Late postoperative infection following spinal instrumentation: stainless steel versus titanium implants

Late postoperative infection following instrumented spinal surgery is a clinical entity that has emerged in recent years. The extended surface of the spinal instrumentation in combination with hematogenous seeding or intraoperative inoculation is the main predisposing factor. In order to investigate the contribution of the instrumentation material (stainless steel versus titanium implants) and mechanical loosening, two groups of patients are presented. The first group includes 50 idiopathic scoliotic patients who were treated with first-generation posterior stainless steel spinal segmental multihook instrumentation [Texas Scottish Rite Hospital (TSRH) instrumentation system], and the second group includes 45 similar patients who were treated with newer titanium implants (MOSS MIAMI, XIA, and CD). Follow-up ranged from 3 to 13 years. Six patients from the first group and one patient from the second group presented with late infections 1 to 7 years postoperatively. Common intraoperative findings were excessive inflammatory tissue and some degree of instrumentation loosening and corrosion (stainless steel). Removal of instrumentation in combination with appropriate antibiotics was an effective treatment. Further study with long-term follow-up is necessary in order to understand the exact incidence and pathology of such infections.     

Effect of time of onset and depth of infection on the outcome of total knee arthroplasty infections

The treatment results of 24 infected total knee arthroplasties with a minimum follow-up period of two years are presented. The most common pathogens were coagulase-positive staphylococci (50%), coagulase-negative staphylococci (29.2%), and enterococci (12.5%). Eleven patients with early postoperative infections (occurring within one month of prosthesis implantation) were treated with debridement, retention of the prosthesis, and intravenous antibiotics. Treatment was successful in all five patients with superficial infections not extending into the joint. In six patients with deep infections, treatment was successful in only two (33%), despite a longer course of antibiotic therapy (four to six weeks) and the use of tobramycin-impregnated polymethylmethacrylate beads. Three patients continued to have recurrent drainage, and one patient was subsequently successfully treated with a delayed exchange arthroplasty. Thirteen patients were diagnosed with late infections. One patient with a late, superficial infection and another with an acute (hematogenous seeding), deep infection were successfully managed with debridement and intravenous antibiotics. Prosthesis removal was not required. Eleven patients presented with late, deep infections. Of three patients who were treated without removal of the prosthesis, infection was arrested in only one. The remaining eight patients were treated with debridement, intravenous antibiotics, tobramycin-impregnated polymethylmethacrylate beads, and delayed exchange arthroplasty. The median interval to reimplantation was eight weeks (range, seven to 25 weeks). Treatment was successful in six cases (75%). The overall success rate in the treatment of total knee arthroplasty infections was 71%. In 19 patients with deep infections, treatment success was seen in 78% of patients treated with delayed exchange arthroplasty, but this value was only 40% in patients who were not treated with prosthesis removal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Delayed infections after posterior TSRH spinal instrumentation for idiopathic scoliosis: revisited

OBJECTIVE: To determine the incidence of delayed infections in idiopathic scoliosis treated with TSRH instrumentation, proper wound management after instrumentation removal, and whether the previously identified bacterial trend remains consistent. METHODS: All patients with idiopathic scoliosis > or =2 years after surgery with posterior TSRH instrumentation were included. Those cases with delayed infections were retrospectively reviewed. Time of presentation (infection) from index operation, clinical picture, sedimentation rate, presence of pseudarthrosis, organisms grown on culture, type of wound closure, and duration of antibiotics were examined. RESULTS: A total of 489 patients were identified > or =2 years postoperation; 23 had delayed infections (4.7%). Time of presentation averaged 27 months after initial surgery. Spontaneous drainage occurred in 15 patients, fluctuance in 6, and neither in the remaining 2 (pain and fever). Sedimentation rate averaged 48 mm/hr. All patients had instrumentation removed. Primary closure (1 stage) was performed in 14 patients, and delayed primary closure (> or =2 stages) was performed in nine patients. All wounds healed uneventfully. Cultures at the time of instrumentation removal grew Propionibacterium acnes in 12 patients, Staphylococcus epidermidis (or Staphylococcus coagulase-negative) in 4, Micrococcus varians in 1, and Staphylococcus aureus in 1. Five patients had negative cultures. After removal, patients received parenteral antibiotics; in 21 of these patients this was followed by oral antibiotics. CONCLUSIONS: Low-virulent skin organisms are primarily responsible for delayed infections. Intraoperative seeding followed by subclinical quiescent periods appears to be the method by which infection occurs. The increased bulk and modularity of modern instrumentation systems can lead to inflammation and bursa formation, thus contributing significantly to the activation of these infections. Primary wound closure results in successful wound healing. Delayed closure after 48 hours is unnecessary. Short-term postoperative parenteral antibiotics (2-5 days) followed by short-term oral antibiotics (7-14 days) is recommended.     

