Lateral Femoral Trochlea Osteochondral Flap Reconstruction of Proximal Pole Scaphoid Nonunions

PURPOSE

The medial femoral trochlea flap has been described as a method of scaphoid proximal pole nonunion reconstruction when the proximal pole is deemed nonsalvageable. The lateral femoral trochlea (LFT) is an alternative donor site providing a comparable vascularized convex osteochondral flap. We describe the technique and outcomes of our first 17 cases of LFT flap reconstruction of the proximal scaphoid pole with a minimum follow-up of 14 months.

METHODS

Seventeen of the first 24 patients who underwent LFT scaphoid reconstruction at 3 institutions were able to be contacted for clinical follow-up and chart reviews. We recorded patient age and sex, duration of nonunion, number of previous surgical procedures, details of surgical technique, achievement of osseous union, complications, additional postoperative procedures, preoperative and postoperative pain, and range of motion. Preoperative and postoperative scapholunate and radiolunate angles were analyzed on x-rays and achievement of osseous union on computerized tomography scans.

RESULTS

The average age of patients included was 35 years (range, 16-55 years). Follow-up data were recorded at an average of 33 months (range, 14-62 months). Ten patients had previous procedures (average, 1; range, 0-2). Median duration from trauma to LFT was 3.4 years (range, 8 months-12 years) among patients who had a recognized date of injury. Osseous healing was achieved in 16 of 17 patients and confirmed by computerized tomograpy scan. Twelve patients reported complete pain relief, while 5 reported partial pain relief. Final postoperative range of motion was 59°extension (range, 30°-85°) and 50° flexion (range, 10°-80°), which was comparable to preoperative values. Preoperative (59°) and postoperative (55°) scapholunate angles were similar to normal wrists.

CONCLUSION

Vascularized LFT flaps provide an alternative donor site for vascularized osteochondral reconstruction of proximal pole scaphoid nonunion. Rate of union, range of motion, and pain relief are similar to reported results with medial femoral trochlea flap reconstruction.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The use of vascularized fibula flap with allograft in post-oncologic microsurgical bone reconstruction of lower limbs in pediatric patients

BACKGROUND

Post-oncologic surgical reconstruction of lower limbs in pediatrics remains a challenging topic. Microsurgical techniques allow reconstructions of large bony defects. The use of vascularized fibular flap with allograft has proven to be an ideal biologic construct. We aim to assess the success rate of this operation, including flap survival, bony union, weight-bearing ambulation, and complications in a long-term follow-up in our case series compared to the literature.

PATIENTS AND METHODS

Our case-series includes 18 femoral resections (9 osteosarcomas, 8 Ewing sarcoma, and 1 desmoid tumor) and 15 tibial resections (10 osteosarcoma, 4 Ewing sarcoma, and 1 Malignant Fibrous Histiocytoma). We collected patients' demographics, type of tumor, type of resection, defect size, fibula-flap length, method of fixation, anastomosis site, follow-up data, complications, and their management. All survivals were examined by X-ray and CT-scan to evaluate the morphological changes of the vascularized fibula and follow-up. The functional evaluation was performed by the 30-point Musculoskeletal Tumor Society Rating Score (MSTS) for the lower limb (Enneking et al., Clinical Orthopaedics and Related Research 1993(286):241-246).

RESULTS

The mean age of the femur resection patients' group was 11.2 years with a mean defect size of 14 cm and a mean length of the fibular flap of 18 cm; for the tibia the mean age was 12 years with a mean defect size of 14 cm and a mean length of the fibular flap of 16.6 cm. The overall survival of the reconstructions at 5 years follow-up was 17 out 18 cases for the femur and 13 out of 15 cases for the tibia. MSTS score was 28.2 for the femur and 23.7 for the tibia. The average time of union of the fibula was seen after 5 months, while allograft consolidation was observed around 19.7 months. The mean time of follow-up was 144.5 months for the femur and 139.2 months for the tibia. The complication rate observed was 7 out of 18 for the femur and 7 out of 15 for the tibia reconstructions.

