Are silver-coated megaprostheses superior to uncoated megaprostheses in managing chronic end-stage periprosthetic hip and knee infection?

INTRODUCTION: Outcomes for silver coated megaprostheses (SC-MP) used in cases of end-stage periprosthetic joint infection (PJI) have not been clearly defined. Although attractive, concerns over implant longevity and the risk of infection relapse exist among the scientific community. Therefore, we sought to investigate the effect of silver coating in lower-extremity MPs used in such difficult-to-treat scenarios. The study's primary hypothesis was that the periprosthetic infection control rate would be higher in patients with silver-coated implants. MATERIALS AND METHODS: Non-interventional retrospective study with a historical comparison group. We identified all consecutive end-stage hip and knee PJI cases at our center managed with exchange arthroplasty using a silver-coated megaprosthesis from January 2016 to March 2021, these cases were compared with a historical cohort of end-stage PJI cases managed with uncoated megaprostheses. The main outcome studied was infection control rate. Secondarily, we analyzed the short-to-medium-term survivorship of this type of silver-coated implant. RESULTS: Fifty-nine megaprostheses used in cases of end-stage PJI were included in this study. We identified 30 cases of chronic hip or knee PJI in which a silver-coated modular megaprosthesis was implanted. Our non-coated megaprosthesis (NC-MP) historical group included 29 patients. Both groups had similar demographic characteristics. We found no statistically significant differences in infection control rate (80% vs. 82.8%, p = 0.47) or implant survivorship (90% vs. 89.65%, p = 1) after a mean follow-up for SC-MP of 46.43 months, and 48 months for the non-coated MP group. In relapsed cases, there were no differences in infection eradication after DAIR (66% SC-MP vs. 60% NC-MP success rate, p = 1). During the follow-up we observed one case of skin argyria without further repercussion. CONCLUSION: We were unable to confirm our initial hypothesis that use of silver-coated implants in end-stage PJI scenarios may be associated with better outcomes in terms of infection control or implant survivorship.

Sequential repeated tibial tubercle osteotomy in a two-stage exchange strategy: a superior approach to treating a chronically infected knee arthroplasty?

PURPOSE: Surgical approach can impact the reliability of the debridement after a chronic total knee periprosthetic joint infection (PJI), a factor of utmost importance to eradicate the infection. The most adequate knee surgical approach in cases of PJI is a matter of debate. The purpose of this study was to determine the influence of performing a tibial tubercle osteotomy (TTO) in a two-stage exchange protocol for knee PJI treatment. METHODS: Retrospective cohort study examining patients managed with two-stage arthroplasty due to chronic knee PJI (2010-2019). Performance and timing of the TTO were collected. Primary end-point was infection control with a minimum FU of 12 months and according to internationally accepted criteria. Correlation between TTO timing and reinfection rate was reviewed. RESULTS: Fifty-two cases were finally included. Overall success (average follow-up: 46.2 months) was 90.4%. Treatment success was significantly higher among cases addressed using TTO during the second stage (97.1% vs. 76.5%, p value 0.03). Only 4.8% of the patients relapsed after performing a sequential repeated TTO, that is, during both first and second stages, compared to 23.1% cases in which TTO was not done (p value 0.28). No complications were observed among patients in the TTO group with a significant decrease in soft tissue necrosis (p: 0.052). CONCLUSION: Sequential repeated tibial tubercle osteotomy during a two-stage strategy is a reasonable option and offers high rates of infection control in complex cases of knee PJI with a low rate of complications.

Two-stage strategy in end-stage hip periprosthetic joint infection: utility of industrially prefabricated custom-made antibiotic spacers.

