Antibiotic Cement-Coated Nails for the Treatment of Infected Nonunions and Segmental Bone Defects

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1 This is an enhanced PDF from The Journal of Bone and Joint Surgery The PDF of the article you requested follows this cover page. Antibiotic Cement-Coated Nails for the Treatment of Infected Nonunions and Segmental Bone Defects Raghuram Thonse and Janet D. Conway J Bone Joint Surg Am. 2008;90: doi: /jbjs.h This information is current as of December 20, 2008 Reprints and Permissions Publisher Information Click here to order reprints or request permission to use material from this article, or locate the article citation on jbjs.org and click on the [Reprints and Permissions] link. The Journal of Bone and Joint Surgery 20 Pickering Street, Needham, MA

2 163 COPYRIGHT 2008 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Antibiotic Cement-Coated Nails for the Treatment of Infected Nonunions and Segmental Bone Defects By Raghuram Thonse, MS(Orth), DNB(Orth), FRCS(Glasg), FRCS(Ed), and Janet D. Conway, MD Introduction Treatment of infected nonunions is a challenge faced by many orthopaedic surgeons. Traditionally, the treatment strategy has been control of the infection followed by procedures to achieve osseous union. Débridement, antibiotic-impregnated cement beads, and intravenous antibiotics have been used for the control of the infection 1-3. External or internal fixation methods have been used to achieve stability to promote union. Antibiotic cement-coated intramedullary nails can be used to treat the infection with high doses of local antibiotics and to provide bone stability 4. Use of these devices allows immediate weight-bearing and prevents many complications associated with external fixation, such as pintrack infections and joint stiffness. This novel approach to the treatment of infected nonunions was developed to minimize the number of additional surgical procedures required for infection control and to achieve bone union. We present our series of fifty-two patients in whom an antibiotic cement-coated intramedullary nail was inserted for the treatment of an infected nonunion or segmental bone defect. Materials and Methods Preoperative Planning areful preoperative planning is essential. It is essential to C determine if the patient has a history of allergy to antibiotics so that those antibiotics are not used when mixing the bone cement. The evaluation of intraoperative culture and sensitivity results guides the selection of the appropriate postoperative intravenous antibiotics. Preoperative radiographs, including anteroposterior and lateral views of the involved bone and full-length standing anteroposterior views of both lower extremities made with a 130-cm cassette, should be evaluated. This evaluation allows the surgeon to determine the size of the intramedullary nail that should be used and also provides information regarding the need for additional procedures (such as deformity correction). The length of the intramedullary nail is determined with the same standard method as is used to determine the length of an interlocking nail. For example, when antegrade nailing of the femur is performed, the nail s length should be the same as the distance from the piriformis fossa to the distal femoral physeal scar. Proper preoperative planning allows the surgeon to prepare the antibiotic cement-coated nail while the other members of the operating team prepare the patient for surgery. The cement coating on the nail can then harden on the clean back table while the surgeon performs a thorough débridement of the infected bone and the soft tissues followed by copious lavage. Once débridement is complete, the instruments that were used for the dirty portion of the procedure are removed and the patient s limb is prepared again and draped. The surgeon and the rest of the operating team change all gowns and gloves. The clean portion of the procedure then begins, usually by the surgeon inserting the antibiotic cement-coated nail. Two methods have been used to prepare the antibiotic cement-coated intramedullary nails. Initially, the antibiotic cement-coated nails were prepared with a reusable mold (the mold technique, or Method 1). The second generation of antibiotic cement-coated nails was prepared with use of disposable silicone tubing (the silicone tubing technique, or Method 2). The intraoperative time required to prepare a nail with use of Method 2 is approximately ten minutes, which is substantially less than the time required to prepare a nail with Method 1 (one hour). Additional advantages of Method 2 include the uniformity and improved reliability of the coating. There have been no instances of insertional debonding of nails made with Method 2. All antibiotic cement-coated nails were made with use of the same antibiotic combination of 3.6 g of tobramycin and 1 g of vancomycin per 40-g package of cement, except for two patients who had a history of allergy to vancomycin. Extra monomer (3 to 4 ml) was necessary for mixing the large Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits of less than $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Quantum Medical Concepts). No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated. J Bone Joint Surg Am. 2008;90 Suppl 4: doi: /jbjs.h.00753

