Vancouver Experience of Recombinant Human Platelet-Derived Growth Factor.

Joint arthrodesis utilizing autogenous bone graft remains the gold standard of treatment in fusion procedures of the foot and ankle. Graft harvest, however, has been associated with increased morbidity to patients as well as increased costs. With this in mind, multiple clinical studies have evaluated the efficacy of recombinant human platelet-derived growth factor (rh-PDGF-BB) with beta-tricalcium phosphate (B-TCP) to augment in foot and ankle arthrodesis with favorable results. These factors have led to the increased use of rh-PDGF-BB with B-TCP in Vancouver with good clinical results.

Increased Cost of Negative Pressure Dressings Is Not Justified for Split-Thickness Skin Grafting of Low-Risk Wounds.

OBJECTIVES: (1) To determine whether negative pressure dressings (NPDs) are superior to conventional compressive dressings (CDs) for split-thickness skin grafts (STSGs) placed on healthy, low-risk wounds, (2) To determine the cost difference of NPDs versus that of CDs. DESIGN: Retrospective. SETTING: Level I Trauma Center. PATIENTS/PARTICIPANTS: One hundred ninety-five traumatic wounds treated with STSG. MAIN OUTCOME MEASUREMENTS: Patients were assigned outcomes based on postoperative documentation: completely healed, incompletely healed (small areas of graft necrosis), failed, or lost to follow-up. The costs associated with each dressing type were documented. RESULTS: Thirty five of 195 STSGs were lost to follow-up, leaving n = 120 STSG-NPD, n = 40 STSG-CD. Of the remaining 120 STSGs treated with NPD, 91 completely healed, 23 incompletely healed, and 6 failed. Of the 40 STSGs treated with a CD, 37 completely healed, 1 incompletely healed, and 2 failed. Patients treated with CDs had a higher likelihood of healing relative to those treated with the NPD (P = 0.018). Analyzing the outcomes as failed versus "not failed" revealed no significant difference between the groups (P = 1.00). There were more smokers in the CD group (P = 0.022). In this series, the mean cost associated with NPD compared with that of CD was $2370 more per patient. CONCLUSIONS: There is a high rate of successful healing of STSGs for traumatic extremity wounds regardless of the dressing used. The increased cost of NPDs is not justified in wounds that are at a low risk of developing STSG failure. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Complications of high-energy bicondylar tibial plateau fractures treated with dual plating through 2 incisions.

OBJECTIVES: To characterize the rate of complications after operative fixation of bicondylar (OTA/AO 41-C) tibial plateau fractures and to evaluate the contribution of common risk factors. DESIGN: Retrospective review. SETTING: Level 1 regional trauma center. PATIENTS/PARTICIPANTS: One hundred thirty-eight patients older than 18 years with 140 bicondylar tibial plateau fractures were participated in this study. INTERVENTION: Open reduction and internal fixation using medial and lateral plate construct through 2 incisions. MAIN OUTCOME MEASUREMENTS: Development of a deep infection or a nonunion. RESULTS: The overall major complication rate was 27.9%: 23.6% deep infection and 10.0% nonunion. Open fractures were associated with a higher rate of infection: 43.8% versus 21.0% for closed injuries (odds ratio = 2.96, P = 0.05). Fasciotomy closure before definitive fixation was associated with significantly fewer deep infections compared with internal fixation with open fasciotomy wounds: 11.8% versus 50.0% (odds ratio = 7.5, P = 0.05). The presence of compartment syndrome, tobacco use, diabetes, and timing of surgery had no statistically significant association on the rate of infection or nonunion. CONCLUSIONS: Nonunion and deep infections occur commonly after staged open reduction and internal fixation of high-energy tibial plateau fractures. Open fractures and open fasciotomy wounds at the time of internal fixation are associated with higher rates of infection. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Genomewide molecular and biologic characterization of biomembrane formation adjacent to a methacrylate spacer in the rat femoral segmental defect model.

