Pain Classification using Evoked EEG Induced by Thermal Grill Illusion - Deep Neural Network Approach.

As the quantification of pain has emerged in biomedical engineering today, studies have been developing biomarkers associated with pain actively by measuring bio-signals such as electroencephalogram (EEG). Recently, some EEG studies of cold and hot pain have been reported. However, they used one type of stimulus condition for each trial and a relatively long stimulation time to collect EEG features. In this study, EEG signals during Cool (20 °C), Warm (40 °C), and Thermal Grill Illusion (TGI, 20-40 °C) stimuli were collected from 43 subjects, and were classified by a deep convolutional neural network referred to as EEGNet. Three binary classifications for the three conditions (TGI, Cool, Warm) were conducted for each subject individually. Classification accuracies for TGI-Cool, TGI-Warm, and Warm-Cool were 0.74±0.01, 0.71±0.01, and 0.74±0.01, respectively. For subjects who rated the TGI significantly hotter than the Warm stimulus, the classification accuracy for TGI-Cool (0.74±0.01) was significantly higher than for TGI-Warm (0.71±0.01). In contrast, the classification accuracy for TGI-Cool (0.72±0.03) did not differ statistically from TGI-Warm (0.73±0.01) in subjects without illusion. We found that the TGI and Cool stimuli were classified better than the TGI and Warm stimuli, implying that objective EEG features are consistent with subjective behavioral results. Further, we observed that most discriminative features between the TGI and the Cool or Warm conditions appeared in the parietal area for subjects who perceived the illusion. We postulate that the somato-sensory cortex may be activated when TGI is perceived to be hot pain.

Tibial Post Refracture in Posterior-Stabilized Total Knee Arthroplasty Following Isolated Tibial Insert Exchange.

Background: We report 4 cases with a tibial post refracture following isolated tibial insert exchange in posterior-stabilized total knee arthroplasty at a single center. Methods: In our institution, 27 cases (26 patients) underwent reoperation due to tibial post fracture in posterior-stabilized total knee arthroplasty between July 2008 and November 2020. Of these 27 cases, 4 (4 patients) tibial post refractures occurred at a mean follow-up period of 9.1 years. Results: All 4 cases of tibial post refracture occurred in a group of 21 cases with isolated tibial insert exchange. There was no tibial post refracture in patients with a tibial revision surgery. The incidence of this complication following isolated tibial insert exchange was 19.0%. The mean elapsed time from tibial insert exchange to the diagnosis of a post refracture was 2.5 years (range: 1.1-6.6 years). Conclusions: Isolated exchange of a tibial insert with excessive thickness as a treatment for tibial post fracture is associated with a high probability of tibial post refracture. The treatment method should be selected after a thorough analysis according to the cause of fracture. Level of evidence: IV.

No higher tibial post fracture rate with highly cross-linked polyethylene inserts in total knee arthroplasty at a minimum 10-year follow-up.

PURPOSE: The purpose of this study was to assess tibial post fracture between highly cross-linked polyethylene (HXPE) and conventional polyethylene inserts in consecutive posterior-stabilized (PS) total knee arthroplasty (TKA) over a minimum 10-years follow-up period. METHODS: Between July 2008 and December 2011, a consecutive series of 3264 primary TKAs was performed in 2098 patients using a PS total knee prosthesis at a single institution. The final cohort was classified into the HXPE group (792 cases) and the conventional group (2113 cases) according to insert material used during the procedure. RESULTS: The mean follow-up period was 11.4 years in the HXPE group and 11.8 years in the conventional group. Both cases of tibial post fracture occurred in the HXPE group, a complication rate of 0.25%. These two cases required replacement with a thicker tibial insert with retention of the femoral and tibial components. There were no cases of tibial post fracture in the conventional group. CONCLUSION: There was no difference in tibial post fracture rate between the HXPE group and the conventional group in PS TKA on long-term follow-up. LEVEL OF EVIDENCE: IV.

Distal Femoral Pin Tracker Placement Prevents Pin Tract-induced Fracture in Robotic-Assisted Total Knee Arthroplasty.

The purpose of this study was to determine the effectiveness of the placement of pin trackers in the medial sagittal plane of the distal femur in robotic-assisted total knee arthroplasty (TKA) over a minimum follow-up period of 3 months. From August 2020 to October 2020, a consecutive series of 81 TKAs were performed in 59 patients using the Triathlon posterior-stabilized total knee prosthesis with a robotic-assisted system (Mako) at our hospital. Patient charts were reviewed for complications associated with the pin sites, including fracture, infection, thigh pain, and the need for reoperation. No patients had any minor or major complications associated with distal femoral pins. This technique, which used pin trackers in the medial sagittal plane of the distal femur, could be a useful option for surgeons performing robotic-assisted TKA. This is a Level IV study.

