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.

[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.

Low-intensity pulsed ultrasound therapy stimulates callus formation between host femur and cortical onlay strut allograft

Cortical onlay strut allografting is a promising surgical option to reconstruct and reinforce the deficient femur in a hip arthroplasty. However, the union of the allograft to the host bone takes a long time. To accelerate the process of cortical onlay strut allograft healing, we studied the effects of low-intensity pulsed ultrasound (LIPUS) on callus formation. From 2 wk after the operation, LIPUS was given for 20 min/d at each end of the strut allograft. The LIPUS treatment group was assigned 14 allograft transplantations, while 21 control patients were treated without LIPUS. The LIPUS treatment group formed calluses and had complete bridging between the host femur and the allograft faster after operation (16.9 and 29.4 wk after operation, respectively) compared with the control group (40.7 and 82.0 wk after operation, respectively). Our findings showed that LIPUS stimulated bone bonding between the host femur and the cortical onlay strut allografts.

[An alternative model of composite tissue transplantation in rat: the femur osteomyocutaneous flap]

OBJECTIVE

To reconstruct a simpler and reliable composite tissue transplantation model-the femur osteomyocutaneous flap for the replacement of hindlimb transplantation.

METHODS

Ten femur osteomyocutaneous flaps from 5 Lewis rats were transplanted into 10 syngeneic recipients' inguinal region. Their nutrient vessels were anastomosed with recipients vessels. The graft of this model was consisted of the groin flap and partial femur. To verify the feasibility of this model, gross and histological appearance were studied after transplantation to evaluate the viability of grafts.

RESULTS

The operative time was (159.0 +/- 8.3) min with the harvesting time of (68.0 +/- 4.8) min and the ischemia time of (55. 8 +/- 6.8) min. The methylene blue injection showed rich blood supply of transplanted femur osteomyocutaneous flap. All the 10 flaps survived completely with pink skin color and hair regrowth. The histologic examination of the flaps also revealed the normal appearance of the viable skin and bone marrow.

CONCLUSIONS

The femur osteomyocutaneous flap is a simple and reliable model for composite tissue transplantation, and its establishment will provide a new tool for the study of composite tissue allografts.

Matching osteochondritis dissecans lesions in identical twin brothers

Osteochondritis dissecans is a disorder of unknown etiology that can result in fragmentation of osteochondral surfaces, most commonly of the knee, shoulder, elbow, and ankle. This may lead to sequelae of pain and an inability to participate in desired activities. Multiple theories exist as to the true cause of the disorder, but none have been fully proven. One such proposed etiology is genetic causation. Familial cases of osteochondritis dissecans are rare, yet these cases offer support to growing evidence that may support a genetic link. This article describes osteochondritis dissecans lesions of the femoral trochlea in monozygotic (identical) twins. Both twins presented with similar symptoms 1 year apart. Neither twin had any clear inciting trauma. Magnetic resonance imaging revealed osteochondral lesions in similar positions of the lateral trochlear of the same knee in both brothers. Osteochondral autograft transfer and tibial tubercle anteromedialization were performed on both patients. An identical postoperative protocol was followed, and recovery with full return to sport was comparable for the brothers. To the authors' knowledge, only 1 other case report exists of osteochondritis dissecans lesions in monozygotic twins. Although debate continues regarding the true etiology of this disorder, cases of identical twins presenting with a similar disease process are highly suggestive of a genetic component and may lead to early identification and treatment of these lesions. Continued research in the area of osteochondritis dissecans and its genetic basis is needed to completely understand this disorder.

Surgical revascularization induces angiogenesis in orthotopic bone allograft

BACKGROUND

Remodeling of structural bone allografts relies on adequate revascularization, which can theoretically be induced by surgical revascularization. We developed a new orthotopic animal model to determine the technical feasibility of axial arteriovenous bundle implantation and resultant angiogenesis.

QUESTIONS/PURPOSES

We asked whether arteriovenous bundles implanted in segmental allografts would increase cortical blood flow and angiogenesis compared to nonrevascularized frozen bone allografts and contralateral femoral controls.

