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Purpose: To investigate the aseptic survival of 1.5-stage exchange arthroplasty for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). Methods: Eighty-eight cases of 1.5-stage exchange arthroplasty for PJI without reinfection were retrospectively analysed. The autoclaved femoral component and new polyethylene insert (PE) were implanted using antibiotic mixed cement. The explanted tibial component was not reinserted. The Western Ontario and McMaster Universities Osteoarthritis Index and range of motion were clinically evaluated preoperatively and at the last follow-up (the last time for the implant in situ). Radiographically, hip–knee–ankle angle (HKA) and component positions were measured preoperatively, postoperatively (1 month after the 1.5-stage exchange arthroplasty), and at the last follow-up. The survival rate was analysed using the Kaplan–Meier method, in which failure was defined as reoperation due to aseptic failure. Mean period to failure and failure site were analysed. Factors affecting survival were investigated in terms of demographics and inappropriateness of the postoperative HKA (HKA > 0 ± 3°) and component positions (α angle > 95 ± 3°, β angle > 90 ± 3°, γ angle > 3 ± 3°, and δ angle > 87 ± 3°). Results: The spacer in-situ time was 3.7 years (0.2–6.4). The clinical results improved hip–knee–ankle significantly at the last follow-up. Radiographically, the average HKA was valgus 0.1° postoperatively. The average α, β, γ, and δ angles of the postoperative component positions were 95.9°, 90.4°, 3.8°, and 86.7°, respectively. The 1-, 2-, and 5-year postoperative survival rates were 90.9%, 86.4%, and 80.6%, respectively. The mean period to failure was 2.0 years (0.2–5.3). There were 18 cases of aseptic loosening (20.8%), occurring on both the femur and tibial sides in 1 knee, and only on the tibial side in 17 knees. Inappropriate coronal position of the PE (β angle > 90 ± 3°) was a significant factor affecting survival (odds ratio = 5.491; p = 0.011). Conclusion: The aseptic survival of the 1.5-stage exchange arthroplasty was acceptable when using an autoclaved femoral component and new PE. The appropriate coronal position of the PE helps ensure favourable survival of 1.5-stage exchange arthroplasty. Level of evidence: IV [ABSTRACT FROM AUTHOR]

Purpose: A new tibial baseplate of the cobalt-chrome (CoCr) prosthesis has an enhanced design with additional cement pockets and undersurface with increased roughness compared with the original baseplate. This study aimed to compare the incidence of medial proximal tibial resorption (MPTR) in total knee arthroplasties (TKAs) with the original and new CoCr tibial baseplates. Methods: Each of 200 posterior stabilized TKAs with the original (Group O) and new (Group N) CoCr tibial baseplates with a minimum follow-up period of 2 years were retrospectively reviewed. The matches were made according to age, sex, body mass index, and severity of varus deformity. The occurrence of MPTR was investigated with a radiograph at 2 years postoperatively. MPTR was categorized as type U (resorption under the tibial baseplate; associated with stress shielding), C (resorption around the penetrated cement under the baseplate; associated with thermal necrosis), and M (resorption on the medial tibial cortex without extension to the baseplate; associated with bony devascularization). Results: The incidence of MPTR was 35% in group O and 24% in group N (p = 0.021) at postoperative 2 years. The U type of MPTR occurred more frequently in group O (26 vs. 15%, p = 0.009). There were no significant differences in the incidence of types C and M MPTR. Conclusion: The modified design of the CoCr tibial baseplate affected the incidence of MTPR. The new tibial baseplate was more advantageous in preventing MPTR than the original baseplate in TKAs using the CoCr prosthesis. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the incidence of intraoperative mid-flexion laxity using continuous flexion-arc gap assessment, risk factors for mid-flexion laxity, and clinical results in navigation-assisted total knee arthroplasty (TKA). Methods: Ninety posterior-stabilized TKAs were performed under navigation guidance for patients with degenerative arthritis and varus deformity. Intraoperatively, the gap between the trial femoral component and insert was evaluated in the navigation system with continuous flexion-arc gap assessment. Each medial and lateral gap at flexion (90°) and extension (0°) were made to be less than 3 mm. Mid-flexion laxity was determined when the gap in the flexion range between 15° and 60° was 3 mm or more. The proportion of knees with mid-flexion laxity was investigated. The factors affecting mid-flexion laxity were identified in terms of demographics, preoperative convergence angle, and change in joint line height and posterior femoral offset. The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. Results: There were 31 cases (34.4%) of lateral mid-flexion laxity (average peak mid-flexion gap = 3.7 mm). The other 59 cases did not show mid-flexion laxity. The preoperative convergence angle was the only significant factor affecting lateral mid-flexion laxity (odds ratio = 1.466, p = 0.002). There were no significant differences in the clinical results between the groups with and without mid-flexion laxity. Conclusions: The continuous flexion-arc gap assessment was useful in evaluating mid-flexion laxity using navigation-assisted TKA. The preoperative convergence angle, reflecting soft-tissue laxity, can be a practical and simple radiographic finding for predicting lateral mid-flexion laxity. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

