Posterior Draw Research Articles

Suture Tape Augmentation Improves Posterior Stability After Isolated Posterior Cruciate Ligament Reconstruction Using Hamstring Tendon Autograft With Single-Bundle Transtibial Technique

PurposeThe purpose of this study was to assess whether posterior cruciate ligament reconstruction (PCLR) suture tape augmentation can yield more stability after isolated PCLR. MethodsA prospective database was retrospectively reviewed to identified patients that underwent primary isolated PCLR (control study) or isolated PCLR with suture tape augmentation (study group) from January 2016 to September 2020. the subjective International Knee Documentation Committee Subjective (IKDC) Knee, Lysholm and Tegner scores, posterior draw tests, as well as posterior stress radiographs and return to sports activity rates. The minimal clinically important difference (MCID) was used to evaluate the clinically relevance (subjective IKDC, Lysholm and Tegner scores). Results59 were included in this analysis (28 patients in control group, 31 patients in study group). The average length of follow-up was similar between the study and control groups (48.6 vs 47.9months; p=0.800). Knee function, in terms of subjective IKDC (study vs. control: 85.1±6.4 vs. 79.8±6.4; P=0.002), Lysholm (study vs. control: 86.3±7.4 vs. 80.8±7.4; P=0.005) and Tegner (study vs. control: 7.0±1.4 vs. 5.6±1. 7; P=0.006) scores, was significantly improved in the study group. However, the differences between control group and study group were less than the MCID in the subjective IKDC score and Lysholm score. 21.4% (6/28) and 48.4% of patients (15/31) in the control and study groups, respectively, returned to the preinjury sports activity levels (P=0.031). At last follow-up, the mean side-to-side differences in posterior laxity was significantly improved in the study group compared with the control patients (study vs. control: 1.52±0.70 mm vs. 3.17±2.01 mm; p<0.01). ConclusionsPrimary isolated PCLR with suture tape augmentation provides better posterior stability than PCLR without suture tape augmentation at a minimum 2 years follow-up. No differences observed between the groups in the percentage of patients who met or exceeded the MCID in subjective IKDC and Lysholm score.

The posterolateral ligament of the elbow: anatomy and clinical relevance

The posterolateral capsule was recognized in the past as an important structure for elbow stability but was later disregarded. Two recent biomechanical studies demonstrated its role in preventing posterolateral instability, and thus it should be identified as a distinct ligament: the posterolateral ligament (PLL). This study includes 2 parts: an anatomic study of the PLL's footprint and a collection of 5 cases of pathologic lesions of the PLL. Six cadaveric upper limbs were assessed. The attachments of the PLL were dissected, the footprints were marked and photographed, and the 2-dimensional area and length were measured. The mean proximal attachment dimensions were a length of 13 mm and an area of 101 mm2, and the mean distal attachment dimensions were 19 mm and 111 mm2, respectively. There were 2 cases of posterolateral elbow pain in professional cricket bowlers, diagnosed radiographically as enthesopathy of the PLL's proximal attachment on the posterior capitellum, probably due to repeated forced hyperextension of the elbow. Both patients were treated by débridement of the posterior capitellum and reattachment of the PLL, with complete resolution of symptoms. In addition, there were 3 cases of clinical posterolateral rotatory instability in young patients. Two athletes had an isolated acute tear of the PLL, and on physical examination, both had positive posterior draw test results but negative pivot-shift test results. Both underwent elbow arthroscopy and repair of the PLL with resolution of symptoms. The third patient had long-standing recurrent elbow instability, following a failed lateral ulnar collateral ligament reconstruction, in the presence of an Osborne-Cotterill lesion. He underwent revision lateral ulnar collateral ligament reconstruction, bone grafting of the bony lesion, and reattachment of the PLL, with complete resolution of symptomatic posterolateral rotatory instability. The PLL of the elbow has a significant role in the elbow's posterolateral stability. Its footprints were described, and its clinical significance was demonstrated in cases of elbow instability caused by acute ligament tears and elbow pain due to ligament enthesopathy. Surgeons should be aware of this structure and potential pathology related to its injury.

Comparison of Clinical and Radiographic Outcomes According to the Presence or Absence of a Posterior Draw Force during Graft Fixation in Anterior Cruciate Ligament Reconstruction.

