Postoperative Maximum Flexion Research Articles

Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting total knee arthroplasty.

To investigate the correlation between intraoperative tibiofemoral anteroposterior changes at 90° of flexion and postoperative maximum flexion angles in navigated cruciate-substituting TKA. The hypothesis of this study was that intraoperative tibiofemoral anteroposterior changes at 90° of flexion indirectly reflect posterior cruciate ligament (PCL) function and associate with postoperative maximum flexion angles. Fifty-five consecutive patients with varus osteoarthritis treated with primary TKA were retrospectively analysed. All patients received the same type of implant, placed with an image-free navigation system. The PCL was retained, and cruciate-substituting inserts were used in all cases. The mean follow-up was 44 ± 8months. The preoperative and postoperative kinematics were measured intraoperatively with a navigation system, and the preoperative and postoperative tibiofemoral anteroposterior positions at 90° of flexion were determined. The correlation between intraoperative anteroposterior position changes and postoperative maximum flexion angles was investigated. The correlation between the change of anteroposterior position and tibiofemoral rotational angles was also assessed. The intraoperative anteroposterior position change was -1.7 ± 3.4mm (a positive value indicates tibial posterior shift). Flexion angle improvement was negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.17, p < 0.005). Postoperative maximum flexion angles were also negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.09, p < 0.05). The postoperative amount of tibial internal rotation was positively correlated with the preoperative amount (R2 = 0.60, p < 0.0001); however, the intraoperative anteroposterior position change was not correlated with the postoperative amount of tibial internal rotation (n.s.). A navigation system may be able to indirectly evaluate PCL function and predict the postoperative flexion angles in cruciate-substituting TKA. Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting TKA. Level 3, retrospective comparative study.

Necessary Factors to Achieve Deep Flexion for Asian Populations after Oxford Unicompartmental Knee Arthroplasty.

There have been many reports on the clinical outcomes of Oxford unicompartmental knee arthroplasty (UKA); however, none have investigated the influence of flexion angle after UKA on clinical outcomes. The objective of this study was to clarify the relationship between outcomes and the postoperative maximum flexion angle and reveal the necessary factors for maximum flexion angle ≥ 140 degrees which is considered necessary for Asian populations. We categorized 212 UKA patients into the following three groups based on the postoperative maximum flexion angle: group 1 had flexion angle ≥ 140 degrees in 80 patients (38%), group 2 had 130 degrees ≤ flexion angle < 140 degrees in 80 patients (38%), and group 3 had flexion angle < 130 degrees in 52 patients (24%). Furthermore, we compared the postoperative clinical outcomes between the three groups and conducted multivariable regression analyses to assess parameters affecting the flexion angle. Postoperative Knee Society function scores for group 1 was significantly higher than for group 3. Group 1 had higher mean knee injury and osteoarthritis outcome scores (KOOS) in all subscales and significantly higher KOOS scores in the sports and quality of life subscales compared with group 2 and in all subscales compared with group 3. Multivariable logistic regression showed that preoperative flexion angle and tibial component posterior slope were associated with maximum flexion angle ≥ 140 degrees. Maximum flexion angle ≥ 140 degrees after Oxford UKA improved the clinical results, particularly for patient-reported outcomes. Furthermore, the tibial posterior slope was an important factor in achieving maximum flexion angle ≥ 140 degrees in UKA patients.

Influence of Posterior Tibial Slope on Kinematics After Cruciate-Retaining Total Knee Arthroplasty

BackgroundThe purpose of this study was to investigate the influence of posterior tibial slope (PTS) on knee kinematics after cruciate-retaining total knee arthroplasty (CR-TKA). These influences were evaluated using a prosthesis designed with high geometric conformity to the medial articular surface under the weight-bearing condition of deep knee bending. MethodsWe evaluated 71 knees (52 patients) after CR-TKA using 2- to 3-dimensional registration techniques. All patients were categorized into 2 groups: group A (PTS ≤ 7°) and group B (PTS ≥ 8°). We compared in vivo knee kinematics during deep knee bending under weight-bearing conditions between the 2 groups. The anteroposterior position of the nearest points, flexion angles, and external rotation angles of the femoral components relative to the tibial components were evaluated. Additionally, the knee flexion angles of the femur relative to the tibia obtained from the installation angles of the components were evaluated. ResultsPTS did not affect the external rotation angles and anteroposterior position. The postoperative maximum flexion angle and range of motion between the femur and tibia in group B were significantly greater than those in group A. ConclusionPTS of 8° or more in CR-TKA using prosthetics designed with high geometric conformity to the medial articular surface did not affect the anteroposterior position and external rotation, but increased the postoperative maximum flexion angle and range of motion.

