The influences of posterior tibial slope on the knee kinematics have been reported in both TKA and UKA. We hypothesized the posterior tibial slope (PTS) would affect the sagittal knee alignment after UKA. The influences of PTS on postoperative knee extension angle were investigated with routine lateral radiographies of the knee after UKA. Twenty-four patients (26 knees; 19 females, 7 males) underwent medial UKA were involved in this study. Average age was 74.8 ± 7.2 years. The mean preoperative active range of motion were − 4.1° ± 6.3°in extension and 123.2° ± 15.5° in flexion. All UKAs were performed using fixed bearing type UKA (Zimmer Biomet, ZUK), with adjusting the posterior slope of the proximal tibial bone cut according to the original geometry of the tibia. Routine lateral radiographies of the knee were examined preoperatively, 6 months after the surgery. PTS and knee extension angles with maximal active knee extension (mEXT) and one-leg standing (sEXT) were radiographically measured. We used the fibular shaft axis (FSA) for the sagittal mechanical axis of the tibia. PTS was defined as the angle between the medial tibial plateau and the perpendicular axis of FSA. Extension angles (mEXT and sEXT) were defined as the angles between FSA and distal femoral shaft axis (positive value for hyperextension). The changes of PTS and the influences of PTS on sEXT at each time period were analyzed using simple linear regression analysis (p<0.05).Introduction
Materials & Methods
Patients-reported outcome measures (PROMs) have been reported as the important methods to evaluate clinical outcomes in total knee arthroplasty (TKA). The patient satisfaction score in Knee Society Score (KSS-2011) has been used in the recent literatures. Patient satisfaction was subjective parameter, and would be affected by multiple factors including psychological factors and physical conditions at not only affected joint but also elsewhere in the body. The question was raised regarding the consistency of patient satisfaction score in KSS-2011 to other PROMs. The purpose of this study was to investigate the correlation of patient satisfaction in KSS-2011 to other categories in KSS-2011 and to other PROMs including Forgotten Joint Score (FJS-12), EuroQol-5 Dimensions (EQ-5D) and 25-questions in Geriatric Locomotive Function Scale (GLFS-25). 83 patients over 65 years old with osteoarthritic knees were involved in this study. All patients underwent CR-TKAs (Persona CRR). The means and ranges of demographics were as follows: age; 74.5 years old (65–89), Hip-Knee-Ankle (HKA) angle; 12.4 (−6.2–22.5) in varus. We asked patients to fulfill the questionnaire including KSS-2011, FJS-12, EQ-5D and GLFS-25 at 1-year postoperative follow-up visit. KSS-2011 consisted of 4 categories of questions; patient satisfaction (PS), symptoms, patient expectations (PE), functional activities (FA). We evaluated the correlation of PS to other PROMs using simple linear regression analyses (p<0.001).Introduction
Material & Method
Both measured resection technique and gap balancing technique have been important surgical concepts in total knee arthroplasty (TKA). Modified gap technique has been reported to be beneficial for the intra-operative soft tissue balancing in posterior-stabilizing (PS) -TKA. On the other hand, we have found joint distraction force changed soft tissue balance measurement and medial knee instability would be more likely with aiming at perfect ligament balance at extension in modified gap technique. The medial knee stability after TKA was reported to essential for post-operative clinical result. We have developed a new surgical concept named as “medial preserving gap technique” for varus type osteoarthritic (OA) knees to preserve medial knee stability and provide quantitative surgical technique using tensor device. The purpose of this study was to compare post-operative knee stability between medial preserving gap technique (MPGT) and measured resection technique (MRT) in PS-TKA. The subjects were 140 patients underwent primary unilateral PS-TKA for varus type OA knees. The surgical technique was MPGT in 70 patients and MRT in 70 patients. There were no significant differences between two groups in the pre-operative clinical features including age, sex, ROM and deformity. Originally developed off-set type tensor device was used to evaluate both center gap and varus angle with 40 lbs. of joint distraction force. The extension gap preparation was identical in both group. In MPGT group, femoral component size and external rotation angle were adjusted depending on the differences of center gaps and varus angles between extension and flexion before posterior femoral condylar osteotomy. The knee stabilities at extension and flexion were assessed by stress radiographies; varus-valgus stress test with extension and stress epicondylar view with flexion, at one-month and one-year after TKA. We measured joint opening distance (mm) at medial and lateral compartment at both knee extension and flexion. Joint opening distances were compared between two groups using unpaired t-test, and the difference between medial and lateral compartment in each group was compared using paired t- test (p<0.05).Introduction
