Posterior-stabilized Group Research Articles

Muscle Activity and Biomechanics While Descending a Staircase After Total Knee Arthroplasty: A Study Comparing Different Posterior Stabilized and Medial Ball-and-Socket Designs

BackgroundMany patients report more difficulty when descending stairs compared to level walking after total knee arthroplasty (TKA). Different implant designs can affect knee biomechanics and muscle activity during gait, but their effect during stair descent is unclear. The purpose of this study was to evaluate knee biomechanics and muscle activations of quadriceps, hamstrings, and gastrocnemius muscles during a stair descent task in patients who underwent TKA with either a posterior stabilized (PS) or medial ball-and-socket (MBS) implant and to compare them to a group of healthy controls. MethodsThere were 28 TKA patients who were randomized to either an MBS (n = 14) or PS (n = 14) implant and were compared with 14 controls. Patients visited the biomechanics lab approximately 12 months after TKA, where knee biomechanics and muscle activity were measured as they descended a 3-step staircase. ResultsCompared to the MBS and control groups, the PS group descended the stairs with a reduced knee flexion angle and greater hamstring muscle activation throughout single limb support. Knee joint moments and power were similar between the MBS and PS groups, but neither reached the level of the control group. ConclusionsLower knee flexion angles and increased hamstring muscle activity indicated that the PS group descended the stairs with a stiffer knee gait pattern than the MBS group. The MBS implant design may provide additional stability as patients require less muscle activity than the PS group.

Cruciate-retaining Arthroplasty in Patients with Severe Varus Deformity: A Retrospective Comparative Study

Introduction: There has been debate regarding the advantages of cruciate-retaining over posterior stabilized (PS) knee arthroplasty and vice versa. Many authors consider any coronal plane deformity >15° as a contraindication for cruciate-retaining total knee arthroplasty. We aimed to compare whether functional outcome, deformity correction, and survivorship of cruciate retaining knee arthroplasty (CR) for severe varus deformity are equivalent to that of posterior cruciate ligament substituting (PS) for 6 years. Materials and Methods: We conducted a retrospective comparative study among patients who underwent Total Knee Replacement in the Orthopedics Department of a tertiary care hospital between 2016 and 2018 August who had a varus deformity of more than 15°. The first author exclusively performed CR operation (Group A) for all complex knees. In contrast, the second author performed PS surgery (Group B) for any coronal plane deformity over 15°. Clinical evaluation included completing a Knee Society Score (KSS) Evaluation Form. Pre-operative scoring was collected from the hospital database. All clinical examinations and radiographs at the final follow-up were done by the third author, who was unbiased and not involved with the initial patient care. Results: There were 39 patients in Group A (CR) and 28 patients in Group B (PS). In Group A, the mean pre-operative varus was 22.05 ± 2.72° and the pre-operative KSS was 32.94 ± 6.79. Postoperatively, the deformity corrected to a mean valgus of 5.48 ± 1.8° and mean KSS of 89.17 ± 5.79. In Group B, the mean pre-operative varus was 22.14±3.82° and pre-operative KSS was 32.82 ± 5.98. Postoperatively, the deformity corrected to a mean valgus of 4.85 ± 2.1° and mean KSS of 90.17 ± 5.13. The mean insert thickness was 11.76 ± 1.75 mm and 11.42 ± 1.75mm among the CR and PS groups, respectively. Concerning deformity correction (P = 0.19) and functional outcome (P = 0.46), both groups showed equal improvement with a 100% survival rate for 6 years. Conclusion: We concluded that CR knee replacements are possible with excellent functional and radiological outcomes in severe varus arthritic knees with a 100 % survival rate. Keywords: Arthritis, total knee arthroplasty, cruciate retaining, posterior stabilizing, varus deformity.

