Retention Of Posterior Cruciate Ligament Research Articles

Posterior Cruciate Ligament Preservation versus Posterior Cruciate Ligament Sacrifice: Comparing Patient Outcomes in Medial Congruent Total Knee Arthroplasty.

This study aimed to compare outcomes and complication rates between posterior cruciate ligament (PCL) retention and excision utilizing a medial congruent (MC) polyethylene insert in total knee arthroplasty (TKA) in a specialized ambulatory surgery center (ASC) dedicated to hip and knee arthroplasty. A retrospective review was performed between May 2023 and October 2023 analyzing 398 patients who underwent primary MC TKA by high-volume joint arthroplasty surgeons (n = 9) with either PCL preservation (n = 264) or sacrifice (n = 134) in a single free-standing ASC. Patients were matched chronologically on a 2:1 basis. Demographics, baseline function, 90-day complications, and patient-reported outcomes were recorded for each patient. There were no differences in preoperative baseline function or patient-reported outcome measures, Charlson Comorbidity Index, or American Society of Anesthesiologists class among patient groups. The PCL-preserve and PCL-sacrifice cohorts showed significant variation in 12-week postoperative Knee Injury and Osteoarthritis Outcome, Junior (KOOS, JR.) scores. Specifically, the number of patients who achieved the minimal clinically important difference (MCID) in KOOS, JR. scores was higher in the PCL-sacrifice group (p < 0.05). Yet, no complications within the 90-day period were associated with PCL status and other patient-reported outcomes. This study comparing outcomes between MC TKAs with PCL retention and sacrifice suggests that both techniques are viable options with similar functional outcomes, pain scores, and complication rates, which may have benefits in an ASC setting. The PCL-sacrifice group exhibited a statistically significant increase in patients who achieved the MCID in KOOS, JR. score compared with the PCL-preserving at early follow-up. Future research should employ prospective, randomized designs to further validate these findings and explore long-term implications.

An Insert Goniometer Can Help Select the Optimal Insert Thickness When Performing Kinematically Aligned Total Knee Arthroplasty with a Medial 1:1 Ball-in-Socket and Lateral Flat Surface Insert and Posterior Cruciate Ligament Retention.

Current surgical practices in total knee arthroplasty (TKA) have advanced and include significant changes and improvements in alignment philosophies, femorotibial implant conformities, and ligament management to replicate in vivo knee kinematics. While corrective measures have emphasized sagittal plane alignment to restore normal flexion-extension (F-E) motion and coronal plane ligament balance, internal-external (I-E) rotation kinematics in the axial plane have been largely neglected. Recent in vivo evidence indicates that the combination of factors necessary to closely restore native tibial rotation as the knee flexes and extends is kinematic alignment (KA), which resurfaces the patient's pre-arthritic knee without releasing ligaments, an insert with medial 1:1 ball-in-socket conformity and a lateral flat surface, and posterior cruciate ligament (PCL) retention. However, the inherent anterior-posterior (A-P) stability provided by the medial 1:1 ball-in-socket limits the surgeon's ability to select the correct insert thickness using manual laxity testing. Accordingly, this review presents the design and validation of an instrument called an insert goniometer that measures I-E tibial rotation for inserts that differ in thickness by 1 mm and uses rotation limits at extension and 90° flexion to select the optimal insert thickness. The optimal thickness is the one that provides the greatest external tibial orientation in extension and internal tibial orientation at 90° flexion without lift-off of the insert.

Retention of the posterior cruciate ligament stabilizes the medial femoral condyle during kneeling using a tibial insert with ball-in-socket medial conformity.

Resecting the posterior cruciate ligament (PCL) increases posterior laxity and increases the flexion gap more than the extension gap in the native (i.e. healthy) knee. These two effects could lead to significant anterior displacement of the medial femoral condyle in kneeling following total knee arthroplasty even when using a tibial insert with a high degree of medial conformity. Using an insert with ball-in-socket medial conformity and a flat lateral articular surface, the primary purpose was to determine whether the medial femoral condyle remained stable with and without PCL retention during kneeling. Two groups of patients were studied, one with PCL retention (22 patients) and the other with PCL resection (25 patients), while kneeling at 90º flexion. Following 3D model-to-2D image registration, A-P displacements of both femoral condyles were determined relative to the dwell point of the medial socket. With PCL resection versus PCL retention, the medial femoral condyle was 5.1 ± 3.7mm versus 0.8 ± 2.1mm anterior of the dwell point (p < 0.0001). Patient-reported function scores were comparable (p ≥ 0.1610) despite a significantly shorter follow-up of 7.8 ± 0.9 months with PCL retention than 19.6 ± 4.9 months with PCL resection (p < 0.0001). Range of motion was 126 ± 8° versus 122 ± 6° with and without PCL retention, respectively (p = 0.057). Surgeons that use a highly conforming tibial insert design can stabilize the medial femoral condyle during kneeling by retaining the PCL. In patients with PCL resection, the 9mm high anterior lip of the insert with ball-in-socket medial conformity was insufficient to prevent significant anterior displacement of the medial femoral condyle when weight-bearing on the anterior tibia.

