Two-stage revision for periprosthetic joint infection after hip and knee arthroplasty.

Aims: Histology is widely used for diagnosis of persistent infection during reimplantation in two-stage revision hip and knee arthroplasty, although data on its utility remain scarce. Therefore, this study aims to assess the predictive value of permanent sections at reimplantation in relation to reinfection risk, and to compare results of permanent and frozen sections. Methods: We retrospectively collected data from 226 patients (90 hips, 136 knees) with periprosthetic joint infection who underwent two-stage revision between August 2011 and September 2021, with a minimum follow-up of one year. Histology was assessed via the SLIM classification. First, we analyzed whether patients with positive permanent sections at reimplantation had higher reinfection rates than patients with negative histology. Further, we compared permanent and frozen section results, and assessed the influence of anatomical regions (knee versus hip), low- versus high-grade infections, as well as first revision versus multiple prior revisions on the histological result at reimplantation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), chi-squared tests, and Kaplan-Meier estimates were calculated. Results: Overall, the reinfection rate was 18%. A total of 14 out of 82 patients (17%) with positive permanent sections at reimplantation experienced reinfection, compared to 26 of 144 patients (18%) with negative results (p = 0.996). Neither permanent sections nor fresh frozen sections were significantly associated with reinfection, with a sensitivity of 0.35, specificity of 0.63, PPV of 0.17, NPV of 0.81, and accuracy of 58%. Histology was not significantly associated with reinfection or survival time for any of the analyzed sub-groups. Permanent and frozen section results were in agreement for 91% of cases. Conclusion: Permanent and fresh frozen sections at reimplantation in two-stage revision do not serve as a reliable predictor for reinfection.

Long-Term Results after Chiari Pelvic Osteotomy in the Skeletally Immature and the Role of the Anti-Chiari Effect.

Several authors observed a loss of correction after performing Chiari pelvic osteotomy (CPO) in young patients. Hence, the aim of this study was to answer two questions: (1) Does the Chiari pelvic osteotomy affect the development of the acetabulum in skeletally immature patients in the long term? (2) Is there any evidence of the previously described "Anti-Chiari" effect after a mean follow-up of 36 years? Data from 21 patients (27 hips) undergoing CPO before the age of 16 years were clinically assessed, and the evolution of radiological parameters over time was analyzed. The mean age at CPO was 11.2 years (±3; 4.4-15.7). The 20- and 30-year survival rates of the CPO were 100% and 92.6%, respectively. Mean postoperative medialization was 54% (±18; 23-99). The average osteotomy angle was 11° (±7; 2-28). No significant changes were found for the center-edge angle (CEA) and acetabular index (AI) over time; the angle of Idelberger and Frank (ACM) almost reached normal values at follow-up (FU); for the acetabular-head index (AHI), a slight shift toward the initial situation could be detected. The morphology of the acetabulum remained unchanged over time. The "Anti-Chiari effect" seems to be primarily caused by insufficient coverage of the femoral head rather than damage to the apophysis due to surgery.

Long Term Results of a Rotating Hinge Total Knee Prosthesis With Carbon-Fiber Reinforced Poly-Ether-Ether-Ketone (CFR-PEEK) as Bearing Material.

Background: The use of rotating hinge (RH) prostheses for severe primary as well as revision arthroplasty is widely established. Due to the steadily increasing number of RH prostheses, we aimed to assess the complication frequencies, complication types and clinical outcomes of a modern RH hinge prosthesis using a new bearing material with a minimum follow-up of 7 years. Methods: Fifty-six consecutive patients who received the EnduRo® RH prosthesis using carbon-fiber reinforced poly-ether-ether-ketone (CFR-PEEK) as bearing material were included in this prospective study: 21 patients (37.5%) received the prosthesis as a primary total knee arthroplasty (TKA) and 35 patients (62.5%) underwent revision total knee arthroplasties (rTKA). Clinical and radiographic examinations were performed preoperatively, postoperatively after three and 12 months and annually thereafter. Clinical scores were documented for each patient. Competing risk analysis was assessed with respect to indication and failure mode. Results: Knee Society Score (KSS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS) and range of motion (ROM) improved significantly compared to preoperative values (p < 0.0001). The overall cumulative incidence for revision surgery was 23.6% at 7 years and the cumulative incidence for complications associated with failure of the prothesis was 5.6% at 7 years, respectively. Complications occurred more frequently in the revision group (p = 0.002). Conclusion: The evaluated RH prosthesis provided reliable and durable results for a minimum follow-up of 7 years. Prosthesis survival was successful considering the complexity of the cases. The use of this RH system in primary patients showed high survival rates and long-term functional outcomes and clinical outcomes proved to be satisfying in both revision and primary cases. No adverse events were associated with the new bearing material CFR-PEEK.

Results in the surgical treatment of aneurysmal bone cysts - A retrospective data analysis.