Clinical and Biomechanical Evaluation of Mid-Level Constrained and Posterior-Stabilized Polyethylene Inserts in Primary Total Knee Arthroplasty: An Analysis of 12,674 Cases

BackgroundMid-level constraint polyethylene designs provide additional stability in total knee arthroplasty (TKA). The purposes of this study were to (1) compare the survivorship and reason for revision between mid-level inserts and posterior-stabilized (PS) used in primary TKA and (2) evaluate the biomechanical constraint characteristics of mid-level inserts. MethodsWe reviewed all cases of primary TKA performed at our institution from 2016 to 2019 using either PS or mid-level constrained inserts from 1 of 6 manufacturers. Data elements included patient demographics, implants, reasons for revision, and whether a manipulation under anesthesia was performed. We performed finite element analyses to quantify the varus/valgus and axial-rotation constraint of each mid-level constrained insert. A one-to-one propensity score matching was conducted between the patients with mid-level and PS inserts to match for variables, which yielded 2 cohorts of 3,479 patients. ResultsFor 9,163 PS and 3,511 mid-level TKAs, survivorship free from all-cause revision was estimated up to 5 years and was lower for mid-level than PS inserts (92.7 versus 94.1%, respectively, P = .004). When comparing each company’s mid-level insert to the same manufacturer’s PS insert, we found no differences in all-cause revision rates (P ≥ .91) or revisions for mechanical problems (P ≥ .97). Using propensity score matching between mid-level and PS groups, no significant differences were found in rates of manipulation under anesthesia (P = .72), all-cause revision (P = .12), revision for aseptic loosening (P = .07), and revision for instability (P = .45). Finite element modeling demonstrated a range in varus/valgus constraint from ±1.1 to >5°, and a range in axial-rotation constraint from ±1.5 to ±11.5° among mid-level inserts. ConclusionsDespite wide biomechanical variations in varus/valgus and axial-rotation constraint, we found minimal differences in early survivorship rates between PS and mid-level constrained knees.

Preserving primary medial static stabilizer ligaments achieves physiological knee kinematics in total knee arthroplasty

PurposeAs postoperative knee instability has been reported to be one of the critical reasons for early failure in total knee arthroplasty (TKA), obtaining optimal knee stability—especially in medial—was indispensable for successful TKA. We hypothesized that preserving medial soft tissue structures was the key to maintain physiological medial knee stability. Thus, TKAs with preserving primary medial static stabilizer ligaments technique were performed, and the postoperative knee kinematics was evaluated. MethodsPrimary knee osteoarthritis patients with varus knee deformity and planed for primary TKA were enrolled. However, patients with severe varus knee deformities, valgus knee deformities, and rheumatoid arthritis were excluded. TKAs were performed by removing medial femoral and tibial osteophytes; however, the primary medial static stabilizer ligaments—the superficial medial collateral ligament (MCL), deep MCL, and posterior oblique ligament—were not released. The cruciate-retaining (CR), posterior-stabilized (PS), and medial-pivot (MP) inserts were implanted, and the knee kinematics was measured. These data were statistically analyzed using analysis of variance. The institutional review board approved the study. ResultsFrom full extension to maximum flexion, the lateral femoral condyle moved backward, greater than the medial femoral condyle, and consequently the femur external rotated on the tibia. These kinematics patterns were shown in CR, PS, and MP groups. ConclusionAs the knee kinematics of CR and PS are similar to that of MP, which has been reported to demonstrate physiological knee kinematics, preserving primary medial static stabilizer ligaments technique could potentially preserve physiological knee kinematics.

L’efficacité de la conservation du ligament croisé postérieur versus la stabilisation postérieure sur les fonctions du genou et de l’appareil extenseur chez les patients après une arthroplastie totale bilatérale simultanée du genou : une étude de suivi rétrospective de deux ans