PURPOSE: Use of prefabricated mobile spacers in end-stage cases of hip periprosthetic joint infection (HPJI) is hindered when large bone defects exist. In such cases, prefabricated custom-made antibiotic spacers (P-CMAS) offer an alternative. Such spacers are individually designed according to the size and anatomical characteristics of the bone defect. The purpose of this study is to describe and evaluate the use of such patient-specific spacers in a two-stage strategy to treat end-stage HPJI cases, and to report on clinical outcomes. METHODS: A retrospective study identified all patients with end-stage HPJIs from January 2015 through December 2019, treated using a P-CMAS. Primary outcome: infection eradication rate. Secondary outcomes: spacer-related complications and patient satisfaction. Minimum follow-up: 12 months after the second-stage surgery. RESULTS: A total of 7 end-stage cases (mean of 6.7 previous surgical procedures) were included. Mean bone defect size was 191.57 (range 47-304) mm. Polymicrobial infection was detected in 42.86% of these cases. During the spacer stage there were no periprosthetic fractures, spacer dislocations or breakages, nor spacer-drug-related complications. All patients proceeded with the second stage uneventfully, with an average time between stages of 178 (range 119-326) days. In 5 cases a total femur arthroplasty was the reconstructive procedure performed. After a mean follow-up of 27.29 (range 14-49) months the infection was clinically eradicated in all patients, despite their difficult-to-treat scenarios. CONCLUSIONS: Industrially custom-made spacers offer an effective and safe option in performing 2-stage exchange arthroplasty in cases of end-stage HPJI with extensive bone defects.

Preliminary Outcomes of a Staged Percutaneous Retrograde Prefabricated Gentamicin-coated Intramedullary Nail to Manage Complications after Ankle Fusion through Tibial Bone Transport.

Aim: Distal tibial injuries combining bone loss, articular destruction and infection can be treated through distraction osteogenesis combined with ankle fusion. Bone transport is not without complications. This study investigates our preliminary results using a retrograde prefabricated gentamicin-coated nail (ETN PROtect®) to treat complications after infected bone defects of the distal tibial were managed by ankle arthrodesis and distraction osteogenesis. Materials and methods: This is a retrospective case series study. All consecutive patients with bone transport complications after ankle arthrodesis and distraction osteogenesis who were subsequently operated on using a retrograde ETN PROtect® nail were analysed. The cases occurred between 2017 and 2020. The primary objective was to report on the resolution of the clinical problem and the risk of deep infection after nail implantation. Results: Five patients have included: two docking site non-unions, two regenerated bone fractures and one hypotrophic regenerated bone. These complications were resolved in all patients (5/5, 100%). A painless, stable and plantigrade ankle arthrodesis was achieved in all cases. No patient developed a local infection or required nail removal (mean follow-up: 35.2 months). The mean LEFS score was 46.8 ± 13.8 and the mean knee ROM was 112 ± 12.7°. All patients tolerated full weight-bearing. All patients were very satisfied with the procedure (mean SAPS score was 93.8 points). Conclusion: The staged retrograde nailing technique using the ETN PROtect® nail may represent an effective and safe treatment for bone transport complications in high-infection-risk patients. Furthermore, the technique allows simultaneous achievement of ankle arthrodesis. The patients had good functional outcomes and were satisfied with the procedure. Clinical significance: This strategy of using retrograde gentamicin-coated tibial nails offers a solution to resolve bone transport complications while simultaneously achieving functional ankle arthrodesis. How to cite this article: Pujol O, Vicente M, Castellanos S, et al. Preliminary Outcomes of a Staged Percutaneous Retrograde Prefabricated Gentamicin-coated Intramedullary Nail to Manage Complications after Ankle Fusion through Tibial Bone Transport. Strategies Trauma Limb Reconstr 2023;18(3):155-162.

Outcomes of two circular external fixation systems in the definitive treatment of acute tibial fracture related infections.

