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Purpose: To evaluate if there was a correlation between in vivo kinematics of a medial-stabilized (MS) total knee arthroplasty (TKA) and post-operative clinical scores. We hypothesized that (1) a MS-TKA would produce a medial pivot movement and that (2) this specific pattern would be correlated with higher clinical scores. Methods: 18 patients were evaluated through clinical and functional scores evaluation (Knee Society Score clinical and functional, Womac, Oxford), and kinematically through dynamic radiostereometric analysis (RSA) at 9months after MS-TKA, during the execution of a sit-to-stand and a lunge motor task. The anteroposterior (AP) Low Point translation of medial and lateral femoral compartments was compared through Student’s t test (p < 0.05). A correlation analysis between scores and kinematics was performed through the Pearson’s correlation coefficient r. Results: A significantly greater (p < 0.0001) anterior translation of the lateral compartment with respect to the medial one was found in both sit-to-stand (medial 2.9mm ± 0.7mm, lateral 7.1mm ± 0.6mm) and lunge (medial 5.3mm ± 0.9mm, lateral 10.9mm ± 0.7mm) motor tasks, thus resulting in a medial pivot pattern in about 70% of patients. Significant positive correlation in sit-to-stand was found between the peak of AP translation in the lateral compartment and clinical scores (r = 0.59 for Knee Society Score clinical and r = 0.61 for Oxford). Moreover, we found that the higher peak of AP translation of the medial compartment correlated with lower clinical scores (r = − 0.55 for Knee Society Score clinical, r = − 0.61 for Womac and r = − 0.53 for Oxford) in the lunge. A negative correlation was found between Knee Society Score clinical and VV laxity during sit-to-stand (r = − 0.56) and peak of external rotation in the lunge motor task (r = − 0.66). Conclusions: The MS-TKA investigated produced in vivo a medial pivot movement in about 70% of patients in both examined motor tasks. There was a correlation between the presence of medial pivot and higher post-operative scores. Level of evidence: IV.

Achieving a well-balanced total knee arthroplasty (TKA) is a difficult task, but the use of real-time sensing technology could provide intraoperative dynamic feedback regarding stability and load. This study compared intraoperative data and clinical outcomes between two cohorts, where one cohort had a sensor-guided medial pivot TKA performed.Methods:Two cohorts of 50 patients each were preoperatively matched to receive the same TKA, having a J-curve femoral design with an adapted “medially congruent” polyethylene insert; the second cohort (group B) underwent the intraoperative sensor-check. Intraoperative sensor data were recorded as tibiofemoral load at 10°, 45°, and 90°. We considered stable knees those with a pressure Results:All patients (group A: no sensor; group B: sensor) were available at 2-year minimum follow-up (FU; min. 24 months, max. 34 months); no preoperative statistical differences existed between groups in the average range of motion (ROM), OKS, KSS, and body mass index. There were no statistical differences at final FU between groups in the average OKS (group A: 41.1; group B: 41.5), in the average KSS (group A: 165.7; group B: 166.3), or in final ROM (group A: 123°; group B: 124°). One patient in each group required a manipulation under anesthesia. In the sensor group, an accessory soft tissue release/bone recut was necessary after sensor testing with trial components in 24% to obtain the desired loads; in the same group, the level of constraint in the final components was increased to posterior-stabilized in 12% because of an inter-compartmental difference >40 lbs. Surgical time was 8 min longer in the sensor group.Conclusion:The use of this sensing technology did not improve the clinical outcome but supported multiple intraoperative decisions aimed to better reproduce the medial pivot kinematic of the normal knee.

Background The medial-pivot (MP) design for total knee arthroplasty (TKA) aims to restore more natural “ball-and-socket” knee kinematics compared to the traditional posterior-stabilized (PS) implants for TKA. The objective of this study is to determine if there was any difference in functional outcomes between patients undergoing MP-TKA vs PS-TKA. Methods This prospective randomized controlled trial consisted of 43 patients undergoing MP-TKA vs 45 patients receiving a single-radius PS-TKA design. The primary outcome was postoperative range of motion (ROM). Secondary outcomes included the Western Ontario and McMaster Universities Arthritis Index, Oxford Knee Score, Knee Society Score (KSS), and radiological outcomes. All study patients were followed-up for 2 years after surgery. Results Patients undergoing MP-TKA had comparable ROM at 1 year (114.6° ± 16.3° vs 111.3° ± 17.8° respectively, P = .88) and 2 years after surgery (114.9° ± 15.5° vs 114.9° ± 16.4° respectively, P = .92) compared to PS-TKA. There were also no differences in Western Ontario and McMaster Universities Arthritis Index (26.8 ± 19.84 vs 22.0 ± 12.03 respectively, P = .14), Oxford Knee Score (42.7 ± 8.1 vs 42.3 ± 6.7 respectively, P = .18), KSS clinical scores (82.9 ± 16.96 vs 81.42 ± 10.45 respectively, P = .12) and KSS functional scores (76.2 ± 18.81 vs 73.93 ± 8.53 respectively, P = .62) at 2-year follow-up. There was no difference in postoperative limb alignment or complications. Conclusion This study demonstrated excellent results in both the single-radius PS-TKA design and MP-TKA design. No differences were identified at 2-year follow-up with respect to postoperative ROM and patient-reported outcome measures.

