Antibiotic-impregnated cement spacer for bone defects of the forearm and hand

Feasibility evaluation of the induced membrane technique with structural autologous strip bone graft management of phalangeal and metacarpal segmental defects using radiography

PURPOSE

The purpose of this study was to explore the feasibility and evaluate the clinical outcomes of treatment for phalangeal and metacarpal segmental defects with the induced membrane technique and autologous structural bone grafting.

METHODS

Sixteen patients who sustained phalangeal or metacarpal bone segmental defects were treated by the induced membrane technique and autologous structural bone grafting from June 2020 to June 2021 at our center.

RESULTS

The average follow-up was 24 weeks (range, 12-40 weeks). Radiography demonstrated union of all bone grafts after an average of 8.6 weeks (range, 8-12 weeks). All incisions at donor and recipient sites demonstrated primary heal without infection complications. The mean visual analog scale score of the donor site was 1.8 (range, 0-5), with a good score in 13 cases and a fair score in 3. The mean total active motion of the fingers was 179.9°.

CONCLUSIONS

The feasibility of the induced membrane technique and structural treatment with a cylindrical bone graft for segmental bone defects of the metacarpal or phalanx is demonstrated by follow-up radiography results. The bone graft provided much more stability and structural support in the bone defects, and the bone healing time and bone union rate were ideal.

Resorbable polylactide membrane for the treatment of segmental bone defects

INTRODUCTION

Segmental bone defects are a challenging clinical problem. In animal studies and craniomaxillofacial surgery, resorbable polylactide membrane (OrthoMesh; DePuy Synthes, West Chester, PA) shows promise for treatment of bone defects. This study presents the results of the treatment of segmental bone defects with resorbable polylactide membrane, bone morphogenic protein-2 (BMP-2), and autograft.

METHODS

This study was approved by the institutional review board. All patients with a segmental bone defect treated with a resorbable polylactide membrane by a single surgeon from 2010 to 2019 were retrospectively reviewed. Data related to demographic variables, surgical details, and union were collected.

RESULTS

Eleven patients with median age of 37 years (range 22-62 years) were included in the study with segmental bone defects in the tibia (n = 3), femur (n = 4), or forearm (n = 4). Median bone defect size was 6 cm (range 3-12 cm). Etiology of bone defects included osteomyelitis (n = 7), oncologic resection (n = 3), and post-traumatic aseptic nonunion (n = 1). Flap coverage was performed in two patients. Median radiographic follow-up was 24 months (range 5-75 months). Ten patients (10/11) achieved union at a median of 17 months (range 5-46 months). Seven patients required reoperation for any reason with six patients requiring repeat grafting.

CONCLUSIONS

To our knowledge, this study is the largest series of patients with segmental bone defects treated with resorbable polylactide membrane. Resorbable polylactide membrane in combination with BMP-2 and autograft represents a safe and effective method of bone graft containment in segmental bone defects measuring up to 12 cm in this series. Ten of 11 patients achieved union at a median time of 16 months with 6 patients requiring repeat grafting. These results compare favorably with the induced membrane technique. This study is limited by its retrospective design, absence of control and comparison groups, and low patient numbers. Future prospective randomized study of the induced membrane technique and resorbable polylactide membrane should be undertaken to determine preferred approaches for treatment of segmental bone defects.

Sustaining Antibiotic Release from a Poly(methyl methacrylate) Bone-Spacer

One of the challenges in using a bone-spacer to cure infection is the fabrication of a material that can continuously release required antibiotics at effective concentrations for at least 4-6 weeks. Poly(methyl methacrylate) (PMMA) impregnated with antibiotics is one of the popularly used bone-spacer materials. Currently, improved sustained release of hydrophobic and hydrophilic antibiotics is needed for this material. Here, hydrophilic vancomycin (VAN) was encapsulated into calcium citrate (CC) particles and natural rice granules, and hydrophobic erythromycin (ERY) was encapsulated into ethyl cellulose and poly(lactic-co-glycolic acid) particles. The four antibiotic-loaded particles were each incorporated into the PMMA cement. The two unencapsulated drugs and all four drug-loaded particles distributed well in the obtained composites. PMMA composited with VAN-loaded CC showed prolonged VAN release at an effective concentration for more than 40 days, but the composite possessed lesser compressive strength than the PMMA with no drug. PMMA composited with unencapsulated ERY showed a better sustainment of drug release than those composited with encapsulated ERY. VAN elution from the VAN-CC-PMMA did not significantly affect the compressive strength of the material, whereas ERY elution from the ERY-PMMA composite significantly decreased the material's mechanical strength.

