Reconstruction of Long Bone Infections Using the Induced Membrane Technique: Tips and Tricks

Acute prophylactic antibiotic nailing of open femoral shaft fractures for prevention of fracture-related infection

Background

Open, grossly contaminated femoral shaft fractures pose a significant threat for fracture-related infection. Traditional treatment for these injuries consists of irrigation and debridement with temporizing external fixation placement and staged conversion to definitive fixation.

Methods

We describe a protocol for acute antibiotic cement nailing of open femoral shaft fractures as an infection prophylaxis modality in fractures with a high risk of infection and present three cases.

Results

Three patients presented with open femoral shaft fractures with large soft tissue defects and gross contamination and were successfully treated with acute retrograde antibiotic nailing and external fixation with later conversion to definitive metallic nailing. They did not develop infection and had acceptable postoperative function and fracture alignment.

Conclusion

This technique of early infection prophylaxis after open femoral shaft fracture is reproducible, pragmatic, and cost-effective.

The induced membrane technique for the management of infected segmental bone defects

Aims

The aim of the present study was to assess the outcomes of the induced membrane technique (IMT) for the management of infected segmental bone defects, and to analyze predictive factors associated with unfavourable outcomes.

Methods

Between May 2012 and December 2020, 203 patients with infected segmental bone defects treated with the IMT were enrolled. The digital medical records of these patients were retrospectively analyzed. Factors associated with unfavourable outcomes were identified through logistic regression analysis.

Results

Among the 203 enrolled patients, infection recurred in 27 patients (13.3%) after bone grafting. The union rate was 75.9% (154 patients) after second-stage surgery without additional procedures, and final union was achieved in 173 patients (85.2%) after second-stage surgery with or without additional procedures. The mean healing time was 9.3 months (3 to 37). Multivariate logistic regression analysis of 203 patients showed that the number (≥ two) of debridements (first stage) was an independent risk factor for infection recurrence and nonunion. Larger defect sizes were associated with higher odds of nonunion. After excluding 27 patients with infection recurrence, multivariate analysis of the remaining 176 patients suggested that intramedullary nail plus plate internal fixation, smoking, and an allograft-to-autograft ratio exceeding 1:3 adversely affected healing time.

Conclusion

The IMT is an effective method to achieve infection eradication and union in the management of infected segmental bone defects. Our study identified several risk factors associated with unfavourable outcomes. Some of these factors are modifiable, and the risk of adverse outcomes can be reduced by adopting targeted interventions or strategies. Surgeons can fully inform patients with non-modifiable risk factors preoperatively, and may even use other methods for bone defect reconstruction.

A retrospective cohort study of autogenous iliac strut bone grafting in large bone defects of the lower extremity

Autogenous iliac bone graft (AIBG) is the treatment of choice for managing bone defects, and favorable results have been reported for bone defects < 5 cm in length. In large bone defects ≥ 5 cm, it is difficult to obtain good results with simple bone grafting, and other management options have drawbacks, such as long immobilization periods and high complication rates. We hypothesized that AIBG in the strut form might show favorable results in large bone defects with minimal complications. This study aimed to investigate the outcomes of strut-type AIBG and evaluate its effectiveness compared to cancellous AIBG. This retrospective study included 50 patients who underwent AIBG for bone defects at a single institution between March 2011 and April 2020. We performed corticocancellous AIBG in a strut form to manage bone defects ≥ 5 cm in the lower extremities. The strut bone was harvested along the iliac crest and grafted slightly longer than the bone defect to apply a sufficient compressive force. Demographic information and radiographic and clinical results of patients who underwent strut AIBG (Group S) were analyzed. The outcomes of union, time to union, complications, and reoperation were compared with those of patients who underwent cancellous AIBG (Group C). The study population comprised 37 men (74%) and 13 women (26%), with a mean age of 50.0 (range: 19-78). The average follow-up period was 25.6 months (12-104 months). Group S included 16 patients with a mean bone defect length of 6.8 ± 1.2 cm. In Group S, union was achieved in all patients, with an average time to union of 6.7 months. Complications occurred in four cases, all related to wound problems. Group C comprised d 34 patients with a mean defect length of 2.8 ± 1.1 cm. Complications occurred in five patients in Group C, including four soft tissue problems and one implant failure. When comparing the outcomes of Groups S and C, no significant differences were observed. AIBG is an effective and safe technique for managing bone defects. Strut AIBG can be used effectively for bone defects ≥ 5 cm in the lower extremities.

Antibiotic impregnated cement coated intramedullary nail (ACCIN) using bronchoscopy tubing: technical tips, case series and a review of the literature

Antibiotic impregnated cement coated intramedullary nails (ACCINs) have been used in clinical practice for many years and have been shown to help eradicate infection in tibial osteomyelitis while providing stability. We present a novel technique for preparation using bronchoscopy tubing, as well as technical tips and a review of the literature, for ease of preparation and potential subsequent retrieval.

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.

Masquelet technique in military practice: specificities and future directions for combat-related bone defect reconstruction

Because of its simplicity, reliability, and replicability, the Masquelet induced membrane technique (IMT) has become one of the preferred methods for critical bone defect reconstruction in extremities. Although it is now used worldwide, few studies have been published about IMT in military practice. Bone reconstruction is particularly challenging in this context of care due to extensive soft-tissue injury, early wound infection, and even delayed management in austere conditions. Based on our clinical expertise, recent research, and a literature analysis, this narrative review provides an overview of the IMT application to combat-related bone defects. It presents technical specificities and future developments aiming to optimize IMT outcomes, including for the management of massive multi-tissue defects or bone reconstruction performed in the field with limited resources.

Bone defect treatment: does the type and properties of the spacer affect the induction of Masquelet membrane? Evidence today

PURPOSE

High clinical success rates have been reported with the Masquelet technique in the treatment of traumatic bone loss. An increasing number of studies suggest that various factors can influence the properties of induced membranes. Goal of this systematic review is to answer the following questions: (1) which are the ideal spacer properties (material, surface topography, antibiotic supplementation) to booster the quality and osteogenic potential of induced membranes? (2) what is the ideal time to perform the second-stage operation?