IntroductionThe importance of the posterior cruciate ligament in knee functionality is known; however, the effect of preserving the posterior cruciate ligament in total knee arthroplasty (TKA) on extensor mechanism function and knee function is not clear. We aimed to compare extensor mechanism function and knee function between patients operated with the cruciate-retaining and posterior-stabilized designs for simultaneous bilateral TKA. HypothesisPatients operated with the cruciate-retaining design would produce better outcomes than those operated with the posterior-stabilized design. Materials and methodsA total of 104 patients were divided into two groups as the cruciate-retaining (n=52) and posterior-stabilized (n=52) groups. The groups were compared for extensor mechanism function (chair-rise test) and knee function (Hospital for Special Surgery [HSS] knee score). The follow-up points were six weeks, three months, six months, one year, and two years. ResultsNo statistically significant effect on chair-rise performance of the group-by-time interaction (χ2 [5,N=104]=5.32, p=0.37) or of group (χ2 [1,N=104]=1.69, p=0.19). In the HSS knee score, the group-by-time interaction was statistically significant (F [5,510]=6.24, p<0.001). A statistically significant difference of 7.4 points in favor of the posterior-stabilized group was found at six weeks (p=0.002). No statistically significant differences were found between the groups at the other follow-up points. DiscussionThe cruciate-retaining and posterior-stabilized designs have similar outcomes with regard to extensor mechanism function and knee function in the long-term period in patients who underwent simultaneous bilateral TKA. In the short-term period, the posterior-stabilized design shows better knee function than the cruciate-retaining design. Level of evidenceIII; a retrospective study.

The effectiveness of cruciate-retaining versus posterior-stabilized designs on extensor mechanism function and knee function in patients after simultaneous bilateral total knee arthroplasty: A two-year retrospective follow-up study

IntroductionThe importance of the posterior-cruciate ligament in knee functionality is known; however, the effect of preserving the posterior-cruciate ligament in total knee arthroplasty (TKA) on extensor mechanism function and knee function is not clear. We aimed to compare extensor mechanism function and knee function between patients operated with the cruciate-retaining and posterior-stabilized designs for simultaneous bilateral TKA. HypothesisPatients operated with the cruciate-retaining design would produce better outcomes than those operated with the posterior-stabilized design. Materials and methodsA total of 104 patients were divided into two groups as the cruciate-retaining (n=52) and posterior-stabilized (n=52) groups. The groups were compared for extensor mechanism function (chair-rise test) and knee function (Hospital for Special Surgery [HSS] knee score). The follow-up points were six weeks, three months, six months, one year and two years. ResultsNo statistically significant effect on chair-rise performance of the group-by-time interaction (χ2 [5, n=104]=5.32, p=.37) or of group (χ2 [1, n=104]=1.69, p=.19). In the HSS knee score, the group-by-time interaction was statistically significant (F [5.510]=6.24, p<.001). A statistically significant difference of 7.4 points in favor of the posterior-stabilized group was found at six weeks (p=.002). No statistically significant differences were found between the groups at the other follow-up points. DiscussionThe cruciate-retaining and posterior-stabilized designs have similar outcomes with regard to extensor mechanism function and knee function in the long-term period in patients who underwent simultaneous bilateral TKA. In the short-term period, the posterior-stabilized design shows better knee function than the cruciate-retaining design. Level of evidenceIII; a retrospective study.

A Comparative Study of Clinical Outcomes Between Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty: A Propensity Score-Matched Cohort Study.

We investigated a comparison of clinical outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty. However, it is still controversial which design leads to better clinical results. In clinical settings, choosing either CR or PS is likely based on the surgeon's preferences. In this study, short-term clinical outcomes between CR and PS in patients who received a single knee prosthesis were compared using propensity score matching. Two hundred and twelve CR and 43 PS of a single knee prosthesis were enrolled in this study. After propensity score matching, 34 knees each in the CR and PS groups were chosen and were without significant differences in age at operation, gender, BMI, preoperative range of motion (ROM), preoperative femorotibial angle (FTA), and presence or absence of patellar replacement. Clinical scores, including ROM, Knee Society score (KSS), knee injury and osteoarthritis outcome score (KOOS), except for the sports subscale, were compared between the CR and PS groups preoperatively and two years postoperatively. Postoperatively, there were no significant differences in FTA, ROM, or KSS. Preoperative scores for the KOOS except for the pain subscale were comparable between the groups. Postoperatively, however, the PS group had a significantly higher score in the ADL subscale compared to the CR group (PS: 89.5 vs. CR: 80.8,p= 0.017). The KOOS subscales other than activities of daily living (ADL) were comparable between the groups. In this propensity score-matched cohort study, PS showed a better outcome for the ADL than the CR design. These findings suggest that choosing either CR or PS should not depend on the surgeon's preferences. A PS design may be preferable to CR for elderly patients.

