporary external fixator

10 patients had hyperbare oxygenotherapy. All patients were evaluated radiographically and by physical examination. using SF-36 questionnary.

Results: There was no amputation but 4 complications. There were 3 deep infections: one just between the 2 stages and one 2 years after the second stage: both were treated by nail exchange and adapted intra-venous anti-biotherapy. The third one was the complete bone graft resorption because of an infection just after the second stage (the only failure of the method). The fourth complication is the nonunion 13 months after the second stage: nails has broken and has been changed. Bone healing was obtained in 12 patients at mean follow-up was 32 months (12–69). They were able to walk 4,3 months after bone grafting. 8 patients answered to the SF-36 questionnary: overall function was limited with a mean score of 99.8.

Discussion: and conclusion: Our modified technique gave satisfactory results at medium term. Nailing, comparing to external fixator, offers a better stabilization of bone fragments, better control of axis and length of lower limb, and an easier access for plastic surgery and nurse care. Others bone reconstruction treatment like ilizarov bone transport, free vascularized fibula fiap or allograft are still possible if failure. However, the rate of deep infections are quite high (4/13) may be questionable. Sacrifice of intramedullary blood supply and the difficulties to confirm union on radiological exams are still problematics.

The need for an artificial scaffold in very large bone defects is clear, not only to limit the risk of graft harvesting, but also to improve clinical success. The use of custom osteoconductive scaffolds made from biodegradable polyester and ceramics can be a valuable patient friendly option, especially in case of a concomitant infection. Multiple types of scaffolds for the Masquelet procedure (MP) are available, however these frequently demonstrate central graft involution when defects exceed a certain size and the complication rates remains high. This paper describes three infected tibial defect nonunions with a segmental defect over ten centimeters long treated with a customized 3D printed polycaprolactone-tricalcium phosphate (PCL-TCP) cage in combination with biological adjuncts. Three male patients, between the age of 37 and 47, were treated for an infected tibial defect nonunion after sustaining Gustilo grade 3 open fractures. All had a segmental midshaft bone defect of more than ten centimeters (range 11–15cm). First stage MPs consisted of extensive debridement, external fixation and placement of anterior lateral thigh flaps (ALT). Positive cultures were obtained from all patients during this first stage, that were treated with specific systemic antibiotics during 12 weeks. The second stage MP was carried out at least two months after the first stage. CT scans were obtained after the first stage to manufacture defect-specific cages. In the final procedure a custom 3D printed PCL-TCP cage (Osteopore, Singapore) was placed in the defect in combination with biological adjuncts (BMAC, RIA derived autograft, iFactor and BioActive Glass). Bridging of the defect, assessed at six months by CT, was achieved in all cases. SPECT-scans 6 months post-operatively demonstrated active bone regeneration, also involving the central part of the scaffold. All three patients regained function and reported less pain with full weight-bearing. This case report shows that 3D printed PCL-TCP cages in combination with biological adjuncts is a novel addition to the surgical treatment of very large bone defects in (infected) posttraumatic nonunion of the tibia. This combination could overcome some of the current drawbacks in this challenging indication