Postoperative deep wound infections in adults after spinal fusion: management with vacuum-assisted wound closure

OBJECTIVE: Vacuum-assisted wound closure (VAC) exposes the wound bed to negative pressure, resulting in removal of edema fluid, improvement of blood supply, and stimulation of cellular proliferation of reparative granulation tissue. It has been used to treat open wounds in the extremities, open sternal wounds, pressure ulcers, and abdominal wall wounds. This study retrospectively reviewed instrumented spine fusions complicated by surgical wound infection and managed by a protocol including the use of VAC in order to evaluate the efficacy of applying vacuum therapy on patients with deep spine infections and exposed instrumentation. METHODS: Twenty consecutive patients with deep wound infections after undergoing spinal fusion procedures were studied. There were 12 men and 8 women with an average age of 55 years (31-81 years). Eight patients had undergone concomitant anterior and posterior arthrodesis, nine patients had a posterior spinal fusion, and three patients had a transforaminal lumbar interbody fusion. Seven patients had a decompression with exposed dura. Sixteen patients presented with a draining wound within the first 6 weeks postoperatively (average 24 days). There were four patients who presented with back pain and temperature after 1 year postoperatively (average 3 years). All patients were taken to the operating room for irrigation and debridement followed by placement of the VAC with subsequent delayed closure of the wound. RESULTS: There was an average of 1.8 (1-8) irrigation and debridement procedures prior to placement of the VAC. Once the VAC was initiated, there was an average of 2.2 (2-3) procedures until and including closure of the wound. The wound was closed an average of 7 days (5-14 days) after the placement of the initial VAC in the wound. All patients tolerated the VAC without adverse effects. All patients were kept on a 6-week course of intravenous antibiotic therapy. The average follow-up was 10 months (6-24 months). There were no cases of uncontrolled sepsis once the VAC was initiated. All patients achieved a clean closed wound without removal of instrumentation at a minimum follow-up of 6 months. CONCLUSION: VAC therapy is an effective adjunct in closing complex deep spinal wounds with exposed instrumentation.     

Late-developing infection in instrumented idiopathic scoliosis.

STUDY DESIGN: This is a retrospective review of all patients requiring either Cotrel-Dubousset or Moss Miami rod removal. All initial spinal instrumentations were for adolescent idiopathic scoliosis from 1985 through 1994. Twenty-two patients who underwent rod removal for late-developing infection constitute the study group. OBJECTIVES: To determine the bacteriology and treatment of patients with late-developing infection after posterior spinal instrumentation for scoliosis. SUMMARY OF BACKGROUND DATA: There have been conflicting reports regarding this entity, some reporting a high percentage of positive cultures and others a low yield. The latter have attributed the entity to fretting corrosion. Much literature describes late appearance of infection with large foreign bodies (implants). Glycocalyx, a membrane that surrounds bacteria adjacent to surgical implants, results in poor antibiotic penetration, poor macrophage action, and difficulty in culturing bacteria. METHODS: One thousand two hundred forty-seven patients who underwent posterior instrumentation from 1985 through 1994 were reviewed. Those requiring implant removal were further studied. Those with late-developing infection (more than 1 year after the initial procedure) were further reviewed. Culture reports, presence of pseudarthrosis, and antibiotic regimen after implant removal were the primary parameters studied. RESULTS: Twenty-two patients (1.7%) experienced development of late infection a mean of 3.1 years after the initial procedure. In specimens from these patients cultured only 72 hours, only 1 of 10 was positive. Of those cultured for 7-10 days (the last 12) 11 were positive, usually for low-virulence skin organisms. After surgery, patients received antibiotics parenterally for 48 hours and orally for 7 days. All wounds were closed primarily. Four patients had pseudarthroses, two underwent revised procedures with titanium implants without signs of infection at more than 2 years' follow-up. CONCLUSIONS: Late-appearing infection with spinal instrumentation can be treated with device removal, primary skin closure, and short-term oral antibiotics. The infections affect soft tissue, not the bone.     

