Comparison of Anterior-Stabilized and Posterior-Stabilized Total Knee Arthroplasty in the Same Patients: A Prospective Randomized Study.

BACKGROUND: A highly conforming, anterior-stabilized (AS) insert is designed to provide anteroposterior (AP) stability of the posterior-stabilized (PS) insert without a post. The purpose of this study was to compare the static and dynamic stability and function of AS and PS total knee arthroplasty (TKA) in the same patients. METHODS: A prospective, randomized controlled trial was performed in 45 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to receive an AS TKA, and the other knee was scheduled for a PS TKA from the same knee system. At 2 years postoperatively, the static AP stability was compared using anterior and posterior drawer stress radiographs at 90° knee flexion. Dynamic AP stability was evaluated using one-leg standing lateral fluoroscopic images throughout the range of motion. Knee function was compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. RESULTS: At 2 years postoperatively, there was a significant difference in knee AP laxity at 90° of flexion between the two groups (7.6 ± 3.9 mm in the AS group vs 2.2 ± 2.3 in the PS group, P < .001). However, there were no differences in dynamic AP stability under one-leg standing fluoroscopic lateral images at 30°, 60°, and 90° knee flexion (P = .732, P = .764, and P = .679, respectively). The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were not significantly different between the two groups (P = .641 and P = .582, respectively). CONCLUSION: Despite the fact that the AS TKA group showed significantly more static posterior displacement than the PS TKA group at 90° of knee flexion, both the AS and PS TKA groups showed similar dynamic stability under weight-bearing conditions and knee function at 2 years postoperatively.

Central Sensitization Is a Risk Factor for Persistent Postoperative Pain and Dissatisfaction in Patients Undergoing Revision Total Knee Arthroplasty.

BACKGROUND: The objective of this study is to investigate whether central sensitization (CS) was associated with patient dissatisfaction after revision total knee arthroplasty (TKA). METHODS: Between 2012 and 2016, 68 cases (68 patients) of revision TKA performed by a single surgeon were included in this study with a minimum follow-up of 2 years. Patients were categorized into 2 groups by 40-point preoperative Central Sensitization Inventory (CSI) scores. The control group consisted of 48 patients (48 knees) with CSI scores of less than 40 points, while the CS group consisted of 20 patients (20 knees) with CSI scores of 40 points or more. Clinical outcomes were evaluated using an 11-point visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient satisfaction was evaluated using the satisfaction items of the new Knee Society Scores, where scores ≥20 indicated satisfaction. RESULTS: Higher preoperative pain VAS scores in the CS group were maintained 3, 6, 12, and 24 months postoperatively (all P < .05). The CS group showed significantly worse pain, function subscores, and total scores of the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and at 2 years postoperatively. Forty-four (91.7%) patients in the control group and 3 (15.0%) patients in the CS group were satisfied with their revision TKAs (P < .001). Multivariate logistic regression analysis demonstrated that the odds of dissatisfaction after revision TKAs were increased 39.081 times (95% confidence interval 6.926-220.504, P < .001) in patients with CSI scores ≥40. Higher VAS intensity 2 years postoperatively also predicted dissatisfaction following revision TKA (odds ratio 1.864, 95% confidence interval 1.086-3.199, P = .024). CONCLUSION: CS is a risk factor for persistent postoperative pain and dissatisfaction in patients undergoing revision TKAs. LEVEL OF EVIDENCE: III.

Correcting Severe Varus Deformity Using Trial Components During Total Knee Arthroplasty.

BACKGROUND: Extensive medial soft tissue release may be necessary to correct severe varus deformity during total knee arthroplasty (TKA). However, this procedure may result in instability. Here, we describe a novel soft tissue balancing technique, which can minimize medial release in severe varus deformity during TKA. METHODS: Fifty knees (40 patients) with hip-knee-ankle angle of more than 20° of varus were corrected using this technique (group 1). After achieving flexion gap balancing by needle puncturing and spreading of the superficial medial collateral ligament, extension gap balancing was obtained by gradual extension with the trial components in place. After group 1 was set, a one-to-one patient-matched control group who had mild varus deformity was selected by propensity score matching (50 knees, 48 patients, group 2). At postoperative 1 year, mediolateral laxity was compared between the 2 groups using the stress radiographs. Clinical outcomes were also compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score. RESULTS: There were no differences in mean medial and lateral laxities between groups 1 and 2 at 1 year after the operation (medial laxity: 2.3° ± 1.4° and 2.7° ± 1.3°, respectively, P = .310) (lateral laxity: 3.6° ± 1.7° and 3.2° ± 2.0°, respectively, P = .459). There were no significant differences in postoperative clinical scores and knee alignment. CONCLUSION: Our technique of obtaining extension gap balancing using trial components led to safe and effective balancing by avoiding unnecessary extensive release in severe varus deformity during TKA.

Differences in Patient-Reported Outcomes Between Unicompartmental and Total Knee Arthroplasties: A Propensity Score-Matched Analysis.