Comparative analysis and validation of posterior cruciate ligament management in mobile-bearing total knee arthroplasty: Meta-analysis and animal study.

Total knee arthroplasty (TKA) is an effective treatment for end-stage knee joint diseases. The debate over preserving or sacrificing the posterior cruciate ligament (PCL) in mobile-bearing TKA (MB TKA) still needs to be solved due to the lack of high-quality evidence, particularly meta-analyses comparing these techniques. This study aims to conduct a meta-analysis to compare the outcomes of PCL retention (CR) and PCL sacrifice (PS) in terms of clinical and functional knee scores, range of motion, complication rates, and revision rates and to validate these findings through animal experiments. A comprehensive search was conducted using MEDLINE, Cochrane, and Embase databases. Relevant studies were selected for the meta-analysis using RevMan 5.3. Additionally, an animal experiment using Sprague-Dawley rats simulated MB TKA to compare the effects of PCL retention and sacrifice surgeries. 12 studies were included in the meta-analysis. No significant differences were found between CR and PS techniques regarding HSS, KSS, KSFS, WOMAC, ROM, and medial/lateral instability. However, CR MB showed slight superiority in NKJS, while PS MB had better outcomes in complication and revision rates. In the animal study, CR rats exhibited significant early postoperative inflammation, but both groups' knee structures gradually normalized. The meta-analysis indicates that PCL retention (CR MB) and sacrifice (PS MB) have similar effects on various clinical and functional knee scores. However, PS MB is significantly better at reducing complications and revision rates. The animal experiment confirms PS MB's advantages in reducing inflammation and promoting joint recovery. Despite the strong evidence, long-term follow-up and larger-scale randomized controlled trials are necessary to confirm these findings.

Developing a Machine-Learning Predictive Model for Retention of Posterior Cruciate Ligament in Patients Undergoing Total Knee Arthroplasty.

Predicting whether the posterior cruciate ligament (PCL) should be preserved during total knee arthroplasty (TKA) procedures is a complex task in the preoperative phase. The choice to either retain or excise the PCL has a substantial effect on the surgical outcomes and biomechanical integrity of the knee joint after the operation. To enhance surgeons' ability to predict the removal and retention of the PCL in patients before TKA, we developed machine learning models. We also identified significant feature factors that contribute to accurate predictions during this process. Patients' data on TKA continuously performed by a single surgeon who had intended initially to undergo implantation of cruciate-retaining (CR) prostheses was collected. During the sacrifice of PCL, we utilized anterior-stabilized (AS) tibial bearings. The dataset was split into CR and AS categories to form distinct groups. Relevant information regarding age, gender, body mass index (BMI), the affected side, and preoperative diagnosis was extracted by reviewing the medical records of the patients. To ensure the authenticity of the research, an initial step involved capturing X-ray images before the surgery. These images were then analyzed to determine the height of the medial condyle (MMH) and lateral condyle (LMH), as well as the ratios between MLW and MMH and MLW and LMH. Additionally, the insall-salvati index (ISI) was calculated, and the severity of any varus or valgus deformities was assessed. Eight machine-learning methods were developed to predict the retention of PCL in TKA. Risk factor analysis was performed using the SHApley Additive exPlanations method. A total of 307 knee joints from 266 patients were included, among which there were 254 females and 53 males. A stratified random sampling technique was used to split patients in a 70:30 ratio into a training dataset and a testing dataset. Eight machine-learning models were trained using data feeding. Except for the AUC of the LGBM Classifier, which is 0.70, the AUCs of other machine learning models are all lower than 0.70. In importance-based analysis, ISI, MMH, LMH, deformity, and age were confirmed as important predictive factors for PCL retention in operations. The LGBM Classifier model achieved the best performance in predicting PCL retention in TKA. Among the potential risk factors, ISI, MMH, LMH, and deformity played essential roles in the prediction of PCL retention.

Risk of tibial baseplate loosening is low in patients following unrestricted kinematic alignment total knee arthroplasty using a cruciate-retaining medial conforming insert: A study using radiostereometric analysisat 2 years.