脊柱侧凸后路矫形融合术术后感染的治疗

目的评价清创术后置管冲洗、负压吸引及一期关闭伤口对脊柱侧凸后路矫形融合术术后感染的治疗效果。方法回顾1984年2月～1997年10月924例行脊柱后路矫形融合术的脊柱侧凸病例,发现感染15例,男5例,女10例,年龄11～32岁,平均17.5岁;特发性脊柱侧凸7例,先天性脊柱侧凸8例;内固定系统包括Harrington Luque3例,Harrington8例,CD4例。结果7例诊断为术后早期感染,平均发现时间为术后15d,清创术后除2例内固定物取出外,其余5例均予保留。8例迟发感染,平均发现时间为术后5.5个月,所有病例均予彻底清创,4例内固定物完全取出(其中1例因并发呼吸功能衰竭死亡),2例内固定物部分取出,2例保留。所有病例清创术后均置管持续冲洗及负压吸引,一期关闭伤口。平均置管冲洗2.8周,清创术后静脉使用抗生素19d。14例患者平均随访3.5年,未见感染复发。结论清创术后置管冲洗、负压吸引及一期关闭伤口,是治疗脊柱侧凸后路矫形融合术术后感染的有效方法。保留植入物,对多数病例并不影响对感染的控制。     

Vacuum-assisted wound closure of deep infections after instrumented spinal fusion in six children with neuromuscular scoliosis.

BACKGROUND CONTEXT: The rate of infection after spinal fusion in neuromuscular scoliosis is reported to range from 4% to 20%. Infection persists in about 50% after traditional treatment including debridement and closure. Instrumentation removal is necessary in up to 28%. PURPOSE: To analyze the outcome of vacuum-assisted wound closure (VAC) in combination with antibiotics for the treatment of deep wound infection after instrumented spinal fusion in pediatric neuromuscular scoliosis. STUDY DESIGN: Six prospective consecutive neuromuscular patients with scoliosis. PATIENT SAMPLE: Between 2001 and 2005, six consecutive pediatric patients (average age, 12.6 years) with neuromuscular scoliosis with a postoperative deep wound infection after instrumented spinal fusion were included in the study. OUTCOME MEASURES: Measurement of the duration of wound closure and infection parameters during treatment. METHODS: The patients were treated with a VAC system in combination with antibiotics. RESULTS: Wound closure averaged 3 months. Infection parameters were normalized within 6 weeks. Removal of the instrumentation was not necessary in any patient, and there were no signs of infection at follow-up ranging from 9 to 42 months. CONCLUSION: The VAC system, in combination with antibiotic therapy, seems to be a useful method for treatment of deep wound infections after spinal fusion in pediatric neuromuscular scoliosis. It may prevent removal of the instrumentation and multiple surgery for irrigation and closure of the wound.     

Treatment of infected knee arthroplasty

Forty-eight patients with 51 infected knee arthroplasties were treated at the authors' institution between 1973 and 1986 and followed for 5.5 (range, 0-14) years. Six methods to treat the infections were employed: antibiotics only, soft-tissue surgery, removal of the prosthesis, revision arthroplasty, arthrodesis, and amputation. Failure of the initial surgical treatment led to second revision surgery in 20 patients. At the follow-up examination, three patients (five knees) had died from septic complications and two patients had had above-knee amputation. Two of 32 patients had been successfully treated with antibiotics with no additional surgery. Four patients had successful soft-tissue surgery. Following removal of the prosthesis, the infection healed in four patients. In 12 of 19 patients (13 knees) with revision arthroplasty the infection healed, but only seven of these had functioning prostheses. The infection healed in all but one of the 21 patients with arthrodeses, and all but two were fused. Infected compartmental prostheses with good bone stock can be treated with an exchange arthroplasty using a two-stage procedure with tricompartmental revision prostheses. Otherwise, an arthrodesis using a two-stage procedure is recommended for the treatment of infected knee arthroplasty.     

Late hematogenous infection of penile prostheses

Late deep wound infection caused by hematogenous bacterial spread from a remote focus is a rare but disastrous complication of prosthetic devices. Six patients with probable late hematogenous infection are described. The initial implantation was free of contamination and infection, and a long functional interval ensued. A febrile process associated with a painful, swollen penis followed a probable remote infection source that was not covered with prophylactic antibiotics. All prostheses required removal. Prophylactic antibiotics may prevent these late hematogenous infections.     

