Experimental tibial plateau fractures augmented with calcium phosphate cement or autologous bone graft

Hydroxyapatite nanoparticle-modified porous bone grafts with improved cell attachment

Emulsion-templated foams have displayed promise as injectable bone grafts; however, the use of a surfactant as an emulsifier resulted in relatively small pores and impedes cell attachment. Hydroxyapatite nanoparticles were explored as an alternative stabilizer to address these limitations. To this end, hydroxyapatite nanoparticles were first modified with myristic acid to generate the appropriate balance of hydrophobicity to stabilize a water-in-oil emulsion of neopentyl glycol diacrylate and 1,4-butanedithiol. In situ surface modification of the resulting foam with hydroxyapatite was confirmed with elemental mapping and transmission electron microscopy. Nanoparticle-stabilized foams displayed improved human mesenchymal stem cell viability (91 ± 5%) over surfactant-stabilized foams (23 ± 11%). Although the pore size was appropriate for bone grafting applications (115 ± 71 μm), the foams lacked the interconnected architecture necessary for cell infiltration. We hypothesized that a co-stabilization approach with both surfactant and nanoparticles could be used to achieve interconnected pores while maintaining improved cell attachment and larger pore sizes. A range of hydroxyapatite nanoparticle and surfactant concentrations were investigated to determine the effects on microarchitecture and cell behavior. By balancing these interactions, a co-stabilized foam was identified that possessed large, interconnected pores (108 ± 67 μm) and improved cell viability and attachment. The co-stabilized foam was then evaluated as an injectable bone graft including network formation, microscale integration with bone, push out strength, and compressive properties. Overall, this work demonstrated that in situ surface modification with nHA improved cell attachment while retaining desirable bone grafting features and injectability.

Gentamicin-permeated cement to sustain mechanical support for the treatment of a chronic calcaneal abscess. A case report

INTRODUCTION AND IMPORTANCE

Chronic calcaneal osteomyelitis is a challenging condition associated with high relapse rates, requiring a multidisciplinary approach and various therapeutic options for effective management. We report a very rare case of a pyogenic osteomyelitis of the os calcis presented as a bone abscess.

CASE PRESENTATION

A diabetic male patient presented with chronic osteomyelitis of the calcaneus in the form of bone abscess with a cavity of 6*5 cm. After pus evacuation and debridement of the cavity, gentamycin-impregnated polymethylmethacrylate cement was used to locally assist in controlling the infection and to assure mechanical support. Antibiogram-based oral antibiotic was administrated for 6 weeks. At final follow-up, the patient could walk without any assistance and was able to raise his body on the operated heel, with no signs of infection.

CLINICAL DISCUSSION

This case illustrates successful conservative surgical treatment of calcaneal abscess using antibiotic-impregnated cement for mechanical support and local infection control.

CONCLUSION

Incorporating antibiotic-impregnated cement into conservative foot surgeries for deeply embedded calcaneal abscesses provides effective infection control, mechanical support, and functional preservation, leading to successful treatment outcomes.

Tissue Integration of Calcium Phosphate Compound after Subchondroplasty: 4-Year Follow-Up in a 76-Year-Old Female Patient

Subchondroplasty is a new minimally invasive surgical technique developed to treat bone marrow lesions (BML) and early osteoarthritis (OA). During the procedure, engineered calcium phosphate compound (CPC) is injected. It is claimed by the manufacturer that during the healing process, the CPC is replaced with new bone. The purpose of this study was to verify the replacement of CPC with new bone after subchondroplasty for the first time in humans. A 76-year old woman was referred for resistant medial knee pain. Standing radiographs showed varus knee OA and magnetic resonance imaging (MRI) revealed BML. She was treated with subchondroplasty of medial femoral condyle. Excellent relief of pain was achieved after procedure. Afterwards, the pain worsened, the radiographs confirmed the OA progression and the patient was treated with a total knee arthroplasty (TKA) 4 years after primary procedure. The resected bone was examined histologically and with micro-computed tomography (CT). Histologically, bone trabeculae of subcortical bone were embedded in the amorphous mass. However, no signs of CPC resorption and/or bone replacement have been found with micro-CT. In short term, excellent pain relief could be expected after the subchondroplasty procedure. However, there was no replacement of CPC with bone and the technique probably did not influence the natural process of knee OA.

Packing with alpha-tricalcium phosphate followed by curettage and phenol-ethanol ablation for appendicular giant cell tumor of bone

Giant cell tumor of bone (GCTB) is an intermediate and locally aggressive bone tumor. Alpha-tricalcium phosphate (alpha-TCP) is an adjustable bone substitute used to fill various sizes of bone cavities after curettage for GCTB. This study aimed to evaluate the surgical outcome of packing with alpha-TCP followed by curettage and phenol-ethanol ablation. We retrospectively reviewed data of 16 patients with GCTB who underwent primary surgery in our institute between January 2009 and April 2021. Data of Campanacci grading system; number of local recurrences and distant metastases; local recurrence-free survival rate using the Kaplan-Meier method; oncological outcomes; and complications after surgery (secondary osteoarthritis and postoperative fracture) were evaluated in this study. Regarding the Campanacci grading system, 2 patients were classified as grade I, 14 as grade II, and none as grade III. The 5-year local recurrence-free survival rate was 77.8% in all cases. Lung metastasis was not detected in this study. Oncological outcomes were: continuous disease free, 13 patients; alive with disease, 3 patients; and no evidence of disease or death of disease, none of the patients. Secondary osteoarthritis after surgery was not detected in the present study. Packing with alpha-TCP followed by curettage and phenol-ethanol ablation for appendicular GCTB may be safe and effective in suppressing the risk of secondary osteoarthritis.

Plate osteosynthesis combined with bone cement provides the highest stability for tibial head depression fractures under high loading conditions

Older patients sustaining tibial head depression fractures often cannot follow the post-operative rehabilitation protocols with partial weight-bearing of the affected limb, leading to osteosynthesis failure, cartilage step-off and arthritis development. Therefore, the aim of this study was to analyse the biomechanical performance of different types of osteosyntheses alone and in combination with bone cement simulating cyclically high loading conditions of tibial head depression fractures. Lateral tibial head depression fractures (AO: 41-B2.2; Schatzker type III) were created in synthetic bones and stabilized using three different osteosyntheses alone and in combination with a commonly used bone cement (chronOS™): 2 screws, 4 screws in the jail technique and a lateral angle-stable buttress plate. After fixation, the lateral tibial plateau was axially loaded in two, from each other independent testing series: In the first test protocol, 5000 cycles with 500 N and in the end load-to-failure tests were performed. In the second test protocol, the cyclic loading was increased to 1000 N. Parameters of interest were the displacement of the articular fracture fragment, the stiffness and the maximum load. The osteosyntheses revealed a higher stiffness in combination with bone cement compared to the same type of osteosynthesis alone (e.g., 500 N level: 2 screws 383 ± 43 N/mm vs. 2 screws + chronOs 520 ± 108 N/mm, increase by 36%, p < 0.01; 4 screws 368 ± 97 N/mm vs. 4 screws + chronOS 516 ± 109 N/mm, increase by 40%, p < 0.01; plate: 509 ± 73 N/mm vs. plate + chronOs 792 ± 150 N/mm, increase by 56%, p < 0.01). Bone cement reduced the displacement of the plate significantly (500 N level: plate: 8.9 ± 2.8 mm vs. plate + chronOs: 3.1 ± 1.4 mm, reduction by 65%, p < 0.01; 1000 N level: 16.9 ± 3.6 mm vs 5.6 ± 1.3 mm, reduction by 67%, p < 0.01). Thus, the highest stiffness and lowest displacement values were found when using the plate with bone cement in both loading conditions (500 N level: 2 screws + chronOs 3.7 ± 1.3 mm, 4 screws + chronOs 6.2 ± 2.4 mm; 1000 N level: 2 screws + chronOs 6.5 ± 1.2 mm, 4 screws + chronOs 5.7 ± 0.8 mm). From a biomechanical perspective, plate osteosynthesis of tibial head depression fractures should always be combined with bone cement, provides higher stability than 2-screw and 4-screw fixation and is a valid treatment option in cases where extraordinary stability is required.