METHODS

A systematic search using the keywords "((Masquelet) OR (Induced Periosteum)) AND ((Spacer) OR (Time))" was performed in PubMed, Embase and Cochrane Library according to PRISMA guidelines. Studies published up to the 23rd of February 2022 were included and assessed independently by two reviewers.

RESULTS

Thirteen animal and 1 clinical studies were identified to address the above questions. Spacer materials used were PMMA, silicone, titanium, polypropylene, PVA, PCL and calcium sulfate. With the exception of PVA sponges, all solid materials could induce membranes. Low union rates have been reported with titanium and rough surfaced spacers. Scraping of the inner surface of the IM also increased bony union rates. In terms of the ideal timing to perform the second-stage evidence suggests that membranes older than 8 weeks continue to have regenerative capacities similar to younger ones.

CONCLUSION

Membranes induced by smooth PMMA spacers loaded with low concentrations of antibiotics showed powerful osteogenic properties. Other materials such as Polypropylene or Calcium sulfate can also be used with good results. Despite current recommendation to perform the second stage operation in 4-8 weeks, membranes older than 8 weeks seem to have similar regenerative capacities to younger ones.

Local Fixation of Colistin With Fibrin Spray: An in vivo Animal Study for the Therapy of Skin and Soft Tissue Infections

Objective

Skin and soft tissue infections (SSTI) are a commonly known entity of diseases associated with difficult treatment procedures. The current gold standard when there is a rapidly progressing infection of soft tissues with a risk of sepsis is radical surgical debridement accompanied by systemic antibiotic therapy. In clinical settings, local antibiotics alone or formulated within carrier material are commonly used alongside this therapy regimen. One possibility of local antibiotic application is the fixation of colistin with fibrin glue spray. It is not yet sufficiently researched how the local antibiotic concentrations remain as high as possible over time.

Methods

We conducted an animal study including 29 male Wistar rats inducing sterile back sores reaching the muscle fascia. We sprayed only colistin, simultaneously or consecutively, with fibrin glue in different groups in order to measure the tissue concentration of the antibiotic applied locally.

Results

After liquid chromatography and quadrupole mass spectrometry analysis, it could be demonstrated that in comparison to the colistin group, tissue concentrations of colistin stayed significantly higher in the wound tissue when it was fixed with fibrin glue. This was observed in both groups, the simultaneous as well as in the consecutively fibrin glue sprayed groups after colistin application.

Conclusion

The fixation of colistin with the fibrin-glue-spray technique as a carrier for local antibiotic therapy is an easy and inexpensive method and shows promising potential for the treatment of SSTI.

Effects of PMMA spacer loaded with varying vancomycin concentrations on bone regeneration in the Masquelet technique

Whether antibiotics should be included remains greatly debated in Masquelet technique. This study intended to determine the effect of polymethyl methacrylate (PMMA) spacer loaded with different vancomycin concentrations on bone defect repair. Hollow cylindrical spacers consisting of PMMA and varying vancomycin concentrations (0, 1, 2, 4, 6, 8, and 10 g) were prepared. Critical bone defects of rabbits were created at the radial shaft, and spacers were implanted and subsequently intramedullary fixed with retrograde Kirschner’s wires (n = 4 for each vancomycin concentration). After 4 weeks, the induced membranes were opened and cancellous allografts were implanted into the defects. Eight weeks post-operatively, the results of X-ray, histology, and micro-CT revealed that some cortical bone was formed to bridge the gap and the bone marrow cavity was formed over time. Quantitatively, there was more new bone formation in the groups with a relatively lower vancomycin concentration (1–4 g) compared with that in the groups with a higher vancomycin concentration (6–10 g). Our findings suggested that PMMA spacers loaded with relatively lower vancomycin concentrations (1–4 g) did not interfere with new bone formation, whereas spacers loaded with relatively higher vancomycin concentrations (6–10 g) had negative effects on bone formation.

Antibiotic cement coating in orthopedic surgery: a systematic review of reported clinical techniques

Background

Antibiotic-containing cement and bone graft substitute-coated orthopedic implants provide the advantages of simultaneous local antibiotic delivery and internal stable fixation, aiding in both infection eradication and osseous healing. Standardized protocols pertaining to implant coating techniques in various clinical and particularly intraoperative settings are scarce, and available literature is limited. This systematic review aims to provide a summary of the available current literature reporting on custom-made coating techniques of orthopedic implants, indications, outcomes, and associated complications in clinical use.

Methods

A systematic search of the literature in PubMed, Medline, Embase, and Cochrane Library databases was performed in accordance with PRISMA guidelines. Articles reporting specifically on custom-made coating techniques of orthopedic implants in a clinical setting were eligible.

Results

A total of 41 articles with a cumulative total number of 607 cases were included. Indications for treatment mostly involved intramedullary infections after previous plate osteosynthesis or nailing. A variety of implants ranging from intramedullary nails, plates, wires, and rods served as metal cores for coating. Polymethylmethacrylate (PMMA) bone cement was most commonly used, with vancomycin as the most frequently added antibiotic additive. Chest tubes and silicone tubes were most often used to mold. Common complications are cement debonding and breakage of the metallic implant.

Conclusion

Adequate coating techniques can reduce the burden of treatment and be associated with favorable outcomes. Lack of general consensus and heterogeneity in the reported literature indicate that the perfect all-in-one implant coating method is yet to be found. Further efforts to improve implant coating techniques are warranted.

Level of evidence

III.

Complications in the Treatment of Delayed Union and Underlying Chronic Osteomyelitis After Right Crural Fracture Treated With Anterolateral Thigh Flap and Double-Barrelled Vascularized Fibula Graft

Background: Segmental bone defects pose a major, unsolved clinical challenge and may be the result of high-energy trauma, infection, and tumour resection or revision surgery. Several options exist to reconstruct, including Ilizarov bone transport, Masquelet technique, cylindrical mesh technique, allografts, and vascularized bone autografts. We present a patient with a delayed union of the tibia with concomitant chronic osteomyelitis treated with anterolateral thigh (ALT) flap and double-barrelled vascularized fibula graft.

Case presentation:A 60-year-old male with a chronic pretibial wound with underlying osteomyelitis of the right leg presented himself at the emergency department and was admitted to the surgical ward. He had complex chronic osteomyelitis of a tibial non-union after an earlier right crural fracture (a previous work-related accident). He was treated with an ALT flap and double-barrelled vascularized fibula graft, which was complicated with an additional fracture and breakage of osteosynthesis material.