Implant removal for late-developing infection after instrumented posterior spinal fusion for scoliosis: reinstrumentation reduces loss of correction. A retrospective analysis of 45 cases

A retrospective follow-up study of patients who, having undergone instrumented posterior spinal fusion for scoliosis, experienced late infection and then underwent either implant removal alone or implant removal and instrumented refusion. We conducted this study to determine whether it is possible to avoid loss of correction by a single-stage implant removal and reinstrumentation procedure. There have been a few reports of late-appearing infections after spinal instrumentation. Implant bulk, metallurgic reactions, and contamination with low-virulence microorganisms have been suggested as possible etiologic factors. The clinical symptoms include pain, swelling, redness, and spontaneous drainage of fluid. Complete instrumentation removal and systemic antibiotics is usually curative. We retrospectively reviewed 45 patients who underwent instrumented posterior spinal fusion for scoliosis and experienced development of late infections and, after a mean of 3 years after the initial procedure, either underwent implant removal alone [n=35, instrumentation removal (HR) group] or additionally underwent reinstrumentation and fusion [n=10, reinstrumentation and fusion (RI&F) group]. Three patients were reinstrumented 1.5 years after instrumentation removal, and seven underwent a one-stage rod removal and reinstrumentation/refusion procedure. Allergic predisposition, protracted postoperative fever, and pseudarthrosis appear to increase the risk of late-developing infection after posterior spinal fusion. All wounds in both groups healed uneventfully. Preoperative radiographic Cobb measurements showed no statistically significant between-group differences. At follow-up, however, outcome was clearly better in the RI&F group: Loss of correction was significantly smaller in reinstrumented patients. Thus, the thoracic Cobb angle was 28±16° (range 0–55°) in the RI&F group versus 42±15° (21–80°) in the HR group, and the lumbar Cobb angle was 22±11° (10–36°) in the RI&F group versus 29±12° (13–54°) in the HR group. The results of our study demonstrate that wound healing is usually uneventful after instrumentation removal for late infection, also when patients undergo instrumented refusion in a one-stage procedure. Reinstrumentation appears to achieve permanent correction of scoliosis.     

Efficacy of prophylactic application of vancomycin powder in preventing surgical site infections after instrumented spinal surgery: A retrospective analysis of patients with high-risk conditions

ObjectiveThis study aimed to determine the efficacy of prophylactic use of vancomycin powder against surgical site infections in patients with high-risk conditions who underwent posterior spinal instrumentation.MethodsData obtained from 209 patients who underwent posterior spinal instrumentation at a single institution from 2014 to 2017 were retrospectively reviewed. Patients were then divided into two groups: control group, including 107 patients (61 females, 46 males; mean age=54 years; age range=16–85 years), and treatment group, including 102 patients (63 females, 39 males; mean age=53 years; age range=14–90 years). All patients received the same standard prophylactic antibiotic regimen. In addition to the prophylactic antibiotic, vancomycin powder was applied locally to the surgical site in the treatment group. All patients were followed up for at least 90 days postoperatively. Infections were categorized as superficial and deep infections. Subgroup analysis of high-risk patients (Syrian refugees) was also performed.ResultsThe infection rates were 1.96% (two patients) in the treatment group and 6.54% (seven patients) in the control group. A significant decrease in the infection rates was observed with local vancomycin powder application. Advanced age (>46 years) and prolonged surgical duration (>140 min) were found to be the main risk factors for surgical site infections (p=0.004 and p=0.028, respectively). The infection rates were 3.22% and 8.11% in the treatment and control groups of refugees, respectively. There were three superficial and four deep infections in the control group and one superficial and one deep infection in the treatment group. A dominance of staphylococcus infections was observed in the control group, whereas no significant dominance was observed in the treatment group. Three patients in the control group and one patient in the treatment group received implant removal.ConclusionEvidence from this study has revealed that local application of vancomycin powder reduces the rate of surgical site infections after instrumented spinal surgery. The benefit of vancomycin application may be most appreciated in higher risk populations or in clinics with high baseline rates of infection.Level of EvidenceLevel III, Therapeutic Study     

Residual mobility of instrumented and non-fused segments in thoracolumbar spine fractures