Photodynamic Antimicrobial Chemotherapy (PACT) in osteomyelitis induced by Staphylococcus aureus: Microbiological and histological study

Osteomyelitis is an inflammation either of medullar spaces or of the surface of cortical bones, which represents a bacterial infection. Photodynamic Antimicrobial Chemotherapy (PACT) is a treatment based on a cytotoxic photochemical reaction that induces a series of metabolic reactions and culminates in bacterial suppression. Such effect led to the idea that it could be used as a treatment of osteomyelitis. Following approval by the Animal Experimentation Committee of the School of Dentistry of the Federal University of Bahia, the present randomized study used eighty Wistar rats with the aim to evaluate, by microbiological and histological analysis, the effects of Photodynamic Antimicrobial Chemotherapy - PACT on tibial surgical bone defects in rats infected by Staphylococcus aureus. The animals were divided in groups: Control (non-infected); Control Osteomyelitis Induction; Saline solution; Photosensitizer; Red Laser and PACT - on this group, a diode laser (40mW; λ660nm ∅=0.04cm(2), CW, 10J/cm(2)) was used in combination with 5μg/ml of toluidine blue as the photosensitizer. On the microbiological study, immediately after treatment, the PACT group presented a bacterial reduction of 97.4% (p<0.001). Thirty days after treatment, there was a bacterial reduction of more than 99.9% (p<0.001). In the histological study, it was observed that the PACT group demonstrated an intense presence of osteocytes and absence of bone sequestration and micro-abscesses. The PACT using toluidine blue was effective in reducing the number of S. aureus enabling a better quality bone repair.

Current therapies for diabetic foot infections and osteomyelitis

Treatment of the patient with a diabetic foot infection and underlying osteomyelitis is currently an evolving process, often complicated by neuropathy, peripheral vascular disease, and renal insufficiency. Understanding which patients require hospitalization, intravenous antibiotic therapy, and urgent operative intervention may ultimately prevent the spread of infection or major limb amputation. The treating surgeon should focus on accurate and early diagnosis, proper antibiosis, and appropriate surgical debridement to eradicate infection while preserving function with a plantar-grade foot.

Application of an antibiotic intramedullary nail in the management of a large metacarpal bone defect

Contaminated wounds and infected nonunions of the hand are not amenable to primary internal fixation and grafting. Antibiotic-impregnated cement intramedullary nails have been used in the lower extremity in the treatment of these fractures but have not been described in the hand. This technique combines the advantages of local antibiotic delivery with the mechanical stability afforded by an intramedullary nail. We describe an alternative technique for the management of skeletal defects in a contaminated wound bed in the hand using readily available operating room equipment. The antibiotic-impregnated cement intramedullary nail can be placed temporarily until definitive internal fixation and grafting occur.

A new preclinical approach for treating chronic osteomyelitis induced by Staphylococcus aureus: in vitro and in vivo study on photodynamic antimicrobial therapy (PAmT)

Osteomyelitis is an acute or chronic inflammation in the marrow spaces in the superficial or cortical bone, and can be associated with bacterial or fungal infections. Chronic osteomyelitis represents a major health problem due to its difficult treatment and increased morbidity. Photodynamic antimicrobial therapy (PAmT) is a treatment based on a cytotoxic photochemical reaction in which a bright light produced by a laser system and an active photosensitizer absorbed by cells leads to a process of activation that induces a series of metabolic reactions that culminates a bacterial killing. The aim of the present randomized study was to evaluate, by in vitro and in vivo microbiological analysis, the effects of PAmT on tibial surgical bone defects in rats infected by Staphylococcus aureus using bacterial counts carried out immediately and after 30 days after treatment as outcome measure. In the preliminary in vitro study, a diode laser (λ660 nm; 40 mW; ϕ = 0.4 cm(2); 5 or 10 J/cm(2)) and 5, 10, and 15 μg/mL toluidine blue were tested, and the best parameter was chosen for the in vivo study. The concentration of 5 μg/mL was selected to perform the decontamination of S. aureus-infected tibial bone defects in rats. The findings were subjected to statistical analysis. For all PAmTs groups, with the different concentrations, treatment showed significant reductions (p < 0.001) in the amount of bacteria. The in vivo study PAmT group presented a bacterial reduction of 97.4% (p < 0.001). The PAmT using toluidine blue was effective in reducing the number of S. aureus in both in vitro and in vivo studies.

