Long-term survival of a free split-thickness skin graft on a large seroma

A free skin graft about 12 cm in diameter transplanted after excision of a Bowen's carcinoma on the back totally survived for a long period on seroma and was confirmed to have revascularization from the host skin margin. Repeated evacuations of the fluid and subsequent pressure dressings failed to cause adherence of the graft to the bed, even on the thirty-ninth postoperative day. Histologic examination of the graft and the bed revealed partial epithelialization on the face-to-face surfaces, to which no adherence was attributed. The incomprehensible phenomenon in this unusual clinical case evokes a new interest in the mechanism of free skin graft survival, particularly in the phase of serum imbibition.     

Hook nail deformity repaired using a composite toe graft.

The hook nail deformity is caused by loss of fingertip bone and soft tissue. Healing can result in a volarly displaced distal nailbed and a tight tip with inadequate padding and a poor cosmetic appearance. A composite graft from the second toe placed beneath the released nailbed gives good support and improved pulp substance. The technique of the composite toe graft has been performed in nine patients. All grafts were 100 percent viable, but one patient required a second graft for additional tip bulk. There has been no donor-site morbidity in the follow-up of 1 month to 2 years.     

Osteochondral graft fixation using a bioresorbable bone cement

Multiple osteochondral grafts can be used to resurface large joint defects in both humans and horses. In humans, immediate postoperative weight bearing can be prevented, however in the equine, it is unavoidable. Early weight bearing can create detrimental graft micromotion. The aim of this study was to investigate the role of a bioresorbable cement in improving the initial stability of multiple osteochondral graft repairs of large subchondral cystic lesions in the horse. Configurations employed for filling a 20mm diameter cylindrical defect included: (A) twelve 4.5mm diameter grafts with cement, (B) five 6.5mm diameter grafts with cement, (C) four each of 4.5mm and 6.5mm grafts with cement and (D) cement only. Intact bone slices (E) were also tested. Push-out tests were used to quantify construct to host sidewall interface fixation. Configuration (A) proved clinically impractical (n=3). Configurations (B) (n=6), and (C) (n=4) had statistically similar interface stiffnesses and failure stresses (43+/-8 and 30+/-12 MPa and 0.96+/-0.1 and 1.2+/-0.3 Mpa, respectively) suggesting that they are equally susceptible to interface movement in the immediate postoperative period. By way of comparison, defects filled only with cement had an average stiffness of 53+/-7MPa and failure stress of 1.8+/-0.3 MPa (n=6) while the intact femoral condyle demonstrated a stiffness of 108+/-7 MPa and failure stress of 18+/-0.4 MPa (n=6). Cement augmentation improved immediate postoperative stability of multiple osteochondral graft constructs over uncemented constructs, although in all cases the observed moduli of elasticity and yield stress values were lower than those observed for cement only and intact bone test specimens. (all numbers are mean+/-SEM).     

Porous hydroxyapatite as a bone graft substitute in cranial reconstruction: a histometric study

To assess the potential of a porous hydroxyapatite matrix to serve as a bone graft substitute, bilateral 15 X 20 mm craniectomy defects were reconstructed in 17 dogs with blocks of implant and split-rib autografts. Specimens were retrieved at 3, 6, 12, 24, and 48 months, and undecalcified sections were prepared for microscopy and histometry. The implant and graft cross-sectional areas did not change with time, documenting their equivalent ability to maintain cranial contour. Bone ingrowth extended across the implant from one cranial shelf to the other in 15 specimens. Little apparent bone ingrowth was seen in most graft specimens. Two implants and three grafts were nonunited, possibly due to lack of fixation or the orientation of the histology sections. The implant specimens were composed of 39.3 percent hydroxyapatite matrix, 17.2 percent bone ingrowth, and 43.5 percent soft-tissue ingrowth. The graft specimens were composed of 43.7 percent bone and 56.3 percent soft tissue. This study supported the thesis that a porous hydroxyapatite matrix may function in part as a bone graft substitute. The brittle hydroxyapatite matrix undoubtedly became stronger with bone ingrowth, but the degree of cranial protection achieved was not measured in this study. The size of the cranial defect used in this study did not permit estimation of the distance over which bone ingrowth may be reliably expected. There remains a need for greater understanding of the causes of nonunion, the extent of predictable ingrowth depth, and the strength of the resultant implant-bone composite.     

Predicting the structural integrity of bone defects repaired using bone graft materials

Bone defects create stress concentrations which can cause fracture under impact or cyclic loading. Defects are often repaired by filling them with a bone graft material; this will reduce the stress concentration, but not completely, because these materials have lower stiffness than bone. The fracture risk decreases over time as the graft material is replaced by living bone. Many new bone graft materials are being developed, using tissue engineering and other techniques, but currently there is no rational way to compare these materials and predict their effectiveness in repairing a given defect. This paper describes, for the first time, a theoretical model which can be used to predict failure by brittle fracture or fatigue, initiating at the defect. Preliminary results are presented, concentrating on the prediction of stress fracture during the crucial post-operative period. It is shown that the likelihood of fracture is strongly influenced by the shape of the defect as well as its size, and also by the level of post-operative exercise. The most important finding is that bone graft materials can be successful in preventing fracture even when their mechanical properties are greatly inferior to those of bone. Future uses of this technique include pre-clinical assessment of bone replacement materials and pre-operative planning in orthopaedic surgery.     

