A Medial Congruent Polyethylene Offers Satisfactory Early Outcomes and Patient Satisfaction in Total Knee Arthroplasty

The Effect of the Design of Polyethylene Inserts in Total Knee Arthroplasty on Patient Reported Outcomes

INTRODUCTION

Several types of polyethylene liners have been developed to address the specific needs of patients' anatomy within total knee arthroplasty (TKA). In modern TKA, the posterior-stabilized (PS) and the cruciate-retaining (CR) designs are the most common, with the medial congruent (MC) design becoming more popular. The MC total knee arthroplasty has a posterior dwell point allowing for more flexion. The purpose of this study was to determine differences in patient-reported outcomes (PROMs) or postoperative outcomes between these three TKAs.

METHODS

Patients who underwent a primary, elective, unilateral TKA between June 2021 and July 2023 were identified. Demographics and perioperative and postoperative outcomes were extracted from the medical record. PROMs from 624 patients were obtained through a digital engagement platform. A P value ≤0.05 was considered statistically significant.

RESULTS

Patients were subdivided into three groups; 111 PS-TKA, 278 CR-TKA, and 235 MC-TKAs. Most implants were Zimmer (71.5%) and were cemented (92.9%). Patients in the CR group were predominantly male (P = 0.003) and had a lower body mass index (P < 0.001). No differences were seen in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores at any time point (preoperative: P = 0.073; 12 weeks: P = 0.144; 6 months: P = 0.666; 1 year: P = 0.622). A similar percentage of patients met the minimal clinically important difference (P = 0.480), and Forgotten Joint Scores were equivalent (P = 0.930). Patient physical therapy parameters (Timed Up and Go test [P = 0.779] and ambulation distance [P = 0.103]), inpatient pain levels (at rest: P = 0.101, with activity: P = 0.052), or morphine milligram equivalents dosed (P = 0.608) were comparable. No differences were seen in 30-day complications.

CONCLUSION

This study fails to demonstrate a difference in PROMs, functional parameters, or complications between the PS-TKAs, CR-TKAs, and MC-TKAs. All three constructs perform similarly in the immediate postoperative period. Because equivalent outcomes occur with each polyethylene, implant choice should be left to physician preference.

A Comparison of Medial-congruent, Ultracongruent, and Cruciate-retaining Bearings Using a Single Cruciate-retaining Total Knee Design

Background

Improving outcomes has driven advancements in total knee arthroplasty (TKA) bearing design. The aim of this study was to compare medial-congruent (MC), ultracongruent (UC), and cruciate-retaining (CR) TKA utilizing a single CR total knee system.

Methods

Six surgeons performed 2883 primary TKAs from 2012 to 2022 using the same implant design, comprised of 708 MC, 799 UC, and 1376 CR bearings. Prospectively collected data on clinical and patient-reported outcome measures were compared. Data analyses utilized analysis of variance tests for continuous data, chi-square tests for categorical data, and Mantel-Cox tests for survivorship analysis. MC subjects were older (MC = 67.5 vs UC = 65.3 vs CR = 66.7 years; P < .001), had lower body mass index (MC = 32.4 vs UC = 33.1 vs CR = 33.2 kg/m2; P = .04), and had shorter mean follow-up (MC = 1.2 vs UC = 2.4 vs CR = 2.9 years; P < .001).

Results

All groups experienced similar rates of 90-day complications (MC = 26/708, 3.7% vs UC = 39/799, 4.9% vs CR = 52/1376, 3.8%; P = .38) and revisions (MC = 1/708, 0.1% vs UC = 4/799, 0.5% vs CR = 5/1376, 0.4%; P = .49). Survivorship was similar at 2 years (P = .41) and above 98% at 5 years for all groups. At the 1-year follow-up, MC bearings had significantly greater Patient-Reported Outcomes Measurement Information System Global Health Physical (MC = 47.1 vs UC = 41.5 vs CR = 42.8; P < .001) and mental scores (MC = 48.9 vs UC = 41.3 vs CR = 43.7; P < .001).