METHODS

We performed segmental femoral allotransplantation orthotopically from 10 Brown Norway rats to 20 Lewis rats. Ten rats each received either bone allograft reconstruction alone (Group I) or allograft combined with an intramedullary saphenous arteriovenous flap (Group II). At 16 weeks, we measured cortical blood flow with the hydrogen washout method. We then quantified angiogenesis using capillary density and micro-CT vessel volume measurements.

RESULTS

All arteriovenous bundles were patent. Group II had higher mean blood flow (0.12 mL/minute/100 g versus 0.05 mL/minute/100 g), mean capillary density (23.6% versus 2.8%), and micro-CT vessel volume (0.37 mm(3) versus 0.07 mm(3)) than Group I. Revascularized allografts had higher capillary density than untreated contralateral femora, while vessel volume did not differ and blood flow was lower.

CONCLUSIONS

Axial surgical revascularization in orthotopic allotransplants can achieve strong angiogenesis and increases cortical bone blood flow.

[Periacetabular pelvic reconstruction for chondrosarcoma with autograft of the proximal femur]

INTRODUCTION

Chondrosarcoma is a malignant tumor of chondroid matrix-producing cells; based on its frequency, it is the second most common malignant bone tumor (10-20%) and responds poorly to chemo- and radiotherapy. It is infrequent in the pelvis. It has a rapid growth potential. The indicated treatment is broad resection with tumor-free margins. Pelvic reconstruction after resection is controversial. The current management of musculoskeletal neoplasias has a two-fold purpose. First of all, controlling the neoplasia by means of surgeries with cancer-free margins and, second, performing procedures for the reconstruction of the involved segment achieving limb preservation with maximum functionality.

OBJECTIVE

Intrapelvic reconstruction with the proximal third of the ipsilateral femur in a patient with a chondrosarcoma in Enneking-Dunham's zone II. And placement of an unconventional femur prosthesis.

CLINICAL CASE

We present herein the case of a 58 year-old male, with a lytic lesion of the right acetabulum. The patient completed the diagnostic protocol, and the biopsy result was dedifferentiated chondrosarcoma.

CONCLUSION

The purpose of the surgical technique is to use the proximal third of the femur as a novel reconstruction alternative with massive autograft for tumor lesions located in Enneking-Dunham zone II.

Vascularized bone grafts for scaphoid nonunions

Scaphoid fractures that fail to unite are at risk of developing avascular necrosis and progressive structural collapse, thereby complicating attempts at revision surgical treatment. Vascularized bone grafts have demonstrated utility in promoting consolidation in the treatment of scaphoid nonunions complicated by avascular necrosis. Numerous pedicled and free vascularized grafts have been described with variable, but generally favorable, outcomes. Understanding the indications for different grafts is critical to the successful application of these techniques and grafts in the treatment of challenging scaphoid nonunions.

Primary tumor of the periacetabular region: resection and reconstruction using a segmental ipsilateral femur autograft

INTRODUCTION

Bone reconstruction, after periacetabular tumour removal, is a complex procedure that carries a high morbidity rate and can result in poor clinical outcomes. Among the available options, the Puget pelvic resection-reconstruction procedure uses an autograft from the ipsilateral proximal femur to restore the anatomical and mechanical continuity of the pelvic ring before inserting an acetabular implant. HYPOTHESIS AND GOALS: This reconstruction technique satisfactorily restores the pelvic anatomy such that functional results and morbidity are comparable to alternative reconstruction techniques.

PATIENTS AND METHODS

This was a retrospective study of 10 patients with an average age of 38.2 years (range 19 to 75) at the surgical procedure (performed between 1986 and 2007). There were five chondrosarcomas, three Ewing tumours, one plasmacytoma and one giant cell tumour. The position of the hip centre of rotation after reconstruction and autograft integration were evaluated on radiographs. Functional results were evaluated through the Musculoskeletal Tumor Society (MSTS) score and the Postel and Merle d'Aubigné (PMA) score.

