Total knee arthroplasty designed to accommodate the presence or absence of the posterior cruciate ligament

Modern Total Knee Arthroplasty Bearing Designs and the Role of the Posterior Cruciate Ligament

The role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) surgery continues to be a source of debate among the adult reconstruction community. In native knee flexion, the PCL is comprised of an anterolateral and posteromedial bundle that work together to limit posterior tibial translation and allow adequate femoral rollback for deep flexion. In the arthritic knee, the PCL can often become dysfunctional and attenuated, which led to the development of posterior stabilized (PS) TKA bearing options. PS TKAs implement a cam-post construct to functionally replace a resected PCL. While PS designs may facilitate balancing knees with significant deformity, they are associated with complications such as postfracture, increased wear, and patellar clunk/crepitus. In recent years, newer designs have been popularized with greater degrees of congruency and incorporation of medial and lateral pivoting to better recreate native knee kinematics. The American Joint Registry has confirmed the recent predilection for ultra-congruent and cruciate-retaining TKA inserts over PS TKAs during the last decade. Studies have failed to identify an overall clinical superiority between the cruciate substituting and sacrificing designs. The literature has also failed to identify clinical consequences from PCL resection with modern, more conforming TKA designs. In this article, we review modern PCL sacrificing designs and discuss the impact of each on the kinematics after TKA. We also will delineate the role of the PCL in modern TKA in the hopes to better understand the recent surge in sacrificing but not substituting knee implants.

Cementless and Cemented Dual-pivot Total Knee Arthroplasty: A Matched Comparison with a Minimum Two-year Follow-up

INTRODUCTION

With the use of newer biomaterials, many authors have reported similar results between cementless and cemented total knee arthroplasty (TKA). The purpose of this study was to compare the early clinical and radiographic outcomes of cementless and cemented TKA using the same dual-pivot articulation.

METHODS

A consecutive series of 806 TKAs were implanted by a single surgeon using the same dual-pivot articulation. There were 634 TKAs (79%) cemented and 172 (21%) uncemented. One patient in the cementless group was lost before two years. The remaining 171 cementless TKAs were matched 1:1 with cemented TKAs with respect to age, sex, and body mass index (BMI). All patients were followed for a minimum of two years (range, 24 to 66 months) using the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR), and Knee Society clinical and radiographic evaluation. The average follow-up was 3.8 years (range, 24-66 months) in the cemented group and 3.4 years (range,24-56 months) in the cementless group.

RESULTS

At final follow-up, the average KOOS-JR score was higher in the cementless group (86 points (range, 64-100) vs. 80 points (range, 57-100). Post-op Knee Society scores (including pain and function) were similar. There was one deep infection (cemented TKA). The manipulation rate was 1.2% in the cementless group and 2.4% in the cemented TKA group. Excluding infection, two knees (1.2%) were revised in each group. No cases of femoral or tibial component loosening were identified.

CONCLUSION

Patients implanted with either a cemented or cementless TKA using the same conforming dual-pivot articulation design had similar early outcomes and functional improvements. The type of fixation did not appear to influence the early clinical results.

Native knee kinematics is not reproduced after sensor guided cruciates substituting total knee arthroplasty

PURPOSE

Gait analysis was used to evaluate knee kinematics in patients who underwent successful primary total knee arthroplasty (TKA) using two modern bi-cruciate substituting designs. The knee joint was balanced intraoperatively using real-time sensor technology, developed to provide dynamic feedback regarding stability and tibiofemoral load. The authors hypothesized that major differences exist in gait parameters between healthy controls and post-TKA patients.

METHODS

Ten patients who underwent successful TKA using bi-cruciate substituting designs were evaluated at a minimum of 9 months postoperatively using three-dimensional knee kinematic analysis; a multi-camera optoelectronic system and a force platform were used. Sensor-extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA) and knee rotational angle at heel-strike. Multiple gait analysis data from the study group were compared to a group of ten healthy controls who were matched by age, sex and BMI. Clinical outcome in the TKA group was also measured using the Knee injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Clinically, at final follow-up, a statistically significant difference in pain, general symptoms, and activities of daily living was seen between the groups. From a gait analysis standpoint, TKA patients had significantly less rotation at heel strike (p = 0.04), lower late stance peak extension moments (p = 0.02), and less Knee Adduction Angle excursion during swing phase (p = 0.04) compared to the control group. No statistically significant difference was observed for knee flexion angle at heel strike, knee adduction moment, or peak knee flexion moment between the groups.

CONCLUSIONS

Modern bi-cruciate substituting TKA designs failed to reproduce normal knee kinematics. The lack of full knee extension during the stance phase, absence of the "screw-home mechanism" typical of an ACL functioning knee, and the reduced fluctuation in knee adduction angle during the swing phase still represent major proprioceptive and muscular recruitment differences between normal and replaced knees.