Assessing the risk of tibial baseplate loosening in patients after unrestricted kinematically aligned (unKA) total knee arthroplasty (TKA) using a medially conforming insert is important because baseplates generally are aligned in varus which has been linked to an increased incidence of aseptic loosening following mechanically aligned TKA. Two limits that indicate long-term stability in patients are a change in maximum total point motion between 1 and 2 years (ΔMTPM) < 0.2 mm and anterior tilt at 2 years < 0.8°. The purposes were to determine: (1) the number of patients with ΔMTPM > 0.2 mm, (2) the number of patients with anterior tilt > 0.8°and (3) whether increased varus baseplate and limb alignment were associated with increased migration. Thirty-five patients underwent cemented, caliper-verified, unKA TKA using a medially conforming tibial insert with posterior cruciate ligament (PCL) retention. Biplanar radiographs acquired on the day of surgery and at 1.5, 3, 6, 12and 24 months were processed with model-based radiostereometric analysis (RSA) software to determine migration and the number of patients with migration above the two stability limits. Medial proximal tibial angle (MPTA), hip-knee-ankle angle (HKAA)and posterior slope angle (PSA) were analyzed for an association with migration in six degrees of freedom and in MTPM. Thirty-two of 35 patients were available for analysis at 2 years. One patient exhibited ΔMTPM > 0.2 mm. The same patient exhibited anterior tilt > 0.8°. Varus rotation (p = 0.048, r ≤ 0.34) and medial translation (p = 0.0273, r ≤ 0.29) increased with increased varus baseplate alignment. The results indicate low risk of long-term baseplate loosening in patients. Although varus rotation and medial translation increased with increased varus baseplate alignment, the magnitudes of the migrations were minimal and did not increase ΔMTPM and anterior tilt. Level II, therapeutic prospective cohort study.

Current State of Knee Arthroplasty in Russia: Analysis of 36,350 Сases from the Register of the Vreden National Medical Research Center of Traumatology and Orthopedics

Background.Nowadays the knee arthroplasty register of the Vreden National Medical Research Center of Traumatology and Orthopedics (hereinafter referred to as the Vreden Center) contains clinical and statistical data on more than 39,000 primary and revision knee replacements, that mimics current state of this kind of surgery in Russia.&#x0D; Aimofthestudy to analyze the last decade trends in primary knee arthroplasty in largest Russian arthroplasty center.&#x0D; Methods.Data were obtained from the register of the Vreden Center for the period from 2011 to 2022. Information on knee arthroplasty included epidemiologic and numerous peri-operative data including type of surgery and implant, degree of constrain, primary patella resurfacing etc.&#x0D; Resultsanddiscussion.From 2011 to 2022, 36,350 (92.3%) primary arthroplasties performed at the Vreden Center.&#x0D; The number of interventions increased more than twice: from 1,678 in 2011 to 3,924 in 2022. Similar trends observed in Australia and Sweden, where the number of knee arthroplasties increased by 8.2% and 8% in 2021 compared to 2020, respectively. The frequency of primary patellar resurfacing at the Vreden Center was 2.2% over the entire period of observation. On the contrary, the rate of patella replacement increased from 41% in 2005 to 76.1% in 2021 in Australia and from 24.4% in 2015 to 31.9% in 2020 in Switzerland. The partial knee arthroplasty showed enormous growth more than 14 times: from 0.3% in 2011 to 4.3% in 2022 at the Vreden Center. Worldwide unicompartmental knee replacement is still less popular than total and its number widely varies: 4.2% in the USA, 6.9% in Australia, 9.2% in Canada, 11.9% in Norway, 12.8% in Sweden, and 18.4% in Switzerland. Posterior cruciate ligament (PCL) retaining total knee arthroplasties (TKA) prevailed at the Vreden Center: 68.3%, while in other countries it utilize even more widely: 70.5% in Norway, 75% in New Zealand and 93.5% in Sweden.&#x0D; The total length of hospital stay (LOS) decreased dramatically from 19.6 in 2011 to 8.6 in 2022 at the Vreden Center. Nevertheless, there are still opportunities to improve it: by the way in Canada the average LOS for TKA is 2.3 and the USA 0.8 and 1.7 for partial and total arthroplasty, respectively.&#x0D; Conclusion.The main current trends of knee arthroplasty in Russia are the following: increase the number of surgeries, reduced LOS, TKA without patella resurfacing and with PCL retention, finally the growth of partial knee arthroplasties.

