Introduction and Objective

Osteochondral allograft (OCA) transplants have been used clinically for more than 40 years as a surgical option for joint restoration, particularly for young and active patients. While immediate graft rejection responses have not been documented, it is believed that the host's immunological responses may directly impact OCA viability, incorporation, integrity, and survival, and therefore, it is of the utmost importance to further optimize OCA transplantation outcomes. The influences of sub-rejection immune responses on OCA transplantation failures have not been fully elucidated therefore aimed to further characterize cellular features of OCA failures using immunohistochemistry (IHC) in our continued hopes for the successful optimization of this valuable surgical procedure.

Objectives

The period of post-operative treatment before surgical wounds are completely closed remains a key window, during which one can apply new technologies that can minimise complications. One such technology is the use of negative pressure wound therapy to manage and accelerate healing of the closed incisional wound (incisional NPWT).

Purpose: Fractures of the calcaneus remain a significant clinical challenge. Little study has been done to investigate the potential benefit of bone graft in the treatment of these fractures. The purpose of this study is to compare the clinical outcome of calcaneus fractures treated with and without ICBG.

Method: In an ongoing study at a Level I Trauma Center 45 patients with calcaneus fractures requiring operative management were enrolled in a prospective, randomized study. 24 patients were randomized to ORIF without graft (control) and 24 patients were randomized to ORIF with ICBG (study group). Demographic, intra-operative and long term clinical outcome data was collected. Outcome measures included pain scores, Creighton-Nebraska Foot Scores, time to weight bearing, return to work and wound complications.

Results: The groups showed no differences in gender, age, mechanism of injury, fracture classification or time to surgery (avg. 12 days). Tscherne scores at presentation differed, with higher average scores in the control group. There were 2 open fractures in each group. The groups showed no statistically significant differences in any of the clinical outcome measures. There was no difference in pain scores (control mean 2.6 vs. study mean 4.1, p = 0.1), Creighton-Nebraska Scores (control 71 vs. study 55, p = 0.1), time to weight bearing (control 2.6 months vs. study 2.7 months, p = 0.9). At 6 months 38% of controls had returned to work (with 87% of those returning to the some occupation) while 39% of the study group returned to work (71% to same occupation). An overall wound complication rate of 27% was seen with 30% of controls and 24% of study patients exhibiting wound issues.

Conclusion: In this prospective randomized study, patients treated with ORIF for calcaneus fractures showed no difference in clinical outcomes with or without the addition of ICBG. No clear benefit is demonstrated to warrant the additional operative time, pain and possible complications that have been previously documented to be associated with ICBG.

Purpose: Autologous bone grafting is considered the gold standard for multiple orthopaedic indications, including non-union of fractures and other bone defects. Previously autograft was most commonly harvested from the iliac crest, with an estimated complication rate of greater than 10%. New technology, the RIA system, allows harvest of graft material from the medullary canal of the femur. The purpose of this study is to examine the osteo-inductive properties of this human femoral bone graft obtained using the RIA system and the RIA filtrate combined with chronOS (Tricalcium Phosphate). This study will examine whether these materials will induce bone growth when implanted in a rat sub-muscular pouch model.

Method: Three samples were collected from each human subject. These included:

femoral bone graft obtained using the RIA {n=10}

chronOS (alone) was used as control {n=10}. These materials were implanted into a sub-muscular pouch in athymic rats (to eliminate rejection of the xenograft). Rat serum levels of BMP-2, VEG-F, TGF-β and IL-10 were obtained at days 7, 14, 21 and 28. Rats were sacrificed at day 28 and radiographic and histologic examinations and histomorphometric analyses were performed.

Results: Overall, there were no significant differences in BMP-2, VEG-F, TGF-β and IL-10 levels either between groups or between time points. Average serum values for BMP-2 decreased over time for all groups. Histologically and radiographically, all four materials induced new bone production. chronOS alone produced the greatest volume of new bone while RIA reamings alone produced the least. Histological analysis demonstrated formation of normal bone.

Conclusion: The RIA system allowed for harvest of femoral bone graft. This graft induced bone formation and increased osteogenic protein levels when implanted in the rat model. The RIA filtrate, when combined with Tricalcium Phosphate, is equally osteoinductive. Combining reamings with filtrate material may allow large volumes of graft to be produced using this system. This new technology may allow the collection of large volume, osteoinductive grafts without the complications previously described for iliac crest bone graft harvesting.

Purpose: One of the most difficult challenges for orthopaedic surgeons is the management of bone loss resulting in a segmental bone defect. Segmental bone defects are ubiquitously difficult to treat, require multi-phase surgery and have frequent complications. A promising new strategy involves combining tissue engineering techniques with the delivery of biologically active proteins to facilitate bone regeneration. The purpose of this study is twofold:

First, to investigate whether a cylindrical, biodegradable load-bearing scaffold, stabilized with an intramedullary (IM) nail, will facilitate early weight bearing in a critical sized canine defect model.

Method: A critical size defect of 3 cm was created in the canine tibia by osteotomy. A cylindrical, biodegradable scaffold of (poly) propylene fumarate was inserted into the defect and the tibia was stabilized with a locked intramedullary nail. Half of the scaffolds were impregnated with 300μg rhBMP-2 and half remained as controls. The animals were allowed immediate weight bearing post-operatively. X-rays were obtained post-operatively and at weeks 1, 2, 3, 6, 12, 18, and 24. X-rays were assessed for loss of height, integrity of the scaffold, and presence of bridging callous formation.

Results: The animals that received scaffolds treated with rhBMP-2 showed abundant callus formation on X-ray. Partial bridging callus formation in this group was seen at 3 weeks. Complete bridging callus (bridging on 4 cortices) was observed by 6 weeks. These specimens maintained height of the defect and overall length of the tibia. Controls demonstrated minimal callus formation at all time points. By 3 weeks significant loss of defect height was observed. By 6 weeks failure of hardware (breakage of interlocking screws and/or screw loosening) was evident.

Conclusion: This study shows that biodegradable scaffolds, treated with rhBMP-2 and implanted in a critical sized defect facilitate bridging callus formation and healing across the defect. This data indicates that biodegradable scaffolds made of (poly) propylene fumarate are suitable carriers for rhBMP-2 while providing initial structural support for weight bearing.