The surgical management of thoracolumbar fractures presents potential benefits. However, the surgery solve the instability by fusion of mobile segments. We incorporate in our treatment algorithms, the use of restricted arthrodesis at injured levels, regardless of longer instrumentations, as well as the use of non-fused transitory stabilizations, based on the conviction that in non-fused segments without traumatic disc injury, mobility persists once the instrumentation is removed. The goals of this study were to compare the mobility of non-fused segments after hardware removal to a normal range of motion and to find prognostic pre-op imaging patterns. We reviewed 21 consecutive patients who underwent surgery with preservation of mobile segments (non-fused segments included in the construction) in order to recover mobility after removal of instrumentation, performed between 1995 and 2001. All patients were treated by indirect reduction with posterior transpedicular instrumentation. Clinical and radiological outcome was analyzed after an average follow-up of 46.6 months. Satisfactory subjective outcome results were obtained in 94.7%. The dynamic radiological follow-up study showed 75% (21 segments) with normal or decreased range of motion (ROM) and 25% (7 segments) without mobility. The non-fused segments with hardware removal before 10 months of evolution presented a normal or decreased mobility in 83.2% while the segments with hardware removal after 10 months showed 68.8% of mobility. The intervertebral disc (IVD)s with normal initial MRI morphology preserved their mobility in 81.9%. Complications occurred in four patients: two superficial wound infections and two patients presented a late fracture of one USS Schanz. The results of this study prove that in thoracolumbar fractures, non-fused spinal segments included in pedicular instrumentation maintained mobility in a high percentage once the hardware is removed. 75% of the segments presented a normal or decreased ROM.     

Anterior stabilization, instrumentation, and decompression for post-traumatic kyphosis

Thirty-seven patients underwent surgery for late post-traumatic kyphosis in the lumbar, thoracolumbar, or thoracic spine. Indications for surgery included: increasing deformity, pain, and persistent neurologic deficit with paraparesis in eight, and development of late spinal stenosis in a further nine patients. All patients underwent anterior correction with Kostuik-Harrington instrumentation. Seventeen patients with neurologic deficit underwent decompression over appropriate levels as well. No posterior fusions or instrumentation were carried out. Stable arthrodesis with correction of the deformity occurred in 36 of 37 patients with only one nonunion. Pain was reduced significantly in 78% of patients. Late neurologic improvement of a significant functional degree occurred in three of eight paraparetics. All patients with spinal stenosis had relief of their symptoms and signs.     

单中心8818例脊柱畸形矫形术后深部感染的处理策略

目的探讨脊柱畸形矫形术后深部感染的发生率及其相应的处理策略。方法回顾性分析1998年1月至2017年12月接受脊柱畸形矫形术治疗8818例患者的病历资料,根据患者术后的临床症状、影像学检查及实验室检查判断是否发生深部感染。将初次手术后3个月之内发生的感染定义为早发性感染,初次手术3个月后发生的感染定义为迟发性感染。所有感染患者行清创灌洗、术后引流冲洗,并静脉应用敏感抗生素。若感染无法根除,如手术后时间不足2年,暂予伤口换药保留内固定;如手术后时间达到2年,评估融合情况满意后可在伤口清创的同时取出内固定。摄站立位全脊柱正、侧位X线片测量冠状面和矢状面参数,评估取出内固定者矫正丢失情况。结果共有60例(0.68%,60/8818)术后发生深部感染,早发性感染11例(发生率为0.12%,11/8818),迟发性感染49例(发生率为0.56%,49/8818)。两组患者在年龄、性别、手术入路及融合节段数方面的差异均无统计学意义。术后2~5年是深部感染发生的高峰期。特发性脊柱侧凸及强直性脊柱炎患者术后感染的发生率最低,综合征性及神经肌源性脊柱侧凸术后感染的发生率较高。初次培养阴性率较高,早发性感染中金黄色葡萄球菌和大肠埃希菌居多;迟发性感染中痤疮丙酸杆菌和凝固酶阴性葡萄球菌占比明显增高。经治疗后早发性感染组中9例保留内固定,2例换药至术后2年取出内固定。迟发性感染组中5例保留内固定,10例换药至术后2年取出内固定,34例手术时间超过2年直接取出内固定;其中1例患者取出内固定后1个月重新植入内固定;另有1例患者因矫正丢失在取出内固定3年后重新植入内固定。末次随访时取出内固定的患者出现了明显的冠状面矫正丢失。结论脊柱畸形矫形术后深部感染的发生率为0.68%,早发性感染发生率较低,迟发性感染较高;神经肌源性脊柱侧凸与综合征性脊柱侧凸患者有着较高的感染风险。如果感染在反复清创后无法根除,推荐在术后2年骨融合后取出内固定,但仍存在矫正丢失的风险。     

