Effects of high antibiotic concentrations applied to continuous local antibiotic perfusion on human bone tissue-derived cells

Aims

Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 μg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells.

Methods

Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies.

Results

The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 μg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 μg/ml, and ALP activity was significantly decreased at ≥ 750 μg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 μg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 μg/ml on day 21 and at 500 μg/ml on day 28, and ALP activity was significantly decreased at 500 μg/ml on day 28.

Conclusion

Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting.

Treatment of infected bone defects with the induced membrane technique

Aims

This study aimed to evaluate the effectiveness of the induced membrane technique for treating infected bone defects, and to explore the factors that might affect patient outcomes.

Methods

A comprehensive search was performed in PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases between 1 January 2000 and 31 October 2021. Studies with a minimum sample size of five patients with infected bone defects treated with the induced membrane technique were included. Factors associated with nonunion, infection recurrence, and additional procedures were identified using logistic regression analysis on individual patient data.

Results

After the screening, 44 studies were included with 1,079 patients and 1,083 segments of infected bone defects treated with the induced membrane technique. The mean defect size was 6.8 cm (0.5 to 30). After the index second stage procedure, 85% (797/942) of segments achieved union, and 92% (999/1,083) of segments achieved final healing. The multivariate analysis with data from 296 patients suggested that older age was associated with higher nonunion risk. Patients with external fixation in the second stage had a significantly higher risk of developing nonunion, increasing the need for additional procedures. The autografts harvested from the femur reamer-irrigator-aspirator increased nonunion, infection recurrence, and additional procedure rates.

Conclusion

The induced membrane technique is an effective technique for treating infected bone defects. Internal fixation during the second stage might effectively promote bone healing and reduce additional procedures without increasing infection recurrence. Future studies should standardize individual patient data prospectively to facilitate research on the affected patient outcomes.

Resistant distal femoral nonunion treated with combined nail/plate construct and reamer-irrigator-aspirator technique

OBJECTIVE

This study was performed to evaluate the effectiveness of intramedullary nailing and a lateral locking plate combined with the reamer-irrigator-aspirator (RIA) bone grafting technique for resistant distal femoral nonunion.

METHODS

This retrospective observational study was performed from January 2018 to December 2021 and involved five patients who presented with resistant distal femoral nonunion despite undergoing several surgeries. They were treated with intramedullary nailing and a lateral locking plate combined with the RIA bone grafting technique. Postoperative follow-up was performed to observe the healing time, and functional outcomes were evaluated using the Lower Extremity Functional Scale (LEFS).

RESULTS

After the patients had been monitored for a mean of 17.9 months, complete bone healing was observed in every patient (mean healing time of 4.8 months). Postoperative wound failure in an older patient was successfully treated with resuturing and nutritional assistance. At the last follow-up, the mean LEFS score was 71.2/80 and the mean knee flexion was 109 degrees.

CONCLUSIONS

Our study demonstrates that combining intramedullary nailing and a lateral locking plate with the RIA bone grafting technique enhances biological properties, provides good structural support, and achieves good union and functional results in the management of resistant nonunion of the distal femur.

The Reamer-Irrigator-Aspirator (RIA) System for the treatment of aseptic femoral nonunions: Report of two cases and literature review

Femoral shaft nonunions are disabling complications of fractures, with relevant socioeconomic and psychological impact. The incidence of femoral shaft nonunions is not negligible, ranging between 1% and 10% after intramedullary nailing, but can exceed 20% in case of subtrochanteric fractures. Treatment options are influenced by pathomechanical, anatomical, and clinical factors. Hypertrophic nonunions are usually treated by enhancing stability of fixation, while atrophic nonunions require additional biological stimulation to achieve bone union. The Reamer-Irrigator-Aspirator (RIA) System® was developed to reduce intramedullary pressure and heat generation during intramedullary reaming, thus preventing thermal necrosis and decreasing the risk of fat embolism. The RIA System allows to provide large volumes of high-quality morselized autologous bone, that has shown high osteogenetic and osteoinductive properties. Therefore, its use has been expanded as a valuable source of autologous bone graft for the treatment of large bone defects of different nature. In this article, we present two cases of complex femoral nonunions treated with the use of the RIA System. A review of the published literature on the treatment of femoral nonunions with RIA was also performed. Core tip: In case of atrophic nonunions, the RIA System can be used to obtain biologically active tissue to enhance bone healing. Despite the absence of high-quality studies focused on femoral nonunions, the efficacy of RIA is well-known and orthopaedic surgeons should be aware of this powerful tool.

Nonunion After an Open Trimalleolar Ankle Fracture: An Extended Clinical Course and a Novel Approach to Tibio-Talo-Calcaneal Arthrodesis

Nonunion in the setting of chronic osteomyelitis after severe open ankle fractures is a feared outcome with severe loss in patient quality of life. Tibio-talo-calcaneal arthrodesis is a good salvage treatment option in this difficult patient cohort. We report a case of chronic osteomyelitis with severe destruction of the ankle joint after failed fracture fixation of an open trimalleolar ankle fracture. Fusion was ultimately achieved 5 years later using a novel-staged Masquelet technique with external ring fixator stabilization and bone graft reconstruction including femoral harvested autograft using reamer-irrigator-aspirator. This case shows that infection free arthrodesis of the ankle can be achieved even years after failed treatment. This procedure restored significant quality of life through pain relief and much improved mobility and may be a helpful technique in complex tibio-talo-calcaneal arthrodesis in the setting of chronic osteomyelitis and significant joint destruction.

Native multipotential stromal cell colonization and graft expander potential of a bovine natural bone scaffold

Graft expanders are bone scaffolds used, in combination with autografts, to fill large bone defects in trauma surgery. This study investigates the graft expander potential of a natural bone substitute Orthoss by studying its ability to support attachment, growth and osteogenic differentiation of neighboring multipotential stromal cells (MSCs). Material consisting of bone marrow (BM) aspirate and reamer-irrigator-aspirator (RIA)-harvested autograft bone was co-cultured with commercially available Orthoss granules. Native MSCs attached to Orthoss were expanded and phenotypically characterized. MSCs egress from neighboring cancelous bone was assessed in 3D Matrigel co-cultures. MSC differentiation was evaluated using scanning electron microscopy and measuring alkaline phosphatase (ALP) activity per cell. CD45(+) hematopoietic lineage cells and highly proliferative CD90(+) CD73(+) CD105(+) MSCs preferentially colonized Orthoss granules, over RIA bone chips. MSC colonization was followed by their intrinsic osteogenic differentiation, assessed as mineral deposition and gradual rise in ALP activity, even in the absence of osteogenic stimuli. When in contact with mixed cell populations and RIA chips, Orthoss granules support the attachment, growth and osteogenic differentiation of neighboring MSCs. Therefore, natural bone substitutes similar to Orthoss can be used as void fillers and graft expanders for repairing large bone defects in conjunction with autologous BM aspirates and autografts.