Total Knee Arthroplasty Knee Research Articles

When does postoperative standing function after total knee arthroplasty improve beyond preoperative level of function?

The purpose of the current study was to investigate inpatient recovery process during relaxed standing, and to clarify the question of when postoperative standing function would improve beyond preoperative level of function following total knee arthroplasty (TKA). Thirty patients with bilateral knee osteoarthritis, averaged 75 years old, participated. Subjects underwent unilateral TKA. Evaluations were divided into two categories; subjective and objective components. Subjective component was based on pain level (Visual Analog Scale: 100 mm), and objective component consisted of vertical knee force (%BW) and knee flexion angle (degrees) during relaxed standing. Data evaluations were done pre- and post-operatively. Preoperative pain score was 69.1. After TKA, pain level became maximum (89.9) and significantly larger on postoperative day 3. Thereafter, pain gradually decreased, and it (60.4) was significantly smaller on postoperative day 8 than preoperative score. Preoperative vertical knee force was 43.5%BW. After TKA, it became minimum (32.8) on postoperative day 3. Thereafter, knee force gradually increased, and it (44.1) was significantly larger on postoperative day 17. Preoperative knee flexion angle was 15.6°. After TKA, knee flexion angle during standing became maximum (20.0) on postoperative day 4. Thereafter, subjects could gradually extend the knee, and on postoperative day 16, it (14.3°) was smaller. From our results, subjective pain was significantly reduced from postoperative day 8, and objective knee condition, including vertical knee force on TKA side and knee flexion angle on TKA side during standing, significantly became better from postoperative day 17 and 16, respectively.

Evaluation of joint laxity against distal traction force upon flexion in cruciate-retaining and posterior-stabilized total knee arthroplasty

BackgroundSeveral studies have reported varus-valgus stability in the extension position after total knee arthroplasty (TKA). However, few studies have evaluated joint laxity in the flexion position postoperatively. The purpose of the study was to evaluate joint laxity against distal traction force on flexion after cruciate-retaining and posterior-stabilized total knee arthroplasties. MethodsA total of 44 knees (22 knees cruciate-retaining, 22 knees posterior-stabilized) in 40 patients with osteoarthritis were tested in this study. The subjects were seated at a table and their knee joints were fixed at 80° of flexion to avoid overlapping images of condyles and the femoral shaft. Tibial shafts were adjusted to be parallel to the radiographic film s, and posteroanterior radiographs were obtained. Flexion stress tests were performed with a distal traction of 100 N at a neutral foot position. Radiographs were obtained at neutral and traction positions. The distance from the perpendicular line of the top of the polyethylene insert to the midpoint on the tangential line of the femoral condyle was measured (joint space distance) at each side. ResultsIn the flexion-neutral position, average joint space distances were 0.1 ± 0.2 mm in cruciate-retaining (CR) TKA knees and 0.2 ± 0.3 mm in posterior-stabilized (PS) TKA knees. With flexion-traction stress tests, the average joint space distances were 0.5 ± 0.5 mm in CR TKA knees and 2.4 ± 1.2 mm in PS TKA knees. Average changes of joint space distances between the two positions were 0.3 ± 0.4 mm (CR TKA) and 2.2 ± 1.5 mm (PS TKA). The changes in joint space distances between neutral and traction positions of PS TKA knees were significantly larger than those of CR TKA knees in flexion stress tests (P < 0.01). ConclusionThe posterior cruciate ligament acted as a stabilizer against distal traction force in the CR-TKA knees. However, the laxity of PS-TKA knees against distal force differed among individual cases.

Knee stability before and after total and unicondylar knee replacement: In vivo kinematic evaluation utilizing navigation

Surgical navigation systems are currently used to guide the surgeon in the correct alignment of the implant. The aim of this study was to expand the use of navigation systems by proposing a surgical protocol for intraoperative kinematics evaluations during knee arthroplasty. The protocol was evaluated on 20 patients, half undergoing unicondylar knee arthroplasty (UKA) and half undergoing posterior-substituting, rotating-platform total knee arthroplasty (TKA). The protocol includes a simple acquisition procedure and an original elaboration methodology. Kinematic tests were performed before and after surgery and included varus/valgus stress at 0 and 30 degrees and passive range of motion. Both UKA and TKA improved varus/valgus stability in extension and preserved the total magnitude of screw-home motion during flexion. Moreover, compared to preoperative conditions, values assumed by tibial axial rotation during flexion in TKA knees were more similar to the rotating patterns of UKA knees. The analysis of the anteroposterior displacement of the knee compartments confirmed that the two prostheses did not produce medial pivoting, but achieved a postoperative normal behavior. These results demonstrated that proposed intraoperative kinematics evaluations by a navigation system provided new information on the functional outcome of the reconstruction useful to restore knee kinematics during surgery.

