Patient satisfaction after posterior-stabilized total knee arthroplasty: a functional specific analysis

Robotic-assisted differential total knee arthroplasty with patient-specific implants: surgical techniques and preliminary results

OBJECTIVE

In total knee arthroplasty (TKA), achieving soft-tissue balance while retaining acceptable lower limb alignment is sometimes difficult and may lead to patient dissatisfaction. Theoretically, patient-specific implants can bring great benefits, while the lack of precise surgical tools may hinder the improvement of outcomes. The objective of this study was to illustrate surgical techniques and evaluate kinematics and early clinical outcomes of robotic-assisted TKA using patient-specific implants.

METHODS

Based on preoperative CT scan, femoral and tibial components were 3D printed. Medial and lateral tibial liners were separate with different thicknesses, posterior slopes and conformity. TiRobot Recon Robot was used for surgery, and was armed with smart tools that quantify gap, force and femoral-tibial track. We collected data on demographics, intraoperative gap balance and femoral-tibial motion. In the follow-up, we evaluated the range of motion, Visual Analogue Scale (VAS), forgotten joint score (FJS), Knee injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS, JR) score. Radiological data were also harvested.

RESULTS

Fifteen patients (17 knees) were enrolled with a mean age of 64.6 ± 6.4 (53-76) years. In 5 knees, we used symmetric tibial liners, the rest were asymmetric. After surgery, the average alignment was 1.6 ± 2.0 (-3-5) degrees varus. The average follow-up lasted 6.7 ± 4.2 (1-14) months. The mean visual analogue scale was 0.8 ± 0.7 (0-2), FJS was 62.4 ± 25.3 (0-87), KOOS was 86.5 ± 9.4 (57-97). 11 patients were "very satisfied", 3 were "satisfied" with the result, and one patient was neutral due to restricted extension and unsatisfactory rehabilitation at five months' follow-up.

CONCLUSIONS

With patient-specific implants and robotics, TKA could be performed by a mathematical way, which was dubbed a "differential" TKA. Intraoperative kinematics was excellent in terms of gap-force balancing and femoral-tibial relative motion. Preliminary clinical outcomes were overall satisfactory.

Faster improvement in outcome scores in posterior stabilised total knee arthroplasty compared to medial congruent system with posterior cruciate ligament retained

Most studies comparing medial pivot to the posterior stabilised (PS) systems sacrifice the PCL. It is unknown whether retaining the PCL in the Medial Congruent (MC) system may provide further benefit compared to the more commonly used PS system. A retrospective review of a single-surgeon's registry data comparing 44 PS and 26 MC with PCL retained (MC-PCLR) TKAs was performed. Both groups had similar baseline demographics. The PS and MC-PCLR groups had similar pre-operative range of motion (ROM) (PS:104º ± 20º vs. MC-PCLR: 101º ± 19º, p = 0.70), Oxford Knee Score (OKS) (PS: 27 ± 6 vs. MC-PCLR: 26 ± 7, p = 0.62), and Knee Society Scoring System (KS) Function Score (KS-FS) (PS: 52 ± 24 vs. MC-PCLR: 56 ± 23, p = 0.49). The pre-operative KS Knee Score (KS-KS) was significantly lower in the PS group (PS: 44 ± 14 vs. MC-PLR: 53 ± 18, p < 0.05). At 12-months post-operation, there was significant improvement in all parameters (p < 0.01). Both groups had similar ROM (PS: 115º ± 13º vs. MC-PCLR: 114º ± 10º, p = 0.98), OKS (PS: 41 ± 5 vs. MC-PCLR: 40 ± 4, p = 0.50), KS-FS (PS: 74 ± 22 vs. MC-PCLR: 77 ± 16, p = 0.78), and KS-KS (PS: 89 ± 10 vs. MC-PCLR: 89 ± 10, p = 0.89). The PS group had significant improvement in all parameters from preoperation to 3-month postoperation (p < 0.05), but not from 3-month to 1-year postoperation (p ≥ 0.05). The MC-PCLR group continued to have significant improvement from 3-month to 1-year postoperation (p < 0.05). Preserving the PCL when using MC may paradoxically cause an undesired additional restrain that slows the recovery process of the patients after TKA. Compared to MC-PCLR, a PS TKA may expect significantly faster improvement at 3 months post operation, although they will achieve similar outcomes at 1-year post operation.

Using sequential bone cutting to titrate soft tissue balance in total knee arthroplasty effectively minimizes soft tissue release

BACKGROUND

Achieving soft tissue balance while maintaining limb alignment within acceptable boundaries is crucial for successful total knee arthroplasty (TKA). We proposed a sequential bone cutting (SBC) technique to titrate the soft tissue balance in robot-assisted TKA to achieve the desired balance with minimum soft tissue release.

METHODS

In total, 106 robot-assisted TKAs using the SBC technique were included. The preoperative hip-knee-ankle angle (HKA) was < 10° in 76 and ≥ 10° in 30 knees. The gaps were initially balanced with the help of the pre-resection balancing provided by the robotic system. Soft tissue balance and alignment were quantitatively measured after the initial bone cutting and final bone cutting. Additional adjustments (bone recuts and soft tissue releases) required to address soft tissue imbalance after initial bone cutting were recorded. The frequencies of soft tissue releases, soft tissue balance, and resultant alignment ≤ 3° were compared between non-severe (HKA < 10°) and severe deformity (HKA ≥ 10°) groups.

RESULTS

Soft tissue balance was achieved in 45 knees (42.5%) after initial bone cutting and in 93 knees (87.7%) after final balancing. The postoperative alignment was within 3° from neutral in 87 knees (82.1%) and 3-5° in 17 knees (16.0%). For unbalanced knees (n = 61) after initial bone cutting, soft tissue release was avoided by SBC in 37 knees (60.7%) and was deemed necessary in 24 knees (39.3%). Soft tissue release was more likely to be avoided in the non-severe deformity cohort (86.8% [33 of 38]) than in the severe deformity cohort (17.4% [4 of 23]; p < 0.001). The non-severe deformity cohort showed a significantly higher rate of resultant alignment ≤ 3° from neutral than the severe deformity cohort (90.8% vs. 60.0%; p < 0.001).

CONCLUSION

Pre-resection balancing is inappropriate to ensure soft tissue balance. The SBC technique is effective in minimizing soft tissue release while maintaining overall alignment within acceptable boundaries.

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

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

Exploring expectations of Chinese patients for total knee arthroplasty: once the medicine is taken, the symptoms vanish

BACKGROUND

Preoperative expectations of total knee arthroplasty (TKA) outcomes are important determinants of patient satisfaction. However, expectations of patients in different countries are affected by cultural background. The general goal of this study was to describe Chinese TKA patients' expectations.