RESULTS

At the time of review, one patient was lost to follow-up and four had died. On radiographs, the hip centre of rotation after reconstruction was higher by a median value of 15 mm (range 5 to 35) and more lateral by a median value of 6mm (range -5 to 15). Upon evaluation of radiographs at a median time of 40 months (range 6 to 252 months), the autograft was completely integrated in five patients and partially integrated in three patients (two patients had a local recurrence). There were no cases of autograft fracture or non-union at the junctions of the graft. The median MSTS score was 25 out of 30 (range 20 to 29), or 83% (range 67 to 97%) at the median clinical follow-up of 82 months (range 49 to 264). The median PMA score was 13 out of 18 (range 12 to 18). All living patients were walking without assistance. Five patients required nine surgical revisions. Seven were attributed directly or indirectly to local recurrence; one revision was performed because of instability and one because of early acetabular loosening at 9 months.

CONCLUSION

This challenging procedure provides satisfactory mechanical and anatomical results, while restoring hip anatomy and function. The primary cause of failure in this series was local recurrence of the tumour, which highlights the need to carefully select the indications and optimize the surgical tumour resection.

Induced membrane technique for reconstruction after bone tumor resection in children: a preliminary study

AIM

Segmental long-bone defect due to tumor resection remains a challenge to treat. The induced membrane technique is a new alternative for biological reconstruction. During the first stage, a cement spacer is inserted after bone resection and stabilisation. The cement spacer is removed during a second stage procedure performed after chemotherapy, and cortico-cancellous bone autograft was placed in the biological induced chamber. The aim of this study was to assess preliminary results in eight children.

PATIENTS AND METHODS

This prospective study included six girls and two boys, with a mean age of 12.1 years (range 9.5 to 18) and treated for a mean 15 cm defect (range 10 to 22 cms) due to resection of osteosarcoma (n=4), Ewing sarcoma (n=3) and low grade sarcoma. All patients except one, were given pre- and postoperative chemotherapy. Surgery was performed for three patients with a distal femur tumor, two patients with a proximal tibial tumor and three patients who had proximal humerus, shaft of humerus and fibular tumors. Fixation was mainly performed with locking compression plate (n=4) and locked nail (n=2). The mean operating times for first and second step procedures were 4.8 and 4h respectively. The healing process was radiologically assessed.

RESULTS

After a mean follow-up of 21.6 months (15 to 30), all patients were free of disease and seven had bony union. For the lower limb reconstructions, full weight bearing was possible after a mean of 116 days (range 90 to 150) following the second stage. Mean time to bone union was 4.8 months (1.5 to 10). The early Musculoskeletal Tumor Society (MSTS) score was 25.2/30 (range 20-30). Complications were: non-union (n=1), paradoxical graft resorption (n=1) requiring graft revision.

CONCLUSION

This two stage procedure reduces the operating time during the first stage and it also reduces early complications. Rapid bone union is objectively obtained despite major bone resection and the patients receiving chemotherapy.

SIGNIFICANCE

The induced membrane technique could be an excellent alternative for biological reconstruction after tumor resection in children.

Rabbit trochlear model of osteochondral allograft transplantation

Allografting and autografting of osteochondral tissues is a promising strategy to treat articular cartilage lesions in damaged joints. We developed a new model of fresh osteochondral allografting using the entire rabbit trochlea. The objective of the current study was to demonstrate that this model would achieve reproducible graft-host healing and maintain normal articular cartilage histologic, immunolocalization, and biochemical characteristics after transplantation under diverse storage and transplantation conditions. New Zealand white (n = 8) and Dutch belted (n = 8) rabbits underwent a 2-stage transplantation operation using osteochondral grafts that had been stored for 2 or 4 wk. Trochlear grafts harvested from the left knee were transplanted to the right knee as either autografts or allografts. Grafts were fixed with 22-gauge steel wire or 3-0 nylon suture. Rabbits were euthanized for evaluation at 1, 2, 4, 6, and 12 wk after transplantation. All grafts that remained in vivo for at least 4 wk demonstrated 100% interface healing by microCT. Trabecular bridging was present at the host-graft interface starting at 2 wk after transplantation, with no significant difference in cartilage histology between the various groups. The combined histology scores indicated minimal evidence of osteoarthritis. Immunostaining revealed that superficial zone protein was localized at the surface of all transplants. The rabbit trochlear model met our criteria for a successful model in regard to the ease of the procedure, low rate of surgical complications, relatively large articular cartilage surface area, and amount of host-graft bone interface available for analysis.