The role of polymethylmethacrylate antibiotic-loaded cement in addition to debridement for the treatment of soft tissue and osseous infections of the foot and ankle

Polymethylmethacrylate (PMMA) has been used in skeletal surgery for >40 years as a means of securing prosthetic implants and more recently was used as a delivery agent for local high-dose antibiotics to treat soft tissue and osseous infections. The purpose of this study was to determine the role of PMMA antibiotic-loaded cement (PMMA-ALC) in combination with aggressive debridement for the treatment of foot and ankle soft tissue and osseous infections requiring operative intervention. A retrospective observational cohort study of prospectively collected data was performed for all patients who underwent aggressive debridement with placement of PMMA-ALC for foot and ankle soft tissue and osseous infections between July 2006 and January 2009. There were 35 (29 men, 6 women) patients, 29 who had diabetes, with a mean age of 61 1 13 years (range, 16-86 years). A total of 36 feet/ankles (20 right, 16 left) were involved, and the infections were anatomically divided into 6 groups: (1) toes (n = 9), (2) metatarsalphalangeal joints (MTPJ) (first MTPJ, n = 5; fifth MTPJ, n = 5), (3) forefoot (n = 11), (4) rearfoot (n = 4), and (6) ankle/lower leg (n = 3). All patients had confirmed bacterial infection via microbiologic or pathologic analysis before PMMA-ALC insertion. A total of 73 cultures were obtained at the time of PMMA-ALC removal, with 66 showing no bacterial growth (90.4%) and 7 positive for bacterial growth (9.6%). Methicillin-resistant Staphylococcus aureus was the most commonly cultured organism both preoperatively and postoperatively. When combined with aggressive irrigation and debridement, the use of PMMA-ALC appears to be a beneficial adjunctive therapy for the treatment of foot and ankle soft tissue and osseous infections.

Treatment of osteomyelitis in rats by injection of degradable polymer releasing gentamicin

We evaluated the potential of an injectable degradable polymer-poly(sebacic-co-ricinoleic-ester-anhydride) containing gentamicin for the treatment of osteomyelitis. Osteomyelitis of both tibiae was induced in 13 female Fischer rats by injecting a suspension containing approximately 105 (CFU)/ml of S. aureus into the tibial medullar canal. Three weeks later both tibiae were X-rayed, drilled down the medullar canal, washed with 50 microl gentamicin solution (80 mg/2 ml) and then injected with 50 microl P(SA-RA)+gentamycin 20% w/v to the right tibia and 50 microl P(SA-RA) without gentamicin to the left tibia. After an additional 3 weeks, the rats were sacrificed, and radiographs of the tibiae were taken. Histopathological evaluation of the tibiae was done in a blinded manner. X-ray radiographs showed that all tibiae developed changes compatible with osteomyelitis in 3 weeks. Histological evaluation revealed significant differences between right and left tibiae in 10 rats. In the left tibia moderate intramedullary abscess formation occurred. In most treated tibiae typical changes included the absence (or minimal grade only) of abscesses. The treated group developed significantly less intramedullary abscesses; the p value was 0.028. Locally injected degradable polymer releasing gentamicin proved to be efficient histologically in the treatment of osteomyelitis.

Do we need synthetic osteotomy augmentation materials for opening-wedge high tibial osteotomy

High tibial osteotomy (HTO) is an increasing popular method to treat unicompartimental osteoarthritis of the knee in younger, active patients. In so doing one tries to delay the need for total or unicompartimental joint replacement. The augmentation of HTO opening gaps with supporting material is discussed controversially, especially after the introduction of locking plates, which contribute to the decline of the non-union rate. Currently, we do not recommend synthetic augmentation, when using locking plates in HTO with opening angles less than 10 degrees . In our recent randomized study we could histologically and radiologically demonstrate the complete rebuilding of lamelliform bone in patients without synthetic augmentation, whilst bony ingrowth into the hydroxyapatite/tricalcium phosphate (HA/TCP) wedge of augmented osteotomies just slowly progressed. In contrast to unaugmented osteotomies, there was no advantage in using HA/TCP wedges or the combination of HA/TCP wedges and platelet rich plasma (PRP) as supporting material after 12 months. In osteotomies where an opening angle bigger than 7.5 degrees is chosen, rigid locking plates should be used. In our opinion, autologous iliac crest graft should be used in the high-risk patients (obese, smoker, opening angle bigger than 10 degrees ). Whether synthetic augmentation combined with PRP is equal or even superior to autologous iliac crest graft in openings bigger than 10 degrees has not been proven yet.