CONCLUSIONS

The viability of the fibula is a cornerstone in the success of reconstruction as well as the successful management of complications in intercalary defects after tumor resection in pediatrics to restore good functionality. Our results are in line with those reported in the literature in terms of overall complication rates. The high primary union of allograft, the high MSTS score obtained, and the low rate of severe complications reflect the mechanical role of this reconstructive technique over a long follow-up.

Idiopathic Avascular Necrosis of the Capitate Treated with a Medial Femoral Trochlea Vascularized Osteochondral Flap: A Case Report

CASE

Capitate avascular necrosis should be entertained in a differential diagnosis of young, active adults with midcarpal wrist pain. We present a case study of a 30-year-old laborer who developed avascular necrosis (AVN) of his right proximal capitate. Grip strength and wrist motion were limited on examination, with advanced imaging confirming AVN. A diagnostic arthroscopy confirmed the pathology. Treatment was completed with a medial femoral trochlea vascularized flap for cartilaginous resurfacing. At 10-month follow-up, the patient's capitate was healed with stable fixation, and he is working full-time as a laborer without restrictions.

CONCLUSION

AVN of the capitate is a unique and challenging articular pathology that requires a thoughtful preoperative evaluation and meticulous surgical technique to reconstruct. The medial femoral trochlea (MFT) vascularized bone transfer with cartilaginous resurfacing is 1 available treatment option. This flap is harvested from the medial femur using microsurgical techniques, based on the descending genicular artery. Using a 2-surgeon approach, simultaneous dissection of the AVN is completed at the wrist. This flap is a vascularized option that can be used for both AVN and nonunion with structural deformity before salvage surgeries.

Comparing the efficacy of syngeneic iliac and femoral allografts with iliac crest autograft in a rat model of lumbar spinal fusion

BACKGROUND

Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer-irrigator-aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion.

METHODS

Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft, syngeneic iliac crest allograft, and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation, and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources.

RESULTS

Although no differences were observed between groups in CT fusion mass volumes, iliac allografts displayed an increased number of radiographically fused fusion masses and a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow.

CONCLUSIONS

This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

Free vascularized medial femoral condyle corticoperiosteal flap with non-vascularized iliac crest graft for the treatment of recalcitrant clavicle non-union

Clavicle non-union is a challenging problem. Open reduction with internal fixation and autologous bone grafting is usually the first line treatment. In case of failure, the medial femoral condyle corticoperiosteal flap in association with a non-vascularized bone graft is one of the therapeutic options, which is well adapted to the clavicle anatomical characteristics. We performed a retrospective study of all patients treated with this technique in our department. Between 2014 and 2017, five patients with recalcitrant post traumatic clavicle non-unions received this surgical treatment. The average nonunion time period was 50.2 month (range 10 to 108 months), and the mean defect length was 3.4 cm (between 2 and 5 cm), defects were all located in the medial third of the clavicle Three patients achieved full consolidation with an average time of consolidation of 8,7 months (range 6 to12 months). Patients with radiological consolidation had better functional improvement and pain reduction with an average DASH score improved from 53,6 before surgery to 19,6 after consolidation (at the last follow up visit). There was one donor site complications (hematoma). The medial femoral condyle corticoperiosteal flap with non-vascularized iliac crest graft is a good option for the management of recalcitrant clavicle non-union, especially when the bone defect is small.

USE OF MEDIAL FEMORAL CONDYLE FLAP AND ANTEROLATERAL THIGH FREE FLAP IN PROXIMAL TIBIAL POSTTRAUMATIC NON-UNION WITH MULTIPLE ANASTOMOSIS - CASE REPORT

Fractures of the proximal tibia are high energy fractures. According to available literature, 3-4% of all fractures heal problematically with non-union or osteomyelitis. Usage of locking compression plating system as well as usage of hybrid fixator is associated with the risk of compartment syndrome, local infection and subsequent malunion, osteomyelitis or non-union. We present a case of 30-year-old male suffering from posttraumatic non-union. The medial femoral condyle flap was selected due to its favourable properties providing a highly vascularised osteogenic tissue in combination with anterolateral thigh flap and Corlett loop. Our case report describes a reconstruction of a long weight-bearing bone. Despite the amount of anastomoses and usage of vein graft, the selected method of reconstruction seems to be safe and with a long-lasting benefit for the patient.