Macroscopic and histological evaluation of the posterior cruciate ligament in arthritic knees

The function of Posterior Cruciate Ligament (PCL) in Total Knee Arthroplasty is currently under debate. Supporters of PCL retention suggest better soft tissue balance as well as proprioception, whereas the adversaries have reported an unstable late flexion. Whether the PCL is retained or removed, the results of knee replacement remains the same. The aim of the present study was to look for the morphologic and histological changes in PCL, that aids in assessing its competence, and to compare these with macroscopic changes. A prospective study was performed on 50 osteoarthritic knees. Both the cruciate ligaments were examined macroscopically during Total Knee Replacement surgery, and classified as normal, fatty, mucinous, or cystic. The PCL was also studied and staged histopathologically, and was compared with its macroscopic appearance. On macroscopic examination, fatty type degeneration was the most common type of degeneration in both PCL and ACL, seen in 68% and 56% cases respectively. Histopathologically, majority of the PCLs (52.4%) were in stage 1 of degeneration. 5 PCLs that appeared macroscopically normal showed degeneration microscopically and 8 PCLs that were histologically normal had fatty as well as mucinous degeneration on macroscopic examination.PCL exhibits degenerative and chronic traumatic modifications of different degrees on microscopic examination. These changes cannot be predicted from macroscopic inspection of the knee at the time of surgery. The frequency of these changes suggests that PCLs in an osteoarthritic knee are of varying quality, and this should be considered by the surgeon while selecting the type of knee replacement.

Posterior cruciate ligament retention with medial ball-in-socket conformity promotes internal tibial rotation and knee flexion while providing high clinical outcome scores

BackgroundAlthough retaining the posterior cruciate ligament (PCL) is advantageous in unrestricted kinematically aligned TKA, it is often excised with a medial stabilized implant. The primary objectives were to determine whether PCL retention using an insert with ball-in-socket (B-in-S) medial conformity to maximize A-P stability promotes internal tibial rotation and flexion while providing high patient-reported outcome scores. MethodsTwo cohorts of 25 patients each were treated with unrestricted kinematically aligned (KA) TKA using a tibial insert with B-in-S medial conformity and a flat lateral articular surface. One cohort retained the PCL; the other had it excised. Patients performed deep knee bend and step-up exercises during fluoroscopic imaging. Following 3D model-to-2D image registration, anterior-posterior (A-P) positions of the femoral condyles and tibial rotation were determined. ResultsFor deep knee bend, mean internal tibial rotation with PCL retention was significantly greater at maximum flexion (17.7° ± 5.7° versus 10.4° ± 6.5°, p < 0.001) and significantly greater at 30°, 60°, and 90° flexion as well (p ≤ 0.0283). For step-up, mean internal tibial rotation with PCL retention was significantly greater at at 15°, 30°, and 45° flexion (p ≤ 0.0049) but was marginally not significantly greater at 60° (i.e. maximum) flexion (12.3° ± 4.4° versus 10.1° ± 5.4°, p = 0.0794). Mean flexion during active knee flexion with PCL retention was significantly greater (127° ± 8° versus 122° ± 6°, p = 0.0400). Both cohorts had high median Oxford Knee, WOMAC, and Forgotten Joint Scores that were not significantly different (p = 0.0918, 0.1448, and 0.0855, respectively) ConclusionSurgeons that perform unrestricted KA TKA should retain the PCL with an insert that has B-in-S medial conformity, as this maintains extension and flexion gaps while also promoting internal tibial rotation and knee flexion as well as providing high clinical outcome scores.

A Torn or Reconstructed Anterior Cruciate Ligament Does Not Adversely Affect Clinical Outcome Scores and the Incidence of Reoperation After Unrestricted Kinematically Aligned Total Knee Arthroplasty

BackgroundThere are no reports as to whether the condition of the anterior cruciate ligament (ACL) adversely affects the 2 to 3 year function and reoperation risk of a kinematically aligned (KA) total knee arthroplasty (TKA) performed with posterior cruciate ligament (PCL) retention and an intermediate medial conforming (MC) insert. MethodsA single surgeon’s prospective database query identified 418 consecutive primary TKAs performed between January 2019 and December 2019. The surgeon recorded the ACL condition in the operative note. Patients filled out the Forgotten Joint Score (FJS), Oxford knee score (OKS), and Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement at the final follow-up. There were 299 patients with an intact ACL, 99 with a torn ACL, and 20 with a reconstructed ACL. The mean follow-up was 31 months (range, 20 to 45). ResultsThe median FJS, OKS, and Knee Injury and Osteoarthritis Outcome Score (KOOS) of the reconstructed/torn/intact KA TKAs were 90/79/67, 47/44/43, and 92/88/80 points, respectively. The median OKS and KOOS of the reconstructed ACL cohort were 4 and 11 points higher than in the intact ACL cohort (P = .003, .04). One patient who had a reconstructed ACL underwent manipulation under anesthesia (MUA) for stiffness. The 5 reoperations in the intact ACL cohort were for instability (n = 2), revision after failed MUA for stiffness (n = 2), and infection (n = 1). ConclusionThese results suggest that patients who have a torn and reconstructed ACL can expect high function and a low risk of reoperation comparable to patients who have an intact ACL when treated with unrestricted, caliper-verified KA, PCL retention, and an intermediate MC insert.