The choice of implant used for primary total knee arthroplasty (TKA) may have an impact on clinical outcomes. Clinical outcomes after TKA with gradually reducing radius implants (group G) vs single-radius implants (group S) were evaluated among Asian patients. This study included 541 patients (754 knees) in group G and 187 patients (275 knees) in group S. Range of motion (ROM), flexion contracture, American Knee Society Knee and American Knee Society Function scores (KSKS and KSFS, respectively), and mechanical and anatomic tibiofemoral angles (MTFA and ATFA, respectively) were evaluated with electronic medical records. In univariate analysis, improvements in ROM, KSKS, and KSFS were significantly better in group G compared with group S at 1-year follow-up. Multivariable analyses showed greater ROM (4.52°, P=.002), decreased flexion contracture (-2.80°, P=.011), and improved KSKS (15.57, P<.001) at 1 year for group G vs group S. No significant differences in KSFS, MTFA, or ATFA were observed. Implant-related complications and radiologic loosening were not identified in either group at 2-year follow-up. The TKA implants with a gradually reducing radius showed greater 1-year improvements in ROM, flexion contracture, KSKS, and similar implant-related safety outcomes compared with a single-radius system. [Orthopedics. 2022;45(6):367-372.]. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to analyze long-term clinical and radiographic results, and survival of re-revision total knee arthroplasty (TKA) using fully cemented stems performed on femurs with diaphyseal deformation.Methods: Thirty-seven re-revision TKAs using fully cemented stems performed in femoral diaphyseal deformations, characterized as diaphyseal canal enlargement and cortex deformation due to aseptic loosening of previously implanted stems, between 2003 and 2015 were retrospectively reviewed. The mean follow-up period was 10.0 years. Clinically, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. Radiographically, mechanical axis (MA) and component positions were measured. Complications and survival rates were also analyzed.Results: Clinically, the WOMAC significantly improved at final follow-up (61.2 vs 47.2, p < 0.001), but not the ROM (95.5 vs 102.5, p = 0.206). Radiographically, the MA and component positions were appropriate, with no changes in component positions from immediately post-operative to final follow-up, but with MA change from varus 2.9° to 3.7° (p = 0.020). Two cases (5.4%) with history of previous infections developed periprosthetic joint infection (PJI). Debridement with polyethylene insert exchange following antibiotic suppression were performed in those cases because of concern for difficult implant-cement removal. The five and ten year survival rates were 100% and 93.2%, respectively.Conclusion: Fully cemented stems are viable in providing long-term satisfactory survival after re-revision TKA in patients with femoral diaphyseal deformation. However, it should be used carefully for those with previous infections. [ABSTRACT FROM AUTHOR]

Background: Although total knee arthroplasty (TKA) in hemophilic arthropathy (HA) or rheumatoid arthritis (RA) can improve functional ability, the postoperative range of motion (ROM) and prosthesis durability are reduced compared with those in osteoarthritic patients. Aim: We aimed to compare (1) the pre- and postoperative flexion contracture after TKA in HA and RA, (2) the threshold of preoperative flexion contracture as a predictor of residual contracture > 15° after TKA, and (3) the survival rate. Methods: Data from a consecutive cohort comprising 48 TKAs in HA and 92 TKAs in RA were retrospectively reviewed. The degree of flexion contracture was analyzed. Through receiver operating characteristics analysis, we aimed to determine the cutoff value of preoperative flexion contracture that increases the risk of residual contracture > 15° after TKA and compare the cutoff value in HA and RA. The survival rate was evaluated based on life table analysis and the Kaplan–Meier method. Results: The degree of preoperative flexion contracture was not significantly different. The degree of postoperative residual flexion contracture was 5.6° in the HA group and 1.4° in the RA group, respectively (p < 0.001). The cutoff value of preoperative flexion contracture for residual contracture of > 15° at last-follow up was 25.0° in the HA group and 32.5° in the RA group. The 5- and 12-year survival rates were 96% and 87% in the HA and 99% and 95% in the RA group, respectively (n.s.). Conclusions: The postoperative residual flexion contracture was greater and the cutoff value of preoperative flexion contracture for residual contracture was smaller in the HA group than the RA group. Appropriate intra- and postoperative care to avoid postoperative residual contracture is required in HA patients. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Background: Many surgeons have determined the surgical transepicondylar axis (sTEA) after distal femur resection in total knee arthroplasty (TKA). However, in most navigation systems, the registration of the sTEA precedes the distal femur resection. This sequential difference can influence the accuracy of intraoperative determination for sTEA when considering the proximal location of the anatomical references for sTEA and the arthritic environment. We compared the accuracy and precision in determinations of the sTEA between before and after distal femur resection during navigation-assisted TKA. Methods: Ninety TKAs with Attune posterior-stabilized prostheses were performed under imageless navigation. The sTEA was registered before distal femur resection, then reassessed and adjusted after distal resection. The femoral component was implanted finally according to the sTEA determined after distal femur resection. Computed tomography (CT) was performed postoperatively to analyze the true sTEA (the line connecting the tip of the lateral femoral epicondyle to the lowest point of the medial femoral epicondylar sulcus on axial CT images) and femoral component rotation (FCR) axis. The FCR angle after distal femur resection (FCRA-aR) was defined as the angle between the FCR axis and true sTEA on CT images. The FCR angle before distal resection (FCRA-bR) could be presumed to be the value of FCRA-aR minus the difference between the intraoperatively determined sTEAs before and after distal resection as indicated by the navigation system. It was considered that the FCRA-bR or FCRA-aR represented the differences between the sTEA determined before or after distal femur resection and the true sTEA, respectively. Results: The FCRA-bR was −1.3 ± 2.4° and FCRA-aR was 0.3 ± 1.7° (p < 0.001). The range of FCRA-bR was from −6.6° to 4.1° and that of FCRA-aR was from −2.7° to 3.3°. The proportion of appropriate FCRA (≤ ±3°) was significantly higher after distal femur resection than that before resection (91.1% versus 70%; p < 0.001). Conclusions: The FCR was more appropriate when the sTEA was determined after distal femur resection than before resection in navigation-assisted TKA. The reassessment and adjusted registration of sTEA after distal femur resection could improve the rotational alignment of the femoral component in navigation-assisted TKA. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate intercompartmental load intraoperatively with a sensor after conventional gap balancing with a tensiometer during total knee arthroplasty (TKA).Methods: Fifty sensor-assisted TKA procedures were performed prospectively between August and September 2018 with a cruciate-retaining prosthesis. After applying a modified measured resection technique, conventional balancing between resected surfaces was achieved. The equal and rectangular flexion-extension gaps were confirmed using a tensiometer at 90° and 5°-7° (due to posterior tibial slope) of knee flexion. Then, the load distribution was evaluated intraoperatively with a sensor placed on trial implants in the positions of knee flexion (90° flexion) and extension (10° flexion).Results: The proportion of coronal load imbalance (medial load - lateral load ≥  ± 15 lb) was 56% in extension and 32% in flexion (p = 0.023). The proportion of sagittal load imbalance (extension load - flexion load ≥  ± 15 lb) was 36% in the medial compartment and 4% in the lateral compartment (p < 0.001). An additional procedure for load balancing was performed in 74% of knees.Conclusions: Coronal and sagittal load imbalances existed as determined by the sensor even after the achievement of appropriate conventional gap balance. The additional rebalancing procedure was performed for balanced loads in 74% of the knees after conventional balancing. The use of an intraoperative load sensor offers the advantage of direct evaluation of the load on TKA implants.