Bone Tissue Engineering in the Treatment of Bone Defects

Bones play an important role in maintaining exercise and protecting organs. Bone defect, as a common orthopedic disease in clinics, can cause tremendous damage with long treatment cycles. Therefore, the treatment of bone defect remains as one of the main challenges in clinical practice. Today, with increased incidence of bone disease in the aging population, demand for bone repair material is high. At present, the method of clinical treatment for bone defects including non-invasive therapy and invasive therapy. Surgical treatment is the most effective way to treat bone defects, such as using bone grafts, Masquelet technique, Ilizarov technique etc. In recent years, the rapid development of tissue engineering technology provides a new treatment strategy for bone repair. This review paper introduces the current situation and challenges of clinical treatment of bone defect repair in detail. The advantages and disadvantages of bone tissue engineering scaffolds are comprehensively discussed from the aspect of material, preparation technology, and function of bone tissue engineering scaffolds. This paper also summarizes the 3D printing technology based on computer technology, aiming at designing personalized artificial scaffolds that can accurately fit bone defects.

The Study of Biomechanics and Clinical Anatomy on a Novel Plate Designed for Posterolateral Tibial Plateau Fractures via Anterolateral Approach

There is no consensus about the optimal internal fixation selection for treatment of posterolateral tibial plateau fracture. This study described a novel plate through an anterolateral approach for posterolateral tibial plateau fractures (PTPFs). We evaluated the biomechanical performance of a novel plate and two conventional internal implants and investigated the anatomic feasibility of the novel plate. The fracture models were randomly assigned into six groups: Groups A–C were the model groups of posterolateral split fracture, fixed with the posterior buttress plate, the lateral locking plate, and the novel plate, respectively. Groups D–E were the model groups of posterolateral depression fracture, fixed with the posterior buttress plate, the lateral locking plate, and the novel plate, respectively. We evaluated the biomechanical performance of six model groups by the biomechanical testing and finite element analysis. Progressively increasing axial compressive loads were applied to each synthetic fracture model by using a customized indentor under 250–750 N loads. Meanwhile, we dissected 12 fresh frozen knee specimens and fixed them with the novel plate through the anterolateral approach. We recorded the adjacency of the novel plate to important anatomic structures. Biomechanical testing showed that the novel plate had the least displacement, followed by the posterior buttress plate, and the lateral plate had the most displacement in posterolateral split fracture. There was no significant difference in the displacement between the novel plate and the lateral plate at different loads in posterolateral depression fractures. And the posterior buttress plate showed the most displacement. In the finite element analysis, the maximum stress values of Groups A, B, and C were 383.76, 414.63, and 305.07 MPa under the load of 750 N, respectively. The maximum stress values of Groups D, E, and F were 474.28, 436.31, and 413.4 MPa under the load of 750 N, respectively. In the anatomic study, the placement of the novel plate had a low risk of damage to the important anatomic structures of knee posterolateral corner. The novel plate could be a great choice for the treatment of PTPFs due to better biomechanical performance and easy manipulation.

Treatment of Subchondral Bone Marrow Edema with Intralesional Viscous Bone Cement in a Young, Active Patient: A Case Report

CASE

A 23-year-old male patient presented with symptomatic, high-grade medial tibial plateau bone marrow edema unresponsive to conservative treatment. After the injection of intralesional viscous bone cement, the patient had resolution of his symptoms and returned to running.

CONCLUSION

The use of intralesional viscous bone cement has grown in popularity for the treatment of bone marrow edema in individuals older than 40 years but is uncommon in younger individuals. This case demonstrates that intralesional viscous bone cement may be considered in the treatment of high-grade bone marrow edema in young, active patients who are unresponsive to extensive conservative management.

Autologous versus synthetic bone grafts for the surgical management of tibial plateau fractures: a systematic review and meta-analysis of randomized controlled trials

AIMS

Our objective was to conduct a systematic review and meta-analysis, to establish whether differences arise in clinical outcomes between autologous and synthetic bone grafts in the operative management of tibial plateau fractures.

METHODS

A structured search of MEDLINE, EMBASE, the online archives of Bone & Joint Publishing, and CENTRAL databases from inception until 28 July 2021 was performed. Randomized, controlled, clinical trials that compared autologous and synthetic bone grafts in tibial plateau fractures were included. Preclinical studies, clinical studies in paediatric patients, pathological fractures, fracture nonunion, or chondral defects were excluded. Outcome data were assessed using the Risk of Bias 2 (ROB2) framework and synthesized in random-effect meta-analysis. The Preferred Reported Items for Systematic Review and Meta-Analyses guidance was followed throughout.

RESULTS

Six studies involving 353 fractures were identified from 3,078 records. Following ROB2 assessment, five studies (representing 338 fractures) were appropriate for meta-analysis. Primary outcomes showed non-significant reductions in articular depression at immediate postoperative (mean difference -0.45 mm, p = 0.25, 95%confidence interval (CI) -1.21 to 0.31, I2 = 0%) and long-term (> six months, standard mean difference -0.56, p = 0.09, 95% CI -1.20 to 0.08, I2 = 73%) follow-up in synthetic bone grafts. Secondary outcomes included mechanical alignment, limb functionality, and defect site pain at long-term follow-up, perioperative blood loss, duration of surgery, occurrence of surgical site infections, and secondary surgery. Mean blood loss was lower (90.08 ml, p < 0.001, 95% CI 41.49 to 138.67) and surgery was shorter (16.17 minutes, p = 0.04, 95% CI 0.39 to 31.94) in synthetic treatment groups. All other secondary measures were statistically comparable.

CONCLUSION

All studies reported similar methodologies and patient populations; however, imprecision may have arisen through performance variation. These findings supersede previous literature and indicate that, despite perceived biological advantages, autologous bone grafting does not demonstrate superiority to synthetic grafts. When selecting a void filler, surgeons should consider patient comorbidity, environmental and societal factors in provision, and perioperative and postoperative care provision. Cite this article: Bone Jt Open 2022;3(3):218-228.