Conclusion: Segmental bone defects pose a major, unsolved clinical challenge in orthopaedic, trauma-surgical, and plastic surgical practice. Concomitant infections and fractures can be part of the postoperative course. Patients with complex segmental bone defects need to be treated by a multidisciplinary team including at least an (orthopaedic) trauma surgeon, a plastic surgeon, and an infectiologist.

Strategies for large bone defect reconstruction after trauma, infections or tumour excision: a comprehensive review of the literature

Large bone defects resulting from musculoskeletal tumours, infections, or trauma are often unable to heal spontaneously. The challenge for surgeons is to avoid amputation, and provide the best functional outcomes. Allograft, vascularized fibular or iliac graft, hybrid graft, extracorporeal devitalized autograft, distraction osteogenesis, induced-membrane technique, and segmental prostheses are the most common surgical strategies to manage large bone defects. Given its optimal osteogenesis, osteoinduction, osteoconduction, and histocompatibility properties, along with the lower the risk of immunological rejection, autologous graft represents the most common used strategy for reconstruction of bone defects. However, the choice of the best surgical technique is still debated, and no consensus has been reached. The present study investigated the current reconstructive strategies for large bone defect after trauma, infections, or tumour excision, discussed advantages and disadvantages of each technique, debated available techniques and materials, and evaluated complications and new perspectives.

[Masquelet technique combined with flap transplantation for infectious bone and soft tissue defects of lower leg]

OBJECTIVE

To investigate the effectiveness of Masquelet technique combined with flap transplantation in treatment of infectious bone and soft tissue defects of the lower leg.

METHODS

Between January 2013 and January 2017, 35 cases of infectious bone and soft tissue defects of lower leg were treated with Masquelet technique combined with flap transplantation. There were 21 males and 14 females, with an average of 31.5 years (mean, 25-55 years). All patients were tibial fractures caused by trauma and the infections occurred after debridement or internal fixation. The time from injury to admission was 1 to 6 months, with an average of 3.2 months. Defect located at the proximal leg in 11 cases, the middle leg in 11 cases, and the distal leg in 13 cases. The length of tibia defect after debridement ranged from 5.6 to 11.2 cm, with an average of 7.1 cm. The size of soft tissue defect ranged from 14.2 cm×6.9 cm to 17.3 cm×8.7 cm. Bacterial culture of purulent secretion of wound was positive in 18 cases. After debridement, the bone cement was used to fill the bone defect and the flap transplantation was used to repair the wound. The bone cement was taken out at 8 to 12 weeks after the one-stage operation, and the bone defect was repaired with autogenous iliac bone or combined with artificial bone.

RESULTS

Three cases had necrosis at the distal edge of the flap after one-stage operation, and survived after dressing change. The other flaps survived successfully, and the wounds healed by first intention. All incisions healed by first intention after two-stage operation. All patients were followed up 24-32 months, with an average of 27 months. The color of the flap was similar to that of the surrounding normal tissue, and its texture was good. X-ray reexamination showed that all bone defects healed after 6-8 months, with an average of 6.7 months. At 9 months after two-stage operation, according to the revised Edwards tibial fracture evaluation standard, 19 cases were excellent, 14 cases were good, and 2 cases were poor, the excellent and good rate was 94.3%. The American Orthopedic Ankle Association (AOFAS) score was 60-98, with an average of 81.3. And 21 cases were excellent, 11 were good, and 3 were fair, with an excellent and good rate of 91.4%.

CONCLUSION

Masquelet technique combined with flap transplantation is an effective treatment for infectious bone and soft tissue defects of lower leg.

An antibiotic cement-coated locking plate as a temporary fixation for treatment of infected bone defects: a new method of stabilization

Background

The induced membrane technique has achieved good clinical results in the treatment of infected bone defects, and external fixation is the main method, but it causes inconvenience and complications in patients. In this study, our objective was to investigate the outcomes of using an antibiotic cement-coated locking plate as a temporary internal fixation in the first stage of the surgical induced membrane technique for treating extremities with infected bone defects.

Methods

We retrospectively analysed patients with lower extremity infected bone defects in our department between January 2013 and December 2017. All patients were treated with the induced membrane technique. In the first stage, the defects were stabilized with an antibiotic cement-coated locking plate as a temporary fixation after debridement, and polymethyl methacrylate cement was implanted to induce the formation of a membrane. In the second stage, bone grafting rebuilt the bone defects after infection control, and the temporary fixation was changed to a stronger fixation.

Results

A total of 183 patients were enrolled, with an average follow-up duration of 32.0 (12–66) months. There were 154 males and 29 females with an average age of 42.8 (10–68) years. The infection sites included 81 femurs, 100 tibias and 2 fibulas. After the first stage of treatment (infection control), 16 (8.7%) patients had recurrence of infection. In terms of the incidence of complications, 4 patients had poor wound healing, 2 patients had fixation failure and 1 patient had femoral fracture due to a fall. After the second stage of treatment (bone reconstruction), there were 24 (13.1%) recurrences of infection, with a mean time of 9.9 months (range 0.5 to 36). Among them, 18 patients underwent bone grafting after re-debridement, 6 received permanent placement of antibiotic bone cement after debridement and 2 patients refused further treatment and chose amputation. Bone healing was achieved in 175 (95.9%) patients at the last follow-up, and the average time to bone union was 5.4 (4–12) months.

Conclusions

Antibiotic cement-coated locking plates have good clinical effects in the control of bone infection, but attention must be paid to the possible difficulty of skin coverage when applied in calves.

Investigating clinical characteristics and prognostic factors in patients with chronic osteomyelitis of humerus

Background

Chronic osteomyelitis in the humerus, which has complex neuroanatomy and a good soft tissue envelope, represents a unique clinical challenge. However, there are relatively few related studies in the literature. This article retrospectively reviewed a large case series with the aims of sharing our management experiences and further determining factors associated with the outcomes.

Methods

Twenty-eight consecutive adult patients with a mean age of 36 years were identified by reviewing the osteomyelitis database of our clinic centre. The database was used to prospectively identify all osteomyelitis cases between 2013 and 2017, and all data then was retrospectively analysed.