BACKGROUND: The purpose of this study was to compare the patient-reported outcomes regarding joint awareness, function, and satisfaction after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). METHODS: We identified all patients who underwent a UKA or TKA at our institution between September 2011 and March 2014, with a minimum follow-up of 2 years. Propensity score matching was performed for age, gender, body mass index, operation side, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. One hundred UKAs to 100 TKAs were matched. Each knee was evaluated according to the WOMAC score, Forgotten Joint Score (FJS), High Flexion Knee Score (HFKS) and patient's satisfaction at postoperative 2 years. RESULTS: There was no significant difference in WOMAC score at postoperative 2 years between UKA and TKA groups. However, the FJS of the UKA group was significantly higher than that of the TKA group (67.3 ± 19.8 and 60.6 ± 16.6, respectively; P = .011). The HFKS was also significantly higher in the UKA group compared with the TKA group (34.4 ± 6.4 and 31.3 ± 5.2, respectively; P < .001). Eighty-six percent of all patients who underwent UKA were satisfied compared with 71% of those who underwent TKA (P = .027). CONCLUSION: Patients who underwent UKA had higher FJS, HFKS, and satisfaction rate when compared with patients who underwent TKA, indicating that UKA facilitated less knee awareness and better function and satisfaction than TKA.

Are Midterm Patient-Reported Outcome Measures Between Rotating-Platform Mobile-Bearing Prosthesis and Medial-Pivot Prosthesis Different? A Minimum of 5-Year Follow-Up Study.

BACKGROUND: Both rotating-platform (RP) mobile-bearing and medial-pivot (MP) fixed-bearing prostheses allow axial femorotibial rotation using a highly conforming polyethylene insert. However, limited comparative data are available between the 2 designs. This study was performed to compare the midterm clinical outcomes and patient-reported outcome measures (PROMs) of RP and MP prostheses. METHODS: We retrospectively reviewed the records of 52 total knee arthroplasties using RP mobile-bearing prosthesis and 49 total knee arthroplasties using MP fixed prosthesis with a minimum follow-up period of 5 years. Clinical and radiological outcomes, failure rates, and PROMs, including the Western Ontario and McMaster Universities Osteoarthritis Index score and satisfaction, were compared. RESULTS: There was no difference in clinical or radiographic outcomes (P > .1 for all comparisons), with the exception of the larger flexion contracture (FC) in the MP group (0.3° in RP vs 2.3° in MP, P < .01). No failure in either group was recorded during the study period. PROMs were comparable (P > .1 in all comparisons), with the exception of higher satisfactions in the RP group while performing light household duties (P < .01) and leisure or recreational activities (P = .014) in patients without FC. CONCLUSION: The midterm clinical results with both the RP mobile-bearing and MP fixed-bearing prostheses were satisfactory. Although both prostheses provided comparable PROMs, patients with an RP prosthesis were more satisfied than those with an MP prosthesis for highly demanding activities that are strongly associated with the presence of postoperative FC.

Does Patient Perception Differ Following Adductor Canal Block and Femoral Nerve Block in Total Knee Arthroplasty? A Simultaneous Bilateral Randomized Study.

BACKGROUND: Femoral nerve block (FNB) has been used as part of the multimodal analgesia after total knee arthroplasty (TKA), but leads to weakness in the quadriceps muscles. Recently, adductor canal block (ACB) was reported to provide effective pain relief while sparing the strength of the quadriceps. This simultaneous bilateral randomized study investigated whether patients perceived differences between ACB and the FNB after same-day bilateral TKA. METHODS: We performed a prospective simultaneous bilateral randomized study in 50 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to ACB and the other knee was assigned to FNB. All ACB and FNB were performed using ultrasound-guided single-shot procedures. These 2 groups were compared for pain visual analogue scale, straight leg raising ability and knee extension while sitting, and motor grade. At postoperative week 1, the peak torque for the quadriceps muscle was measured in both knees with an isokinetic dynamometer. RESULTS: There were no differences in pain levels between ACB and FNB during the entire study period. During the first 48 h after TKA, more of the knees that received ACB could perform straight leg raising and knee extension with greater quadriceps strength compared with FNB. However, no group differences in quadriceps functional recovery were found after postoperative 48 h and isometric quadriceps strength at postoperative 1 week. CONCLUSION: This simultaneous bilateral randomized study demonstrates that patients did not perceive differences in pain level, but experienced substantial differences in quadriceps strength recovery between knees during the first 48 h (Identifier: NCT02513082).

The Leukocyte Esterase Strip Test has Practical Value for Diagnosing Periprosthetic Joint Infection After Total Knee Arthroplasty: A Multicenter Study.

BACKGROUND: Leukocyte esterase (LE) was recently reported to be an accurate marker for diagnosing periprosthetic joint infection (PJI) as defined by the Musculoskeletal Infection Society (MSIS) criteria. However, the diagnostic value of the LE test for PJI after total knee arthroplasty (TKA), the reliability of the subjective visual interpretation of the LE test, and the correlation between the LE test results and the current MSIS criteria remain unclear. METHODS: This study prospectively enrolled 60 patients undergoing revision TKA for either PJI or aseptic failure. Serological marker, synovial fluid, and histological analyses were performed in all cases. The PJI group comprised 38 cases that met the MSIS criteria and the other 22 cases formed the aseptic group. All the LE tests were interpreted using both visual judgment and automated colorimetric reader. RESULTS: When "++" results were considered to indicate a positive PJI, the sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy were 84, 100, 100, 79, and 90%, respectively. The visual interpretation agreed with the automated colorimetric reader in 90% of cases (Cronbach α = 0.894). The grade of the LE test was strongly correlated with the synovial white blood cell count (ρ = 0.695) and polymorphonuclear leukocyte percentage (ρ = 0.638) and moderately correlated with the serum C-reactive protein and erythrocyte sedimentation rate. CONCLUSION: The LE test has high diagnostic value for diagnosing PJI after TKA. Subjective visual interpretation of the LE test was reliable and valid for the current battery of PJI diagnostic tests according to the MSIS criteria.