The vascularized medial femoral condyle free flap for reconstruction of segmental recalcitrant nonunion of the clavicle

BACKGROUND

Recalcitrant clavicular nonunion is a rare but complicated problem of clavicular fracture fixation. Nonunion is most often treated with clavicular shortening or in extreme cases vascularized bone grafting. Herein we describe our experience using the vascularized medial femoral condyle (MFC) free flap for the reconstruction of segmental defects in cases of recalcitrant clavicular nonunion.

METHODS

A retrospective chart review was conducted of patients with symptomatic recalcitrant nonunion of the clavicle who underwent reconstruction with the vascularized MFC free flap from June 2003 to January 2018. Patients' demographics, time to union, and postoperative complications were collected.

RESULTS

A total of 7 patients (6 women; 39.8 ± 9.01 years old) underwent clavicular reconstruction after an average of 3.7 ± 1.3 previous surgical procedures. Average preoperative visual analog scale score for pain was 4.1. The graft size ranged from 2 to 5 cm in length with approximately 1 cm in width and depth. The average time of total nonunion was 66 ± 48.2 months before surgery. All flaps survived and all clavicles healed with an average time to radiographic union of 15 ± 6.7 months. Patients regained full shoulder motion, and average postoperative visual analog scale score was 1.6 ± 1.8. All patients returned to their preoperative employment status. Donor site morbidity from the knee was minimal.

CONCLUSION

The MFC free flap is a good option for recalcitrant bone nonunion of the clavicle where larger vascularized flaps are not warranted. It is effective and offers minimal donor site morbidity.

Microvascular reconstructive techniques in orthopaedic traumatology

Great evolution has taken place in Orthopaedic Traumatology, regarding techniques, surgical means and equipment. However, we still encounter complicated cases of limb trauma that necessitate microvascular reconstruction. Through three different illustrative cases (one emergency foot revascularization by a free flap, covering an ankle arthrodesis and bridging the anterior tibial artery, one cure of a complex infected tibial non-union with extensive skeletal defect by double barrel fibular transfer and one osteo-chondral reconstruction of the scaphoid proximal pole using a vascularized graft harvested from the femoral medial condyle), the authors remind the Orthopaedic community about the benefits of microsurgery, especially if used in proper indication and timing. This article is a plea to preserve the knowledge and develop the technical abilities of microvascular techniques in the departments of Orthopaedics and Traumatology.

Capacity of the medullary cavity of tibia and femur for intra-bone marrow transplantation in mice

Intra-bone marrow transplantation (IBMT) has been adapted for mouse models to improve the seeding efficiency of transplanted hematopoietic stem and progenitor cells. Commonly used injection volumes for IBMT into the tibia differ between 10 and 40 μL even though considerable amounts of injected cells leak into the blood circulation immediately after injection. Injection of 3 μL trypan blue into the tibia of dead BALB/c mice showed staining in large vessels of hind limbs, even without supporting circulation. We therefore tested the effective capacity of the medullary cavity of dissected tibiae and femora of different mouse strains by bioluminescence imaging after injection of luciferase expressing cells. Cell leakage was already observed at 3 μL of injection volume and the measured emission rate increased significantly when 5 and 10 μL of volume with the same cell concentration were injected. Surprisingly, increasing injection volumes containing constant cell amounts resulted in comparable emission rates, suggesting a similar amount of leaked and absorbed cells independent of the injection volume. However, the absorption of a specific amount of injected cells could not be confirmed, as the ratio of leaked to absorbed cells was similar between IBMT that were performed with a constant injection volume containing either low or high cell amounts. In summary, for optimal cell transplantation via IBMT in mice we suggest to inject a high concentrated cell suspension with a maximum injection volume of 3 μL.

Three-dimensional printed surgical templates for fresh cadaveric osteochondral allograft surgery with dimension verification by multivariate computed tomography analysis

BACKGROUND

The fit of the allograft is a particular concern in fresh cadaveric osteochondral allograft (FOCA) surgery. Digital design and fabrication were utilized in conjunction with traditional surgery to enable efficient discovery and reproduction of appropriately dimensioned allograft.

