A new biarticular cement spacer technique for infected total hip and knee arthroplasty with massive bone loss.

INTRODUCTION: The management of massive femoral bone defects following prosthetic infection remains a surgical challenge, particularly when the entire femur is affected. METHODS: We present the first results of a new biarticular cement spacer with antibiotic technique using a cephalomedullary nail for the treatment of infected hip arthroplasty involving complete femoral bone loss. RESULTS: 5 patients with a minimum follow-up of 1 year were included. In all cases 2-stage replacement due to hip periprosthetic infection was carried out, with the need for a biarticular complete femoral spacer in view of the magnitude of the bone defect. The infection was resolved in all patients, with no complications (spacer fracture or dislocation) associated to spacer use, and the patients were all able to maintain the sitting position with active knee movements between the 2 surgical stages. Improvement with respect to preoperative functional status was observed in all cases, as evidenced by the Harris Hip Score (HHS) (from 24.2 to 73; p < 0.001) and 12-Item Short-Form Health Survey (SF-12) (from 16.8 to 33.2; p = 0.001), with a lessened need for walking aids. DISCUSSION: The described technique offers a possible solution to a number of complications observed with the use of spacers in massive defects, affording greater patient comfort and autonomy while waiting to receive total femoral replacement.

Patient-Specific Instrument Can Improve Functional and Radiographic Results during Learning Curve for Oxford Unicompartmental Knee Arthroplasty.

The true value of use of patient-specific instrumentation (PSI) systems by inexperienced surgeons during their learning curve to improve the clinical and radiographic outcome of unicompartmental knee arthroplasty (UKA) has not been previously studied. Fifty patients with a mean age of 64.3 years undergoing surgery for Oxford UKA were prospectively divided into two groups. Twenty-five patients were operated on by a surgeon with no prior experience in UKA using a PSI system and the other 25 patients by an experienced surgeon using a conventional procedure. Patients were scored using joint range of motion (ROM), the Knee Society Score (KSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the 12-item Short-Form (SF-12) before and 3 months and 2 years after surgery. Impact of use of PSI was measured by comparing clinical and radiographic outcome, complications, and implant survival. No evidence of poorer clinical outcome was seen in any subscale of KSS, KOOS, and SF-12 for inexperienced surgeons using PSI (p = 0.45, p = 0.32, and p = 0.61, respectively). No difference was found between the two procedures in precision of radiographic alignment of components (p = 0.53). No complication occurred in any group. PSI may improve precision of component alignment during the learning curve of surgeons, thus achieving functional results similar to those of more experienced surgeons using a conventional procedure.

Microencapsulation of rifampicin: A technique to preserve the mechanical properties of bone cement.

Two-stage exchange with antibiotic-loaded bone cement spacers remains the gold standard for chronic periprosthetic joint infection (PJI). Rifampicin is highly efficient on stationary-phase staphylococci in biofilm; however, its addition to PMMA to manufacture spacers prevents polymerization and reduces mechanical properties. Isolation of rifampicin during polymerization by microencapsulation could allow manufacturing rifampicin-loaded bone cement maintaining elution and mechanical properties. Microcapsules of rifampicin with alginate, polyhydroxybutyratehydroxyvalerate (PHBV), ethylcellulose and stearic acid (SA) were synthesized. Alginate and PHBV microcapsules were added to bone cement and elution, compression, bending, hardness, setting time and microbiological tests were performed. Repeated measures ANOVA and Bonferroni post-hoc test were performed, considering a p < 0.05 as statistical significance. Bone cement specimens containing alginate microcapsules eluted more rifampicin than PHBV microcapsules or non-encapsulated rifampicin over time (p < 0.012). Microencapsulation of rifampicin allowed PMMA to preserve mechanical properties in compression and bending tests. Cement with alginate microcapsules showed similar behavior in hardness tests to control cement over the study period (73 ± 1.68HD ). PMMA with alginate microcapsules exhibited the largest zones of inhibition in microbiological tests. Statistically significant differences in mean diameters of zones of inhibition between PMMA loaded with alginate-rifampicin (p = 0.0001) and alginate-PHBV microcapsules (p = 0.0001) were detected. Rifampicin microencapsulation with alginate is the best choice to introduce rifampicin in PMMA preserving mechanical properties, setting time, elution, and antimicrobial properties. The main applicability of this study is the opportunity for obtaining rifampicin-loaded PMMA by microencapsulation of rifampicin in alginate microparticles, achieving high doses of rifampicin in infected tissues, increasing the successful of PJI treatment. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:459-466, 2018.