The survival rate of navigation-assisted mobile bearing total knee arthroplasty when mechanical revision was considered as the end-point wa snot impacted by the design, either central pivot or medial pivot.

ObjectiveThe purpose of this study was to explore the mid-and long-term clinical effects of Chinese patients with medial pivot (MP) prosthesis and posterior-stabilized (PS) prosthesis after total knee arthroplasty (TKA), to provide a reference for the recommendation of clinical prostheses.MethodsA retrospective analysis of 802 patients who received TKA was performed from June 2010 to December 2013. A total of 432 patients received a MP prosthesis (MP group) and 375 patients received a PS prosthesis (PS group). Postoperative range of motion (ROM), clinical scores including the knee scoring system (KSS), the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), the forgotten joint score (FJS), and postoperative complications were compared between the two groups.ResultsA total of 527 patients were followed up, including 290 in the MP group and 237 in the PS group. Both groups achieved satisfactory results in terms of KSS score, WOMAC score, and postoperative ROM, which were significantly improved compared with those before surgery, but the difference between the groups was not statistically significant (P> 0.05). The FJS scores of the MP group and the PS group were satisfactory and no significant difference was observed (P= 0.426). Postoperative complications occurred in 5 and 11 patients in the MP group and PS group, respectively.ConclusionThe clinical results of TKA with MP or PS in Chinese patients at mid- and long-term are encouraging, and no significant differences were observed between the two types of prostheses. Studies have also shown that both prostheses are safe for Chinese patients.

Purpose To investigate if postoperative clinical outcomes correlate with specific kinematic patterns after total knee arthroplasty (TKA) surgery. The hypothesis was that the group of patients with higher clinical outcomes would have shown postoperative medial pivot kinematics, while the group of patients with lower clinical outcomes would have not. Methods 52 patients undergoing TKA surgery were prospectively evaluated at least a year of follow-up (13.5 ± 6.8 months) through clinical and functional Knee Society Score (KSS), and kinematically through dynamic radiostereometric analysis (RSA) during a sit-to-stand motor task. Patients received posterior-stabilized TKA design. Based on the result of the KSS, patients were divided into two groups: “KSS > 70 group”, patients with a good-to-excellent score (93.1 ± 6.8 points, n = 44); “KSS n = 8). The anteroposterior (AP) low point (lowest femorotibial contact points) translation of medial and lateral femoral compartments was compared through Student’s t test (p Results Low point AP translation of the medial compartment was significantly lower (p 70 (6.1 mm ± 4.4 mm vs 10.7 mm ± 4.6 mm) and the KSS p > 0.05) between the two groups, while the AP translation of the medial femoral compartment was significantly higher for the KSS > 70 group (p = 0.0442). Conclusion In the group of patients with a postoperative KSS Level of evidence II.

Introduction Total knee arthroplasty (TKA) usually provides good pain relief and improved function but has generally been unable to fully restore normal knee kinematics. Does Medial or Lateral Pivot TKA designs guide us to native knee kinematics needs to be elucidated? Methods Kinematic assessment of 13 knees with Medial Pivot TKA and 13 knees with Lateral Pivot TKA was done. The subjects were asked to perform step-up and weight bearing deep knee bend exercise under fluoroscopy for kinematic assessment. Patellar Tendon Angle (PTA) was measured after correcting f luoroscopic images for distortion against Knee Flexion Angle (KFA). Results During the weight bearing deep knee bend, the average active maximum flexion achieved with Medial Pivot design was 113.8 as compared to 102.9 with Lateral Pivot design. There was no significant difference in PTA in step up and deep knee bend exercise between both the designs. Conclusion The kinematic assessment of both the Medial and Lateral Pivot TKA designs revealed linear trend of PTA with increasing KFA as described for normal knee. Both the designs were able to achieve functional knee range of motion.

The medial pivot total knee arthroplasty (TKA) has good patients’ satisfaction; however, there is likely the restriction of postoperative knee flexion. The 2nd generation medial pivot TKA prosthesis was designed to improve postoperative knee flexion. This study aimed to compare the clinical outcomes and patient satisfaction between the 2nd generation and 1st generation medial pivot TKA prostheses. We conducted a retrospective study of 472 consecutive TKAs, performed using either the 2nd generation (EVOLUTION™), having smaller posterior femoral condyle and asymmetrical tibial tray, or 1st generation (ADVANCE™) prosthesis. The use of each system was historically determined. Patient age, sex and body mass index were matched between the two groups, with 157 cases ultimately included in each group. Measured clinical outcomes included: knee range of motion, the Knee Society Score, the rate of re-operation, and radiological parameters. Patient satisfaction was evaluated using the 12-item Forgotten Joint Score (FJS-12). The average follow-up period was 5.0 (3.7–6.3) years for the 2nd generation group and 8.7 (6.1–12.8) years for the 1st generation group (p