METHODS

A patient with large osteochondral defects in the lateral femoral condyle was to undergo FOCA surgery. A digital virtual operation was performed, based on computed tomography (CT) images of the patient. Polyamide saw templates were manufactured using a selective laser sintering process, and gypsum powder was used to manufacture preoperative and intraoperative medical models with binder jetting process. The design dimensions were verified numerically by determining the intactness of the section surface and allograft volume based on four independent measurements of the initial design, and an automated design optimization strategy was postulated. For the surgery, a lateral longitudinal approach was employed.

RESULTS

The virtual operation allowed an efficient design of the saw templates. Their shape and dimensions were verified with a numerical CT analysis method. The allograft dimensions (medial-lateral/superior-inferior/anterior-posterior) were approximately 40/28.5/24 mm, respectively, with the anterosuperior corner diagonally removed, yielding a section volume of approximately 16.5 cm³. These manually chosen dimensions were reminiscent of the corresponding computationally optimized values.

CONCLUSIONS

Use of computer-aided design in virtual operation planning and three-dimensional printing in the fabrication of designed templates allowed for an efficient FOCA procedure and accurate allograft fitting. The numerical optimization method allowed for a semiautomated design process, which could in turn be realized also with surgical navigation or robotic surgery methods.

Polyhydroxyalkanoate (PHBV) fibers obtained by a wet spinning method: Good in vitro cytocompatibility but absence of in vivo biocompatibility when used as a bone graft

Polyhydroxyalkanoates (PHAs) are biomaterials widely investigated for tissue-engineering applications. In this regard, we describe a method to prepare fibers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by a wet-spinning technique. Polymer fibers were used to test the cytocompatibility of the material in vitro. We have investigated their behavior in vitro in presence of the osteoblast-like (SaOs2) and macrophage (J774.2) cell lines. The PHBV fibers used were 100-200μm in diameter and offered a large surface for cell adhesion, similar to that they encounter when apposed onto a bone trabeculae. The fiber surface possessed a suitable roughness, a factor known to favor the adherence of cells, particularly osteoblasts. PHBV fibers were degraded in vitro by J774.2 cells as erosion pits were observable by transmission electron microscopy. The fibers were also colonisable by SaOs2 cells, which can spread and develop onto their surface. However, despite this good cytocompatibility observed in vitro, implantation in a bone defect drilled in rabbit femoral condyles showed that the material was only biotolerated without any sign of osteoconduction or degradation in vivo. We can conclude that PHBV is cytocompatible but is not suitable to be used as a bone graft as it does not favor osteoconduction and is not resorbed by bone marrow macrophages.

Ribose pre-treatment can protect the fatigue life of γ-irradiation sterilized bone

Structural bone allografts are often sterilized with γ-irradiation to decrease infection risk, which unfortunately degrades the bone collagen connectivity, making the bone weak and brittle. In previous studies, we successfully protected the quasi-static mechanical properties of human cortical bone by pre-treating with ribose, prior to irradiation. This study focused on the quasi-static and fatigue tensile properties of ribose treated irradiated sterilized bone allografts. Seventy-five samples were cut from the mid-shaft diaphysis of human femurs into standardized dog-bone shape geometries for quasi-static and fatigue tensile testing. Specimens were prepared in sets of three adjacent specimens. Each set was made of a normal (N), irradiated (I) and ribose pre-treated + irradiation (R) group. The R group was incubated in a 1.2 M ribose solution before γ-irradiation. The quasi-static tensile and decalcified tests were conducted to failure under displacement control. The fatigue samples were tested under cyclic loading (10 Hz, peak stress of 45MP, minimum-to-maximum stress ratio of 0.1) until failure or reaching 10 million cycles. Ribose pre-treatment significantly improved significantly the mechanical properties of irradiation sterilized human bone in the quasi-static tensile and decalcified tests. The fatigue life of the irradiated group was impaired by 99% in comparison to the normal control. Surprisingly, the R-group has significantly superior properties over the I-group and N-group (p < 0.01, p < 0.05) (> 100%). This study shows that incubating human cortical bone in a ribose solution prior to irradiation can indeed improve the fatigue life of irradiation-sterilized cortical bone allografts.