3 Thonse.fm Page 164 Wednesday, October 15, :52 PM 164 THE JOURNAL BONE & JOINT SURGER Y JBJS.ORG VO L U M E 90-A S U P P L E M E N T OF A N T I B I O T I C C E M E N T -C O A T E D N A I L S F O R T H E TR E A T M E N T OF IN FE C TED NONU N IONS A N D S E G M EN T A L B ONE DEF EC T S Fig. 1-A Fig. 1-B Fig. 1-C Fig. 1-D Fig. 1-E Fig. 1-F Figs. 1-A through 1-K The mold technique (Method 1). Figs. 1-A and 1-B Molds are coated with sterile ultrasound gel. Figs. 1-C and 1-D Cement powder is sprinkled over the ultrasound gel, and excess powder is removed. Figs. 1-E and 1-F Powdered antibiotics and cement powder are mixed with monomer in a cement gun until the mixture is homogeneous. The cement gun is used to apply the antibiotic-impregnated cement to both sides of the mold. The nail is then inserted into one of the molds.

4 165 Fig. 1-G The mold is closed carefully while ensuring that the nail is still centered in it. The insertion threads of the proximal part of the nail are kept free of cement by placing the insertion bolt into the proximal nail threads. quantity of antibiotics with the cement. Commercially available interlocking nails, including femoral (antegrade or retrograde), knee arthrodesis, tibial, and ankle arthrodesis nails, were selected for the specific condition of each patient. Molds were used to provide a uniform 1-mm-thick cement mantle circumferentially around the intramedullary nail, starting from just distal to the proximal interlocking holes and extending to the tip of the nail. Molds composed entirely of stainless steel were obtained from Biomet (Warsaw, Indiana). All mold sizes accommodated an increase in nail diameter of 2 mm. The mold templates were 12 mm in width for the knee arthrodesis, tibial, and ankle arthrodesis nails. The femoral mold was 14 mm in diameter to accommodate a 12- mm-diameter nail. Method 1 (Mold Technique) The antibiotic cement-coated nail is prepared on a sterile table (Figs. 1-A through 1-K). A thin layer of sterile ultrasound gel (AQUAGEL; Parker Laboratories, Fairfield, New Jersey) is smeared on the mold. We used Surgilube (Fougera, Melville, New York) for the initial cases, but it caused pitting of the cement surface. Dry cement powder is sprinkled over the coated mold, and the excess cement powder is shaken off the mold. In all cases in which Method 1 was used, a 12 by 36-cm mold was used to coat a 10-mm-diameter tibial nail, a 14 by 42-cm mold was used to coat a 12-mm-diameter femoral nail (either antegrade or retrograde), a 12 by 75-cm mold was used to coat a 10-mm-diameter knee arthrodesis nail, and a 12 by 24-cm mold was used to coat a 10-mm-diameter ankle arthrodesis nail. All femoral nails and knee arthrodesis nails and some tibial nails were manufactured by Biomet. TriGen intramedullary nails (Smith and Nephew, Memphis, Tennessee) were also coated with the use of the tibial mold. The decision to use a TriGen intramedullary nail instead of a Biomet intramedullary nail was based on the proximal triplanar locking pattern and matte finish of the TriGen nail. Two packages of cement are required for ankle arthrodesis, femoral, and tibial nails, whereas knee arthrodesis nails require as many as three packages. The antibiotics are mixed with the cement powder. The vacuum cement mixer is used to mix the cement powder containing antibiotics with the cement liquid. Often, extra monomer (3 to 4 ml) is needed to allow adequate mixing of the Palacos bone cement (Zimmer, Warsaw, Indiana) with the antibiotic powder. The Palacos cement is mixed in a standard fashion with use of a vacuum mixing technique. The nozzle of the cement gun is used to insert the antibiotic-impregnated bone cement into the slots of the molds. The interlocking nail selected for the patient is carefully placed into one of the slots. The second mold is placed over the first mold, and the two are gently pressed together while Fig. 1-H Fig. 1-I Figs. 1-H and 1-I The mold is opened carefully and excess cement is removed with an osteotome.