Many Asian populations have a unique floor-based lifestyle that might cause mechanical stress of the knees. It is important to clarify the longevity of a medial pivot total knee arthroplasty, as its prosthetic design could cause mechanical stress onto the insert. The purpose of this study was to clarify the clinical results of medial pivot total knee arthroplasty for Asian patients in a 10-year follow-up study.Consecutive, primary total knee arthroplasties (n = 257) were analyzed in the study using the medial pivot knee system. The clinical outcomes were assessed preoperatively and at the final follow-up. The patient-reported Forgotten Joint Score-12 and radiological outcomes were measured at the final follow-up. The survival rate was assessed with reoperation or revision as the end-point.The mean follow-up period was 10.1 ± 1.7 years. The lost to follow-up was 4.5%. All clinical outcomes improved significantly after surgery (p 0.001). The mean postoperative knee flexion was 118° ± 11° and the mean Forgotten Joint Score-12 was 59.7 ± 27 points. The radiolucent line was observed in 29 patients (11.3%), however there was no aseptic loosening noted. The survival rates with reoperation or revision were 96.3% or 98.4% at 10 years after the operation.Medial pivot total knee arthroplasty used for Asian patients showed good longevity and patient-reported outcome measurement in a mean 10-year follow-up study. Medial pivot total knee arthroplasty has long-term stability among patients who have a floor-based lifestyle.III.

Background Total knee arthroplasty (TKA) is a common treatment for severe knee osteoarthritis. TKA designs have evolved from posterior-stabilized systems (PS-TKA) developed in the late 70 s that replicate posterior-cruciate ligament function to medial-pivot systems (MP-TKA) developed in the early 90 s that more closely mimic natural knee kinematics. This study aimed to test the hypothesis that people with MP-TKA have better postoperative outcomes than PS-TKA, and their balance control is more akin to age-matched asymptomatic controls.Methods Fifty-seven participants (20 PS-TKA, 18 MP-TKA and 19 asymptomatic controls) were recruited. At 1-year post-TKA, pain, knee stiffness and physical function were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Static balance, mobility and gait stability were assessed using wearable devices during the near tandem stance, timed-up-and-go (TUG) and six-minute walk (6MWT) tests.Results Compared to asymptomatic controls, both TKA groups reported significantly more pain and stiffness, and demonstrated reduced functional mobility, increased stride-time-variability and impaired balance; indicating increased fall risk. After Bonferroni adjustment, no significant differences were observed between PS-TKA and MP-TKA participants. However, there was a trend for increased anteroposterior sway of the lumbar and head regions in the MP-TKA participants when undertaking the near tandem stance test.Conclusions Contrary to the hypothesis, the MP-TKA patients did not have less pain or better balance and mobility performance than the PS-TKA patients 1 year after surgery. Future longitudinal research should determine whether the two types of patients display different pain, balance controls and mobility over the first year postoperative period.

Objective To compare the clinical outcomes of Medial-pivot and Posterior-stablized total knee arthroplasty during 8 years follow-up. Methods 109 patients with osteoarthritis who underwent primary total knee arthroplasty were conducted and divided into two groups according to the choice of prosthesis,49 in the Medial-pivot(MP) group and 60 in the Postirior-stabilized(PS) group.There were no statistical differences in age,gender,BMI,operative side and operation time between the two groups (P>0.05).The same protocol of perioperative treatment was adopted in both groups. Comparison of clinical outcome and survival rates were acquired through minimum 8 years follow-up. Results The prosthesis survival rate andthe excellent and good rate of MP group were 93.9% and 88.9% during average 8.3 years follow-up period,versus the prosthesis survival rate and the excellent or good rate of PS group were 93.3% and 86.7% during average 8.4 years follow-up period.There were no statistical diferences in survival rate,excellent and good rate and radiolucency of weight-bearing areas between the two groups ( P >0.05). There were no statistical differences in range of motion,KSS score and WOMAC index between the two groups preoperatively (P>0.05).The range of motion at all follow-up time points and KSS score at 6 months postoperatively of PS group were superior than those of MP group ( P

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

A Guided Motion knee is one with features other than basic bearing surfaces, to guide or control the motion in prescribed ways, usually to provide some resemblance to anatomic knee motion. Among the earliest knees were those which allowed freedom of rotation of the femoral component on the tibia about a central axis, the UCI and the Variable Axis being two examples. These designs allowed for the axial rotation which occurs in function as well as anterior-posterior stability. Reproducing the function of the menisci was a logical goal in that they maintain a large area of contact, minimize contact stresses, and buffer the femur at the extremes of motion. Meniscal bearing knees were the result, including the Oxford and Minns. An evolution of this concept was the LCS rotating platform, which also provided freedom of internal-external rotation. Based on experimental data that the knee pivoted about the medial side, due to medial stability and lateral mobility, medial pivot knees were invented and have shown positive clinical feedback. Biomimetic knees, either imitating anatomic geometry or motion, have been challenging in that several designs have been invented, but there has been limited experience so far. This class of knee has a high but as yet unrealized potential.