Results

The mean follow-up period was 35 months (range 24–60). The aetiology was trauma in 43% (12) of the patients and haematogenous in 57% (16) of the patients, and Staphylococcus aureus was a solitary agent in 50% (14) of the patients. Host-type (Cierny’s classification) was IA in 8, IIIB in 11 and IVB in 9 patients. All patients required debridement followed by the placement of a temporary antibiotic-impregnated cement spacer (rod). Seventeen patients received a cement-coated plate for internal fixation after debridement, and 13 patients needed bone grafts when the spacer was staged removed. All patients attained an infection-free bone healing state at the final follow-up. The final average DASH (disabilities of the arm, shoulder and hand) score was 18.14 ± 5.39, while 6 patients (two developed traumatic olecranarthritis, four developed radial nerve injuries) showed the lowest levels of limb function (p = 0.000) and were unemployed. Three patients (type I; significant difference between type I versus type III and type IV patients, p < 0.05) experienced recurrence after debridement and underwent a second revision, which was not related to the bone graft (p = 0.226) or plate fixation (p = 0.050).

Conclusions

Humeral chronic osteomyelitis can be treated with general surgery and anti-infective therapy; medullary (type I) infection presents a challenge, and the antibiotic-coated cement plate provides favourable fixation without increasing recurrence of infections. Clinicians should be aware of potential iatrogenic nerve injuries when treating these patients with complicated cases, and an experienced surgeon may improve the outcome.

The Masquelet technique for septic arthritis of the small joint in the hands: Case reports

Septic arthritis in distal interphalangeal (DIP) joints sometimes occurs in association with mucous cysts or after the surgical treatment of mallet fingers. Recently, several studies have demonstrated the effectiveness of the Masquelet technique in the treatment of bone defects caused by trauma or infection. However, only few studies have reported the use of this technique for septic arthritis in small joints of the hand, and its effectiveness in treating septic arthritis in DIP joints remains unclear. We report the clinical and radiological outcomes of three patients who were treated with the Masquelet technique for septic arthritis in DIP joints. One patient had uncontrolled diabetes and another had rheumatoid arthritis treated with methotrexate and prednisolone. The first surgical stage involved thorough debridement of the infection site, including the middle and distal phalanx. We placed an external fixator from the middle to the distal phalanx and then packed the cavity of the DIP joint with antibiotic cement bead of polymethylmethacrylate (40 g) including 2 g of vancomycin and 200 mg of minocycline. At 4-6 weeks after the first surgical stage, the infection had cleared, and the second surgical stage was performed. The external fixator and cement bead were carefully removed while carefully preserving the surrounding osteo-induced membrane. The membrane was smooth and nonadherent to the cement block. In the second surgical stage, an autogenous bone graft was harvested from the iliac bone and inserted into the joint space, within the membrane. The bone graft, distal phalanx, and middle phalanx were fixed with Kirschner wires and/or a soft wire. Despite the high risk of infection, bone union was achieved in all patients without recurrence of infection. Although the Masquelet technique requires two surgeries, it can lead to favorable clinical and radiological outcomes for infected small joints of the hand.

[MagicTube: new possibilities for completely internal bone segmental transport and optional lengthening : New additional module for motorized lengthening nails for treatment of large bone defects]

Segmental bone transport is an effective method of treatment for segmental defects but the previous need for external fixation constructs during the transport phase is a great disadvantage, especially in the femur. In order to avoid external fixation, a new cylindrical combitube segmental transport (CKTST, MagicTube) module for combination with a commercially available motorized lengthening nail was developed by the author. This MagicTube module enables completely internal segmental bone transport and also enables optional lengthening if needed. The concept and surgical technique of MagicTube are described, illustrated, discussed and exemplified by clinical cases involving the tibia and femur.

Induced membrane maintains its osteogenic properties even when the second stage of Masquelet's technique is performed later

PURPOSE

Previous clinical studies have shown the effectiveness of bone repair using two-stage surgery called the induced membrane (IM) technique. The optimal wait before the second surgery is said to be 1 month. We have been successfully performing the IM technique while waiting an average of 6 months to carry out the second stage. We hypothesised that the IM maintains its beneficial capabilities, even at a later second stage, and that there is no relation between the speed of bone union and the wait between the first and second stage. We sought to explore the biological properties of 'older' IMs sampled to substantiate our clinical observations.

METHODS

Thirty-four patients with a critical size defect were treated with the IM technique. In seven of these patients, pieces of the IM were collected 4.2-14.7 months after the first surgery. IM-derived cell phenotype and osteogenic potential were investigated using in vitro studies (n = 4) while IM nature and function were investigated by histology and immunohistochemistry (n = 3).

RESULTS

The median wait before the second surgery was 5.8 months [range 1.2-14.7] and bone healing occurred at 7.6 months [range 2.5-49.9] for 26 patients. IMs aged 4.2-14.7 months contained mesenchymal stromal cells with in vitro osteogenic potential and corresponded to a multipotent tissue with osteogenic and chondrogenic capabilities contributing to osteogenesis over time.

CONCLUSION

This preliminary study suggests the IM retains its powerful osteogenic properties over time and that waiting longer between the two surgeries does not delay bone union.

Reconstruction of large segmental bone defects in rabbit using the Masquelet technique with α-calcium sulfate hemihydrate

Background

Large segmental bone defects can be repaired using the Masquelet technique in conjunction with autologous cancellous bone (ACB). However, ACB harvesting is severely restricted. α-calcium sulfate hemihydrate (α-CSH) is an outstanding bone substitute due to its easy availability, excellent biocompatibility, biodegradability, and osteoconductivity. However, the resorption rate of α-CSH is too fast to match the rate of new bone formation. The objective of this study was to investigate the bone repair capacity of the Masquelet technique in conjunction with isolated α-CSH or an α-CSH/ACB mix in a rabbit critical-sized defect model.