METHODS

Patients scheduled for TKA were recruited in a quantitative study(n = 198). The Hospital for Special Surgery Total Knee Replacement Expectations Survey Questionnaire was used for survey TKA patients' expectations. Descriptive phenomenological design was used for the qualitative research. Semi-structured interviews were conducted with 15 TKA patients. Colaizzi's method was used for interview data analysis.

RESULTS

The mean expectation score of Chinese TKA patients was 89.17 points. The 4 highest score items were walk short distance, remove the need for walker, relieve pain and make knee or leg straight. The 2 lowest score items were employed for monetary reimbursement and sexual activity. Five main themes and 12 sub-themes emerged from the interview data, including multiple factors raised expectations, expectations of physical comfort, expect various activities back to normal, hope for a long joint lifespan, and expect a better mood.

CONCLUSIONS

Chinese TKA patients reported a relatively high level of expectations, and differences across cultures result in different expectation points than other national populations, requiring adjustment of items when using assessment tools across cultures. Strategies for expectation management should be further developed.

LEVEL OF EVIDENCE

Level IV.

Clinical and Radiological Outcomes of Revision Total Hip Arthroplasty for Patients with Prior Hartofilakidis Type C Hip Dysplasia

OBJECTIVE

To investigate the clinical and radiological results of revision total hip arthroplasty (THA) for patients with previously diagnosed Hartofilakidis type C hip dysplasia, which is technically challenging and lacks literature.

METHODS

We enrolled 20 patients with previously diagnosed Hartofilakidis type C hip dysplasia who underwent revision THA between November 2008 and July 2015 at our hospital. Patients were followed up for an average of 87 months. Data pertaining to the Harris hip score (HHS), modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), general satisfaction, and the level of satisfaction related to 16 hip functions or issues experienced after revision THA were collected. The vertical and horizontal center of rotation (COR) of the hips were measured bilaterally based on preoperative and postoperative anteroposterior radiographs. Categorical variables were analyzed by the chi-square test. Continuous variables were analyzed using the student's t test or non-parametric Wilcoxon Rank Sum test.

RESULTS

There were significant postoperative improvements in the HHS (47.4 ± 31.6 vs 70.1 ± 39.0), modified WOMAC (48.5 ± 27.9 vs 75.7 ± 36.8), and the vertical (45.7 ± 33.7 mm vs 21.6 ± 21.8 mm) and horizontal (41.8 ± 17.0 mm vs 31.4 ± 14.7 mm) offset of the COR after revision THA (P < 0.05). Fifteen (75.0%) patients were satisfied with the procedure. The satisfaction rate for each of the 16 items ranged from 45% to 100%. The top three dissatisfactory items were squatting, getting into/out of cars, and leg-length discrepancy. Postoperatively, dissatisfied patients had a significantly higher visual analogue scale pain score and lower WOMAC pain, HHS pain, WOMAC total, and HHS total scores, a lower satisfaction rate for pain relief, and a higher vertical COR.

CONCLUSION

There is a high rate (25%) of dissatisfaction with the outcome after revision THA for patients with prior Hartofilakidis type C hip dysplasia. The most likely reasons for dissatisfaction were inadequate pain relief and a higher vertical COR measured on radiography.

[Short-term effectiveness of novel computer navigation system assisted total knee arthroplasty]

Objective

To investigate the short-term effectiveness of novel computer navigation system (Knee 3 software; Brainlab, Germany) assisted total knee arthroplasty (TKA).

Methods

Between July 2020 and December 2020, 19 patients underwent unilateral TKA assisted with Knee 3 software. There were 4 males and 15 females. The mean age was 66.3 years (range, 52-79 years). Eighteen patients were diagnosed with osteoarthritis and 1 patient with rheumatoid arthritis. Sixteen patients had varus knees and 3 patients had valgus knees. Preoperative Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain, stiffness, function, and total scores were 12.4±3.4, 2 (1, 4), 22 (18, 29), and 37 (29, 43), respectively. Intraoperatively, the medial and lateral gaps in knee extension and in 90° of knee flexion were recorded. The operation time, intraoperative blood loss, blood transfusion, and complications were recorded. The hip-knee-ankle angle (HKA), lateral distal femoral angle, and medial proximal tibial angle were measured to evaluate lower limb alignment and prostheses's alignment using X-ray films at 6 weeks after operation. Patient's satisfaction rate and WOMAC pain, stiffness, function, and total scores were investigated.

Results

Eighteen patients (94.7%) had medial- lateral gap balancing in knee extension, 18 patients (94.7%) had medial-lateral gap balancing in 90° of knee flexion, 19 patients (100%) had medial gap balancing between knee extension and 90° of knee flexion, and 18 patients (94.7%) had lateral gap balancing between knee extension and 90° of knee flexion. The mean operation time was 126 minutes (range, 100-200 minutes). The mean intraoperative blood loss was 205 mL (range, 100-400 mL). Patients were followed up 4-8 months, with an average of 6.2 months. Postoperative complications included 1 deep vein thrombosis of lower extremities and 1 cerebral infarction. X-ray films showed that the mean HKA, lateral distal femoral angle, and medial proximal tibial angle were 179.8° (range, 178°-182°), 83.5° (range, 80°-87°), and 89.5° (range, 87°-93°), respectively. At last follow-up, WOMAC pain, stiffness, function, and total scores were 3.6±1.9, 0 (0, 2), 4 (2, 6), and 9 (5, 10), respectively, which improved when compared with preoperative scores ( P<0.05). Twelve patients were very satisfied with the operation results and 7 patients were satisfied with the operation results. The overall satisfaction rate was 100%.

Conclusion

Knee 3 software can help to obtain good gap balancing and optimal lower limb alignment, with high patient's satisfaction and good short-term effecectiveness.

In Vitro Kinematic Analysis of Single Axis Radius Posterior-Substituting Total Knee Arthroplasty

This is an experimental study. As current posterior-substituting (PS) total knee arthroplasties have been reported to incompletely restore intrinsic joint biomechanics of the healthy knee, the recently designed single axis radius PS knee system was introduced to increase posterior femoral translation and promote ligament isometry. As there is a paucity of data available regarding its ability to replicate healthy knee biomechanics, this study aimed to assess joint and articular contact kinematics as well as ligament isometry of the contemporary single axis radius PS knee system. Implant kinematics were measured from 11 cadaveric knees using an in vitro robotic testing system. In addition, medial collateral ligament (MCL) and lateral collateral ligament (LCL) forces were quantified under simulated functional loads during knee flexion for the contemporary PS knee system. Posterior femoral translation between the intact knee and the single axis radius PS knee system differed significantly (p < 0.05) at 60, 90, and 120 degrees of flexion. The LCL force at 60 degrees (9.06 ± 2.81 N) was significantly lower (p < 0.05) than those at 30, 90, and 120 degrees of flexion, while MCL forces did not differ significantly throughout the range of tested flexion angles. The results from this study suggest that although the contemporary single axis radius PS knee system has the potential to mimic the intact knee kinematics under muscle loading during flexion extension due to its design features, single axis radius PS knee system did not fully replicate posterior femoral translation and ligament isometry of the healthy knee during knee flexion.