Background and Objectives: A reduction forced toward the posterior side during graft fixation may help to lessen anterior tibial translation after ACL reconstruction. The purpose was to compare the clinical and radiological outcomes of graft fixation when a posterior draw was used and when it was not used during anterior cruciate ligament (ACL) reconstruction surgery. Materials and Methods: Of 110 patients who had undergone primary arthroscopic ACL reconstruction between January 2017 and August 2020, in all, 76 patients had been operated on without a posterior draw (non-draw group), and 34 patients had received surgery with a posterior draw (draw group). The results of the Lachman test and the pivot-shift test, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) indexes, the Lysholm scores, the International Knee Documentation Committee (IKDC) subjective scores, and side-to-side difference (STSD) on stress radiography were compared between the two groups. Results: The postoperative WOMAC indexes, Lysholm scores, and IKDC subjective scores were similar across both groups. Postoperative STSD (2.4 ± 2.2 for the non-draw group vs. 2.0 ± 2.2 for the draw group; p = 0.319) and change in STSD (3.5 ± 3.5 for preoperative STSD vs. 4.3 ± 4.4 for postoperative STSD; p = 0.295) were not superior in the draw group. Conclusions: The take-home message is that graft fixation with a posterior draw during ACL reconstruction did not result in significantly better postoperative stability. The postoperative clinical outcomes were similar between both groups.

Clinical and functional outcome of isolated posterior cruciate ligament avulsion fractures treated by open reduction and internal fixation

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; PCL ligament avulsion fracture injuries constitute about 3-20% of all the knee injuries. Isolated posterior cruciate ligament injuries are uncommon and often go undiagnosed in acutely injured knees. fracture. In the long run they cause severe functional disability of the knee joint. There is no consensus concerning the optimal surgical treatment approach for these injuries. Our study was to assess the functional and clinical outcome of isolated PCL avulsion fractures with open reduction and internal fixation.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; This is a prospective study of 27 patients with isolated PCL avulsion fractures, done in the department of orthopaedics in RNT medical college over a 2-year period. All were treated with open reduction and internal fixation with 4 mm cannulated cancellous screw and washer. Postoperatively, patient leg was immobilized in posterior POP slab for 2 weeks, allowing toe touch weight bearing. All patients were regularly followed-up. 3 cases of post operative wound infection were detected.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Of the 27 patients, there were 19 males and 8 females. All the cases showed good fracture union in an average of 12 weeks post operatively. In the first 6 weeks, all of them acquired an average knee flexion of 90 degrees and by 3 months, all of them had 125 degrees of free flexion possible.2 cases showed negative posterior draw sign. The knee scoring system assessment showed 21 cases of excellent result, 4 cases of good result and 2 cases of fair result.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Though rare, PCL avulsion fractured are to be managed properly and treated surgically. PCL tibial avulsion fractures treated through Burk and Schaffer approach with open reduction and internal fixation produces good results.&lt;/p&gt;

Pivotal discrepancy measures for Bayesian modelling of spatio-temporal data

Within the field of geostatistics, Gaussian processes are a staple for modelling spatial and spatio-temporal data. Statistical literature is rich with estimation methods for the mean and covariance of such processes (in both frequentist and Bayesian contexts). Considerably less attention has been paid to developing goodness-of-fit tests for assessment of model adequacy. Jun et al. (Environmetrics 25(8):584–595, 2014) introduced a statistical test that uses pivotal discrepancy measures to assess goodness-of-fit in the Bayesian context. We present a modification and generalization of their statistical test. The initial method involves spatial partitioning of the data, followed by evaluation of a pivotal discrepancy measure at each posterior draw to obtain a posterior distribution of pivotal statistics. Order statistics from this distribution are used to obtain approximate p-values. Jun et al. (Environmetrics 25(8):584–595, 2014) use arbitrary partitions based on pre-existing spatial boundaries. The partitions are made to be of equal size. Our contribution is two-fold. We use K-means clustering to create the spatial partitions and we generalise Jun et al.’s approach to incorporate unequal partition sizes. Observations from a spatial or spatio-temporal process are partitioned using an appropriate feature vector that incorporates the geographic location of the observations into subsets (not necessarily of the same size). The method’s viability is illustrated in a simulation study, and in an application to hoki (Macruronus novaezelandiae) catch data from a survey of the sub-Antarctic region.