Methods

The rabbits (n = 28) were randomized into four groups: sham, isolated α-CSH, α-CSH/ACB mix, and isolated ACB group. A 15-mm critical-sized defect was established in the left radius, followed by filling with polymethyl methacrylate spacer. Six weeks after the first operation, the spacers were removed and the membranous tubes were grafted with isolated α-CSH, isolated ACB, α-CSH/ACB mix, or none. Twelve weeks later, the outcomes were evaluated by manual assessment, radiography, and spiral-CT. The histopathological and morphological changes were examined by H&E staining. The levels of alkaline phosphatase and osteocalcin were analyzed by immunohistochemistry and immunofluorescence staining.

Results

Our results suggest that the bone repair capacity of the α-CSH/ACB mix group was similar to the isolated ACB group, while the isolated α-CSH group was significantly decreased compared to the isolated ACB group.

Conclusion

These results highlighted a promising strategy in the healing of large segmental bone defect with the Masquelet technique in conjunction with an α-CSH/ACB mix (1:1, w/w) as they possessed the combined effects of sufficient supply and low resorption.

Induced-Membrane Technique in the Management of Posttraumatic Bone Defects

Background

Critical-size bone defects are defined as bone defects where spontaneous regeneration is not expected without treatment¹. The characteristics of bone defects (etiology, location, size, presence of infection, and soft-tissue conditions) vary greatly and, to be effective, the treatment method should address this variability. The induced-membrane technique, or Masquelet technique, is a method for treating critical-size bone defects^2,3 of various sizes and anatomic locations. It has been used to treat infected and noninfected bone defects and may be performed with a variety of fixation methods^2,3.

Description

The induced-membrane technique is a 2-stage procedure. The first stage consists of debridement followed by insertion of a polymethylmethacrylate (PMMA) spacer in the bone defect. The presence of the PMMA leads to a foreign-body reaction with the development of a thick pseudosynovial membrane that is extremely vascularized and rich in growth factors. The filling of the bone defect with the cement spacer prevents fibrous tissue invasion and allows the development of an optimal vascularized gap for bone-grafting. After 6 to 8 weeks, the membrane around the spacer is carefully opened for the removal of the spacer, which is then replaced by bone graft^2,3, which can be expanded with allograft or biomaterials.

Alternatives

Alternatives include vascularized or nonvascularized autologous bone graft, allograft, bone transport methods, titanium cages, megaprostheses, shortening, and amputation.

Rationale

Posttraumatic bone defects frequently are associated with soft-tissue injury and infection that impair the local vascularization and the healing potential. The highly vascularized induced membrane may play a role in restoring the local regenerative capacity. Numerous studies have demonstrated its successful use in the treatment of posttraumatic bone defects in the hand, forearm, humerus, femur, tibia, and foot. The induced-membrane technique is especially advantageous in the treatment of infected bone defects because the presence of the spacer helps in the treatment of the infection by reducing dead space, acting as a local antibiotic carrier, and promoting some degree of bone stability^3-5.

The use of free nonvascularized fibular graft in the induced membrane technique to manage post-traumatic bone defects

PURPOSE

The aim of the present study is to assess the results of free nonvascularized fibular graft in the induced membrane technique to manage bone defects.

MATERIALS AND METHODS

Fifteen patients with segmental skeletal defects were treated by the induced membrane technique using free nonvascularized fibular graft. The ages ranged from 20 to 48 years with an average of 32 years. The cause of the defects was post-traumatic bone loss in all cases. The defects were located in the distal femur in nine cases, proximal tibia in two cases and middle third of the tibia in four cases. The defects ranged from 5 to 14 cm with an average of 8 cm. All cases were treated by the induced membrane technique in two stages. Autogenous cancellous bone graft and free nonvascularized fibular graft were used to fill the defect in the second stage of surgery.

RESULTS

All cases healed without additional procedures after the second stage except in two cases. The time-to-bone union ranged from 4 to 13 months with an average of 7 months. After physiotherapy, all cases regained good range of ankle and knee movements except two cases. The complications included nonunion of the graft in two cases, deep wound infection in one case, and chronic pain along the iliac crest in one case. No cases were complicated by implant failure or refracture.

CONCLUSION

The use of free nonvascularised fibular graft in the induced membrane technique reduces the time of healing and improves the final outcome.

Calcium sulfate induced versus PMMA-induced membrane in a critical-sized femoral defect in a rat model

Aimed to investigate the characteristics of CS-induced membrane in comparison with the PMMA-induced membrane. Cellular components, histological changes, growth factor expressions of IL-6, VEGF, BMP-2, and TGF-β1 in the two induced membranes were compared at 2, 4, 6 and 8 weeks, respectively. We also compared the histological changes at the bone defects between CS and PMMA groups. The structural characteristics of induced membrane were similar between CS and PMMA. Endochondral ossification took place in the CS-induced membrane at 8 week. Levels of VEGF, BMP-2 and TGF-β1 in CS-induced membrane were insignificantly higher than those in PMMA-induced membrane at different time points. The expression of IL-6 was significantly higher in PMMA-induced membranes at 2nd week. In addition, osteogenic and neovascular activities of induced membranes increased with time and peaked at 6 weeks. CS promoted endochondral ossification at the broken ends of the bone defect than PMMA did. CS-induced membrane has a better capacity of generating VEGF, BMP-2 and TGF-β1.osteogenic and neovascular activities achieve highest level at 6 week. CS may have the potential to replace PMMA as a novel spacer in Masquelet technique.

Congenital pseudarthrosis of the clavicle treated by Masquelet technique

Congenital pseudarthrosis of the clavicle (CPC) is a very rare pathology of which over 200 cases have been reported. Usually discovered during the first months of life, CPC is characterised by a definitive bone defect in the middle third of the clavicle. Generally asymptomatic, the pseudarthrosis of the clavicle can cause aesthetic issues and functional symptoms indicating a surgical repair. Different reconstruction techniques have been reported with various complications. We present a 14-year-old boy diagnosed with CPC and concerned about the cosmetic aspect of a swelling of his right clavicle. We performed a two-stage surgical repair using the induced membrane technique described by Masquelet. A complete bone union has been obtained, and patient is satisfied with the cosmetic appearance. In our opinion, the Masquelet technique is a safe and reproducible procedure to treat CPC in high-risk older patients with long gap allowing a rapid and lasting bone union.

