Partial restoration of knee kinematics in severe valgus deformity using the medial-pivot total knee arthroplasty

Medially congruent total knee arthroplasty in valgus knee deformities yields satisfactory outcomes: a multicenter, international study

PURPOSE

Postoperative instability represents one of the most common complications following primary total knee arthroplasty (TKA). To prevent this outcome, valgus deformities have been historically treated using more constrained implants. The purpose of this study was to evaluate the outcome of treating a moderate valgus deformity by combining a surgical technique used to release the postero-lateral soft tissue envelope with the use of a medially congruent (MC) TKA design without using classical, semi-constrained inserts.

METHODS

Seventy-nine MC TKAs were performed by three surgeons at three institutions between 2016 and 2018 as part of a multicenter, international study. Inclusion criteria were: radiographic late-stage osteoarthritic knees with Ranawat's type 1 or 2 classification of valgus deformity and integrity of the medial capsular-ligament complex (less than 10 mm of medial opening during valgus stress test at 10° of knee flexion). Exclusion criteria were: BMI > 40; neuromuscular, metabolic, or immunologic disorders; or the inability to complete outcome measures or radiographic assessment.

RESULTS

Seventy-seven patients (79 knees), 59 males and 18 females, were evaluated at 2-year minimum follow-up according to the Knee Society Score (KSS) and Forgotten Joint Score (FJS). Mean age at surgery was 70 years (range 48-91). The mean range of motion (ROM) improved from 110° (range 85°-130°) preoperatively to 121° (range 105°-135°) (p < 0.001) at the time of the last follow-up. Preoperative knee extension significantly improved from 3° (range - 15° to 20°) to 1° (range - 5° to 5°) of flexion at the last follow-up in all the patients. KSS and KSS Functional scores were 89 (range 65-100) and 82 points (range 55-100), respectively. The FJS obtained at the last follow-up was 72 (range 49-88). Two patients (2.5%) had major postoperative complications (one periprosthetic joint infection; one postoperative patellar fracture) requiring surgical interventions.

CONCLUSIONS

In different surgeon's hands, the use of a modern medially congruent TKA design yielded good clinical outcomes at 2 years in a consecutive series of TKA in valgus arthritic knees. Postoperative instability was not recorded in this series and this finding was related to the high conformity design of the MC polyethylene insert, which significantly differs from classical posterior-stabilized (PS) designs.

LEVEL OF EVIDENCE

IV.

Intraoperative femoral rotational kinematics are similar in varus and valgus knees during medial pivot total knee arthroplasty

BACKGROUND

Medial-pivot type total knee arthroplasty is designed to reproduce physiological femoral rotational kinematics during knee flexion; however, its rotational kinematics in valgus knees remain unknown. This study's hypothesis is that its kinematics show the similar medial pivot motion in valgus knees as in varus knees.

METHODS

This retrospective study included 50 cases of primary medial-pivot type total knee arthroplasty performed with navigation for knee osteoarthritis. Cases were grouped as valgus (n = 20) or varus (n = 30). In valgus knees, surgeons used preoperative manual testing to confirm that alignment was correctable. They evaluated femoral rotational kinematics at maximum extension, 30°, 60°, 90°, and maximum flexion, using a navigation system, both before and after implantation. Finally, intraoperative rotational kinematics, postoperative patient-reported outcomes, and knee range of motion were compared between the two groups.

FINDINGS

Before implantation, both valgus and varus knees displayed external femoral rotation relative to the tibia during knee flexion. The rotation magnitude was significantly larger in varus knees at 60°, 90°, and maximum flexion angles compared to valgus knees (P < 0.05). In contrast, after implantation, both groups displayed external femoral rotation of 12-13° during knee flexion with no significant differences between the two groups at any knee flexion angle tested (P > 0.05). Short-term clinical outcomes were comparable between valgus and varus knees.

INTERPRETATION

Postoperatively, medial-pivot type total knee arthroplasty for knee osteoarthritis resulted in external femoral rotation during knee flexion. Notably, this occurred even in valgus knees with good short-term clinical outcomes.

