Knee fusion using dual platings with the locking compression plate

Knee Arthrodesis with a Modular Silver-Coated Endoprosthesis for Infected Total Knee Arthroplasty with Extensive Bone Loss: A Retrospective Case-Series Study

INTRODUCTION

Knee arthrodesis is a limb salvage intervention for persistent periprosthetic joint infection (PJI) when revision total knee arthroplasty fails. Conventional arthrodesis techniques are associated with the increased rate of complications, especially in patients with extensive bone loss and extensor tendon deficiency.

METHODS

Eight patients with a modular silver-coated arthrodesis implant after failed exchange arthroplasty for infection, were retrospectively reviewed. All patients had significant bone loss, while 5 displayed extensor tendon deficiency. Survivorship, complications, leg length discrepancy, median Visual Analogue Scale (VAS) and Oxford Knee score (OKS) were evaluated.

RESULTS

The median follow up was 32 months (range 24-59 months). The survivorship rate of the prosthesis was 86% during the minimum time of follow up of 24 months. In one patient recurrence of the infection was observed and above-knee amputation was performed. The median postoperative leg length discrepancy was 2.07 ± 0.67 cm. Patients were able to ambulate with mild or no pain. The median VAS and OKS was 2.14 ± 0.9 and 34.7 ± 9.3, respectively.

CONCLUSIONS

The results of our study demonstrated that knee arthrodesis with a silver coated arthrodesis implant, performed for persistent PJI in patients with significant bone loss and extensor tendon deficit, provided a stable construct, allowed eradication of infection and was associated with good functional outcome.

National Decline in Knee Fusions Performed for Salvage of Chronic Periprosthetic Total Knee Infections

The primary purpose of this study was to study and compare rates of two salvage operations for patients with chronically infected total knee arthroplasties: (1) knee arthrodesis and (2) above knee amputation (AKA). An analysis was performed comparing the inpatient hospital characteristics and complications between the two procedures. Secondarily, we presented rates of all surgically treated periprosthetic total knee infections over a 6-year period. Using the Nationwide Inpatient Sample, we identified all patients with a periprosthetic infection (International Classification of Diseases, Ninth Revision [ICD-9] 996.66) from 2009 to 2014. Subsequently, we identified surgically treated total knee infections through the following ICD-9 codes: 00.80 (all component revision), 00.84 (liner exchange), 80.06 (removal of prosthesis), 84.17 (AKA), and 81.22 (knee fusion). From 2009 to 2014, the annual incidence of surgically treated total knee periprosthetic infections increased by 34.9% nationally, while the annual incidence of primary total knees increased by only 13.9%. Salvage operations (AKA and knee fusion) represented 5.8% of all surgically treated infections. The rate of knee fusions decreased from 1.9% of surgically treated infections in 2009 to 1.4% in 2014 (p < 0.05), while the rate of AKA stayed steady at 4.5% of cases over the 6-year period. Length of stay was significantly shorter in the knee fusion group (7.9 vs. 10.8 days, p < 0.05), but total hospital costs were higher (33,016 vs. 24,933, p < 0.05). In the multivariable adjusted model, patients undergoing knee fusion had significantly decreased odds of being discharged to skilled nursing facility (odds ratio: 0.42, 95% confidence interval: 0.31-0.58). The annual incidence of surgically treated periprosthetic total knee infections is increasing. The rate of knee arthrodesis for chronic periprosthetic total knee infections is decreasing. Reasons for this downward trend in knee fusions should be evaluated carefully as knee fusions have shown to have the potential advantage of improved mobility and decreased patient morbidity for chronic PJI. The level of evidence is III.