5 166 TABLE I Demographic Characteristics of Patients Treated with an Antibiotic Cement-Coated Nail Mold Technique (Method 1) Silicone Tubing Technique (Method 2) No. of patients (M, F) 32 (23, 9) 20 (17, 3) Mean age (range) (yr) 46.5 (16-86) 45.7 (19-80) Host status 5 (no. of patients) A 8 6 B Mean duration of follow-up (range) (mo) 22.5 (2-60) 4.5 (1-12) Type of bone involvement (no.) Nonunion Segmental bone defect 15 (avg. size, 8.63 cm; range, 1-30 cm) 2 (sizes, 6 cm and 1.5 cm) Acute fracture after external fixation 1 the cement is allowed to set. Before the nail is placed in the mold, the threaded bolt of the interlocking nail insertion jig should be inserted into the proximal end of the nail to prevent inadvertent coating of the threads on the inside of the proximal part of the intramedullary nail. In the initial cases, an attempt was made to keep the interlocking holes free of cement by placing screw-sized pins into the holes and through the mold. It later became clear that this was not necessary and could affect the uniformity of the cement mantle. Currently, the cement is allowed to fill the interlocking holes, which are subsequently drilled during insertion of the locking screws into the nail as if one were inserting a normal locking screw. After the cement has set, the two parts of the mold and the antibiotic cement-coated nail are separated with the gentle use of osteotomes. A file is used on the cement to create a bullet-shaped tip. If there is an area of spotty coverage, newly prepared antibiotic-impregnated cement is used to cover this area. Method 2 (Silicone Tubing Technique) This method of preparation of the antibiotic cement-coated nail involves the use of disposable silicone tubing (Quantum Medical Concepts, Portland, Oregon). The antibiotic-impregnated cement is prepared as it is in Method 1. The nozzle of the cement gun is used to insert the cement into the silicone tubing (with a 12.5-mm inner diameter), filling its entire length (Fig. 2-A). Then the interlocking nail is inserted into the silicone tubing. The tube with the nail inside is gently rolled on the sterile preparation table to ensure a uniform cement mantle (Fig. 2-B). After the cement has set, the silicone tube is split longitudinally with a sharp knife (Fig. 2-C), and the antibiotic cement-coated nail is removed. Excess cement that is present beyond the tip of the nail is removed with use of an osteotome, and the tip is filed to a smooth bullet shape as it is in Method 1. Insertion of the Nail The insertion technique is similar to that for an interlocking Fig. 1-J Fig. 1-K Figs. 1-J and 1-K The tip is filed to a bullet shape for ease of insertion, and the nail is mounted on the insertion jig. The antibiotic cement-coated nail is ready for insertion.

6 167 surgery. If removal of an antibiotic cement-coated nail is indicated, it is performed in a standard fashion with care taken to prevent cement-nail debonding. If debonding occurs, the cement mantle can be removed with reasonable ease by using a J-hook from the revision cemented total hip arthroplasty instrument set (Moreland Cemented Instruments; DePuy Orthopaedics, Warsaw, Indiana). Use of an image intensifier greatly facilitates this process. Tips for Preparation and Insertion of the Antibiotic Cement-Coated Nail 1. Overream the medullary canal of the bone by 2 mm (the intramedullary nail diameter plus an additional 2 mm for the cement coating plus 2 mm) for ease of insertion. Fig. 2-A Figs. 2-A, 2-B, and 2-C The silicone tubing technique (Method 2). Fig. 2-A After the cement is mixed as it is in Method 1, the cement gun is used to insert the cement into silicone tubing that has a 12.5-mm inner diameter. nail. The medullary canal of the bone is reamed to a diameter that is at least 2 mm greater than the diameter of the antibiotic cement-coated nail. One millimeter of cement coating is provided around the nail; therefore, the final diameter of the antibiotic cement-coated nail is 2 mm larger than that of the intramedullary nail. For example, after a 10-mm-diameter nail is coated with cement, it will have a total diameter of 12 mm and the canal will be reamed to 14 mm. The antibiotic cement-coated nail is mounted on the insertion jig that is provided with the interlocking-nail instrumentation. The guidewire used for reaming is removed. The antibiotic cement-coated nail is inserted in the same manner as is employed for unreamed nailing. The cement occludes the cannulated portion of the intramedullary nail, preventing its insertion over a guidewire, and it is inserted with use of a combination of direct inspection, palpation, and intraoperative fluoroscopy. Proximal locking is performed with the help of the insertion guide of the interlocking nail. Distal locking is performed with a freehand technique and use of image intensification. The cement might separate from the intramedullary nail (i.e., there might be cement-nail debonding) during its insertion. Proper preparation of the canal, including overreaming, can prevent this. If debonding does occur, it can be dealt with by removing the nail and the cement and preparing a new antibiotic cement-coated nail. Removal of the Nail The antibiotic cement-coated nail can remain in the medullary canal indefinitely after the dual goals of control of the infection and union have been achieved. If both infection and nonunion persist, the nail is exchanged for another antibiotic cement-coated nail, generally six to eight weeks after the index Fig. 2-B An intramedullary nail is inserted into the silicone tubing and rolled carefully in the tubing to ensure a uniform coating. Fig. 2-C The silicone tubing is cut and peeled off. The antibiotic cement-coated nail is mounted on the insertion jig and is ready for insertion.