Distal Femoral Tracker Pin Placement Prevents Delayed Pin Tract-Induced Fracture in Robotic-Assisted Total Knee Arthroplasty: Results of Minimum 1-Year Follow-Up.

The purpose of this study was to determine the outcomes of the placement of a pin tracker in the distal femur in robotic-assisted total knee arthroplasty (TKA) over a minimum follow-up period of 1 year. A consecutive series of 81 TKAs were performed in 59 patients using a robotic-assisted system (Mako) at our hospital. The mean follow-up period was 1.1 years (range, 1-1.2 years). No periprosthetic fracture at a pin tracker site was reported at a minimum of 1 year of follow-up. No patients reported minor or major complications associated with the distal femoral pins. In addition, unicortical pin-site drilling marks in all patients disappeared on one-postoperative-year follow-up radiographs. Our technique, which used unicortical pin placement in the distal femur in robotic-assisted TKA, demonstrated that it was a safe and reliable method at a minimum follow-up period of 1 year. The level of evidence is IV.

Long-term outcomes of total knee arthroplasty in patients with windswept deformity.

BACKGROUND: This study compared the functional outcomes, implant survival rates, and complications of total knee arthroplasty (TKA) performed in patients with windswept deformity (WSD) and non-WSD patients over at least 10 years of follow-up. METHODS: From January 2008 to December 2010, 40 TKAs were performed in 20 patients with WSD (WSD group). Additionally, 60 propensity score-matched patients without WSD who had undergone primary bilateral TKA were chosen for the control group in a three-to-one ratio. Then, the functional outcomes, implant survival rates, and complications of TKA in the two groups were compared. The mean follow-up periods were 10.8 years in the WSD group and 11.5 years in the control group. RESULTS: The mean Knee Society knee scores in the WSD and control groups improved from 37.7 to 38.1 points preoperatively to 79.5 and 79.2 points at final follow-up (p = 0.974), while the mean function scores in the WSD and control groups improved from 36.5 to 37.2 points preoperatively to 77.8 and 77.4 points at final follow-up (p = 0.863). Two knees in the WSD group required revision surgery, including one due to septic loosening and one due to aseptic loosening. Five knees in the control group required revision surgery, including three due to septic loosening and two due to aseptic loosening. Kaplan-Meier survivorship analysis with the revision of either component as an endpoint in the WSD and control groups estimated 95.0% and 95.8% chances of survival for 10 years, respectively (p = 0.824). CONCLUSIONS: TKA performed in patients with WSD yielded good clinical outcomes and survivorship at least 10 years later. LEVEL OF EVIDENCE: IV.

Early aseptic loosening of primary total knee arthroplasty in patients with osteonecrosis of the knee: A case series.

The cause of early aseptic loosening in total knee arthroplasty (TKA) is uncertain, although several possibilities could be offered. We report that osteonecrosis of the knee should be considered as a possible cause or contributing etiologic factor for early aseptic loosening following primary TKA.

Coronal Correction for Post-Traumatic Malalignment Using Robot-Assisted Total Knee Arthroplasty: A Case Series.

Background: Achieving proper axis alignment can be difficult in the presence of posttraumatic extra-articular deformities in either the femur or the tibia. We present radiological outcomes following robot-assisted total knee arthroplasty (TKA) in patients with osteoarthritis of the knee accompanied by posttraumatic extra-articular deformities. Methods: We analyzed the outcomes of five knees in five patients with (1) Kellgren-Lawrence (K-L) Grade III-IV osteoarthritic knees, (2) the presence of posttraumatic extra-articular deformities either in the femur or the tibia, and (3) who underwent robot-assisted TKA. Their radiological findings were evaluated. Results: All five knees with initial deformity (mean 14.8°, range 12.7-18.5°) were corrected to neutral alignment (mean 0.7°, range -1.1-2.7°). There was no postoperative outlier of hip-knee-ankle (HKA) angle. Conclusion: Our results indicate that robot-assisted TKA can be used to achieve proper limb alignment in patients with posttraumatic extra-articular deformities.

