Advantage of antibiotic cement-coated interlocking intramedullary nail (tibia nail/femur nail) over conventionally used antibiotic cement-coated Kuntscher nail in infected nonunion

Introduction

Infection of long bones during its process of fracture healing becomes very challenging for surgeon. Co-morbid condition such as diabetes, smoking, chronic NSAIDS futher worse the situation and limb threatening problem to patients. Almost orthopedic infections usually caused by proctative layer (biofilm) forming bacteria. These infection very difficult to treat because these are impermeable to immune system and antimicrobial agent and contribute to chronic infection. Throughout debridement of nacrotic tissue and removing of fibrous tissue also helps in increase vascularity and increase antibiotic delivery at fracture site. High delivery of antibiotic concentration through antibiotic cement coated intramedullary nail at help in eradication of infection and convert into aseptic condition. Immbolisation of fracture with intramedullary nail promote the fracture healing.

Traditionally, The use of an antibiotic cement-impregnated intramedullary nailing (K-nail) for infected nonunion of tibia and femur fractures has been used for decade.1, 2, 3, 4 this very effective single-stage procedure for treating infected non-union and have been widely used. This procedure has many limitation in terms of stability and has significant complications like bending of nail, broken nail, migration in joint space. The antibiotic coated interlocking intramedullary nail fills in the dead space, provides a high concentration of antibiotics locally without any significance systemic side effect locally, and gives good mechanical as well as axial and rotational stability.1, 2, 3, 4 However; this studies have used two groups of patients (one with antibiotic cement coated K nail and another with antibiotic cement coated interlocking intramedullary nail) cases without significant bone defect. The present study was undertaken to analyze the advantage of antibiotic cement coated interlocking intramedullary nail over conventionally use of antibiotic coated k-nail in cases of infected non-union in aspect of controlling infection and achieving fracture union in long bone and associated complications.

Materials and Methods

There are 20 patients (of established infected nonunion without significant bone loss) included in our study and all treated with intramedullary antibiotic cement coated nail, devided according to implant used. Group A were treated using antibiotic cement-coated nail (interlocking intramedullay nail) in cases of primarily infected fracture without bone defect. Group B patients are treated with intramedullary antibiotic mixed cement coated K-nail without bone loss.

Operative procedure

After investigation, and radiologically assessment of fracture nonunion patients were posted for surgery. Initially throughout radical debriment of infected necrotic tissue and fibrous tissue removed and sample collected for culture and sensitivity. The intramedullary canal was reamed to size 1 mm more than the prepared antibiotic cement coating nail.

The wound and the entire reamed medullary canal were irrigated with hydrogen peroxide + betadine+ normal saline and lavage of about 1-2 L of normal saline.

The recommended mix ratio of antibiotic to bone cement We used was 4 g of vancomycin and 3 g of clindamycin mixed with every 40 g of bone cement.5 Manual mixing and application of the cement was done in a uniform smooth layer excluding the interlocking site to facilitate screw fixation of the nail and the eye to facilitate easy removal later in k-nail. Size of implant was decided according to the length of long bone.

For group A the diameter of interlocking nail is selected as thinner as possible to accommodate 1mm of antibiotic cement coating over it. For femur, we used 9mm diameter and for tibia it was 8mm in diameter. The smooth surface of nail has been roughed with sterile sand papper Before coating with antibiotic mixed cement over the nail to prevent debonding of cement during insertion. The excess cement over the locking hole is removed before it set. The cement coating done separately on sterile table. It is inserted anterograde manually with the help of zig over the guide wire. Insertion of the nail was guided by guide wire with easy.

Group B for this group of patient 6mm or 7mm of diameter k-nail is selected for the antibiotic mixed cement coating over it. The k-nail was directly inserted anterograde manually with precaution as no guiding wire can be use.

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K-Nail is clover shaped so cement debonding during insertion is not a common complication in this. However it was avoided by allowing adequate time for the cement to set and gently anterograde insertion without rotatory movement. Wound closure done in layers.

Anteroposterior and lateral radiographs were taken during procedure and thereafter following procedures.

All patients were administered 4–6 weeks of antibiotics.

Control of Infection was monitored by wound discharge, clinical signs of inflammation, and laboratory investigation such as Complete blood count, ESR, and C Reactive protein. Postoperatively regularly dressing and physiotherapy to regain the knee and ankle joint mobility. Bony union assess at 4 weeks of interval by until radiological and clinical sign of union appear.

