Endoprosthetic reconstruction of massive bone defects has become the reconstruction method of choice after limb-sparing resection of primary malignant tumors of the long bones. Given the improved ...survival rates of patients with extremity bone sarcomas, an increasing number of patients survive but have prosthetic complications over time. Several studies have reported on the outcome of first endoprosthetic complications. However, no comprehensive data, to our knowledge, are available on the likelihood of an additional complication and the associated risk factors, despite the impact of this issue on the affected patients.
(1) What are the types and timing of complications and the implant survivorship free from revision after the first complication? (2) Does survivorship free from repeat revision for a second complication differ by anatomic sites? (3) Is the type of first complication associated with the risk or the type of a second complication? (4) Are patient-, tumor-, and treatment-related factors associated with a higher likelihood of repeat revision?
Between 1993 and 2015, 817 patients underwent megaprosthetic reconstruction after resection of a tumor in the long bones with a single design of a megaprosthetic system. No other prosthetic system was used during the study period. Of those, 75% (616 of 817) had a bone sarcoma. Seventeen patients (3%) had a follow-up of less than 6 months, 4.5% (27 of 599) died with the implant intact before 6 months and 43% (260 of 599 patients) underwent revision. Forty-three percent of patients (260 of 599) experienced a first prosthetic complication during the follow-up period. Ten percent of patients (26 of 260) underwent amputation after the first complication and were excluded from further analysis. Second complications were classified using the classification of Henderson et al. to categorize surgical results. Briefly, this system categorizes complications as wound dehiscence (Type 1); aseptic loosening (Type 2); implant fractures or breakage and periprosthetic fracture (Type 3); infection (Type 4); and tumor progression (Type 5). Implant survival curves were calculated with the Kaplan-Meier method and compared using the log-rank test. Hazard ratios (HR) were estimated with their respective 95% CIs in multivariate Cox regression models.
A second complication occurred in 49% of patients (115 of 234) after a median of 17 months (interquartile range IQR 5 to 48) after the surgery for the first complication. The time to complication did not differ between the first (median 16 months; IQR 5 to 57) and second complication (median 17 months; IQR 5 to 48; p = 0.976). The implant survivorship free from revision surgery for a second complication was 69% (95% CI 63 to 76) at 2 years and 46% (95% CI 38 to 53) at 5 years. The most common mode of second complication was infection 39% (45 of 115), followed by structural complications with 35% (40 of 115). Total bone and total knee reconstructions had a reduced survivorship free from revision surgery for a second complication at 5 years (HR 2.072 95% CI 1.066 to 3.856; p = 0.031) compared with single joint replacements. With the numbers we had, we could not show a difference between the survivorship free of revision for a second complication based on the type of the first complication (HR 0.74 95% CI 0.215 to 2.546; p = 0.535). We did not detect an association between total reconstruction length, patient BMI, and patient age and survivorship free from revision for a second complication. Patients had a higher risk of second complications after postoperative radiotherapy (HR 1.849 95% CI 1.092 to 3.132; p = 0.022) but not after preoperative radiotherapy (HR 1.174 95% CI 0.505 to 2.728; p = 0.709). Patients with diabetes at the time of initial surgery had a reduced survivorship free from revision for a second complication (HR 4.868 95% CI 1.497 to 15.823; p = 0.009).
Patients who undergo revision to treat a first megaprosthetic complication must be counseled regarding the high risk of future complications. With second complications occurring relatively soon after the first revision, regular orthopaedic follow-up visits are advised. Preoperative rather than postoperative radiotherapy should be performed when possible. Future studies should evaluate the effectiveness of different approaches in treating complications considering implant survivorship free of revision for a second complication.
Level III, therapeutic study.
Intraoperative cultures are important in the diagnosis and targeted treatment of periprosthetic joint infection (PJI). Positive cultures at reimplantation during a two-stage exchange are discussed as ...a risk factor for reinfection. The aim of this study is the investigation of the incidence and risk factors for positive cultures during reimplantation.
We retrospectively identified 204 patients (111 knees, 93 hips) who were treated between 2012 and 2016 for PJI using a two-stage exchange protocol at a median follow-up of 42 months. PJI was diagnosed using the criteria of the musculoskeletal infection society (MSIS) of 2011. All cultural findings from first and second stage surgery were recorded. The primary endpoint was revision for infection. Risk factors for positive cultures and reinfection were analyzed.