Robot-assisted total knee arthroplasty improves mechanical alignment and accuracy of component positioning compared to the conventional technique.

PURPOSE: The purpose of this study was to compare the mechanical axis, accuracy of component positioning, and polyethylene liner thickness between robot-assisted total knee arthroplasty (TKA) and conventional TKA. METHODS: From July 2020 to December 2020, 154 TKAs were performed in 110 patients with Kellgren-Lawrence grade IV varus knees using a robot-assisted system (MAKO group). Additionally, 110 propensity score-matched patients who had undergone primary conventional TKA were chosen in a one-to-one ratio for the conventional group. Post-operative radiographs were used to evaluate mechanical axis and component coronal and sagittal positioning. The polyethylene liner thickness was investigated. The respective mean error values and outliers were obtained for the two study groups and were compared to determine the mechanical axis and the accuracy of the postoperative component positioning. RESULTS: Patients in the MAKO group achieved better accuracy than those in the conventional group in terms of postoperative mean mechanical axis (1.9˚ vs. 2.8˚, p < 0.05), femur coronal inclination (91.2˚ vs. 91.8˚, p < 0.05), tibia coronal inclination (90.8˚ vs. 91.1˚, p < 0.05), and tibia sagittal inclination (90.7˚ vs. 91.7˚, p < 0.05). However, there was no difference between the two groups in polyethylene liner thickness. CONCLUSIONS: Robot-assisted TKA showed improved mechanical axis and higher accuracy of component positioning compared to the conventional TKA technique, with no significant difference in polyethylene liner thickness between the two groups. Long-term follow-up studies are needed to compare the clinical outcomes of robot-assisted TKA. LEVEL OF EVIDENCE: IV.

Long-term outcomes of primary total knee arthroplasty in patients with hepatitis B virus infection.

AIMS: The purpose of this study was to compare the clinical outcomes, mortalities, implant survival rates, and complications of total knee arthroplasty (TKA) in patients with or without hepatitis B virus (HBV) infection over at least ten years of follow-up. METHODS: From January 2008 to December 2010, 266 TKAs were performed in 169 patients with HBV (HBV group). A total of 169 propensity score-matched patients without HBV were chosen for the control group in a one-to-one ratio. Then, the clinical outcomes, mortalities, implant survival rates, and complications of TKA in the two groups were compared. The mean follow-up periods were 11.7 years (10.5 to 13.4) in the HBV group and 11.8 years (11.5 to 12.4) in the control group. RESULTS: The mean Knee Society scores in the HBV and control groups improved from 37.1 (SD 5.6) and 38.4 (SD 5.4) points preoperatively to 78.1 (SD 10.8) and 81.7 (SD 10.2) points at final follow-up (p = 0.314), while the mean function scores in the HBV and control groups improved from 36.2 and 37.3 points preoperatively to 77.8 and 83.2 points at final follow-up (p = 0.137). Nine knees in the HBV group required revision surgery, including seven due to septic loosening and two due to aseptic loosening. Four knees in the control group required revision surgery, including three due to septic loosening and one due to aseptic loosening. Kaplan-Meier survivorship analysis with the revision of either component as an endpoint in the HBV and control groups estimated 96.6% and 98.5% chances of survival for ten years, respectively (p = 0.160). CONCLUSION: TKA in patients with HBV infection resulted in good clinical outcomes and survivorship. However, there was a higher revision rate over a minimum ten-year follow-up period compared to TKA in patients without HBV infection. Cite this article: Bone Jt Open 2022;3(6):470-474.

Usefulness of Trabecular Metal Cones in Revision Total Knee Arthroplasty in a Korean Population: A Case Series.

Purpose: The purpose of this study was to assess the medium-term results of trabecular metal cones for the reconstruction of large bone defects in revision TKA. Methods: Thirteen patients who had undergone revision TKA using trabecular metal cones for femoral and/or tibial large bone defects were identified. We included patients who had a minimum of three years follow-up in the study. We evaluated their functional outcomes, implant survivorship, radiological findings, and complications. Results: At a mean follow-up of 6.9 years (range of 3.5-9.4 years), all trabecular metal cones and implants were well fixed and did not exhibit any radiographic evidence of migration or loosening. At the final follow-up, the mean Knee Society knee scores had improved from 37.2 to 78.1 (p < 0.05), and function scores had improved from 35.5 to 77.5 points (p < 0.05). One intraoperative fracture in the distal femur occurred in an 85-year-old woman during impaction of a single trabecular metal cone. The fracture was successfully affixed to the femoral cone and bone three months postoperatively. Conclusion: The present study of trabecular metal cones demonstrates excellent clinical outcomes and survivorship in revision TKA during medium-term follow-up periods. However, longer-term follow-up studies are needed to further investigate these implants in revision TKA. Additionally, the necessity of metal cones in revision procedures should be carefully considered depending on patient needs and economic capabilities.