Total femur arthroplasty for revision hip failure in osteogenesis imperfecta: limits of biology.

Osteogenesis imperfecta (OI) is a rare congenital disease characterized by alterations in bone quality, with susceptibility to fractures, instability, deformities, and osteoarthrosis. Prosthetic surgery in these patients is associated with an abnormally high rate of implant failures. On the other hand, abnormal bone fragility adds to the complexity of revision surgery in such individuals-thus representing a genuine challenge for the orthopaedic surgeon. We present a case of femoral reconstruction in a patient with OI and prosthetic loosening after reconstruction secondary to femoral septic pseudoarthrosis. Intramedullary total femoral reconstruction was carried out after exceeding the biological reconstruction limits. This is the first reported instance of the use of an intramedullary total femur arthroplasty as salvage technique in an OI patient. This technique should be considered when we have exceeded biological limits for femoral fixation.

Intraoperative radiotherapy for extremity soft-tissue sarcomas: can long-term local control be achieved?

BACKGROUND: Intraoperative electron-beam radiation therapy (IOERT) during limb-sparing surgery has the advantage of delivering a single high boost dose to sarcoma residues and surgical bed area near to radiosensitive structures with limited toxicity. Retrospective studies have suggested that IOERT may improve local control compared to standard radiotherapy and we aimed to demonstrate this theory. Therefore, we performed an observational prospective study to determine (1) if it is possible to achieve high local control by adding IOERT to external-beam radiation therapy (EBRT) in extremity soft-tissue sarcomas (STS), (2) if it is possible to improve long-term survival rates, and (3) if toxicity could be reduced with IOERT MATERIALS AND METHODS: From 1995-2003, 39 patients with extremity STS were treated with IOERT and postoperative radiotherapy. The median follow-up time was 13.2 years (0.7-19). Complications, locoregional control and survival rates were collected. RESULTS: Actuarial local control was attained in 32 of 39 patients (82%). Control was achieved in 88% of patients with primary disease and in 50% of those with recurrent tumors (p = 0.01). Local control was shown in 93% of patients with negative margins and in 50% of those with positive margins (p = 0.002). Limb-sparing was achieved in 32 patients (82%). The overall survival rate was 64%. 13% of patients had grade ≥3 acute toxicity, and 12% developed grade ≥3 chronic toxicity. CONCLUSION: IOERT used as a boost to EBRT provides high local control and limb-sparing rates in patients with STS of the extremities, with less toxicity than EBRT alone.

Does a new implant design with more physiological kinematics provide better results after knee arthroplasty?

BACKGROUND: Improved knee kinematics is one of the major goals to obtain better satisfaction after total knee arthroplasty. This study examined whether a guided motion knee design improves functional outcome and satisfaction as compared to a conventional design. METHODS: In a retrospective manner, from January 2005 to December 2008, patients with two different kinematic TKA designs were enrolled. The 150 patients were divided into two groups: guided motion group (77) with kinematic design (Journey) and control group (73) with no kinematic design (LCS). All the patients had the same surgical technique and postoperative protocols. The functional and radiographic results were interpreted with the Hospital for Special Surgery (HSS) knee score and WOMAC score. RESULTS: After a mean follow-up of 84.2months, the guided motion group had higher mean postoperative range of motion (p=0.022), functional status in the WOMAC function subscale (p=0.002), but had higher residual pain in the WOMAC pain subscale (p=0.018 and p=0.013) and higher iliotibial band syndrome incidence (6.6% vs 0%; p=0.02). There were no significant differences in HSS score between the two groups. No differences were seen between groups in patient satisfaction in the WOMAC total score (p=0.46) and survival rate. CONCLUSION: The guided motion design can improve functional status according to WOMAC but not to HSS knee scores. Poorer pain scores and no higher patient satisfaction were observed with this kinematic design.