OBJECTIVES: This study focuses upon the morphologic and molecular features of the layer of cells, termed the "biomembrane," which forms around methacrylate spacers in bone segmental defects. The objective of this research was to assess the biomembrane formed in a novel rodent femoral segmental defect model at 4, 8, and 16 weeks with histologic and molecular studies. METHODS: Following Institutional Animal Care and Use Committee approval, a segmental defect was created in the rat femur and stabilized with the AO LockingRatNail and analyzed at 4, 8, and 16 weeks postsurgery using digital radiologic imaging, morphological and immunohistochemical studies, and genomewide gene expression studies employing microarray analysis. RESULTS: The biomembrane formed around the methacrylate spacer was rich in vasculature, which showed vascular endothelial growth factor immunolocalization. The biomembrane supported development of foci of bone and cartilage within it. Bone morphogenetic protein 2 immunolocalization and gene expression were positive within developing osseous and chondrocyte foci. Microarray analysis showed significant expression of key genes related to bone and cartilage formation and angiogenesis. CONCLUSIONS: This rat bone model was effective in creation of the biomembrane. Bone and cartilage foci were formed within the vascularized biomembrane with associated expression of genes critical for bone and cartilage development/formation and vascularization. The polymethyl methacrylate-induced biomembrane offers an exciting potential solution for segmental defects; the biomembrane, may act as a receptive bed and also serve as a source for mesenchymal stem cells, which could be recruited/directed for the healing process.

Utilization of the AO LockingRatNail in a novel rat femur critical defect model.

BACKGROUND: Our objective was to utilize a commercially available rodent locked intramedullary nail in a rat femur diaphyseal defect. This model is needed for future studies where materials in the critical defect could be modified with agents to fight infection (antibiotics) or promote osteogenesis. METHODS: After unsatisfactory attempts to develop a reliable femur critical size defect model utilizing various forms of fixation, a locked intramedullary nailing system (AO LockingRatNail) was employed in 105 male Sprague Dawley rats. A 5 mm critical size mid-diaphyseal femoral defect was created using a pneumatic sagittal saw. The intramedullary nail was placed in the femur in a retrograde manner. A prefabricated polymethyl-methacrylate (PMMA) spacer was utilized to fill the defect. Once adequate alignment was achieved, two locking pegs were placed (one distal, one proximal) to provide stable fixation. RESULTS: The technique was successful in 90% of femurs (95 of 105). The majority of complications centered on failure of the placement of locking pegs (7 of 10). One rat presented with migration of the nail out of the knee. Two rats presented with fractures not recognized intraoperatively. These complications occurred early in the study and decreased as surgical experience increased. Surgery was tolerated well by the rats as reflected by significant weight postoperative gain (p < .001). CONCLUSIONS: The AO LockingRatNail is a novel, reproducible, and successful method for stabilization of critical size femoral diaphyseal defects in the rat. This model has future value in the examination of the biological processes involved in the healing of critical bone defects.

Effect of graft height mismatch on contact pressures with osteochondral grafting of the talus.

BACKGROUND: Osteochondral allograft transplantation is technically demanding. It is not always possible to place the surface of the graft perfectly flush with the surrounding cartilage. One must often choose between placing at least some portion of the surface of the graft slightly elevated or recessed. The effect of this choice on joint contact pressure is unknown. PURPOSE: This study was undertaken to determine the effect of graft height mismatch on joint contact pressure in the ankle. STUDY DESIGN: Controlled laboratory study. METHODS: Ten human cadaveric ankles underwent osteochondral grafting by removal then replacement of an osteochondral plug. Six conditions were tested: intact, graft flush, graft elevated 1.0 mm, graft elevated 0.5 mm, graft recessed 0.5 mm, and graft recessed 1.0 mm. Joint contact pressures were measured with a Tekscan sensor while loads of 200 N, 400 N, 600 N, and 800 N were sequentially applied. RESULTS: The peak contact pressure at the graft site for the flush condition was not significantly different from the intact condition for either medial or lateral lesions. In contrast, peak pressure on the opposite facet of the talar dome was significantly increased during the flush condition for the medial but not the lateral grafts. Elevated grafts experienced significantly increased contact pressures, whereas recessed grafts experienced significantly decreased pressures. These changes were greater for lateral than for medial lesions. Reciprocal changes in joint contact pressures were found on the opposite facet of the talus with elevated grafts on the lateral side and recessed grafts on the medial side. CONCLUSION: Flush graft placement can restore near-normal joint contact pressure. Elevated graft placement leads to significant increases in joint contact pressure at the graft site. Recessed graft placement leads to a transfer of pressure from the graft site to the opposite facet of the talus. CLINICAL RELEVANCE: Osteochondral grafts in the talus should be placed flush if possible or else slightly recessed.