Regeneration of the lateral discoid meniscus after arthroscopic saucerization in an adult patient undergoing high tibial osteotomy: A case report.

Arthroscopic saucerization of the lateral discoid meniscus is considered due to an increase in the load of the lateral compartment after high tibial osteotomy (HTO). We report a case of lateral discoid meniscus regeneration after arthroscopic saucerization in a middle-aged female patient who underwent HTO.

High rate of tibial post-fracture in highly cross-linked polyethylene compared to conventional polyethylene in posterior-stabilized total knee arthroplasty at a minimum 12-year follow-up.

PURPOSE: The purpose of this study was to assess tibial post-fracture between highly cross-linked polyethylene (HXPE) and conventional polyethylene inserts in consecutive posterior-stabilized (PS) total knee arthroplasty (TKA) over a minimum 12-year follow-up period. METHODS: Between January 2007 and June 2008, a consecutive series of 2446 primary TKAs was performed in 1478 patients at a single institution. The final cohort was classified into two groups (1559 in the HXPE group and 887 in the conventional group) based on the insert material used during the procedure. RESULTS: The mean follow-up period was 13.1 years in the HXPE group and 13.4 years in the conventional group. All 16 cases of tibial post-fracture occurred in the HXPE group. This complication rate was 1.03%. The mean elapsed time from primary TKA to the diagnosis of post-fracture was 3.9 years (range 0.5-10.0 years). Ten cases required replacement with a thicker polyethylene insert, and six cases underwent tibial revision surgery. There were no cases of tibial post-fracture in the conventional group. CONCLUSION: Tibial post-fracture is not a rare complication in PS TKA with HXPE. Therefore, the possibility of a tibial post-fracture should be considered if newly developed pain, acute subluxation, effusion, patellar clunking, or instability occurs in patients treated with PS Scorpio knee system TKA using an HXPE insert. LEVEL OF EVIDENCE: IV.

Usefulness of robot-assisted total knee arthroplasty in patients with retained hardware: A report of two cases.

Total knee arthroplasty (TKA) is technically demanding in patients with pre-existing hardware around the knee. We report two cases of knee osteoarthritis in patients with retained hardware who would have difficulty undergoing conventional TKA. Robot-assisted TKA can be a useful treatment for knee osteoarthritis in patients with retained hardware.

Inferior outcomes of primary total knee arthroplasty in patients with rheumatoid arthritis compared to patients with osteoarthritis.

PURPOSE: The purpose of this study was to compare the functional outcomes, activity levels, mortalities, implant survival rates, and complications of total knee arthroplasty (TKA) in patients with rheumatoid arthritis (RA) with those in patients with osteoarthritis (OA) over a minimum 10-year follow-up period. METHODS: Between January 2007 and December 2009, 90 TKAs performed in 57 patients with RA (RA group) were retrospectively reviewed and matched with a control group of 180 TKAs performed in 114 patients with OA. The functional outcomes (Knee Society Score), activity levels (Koval grade), mortalities, implant survival rates, and complications were compared between the two groups with a minimum 10-year follow-up period. The mean follow-up periods were 12.3 years in the RA group and 12.6 years in the OA group. RESULTS: The mean Knee Society knee scores in the RA and OA groups improved from 37.7 ± 5.4 to 38.2 ± 5.3 preoperatively to 72.9 ± 22.8 to 83.1 ± 11.0 points, respectively, at the final follow-up (p < 0.05). At the final follow-up, 38 of 48 (79.2%) in the RA group and 105 of 109 (96.3%) in the OA group (p < 0.05) were outdoor ambulatory patients. The cumulative mortality rates in the RA and OA groups were 15.8% (9/57) and 4.4% (5/114) (p < 0.05) at the final follow-up, respectively. Kaplan-Meier survivorship analysis with revision of either component as an endpoint in the RA and OA groups estimated 94.4% and 98.3% chance of survival for 10 years, respectively. CONCLUSION: TKA in patients with RA had worse functional outcomes and higher mortality over a minimum 10-year follow-up period, compared with TKA in patients with OA. LEVEL OF EVIDENCE: IV.