During reimplantation 25% (51/204) of patients had at least one positive culture, in 19.1% (39/204) only a single culture. Patients with culture-negative infections had a higher risk for positive cultures at reimplantation (HR 2.946 (95% CI 1.247-6.961), P = .014) and patients with infected total hip arthroplasty (THA) (HR 3.547 (95% CI 1.7-7.4), P = .001). Patients with positive cultures during reimplantation had a higher risk for reinfection (HR 2.27 (95% CI 1.181-4.363), P = .014) as well as patients with a single positive culture (HR 2.421 (95% CI 1.139-5.143), P = .021).
As positive cultures are common and increase reinfection risk irrespective of their numbers, longer antibiotic therapy following reimplantation can be an option. Single positive cultures in reimplantation surgery should not be considered contamination.
Endoprosthetic reconstruction of massive bone defects has become the reconstruction method of choice after limb-sparing resection of primary malignant tumors of the long bones. Given the improved ...survival rates of patients with extremity bone sarcomas, an increasing number of patients survive but have prosthetic complications over time. Several studies have reported on the outcome of first endoprosthetic complications. However, no comprehensive data, to our knowledge, are available on the likelihood of an additional complication and the associated risk factors, despite the impact of this issue on the affected patients.
(1) What are the types and timing of complications and the implant survivorship free from revision after the first complication? (2) Does survivorship free from repeat revision for a second complication differ by anatomic sites? (3) Is the type of first complication associated with the risk or the type of a second complication? (4) Are patient-, tumor-, and treatment-related factors associated with a higher likelihood of repeat revision?
Between 1993 and 2015, 817 patients underwent megaprosthetic reconstruction after resection of a tumor in the long bones with a single design of a megaprosthetic system. No other prosthetic system was used during the study period. Of those, 75% (616 of 817) had a bone sarcoma. Seventeen patients (3%) had a follow-up of less than 6 months, 4.5% (27 of 599) died with the implant intact before 6 months and 43% (260 of 599 patients) underwent revision. Forty-three percent of patients (260 of 599) experienced a first prosthetic complication during the follow-up period. Ten percent of patients (26 of 260) underwent amputation after the first complication and were excluded from further analysis. Second complications were classified using the classification of Henderson et al. to categorize surgical results. Briefly, this system categorizes complications as wound dehiscence (Type 1); aseptic loosening (Type 2); implant fractures or breakage and periprosthetic fracture (Type 3); infection (Type 4); and tumor progression (Type 5). Implant survival curves were calculated with the Kaplan-Meier method and compared using the log-rank test. Hazard ratios (HR) were estimated with their respective 95% CIs in multivariate Cox regression models.
A second complication occurred in 49% of patients (115 of 234) after a median of 17 months (interquartile range IQR 5 to 48) after the surgery for the first complication. The time to complication did not differ between the first (median 16 months; IQR 5 to 57) and second complication (median 17 months; IQR 5 to 48; p = 0.976). The implant survivorship free from revision surgery for a second complication was 69% (95% CI 63 to 76) at 2 years and 46% (95% CI 38 to 53) at 5 years. The most common mode of second complication was infection 39% (45 of 115), followed by structural complications with 35% (40 of 115). Total bone and total knee reconstructions had a reduced survivorship free from revision surgery for a second complication at 5 years (HR 2.072 95% CI 1.066 to 3.856; p = 0.031) compared with single joint replacements. With the numbers we had, we could not show a difference between the survivorship free of revision for a second complication based on the type of the first complication (HR 0.74 95% CI 0.215 to 2.546; p = 0.535). We did not detect an association between total reconstruction length, patient BMI, and patient age and survivorship free from revision for a second complication. Patients had a higher risk of second complications after postoperative radiotherapy (HR 1.849 95% CI 1.092 to 3.132; p = 0.022) but not after preoperative radiotherapy (HR 1.174 95% CI 0.505 to 2.728; p = 0.709). Patients with diabetes at the time of initial surgery had a reduced survivorship free from revision for a second complication (HR 4.868 95% CI 1.497 to 15.823; p = 0.009).
Patients who undergo revision to treat a first megaprosthetic complication must be counseled regarding the high risk of future complications. With second complications occurring relatively soon after the first revision, regular orthopaedic follow-up visits are advised. Preoperative rather than postoperative radiotherapy should be performed when possible. Future studies should evaluate the effectiveness of different approaches in treating complications considering implant survivorship free of revision for a second complication.
