Domenico Tigani

Two-stage reimplantation for periprosthetic knee infection: Influence of host health status and infecting microorganism

BACKGROUND Two-stage revision is the gold standard treatment of TKA infection; nevertheless various factors may influence the success rate. The aim of our study was to assess the impact of the number of patient comorbidities together with virulence of infectious organism on prognosis of two-stage revision procedure in chronic peri-prosthetic knee infection; moreover we tried to demonstrate correlation between the presence of positive culture during re-implantation and re-infection rate. METHODS Thirty-eight cases of two-staged revision procedures for infected total knee arthroplasty were prospectively followed. The presence of high virulence microorganisms on the culture result and the number (more than three) of comorbidities were used as major risk factors. All cases were divided into three groups: Group 1 (10 patients without major risk factors), Group 2 (18 patients with only one major risk factor), Group 3 (10 patients with both of major risk factors). RESULTS After a mean follow-up of 65months (range 24-139months), there was infection recurrence in nine cases: four re-infections occurred with the same organism while five patients had re-infection with a different organism. Recurrence was higher in Group 3 (33% of the cases), lower in Group 2 (12% of the cases), whereas no infection occurred in Group 1. Finally in case of positive intraoperative cultures recurrence rate was 83%, whereas when specimens were negative we had only 12.5% of re-infections. CONCLUSIONS Even if standard protocol of two-stage revision has demonstrated good results when treating low-virulence infections or patients without associated risk factors, its application to more challenging condition cannot be assumed. LEVEL OF EVIDENCE Level IV, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.

Interlocking nail for femoral shaft fractures: is dynamization always necessary?

A series of 179 closed femoral fractures treated by static interlocking nailing (Grosse-Kempf nail) was reviewed to evaluate the effect of dynamization on the time to bony union. In 75 patients, dynamization was performed whereas in 104 the implant was left static. Union occurred in 178 patients. We observed one infection. Time to union was significantly shorter in the static group (103 days) compared to the dynamized group (126 days).RésuméUne série de 179 fractures fémorales fermées traitées par enclouage verrouillé centro-médullaire statique (clou de Grosse-Kempf) a été examinée pour évaluer l’effet de la dynamisation sur le temps de consolidation osseuse. Chez 75 malades la dynamisation a été exécuté, alors que pour 104 l’implant était laissé statique. La consolidation s’est effectuée chez 178 malades. Nous avons observé une infection. Le temps de consolidation était significativement plus court dans le groupe statique (103 jours) comparé au groupe dynamisé (126 jours).

Vancomycin and meropenem in acrylic cement: elution kinetics of in vitro bactericidal action

The Authors present a paper with a dual goal: in vitro evaluation of the elution of vancomycin and monitoring of its bactericidal action when the antibiotic is used in acrylic cement. Discs of cement with different concentrations of vancomycin alone or combined with meropenem were prepared. To assess the elution of vancomycin the discs were kept in physiological solution and periodically sampled for five weeks. The bactericidal action was assessed by putting the antibiotic discs in contact with colonies of Staphylococcus, Enterococcus, Pseudomonas and Escherichia coli. Two combinations of antibiotic-loaded cement were tested: the first one to act as a spacer and the second to stabilise the revision prosthesis.

The potential role of metal ion release as a marker of loosening in patients with total knee replacement: A COHORT STUDY

We investigated the role of ion release in the assessment of fixation of the implant after total knee replacement and hypothesised that ion monitoring could be a useful parameter in the diagnosis of prosthetic loosening. We enrolled 59 patients with unilateral procedures and measured their serum aluminium, titanium, chromium and cobalt ion levels, blinded to the clinical and radiological outcome which was considered to be the reference standard. The cut-off levels for detection of the ions were obtained by measuring the levels in 41 healthy blood donors who had no implants. Based on the clinical and radiological evaluation the patients were divided into two groups with either stable (n = 24) or loosened (n = 35) implants. A significant increase in the mean level of Cr ions was seen in the group with failed implants (p = 0.001). The diagnostic accuracy was 71% providing strong evidence of failure when the level of Cr ions exceeded the cut-off value. The possibility of distinguishing loosening from other causes of failure was demonstrated by the higher diagnostic accuracy of 83%, when considering only patients with failure attributable to loosening. Measurement of the serum level of Cr ions may be of value for detecting failure due to loosening when the diagnosis is in doubt. The other metal ions studies did not have any diagnostic value.

