The relation between meniscal dynamics and tibiofemoral kinematics

Over the past 30 years, research on meniscal kinematics has been limited by challenges such as low-resolution imaging and capturing continuous motion from static data. This study aimed to develop a computational knee model that overcomes these limitations and enables the continuous assessment of meniscal dynamics. A high-resolution MRI dataset (n = 11) was acquired in 4 configurations of knee flexion. In each configuration, the menisci were modeled based on the underlying osseous anatomy. Principal Polynomial Shape Analysis (PPSA) was employed for continuous meniscal modeling. Maximal medial anterior horn displacement occurred in 60° of flexion, equaling 6.24 mm posteromedial, while the posterior horn remained relatively stable. At 90° of flexion, the lateral anterior and posterior horn displaced posteromedially, amounting 5.70 mm and 6.51 mm respectively. The maximal observed Average Surface Distance (ASD) equaled 0.70 mm for lateral meniscal modeling in 90° of flexion. Based on our results, a strong relation between meniscal dynamics and tibiofemoral kinematics was confirmed. Expanding on static meniscal modeling and employing PPSA, we derived and validated a standardized and systematic methodological workflow.

Inhibitory control of locomotor statistics in walking Drosophila

In order to forage for food, many animals regulate not only specific limb movements but the statistics of locomotor behavior over time, for example switching between long-range dispersal behaviors and more localized search depending on the availability of resources. How pre-motor circuits regulate such locomotor statistics is not clear. Here we took advantage of the robust changes in locomotor statistics evoked by attractive odors in walking Drosophila to investigate their neural control. We began by analyzing the statistics of ground speed and angular velocity during three well-defined motor regimes: baseline walking, upwind running during odor, and search behavior following odor offset. We find that during search behavior, flies adopt higher angular velocities and slower ground speeds, and tend to turn for longer periods of time in one direction. We further find that flies spontaneously adopt periods of different mean ground speed, and that these changes in state influence the length of odor-evoked runs. We next developed a simple physiologically-inspired computational model of locomotor control that can recapitulate these statistical features of fly locomotion. Our model suggests that contralateral inhibition plays a key role both in regulating the difference between baseline and search behavior, and in modulating the response to odor with ground speed. As the fly connectome predicts decussating inhibitory neurons in the lateral accessory lobe (LAL), a pre-motor structure, we generated genetic tools to target these neurons and test their role in behavior. Consistent with our model, we found that activation of neurons labeled in one line increased curvature. In a second line labeling distinct neurons, activation and inactivation strongly and reciprocally regulated ground speed and altered the length of the odor-evoked run. Additional targeted light activation experiments argue that these effects arise from the brain rather than from neurons in the ventral nerve cord, while sparse activation experiments argue that speed control in the second line arises from both LAL neurons and a population of neurons in the dorsal superior medial protocerebrum (SMP). Together, our work develops a biologically plausible computational architecture that captures the statistical features of fly locomotion across behavioral states and identifies potential neural substrates of these computations.

Poster Session: Spatial-frequency-selective enhancement of visual sensitivity from saccade dynamics

Eye movements transform a spatial scene into luminance modulations on the retina. Recent work has shown that this transformation is highly structured: within human temporal sensitivity, saccades deliver power that increases in proportion to spatial frequency (SF) up to a critical frequency and remains constant beyond that. Importantly, the critical SF increases with decreasing amplitude. Therefore, at sufficiently low SFs, larger saccades effectively deliver stronger input signals to the retina. Here we tested whether this input reformatting has the predicted perceptual consequences, by examining how large and small saccades (6o & 1o) affect contrast sensitivity. We measured relative sensitivity at two SFs: a reference (0.5 cpd), equal to the critical SF for the small saccade, and a probe at either a lower or higher SF (0.1/2.5 cpd). We predicted that large saccades enhance visibility only when the probe has a lower SF than the reference. Subjects (N=7) made instructed saccades while presented with a plaid of overlapping orthogonal gratings at the two SFs and reported which grating was more visible. Results closely follow theoretical predictions: psychometric functions following small and large saccades only differed with the lower SF probe, in which case the larger saccade significantly enhanced visibility. In sum, saccades enable selectivity not only in the spatial domain, but also in the spatial-frequency domain.