Late implant infections caused by Propionibacterium acnes in scoliosis surgery

One hundred and one consecutive adolescent scoliosis patients instrumented from the posterior between 1995 and 2002, with a minimum follow-up of 24 months (maximum 106 months), were reviewed for incidence of infection. Stainless steel implants with pedicle screws were used in the thoracic and lumbar spine of all patients. All were operated on by a single surgeon. There were no early infections. Incidence of late infection was 6.9% (seven patients). Clinical indicators for infection were the sudden onset of local pain and swelling without fever after an initial pain-free interval. There were no reliable laboratory parameters. Normal CRP and ESR did not rule out a late infection. Extended cultures were done from intraoperative swabs. Propionibacterium acnes was found in six patients. There were no other organisms identified. No causative organism could be identified in one patient, despite extended cultures. All patients were successfully treated with implant removal and antibiotic therapy for 4–9 weeks. No pseudarthrosis was seen on implant removal. Despite bony fusion, loss of correction between 10° and 26° was observed in three patients after implant removal.     

Late infection after cranioplasty--review of 14 cases

The incidence of late infection after cranioplasty was studied in 130 patients with 133 cranioplasties. The materials used were prefabricated resin in 62 cases, autogenic bone in 38, intraoperatively fashioned resin in 25, and vitallium in eight. Six infections were documented, for an infection rate of 4.5%. In addition to these six cases, we studied eight patients with infections who had undergone cranioplasty elsewhere but had the infected plates removed in our hospitals. Among the 14 cases of infection, the intervals between cranioplasty and plate removal were 3 to 43 months (average, 10.5 months). The eight patients referred from other hospitals had a significantly shorter average interval between external decompression and cranioplasty than did patients who did not develop infection (2.6 versus 6.7 months; p less than 0.005). Systemic signs were mild despite obvious local signs of infection. Of the 11 first infections, nine (82%) were associated with discharge of pus from a fistula; in these cases a galeal suture had become infected apparently through scratching by the patients. In contrast, in the three patients who had had a previous infection, the second infection manifested as subgaleal and epidural empyema or meningitis without a fistula or pus discharge. Nine infections (69%) were due to Staphylococcus. All but two patients required removal of the infected plates. One recovered with conservative therapy and one died of meningitis, giving a mortality rate of 0.8%. No matter how mild the systemic signs, late infection warrants surgical debridement and plate removal. The risk factors for late infection of cranioplasty are discussed.     

Deep, late infections associated with internal fixation in children

Deep, late infection associated with internal fixation is well known in adults, but has not been previously reported in children. We report here six cases of deep, late infection in children associated with internal fixation of the proximal femur. All patients had cerebral palsy and had undergone a proximal femoral osteotomy for hip subluxation or dislocation. The patients presented with infection between 7 and 24 months after a period of total recovery. The clinical presentation was variable, although many patients had increasing hip pain. Radiographs showed radiolucency around the lag screw. The bacteriologic finding was usually Staphylococcus aureus, and patients responded to wound debridement, hardware removal, and intravenous antibiotics. In light of these cases of deep, late infection, we strongly urge routine removal of metallic implants as soon as bony healing will allow.     

Arthrodesis of the knee with a long intramedullary nail following the failure of a total knee arthroplasty as the result of infection

BACKGROUND: Knee arthrodesis can be an effective treatment option for relieving pain and restoring some function after the failure of a total knee arthroplasty as the result of infection. The purpose of the present study was to review the outcome of a staged approach for arthrodesis of the knee with a long intramedullary nail after the failure of a total knee arthroplasty as the result of infection. METHODS: We reviewed the results for twelve patients who underwent knee arthrodesis after the removal of a prosthesis because of infection. The study group included seven women and five men who had an average age of sixty-eight years at the time of the arthrodesis. All patients were managed with a staged protocol. Implant removal, débridement, and insertion of antibiotic cement spacers was followed by the administration of systemic antibiotics. Provided that clinical and laboratory data suggested eradication of the infection, arthrodesis of the affected knee with use of a long intramedullary nail was carried out. Clinical and laboratory evaluation and radiographic analysis were performed after an average duration of follow-up of 4.1 years. RESULTS: Solid union was achieved in ten of the twelve knees. The average time to union was 5.5 months. One patient had an above-the-knee amputation because of recurrence of infection. In another patient, nail breakage occurred three years following implantation. The average limb-length discrepancy was 5.5 cm. The mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from 41 to 64 points. None of the seven patients who underwent arthrodesis with a technique involving convex-to-concave reamers had a complication, and the average time to union for these seven patients was shorter than that for the remaining five patients (4.3 compared with 7.4 months). CONCLUSIONS: We believe that obtaining large surfaces of bleeding contact bone during arthrodesis following staged treatment of an infection at the site of a failed total knee arthroplasty contributes to stability and enhances bone-healing. Staged arthrodesis with use of a long intramedullary nail and convex-to-concave preparation of bone ends provided a painless functional gait with low complication and reoperation rates in this challenging group of patients.     