Effect of Bisphosphonate Pretreatment on Fresh Osteochondral Allografts: Analysis of In Vitro Graft Structure and In Vivo Osseous Incorporation

Fresh allograft transplantation of osteochondral defects restores functional articular cartilage and subchondral bone; however, rapid loss of chondrocyte viability during storage and osteoclast-mediated bone resorption at the graft-host interface after transplantation negatively impact outcomes. The authors present a pilot study evaluating the in vitro and in vivo impact of augmenting storage media with bisphosphonates. Forty cylindrical osteochondral cores were harvested from femoral condyles of human cadaveric specimens and immersed in either standard storage media or storage media supplemented with nitrogenated or non-nitrogenated bisphosphonates. Maintenance of graft structure and chondrocyte viability were assessed at 3 time points. A miniature swine trochlear defect model was used to evaluate the influence of bisphosphonate-augmented storage media on in vivo incorporation of fresh osteochondral tissue, which was quantified via μCT and decalcified histology. In the in vitro study, Safranin-O/Fast Green staining showed that both low- and high-dose nitrogenated-treated grafts retained chondrocyte viability and cartilage matrix for up to 43 days of storage. Allografts stored in nitrogenated-augmented storage media showed both μCT and histologic evidence of enhanced in vivo bony and cartilaginous incorporation in the miniature swine trochlear defect model. Several preclinical studies have shown the potential for enhanced storage of fresh osteochondral allografts via additions of relatively common drugs and biomolecules. This study showed that supplementing standard storage media with nitrogenated bisphosphonates may improve maintenance of chondrocyte viability and graft structure during cold storage as well as enhance in vivo osseous and cartilaginous incorporation of the graft. [Orthopedics: 2018; 41(3):e376-e382.].

Osteoarticular Allograft Transplantation of the Trochlear Groove for Trochlear Dysplasia: A Case Report

CASE

A 21-year-old woman with recurrent lateral patellar instability caused by severe trochlear dysplasia and concomitant grade-IV trochlear chondromalacia was treated successfully with osteoarticular allograft transplantation of the entire trochlear groove.

CONCLUSION

The treatment of chronic lateral patellar instability caused by trochlear dysplasia can be challenging. When nonoperative treatment is unsuccessful, a sulcus-deepening trochleoplasty may be indicated. However, contraindications for a trochleoplasty include grade-IV chondromalacia of the patellofemoral joint. Even with this contraindication, an osteoarticular allograft transplant of the trochlear groove can serve as a salvage procedure to improve knee function.

Vascularized Medial Femoral Condyle Graft for Manubrium Nonunion: Case Report and Review of the Literature

Fractures of the sternum are rare. Persistent nonunions, however, can lead to chronic pain and significant functional limitations. The vascularized medial femoral condyle is a versatile tool in the surgeon's armamentarium. Traditionally, it has been used as a thin corticoperiosteal graft in the treatment of nonunion of tubular bones. Its use as a structural corticocancellous graft has also been expanding. This report presents a case of a patient with a recalcitrant symptomatic nonunion of the manubrium treated with the unique combined corticoperiosteal and corticocancellous vascularized bone graft from the medial femoral condyle and reviews the literature concerning these uncommon nonunions. (Journal of Surgical Orthopaedic Advances.

High dose teriparatide (rPTH1-34) therapy increases callus volume and enhances radiographic healing at 8-weeks in a massive canine femoral allograft model