Background Medial pivot (MP) type total knee arthroplasty (TKA) implants are designed with a highly congruent medial tibiofemoral articulation. Compared with the cam-and-post design of the posterior-stabilized (PS) TKA, the MP-TKA design has been hypothesized to better replicate the natural kinematics of the knee. We compared the MP-TKA and PS-TKA designs, with our primary outcome measures being range of motion (ROM) and patient-reported satisfaction. Methods This study was a retrospective comparison between the 2 groups (76 MP-TKA vs 88 PS-TKA). ROM was collected preoperatively, 6 weeks, 6 months, and 1 year postoperatively. The Forgotten Joint Score-12 (FJS-12) scores were collected at a minimum of 1 year postoperatively. Results There was no statistically significant difference in age, gender, or body mass index between the groups. We found a statistical difference in preoperative ROM (MP = 120.3°, PS = 112.8°, P = .002). There was no difference in ΔROM at 6 weeks (MP = −12.36, PS = −3.79, P = .066), 6 months (MP = −4.23, PS = 2.73, P = .182), or 1 year (MP = .17, PS = 3.31, P = .499). Patients who underwent the MP-TKA scored significantly better than the PS-TKA on the FJS-12 score (MP = 59.72, PS = 44.77, P = .007). Conclusion We found that patients who underwent the MP-TKA scored better on the FJS than those who underwent the PS-TKA; particularly with regard to deep knee flexion and stability of the prosthesis. The MP-TKA design may offer improved patient outcomes because of its highly congruent medial tibiofemoral articulation.

Medial pivot kinematics describes the normal axial rotation of the lateral compartment of the knee about the inherently more constrained medial compartment that occurs during flexion and extension. Medial stabilized total knee arthroplasty designs replicate the asymmetric medial-lateral constraint p

AimsThe outcome of total knee arthroplasty (TKA) is not always satisfactory. The purpose of this study was to identify satisfaction and biomechanical features characterising the gait of patients who had undergone TKA with either an anatomical single radius design or a medial pivot design. We hypothesised that the latter would provide superior function.Patients and MethodsThis is a study of a subset of patients recruited into a prospective randomised study of a single radius design versus a medial pivot design, with a minimum follow-up of one year. Outcome measurements included clinical scores (Knee Society Score (KSS) and Oxford Knee Score (OKS)) and gait analysis using an instrumented treadmill.ResultsThere was no statistically significant difference between the two groups for both the KSS and OKS. There was also no statistical significance in cadence, walking speed, stride length and stance time, peak stride, mid support and push-off forces.ConclusionThis study corroborates a previous study by the same authors that showed equally good results in clinical outcome and gait between the conventional single radius and medial pivot designs under stringent testing conditions. Cite this article: Bone Joint J 2018;(1 Supple A)100-B:76–82.

Few studies on kinematics correlate patterns to functional outcomes after total knee arthroplasty (TKA). The purpose of this study was to determine if lateral pivot motion in early flexion and medial pivot in high flexion, simulating native knee kinematics, produces superior clinical outcomes. A second objective was to determine if specific kinematic patterns produce superior outcomes.One hundred twenty consecutive TKAs were performed using sensor trials to record intraoperative knee kinematics. Lateral and medial pivot pattern designations were based on the center of rotation within 3 flexion zones: 0°-45° (early), 45°-90°, and 90° to full flexion (late). Knee Society Scores, pain scores, and patient satisfaction were analyzed in relation to kinematic patterns.Knee Society function scores were higher in TKAs with early lateral pivot/late medial pivot intraoperative kinematics compared to all other kinematic patterns (P = .018), and there was a greater decrease in the proportion who reported that their knee never feels normal (P = .011). Early lateral/late medial pivot had greater function scores at 1-year (P.001) and improvement from preoperative baseline (P = .008) compared to those with the least ideal pattern. All patients with the most ideal pattern compared to none of the least ideal pattern reported they were very satisfied (P = .003).Patients with an intraoperative early lateral pivot pattern followed by medial pivot motion in later flexion, reported higher functional outcome scores along with higher overall patient satisfaction. Replicating the dual-pivot kinematic pattern observed in native knees may improve function and satisfaction after TKA.

Malrotation of tibial components is one of the important causes of failure in total knee arthroplasty. The aim of this study is to determine the relationship between tibial rotational positioning and coverage of the tibial surface during the operation, using a symmetric and newly introduced asymmetric medial pivot tibial components. The coverage and overhang were compared between a symmetric component (Advance medial pivot) and a newly introduced asymmetric medial pivot tibial component (Evolution medial pivot) in 31 knees during the operation. When the tibial component was placed parallel to the anteroposterior (AP) axis, the uncovered width in the posteromedial part using a symmetric design was larger than that using an asymmetric design (p

To assess whether there the final range of motion (ROM) results achieved by patients undergoing total knee arthroplasty (TKA) with prosthesis using Medial Pivot design are predictable.Between January and August of 2014, 155 patients with primary osteoarthritis of knee who underwent TKA using the prosthesis ADVANCESignificant differences (The final ROM achieved by patients that underwent TKA with medial pivot prosthesis can be predicted. The perioperative ROM correlates with that at 45 days after surgery. The final ROM is correlated with that of the pre-operative period.Avaliar se há previsibilidade da amplitude de movimentos alcançada por pacientes submetidos a artroplastia total do joelho com prótese que usa desenho medial pivot.Entre janeiro e agosto de 2014 foi feita avaliação prospectiva de 155 pacientes com osteoartrose primária do joelho submetidos a artroplastia total do joelho com o uso da prótese AdvanceDiferenças significativas (p 0,001) foram relatadas entre as médias e medianas da amplitude de movimentos no pré-operatório em comparação com as medidas obtidas no período intraoperatório. As medidas do pré-operatório também se mostraram diferentes quando comparadas com aquelas após seis meses de pós-operatório (p 0,001). Não foram encontradas diferenças significativas entre as médias e medianas da amplitude de movimento na comparação do intraoperatório e as medidas feitas aos 45 dias (Há previsibilidade da amplitude de movimentos obtida por pacientes submetidos a artroplastia total do joelho com prótese medial pivot. A amplitude aos 45 dias é semelhante àquela observada nas medidas intraoperatórias. A amplitude final está relacionada à amplitude pré-operatória.