BACKGROUND: Aneurysmal bone cysts (ABC) are benign tumors mostly occurring in children and young adults. Different open and minimal invasive surgical approaches have been proposed for the treatment of ABCs and yet no consensus is defined to date. The aim of this study was to retrospectively review data of a large single center series of ABCs with patients treated by open curettage with or without filling of the cavity or en-bloc resection. Questions/purposes We asked: (1) What was the local recurrence rate of ABC after surgical treatment at our institution? (2) What were positive or negative predictors for local recurrence? (3) Was there a benefit from adjuvant burring, phenolization or filling, respectively? (4) Where there changes in recurrence free survival in different time periods of primary surgery? METHODS: By retrospective data analysis of the Vienna Bone and Soft Tissue Tumor Registry, 123 patients surgically treated for primary aneurysmal bone cysts were identified. After exclusion of 33 patients (27%) due to a postoperative follow up below one year, 90 patients who were treated for primary ABCs between 1986 and 2009 were evaluated. These included 50 males and 40 females with a mean age of 16 years (SD 10 years; range: 2 to 51 years). The mean follow-up was 99 months. (SD 72 months, range: 13 to 329 months) RESULTS: Curettage was performed in 84 patients, while 45 patients received adjuvant phenolization. Local recurrence occurred in 28 patients after a mean time of 16 months, with a corresponding local recurrence free survival (RFS) of 83% after one year, 77% after 2 years and 66% after 5 years. ABCs located in hands and feet (p=0.044) showed a superior RFS, while younger patients (p=0.001) displayed an inferior RFS. Regarding adjuvant surgical techniques, mechanical cavity burring (p=0.004) and filling with autologous cancellous bone graft (p=0.024) showed protective effects on RFS. Patients treated between 1986 and 1999 (n=47) had a higher RFS than patients treated between 2000 and 2009 (n=43, p=0.011), as surgeons and surgical indications changed over time. CONCLUSION: Although curettage, burring, phenolization and reconstruction with bone grafts came with a relatively high risk of local recurrence, open surgery is still justified in aggressively growing ABCs of critical localizations. LEVEL OF EVIDENCE: IV; therapeutic study.

Proximal femoral reconstruction with modular megaprostheses in non-oncological patients.

INTRODUCTION: Multiple revision hip arthroplasties and critical trauma might cause severe bone loss that requires proximal femoral replacement (PFR). The aim of this retrospective study was to analyse complication- and revision-free survivals of patients who received modular megaprostheses in an attempt to reconstruct massive non-neoplastic bone defects of the proximal femur. Questions/purposes (1) What were general complication rates and revision-free survivals following PFR? (2) What is the incidence of complication specific survivals? (3) What were risk factors leading to a diminished PFR survival? MATERIALS AND METHODS: Twenty-eight patients with sufficient follow-up after receiving a modular proximal femoral megaprosthesis were identified. The indications for PFR included prosthetic joint infection (PJI), periprosthetic fracture, aseptic loosening, non-union and critical femoral fracture. Complications were grouped according to the ISOLS-classification of segmental endoprosthetic failure by Henderson et al. RESULTS: Overall, the complication-free survival was 64.3% at one year, 43.2% at five years and 38.4% at ten years, with 16 patients (57%) suffering at least one complication. Complications were dislocation in eight patients (29%), PJI in 6 patients (21%), periprosthetic fracture in five patients (18%), and aseptic loosening in six patients (21%). Prosthesis stem cementation showed a lower risk for revision in a cox proportional hazard model (95% CI 0.04-0.93, HR 0.2, p = 0.04). CONCLUSION: PFR with modular megaprostheses represents a viable last resort treatment with high complication rates for patients with severe proximal femoral bone loss due to failed arthroplasty or critical fractures. In revision arthroplasty settings, PFR cementation should be advocated in cases of impaired bone quality.

Does a Competing Risk Analysis Show Differences in the Cumulative Incidence of Revision Surgery Between Patients with Oncologic and Non-oncologic Conditions After Distal Femur Replacement?