Conclusions

No differences in all-cause complications or revisions were observed for MC, UC, and CR bearings using the same total knee system. Clinically important differences favoring MC bearings were found with Patient-Reported Outcomes Measurement Information System Global Health Physical scores at 1 year; however, longer follow-up is necessary to determine if this trend holds.

Complete and Selective Resection of the Posterior Cruciate Ligament Reduces Contact Forces Asymmetrically in Cruciate-Retaining Total Knee Arthroplasty: A Computational Study

BACKGROUND

Assessing intraoperative ligament balance in the posterior cruciate ligament (PCL)-retaining total knee arthroplasty (TKA) can be achieved by quantifying tibio-femoral contact forces. Ligament balancing may involve selectively releasing PCL fibers; however, the effects of the extent and location of PCL release on compartmental contact forces are not well understood. To investigate these effects, we developed a computational model to quantify changes in medial and lateral contact forces resulting from targeted PCL fiber release.

METHODS

Computational models of 10 cadaver knees (five men and five women with a mean age of 63 years) were virtually implanted with a cruciate-retaining TKA. Passive knee flexion was simulated under three PCL conditions: all PCL fibers retained, all PCL fibers resected, and only the central PCL fibers released. Tibio-femoral contact forces in the medial and lateral compartments at 90° of flexion were measured for each PCL condition.

RESULTS

Resecting the PCL resulted in a reduction of contact forces by a median of 24.2 N (P ≤ 0.01) medially and a median of 11.1 N (P ≤ 0.01) laterally. Selective release of only the central PCL fibers reduced medial and lateral contact forces by medians of 11.5 N (P ≤ 0.05) and 4.5 N (P ≤ 0.05), representing 47 and 50% of the reduction observed with complete PCL resection, respectively.

CONCLUSIONS

Resecting the PCL asymmetrically impacts compartmental contact forces, with a greater reduction observed in the medial compartment. Given the contribution of the releasing PCL's central portion to the reduction in compartmental contact forces, surgeons may consider first focusing on this region when conducting intraoperative releases to achieve ligament balance via PCL resection in cruciate-retaining TKA.

Simulated Partial and Complete Resection of the Posterior Cruciate Ligament in Medially Conforming Total Knee Arthroplasty Causes a Graded Reduction in Femoral Rollback and Increase in Posterior Tibial Sag: A Computational Study

BACKGROUND

Medially conforming (MC) total knee arthroplasty (TKA) has seen increased clinical utilization. This design allows for either retention or resection of the posterior cruciate ligament (PCL); however, the impact of the PCL on femoral rollback and posterior tibial sag is unknown. Therefore, we developed a computational model to quantify how the PCL affects femoral rollback and posterior sag in MC-TKA.

METHODS

Computational models of 10 cadaver knees were virtually implanted with MC-TKAs. Clinical tests of passive flexion and posterior sag were simulated, and femoral rollback and posterior tibial translation (PTT) were quantified. These tests were simulated in MC-TKA with the PCL retained, partially resected, and completely resected. We then assessed how increasing the tibial insert thickness in PCL-resected MC-TKA and switching to posterior-stabilized (PS)-TKA impacted posterior sag.

RESULTS

Femoral rollback decreased medially by a median of 2.4 mm (P ≤ 0.001) and laterally by a median of 3.3 mm (P ≤ 0.001) with simulated PCL resection. For the simulated sag test, PTT increased by a median of 4.2 (P ≤ 0.05) and 7.4 mm (P ≤ 0.001) with partial and complete PCL resection, respectively. Moreover, PTT was reduced by a median of 7.1 mm (P ≤ 0.01) when converting a PCL-resected MC-TKA to a PS-TKA.

CONCLUSIONS

In a computational model, MC-TKA does not fully compensate for the function of the PCL, which facilitates femoral rollback in passive flexion and resists PTT during a posterior sag test. Resecting the antero-lateral bundle, with preservation of the postero-medial bundle of the PCL, yields more femoral rollback and less PTT than complete PCL resection in MC-TKA. Increasing tibial insert thickness in MC-TKA also does not account for the role of the PCL in reducing PTT during a sag test, while a PS-TKA does.

