Postoperative Flexion Angle Research Articles

Lateral Laxity in Flexion Increases the Postoperative Flexion Angle in Cruciate-Retaining Total Knee Arthroplasty

Thirty-eight patients diagnosed with osteoarthritis underwent 41 cruciate-retaining total knee arthroplasties. In varus and valgus tests at flexion, subjects were seated on a table at 80° of knee flexion; 50 N was applied perpendicular to the lower leg. The factors affecting the postoperative flexion angle were investigated in a multiregression analysis. The mean joint angles of the flexion-valgus and flexion-varus tests were 3.4° ± 1.4° and 6.2° ± 2.5°, respectively. The flexion-varus angle was correlated with the postoperative flexion angle ( P < .01). The mean postoperative flexion angles were 110.8° ± 9.6° and 118.1° ± 8.0° in the groups with the flexion-varus angle of 6° or less and more than 6°, respectively ( P = .02). Slack lateral laxity in flexion had a significant effect during knee flexion in cruciate-retaining total knee arthroplasty.

Influence of intra-operative joint gaps on post-operative flexion angle in posterior cruciate-retaining total knee arthroplasty

The purpose of this study is to examine the joint component gap and its relationship with post-operative flexion angles in posterior cruciate-retaining (CR) total knee arthroplasty (TKA). In posterior-stabilized (PS) TKA, an inverse correlation between the joint component gap and the post-operative flexion angle was reported. However, the kinematics of the joint component gap has a different pattern in PS and CR TKA. It was hypothesised that CR TKA has a different correlation between the joint component gap and the post-operative flexion angle compared to PS TKA. The joint component gap was measured with an offset-type tensor. The joint component gaps were measured at 0°, 10°, 30°, 60°, 90° and 120° knee flexion angle and various values of the change in the joint component gap were calculated; 10°-0°, 30°-0°, 60°-0°, 90°-0° and 120°-0°. Multivariate regression analysis was used to determine the influencing of these parameters to post-operative knee flexion angle. The post-operative flexion angle was positively correlated with a joint component gap of 90° and 120° and the values of the change in the joint component gap of 90°-0° and 120°-0°. Multivariate regression analysis demonstrated pre-operative knee flexion angle, and the values of the change in the joint component gap of 90°-0° had a significant independent factor of post-operative knee flexion angle. Post-operative flexion angle is multi-factorial. However, it is important to avoid flexion component gap tightness as well as excessive flexion component gap looseness for acquisition of better flexion angle in CR TKA. IV.

Effect of posterior design changes on postoperative flexion angle in cruciate retaining mobile-bearing total knee arthroplasty

The Dual Bearing Knee (DBK) prosthesis is a new concept which has a mobile-bearing insert. In May 2001, the posterior femoral condyle design of the DBK was changed to become smaller and there was a posterior shift in the base of the insert dish (Hi-Flex). Between 1998 and 2004, 371 DBKs (112 Hi-Flex and 220 Standard) were performed by one surgical team. There was a significant difference in postoperative flexion angle between the Hi-Flex and Standard DBKs (117.0° and 111.3°; p = 0.001). The delta flexion angle in the Hi-Flex (-2.4°) was significantly increased compared with that in the Standard DBK (-9.6°) (p = 0.001). In the Hi-Flex DBK, the postoperative flexion angle (5.7°) and the delta flexion angle (7.2°) were significantly larger than for the Standard DBK (p < 0.001). These results suggest that the flexion is greater for a design with smaller posterior condyle prosthesis and with a posterior shift in the base of the insert dish in CR mobile-bearing TKA.

Mobile-bearing prosthesis did not improve mid-term clinical results of total knee arthroplasty