Arthroscopic Approach to Preservation of the Hip with Avascular Necrosis

Avascular necrosis (AVN) of the hip is a devastating disease that affects middle-aged adults with poor outcomes if not treated in its early stages. In recent years, subchondroplasty with calcium phosphate solution has shown promising results. Concomitant intra-articular pathologies, including femoroacetabular impingement and chondral lesions, have been described in hips affected by AVN. These should be addressed at the time of surgery to lower the risk of failure. In this Technical Note, we describe an arthroscopic approach to femoral head subchondroplasty with precollapse lesion in AVN affected hip, combined with labral reconstruction and acetabular chondral treatment.

Treatment of tibial plateau fractures with a novel fenestrated screw system for delivery of bone graft substitute

PURPOSE

The purpose of this study was to describe the incidence of subsidence in patients with AO/OTA 41 (tibial plateau) fractures which were repaired with a novel fenestrated screw system to used to deliver CaPO4 bone substitute material to fill the subchondral void and support the articular reduction.

METHODS

Patients with unicondylar and bicondylar tibial plateau fractures were treated according to the usual technique of two surgeons. After fixation, the Zimmer Biomet N-Force Fixation System®, a fenestrated screw that allows for the injection of bone substitute was placed and used for injection of the proprietary calcium phosphate bone graft substitute into the subchondral void. For all included patients, demographic information, operative data, radiographs, and clinic notes were reviewed. Patients were considered to have articular subsidence if one or more of two observations were made when comparing post-operative to their most recent clinic radiographs: > 2 mm change in the distance between the screw and the lowest point of the tibial plateau, > 2 mm change in the distance between the screw and the most superior aspect of the plate. Data were analyzed to determine if there were any identifiable risk factors for complication, reoperation, or subsidence using logistic regression. Statistical significance was set at p < 0.05.

RESULTS

34 patients were included with an average follow-up of 32.03 ± 22.52 weeks. There were no overall differences between height relative to the medial plateau or the plate. Two patients (5.9%) had articular subsidence. Six patients (15.2%) underwent reoperation, two (6%) for manipulations under anaesthesia due to arthrofibrosis, and four (12%) due to infections. There were 6 (19%) total infections as 2 were superficial and required solely antibiotics. One patient had early failure.

CONCLUSION

Use of a novel fenestrated screw system for the delivery of CaPO4 BSM results in articular subsidence and complication rates similar to previously published values and appears to be a viable option for addressing subchondral defects in tibial plateau fractures.

LEVEL OF EVIDENCE

IV.

Subchondral Rafting Plate for the Treatment of Fragmented Articular Central Depression Tibial Plateau Fracture Patterns: Case Series and Technical Illustration

Articular depression is a significant component of lateral tibial plateau fracture patterns. Current literature supports the use of subchondral rafting screws, either placed through a plate or not. However, articular comminution has been associated with increased articular subsidence despite an adequate screw-joint distance. We report four cases that underwent the subchondral rafting plate technique for fragmented articular central depression lateral tibial plateau fractures. Clinical and radiographic evaluations were performed at the last follow-up. The mean follow-up was 18 months. All patients healed the fracture without any significant articular subsidence or loss of reduction. This case study hints that this novel technique is a potentially safe and cost-effective strategy to be incorporated in the daily practice of the orthopedic trauma surgeon, especially in certain challenging circumstances when a salvage procedure is required due to lateral tibial plateau fracture malreduction and the unavailability of anatomically designed locking plates.

Biological and mechanical performance and degradation characteristics of calcium phosphate cements in large animals and humans

Calcium phosphate cements (CPCs) have been used to treat bone defects and support bone regeneration because of their good biocompatibility and osteointegrative behavior. Since their introduction in the 1980s, remarkable clinical success has been achieved with these biomaterials, because they offer the unique feature of being moldable and even injectable into implant sites, where they harden through a low-temperature setting reaction. However, despite decades of research efforts, two major limitations concerning their biological and mechanical performance hamper a broader clinical use. Firstly, achieving a degradation rate that is well adjusted to the dynamics of bone formation remains a challenging issue. While apatite-forming CPCs frequently remain for years at the implant site without major signs of degradation, brushite-forming CPCs are considered to degrade to a greater extent. However, the latter tend to convert into lower soluble phases under physiological conditions, which makes their degradation behavior rather unpredictable. Secondly, CPCs exhibit insufficient mechanical properties for load bearing applications because of their inherent brittleness. This review places an emphasis on these limitations and provides an overview of studies that have investigated the biological and biomechanical performance as well as the degradation characteristics of different CPCs after implantation into trabecular bone. We reviewed studies performed in large animals, because they mimic human bone physiology more closely in terms of bone metabolism and mechanical loading conditions compared with small laboratory animals. We compared the results of these studies with clinical trials that have dealt with the degradation behavior of CPCs after vertebroplasty and kyphoplasty.

Enhanced Subchondroplasty Treatment for Post-Traumatic Cartilage and Subchondral Bone Marrow Lesions in a Canine Model

This study characterizes outcomes associated with subchondroplasty (SCP) versus SCP enhanced with platelet-rich plasma (PRP) or bone marrow aspirate concentrate (BMC) treatment of impact-induced subchondral bone marrow lesions (BML) using a validated preclinical canine model. With IACUC approval, purpose-bred research hounds (n = 24) underwent arthroscopic impact injury (40 N) to both medial femoral condyles. At 3 months, functional assessments, arthroscopy, and magnetic resonance imaging (MRI) were performed. One knee in each dog (n = 24; n = 12 per endpoint) was randomly assigned to SCP with the other knee randomly assigned to SCP + PRP, SCP + BMC or sham injection (control) (n = 8 per group; n = 4 per endpoint). Dogs were evaluated at 6 and 12 months after treatment using functional assessments, radiography, arthroscopy, and MRI and humanely euthanatized at 6 or 12 months after treatment for histologic assessments. At 6 months post-treatment, comfortable range-of-motion (CROM) was higher (p < 0.04) in SCP + PRP and SCP + BMC knees compared with controls. At 1 year post-treatment, %Total Pressure Index was higher (p = 0.036) in SCP + BMC compared with controls, pain was lower (p < 0.05) in SCP + BMC and SCP + PRP compared with SCP and controls, and CROM was higher (p < 0.05) in SCP + BMC and SCP + PRP compared with SCP and controls. Knees treated with SCP + PRP and SCP + BMC had better (p < 0.05) MRI grades than SCP and controls. No statistically significant differences in arthroscopic or histologic pathology were noted. Clinical significance: Biologics added to SCP treatment may further enhance its beneficial effects by improving range-of-motion, pain severity, and limb loading through 1 year after treatment. However, these benefits must be considered alongside cost, logistics, and treatment availability. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:740-746, 2020.

Subchondroplasty of the Foot: Two Case Reports

Early avascular necrosis of metatarsal heads and cuboid injuries are uncommon conditions encountered by foot and ankle specialists. Treatment options are limited and typically include long periods of offloading or non-weightbearing. There is limited published information on alternative treatment approaches for such pathologies when conservative therapies fail. Presented are 2 patient cases treated with a percutaneous calcium phosphate injection after failure of standard therapy, persistent pain, and bone marrow edema in the foot.