No difference in clinical outcomes when retaining or sacrificing the posterior cruciate ligament in medial congruent total knee replacement. A retrospective study

PURPOSE

The aim of this study is to evaluate the effect of retaining or sacrificing the posterior cruciate ligament (PCL) in patients who undergo primary total knee replacement (TKR) with the medial congruent (MC) implant.

METHODS

This retrospective study looks at patients who underwent TKR with the MC implant. Comparison was made between the group with the PCL sacrificed (MC-PCLS) and the group with the PCL retained (MC-PCLR). Range of motion (ROM), Oxford knee score (OKS), Knee society knee score (KS-KS) and Knee society function score (KS-FS) were recorded.

RESULTS

The study identified 76 patients. 50 in the MC-PCLS group and 26 in the MC-PCLR group. Both groups had similar patient demographics. Three months postoperatively, OKS and KS-KS had significant improvement. However, there was significant improvement in KS-FS score in the MC-PCLS group but not the MC-PCLR group (MC-PCLR: 33 ± 17, p = 0.07; MC-PCLS: 19 ± 24, p = 0.01). Twelve months postoperatively, the OKS continued to improve significantly for both groups, while the KS-FS and KS-KS scores appeared to stagnate. The ROM continued to improve significantly for the MC-PCLR group but not the MC-PCLS group (MC-PCLR: 7 ± 9, p = 0.03; MC-PCLS: 4 ± 9, p = 0.30). Both groups were similar in ROM, OKS and KSS scores at both the 3 and 12 month post-operative period.

CONCLUSION

There is no difference in post-operative outcomes with the PCL retained or sacrificed. As such, surgeons can consider routinely sacrificing the PCL for easier balancing of the knee and shorter surgical time.

Ultracongruent Versus Posterior-Stabilized Polyethylene: No Difference in Anterior Knee Pain but Decreased Noise Generation

BACKGROUND

Noise generation and anterior knee pain can occur after primary total knee arthroplasty (TKA) and may affect patient satisfaction. Polyethylene design in cruciate-sacrificing implants could be a variable influencing these complications. The purpose of this study was to analyze the effect of polyethylene design on noise generation and anterior knee pain.

METHODS

We prospectively reviewed a cohort of patients who underwent primary TKA between 2014 and 2022 by a single surgeon using either a posterior-stabilized (PS) or ultracongruent (UC) polyethylene of the same implant design. The primary outcomes were measured through a noise generation questionnaire and the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score.

RESULTS

A total of 409 TKA procedures were included, 153 (37.4%) PS and 256 (62.6%) UC. No difference was noted in the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score between PS and UC designs (71.7 ± 26 versus 74.2 ± 23.2, P = 0.313). A higher percentage of patients in the PS cohort reported hearing (32.7% versus 22.3%, P = 0.020) or feeling noise (28.8 versus 20.3, P = 0.051) coming from their implant. No notable difference was observed in noise-related satisfaction rates. Independent risk factors of noise generation were age (OR, 0.96; P = 0.006) and PS polyethylene (OR, 1.61; P = 0.043). Noise generation was associated with decreased patient-reported outcome measure scores ( P < 0.001).

CONCLUSION

While there was no difference in anterior knee pain between PS and UC polyethylene designs, PS inserts exhibit higher rates of noise generation compared with UC. Noise generation had comparable satisfaction but was associated with decreased patient-reported outcome measure scores.

Survivorship and Patient Outcomes of Conforming Bearings in Modern Primary Total Knee Arthroplasty: Mean 3.5 Year Follow-Up

BACKGROUND

The use of conforming and congruent bearings in total knee arthroplasty (TKA) have rapidly increased due to the benefits of increased stability and the potential for replicating normal knee kinematics. However, limited data exist for these newly available bearings. This study evaluated revision-free survivorship and patient-reported outcome measures (PROMs) of a large granular database of primary TKAs using a single conforming bearing design.