INTRODUCTION: Acute tibial fracture-related infection (FRI) is one of the most feared and challenging complications after a tibial fracture. The most appropriate treatment in this scenario is far from a resolved topic. Circular external fixators (CEFs) offer multiplanar control and minimize soft tissue injury using temporary implants far from the infected area. This study aimed to investigate the outcomes of two different types of CEFs (Ilizarov and hexapod) in the treatment of a series of acute tibial FRIs. MATERIAL AND METHODS: A retrospective study at two specialized limb reconstruction centres identified all patients with an acute tibial FRI (≤4 weeks after index procedure) definitively treated with a CEF from January 2015 to December 2020. PRIMARY OUTCOMES: fracture healing and infection eradication rate with a minimum FU of 12 months after frame removal. SECONDARY OUTCOMES: to investigate the differences between the two types of circular frames regarding final post-treatment deformity magnitude. RESULTS: We included 31 patients with acute tibial FRIs: 18 treated with hexapod-type and 13 with Ilizarov-type CEFs. Average age was 45.5±16.56 years. Fracture healing and infection eradication were achieved in all patients (31/31) after a mean follow-up of 24.7 months (range 12.1-55.3). Patients treated with an Ilizarov-type fixator presented shorter time to fracture union (5.5±2.2 months vs. 9.2±6.0 months; p-value 0.021) and shorter duration of external fixation (p-value 0.001). Regarding residual post-treatment deformity, the hexapod system presented significantly less residual coronal translation deformity (p-value 0.034) and better callus quality. Fixator-related complications were similar when comparing the two groups. No significant differences were seen in pain (p-value 0.25), RTW rate (35% vs. 45%; p-value 0.7) or functionality (p-value 0.4). CONCLUSIONS: Definitive circular external fixation is an excellent treatment for acute tibial FRI. Both Ilizarov and hexapod systems offer a very high rate of fracture healing and infection eradication. Although both presented very low radiological post-operative residual deformity, the hexapod system showed less residual coronal translation deformity and better callus quality.

Should we employ preoperative templating in hip hemiarthroplasty after femoral neck fracture? A nested case-control study.

INTRODUCTION: Dislocation following hip hemiarthroplasty is a serious complication. It remains unclear if acetabular morphology is associated with a higher risk of dislocation. The aim of our study was to investigate whether there are differences in hip morphology radiological parameters between patients who have suffered a dislocation episode, and those who have not suffered a dislocation. MATERIAL AND METHODS: Between January 2015 and December 2018, a nested case-control study was performed. From 707 patients who underwent hip hemiarthroplasty because of femoral neck fracture, 50 patients (50 hips) suffered an episode of dislocation. They were randomly matched with 94 patients (100 hips) without dislocation (ratio 1:2). Clinical data regarding demographics, medical comorbidities and surgical and radiological parameters were studied. RESULTS: Statistically significantly smaller lateral centre-edge angle (LCEA) and femoral offset (FO) and greater Tönnis angle were found in the dislocation group. No differences in acetabular angle were seen. Neurological impairment prevalence was statistically significantly higher in patients who suffered a dislocation (60% vs. 44%, p = 0.011). CONCLUSIONS: The current study suggests that a smaller LCEA and FO, a greater TA, and neurological impairment could be related to a higher risk of hip hemiarthroplasty dislocation after femoral neck fracture in the elderly. We consider that preoperative templating could be helpful in identifying abnormal parameters and carefully planning surgery could lead to changes in treatment strategy, such as choosing a dual-mobility total hip arthroplasty.

Three-stage limb salvage in tibial fracture related infection with composite bone and soft-tissue defect.

INTRODUCTION: Managing critical-sized tibial defects is one of the most complex challenges orthopedic surgeons face. This is even more problematic in the presence of infection and soft-tissue loss. The purpose of this study is to describe a comprehensive three-stage surgical protocol for the reconstruction of infected tibial injuries with combined bone defects and soft-tissue loss, and report the clinical outcomes. MATERIALS AND METHODS: A retrospective study at a specialized limb reconstruction center identified all patients with infected tibial injuries with bone and soft-tissue loss from 2010 through 2018. Thirty-one patients were included. All cases were treated using a three-stage protocol: (1) infected limb damage control; (2) soft-tissue coverage with a vascularized or local flap; (3) definitive bone reconstruction using distraction osteogenesis principles with external fixation. PRIMARY OUTCOMES: limb salvage rate and infection eradication. SECONDARY OUTCOMES: patient functional outcomes and satisfaction. RESULTS: Patients in this series of chronically infected tibias had been operated upon 3.4 times on average before starting our limb salvage protocol. The mean soft-tissue and bone defect sizes were 124 cm2 (6-600) and 5.4 cm (1-23), respectively. A free flap was performed in 67.7% (21/31) of the cases; bone transport was the selected bone-reconstructive option in 51.7% (15/31). Local flap failure rate was 30% (3/10), with 9.5% for free flaps (2/21). Limb salvage rate was 93.5% (29/31), with infection eradicated in all salvaged limbs. ASAMI bone score: 100% good/excellent. Mean VAS score was 1.0, and ASAMI functional score was good/excellent in 86% of cases. Return-to-work rate was 83%; 86% were "very satisfied" with the treatment outcome. CONCLUSION: A three-stage surgical approach to treat chronically infected tibial injuries with combined bone and soft-tissue defects yields high rates of infection eradication and successful limb salvage, with favorable functional outcomes and patient satisfaction.