Ball-in-socket medial conformity with posterior cruciate ligament retention neither limits internal tibial rotation and knee flexion nor lowers clinical outcome scores after unrestricted kinematically aligned total knee arthroplasty.

For a new tibial insert design with ball-in-socket (B-in-S) medial conformity (MC), posterior cruciate ligament (PCL) retention, and flat lateral articular surface (B-in-S MC + PCL), this study determined whether internal tibial rotation and knee flexion were limited and clinical outcome scores were lower during weight-bearing activities relative to an insert with intermediate (I) (i.e., less than ball-in-socket) medial conformity (I MC + PCL). Twenty-five patients were treated with bilateral unrestricted, caliper-verified kinematic alignment (KA) total knee arthroplasty (TKA) with an I MC + PCL insert and B-in-S MC + PCL insert in opposite knees. Each patient performed weight-bearing deep knee bend, step up, and chair rise under single-plane fluoroscopy. Analysis following 3D model-to-2D image registration determined internal tibial rotation. For each TKA, knee flexion was measured and patients completed clinical outcome scoring questionnaires. Internal tibial rotation did not differ between conformities during chair rise and step up (p = 0.3419 and 0.1030, respectively). During deep knee bend, internal tibial rotation between 90° and maximum flexion was 3° greater in the B-in-S MC + PCL group (18° vs 15°) (p = 0.0290). Mean knee flexion (p = 0.3115) and median Forgotten Joint Score (FJS), Oxford Knee Score (OKS), and Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores (p = 0.2100, 0.2154, and 0.4542, respectively) did not differ between conformities. An insert with ball-in-socket medial conformity, which maximizes anteroposterior (AP) stability, did not limit internal tibial rotation and knee flexion and did not lower patient-reported outcomes when implanted with unrestricted caliper-verified KA and PCL retention. Thehigh AP stability provided by the medial ball-in-socket might interest those surgeons exploring the treatment of theactive patient with a desire to return to high-level and athletic activities.

Effect of posterior cruciate ligament on knee pressure and gap measured by an electronic sensor during total knee arthroplasty

PurposeThe purpose of this study was to evaluate the change in posterior cruciate ligament (PCL) tension by directly measuring the pressure changes in the knee joint when the ligament was released or resected during total knee arthroplasty.MethodsWe prospectively analyzed 54 patients who underwent primary total knee arthroplasty (67 knees) from October 2019 to January 2022. An electronic pressure sensor was used to measure the pressure changes in the medial and lateral chambers on PCL retention, recession or resection.ResultsAt 0°, 45°, 90° and 120° of flexion, the total pressure in the knee joint of PCL retention was significantly higher than with PCL recession, and even higher than PCL resection. PCL recession or resection affected knee joint extension, and the medial/lateral pressure in the knee joint decreased. Pressure in the lateral compartment showed no significant change during knee flexion, whereas pressure in the medial compartment was significantly decreased, which also led to a change in the ratios of the medial and lateral pressures in the knee joint. After PCL resection, the flexion gap (90°) increased significantly more than the extension (0°) gap, while 46 cases displayed the same change in the flexion and extension gaps after PCL resection of the 67 cases.ConclusionThe PCL retained partial function after tibial recession. PCL resection affected both the flexion and extension gaps; although the average flexion gap increased more than the extension gap, the change in most cases of these two gaps was the same.

A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention closely restores native knee tibial rotation after unrestricted kinematic alignment

PurposeIn total knee arthroplasty (TKA) with posterior cruciate ligament (PCL) retention, the medial and lateral insert conformity that restores in vivo native (i.e., healthy) knee tibial rotation and high function without causing stiffness is unknown. The purpose was to determine whether a ball-in-socket (B-in-S) medially conforming (MC) and flat lateral insert implanted with unrestricted kinematic alignment (KA) TKA and PCL retention restores tibial rotation to native.MethodsOne group of 25 patients underwent unrestricted KA TKA with manual instruments. Another group of 25 patients had native knees. Single-plane fluoroscopy imaged each knee while patients performed step-up and chair rise activities. Following 3D model-to-2D image registration, anterior–posterior (A-P) positions of the femoral condyles were determined. Changes in A-P positions with flexion were used to determine tibial rotation.ResultsAt maximum flexion, mean tibial rotations of KA TKA knees were comparable to native knees (Step up: 12.3° ± 4.4° vs. 13.1° ± 12.0°, p = 0.783; Chair Rise: 12.7° ± 6.2° vs. 12.6° ± 9.5º, p = 0.941). However, paths of rotation differed in that screw home motion was less evident in KA TKA knees. At 8 months follow-up, the median Forgotten Joint Score was 69 points (range 65 to 85), the median Oxford Knee Score was 43 points (range 40 to 46), and mean knee flexion was 127º ± 8°.ConclusionsThe ball-in-socket medial, flat lateral insert and PCL retention implanted with unrestricted KA TKA restored in vivo native knee tibial rotation at maximum flexion for each activity and high function without stiffness. Providing high A-P stability, this implant design might benefit patients desiring to return to demanding work and recreational activities.Level of evidenceTherapeutic – Level II.