Material & Method
In recent literatures, medial instability after TKA was reported to deteriorate early postoperative pain relief and have negative effects on functional outcome. Furthermore, lateral laxity of the knee is physiological, necessary for medial pivot knee kinematics, and important for postoperative knee flexion angle after cruciate-retaining total knee arthroplasty (CR-TKA). However, the influences of knee stability and laxity on postoperative patient satisfaction after CR-TKA are not clearly described. We hypothesized that postoperative knee stability and ligament balance affected patient satisfaction after CR-TKA. In this study, we investigated the effect of early postoperative ligament balance at extension on one-year postoperative patient satisfaction and ambulatory function in CR-TKAs. Sixty patients with varus osteoarthritis (OA) of the knee underwent CR-TKAs were included in this study. The mean age was 73.6 years old. Preoperative average varus deformity (HKA angle) was 12.5 degrees with long leg standing radiographs. The knee stability and laxity at extension were assessed by stress radiographies; varus-valgus stress X-ray at one-month after operation. We measured joint separation distance (mm) at medial compartment with valgus stress as medial joint opening (MJO), and distance at lateral compartment with varus stress as lateral joint opening (LJO) at knee extension position. To analyze ligament balance; relative lateral laxity comparing to the medial, varus angle was calculated. New Knee Society Score (NKSS) was used to evaluate the patient satisfaction at one-year after TKA. We measured basic ambulatory functions using 3m timed up and go test (TUG) at one-year after surgery. The influences of stability and laxity parameters (MJO, LJO and varus angle at extension) on one-year patient satisfaction and ambulatory function (TUG) was analyzed using single linear regression analysis (p<0.01).Background
Materials & Methods
Knee osteoarthritis (OA) is a major cause of ambulatory disabilities. Although total knee arthroplasty (TKA) has been reported as the most effective treatment for severe knee OA, quantitative evaluation of ambulatory function have not been well investigated. We hypothesized that better functional recovery would result in better patient satisfaction. The purpose of this study was to quantitatively evaluate ambulatory functional recovery and assess the influence on patient satisfaction after TKA. 90 patients (80 females and 10 males) were involved in this study. The mean age at TKA was 75.2 ± 5.8 years. Patients were subjected to 3 meters timed up and go test (TUG) to evaluate ambulatory function. TUG was performed at 6 time periods; before surgery, 2 weeks, 1, 3, 6 months, and 1 year after surgery. We also asked the patients to fill out the questionnaire of patient satisfaction category in the New Knee Society Score at 1 year after TKA. The sequential changes in TUG were analyzed using repeated measures ANOVA (p<0.05). The influences of each parameter (age, TUGs) on the patient satisfaction score were analyzed with simple regression analysis (p<0.05).Background
Material and Methods
As the aging society progresses rapidly in Japan, the number of elderly patients underwent TKA is increasing. These elderly patients do not expect to do sports, but regain independency in the activity of daily living. Therefore, we measured basic ambulatory function quantitatively using 3m timed up and go (TUG) test. We clinically experienced patient with medially unstable knee after TKA was more likely to result in the unsatisfactory outcome. We hypothesized that post-operative knee stability influenced ambulatory function recovery after TKA. In this study, we evaluated ambulatory function and knee stability quantitatively, and analyzed the effect of knee stability on the ambulatory function recovery after TKA. Seventy nine patients with varus type osteoarthritic knees underwent TKA were subjected to this study. The mean age of surgery was 72.4 years old. Preoperative standing coronal deformity was 9.6 degrees in varus. TUG test results in less duration with faster ambulatory function. TUG (seconds) was measured at 3 time periods; pre-operatively, at