Diagnosis and management of infected arthroplasty

Periprosthetic joint infection (PJI) is one of the most dreadful complications after THA and TKA. Though prevention is of utmost importance in PJI management, the last decade has seen many remarkable developments in PJI diagnosis, including the introduction of several standardized PJI diagnostic definitions and biomarkers. Depending on the specific clinical situation, a myriad of treatment options for PJI are offered. Our review aims to summarize the pertinent information on PJI diagnosis and synthesize literature on the different treatment methods currently used in clinical practice. One of the most accepted PJI diagnostic definitions was developed by the Musculoskeletal Infection Society (MSIS) in 2011, later modified in the 2013 International Consensus Meeting (ICM). After promising results from studies, alpha-defensins and D-dimer were recently incorporated into the 2018 ICM PJI definition. The management choices for PJI include irrigation and debridement (DAIR), one-stage exchange arthroplasty, or two-stage exchange arthroplasty, to name a few. While two-stage revision has traditionally been the treatment of choice in the United States, there has been a growing body of evidence framing one-stage revision as a comparable choice. One-stage revision should be offered in patients meeting strict selection criteria: no sinus tract, proper soft tissue available for wound closure, appropriate bone stock, a favorable identifiable organism with encouraging antibiotic sensitivities (for cement and oral suppression later), and robust immunological status. DAIR can be considered in case of early infections with sensitive infecting organisms. Patients with multiple unsuccessful revisions or those who refuse further surgical intervention for PJI can be offered antibiotic suppression. If nothing seems to work, salvage procedures (resection arthroplasty and arthrodesis) are available as a last resort. Further research is encouraged to improve on diagnostic capabilities and develop evidence on the best treatment of choice for PJI.

Knee arthrodesis as last resort for persistent knee joint infections : Comparison of extramedullary and intramedullary treatment

Background

Knee joint arthrodesis is an established treatment for periprosthetic infections (PPI) providing stability and pain relief. In this study the outcome after arthrodesis of the knee joint for persistent infections was compared and evaluated depending on the surgical procedure (intramedullary vs. extramedullary).

Material and methods

In a retrospective case analysis, all patients who underwent knee joint arthrodesis between 1 January 2010 and 31 December 2016 were identified and divided into two groups: IMA and EMA. All patients were examined clinically and radiologically and the patient files were evaluated. In addition, the FIM score, the LEFS, the WHOQOL-BREF and NRS were evaluated.

Results

The median LEFS score for the IMA group was 26 points and in the EMA group 2 points (p = 0.03). The IMA patients showed a median pain scale at rest of 0 and during exercise of 2. The EMA group recorded a pain scale of 3 at rest and 5 during exercise (p = 0.28 at rest; p = 0.43 during exercise). In the IMA group the median postsurgical leg length difference was −2.0 cm and −2.5 cm in the EMA group (p = 0.31). At the end of the follow-up examinations, the FIM score of patients in the IMA group was 74.5 points and 22 points in the EMA group (p = 0.07).

Conclusion

The study showed that no arthrodesis procedure is obviously superior with respect to the postoperative outcome. The IMA combines advantages especially in the early phase after surgery in terms of function as well as patient comfort and is therefore currently the procedure of choice. The attending physician should be familiar with the advantages and disadvantages of the various procedures in order to be able to make an individual decision and thus maximize the chance of treatment success.

Trends in the treatment of infected knee arthroplasty

Essential treatment methods for infected knee arthroplasty involve DAIR (debridement, antibiotics, and implant retention), and one and two-stage exchange arthroplasty.

Aggressive debridement with the removal of all avascular tissues and foreign materials that contain biofilm is mandatory for all surgical treatment modalities.

DAIR is a viable option with an acceptable success rate and can be used as a first surgical procedure for patients who have a well-fixed, functioning prosthesis without a sinus tract for acute-early or late-hematogenous acute infections with no more than four weeks (most favourable being < seven days) of symptoms. Surgeons must focus on the isolation of the causative organism with sensitivities to bactericidal treatment as using one-stage exchange.

One-stage exchange is indicated when the patients have:

minimal bone loss/soft tissue defect allowing primary wound closure,

easy to treat micro-organisms,

absence of systemic sepsis and

absence of extensive comorbidities.

There are no validated serum or synovial biomarkers to determine optimal timing of re-implantation for two-stage exchange.