Introduction. A significant burden of disease exists with respect to critical sized bone defects; outcomes are unpredictable and often poor. There is no absolute agreement on what constitutes a “critically-sized” bone defect however it is widely considered as one that would not heal spontaneously despite surgical stabilisation, thus requiring re-operation. The aetiology of such defects is varied. High-energy trauma with soft tissue loss and periosteal stripping, bone infection and tumour resection all require extensive debridement and the critical-sized defects generated require careful consideration and strategic management. Current management practice of these defects lacks consensus. Existing literature tells us that tibial defects 25mm or great have a poor natural history; however, there is no universally agreed management strategy and there remains a significant evidence gap. Drawing its origins from musculoskeletal oncology, the Capanna technique describes a hybrid mode of reconstruction. Mass allograft is combined with a vascularised fibula autograft, allowing the patient to benefit from the favourable characteristics of two popular reconstruction techniques. Allograft confers initial mechanical stability with autograft contributing osteogenic, inductive and conductive capacity to encourage union. Secondarily its inherent vascularity affords the construct the ability to withstand deleterious effects of stressors such as infection that may threaten union. The strengths of this hybrid construct we believe can be used within the context of critical-sized bone defects within tibial trauma to the same success as seen within tumour reconstruction. Methodology. Utilising the Capanna technique in trauma requires modification to the original procedure. In tumour surgery pre-operative cross-sectional imaging is a pre-requisite. This allows surgeons to assess margins, plan resections and order allograft to match the defect. In trauma this is not possible. We therefore propose a two-stage approach to address critical-sized tibial defects in open fractures. After initial debridement, external fixation and soft tissue management via a combined orthoplastics approach, CT imaging is performed to assess the defect geometry, with a polymethylmethacrylate (PMMA) spacer placed at index procedure to maintain soft tissue tension, alignment and deliver local antibiotics. Once comfortable that no further debridement is required and the risk of infection is appropriate then 3D printing technology can be used to mill custom jigs. Appropriate tibial allograft is ordered based on CT measurements. A pedicled fibula graft is raised through a lateral approach. The peroneal vessels are mobilised to the tibioperoneal trunk and passed medially into the bone void. The cadaveric bone is prepared using the custom jig on the back table and posterolateral troughs made to allow insertion of the fibula, permitting some hypertrophic expansion. A separate medial incision allows attachment of the custom jig to host tibia allowing for reciprocal cuts to match the allograft. The fibula is implanted into the allograft, ensuring nil tension on the pedicle and, after docking the graft, the hybrid construct is secured with multi-planar locking plates to provide rotational stability. The medial window allows plate placement safely away from the vascular pedicle. Results. We present a 50-year-old healthy male with a Gustilo & Anderson 3B proximal tibial fracture, open posteromedially with associated shear fragment, treated using the Capanna technique. Presenting following a fall climbing additional injuries included a closed ipsilateral calcaneal and medial malleolar fracture, both treated operatively. Our patient underwent reconstruction of his tibia with the above staged technique. Two debridements were carried out due to a 48-hour delay in presentation due to remote geographical location of recovery. Debridements were carried out in accordance with BOAST guidelines; a spanning knee external fixator applied and a small area of skin loss on the proximal medial calf reconstructed with a split thickness skin graft. A revision cement spacer was inserted into the metaphyseal defect measuring 84mm. At definitive surgery the external fixator was removed and graft fixation was extended to include the intra-articular fragments. No intra-operative complications were encountered during surgeries. The patient returned to theatre on day 13 with a medial sided haematoma. 20ml of haemoserous fluid was evacuated, a DAIR procedure performed and antibiotic-loaded bioceramics applied locally. Samples grew Staphylococcus aureus and antibiotic treatment was rationalised to Co-Trimoxazole 960mg BD and Rifampicin 450mg BD. The patient has completed a six-week course of Rifampicin and continues on suppressive Co-Trimoxazole monotherapy until planned metalwork removal. There is no evidence of ongoing active infection and radiological evidence of early union. The patient is independently walking four miles to the gym daily and we believe, thus far, despite accepted complications, we have demonstrated a relative early success. Conclusions. A variety of techniques exist for the management of critical-sized bone defects within the tibia. All of these come with a variety of drawbacks and limitations. Whilst acceptance of a limb length discrepancy is one option, intercalary defects of greater than 5 to 7cm typically require reconstruction. In patients in whom fine wire fixators and distraction osteogenesis are deemed inappropriate, or are unwilling to tolerate the frequent re-operations and potential donor site morbidity of the Masqualet technique, the Capanna technique offers a novel solution. Through using tibial allograft to address the size mismatch between vascularised fibula and tibia, the possible complication of fatigue fracture of an isolated fibula autograft is potentially avoidable in patients who have high functional demands. The Capanna technique has demonstrated satisfactory results within tumour reconstruction. Papers report that by combining the structural strength of allograft with the osteoconductive and osteoinductive properties of a vascularised autograft that limb salvage rates of greater than 80% and union rates of greater than 90% are achievable. If these results can indeed be replicated in the management of critical-sized bone defects in tibial trauma we potentially have a treatment strategy that can excel over the more widely practiced current techniques

Introduction. Reconstruction of large defect of tibia following infection is considered as one of the most difficult problem facing the orthopaedic surgeon. Amputation with modern prosthetic fitting is a salvage procedure to treat big defects, which gives a functional result with unpredictable psychological impact. Materials & Methods. Between January 2000 and January 2021, 56 patients (30 males and 26 females) with big defects following infection and post traumatic injury of the tibia were treated. The mean age of the patients at the time of surgery was 20.5 years (4–24 years). The fibula was mobilized medially to fill the defect and was fixed with Ilizarov fixator. The average size of the defects reconstructed was 18.5 cm (17–20 cm). Results. The average time for complete union was 8.6 months (range, 5–9 months). At final follow-up all patients had fully united. We found leg length discrepancy in 52 patients and that was corrected by re-lengthening of the solid new regenerate bone. Conclusions. The Ilizarov method has been shown to be an effective method of treating Tibialization of fibula for reconstruction of big tibial defects