hospital discharge and 1year after surgery. To standardize TUG recovery time during 1 year after TKA, we defined TUG recovery rate as the percentage of recovery time to the pre-operative TUG as shown in the following equation. TUG recovery rate (%) = (TUG pre-op –TUG 1y po) / TUG pre-op ×100 We also evaluated the knee stability at hospital discharge and 1year after surgery. The knee stability at extension and flexion were assessed by varus and valgus stress radiography using Telos (10kg) and stress epicondylar view with 1.5kg weight at the ankle respectively. Image analyzing software was used to measure joint separation distance (mm) at medial as medial joint opening (MJO) and at lateral as lateral joint opening (LJO) at both knee extension and flexion. (Fig.1) The sequential change of TUG was analyzed using repeated measures ANOVA (p<0.05). The influence of joint opening distances (MJO and LJO at extension and flexion) on TUG 1y po and TUG recovery rate were analyzed using simple linear regression analysis (p<0.05).Objective
Materials & Methods
Although gap balancing technique has been reported to be beneficial for the intra-operative soft tissue balancing in posterior-stabilized (PS)-TKA, excessive release of medial structures for achieving perfect ligament balance would be more likely to result in medial instability, which would deteriorate post-operative clinical results. We have modified conventional gap balancing technique and devised a new surgical concept; named as “medial gap technique” aiming at medial stability with permitting lateral looseness, as physiologically observed in normal knee. We compared intra-operative soft tissue balance between medial gap technique (MGT) and measured resection technique (MRT) in PS-TKAs.Introduction
Objective
To achieve well aligned and balanced knee is essential for the post-operative outcome in total knee arthroplasty (TKA). Gap balancing technique can adjust the bone cut depending on the soft tissue balance in addition to soft tissue releases. Therefore, gap balancing technique would be more advantageous in soft tissue balance comparing to measured resection technique (MRT) in which soft tissue balancing relayed on soft tissue releases alone. Nevertheless, the influence of surgical technique on the post-operative knee stability has not been fully investigated. We introduced a new surgical technique (medial gap technique: MGT) according to modified gap technique regarding medial knee stability as important. The intra-operative soft tissue balance and post-operative knee stability were compared between MGT and MRT in posterior-stabilized (PS) TKA for varus type osteoarthritic knees.Introduction
Objective
As the aging society progresses rapidly, the number of patients underwent total knee arthroplasty (TKA) is increasing especially for the elderly population. In Japan, the average age for TKA is around 75 years old. Japanese Orthopaedic Association indicated a new clinical entity of musculoskeletal ambulation disability symptom complex (MADS) to define the higher risk of fall and ambulatory disability in the elderly population in 2006. The diagnosing criteria for MADS consists of 2 simple performance tests. 3m timed up and go test (TUG) evaluates ambulatory function, and one leg standing time (ST) assesses balancing ability. In this study, we analyzed the effect of TKA on the ambulatory function by quantitative measurement using 2 simple performances test: TUG and ST.Introduction
Objective
The goal of total knee arthroplasty (TKA) is to achieve a stable and well-aligned tibiofemoral and patello-femoral (PF) joint, aiming at long-term clinical patient satisfaction. The surgical principles of both cruciate retaining (CR) and posterior stabilized (PS) TKA are accurate osteotomy and proper soft tissue balancing. We have developed an offset-type tensor, and measured intra-operative soft tissue balance under more physiological joint conditions with femoral component in place and reduced PF joint. In this study, we measured intra-operative soft tissue balance and assessed the post-operative knee joint stability quantitatively at one month, six months and one year after surgery, and compared these parameters between CR and PS TKAs. Sixty patients with varus osteoarthritis of the knee underwent TKAs (30 CR TKAs: CR and 30 PS TKAs: PS). Mean varus deformity in standing position was 11.1 degrees in CR, and 12.6 degrees in PS. All TKAs were performed by a single surgeon with measured resection technique. The external rotation of posterior femoral condyle osteotomy was performed according to surgical epicondylar axis in pre-operative CT. We measured intra-operative soft tissue balance using an offset-type tensor with 40 lbs of