Mid-term outcomes and complications of total knee arthroplasty in haemophilic arthropathy: A review of consecutive 131 knees between 2006 and 2015 in a single institute.

Although total knee arthroplasty (TKA) in haemophilic arthropathy can reduce severe joint pain and improve functional disability, it is technically demanding. To evaluate mid-term outcomes and complications of TKA in haemophilic arthropathy. This study retrospectively reviewed 131 consecutive primary TKAs in a single institute. The mean age was 41.0years old, and the mean follow-up period was 6.8years. Clinical and radiographic results were evaluated. Complications were categorized according to the classification system of the Knee Society for TKA complications. The average Western Ontario and McMaster Universities Arthritis Index (WOMAC) score improved from 66.0 to 24.2. The average flexion contracture significantly decreased from 17.3° to 4.7°, but the average pre- and postoperative maximum flexion did not differ (80.9° vs 85.6°, respectively). The average mechanical axis was varus 5.2° preoperatively and valgus 0.3° postoperatively. The coronal positions of the femoral and tibial components and the sagittal positions of these components were within ±3° in 83.2%, 89.3%, 63.4% and 73.3% of cases, respectively. Complications occurred in 17 knees (13.0%): hemarthrosis (n=7), medial collateral ligament injury (n=1), stiffness (n=2), deep periprosthetic joint infection (PJI) (n=3) and periprosthetic fracture (n=4). The mid-term results of TKA in haemophilic arthropathy were satisfactory in pain relief, improved function and decreased flexion contracture. Bleeding and PJI continue to be major concerns for TKA in haemophilic arthropathy, and risk of periprosthetic fracture must be taken into account for patient education and appropriate prevention.

No influence of obesity on survival of cementless, posterior-stabilised, rotating-platform implants.

This study compares survival and outcomes in four total knee arthroplasty (TKA) populations defined by baseline body mass index (BMI). We hypothesised that there would be no difference in survival between the groups. Using an initial cohort of 1059 TKAs, BMI was systematically measured prior to surgery. A retrospective study was conducted and patients were accordingly allocated to four groups: normal or underweight (BMI<25; n=111), overweight (25≤BMI<30; n=417), moderately obese (30≤BMI<35; n=330) and severely or morbidly obese (BMI≥35; n=201). The pre- and postoperative clinical and radiographical profiles of the four groups were compared, along with any postoperative complications and the survival of each group. The minimum follow-up was 24months. All implants had an ultra-congruent cementless posterior-stabilised rotating-platform design (Amplitude®). The primary endpoint was implant survival using Kaplan-Meier analysis. Statistical analysis was conducted using Chi-squared and Kruskal-Wallis H tests to compare the data with p<0.05. A total of 94 knees from normal weight or underweight individuals were analysed, 346 from overweight, 281 from moderately obese and 159 from severely or morbidly obese. All knees had been operated on between 2002 and 2011 with an average follow-up of 61.7 (12-146)months. A greater degree of obesity was significantly correlated with young age at intervention (p<0.001), as well as with a low average preoperative maximum flexion angle (p<0.001) and KSS (p<0.001). Postoperatively, there were no significant differences between the groups in terms of patient satisfaction (p=0.9) or mechanical axial deviation evaluated with whole-leg standing radiography (mFTA, p=0.3; mFA, p=0.1; mTA, p=0.3). The greater the degree of obesity, the lower the average postoperative maximum flexion angle (p<0.001), KSS knee score (p<0.001) and function score (p=0.005). There was no significant difference between the groups in terms of total rate of postoperative complications (p=0.9) or implant revision (p=0.9), or in terms of 10-year implant survival (p=0.4). Obesity does not affect mid-term implant survival, irrespective of BMI, but has a negative influence on functional outcomes and potential risk of postoperative complications.