Anterior dislocation of a total knee arthroplasty in a patient with postoperative delirium: a case report.

We report a rare case of traumatic anterior dislocation in a patient with postoperative delirium following total knee arthroplasty. The patient was successfully treated by open reduction of the dislocation and polyethylene liner change. Recognition of risk factors for postoperative delirium is important for the prevention of this uncommon injury.

Poor outcomes of revision total knee arthroplasty in patients with septic loosening compared to patients with aseptic loosening.

BACKGROUND: The purpose of this study was to compare the functional outcomes, activity levels, mortalities, implant survival rates, and complications in revision total knee arthroplasty (TKA) of patients with septic loosening with those in patients with aseptic loosening over a minimum 10-year follow-up period. METHODS: A cohort of 78 patients (36 septic loosening and 42 aseptic loosening) was selected between January 2008 and December 2009. The functional outcomes, activity levels, mortalities, implant survival rates, and complications of revision TKA in patients with septic and aseptic loosening were compared. RESULTS: The mean Knee Society knee scores in the septic and aseptic groups improved from 36.7 and 37.4 preoperatively to 65.3 and 76.8 points at the final follow-up, respectively (p < 0.05). Outdoor ambulatory patients at the final follow-up included 20 of 29 (69.0%) patients in the septic group and 35 of 39 (89.7%) patients in the aseptic group (p < 0.05). The cumulative mortality rates in the septic and aseptic groups were 19.4% (7/36) and 7.1% (3/42) (p = 0.102) at final follow-up, respectively. Kaplan-Meier survivorship analysis with re-revision of either component as an endpoint in the septic and aseptic groups estimated 86.5% and 95.5% chance of survival for 10 years, respectively. CONCLUSIONS: Revision TKA in patients with septic loosening had worse functional outcomes and higher mortality over a minimum 10-year follow-up period compared with that in patients with aseptic loosening. LEVEL OF EVIDENCE: IV.

Early Failure of Total Ankle Arthroplasty in a Patient with Ipsilateral Varus Knee Deformity.

Multiple risk factors such as age, body mass index (BMI), preoperative diagnosis, smoking, diabetes mellitus, malalignment of an implant, and presence of ipsilateral hindfoot fusion have been shown to contribute to failure of total ankle arthroplasty (TAA). However, the exact causes of TAA failure remain uncertain, and various causes can lead to a need for revision surgery. We report a case of early aseptic loosening of the implant following TAA in a patient with severe varus deformity of the ipsilateral knee.

Open-wedge high tibial osteotomy for the treatment of osteoarthritis of both knee and ankle in the same leg: A report of two cases.

We report two cases of patients with concurrent osteoarthritis of the knee and ipsilateral ankle. The patients were treated with high tibial osteotomy (HTO). In well-planned and selected cases, HTO may be effective in treating not only the knee, but also the ankle in patients with ipsilateral double-joint osteoarthritis.

Long-term survivorship of total knee arthroplasty with a single-radius, high-flexion posterior stabilized prosthesis.

BACKGROUND: The purpose of this study was to determine functional outcomes, implant survival rate, and complications of a single-radius, high-flexion posterior stabilized (PS) total knee prosthesis at a minimum follow up of 10 years for a consecutive series. METHODS: This retrospective observational study included 395 consecutive patients who underwent 585 single-radius, PS total knee arthroplasties (TKAs) between January 2009 and December 2009. Their functional outcomes, implant survival rates, radiological findings, and complications were evaluated. RESULTS: At a mean follow up of 11.2 years (range, 10.6-11.8 years), 395 (80.8%) patients were available for review. At final follow up, preoperative Knee Society knee scores were improved from 37.3 to 80.1 (P < 0.05) and function scores were improved from 35.7 to 80.5 points (P < 0.05). Sixteen knees (2.7%) in 15 patients required revision surgery due to 11 septic loosening (1.9%) and five aseptic loosening events (0.8%). Cumulative survival for the prosthesis was 97.3% for any cause at 10 years. A total of 34 radiolucent lines (5.8%) were detected an average of 2.4 years following surgery and radiological assessment did not reveal any evidence of component migration at final follow up. CONCLUSIONS: Single-radius, high-flexion PS TKA showed good long-term survival rates and clinical outcomes. Further study is required to determine whether limited radiolucency findings at the tibial component-tibial plateau could progress to or result in the loosening of components.