The Effect of Posterior Cruciate Ligament Release on Kinematics and Outcomes in Primary Total Knee Arthroplasty With a Dual-Pivot Conforming Polyethylene

BACKGROUND

Ultracongruent bearings are increasingly utilized in total knee arthroplasty (TKA); however, implications of surgical technique on knee kinematics and outcomes with these bearings are not well understood. This study's purpose was to evaluate the relationship of 3-dimensional knee kinematics and patient-reported outcome measures (PROMs) in a dual-pivot congruent bearing TKA with and without posterior cruciate ligament (PCL) release.

METHODS

Forty patients undergoing TKA with an asymmetric ultracongruent bearing were prospectively enrolled for gait analysis preoperatively and 4 months postoperatively. Three-dimensional gait analysis was performed utilizing infrared motion capture. Knee kinematic data and PCL disposition were analyzed for correlations with PROMs.

RESULTS

The PCL was fully released in 52.5% (21/40) of cases. Greater maximum anteroposterior femoral translation correlated with lower Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (rho = -0.596, P = .012), greater Knee Society Score pain with level walking (rho = 0.411, P = .101), and greater Knee Society Score pain while climbing stairs (rho = 0.469, P = .058) at 4-month follow-up. The PCL-release group was associated with greater maximum femoral anteroposterior translation (9.8 vs 5.5 mm, P = .053) and greater maximum internal tibial rotation (-6.2° vs -3.0°, P = .040), supporting a more anterior-based position of the medial condyle. The PCL released group had lower median Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores (70.7 vs 76.3, P = .031) and reported that their knees "sometimes or always" feel normal less frequently (81.8% vs 92.3%, P = .576).

CONCLUSION

With this asymmetric ultracongruent bearing TKA, preservation or partial titration release of the PCL, as opposed to full PCL release, appears to minimize deleterious anterior femoral translation and internal tibial rotation, which is correlated with optimized patient-reported outcomes.

LEVEL OF EVIDENCE

II.

Press-Fit Dual-Pivot Total Knee Arthroplasty: Early Results With a Minimum 2-Year Follow-Up

BACKGROUND

Ultracongruent (UC) tibial bearings are being used with increasing frequency in the United States. Evidence suggests that the use of certain UC bearings may lead to improved patient satisfaction when compared with using conventional inserts. However, little is known as to what effect the use of UC tibial inserts has on bone ingrowth in uncemented total knee arthroplasty (TKA). The purpose of this study was to determine the early clinical and radiographic results of TKA using a press-fit dual-pivot design.

METHODS

Between 2017 and 2019, a consecutive series of 232 TKAs were implanted using a press-fit tibial and femoral component and a UC dual-pivot tibial insert. Sixty-two percent of patients were male. The average age was 56 years. Patients were followed for a minimum of 2 years (range, 24-42 months) using KOOS-JR and Knee Society clinical and radiographic evaluation.

RESULTS

No patient had more than mild knee stiffness at the final follow-up. Two patients reported moderate knee pain with stair climbing. All other patients reported either mild or no pain with activity. Knee Society pain scores averaged 42 points. Flexion averaged 118 degrees. Three knees (1.3%) were revised (one each for flexion instability, tibial plateau fracture, and suspected femoral component loosening). No other cases of femoral or tibial loosening were identified.

CONCLUSION

Although the success of uncemented TKA is determined by a variety of factors, the use of this dual-pivot knee design did not appear to influence tibial or femoral component fixation at early follow-up, yielding acceptable clinical and radiographic outcomes.

Conforming Polyethylene Inserts in Total Knee Arthroplasty: Beyond the Posterior-Stabilized and Cruciate-Retaining Debate

Total knee arthroplasty continues to be one of the most commonly performed surgical procedures worldwide. However, considerable controversy exists regarding the optimal implant design. Total knee implants with both posterior-stabilized and cruciate-retaining designs have excellent long-term outcomes with inadequate data demonstrating superiority of either design. Recently, the popularity of total knee designs with more conforming polyethylene liners has increased. These polyethylene inserts prevent paradoxical anterior translation of the femur, without relying on a cam and post mechanism, and promote more physiologic native knee kinematics. This review summarizes the design rationale of several commercially available implants, discusses the kinematic data of several designs, and reviews the available clinical data.

Retention of Posterior Cruciate Ligament Alone May Not Achieve Physiological Knee Joint Kinematics After Total Knee Arthroplasty: A Retrospective Study

BACKGROUND

The apparently physiological kinematics of the bicruciate-stabilized total knee arthroplasty (BCS TKA) systems have been attributed to the anterior and posterior post-cam mechanism. Although comparisons between TKA designs with either a retained or a sacrificed cruciate ligament have been conducted, we are not aware of any analyses of 2 implants with identical bearing geometry but different cruciate-ligament strategies under equal loading conditions. Knowledge about the kinematic effect of the different cruciate ligament strategies would potentially be valuable to facilitate preoperative planning and decision-making with regard to selecting the most appropriate implant for a patient.