Maximum Likelihood Multiple Imputation: Faster Imputations and Consistent Standard Errors Without Posterior Draws

Multiple imputation (MI) is a method for repairing and analyzing data with missing values. MI replaces missing values with a sample of random values drawn from an imputation model. The most popular form of MI, which we call posterior draw multiple imputation (PDMI), draws the parameters of the imputation model from a Bayesian posterior distribution. An alternative, which we call maximum likelihood multiple imputation (MLMI), estimates the parameters of the imputation model using maximum likelihood (or equivalent). Compared to PDMI, MLMI is faster and yields slightly more efficient point estimates. A past barrier to using MLMI was the difficulty of estimating the standard errors of MLMI point estimates. We derive, implement and evaluate three consistent standard error formulas: (1) one combines variances within and between the imputed datasets, (2) one uses the score function and (3) one uses the bootstrap with two imputations of each bootstrapped sample. Formula (1) modifies for MLMI a formula that has long been used under PDMI, while formulas (2) and (3) can be used without modification under either PDMI or MLMI. We have implemented MLMI and the standard error estimators in the mlmi and bootImpute packages for R.

Joint Bayesian Inference about Impulse Responses in VAR Models

Structural VAR models are routinely estimated by Bayesian methods. Several recent studies have voiced concerns about the common use of posterior median (or mean) response functions in applied VAR analysis. In this paper, we show that these response functions can be misleading because in empirically relevant settings there need not exist a posterior draw for the impulse response function that matches the posterior median or mean response function, even as the number of posterior draws approaches infinity. As a result, the use of these summary statistics may distort the shape of the impulse response function which is of foremost interest in applied work. The same concern applies to error bands based on the upper and lower quantiles of the marginal posterior distributions of the impulse responses. In addition, these error bands fail to capture the full uncertainty about the estimates of the structural impulse responses. In response to these concerns, we propose new estimators of impulse response functions under quadratic loss, under absolute loss and under Dirac delta loss that are consistent with Bayesian statistical decision theory, that are optimal in the relevant sense, that respect the dynamics of the impulse response functions and that are easy to implement. We also propose joint credible sets for these estimators derived under the same loss function. Our analysis covers a much wider range of structural VAR models than previous proposals in the literature including models that combine short-run and long-run exclusion restrictions and models that combine zero restrictions, sign restrictions and narrative restrictions.

Joint Bayesian Inference about Impulse Responses in VAR Models

Structural VAR models are routinely estimated by Bayesian methods. Several recent studies have voiced concerns about the common use of posterior median (or mean) response functions in applied VAR analysis. In this paper, we show that these response functions can be misleading because in empirically relevant settings there need not exist a posterior draw for the impulse response function that matches the posterior median or mean response function, even as the number of posterior draws approaches infinity. As a result, the use of these summary statistics may distort the shape of the impulse response function which is of foremost interest in applied work. The same concern applies to error bands based on the upper and lower quantiles of the marginal posterior distributions of the impulse responses. In addition, these error bands fail to capture the full uncertainty about the estimates of the structural impulse responses. In response to these concerns, we propose new estimators of impulse response functions under quadratic loss, under absolute loss and under Dirac delta loss that are consistent with Bayesian statistical decision theory, that are optimal in the relevant sense, that respect the dynamics of the impulse response functions and that are easy to implement. We also propose joint credible sets for these estimators derived under the same loss function. Our analysis covers a much wider range of structural VAR models than previous proposals in the literature including models that combine short-run and long-run exclusion restrictions and models that combine zero restrictions, sign restrictions and narrative restrictions.

Hierarchical Bayesian modeling for predicting ordinal responses of personalized thermal sensation: Application to outdoor thermal sensation data

A concept known as ‘nudge’ has recently received attention in many application domains. It implies influencing the behavior and decision-making of individuals by making indirect suggestions through the presentation of adequate information. We apply such a perspective to improve the value of a space. It can be measured by the number of visitors, and the predicted thermal sensation is considered as information offered to potential visitors. In the present study, we explain how to generate the information required for a successful nudge. This information must be specifically tailored towards personalized characteristics, rather than a one-fits-all approach. This study presents a new data-driven method for predicting individuals' thermal sensation by formulating the effect of both measured (thermal) and non-measured factors on thermal sensation votes. The proposed model is explicitly encoded based on a major premise that “different individuals have different thermal sensation characteristics; however, all individuals also have a common trend.” The inference model uses a Bayesian approach, and is hierarchically structured to represent dependencies across model parameters of the personalized characteristics of individual-level and the typical trend of group-level thermal sensations. The Markov chain Monte Carlo approach is used to approximate the posterior distribution and draw inferences on the model parameters. The results, based on data collected from outdoor spaces, show that the proposed model provides accurate predictions for personalized thermal sensation and improves the efficiency of parameter estimates. Our approach provides fresh insight into statistical models for predicting thermal sensation.