Level III, therapeutic study.
Purpose
There has been a renewed interest in the repair of the torn anterior cruciate ligament (ACL). Purpose of this study was to evaluate the functional outcome of arthroscopic ACL repair with ...additional suture augmentation (SA), hypothesizing that isolated ACL ruptures would yield superior patient-reported outcome measures (PROMs) compared to those with concomitant meniscal and/or ligamentous injuries.
Methods
This is a retrospective analysis of 93 consecutive patients (67 female, median age 42 years) who underwent arthroscopic ACL repair with SA between January 2017 and March 2019 for an acute traumatic ACL tear confirmed by magnetic resonance imaging (MRI). Patients with pre- or intraoperative mid-substance or distal ACL tears and/or poor tissue quality of the ACL remnant were not considered for ACL repair but were scheduled for an ACL reconstruction with a tendon autograft. In patients who underwent ACL repair with SA, the SA construct was proximally stabilized with a flip-button and distally with a suture anchor. Surgery was preferably performed on the day of injury and all surgeries were performed by the same surgeon. Postoperative rehabilitation included partial weight-bearing (20 kg) for 6 weeks and immobilization in a brace limited at 90-degrees of knee flexion for 4 weeks. Patient-reported outcome measures (PROMs) were determined using International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Lysholm Score (LS), Tegner Activity Score (TS) and Forgotten Joint Score (FJS). Knee-laxity was assessed using the KT-1000 arthrometer (Med Metrics Corp. Inc., San Diego, USA).
Results
Nine patients underwent revision surgery for a traumatic re-tear (four patients) and chronic instability (five patients) and were excluded from further functional analysis. Functional results of 77 patients (54 female) with a median age of 44 years (IQR 33–51) on the day of surgery were available for follow-up after a median time of 35 months (IQR 33–44). Concomitant injuries were observed in 66 Patients (86%), meniscal injuries in 43 patients (55%) and ligamentous injuries in 50 patients (65%). Median interval from injury to surgery was 1 day (IQR 0–1) with 81% (62/77) of patients being treated within 24 h of injury. The median IKDC was 92 (IQR 86–99), the median LS was 95 (IQR 86–100), the median pre-traumatic TS was 7 (IQR 6–7), the median post-traumatic TS was 6 (IQR 5–7) with a non-significant median difference (TS
Diff
) of 0 (IQR 0–1). The median FJS was 95 (IQR 78–98). KT-1000 measurements were available in 34 of 77 patients with a median postoperative laxity compared to the uninjured side of 1 mm (IQR 0–2). Interval from injury to surgery, patients’ age, body mass index (BMI), knee laxity and concomitant ligamentous or meniscal injuries had no statistically significant impact on postoperative PROMs (n.s.).
Conclusion
Following arthroscopic ACL repair with SA good-to-excellent functional results were observed. However, a failure rate of 10% cannot be neglected and warrants further attention. Concomitant injuries to the meniscus and/or collateral ligaments do not seem to be associated with inferior PROMs.
Level of evidence
Level IV.
Purpose
The purpose of the study was to determine the long-term survivorship, functional outcomes of a single-design condylar constrained (CCK) TKA in primary and revision cases as well as to assess ...specific risk factors for failure. It was hypothesized that primary CCK TKA had a better survival than revision knees.
Methods
One hundred and forty three patients who underwent revision TKA (
n
= 119) or complex primary TKA (
n
= 24) using a single-design condylar constrained knee system (Genesis CCK, Smith & Nephew) performed at a single institution between 1999 and 2008 were retrospectively included. The median follow-up amounted to 11.8 years (IQR 10.3–14.4). Implant survivorship was analyzed using Kaplan–Meier survival estimates and multivariate Cox regression analysis to identify risk factors for failure. Function was determined using the Oxford Knee Score (OKS).
Results
The implant survival was 86.4% after five, 85.5% after ten and 79.8% at 15 years. A reduced implant survivorship was found in males (HR 5.16,
p
= 0.001), smokers (HR 6.53,
p
= 0.004) and in obese patients (HR 2.26,
p
= 0.095). Patients who underwent primary TKA had a higher revision-free implant survivorship compared to revision TKA at 15 years (100% vs. 76%,
p
= 0.036). The main cause for re-revision was infection in 10% of all revision TKA performed with the CCK design included, while no case was revised for instability.