Our previous rat study demonstrated an ex vivo-created “Biomimetic Hematoma” (BH) that mimics the intrinsic structural properties of normal fracture hematoma, consistently and efficiently enhanced the healing of large bone defects at extremely low doses of rhBMP-2 (0.33 μg). The aim of this study was to determine if an extremely low dose of rhBMP-2 delivered within BH can efficiently heal large bone defects in goats. Goat 2.5 cm tibial defects were stabilized with circular fixators, and divided into groups (n=2-3): 2.1 mg rhBMP-2 delivered on an absorbable collagen sponge (ACS); 52.5 μg rhBMP-2 delivered within BH; and an empty group. BH was created using autologous blood with a mixture of calcium and thrombin at specific concentrations. Healing was monitored with X-rays. After 8 weeks, femurs were assessed using microCT. Using 2.1 mg on ACS was sufficient to heal 2.5 cm bone defects. Empty defects resulted in a nonunion after 8 weeks. Radiographic evaluation showed earlier and more robust callus formation with 97.5 % (52.5 μg) less of rhBMP-2 delivered within the BH, and all tibias were fully bridged at 3 weeks. The bone mineral density was significantly higher in defects treated with BH than with ACS. Defects in the BH group had smaller amounts of intramedullary and cortical trabeculation compared to the ACS group, indicating advanced remodeling. The results confirm that the delivery of rhBMP-2 within the BH was much more efficient than on an ACS. Not only did the large bone defects heal consistently with a 40x lower dose of rhBMP-2, but the quality of the defect regeneration was also superior in the BH group. These findings should significantly influence how rhBMP-2 is delivered clinically to maximize the regenerative capacity of bone healing while minimizing the dose required, thereby reducing the risk of adverse effects

Introduction. Aneurysmal bone cysts commonly found in lower limbs are locally aggressive masses that can lead to bony erosion, instability and fractures. This has major implications in the lower limbs especially in paediatric patients, with potential growth disturbance and deformity. In this case series we describe radical aneurysmal bone cyst resection and lower limb reconstruction using cable transport and syndesmosis preservation. Materials & Methods. Case 1 - A 12-year-old boy presented with a two-week history of atraumatic right ankle pain. An X-ray demonstrated a distal tibia metaphyseal cyst confirmed on biopsy as an aneurysmal bone cyst. The cyst expanded on interval X-rays from 5.5cm to 8.5cm in 9 weeks. A wide-margin en-bloc resection was performed leaving a 13.8cm tibial defect. A cable transport hexapod frame and a proximal tibial osteotomy was performed, with syndesmosis screw fixation. The transport phase lasted 11 months. While in frame, the boy sustained a distal femur fracture from a fall. The femur and the docking site were plated at the same sitting and frame removed. At one-year post-frame removal he is pain-free, with full ankle dorsiflexion but plantarflexion limited to 25 degrees. He has begun graduated return to sport. Results. Case 2 - A 12-year-old girl was referred with a three-month history of lateral left ankle swelling. X-ray demonstrated an aneurysmal bone cyst in the distal fibula metaphysis. The cyst grew from 4.2 × 2.3cm to 5.2 × 3.32cm in 2 months. A distal fibula resection (6.2cm) with syndesmosis fixation and hexapod cable transport frame were undertaken. The frame was in situ for 13 weeks and during this time she required an additional osteotomy for premature consolidation and had one pin site infection. After 13 weeks a second syndesmosis screw was placed, frame removed, and a cast applied. 3 months later she had fibular plating, BMAC and autologous iliac crest bone graft for slow union. At 3 years post-operative she has no evidence of recurrence, is pain-free and has no functional limitation. Conclusions. We describe two cases of ankle syndesmosis preservation using cable transport for juxta-articular aneurysmal bone cysts. This allows wide resection to prevent recurrence while also preserving primary ankle stability and leg length in children. Both children had a minor complication, but both had an excellent final outcome. Cable bone transport and prophylactic syndesmosis stabilization allows treatment of challenging juxta-articular aneurysmal bone cysts about the ankle. These techniques are especially useful in large bone defects