Antibiotic-free waiting intervals and joint aspiration before the second stage are no longer recommended. The decision to perform aspiration should be made based on the index of suspicion for persistent infection.

Re-implantation can be performed when the treating medical team feels that the clinical signs of infection are under control and serological tests are trending downwards.

Cite this article: EFORT Open Rev 2020;5:672-683. DOI: 10.1302/2058-5241.5.190069

Application of the Ilizarov technique for knee joint arthrodesis as a treatment for end-stage tuberculosis of the knee

Background

With the global determination to eliminate tuberculosis (TB), the treatment for end-stage TB of the knee joint is still a great clinical challenge. This study aims to retrospectively determine the clinical and radiographic outcomes after use of the Ilizarov technique for knee joint arthrodesis as a treatment for end-stage knee TB.

Methods

Twenty-six patients with end-stage knee TB treated by external fixation with the Ilizarov fixator between 2012 and 2017 were examined. Anti-TB drugs were administered preoperatively, intraoperatively, and postoperatively. Clinical and radiologic examinations were performed for comprehensive evaluations, and these include C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), flexion and valgus angle of the knee, leg-length discrepancy, and Lysholm score.

Results

Twenty-four patients were followed up for an average of 5.8 years (2.2–7 years). All patients achieved bone fusion within a mean of 6.4 months (4–16 months). The ESR and CRP concentrations were observed to return to normal within 5.1 ± 1.1 months postoperatively. There was no recurrence of TB. At last follow-up, the mean leg-length discrepancy was 2.7 ± 1.4 cm, and the mean alignment was 8.7 ± 2.6° flexion and 5.3 ± 1.0° valgus. No patient had a significant rotational deformity. The average Lysholm score was seen to improve significantly from 36.8 ± 18.4 preoperatively to 79.5 ± 5.9 at final follow-up (p < 0.0001).

Conclusion

This study has demonstrated that the Ilizarov technique for knee joint arthrodesis as a treatment of end-stage knee TB achieved promising outcomes with minimal complications.

Peri-implant fracture after dual-plating knee arthrodesis for failed total knee arthroplasty: case series

Knee arthrodesis is an option in the setting of failed total knee arthroplasty. Dual-plate fixation is a described technique to obtain knee fusion in this scenario. Literature on the complications of knee arthrodesis with dual-plate constructs is limited. We present 3 cases who underwent dual-plate knee arthrodesis complicated by peri-implant femur fracture.

Salvage Procedures for Management of Prosthetic Joint Infection After Hip and Knee Replacements

Background:

The increasing load placed by joint replacement surgery on health care systems makes infection, even with the lowest rates, a serious concern that needs to be thoroughly studied and addressed using all possible measures.

Methods:

A comprehensive review of the current literature on salvage procedures for recurrent PJIs using PubMed, EMBASE and CINAHL has been conducted.

Results:

Prolonged suppressive antibiotic therapy (PSAT), resection arthroplasty and arthrodesis were the most common procedures performed. Suppressive antibiotic therapy is based on the use of well tolerated long term antibiotics in controlling sensitive organisms. Resection arthroplasty which should be reserved as a last resort provided more predictable outcomes in the hip whereas arthrodesis was associated with better outcomes in the knee. Various methods for arthrodesis including internal and external fixation have been described.

Conclusion:

Despite good union and infection control rates, all methods were associated with complications occasionally requiring further surgical interventions.

Knee arthrodesis with a long intramedullary nail as limb salvage for complex periprosthetic infections

BACKGROUND

Periprosthetic infection following total knee arthroplasty is a devastating complication, which is not always satisfactorily resolved by revision surgery. Arthrodesis is a salvage alternative to above-knee amputation or permanent resection arthroplasty. Fixation options include internal compression plating, external fixation, and intramedullary nails.