Safety and effectiveness of vitamin D mega-dose: A systematic review.

INTRODUCTION: Supplementation with high doses of vitamin D, known as mega-dose or "stoss therapy," refers to administering high doses of vitamin D by oral or intramuscular route in short periods of time. In this sense, conducting a review to organize this knowledge in a single article will generate a helpful instrument for researchers working in this area and for health professionals who use this therapeutic tool. OBJECTIVE: To carry out a literature review on safety and efficacy (normalization of serum vitamin D level, and changes in the clinical picture) of vitamin D mega-dose use. METHODOLOGY: This is a systematic review of the literature searching data through the electronic banks of PubMed, Scielo, and LILACS, using the following keywords: "vitamin D," "mega-dose," "stoss therapy," "cholecalciferol," in different combinations. CONSORT questionnaire was used to assess the quality of the included studies. RESULTS: Of the 59 articles screened for this review, 10 were included in the review, studying patients with rickets, osteoporosis, and critically ill patients. Two studies compared the exact dosage of vitamin D by different routes of administration, and three studies compared different doses by the same route. All others studied vitamin D mega-dose versus placebo. Adverse effects were observed through the presence of hypercalcemia/hypercalciuria. Serum vitamin D levels were normalized between 70 and 100% of patients, and adverse effects ranged between 1.9 and 18.5%. CONCLUSION: The study demonstrated that vitamin D mega-dose therapy is effective in normalizing serum vitamin levels, and the toxicity assessed through adverse effects was low, with no expressive clinical significance. Despite this, there is still a need for further studies in the area to confirm the results found.

Reconstruction of infected post-traumatic bone defects of the distal femur with the CompressⓇ implant. Preliminary results of a staged non-biological strategy.

INTRODUCTION: Infected post-traumatic distal femur defects remain a therapeutic challenge. Non-biological reconstruction offers an option for avoiding complex biological knee arthrodesis procedures. The CompressⓇ implant is an alternative to the traditional distal femur stemmed megaprosthesis. The aim of this study is to analyse the first patients treated with a distal femur CompressⓇ prosthesis to manage massive infected post-traumatic defects of the distal femur with joint involvement. METHODS: We retrospectively reviewed all patients with massive infected defects of the distal femur where this implant was used in a two-stage strategy, together with an antibacterial coating hydrogel (DACⓇ). The specific protocol, microbiological data, clinical and radiological results, complications, functional results and prosthesis survivorship were determined. Follow-up was for a minimum of 12 months, or until implant removal. RESULTS: Ten patients (11 CompressⓇ implants) with a mean age of 52 years (range 35-73) were included. On average, patients had undergone 4.4 previous surgical procedures before index surgery. The mean bone defect was 14 cm (range 8-21). After a median follow-up of 27 months (range 12-50 months) no patient had presented with recurrence of the infection, and limb salvage was achieved in all cases. Two patients suffered aseptic loosening which required revision of the femoral component. The short-term survivorship of the implant in our series was 81.8% at 4 years, with all failures occurring in the first 7 months. After this 7-month time threshold, we encountered no further loosening. Regarding functional outcomes, patients had a mean knee ROM of -4/86, expressed high overall satisfaction with the procedure according to the SAPS scale, and had an average LEFS of 52.5% (40-72.5%). CONCLUSION: Non-biological reconstruction of the distal femur with the CompressⓇ implant is a valid option in selected patients with massive infected defects with joint involvement. Survivorship was high, with all loosening occurring in the first months after surgery-representing a failure in the osseointegration of the implant.