Tibiofemoral rotational alignment affects flexion angles in navigated posterior-stabilized total knee arthroplasty

To investigate the tibiofemoral rotational profiles during navigated posterior-stabilized (PS) total knee arthroplasty (TKA) and investigate the effect on post-operative maximum flexion angles. Twenty-five subjects, treated with navigated PS TKA, were enrolled, and the effect of posterior cruciate ligament (PCL) resection and component implantation on tibiofemoral rotational kinematics was statistically evaluated. Then, the effect of rotational alignment changes on the post-operative maximum angles was retrospectively examined in 96 subjects using the multiple regression analysis. Tibial internal rotation was significantly increased in full extension (p<0.01 and <0.001, respectively) and at 60° and 90° flexion (p<0.05) after PCL resection, which further increased after implantation, compared with that before resection. The amount of tibial internal rotation from 90° flexion to maximum flexion was significantly decreased after PCL resection and implantation, compared with that before resection (p<0.05). The internal changes in the rotational alignment were independent factors for the minimal improvement in the post-operative maximum flexion angles (R 2=0.078, p=0.0067). PCL resection changed the tibial rotational alignment and decreased the amount of tibial internal rotation. The implantation of PS components further increased the internal rotational alignment and could not compensate for the tibiofemoral rotation. Finally, the internal changes in rotational alignment affected the improvement of the maximum flexion angles, suggesting that rotational alignment is an important factor for improving post-operative maximum flexion angles. II.

Navigation-based tibial rotation at 90° of flexion is associated with better range of motion in navigated total knee arthroplasty.

In clinical practice, people with better femorotibial rotation in the flexed position often achieve a favourable postoperative maximum flexion angle (MFA). However, no objective data have been reported to support this clinical observation. In the present study, we aimed to investigate the correlation between the amount of intraoperative rotation and the pre- and postoperative flexion angles. Fifty-five patients with varus osteoarthritis undergoing computer-assisted posterior-stabilized total knee arthroplasty (TKA) were enrolled. After registration, rotational stress was applied towards the knee joint, and the rotational angles were recorded by using a navigation system at maximum extension and 90° of flexion. After implantation, rotational stress was applied for a second time, and the angles were recorded once more. The MFA was measured before surgery and 1month after surgery, and the correlation between the amount of femorotibial rotation during surgery and the MFA was statistically evaluated. Although the amount of tibial rotation at maximum extension was not correlated with the MFA, the amount of tibial rotation at 90° of flexion after registration was positively correlated with the pre- and postoperative MFA (both p<0.005). However, no significant relationship was observed between the amount of tibial rotation after implantation and the postoperative MFA (n.s.). The results showed that better femorotibial rotation at 90° of flexion is associated with a favourable postoperative MFA, suggesting that the flexibility of the surrounding soft tissues is an important factor for obtaining a better MFA, which has important clinical relevance. Hence, further evaluation of navigation-based kinematics during TKA may provide useful information on MFA. Diagnostic studies, development of diagnostic criteria in a consecutive series of patients, and a universally applied "gold" standard, Level II.

Functional Outcomes of a New Mobile-Bearing Ultra-Congruent TKA System: Comparison With the Posterior Stabilized System

We determined whether a new mobile-bearing ultra-congruent (UC) TKA system provides better functional outcomes than an established posterior-stabilized (PS) prosthesis. The functional outcomes (motion arc, AKS scores, WOMAC Index, and SForm-36 scores evaluated at 1 and 2years postoperatively), satisfaction and incidences of adverse events were compared between the knees implanted with mobile-bearing UC prosthesis (n=103) and the mobile-bearing PS prosthesis (n=99). At 2years, mobile-bearing UC TKAs showed similar functional outcomes and satisfaction, but smaller motion arc compared to mobile-bearing PS TKAs (126° vs. 131°). There were no differences in the incidence of adverse events. Mobile-bearing UC prosthesis can be considered a safe and viable alternative to the PS design, with an expectation of smaller postoperative maximum flexion.

Factors affecting intraoperative kinematic patterns and flexion angles in navigated total knee arthroplasty.

To investigate the factors affecting intraoperative kinematics, as measured with a navigation system, and their effect on maximum flexion angles during total knee arthroplasty (TKA). One hundred posterior stabilised (PS) TKAs performed using an image-free navigation system were evaluated. Tibial internal rotation angles at maximum extension, 30°, 45°, 60°, 90°, and maximum flexion were collected at registration and after implantation. The varus angles from the coronal mechanical axis were also collected. The rotational patterns were divided into four groups to investigate whether flexion contracture and varus deformity affected the kinematic patterns, and correlated with the maximum pre- and post-operative flexion angles. At registration, the flexion angles at maximum extension differed significantly between the kinematic groups; the flexion angle at maximum extension at registration was negatively correlated with the pre-operative maximum flexion angle (R(2) = 0.226, p < 0.0001) and the post-operative maximum flexion angle (R(2) = 0.059, p = 0.0167). Varus deformity at registration also differed significantly between the kinematic groups; varus deformity at registration was negatively correlated with the pre-operative maximum flexion angle (R(2) = 0.087, p = 0.0036) and post-operative maximum flexion angle (R(2) = 0.101, p = 0.0027). Navigation-based measurements in patients undergoing PS TKA indicated that pre-operative flexion contracture and varus deformity are negatively correlated with both pre- and post-operative maximum flexion angles. The results may improve the ease with which surgeons can interpret intraoperative kinematics, by providing a multi-dimensional perspective. With further knowledge regarding intraoperative kinematics, it might be possible to improve surgical approach, prosthesis design, and clinical outcomes. II.