Small animal studies have demonstrated significant high-dose recombinant parathyroid hormone1-34 (rPTH1-34) effects on intercalary allograft healing. Towards a human adjuvant therapy to decrease non-unions, we evaluated rPTH1-34 safety and efficacy in a clinically relevant canine femoral allograft model. Adult female mongrel hounds (n = 20) received a 5cm mid-diaphyseal osteotomy reconstructed with a plated allograft, and were randomized to: 1) Placebo (n = 5; daily saline), 2) Continuous rPTH1-34 (n = 7; 5 μg/kg/day s.c. from day 1-55 post-op), or 3) Delayed rPTH1-34 (n = 8; 5 μg/kg/day s.c. from day 14-28 post-op). Safety was assessed by physical behavior and blood calcium monitoring. Cone beam CT (CB-CT) was performed on days 14, 28 and 56 post-op to assess 2D cortical healing, 3D bone volume, and Union Ratio. Biomechanical testing and dynamic histomorphometry were also performed. The high drug dose was poorly tolerated, as most dogs receiving rPTH1-34 had to be given intravenous saline, and one dog died from hypercalcemia. Continuous rPTH1-34 significantly increased 2D healing and callus volumes at 4-weeks versus Placebo, and sustained the significant increase in cortical union at 8-week (p<0.05). These rPTH1-34 effects were confirmed by histomorphometry, revealing significant increases in mineral apposition rates (MAR) on host bone and graft-host junctions (p<0.05). Delayed rPTH1-34 significantly increased callus volume and MAR at 8 weeks (p<0.05). Although no biomechanical differences were observed, as expected for early healing, the results demonstrated that 2D RUST scoring significantly correlated with torsional biomechanics (p<0.01). In conclusion, 8-weeks of intermittent high-dose rPTH1-34 treatment significantly increases callus formation and accelerates bony union of intercalary massive allografts in a clinically relevant canine model, but with serious side-effects from hypercalcemia.

The treatment of long bones nonunions of upper limb with microsurgical cortico-periosteal free flap

BACKGROUND AND PURPOSE

Medial condyle corticoperiosteal flap is an emerging option for the treatment of upper limb non-infected nonunions. The hypothesis of our study is that corticoperiosteal flap could be an effective and safe procedure for the treatment of upper limb non-infected nonunions, evaluating radiographic and clinical outcome.

METHODS

We enrolled 14 patients who underwent vascularized medial femoral condyle corticoperiosteal free flaps from January 2011 to December 2014. All patients were clinically evaluated (VAS, DASH) before surgery and at 6 and 12 months post surgery. The radiographic evaluation was performed every 30 days until the complete healing and at 12-month follow-up. We also recorded the range of motion pre and post surgery at the donor site.

RESULTS

All nonunion sites healed primarily at an average time period of 5.2 months ±1. Preoperative DASH score was 70 ± 15.6; at 6 month follow-up was 21.51 ± 10.63; at 12 month follow-up 18.0 ± 9.9. Preoperative VAS was 7.05 ± 2; at 6-month follow-up was 2.1 ± 2; at 12-month follow-up was 1.8 ± 1.16. Statistical analysis showed a significant difference (p <0.001) about the preoperative and the postoperative VAS and DASH evaluation both at 6 and 12-month follow-up, but we did not record any statistical difference between the 6-month and 12-month follow-up. At the donor site, the mean VAS score was 2 ± 2.1 at seven days post operatively. All patients restore the full ROM at 7 days post surgery.

CONCLUSIONS

Vascularized medial condyle corticoperiosteal free flap represents an effective and safe procedure for the treatment of upper limb nonunions.

Knockdown of toll-like receptor 4 signaling pathways ameliorate bone graft rejection in a mouse model of allograft transplantation

Non-union occurring in structural bone grafting is a major problem in allograft transplantation because of impaired interaction between the host and graft tissue. Activated toll-like receptor (TLR) induces inflammatory cytokines and chemokines and triggers cell-mediated immune responses. The TLR-mediated signal pathway is important for mediating allograft rejection. We evaluated the effects of local knockdown of the TLR4 signaling pathway in a mouse segmental femoral graft model. Allografts were coated with freeze-dried lentiviral vectors that encoded TLR4 and myeloid differentiation primary response gene 88 (MyD88) short-hairpin RNA (shRNA), which were individually transplanted into the mice. They were assessed morphologically, radiographically, and histologically for tissue remodeling. Union occurred in autografted but not in allografted mice at the graft and host junctions after 4 weeks. TLR4 and MyD88 expression was up-regulated in allografted mice. TLR4 and MyD88 shRNAs inhibited TLR4 and MyD88 expression, which led to better union in the grafted sites. More regulatory T-cells in the draining lymph nodes suggested inflammation suppression. Local inhibition of TLR4 and MyD88 might reduce immune responses and ameliorate allograft rejection.