Comparison of ultra-congruent anterior-stabilized vs. a posterior cruciate substituting total knee arthroplasty for osteoarthritis with severe varus knee deformity: comparable 2 year outcomes with two design.

In this retrospective study, we compared the functionality and clinical outcomes of patients with severe varus knees who underwent total knee arthroplasty (TKA) that used prostheses with either a posterior stabilized (PS) design or an ultra-congruent (UC) design. Primary TKA was performed in 161 patients; the UC device was used in 82 (51%) cases and the PS device in 79 (49%). Preoperatively and at the final follow-up examination, all patients were evaluated by orthoroentgenography. The mechanical axis angle and radiolucent lines were evaluated according to the Knee Society Roentgenographic Evaluation System on preoperative and 5-year follow-up radiographs. Total Knee Society Score (KSS) (knee score/function score) and Visual Analog Scale scores were obtained at the final follow-up examination. Demographic and surgical data and revision rates were evaluated for all patients. Postoperative angle values were significantly decreased in both the UC and PS groups (p<0.001 and p<0.001, respectively). Postoperative flexion range of motion values were significantly increased in both the UC and PS groups (p<0.001 and p<0.001, respectively). The postoperative KSS function scores were not significantly different between the groups (p=0.194). The mean surgical time of the PS group (54.99±4.18 minutes) was significantly higher than that of the UC group (46.02±4.48 minutes) (p<0.001). No notable differences were found between the UC and PS groups with respect to the clinical and functional parameters examined. Based on these results, UC TKA can be considered a safe alternative to PS TKA in severe varus knees.

The clinical results of bi-cruciate vs posterior stabilized total knee arthroplasty for flexion contracture in osteoarthritic knee.

The improvement of flexion contracture is important in knee arthroplasty since residual flexion contracture postoperatively is associated with decreased quality of life and patient satisfaction. In this study, we investigated the effect of bi-cruciate stabilized (BCS)-type total knee arthroplasty (TKA) as compared to posterior stabilized (PS)-type TKA on osteoarthritic primary knees with flexion contractures. 59 TKAs from January 2014 to December 2020, of which 30 were PS-type TKAs (NexGen LPS-flexⓇ; 76.3years, BMI 27.5) and 29 BCS-type TKAs (Journey IIⓇ; 72.5years, BMI 28.6), were performed for knee osteoarthritis with preoperative flexion contracture of 15° or greater. Full extension was obtained intraoperatively during all TKAs. Clinical outcomes, radiological evaluations, and the amount of additional distal femoral osteotomy during TKA were evaluated in a retrospective study design. The range of motion improved in the both groups. Postoperative flexion contracture was significantly improved in the BCS group. Knee Society Score improved significantly in both groups, with no difference between the two groups. The amount of additional distal femoral osteotomy was 2.5 ± 1.3mm for the PS group, and 1.8 ± 1.5mm for the BCS group, showing a significant difference (p = 0.04). The BCS-type TKA significantly improved preoperative flexion contracture and reduced the amount of additional distal femoral osteotomy compared to PS-type TKA. This is attributed to the anterior cam in the BCS-type TKA, which leads to a smaller amount of protrusion of the posterior femoral condyle from the posterior margin of the tibial component in the BCS-type in knee extension, as compared to the PS-type.