Introduction. Bone transport and distraction osteogenesis have been shown to be an effective treatment for significant bone loss in the tibia. However, traditional methods of transport are often associated with high patient morbidity due to the pain and scarring caused by the external frame components transporting the bone segment. Prolonged time in frame is also common as large sections of regenerate need significant time to consolidate before the external fixator can be removed. Cable transport has had a resurgence with the description of the balanced cable transport system. However, this introduced increasingly complex surgery along with the risk of cable weave fracture. This method also requires frame removal and intramedullary nailing, with a modified nail, to be performed in a single sitting, which raised concern regarding potential deep infection. An alternative to this method is our modified cable transport system with early intramedullary nail fixation. Internal cables reduce pain and scarring of the skin during transport and allow for well controlled transport segment alignment. The cable system is facilitated through an endosteal plate that reduces complications and removes the need for a single-stage frame removal and nailing procedure. Instead, the patients can undergo a pin-site holiday before nailing is performed using a standard tibial nail. Early intramedullary nailing once transport is complete reduces overall time in frame and allows full weight bearing as the regenerate consolidates. We present our case series of patients treated with this modified cable transport technique. Methodolgy. Patients were identified through our limb reconstruction database and clinic notes, operative records and radiographs were reviewed. Since 2019, 8 patients (5 male : 3 female) have undergone bone transport via our modified balanced cable transport technique. Average age at time of transport was 39.6 years (range 21–58 years) with all surgeries performed by the senior author. Patients were followed up until radiological union. We recorded the length of bone transport achieved as well as any problems, obstacles or complications encountered during treatment. We evaluated outcomes of full weight bearing and return to function as well as radiological union. Results. 4/8 bone defects were due to severely comminuted open fractures requiring extensive debridement. All other cases had previously undergone fixation of tibial fractures which had failed due to infection, soft tissue defects or mal-reduction. The mean tibial defect treated with bone transport was 41mm (range 37–78mm). From the start of cable transport to removal of external fixator our patients spent an average of 201 days in frame. 7/8 patients underwent a 2-week pin-site holiday and subsequent insertion of intramedullary nail 2 weeks later. One patient had sufficient bony union to not require further internal fixation after frame removal. 10 problems were identified during treatment. These included 4 superficial infections treated with antibiotics alone and 5 issues with hardware, which could be resolved in the outpatient clinic. 1 patient had their rate of transport slowed due to poor skin quality over the site of the regenerate. 4 obstacles resulted in a return to theatre for additional procedures. 1 patient had a re-do corticotomy and 3 had revision of their internal cable transport constructs due to decoupling or screw pull out. 1 patient had residual ankle joint equinus following treatment which required an Achilles tendon lengthening procedure. Another patient underwent treatment for DVT. There were no deep infections identified and no significant limb length discrepancies or deformities. Conclusions. Overall, we have found that our modified balanced cable transport technique has allowed for successful bone transport for significant defects of the tibia. We have learned from the obstacles encountered during this case series to avoid unnecessary return trips to theatre for our future transport patients. The internal cable system allowed all patients to complete their planned transport without excessive pin tract scarring or pain. Early conversion to intramedullary nail allowed for a shorter time in frame with continued full weight bearing as the regenerate consolidated. No metalwork failure or deformity has occurred in relation to docking site union. All patients have made a good return to pre-operative function during their follow-up period with no evidence of late complications such as deep infection

Background. Tissue engineering strategies to heal critical-size bone defects through direct bone formation are limited by incomplete integration of grafts with host bone and incomplete vascularisation. An alternative strategy is the use of cartilage grafts that undergo endochondral ossification. Endochondral cartilages stimulate angiogenesis and are remodeled into bone, but are naturally found in only small quantities. We sought to develop engineered endochondral cartilage grafts using human osteoarthritic (OA) articular chondrocytes. Methods. Study approval was obtained from our human and animal ethics review committees. Human OA cartilage was obtained from discarded tissues from total knee replacements. Scaffold-free engineered grafts were generated by pelleting primary or passaged chondrocytes, followed by culture with transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein 4. Samples were transplanted into immunocompromised mice either subcutaneously or into critical-size tibial defects. Grafts derived from passaged chondrocytes from either of two patients (64 year old and 68 year old men) where implanted into tibial defects in five mice. Bone formation was assessed with histology after four weeks of implantation. Results. Engineered cartilage grafts generated from passaged OA chondrocytes underwent endochondral ossification after implantation either subcutaneously or in bone. The grafts bridged tibial defects, integrating with bone proximally and distally in all cases. Portions of the graft were remodeled into woven bone, which spanned the defects in two animals. Unmodified OA cartilage and engineered grafts formed from primary chondrocytes did not undergo endochondral ossification in vivo. Conclusions. Human OA chondrocytes adopt an endochondral phenotype after passaging and TGF-β superfamily treatment. Engineered endochondral cartilage grafts can integrate with host bone, undergo ossification, and heal critical-size long-bone defects in a mouse model. Level of Evidence. Animal study. Disclosure. A patent application on this technology has been filed

Aims. Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA. Methods. This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living. Results. Small micromotions (mean < 12 µm) were found to occur at the bone-implant interface for all loading cases with or without a stem. Stem inclusion was associated with lower micromotion, however these reductions were too small to have any clinical significance. Peak interface micromotion, even when the cone is used without a stem, was too small to effect osseointegration. The maximum difference occurred with stair descent loading. Stress concentrations in the bone occurred around the inferior aspect of each implant, with the largest occurring at the end of the long stem; these may lead to end-of-stem pain. Stem use is also found to result in stress shielding in the bone along the stem. Conclusion. When a metaphyseal cone is used at rTKA to manage uncontained posterior or medial defects of up to 10 mm depth, stem use may not be necessary. Cite this article:Bone Joint Res. 2020;9(4):162–172

