Time Required for Planned and Unplanned Episodes of Care in Septic and Aseptic Hip and Knee Revision Surgery

Background: Surgical reimbursement rates are established by the Centers for Medicare and Medicaid Services (CMS). Studies have indicated that revision hip (rTHA) and knee (rTKA) arthroplasties require significantly more work effort, but are reimbursed less than primary procedures. This study quantified planned and unplanned work performed for revision surgeries by the surgeon and/or the surgeon’s team during the episode of care “reimbursement window.” Quantification of time was performed separately for aseptic and septic (two-stage) revisions and compared to allowed reimbursement amounts. Methods: All unilateral rTHA and rTKA procedures performed over a 10-year period by a single surgeon at a single institution were retrospectively reviewed. Time dedicated to planned work was calculated over each episode of care, from surgery scheduling to 90 days postoperatively. Impromptu patient inquiries and treatments after discharge, but within the episode of care, involving the surgeon/surgeon team constituted unplanned work. Planned and unplanned work minutes were summed and divided by the number of patients reviewed to obtain average minutes of work per patient. Results: Calculations demonstrated average per patient work for aseptic rTKA exceeded the reimbursable amount by 31 minutes. Calculated average minutes of work per patient required for aseptic rTHA fell within the number of minutes approved for reimbursement. Average per patient work for septic rTKA and rTHA exceeded the reimbursable amounts by 331 and 166 minutes, respectively, equating to 2.8 to 5.5 hours of uncompensated time. Conclusion: Revision hip and knee procedures are substantially more complex than primary procedures, with many surgeons referring patients to out-of-network care. Financially dis-incentivizing surgeons to care for these patients reduces patient access to care when high quality care is needed the most, especially infection cases susceptible to high sepsis and mortality rates. Study findings will be applied to advocacy efforts for appropriate legislative reform.

Intraoperative Fractures of the Tibia and Femur in Knee Revision Surgery

Intra-operative fractures in knee revision surgery are relatively rare and have not been well studied. They may occur during joint exposition, removal of the prosthesis or cement, or implantation of trial or original components. The fractures affect both the metaphyseal area and diaphysis of the tibia and femur. Tibial fractures are slightly more common than femur fractures. On the femur, the medial condyle is most frequently affected, followed by the femur diaphysis. The use of non-cemented stems is associated with a greater risk of intra-operative diaphyseal fractures than that of cemented stems. Overall, women and patients with an osteopenic bone structure have a higher risk of fractures. It is common that fractures are diagnosed post-operatively. In these cases, conservative therapy may be successful, depending on the stability of the prosthesis and bones. The most common surgical fixation options are cerclages and screws, followed by stem extensions for bridging the fracture. Plate fixation or use of strut grafts are also sensible therapy options. Overall, intraoperative fractures have a high healing potential with stable and good joint function. The revision rate is still 15%, which is most often caused by peri-prosthetic infection.

Elevated ESR and CRP Prior to Second-Stage Reimplantation Knee Revision Surgery for Periprosthetic Joint Infection Are Associated with Increased Reinfection Rates

Purpose Although two-stage revision surgery is considered as the most effective treatment for managing chronic periprosthetic joint infection (PJI), there is no current consensus on the predictors of optimal timing to second-stage reimplantation. This study aimed to compare clinical outcomes between patients with elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior to second-stage reimplantation and those with normalized ESR and CRP prior to second-stage reimplantation. Methods We retrospectively reviewed 198 patients treated with two-stage revision total knee arthroplasty for chronic PJI. Cohorts included patients with: (1) normal level of serum ESR and CRP (n = 96) and (2) elevated level of serum ESR and CRP prior to second-stage reimplantation (n = 102). Outcomes including reinfection rates and readmission rates were compared between both cohorts. Result At a mean follow-up of 4.4 years (2.8–6.5 years), the elevated ESR and CRP cohort demonstrated significantly higher reinfection rates compared with patients with normalized ESR and CRP prior to second-stage reimplantation (33.3% vs. 14.5%, p < 0.01). Patients with both elevated ESR and CRP demonstrated significantly higher reinfection rates, when compared with patients with elevated ESR and normalized CRP (33.3% vs. 27.6%, p = 0.02) as well as normalized ESR and elevated CRP (33.3% vs. 26.3%, p < 0.01). Conclusion This study demonstrates that elevated serum ESR and/or CRP levels prior to reimplantation in two-stage knee revision surgery for chronic PJI are associated with increased reinfection rate after surgery. Elevation of both ESR and CRP were associated with a higher risk of reinfection compared with elevation of either ESR or CRP, suggesting the potential benefits of normalizing ESR and CRP prior to reimplantation in treatment of chronic PJI.