Surgical Treatment of Bone Marrow Lesion Associated with Recurrent Plantar Fasciitis: A Case Report Describing an Innovative Technique Using Subchondroplasty®

Plantar fasciitis is one of the most common chief complaints seen in the foot and ankle clinic. With a relatively benign course, most cases are self-limiting or amendable to conservative therapy; ~90% of all plantar fasciitis cases will respond to these methods. When conservative treatment and time fail, surgical intervention can be necessary to improve outcomes. We present a novel method using Subchondroplasty^® (SCP^®; Zimmer Holdings, Inc.; Warsaw, IN) and revision fasciotomy in a case in which initial fasciotomy had failed. After the patient had failed to improve, a worsening underlying bone marrow lesion was identified at the origin of the plantar fascia; thus, SCP^® was used with repeat fasciotomy. SCP^® involves injecting calcium phosphate into bone marrow lesions to stimulate long-term bone repair. At 10 months after SCP^®, the patient remained pain free and had returned to running at the final follow-up examination. This surgical treatment should be considered as an adjunctive procedure for those patients with plantar fasciitis, identifiable bone marrow lesions on magnetic resonance imaging, and continued pain when other treatment modalities have failed.

Injectable strontium-doped hydroxyapatite integrated with phosphoserine-tethered poly(epsilon-lysine) dendrons for osteoporotic bone defect repair

The control of the inflammatory response induced by the implantation of foreign biomaterials is fundamental in determining tissue healing. It has been shown that the activation of specific macrophage pathways upon contact with a biomaterial can lead either to a chronic inflammation preventing a physiological tissue repair or to an improved tissue healing. In the case of bone repair, calcium phosphate cements with good osteoconductivity properties have been successfully applied in bone defect filling and repair, but poor handling properties, insufficient viscous flow and unmatched degradation rate are still problems that remain unsolved. In this study, a strontium-doped hydroxyapatite (HA) gel was modified by integrating branched poly(epsilon-lysine) dendrons with third-generation branches exposing phosphoserine (SrHA/G3-K PS). The interaction of this material with macrophages was investigated in vitro, focusing on the secretion and gene expression of specific pro-inflammatory cytokines. Our results showed that the addition of strontium and G3-K PS to HA sol-gel could down-regulate the gene expression of inflammatory factors such as IL-1β, TNF-α and MCP-1, while increasing the gene expression of IL-6, a cytokine known for its osteogenic effect. These results were further confirmed by ELISA test of the respective protein concentrations. When exposed to supernatants of macrophage culture in the presence of strontium and G3-K PS, osteoblast viability was promoted with elevated osteogenic gene markers, in terms of OPG, ALP, OCN and COL-I. In vivo implantation experiments using an osteoporotic rat model with bone defect further confirmed that the addition of G3-K PS to HA could dramatically promote new bone regeneration. Although the introduction of strontium improved the degradation properties of the injectable materials, no positive effect on promoting in vivo bone regeneration was observed.

Subchondroplasty for the treatment of post-traumatic bone marrow lesions of the medial femoral condyle in a pre-clinical canine model

This study characterizes long-term outcomes associated with subchondroplasty (SCP) treatment for impact-induced subchondral bone marrow lesions (BML) using a validated pre-clinical canine model. With IACUC approval, purpose-bred research hounds (n = 16) underwent arthroscopic impact injury (40N) to both medial femoral condyles. At 3 months, functional assessments, arthroscopy, and MRI were performed and knees (n = 32) were randomly assigned to SCP (3 ml fluoroscopically guided percutaneous injection of AccuFill BSM into BML bone defects) or sham injection (Control). Dogs were assessed at 3, 6, 12, and 24 months after treatment using functional assessments, radiographic evaluation, arthroscopy, and MRI. Dogs were humanely euthanatized at 3, 6, 12, or 24 months after treatment for gross, microCT, and histologic assessments. All knees had focal articular cartilage defects with associated subchondral BMLs, as well as clinical dysfunction, 3 months after injury. At the 3 and 6 months, SCP knees showed more functional impairment than Control knees, however, these differences were not statistically significant. At 1- and 2-year post-treatment, function in SCP knees was better than in Control knees with range of motion being significantly (p < 0.05) better for SCP. Radiographic, arthroscopic, MRI, gross, microCT, and histologic findings matched the functional assessments well with Control being associated with better results at the two early time points and SCP being associated with better results at 1 and 2 years. Clinical significance: SCP treatment using calcium phosphate bone void filler was associated with an initial increase in pain and dysfunction followed by symptomatic benefits for up to 2 years after treatment for post-traumatic femoral condyle BMLs in a preclinical canine model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2709-2717, 2018.

ß-TCP bone substitutes in tibial plateau depression fractures

BACKGROUND

The use of beta-tricalciumphospate (ß-TCP, Cerasorb®) ceramics as an alternative for autologous bone-grafting has been outlined previously, however with no study focusing on both clinical and histological outcomes of ß-TCP application in patients with multi-fragment tibial plateau fractures. The aim of this study was to analyze the long-term results of ß-TCP in patients with tibial plateau fractures.

METHODS

52 patients were included in this study. All patients underwent open surgery with ß-TCP block or granulate application. After a mean follow-up of 36months (14-64months), the patients were reviewed. Radiography and computed-tomography were performed, while the Rasmussen score was obtained for clinical outcome. Furthermore, seven patients underwent biopsy during hardware removal, which was subsequently analyzed by histology and backscattered electron microscopy (BSEM).

RESULTS

An excellent reduction with two millimeters or less of residual incongruity was achieved in 83% of the patients. At follow-up, no further changes occurred and no nonunions were observed. Functional outcome was good to excellent in 82%. Four patients underwent revision surgery due to reasons unrelated to the bone substitute material. Histologic analyses indicated that new bone was built around the ß-TCP-grafts, however a complete resorption of ß-TCP was not observed.

DISCUSSION

ß-TCP combined with internal fixation represents an effective and safe treatment of tibial plateau depression fractures with good functional recovery. While its osteoconductivity seems to be successful, the biological degradation and replacement of ß-TCP is less pronounced in humans than previous animal studies have indicated.

Outcome evaluation of staged treatment for bicondylar tibial plateau fractures

BACKGROUND

The universal accepted strategy for treating high-energy tibial plateau fractures remains a topic of ongoing debate. The challenge for the practicing orthopaedic trauma surgeon is to provide anatomical articular fracture reduction, with successfully managing the complex soft-tissue injury that is commonly present at patient admission. The primary aim of the actual study was to evaluate the results of a staged protocol for the treatment of high-energy bicondylar tibial plateau fractures. The secondary aim was to describe the technique used for the definitive fixation of this complex fracture pattern.

METHODS

Thirty patients with unstable high-energy closed bicondylar tibial plateau fractures (17 Schatzker V and 13 Schatzker VI) were managed. There were 24 men (80%) and six women (20%). All of them were skeletally mature with their age ranging from 19 to 67 years (mean of 33.1±3.4 years). Treatment involved a two-stage procedure with appropriate emergency care, preoperative planning, and definitive fixation. Initial treatment, named 'damage control on complex articular fracture elements', consisted on temporary bridging external fixation. Definitive treatment was delayed in a mean of 10 days (ranging from seven to 13 days) and was performed when the soft-tissue conditioning demonstrated either complete or almost complete remission of the inflammatory reaction due to the 'first hit'. Conventional implants were used in the 30 patients. All patients were evaluated clinically and radiographically.