Total knee arthroplasty in patients with poliomyelitis

We performed a retrospective chart and radiograph review of 10 patients with a history of poliomyelitis involving a limb that subsequently underwent primary total knee arthroplasty between 2000 and 2008. One posterior stabilized (PS), two condylar constrained (CCK), and seven rotating hinge (RHK) prostheses belonging to the same system were implanted. Eight patients were followed for a minimum of 2 years (mean 4.3 years, range 2 to 8.5 years); one patient required revision for prosthesis infection. The last patient was followed for just six months reporting excellent pain relief, and without complications. American Knee Society Score (AKSS) improved postoperatively in all eight patients with at least 2 years follow-up. The improvement was more marked for the knee score, which increased from a mean of 37 points preoperatively (range 20 to 51) to 75.7 points postoperatively (range 50 to 92); for the functional score the mean increase was only 15.8 points, from a mean of 38.5 points (range 20 to 70) to 54.3 points (range 20 to 80) after the intervention. One patient had a recurrence of the recurvatum deformity after implanting a CCK prosthesis. We found that a rotating hinge prosthesis that allowed hyperextension was suitable treatment for patients with knee osteoarthritis and polio as this compensated for loss of quadriceps power.

Preliminary experience with electromagnetic navigation system in TKA.

Accuracy of implant positioning and precise reconstruction of leg alignment offers the best way to achieve good long-term results in total knee arthroplasty. Computer instrumentation was developed to improve the final position of the component and restore the mechanical axis. Current navigation systems use either optical or electromagnetic tracking. The advantage of the Electromagnetic (EM) navigation system is that no line-of-sight issues are present. However, special iron-free instruments are required. This report analyzes the postoperative radiological results of 32 knees treated using an EM system. All the measurements were recorded using software able to subtend angles automatically by five physicians, three radiologist and two orthopedic residents not involved with the surgery. Each radiograph was measured three times, in random order, and at delayed intervals. We found an ideal alignment for the mechanical axis (180+/-3 degrees ) in 30 out of 32 cases, whereas all the patients achieved a value of 90 degrees +/-3 degrees for both femoral and tibial frontal component angles. An apparently over-corrected implant position for the sagittal femoral component was reported, with a mean value of 11.2 degrees +/-3.6. The mean position of the tibial component was 90.6 degrees +/-2.8; just four measurements were outside of the +/-3 degrees of the desired value. EM is safe and there were no complications related to this system. An almost perfect correlation was found between the mechanical axis value of the EM navigation system (179.8 degrees +/-1.8) and the median value of the all reviewers (180.3 degrees +/-1.9) with a difference of 0.5 degrees .

Trabecular metal patella in total knee arthroplasty with patella bone deficiency.

This study evaluates results following patellar resurfacing using trabecular metal (TM) patella in marked deficiency or weakness of patellar bone that precludes patellar resurfacing with a standard cemented patellar button. Ten consecutive patients undergoing primary (3 cases) or revision (7 cases) total knee arthroplasty with patella augmentation were evaluated at a mean follow-up of 45 months (range 18-65). Nine patients had marked patellar bone deficiency and one had had previous patellectomy. No intra-operative complications occurred. There was no displacement of the patellar component and no patellar fractures when at least 50% of bone contact was possible. We observed loosening of the patella augmentation 17 months after the index procedure only in the case of previous patellectomy. When bone was present the fixation appeared excellent by radiographic evaluation already at 3 to 6 months after surgery; afterward bone contact was uniform in the peripheral regions in both lateral and Merchant radiographic views without signs of loosening. Finally, the mean Knee Society scores improved in all patients.