Better Flexion but Unaffected Satisfaction After Treatment With Posterior Stabilized Versus Cruciate Retaining Total Knee Arthroplasty – 2-year Results of a Prospective, Randomized Trial

BackgroundBoth the cruciate-retaining (CR) and posterior-stabilized (PS) implant systems are commonplace in modern total knee arthroplasty (TKA) practice. However, there is controversy regarding functional outcomes and survivorship. The aim of the underlying study was to evaluate differences between CR and PS TKA regarding knee function, patient-reported outcome measures (PROMs) as well as complication rates. Methods140 patients with knee osteoarthritis scheduled for an unconstrained TKA were enrolled in a prospective, randomized study. Patients received either a CR or PS implant. Range of motion and PROMs (Oxford Knee Score, Knee Society Score, European Quality of Life 5 Dimensions 3 Level, University of California Los Angeles Activity scale and subjective satisfaction) were assessed prior to, 3 months, 1 and 2 years after surgery. ResultsWe found minor differences between treatment groups regarding demographic factors. Within the PS group duration of surgery was longer (mean PS 81.4 min vs CR 76.0 min, P = .006). We observed better flexion (median PS 120.0° vs CR 115°, P = .017) and an overall better range of motion (median PS 120.0° vs CR 115.0°, P = .008) for the PS group. PROMs did not differ between groups. At 2-year follow-up there were no revisions in either cohort. Five patients needed reoperations. Three patients needed manipulation under anesthesia, 2 in the CR and one in the PS group. ConclusionWhile PS TKA achieved a better flexion capability, PROMs were similar in CR and PS TKA. The CR implant design continues to be a reliable option for patients with an intact posterior cruciate ligament.

Inserting the best knee: A short-term analysis of posterior stabilized versus cruciate substituting ultracongruent tibial inserts for total knee replacement

Objectives: As the posterior cruciate ligament is a primary stabilizer of the knee, it is functionally replaced using posterior stabilized (PS) or anterior stabilized ultracongruent (UC) inserts in cases where it is attenuated or requires resection. This study compared PS and UC inserts in terms of functional and pain scores in patients undergoing total knee replacement (TKR). Methods: This prospective randomized study included 90 consecutive patients who underwent total TKR; PS and UC inserts were used in 47 and 43 patients, respectively. Outcomes were measured over 1 year. The duration of surgery was recorded, and the pain was assessed using the Visual Analog Scale score; functional outcomes were evaluated by assessment of the range of motion (ROM), Knee Society Score, and joint stability. All parameters and scores were assessed pre-operatively, immediately post-operative, 1 month, 3 months, and at 1-year follow-up. Results: The groups showed no significant differences and matched similarly in terms of body mass index, sex, or age. At a minimum of 1-year follow-up, TKR using either insert significantly improved the mean ROM and Knee Society and functional scores, which were comparable between the groups. Overall, 14 and 13 patients with UC and PS inserts, respectively, had excellent outcomes; 2 and 1 patients from the PS and UC groups, respectively, were lost to follow-up. Surgery was significantly shorter in the UC group. Although the Visual Analog Scale score had reduced significantly in both groups at the end of 3 months, one patient from the PS group had persistent knee pain with decreased ROM. Conclusion: The inserts showed no significant differences in terms of the ROM and Knee Society and functional scores. Surgery was notably shorter in the UC group (by 5 min). TKR using UC inserts is an effective alternative in patients with small bony geometry and may preserve intercondylar bone.

Varus osteotomy as a salvage procedure for young patients with symptomatic patellofemoral arthritis and valgus malalignment at short- to mid-term follow-up

Constrained primary total knee arthroplasty (TKA) can provide stability in the face of incompetent collateral structures or irreconcilable flexion–extension imbalances. However, little is known about its effect on overall knee range of motion (ROM). This study determines whether TKA with increased constraint affects postoperative ROM.Patients undergoing primary TKA using either posterior stabilized (PS) or constrained condylar knee (CCK) inserts were match-paired based on body mass index, preoperative ROM, and direction and severity of the coronal deformity, yielding 68 pairs. ROM and Knee Society Score (KSS) were obtained preoperatively and at 6 weeks, 4 months, and 1 year.When the 68 matched pairs were considered, all outcome variables related to ROM between the PS and CCK groups at each of the postoperative intervals were similar. Additionally, both the individual items and combined scores of the KSS were similar between groups at all time points.We demonstrate that the use of increased constraint does not affect ROM, relief of pain, or function after TKA.Level III (retrospective case-controlled study, based on prospectively collected data).