Current actual success rate of the two-stage exchange arthroplasty strategy in chronic hip and knee periprosthetic joint infection.

AIMS: The success rates of two-stage revision arthroplasty for infection have evolved since their early description. The implementation of internationally accepted outcome criteria led to the readjustment of such rates. However, patients who do not undergo reimplantation are usually set aside from these calculations. The aim of this study was to investigate the outcomes of two-stage revision arthroplasty when considering those who do not undergo reimplantation, and to investigate the characteristics of this subgroup. METHODS: A retrospective cohort study was conducted. Patients with chronic hip or knee periprosthetic joint infection (PJI) treated with two-stage revision between January 2010 and October 2018, with a minimum follow-up of one year, were included. Variables including demography, morbidity, microbiology, and outcome were collected. The primary endpoint was the eradication of infection. Patients who did not undergo reimplantation were analyzed in order to characterize this subgroup better. RESULTS: A total of 162 chronic PJIs were included in the study. After a mean follow-up of 57.3 months (12.1 to 115.7), 18 patients (11.1%) did not undergo reimplantation, due either to medical issues (10), the patient's choice (4), or death (4). When only considering those who underwent reimplantation, the success rate was 80.6%. However, when those who did not undergo reimplantation were included, the success rate dropped to 71.6%. Advanced age, American Society of Anesthesiologists grade ≥ III, McPherson's C host, and Gram-negative related PJI were independent risk factors for retention of the spacer. The mortality was higher in the non-reimplanted group. CONCLUSION: The real success rate of two-stage revision may not be as high as previously reported. The exclusion of patients who do not undergo reimplantation resulted in a 9% overestimation of the success rate in this series. Many comorbidity-related risk factors for retention of the spacer were identified, as well as higher death rates in this group. Efforts should be made to optimize these patients medically in order to increase reimplantation and success rates, while decreasing mortality. Cite this article: Bone Joint J 2020;102-B(12):1682-1688.

Uniplanar versus biplanar monolateral external fixator knee arthrodesis after end-stage failed infected total knee arthroplasty: a comparative study.

BACKGROUND: External fixator knee arthrodesis is a salvage procedure used primarily in cases of end-stage infected total knee replacement (iTKR). Stable fixation combined with bone-end compression is essential to achieve knee fusion, but providing sufficient stability can be challenging in the presence of severe bone loss. Our hypothesis is that using an external fixation biplanar configuration would bring about a fusion rate superior to that of a monolateral frame. METHODS: This study compares outcomes of biplanar external fixator knee fusion due to non-revisable iTKR with those of a historical cohort control study with patients managed with a monoplanar configuration. Primary endpoints were fusion rate, time to achieve bone fusion and infection eradication rate. Limb-length discrepancy, pain level, patient satisfaction and health-related quality of life were evaluated. RESULTS: A total of 29 knee fusion cases were included. In the biplanar group, infection was eradicated in 100% of the patients and fusion was achieved in all cases within an average of 5.24 months. In comparison, in the monolateral group, infection was eradicated in 86% of the cases and fusion was achieved in 81% of the patients after a mean of 10.3 months (p < 0.05). In both groups, postoperative pain was mild and patients expressed a high degree of satisfaction once fusion was achieved. CONCLUSIONS: According to our data, external fixation knee fusion is a useful limb-salvage procedure in end-stage cases of knee PJI. We conclude that a biplanar configuration can halve the time required to achieve solid bone fusion in such a complex scenario.

Vancomycin-Gentamicin Prefabricated Spacers in 2-Stage Revision Arthroplasty for Chronic Hip and Knee Periprosthetic Joint Infection: Insights Into Reimplantation Microbiology and Outcomes.