Navigation-based femorotibial rotation pattern correlated with flexion angle after total knee arthroplasty.

To investigate whether intraoperative kinematics obtained by navigation systems can be divided into several kinematic patterns and to assess the correlation between the intraoperative kinematics with maximum flexion angles before and after total knee arthroplasty (TKA). Fifty-four posterior-stabilised (PS) TKA implanted using an image-free navigation system were evaluated. At registration and after implantation, tibial internal rotation angles at maximum extension, 30°, 45°, 60°, 90°, and maximum flexion were collected. The rotational patterns were divided into four groups and were examined the correlation with maximum flexion before and after operation. Tibial internal rotation from 90° of flexion to maximum flexion at registration was correlated with maximum flexion angles pre- and postoperatively. The four groups showed statistically different kinematic patterns. The group with tibial external rotation up to 90° of flexion, following tibial internal rotation at registration, achieved better flexion angles, compared to those of another groups (126.7° ± 12.0°, p < 0.05). The group with tibial external rotation showed the worst flexion angles (80.0° ± 40.4°, p < 0.05). Furthermore, the group with limited extension showed worse flexion angles (111.6° ± 8.9°, p < 0.05). Navigation-based kinematic patterns found at registration predict postoperative maximum flexion angle in PS TKA. Navigation-based kinematics can be useful information during TKA surgery. Diagnostic studies, development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Clinical Results of Posterior Cruciate Ligament–Retaining Total Knee Arthroplasty in Patients with Rheumatoid Arthritis: A 5- to 13-Year Follow-up Study

Aim: Total knee arthroplasty (TKA) is commonly performed to relieve pain and improve function in patients with rheumatoid arthritis (RA). However, treatment with posterior cruciate ligament–retaining (CR-type) TKA is thought to be controversial, particularly in patients with RA. In the present study, we aimed to investigate the clinical results of CR-type TKA and evaluate the efficacy of this type of prosthesis in patients with RA. Methods: In our hospital, 77 CR-type TKA procedures were performed in 59 patients with RA between January 2001 and 2008. In total, we assessed 45 CR-type TKA procedures in 30 patients with RA who underwent follow-up for at least 5 years. The assessment was based on the Knee Society clinical score (KSS) and an independent radiographic analysis. Results: During a mean follow-up period of 8 years, 2 patients developed late infection and 2 other patients experienced supracondylar fracture after each TKA procedure. After surgery, the KSS improved significantly among the patients and 87% of the patients did not experience any pain. Moreover, the mean postoperative maximum flexion angle was 114.8°, whereas the maximum extension angle was -4.2°. Conclusion: Although additional long-term follow-up studies are required, the results of our medium-term followup study indicate that CR-type TKA was not problematic, even in patients with RA.

Restoring the anatomical tibial slope and limb axis may maximise post-operative flexion in posterior-stabilised total knee replacements

The optimal management of the tibial slope in achieving a high flexion angle in posterior-stabilised (PS) total knee replacement (TKR) is not well understood, and most studies evaluating the posterior tibial slope have been conducted on cruciate-retaining TKRs. We analysed pre- and post-operative tibial slope differences, pre- and post-operative coronal knee alignment and post-operative maximum flexion angle in 167 patients undergoing 209 TKRs. The mean pre-operative posterior tibial slope was 8.6° (1.3° to 17°) and post-operatively it was 8.0° (0.1° to 16.7°). Multiple linear regression analysis showed that the absolute difference between pre- and post-operative tibial slope (p < 0.001), post-operative coronal alignment (p = 0.02) and pre-operative range of movement (p < 0.001) predicted post-operative flexion. The variance of change in tibial slope became larger as the post-operative maximum flexion angle decreased. The odds ratio of having a post-operative flexion angle < 100° was 17.6 if the slope change was > 2°. Our data suggest that recreation of the anatomical tibial slope appears to improve maximum flexion after posterior-stabilised TKR, provided coronal alignment has been restored.