Infection after total knee arthroplasty. A retrospective study of the treatment of eighty-one infections.

BACKGROUND: The clinical presentation of an infection at the site of a total knee arthroplasty can be used as a guide to treatment, including the decision as to whether the prosthesis should be retained or removed. We reviewed the results of treatment of infection after total knee arthroplasty to evaluate the effectiveness of four treatment protocols based on the clinical setting of the infection. METHODS: We retrospectively evaluated the results of treatment of eighty-one infections in seventy-six consecutive patients who either had an infection after a total knee arthroplasty or had multiple positive intraoperative cultures of specimens of periprosthetic tissue obtained during a revision total knee arthroplasty performed because of presumed aseptic loosening. The patients were managed according to one of four protocols. Five infections in five patients who had positive intraoperative cultures were treated with antibiotic therapy alone. Twenty-three early postoperative infections in twenty-one patients were treated with débridement, antibiotic therapy, and retention of the prosthesis. Twenty-nine late chronic infections in twenty-eight patients were treated with a delayed-exchange arthroplasty after a course of antibiotics. Seven acute hematogenous infections in six patients were treated with débridement, antibiotic therapy, and retention of the prosthesis. Seventeen infections in seventeen patients were not treated according to one of the four protocols. Sixteen late chronic infections were treated either with an arthrodesis (five infections) or with débridement, antibiotic therapy, and retention of the prosthesis (eleven infections). One acute hematogenous infection was treated with resection arthroplasty because of life-threatening sepsis. RESULTS: The mean duration of follow-up was 4.0 years (range, 0.3 to 14.0 years). Eleven patients who had an arthrodesis, a resection arthroplasty, or an above-the-knee amputation after less than two years of follow-up were included in the study as individuals who had a failure of treatment. In the group of patients who were managed according to protocol, the initial course of treatment was successful for all five infections that were diagnosed on the basis of positive intraoperative cultures, five of the ten deep early infections, all thirteen superficial early infections, twenty-four of the twenty-nine late chronic infections, and five of the seven acute hematogenous infections. Only one of eleven prostheses in patients who had a late chronic infection that was not treated according to protocol was successfully retained after débridement. CONCLUSIONS: Our treatment protocols, which were based on the clinical setting of the infection, were successful for most patients. A major factor associated with treatment failure was a compromised immune status. Bone loss and necrosis of the soft tissues around the joint also complicated the treatment of these infections.     

Arthrodesis of the knee with intramedullary nail fixation

Thirty-three patients had an arthrodesis of the knee by means of an intramedullary nail introduced through the greater trochanter. Fifteen of the procedures were done for a failed knee arthroplasty; eight had failed because of infection and seven, because of aseptic loosening. Twenty-nine of the thirty-three knees united three to four months after the first attempt at arthrodesis and three united after technical errors were corrected. One knee had a broken nail and a non-union; this was still untreated at the time of writing. Four nails broke: three in the line of fusion and one in the line of an infected supracondylar pseudarthrosis of the femur. No new infections developed after the arthrodesis. Three patients had had an infection and a chronic fistula before the arthrodesis, and the fistulae healed six, fourteen, and eighteen months postoperatively. In another patient, who had had infection and necrosis of the skin preoperatively, the wound healed in six months. All of these knees healed without an additional major operation. The functional result was satisfactory in all patients. After the arthrodesis, seventeen of the thirty-three patients needed less aid when walking, and no patient needed more aid. Fusion of the knee with a long intramedullary nail can be safe and effective, even in the presence of infection, if the revision is performed properly and certain technical principles are followed. It is especially important to establish good contact between the resected bones.