[Three-dimensional gait analysis of patients with osteonecrosis of femoral head before and after treatments with vascularized greater trochanter bone flap]

OBJECTIVE

To provide the objective basis for the evaluation of the operative results of vascularized greater trochanter bone flap in treating osteonecrosis of the femoral head (ONFH) by three-dimensional gait analysis.

METHODS

Between March 2006 and March 2007, 35 patients with ONFH were treated with vascularized greater trochanter bone flap, and gait analysis was made by using three-dimensional gait analysis system before operation and at 1, 2 years after operation. There were 23 males and 12 females, aged 21-52 years (mean, 35.2 years), including 8 cases of steroid-induced, 7 cases of traumatic, 6 cases of alcoholic, and 14 cases of idiopathic ONFH. The left side was involved in 15 cases, and right side in 20 cases. According to Association Research Circulation Osseous (ARCO) classification, all patients were diagnosed as having femoral-head necrosis at stage III. Preoperative Harris hip functional score (HHS) was 56.2 +/- 5.6. The disease duration was 1.5-18.6 years (mean, 5.2 years).

RESULTS

All incisions healed at stage I without early postoperative complications of deep vein thrombosis and infections of incision. Thirty-five patients were followed up 2-3 years with an average of 2.5 years. At 2 years after operation, the HHS score was 85.8 +/- 4.1, showing significant difference when compared with the preoperative score (t = 23.200, P = 0.000). Before operation, patients showed a hip muscles gait, short gait, reduce pain gait, and the pathological gaits significantly improved at 1 year after operation. At 1 year and 2 years after operation, step frequency, pace, step length and hip flexion, hip extension, knee flexion, ankle flexion were significantly improved (P < 0.01). Acceleration-time curves showed that negative wave and spinous wave at acceleration-stance phase of front feet and hind feet in affected limb were obviously reduced at 1 year and 2 years after operation. Postoperative petronas wave appeared at swing phase; the preoperative situation was three normal phase waves.

CONCLUSION

These results suggest that three-dimensional gait analysis before and after vascularized greater trochanter for ONFH can evaluate precisely hip vitodynamics variation.

Teriparatide therapy enhances devitalized femoral allograft osseointegration and biomechanics in a murine model

Despite the remarkable healing potential of long bone fractures, traumatic injuries that result in critical defects require challenging reconstructive limb sparing surgery. While devitalized allografts are the gold standard for these procedures, they are prone to failure due to their limited osseointegration with the host. Thus, the quest for adjuvants to enhance allograft healing remains a priority for this unmet clinical need. To address this, we investigated the effects of daily systemic injections of 40 μg/kg teriparatide (recombinant human parathyroid hormone) on the healing of devitalized allografts used to reconstruct critical femoral defects (4mm) in C57Bl/6 mice. The femurs were evaluated at 4 and 6 weeks using micro CT, histology, and torsion testing. Our findings demonstrated that teriparatide induced prolonged cartilage formation at the graft-host junction at 4 weeks, which led to enhanced trabeculated bone callus formation and remarkable graft-host integration at 6-weeks. Moreover, we observed a significant 2-fold increase in normalized callus volume (1.04 ± 0.3 vs. 0.54 ± 0.14 mm³/mm; p < 0.005), and Union Ratio (0.28 ± 0.07 vs. 0.13 ± 0.09; p < 0.005), compared to saline treated controls at 6-weeks. Teriparatide treatment significantly increased the torsional rigidity (1175 ± 311 versus 585 ± 408 N.mm²) and yield torque (10.5 ± 4.2 versus 6.8 ± 5.5 N.mm) compared to controls. Interestingly, the Union Ratio correlated significantly with the yield torque and torsional rigidity (R²=0.59 and R²=0.77, p < 0.001, respectively). These results illustrate the remarkable potential of teriparatide as an adjuvant therapy for allograft repair in a mouse model of massive femoral defect reconstruction, and warrant further investigation in a larger animal model at longer time intervals to justify future clinical trials for PTH therapy in limb sparing reconstructive procedures.