A DIAGNOSTIC TOOL FOR CHECKING ASSUMPTIONS OF REGRESSION MIXTURE MODELS.

Regression mixture models are becoming more widely used in applied research. It has been recognized that these models are quite sensitive to underlying assumptions, yet many of these assumptions are not directly testable. We discuss a diagnostic tool based on reconstructed residuals that can help uncover violations of model assumptions. These residuals are found by using the posterior probability of class membership to assign, based on a multinomial distribution, a class to each observation. Standard residual checks can be applied to these posterior draw residuals to explore violations of the model assumptions. We present several illustrations of the diagnostic tool.

The contribution of the posterolateral capsule to elbow joint stability: a cadaveric biomechanical investigation

Elbow posterolateral rotatory instability occurs after an injury to the lateral collateral ligament complex (LCLC) in isolation or in association with an osteochondral fracture of the posterolateral margin of the capitellum (Osborne-Cotterill lesion [OCL]). The contribution to elbow stability of the posterolateral capsule, attached to this lesion, is unknown. This study quantified the displacement of the radial head on simulated posterior draw with sectioning of the posterior capsule (a simulated OCL) or LCLC. Biomechanical testing of the elbow was performed in 8 upper limb cadavers. With the elbow 0°, 30°, 60°, and 90° degrees of flexion, posterior displacement of the radius was measured at increments of a load of 5 N up to 50 N. A simulated OCL and LCLC injury was then performed. A simulated OCL results in significantly more displacement of the radial head compared with the intact elbow at 30° to 60° of elbow flexion. LCLC resection confers significantly more displacement. An OCL after LCLC resection does not create further displacement. The degree of radial head displacement is greater after a simulated OCL at 30° to 60° of flexion compared with the intact elbow with the same load but not as great as seen with sectioning of the LCLC. This study suggests that the posterior capsule attaching to the back of the capitellum is important to elbow stability and should be identified as the Osborne-Cotterill ligament. Clinical studies are required to determine the importance of these biomechanical findings.

The patella: A mechanical determinant of coordination during vertical jumping

The patella is traditionally understood to be a “joint spacer” that increases the moment arm of the patellar tendon. This characterisation is unsatisfactory as it fails to explain the more interesting characteristics of the patella: 1) that the changing pivot point of the patella causes the ratio of quadriceps to patellar tendon force to almost double as the knee flexes; 2) that the patellar tendon exerts an anteriorly directed force on the tibia when the knee is extended but this switches to a posterior draw as the knee flexes; and 3) that the presence of the patella allows the quadriceps to exert different moments on the femur and tibia. Here, I use a simple, model of the geometry of the knee to calculate the changes in the effective moment arms of the quadriceps on the femur and tibia as the knee extends during vertical jumping. These effective moment arms are then contrasted with the actual changes in moments seen during a vertical jump. This analysis demonstrates that the changing geometry of the knee alone can explain 93% (p < 0.05) of the variance in the characteristic femoral to tibial pattern of moment production during jumping – suggesting that the mechanics of the patella have a crucial influence on the coordination of jumping. These results lend support to the contention that mechanical considerations play a pivotal role in the control of movement by creating a stronger imperative towards a particular movement solution than might be suggested by the large degree of redundancy in the neuromuscular system. This idea is consistent with dynamic systems theories of motor control, i.e. the mechanical structure of the musculoskeletal system itself is important in the organisation of movement (so called mechanical intelligence).

Approximate Bayesian Computation in the estimation of the parameters of the Forbush decrease model

Realistic modeling of the complicated phenomena as Forbush decrease of the galactic cosmic ray intensity is a quite challenging task. One aspect is a numerical solution of the Fokker-Planck equation in five-dimensional space (three spatial variables, the time and particles energy). The second difficulty arises from a lack of detailed knowledge about the spatial and time profiles of the parameters responsible for the creation of the Forbush decrease. Among these parameters, the central role plays a diffusion coefficient. Assessment of the correctness of the proposed model can be done only by comparison of the model output with the experimental observations of the galactic cosmic ray intensity. We apply the Approximate Bayesian Computation (ABC) methodology to match the Forbush decrease model to experimental data. The ABC method is becoming increasing exploited for dynamic complex problems in which the likelihood function is costly to compute. The main idea of all ABC methods is to accept samples as an approximate posterior draw if its associated modeled data are close enough to the observed one. In this paper, we present application of the Sequential Monte Carlo Approximate Bayesian Computation algorithm scanning the space of the diffusion coefficient parameters. The proposed algorithm is adopted to create the model of the Forbush decrease observed by the neutron monitors at the Earth in March 2002. The model of the Forbush decrease is based on the stochastic approach to the solution of the Fokker-Planck equation.