The medial pivot total knee prosthesis with alumina ceramic femoral components was introduced to reproduce physiological knee kinematics and reduce polyethylene wear. The five-year clinical outcomes of alumina medial pivot total knee arthroplasties (TKA) have previously been reported. The purpose of this study was to provide the longer-term clinical results at a minimum follow-up of 10years.The clinical results of 70 alumina medial pivot TKA in 51 consecutive patients, with a minimum follow-up period of 10years, were evaluated.Mean follow-up was 11.8years (range 10 to 13). Alumina medial pivot TKAs improved the patients' Knee Society knee scores, function scores, and postoperative ranges of motion compared with their pre-operative statuses (P0.05 for each). Revision surgery was required in one knee due to a postoperative fracture of the tibial plateau after a fall that occurred two years postoperatively. Osteolysis and femoral component loosening was identified in one case after the initial five-year time point of analysis. The survival rate was 99.1% at 10years.This study demonstrated excellent clinical results for patients receiving the alumina medial pivot prosthesis at a minimum follow-up period of 10years.

Both rotating-platform (RP) mobile-bearing and medial-pivot (MP) fixed-bearing prostheses allow axial femorotibial rotation using a highly conforming polyethylene insert. However, limited comparative data are available between the 2 designs. This study was performed to compare the midterm clinical outcomes and patient-reported outcome measures (PROMs) of RP and MP prostheses.We retrospectively reviewed the records of 52 total knee arthroplasties using RP mobile-bearing prosthesis and 49 total knee arthroplasties using MP fixed prosthesis with a minimum follow-up period of 5 years. Clinical and radiological outcomes, failure rates, and PROMs, including the Western Ontario and McMaster Universities Osteoarthritis Index score and satisfaction, were compared.There was no difference in clinical or radiographic outcomes (P.1 for all comparisons), with the exception of the larger flexion contracture (FC) in the MP group (0.3° in RP vs 2.3° in MP, P.01). No failure in either group was recorded during the study period. PROMs were comparable (P.1 in all comparisons), with the exception of higher satisfactions in the RP group while performing light household duties (P.01) and leisure or recreational activities (P = .014) in patients without FC.The midterm clinical results with both the RP mobile-bearing and MP fixed-bearing prostheses were satisfactory. Although both prostheses provided comparable PROMs, patients with an RP prosthesis were more satisfied than those with an MP prosthesis for highly demanding activities that are strongly associated with the presence of postoperative FC.

Introduction The kinematic alignment (KA) technique for total knee arthroplasty (TKA) and the medial pivot (MP) component design are two options promoting a physiologic prosthetic knee kinematics when used in combination that could improve TKA outcomes. Case-control study is initiated to compare the 1-year radio-clinical outcomes between kinematic alignment medial pivot total knee arthroplasty (KA MP-TKAs) and mechanical alignment medial pivot total knee arthroplasty (MA MP-TKA). Goal of a study was to answer the following questions: Do KA MP-TKAs patients have improved functional outcomes compared to MA MP-TKAs patients? (Q1); Do prosthetic knee and lower limb alignments differ between KA and MA patients (Q2)? And does kinematic implantation of MP TKA has higher risk of reoperations and revisions (Q3)? Material and methods A case-control study was carried out to compare the 1-year clinical and radiographic outcomes between 24 consecutive KA-TKA patients and 24 matched MA-TKA patients. All patients had implantation with manual instruments and a cemented medial pivot TKA with excision of the PCL. All data were collected prospectively, and outcome scores were patient reported. Results KA patients had superior values in Forgotten Joint Score (FJS) at 1-year (KA 77 vs. MA 51) (p = 0.05) follow-up. After one year KA patients scored better in objective section of the new Knee Society Score (KSS) (p = 0.02), and in sport section of the Knee Osteoarthritis Outcome Score (KOOS) (p = 0.01). Eleven out of 24 patients (46%) in KA group and 7/24 patients (29%) in MA group had limb alignment out of 180° ± 3°, whereas 17/24 (70%) of KA patients, and 14/24 (58%) of MA patients had orientation of tibial component with more than 3° of varus. No reoperation or revision occurred in either group. Discussion/Conclusion The KA of MP TKA design seems to have a good efficacy at early-term, with some 1-year functional performance higher to the ones from MA MP TKAs. Further research is needed to define if those early results will last over time. Level of evidence III, case-controlled study.