METHODS

A total of 1,306 consecutive primary TKAs performed using a single conforming bearing design (85% cemented and 15% cementless) were retrospectively reviewed. Kaplan-Meier survivorship estimates were calculated based on the latest clinical follow-up. The PROMs and minimal clinically important differences were evaluated. A total of 93% of cases achieved minimum 1-year clinical follow-up (mean 3.5 years; range, 1 to 7), with a subset of 261 cases that achieved minimum 5-year follow-up (mean 5.8 years; range, 5 to 7).

RESULTS

All-cause and aseptic Kaplan-Meier survivorship estimates were 97.6 (95% CI [confidence interval], 97 to 99) and 98.1% (95% CI, 97 to 99) at 7.0 years. Revision-free survivorship did not differ by cemented or cementless fixation (98 versus 97%, P = .163). All PROM scores significantly improved from preoperative baseline (P < .001), and ≥ 86% of patients achieved minimal clinically important differences for Knee Society pain and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement total scores. A total of 89% of cases reported their knees to 'sometimes or always' feel normal. For cases with minimum 5-year PROMs, 93% were 'very satisfied' or 'satisfied.'

CONCLUSIONS

Conforming-bearing TKA demonstrated excellent survivorship up to 7.0 years. In addition, PROMs were comparable to other designs reported in the literature. While mid-term (mean 3.5-year) results are promising, long-term data are warranted on survivorship due to potential polyethylene wear in conforming bearings with more surface area in contact with articulating surfaces.

LEVEL OF EVIDENCE

IV.

Comparison of accuracy and early outcomes in robotic total knee arthroplasty using NAVIO and ROSA

This study aimed to compare the cutting and component placement accuracies and early outcomes after total knee arthroplasty (TKA) between an image-free handheld robotic system (NAVIO) and a radiography-based robotic system (ROSA). This retrospective study included 88 patients (88 knees) who underwent TKA using the NAVIO (40 patients) or ROSA (48 patients) robotic systems. The accuracies of the robotic systems were compared. Clinical scores were evaluated using the Knee Society Score 2011 (KSS 2011) and the forgotten joint score (FJS)-12 at 1 year postoperatively. The femoral sagittal cutting error was smaller in the NAVIO group than in the ROSA group. The other cutting errors were not statistically different in both groups. Implantation errors did not differ between the groups. Regarding the clinical outcomes of the KSS 2011 subscales, the symptoms score was higher in knees operated using ROSA than in those using NAVIO. The other KSS 2011 subscales and the FJS-12 showed no differences between the two groups. In conclusion, the femoral sagittal cutting error was smaller in the NAVIO group than in the ROSA group, and the KSS 2011 symptom score subsection at one year was higher in the knees operated using ROSA than in those using NAVIO.

PCL preservation or sacrifice does not influence clinical outcomes and survivorship at mid-term follow-up of a J-curve CR total knee replacement with a medial congruent liner and a functional coronal alignment

BACKGROUND

In recent years, increasing interest has arisen for medial pivoting TKA implants, designed to mimic the physiological knee kinematics, maximizing the contact area on the medial compartment of the knee, increasing anterior-posterior stability, and contributing to a ball-in-socket effect that allows the posterior cruciate sacrifice without a post-CAM mechanism. The medial congruent liner works with a J-curve cruciate-retaining (CR) femur without a real ball-in-socket design. The aim of this study was to evaluate the clinical outcomes and survival of these implants, with or without PCL sparing, at a medium follow-up.

METHODS

Between October 2016 and October 2018, 165 TKRs were performed in 161 patients (69.2% females and 30.8% males) and prospectively followed. Mean follow-up was 72 ± 12 months. All surgeries were performed using an extramedullary device and the same prosthetic implant. Patients were matched in two groups: in 80 patients, the PCL was preserved; in 85 patients, the PCL was sacrificed with a reduction of the tibial slope.

RESULTS

The OKS and KSS improved in both groups. The difference between the two groups at the final follow-up was not statistically significant. Good-to-excellent clinical results according to the KSS were achieved in 93% of the knees in the PCP group and in 95% in the PCS group. At final follow-up, the Forgotten Joint Score (FJS) was 73.6 in the PCP group and 74.1 in the PCS group with no statistical difference between the two groups (P > 0.05).