Introduction. Various methods to manage medial tibial defects in primary total knee arthroplasty (TKA) have been described. According to Vail TP, metal augmentation is usually indicated for defect depth of >10 mm of the medial tibial plateau. The outcomes of metal augmentation have been described as excellent. Nevertheless, we believe that it is mandatory to preserve as much of the bone as possible for future revision surgeries. Therefore, we performed autologous impaction bone grafting even for large bone defects (defect depth of ≥10 mm) in primary TKA. The objectives of this study are to describe our bone grafting technique in detail and to assess the radiological outcomes of the grafted bone. Methods. Between 2003 and 2011, 26 TKAs with autologous impaction bone grafting for ≥10 mm medial tibial defects were performed. The preoperative diagnoses were osteoarthritis in 17 knees, rheumatoid arthritis in 2 knees, osteonecrosis of the medial tibial condyle in 6 knees, and Charcot's joint in 1 knee. The average mediolateral width and depth of the medial tibial defects, measured after the horizontal osteotomy of the tibial articular surface, were 17.8 mm (range, 10–25 mm) and 12.0 mm (range, 10–23 mm), respectively. The average patient age at surgery was 73.2 years (range, 56–85 years). The patients were followed up for an average of 55 months (range 27–109 months). Bone grafting technique: Multiple drill holes (white arrow) were made on the floor of the defect (A) and a morselized cancellous bone was impacted using the grip end of a metal hammer (white asterisk) and firm manual pressure to fill the defect. Thus, the firm impaction prevented bone cement from entering the space between the graft and the tibial host bed. An assistant's index finger (black asterisk) was used as a bank (B). The tibial component was fixed on the grafted bone (white asterisk) with bone cement (C). Internal fixation devices were not required, and stem extension was used in only Charcot's joint (defect depth=23 mm). Aftertreatment was the same as that for the usual TKAs without bone defects. Results. In terms of clinical outcomes, no patient showed disturbances in walking ability at final follow-up. The average knee flexion angle was 114° (range, 95°–130°). The grafted bone was kept at the grafted area on the radiograms throughout the follow-up period. No absorption or collapse of the grafted bone was observed on the radiograms at the final follow-up. Usually, the grafted bone showed osteosclerotic changes around 2–3 months after TKA. Then, the osteosclerosis became weakened and the bony trabeculae could be detected in the grafted area. Finally, the grafted bone completely incorporated into the host bone in all knees with evidence of bony trabeculae crossing the interface by up to 1 year after surgery. The margin of the grafted area resembled bony cortex in 19 TKAs (73.1%). Conclusions. Our technique is easy, economic, and reproducible. It is an acceptable alternative to metal augmentation for large medial tibial defects in primary TKA

Metaphyseal fracture healing is important in joint-adjacent fractures and appears to differ from diaphyseal healing. We recently found that a biomaterial delivering bone morphogenic protein-2 (BMP-2) and zoledronic acid (ZA) healed the metaphyseal bone in a tibial defect but failed closing the cortical defect. In this study we added a BMP-2 soaked collagen membrane to study cortical healing from the muscle tissue surrounding the bone. We used SD rats and a 4.5 mm metaphyseal circular tibial defect. In group 1 (G1), a porous gelatin-calcium sulphate-hydroxyapatite (GCH) biomaterial containing rhBMP-2 and ZA was used to fill the defect (GCH+5 μg BMP-2+10 μg ZA). In group 2 (G2), we used a collagen membrane (2 μg BMP-2) to cover the GCH filled defect (GCH+3μg BMP+10 μg ZA). Group 3 (G3) was an empty control. Animals were sacrificed after 8-weeks and bone regeneration was evaluated with micro-CT and histology. In both G1 (P<0.001) and G2 (p<0.001) a significantly higher mineralized volume was found in the defect compared to empty G3. In G2 higher mineralized volume was found in the cortical region compared to both G1 (p<0.01) and G3 (p<0.001) as seen via micro-CT. Histologically, G1 and G2 showed islands of trabecular bone in the defect peripherally but only G2 showed cortical healing. G3 was empty in the middle but showed healed cortex. In conclusion, GCH can be used to deliver BMP-2 and ZA to promote metaphyseal bone growth. A membrane (CM) doped with low dose BMP-2 improved cortical regeneration