Outcomes analysis of anterior-posterior fusion for low grade isthmic spondylolisthesis

BACKGROUND

Traditional surgical treatment of isthmic spondylolisthesis is posterior-lateral fusion, but the addition of anterior surgery has been explored. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis.

METHODS

Retrospectively, we enrolled 23 consecutive patients (mean age of 50) who underwent surgical treatment for low grade isthmic spondylolisthesis. The mean follow-up was 10 months. Basic demographic and radiographic data was collected. Pre- and post-surgical clinical surveys (VAS, ODI, and SF-36) were collected.

RESULTS

All 23 patients underwent anterior interbody fusion with a femoral ring allograft or ICBG in combination with posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (p = 0.24) while slip angle increased from 9.8° to 17.9° (p < 0.001) and average disc height decreased from 1.9 cm to 0.80 cm (p < 0.001). VAS scores decreased from 7.1 to 2.4 (p < 0.001), ODI scores decreased from 52.5 to 28.1 (p < 0.001), and SF-36 scores increased in the Physical Component Scale (PCS) from 29.5 to 42.6 (p < 0.001).

CONCLUSION

In our study, patients demonstrated an improvement in the ODI as well the physical component scores of the SF-36, thus having a good clinical outcome.

Biomechanical comparison of translaminar screw versus pedicle screw supplementation of anterior femoral ring allografts in one-level lumbar spine fusion

Pedicle screws (PS) can provide initial stabilization of anterior interbody femoral ring allograft (FRA) lumbar constructs. Translaminar screws (TLS) have also been advocated for this procedure. The objective of this study was to use an in vitro human cadaveric model to compare the stability of one-level anterior interbody lumbar constructs stabilized with PS and those stabilized with TLS. Five human cadaveric spinal motion segments (L4-S2) were biomechanically evaluated in the intact condition and using the follow- ing methods of stabilization: anterior interbody fusion with FRA, anterior FRA supplemented with PS, and anterior FRA supplemented with TLS. Stability was determined for each construct by measuring construct displacement as a function of applied load under the following conditions: compression, flexion, extension, lateral bending to each side, and axial torsion. There were no statistically significant differences in construct stability between FRA supplemented with PS and FRA supplemented with TLS under any of the loading conditions. In selected cases, supplementation of anterior femoral ring allograft with translaminar screws is a viable alternative to supplementation with pedicle screws.

Three-dimensional morphometric analysis of the distal femur: a validity method for allograft selection using a virtual bone bank

Tumor excision is the primary treatment of aggressive or recurrent benign bone tumors and malignant bone sarcomas. This requires a surgical resection with the potential for large residual osseous defects that could be reconstructed using fresh frozen allografts. Virtual bone banks enable the creation of databases allowing a 3D pre-surgery evaluation of such allgorafts, based on segmentation of DICOM-CT images. This study demonstrates the usefulness of patient specific 3D models for an accurate host-donor allograft match. We describe one way to select the best match according to size and shape. The results suggest that a robust and reliable technique has been established. Since it is difficult to plan an allograft on a distal femur deformed by the tumor, we propose to plan the surgery on the contralateral side. Our results support this limb symmetry hypothesis. The use of this measurement protocol enables accurate selection of allografts from a contralateral healthy femur 3D CT model achieving the best match possible considering the geometry of available allograft candidate femur specimens.