Low tibial baseplate migration 1year after unrestricted kinematically aligned total knee arthroplasty using a medial conforming implant design.

Varus alignment of the tibial baseplate and limb > 3° might adversely affect baseplate fixation after total knee arthroplasty (TKA), especially for unrestricted kinematically aligned (KA) TKA which aligns a majority of baseplates in varus. The purposes of this study were to determine whether baseplate migration at 1year (1) was significantly less than a stability limit of 0.5mm, (2) increased over time, and (3) was related to varus alignment of the baseplate and limb after unrestricted KA TKA. Thirty-five patients underwent unrestricted KA TKA using a fixed-bearing, cemented, medial conforming tibial insert with posterior cruciate ligament retention. Using model-based radiostereometric analysis, maximum total point motion (MTPM) (i.e., largest displacement on the baseplate) was computed at 6weeks, 3months, 6months, and 1year postoperatively relative to the day of surgery. Baseplate and limb alignment were measured postoperatively on long-leg CT scanograms. At 1year, mean MTPM of 0.35mm was significantly less than the 0.5mm stability limit (p = 0.0002). Mean MTPM did not increase from 6weeks to 1year (p = 0.3047). Notably, 89% (31/35) of tibial baseplates and 46% (16/35) of limbs were > 3° varus. Baseplate and limb alignment had no relationship to MTPM at 1year (|r|≤ 0.173, p ≥ 0.3276). Low and non-progressive tibial baseplate migration 1year after unrestricted KA TKA with a medial conforming design should allay any concern that unrestricted KA TKA increases risk of baseplate looseningdue to varus alignment of the baseplate and limb. Level II, therapeutic prospective cohort study.

Preoperative Factors Predicting the Preservation of the Posterior Cruciate Ligament in Total Knee Arthroplasty.

ObjectivePredicting the successful preservation of posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) is an important step for preoperative planning to secure the satisfactory outcomes. We aimed to examine the preoperative factors predicting the successful preservation of the PCL in cruciate‐retaining TKA and the outcome of sacrificing the PCL.MethodsIn this retrospective study, we analyzed TKAs consecutively performed by a single surgeon between January 2019 and August 2021 who had been preoperatively planned to undergo implantation of cruciate‐retaining (CR) prostheses. The outcome of the current study was whether the PCL was retained or sacrificed. Anterior‐stabilized (AS) tibial bearings when the PCL was sacrificed as needed were used intraoperatively. Age, sex, body mass index (BMI), and preoperative diagnosis from the patients' medical records were obtained. The medial‐lateral width of epicondyle (MLW), the medial posterior condyle height (MPCH), the lateral posterior condyle height (LPCH), the ratio of MLW and MPCH, the ratio of MLW and LPCH, the Insall–Salvati index, and the severity of the varus or valgus deformity were measured using preoperative radiographs. Univariate and multivariate regression were fitted to assess the association of these factors with the successful retention of PCL. To examine the influence of sacrifice of the PCL on the surgical procedure, the size of the tibial and femoral components, the thickness of the polyethylene insert, and the rate of patella replacement between the CR group and AS group were also compared using t tests or chi‐square tests.ResultsAmong 307 TKAs included, PCL was sacrificed with concurrent use of AS prostheses in 89 (29.0%) procedures. Knees with rheumatoid arthritis (P < 0.01), lower Insall–Salvati index (P < 0.01), and more severe varus deformity (P = 0.011) were at a higher risk of sacrificing the PCL intraoperatively. There was no significant difference in age, sex, BMI, MLW, MPCH, LPCH, ratio of MLW and MPCH, ratio of MLW and LPCH, size of the tibial and femoral components, or replacement of the patella between the CR and AS groups. Converting from CR to AS was associated with a higher risk of using a thicker polyethylene insert (P < 0.01).ConclusionRheumatoid arthritis, lower Insall–Salvati index, and more severe varus deformity were associated with an increased risk of sacrificing the PCL in TKAs planned to undergo implantation CR prostheses. Converting to AS tibial bearing may result in a thicker polyethylene insert. These factors should be carefully considered for the appropriate selection of prosthesis type preoperatively.