Patient Resilience Has Moderate Correlation With Functional Outcomes, but Not Satisfaction, After Primary Unilateral Total Knee Arthroplasty

BACKGROUND

As many as 20% of patients who undergo total knee arthroplasty (TKA) are dissatisfied. Psychological factors have been shown to play a role in outcomes after TKA. The purpose of this study was to investigate the impact of patient resilience on functional outcomes and satisfaction after primary unilateral TKA.

METHODS

Eighty-six patients who underwent primary unilateral TKA by a single surgeon were studied. Primary outcomes were the Brief Resilience Scale (BRS), mental health component of the Veterans Rand 12-Item Health Survey (VR-12 MCS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, and New Knee Society Score. Correlations between BRS and dependent variables were found by using Spearmen's Rho Correlation testing. Unadjusted and adjusted regressions were run using the delta values as the dependent outcome and the BRS score as the main independent value, with data presented as an estimate of 95% confidence interval P value.

RESULTS

Resilience significantly correlated with male sex (P = .031), preoperative VR-12 MCS scores (P = .013), and postoperative VR-12 MCS scores (P < .001). BRS had moderate correlation with postoperative Knee Society Scores (KSS) Functional Activity Scores, as this approached, but did not achieve statistical significance (P = .062). There was no correlation between BRS and postoperative KSS Patient Expectations score, KSS Patient Satisfaction score, or total postoperative opioid usage.

CONCLUSIONS

Primary TKA patients with greater resilience are more likely to be male and have better mental health characteristics than those with lower resilience. Patients with greater resilience also tended to have improved knee function after TKA, although this was not statistically significant. Resiliency did not correlate with postoperative opioid consumption or patient satisfaction after TKA.

A high degree of knee flexion after TKA promotes the ability to perform high-flexion activities and patient satisfaction in Asian population

Background

This study investigated whether achieving a higher degree of knee flexion after TKA promoted the ability to perform high-flexion activities, as well as patient satisfaction and quality of life.

Methods

Clinical data on 912 consecutive primary TKA cases involving a single high-flexion posterior stabilized fixed-bearing prosthesis were retrospectively analyzed. Demographic and clinical data were collected, including knee flexion angle, the ability to perform high-flexion activities, and patient satisfaction and quality of life.

Results

Of the cases, 619 (68%) achieved > 130° of knee flexion after TKA (high flexion group). Knee flexion angle and clinical scores showed significant annual changes, with the maximum improvement seen at 5 years and slight deterioration observed at 10 years postoperatively. In the high flexion group, more than 50% of the patients could not kneel or squat, and 35% could not stand up from on the floor. Multivariate analysis revealed that > 130° of knee flexion, the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient satisfaction after TKA, while the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient quality of life after TKA.

Conclusions

High knee flexion angle (> 130°) after TKA increased the ease of high-flexion activities and patient satisfaction. The ease of high-flexion activities also increased quality of life after TKA in our Asian patients, who frequently engage in these activities in daily life.

Investigation of association between the preoperative intra-articular anesthetic test and persistent pain after total knee arthroplasty

BACKGROUND

A better understanding of the etiology of persistent pain after total knee arthroplasty (TKA) is required to prevent unfavorable outcomes. The purpose of this study was to investigate the association of persistent pain after TKA, patient characteristics, and the remaining pain ratio per the preoperative intra-articular anesthetic test.

METHODS

This study included 89 patients who underwent TKA and underwent an intra-articular anesthetic test preoperatively. The remaining pain ratio out of 100 percent 30 min after intra-articular anesthetic injection and demographic data were also evaluated preoperatively. Numerical rating scale (NRS) scores for pain during movement (Q1), at rest (Q2), at first movement in the morning (Q3), and during climbing up and down stairs (Q4) were evaluated 1 year after TKA. Multiple linear regression analysis was performed to assess the impact of independent variables on the NRS score for questionnaire No.4. and the remaining pain ratio per the intra-articular anesthetic.

RESULTS

The mean remaining pain ratio per the preoperative intra-articular anesthetic test was 29.3%. The NRS score for Q4 was significantly higher than those for any of the other NRS questionnaires administered 1 year after TKA (Q1-Q4, Q2-Q4, P < 0.001; Q3-Q4, P < 0.05). The analysis found the weak correlation between the pain ratio of anesthetic test and the NRS score for Q4 after TKA (R = 0.28, P = 0.018). BMI and preoperative FTA were the major predictors of remaining pain ratio per the intra-articular anesthetic test (R = 0.40, P = 0.002).

CONCLUSION

This study revealed that the remaining pain ratio per the preoperative intra-articular anesthetic test was weakly correlated with persistent pain during climbing up and down stairs 1 year after TKA. In addition, BMI and preoperative FTA were associated with the remaining pain ratio per the preoperative intra-articular anesthetic test.

Does Unicompartmental Knee Replacement Offer Improved Clinical Advantages Over Total Knee Replacement in the Treatment of Isolated Lateral Osteoarthritis? A Matched Cohort Analysis From an Independent Center

BACKGROUND

The purpose of this study is to compare the functional and radiographic results, perioperative complications, satisfaction rate, and mid-term survivorship after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) for the treatment of lateral compartmental knee osteoarthritis (LCKO).

METHODS

Between March 2007 and September 2017, we identified 35 patients with primary TKAs and 121 patients with lateral UKAs (LUKAs) for LCKO with a minimum follow-up of 2 years (mean 5.3 years, range 2-12.4). The matched variables were age, gender, operation side, body mass index, American Society of Anesthesiologist grade, initial diagnosis, osteoarthritis grade in lateral compartment, and follow-up time. All patients were assessed using the Oxford Knee Score, Hospital for Special Surgery score, range of motion, length of hospital stay, satisfaction, and complications. Survivorship of UKA and TKA implants was also compared.

RESULTS

At last follow-up, LUKA had a significantly better postoperative Oxford Knee Score, Hospital for Special Surgery score, range of motion, shorter length of hospital time, and higher satisfaction rate than matched TKA group. There were significant differences regarding patellar tendon injury (P = .043), superficial wound infection (P = .028), patellar snapping or impingement (P = .047), and stiffness (P < .001). Five-year survivorships free from revision were similar in both groups (99.2% vs 97.1%, P = .347).