Management of Bone Loss in Primary and Revision Knee Replacement Surgery

Total knee arthroplasty (TKA) often deal with bone defect localized in areas corresponding to tibial and femoral articular surfaces, a condition that is often observed in revision knee prosthetic surgery but occasionally in primary arthroplasty of the knee too. Such intraoperative situation, could create a main problem in maintaining proper alignment of the implant components and in establishing sufficient bone stock to achieve a stable boneimplant interface. The surgeon must assess the degree of complexity preoperatively and intraoperatively and have a broad armamentarium available during surgery. Multiple surgical options are available to repair or reconstruct the loss of bone, these include: bone cement, bone grafts, metal augments and custom-made implants. Principles to consider in bone loss management are knee-related (particularly defect size and location, ligament stability, limb alignment) and patient-related (age, body mass index, activity level, life expectancy).

Total Knee Arthroplasty for Post-Traumatic Proximal Tibial Bone Defect: Three Cases Report

Bone stock deficiency in primary as well as in revision total knee arthroplasty (TKA) represents a difficult problem to surgeon with regard to maintaining proper alignment of the implant components and in establishing a stable bone-implant interface. Different surgical procedures are available in these situations, for instances the use of bone cement, prosthetic augments, custom implant, and wire mesh with morsellized bone grafting and structural bone allograft. Structural allograft offers a numerous advantages as easy remodeling and felling cavitary or segmental defects, excellent biocompatibility, bone stock restoration and potential for ligamentous reattachment. In this article we report a short term result of three cases affected by severe segmental medial post/traumatic tibial plateau defect in arthritic knee, for which massive structural allograft reconstruction and primary total knee replacement were carried. The heights of the bone defect were between 27-33 mm and with moderate medio-lateral knee instability. Pre-operative AKS score in three cases was 30, 34 and 51 points consecutively and improved at the last follow-up to 83, 78 and 85 consecutively. No acute or chronic complication was observed. Last radiological exam referred no signs of prosthetic loosening, no secondary resorption of bone graft and well integrated graft to host bone. These results achieved in our similar three cases have confirmed that the structural bone allograft is a successful biological material to restore hemi-condylar segmental tibial bone defect when total knee replacement is indicated.

Opening-wedge high tibial osteotomy: a seven - to twelve-year study.

PURPOSE medial opening-wedge osteotomy is a widely performed procedure used to treat moderate isolated medial knee osteoarthritis. Historically, the literature has contained reports showing satisfactory mid-term results when accurate patient selection and precise surgical techniques were applied. This study was conducted to investigate the clinical and radiographic seven- to twelve-year results of opening-wedge high tibial osteotomy in a consecutive series of patients affected by varus knee malalignment with isolated medial compartment degenerative joint disease. METHODS we reviewed a case series of 147 medial opening-wedge high tibial osteotomies at an average follow-up of 9.5 years. Endpoints for evaluation included the reporting of adverse effects, radiographic evidence of bone union, radiographic changes in the correction angle during union, and clinical and functional final outcomes. RESULTS good or excellent results were obtained in 94% of the cases: the patients reported no major complications related to the opening-wedge high tibial osteotomy surgical technique, bone graft resorption, implant choice or postoperative rehabilitation protocol. At final follow-up, the average hip-knee angle was 4° of valgus without major loss of correction during the healing process. A statistically significant change in the patellar height was detected postoperatively, with a trend towards patella infera. CONCLUSIONS medial opening-wedge high tibial osteotomy is still a reliable method for correcting varus deformity while producing stable fixation, thus allowing satisfactory stability, adequate bone healing and satisfactory mid- to long-term results. LEVEL OF EVIDENCE Level IV, therapeutic cases series.