No difference in 13-year survival after medial pivot or central pivot mobile bearing total knee arthroplasty. A propensity matched comparative analysis

PURPOSE

The present study was designed to evaluate the long-term results (more than 10 years) of mobile bearing total knee arthroplasty (TKA) and to compare the survival of medial pivot axis (MPA) and central pivot axis (CPA) TKAs. The primary hypothesis was that the 10- to 15-year survival rate of MPA TKAs will be better than CPA TKAs.

METHODS

A national, multicenter, retrospective study was performed in France. In this case-control design, 1154 TKAs were paired into the CPA group (control group: 577 cases) and MPA group (study group: 577 cases) based on a logistic regression analysis of age, gender, body mass index and severity of the coronal deformity, defining the propensity score for each case. Final survival information follow-up was obtained for 946 cases (82%).

RESULTS

There was no significant difference between the control and study groups for any baseline data. Twenty-two prosthetic revisions (2%) were performed for mechanical reasons during the follow-up period. There was no significant difference between the 13-year survival rates of CPA (98%) and MPA (97%) TKAs. There was no significant difference between groups in their final Oxford and Knee Society scores.

CONCLUSION

Our findings do not support the assumption that medialization of the pivot axis of a mobile bearing TKA improves clinical results or survival.

LEVEL OF EVIDENCE

Level III.

Mid-term clinical outcomes and survivorship of medial-pivot total knee arthroplasty-a mean five year follow-up based on one thousand, one hundred and twenty eight cases

PURPOSE

The unique medial-pivot (MP) design of ADVANCE® system largely simulates the movement of a normal knee joint and a high mid- and long-term success rate has been reported in limited populations. The aims of this study are to investigate the mid-term clinical outcomes and survivorship based on a large cohort with 1128 cases.

METHODS

One thousand seven patients received 1276 ADVANCE® MP TKAs from January 2011 to April 2016 in our institution were retrospectively investigated. The range of motion (ROM), the Knee Society Score (KSS), the Knee Society Function Score (KSFS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and the Forgotten Joint Score (FJS) were used to evaluate clinical outcomes and Kaplan-Meier survival curve was used to calculate the survivorship.

RESULTS

In an averaged five year follow-up, the results of 879 patients (1128 knees) were successfully obtained and the clinical outcomes of 1107 knees were recorded. One hundred forty-eight knees (11.6%) were lost to follow-up. Excellent mid-term ROM, KSS, KSFS, and WOMAC score were recorded. A total of 53 complications were identified and most complications were related to the discordance of femoropatellar joint. Taking revision for any reason as end point, the overall survivorship was 99.2% at seven years. When taking all cases lost to follow-up as failures, the survivorship was 83.8% at five years and 50.6% at seven years.

CONCLUSION

For MP designs, the intermediate clinical outcomes are good to excellent and the mid-term survivorship related to reasons other than infection is also satisfactory.

Comparison of clinical and radiographic results between total knee arthroplasties using medial pivot and posterior-stabilized prosthesis: A meta-analysis

OBJECTIVE

To evaluate the clinical and radiographic outcomes of total knee arthroplasties (TKA) between using medial-pivot (MP) and posterior-stabilized (PS) prosthesis. Does MP prosthesis and PS prosthesis influence the clinical results of a TKA?

METHODS

An electronic literature search of PubMed Medline and the Cochrane Library was performed from inception to October 1, 2019. A meta-analysis to compare postoperative outcomes of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Score (KSS), range of motion (ROM), complications, and radiographic results between MP and PS prosthesis were conducted.

RESULTS

Seven eligible studies involving 934 adult patients (MP group, n = 461; PS group, n = 473) were identified for analysis. This study showed no significant difference between the 2 groups in the WOMAC scores, KSS, ROM, and complications (P > .05). The differences of the femorotibial angle, position of implant, and patellar tilt were also not significant between the 2 groups (P > .05).