METHODS

This retrospective study included 20 patients: 10 treated with a BCS and 10 treated with a cruciate retaining (CR) TKA. Fluoroscopic analyses during high-flexion activities (unloaded flexion-extension and loaded lunge) were conducted at 24 months postsurgery. All patients completed the Knee Society Score, Forgotten Joint Score, and High-Flexion Knee Score questionnaires preoperatively and postoperatively.

RESULTS

The BCS cohort showed greater femoral lateral rollback as well as a medial pivot in both activities. In contrast, the CR cohort showed a significant increase in anterior translation on the medial compartment as well as almost absent femoral lateral rollback. Higher clinical scores were observed in the BCS cohort.

CONCLUSIONS

At 24 months postsurgery, despite equal bearing geometry, retention of the posterior cruciate ligament in the CR cohort apparently was insufficient to reduce anterior shift. The BCS cohort showed expected knee joint kinematics; however, the kinematics in this cohort could eventually benefit from a smooth transition between the interchanging surfaces. Further investigation should be focused on the surgical technique and its interaction with the TKA design.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Total Knee Arthroplasty Using a Medial Pivot or Posterior Cruciate-Stabilizing Prosthesis in Chinese Patients

There is an unmet need for a prosthesis designed according to the anatomical parameters of the Chinese population. This study aims to compare the use of a medial pivot (MP) implant or posterior cruciate ligament (PCL) substitution (posterior-stabilized [PS]) prosthesis for unilateral total knee arthroplasty (TKA) in a Chinese population. The medical records of patients undergoing unilateral TKA with an MP implant (Group A) or a PS prosthesis (Group B) at our institution between January 2010 and December 2011 were retrospectively reviewed. Patients were followed up for 5 years. Preoperatively and at the December 2016 postoperative follow-up, the Hospital for Special Surgery scoring system (HSS knee score) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score were measured to evaluate TKA outcomes. This study included 49 patients in Group A and 51 in Group B. As of December 2016, there were no significant differences in the preoperative/postoperative changes in any category of the HSS knee score or WOMAC score between the groups. There were no postoperative complications in either group during the 5-year follow-up. There were no periprosthetic infections or need for revision surgery. One patient in Group A experienced aching and a small amount of effusion in the articular cavity that was attributed to overexertion. In conclusion, there were no significant differences in midterm outcomes in Chinese patients receiving an MP implant or a PS prosthesis for unilateral TKA. These data suggest that the MP and PCL substitution design are safe and effective for unilateral TKA in China.

A Single Surgeon Series Comparing the Outcomes of a Cruciate Retaining and Medially Stabilized Total Knee Arthroplasty Using Kinematic Alignment Principles

BACKGROUND

Total knee arthroplasty (TKA) designs are developed to optimize kinematics and improve patient satisfaction. The cruciate retaining (CR) and medially stabilized (MS) TKA designs have reported good mid-term follow-up outcomes. However, reasons for consistently high rates of patient dissatisfaction following a TKA remain poorly understood. To further investigate this, we compared the short-term functional outcomes and quality of life, using patient-reported outcome measures (PROMs) and range of motion (ROM), between a CR and MS TKA.

METHODS

A prospective comparison was made between 2 groups (44 CR-TKAs vs 46 MS-TKAs). The Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS-12, KOOS-Short form, KOOS-Joint Replacement, Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index, UCLA Activity Scale, and EuroQuality of life - 5 Dimension were completed preoperatively and 1 year postoperatively. The Forgotten Joint Score (FJS) and Visual Analogue Scale-Satisfaction were completed at 1 year postoperatively. ROM was collected preoperatively and 1 year postoperatively.

RESULTS

Patients who underwent an MS-TKA scored significantly better than the CR-TKA on the FJS (MS = 79.87, CR = 63.8, P = .005), the KOOS-12 Quality of Life subscale (MS = 82.8, CR = 74.4, P = .43), and the KOOS Quality of Life subscale (MS = 82.8, CR = 74.6, P = .44). There was no difference between the groups in all assessed PROMs or ROM, preoperatively and 1 year postoperatively.

CONCLUSION

Patients who underwent the MS-TKA scored significantly better on the FJS and the quality of life subscale of the KOOS and KOOS-12 than those who underwent a CR-TKA. All other assessed PROMs and ROM were comparable between the 2 groups and demonstrated that both implants facilitated symptom relief and improved daily function at 1 year postoperatively. These findings suggest that at short-term follow-up, the MS device is more likely to allow a patient to "forget" that a joint has been replaced and restore their quality of life. Long-term assessment of MS-TKA design outcomes in larger cohorts is recommended.