METHODS

We retrospectively reviewed twelve consecutive cases (9 males, 3 females; mean age, 67 years) of knee arthrodesis with a long intramedullary nail, performed at a single institution between 2003 and 2014. Desired outcomes were the ability to mobilize without pain, solid radiographic fusion, and the eradication of infection.

RESULTS

Mean follow-up was 48.5 months (range, 9-120 months). Eleven patients (92 %) demonstrated stable fusion, ten patients (83 %) were ambulatory without pain, and ten patients (83 %) remained without infection at most recent follow-up. Eight patients (67 %) achieved union at an average of 12 months; three required repeat procedures, achieving union at an average of 9 months. There was a significant difference (P < 0.01) between the numbers of previous operations amongst the eight patients who initially achieved union (mean, 3.25) and three who subsequently required repeat procedures (mean, 8.33).

CONCLUSIONS

In contrast to similar studies, we performed a single-stage exchange where possible, while comparable ambulatory and fusion rates were observed. Numerous previous attempts at revision arthroplasty, co-morbidities, and infections with highly resistant organisms have been associated with further complications. Although technically challenging, knee arthrodesis with a long intramedullary nail offers an acceptable limb salvage procedure for carefully selected patients with complex periprosthetic infections.

The SIGN nail for knee fusion: technique and clinical results

Purpose: Evaluate the efficacy of using the SIGN nail for instrumented knee fusion.

Methods: Six consecutive patients (seven knees, three males) with an average age of 30.5 years (range, 18–50 years) underwent a knee arthrodesis with SIGN nail (mean follow-up 10.7 months; range, 8–14 months). Diagnoses included tuberculosis (two knees), congenital knee dislocation in two knees (one patient), bacterial septic arthritis (one knee), malunited spontaneous fusion (one knee), and severe gout with 90° flexion contracture (one knee). The nail was inserted through an anteromedial entry point on the femur and full weightbearing was permitted immediately.

Results: All knees had clinical and radiographic evidence of fusion at final follow-up and none required further surgery. Four of six patients ambulated without assistive device, and all patients reported improved overall physical function. There were no post-operative complications.

Conclusion: The technique described utilizing the SIGN nail is both safe and effective for knee arthrodesis and useful for austere environments with limited fluoroscopy and implant options.

Knee arthrodesis using a unilateral external fixator combined with crossed cannulated screws for the treatment of end-stage tuberculosis of the knee

Background

The treatment of end-stage tuberculosis (TB) of the knee remains a significant clinical challenge, and clinical data are lacking. This study aimed to retrospectively determine the outcome of single-stage knee arthrodesis with a unilateral external fixator combined with cannulated screws for the treatment of end-stage TB.

Methods

Twenty-six patients with end-stage knee TB were treated by single-stage arthrodesis. All patients underwent open debridement and the insertion of a unilateral external fixator combined with crossed cannulated screws and received systemic antitubercular therapy. Clinical evaluations and radiographic analyses were performed after an average follow-up duration of 5.5 years.

Results

The mean time to radiographic bone fusion was 5.6 months. Primary full union was achieved in 25 patients (96.2 %) within 8 months, and the remaining patients achieved bone fusion at 14 months postoperatively. The mean post-operative alignment was 5.4° valgus and 12.5° flexion. The mean leg-length discrepancy was 2.8 cm. The mean VAS score improved from 67.3 before surgery to 16.2 at the last follow-up (P < 0.01), and the mean WOMAC score improved from 58.8 to 13.7 (P < 0.01). The erythrocyte sedimentation rate (ESR) and C-reactive protein level returned to normal in 25 patients by 3 months postoperatively. No recurrence in the target knee was noted.

Conclusions

Single-stage arthrodesis with a unilateral external fixator combined with cannulated screws can be regarded as efficacious for the treatment of end-stage knee TB. Additional studies are necessary to confirm the findings of our study.

The multiply-operated total knee replacement patient: salvage options

Although the vast majority of patients that undergo total knee replacement have satisfactory outcomes with a generally low complication rate, occasionally a patient will be encountered that has had multiple failed surgeries, and now reaches a crossroad as to whether limb salvage will be acceptable or not.

