The anteroposterior distance between the posterior edge of the medial tibial condyle and the posterior edge of the fibular head in the lateral view can be a reference in determining the axis perpendicular to the tibial anteroposterior axis.

BACKGROUND: Obtaining an accurate tibial lateral view is important during high tibial osteotomy. This study investigated whether the posterior edge of the medial/lateral tibial condyle (PEMTC/PELTC) and the posterior edge of the fibular head (PEFH) in a lateral view could be a reference for determining the accurate tibial lateral view. METHODS: A total of 75 lower limbs in 38 subjects were evaluated in this study. In order to target healthy knees, subjects undergoing primary total hip arthroplasty were selected. The MF/LF, comprising the anteroposterior distance between PEMTC/PELTC and PEFH, was measured on the lateral view of the tibial bone model based on the tibial anteroposterior (AP) axis (true lateral view: TLV). In addition, measurements were calculated in the model with a 10° external/internal rotation. Using these measurements, linear regression analysis was performed to predict the tibial rotation with MF/LF. RESULTS: The mean MF/LF was 0.9/4.6 mm (P < 0.001). MF and LF increased with incremental tibial rotation. Regression formulas were derived from these results as follows: Tibial rotation = (1) -1.01 + 1.06 × MF (R2 = 0.87, P < 0.001), (2) -8.70 + 1.86 × LF (R2 = 0.51, P < 0.001). The mean tibial rotation angle when MF was 0 mm was -0.9°. CONCLUSIONS: Based on formula (1) and actual measurements, the mean tibial rotation angle when MF is 0 mm is an internal rotation of about 1°. Therefore, a lateral view, in which PEMTC and PEFH are seen colinearly, can be the approximate TLV. The MF can be a suitable intraoperative reference in determining TLV.

The medial tangent of the proximal tibia is a suitable extra-articular landmark in determining the tibial anteroposterior axis.

BACKGROUND: Tibial rotational alignment in total knee arthroplasty (TKA) is generally determined based on intra-articular structure, and can be difficult to ascertain in some cases. The aim of this study was to investigate whether the medial tangent angle of the tibia (MTAT) could be useful in determining the anteroposterior axis of the tibia. METHODS: This study was performed on 103 lower limbs in 53 patients who underwent primary total hip arthroplasty. The selection criteria for our study were based on the assumption that knees in patients undergoing THA exhibit fewer degenerative changes than knees in patients undergoing TKA. Using computed tomography images, the MTAT, comprising the medial tangent of the proximal tibia and the anteroposterior (AP) axis of the tibia, was measured on three horizontal planes: at the distal edge of the tibial tubercle (A), at 5 cm distally (B), and at 10 cm further distally (C). The tibial medial surface was grouped into three classes according to shape: valley type, flat type, and hill type. The percentage at which these shapes were observed in each group was also calculated. Measurement reliability was calculated using the intraclass correlation coefficient. RESULTS: The angles were 45.2° (interquartile range: IR 43.0-47.7) at A, 42.7° (IR 38.7-45.9) at B, and 42.4° (IR 38.2-45.9) at C. Intra-rater reliability and inter-rater reliability was 0.982 and 0.974 at A, 0.810 and 0.411 at B, and 0.940 and 0.811 at C, respectively. Regarding the tibial medial surface, the valley type was observed in all cases at A, and the hill type was observed in the highest percentage of cases at B and C. CONCLUSIONS: The MTAT was approximately 45° at level A, and reproducibility was the highest among the three groups. The two points forming the valley on the tibial medial surface were bony ridges. Therefore, the medial tangent of the tibia at level A could be easily determined. Because the distal edge of the tibial tubercle exists at the surgical area and the extra-articular area, it can be a suitable intraoperative, extra-articular landmark in determining the tibial AP axis, even for revision TKA.

Semi-constrained posterior stabilized total knee arthroplasty reproduces natural deep knee bending kinematics.