The management of bone loss in revision total knee replacement (TKA) remains a challenge. To accomplish the goals of revision TKA, the surgeon needs to choose the appropriate implant design to “fix the problem,” achieve proper component placement and alignment, and obtain robust short- and long-term fixation. Proper identification and classification of the extent of bone loss and deformity will aid in preoperative planning. Extensive bone loss may be due to progressive osteolysis (a mechanism of failure), or as a result of intraoperative component removal. The Anderson Orthopaedic Research Institute (AORI) is a useful classification system that individually describes femoral and tibial defects by the appearance, severity, and location of bone defects. This system provides a guideline to treatment and enables preoperative planning on radiographs. In Type 1 defects, femoral and tibial defects are characterised by minor contained deficiencies at the bone-implant interface. Metaphyseal bone is intact and the integrity of the joint line is not compromised. In this scenario, the best reconstruction option is to increase the thickness of bone resection and to fill the defect with cancellous bone graft or cement. Type 2 defects are characterised by deficient metaphyseal bone involving one or more femoral condyle(s) or tibial plateau(s). The peripheral rim of cortical bone may be intact or partially compromised, and the joint line is abnormal. Reconstruction options for a Type 2A defect include impaction bone grafting, cement, or more commonly, prosthetic augmentation (e.g. sleeves, augments or wedges). In Type 2B defects, metaphyseal bone of both femoral condyles or both tibial plateaus is deficient. The peripheral rim of cortical bone may be intact or partially compromised, and the joint line is abnormal. Options for a Type 2B defect include impaction grafting, bulk structural allograft, prosthetic augmentation, metaphyseal sleeves (in some cases), or metaphyseal cones. Finally, in the presence of a Type 3 deficiency, both metaphyseal and cortical bone is deficient and there is partial or complete disruption of the collateral ligament attachments. In this case, the most commonly used reconstruction options include hinged implants or megaprostheses with or without bulk structural allograft, prosthetic augmentation, and/or metaphyseal/diaphyseal sleeves or cones. Today, we are fortunate to have a wide variety of options available to aid in reconstruction of a revision TKA with massive bone loss. Historically, use of cement, bone grafting, or use of a tumor-type or hinged implant were considered the main options for reconstruction. The development and adoption of highly porous sleeves and cones has given the surgeon a new and potentially more durable option for reconstruction of previously difficult to treat defects. Using radiographs and computed tomography, surgeons are able to preoperatively classify bone loss and anticipate a reconstruction plan based upon the classification; however, it is always important to have several back-up options on hand during revision surgery in the event bone loss is worse than expected

Introduction. Circular frame fixation has become a cornerstone of non-union and deformity management since its inception in the 1950s. As a consequence of modularity and heterogenous patient and injury factors, the prediction of the mechanobiological environment within a defect is subject to wide variations in practice. Given these wide range of confounding variables, clinical and cadaveric experimentation is close to impossible and frame constructs are based upon clinician experience. The Finite Element Analysis (FEA) method provides a powerful tool to numerically analyse mechanics. This work aims to develop an FEA model of a tibial defect and predict the mechanical response within the construct. Materials and Methods. The geometry of a tibia was acquired via CT and a series of bone defects were digitally created in the tibial diaphysis. A 4-ring, 10-wire Ilizarov fixator was constructed using 180mm stainless steel rings and 1.8mm stainless steel wires tensioned to 1200N. An axial load (800N) was applied to simulate single leg stance of an 80kg patient. The magnitude of displacement was measured for defects with varying sizes (5–40mm). A numerical analysis was performed in large-strain regime using open-source FEA library (MoFEM). Results. Defect size did not effect displacement, but significantly influenced strain. Measured displacements were 5.72–5.78mm, however strain ranged from 14.5–100%. Moreover, it was found that bone material properties also have no significant impact on the results. Conclusions. Accounting for FEA assumptions, this model predicted a strain environment which was above expected favourable range for bone healing. The addition of graft within the environment is likely to change the mechanobiological environment which warrants further investigation. We plan to develop this model to answer further research questions in the limb reconstruction discipline and validate its accuracy with mechanical data. We believe the presented approach can be a useful tool for investigating the performance circular frames

Aim: To review the effectiveness of ipsilateral þbular transfer with its vascular pedicle mobilised in bridging defects in the tibial shaft. Method & Results: This operation was performed in 8 patients with segmental tibial defect following injury. We reviewed these cases with a minimal follow up of 2.5 years. All the tibial defects were the result of severe open fractures (Gustilo Grade III) and either bone loss or infected non-union, and ranged in size from 1 to 12 cm. The patients had an average of seven procedures and a delay of 33 months before þbular transfer. The procedure was successful in achieving fracture union in all cases, with an average time to union of 15 months (range, 5–33 months). Shortening of up to 3 cm and some residual ankle stiffness was found but all patients were ambulating bearing full weight and six had returned to their previous occupation by their þnal follow up. Only one patient had signiþcant pain affecting function. Conclusion: This is a successful and relatively simple method of reconstructing segmental tibial defects with relatively avascular beds, and avoids the problems of tibial transport and of microvascular anastomoses