RESULTS

Twenty-six (86.7%) patients had a moderate level of activity, three (10%) patients had a very light level of activity, and one (3.3%) patient was unable to have any kind of work activity and is currently supported by the Brazilian Welfare. Using the visual analog scale mean pain score was 30 (ranging from 10 to 60); even the patient with the workers' compensation had no severe pain. All patients except three have no difficulty with stairs, giving way, locking, swelling, and squatting, but were unable to run. Three (10%) patients had problems with stairs and could not bend the operated knee more than 90^°. One of them had a varus knee but no instability. Ninety percent of the patients were either very satisfied or somewhat satisfied with their outcome. The three dissatisfied patients suffered postoperative complications, most commonly wound infections. Four (13.4%) patients with former anatomical reduction had a residual articular step-off or diastasis of less than 3mm after fracture healing. All patients had no or mild arthrosis at the time of the last outpatient consultation.

CONCLUSIONS

The two-staged procedure presented herein showed to be an effective strategy for managing bycondilar tibial plateau fractures. The protocol used for these complex traumatic injuries follows very well defined steps, which means acute stabilization with a linear bridging external fixation, adequate soft tissue handling, preoperative planning, and definitive surgical fixation after seven to 14 days. The model presents a more biological approach to optimizing functional outcome with an acceptable complication rate and minimal risk of loss of reduction in these high-energy tibial plateau fractures.

Evaluating augmentation with calcium phosphate cement (chronOS Inject) for bone defects after internal fixation of proximal tibial fractures: A prospective, multicenter, observational study

INTRODUCTION

Managing subchondral bone defects in proximal tibia fractures after plateau reduction is an important consideration. ChronOS Inject is a recently developed calcium phosphate bone substitute that shows relatively fast osteointegration.

HYPOTHESIS

Using chronOS Inject during internal fixation of proximal tibial fractures provides a satisfactory treatment option that is both clinically and radiologically safe.

PATIENTS AND METHODS

Patients enrolled in this study were treated with chronOS Inject bone void filler, during internal fixation of proximal tibial fractures. Patients were evaluated preoperatively and at 6 weeks, 6 and 12 months postoperative. Radiographic union was assessed using plain films supplemented by CT scans. Pain, function and adverse events were collected at all visits. A total of 36 patients were enrolled in the study and treated according to a predetermined protocol. Seven of the 36 patients (19.4%) were lost to follow-up.

RESULTS

Successful radiographic union was achieved in 27/29 (93.1%) of patients at final follow-up. Articular subsidence of>2mm only occurred in one patient. Statistical analysis showed significant improvements both in leg pain and knee function. Progress in knee function was observed in 93.1% (27/29) of patients from 6 weeks to 12 months. No product-related complications were reported.

CONCLUSIONS

Successful union was achieved based on radiographic criteria as well as clinical outcomes. When managing bone defects after internal fixation of proximal tibial fractures, the use of chronOS Inject resulted in significant improvement of knee function and reduction of leg pain.

LEVEL OF EVIDENCE

Level IV, prospective observational study.

Minimally-invasive treatment of calcaneal fractures: A review of the literature and our experience

The optimal treatment of calcaneal fractures (CF) is currently controversial and is still under debate. It is well established that conservative treatment of these fractures is associated with poor results. Several surgical techniques are described in the literature; however, there is no consensus on which of these is more effective. The main goals of surgery are to restore the subtalar joint congruence, and calcaneal width, height, shape and alignment, thus avoiding medial and lateral impingement and enabling the patient to resume a normal lifestyle. ORIF is the most popular technique for these fractures, but it is associated with high rates of wound complications, hardware failure and infections. Several minimally-invasive techniques have been developed recently for the treatment of CF, with the common aim to be as simple, effective and inexpensive as possible and to reduce surgical times, complications and length of hospital stay.

Subchondroplasty: What the Radiologist Needs to Know

OBJECTIVE

Subchondroplasty is a novel minimally invasive procedure that is used to treat painful bone marrow lesions in patients with knee osteoarthritis or insufficiency fractures. The objective of this article is to describe the surgical technique and the pre- and postoperative imaging findings of a small case series acquired at a single center.

CONCLUSION

The radiologist should be familiar with the anticipated postoperative imaging appearances after subchondroplasty and the potential complications.

Biomechanical analysis of different osteosyntheses and the combination with bone substitute in tibial head depression fractures

BACKGROUND

Tibial head depression fractures demand a high level of fracture stabilization to prevent a secondary loss of reduction after surgery. Elderly individuals are at an increased risk of developing these fractures, and biomechanical investigations of the fractures are rare. Therefore, the aim of this study was to systematically analyze different types of osteosyntheses in combination with two commonly used bone substitutes.

METHODS

Lateral tibial head depression fractures were created in synthetic bones. After reduction, the fractures were stabilized with eight different treatment options of osteosynthesis alone or in combination with a bone substitute. Two screws, 4 screws and a lateral buttress plate were investigated. As a bone substitute, two common clinically used calcium phosphate cements, Norian® Drillable and ChronOS™ Inject, were applied. Displacement of the articular fracture fragment (mm) during cyclic loading, stiffness (N/mm) and maximum load (N) in Load-to-Failure tests were measured.

RESULTS

The three different osteosyntheses (Group 1: 2 screws, group 2: 4 screws, group 3: plate) alone revealed a significantly higher displacement compared to the control group (Group 7: ChronOS™ Inject only) (Group 1, 7 [p < 0.01]; group 2, 7 [p = 0.04]; group 3, 7 [p < 0.01]). However, the osteosyntheses in combination with bone substitute exhibited no differences in displacement compared to the control group. The buttress plate demonstrated a higher normalized maximum load than the 2 and 4 screw osteosynthesis. Comparing the two different bone substitutes to each other, ChronOS™ inject had a significantly higher stiffness and lower displacement than Norian® Drillable.

CONCLUSIONS

The highest biomechanical stability under maximal loading was provided by a buttress plate osteosynthesis. A bone substitute, such as the biomechanically favorable ChronOS™ Inject, is essential to reduce the displacement under lower loading.

Mechanical behaviour of Bioactive Glass granules and morselized cancellous bone allograft in load bearing defects

Bioactive Glass (BAG) granules are osteoconductive and possess unique antibacterial properties for a synthetic biomaterial. To assess the applicability of BAG granules in load-bearing defects, the aim was to compare mechanical behaviour of graft layers consisting of BAG granules and morselized cancellous bone allograft in different volume mixtures under clinically relevant conditions. The graft layers were mechanically tested, using two mechanical testing modalities with simulated physiological loading conditions: highly controllable confined compression tests (CCT) and more clinically realistic in situ compression tests (ISCT) in cadaveric porcine bone defects. Graft layer impaction strain, residual strain, aggregate modulus, and creep strain were determined in CCT. Graft layer porosity was determined using micro computed tomography. The ISCT was used to determine graft layer subsidence in bone environment. ANOVA showed significant differences (p<0.001) between different graft layer compositions. True strains absolutely decreased for increasing BAG content: impaction strain -0.92 (allograft) to -0.39 (BAG), residual strain -0.12 to -0.01, and creep strain -0.09 to 0.00 respectively. Aggregate modulus increased with increasing BAG content from 116 to 653MPa. Porosity ranged from 66% (pure allograft) to 15% (pure BAG). Subsidence was highest for allograft, and remarkably low for a 1:1 BAG-allograft volume mixture. Both BAG granules and allograft morsels as stand-alone materials exhibit suboptimal mechanical behaviour for load-bearing purpose. BAG granules are difficult to handle and less porous, whereas allograft subsides and creeps. A 1:1 volume mixture of BAG and allograft is therefore proposed as the best graft material in load-bearing defects.