The median OKS was 39 (IQR 35–44) in 102 patients available for long-term functional outcome.
Conclusion
CCK implants are associated with excellent long-term survival when used in primary TKA; however, survival was worse when used during revision TKA. Males, smokers, obese patients and are at higher risk for revision. While instability and aseptic loosening were rare, infection remains a major concern.
Level of evidence
Level IV, retrospective observational study.
Introduction
Two-stage revision is a frequently chosen approach to treat chronic periprosthetic joint infection (PJI). However, management of recurrent infection after a two-stage exchange remains ...debated and the outcome of a repeat two-stage procedure is unclear. This study investigates the success rates of repeat two-stage exchange arthroplasty and analyzes possible risk factors for failure.
Materials and methods
We retrospectively identified 55 patients (23 hips, 32 knees) who were treated with repeat resection arthroplasty and planned delayed reimplantation for recurrent periprosthetic joint infection between 2010 and 2019 after a prior two-stage revision at the same institution. The minimum follow-up was 12 months with a median follow-up time of 34 months (IQR 22–51). The infection-free survival, associated revision surgeries, and potential risk factors for further revision were analyzed using Kaplan–Meier survival curves and comparative non-parametric testing.
Results
78% (43/55) underwent reimplantation after a repeat implant removal. Of those who completed the second-stage surgery, 37% (16/43) underwent additional revision for infection and 14% (6/55) underwent amputation. The reinfection-free implant survivorship amounted to 77% (95% CI 64–89%) after 1 year and 38% (95% CI 18–57%) after 5 years. Patients with a higher comorbidity score were less likely to undergo second-stage reimplantation (median 5 vs. 3,
p
= 0.034). Furthermore, obese patients (
p
= 0.026, Fisher’s exact test) and diabetics (
p
< 0.001, log-rank test) had a higher risk for further infection. Most commonly cultures yielded polymicrobial growth at the repeat two-stage exchange (27%, 15/55) and at re-reinfection (32%, 9/28). Pathogen persistence was observed in 21% (6/28) of re-reinfected patients.
Conclusion
The success rates after repeat two-stage exchange arthroplasty are low. Patients must be counseled accordingly and different modes of treatment should be considered.
In the field of local application of antimicrobials, a number of novel drugs and/or new drug delivery systems have been developed in recent years. The present study aimed to investigate ...hydroxyapatite cement (HAC) as a carrier for vancomycin in the treatment of chronic osteomyelitis due to
Staphylococcus aureus strains with various mechanisms of resistance. The release of vancomycin from standard test cylinders was determined in vitro and the efficacy of the delivery system was measured in vivo using a rabbit model of chronic osteomyelitis.
First, powdered HAC was mixed with vancomycin at 80, 160 and 240
mg/g. After hardening, formed cylinders were eluted in phosphate buffer and antibiotic release was measured by agar diffusion. High levels of release (1512±318 to 1937±336
μg/ml) were obtained for 12 to 20 days depending on the dosage of vancomycin.
Additionally, bone infection was induced in the tibia of 30 New Zealand white rabbits by injecting either a methicillin-resistant
S. aureus strain (MRSA) or a
S. aureus strain with a small colony variant (SCV) phenotype. After 3 weeks (chronic infection), all animals were treated by debridement. Moreover, group 1 (challenged with SCVs) and group 2 (challenged with MRSA) were treated by filling the marrow with HAC alone, whereas in groups 3 (SCVs) and 4 (MRSA) the marrow was filled with HAC/vancomycin (160
mg/g). After 6 weeks all animals were sacrificed.
At 3 weeks, pathogens were detected in 24 of 30 animals. All swabs of the control groups, positive for
S. aureus on day 21, were also positive on day 42 and
S. aureus strains recovered were shown to be clonal to the strains used for induction of osteomyelitis. By contrast, no growth was found in the treatment group following 7 days of incubation in BHI bouillon. HAC/vancomycin-treated animals showed no histological evidence of infection on day 42. In the other groups, different stages of chronic osteomyelitis were found histologically. No local or systemic side effects due to HAC or vancomycin were seen.