Arthrodesis of the knee following failed arthroplasty

PURPOSE

Primary stability in arthrodesis of the knee can be achieved by external fixation, intramedullary nailing or plate fixation. Each method has different features and results. We present a practical algorithm for arthrodesis of the knee following a failed (infected) arthroplasty, based on our own results and a literature review.

METHODS

Between 2004 and 2010, patients were included with an indication for arthrodesis after failed (revision) arthroplasty of the knee. Patients were analyzed with respect to indication, fusion method and bone contact. End-point was solid fusion.

RESULTS

Twenty-six arthrodeses were performed. Eighteen patients were treated because of an infected arthroplasty. In total, ten external fixators, ten intramedullary nails and six plate fixations were applied; solid fusion was achieved in 3/10, 8/10 and 3/6, respectively.

CONCLUSIONS

There is no definite answer as to which method is superior in performing an arthrodesis of the knee. Intramedullary nailing achieved the best fusion rates, but was used most in cases without--or cured--infection. Our data and the contemporary literature suggest that external fixation can be abandoned as standard fusion method, but can be of use following persisting infection. The Ilizarov circular external fixator, however, seems to render high fusion rates. Good patient selection and appropriate individual treatment are the key to a successful arthrodesis. Based upon these findings, a practical algorithm was developed.

Better function for fusions versus above-the-knee amputations for recurrent periprosthetic knee infection

BACKGROUND

Treatment of chronic periprosthetic joint infections (PJIs) after TKA is limited to fusions, above-the-knee amputations (AKAs), revision TKA, and antibiotic suppression and is often based on the patient's medical condition. However, when both fusion and AKA are options, it is important to compare these two procedures with regard to function.

QUESTIONS/PURPOSES

Do patients receiving a knee fusion for PJI after TKA have better function compared to patients receiving an AKA?

METHODS

We retrospectively reviewed patients who were eligible for either fusion or AKA after PJI TKA. Thirty-seven patients underwent a fusion for PJIs after TKA between 1999 and 2010. Nine patients died postoperatively and eight patients were lost to followup, leaving 20 patients. Patients completed a specialized questionnaire about their fusion, and functional capability was assessed by the SF-12. We compared fusions to a previously published group of six patients who underwent AKA for recurrent PJI after TKA.

RESULTS

For patients with fusion, community ambulators increased from five to 10 and nonambulators decreased from three to one. For patients with AKA, nonambulatory patients increased from zero to two, and community ambulators decreased from four to one. The SF-12 physical component summary measurements were higher for fusions (51) than for AKAs (26). The mental component summary was also higher in fusions (60) than in AKAs (44). Seventy percent of patients indicated they would undergo a fusion again instead of undergoing an amputation if they were presented with both options after undergoing their operation.

CONCLUSIONS

Patients receiving knee fusions for treating recurrent PJIs after TKA have better function and ambulatory status compared to patients receiving AKA.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Distraction arthrodesis with intramedullary nail and mixed bone grafting after failed infected total knee arthroplasty

PURPOSE

The purpose of this study was to determine the success rate of the distraction arthrodesis, which was attempted to maintain the limb length during arthrodesis using an intramedullary nail and mixed bone grafting, in terms of the eradication of infection, solid union, and functional outcome. The hypothesis was that distraction arthrodesis would be successful in union and elimination of infection with minimal limb shortening and a satisfactory functional outcome despite large bone defects.

METHODS

Eight patients were managed by arthrodesis using a Huckstep intramedullary nail and massive corticocancellous bone chip grafts from autologous iliac bone and deep-frozen femoral head allografts were included in the study. The mean age of the patients was 65.5 ± 7.1 years, and the follow-up duration was 52.1 ± 21.3 months. A mean of 5.3 ± 1.3 surgical procedures had been performed before arthrodesis. The mean longest and shortest distances of the bone defect were 58.6 ± 10.3 and 34.6 ± 7.0 mm, respectively.