Unicompartmental versus Total Knee Arthroplasty in the Same Patient

Purpose: To compare the clinical and radiographic results of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) in the same patient, and to investigate patient preference and satisfaction. Materials and Methods: Among the 56 patients who underwent a UKA in one knee and a TKA in the opposite knee between January 2002 and December 2004, 51 patients were followed up. The average follow-up period was 4 years. Results: The average Knee Society Score (KSS) improved from 53.5 preoperatively to 90.7 at last follow-up in the UKA knee, and from 50.4 to 89.8 in the TKA knee. The mean range of knee motion also improved from 124.7˚ to 133.2˚ in the UKA knee, and from 122.5˚ to 127.1˚ in the TKA knee. The tibiofemoral angle changed from 0.3˚ of varus to 5.6˚ of valgus in the UKA knee, and from 2.4˚ of varus to 5.8˚ of valgus in the TKA knee. For patient preference, 23 patients (45%) preferred the UKA knee and 19 patients (37%) preferred the TKA knee. Most patients (42 patients, 82%) reported being ‘very satisfied' or ‘satisfied' with both knees. Conclusion: The clinical and radiographic results of both the UKA and the TKA in the same patient were satisfactory at the 4-year follow-up. The UKA knee had a slightly better range of knee motion, but there was essentially no difference between the UKA knee and the TKA knee.

Effect of increased posterior tibial slope or partial posterior cruciate ligament release on knee kinematics of total knee arthroplasty

To compare the effects of increased posterior tibial slope or partial posterior cruciate ligament (PCL) release on knee kinematics of total knee arthroplasty (TKA). Anteroposterior laxity, rotational laxity, varus and valgus laxity and maximum flexion angle were evaluated in 6 normal cadaver knees and the knees after TKA at flexion 0 degrees , 30 degrees , 60 degrees , 90 degrees and 120 degrees . Then the femoral prosthesis was shifted 5 mm posteriorly to simulate the tightly implanted knee. The same tests were performed on the tightly implanted knees. After that, the posterior tibial slope was increased 4 degrees or the PCL was partially released, and the same tests were made as in the normal knees respectively. Statistical analysis of the results was made using student's t test. Anteroposterior laxity, rotational laxity and varus and valgus laxity of the tightly implanted knees at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees were significantly less than those of the normal TKA knees (P < 0.05). Compared with the tightly implanted knees, anteroposterior laxity, rotational laxity and varus and valgus laxity at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees significantly improved after increased 4 degrees posterior tibial slope (P < 0.05); in the partial PCL released group, anteroposterior laxity at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees was significantly improved (P < 0.05), varus and valgus laxity was significantly improved only at flexion 90 degrees (P < 0.05), and rotational laxity was significantly improved at flexion 30 degrees , 60 degrees and 90 degrees (P < 0.05). Compared with PCL released group, varus and valgus laxity at flexion 30 degrees , 60 degrees and 90 degrees and rotational laxity at flexion 0 degrees , 30 degrees , 60 degrees and 90 degrees were significantly improved in the group of increased 4 degrees posterior tibial slope (P < 0.05). Maximum flexion angle of the tightly implanted knee (120.4 degrees ) was less than that of the normal TKA knees (130.3 degrees , P < 0.05) and that of increased 4 degrees posterior tibial slope group (131.1 degrees , P < 0.05). There was no significant difference at the maximum flexion angle between the increased 4 degrees posterior tibial slope group and the PCL released group (131.1 degrees vs 124.0 degrees , P = 0.0816). Anteroposterior laxity, varus and valgus laxity, rotational laxity and maximum flexion angle of the tightly implanted knees are less than those of the normal TKA knees. After increased 4 degrees posterior tibial slope, these indexes are improved significantly. Partial PCL released can significantly improve the anteroposterior laxity and had less effect on the varus and valgus laxity, rotational laxity and maximum flexion angle. So, a knee that is tight in flexion can be more likely to be corrected by increasing posterior tibial slope than by partially releasing PCL.