Medial pivot (MP) TKA has been shown to mimic normal knee kinematics with long-term survivorship comparable to most contemporary TKA. However, there are inadequate evidences to suggest its superiority in terms of patient preference and satisfaction. The aim of this study is to compare the MP with posterior-stabilized (PS) TKA in terms of patient preference and satisfaction. 46 patients with staged bilateral TKA were recruited. TKA with MP or PS design was performed at interval of 6–12 months. Patient preference, patient satisfaction score (0–100), Forgotten Joint Score (FJS), range of motion (ROM), Pain Score, Knee Society Score (KSS), Knee Function Score (KFS) and WOMAC Score were compared at up to 12 months. The mean age was 70 and 69.6% were female. There was no difference in all preoperative parameters, operative time and length of stay between two knees. No difference was found in in range of motion and all outcome scores at 6 months and 12 months. Satisfaction score was similar for the two designs (82 vs 85, p = n.s.) at 1 year after the second TKA. Proportion of patients with preference on one design over another was not significantly different (28.9 vs 35.6%, p = n.s.). There is no evidence to support the superiority of MP TKA over PS TKA in terms of preference and satisfaction. The choice between MP TKA versus PS TKA maybe more a surgeon’s preference than a patient’s preference based on current evidence.

PURPOSE: The purpose of the present study was to assess the kinematical behavior of a multi-radius posterior-stabilized (PS) mobile-bearing (MB) total knee arthroplasty (TKA) during an activity of daily living (Sit-To-Stand-STS) and a high demanding motor task (Deep-Knee-Lunge-DKL) using model-based dynamic RSA. We hypothesized the achievement of medial pivoting movement in both motor tasks due to the congruent geometry of the inlay with the femoral component, which should allow good stability of the medial compartment, and to the high magnitude of rotations guaranteed by the MB on the tibial side. METHODS: Twenty-two randomly selected patients were recruited and prospectively evaluated. The PS MB cemented TKA was implanted with the standard technique (medial parapatellar approach, adjusted mechanical alignment). At minimum 9-month follow-up, patients were examined with model based Dynamic RSA developed in our Institute (BI-STAND DRX 2) during the execution of two motor tasks: STS and DKL. The motion parameters were evaluated using the Grood and Suntay decomposition and the low-point kinematics methods. RESULTS: In the extension phase of DKL femur performed a greater antero posterior translation of 3.8 mm compared to STS between 0° and 20° of knee flexion (p

Conclusive evidence supporting a clinical difference between posterior-stabilized (PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA) does not currently exist, despite both designs being used for decades. Proponents of PS designs that employ a cam-and-post mechanism cite in vivo fluoroscopic data that demonstrate improved posterior rollback; however, optimal rollback has never been correlated to superior clinical outcomes. Recently, anterior-lipped and more conforming CR bearings, such as ultracongruent, medial pivot, and dual-pivot designs, have been used to substitute for the posterior cruciate ligament and obviate the need for the cam–post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include eliminating the risk of box cut induced femoral condylar fracture, improving operative efficiency by removing procedural steps, removing the articulation that is a source of wear, postdeformation, breakage, or dislocation, and eliminating patellar clunk. Health care reform efforts mandate cost reduction, and procedural efficiencies and minimizing inventory through the removal of unnecessary bearing options foster that initiative.

AimsBetween 15% and 20% of patients remain dissatisfied following total knee arthroplasty (TKA). The SAIPH knee system (MatOrtho, Surrey, United Kingdom) is a medial ball and socket TKA that has been designed to replicate native knee kinematics in order to maximize the range of movement, stability, and function. This system is being progressively introduced in a stepwise fashion, with this study reporting the mid-term clinical and radiological outcomes.Patients and MethodsA retrospective review was undertaken of the first 100 consecutive patients with five-year follow-up following SAIPH TKA performed by the senior authors. The data that were collected included the demographics of the patients, clinical findings, the rate of intraoperative ligamentous release, patient-reported outcome measures (PROMS), radiological assessment, complications, and all-cause revision. Revision data were cross-checked with a national registry.ResultsA total of 100 TKAs in 92 patients were included. Three patients died (three TKAs) and a further two TKAs were revised. Of the remaining 95 TKAs, five-year follow-up data were available for 81 TKAs (85%) in 87 patients. There were significant improvements in all PROMs and high satisfaction. The mean ROM at final follow-up was from 0° (full extension) to 124° flexion. There were seven major complications (7%): one infection, two deep vein thromboses, one cerebrovascular event, and two patients with stiffness requiring a manipulation under anaesthesia. Two patients required a lateral retinacular release to optimize patellar tracking in valgus knees; no additional ligament releases were performed in any patient. Radiological analysis demonstrated no evidence of implant-related complications.ConclusionThese results demonstrate satisfactory clinical and radiological outcomes at five years following a medial ball and socket TKA. The complication and revision rates are consistent with those previously reported for patients undergoing TKA. These results demonstrate the safety and efficacy of the SAIPH Knee TKA system and support its wider use.

Total knee arthroplasty (TKA) is one of the success stories of modern surgery. Primary TKA is commonly used when nonsurgical treatments for osteoarthritis fail. The need for TKA is projected to increase by 673% between 2005 and 2030, creating a tremendous burden on the healthcare system. This article reviews selected perioperative management strategies, computer-aided navigation, patient-specific cutting blocks, and medial pivot knee implants as potential sources of improvements in clinical efficiency and patient outcomes.