Result

There were total 20 cases of established infected nonunion involved in our study for treatment for antibiotic cement coated intramedullary nail (either K-nail or interlocking Nail). The preoperative and intraoperative specimen of pus and soft tissue showed positive culture for Staphylococcus aureus in all 19 cases, one samples were positive for Klebsiella. All the patients achieved infection control with normal laboratory parameters and no active discharge in an average of 6 weeks (5-8 week). All patient divided into two group as per type of intramedullary nail used.

Group B

In this group there 7 patients achieved infection control by 6.5 weeks. 1 patient required additional procedure. Clinical and radiological bony union achieved in 5 patients with the average time to union being 8 months (range, 7–11 months) for this group.

Remaining 3 cases required bone grafting, bone marrow infiltration.

The complication in this group reported are 1 patient report bending and broken k-nail, one patient reported bending of k-nail, one reported migration into adjacent joint difficult nail removal seen in three patients, which may be attributed to improper nail preparation and late presentation to hospital and finally k-nail removed with corticotomy.

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Discussion

Infection over long bone fractures not only retard the fracture healing but also increase morbidity and functional disability of patients. Which leads to delay the union or sometime completely abort the fracture healing process. In such cases it require the procedure to provide stability along with controling infection to achieve union.6 Traditionally multistep approach is widely used to deal the infected nonunion, first step to cure the infection along with or without external fixator. After controlling the infection nonunion is treat with internal fixation with without bone grafting. Which causes a significant morbidity and increases the hospital stay and economical loss. Using an antibiotic mixed cement coated interlocking intramedullary nail instead of conventionally used antibiotic coated K-nail for infected nonunion not only control the infection but also provide the rotational & axial stability to enhance the bony union and it has less complication compare to antibiotic-cement coated k-nail such as difficulty in removal, bending, migration into adjacent joint, prone to broken. Easy removal after fitting with conical bolt provide great advantage for antibiotic mixed cement coated interlocking intramedullary nail (tibia/femur nail) compare to k-nail as it can bend insitu rotate, migrate into medullary canal and which make it difficult to locate the eye for removal.

Surgical debridement of necrotic tissue and higher concentration of antibiotic either locally very effective to eradicate the infection.6

This method of local delivery of antibiotics also used in many condition related to chronic bone infection and open fracture.7 PMMA cement is the most commonly used and also a cost-effective antibiotics delivery material. After being mixed into the PMMA cement and coated over implant, these antibiotics are steadily released from the cement’s surface and from cracks and voids in the cement8 results in high local concentration of antibiotic with minimum systemic toxicity.6

The selected antibiotics are should have a broad spectrum of activity, heat stable with good elution properties from the cement and should have low allergenicity. Many previous study in the past used a combination of vancomycin with gentamicin or tobramycin. In our study, we used a combination of vancomycin and clindamycin as most of the culture and sensitivity reports from the patients at our center were reporting S. aureus.

Wider surface area of elution allows for high antibiotic concentration along entire length of the bone. This is essential as necrotic and avascular segments are impermeable to systemic parenteral antibiotic therapy. There is a high local concentration of antibiotic even in the presence of extensive scarring and compromised vascularity. Patients with elevated renal parameters can be treated with effective concentration of antibiotic without side effects.9

Other conventionally used external fixator or Ilizarov is cumbersome and very poor patient compliance. Patient compliance is found poor with this method as in external fixator or Ilizarov the apparatus is bulky and prone for pin-tract infection. For this, regular follow-up is cumbersome for a patient with external fixator. In patients with ACIIN Postoperative morbidity is less due to early passive mobilization of the limb, and it essentially helps in early rehabilitation.10

Conclusions

ACIINs is a good procedure to achieve early infection control, provide stability, and bone union with single-stage procedure in infected long bone fractures without bone gap.

In group A, infection was controlled in all cases. Bony union achieved in 10out of 12 cases (83%). Rest 2 cases required further additional procedures such as bone marrow infiltration, plasma-rich protein infiltration, or bone grafting, exchange nailing. Recurrence of infection occurred in two cases. Average time to union being 8 months (range, 6–11 months) for this group.

In group B all patients achieved infection control. Clinical bony union achieved in 5 patients with the average time to union being 8.5 months (range, 7–11 months) for this group.

Source of Funding

None.

Conflict of Interest

None.