BACKGROUND: Second-stage positive cultures in 2-stage revision arthroplasty are a matter of concern, as their influence in outcomes is not clearly defined. We sought to study reimplantation microbiology when using vancomycin-gentamicin prefabricated cement spacers in hip and knee periprosthetic joint infection. The associations of second-stage positive cultures with treatment failures and patient-associated factors were analyzed. METHODS: We conducted a retrospective cohort study, examining patients managed with 2-stage revision arthroplasty due to knee or hip chronic periprosthetic joint infection between 2010 and 2017. Prefabricated vancomycin-gentamicin cement spacers were used during the spacer stage. Intraoperative microbiological culture results after the first and second stages were evaluated. The primary end point was infection eradication or relapse. RESULTS: A total of 108 cases were included (61 hips and 47 knees). And 22.2% of patients had ≥1 second-stage positive culture, while 9.3% had ≥2 positive samples. Overall success, at an average follow-up of 46.4 months, was 77.8%. Treatment failure was higher among cases with positive cultures (15.5% vs 45.8%, P < .01) regardless of the number of positive samples. Diabetes was identified as a risk factor for second-stage positive cultures (P = .03); use of cement loaded with extra antibiotics for spacer fixation showed a protective effect (P < .01). CONCLUSION: Second-stage positive cultures were related to a higher failure rate when using vancomycin-gentamicin cement spacers. Diabetes increased the likelihood of second-stage positive cultures. The use of extra-antibiotic-loaded cement for spacer fixation during the first stage showed a protective effect.

Causes and Frequencies of Reoperations After Endoprosthetic Reconstructions for Extremity Tumor Surgery: A Systematic Review.

BACKGROUND: Excision of bone tumors and endoprosthetic reconstruction allow patients early weightbearing and a potential functional advantage compared with amputation. These reconstructions do not restore the limb to normal status, however, and patients are subject to complications that may result in revision or loss of the limb. Because better understanding of these complications based on current information might help the patient and surgeon in decision-making, we undertook a systematic review of studies published on this topic. QUESTIONS/PURPOSES: (1) What are the primary modes and proportion of failure of tumor endoprostheses in patients undergoing reconstruction after excision of primary extremity bone sarcomas? METHODS: We systematically searched MEDLINE, Embase, and the Cochrane Library for all studies published from April 15, 1998, to April 15, 2018. Three reviewers independently reviewed studies reporting endoprosthetic reconstruction survival and events requiring revision for primary extremity bone tumors treated with endoprosthetic reconstruction for inclusion and performed independent data extraction. We excluded all studies with fewer than five patients, any systematic review/meta-analyses, and any study not reporting on primary extremity bone tumors. All discrepancies were resolved by the study's senior author. Data extracted from included studies were any reoperation event for wound dehiscence, any operative fixation for a pathologic fracture, and any revision of the primary endoprosthesis for implant wear or breakage, deep infection not amenable to prosthesis retention, or for local recurrence. We assessed the overall quality of the evidence with the Methodological Index for Non-Randomized Studies (MINORS) approach with a higher MINORS score representative of a more methodologically rigorous study with a total possible score of 16 points for noncomparative and 24 points for comparative studies. Forty-nine studies met criteria for inclusion from an initial search return of 904 studies, of which no studies were randomized controlled trials. From a total patient population of 2721, there was a mean followup of 93 months (range, 1-516 months) with loss to followup or death occurring in 447 of 2118 (21%) patients with six studies not providing loss to followup data. The mean MINORS score was 14 for prospective studies and 11 for retrospective studies. RESULTS: Overall, there were 1283 reoperations among the 2721 (47%) patients. Reoperation for mechanical endoprosthetic events (soft tissue dehiscence or periarticular soft tissue instability, aseptic loosening, or implant wear/fracture) occurred in 907 of 2721 (33%) patients. Aseptic loosening occurred at a mean of 75 months (range, 1-376 months) in 212 of 315 patients (67%). Deep infection requiring removal of the initial prosthesis occurred in 247 of 2721 (9%) patients with deep infection occurring at a mean of 24 months (range, 1-372 months) in the 190 infections (77%) with time to infection data available. Local recurrence rates requiring revision or amputation occurred in 129 (5%) of all patients. There was an overall primary endoprosthesis survival rate without any surgical reintervention of 63% among reporting studies at a mean of 79 months followup. CONCLUSIONS: Failures of endoprosthetic reconstructions after extremity tumor surgery are common, most often resulting from implant wear or fracture, aseptic loosening, and infection. Importantly, the aggregated data are the first to attempt to quantify the time to specific complication types within this patient population. Deep infection not amenable to endoprosthesis retention appears to occur approximately 2 years postoperatively in most patients, with aseptic loosening occurring most commonly at 75 months. Although endoprosthetic reconstruction is one of the most common forms of reconstruction after bone tumor resection, the quality of published evidence regarding this procedure is of low quality with high loss to followup and data quality limiting interstudy analysis. The quality of the evidence is low with high loss to followup and inconsistent reporting of times to reintervention events. Although the most common modes of endoprosthetic failure in this population are well known, creation of quality prospective, collaborative databases would assist in clarifying and informing important elements of the followup process for these patients. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Vascularized Periosteal Flaps Accelerate Osteointegration and Revascularization of Allografts in Rats.