CONCLUSION

The present meta-analysis has shown that patients with the MP prosthesis have similar clinical results as patients with PS prosthesis. Furthermore, the radiographic results, especially patella tilt angle, were also similar between the 2 groups. Therefore, surgeons should be aware that the types of prostheses are not a decisive factor to ensure successful operation.

Rotational kinematics differ between mild and severe valgus knees in total knee arthroplasty

BACKGROUND

There is no consensus regarding femorotibial rotational kinematics in total knee arthroplasty (TKA) for valgus knee deformity. Additionally, whether the degree of valgus deformity influences intraoperative rotational kinematics and postoperative clinical scores remains unclear. The objectives of this study were to investigate whether the valgus angle is associated with intraoperative rotational kinematics in TKA for valgus knee deformity and to examine the relationship between rotational kinematics and postoperative clinical results.

MATERIALS AND METHODS

A total of 24 knees with valgus deformity for TKA were included in this study and were divided into two groups depending on the femorotibial angle (FTA); there were 11 knees in the severe valgus group (FTA < 160°) and 13 knees in the mild valgus group (FTA ≥ 160°). Intraoperative femorotibial rotational kinematics from knee extension to flexion were evaluated using an image-free navigation system and postoperative clinical results (range of motion and subjective outcomes) were evaluated 1 year postoperatively. All parameters were compared between the two groups.

RESULT

Mild valgus knee showed tibial internal rotation during knee flexion before implantation, whereas severe valgus knee showed tibial external rotation during knee flexion before implantation. The postoperative flexion angle was positively correlated with the tibial internal rotation angle after implantation in the mild valgus group only.

CONCLUSION

Intraoperative rotational kinematics before implantation differed between mild and severe valgus knee deformity in TKA. Intraoperative tibial rotation influenced the postoperative knee flexion angle in mild, but not severe, valgus knee deformity. Ideal postoperative rotational kinematics may be different between the two groups and the difference may be taken into consideration in implant selections and surgical techniques.

The effect of knee prosthesis design on tibiofemoral biomechanics during extension tasks following total knee arthroplasty

BACKGROUND

Determine whether the tibiofemoral motion and electromyographic activity of the knee differs in patients with a medial pivot implant, compared to those with cruciate-retaining and posterior-stabilised designs, during knee extension after Total Knee Arthroplasty (TKA).

METHODS

An observational study was conducted on a cohort of patients that had undergone TKA for a minimum of 12 months prior. Three matched groups (n = 18) were categorised based on implant type: medial-pivot (MP), posterior-stabilised (PS) and cruciate-retaining (CR). Kinematics, with motion analysis (Vicon, USA) and surface electromyography (Delsys, USA) were assessed during step-ascent and walking tasks.

RESULTS

All groups displayed a similar amount of knee extension in both tasks. They also paradoxically produced an average mean internal rotation movement during knee extension in both the step-ascent and walking tasks. The only significant difference was found in the step-ascent task, in which the MP group produced a larger absolute amount of rotation than the CR implant group (P = 0.007), but neither group differed from the PS implant group. The groups did not differ in rotation during the walking task (P > 0.05). The MP group displayed significantly (P < 0.01) greater knee extensor activation during the step-ascent than the PS group.

CONCLUSION

The MP design was only significantly different to another implant design for the step-ascent task. Patients with either knee implant types were not strictly limited to producing the traditional "screw-home" mechanism, defined by external rotation during extension. Furthermore, comparison with the non-implant contralateral limb suggested that rotation is not necessarily dictated by implant design.

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

PURPOSE

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.

METHODS

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 1 month after surgery, and the correlation between the amount of femorotibial rotation during surgery and the MFA was statistically evaluated.

RESULTS

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.).

CONCLUSION

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.

LEVEL OF EVIDENCE

Diagnostic studies, development of diagnostic criteria in a consecutive series of patients, and a universally applied "gold" standard, Level II.

Medial pivot knee in primary total knee arthroplasty

Total knee arthroplasty (TKA) with a medial pivot design was developed in order to mimic normal knee kinematics; the highly congruent medial compartment implant should improve clinical results and decrease contact stresses. Clinical and radiographic mid-term outcomes are satisfactory, but we need other studies to evaluate long-term results and indications for unusual cases.