Elution Kinetics from Antibiotic-Loaded Calcium Sulfate Beads, Antibiotic-Loaded Polymethacrylate Spacers, and a Powdered Antibiotic Bolus for Surgical Site Infections in a Novel In Vitro Draining Knee Model

Antibiotic-tolerant bacterial biofilms are notorious in causing PJI. Antibiotic loaded calcium sulfate bead (CSB) bone void fillers and PMMA cement and powdered vancomycin (VP) have been used to achieve high local antibiotic concentrations; however, the effect of drainage on concentration is poorly understood. We designed an in vitro flow reactor which provides post-surgical drainage rates after knee revision surgery to determine antibiotic concentration profiles. Tobramycin and vancomycin concentrations were determined using LCMS, zones of inhibition confirmed potency and the area under the concentration–time curve (AUC) at various time points was used to compare applications. Concentrations of antibiotcs from the PMMA and CSB initially increased then decreased before increasing after 2 to 3 h, correlating with decreased drainage, demonstrating that concentration was controlled by both release and flow rates. VP achieved the greatest AUC after 2 h, but rapidly dropped below inhibitory levels. CSB combined with PMMA achieved the greatest AUC after 2 h. The combination of PMMA and CSB may present an effective combination for killing biofilm bacteria; however, cytotoxicity and appropriate antibiotic stewardship should be considered. The model may be useful in comparing antibiotic concentration profiles when varying fluid exchange is important. However, further studies are required to assess its utility for predicting clinical efficacy.

Should all hip and knee prosthetic joints be aspirated prior to revision surgery?

Aims It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery. Methods We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria. Results A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%). Conclusion Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection.

How reliable is the next generation of multiplex-PCR for diagnosing prosthetic joint infection compared to the MSIS criteria? Still missing the ideal test

Introduction: Identification of the pathogen in case of a periprosthetic joint infection (PJI) remains 1 of the greatest challenges in septic surgery. Rapid germ identification enables timely, specific, antimicrobial therapy. The first multiplex PCR (polymerase chain reaction) generation (Unyvero-i60) enables germ detection within 5 hours with a sensitivity of 78.8% and a specificity of 100%. The aim of this study is to investigate the performance of the new generation of cartridges (Unyvero-ITI) of multiplex PCR in the case of a PJI. Methods: In a prospective study, intraoperatively aspirated synovial fluid from 97 patients with aseptic or septic hip or knee revision surgery (49 aseptic, 48 septic) was examined with the multiplex PCR system (Unyvero-ITI) and the results were compared with the MSIS criteria. In addition, the time until the microbiological result was obtained in the event of a germ detection was documented. Results: The multiplex PCR showed a germ detection with a sensitivity of 85.1% and a specificity of 98.0%. In 7 cases a false negative result was found and in one patient a false positive result was found. The general accuracy of this test procedure was 91.8%. The detection of germs was carried out within 5 hours with the multiplex PCR compared to 4.9 days in conventional microbiological diagnostics. Conclusions: The new generation of multiplex-PCR was able to improve germ detection. The possibility of prompt detection of germs offers the option of faster, targeted antimicrobial therapy. This diagnostic tool offers significant advantages, particularly in the context of an acute periprosthetic infection.

Identification of pain patterns in unhappy patients after total knee arthroplasty

Introduction: About 20% of patients after total knee arthroplasty (TKA) are not satisfied nor pain free. After a challenging diagnostic workup it is not unusual that revision surgery becomes necessary. There is a general consensus that knee revision surgery should only be performed when the causes of the complaints are identified. In the clinical diagnostic process the detection of pain patterns that are typical for specific pathologies is paramount. Revision surgeons in clinical practice are well aware of some pain patterns but to date there is no study dealing with detection and identification of typical pain patterns in patients with painful TKA. Hypotheses: The primary aim of this study was to precisely assess various characteristics of pain in patients after TKA qualifying for revision surgery and hence identify specific pain patterns. Secondary aim was to attribute the identified pain patterns to the underlying pathologies and implant characteristics. We hypothesised that specific pain patterns can be identified and then attributed to typical pathologies, which are being held responsible for the cause of pain. Methods: A retrospective cohort of 97 painful primary TKA patients were systematically evaluated in a specialized knee centre according to a standardised diagnostic algorithm. The end point of the clarification process results in a diagnosis which is being held responsible for the pain and states the indication for revision surgery. Within this process pain character, location, dynamics of pain and pain radiation is assessed and correlated with TKA characteristics and the underlying pathologies. Results: Most frequent pain characters were pricking/lancinating (45.7%), pinching/crushing (38.6%), dull/heavy (38.6%) and hot/searing (27.1%); 89.5% of all patients localized their knee pain anteriorly, 63.2% laterally, 57.9% medially and 5.3% posteriorly. 81.4% reported pain aggravations under strain, 48.1% on descending and 35.8% on ascending stairs, 25.6% at night. Radiation to the thigh, lower leg and spine was reported in 17.3, 13.6 and 9.9% of the patients. In 74.2% of the patients more than one underlying pathology was found; instability (52.6%), patella- (56.7%) and component-related problems (28.9%) are the most reported ones. Based on these findings nine specific pain patterns were identified including typical correlations between pain and TKA characteristics and pathologies. For example, pattern one represents pricking/lancinating, hot/searing and jumping/shooting pain, typically medially localized, aggravated in flexion and relieved by walking downhill, attributed to an instability problem of the TKA. Conclusion: The assessment of painful TKA patients involving specific pain patterns and its correlation with underlying pathologies, help to further differentiate and define the clinical picture of a painful knee after TKA. Knowing these pain patterns in patients with painful TKA enables a prediction of the cause of the pain to be made as early as possible in the diagnostic process. If the causes of the described complaints are known, a decision for a necessary therapy can also be made reliably and sustainably at an early stage before the state of pain becomes chronic.