Complex Regional Pain Syndrome Complicating Total Knee Arthroplasty

To compare the long-term outcome of patients diagnosed with complex regional pain syndrome-type 1 (CRPS-1) after total knee arthroplasty (TKA) with those of uncomplicated TKA knees and preoperative osteoarthritic knees. Medical records of 1280 patients who underwent TKA for osteoarthritis were retrospectively reviewed; 8 were diagnosed as having symptoms and signs consistent with CRPS after TKA. Patients with primary inflammatory arthritis, signs of component loosening, malpositioning, or of infected arthroplasty were excluded. No patient had signs of CRPS prior to operative intervention. The 8 patients were compared with 2 groups of age- and sex-matched controls: uncomplicated TKA knees and preoperative osteoarthritic knees. Patients were followed up for a mean of 54 (range, 13-111) months and their range of movement, Western Ontario and McMaster Universities Osteoarthritis Index, SF-36 questionnaire scores, and Knee Society scores were assessed and compared. After appropriate treatment, most CRPS complicated patients had similar scores on SF-36, Western Ontario and McMaster Universities Osteoarthritis Index, and Knee Society scores when compared with uncomplicated TKA patients. Scores for CRPS complicated patients were significantly improved when compared with preoperative osteoarthritic patients. The incidence of CRPS after TKA was 0.7%. When managed early, patients complicated with CRPS after TKA have a similar prognosis to patients with uncomplicated TKA.

Magnetic resonance imaging of in vivo kinematics after total knee arthroplasty

To improve the quality of magnetic resonance imaging (MRI) on knees after total knee arthroplasty (TKA) by minimizing image artifacts caused by metallic implants, and to establish a method determining in vivo kinematics of TKA knees using MRI. Two knee implants made of cobalt-chrome and oxidized zirconium were tested with different pulse sequences and imaging parameters. Then, in vivo kinematic MRI was performed on five well-functioning TKAs under simulated weight-bearing conditions. Kinematic measurements were made and a linear correlation test was run between the tibio- and patellofemoral measurements. The best images with minimum metallic artifacts were observed using oxidized zirconium implants, a fast spin echo sequence (FSE), thin slice thickness, and high readout gradient. TKA kinematics exhibited a large deviation from the normal kinematics and considerable patient-to-patient variability. However, significant linear correlations between tibiofemoral and patellofemoral kinematics were observed (R = -0.96, 0.92, 0.88). Metallic artifacts due to orthopedic implants can be reduced in MR images for some materials, appropriate pulse sequence, and imaging parameters selection, enabling MR quantification of knee kinematics. Tibiofemoral kinematics appears to affect patellofemoral position after total knee arthroplasty.

Anterior tibial post impingement in a posterior stabilized total knee arthroplasty

Despite the numerous long-term success reports of posterior stabilized (PS) total knee arthroplasty (TKA), recent retrieval studies of various PS TKA designs revealed wear and deformation on the anterior side of the tibial post. This study investigated the mechanisms of anterior impingement of the post with the femoral component. Seven cadaveric knees were tested to study kinematics and tibial post biomechanics during simulated heel strike using an in vitro robotic testing system. Intact knee kinematics and in situ anterior cruciate ligament (ACL) forces were determined at hyperextension (0° to −9°) and low flexion angles (0° to 30°) under the applied loads. The same knee was reconstructed using a PS TKA. The kinematics and the tibial post contact forces of the TKA were measured under the same loading condition. The ACL in the intact knee carried load and contributed to knee stability at low flexion angles and hyperextension. After TKA, substantial in situ contact forces (252.4 ± 173 N at 9° of hyperextension) occurred in the tibial post, indicating anterior impingement with the femoral component. Consequently, the TKA showed less posterior femoral translation compared to the intact knee after the impingement. At 9° of hyperextension, the medial condyle of the intact knee translated 0.1 ± 1.1 mm whereas the medial condyle of the TKA knee translated 5.6 ± 6.9 mm anteriorly. The lateral condyle of the intact knee translated 1.5 ± 1.0 mm anteriorly whereas the lateral condyle of the TKA knee translated 2.1 ± 5.8 mm anteriorly. The data demonstrated that anterior tibial post impingement functions as a substitute for the ACL during hyperextension, contributing to anterior stability. However, anterior post impingement may result in additional polyethylene wear and tibial post failure. Transmitted impingement forces might cause backside wear and component loosening. Understanding the advantages and disadvantages of the tibial post function at low flexion angles may help to further improve component design and surgical techniques and thus enhance knee stability and component longevity after TKA.