Clinical results of Hi-tech Knee II total knee arthroplasty in patients with rheumatoid athritis: 5- to 12-year follow-up

BackgroundTotal knee arthroplasty (TKA) is a common form of treatment to relieve pain and improve function in cases of rheumatoid arthritis (RA). Good clinical outcomes have been reported with a variety of TKA prostheses. The cementless Hi-Tech Knee II cruciate-retaining (CR)-type prosthesis, which has 6 fins at the anterior of the femoral component, posterior cruciate ligament (PCL) retention, flat-on-flat surface component geometry, all-polyethylene patella, strong initial fixation by the center screw of the tibial base plate, 10 layers of titanium alloy fiber mesh, and direct compression molded ultra high molecular weight polyethylene (UHMWPE), is appropriate for TKA in the Japanese knee.The present study was performed to evaluate the clinical results of primary TKA in RA using the cementless Hi-Tech Knee II CR-type prosthesis.Materials and methodsWe performed 32 consecutive primary TKAs using cementless Hi-Tech Knee II CR-type prosthesis in 31 RA patients. The average follow-up period was 8 years 3 months. Clinical evaluations were performed according to the American Knee Society (KS) system, knee score, function score, radiographic evaluation, and complications.ResultsThe mean postoperative maximum flexion angle was 115.6°, and the KS knee score and function score improved to 88 and 70 after surgery, respectively. Complications, such as infection, occurred in 1 patient and revision surgery was performed. There were no cases of loosening in this cohort, and prosthesis survival rate was 96.9% at 12 years postoperatively.ConclusionThese results suggest that TKA using the cementless Hi-Tech Knee II CR-type prosthesis is a very effective form of treatment in RA patients at 5 to 12 years postoperatively. Further long-term follow-up studies are required to determine the ultimate utility of this type of prosthesis.

High-flexion total knee arthroplasty improves flexion of stiff knees

High-flexion knee prosthesis designs are generally thought to be of benefit only in patients with a satisfactory preoperative flexion angle. The aim of the study was to evaluate whether high-flexion designs were indeed worthless in osteoarthritis patients with severe preoperative flexion limitation. The postoperative maximum flexion was compared in osteoarthritis patients with a preoperative maximum flexion of 100° or less, using LPS and LPS-flex implants (NexGen®; Zimmer, Warsaw, IN) in total knee arthroplasties. Data on 39 knees in the LPS group and 41 in the LPS-flex group, with a minimum of 2 years of follow-up, were reviewed retrospectively, focused on the postoperative maximum flexion. Two years after operation, the LPS-flex group had a mean postoperative maximum flexion of 131±10° (range, 105-140°), which was significantly higher than the 121±12° (range, 95-140°) in the LPS group (P<0.001). In the LPS-flex group, about half of the knees (n=18, 44%) could achieve a maximum flexion of 140° postoperatively, but in the LPS group only five knees (13%) achieved a maximum flexion of 140°. Despite a different period of the operation between groups, this study suggested that osteoarthritis patients with severe preoperative flexion limitation could achieve more postoperative gain in flexion when a high-flexion prosthesis was used, compared to the flexion obtained using a standard prosthesis.

Correlation of maximum flexion with clinical outcome after total knee replacement in Asian patients

This study aimed to determine the correlation between the amount of maximum flexion and the clinical outcome in 207 Koreans (333 knees) undergoing total knee replacement. The association of maximum flexion with clinical outcome was evaluated one year postoperatively using three scoring systems; the American Knee Society score, Western Ontario McMaster Universities Osteoarthritis index and the Short Form-36. The mean maximum flexion decreased post-operatively at 12 months from 140.1 degrees (60 degrees to 160 degrees ) to 133.0 degrees (105 degrees to 150 degrees ). Only the social function score of the Short Form-36 correlated significantly with maximum flexion (correlation coefficient = 0.180, p = 0.039). In comparative analyses of subgroups divided by a maximum flexion of 120 degrees , we found no significant differences in any parameters except the social function score of the Short Form-36 (41.9 vs 47.3, p = 0.031). Knees with a maximum flexion of more than 135 degrees had a better functional Western Ontario McMasters Universities Osteoarthritis index score than knees with maximum flexion of 135 degrees or less (17.5 vs 14.3, p = 0.031). We found only weak correlation between the postoperative maximum flexion and the clinical parameters for pain relief, function and quality of life, even in Korean patients. Efforts to increase post-operative maximum flexion should be exercised with caution until concerns relating to high-flexion activities are sufficiently resolved.