Midterm clinical results of bi-cruciate stabilized total knee arthroplasty compared with posterior stabilized total knee arthroplasty with single radius design

PurposeAttempts have been made to enhance knee prostheses design to improve clinical outcomes including bi-cruciate stabilized (BCS) TKA design and single-radius (SR) femoral component design. The complication rate of first generation BCS (fBCS) TKA was higher than that of standard TKA. Regarding BCS TKA, modification of the fBCS TKA system to the second-generation BCS (sBCS) TKA system was performed to avoid complications. This study aimed to compare the midterm clinical results of sBCS TKA and SR TKA. MethodsWe retrospectively reviewed data from TKA patients. A total of 142 patients who were followed up for at least 5 years were enrolled: 61 TKAs using sBCS and 81 TKAs using the posterior stabilized (PS) single-radius (SR) design. The clinical results at 6 months, 2 years, and 5 years postoperatively were compared between the sBCS and SR PS groups. ResultsAt 6 months postoperatively, the maximum flexion angle (MFA) of the sBCS group was larger than that of the SR PS group. At 2 years, MFA, KOOS subscales of pain and ADL in the sBCS group were better and at 5 years, the MFA, KOOS subscales of pain and QOL in the sBCS group were better than those in the SR group. There was no significant differences of the ratios of complications and revision surgeries between the two groups. ConclusionThe midterm clinical results of sBCS TKA were better than those of SR PS TKA in terms of the MFA and KOOS subscales of pain and QOL.

Larger Medial Contact Area and More Anterior Contact Position in Medial-Pivot than Posterior-Stabilized Total Knee Arthroplasty during In-Vivo Lunge Activity

This study aimed to compare the in-vivo kinematics and articular contact status between medial-pivot total knee arthroplasty (MP-TKA) and posterior stabilized (PS) TKA during weight-bearing single-leg lunge. 16 MP-TKA and 12 PS-TKA patients performed bilateral single-leg lunges under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The closest point between the surface models of the femoral condyle and the polyethylene insert was used to determine the contact position and area. The nonparametric statistics analysis was performed to test the symmetry of the kinematics between MP-TKA and PS-TKA. PS-TKA demonstrated a significantly greater range of AP translation than MP-TKA during high flexion (p = 0.0002). Both groups showed a significantly greater range of lateral compartment posterior translation with medial pivot rotation. The contact points of PS-TKA were located significantly more posterior than MP-TKA in both medial (10°-100°) and lateral (5°-40°, 55°-100°) compartments (p < 0.0500). MP-TKA had a significantly larger contact area in the medial compartment than in the lateral compartment. In contrast, no significant differences were observed in PS-TKA. The present study revealed no significant differences in clinical outcomes between the MP and PS groups. The PS-TKA demonstrated significantly more posterior translations than MP-TKA at high flexion. The contact points are located more posteriorly in PS-TKA compared with MP-TKA. A larger contact area and medial pivot pattern during high flexion in MP-TKA indicated that MP-TKA provides enhanced medial pivot rotation.

Comparison of the in-vivo kinematics of three different knee prosthesis designs during a step-up movement