BACKGROUND: Surgical reconstruction of large bone defects with structural bone allografts can restore bone stock but is associated with complications such as nonunion, fracture, and infection. Vascularized reconstructive techniques may provide an alternative in the repair of critical bone defects; however, no studies specifically addressing the role of vascularized periosteal flaps in stimulating bone allograft revascularization and osseointegration have been reported. QUESTIONS/PURPOSES: (1) Does a vascularized periosteal flap increase the likelihood of union at the allograft-host junction in a critical-size defect femoral model in rats? (2) Does a vascularized periosteal flap promote revascularization of a critical-size defect structural bone allograft in a rat model? (3) What type of ossification occurs in connection with a vascularized periosteal flap? METHODS: Sixty-four rats were assigned to two equal groups. In both the control and experimental groups, a 5-cm critical size femoral defect was created in the left femur and then reconstructed with a cryopreserved structural bone allograft and intramedullary nail. In the experimental group, a vascularized periosteal flap from the medial femoral condyle, with a pedicle based on the descending genicular vessels, was associated with the allograft. The 32 rats of each group were divided into subgroups of 4-week (eight rats), 6-week (eight rats), and 10-week (16 rats) followup. At the end of their assigned followup periods, the animals were euthanized and their femurs were harvested for semiquantitative and quantitative analysis using micro-CT (all followup groups), quantitative biomechanical evaluation (eight rats from each 10-week followup group), qualitative confocal microscopic, backscattered electron microscopic, and histology analysis (4-week and 6-week groups and eight rats from each 10-week followup group). When making their analyses, all the examiners were blinded to the treatment groups from which the samples came. RESULTS: There was an improvement in allograft-host bone union in the 10-week experimental group (odds ratio [OR], 19.29 [3.63-184.50], p < 0.05). In contrast to control specimens, greater bone neoformation in the allograft segment was observed in the experimental group (OR [4-week] 63.3 [39.6-87.0], p < 0.05; OR [6-week] 43.4 [20.5-66.3], p < 0.05; OR [10-week] 62.9 [40.1-85.7], p < 0.05). In our biomechanical testing, control samples were not evaluable as a result of premature breakage during the embedding and assembly processes. Therefore, experimental samples were compared with untreated contralateral femurs. No difference in torsion resistance pattern was observed between both groups. Both backscattered electron microscopy and histology showed newly formed bone tissue and osteoclast lacunae, indicating a regulated process of bone regeneration of the initial allograft in evaluated samples from the experimental group. They also showed intramembranous ossification produced by the vascularized periosteal flap in evaluated samples from the experimental group, whereas samples from the control group showed an attempted endochondral ossification in the allograft-host bone junctions. CONCLUSIONS: A vascularized periosteal flap promotes and accelerates allograft-host bone union and revascularization of cryopreserved structural bone allografts through intramembranous ossification in a preclinical rat model. CLINICAL RELEVANCE: If large-animal models substantiate the findings made here, this approach might be used in allograft reconstructions for critical defects using fibular or tibial periosteal flaps as previously described.

Septic Nonunion Caused by Mycobacterium canariasense: A Case Report.