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: The purposes of the present study were to assess the levels of prosthetic constraint chosen during revision total knee arthroplasty (TKA) and to identify factors influencing the choice of a constrained prosthesis.Methods: We retrospectively reviewed data on 274 revision TKAs. The mean follow-up period after revision TKA was 7.2 years. The femorotibial angle (FTA), joint line height (JLH), and Insall-Salvati ratio (ISR) were radiographically evaluated. Factors affecting the extent of constraint chosen were evaluated in terms of age, gender, body mass index, primary diagnosis, the cause of revision TKA, the Anderson Orthopedic Research Institute (AORI) classification, and changes in the JLH and ISR.Results: Totals of 247 (90.1%), 11 (4.0%), and 9 (3.4%) knees received posteriorly stabilized prostheses, constrained condylar knees, and rotating hinge prostheses, respectively. On multivariate analysis, the cause of revision TKA including loosening and instability and the changes in the JLH and ISR affected independently the choice of a constrained prosthesis.Conclusions: The frequency of implantation of constrained prostheses was 7.4% in the present study. Consideration of various factors including the cause of revision TKA and changes in the JLH and ISR will aid the TKA surgeon in selecting prostheses with appropriate constraints when performing revision TKAs. [ABSTRACT FROM AUTHOR]

Purpose: In the present study, the early results of sensor-assisted versus manually balanced posterior-stabilized total knee arthroplasty (TKA) for osteoarthritis with varus deformities were prospectively compared.Methods: Fifty patients undergoing sensor-assisted TKA (group S) and 50 patients receiving manually balanced TKA (group M) were prospectively compared. The groups did not differ in terms of demographics, preoperative clinical status, or severity of deformity. The knee and function scores (KS and FS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and range of motion (ROM) were evaluated clinically. The mechanical axes and positions of components were assessed radiographically. In sensor-assisted TKA, the medial and lateral compartment loads were compared based on the patellar positions of inversion and eversion.Results: There was no between-group difference in the postoperative KS or FS (n.s., respectively). The average postoperative WOMAC score was 17.0 in group S and 18.0 in group M (n.s.). The ROM was 131.2° in group S and 130.8° in group M (n.s.). Neither the postoperative alignment of the mechanical axis nor the component positioning differed between the groups (n.s.). In sensor-assisted TKA, the difference between the medial and lateral compartment loads was less than 15 lbs (6.8 kg) in each knee. The lateral compartment load increased after patellar eversion (p < 0.001).Conclusion: There are concerns about the cost-benefit ratio of the intraoperative load sensor, despite its advantage of more precisely assessing ligament balance without patellar eversion, which resulted in a smaller lateral gap. A long-term follow-up study with a large cohort is required.Level Of Evidence: II. [ABSTRACT FROM AUTHOR]

Purpose: Long-term clinical and radiographic results and survival rates were compared between closed-wedge high tibial osteotomy (HTOs) and fixed-bearing unicompartmental knee arthroplasty (UKA) in patients with similar demographics.Methods: Sixty HTOs and 50 UKAs completed between 1992 and 1998 were retrospectively reviewed. There were no significant differences in pre-operative demographics. The mean follow-up period was 10.7 ± 5.7 years for HTO and 12.0 ± 7.1 years for UKA (n.s.). The Knee Society knee and function scores, WOMAC, and range of motion (ROM) were investigated. The mechanical axis and femorotibial angle were evaluated. Kaplan-Meier survival analysis was performed (failure: revision to TKA) and the failure modes were investigated.Results: Most of the clinical and radiographic results were not different at the last follow-up, except ROM; ROM was 135.3° ± 12.3° in HTO and 126.8° ± 13.3° in UKA (p = 0.005). The 5-, 10-, 15-, and 20-year survival rates were 100%, 91.0%, 63.4%, and 48.3% for closed-wedge HTO, respectively, and 90.5%, 87.1%, 70.8%, and 66.4% for UKA (n.s.). The survival rate was higher than that for UKA until 12 years post-operatively but was higher in UKAs thereafter, following a remarkable decrease in HTO. The most common failure mode was degenerative osteoarthritic progression of medial compartment in HTO and femoral component loosening in UKA.Conclusions: Long-term survival did not differ significantly between closed-wedge HTO and fixed-bearing UKA in patients with similar pre-operative demographics and knee conditions. The difference in post-operative ROM and failure mode should be considered when selecting a procedure.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: This study was performed to prospectively compare the clinical and radiographic results between mobile-bearing (MB) and fixed-bearing (FB) TKAs using ceramic titanium nitride (TiN)-coated prostheses.Methods: Seventy MB and 70 FB TKAs using TiN-coated prostheses (ACS®) were prospectively evaluated. There were no differences in demographic characteristics between the two groups. Clinically, the Knee Society knee and function scores, WOMAC, and range of motion (ROM) were compared. Considering the possibility of a kinematic change in the polyethylene (PE) insert and a decrease in ROM following MB TKA, serial changes in the ROM were also compared. The thickness of the PE insert was compared according to the size of the femoral component. Radiographically, the alignment and positions of the components were compared.Results: There were