Bayesian hierarchical joint modeling of repeatedly measured continuous and ordinal markers of disease severity: Application to Ugandan diabetes data.

Modeling of correlated biomarkers jointly has been shown to improve the efficiency of parameter estimates, leading to better clinical decisions. In this paper, we employ a joint modeling approach to a unique diabetes dataset, where blood glucose (continuous) and urine glucose (ordinal) measures of disease severity for diabetes are known to be correlated. The postulated joint model assumes that the outcomes are from distributions that are in the exponential family and hence modeled as multivariate generalized linear mixed effects model associated through correlated and/or shared random effects. The Markov chain Monte Carlo Bayesian approach is used to approximate posterior distribution and draw inference on the parameters. This proposed methodology provides a flexible framework to account for the hierarchical structure of the highly unbalanced data as well as the association between the 2 outcomes. The results indicate improved efficiency of parameter estimates when blood glucose and urine glucose are modeled jointly. Moreover, the simulation studies show that estimates obtained from the joint model are consistently less biased and more efficient than those in the separate models.

A Pattern-Mixture Model with Nonfuture Dependence and Shift in Current Missing Values

For incomplete continuous longitudinal data with a monotone pattern, we study a pattern-mixture model which assumes that missingness only depends on observed data and the current missing value, and that the conditional distribution of the current missing value differ from that of the observed patterns by location and scale shifts. The shift parameters measure the departure from the missing at random mechanism. We show that a numerical or Monte Carlo approximation is needed to obtain the posterior draw of the mean at the final time point as a function of the posterior draw of the observed data model parameters and shift parameters, and that scale shifts have negligible impact on the estimated mean at the final time point. We use multiple imputation to avoid numerical integration and demonstrate that the usual multiple imputation variance estimator is valid for the estimated mean at the final time point when scale shifts are not considered. The multiple imputation method is applied to a clinical study of major depressive disorders.

Neural Structures within Human Meniscofemoral Ligaments: A Cadaveric Study.

Aim. To investigate the existence of neural structures within the meniscofemoral ligaments (MFLs) of the human knee. Methods. The MFLs from 8 human cadaveric knees were harvested. 5 μm sections were H&E-stained and examined under light microscopy. The harvested ligaments were then stained using an S100 monoclonal antibody utilising the ABC technique to detect neural components. Further examination was performed on 60–80 nm sections under electron microscopy. Results. Of the 8 knees, 6 were suitable for examination. From these both MFLs existed in 3, only anterior MFLs were present in 2, and an isolated posterior MFL existed in 1. Out of the 9 MFLs, 4 demonstrated neural structures on light and electron microscopy and this was confirmed with S100 staining. The ultrastructure of these neural components was morphologically similar to mechanoreceptors. Conclusion. Neural structures are present in MFLs near to their meniscal attachments. It is likely that the meniscofemoral ligaments contribute not only as passive secondary restraints to posterior draw but more importantly to proprioception and may therefore play an active role in providing a neurosensory feedback loop. This may be particularly important when the primary restraint has reduced function as in the posterior cruciate ligament—deficient human knee.

The Bias and Efficiency of Incomplete-Data Estimators in Small Univariate Normal Samples

Widely used methods for analyzing missing data can be biased in small samples. To understand these biases, we evaluate in detail the situation where a small univariate normal sample, with values missing at random, is analyzed using either observed-data maximum likelihood (ML) or multiple imputation (MI). We evaluate two types of MI: the usual Bayesian approach, which we call posterior draw (PD) imputation, and a little used alternative, which we call ML imputation, in which values are imputed conditionally on an ML estimate. We find that observed-data ML is more efficient and has lower mean squared error than either type of MI. Between the two types of MI, ML imputation is more efficient than PD imputation, and ML imputation also has less potential for bias in small samples. The bias and efficiency of PD imputation can be improved by a change of prior.