Predicting the structural integrity of bone defects repaired using bone graft materials

Bone defects create stress concentrations which can cause fracture under impact or cyclic loading. Defects are often repaired by filling them with a bone graft material; this will reduce the stress concentration, but not completely, because these materials have lower stiffness than bone. The fracture risk decreases over time as the graft material is replaced by living bone. Many new bone graft materials are being developed, using tissue engineering and other techniques, but currently there is no rational way to compare these materials and predict their effectiveness in repairing a given defect. This paper describes, for the first time, a theoretical model which can be used to predict failure by brittle fracture or fatigue, initiating at the defect. Preliminary results are presented, concentrating on the prediction of stress fracture during the crucial post-operative period. It is shown that the likelihood of fracture is strongly influenced by the shape of the defect as well as its size, and also by the level of post-operative exercise. The most important finding is that bone graft materials can be successful in preventing fracture even when their mechanical properties are greatly inferior to those of bone. Future uses of this technique include pre-clinical assessment of bone replacement materials and pre-operative planning in orthopaedic surgery.     

Reconstruction of orbital floor fracture using solvent-preserved bone graft

The orbital floor is one of the most frequently damaged parts of the maxillofacial skeleton during facial trauma. Unfavorable aesthetic and functional outcomes are frequent when it is treated inadequately. The treatment consists of spanning the floor defect with a material that can provide structural support and restore the orbital volume. This material should also be biocompatible with the surrounding tissues and easily reshaped to fit the orbital floor. Although various autografts or synthetic materials have been used, there is still no consensus on the ideal reconstruction method of orbital floor defects. This study evaluated the applicability of solvent-preserved cadaveric cranial bone graft and its preliminary results in the reconstruction of the orbital floor fractures. Twenty-five orbital floor fractures of 21 patients who underwent surgical repair with cadaveric bone graft during a 2-year period were included in this study. Pure blowout fractures were determined in nine patients, whereas 12 patients had other accompanying maxillofacial fractures. Of the 21 patients, 14 had clinically evident diplopia (66.7 percent), 12 of them had enophthalmos (57.1 percent), and two of them had gaze restriction preoperatively. Reconstruction of the floor of the orbit was performed following either the subciliary or the transconjunctival approach. A cranial allograft was placed over the defect after sufficient exposure. The mean follow-up period was 9 months. Postoperative diplopia, enophthalmos, eye motility, cosmetic appearance, and complications were documented. None of the patients had any evidence of diplopia, limited eye movement, inflammatory reactions in soft tissues, infection, or graft extrusion in the postoperative period. Providing sufficient orbital volume, no graft resorption was detected in computed tomography scan controls. None of the implants required removal for any reason. Enophthalmos was seen in one patient, and temporary scleral show lasting up to 3 to 6 weeks was detected in another three patients. Satisfactory cosmetic results were obtained in all patients. This study showed that solvent-preserved bone, which is a nonsynthetic, human-originated, processed bioimplant, can be safely used in orbital floor repair and can be considered as another reliable treatment alternative.     

A simple technique for reconstruction of the umbilicus, using a conchal cartilage composite graft

A simple technique to reconstruct the umbilicus is reported in which a conchal cartilage composite graft, such as that used in tragus construction in the treatment of microtia, was employed with a very satisfactory result.     

Reconstruction of radial bone defect using gelatin sponge and a BMP-2 combination graft

Many bioactive molecules like recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed for mineralized bone grafts, for which proper scaffolds are necessary to successfully apply the bioactive molecules. In this study, we tested the osteogenic efficacy of rhBMP-2 produced in-house in combination with gelatin sponge as the scaffold carrier in a rabbit radial defect model. The efficacy of the rhBMP-2 was determined by alkaline phosphatase activity assay of C2C12 cells. Two groups of ten rabbits each were treated with rhBMP-2/gelatin sponge, or gelatin sponge only. At 4 weeks, rhBMP-2/gelatin sponge grafts showed more bone regeneration than gelatin sponge grafts, as determined by X-ray radiography, micro-computed tomography, and histological analyses. At 8 weeks, rhBMP-2/gelatin sponge grafts exerted much stronger osteogenic effects. The study demonstrates the improved osteogenic efficacy of the rhBMP-2/gelatin sponge grafts in a rabbit radial bone defect model acting as a bone-inductive material. [BMB Reports 2013; 46(6): 328-333]