The chorioallantoic membrane (CAM) assay for the study of human bone regeneration: a refinement animal model for tissue engineering

Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p < 0.01). This human-avian system offers a simple refinement model for animal research and a step towards a humanized in vivo model for tissue engineering.

[One-stage bone grafting combined with non-contact plate technique for treatment of post-traumatic femoral osteomyelitis and bone defects]

Eight patients with femoral osteomyelitis were admitted in Lanzhou General Hospital of PLA between July 2012 and July 2015. During the operation the femur was fixed with non-contact locking plate after thorough debridement. Iliac morselized cancellous bones without cortical bone were filled in the bone defect after debridement. The locking plates were placed in the lateral subcutaneous interface superficial to the vastus lateralis muscle. Drainage tubes were routinely placed postoperatively. The surgery was completed successfully in all patients, and the average operation time was (130±10) min (120-150 min). Intravenous antibiotics were administrated for 2 weeks and followed by 4 week-oral antibiotics after the operation in all 8 cases. Drainage tubes remained in situ about 8 days. All patients were followed up for 12-48 months, with an average of (19±7) months. Postoperative X-ray examination showed bone union in 7 cases with an average healing time of (16±5) weeks. One patient failed with relapsed infection, and was later treated with Ilizarov apparatus after secondary debridement. No plate and screw fracture, loose and fixation failure were observed in all 8 cases.

Mosaicplasty for femoral osteochondritis dissecans

The authors describe a surgical mosaicplasty technique, with an anterior surgical dislocation approach without trochanterotomy, for osteochondritis dissecans of the hip. A graft was taken from the lateral condyle of the knee. Two adolescents underwent this procedure with good results. No osteonecrosis was observed at the longest follow-up. Mosaicplasty is a useful treatment method for small osteochondritis dissecans (<2cm(2)).

[Healing of experimental defect in a long bone after implantation of "CollapAn" osteoplastic material in its cavity (computed tomographic study)]

The dynamics of biodegradation of "CollapAn" osteoplastic material was studied after its implantation into the defect of the femoral diaphysis in 30 rats. Computed tomographic analysis of the healing of bone defects was conducted with the determination of the optical density of bone tissue in Hounsfield units. Since Day 30 of the experiment, the appearance and further progress of the radiographic signs of bone tissue neoformation and maturation were noted exactly along the contours of osteoplastic material, together with the gradual disappearance of the defect from the side of bone cortical layer and simultaneous increase of the optical density of the intermediary and endosteal part of the regenerate. At Day 120, regenerate optical density exceeded the absolute optical density of the parent bone; simultaneously, during this period no full recovery of the original shape of the bone took place, while parent bone rarefication was identified during all the periods of observation.

Utility of computed tomography arthrograms in evaluating osteochondral allograft transplants of the distal femur

Postsurgical evaluation of osteochondral allograft transplant surgery (OATS) of the distal femur most commonly utilizes radiographs or magnetic resonance imaging. This article proposes the utilization of computed tomography (CT) arthrography as an additional option, which allows clear assessment of articular congruity and osseous integration. A retrospective review was performed of 18 patients who underwent an OATS for distal femoral chondral lesions and obtained CT arthrograms postoperatively. CT arthrograms were evaluated for osseous integration and articular congruity. The average age and follow-up were 30.9 years and 4.3 years, respectively. Only 60% of patients were able to remain in the military postoperatively. The articular cartilage was smooth in eight (44.4%); complete bony integration was noted in eight (44.4%) patients. Neither articular congruity nor bony integration was associated with duty status at final follow-up. Although it allows excellent evaluation, similar to other modalities, CT arthrogram does not appear predictive of functional outcome.

Surgical revascularization in structural orthotopic bone allograft increases bone remodeling

BACKGROUND

Osseous defects reconstructed with cryopreserved structural allografts are poorly revascularized and therefore are prone to nonunion, infection, deterioration of mechanical properties, and fracture. Whether this can be mitigated by specific interventions such as intramedullary surgical revascularization has been incompletely evaluated.