Use of a raft construct through a locking plate without bone grafting for split-depression tibial plateau fractures

PURPOSE

To review the outcome after open reduction and internal fixation using a periarticular raft construct through a locking plate without bone grafting for split-depression tibial plateau fractures.

METHODS

Records of 38 knees in 31 men and 7 women aged 25 to 75 (mean, 42.7) years who underwent open reduction and internal fixation using a periarticular raft construct through a locking plate without use of a bone graft or bone substitute for split-depression (>5 mm) proximal tibial plateau fractures (Schatzker type II or AO/OTA type 4.1 B3) were reviewed. The integrity of the articular surface was assessed using radiographs. The Rasmussen radiological score and clinical score, the Lysholm knee score, and the Tegner activity score were also assessed.

RESULTS

The mean follow-up period was 22.8 (range, 6-36) months. All patients achieved bone union after a mean of 13.2 (range, 8-26) weeks. The mean range of motion was 118º (range, 100º-130º). The Rasmussen radiological score was excellent in 27 patients, good in 9, and fair in 2. The Rasmussen clinical score was excellent in 15 patients, good in 21, and fair in 2. The Lysholm knee score was excellent in 26 patients, good in 8, and fair in 4. 32 of the 38 patients recovered to their preoperative Tegner activity scores. Only one patient with severe comminution had loss of reduction after full weightbearing.

CONCLUSION

Fixation using a periarticular raft construct through a locking plate without use of a bone graft or bone substitute for split-depression proximal tibial plateau fractures is a viable option.

Treatment of bone defect with calcium phosphate cement subsequent to tumor curettage in pediatric patients

The aim of the present study was to investigate the mid- to long-term clinical performance of calcium phosphate cement (CPC) in the treatment of benign bone tumors in pediatric patients with a follow-up of at least 2-years. The cases of 33 patients with benign bone tumors treated by curettage and subsequent implantation of CPC were retrospectively reviewed. The patients consisted of 13 males and 20 females, with a median age of 13 years and median follow-up time of 79 months. All patients were alive at the time of review. No toxicity was detected in routine blood tests. Radiography was used to confirm that CPC was well adapted to the surrounding host bone, although the resorbability of CPC was not obtained for all patients at the final follow-up. Local tumor recurrence occurred in 4 patients. None of the patients reported post-operative fractures. In total, 6 patients required a second surgical procedure, as follows: 4 patients in whom local tumor recurrence occurred; 1 patient with post-operative superficial wound infection, who underwent wound debridement; and 1 patient that required the removal of CPC due to deep infection at the proximal humerus. All patients had regained full physical function without any pain at the final follow-up. The present study recommends that the properties of CPC should be taken into consideration and applied to the reconstruction of bone defects subsequent to curettage of bone tumors.

Treatment of the benign bone tumors including femoral neck lesion using compression hip screw and synthetic bone graft

PURPOSE

The proximal femur is one of the most common locations for benign bone tumors and tumor like conditions. We describe the clinical outcomes of the surgical treatment of benign lesions of the proximal femur including femoral neck using compression hip screw and synthetic bone graft.

METHODS

Thirteen patients with benign bone tumors or tumor like conditions of the proximal femur including femoral neck were surgically treated. Their average age at the time of presentation was 35 years and the average follow-up time was 76 months.

RESULTS

The average intraoperative blood loss was 1088 mL and intraoperative blood transfusion was required in eight patients. The average operative time was 167 minutes. All patients required one week and 12 weeks after surgery before full weight-bearing was allowed. All patients had regained full physical function without pain by the final follow-up. No patient sustained a pathological fracture of the femur following the procedure. All patients achieved partial or complete radiographic consolidation of the lesion within one year except one patient who developed a local tumor recurrence in 11 months. Post-operative superficial wound infection was observed in one patient, which resolved with intravenous antibiotics. Chronic hip pain was observed in one patient due to the irritation of tensor fascia lata muscle by the tube plate.

CONCLUSION

We suggest that the treatment of benign bone lesion of the proximal femur using compression hip screw and synthetic bone graft is a safe and effective method.

Impaction bone grafting has potential as an adjunct to the surgical stabilisation of osteoporotic tibial plateau fractures: Early results of a case series

INTRODUCTION

Osteoporotic tibial plateau fractures (TPFs) are difficult to treat with either open reduction internal fixation (ORIF) or acute total knee arthroplasty (TKA). They have high complication rates, poor outcomes and often fail in the short- to mid-term. We investigated the use of impaction bone grafting (IBG) as an adjunct to stabilise the fracture in a cohort of osteoporotic TPFs.

METHODS

Nine consecutive osteoporotic TPFs were surgically stabilised with ORIF augmented with IBG or with IBG alone (one pure depression fracture) using on average allograft from 2 femoral heads/case (range 1-4 heads or 25-100 cm(3)). The median bone mineral density T-score of the patients was -2.9 (-2.5 to -4.5). All patients were mobilised weight-bearing as tolerated immediately after surgery and had regular follow-up to a minimum of 2 years where functional scores were taken and gait was assessed. Fracture reduction was assessed on plain radiographs and computed tomography (CT) scans; maintenance of fracture reduction was monitored using plain radiographs, CT and radiostereometric analysis (RSA). Bone graft remodelling was assessed by comparison of immediate post-operative CT scans with scans at a minimum of 1 year.

RESULTS

All surgeries were uneventful. All patients progressed to full weight bearing within 6 weeks of surgery and regained a normal gait by 3 months. Seven fractures healed with a cranio-caudal migration of less than 3mm (range 0-2.6mm using RSA and 0-2mm using CT). Two fractures had an isolated posterolateral fragment depression of 13.5mm and 9 mm, respectively, which did not affect the overall joint alignment or clinical outcomes at short-term follow-up. At latest CT follow-up, on average 51% of the graft area (range 36-70%) had remodelled into new host bone.

CONCLUSION

Impaction bone grafting shows promising results as an adjunct to the surgical stabilisation of osteoporotic TPFs. In this case series the technique provided enough fracture stability for patients to mobilise weight-bearing as tolerated immediately after surgery and achieve full weight-bearing by the sixth postoperative week. There was no failure of fixation and 7 of the 9 cases healed with minimal fracture displacement.