BackgroundThere is no consensus on the importance of the kinematics of the prosthetic joint for the clinical outcome after total knee arthroplasty. A 3-armed randomized controlled trial was done to determine and compare the in vivo kinematics of a posterior cruciate-retaining and two posterior cruciate-sacrificing (Anterior-Stabilized and Posterior-Stabilized) prosthetic designs from the same total knee arthroplasty system. Since the anterior-stabilized and posterior-stabilized designs are posterior cruciate ligament-sacrificing designs, we hypothesized they would have similar contact-point kinematics. Further, we hypothesized that the cruciate-retaining design would have contact-point kinematics different from the anterior-stabilized and the posterior-stabilized designs, but comparable to a native knee. MethodsThirty-nine patients with a well-functioning total knee arthroplasty one year postoperatively underwent kinematic analysis of a weight-bearing step-up movement under fluoroscopic recording. Model-based radiostereometric analysis was used to determine anteroposterior contact-point translations and rotations through the movement path to assess knee kinematics. FindingsThe cruciate-retaining and anterior-stabilized groups' medial and lateral contact-points displayed similar paradoxical posterior translations during step-up in the magnitude of 7 and 2 mm, respectively. In contrast, the posterior-stabilized group's contact-points translated anteriorly by 4 and 10 mm throughout the movement and were significantly more posterior than the cruciate-retaining and the anterior-stabilized groups from >100° to 40° of flexion. The femur rotated internally with all designs. InterpretationThe cruciate-retaining and anterior-stabilized designs displayed similar contact-point translation patterns during a step-up movement. Only the posterior-stabilized design showed a pattern comparable to native knees. Conversion from a cruciate-retaining to an anterior-stabilized design because of posterior cruciate ligament insufficiency will not change knee kinematics.

What's New in Adult Reconstructive Knee Surgery.

What's New in Adult Reconstructive Knee Surgery.

Bicruciate-retaining total knee arthroplasty non-inferior to posterior-stabilized prostheses after 5years: a randomized, controlled trial.

Bicruciate-retaining (BCR) prostheses may improve satisfaction of patient undergoing total knee arthroplasty (TKA). The objective of this randomized controlled trial was to assess whether BCR prostheses provide better clinical outcomes than posterior-stabilized (PS) prostheses. This is a randomized single-blind control trial involving a total of 77 patients with knee osteoarthritis, randomly assigned to undergo TKA with a BCR or PS implant between 2015 and 2019. Mean follow-up period was 39months. Clinical and demographic data were extracted manually from medical records. Data acquisition included patient demographics, knee range of motion, and patient-reported outcomes via KSS, KOOS, WOMAC, and SF-12 scores. A total of 38 patients were randomized to the PS group and 39 to the BCR group. At the 5-year follow-up, no statistical differences were noted for knee range of motion or patient-reported outcomes between the two groups, except for a greater knee flexion in the early follow-up period in the PS group. Five adverse events occurred in the BCR group compared to none in the PS group (p = 0.02). BCR TKA yield similar clinical and patient-reported outcomes 5 years following the intervention compared with PS TKA. The BCR TKA had more complications. I (Randomized Controlled Trial).

A prospective comparison of total knee arthroplasty using ultra-congruent, condylar-stabilizing, and posterior-stabilized devices implanted with kinematic alignment: better 2-year outcomes with ultra-congruent

PurposeThis study compared the 5-year results of posterior cruciate ligament (PCL)-sacrificing total knee arthroplasty (TKA) with either a post and cam posterior-stabilized (PS) device, a dished, congruent condylar-stabilizing (CS) device, or a deep-dished ultra-congruent (UC) device. The hypothesis was that the clinical and radiographic outcomes would be equivalent. CS and PS participants were part of a prospective, randomized trial, and UC participants were part of a separate prospective, non-randomized protocol that was otherwise identical. A kinematic alignment surgical technique was utilized.MethodsParticipants were assessed preoperatively, and postoperatively at 6 weeks, 6 months, and annually for 5 years by Knee Society Score (KSS), SF-36 v2, Lower Extremity Activity Scale (LEAS), and physical and radiographic evaluation. There were 116 CS/PS participants and 69 UC participants who participated in the study.ResultsTourniquet (P = .02) and operative (P = .01) times for the CS and UC groups were significantly shorter than the PS group. KSS Function scores were better for the UC group than the CS and PS groups at 6 months (P = .04) and 1 year (P = .03), and better in the UC group vs. CS at 2 years (P = .04). The KSS Pain-only score was also better in the UC compared to PS at 6 months (P = .04). There were no significant differences for the KSS Pain/Motion scores, flexion, SF-36, and LEAS scores at any time.ConclusionThese data confirm the hypothesis that there are no clinically meaningful significant differences in outcomes between the three groups at a 5-year minimum follow-up, though there is a trend toward less pain and better function at earlier visits in the UC group.Level of evidenceII.