Measurement of bone density around total knee arthroplasty using fan-beam dual energy X-ray absorptiometry.

The clinical survival of joint arthroplasties is clearly associated with the quality of surrounding bone environment. Bone mineral density (BMD) is an important measure of bone strength and quality. Periprosthetic BMD can be measured by using dual-energy X-ray absorptiometry (DXA) with special software algorithms. We studied short-term reproducibility of the periprosthetic BMD measurements after total knee arthroplasty (TKA) in 30 patients with primary osteoarthrosis. The operated knees and the contralateral control knees were measured twice and the results were expressed as a coefficient of variation (CV%). The average precision error was 3.1% in femoral regions of interest (ROI) and 2.9% in tibial ROIs after TKA. In the prosthesis-free control knees, CV% were similar; 3.2% and 2.5%, respectively. The best precision was found in the femoral diaphyses above the implant (1.3%), whereas the least reproducible BMD was determined in the patellar region of the TKA knees (6.9%). Our results confirm that DXA measures precisely small bone mineral changes around TKA and makes it possible to follow bone remodeling DXA and may provide a feasible method for monitoring TKA in the future.

Incidence of fatal pulmonary embolism after 1,390 knee arthroplasties without routine prophylactic anticoagulation, except in high-risk cases

A consecutive series of 1,390 primary total knee arthroplasty (TKA) procedures (1,201 patients, 1,600 arthroplasties) performed between January 1980 and July 1994 were reviewed to establish the incidence of death from pulmonary embolism (PE). Nine hundred twenty-three bi- or tricompartment TKAs and 467 unicompartment TKAs were performed as one-stage procedures. Chemical thromboprophylaxis was used only in high-risk cases in which there was a history of previous thromboembolism or obesity. There were no deaths from PE after unicompartment arthroplasty procedures. Autopsy confirmed PE as the cause of death in 2 patients following bi- and tricompartment TKAs (0.22%; 95% confidence interval [CI], 0.03-0.8%). The incidence was higher for one-stage bilateral TKA as 1 of the autopsy-confirmed deaths occurred in this group 0.7% (95% CI, 0.02–3.78%). Two other deaths were certified without postmortem examination (pneumonia and myocardial infarction in each case). As PE could not be ruled out as the cause of death in the latter 2 cases, these were considered as possible PE deaths to provide the maximum possible death rate that could result. Thus, the maximum possible incidence of fatal PE after TKA without routine use of chemical anticoagulation was 0.4% (95% CI, 0.1–1.1%). It is concluded that the risk of fatal PE after unilateral TKA and unicompartment knee arthroplasty is low. The risk of clinical, nonfatal thromboembolic events, which might themselves warrant prophylaxis, was not quantified in this article.

Unicompartmental Versus Total Knee Arthroplasty in the Same Patient

The purpose of this study was to compare unicompartmental knee arthroplasty (UKA) with total knee arthroplasty (TKA) and more specifically to evaluate the role of the patella in patient preference between UKA and TKA. A group of 23 patients were chosen, each with a UKA in one knee and a TKA in the opposite knee. As a subset of the group, 13 patients were compared who had not had patellar resurfacing on their TKA side (Group A) versus ten patients who had patellar resurfacing (Group B). Each patient had a UKA and TKA performed during the same hospitalization. Each patient's resurfacing was performed by the same surgical team. Moreover, inpatient care and physical therapy for each patient's respective UKA and TKA were the same. Patient evaluation consisted of chart review, joint registry data, and telephone interviews that focused on patient preference regarding pain, stability, "feel," and ability to climb stairs. The 23 patients studied had an average follow-up period of 81 months (range, 38-153 months). There were 14 men and ten women with an average age of 67 years. Preoperative diagnosis was osteoarthritis in 22 patients and rheumatoid arthritis in one patient. Range of motion (ROM) improved from a preoperative mean of 106 degrees to 123 degrees postoperatively on the UKA side. Mean ROM for the Group A TKAs improved from 104 degrees to 109 degrees, whereas the Group B TKAs remained unchanged at 113 degrees. For patients surveyed in Group A, 31% stated that their UKA knee was their better knee overall, 15% stated that their TKA knee was their better knee overall, and 54% could find no difference.(ABSTRACT TRUNCATED AT 250 WORDS)