no differences between the two groups in clinical scores or ROM (n.s.). The maximum flexion increased from 133.5° ± 8.3° to 137.6° ± 5.5° across all time points in the MB group. The serial maximum flexion angles did not differ between the two groups over time (n.s.). The average thickness of the PE insert was greater in the MB group (12.0 ± 1.9 vs. 11.2 ± 1.6 mm, respectively, p = 0.008), especially when a large femoral component was used (12.7 ± 1.9 vs. 11.0 ± 1.5 mm, p = 0.005). The pre- and postoperative mechanical axes and positions of the components did not differ between the two groups (n.s.).Conclusions: TiN-coated MB TKA showed no significant advantage over FB TKA. The selection of bearing design would be clinically insignificant when using the TiN-coated TKA prosthesis.Level Of Evidence: II. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to compare the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, including outcomes related to compatibility of the patellofemoral joint.Methods: The clinical and radiographic results of 81 patients (100 knees) who underwent TKA using the specific prosthesis (group A) were compared with those in a control group who underwent TKA using the other prosthesis (group B). The presence of anterior knee joint pain, patellar crepitation, and patellar clunk syndrome was also checked.Results: The function score and maximum flexion angle at the last follow-up were slightly better in group A than those in group B (92.0 ± 2.3 vs. 90.6 ± 4.2) (133.6° ± 8.4° vs. 129.6° ± 11.4°). Anterior knee pain was observed in 6 knees and patellar crepitation in four knees in group A. In group B, these symptoms were observed in 22 knees and 18 knees, respectively. There was no patellar clunk syndrome in either group. The alignment was corrected with satisfactory positioning of components. The patellar height remained unchanged after TKA in the two groups. The differences between preoperative and postoperative patellar tilt angle and patellar translation were small.Conclusion: When comparing the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, TKA using the specific prosthesis provided satisfactory results with less clinical symptoms related to the patellofemoral kinematics with TKA using the other prosthesis.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to compare mid-term clinical and radiographic results of conversion total knee arthroplasties (TKA) following a closed-wedge high tibial osteotomy (HTO) and primary TKAs.Methods: A total of 32 conversion TKAs (29 patients) were compared with a matched control group of patients who had undergone primary TKA. The clinical results were evaluated using the Knee Society Knee and Function score, the Western Ontario and McMaster Universities score, patella score, and range of motion (ROM). The radiographic results were evaluated using femorotibial angle, mechanical axis (MA), the method employed by the American Knee Society, joint line height (JLH), the amount of tibial bone resection, and the Insall-Salvati ratio. The clinical and radiographic results of conversion TKAs were compared with primary TKAs. The thickness of the polyethylene insert was also compared.Results: No significant differences were observed in the clinical scores or ROM between two groups. No significant differences were detected in femorotibial angle, MA, and position of the components between two groups. The amount of tibial bone resection and pre-operative JLH both were significantly lower in the conversion group than those in the control group, although postoperative JLH and pre and postoperative Insall-Salvati ratio did not differ between two groups. No significant difference in the thickness of the polyethylene insert was identified between two groups.Conclusions: The previous closed-wedge HTO itself had no detrimental effect on the mid-term outcome of the subsequent TKA, including patellar symptom and position. No significant differences in the postoperative joint line and patella height were detected between the conversion and primary TKA groups. [ABSTRACT FROM AUTHOR]

Abstract: Twenty-five total knee arthroplasties were performed in 21 patients with hemophilia. The mean patient age was 35.8 years and mean follow-up time was 6.2 years. The average preoperative knee score increased from 18.6 points (range, 3-29) to 82.8 points (range, 44-99). The average preoperative knee function score increased from 41.4 points (range, 20-60 points) to 75.8 points (range, 45-95 points). The average preoperative range of motion was 73.4° with an average flexion contracture of 22.6°, whereas the average postoperative range of motion increased to 92.2° with an average flexion contracture of 5.6°. Median consumption of coagulation factor concentrate decreased from 4837 U/month before operation to 1500 U/month 1 year after surgery. The total knee arthroplasty is a useful treatment in severe hemophilic arthropathy to obtain pain relief and functional improvement, and to reduce the need for ongoing treatment using coagulation factor concentrate. [Copyright &y& Elsevier]