Octogenarians Are the New Sexagenarians: Cruciate-Retaining Total Knee Arthroplasty Is Not Inferior to Posterior-Stabilized Arthroplasty in Octogenarian Patients.

Purpose: The primary goal of this study was to compare survivorship and functional results in individuals aged 80 and over who underwent total knee arthroplasty (TKA) with cruciate-retaining (CR) or posterior-stabilized (PS) implants. Methods: We prospectively analyzed the clinical records of two consecutive cohorts for a total of 96 implants in patients aged 80 years or over. The first cohort consisted of 59 consecutive cemented PS cases, while the second cohort comprised 37 consecutive cemented CR cases. The decision to either perform a PS or CR arthroplasty was taken based on preoperative magnetic resonance imaging and intraoperative findings. The clinical evaluation entailed evaluating each patient’s visual analogue scale for pain (VAS), range of motion (flexion and extension), Knee Society Score (KSS), and Oxford Knee Score (OKS). Each patient was clinically evaluated the day before surgery (T0) and at two consecutive follow-ups at least 1 (T1) and 2 (T2) years after surgery. Implant survival was calculated using the Kaplan–Meier method. Results: Both groups showed statistically significant improvements at each follow-up compared with the preoperative values (p < 0.05). The CR group showed a higher flexion degree at T1 than the PS group (116.14 ± 5.57° versus 113.16 ± 7.66°; p = 0.048). No differences were found between the two groups regarding survival rate (chi-squared test p-value = 0.789). Three failures were noted in the CR group, while there were four in the PS group. Conclusions: This prospective clinical study demonstrates that CR and PS TKA had similar clinical outcomes in octogenarians with regard to knee function, postoperative knee pain, and other complications. Prosthesis survivorship for CR and PS TKA were both satisfactory, and in selected octogenarian patients, CR TKA should always be considered because of the reduced surgical time.

Posterior stabilized total knee arthroplasty increases the risk of postoperative periprosthetic fractures

Background The Insall-Burstein posterior-stabilized knee design was first developed in 1978 by adding a central cam mechanism to the articular surface geometry of the total condylar prosthesis to correct its problems being not “rolling back”. Since then, the use of posterior-stabilized (PS) implants in total knee arthroplasty (TKA) is becoming increasingly popular. However, one of the main disadvantages of PS designs is related to the amount of bone removed during femoral box osteotomy to create the housing of the PS mechanism, the clinical value of removing more or less bone during primary TKA remains to be fully established. The objective of this study was to compare the incidence of early postoperative periprosthetic fractures in the cruciate retaining (CR) and posterior stabilized (PS) knee prosthesis. Methods An institutional high volume arthroplasty unit database was reviewed to identify all patients who sustained a postoperative periprosthetic fracture following primary TKA between January 2014 and May 2018. A retrospective chart review was performed to collect clinical, radiographic, and operative report data. A total of 352 patients with 600 primary TKAs were identified. (300 cases of cruciate retaining TKAs from 178 patients and 300 cases of posterior stabilized TKAs from 174 patients) were retrospectively reviewed. Results Eleven patients (1.83%) sustained periprosthetic fractures in the postoperative setting following primary TKA. All of the fractures were located on the femur and were treated surgically. Only one knee (one patient) from the CR group sustained a periprosthetic fracture, while 10 knees (from 10 patients) from the PS group sustained a fracture. The relative risk of sustaining a fracture in the CR group was 0.10 times relative to the PS group (RR = 0.10, 95% CI 0.0129 – 0.776). Conclusion Posterior stabilized total knee arthroplasties (TKAs) significantly increase the risk of periprosthetic fractures in obese Asian patients compared to cruciate retaining TKAs.