Weight Bearing Activities change the Pivot Position after Total Knee Arthroplasty

The knee joint center of rotation is altered in the absence of the anterior cruciate ligament, which leads to substantially higher variance in kinematic patterns. To overcome this, total knee arthroplasty (TKA) designs with a high congruency in the lateral compartment have been proposed. The purpose of this study was to analyze the influence of a lateral pivot TKA-design on in-vivo knee joint kinematics. Tibiofemoral motion was retrospectively addressed in 10 patients during unloaded flexion-extension and loaded lunge using single plane fluoroscopy. During the unloaded flexion-extension movement, the lateral condyle remained almost stationary with little rollback at maximum flexion. The medial condyle exhibited anterior translation during the whole flexion cycle. During the loaded lunge movement, a higher degree of rollback compared to the unloaded activity was observed on the lateral condyle, whereas the medial condyle remained almost stationary. The results showed a clear lateral pivot during the unloaded activity, reflective of the implant’s geometric characteristics, and a change to a medial pivot and a higher lateral rollback during the weight-bearing conditions, revealing the impact of load and muscle force. It remains unclear if the kinematics with a lateral TKA design could be considered as physiological, due to the limited knowledge available on native knee joint kinematics.

Kinematic analysis of stair climbing in rotating platform cruciate-retaining and posterior-stabilized mobile-bearing total knee arthroplasties

INTRODUCTION

The aim of our study was to compare and contrast the effects of two types of mobile-bearing total knee arthroplasties (TKA), namely, the cruciate-retaining (CR) and posterior-stabilized (PS) TKAs, on clinical outcomes and in vivo kinematics during stair climbing.

MATERIALS AND METHODS

The Press-Fit Condylar Sigma rotating platform was used for both CR and PS TKAs. Patient-reported outcomes were assessed using the 2011 Knee Society Score. Quadriceps muscle strength was evaluated by isokinetic dynamometry. In vivo kinematics were evaluated using periodic sagittal plane radiographic images obtained during stair climbing to quantify anteroposterior (AP) tibiofemoral translation, implant flexion and axial rotation angles using image-matching techniques. Outcomes were evaluated in 20 TKAs, which had been undergone with clinical success, including ten knees with CR types and ten knees with PS types.

RESULTS

There were no significant differences between the CR and PS TKA groups (p > 0.05) in isometric extensor torque (1.0 ± 0.2 and 1.1 ± 0.6 N m/kg, respectively) or patient-reported score for stair climbing function (4.0 ± 0.5 and 3.8 ± 0.9, respectively). Both types of TKAs showed stable AP translation in the mid range of knee flexion and paradoxical translation in the low range of flexion, with limited rotation, during stair climbing. There were no significant differences between the CR and PS TKA groups (P > 0.05) in anterior translation from 80° to 40° of knee flexion (4.2 ± 1.2 and 3.5 ± 1.6 mm, respectively), posterior translation from 40° to 10° of knee flexion (2.3 ± 1.9 and 2.0 ± 1.5 mm, respectively), and total external rotation (2.8° ± 4.9° and 0.5° ± 5.0°, respectively).

CONCLUSIONS

Both CR and PS types of rotating platform mobile-bearing TKAs provided reproducible knee joint kinematics during stair climbing and equivalent clinical outcomes.

LEVEL OF EVIDENCE

IV.

In vitro biomechanical evaluation of tri-condylar total knee arthroplasty with posterior release for restoration of full extension

Background/Objective

The continuous improvement of knee function during deep flexion remains a challenge in total knee arthroplasty. Tri-condylar total knee arthroplasty has been designed to achieve this goal. However, the introduction of a third nonanatomic spherical condyle might prevent the joint from reaching full extension due to posterior soft tissue tightening. This study aimed to address these issues related to soft tissue tightening and full extension limitation.

Methods

Biomechanical tests were performed on six cadaveric specimens of the entire lower extremities. The tri-condylar design was compared with a posterior cruciate sacrificing design of the same shape without the ball structure. Knee joint kinematics was measured, including the extension and flexion angles, the extension balance, and the extension gap. The test was repeated after release of the medial and lateral posterior intercondylar soft tissues at a safe distance from the popliteal artery and nerves.

Results

Both designs resulted in a knee flexion angle up to ∼130°. The tri-condylar design showed an extension angle of -11.2 ± 5.4°, which was a significantly greater limitation than that obtained with the cruciate sacrificing design (-3.8 ± 4.7°; p = 0.047). Moreover, the extension angle of the tri-condylar design was significantly improved after the release of posterior intercondylar soft tissues (-0.1 ± 6.7°; p = 0.028).

Conclusion

The tri-condylar design efficiently allowed the full extension by the release of posterior intercondylar soft tissues at a safe distance from the popliteal artery and nerves.