Balloon-assisted reduction, pin fixation and tricalcium phosphate augmentation for calcanear fracture

Two-thirds of hindfoot fractures involve the calcaneus. The best treatment for intraarticular fractures is still debated. The goal of treatment has been focussed for years on the anatomical reduction of the articular surface. Open reduction and internal fixation enables the surgeon to view the articular surface directly, but it is associated with a high rate of wound breakdown and infection. Therefore, length, width and angular replacement of the great tuberosity are actually the main parameters to consider when treating this type of fracture. This is a report of our experience of 20 patients treated with a minimally invasive technique of reduction using an inflatable bone tamp filled with tricalcium phosphate, with a mean follow-up of 12.25 months (range 7-26 months). Percutaneous K-wires were used to help reduction and to direct balloon inflation. Surgical goals were restoration of the mechanical stability for earlier full weight-bearing and patient mobilisation.

Bone substitute first or screws first? A biomechanical comparison of two operative techniques for tibial-head depression fractures

BACKGROUND

The aim of this study was to investigate a drillable and injectable bone substitute (calcium phosphate cement) and the operative technique enabled by the drillable option in a new biomechanical fracture model for tibial depression fractures in synthetic bones.

MATERIALS AND METHODS

Lateral depression fractures of the tibial plateau (AO 41-B2, Schatzker III) were created in a biomechanical fracture model in three different synthetic bones (Sawbone 3401, Synbone 1110/1116). Reproducible fractures were generated employing Synbone 1110, which exhibited a comparable strength to human osteoporotic bones and was used for the further experiments. After reduction of the fractures, the stabilization was performed with two different operative techniques. In group 1, first an osteosynthesis with four screws was performed and then the metaphyseal defect was filled up with calcium phosphate cement (Norian drillable). In group 2, initially the filling up with Norian drillable was done enabling a complete filling of the defect, followed by placing of the screws. Displacement under cyclic loading with 250 N for 3,000 cycles, stiffness, and maximum load in load-to-failure tests were determined.

RESULTS

A comparison of the two operative techniques of stabilization showed a distinctly lower displacement and higher stiffness for group 2 when the defect was filled up first. For the maximum load, no significant differences could be demonstrated.

CONCLUSIONS

A complete filling of the defect by first applying the calcium phosphate cement significantly reduces the secondary loss of reduction of the depression fracture fragment under cyclic loading with a clinically relevant partial weight bearing. The beneficial effects of drillable calcium phosphate cement may also be transferable to defects other than tibial-head depression fractures.

Autograft transfer from the ipsilateral femoral condyle in depressed tibial plateau fractures

Introduction :

The rationale for operative treatment of depressed tibial plateau fractures is anatomic reduction, stable fixation and grafting. Grafting options include autogenous bone graft or bone substitutes.

Methods :

The autograft group included 18 patients with depressed tibial plateau fractures treated with autogenous bone grafting from the ipsilateral femoral condyle following open reduction and internal fixation. According to Schatzker classification, there were 9 type II, 4 type III, 2 type IV and 3 type V lesions. The average time to union and the hospital charges were compared with the bone substitute group. The latter included 17 patients who had an excellent outcome following treatment of split and/or depressed lateral plateau fractures, using a similar surgical technique but grafting with bone substitutes (allografts).

Results :

Excellent clinical and radiological results were detected in the autograft group after an average follow-up of 28 months (range 12-37). The average time to union in the autograft group was 14 weeks (range 12-16), while in the bone substitute group it was 18 weeks (range 16-20). The mean total cost was 1276 Euros for the autograft group and 2978 Euros for the bone substitute group.

Discussion :

The use of autogenous graft from the ipsilateral femoral condyle following open reduction and internal fixation of depressed tibial plateau fractures provided enough bone to maintain the height of the tibial plateau and was not associated with any donor site morbidity. Using this method, the surgical time was not significantly elongated and the rehabilitation was not affected. It also exhibited faster fracture healing without postoperative loss of reduction and it was less expensive than the use of bone substitutes.

Reduction and Stabilization of Depressed Articular Tibial Plateau Fractures: Comparison of Inflatable and Conventional Bone Tamps: Study of a Cadaver Model

BACKGROUND

Restoration of articular congruity and mechanical integrity of subchondral bone are important surgical goals of the treatment of intra-articular fractures. The purpose of this study was to compare the reduction quality and biomechanical integrity between cadaveric intra-articular tibial plateau fractures reduced with an inflatable bone tamp and contralateral fractures reduced with a series of cylindrical conventional metal bone tamps.

METHODS

A standardized lateral tibial plateau split-depression fracture was created in each leg of fourteen pairs of cadaver legs. In each pair, the fracture on one side was reduced under fluoroscopy with use of an inflatable bone tamp and the fracture on the contralateral, control side was reduced with conventional bone tamps and a mallet. Any residual bone defects were filled with calcium phosphate bone-void filler. The constructs were stabilized with a lateral tibial plateau buttress plate. Each articular reduction was qualitatively graded by blinded observers using fluoroscopic images, three-dimensional computed tomography (CT) scans, and visual inspection of the articular surface. Quantitative volumetric analysis was performed to calculate under-reduction, over-reduction, and total malreduction volumes. Each reduced fracture was cyclically loaded and then statically loaded to failure under axial compression, and the strength and stiffness of the constructs were compared between sides.

RESULTS

The majority (eleven) of the fourteen fractures reduced with the inflatable bone tamp were rated as having a better reduction than the contralateral fracture reduced with the conventional bone tamps. The median over-reduction and malreduction in the inflatable-tamp group (7% and 21.6%, respectively) were significantly less than those in the conventional-tamp group (19.2% and 47.1%), although the median under-reduction (6.2% in the inflatable-tamp group and 9.6% in the conventional-tamp group) did not differ significantly between groups. The fractures reduced with the inflatable tamp displaced less during cyclic loading than those reduced with the conventional tamp. Median static stiffness and yield load were also significantly higher in the inflatable-tamp group (880 N/mm and 704 N) than in the conventional-tamp group (717 N/mm and 641 N).

CONCLUSIONS

As compared with contralateral control fractures treated with conventional bone tamps, fractures treated with an inflatable bone tamp had qualitatively and quantitatively better reduction, typically resulting in a smoother articular surface with less residual defect volume. Fractures reduced with an inflatable bone tamp exhibited less subsidence during cyclic loading and greater stiffness under static loading compared with those treated with conventional bone tamps.

CLINICAL RELEVANCE

Using an inflatable bone tamp in association with calcium phosphate bone-void filler to reduce and maintain reduction of an articular fracture may help in achieving the surgical goal of a more anatomic reduction with better resistance to subsidence.

Outcomes of Schatzker II tibial plateau fracture open reduction internal fixation using structural bone allograft

OBJECTIVES

The purpose of this study is to report the rate of anatomic reduction, articular subsidence, and clinical outcomes for Schatzker II tibial plateau fractures treated with structural bone allografts.

DESIGN

This is a retrospective case series.

SETTING

Academic Level I Trauma Center.

PATIENTS/PARTICIPANTS

A trauma registry was used to identify 77 Schatzker II tibial plateau fractures.

INTERVENTION

Schatzker II tibial plateau fracture open reduction internal fixation and structural bone graft using either Plexur P (N = 29) or fibular allograft (N = 48).