A prospective study was performed to compare the clinical and radiological results of mobile- and fixed-bearing total knee arthroplasty with specific attention to rotational alignment and range of motion. Sixty-one knees were assigned to total knee arthroplasty with either the NexGen LPS Flex fixed-bearing or with the NexGen LPS Flex mobile-bearing prosthesis. Postoperatively, knees were compared with regard to range of motion, clinical score, and radiographic findings. Rotational alignment of the femoral and tibial components was evaluated by computed tomography. The median follow-up period was 5.9years (range 2.1-8.8years). Median postoperative Knee Society scores were 99 points (68-100) for the fixed-bearing group and 100 points (66-100) for the mobile-bearing group (n.s.). The median postoperative flexion angles of 120° (90°-150°) for the fixed-bearing group and 125° (90°-145°) for the mobile-bearing group were not significantly different from each other (n.s.). No knee required revision surgery due to wear of polyethylene or loosening of the component in either group. Computed tomography showed that 11 knees had rotational mismatches of more than 10° between the femoral and tibial components, but no significant difference was found in the postoperative extension and flexion angles or in the clinical score between the two treatment groups. Using the identical design for both fixed- and mobile-bearing prostheses, this prospective, randomized study did not show any clinical advantages of the mobile-bearing knee. Analysis of rotational alignment by CT scan did not reveal a particular advantage of the self-aligning mechanism of mobile-bearing implants.

Relationship between joint gap difference and range of motion in total knee arthroplasty: a prospective randomised study between different platforms

The objective of this study was to investigate the range of motion (ROM) of the knee before and four years after total knee arthroplasty (TKA) with a mobile or fixed type of platform and to prospectively evaluate whether there was a difference in ligament balance between the platform types. The subjects were 68 patients involving 76 joints. The mobile type was used in 31 joints and fixed type in 45 joints by employing a prospective randomised method. The passive maximum ROM was measured using a goniometer before and four years after surgery. Also, the intraoperative knee ligament balance was measured. The postoperative extension ROM was significantly improved after TKA using a mobile bearing type compared with that employing a fixed bearing type. In TKA using the former, the intraoperative gap difference was not related to the postoperative flexion angle of the knee. However, they were related in TKA using a fixed bearing type, with a positive correlation regarding the flexion gap.

Comparison of Posterior-Cruciate Retaining versus Substituting P.F.C. Total Knee Arthroplasty (A Randomized Study)

Purpose: To compare the functional results of posterior cruciate-retaining (PCR) and posterior sub- stituting (PS) replacement in patients undergoing primary total knee arthroplasty (TKA) for osteoarthritis. Materials and Methods: A randomized controlled study was carried out to compare the clinical and radiological outcomes of PCR and PS primary P.F.C. Ⓡ TKA. One hundred and sixty eight patients (188 cases), who had a primary diagnosis of osteoarthritis, and an intact functioning posterior cruciate ligament, were enrolled in this study. The patients were randomized regardless of the level of posterior cruciate ligament preservation. One hundred and eighty eight cases had a minimum 6-year follow-up, which included 96 and 92 cases in the PCR and PS groups, respectively. Results: The Knee Society Score, the Hospital for Special Surgery (HSS) knee rating scores, average flexion contracture and radiologic alignment improved significantly, but there were no significant difference between the two groups. On the other hand, the mean postoperative flexion angles in the PCR and PS knees increased from 114.7 o to 121.2 o and 119.3 o to 131.3 o , respectively (p<0.05). Conclusion: There were no significant differences between PCR and PS TKA in the follow-up knee scores. However, the level of postoperative improvement in further flexion was better in the PS group.

Influence of intra-operative joint gap on post-operative flexion angle in osteoarthritis patients undergoing posterior-stabilized total knee arthroplasty

Recently, we developed a new tensor for total knee arthroplasty (TKA) procedures enabling soft tissue balance assessment throughout the range of motion while reproducing post-operative joint alignment with the patello-femoral (PF) joint reduced and the tibiofemoral joint aligned. Using the tensor with a computer-assisted navigation system, we investigated the relationship between various intra-operative joint gap values and their post-operative flexion angles. An increased value during the extension to flexion gap and a decreased value during the flexion to deep flexion gap with PF joint reduced, not everted, showed an inverse correlation with post-operative knee flexion angle, not pre-operative flexion angle. In conclusion, understanding the characteristics of joint gap kinematics in posterior-stabilized TKA under physiological and reproducible joint conditions may enable the prediction of the post-operative flexion angle and help to determine the appropriate intra-operative joint gap.