7 168 TABLE II Types of Intramedullary Nails Used to Create Antibiotic Cement-Coated Nails No. of Nails Type of Intramedullary Nail Mold Technique (Method 1) Silicone Tubing Technique (Method 2) Total Ankle arthrodesis nail Tibial nail Femoral antegrade nail Knee arthrodesis nail Femoral retrograde nail Fig. 3-B Fig. 3-A Fig. 3-A Anteroposterior radiograph of a twenty-five-year-old man who sustained a Grade-IIIB 28 femoral fracture in a motor-vehicle collision. He was treated with a rotational flap and split-thickness skin graft. Infection and nonunion of the left femur developed. Fig. 3-B Lateral (left) and anteroposterior (right) radiographs made before the index operation.

8 While preparing the antibiotic cement-coated nail, maintain a low room temperature to allow more working time. 3. Do not forget to add additional monomer when combining large quantities of antibiotic powder with cement. 4. Do not use Surgilube in place of ultrasound gel. It causes pitting in the cement coating. 5. Use the bolt from the insertion device while preparing the antibiotic cement-coated nail to prevent cement from clogging the insertion threads. 6. Do not ream out interlocking holes before insertion of the antibiotic cement-coated nail; the cement mantle might fragment. This does not occur when the interlocking holes are drilled after the insertion of the antibiotic cement-coated nail inside the bone. Tips for Removal of the Antibiotic Cement-Coated Nail 1. If cement debonds during removal, the J-hook from the arthroplasty cement-removal set is the most effective instrument for removal of the cement. 2. If initial attempts to remove residual cement with the arthroplasty cement-removal instruments have failed, the cement can be removed with sequential reaming and Fig. 3-C Anteroposterior (left) and lateral (right) radiographs made immediately after the surgery. At the time of surgery, the medial bridge had healed but tissue suspicious for infection was noted. Before the surgical site was opened, a Reamer/Irrigator/Aspirator System (Synthes USA, West Chester, Pennsylvania) was used to harvest bone graft. An antibiotic cement-coated nail was inserted, and antibiotics and bone morphogenetic protein-2 (BMP-2) were added to the bone graft.

9 170 subsequent copious irrigation of the canal with use of canaltip pulsed lavage. 3. A distal vent hole or channel is often necessary to completely remove all retained cement if one must resort to reaming the cement coating. Results fter receiving approval by our institutional review board, Awe performed a retrospective study of fifty-two (twelve female and forty male) patients who had undergone treatment with an antibiotic cement-coated nail between 2002 and Thirty-four infected nonunions or arthrodesis sites and seventeen infected segmental bone defects were treated. One patient had an acute fracture that was initially treated with external fixation. The initial cause of the nonunion and infection in these patients was trauma (Figs. 3-A through 3-D), chronic osteomyelitis, chronic infection after total knee arthroplasty, and infection in an ankle with Charcot arthropathy. The average patient age was 46.2 years (range, sixteen to eighty-six years). According to the clinical staging system described by Cierny et al. 5, fourteen patients had a host status of A and thirty-eight patients had a host status of B. The demographic characteristics of the patients treated by the two methods are shown in Table I. The average duration of follow-up was 22.5 months for the patients treated with Method 1, 4.5 months for those treated with Method 2, and 15.6 months (range, one to sixty months) for the combined groups. The interlocking nail that was used depended on the anatomic site. The types used most often were ankle and knee arthrodesis nails (Table II). The most common isolated organism was methicillin-resistant Staphylococcus aureus. Multiple organisms were isolated from a large number of patients (Table III). Two of the fifty-two patients were lost to follow-up, and Fig. 3-D Postoperative anteroposterior (left) and lateral (right) radiographs. The infection was eradicated, and the bone has healed.