Osteolysis commonly causes total knee replacement (TKR) failure, often associated with asymptomatic large defects. Detection and size estimation of lytic defects is important for the indications and planning of revision surgery. Our study compares the utility of fluoroscopic-guided plain X-rays and computed topography (CT) in osteolysis detection and volume appreciation. Three cadaveric specimens were imaged at baseline and following the creation of reamed defects (small, medium and large approximately = 1, 5 & 10 cm3 volume respectively) in the tibia and femur with TKR component implantation at each timepoint. Imaging was with fluoroscopic-guided plain X-rays (Anteroposterior & Lateral [APL], Paired Oblique [OBL]) as well as rapid-acquisition spiral Computed Topography [CT] with a beam-hardening artefact removal algorithm. Three arthroplasty surgeons estimated the size of the lesion, if present, and confidence (none=0, fair=1, excellent=2) in their assessment on randomly presented images. Each surgeon performed two assessments of each image one month apart. The accuracy of detecting lesions was determined using the area under the receiver-operating curve (AU-ROC) obtained from a logistic regression with adjustment for assessment sequence, observer, knee and bone. Volume appreciation and assessor confidence were determined using Kappa and the mean average of confidence scores respectively. The AU-ROC using combinations of either APL/OBL/CT (0.83) or OBL/CT (0.83) resulted in superior detection of lesions (p<0.05) compared to APL (0.75) or OBL alone (0.77). Correct volume appreciation was highest with APL/OBL/CT (kappa=0.52), followed by APL/OBL (0.51) and was superior (p<0.05) to APL (0.29) or CT alone (0.31). Small and medium defects were more often missed than large with all modalities (20.3 vs. 39.7 %). Femoral defects were missed more often than tibial defects (40% vs. 28.7%) and small lesions missed more with CT (50%) versus APL (48%) and Oblique (40%). CT missed 19% of large sized defects, attributed mostly to femoral (29.1%) rather than tibial defects (8.3%). Greater confidence was derived from use of CT (1.29) and APL (1.19) [Interquartile range (IQR) 1,2] when compared to OBL (.98, IQR 1,1) [p<.01]. Also, there was greater confidence regarding judgement of tibial defects (1.25, IQR 1,2) compared with femoral defects (1.05, IQR 1,1) [p<.01]. Combining all imaging modalities was synergistic and the most sensitive and specific means of defect detection and volume appreciation. CT provided more confidence, superior detection and volume appreciation when used in combination with APL/OBL versus APL/OBL alone. There is also additional value when APL is combined with OBL

Summary Statement. Parathytorid hormone-related protein (107–111) loaded onto biopolymer-coated nanocrystalline hydroxyapatite (HA. Glu. ) improves the bone repair in a cavitary defect in rat tibiae. Introduction. Biopolymer-coated nanocrystalline hydroxyapatite (HA. Glu. ) made as macroporous foams are promising candidates as scaffolds for bone tissue engineering applications. They exhibit optimal features, promoting internalization, proliferation and differentiation of osteoprogenitors, with an adequate cell colonization over the entire scaffold surface. Parathyroid hormone-related protein (PTHrP) is an important modulator of bone formation. Its 107–111 epitope (osteostatin) exhibits osteogenic properties at least in part by directly acting on osteoblasts. The main aim of this study was to evaluate whether osteostatin loading into HA. Glu. scaffolds might improve their bone regeneration capacity. Materials and Methods. HA. Glu. scaffolds were prepared as previously described (Sánchez-Salcedo S et al. J. Mater. Chem. 2010; 20:6956-61). Osteostatin was adsorbed onto HA. Glu. material by dipping into a solution containing this peptide at 100 nM (in phosphate-buffered saline, pH 7.4), following a standard protocol. We performed a cavitary defect (2 mm in diameter and 3 mm in depth) in both distal tibial metaphysis using a drill under general anesthesia in male Wistar rats (n=8) of 6 months of age. Unloaded HA. Glu. material (7 mg) was implanted into left tibial defects, whereas rigth tibial defects received the osteostatin-loaded material. Animals were sacrificed after 4 weeks for histological, μ-computerised tomography and gene expression analysis of the callus. Our protocol was approved by the Institutional Animal Care and Use Committee at the IIS-FJD. Mouse osteoblastic MC3T3-E1 cells were grown in differentiation medium (α-MEM with 10% fetal bovine serum, 50 µg/ml ascorbic acid, and 10 mM β-glycerolphosphate), in the presence or absence of HA. Glu. material with or without osteostatin. Cell viability (assessed by trypan blue staining), alkaline phosphatase (ALP) activity and mineralization (alizarin red) were analyzed at different culture times. Results. The mean uptake of osteostatin by HA. Glu. scaffolds was about 60 % (representing 0.7 μg/implanted scaffold) after 24 h of loading, and they released a mean of 80 % of loaded peptide to the surrounding medium within 1–24 h. At 4 weeks, this osteostatin-containing HA. Glu. material significantly increased the bone volumen fraction and trabecular thickness of regenerating bone in the tibial methaphysis, compared to those observed with unloaded HAGlu scaffolds. In addition, osteostatin-coated HA. Glu. scaffolds increased (2-fold) the gene expression of osteocalcin and vascular cell adhesion molecule 1, but decreased (2-fold) that of the Wnt inhibitors, SOST and Dickkopf homolog 1 (DKK-1) in the fracture callus. In MC3T3-E1 cell cultures, osteostatin-loaded HA. Glu. material increased cell viability and ALP activity (each by 30%), and matrix mineralization (by 50%) at days 4 and 10, respectively. Conclusions. These results indicate that osteostatin loading improves the bone regeneration capacity of HA. Glu. scaffolds. Our findings suggest that these scaffolds might be promising implants in orthopaedic applications. This work has been supported by a grant from Comunidad Autónoma de Madrid (S-2009/MAT/1472)