Staged reconstruction of diaphyseal fractures with segmental defects: Surgical and patient-reported outcomes

INTRODUCTION

Two-stage limb reconstruction is an option for patients with critical size segmental bone defects following acute trauma or non-union. Reconstruction is technically demanding and associated with a high complication rate. Current protocols for limb reconstruction have well-documented challenges, and no study has reported on patient outcomes using a validated questionnaire. In this study, we aimed to examine the clinical and patient-centered outcomes following our surgical protocol for two-stage limb reconstruction following critical size segmental defects.

PATIENTS AND METHODS

A single surgeon performed reconstruction of long bone defects using antibiotic impregnated cement spacers and intramedullary cancellous bone autograft. A retrospective chart review was performed. Three reviewers independently measured time to union based on radiographs. The Lower Extremity Functional Scale (LEFS) survey was administered to patients after most recent follow-up.

RESULTS

Ten limbs representing nine patients were included. All patients sustained a lower extremity injury, and one patient had bilateral lower extremity injuries. Average clinical follow-up was 18.3 months (range 7-33) from final surgical intervention, and follow-up to questionnaire administration was 28 months (range 24-37). The mean time between stages was 3.1 months. Average time to unrestricted weight-bearing was 7.9 months from Stage 1 (range 3.4-15.9) and 4.5 months from Stage 2 (range 1.1-11.6). Average time to full union was 16.7 months from Stage 1 (range 6.4-28.6) and 13.5 months from Stage 2 (range 1.8-27). Eight patients (nine limbs) participated in the LEFS survey, the average score was 53.1 (range 30-67), equating to 66% of full functionality (range 38%-84%). Complications included 5 infections, 3 non-unions, and one amputation. There was a moderate positive correlation between infection at any time point and non-union (R=0.65, p=0.03).

DISCUSSION AND CONCLUSIONS

Outcomes in this small patient cohort were good despite risks of complication. There is an association between infection and non-union. Further studies addressing clinical and functional outcomes will help to guide expectations for future surgeons and patients.

Circumferential bone grafting around an absorbable gelatin sponge core reduced the amount of grafted bone in the induced membrane technique for critical-size defects of long bones

OBJECTIVES

The objectives of the study were to introduce a circumferential bone graft around an absorbable gelatin sponge core using an induced membrane technique, to assess its ability to reduce the required amount of graft and to maintain the bone graft, and to evaluate the clinical outcomes in the management of critical-size bone defects.

PATIENTS AND METHODS

Circumferential bone grafting using a staged induced membrane technique for managing critical-size bone defects was performed in 21 patients. Postoperative computed tomography scans were performed 7days after Hemovac drain removal and 3 months after bone grafting. Volumetric measurements of the defect size, gelatin sponge proportion, and amount of grafted bone were performed by two independent observers using three-dimensional (3D) software.

RESULTS

The critical-size defects were located at the metadiaphyseal area of 11 tibias, eight femurs, and two humeri. The average defect size was 8.9cm in length and 65.2cm³ in volume. The absorbable gelatin sponge core replaced 21.4% (average) of the defect volume. There was no significant deterioration in the shape of the grafted bone among the serial 3D models. Eighteen patients (86%) were healed radiographically at 9.1 months (average).

CONCLUSION

Our study suggests that circumferential bone grafting in association with the induced membrane technique could reduce the required amount of bone graft and adequately maintain graft position and shape, with favourable clinical outcomes.

Bone union with an in situ spacer after the first stage of the induced membrane technique

INTRODUCTION

We report a case of an infected bone defect in the tibia in which the treatment was stopped in the first stage of the induced membrane technique. The polymethylmethacrylate (PMMA) spacer, retained in the bone defect, was encapsulated by the bone regeneration.

CASE REPORT

A 37-year-old male patient with a 7-cm infected bone defect in the tibia was submitted to the first stage of the induced membrane technique with debridement and implantation of a PMMA spacer with antibiotics. The patient refused the second stage of the procedure and achieved bone union with the spacer in situ. There was no recurrence of infection at the 6-year follow-up.

CONCLUSION

his is the first report of a case in which bone union was achieved with the spacer in situ after the first stage of the induced membrane technique. Keeping the spacer in the bone defect could be an option in some exceptional situations.

The Effect of Surgical Technique and Spacer Texture on Bone Regeneration: A Caprine Study Using the Masquelet Technique

BACKGROUND

The Masquelet-induced-membrane technique is a commonly used method for treating segmental bone defects. However, there are no established clinical standards for management of the induced membrane before grafting.

QUESTIONS/PURPOSES

Two clinically based theories were tested in a chronic caprine tibial defect model: (1) a textured spacer that increases the induced-membrane surface area will increase bone regeneration; and (2) surgical scraping to remove a thin tissue layer of the inner induced-membrane surface will enhance bone formation.

METHODS

Thirty-two skeletally mature female goats were assigned to four groups: smooth spacer with or without membrane scraping and textured spacer with or without membrane scraping. During an initial surgical procedure (unilateral, left tibia), a defect was created excising bone (5 cm), periosteum (9 cm), and muscle (10 g). Segments initially were stabilized with an intramedullary rod and an antibiotic-impregnated polymethylmethacrylate spacer with a smooth or textured surface. Four weeks later, the spacer was removed and the induced-membrane was either scraped or left intact before bone grafting. Bone formation was assessed using micro-CT (total bone volume in 2.5-cm central defect region) as the primary outcome; radiographs and histologic analysis as secondary outcomes, with the reviewer blinded to the treatment groups of the samples being assessed 12 weeks after grafting. All statistical tests were performed using a linear mixed effects model approach.

RESULTS

Micro-CT analysis showed greater bone formation in defects with scraped induced membrane (mean, 3034.5 mm³; median, 1928.0 mm³; quartile [Q]1-Q3, 273.3-2921.1 mm³) compared with defects with intact induced membrane (mean, 1709.5 mm³; median, 473.8 mm³; Q1-Q3, 132.2-1272.3 mm³; p = 0.034). There was no difference in bone formation between textured spacers (mean, 2405.5 mm³; median, 772.7 mm³; Q1-Q3, 195.9-2743.8 mm³) and smooth spacers (mean, 2473.2 mm³; median, 1143.6 mm³; Q1-Q3, 230.2-451.1 mm³; p = 0.917).