CASE: A 43-year-old former drug user presented with a mycobacterium-caused septic nonunion of the humeral shaft. The patient had undergone 2 previous surgeries for a hematogenous fracture-related infection due to Staphylococcus aureus. The procedures had included debridement, double-plate osteosynthesis, and placement of a gentamicin-loaded bone substitute. Culture specimens produced growth of Mycobacterium canariasense. Because the microbiological diagnosis was obtained after the patient had been discharged, no antibiotic treatment could be prescribed. Nevertheless, solid bone fusion was observed in the most recent outpatient examination. CONCLUSION: This case illustrates the importance of considering atypical pathogens in patients who are immunoincompetent. To the best of our knowledge, this is the first reported case of septic nonunion caused by M. canariasense.

Preliminary results using patient-specific 3d printed models to improve preoperative planning for correction of post-traumatic tibial deformities with circular frames.

BACKGROUND: Preoperative planning for circular external fixators is considered vital towards achieving the best results for complex post-traumatic tibial deformities, and patient-specific 3D printed (3DP) models were used here as a planning aid. The main goal was to investigate the fidelity of the preoperative planning process, by assessing the potential to reduce operative time and determining the need to adjust pre-constructed frames intra-operatively. PATIENTS AND METHODS: Nine patients (10 limbs) underwent treatment for post-traumatic tibial complications using circular external fixation. These were compared to 10 similar cases where a 3DPM was not used as a pre-operative planning aide (Control group). Patient-specific models of affected bones were printed, and preoperative planning was performed using conventional techniques and Hexapod-assisted software. Detailed planning in a virtual procedure determined osteotomy levels and identified sites for wires and half-pins. The prototype of the external fixator was locked in this optimized configuration, removed from the model, and sterilized prior to the actual procedure. RESULTS: Nine patients with 10 limbs were treated for complications following tibial fractures. Seven were infected non-unions, and three cases were malunions. For all cases a CT based 3DP model of the full tibia was used in the preoperative planning stage. Image analysis required a mean of 1.7 h, with an average of 14.9 h to 3D print each model. In the control group (without a 3D model), the mean surgical time was 329 min (180-680). The mean surgical time in the 3DPM group was only 172.4 min (72-240), (p = 0.024), reducing the surgery time by 48%. For the 3DPM group it was not necessary to modify the preassembled frame in any case, while in the Control group, the pre-constructed frame required intra-operative modifications in 8 of the 10 cases (p = 0.0007). CONCLUSION: Using patient-specific 3D models has allowed us to carry out meticulous preoperative planning sessions, eliminating the need to modify or alter the frame assembly in the operating room, saving substantial surgical time and enabling a more precise design of the apparatus. This was especially useful in multiplanar deformities and for the spatial configuration of the foot support, talus ring, and ankle ring.

Use of modular megaprosthesis in managing chronic end-stage periprosthetic hip and knee infections: Is there an increase in relapse rate?

BACKGROUND: Bone loss is a common problem in periprosthetic joint infection (PJI) scenarios. Modular megaprosthesis (MP) could offer a limb salvage solution in such situations. Concerns about risk of infection relapse, reinfection and implant longevity exist regarding MP use in cases of chronic PJI, rather than standard implants. We therefore sought to analyze our results with MP use in chronic PJI cases. METHODS: We performed a retrospective analysis of 29 MP patients. Inclusion criteria were the use of this type of modular megaimplant for reconstruction of segmental bone defects in chronically infected lower-extremity arthroplasties (hip or knee) and a minimum follow-up of 18 months. We evaluated the primary outcome of infection control or recurrence. The MPs were classified into 3 groups, according the bone segment replaced (proximal femur, distal femur or total femur). We further analyzed complications, pain, patient satisfaction and functional results. RESULTS: Mean age was 75 years; mean follow-up was 48 months (range 18-82). The most frequently involved pathogens were coagulase-negative staphylococci (62%). Polymicrobial infection was detected in 7 patients. Twenty-eight patients were managed with a two-stage approach. The infection-free rate at the end of follow-up was 82.8% (24 of 29 patients). Aside from infection relapse, the most frequent complication was dislocation. Final-point survival rate was 91.2% (CI 68.1-97.8). Clinical outcome data and satisfaction results were acceptable. CONCLUSION: According our data, MP is a useful tool in treating end-stage PJI cases, achieving acceptable eradication, satisfaction and implant survivorship rates.