CONCLUSION

LUKA for LCKO demonstrated more favorable 5-year results in comparison with TKA. Furthermore, LUKA achieved comparable mid-term survivorship and was less likely to suffer from wound infection and knee stiffness, although not overall surgical complications.

Manipulation under anesthesia as a therapy option for postoperative knee stiffness: a retrospective matched-pair analysis

INTRODUCTION

Due to demographic changes, total knee arthroplasty (TKA) is one of the most frequently performed orthopedic surgeries. Therapies for associated postoperative complications, such as postoperative knee stiffness (PKS), are becoming increasingly important. The aim of this retrospective matched-pair analysis was to evaluate mid-term-results following manipulation under anesthesia (MUA).

MATERIALS AND METHODS

Fifty-one patients with PKS were evaluated and 51 matched-pair patients without PKS after primary TKA were chosen for the control group. In addition to the range of motion, the functionality was recorded by Knee Society Score (KSS), Western Ontario and Mc Masters Universities Osteoarthritis Index (WOMAC), and Short-Form-12 Questionnaire (SF-12). Experience of pain was mapped using a 10-point Numeric Rating Scale (NRS), and the analgesic requirement was mapped using the WHO step scheme. A final follow-up examination was conducted approximately three years after TKA. To evaluate potential risk factors for the development of PKS, TKA alignment was measured via postoperative X-ray images.

RESULTS

Improvement of the average knee flexion of 35.7° and total flexion of 107.4° was detected in PKS patients after MUA. The flexion of the control group was 112.4°; no significant between-group difference was present regarding prosthesis type, sex, age and BMI. Regarding KSS, WOMAC, and SF-12, the MUA cohort achieved statistically-relevant lower overall scores than the control group, p = 0.006, p = 0.005, p = 0.001, respectively. Significantly higher experiences of pain and a higher need for analgesics in MUA patients were reported (p = 0.001 and p < 0.001, respectively). Radiological evaluation of the prosthesis alignment did not show any differences between the two groups.

CONCLUSIONS

MUA can improve mobility after PKS, whereby MUA seemed to be a functional therapy option for PKS. Compared to the control group, the MUA group showed lower functional values and an increased experience of pain. A correlation between prosthesis malalignment and MUA could not be detected radiologically. Further studies are necessary to investigate the reasons for PKS.

In Vivo Knee Kinematics for a Cruciate Sacrificing Total Knee Arthroplasty Having Both a Symmetrical Femoral and Tibial Component

BACKGROUND

Early total knee arthroplasty (TKA) designs were symmetrical, but lead to complications due to over-constraint leading to loosening and poor flexion. Next-generation TKAs have been designed to include asymmetry, pertaining to the trochlear groove, femoral condylar shapes, and/or the tibial component. More recently, an advanced posterior cruciate sacrificing (PCS) TKA was designed to include both a symmetrical femoral component with a patented V-shaped trochlear groove and a symmetrical tibial component with an ultracongruent insert, in an attempt to reduce inventory costs. Because previous PCS TKA designs produced variable results, the objective of this study is to determine and evaluate the in vivo kinematics for subjects implanted with this symmetrical TKA.

METHODS

Twenty-one subjects, implanted with symmetrical PCS fixed-bearing TKA, were asked to perform a weight-bearing deep knee bend (DKB) while under fluoroscopic surveillance. A 3-dimensional to 2-dimensional registration technique was used to determine each subject's anteroposterior translation of lateral and medial femoral condyles as well as tibiofemoral axial rotation and their weight-bearing knee flexion.

RESULTS

During the DKB, the average active maximum weight-bearing flexion was 111.7° ± 13.3°. On average, from full extension to maximum knee flexion, subjects experienced -2.5 ± 2.0 mm of posterior femoral rollback of the lateral condyle and 2.5 ± 2.2 mm of medial condyle motion in the anterior direction. This medial condyle motion was consistent for the majority of the subjects, with the lateral condyle exhibiting rollback from 0° to 60° of flexion and then experienced an average anterior motion of 0.3 mm from 60° to 90° of knee flexion. On average, the subjects in this study experienced 6.6°± 3.3° of axial rotation, with most of the rotation occurring in early flexion, averaging 4.9°.

CONCLUSION

Although subjects in this study were implanted with a symmetrical PCS TKA, they did experience femoral rollback of the lateral condyle and a normal-like pattern of axial rotation, although less in magnitude than the normal knee. The normal axial rotation pattern occurred because the lateral condyle rolled in the posterior direction, while the medial condyle moved in the anterior direction. Interestingly, the magnitude of posterior femoral rollback and axial rotation for subjects in this study was similar in magnitude reported in previous studies pertaining to asymmetrical TKA designs. It is proposed that more patients be analyzed having this TKA implanted by other surgeons.

Comparison of Patient Satisfaction Between Medial Pivot Prostheses and Posterior-Stabilized Prostheses in Total Knee Arthroplasty

OBJECTIVE

To compare medial pivot (MP) prostheses to two types of posterior-stabilized (PS) prostheses (NexGen and NRG) in terms of patient satisfaction, causes of dissatisfaction, and risk factors for dissatisfaction after total knee arthroplasty (TKA).

METHODS

A total of 453 patients who underwent primary TKA by one senior surgeon from August 2016 to August 2018 were investigated in a retrospective study, including 121, 219, and 113 patients in the MP, NexGen, and NRG groups, respectively. The mean age and follow-up time of patients were 70.82 ± 7.06 years and 20.64 ± 3.88 months. A survey was designed and responses were collected by telephone, WeChat, and outpatient follow up. Patient satisfaction, causes of dissatisfaction, post-TKA pain on a numeric rating scale (NRS), and range of motion (ROM) were compared among groups, and risk factors were investigated. Patient satisfaction included a five-level satisfaction rating (very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied), with five options for causes of dissatisfaction (persistent pain, limited ROM, knee instability, asthenia, and/or other factors).

RESULTS

Overall, 89.84% of patients were satisfied with the results of primary TKA. There were no significant differences among the three groups regarding the side of the operation, the length of hospitalization in days, or the average follow-up time. Patient satisfaction was similar among the MP (87.38%), NexGen (89.89%), and NRG groups (90.32%). Persistent pain after TKA was the major cause of dissatisfaction (32/40), but no difference in the frequency of this complaint was found among the groups (P = 0.663). The NRS score (P = 0.598) and the ROM (P = 0.959) of the MP group were not significantly different from those of the NexGen and NRG groups. Gender, length of hospitalization, and follow-up time were all uncorrelated with patient satisfaction, but age showed a very weak correlation with patient satisfaction (r = 0.110, P = 0.033). Moreover, the NRS score (r = 0.459, P < 0.000) and the ROM (r = -0.175, P = 0.001) were significantly correlated with patient dissatisfaction. The odds ratio of dissatisfaction was 6.37 (P < 0.000) in patients with moderate to severe pain (NRS ≥ 3) compared to patients with mild pain (NRS < 3).