A Bayesian Approach to Diameter Estimation in the Diameter Control System of Silicon Single Crystal Growth

In the diameter control system of silicon single crystal growth, the variation of the diameter of the aperture (i.e., a halo with high brightness, which appears at the junction of a solid crystal and a liquid solution) is consistent with the change in the diameter of the growing crystal. Therefore, the diameter of the aperture can be used as a control variable for adjusting the casting speed and temperature so that the grown silicon single crystal approximates to a perfect cylinder. It is obvious that the measured diameter of the current aperture plays an important role in the diameter control system of silicon single crystal growth. In fact, the obtained aperture image from a charge-coupled device camera is a halo of ellipses instead of circles. To estimate the diameter (or radius) of the elliptical aperture, we propose a Bayesian approach, in which a Bayesian model is derived to define a posterior distribution for the unknown parameters. This distribution is too complicated for analytical extraction of moments to sample directly. An efficient computational algorithm based on a Markov chain Monte Carlo method is derived to estimate the posterior distribution and draw samples from the distribution. Comparing with the classical Hough transform-based algorithm and the direct least-squares fitting method, the proposed algorithm has higher estimation accuracy. Some simulated and experimental examples are presented to illustrate the algorithm's effectiveness.

Treatment of Posterior Cruciate Ligament Tibial Avulsion Fractures Through a Modified Open Posterior Approach: Operative Technique and 12- to 48-Month Outcomes

To report clinical and functional outcomes following fixation of tibial posterior cruciate ligament (PCL) avulsion fractures through a modified open posterior approach when combined with a rehabilitation program emphasizing early range of motion. Retrospective case series. Level I trauma center. From March 4, 2000 to May 8, 2003, there were 16 cases of PCL tibial avulsion injuries presented to our institution, with 10 patients available for follow up at 12 to 48 months (mean 28 months). Fixation of tibial PCL avulsion fractures was with a lag screw and washer placed through a modified open posterior approach. Range of motion was begun on postoperative day 1. Clinical stability, range of motion, gastrocnemius muscle strength, radiographic appearance, and each patient's overall health-related quality of life (using the musculoskeletal functional assessment tool) were evaluated at final follow up. The average musculoskeletal functional assessment score was 14. (Musculoskeletal functional assessment scores range from 0-100, with higher scores indicating poorer function.) All patients achieved union of their fracture and had clinically stable knees at the latest follow-up. Flexion difference greater than 10 degrees (P = 0.16), extension difference greater than 2 degrees (P = 0.38), and heel raise difference more than 8 repetitions (P = 0.23) were not demonstrated in comparison to the normal side. Treatment of tibial PCL avulsion fractures, which includes fixation through a modified open posterior approach and early postoperative range of motion, results in healing of the fracture, good functional outcomes, stability to posterior draw testing, and does not lead to gastrocnemius weakness or significant range of motion deficits at 12 to 48 months postoperatively.

Posterior stability in fixed-bearing versus mobile-bearing total knee replacement: a radiological comparison of two implants

Posterior tibial translation in total knee replacement (TKR) could be one major factor for PE wear, delamination and loosening of the tibial component due to increased shear forces and component-to-bone interface stress. The aim of this study was to assess the posterior stability of two different designs of posterior cruciate ligament (PCL) substituting TKR. In this non-randomised consecutive study 43 patients underwent TKR for primary osteoarthritis. Twenty-six patients in group FB received a deep-dished fixed-bearing Duracon TKR (Howmedica, Rutherford, NJ, USA) and 17 patients in group MB a deep-dished rotating mobile-bearing Duracon TKR. In both groups the PCL was resected. All patients had pre- and postoperative kneeling stress radiographs and were clinically evaluated with the Knee Society Score. Posterior tibial translation was measured by tracing a line along the posterior tibial cortex in relationship to the posterior edge of Blumensaat's line. The average follow-up was 13 months for group FB and 11 months for group MB. Both groups demonstrated a statistical significant increase of the mean posterior tibial translation on kneeling stress X-ray of 4.1 mm (group FB) (P < 0.001) and of 6.6 mm (group MB) (P < 0.001) compared to pre-operative. Group MB showed a significant higher posterior draw (P < 0.008). Clinical assessment using the Knee Society Score showed comparable short-term results. The deep-dished fixed-bearing TKR as well as the deep-dished rotating mobile-bearing TKR demonstrated significant posterior tibial translation on kneeling stress X-ray. It remains to be determined what amount of joint play is optimal for clinical function and to minimise shear forces and PE wear. Moreover the amount of posterior tibial translation was significantly higher with the mobile-bearing insert, which could be directly related to the asymmetric rotational mobility of the tibial insert. A long-term follow-up is necessary to investigate whether our findings correlate with the survival-rate of these specific implants.