A TKA Insert with A Lateral Flat Articular Surface Maximizes External and Internal Tibial Orientations without Anterior Lift-Off Relative to Low- and Ultracongruent Surfaces.

Background: In total knee arthroplasty (TKA), inserts can have different levels of medial and lateral congruency determined by the acuteness of the upslopes of the anterior and posterior articular surfaces. The present study evaluated an insert with different levels of lateral congruency and a medial ball-in-socket congruency to test the hypothesis that a lateral flat (F) insert maximizes external tibial orientation at extension and internal orientation at 90° flexion and lowers the incidence of anterior lift-off relative to low-congruent (LC) and ultracongruent (UC) lateral inserts. Methods: Two surgeons treated 23 patients with unrestricted caliper-verified kinematic alignment (KA) and posterior cruciate ligament (PCL) retention. They randomly trialed inserts with a medial radial dial that functioned as a built-in goniometer by measuring the tibial orientation relative to a sagittal line on the femoral trial component. Anterior lift-off of the insert from the baseplate indicated PCL tightness. Results: The F insert’s mean of 9° of external tibial orientation was higher than that of the LC (5°, p < 0.0001) and UC inserts (2°, p < 0.0001). The −13° of internal tibial orientation at 90° flexion was higher than that of the LC (−9°, p < 0.0001) and UC inserts (−7°, p < 0.0001). The 0% incidence of anterior lift-off was less than that of the LC (26%) and UC inserts (57%) (p < 0.0001). Conclusions: Surgeons and implant manufacturers should know that adding congruency to the lateral articular surface limits external tibial orientation in extension and internal tibial orientation at 90° flexion and overtightens the PCL. These rotational limitations and flexion space tightness can adversely affect patellofemoral tracking and knee flexion.

Effects of the posterior cruciate ligament and tibia insert thickness on tibiofemoral joint pressure in total knee arthroplasty: a cadaveric study.

BackgroundEmerging knowledge has highlighted the significant role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA). However, few studies have reported how the PCL affects tibiofemoral joint pressure (TFP), and differences in the effects of the PCL and the effects of tibial insert thickness on TFP remain unknown. Thus, this study used the sensor technique to analyze and compare the effects of PCL and tibial insert thickness on TFP during knee flexion.MethodsCruciate-retaining total knee arthroplasty (CR-TKA) was performed in 8 cadaveric knees. The PCL was partially released and completely resected sequentially while the tibial insert thickness was increased from 10- to 12-mm at 1-mm intervals. With the optimal tibial insert in place, the effects of PCL release and resection on medial and lateral TFP during knee flexion were analyzed. Medial tibiofemoral joint pressure (MTFP) with PCL retention and a 12-mm tibial insert was set as the baseline. The effects of PCL resection without tibial insert thickness reduction on MTFP were compared to the effects of PCL retention with a 1- or 2-mm thinning of the tibial insert on MTFP during knee flexion.ResultsPCL resection significantly reduced MTFP at 90° and 120° of knee flexion (P=0.01 and P=0.03, respectively). Partial release and complete resection of the PCL did not significantly reduce lateral tibiofemoral joint pressure (LTFP) at 10°, 30°, 60°, 90° and 120° of knee flexion (P=0.68, P=0.60, P=0.62, P=0.21 and P=0.12, respectively). At 10°, 30°, and 60° of knee flexion, a 1-mm reduction in the tibial insert had a greater effect on MTFP than did the resection of the PCL. In contrast, at 90° of knee flexion, MTFP was more affected by PCL resection than by a 2-mm reduction of the tibial insert.ConclusionsThe PCL predominantly affects MTFP at 90° and 120° of knee flexion. The impact of PCL resection on MTFP at 90° flexion was higher than the impact of a 2-mm thinning of the tibial insert.

Does Retention of the Posterior Cruciate Ligament Lead to a More "Forgotten Joint" Following Total Knee Arthroplasty?