CONCLUSION

Patient satisfaction and function were not found to be higher in the MP group than in the two PS groups, and persistent pain was the major cause of and an important risk factor for patient dissatisfaction.

Preoperative low scores of Life Satisfaction Rating predicts poor outcomes after total knee arthroplasty: a prospective observational study

Background

Despite the continued improvement in the surgical techniques during primary total knee arthroplasty (TKA), literatures indicate that up to 10 to 20% patients are not satisfied with their outcomes. Psychological factors in this dissatisfaction are yet to be clearly identified. The aim of this study is to develop a method to assess whether the patient’s current mental state is suitable enough to accept a TKA surgery.

Methods

Preoperative demographic and clinical data of 532 patients who underwent TKA were prospectively obtained from January 2012 until December 2016. We recorded the scores evaluated by SF-36 questionnaire and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) preoperatively and 1 year postoperatively. Preoperative Life Satisfaction Rating (LSR) is emphatically evaluated.

Results

Poor preoperative score of LSR was a significant predictor of dissatisfaction after TKA. Patients with low LSR reported significant pain and stiffness, although there was no remarkable effect on functionality of the replaced joint. The results also showed that age and BMI were not strong predictors of satisfaction in TKA.

Conclusion

Our outcomes can help clinicians evaluate whether a patient’s current mental status is favorable for TKA. If patients have extreme low scores of LSR (less than 10), a psychological intervention should be recommended for better satisfaction following a TKA surgery. This would also allow surgeons to individually assess the risks and benefits of surgery.

Kinematic Performance of Gradually Variable Radius Posterior-Stabilized Primary TKA During Various Activities: An In Vivo Study Using Fluoroscopy

BACKGROUND

Posterior-stabilized total knee arthroplasty (TKA) with gradually variable radii (G-curve) femoral condylar geometry is now available. It is believed that a G-curve design would lead to more mid-flexion stability leading to reduced incidence of paradoxical anterior slide. The objective of this study was to assess the in vivo kinematics for subjects implanted with this type of TKA under various conditions of daily living.

METHODS

Tibiofemoral kinematics of 35 patients having posterior-stabilized TKA with G-curve design were analyzed using fluoroscopy while performing three activities: weight-bearing deep knee bend, gait, and walking down a ramp. The subjects were assessed for range of motion, condylar translation, axial rotation, cam-spine engagement, and condylar lift-off.

RESULTS

The average weight-bearing flexion during deep knee bend was 111.4°. On average, the subjects exhibited 5.4 mm of posterior rollback of the lateral condyle and 2.0 mm of the medial condyle from full extension to maximum knee flexion. The femur consistently rotated externally with flexion, and the average axial rotation was 5.2°. Overall movement of the condyles during gait and ramp-down activity was small. No incidence of condylar lift-off was observed.

CONCLUSION

Subjects in this study experienced consistent magnitudes of posterior femoral rollback and external rotation of the femur with weight-bearing flexion. The variation is similar to that previously reported for normal knee where the lateral condyle moves consistently posterior compared to the medial condyle. Subjects experienced low overall mid-flexion paradoxical anterior sliding and no incidence of condylar lift-off leading to mid-flexion stability.

Total Knee Arthroplasty in Patients with Prior Femoral and Tibial Fractures: Outcomes and Risk Factors for Surgical Site Complications and Reoperations

Objective

To investigate the outcomes of total knee arthroplasty (TKA) in patients with a prior femoral or tibial fracture, and identify the risk factors for surgical site complications and reoperations.

Methods

Seventy‐one TKAs performed in 71 patients with a prior tibial or femoral fracture between January 2005 and December 2016 were reviewed retrospectively. Forty males (40 knees) and 31 females (31 knees) were included. The mean age at the time of TKA was 59.2 (range, 29–83) years. Outcomes were assessed using the Knee Society score before surgery and at the final follow‐up visit. The patients' satisfaction rates were evaluated. Complications and reoperations were recorded by clinical and radiographic assessment. Logistic regression analysis was used to identify the risk factors for surgical site complications and reoperations.

Results

The median follow‐up period was 4.7 (range, 3.2–7.1) years. The median knee range of motion increased from 90° preoperatively to 110° at the latest follow‐up. The Knee Society knee score and function score improved from 35 (30, 40) and 40 (30, 50) to 90 (82, 93) and 90 (65, 100), respectively. The degree of overall satisfaction after TKA surgery was very satisfied in 41 patients, satisfied in 20 patients, neutral in four patients, dissatisfied in four patients, and very dissatisfied in two patients. The overall satisfaction (very satisfied and satisfied) rate was 85.9% (61 knees). Twelve knees (16.9%) had 19 surgical site complications. Six knees (8.3%) underwent reoperations, including one revision due to periprosthetic joint infection, one debridement and implant retention for superficial infection, two debridements for delayed wound healing, one open reduction and internal fixation for supracondylar fracture, and one re‐fixation and bone grafting for hardware failure after a combined femoral shaft osteotomy and TKA. Preoperative patella baja was diagnosed in 12 knees, and was identified as a risk factor for surgical site complications and reoperations.

Conclusions

TKA for post‐fracture osteoarthritis significantly relieved pain and improved function, but the incidence of surgical site complications and reoperations was high. Preoperative patella baja was a risk factor for surgical site complications and reoperations.

[Research progress about influence of patellofemoral osteoarthritis on effectiveness of unicompartmental knee arthroplasty]

Objective

To summarize the current research progress about influence of patellofemoral osteoarthritis on clinical outcome of unicompartmental knee arthroplasty (UKA).

Methods

The recent related literature was extensively reviewed and summarized, including pros and cons to regard the patellofemoral osteoarthritis as the contraindication.

Results

Previous studies regarded patellofemoral osteoarthritis as the contraindication of UKA. Most of current researches show that the damage to the articular cartilage of the patellofemoral joint to the extent of full-thickness cartilage loss has no influence on outcome of UKA. There is no correlation between preoperative anterior knee pain or medial patellofemoral joint degeneration and the clinical outcome. However, lateral subluxation of the patella has an adverse impact on postoperative curative effect. Degeneration of the lateral patellofemoral joint may be a risk factor of the outcome.

Conclusion

Patellofemoral osteoarthritis should not be the absolute contraindication of UKA. The effect of degeneration of the lateral patellofemoral joint is not clear at present, and still needs further studies in the future.