RESULTS

Radiological union was obtained in all cases at a mean of 9.9 ± 1.9 months. The mean postoperative limb shortening was 11.0 ± 7.3 mm when compared to the contralateral knee. The mean Knee Society score was 59.9 ± 9.2, and the function score was 38.8 ± 13.3. No additional procedures were required for any of the patients.

CONCLUSION

Distraction arthrodesis of infected knees following total knee arthroplasty demonstrated union and eradication of infection in all patients and a large tibiofemoral gap due to the severe bone defect could be managed with massive bone chip grafts. This method of arthrodesis would be a reliable and an effective method for failed total knee arthroplasty when two-staged reimplantation fails or is not attainable.

Biomechanical investigation of a novel ratcheting arthrodesis nail

Background

Knee or tibiotalocalcaneal arthrodesis is a salvage procedure, often with unacceptable rates of nonunion. Basic science of fracture healing suggests that compression across a fusion site may decrease nonunion. A novel ratcheting arthrodesis nail designed to improve dynamic compression is mechanically tested in comparison to existing nails.

Methods

A novel ratcheting nail was designed and mechanically tested in comparison to a solid nail and a threaded nail using sawbones models (Pacific Research Laboratories, Inc.). Intramedullary nails (IM) were implanted with a load cell (Futek LTH 500) between fusion surfaces. Constructs were then placed into a servo-hydraulic test frame (Model 858 Mini-bionix, MTS Systems) for application of 3 mm and 6 mm dynamic axial displacement (n = 3/group). Load to failure was also measured.

Results

Mean percent of initial load after 3-mm and 6-mm displacement was 190.4% and 186.0% for the solid nail, 80.7% and 63.0% for the threaded nail, and 286.4% and 829.0% for the ratcheting nail, respectively. Stress-shielding (as percentage of maximum load per test) after 3-mm and 6-mm displacement averaged 34.8% and 28.7% (solid nail), 40.3% and 40.9% (threaded nail), and 18.5% and 11.5% (ratcheting nail), respectively. In the 6-mm trials, statistically significant increase in initial load and decrease in stress-shielding for the ratcheting vs. solid nail (p = 0.029, p = 0.001) and vs. threaded nail (p = 0.012, p = 0.002) was observed. Load to failure for the ratcheting nail; 599.0 lbs, threaded nail; 508.8 lbs, and solid nail; 688.1 lbs.

Conclusion

With significantly increase of compressive load while decreasing stress-shielding at 6-mm of dynamic displacement, the ratcheting mechanism in IM nails may clinically improve rates of fusion.

An original knee arthrodesis technique combining external fixator with Steinman pins direct fixation

INTRODUCTION

Knee arthrodesis may be the last possible option for infected total knee arthroplasty (TKA) patients and in revision cases involving severe bone loss and/or extensor mechanism damages. Success in these situations depends on achieving good fixation assembly stability. We report bone fusion results using a fixation technique combining cross-pinning by two Steinman pins with a single-frame external fixator. Remission of infection at long-term follow-up was an additional criteria assessed for those cases initially treated for sepsis.

HYPOTHESIS

This fixation modality improves fusion rates.

PATIENTS AND METHODS

In six of this series of eight patients (mean age: 59 years), surgery was performed in a context of infection: five cases of infected TKA, and one case of septic arthritis. In the other two cases, arthrodesis was respectively indicated for a severe post-traumatic stiffness compounded by extensor system rupture and for a fracture combined to a complete mechanical implant loosening. In three of the six infection cases, arthrodesis was performed as a single-stage procedure. All patients were operated on using the same technique: primary arthrodesis site stabilization by frontal cross-pinning with two Steinman pins, followed by installation of a sagittal external fixator frame. Results were assessed at a mean 8 year follow-up.