[Experimental steroid osteoporosis in rats and the way to restore the bone tissue structure]

Experimental prednisolone administration has been shown to cause osteoporosis in animals. A single administration of fetal tissue--10-day fetal homogeneous tissue at a dose of 0.5 mg into the experimental animal femur improves the bone tissue structure, hastens its remodeling, contributes to elimination of the bone tissue pathologic process in osteoporosis.

Treatment of non-union of forearm bones with a free vascularised corticoperiosteal flap from the medial femoral condyle

We report 6 cases of recalcitrant non-union of forearm bones treated with a free vascularized thin corticoperiosteal graft harvested from the medial condyle of the femur. All non-unions healed. In one 58-year-old patient a fracture of the femur occurred.

[Induction of axial vascularization in processed bovine cancellous bone scaffold using arteriovenous loop]

OBJECTIVE

To explore the method of inducing axial vascularization in a processed bovine cancellous bone scaffold by using an arteriovenous loop, and to evaluate its effect of vascularization.

METHODS

Custom-made processed bovine cancellous bone discs were processed into cylinder with circular grooves. Thirty male SD rats weighing 300-350 g (3-4 months old) were randomly divided into 2 groups (n = 15 per group): experimental group in which the femoral veins in the groin of rats were separated and transplanted to the contralateral femoral artery and vein stump, the processed bovine cancellous bone scaffold was inserted into the arteriovenous loop, which was placed into the annular groove. Control group, in which the blood vessels in the groin of rats were cut, no anastomosis was conducted, and the processed bovine cancellous bone scaffold was planted. At 2, 4 and 8 weeks after operation, gross observation, ink infusion histology observation and microvessel bulk density detection were conducted.

RESULTS

At each postoperative time point, the samples in the experimental group were fresh red, the circulation of blood vessels were smooth bidirectionally, while the samples in the control group were dark red soft, and flexible. Ink infusion histology observation showed the processed bovine cancellous bone scaffold in the experimental group had obvious vascularization, the blood vessels tended to be mature and integrated into network, and neovascular sprouts originated from arteriovenous loop were evident, especially at 8 weeks after operation; while there was no vascularization in the control group. At 2, 4 and 8 weeks after operation, the bulk density of the microvessels in the experimental group was (3.59 +/- 1.84), (16.61 +/- 10.23) and (39.04 +/- 13.46) microm3/microm3, respectively, and it was (2.43 +/- 0.97), (6.79 +/- 2.92) and (25.31 +/- 10.98) microm3/microm3, respectively, in the control group. Significant differences was noted between two groups at 4 and 8 weeks after operation (P < 0.05), and no significant difference was evident at 2 weeks after operation (P > 0.05).

CONCLUSION

Inducing vascularization in a processed bovine cancellous bone using an arteriovenous loop is a new strategy of revascularization and may provide valuable clues for the preparation of functional artificial bone.

Bone graft harvest using a new intramedullary system

Obtaining autogenous bone graft from the iliac crest can entail substantial morbidity. Alternatively, bone graft can be harvested from long bones using an intramedullary (IM) harvesting system. We measured bone graft volume obtained from the IM canals of the femur and tibia and documented the complications of the harvesting technique. Donor site pain and the union rate were compared between the IM and the traditional iliac crest bone graft (ICBG) harvest. Forty-one patients (23 male, 18 female) with an average age of 44.9 years (range, 15-78 years) had graft harvested from long bones using an IM harvest system (femoral donor site, 37 patients; tibial donor site, four patients). Forty patients (23 male, 17 female; average age, 46.4 years; range, 15-77 years) underwent anterior ICBG harvest. We administered patient surveys to both groups to determine pain intensity and frequency. IM group reported lower pain scores than the ICBG group during all postoperative periods. Mean graft volume for the IM harvest group was 40.3 mL (range, 25-75 mL) (graft volume was not obtained for the ICBG group). Using an intramedullary system to harvest autogenous bone graft from the long bones is safe provided a meticulous technique is used.