Mismatch between femur and tibia coronal alignment in the knee joint: classification of five lower limb types according to femoral and tibial mechanical alignment

Background

Reasons for dissatisfaction with total knee arthroplasty (TKA) include unequal flexion or extension gap, soft tissue imbalance, and patella maltracking, which often occur with mismatch between femoral and tibial coronal bony alignment in the knee joint or extremely varus or valgus alignment. However, lower limb coronal alignment classification is based only on hip–knee–ankle angle (HKAA), leading to oversight regarding a mismatch between femoral and tibial coronal alignment. We aimed to classify alignment of the lower limbs according to the mechanical alignment of the femur and tibia in a healthy population.

Methods

All 214 normal triple films were reviewed retrospectively. HKAA, mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), angle between the femoral anatomical axis and the mechanical axis (AA-MA), and knee alignment angle (KAA) were measured. Subjects were categorized into one of five types based on the mechanical alignment of femur and tibia.

Results

Mean HKAA, mLDFA, and mMPTA of all subjects were 1.2°, 87.3°, and 85.8°, respectively. All subjects were classified into one of five types with significant differences (p < 0.001). About 61% of subjects showed neutral alignment, of which nearly 40% were type 2 (valgus of the femur and varus of the tibia with oblique joint line: mLDFA 85.0° ± 1.4°, mMPTA 85.1° ± 1.2°, TJLA 2.7° ± 2.4°) and 60% exhibited neutral alignment with a neutral femur and tibia (type 1). In varus and valgus types, mismatch between the mechanical angle of the femur and tibia was common. Varus alignment, including types 3 (varus of the tibia: mLDFA 88.0° ± 1.4°, mMPTA 83.5° ± 1.6°) and 4 (varus of both the tibia and femur: mLDFA 91.4° ± 1.4°, mMTPA 85.2° ± 2.0°), was found in 30% of subjects. Valgus alignment (type 5 valgus of femur: mLDFA 84.6° ± 1.6°, mMPTA 88.8° ± 2.0°) accounted for 8.9% of all subjects.

Conclusions

Mismatch between mechanical alignment of the femur and tibia was common in varus and valgus alignment types. Joint line obliquity was also observed in 40% of the neutral alignment population. This classification provides a quick, simple interpretation of femoral and tibial coronal alignment, and more detailed guidance for preoperative planning for TKA than the traditional varus–neutral–valgus classification.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2335-9) contains supplementary material, which is available to authorized users.

Postoperative Stiffness Requiring Manipulation Under Anesthesia Is Significantly Reduced After Simultaneous Versus Staged Bilateral Total Knee Arthroplasty

BACKGROUND

For patients with symptomatic bilateral knee arthritis, it is unknown whether the risk of developing stiffness requiring manipulation under anesthesia postoperatively is higher or lower for those undergoing simultaneous bilateral total knee arthroplasty (TKA) compared with those having staged bilateral TKA. Therefore, we undertook this study to evaluate the risk of requiring manipulation under anesthesia in staged versus simultaneous bilateral TKA as well as patients undergoing unilateral TKA.

METHODS

We utilized the California Patient Discharge Database, which is linked with the California Emergency Department, Ambulatory Surgery, and master death file databases. Using a literature-based estimate of the number of patients who failed to undergo the second stage of a staged bilateral TKA, replacement cases were randomly selected from patients who had unilateral TKA and were matched on 8 clinical characteristics of the patients who had staged bilateral TKA. Hierarchical multivariate logistic regression was performed to determine the risk-adjusted odds of manipulation in patients undergoing unilateral TKA, staged bilateral TKA, and simultaneous bilateral TKA using yearly hospital TKA volume as a random effect. Adjustment was made to allow fair comparison of the outcome at 90 and 180 days of follow-up after staged compared with simultaneous bilateral TKA.

RESULTS

During the time period from 2005 through 2013, the cumulative incidence of manipulation within 90 days was 2.14% for unilateral TKA (4,398 events per 205,744 patients), 2.11% for staged bilateral TKA (724 events per 34,352 patients), and 1.62% for simultaneous bilateral TKA (195 events per 12,013 patients). At 180 days of complete follow-up, the cumulative incidence of manipulation was 3.07% after unilateral TKA (6,313 events per 205,649 patients), 2.89% after staged bilateral TKAs (957 events per 33,169 patients), and 2.29% after simultaneous bilateral TKA (267 events per 11,653 patients). With multivariate analyses used to adjust for relevant risk factors, the 90-day odds ratio (OR) of undergoing manipulation after simultaneous bilateral TKA was significantly lower than that for unilateral TKA (OR = 0.70; 95% confidence interval [CI], 0.57 to 0.86) and staged bilateral TKA (OR = 0.71; 95% CI, 0.57 to 0.90). Similarly, at 180 days, the odds of undergoing manipulation were significantly lower after simultaneous bilateral TKA than after both unilateral TKA (OR = 0.71; 95% CI, 0.59 to 0.84) and staged bilateral TKA (OR = 0.76; 95% CI, 0.63 to 0.93). The frequency of manipulation was significantly associated with younger age, fewer comorbidities, black race, and the absence of obesity.

CONCLUSIONS

Although the ORs were small (close to 1), simultaneous bilateral TKA had a significantly decreased rate of stiffness requiring manipulation under anesthesia at 90 days and 180 days after knee replacement compared with that after staged bilateral TKA and unilateral TKA.

LEVEL OF EVIDENCE

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

Patient Dissatisfaction Following Total Knee Arthroplasty: A Systematic Review of the Literature

BACKGROUND

Dissatisfaction following total knee arthroplasty (TKA) is common. Approximately 20% of patients report dissatisfaction following primary TKA. This systematic literature review explores key factors affecting patient dissatisfaction following TKA.

METHODS

Six literature databases published between 2005 and 1 January 2016 were searched using 3 key search phrases. Papers were included if the study investigated patient dissatisfaction in primary unilateral or bilateral TKA. Information from each article was categorized to the domains of socioeconomic, preoperative, intraoperative, and postoperative factors affecting patient dissatisfaction.

RESULTS

This review found that patient dissatisfaction pertains to several key factors. Patient expectations prior to surgery, the degree of improvement in knee function, and pain relief following surgery were commonly cited in the literature. Fewer associations were found in the socioeconomic and surgical domains.

CONCLUSION

Identifying who may be dissatisfied after their TKA is mystifying; however, we note several strategies that target factors whereby an association exists. Further research is needed to better quantify dissatisfaction, so that the causal links underpinning dissatisfaction can be more fully appreciated and strategies employed to target them.

Patient Satisfaction After Total Knee Arthroplasty: A Realistic or Imaginary Goal?