BACKGROUND: The Flexible Nichidai Knee Posterior Stabilized (FNK-PS) system was designed to provide relatively high varus-valgus stabilities without the stem extensions to patients with severe knee joint disorders. This is a combination of a large tibial post and high femoral cam adapted to a PS system. The aim of our study was to analyze the in vivo two-dimensional/three-dimensional registration kinematics of the FNK PS-total knee arthroplasty (TKA) system during deep knee bending. METHODS: Nineteen knees from 15 total knee arthroplasty (TKA) patients who were able to squat with enough knee flexion were selected. During deep knee bending under weight bearing (WB) and non-weight bearing (NWB) conditions, we quantified range of motion, axial rotation, femoral anteroposterior translation, and post-cam engagement angle. RESULTS: The maximum-flexion was significantly different between the two conditions. The mean axial femoral external rotation was 4.8° and 6.2° under WB and NWB conditions, respectively, at 120° flexion. Anteroposterior translation based on bicondylar posterior roll-back patterns was noted with increasing knee flexion. Both the medial and lateral femoral aspects were significantly more posterior during early to mid-flexion. Initial post-cam engagement occurred significantly earlier during flexion under NWB than under WB conditions. Under WB, the timing of the post-cam engagement correlated with the maximum flexion . CONCLUSIONS: The kinematics of the semi-constrained PS system reproducibly exhibited a mild external rotation with smooth posterior roll-back. This was assisted by the engagement of the large tibial post and high femoral cam during the early phase of flexion.

Does cruciate-retaining total knee arthroplasty enhance knee flexion in Western and East Asian patient populations? A meta-analysis.

INTRODUCTION: This study analyzed the published data to examine if CR TKAs can enhance the flexion and functional outcomes of the knee in the Western and East Asian populations using a meta-analysis approach. MATERIALS AND METHODS: A systematic review of literature published through Medline and EMBASE was conducted. The inclusion criteria were: primary TKA, follow up duration greater than one year, a fixed bearing CR prosthesis, and data for maximum pre- and post-operative flexion along with standard deviations or errors. We estimated the weighted mean differences between pre- and post-operative flexion, extension and knee scores (KSS and HSS) via a random effect model. RESULTS: Seventeen articles were selected and reviewed among 1229 studies that included 1090 knees of the Western and 516 knees of the East Asian. No significant difference was noted in maximal knee flexion pre- and post-operatively, when all the studies were pooled together (-0.17°, p=0.93, post-operative

Safety of fondaparinux versus enoxaparin after TKA in Japanese patients.

Fondaparinux and enoxaparin are useful for preventing venous thromboembolism after total knee arthroplasty (TKA), but both drugs have associated complications. The purpose of this study was to clarify the risks associated with use of these drugs in Japanese patients who underwent TKA.A total of 575 patients (935 knees) underwent TKA and were retrospectively reviewed; 277 patients (454 knees) were treated with fondaparinux and 298 patients (481 knees) were treated with enoxaparin. The authors investigated the incidences of deep venous thrombosis of the lower limbs and pulmonary embolism to evaluate venous thromboembolism, knee enlargement compared with the preoperative size, incidence of subcutaneous knee hematoma, and other complications. No significant differences were observed between the 2 drugs regarding the incidences of deep venous thrombosis and pulmonary embolism. However, fondaparinux use resulted in knee enlargement (P<.0005) and subcutaneous hematoma of the knee (P=.035) significantly more often than enoxaparin use. Conversely, enoxaparin use significantly caused the elevation of alanine aminotransferase (one of the liver enzymes) at a higher rate than fondaparinux (30.1% vs 8.3%, respectively; P<.0001). However, the increased alanine aminotransferase levels were transient, and no patient exhibited symptoms of abnormal liver function, such as jaundice or cutaneous pruritus.Fondaparinux and enoxaparin were both effective in preventing venous thromboembolism in Japanese patients undergoing elective TKA. However, both drugs had some adverse effects. It is important to be aware of these potential risks when prescribing these drugs.