10 171 TABLE III Isolated Organisms Isolated Organism Mold Technique (Method 1) (N = 32) No. of Organisms Silicone Tubing Technique (Method 2) (N = 20) Multiple organisms 11 4 Methicillin-resistant Staphylococcus aureus Pseudomonas 1 2 Enterobacter 4 1 Escherichia coli 3 0 Serratia marcescens 3 0 Acinetobacter 1 2 Group-B Streptococcus 3 0 Enterococcus 2 0 Coagulase-negative Staphylococcus 2 3 Staphylococcus aureus 3 0 Streptococcus viridans 1 0 Morganella 1 0 Corynebacterium 2 0 Micrococcus 1 0 Proteus 0 2 Citrobacter 1 0 Klebsiella 0 1 TABLE IV Results Entire Series (Methods 1 and 2) Percent of Patients (No./Total No. in Group) Mold Technique (Method 1) Silicone Tubing Technique (Method 2) Bone union achieved* 84% (41/49) 86% (25/29) 95% (19/20) Infection eradicated 85% (44/52) 78% (25/32) 80% (16/20) Additional procedure needed to treat infection or nonunion 27% (14/52) 38% (12/32) 15% (3/20) Only index antibiotic-coated nail required 73% (38/52) 63% (20/32) 85% (17/20) *Two patients were lost to follow-up, and one patient with a cement spacer was excluded. TABLE V Additional Procedures to Treat Infection Procedure Mold Technique (Method 1) (N = 32) No. of Procedures Silicone Tubing Technique (Method 2) (N = 20) Nail removal Débridement Exchange to an antibiotic cement-coated nail Above-the-knee amputation Total one who had had a cement spacer inserted in situ was excluded from some of the analyses. Osseous union was achieved in 84% (forty-one) of the forty-nine remaining patients. Eight patients had a nonunion; three of these patients had a stable nonunion, two had a pending union, two underwent above-the-knee amputation, and one had an unstable nonunion. Including those with a stable nonunion, 90% (forty-four) of the forty-nine patients were able to walk on the

11 172 TABLE VI Additional Procedures (Bone-Grafting with or without Additional Fixation) to Achieve Union Percent of Patients (No./Total No. in Group)* Mold technique (Method 1) 21% (6/29) Silicone tubing technique (Method 2) 20% (4/20) Entire Series (Methods 1 and 2) 20% (10/49) *Two patients were lost to follow-up, and one patient with a cement spacer was excluded. operatively treated extremity. The infection was controlled in 85% (forty-four) of the fifty-two patients (Table IV). The index surgery with the antibiotic cement-coated nail was the only procedure required in 73% (thirty-eight) of the fifty-two patients. Additional procedures for the treatment of infection and/or nonunion were required in 27% (fourteen) of the fifty-two patients. These additional procedures included exchange to a new antibiotic cement-coated nail, additional débridement, and removal of the intramedullary nail (Table V). Bone graft was used to hasten union after control of the infection in some cases (Table VI). Two patients underwent above-the-knee amputation because the infection was only partially controlled. The overall limb salvage rate was 96% (fifty of fifty-two). More patients treated with Method 1 (the mold technique) underwent additional procedures to control the infection. Twelve procedures were performed in the thirty-two patients who had been treated with Method 1 compared with three procedures in the twenty patients who had been treated with Method 2. We believe that this difference is due to the greater number of patients in the Method-1 group who had bone defects as well as infections with multiple organisms. Complications The most common complication associated with both methods was cement-nail debonding during the removal of the antibiotic cement-coated nail (nine cases) (Table VII). There was retention of cement in two patients after nail removal. The cement in these patients was removed with sequential reaming and subsequent copious irrigation of the canal with use of canal-tip pulsed lavage. A distal vent hole or channel was necessary in these cases to facilitate complete removal of all retained cement. Incarceration of the antibiotic cement-coated nail during insertion occurred in one patient because of improper reaming. This was treated by splitting the anterior femoral cortex, removing the antibiotic cement-coated nail (without debonding), overreaming the canal, and reinserting the nail. This patient had not required any additional surgery by the time of writing. Twenty-five percent (thirteen) of the fifty-two patients had complications specific to the antibiotic cement-coated nail. Discussion nfected nonunions require procedures to control the infec- to provide stability, and to achieve union. Surgical dé- Ition, bridement and delivery of antibiotics locally and systemically are used to control the infection. Local antibiotic therapy results in high local concentrations of antibiotics with minimal systemic levels 2. Antibiotic-impregnated polymethylmethacrylate beads are used in the treatment of osteomyelitis and open fractures 3,6. However, a second procedure is required to remove the beads. Other methods of local antibiotic delivery include use of bioabsorbable delivery vehicles such as calcium sulfate and synthetic polymers 2,7. New synthetic bioabsorbable delivery vehicles are being developed to avoid the need for a second surgical procedure and, in some cases, to promote osseous union At present, cement containing sufficient concentrations of antibiotics to achieve local control of infection is not commercially available. If antibiotic-impregnated bone cement is needed to treat infection, the surgeon must prepare the cement by using high doses of various antibiotics. Aminoglycosides and vancomycin are common choices for local delivery because of their broad spectrum of activity, heat stability, and low allergenicity 2. Palacos bone cement (Zimmer) has been found to elute antibiotics more effectively than Simplex bone cement (Howmedica-Stryker, Rutherford, New Jersey) 15. Antibiotic elution from the polymethylmethacrylate beads follows a biphasic pattern, with an initial rapid phase followed by a secondary phase after five to ten days 16. The safety of local antibiotic therapy has been documented in clinical studies. Both animal and clinical studies TABLE VII Types of Complications Encountered with Antibiotic Cement-Coated Nails Mold Technique (Method 1) Silicone Tubing Technique (Method 2) Percent of patients with a complication (no./total no. in group) No. of complications 31% (10/32) 15% (3/20) Cement-nail debonding with nail removal 7 2 Debonding with nail insertion 1 0 Retained cement 2 0 Nail incarceration with insertion 0 1