CONCLUSIONS

TKA with a medially congruent insert, showed promising results at mid-term follow-up, PCL preservation or sacrifice did not affect the clinical outcomes and survival. Further follow-up will be needed to evaluate these results at long term.

The Early Clinical Outcomes Following Unrestricted Caliper Verified Kinematic Alignment Using a Medial Stabilized Design Total Knee Arthroplasty With a Cruciate Retaining Insert

Background

Although various total knee arthroplasty (TKA) implant designs are widely used, the ideal TKA design is yet to be agreed upon. Although the benefits of cruciate-retaining (CR) TKA and medial stabilized (MS) TKA have been reported in literature, the early clinical outcomes of an MS TKA with CR inserts have not been reported. This study aims to report on the patient-reported clinical and radiological outcomes of MS-TKA combined with a CR insert.

Methods

A prospective single-surgeon series evaluated the clinical- and patient-reported outcomes of 115 patients implanted with GMK Sphere CR. Patient outcomes were assessed with the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Scores (KOOS), Forgotten Joint Score, and Visual Analogue Scale for Satisfaction. Radiological assessment for alignment along with active flexion and extension were also assessed.

Results

Improvement in all scores was observed between the preoperative and 1-year follow-up timepoints, with statistical significance seen for Oxford Knee Score as well as KOOS Symptoms, Pain, Sport, quality of life, and activities of daily living subscales. The mean active flexion between the preoperative and both postoperative timepoints at 6 months and 1 year was also statistically significant (P = .021 and P = .001).

Conclusions

MS-TKA with a CR insert can facilitate symptom relief and improve overall function of the knee after surgery. Both the patient and clinical outcomes were comparable to 1-year outcomes utilizing other MS-TKA designs and were superior to those at 1-year follow-up following implantation of CR-TKA. Most notability, the KOOS symptoms and sports score were higher for the MS-TKA with a CR insert than for an MS-TKA design.

Patient-reported outcomes measurement information system instruments in knee arthroplasty patients: a systematic review of the literature

BACKGROUND

The purpose of this study is to provide a systematic review of the literature pertaining to Patient-Reported Outcome Measurement Information System (PROMIS) validation and utilization as an outcomes metric in total knee arthroplasty (TKA) patients. This is the first systematic review on PROMIS use in total knee arthroplasty patients.

METHODS

A systematic search of the Pubmed/MEDLINE and Embase databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Study characteristics, patient demographics, psychometric properties (Pearson and Spearman correlation) with legacy patient-reported outcome measurement (PROM) instruments, floor and ceiling effects, responsiveness, and minimum clinically important difference (MCID) and PROMIS outcomes were recorded and analyzed.

RESULTS

Fifteen studies investigating PROMIS in 11,140 patients were included. The weighted-average Pearson correlation coefficient comparing PROMIS domains with legacy patient-reported outcome measurements in total knee arthroplasty patients was 0.62 [standard error (SE) = 0.06] and the weighted-average Spearman correlation comparing PROMIS domains with legacy patient-reported outcome measurements in total knee arthroplasty patients was 0.59 (SE = 0.06), demonstrating moderate-to-strong correlation and validity. There were no differences in weighted average floor [0.03% (SE = 3.1) versus 0% (SE = 0.1) versus 0.01% (SE = 1.1); p = 0.25] or ceiling effects [0.01% (SE = 0.7) versus 0.02% (SE = 1.4) versus 0.04% (SE = 3.5); p = 0.36] between PROMIS and legacy instruments. The weighted average for percentage of patients achieving MCID was 59.1% for global physical health (GPH), 26.0% for global mental health (GMH), 52.7% for physical function (PF), 67.2% for pain interference (PI), and 37.2% for depression.

CONCLUSION

Notably, PROMIS global physical health, physical function, and pain interference were found to be significantly responsive, with PROMIS pain interference most effectively capturing clinical improvement as evidenced by the achievement of MCID.