This article summarizes the current literature regarding patient satisfaction after total knee arthroplasty. In 10% to 15% of cases, the operation has not met the patients' expectations. The causes of this dissatisfaction are multifactorial, and include patient-related factors, details related to the surgical procedure and prosthesis chosen, perioperative factors, and factors associated with nursing and general medical care. However, surgeons must bear the brunt of patients' dissatisfaction. This dissatisfaction erodes the doctor-patient relationship, and may have implications in an emerging health care economy in which doctors and hospitals are reimbursed based on both clinical outcome and patient satisfaction.

Early Clinical Outcomes of a New Posteriorly Stabilized Total Knee Arthroplasty Prosthesis: Comparisons with Two Established Prostheses

Purpose

We sought to determine whether early clinical performance of new posterior stabilized (PS) knee system, the Vega-PS (Aesculap), is better than that of two established total knee arthroplasty (TKA) prostheses, the E.motion-PS (Aesculap) and the Genesis II (Smith & Nephew) in terms of functional outcomes, patient satisfaction, and incidence of adverse events.

Materials and Methods

We compared the clinical outcomes of 206 consecutive TKAs using Vega-PS with those of 205 TKAs using E.motion-PS and 216 TKAs using Genesis II at 2 years of follow-up.

Results

Overall, the knees with the Vega-PS had better functional outcome scores than the knees with the E.motion-PS, but had similar outcome scores to the knees with the Genesis II, as evident from the American Knee Society knee score (94.2 vs. 92.5 vs. 93.2), Western Ontario McMaster Universities Osteoarthritis (WOMAC) stiffness index (1.8 vs. 2.3 vs. 2.0), WOMAC function index (11.8 vs. 16.8 vs. 18.5), Short Form 36 (SF-36) physical component summary score (41.9 vs. 39.3 vs. 41.6), and SF-36 mental component summary score (50.0 vs. 45.8 vs. 46.9). Patient satisfaction was higher in the Vega-PS and Genesis II groups than the E.motion-PS group. No notable group differences were found in terms of the incidence of adverse events.

Conclusions

The Vega-PS, a newly developed PS fixed bearing prosthesis, had comparable or superior clinical performance in comparison with the two established fixed or mobile bearing PS prostheses.

Reduction Osteotomy versus Extensive Release on Clinical Outcome Measures in Simultaneous Bilateral Total Knee Arthroplasty

Background

During total knee arthroplasty (TKA) in varus knee deformities, reduction osteotomy (RO) and medial soft tissue release are alternative techniques to aid in achieving deformity correction. In this study, we investigated the effect of RO compared to extensive medial soft tissue release (ER) on clinical outcome measures in simultaneous bilateral TKA.

Material/Methods

We prospectively enrolled 24 patients (48 knees) with bilateral varus knee deformity from July 2014 to December 20l5. For each patient, one knee was assigned to the RO group and the contralateral knee was assigned to ER group. One year postoperative, follow-up outcomes were collected and analyzed.

Results

Time to 90° flexion of the knee was significantly different in the RO group (1.6±0.3 days) compared to the ER group (2.0±0.4 days) (p<0.001). Using a 10-item patient reported outcome questionnaire, total scores were significantly different between the RO group (86.3±3.2) and the ER group (82.4±2.7) (p<0.001). Analysis of variance showed a significant difference on the visual analogue scale (VAS) score (p<0.001) but no significant difference in the range of motion (ROM) of the knee (p>0.05) during the follow-up year.

Conclusions

Knees treated with RO were associated with greater improvements in pain and function than knees treated with conventional ER technique. Additionally, RO technique did not confer an increased risk for adverse clinical outcomes. RO may therefore by a safe method to decrease postoperative pain, achieve earlier functional recovery, and increase patients’ subjective satisfaction after TKA.

Differences in Patient-Reported Outcomes Between Unicompartmental and Total Knee Arthroplasties: A Propensity Score-Matched Analysis

BACKGROUND

The purpose of this study was to compare the patient-reported outcomes regarding joint awareness, function, and satisfaction after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).

METHODS

We identified all patients who underwent a UKA or TKA at our institution between September 2011 and March 2014, with a minimum follow-up of 2 years. Propensity score matching was performed for age, gender, body mass index, operation side, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. One hundred UKAs to 100 TKAs were matched. Each knee was evaluated according to the WOMAC score, Forgotten Joint Score (FJS), High Flexion Knee Score (HFKS) and patient's satisfaction at postoperative 2 years.

RESULTS

There was no significant difference in WOMAC score at postoperative 2 years between UKA and TKA groups. However, the FJS of the UKA group was significantly higher than that of the TKA group (67.3 ± 19.8 and 60.6 ± 16.6, respectively; P = .011). The HFKS was also significantly higher in the UKA group compared with the TKA group (34.4 ± 6.4 and 31.3 ± 5.2, respectively; P < .001). Eighty-six percent of all patients who underwent UKA were satisfied compared with 71% of those who underwent TKA (P = .027).

CONCLUSION

Patients who underwent UKA had higher FJS, HFKS, and satisfaction rate when compared with patients who underwent TKA, indicating that UKA facilitated less knee awareness and better function and satisfaction than TKA.

Distinctions of introarticular force distribution between genesis-II posterior stabilized and cruciate retaining total knee arthroplasty: An intraoperative comparative study of 45 patients

BACKGROUND

Although both the posterior stabilized and cruciate retaining total knee arthroplasty have been proven to effectively relieve pain and restore basic functions, the joint gap width during flexion was reported to be different due to the presence or absence of posterior cruciate ligament, which may lead to different intra-articular force distribution. In this study, we investigated the distinctions in intra-articular force distribution between the two types of TKA designs in patients with varus knee osteoarthritis.

METHODS

Forty five patients (50 knees) with varus knee osteoarthritis were prospectively included, with each 25 knees receiving cruciate retaining and posterior stabilized total knee arthroplasty, respectively. With an intra-articular force measurement system, the intra-articular force distribution with knee flexion at 0°, 30°, 45°, 60°, 90°, and 120° were recorded in all patients.

FINDINGS

The total force was similar for posterior stabilized and cruciate retaining knees at all flexion degrees. However, force in the medial compartment accounted for 59.8%-84.0% of total force in posterior stabilized knees, while 27.4%-65.7% in cruciate retaining knees. In cruciate retaining knees, no significant difference was found between forces in the two compartments at 30° flexion (P=0.444), but force was significantly concentrated in the lateral side during 45°-120° flexion (P=0.000-0.028).

INTERPRETATION

Although the entire intra-articular forces were similar between CR and PS knees at different flexion angles, medial part had higher force than lateral part when PS knee was used. The posterior cruciate ligament do a role in soft balance, and make the force more evenly distributed.