Aim. Simultaneous use of Ilizarov techniques with transfer of free muscle flaps is not current standard practice. This may be due to concerns about duration of surgery, clearance of infection, potential flap failure or coordination of surgical teams. We investigated this combined technique in a consecutive series of complex tibial infections. Method. A single centre, consecutive series of 45 patients (mean age 48 years; range 19–85) were treated with a single stage operation to apply an Ilizarov frame for bone reconstruction and a free muscle flap for soft-tissue cover. All patients had a segmental bone defect in the tibia, after excision of infected bone and soft-tissue defects which could not be closed directly or with local flaps. We recorded comorbidities, Cierny-Mader and Weber-Cech classification, the Ilizarov method used, flap type, follow-up duration, time to union and complications. Results. 26 patients had osteomyelitis and 19 had infected non-union. Staphylococci were cultured in 25 cases and 17 had polymicrobial infections. Ilizarov monofocal compression was used in 14, monofocal distraction in 15, bifocal compression/distraction in 8, and bone transport in 8. 8/45 had an additional ankle fusion, 7/45 had an angular deformity corrected at the same time and 24 also had local antibiotic carriers inserted. Median time in frame was 5 months (3–14). 38 gracilis, 7 latissimus dorsi and 1 rectus abdominus flaps were used. One flap failed within 48 hours and was revised (flap failure rate 2.17%). There were no later flap complications. Flaps were not affected by distraction or bone transport. Mean follow-up was 23 months (10–89). 44/45 (97.8%) achieved bony union. Recurrence of infection occurred in 3 patients (6.7%). Secondary surgery was required to secure union with good alignment in 8 patients (17.8%; docking site surgery in 6, IM nailing in 2) and in 3 patients for infection recurrence. All were infection free at final follow-up. Conclusions. Simultaneous Ilizarov reconstruction with free muscle flap transfer is safe and effective in treating segmental infected tibial defects, and is not associated with an increased flap failure rate. It shortens overall time spent in treatment, with fewer operations per patient. However, initial theatre time is long and a committed multidisciplinary team is required to achieve good results

Purpose: The aim of our study was to evaluate bone formation and angiogenesis produced within a biodegradable poly-D, L-lactide-co-glycolide acid/calcium phosphate (PLGA/CaP) scaffold when used to treat a diaphyseal tibia defect and compare this to an iliac crest autograft or an empty defect. Method: An 8.0 mm diaphyseal defect was created in a canine tibia model. All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail. Eighteen canines were allotted into three treatment groups:. empty (N=5),. iliac crest autograft (N=6), or. PLGA/CaP biodegradable scaffold Tissue Regeneration Therapeutics Inc., ON, Canada) (N=7). Fluorescent markers were given at different times: calcein green (six weeks), xylenol orange (nine weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, and brightfield and fluorescent microscopy were used for analysis. Results: Micro CT and brightfield images of scaffold samples displayed multiple vessels (10 to 100μm) within the scaffold. The bone volume and vasculature volume (measured with Micro CT) within the tibial defect site were reported as a percentage of the total volume of the defect site. The percent bone volume within the defect site was not different between treatment groups (p=0.112). There was greater percent vasculature volume in the scaffold group than the autograft group (p< 0.001). Bone formation at the osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Osteotomy bone formation was significantly greater in the scaffold group than the autograft group (p=0.015). Osteotomy sites associated with greater angiogenesis displayed greater bone formation. Bone formation rates were reported as the distance between the fluorescent bone labels. Autograft samples had the greatest bone formation rates within the periosteum. Autograft and scaffold samples had the greatest rate of bone formation within the cortex. Conclusion: Our canine tibial defect model provides a satisfactory facsimile of the traumatic tibia fracture with associated bone loss. The PLGA/CaP biodegradable scaffold we have employed promotes angiogenesis within a defect and could be used in conjunction with autografting

Aims

This study aimed to evaluate the effectiveness of the induced membrane technique for treating infected bone defects, and to explore the factors that might affect patient outcomes.