PCL retention demonstrates better functional scores and gait patterns in total knee arthroplasty using a medial congruent insert-a prospective study

PURPOSE

Despite Total Knee Arthroplasty (TKA) being one of the most successful procedures for end stage arthritis, nearly 20% of patients undergoing this procedure remain dissatisfied. Various design options have been introduced to reduce this cohort of patients. One such option has been the introduction of the medial congruent (MC) polyethylene design. This study was undertaken to evaluate outcome measures and gait analysis in patients undergoing bilateral single stage TKA where the posterior cruciate ligament (PCL) was retained or excised in contralateral knees.

METHODS

60 bilateral TKA's were performed by a single surgeon using a MC design option from July to Sep 2021. The study lots included patients between the ages of 55 and 70 years with fixed varus deformity of degenerative aetiology, and Kellgren Lawrence Grade 3 and 4 radiological changes. Exclusion criteria were previous surgery to the lower extremities, sero positive arthropathies, post traumatic arthritis, valgus deformity, flexion contractures > 20°, and any pre-existing pathology impacting gait, e.g., poliomyelitis, or neuromuscular disorders. The PCL was retained or sacrificed on contralateral sides for the purpose of this study. Functional scores, outcomes and gait analysis on level and gradient walking were evaluated at a follow-up of 18 months.

RESULTS

At 18, months the Range of Motion (ROM) improved from a preoperative value of 97.3 ± 11.5 to 110.3 ± 6.1 on the PCL retained side (MC-PCL) and from 96.5 ± 10.8 to 113 ± 5.8 on the PCL excised side (MC-PCLX). Knee Society Score (KSS-2011) improved from a preoperative value of 21.2 ± 4.5 to 89.8 ± 3.4 at 18 months postoperatively on the MC-PCL side and from 21.5 ± 4 to 88.2 ± 3.7 on the MC-PCLX side. Forgotten Joint Score (FJS-12) was 8.8 ± 0.7 on the MC-PCL side and 8.1 ± 0.9 on the MC-PCLX side 18 months after surgery. Our gait analysis evaluation demonstrated a lower forefoot pressure in the MC-PCL group in comparison to the MC-PCLX group when subjects were made to walk on a 30° upward incline. This difference was found to be statistically significant.

CONCLUSION

In this study, while ROM was greater in the MC-PCLX study lot, patient satisfaction was higher in the MC-PCL study lot. Gait assessment demonstrated lower forefoot pressure while ascending an incline of 30° in the MC-PCL study lot as compared to the MC-PCLX study lot approximating normal gait patterns.

LEVEL OF EVIDENCE

II.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

IV.

Personalized alignment™ for total knee arthroplasty using the ROSA® Knee and Persona® knee systems: Surgical technique

Total knee arthroplasty (TKA) procedures are expected to increase up to 565% in the United States over the next 3 decades. TKAs were traditionally performed with neutral mechanical alignments that provided equal medial and lateral gaps in extension and flexion to reduce implant wear but were less successful at restoring native knee function and associated with high patient dissatisfaction. Kinematic alignment (KA) restores native anatomy and minimizes soft tissue release; however, KAs that recreate severe deformities and/or biomechanically inferior alignments result in significant increases in implant stress and risk of aseptic loosening. Restricted kinematic alignment (rKA) recreates pre-arthritic anatomy within a range of acceptable alignment boundaries, and improved patient clinical scores and faster recoveries have been reported with rKA techniques. Personalized Alignment™ is an evolution of rKA that relies heavily upon robotic assistance to reliably recreate patient anatomy, native soft tissue laxity, and accurate component placement to improve patients' clinical outcomes. The purpose of this surgical technique report is to describe the Personalized Alignment TKA method using the ROSA^® Knee System and Persona^® The Personalized Knee^® implants. Herein we provide specific procedures for pre-operative planning, anatomical landmarking and evaluation, intra-operative planning and adjustment of resections and cuts, cut validation and soft tissue evaluation with robotic-assisted personalized TKA.

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.