To compare different types of knee arthroplasty, in selected patients with a knee score above 80 points, for their post-operative changes in anteroposterior (AP) laxity and proprioception. Four groups of each ten patients were tested for AP translation after different types of arthroplasty with a KT-1000 device at 30°, 60° and 90° of flexion. Proprioception of the joint was evaluated by joint position sense with three different tests. Clinical outcome of stability and proprioceptive testing was analysed by comparing the results of three (KSS, KOOS and FJS-12) patient-reported outcome measurement scores (PROMS) for each of the different implant types. Anteroposterior laxity was observed at 30° and 90° of flexion for the two PS TKA designs included in this study, but not for the UKA or the medial pivot design. All knee designs, except UKA, had an increased laxity at 60° of flexion. Proprioceptive testing was inconclusive. PROMS were not able to identify differences in clinical outcome among different knee designs in these selected patients, despite observed differences in AP laxity. Increased AP laxity is a result of the surgical procedure in knee arthroplasty. UKA is the only design mimicking native laxity of the knee. A medial pivot design can obtain the same result as UKA at 30° and 90° of flexion, but not at the importantly cited 60° of flexion as tested under non-load-bearing conditions. The clinical relevance of this study is that despite of an important range of AP translations among the different knee designs, good-to-excellent patient-reported outcome was observed within the findings of this study. II.

Objective:The purpose of this radiological study was to assess the posterior laxity of a single model of a total knee arthroplasty design (TKA) having a medially constrained (MC) or a Posterior-Stabilized (PS) polyethylene insert using a well-documented stress x-ray. To the authors knowledge, this is the first report evaluating MC TKA outcomes according to the “kneeling view.”Materials and Methods:Sixty patients with non-traumatic primary knee osteoarthritis undergoing TKA were first matched by age, sex, BMI and diagnosis and then divided in two groups: group A (37 knees) received a MC TKA and group B (23 knees) a PS implant made by the same manufacturer. In all cases the posterior cruciate ligament (PCL) was resected. All patients underwent the same postoperative “kneeling view” and were also clinically evaluated according to the Knee Society Score (KSS) and Oxford Knee Score (OKS). Radiographic measurements were taken by tracing a line along the posterior cortex of the tibia and then measuring the perpendicular distance to a point marked at the posterior corner of Blumensaat’s line.Results:At 12 months minimum FU, no statistically significant differences were found between the two groups in all the clinical scores. There was a statistically significant difference on kneeling view values between the two groups (P = 0.0002): the mean value in the MC group was −1.97 ± 3.8 mm while was −5.6 ± 3.1 mm in the PS group. In both groups, the average position of the posterior cortex of the tibia was anterior to the posterior corner of Blumensaat’s line, showing absence of instability in flexion.Conclusion:This study highlighted that the PCL removal, accompanied by a precise surgical technique, did not increase the instability in flexion in two groups of patients having the same TKA design but polyethylene inserts characterized by different levels of constraint.

Introduction The kinematic alignment (KA) technique for total knee arthroplasty (TKA) and the medial pivot (MP) component design are two options promoting a physiologic prosthetic knee kinematics when used in combination that could improve TKA outcomes. Case-control study is initiated to compare the 1-year radio-clinical outcomes between kinematic alignment medial pivot total knee arthroplastiy (KA MP-TKAs) and mechanical alignment medial pivot total knee arthroplastiy (MA MP-TKA). Goal of a study was to answer the following questions: do KA MP-TKAs patients have improved functional outcomes compared to MA MP-TKAs patients? (Q1); do prosthetic knee and lower limb alignments differ between KA and MA patients (Q2)? And does kinematic implantation of MP TKA has higher risk of reoperations and revisions (Q3)? Material and methods A case-control study was carried out to compare the 1-year clinical and radiographic outcomes between 24 consecutive KA-TKA patients and 24 matched MA-TKA patients. All patients had implantation with manual instruments and a cemented medial pivot TKA with excision of the PCL. All data were collected prospectively, and outcome scores were patient reported. Results KA patients had superior values in Forgotten Joint Score (FJS) at 1-year (KA 77 vs. MA 51) (p = 0.05) follow-up. After one year, KA patients scored better in objective section of the new Knee Society Score (KSS) (p = 0.02), and in sport section of the Knee Osteoarthritis Outcome Score (KOOS) (p = 0.01). Eleven out of 24 patients (46%) in KA group and 7/24 patients (29%) in MA group had limb alignment out of 180 ± 3°, whereas 17/24 (70%) of KA patients, and 14/24 (58%) of MA patients had orientation of tibial component with more than 3 of varus. No reoperation or revision occurred in either group. Discussion/conclusion The KA of MP-TKA design seems to have a good efficacy at early-term, with some 1-year functional performance higher to the ones from MA MP-TKAs. Further research is needed to define if those early results will last over time. Level of evidence III, case-controlled study.