BACKGROUND: Distal femur replacement is frequently used for limb salvage after bone tumor resections. It is also used in patients with severe bone loss because of traumatic conditions or revision TKA. Some studies on distal femur replacement reported on revision-free survival without distinguishing between patients with oncologic diagnoses and those without, although these patients might be incomparable because of their differences in important patient- and disease-specific characteristics. This may lead to an inaccurate and undifferentiated interpretation of the results of survival analyses. QUESTIONS/PURPOSES: (1) What is the overall cumulative incidence of revision surgery after cemented and cementless distal femoral replacement, as determined with a competing risk analysis? (2) Does the cumulative incidence of revision surgery change over time? (3) Are there differences in the cumulative incidence of revision surgery between patients with oncologic conditions and those without who are treated with cemented or cementless distal femoral replacement? METHODS: A total of 403 patients were possible candidates for distal femoral replacement. Of these, 56 patients elected to undergo different procedures, 83 were excluded because an expendable growing prosthesis was implanted, and 28 were lost to follow-up. Therefore, 229 patients who underwent distal femoral replacement for oncologic or non-oncologic reasons between 1983 and 2016 were retrospectively included in this study. The type of fixation method (cemented or cementless) was obtained from the patients' medical records, operation reports, and radiographic analyses from plain radiographs. All radiographs were standardized and obtained at standard time intervals in our institution. No algorithm regarding the fixation approach was followed. According to our data, patients receiving cementless fixation were younger and therefore likely to be more active than those receiving cemented fixation. The median follow-up duration of the overall cohort was 85 months (range 0.1-391 months). Patients who died or had revision surgery before the 2-year minimum follow-up interval were adequately considered using competing risk calculation. The reasons for revision surgery were classified using the classification system proposed by the International Society for Limb Salvage. A competing risk analysis was performed to estimate the cumulative incidence function of revision, accounting for death as a competing event. To evaluate the influence of potential prognostic factors, including diagnosis (oncologic versus non-oncologic), fixation (cemented versus cementless), year of distal femoral replacement, age, and sex on the occurrence of revision surgery, univariate and multivariable Fine and Gray models were applied. RESULTS: The competing risks analysis revealed cumulative incidences of revision surgery for any cause (Types 1 to 5) of 26% (95% CI, 20.3%-31.9%) at 12 months, 37.9% (95% CI, 31.3%-44.4%) at 24 months, 52.6% (95% CI, 45.1%-59.5%) at 5 years, and 58.2% (95% CI, 50.1%-65.4%) at 10 years for all patients. Rotating hinge-type prostheses showed a lower cumulative incidence of revision surgery (41.6%; 95% CI, 31.8%-51%) than fixed-hinge prostheses did (64%; 95% CI, 50.5%-74.5% ) at 5 years (Gray's test: p = 0.01). According to the multivariate Fine and Gray model, the year of surgery did not have any effect on the risk of revision surgery (1994 to 2003: hazard ratio 0.70; 95% CI, 0.46-1.07); 2004 to 2016: HR 0.83; 95% CI, 0.52-1.34; p = 0.26). The multivariate analysis, adjusted for disease, sex, age, cementation, and year of surgery, revealed a difference in the risk of revision surgery between patients with oncologic disease and those with non-oncologic disease (HR 0.44 for oncologic versus non-oncologic; 95% CI, 0.22-0.87; p = 0.02) and a reduction in the risk of overall revision with cemented fixation in patients with oncologic disease (HR 0.53; 95% CI, 0.29-0.98; p = 0.03). CONCLUSION: This study indicates that even with newer implants, there was a high incidence of revision surgery after distal femoral replacement. According to our analysis, patients with oncologic diagnoses have a lower likelihood of revision when the stem is cemented whereas the type of fixation did not impact patients with non-oncologic diagnoses. Because of differences in patient demographics (age, etiology of disease, and use of chemotherapy) and outcomes of fixation, oncologic and non-oncologic patients should be analyzed separately in survival studies about distal femoral replacement. LEVEL OF EVIDENCE: Level III, therapeutic study.

Distal femoral reconstruction following failed total knee arthroplasty is accompanied with risk for complication and reduced joint function.

BACKGROUND: Substantial bone loss following failed total knee arthroplasty (TKA) represents a major challenge in revision arthroplasty, that can require distal femoral reconstruction (DFR). In this study, we aimed to assess the clinical outcome and the complication frequencies of individuals who underwent DFR with modular megaprostheses. Additionally, we aimed to compare functional outcome measures after DFR in these sophisticated cases to an age-matched control group of total knee prostheses to quantify the potential loss of function. METHODS: A retrospective chart review of 30 consecutive patients after DFR from 1997 to 2017 with a mean age of 74.38 years (± 10.1) was performed. Complications were classified according to the Henderson classification. Knee Society Score (KSS) was calculated and range of motion (ROM) was assessed. RESULTS: Thirteen (43.3%) patients had at least one complication requiring revision surgery. Revision-free survival was 74.8% at one year, 62.5% at three and 40.9% at 10 years post-op. Soft-tissue failure complications were found in three (10.0%) patients, aseptic loosening in four (13.3%) patients, structural failure in one (3.3%) patient and infection in eight (26.6%) patients. Of those with infection, five (16.6%) experienced ongoing prosthetic joint infection and three (10.0%) developed new infection after distal femur reconstruction. Patients with DFR achieved 69.3% of KSS pain score, 23.1% KSS function score and 76.2% of ROM compared to patients with primary TKA. CONCLUSIONS: DFR after failed TKA represents a treatment procedure with high risk for complication in this particular group. Despite the prospect of rapid postoperative mobilization, reduced functionality, range of motion and mobilization have to be considered when choosing this treatment option.