Computed Tomography Analysis of Postsurgery Femoral Component Rotation Based on a Force Sensing Device Method versus Hypothetical Rotational Alignment Based on Anatomical Landmark Methods: A Pilot Study

Rotation of the femoral component is an important aspect of knee arthroplasty, due to its effects on postsurgery knee kinematics and associated functional outcomes. It is still debated which method for establishing rotational alignment is preferable in orthopedic surgery. We compared force sensing based femoral component rotation with traditional anatomic landmark methods to investigate which method is more accurate in terms of alignment to the true transepicondylar axis. Thirty-one patients underwent computer-navigated total knee arthroplasty for osteoarthritis with femoral rotation established via a force sensor. During surgery, three alternative hypothetical femoral rotational alignments were assessed, based on transepicondylar axis, anterior-posterior axis, or the utilization of a posterior condyles referencing jig. Postoperative computed tomography scans were obtained to investigate rotation characteristics. Significant differences in rotation characteristics were found between rotation according to DKB and other methods (P < 0.05). Soft tissue balancing resulted in smaller deviation from anatomical epicondylar axis than any other method. 77% of operated knees were within a range of ±3° of rotation. Only between 48% and 52% of knees would have been rotated appropriately using the other methods. The current results indicate that force sensors may be valuable for establishing correct femoral rotation.

No difference in clinical outcomes after total knee arthroplasty between patellar eversion and non-eversion

PURPOSE

Multiple surgical techniques in minimally invasive total knee arthroplasty (TKA) are associated with clinical differences. However, whether patellar eversion impairs clinical outcomes remains controversial. We conducted a systematic review of randomized controlled trials (RCTs) to provide current understanding on this topic.

METHODS

A literature search of the PubMed, Embase, and Cochrane library databases was performed to identify RCTs comparing patellar eversion with patellar non-eversion (PN). Two authors independently selected the studies, assessed methodological quality, and extracted data.

RESULTS

Five RCTs involving 379 knees were included. The results revealed no significant differences in functional scores, pain, quality of life, quadriceps strength, patellar height, alignment, or complication rate between patellar eversion and PN. Power analysis showed that the power of the individual study and meta-analysis ranged from 5.0 to 70.8%, with the exception of the power of alignment and patellar height in two of the individual studies, which was 100.0 and 99.9%, respectively.

CONCLUSIONS

Based on the current evidence, patellar eversion during TKA could not definitely lead to inferior postoperative outcomes. Patellar eversion and patellar non-eversion could achieve similar clinical outcomes.

LEVEL OF EVIDENCE

Systematic review and meta-analysis, Level I.

Stance time variability during stair stepping before and after total knee arthroplasty: A pilot study

The main objectives of this pilot study were to: (1) investigate stance time variability (STV) during stair stepping in older adults with osteoarthritis (OA) before and after total knee arthroplasty (TKA), and compare to an age- and sex-matched group of healthy controls with native knees and (2) evaluate the relationship between quadriceps strength and STV during stair stepping before and after TKA. A prospective, observational, pilot study was carried out on 13 individuals (15% male, mean age 62.71±6.84years) before and after TKA using an instrumented stairway, patient-reported outcomes, timed stair stepping test, and quadriceps strength measures. At 6-months post-operatively, STV during stair descent was significantly greater in the TKA-GROUP compared to the CONTROL-GROUP, but was not significantly different at 12-months compared to controls. There were no significant differences in STV for stair ascent between the pre- and post-operative visits, or compared to controls. There was a trend toward significance for the relationship between quadriceps strength and STV during stair ascent (P=0.059) and descent (P=0.073). Variability during stair stepping may provide an important, short-term rehabilitation target for individuals following TKA and may represent another parameter to predict declines in functional mobility.

Robotic-assisted knee arthroplasty

Robotics in total knee arthroplasty (TKA) has undergone vast improvements. Although some of the systems have fallen out of favor due to safety concerns, there has been recent increased interest for semi-active haptic robotic systems that provide intraoperative tactile feedback to the surgeon. The potential advantages include improvements in radiographic outcomes, reducing the incidence of mechanical axis malalignment of the lower extremity and better tissue balance. Proponents of robotic technology believe that these improvements may lead to superior functional outcomes and implant survivorship. We aim to discuss robotic technology development, outcomes of unicompartmental and total knee arthroplasty and the future outlook. Short-term follow-up studies on robotic-assisted knee arthroplasty suggest that, although some alignment objectives may have been achieved, more studies regarding functional outcomes are needed. Furthermore, studies evaluating the projected cost-benefit analyses of this new technology are needed before widespread adoption. Nevertheless, the short-term results warrant further evaluation.

Manipulation Under Anesthesia After Total Knee Arthroplasty is Associated with An Increased Incidence of Subsequent Revision Surgery

A national database was used to evaluate the risk for manipulation under anesthesia (MUA) after total knee arthroplasty (TKA), the association of demographics and comorbidities with needing MUA, and the risk of revision TKA after MUA. Of the 141,016 patients who underwent TKA, 4.3% required MUA within 6 months. Age under 50 years (OR: 2.79, P<0.0001), age 50-65 years (OR: 2.03, P<0.0001), and female gender (OR: 1.12, P<0.0001) were all associated with increased rates of MUA. In patients under age 65 years, smoking (OR: 1.47, P<0.0001) was associated with an increased rate of MUA. Patients who require MUA within 6 months after TKA have a significantly increased risk of early revision TKA (OR: 2.43, P<0.0001).

Posterior stabilized versus cruciate retaining total knee arthroplasty designs: conformity affects the performance reliability of the design over the patient population

Commercially available fixed bearing knee prostheses are mainly divided into two groups: posterior stabilized (PS) versus cruciate retaining (CR). Despite the widespread comparative studies, the debate continues regarding the superiority of one type over the other. This study used a combined finite element (FE) simulation and principal component analysis (PCA) to evaluate "reliability" and "sensitivity" of two PS designs versus two CR designs over a patient population. Four fixed bearing implants were chosen: PFC (DePuy), PFC Sigma (DePuy), NexGen (Zimmer) and Genesis II (Smith & Nephew). Using PCA, a large probabilistic knee joint motion and loading database was generated based on the available experimental data from literature. The probabilistic knee joint data were applied to each implant in a FE simulation to calculate the potential envelopes of kinematics (i.e. anterior-posterior [AP] displacement and internal-external [IE] rotation) and contact mechanics. The performance envelopes were considered as an indicator of performance reliability. For each implant, PCA was used to highlight how much the implant performance was influenced by changes in each input parameter (sensitivity). Results showed that (1) conformity directly affected the reliability of the knee implant over a patient population such that lesser conformity designs (PS or CR), had higher kinematic variability and were more influenced by AP force and IE torque, (2) contact reliability did not differ noticeably among different designs and (3) CR or PS designs affected the relative rank of critical factors that influenced the reliability of each design. Such investigations enlighten the underlying biomechanics of various implant designs and can be utilized to estimate the potential performance of an implant design over a patient population.