Posterior cruciate ligament (PCL) retention may impact a patient's awareness of their artificial joint following primary total knee arthroplasty (pTKA) due to increased proprioception and more native knee kinematics. Therefore, the purpose of this study was to investigate whether cruciate-retaining (CR) or posterior-stabilized (PS) implants influence the Forgotten Joint Score (FJS-12) following pTKA. We retrospectively reviewed all patients who underwent pTKA with a CR or PS implant at our institute between October 2017 and March 2021. Of the 6,258 patients identified, 5,587 did not have recorded FJS-12 scores at either three months, one year, or two years postoperatively nor a Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) preoperatively, three months, or one year postoperatively, and these were considered lost to follow up. Thus, a total of 671 cases were identified and subsequently stratified into two cohorts based on whether they received a CR (n=236, 35%) or PS (n=435, 65%) implant. Patients who received PS implants were further divided into constrained (CoN) and non-constrained (NCoN) liner cohorts. Multivariable linear regression analysis was used to compare patient-reported outcome (PRO) scores. There were no significant differences in PRO scores between CR and PS implants at any time point. Patients in the CoN (n=74) cohort had significantly higher FJS-12 scores at one year (CoN: 56.31 + 25.34 vs NCoN: 42.24 + 27.00, p=0.001) and two years (CoN: 58.52 + 33.71 vs NCoN: 46.97 + 27.44, p=0.013) postoperatively compared to patients in the NCoN (n=361) cohort. Although our analysis demonstrated significant differences in FJS-12 scores at one and two years postoperatively depending upon the liner constraint, there were no significant differences in FJS-12 scores between CR and PS implants. Therefore, while retention of the PCL does not impact patient awareness of their artificial joint, the level of liner constraint may influence outcomes if the PCL is sacrificed.

Early outcomes of ultra-congruent insert in cruciate-retaining total knee arthroplasty: A prospective study

Introduction: The exponents of cruciate-retaining (CR) total knee arthroplasty (TKA) assert that the retention of posterior cruciate ligament (PCL) preserves more normal knee kinematics, femoral rollback on the tibia during flexion, greater stabilization of the prosthesis, and improved position sense as compared to PCL resection TKA. However, one has to shift to the posterior stabilized (PS) femoral component with box and accompanying cam postpolyethylene, especially in cases where PCL is too attenuated to be functional or too tight predisposing to accelerated polyethylene wear. To minimize both the cam mechanism polyethylene wear and the bone sacrifice due to the intercondylar box cut, the ultra-congruent (UC) inserts have been developed that are characterized by a high anterior wall and a deep-dished plate, promising good stability without cam mechanism. Materials and Methods: We did a prospective study to clinically evaluate the short-term results of the patients who underwent TKA using cemented posterior CR implants and UC inserts. PCL was required to be released either partially or completely in all the study patients. Thirty patients were evaluated preoperatively and postoperatively after 12 months with the new Knee Society Knee Scoring System (2011) and the findings were statistically analyzed. Results: There was a statistically significant postoperative improvement in flexion (from mean of 87.69° to 111.53°, P = 0.000), objective knee indicators (33.53 ± 8.51–70.84 ± 4.91, P = 0.000), patient satisfaction scores (7.48 ± 2.12–21.53 ± 4.26, P = 0.000), and the functional activities score (32.53 ± 5.12–69.02 ± 6.36, P = 0.000). We did not note any disadvantage of CR TKA with UC insert and no patient underwent an early revision for instability. Conclusion: Using UC insert in CR TKA is a reliable procedure that has decreased the dependence on the PS designs.

More passive internal tibial rotation with posterior cruciate ligament retention than with excision in a medial pivot TKA implanted with unrestricted caliper verified kinematic alignment

PurposeExcision of the posterior cruciate ligament (PCL) is recommended when implanting a medial pivot (MP) total knee arthroplasty (TKA) to reduce the risk of limiting flexion by over-tensioning the flexion space. The present study determined whether PCL retention (1) limits internal tibial rotation and (2) causes anterior lift-off of the insert in 90° flexion after implantation of an MP design with unrestricted caliper verified kinematic alignment (KA).MethodsFour surgeons implanted an MP TKA design with medial ball-in-socket and lateral flat tibial insert in ten fresh-frozen cadaveric knees. Before and after PCL excision, trial inserts with medial goniometric markings measured the angular I–E tibial orientation relative to the trial femoral component's medial condyle in extension and at 90° flexion, and the surgeon recorded the occurrence of anterior lift-off of the insert at 90° flexion.ResultsPCL retention resulted in greater internal tibial rotation than PCL excision, with mean values of 15° vs 7° degrees from maximum extension to 90° flexion, respectively (p < 0.0007). At 90° flexion, no TKAs with PCL retention and one TKA with PCL excision had anterior lift-off of the insert (N.S.).ConclusionsThis preliminary study of ten cadaveric knees showed that PCL retention restored more passive internal tibial rotation than PCL excision with a negligible risk of anterior lift-off. However, in vivo analysis from multiple authors with a larger sample size is required to recommend PCL retention with an MP TKA design implanted with unrestricted caliper verified KA.