Biomechanical comparison of hallux valgus correction using the proximal chevron osteotomy fixed with a medial locking plate and the Ludloff osteotomy fixed with two screws.

BACKGROUND: For moderate-to-severe hallux valgus deformities with a 1-2 intermetatarsal angle in excess of 15 degrees , a proximal first metatarsal osteotomy is indicated. The ideal osteotomy has yet to be defined, but should inherently limit the incidence of dorsal malunion and allow for early ambulation. The present study evaluates the mechanical integrity of two popular first metatarsal osteotomies. METHODS: Ten matched pairs of fresh-frozen cadaveric first metatarsals were harvested. In one metatarsal from each pair, a Ludloff osteotomy was created and fixed with two cannulated 3.5mm screws. In the contralateral first metatarsal, a proximal chevron osteotomy was performed and subsequently fixed with a medially applied locking plate. All specimens were mounted within an Instron 1321 servohydraulic materials testing machine and subjected to a plantar-to-dorsal cantilever bending protocol for 1000 cycles. FINDINGS: Two of ten Ludloff osteotomies failed prior to completion of 1000 loading cycles by fracture at the distal screw site, whereas six of ten proximal chevrons failed prior to the 1000th cycle. The mode of failure in this group was by cut-out of the plantar-proximal screw. The bending stiffness of the Ludloff osteotomy exceeded that of the proximal chevron at all measurement points between the 1st and 200th load cycles (P<0.05). After 200 cycles, an inadequate number of plate constructs survived to allow statistical comparison. INTERPRETATION: The results of the present study indicate that the proximal chevron osteotomy fixed with a medially based locking plate exhibits mechanical properties inferior to those of the Ludloff osteotomy under the tested conditions.

Revision tibiotalar arthrodesis.

BACKGROUND: Contemporary recommendations for primary and revision ankle arthrodesis favor internal compression techniques involving the use of screw and/or plate fixation. While tibiotalocalcaneal arthrodesis with internal fixation may be a suitable method of salvage for the treatment of a failed tibiotalar arthrodesis in selected patients, ring external fixation has been reported as an alternative. We reviewed our experience with revision tibiotalar arthrodesis, with a focus on ring external fixation. METHODS: Forty-five consecutive patients underwent revision tibiotalar arthrodesis with use of repeat internal fixation (eleven patients), ring external fixation (twenty-two patients), or tibiotalocalcaneal arthrodesis (twelve patients). Union rates were assessed radiographically, and functional outcome was determined with use of preoperative and postoperative American Orthopaedic Foot and Ankle Society ankle-hindfoot scores. RESULTS: All forty-five patients were available for follow-up at an average of 50.3 months. The average ankle-hindfoot score improved from 31.1 points preoperatively to 65.8 points at the time of the most recent follow-up. At the time of the most recent follow-up, the union rate was 88.9% (forty of forty-five). Fusion was achieved with revision tibiotalar arthrodesis in thirty-six (80%) of forty-five patients, including eight of the eleven patients in the repeat internal fixation group, nineteen of the twenty-two patients in the ring external fixation group, and nine of the twelve patients in the tibiotalocalcaneal arthrodesis group. Re-revision led to union in four of five patients. The overall union rate for ring external fixation, including revision and re-revision tibiotalar arthrodeses, was 84.6% (twenty-two of twenty-six). The five patients with persistent nonunion following revision ankle arthrodesis opted for transtibial amputation. CONCLUSIONS: Revision tibiotalar arthrodesis leads to satisfactory limb salvage in a majority of patients. Ring external fixation may facilitate clinically acceptable limb salvage in complex cases when methods of internal fixation are limited or even contraindicated.