Dynamic hip kinematics in patients with hip osteoarthritis during weight-bearing activities

BACKGROUND

There is an interest in quantifying the hip kinematics of patients with end-stage hip disorders before total hip arthroplasty. The purpose of the present study was to obtain dynamic hip kinematics under four different conditions, including deep flexion and rotation, in patients with osteoarthritis of the hip.

METHODS

Continuous X-ray images were obtained in 14 patients during gait, chair-rising, squatting, and twisting, using a flat panel X-ray detector. These patients received computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial X-ray images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the pelvis and femur during the movement cycle of each activity.

FINDINGS

For gait, chair-rising, and squatting, the maximum hip flexion angles averaged 22°, 64°, and 68°, respectively. The pelvis was tilted anteriorly by an average of around 7° during the full gait cycle. For chair-rising and squatting, the maximum absolute values of anterior/posterior pelvic tilt averaged 8°/17° and 6°/18°, respectively. Hip flexion showed maximum flexion angle on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute values of internal/external hip rotation averaged 3°/13°.

INTERPRETATION

Patients with hip osteoarthritis prior to total hip arthroplasty demonstrated the limited ranges of coordinated motion of the pelvis, femur, and hip joint during each activity, especially in deeply flexed and rotated postures.

Comparison of Midterm Clinical and Radiographic Results Between Total Knee Arthroplasties Using Medial Pivot and Posterior-Stabilized Prosthesis-A Matched Pair Analysis

BACKGROUND

Despite the theoretical advantage of a knee design that can more reliably replicate the medial pivot (MP) of the natural knee, only a few clinical studies have compared the clinical results between the MP prosthesis and another design of prosthesis. We compared the midterm results of total knee arthroplasty (TKA) using an MP prosthesis vs a posterior-stabilized prosthesis via a matched-pair analysis; we included results related to patellofemoral joint symptoms.

METHODS

The midterm clinical and radiographic results of 125 consecutive patients (150 knees) who underwent a TKA with the ADVANCE MP prosthesis were compared with those of a control group who had undergone a primary TKA with a posterior-stabilized prosthesis.

RESULTS

Values of the Knee Society's Knee Scoring System, Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala and Feller scoring systems, as well as the range of motion after TKA, did not significantly differ between the 2 groups. No differences in femorotibial angle and component position, including the patella component, were observed between the 2 groups. No significant differences in the change of patella tilt angle and the postoperative patellar translation were observed between the 2 groups.

CONCLUSION

Patients with the MP prosthesis experienced satisfactory pain relief and a functional recovery, providing results similar to those of the posterior-stabilized prosthesis, including the resolution of patellofemoral joint symptoms.

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

PURPOSE

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).

METHOD

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.

RESULTS

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).

CONCLUSION

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.

LEVEL OF EVIDENCE

II.

[Total knee arthroplasty in 2014 : Results, expectations, and complications]

BACKGROUND

Aseptic loosening seems to have become a minor problem in total knee arthroplasty. In contrast to that, new challenges are defined by changing patients' expectations. Beside reduction of pain and improving mobility, modern implants should not be noticed as such and should not limit sports activities.

OBJECTIVES

In this paper, a summary of the development and the current situation of total knee arthroplasty (e.g., implantation numbers, hospitality, operation time, and infection rates) are provided. The data are compared in an international context. In addition, current trends and developments from recent years are shown and rated according to the literature.

MATERIALS AND METHODS

The paper is based on a literature search (PubMed) and analyses of published official statistical data and expert recommendations.

RESULTS

Implantation numbers have been declining gradually in Germany since 2009. In 2013, 127,077 total knee arthroplasties were implanted. In contrast, the number of revision operations has increased gradually during the last decade. In addition, hospital stay and operation time have declined.

CONCLUSION

The development of implants, instruments, and operation techniques results from changing patients' expectations. All innovations must be compared against the results of well-proven techniques. The arthroplasty register may be an instrument to evaluate the results of new techniques and implants in a broad clinical application in terms of survival.