Long-term oral administration of glucosamine or chondroitin sulfate reduces destruction of cartilage and up-regulation of MMP-3 mRNA in a model of spontaneous osteoarthritis in Hartley guinea pigs.

Histological and molecular changes were examined to investigate the effects of long-term administration of glucosamine (GlcN) and chondroitin sulfate (CS) in a model of spontaneous osteoarthritis (OA) in Hartley guinea pigs. Three groups of female 3-week-old Hartley guinea pigs received GlcN, CS, and neither agent, respectively. Five animals in each group were sacrificed at 8, 12, and 18 months of age. At 8 months of age, Hartley guinea pigs had severe degeneration of knee joint cartilage, chondrocyte apoptosis, marked reduction of tissue total RNA, decreases of aggrecan and collagen type 2 mRNAs, and increases in MMP-3 and MMP-8 mRNAs. Long-term administration of GlcN and CS reduced cartilage degeneration at 8 months of age. The marked loss of total RNA and the increase in MMP-3 mRNA were also inhibited by GlcN and CS. Thus, long-term oral administration of GlcN or CS inhibits OA progression, maintains total RNA and down-regulates MMP-3 mRNA in a spontaneous OA model in Hartley guinea pigs.

Asian-specific total knee system: 5-14 year follow-up study.

BACKGROUND: Knee size and body size differ in Asians compared with Caucasians. Nevertheless, many total knee arthroplasty (TKA) prostheses used worldwide are made for Western Caucasian subjects. As a result, an Asian's knee might not fit these prostheses. We studied the Flexible Nichidai Knee (FNK) system, a new model of TKA for Asian patients. The purpose of this report is to investigate the outcomes of this prosthesis retrospectively. METHODS: We investigated 1055 primary TKAs in 595 patients who underwent FNK for osteoarthritis (OA) in Japan and were followed for > 5 years. The knee score and function score were used for clinical evaluation. We examined the range of motion (ROM) preoperatively and at final follow-up and radiographic assessments. In addition, postoperative complications were investigated. A survivorship analysis was also conducted using two endpoints: revision for any reason and aseptic failure. RESULTS: 890 knees in 502 patients were available for study (follow-up rate of 96.0%). The mean follow-up term was 8.3 years (range, 5.0-14.1 years). The knee and function score significantly improved from 41.3 to 90.3 and from 39.1 to 76.2 points, respectively (p < 0.001). The mean ROM in FNK posterior cruciate retaining (CR) type and FNK posterior-stabilized (PS) type ameliorated significantly from 107.8° and 95.6° to 110.7° and 110.4°, respectively (p < 0.01). Ten knees underwent revision surgery (infection in 3 cases, instability in 2, loosening in 2, and non-union of femoral supracondylar fracture, severe pain, and recurrent hemarthrosis in 1 each). The survivorship rate was 99.4% (95% CI, 99.0-99.8) at 5 years (n = 952 patients at risk) and 96.2% (95% CI, 91.9-100) at 12.5 years (n = 49 patients at risk). CONCLUSION: The FNK prosthesis for Asians achieved excellent mid- to long-term survivorship and clinical results.

Do high flexion posterior stabilised total knee arthroplasty designs increase knee flexion? A meta analysis.

PURPOSE: This systematic literature review analysed the change in range of knee flexion from pre-operative values, following conventional posterior stabilised (PS) and high-flexion (H-F) PS total knee arthroplasty (TKA). METHODS: We calculated the weighted mean differences of pre- and postoperative flexion using meta-analysis with random effect modelling. Eighteen studies met our inclusion criteria. These data included a total of 2,104 PS knees that received conventional implants and 518 knees that received H-F implants. RESULTS: The pooled gain in flexion was 4.70° in the conventional group (p <0.0001) and 4.81° in the H-F group (p = 0.0008). In the subgroup analysis, the Western patient group showed significant difference in the gain of flexion with both implants. In contrast, no significant gain in flexion was observed in the Asian patient group. CONCLUSIONS: These results suggest that improvement of preoperative flexion after TKA using current H-F PS prostheses is similar to that of conventional PS prostheses.