RESULTS

All the arthrodeses showed fusion at a mean 3.5 months (range: 2.5 to 6 months) postoperative delay without reintervention. Weight-bearing was resumed at 2 to 3 months. The external fixator was removed at a mean 5.2 months. No recurrence of infection was observed over a mean follow-up of 8.2 years (range: 1 to 15 years). Three complications occurred: one hematoma, managed surgically; one supracondylar fracture treated orthopedically; and one osteitis, managed by surgical curettage.

DISCUSSION

This knee arthrodesis technique proved effective, with no failures in this short series, especially in cases of primary infection. It is a reproducible means of osteosynthesis, with little subsequent morbidity. Fixation in two orthogonal planes seemed to provide the stability required to achieve bone fusion. This assembly avoids internal fixation, which is never risk-free in a context of primary sepsis.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Knee arthrodesis in failed total knee arthroplasty with severe osteolysis and ipsilateral long-stem total hip arthroplasty

We report a case of knee fusion after a failed total knee arthroplasty (TKA) with severe osteolysis including the epicondyle and ipsilateral total hip arthroplasty (THA) with long Wagner revision stem (Sulzer Orthopedics, Baar, Switzerland). The conventional devices for arthrodesis were unavailable in this case because of the long Wagner revision stem and poor bone stock. A connector was made between the long Wagner revision stem and an intramedullary nail (IM nail; Solco, Seoul, Korea). The custom-made connector was coupled with a femoral stem by cylindrical taper fit with additional cement augmentation and an intramedullary nail by screws. Osseous fusion was achieved without pain or instability.

Knee arthrodesis--a review

Knee arthrodesis as a primary treatment method for knee arthritis has re-emerged as a salvage procedure for failed knee arthroplasty. This article is an overview of indications, contraindications, principles, preoperative preparation and surgical techniques of knee arthrodesis. Their advantages and disadvantages are discussed together with results and complications. An attempt has also been made to incorporate technical considerations, the author's preferred surgical techniques and indications for the various methods of arthrodesis.

[Knee arthrodesis with a double mono-bar external fixators to salvage infected knee arthroplasty: retrospective analysis of 18 knees with mean seven-year follow-up]

PURPOSE OF THE STUDY

Knee arthrodesis is sometimes the only alternative to amputation in patients with an infected knee prosthesis or in major bone damage with loss of the extensor system. We hypothesized that arthrodesis with a double mono-bar external fixators would be a valid technical solution enabling simple fixation sufficiently rigid to control infection. The main objective of our study was to assess outcome with this technique in terms of fusion. The secondary objective was to check remission of the infection at last follow-up for the infection cases.

MATERIAL AND METHODS

Mean follow-up in this retrospective analysis of 18 knee arthroplasties in 17 patients was 85 months. Mean patient age was 65 years. All patients presented destruction of the extensor system associated with infection on a total knee arthroplasty (n=14) or joint destruction (n=4). The first operative stage involved insertion of a temporary external fixator using a lateral bar to align the limb. The infected knee prosthesis was then removed or a spacer was inserted. After avivement of the bone surfaces, compression was applied with an external fixator using an anterior bar. Early weight bearing was encouraged. The lateral fixator was removed at 45 days and the anterior fixator at bone healing.

RESULTS

First-intention fusion was achieved in 16 of the 18 knees at mean five months (range 3-8 months). Fusion was achieved in one case after surgical revision using a bone autograft. Nonunion persisted in the other patient. Mean time to removal of the anterior fixator was 7.5 months (range 6-12 months). Remission of infection was noted at last follow-up in all patients with infection.

DISCUSSION

This technique provides effective treatment for infected knee prostheses or major joint destruction with loss of the extensor mechanism. Joint fusion limits function but is a better solution than above knee amputation. The rigid fixation achieved with two single-bar fixators positioned perpendicularly enables rapid weight bearing, a capital element for these often bedridden elderly patients with multiple co-morbidities. The essential element for fusion is a solid fixation. The use of external fixators also avoids implanting material in septic tissues. Associated with medical treatment for the infection we have been able to achieve complete remission of infection in all patients who underwent arthrodesis for an infected knee arthroplasty.