joint distraction force at 0, 10, 30, 45, 60, 90, 120 and 135 degrees of flexion. The joint component gap (mm) and varus angle (degrees) were measured at each flexion angles. One month, six months and one year after surgery, we evaluated the knee stability at extension by varus and valgus stress radiography using Telos (10kg) and at flexion by epicondylar view with 1.5kg weight at the ankle. We measured joint separation distance at medial as medial joint looseness (MJL) and at lateral as lateral joint looseness (LJL). Intra-operative measurements and post-operative joint stabilities were compared between CR and PS using unpaired t-test. The change of joint looseness in each group was analyzed using repeated measures ANOVA.Objective
Material and Method
Appropriate osteotomy alignment and soft tissue balance are essential for the success of total knee arthroplasty (TKA). The management of soft tissue balance still remains difficult and it is left much to the surgeon's subjective feel and experience. We developed an offset type tensor system for TKA. This device enables objective soft tissue balance measurement with more physiological joint conditions with femoral trial component in place and patello-femoral (PF) joint reduced. We have reported femoral component placement decreased extension gap. The purpose of the present study was to analyze the influence of femoral component size selection on the decrease of extension gap in posterior-stabilized (PS) TKA. 120 varus type osteoarthritic knees implanted with PS TKAs (NexGen LPS flex: Zimmer) were subjected to this study. All TKAs were performed using measured resection technique with anterior reference. The femoral component size was evaluated intra-operatively using conventional femoral sizing jig. The selected femoral component size was expressed by the antero-posterior (AP) size increase (mm) comparing to that of original femoral condyles. Gap measurements were performed using a newly developed offset type tensor device applying 40lbs (178N) of joint distraction force. Firstly, conventional osteotomy gaps (mm) were measured at extension and flexion. Secondary, component gaps (mm) after femoral trial placement with PF joint reduced were evaluated at 0° and 90° of knee flexion. To compare conventional osteotomy gaps and component gaps, estimated extension and flexion gaps were calculated by subtracting the femoral component thickness at extension (9mm) and flexion (11mm) from conventional osteotomy gaps respectively. The decrease of gap at extension and flexion were calculated with estimated gaps subtracted by component gaps. The simple linear regression analysis was used to evaluate the influence of selected femoral component size on the decrease of gap after femoral component placement.Introduction
Material & Method
The goal of total knee arthroplasty (TKA) is to achieve a stable and well-aligned tibiofemoral and patello-femoral (PF) joint, aiming at long-term clinical patient satisfaction. The surgical principles of both cruciate retaining (CR) and posterior stabilized (PS) TKA are accurate osteotomy and proper soft tissue balancing. We have developed an offset-type tensor, and measured intra-operative soft tissue balance under more physiological joint conditions with femoral component in place and reduced PF joint. In this study, we measured intra-operative soft tissue balance and assessed the early post-operative knee joint stability quantitatively, and compared these parameters between CR and PS TKA. Seventy patients with varus osteoarthritis of the knee underwent TKAs (35 CR TKAs: CR and 35 PS TKAs: PS). Mean varus deformity in standing position was 9.8 degrees in CR, and 10.7 degrees in PS (p = 0.45). All TKAs were performed by a single surgeon with measured resection technique. The external rotation of posterior femoral condyle osteotomy was performed according to surgical epicondylar axis (SEA) in pre-operative CT. We measured intra-operative soft tissue balance using an offset-type tensor with 40 lbs of joint distraction force at 0, 10, 30, 45, 60, 90, 120 and 135 degrees of flexion. The joint component gap (mm) and varus angle (degrees) were measured at each flexion angle. Four weeks after operation, we evaluated the knee stability at extension by varus and valgus stress radiography using Telos (10 kg) and at flexion by epicondylar view with 1.5 kg weight at the ankle. We measured joint separation distance at medial as medial joint looseness (MJL) and at lateral as lateral joint looseness (LJL). Joint looseness was defined as the average of MJL and LJL. Intra-operative measurements and post-operative joint stabilities were compared between CR and PS using unpaired t-test.Objective
Material and Method