HAC is an effective carrier material for antibiotic compounds even in refractory infections due to MRSA or
S. aureus SCVs.
Deep infection of megaprostheses remains a serious complication in orthopedic tumor surgery. Despite the use of systemic and local antibiotic prophylaxis the reported infection rate is between 5% and ...35%. Silver-coated medical devices proved their effectiveness in reducing infections. The objective of this study was to examine in vivo the antimicrobial efficacy and possible side-effects of a silver-coated megaprosthesis. In a first study, 30 rabbits (15 titanium versus 15 silver-coated Mutars
®—endoprostheses) were infected with
Staphylococcus aureus. In a second study, toxicological side effects were analyzed in 10 rabbits with a silver-coated megaprosthesis.
The silver group showed significantly (
p<0.05) lower infection rates (7% versus 47%) in comparison with the titanium group. Measurements of the C-reactive-protein, neutrophilic leukocytes, rectal temperature and body weight showed significant (
p<0.05) lower signs of inflammation in the silver group. The analysis of the silver concentration in blood (median 1.883
ppb) and in organs (0.798–86.002
ppb) showed elevated silver concentrations without pathologic changes in laboratory parameters and without histological changes of organs. In conclusion, the new silver-coated Mutars
®—megaprosthesis resulted in reduced infection rates without toxicological side effects, suggesting that this prosthesis might be a promising device in tumor surgery exhibiting antimicrobial activity.
Purpose
This study first analyzes implant survival of this single design modular rotating hinge knee and identifies potential risk factors for failure and evaluates joint function using the ...postoperative WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) score, active flexion and extension deficit.
Methods
131 prostheses implanted for failure of prior total knee arthroplasty (
n
= 120) or complex primary procedures (
n
= 11) using a single modular implant (MUTARS—modular universal tumor and revision system GenuX, Implantcast, Buxtehude, Germany) between 2006 and 2014 including 73 patients treated for periprosthetic joint infection with a two-stage revision protocol were retrospectively identified. Implant survival was assessed using the Kaplan–Meier method; potential risk factors were identified using the log-rank test, as well as non-parametric analysis. Postoperative function was assessed using the WOMAC and measurement of range of motion.
Results
After a median follow-up of 62 months, 37 implants required implant revision (28%). Five-year survival was 69.7% 95% CI (confidence interval) 60.9–78.5 with periprosthetic (re-) infection being the main cause for failure (15%), followed by aseptic loosening (9%). In cases of periprosthetic infection, infection-free survival was 83% at 5 years (95% CI 74–92) with twelve patients suffering reinfection (16%).While body mass index (
p
= 0.75), age (
p
= 0.16) or indication for rotating hinge knee arthroplasty (
p
= 0.25) had no influence on survival, Charlson comorbidity score (CCI) (
p
= 0.07) and number of previous revision surgeries (
p
= 0.05) correlated with implant failure. There was trend (
p
= 0.1) for improved survival in fully cemented implants. Mean postoperative WOMAC was 127(range 55–191), 11 patients (15%) had limited knee extension.
Conclusions
Rotating hinge total knee arthroplasty using a single modular implant shows acceptable survival rates and function compared to previous studies with (re-)infection being the most relevant mode of failure. Patients with a high CCI and multiple previous surgeries are at increased risk for failure.
Level of evidence
Retrospective cohort study, III.
Novel treatment strategies are needed to cure disseminated Ewing sarcoma. Primitive neuroectodermal features and a mesenchymal stem cell origin are both compatible with aberrant expression of the ...ganglioside antigen G(D2) and led us to explore G(D2) immune targeting in this cancer.
We investigated G(D2) expression in Ewing sarcoma by immunofluorescence staining. We then assessed the antitumour activity of T cells expressing a chimeric antigen receptor specific for G(D2) against Ewing sarcoma in vitro and in vivo.
Surface G(D2) was detected in 10 out of 10 Ewing sarcoma cell lines and 3 out of 3 primary cell cultures. Moreover, diagnostic biopsies from 12 of 14 patients had uniform G(D2) expression. T cells specifically modified to express the G(D2)-specific chimeric receptor 14. G2a-28ζ efficiently interacted with Ewing sarcoma cells, resulting in antigen-specific secretion of cytokines. Moreover, chimeric receptor gene-modified T cells from healthy donors and from a patient exerted potent, G(D2)-specific cytolytic responses to allogeneic and autologous Ewing sarcoma, including tumour cells grown as multicellular, anchorage-independent spheres. G(D2)-specific T cells further had activity against Ewing sarcoma xenografts.
G(D2) surface expression is a characteristic of Ewing sarcomas and provides a suitable target antigen for immunotherapeutic strategies to eradicate micrometastatic cells and prevent relapse in high-risk disease.
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