MAIN OUTCOME MEASUREMENT

The primary outcome was articular subsidence. Secondary outcomes included fracture malreduction and clinical outcomes including the Knee Outcome Survey Activities of Daily Living Scale, the Lower Extremity Functional Scale, and the Short Form (SF)-36.

RESULTS

No patients experienced subsidence > 2mm. This rate is significantly lower than published rates for autogenous iliac crest (30.3%, P < 0.0001) and calcium phosphate cement (8.7%, P = 0.0099). The rate of fracture malreduction was 11.7% (9/77); only 4 had more than 3 mm of residual incongruity. Average outcome scores were the following: Knee Outcome Survey Activities of Daily Living Scale, 81.7; Lower Extremity Functional Scale, 78.5; SF-36 physical component, 48.3; and SF-36 mental component, 53.1. There was no difference between patients treated with Plexur P or fibula with regard to the primary or secondary outcomes.

CONCLUSIONS

The use of structural allograft resulted in a high rate of anatomic reduction and negligible rate of articular subsidence and good clinical outcomes in the treatment of this population of Schatzker II tibial plateau fractures. This compares favorably with historical results using nonstructural grafts.

LEVEL OF EVIDENCE

Therapeutic level IV. See instructions for authors for a complete description of levels of evidence.

Self-setting calcium orthophosphate formulations

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided.

Microporous calcium phosphate ceramics as tissue engineering scaffolds for the repair of osteochondral defects: Histological results

Treatment of defects in joint cartilage aims to re-establish normal joint function. In vitro experiments have shown that the application of synthetic scaffolds is a promising alternative to existing therapeutic options. A sheep study was conducted to test the suitability of microporous pure β-tricalcium phosphate (TCP) ceramics as tissue engineering scaffolds for the repair of osteochondral defects. Cylindrical plugs of microporous β-TCP (diameter: 7mm; length: 25mm; porosity: 43.5±2.4%; pore diameter: ~5μm) with interconnecting pores were used. Scaffolds were seeded with autologous chondrocytes in vitro and cultured for 4weeks. A drill hole (diameter 7mm) was placed in both medial femoral condyles of sheep. For the left knee the defect was filled with a TCP plug and for the right knee the defect was left empty. After 6, 12, 26 and 52weeks, seven animals from each group were killed and studied. The samples were examined employing histological, histomorphometric and immunohistological methods as well as various imaging techniques (X-ray, microcomputer tomography and scanning electron microscopy). After explantation the cartilage defects were first assessed macroscopically. There were no signs of infection or inflammation. Histological grading scales were used for assessment of bony integration and cartilage repair. An increasing degradation (81% after 52weeks) of the ceramic with concomitant bone formation was observed. The original structure of cancellous bone was almost completely restored. After 26 and 52weeks, collagen II-positive hyaline cartilage was detected in several samples. New subchondral bone had formed. The formation of cartilage began at the outer edge and proceeded to the middle. According to the O'Driscoll score, values corresponding to healthy cartilage were not reached after 1year. Integration of the newly formed cartilage tissue into the surrounding native cartilage was found. The formation of biomechanical stable cartilage began at the edge and progressed towards the centre of the defect. After 1year this process was still not completed. Microporous β-TCP scaffolds seeded with chondrocytes are suitable for the treatment of osteochondral defects.

Controlling the biological function of calcium phosphate bone substitutes with drugs

There is a growing interest in bone tissue engineering for bone repair after traumatic, surgical or pathological injury, such as osteolytic tumor or osteoporosis. In this regard, calcium phosphate (CaP) bone substitutes have been used extensively as bone-targeting drug-delivery systems. This localized approach improves the osteogenic potential of bone substitutes by delivering bone growth factors, thus extending their biofunctionality to any pathological context, including infection, irradiation, tumor and osteoporosis. This review briefly describes the physical and chemical processes implicated in the preparation of drug-delivering CaPs. It also describes the impact of these processes on the intrinsic properties of CaPs, especially in terms of the drug-release profile. In addition, this review focuses on the potential influence of drugs on the resorption rate of CaPs. Interestingly, by modulating the resorption parameters of CaP biomaterials, it should be possible to control the release of bone-stimulating ions, such as inorganic phosphate, in the vicinity of bone cells. Finally, recent in vitro and in vivo evaluations are extensively reported.

Calcium phosphate cements as drug delivery materials

Calcium phosphate cements are used as synthetic bone grafts, with several advantages, such as their osteoconductivity and injectability. Moreover, their low-temperature setting reaction and intrinsic porosity allow for the incorporation of drugs and active principles in the material. It is the aim of the present work to: a) provide an overview of the different approaches taken in the application of calcium phosphate cements for drug delivery in the skeletal system, and b) identify the most significant achievements. The drugs or active principles associated to calcium phosphate cements are classified in three groups, i) low molecular weight drugs; ii) high molecular weight biomolecules; and iii) ions.

Effective combination of bone substitute and screws in the jail technique: a biomechanical study of tibial depression fractures

PURPOSE

The aim of this study was to investigate a new drillable calcium phosphate cement (Norian drillable Synthes GmbH) as a bone substitute either alone or in combination with screws in the jail technique (Petersen et al. Unfallchirurg Mar 109(3):219-234, 2006; Petersen et al. Unfallchirurg Mar 109(3):235-244, 2006) with regard to the primary stability in lateral tibial depression fractures.

METHODS

Lateral depression fractures of the tibial plateau were created in a biomechanical fracture model. After reduction they were stabilised with bone substitute (group one), bone substitute with additional four screws in the jail technique (group two) or four screws only (group three). Displacement under cyclic loading, stiffness and maximum load in load-to-failure tests were determined.

RESULTS

The groups with the bone substitute showed a lower displacement of the depressed articular fragment under cyclical loading and a higher stiffness. The maximum load was higher for the groups with screws.

CONCLUSIONS

Only the combination of bone substitute and screws prevented secondary loss of reduction and, at the same time, provided enough stability under maximum load.

Balloon tibioplasty: a useful tool for reduction of tibial plateau depression fractures

Reduction of the articular surface in displaced tibial plateau fractures is still challenging and may result in joint incongruence, leading to posttraumatic arthrosis. Conventional techniques use bone tamps and similar instruments, which can increase the surgical trauma due to their size. "Balloon tibioplasty" is a novel minimally invasive technique for the reduction of depressed tibial plateau fractures. We successfully applied an inflatable balloon, commercially available from kyphoplasty, to elevate the depressed articular fragments. This technique allowed for reduction of the depressed tibial plateau fragment without classic fenestration of the tibia, thereby minimizing surgical trauma. Furthermore, under fluoroscopic control, optimal centering of the expanding tibioplasty balloon allows a widespread and continuously increasing reduction force to the fracture area. After fluoroscopy or arthroscopic confirmation of reduction of the articular surface, the cavity resulting from tibioplasty was filled with ceramic bone cement through small incisions and fractures were fixed with a small fragment locking T-plate (3.5 mm). Balloon tibioplasty was applied in 5 patients with displaced tibial plateau fractures (OTA type B2/3). No intra- or postoperative complications were observed. This new technique may be a useful tool to facilitate the reduction of select depressed tibial fractures in the future.