12 173 have shown high local concentrations and undetectable or very low serum levels of the locally delivered antibiotics without systemic toxicity 2,12. Vancomycin and tobramycin are effective against many of the bacteria that were generally found in our patients (Table III). These antibiotics have been shown to be heat stable, with good elution properties from bone cement, and to have few adverse effects on bone-healing 1,2,7,15,17,18. In addition, we administer cefazolin intravenously during the immediate postoperative period until we receive the results of culture and sensitivity testing of the samples sent at the time of surgery. The systemic antibiotics are then changed as necessary, in consultation with an infectious disease specialist. In general, the systemic antibiotics are administered for six weeks or until there is a reduction in the levels of inflammatory markers such as C-reactive protein. Further treatment with oral antibiotics is given if recommended by the infectious disease specialist. Infected nonunions have traditionally been treated with external or internal fixation 19. However, a high prevalence of pin-site infections, muscle contractures, and joint stiffness has been observed in association with external fixation Some patients might not consent to the use of external fixators, while others might not be ideal candidates for external fixation because of obesity or an expectation of poor compliance. The use of antibiotic cement-coated nails benefits these patients. Use of an intramedullary nail with antibiotic-impregnated cement beads has been reported for the treatment of infected nonunions 23,24. This method entails a second procedure for removal of the beads or spacer. Antibiotic-impregnated cement-coated guide rods made with use of a chest tube as a template allow control of infection 25. However, a second surgical procedure is necessary to remove the guide rod and insert the intramedullary nail to provide adequate stability for healing of the nonunion. The use of an Ender or Küntscher nail coated with antibiotic-impregnated cement has also been reported 26,27. However, these nails do not provide adequate stability for healing of the nonunion in all cases. Both methods used to prepare the antibiotic cementcoated intramedullary nails in the present study are effective; however, the silicone tubing method produces a more reliable coating, is associated with fewer complications related to insertion, and requires less intraoperative time to prepare (ten minutes instead of one hour with the mold technique). It is currently our method of choice. Overall, the antibiotic cement-coated intramedullary nails are very effective for treating infected nonunions and segmental bone defects. These conditions would normally require long periods of external fixation and often bone transport. Our method is associated with a 27% risk that an additional procedure will be needed to treat the infection or nonunion. This is an acceptable risk given the difficult nature of the initial problem and the higher risk of complications and additional surgical procedures associated with circular external fixators 22. The only disadvantage of the antibiotic cementcoated nail appears to be cement-nail debonding during nail removal. The arthroplasty cement-removal instruments have been very effective for removal of cement. Future endeavors are being directed at improving the cement-nail interface. Raghuram Thonse, MS(Orth), DNB(Orth), FRCS(Glasg), FRCS(Ed) Musgrave Park Hospital, Belfast BT9 7JB, United Kingdom. address: thonser@yahoo.co.uk Janet D. 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