New parameter of flexion after posterior stabilized total knee arthroplasty: posterior condylar offset ratio on X-ray photographs

In cruciate-retaining (CR) type TKA, the increase in posterior condylar offset (PCO) is considered to be correlated to flexion angle acquired postoperatively according to the article reported by Bellemans (J Bone Joint Surg Br 84:50-53, 2002). However, the significance of PCO seems to differ according to the size of joints. We therefore have defined a new parameter of posterior condylar offset ratio (PCOR) on the lateral view of plain X-ray photographs and studied the relationship between PCOR and postoperative flexion status in posterior-stabilized (PS) type TKA. Flexion status includes two parameters, such as postoperative flexion angle (FA) and flexion achievement rate (AR). The subjects of this study were 160 knees (16 males and 144 females, average 75 years.) with PS type TKA for osteoarthritic knees between 1999 and 2003 at our institution, more than at least 1 year postoperative follow-up. In the study of FA, patients with FA of less than 100 degrees were divided into Group L (n = 28), patients with FA of 130 degrees and greater were divided into Group H (n = 58). In the study of AR, patients with AR of less than 100% were divided into Group P (n = 46), patients with AR of 120% and greater were divided into Group G (n = 22). PCOR was statistically compared in each group, respectively. In FA, PCOR in Group L (0.385) was significantly lower (P = 0.027) than that in Group H (0.428). In AR, PCOR in Group P (0.376) was significantly lower (P = 0.0018) than that in Group G (0.456). We have concluded, though there are many factors influencing the range of movement after TKA, our newly defined PCOR could possibly serve as a parameter of postoperative flexion status of PS type TKA on plain X-ray photographs.

Influence of hip position on knee flexion angle in patients undergoing total knee arthroplasty

The influence of hip position on knee flexion angle before total knee arthroplasty (TKA) and that after TKA were investigated and compared. Sixty-six patients (70 knees) with osteoarthritis who were undergoing TKA were examined using lateral radiographs of maximum knee flexion angle with the hip joint at 0° extension and 90° flexion. The postoperative rate of decrease in knee flexion angle caused by hip extension was significantly larger compared with the value before surgery. The preoperative rate of decrease in knee flexion angle caused by hip extension showed strong inverse correlation with the preoperative and postoperative knee flexion angle ratio. In conclusion, tightness of the extensor mechanism is present in all knees undergoing TKA and especially has a strong influence on the postoperative flexion angle of the knee.

Measurements of acetabular cup position and pelvic spatial orientation after total hip arthroplasty using computed tomography/radiography matching

This study presents a clinical validation of postoperative measurements of acetabular cup alignment following total hip arthroplasty (THA). The methodology was based on concurrent anatomic three-dimensional (3D) measurements of both the acetabular cup alignment and pelvic orientation, using an original CT/X-ray matching algorithm named Xalign. The subjects were 19 patients who had undergone bilateral THA using CT-based surgical navigation. All patients had postoperative pelvic CT scans and multiple antero-posterior (AP) pelvic X-rays. Using a proprietary software algorithm, the X-rays included in the study were matched with the corresponding postoperative CT scans. The goal of this method was to allow 3D anatomic pelvic and acetabular measurements on two-dimensional AP X-rays. The postoperative cup abduction, version and pelvic flexion angles were determined in three different ways: using CT images directly, applying the Xalign method, and finally by performing conventional (abduction only) measurements on AP pelvic X-rays. The cup orientation measured on CT images was taken as the ground truth. The Xalign measurement errors were defined as the difference between the CT cup values and those obtained by applying the matching method. The mean cup abduction error was 0.85° ± 1.3° (± standard deviation) and the mean version error was 0.01° ± 1.99°. Conventionally measured cup abduction ranged from 44° to 62° and correlated significantly (p = 0.001, r = −0.5) with pelvic flexion angle, proving the linear negative correlation between pelvic flexion and the error in conventional radiographic cup measurements. The Xalign method offered reasonable accuracy for cup orientation, and allowed cup and pelvic 3D anatomic measurements at different times.

Soft-tissue tension total knee arthroplasty

It is far from clear how best to define the proper strength of soft-tissue tensioning in total knee arthroplasty (TKA). We attached a torque driver to the Monogram balancer/tensor device and measured soft-tissue tension in full extension and 90° flexion during TKA. In our surgical procedure, when we felt proper soft-tissue tension was being applied, the mean distraction force was noted to be 126N in extension and 121N in flexion. There was no significant correlation between soft-tissue tension and the postoperative flexion angle finally achieved. To the best of our knowledge, this is the first study to assess the actual distraction forces in relation to soft-tissue tension in TKA. Further study may reveal the most appropriate forces to achieve proper soft-tissue tension in the wide variety of circumstances presenting at knee arthroplasty.