CONCLUSIONS

Scraping the induced-membrane surface to remove the innermost layer of the induced-membrane increased bone regeneration. A textured spacer that increased the induced-membrane surface area had no effect on bone regeneration.

CLINICAL RELEVANCE

Scraping the induced membrane during the second stage of the Masquelet technique may be a rapid and simple means of improving healing of segmental bone defects, which needs to be confirmed clinically.

Similarities between induced membrane and amniotic membrane: Novelty for bone repair

Previous clinical studies have shown the efficacy of a two-stage surgical procedure - the induced membrane (IM) technique - for reconstruction of large bone defects or bone non-union. The first stage involves radical debridement and insertion of a cement spacer into the bone defect. The second stage, performed weeks to months later, consists of removing the spacer while leaving the foreign body membrane induced by the cement in place, and then filling the cavity with bone autograft. The IM has been shown to (1) act as a protective physical barrier by preventing bone autograft resorption and (2) act as a bioreactor by promoting healing through revascularisation and growth factor secretion, and by concentrating mesenchymal stem cells (MSC) with osteogenic properties. New solutions to reduce this surgical procedure to a single step are being explored, for example by using an IM-like bioactive and protective barrier inserted into the bone defect at the same time as bone graft.

Outcomes of cement beads and cement spacers in the treatment of bone defects associated with post-traumatic osteomyelitis

Background

Cement spacers (Masquelet technique) have traditionally been used for the treatment of segmental bone defects. However, no reports have used cement spacers for the treatment of small/partial segmental bone defects associated with osteomyelitis and compared the outcomes with cement beads.

Methods

We retrospectively analysed 40 patients with post-traumatic osteomyelitis of the tibia who underwent treatment, which was performed in two stages. In the first stage, thorough debridement was performed, and bone defects were filled with either antibiotic-impregnated cement beads (bead group, 18 patients) or spacers (spacer group, 22 patients). In the second stage, the cement beads or spacers were removed (for the spacer group, the induced membrane formed by the spacer was preserved) and the bone defects were filled with cancellous autografts.

Results

All patients in the bead group had small/partial segmental bone defects after debridement, while 3 patients in the spacer group had large/segmental bone defects.

The mean volume of bone defects of the spacer group (40.4 cm³) was significantly larger than that of the bead group (32.4 cm³). The infection control rate (88.9%,16/18 vs 90.9%, 20/22), bone healing time (8.5 months vs 7.5 months) and complication rates (22.2%, 4/18 vs 27.2%, 6/22) were comparable between bead group and spacer group.

Conclusion

The results of this study suggest that cement spacers may have an infection control rate comparable to cement beads in the treatment of bone defects associated with post-traumatic osteomyelitis. Furthermore, cement spacers could be used for the reconstruction of small/partial segmental bone defects as well as for large/segmental bone defects, whereas cement beads were not suitable for the reconstruction of large/segmental bone defects.

Factors associated with adverse postoperative outcomes in patients with long bone post-traumatic osteomyelitis

AIMS

To evaluate short-term clinical and functional outcomes following operative treatment of long bone post-traumatic osteomyelitis (PTOM).

METHODS

We retrospectively analyzed a consecutive cohort of 142 adult patients undergoing operative treatment of long bone PTOM at our Level I trauma center over a 10-year study period. In addition to subjective patient evaluations, surveyed postoperative outcomes included incidence of residual infection, fracture malunion or nonunion, and requirement for limb amputation. All included patients had a minimum follow-up of 12 months postoperatively.

RESULTS

Patients suffering an adverse postoperative outcome tended to have a higher incidence of polymicrobial infection (25.4 vs. 11.4%, p = 0.042) and requirement for skin grafting (58.1 vs. 37.9%, p = 0.024) and free-flap procedures (43.6 vs. 19.5%, p = 0.003) compared to those achieving complete healing. Sequential administration of parenteral and oral antibiotic therapies was associated with a reduced incidence of adverse postoperative outcome (p = 0.047).

DISCUSSION

Patients with long bone PTOM and extensive soft tissue defects often fail to develop complete remission of their symptoms by 12 months postoperatively. Sequential administration of parenteral and oral antibiotics may help to limit infection recurrence. Further research is required to inform optimal treatment strategy.

Role of Systemic and Local Antibiotics in the Treatment of Open Fractures

The orthopedic community has learned much about the treatment of open fractures from the tremendous work of Ramon Gustilo, Michael Patzakis, and others; however, open fractures continue to be very difficult challenges. Type III open fractures continue to be associated with high infection rates. Some combination of systemic and local antibiotics may be most appropriate in these high-grade open fractures. Further research is still necessary in determining optimal systemic antibiotic regimens as well as the role of local antibiotics. Any new discoveries related to novel systemic antibiotics or local antibiotic carriers will need to be evaluated related to cost.

Challenges of bone tissue engineering in orthopaedic patients

Bone defects may impede normal biomechanics and the structural stability of bone as an organ. In many cases, the correction of bone defects requires extensive surgical intervention involving the use of bone-grafting techniques and other procedures in which healing is slow, there is a high risk of infection and considerable pain is provoked - with no guarantee of complete correction of the defect. Therefore, the search for surgical alternatives continues to present a major challenge in orthopaedic traumatology. The reamer-irrigator-aspirator (RIA) system, which was devised to avoid the problems that can arise with autograft harvesting from the iliac crest, consists of collecting the product of the femoral canal after reaming. The RIA technique improves osteogenic differentiation of mesenchymal stem cells, compared to bone marrow aspiration or cancellous bone harvesting from the iliac crest using a spoon. Another approach, the Masquelet technique, consists of reconstructing a long bone defect by means of an induced membrane grown onto an acrylic cement rod inserted to fill the defect; in a second surgical step, once the membrane is constituted, the cement rod is removed and cancellous autograft is used to fill the defect. Both in RIA and in the Masquelet technique, osteosynthesis is usually needed. Bone transportation by compression-distraction lengthening principles is commonly implemented for the treatment of large bone loss. However, complications are frequently encountered with these techniques. Among new techniques that have been proposed to address the problem of large bone loss, the application of stem cells in conjunction with tissue engineering techniques is very promising, as is the creation of personalised medicine (or precision medicine), in which molecular profiling technologies are used to tailor the therapeutic strategy, to ensure the right method is applied for the right person at the right time, after determining the predisposition to disease among the general population. All of the above techniques for addressing bone defects are discussed in this paper.