Background Restoration of natural knee kinematics for a designed mechanism in knee implants is required to achieve full knee function in total knee arthroplasty (TKA). In different posterior-stabilized TKAs, there are wide variations in tibiofemoral surfaces and post-cam design. However, it is not known whether these design variations preserve natural knee kinematics. The purpose of this study was to determine the most appropriate tibiofemoral surface and post-cam designs to restore natural knee kinematics of the TKA. Methods A subject-specific finite element knee modal was used to evaluate tibiofemoral surface and post-cam design. Three different posts in convex, straight, and concave geometries were considered with a fixed circular cam design in this study. In addition, this post-cam design was applied to three different surface conformities for conforming, medial pivot, and subject anatomy mimetic tibiofemoral surfaces. We evaluated the femoral rollback, internal-external rotation, and quadriceps muscle force under a deep-knee-bend condition. Results The three different tibiofemoral conformities showed that the convex post provided the most natural-knee-like femoral rollback. This was also observed in internal rotation. In surface conformity, subject anatomy mimetic tibiofemoral surfaces showed the most natural -knee-like kinematics and quadriceps force. Conclusions This study confirmed that convex post design and subject anatomy mimetic tibiofemoral surfaces provided the most natural-knee-like kinematics. This study suggested that post-cam design and tibiofemoral surface conformity should be considered in conventional and customized TKA.

Background Component design is one of the contributory factors affecting the postoperative flexion angle. The purpose of this study was to compare short-term outcomes of flat surface and medial pivot designs in posterior cruciate-retaining (CR) total knee arthroplasty (TKA). Methods A retrospective, case-control, and observational cohort study consisted of matched-pairs of the flat surface design (Hi-Tech Knee II) and the medial pivot design (FINE Knee) in CR-TKA with a two-year follow-up period. Results Hi-Tech Knee II and FINE knee groups each included 7 males and 38 females. Surgical time was significantly shorter in the FINE Knee group than in the Hi-Tech Knee II group (104.8 min versus 154.9 min, p = 0.001). Estimated total blood loss was significantly lower in the FINE Knee group than in the Hi-Tech Knee II group (654 ml versus 1158 ml, p = 0.001). The postoperative flexion angle was significantly better in the FINE Knee group than in the Hi-Tech Knee II group (119.3 degrees versus 112.5 degrees), and was positively correlated with the preoperative flexion angle. Postoperative Knee Society scores were significantly better in the FINE Knee group than in the Hi-Tech Knee II group (93.0 points versus 85.0 points, p = 0.001), especially for postoperative pain relief (46.0 points versus 39.0 points out of 50, p = 0.001). Complications were not observed in either group over a two-year follow-up period. Conclusion The short-term outcome of the medial pivot design used in CR-TKA was more favorable than the flat surface design, especially for surgical time, estimated total blood loss, postoperative flexion angle, and knee pain. Electronic supplementary material The online version of this article (10.1186/s12891-018-2138-z) contains supplementary material, which is available to authorized users.

A new philosophy of science and medicine had spread throughout the 17th-century Italy: the “Scientific Revolution.” Giovanni Alfonso Borelli (1608–1679) was one of the most charismatic and brilliant scientists of his generation in Europe. He extended to biology the rigorous analytic methods developed by his indirect mentor Galileo in the field of mechanics. In his masterpiece “De Motu Animalium,” Borelli analyzed structure, motion, balance, and forces concerning almost all the principal joints of the human body, in static and dynamic situations. In particular, he accurately studied the anatomy and biomechanics of the knee joint. He sustained that femoral condyles shift backward during flexion, allowing a wider range of movement. Furthermore, he observed that, when the knee flexes, the lateral condyle moves backward more than the medial condyle: this concept is nowadays known as medial pivoting. The aim of this article is to describe the life and work of this important Italian scientist and to present his unrecognized contribution to modern knee biomechanics.

Background:Traditional total knee implants designs, usually, are not able to reproduce the physiological kinematics of the knee, leaving almost 20% of the patients, those who underwent a total knee arthroplasty (TKA), not fully satisfied. Modern inserts are nowadays designed with a fully congruent medial compartment to reproduce the normal medial pivoting biomechanics of the knee. The aim of this article was to evaluate preliminary clinical improvement using the Medial Congruent (MC) insert as specific level of constraint.Materials and methods:A total of 10 consecutive patients have been enrolled in this study and treated using an MC tibial polyethylene insert. The Oxford Knee Score (OKS) and the Knee Society Score (KSS) have been assessed preoperatively and at 3-month, 6-month, and 1-year follow-up (FU) and used as validated measurements to evaluate early clinical improvements. Postoperative radiological examination was reviewed looking for radiolucent lines or loosening of the components.Results:Average improvement in OKS was from 19.5 to 41.2, whereas KSS improved with an average score from 64.7 preoperatively to 167.5 at the final FU showing good to excellent results in 95% of the treated knees. Evaluating the range of motion, the average maximum active movement was 124° and none of the patients needing for a revision surgery or manipulation under anesthesia. No complications were observed at the final FU as septic or aseptic loosening or vascular or neurologic injury.Discussion and conclusions:Medial Congruent insert showed good to excellent clinical results at 1-year FU. Range of motion and subjective outcomes were satisfying and comparable with results obtained in literature using traditional TKA design.