LEVEL OF EVIDENCE

Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

[Voluminous bone graft harvesting of the femoral marrow cavity for autologous transplantation. An indication for the"Reamer-Irrigator-Aspirator-" (RIA-)technique]

Due to their excellent osteoinductive, osteogenetic, and osteoconductive properties, autologous bone grafts possess biomechanical advantages over synthetic bone substitutes. Furthermore, unlike cadaveric allografts and xenografts, they carry no risk of immunogenic response or transmission of infectious diseases. However, the limited availability of autologous bone grafts requires the use of the above-mentioned bone substitutes for management of large bone defects. The"Reamer-Irrigator-Aspirator-" (RIA-)technique may present an alternative method for harvesting a larger volume of autologous bone graft as compared with conventional harvesting procedures. We report on intramedullary reaming by the RIA technique to obtain autologous bone graft for a nonunion of the proximal femur. The contralateral femur was reamed and the bone graft was applied to the nonunion. The patient showed clinical and radiological healing of the nonunion without donor site complications.

Distinct roles for intrinsic osteocyte abnormalities and systemic factors in regulation of FGF23 and bone mineralization in Hyp mice

X-linked hypophosphatemia (XLH) is characterized by hypophosphatemia and impaired mineralization caused by mutations of the PHEX endopeptidase (phosphate-regulating gene with homologies to endopeptidases on the X chromosome), which leads to the overproduction of the phosphaturic fibroblast growth factor 23 (FGF23) in osteocytes. The mechanism whereby PHEX mutations increase FGF23 expression and impair mineralization is uncertain. Either an intrinsic osteocyte abnormality or unidentified PHEX substrates could stimulate FGF23 in XLH. Similarly, impaired mineralization in XLH could result solely from hypophosphatemia or from a concomitant PHEX-dependent intrinsic osteocyte abnormality. To distinguish between these possibilities, we assessed FGF23 expression and mineralization after reciprocal bone cross-transplantations between wild-type (WT) mice and the Hyp mouse model of XLH. We found that increased FGF23 expression in Hyp bone results from a local effect of PHEX deficiency, since FGF23 was increased in Hyp osteocytes before and after explantation into WT mice but was not increased in WT osteocytes after explantation into Hyp mice. WT bone explanted into Hyp mice developed rickets and osteomalacia, but Hyp bone explanted into WT mice displayed persistent osteomalacia and abnormalities in the primary spongiosa, indicating that both phosphate and PHEX independently regulate extracellular matrix mineralization. Unexpectedly, we observed a paradoxical suppression of FGF23 in juvenile Hyp bone explanted into adult Hyp mice, indicating the presence of an age-dependent systemic inhibitor of FGF23. Thus PHEX functions in bone to coordinate bone mineralization and systemic phosphate homeostasis by directly regulating the mineralization process and producing FGF23. In addition, systemic counterregulatory factors that attenuate the upregulation of FGF23 expression in Hyp mouse osteocytes are present in older mice.

Free medial femoral condyle bone grafting for scaphoid nonunions with humpback deformity and proximal pole avascular necrosis

Treatment of scaphoid nonunions remains a challenging problem, especially in the setting of proximal pole avascular necrosis or humpback deformity. Conventional bone grafting techniques have demonstrated unpredictable results in the setting of collapse deformities, whereas pedicled dorsal distal radius vascularized bone grafts have recently been reported to have nearly a 50% failure rate when used in scaphoid nonunions with proximal pole nonunion. Free vascularized medial femoral condyle bone grafting is one option for the treatment of scaphoid nonunions with proximal pole avascular necrosis associated with a humpback deformity. The indications, contraindications, and technique of free vascularized medial femoral condyle bone grafting are presented for the treatment of scaphoid nonunions associated with proximal pole avascular necrosis and humpback deformities.