QUESTIONS/PURPOSES

We aimed to study surgical revascularization as a means to improve bone remodeling in cryopreserved allograft. Second, we questioned whether spatial histomorphometric differences occur in cortical bone areas after intramedullary surgical revascularization. Third, biomechanical properties of the graft-recipient construct in surgically revascularized allograft were compared with those of conventional allografts.

METHODS

Allografts were harvested from 10 Brown Norway rats, cryopreserved, and transplanted orthotopically in a 10-mm defect in two groups of 10 Lewis rats each (major histocompatibility mismatch). In the control group, no surgical revascularization was performed, whereas in the experimental group, a saphenous arteriovenous bundle was transposed in the bone marrow cavity. Bone remodeling was measured with histomorphometry, histology, and microcomputed tomography at 16 weeks. Spatial differences were analyzed with histomorphometry. To determine biomechanical properties, load at failure and structural stiffness in bending were evaluated by the three-point bend testing. In both groups, normal values of the contralateral femur also were analyzed.

RESULTS

Surgically revascularized allografts had increased bone remodeling (bone formation rate to bone surface ratio: 130 ± 47 µm(3)/µm(2)/year versus 44 ± 43 µm(3)/µm(2)/year, p = 0.006) and higher cortical osteocyte counts (18.6% ± 12.7% versus 3.1% ± 2.8%, p = 0.002) than nonrevascularized grafts. In nonrevascularized grafts, the bone formation rate to bone surface ratio was 35% of the contralateral normal values, whereas in surgically revascularized grafts, the bone formation rate to bone surface ratio in the grafts exceeded the contralateral values (110%). Microcomputed tomography did not show differences in bone volume between groups, however in both groups, bone volume was less in grafts compared with the contralateral femurs. Inner cortical bone formation rate to bone surface ratio was greater in surgically revascularized grafts (65 ± 30 µm(3)/µm(2)/year versus 13 ± 16 µm(3)/µm(2)/year in the control group, p = 0.012). Outer cortical bone formation rate to bone surface ratio also increased in surgically revascularized grafts (49 ± 31 µm(3)/µm(2)/year versus 19 ± 21 µm(3)/µm(2)/year, p = 0.032). No differences were found in load at failure and structural stiffness between both groups. In the control group, load at failure and structural stiffness were lower in grafts than in the contralateral femurs (p = 0.004 and p = 0.02, respectively). In the experimental group, surgically revascularized grafts also had lower load at failure and structural stiffness than the contralateral femurs (p = 0.008 and p = 0.02, respectively).

CONCLUSIONS

Surgical revascularization of large segmental allografts improved bone remodeling and viability without an adverse effect on total bone volume or bending strength and stiffness in this short-term analysis.

CLINICAL RELEVANCE

Cryopreserved allografts remain largely necrotic and are associated with a high rate of complications. Surgical revascularization increases graft healing which could contribute to graft survival with time.

Sequential harvesting of bone graft from the intramedullary canal of the femur

The effectiveness of using the Reamer/Irrigator/Aspirator (RIA) System (Synthes, Inc, West Chester, Pennsylvania) to obtain bone graft from the intramedullary canal of long bones for the treatment of bone defects and nonunions has been previously documented. However, there is nothing in the literature discussing the potential for reaming the same canal at subsequent surgeries. The authors detail their experience of 8 instances of sequential reaming in 7 patients. Six patients were harvested twice, and 1 patient was harvested 3 times. In each patient, the bone graft was obtained from the same canal. The main outcome measurements were time interval between reamings, reamer head size, indication for reaming, volume of harvested bone graft, and complications. Average volume of graft obtained in the first reaming procedure was 34 mL (range, 25-50 mL). After an average of 9 months (range, 3-16 months), the subsequent reaming was performed. Average volume of graft obtained in the second procedure was 45 mL (range, 28-65 mL). In the authors' series, no reaming-related complications were observed. The graft volume was the same or increased during the subsequent intramedullary reaming in all but 1 case, suggesting that the intramedullary canal is a potentially renewable source for bone graft. There were no complications related to the sequential reaming procedure. Overall, the authors' data suggest that sequential reaming with the RIA has the potential to safely and effectively provide a large quantity of bone graft on multiple occasions.