Two stage management of Cierny-Mader type IV chronic osteomyelitis of the long bones

INTRODUCTION

Cierny-Mader (C-M) type IV chronic osteomyelitis represents a complex clinical challenge with permeation of extensive bone and soft tissue involvement. Aggressive debridement through viable tissue margin includes en bloc resection improves the odds of eradication of infection, which creates large bone and soft tissue loss in treating this type of osteomyelitis. The potentially large defects increase reconstruction problems with traditional reconstruction technique. The newly staged induced membrane technique presents length-independent, potential as an alternative reconstruction method for segmental bone defects due to type IV chronic osteomyelitis. The purpose of this study was to assess the result and related factors of C-M type IV chronic osteomyelitis treated with staged methods of aggressive debridement and induced membrane technique.

METHODS

From January 2012 to January 2014, 36 consecutive adult patients of C-M type IV chronic osteomyelitis were treated by this staged method in our clinical center with a minimum of 2-years follow-up. The clinical and imaging results were retrospectively analyzed.

RESULTS

Five patients had a second debridement and eight needed a local flap transfer to cover the wound in the first stage. Patients formed a mean of 5.5cm (range: 2-10.9) segmental bone defect; Sixteen patients had autograft and twenty had autograft mixed allograft in the second stage. The mean follow-up time was 29.5 months (range: 24-45). No patients required amputation. Bone union was achieved in all patients. Clinical eradication of osteomyelitis was achieved in 35 (97%) patients, 35 (97%) patients were able to walk independently, and 31patients (86%) returned to work. Patients returned to a mean of 82% (46.3%-100%) lower extremity function. Bone union time was not dependent on the length of bone defect, but associated with the infection site (p=0.005) and age (p=0.005).

CONCLUSIONS

Staged methods of aggressive debridement and induced membrane technique seems to be a simple, reliable and effective for the treatment of C-M type IV chronic osteomyelitis. Advanced age and poor soft tissue envelope may have adverse affects and are relative contraindications. The combined assessment and management of such patients with a plastic surgeon are advocated.

Antibiotic cement-coated locking plate as a temporary internal fixator for femoral osteomyelitis defects

PURPOSE

Recently we modified the Masquelet technique by using an antibiotic cement-coated locking plate as a temporary internal fixator when treating septic bone defects. This modification is in order to prevent the complications related to external fixator use and provides the involved limb with a greater stability to undergo earlier and more vigorous physical therapy for recovery of joint function. The purpose of this study was to assess the outcomes of large femoral osteomyelitis defects managed by Masquelet technique combined with the antibiotic cement-coated locking plate used as a temporary internal fixator.

METHODS

Between November 2013 to November 2014, 13 cases of large femoral osteomyelitis defects were treated by Masquelet technique and the antibiotic cement-coated locking plate was used as a temporary internal fixator in the first stage surgery. All the patients' clinical and imaging results were retrospectively analyzed.

RESULTS

After debridement, there was a femoral bone defect with a mean of 9.8 cm (range, 5-16 cm). The mean follow-up was 17.8 months (range 12 to 24 months). One patient developed infection in nine months after second stage surgery. Radiographic bony union was achieved within a mean 20.3 weeks (range, 18-30 weeks) in all patients. The mean time period to full weight bearing after the second step procedure was 5.8 months (range, 5-8.5 months). The mean knee range of motion for the patients at the last follow up was 122° (range 100-135°).

CONCLUSION

Based on our experience, we believe that antibiotic cement-coated locking plate is a viable fixation method in the first stage of Masquelet technique for the management of large femoral osteomyelitis defects. It may offer a better chance of infection eradication as well as improved recovery of joint function without increasing the infection recurrence rate and without compromising bone graft union.

Short-term Outcomes of Induced Membrane Technique in Treatment of Long Bone Defects in Iran

Introduction:

Severe defects in long bones can be caused by several factors such as trauma that lead to open wound and secondary infections after surgery. Induced membrane technique is one of the therapeutic strategies that can be used for these patients. Due to importance of this method and lack of information about this technique in Iran.

Aim:

this study was performed to investigate technical strengths and weakness of induced membrane technique.

Material and Methods:

This case series study conducted on 21 patients with bone defects in the femur and tibia and metatarsal bones referred to orthopedic clinic of Rasoul Akram Hospital, Tehran, Iran, for induced membrane surgery in 2012-2015. Demographic and clinical data were obtained using history, clinical examinations and observations for each patient. Union achievement was the main outcome of this study, which was confirmed by radiographic findings and physical examination. Obtained data was analyzed by SPSS ver. 16.

Results:

All patients were male except one and their mean age was 30.52 years old. Bone defects were in tibia, femur and metatarsus in 9, 9 and 3 patients, respectively. Three patients received soft tissue reconstruction with flap before induced membrane surgery. Age, defects size, cigarette addiction and drug use and delay to start the treatment had no significant effect on union status. In total, 90% of patients had successful surgery.

Conclusion:

using induced membrane technique in patients with defects in their long bone such as tibia, femur and metatarsus would lead to high success for reconstruction.

The role of biofilm on orthopaedic implants: the "Holy Grail" of post-traumatic infection management?

The development of post-traumatic infection is potentially a limb threatening condition. The orthopaedic trauma literature lags behind the research performed by our arthroplasty colleagues on the topic of implant-related infections. Surgical site infections in the setting of a recent ORIF are notoriously hard to eradicate due to biofilm formation around the implant. This bacteria-friendly, dynamic, living pluri-organism structure has the ability to morph and adapt to virtually any environment with the aim to maintain the causative organism alive. The challenges are twofold: establishing an accurate diagnosis with speciation/sensitivity and eradicating the infection. Multiple strategies have been researched to improve diagnostic accuracy, to prevent biofilm formation on orthopaedic implants, to mobilize/detach or weaken the biofilm or to target specifically bacteria embedded in the biofilm. The purpose of our paper is to review the patho-physiology of this mysterious pluri-cellular structure and to summarize some of the most pertinent research performed to improve diagnostic and treatment strategies in biofilm-related infections.