Unicondylar osteoarticular allografts of the knee

BACKGROUND

In the management of a resected distal femoral or proximal tibial condyle as the result of tumor or trauma, a unicondylar osteoarticular allograft is currently the only reconstructive option that avoids the sacrifice of the unaffected condyle. The purposes of this study were to perform a survival analysis of unicondylar osteoarticular allografts of the knee and to evaluate the complications.

METHODS

We retrospectively reviewed the results of forty large unicondylar osteoarticular allograft procedures in thirty-eight patients who were followed for a mean of eleven years. Twenty-nine allografts were femoral transplants and included eleven medial and eighteen lateral femoral condyles. Eleven allografts were tibial transplants, including four medial and seven lateral tibial condyles. The procedure was performed after a tumor resection in thirty-six patients and to replace condylar loss after a severe open fracture in the remaining two patients. Complications were analyzed, and allograft survival from the date of implantation to the date of revision or the time of the latest follow-up was determined. Functional and radiographic results were documented according to the Musculoskeletal Tumor Society scoring system at the time of the latest follow-up.

RESULTS

One patient died of tumor-related causes without allograft failure before the two-year follow-up evaluation. The global rate of allograft survival at both five and ten years was 85%, with a mean follow-up of 148 months. In six patients, the allografts were removed at an average of twenty-six months (range, six to forty-eight months) and these were considered failures. All six patients underwent a second allograft procedure including two new unicondylar and four bicondylar reconstructions. The mean radiographic score for the thirty-three surviving allografts evaluated was 89%, with an average functional score of 27 of a possible 30 points.

CONCLUSIONS

Unicondylar osteoarticular allografts of the knee appear to be a reliable alternative for patients in whom reconstruction of massive osteoarticular bone loss is limited to one condyle of the femur or the tibia.

Osteochondral transplantation to treat osteochondral lesions in the elbow

BACKGROUND

Effective treatment of osteochondral lesions in the elbow remains challenging. Arthroscopic débridement and microfracture or retrograde drilling techniques are often insufficient and provide only temporary symptomatic relief. The purpose of this study was to evaluate the treatment of these lesions with osteochondral autografts.

METHODS

From 1999 to 2002, seven patients with osteochondral lesions of the capitellum humeri (five patients), trochlea (one patient), or radial head (one patient) were treated with cylindrical osteochondral grafts, which were harvested from the non-weight-bearing area of the proximal aspect of the lateral femoral condyle. The patients (three female and four male patients with an average age of seventeen years) were evaluated preoperatively and postoperatively, with an average follow-up of fifty-nine months. The Broberg and Morrey score was chosen for functional evaluation of the elbow (with regard to motion, pain, strength, activities of daily living, and stability), and the American Shoulder and Elbow Surgeons score was used for the analysis of pain. All patients had imaging studies done preoperatively to evaluate the defect and postoperatively to assess the ingrowth and viability of the graft. The ipsilateral knee was examined for donor-site morbidity.

RESULTS

The Broberg and Morrey score improved from a mean (and standard deviation) of 76.3 +/- 13.2 preoperatively to 97.6 +/- 2.7 postoperatively, and pain scores were significantly reduced (p < 0.05). The mean elbow extension lag of 4.7 degrees +/- 5.8 degrees was reduced to 0 degrees postoperatively. Compared with the contralateral side, there was a mean preoperative flexion lag of 12.9 degrees +/- 13.8 degrees . At the time of the final follow-up, flexion was free and was equal bilaterally in all patients. None of the plain radiographs made at the time of follow-up showed any degenerative changes or signs of osteoarthritis. The postoperative magnetic resonance imaging scans showed graft viability and a congruent chondral surface in all seven patients. No donor-site morbidity was noted at one year postoperatively.

CONCLUSIONS

The osteochondral autograft procedure described in the present study provides the opportunity to retain viable hyaline cartilage for the repair of osteochondral lesions in the elbow while restoring joint congruity and function and perhaps reducing the risk of osteoarthritis. These medium-term results suggest that the risks of a two-joint procedure are modest and justifiable. In addition, the described technique provides an option for revision surgery after the failure of other surgical procedures.