Bicruciate retaining total knee arthroplasty: current state and future promise

Total knee arthroplasty (TKA) is a well-known surgical procedure performed to address end stage osteoarthritis. The main goal is to relieve pain, recover articular function and return to normal function as soon as possible. Over the years it is frequently performed in the elderly, but lately there is an increased demand in a younger and more active population. Up to 25% of patients feel dissatisfied about their TKA. The anterior cruciate ligament (ACL) is considered the main anteroposterior stabilizer of the knee; nevertheless the ACL is usually sacrificed during conventional TKA. Research shows this might be an unnecessary sacrifice in certain cases. The considerable dissatisfaction rate in mainly high-demanding patients, together with the literature reports on the importance of the ACL function, were the two main reasons for the development of bicruciate retaining (BCR) total knee arthroplasty. BCR TKA may offer superior knee kinematics and proprioception, through anterior cruciate ligament preservation, but requires a higher level of attention to obtain an accurate and precise component orientation to reach proper ligamentous balancing and restore the native knee biomechanics. Many surgeons abandoned its use due to its challenging technique and inconsistent results. Recent new BCR implant designs are promising. This systematic literature review aims to summarize the current state of BCR TKA and what to expect in the future.

Factors Influencing Outcome of Orbital Floor Reconstruction

Introduction  Orbital floor fractures are routinely encountered in facial trauma. Many factors influence the final outcome of the orbital floor surgery, time interval and the extent of other facial bone fractures are the two factors which can significantly influence the postoperative outcome following orbital floor reconstruction. Our study aims to find the ideal time for intervention and the association of other factors in the final outcome of orbital floor reconstruction. Methods  A retrospective and prospective cohort study of patients who were operated at Pondicherry Institute of Medical Sciences for orbital floor fractures, between 2011 January and 2017 July. All the data were entered on an Excel work sheet and statistically analyzed. Results  In our study 8 patients (8/29, 27.58%) had diplopia prior to surgery, 5 patients (5/29, 17.24%) had complete recovery following surgery and 3 patients (3/29, 10.34%) had persistence of diplopia postoperatively. Patients with diplopia operated prior to 7 days were found to have significant improvement in postoperative diplopia. Patients with 5 or more facial fractures were found to have persistence of diplopia, infraorbital numbness, and enophthalmos postoperatively. Conclusion  Our study suggests that early intervention, before 7 days improves the outcome in patients with diplopia and provides a better result postoperatively. In our study preoperative diplopia and infraorbital numbness and postoperative persistence of enophthalmos, diplopia, and paresthesia were found more in patients with 5 or more facial bone fractures. Our study suggests a poor postoperative outcome when 5 or more facial bones are fractured.

Personalized statistical modeling of soft tissue structures in the knee

Background and Objective: As in vivo measurements of knee joint contact forces remain challenging, computational musculoskeletal modeling has been popularized as an encouraging solution for non-invasive estimation of joint mechanical loading. Computational musculoskeletal modeling typically relies on laborious manual segmentation as it requires reliable osseous and soft tissue geometry. To improve on feasibility and accuracy of patient-specific geometry predictions, a generic computational approach that can easily be scaled, morphed and fitted to patient-specific knee joint anatomy is presented.

Methods: A personalized prediction algorithm was established to derive soft tissue geometry of the knee, originating solely from skeletal anatomy. Based on a MRI dataset (n = 53), manual identification of soft-tissue anatomy and landmarks served as input for our model by use of geometric morphometrics. Topographic distance maps were generated for cartilage thickness predictions. Meniscal modeling relied on wrapping a triangular geometry with varying height and width from the anterior to the posterior root. Elastic mesh wrapping was applied for ligamentous and patellar tendon path modeling. Leave-one-out validation experiments were conducted for accuracy assessment.

Results: The Root Mean Square Error (RMSE) for the cartilage layers of the medial tibial plateau, the lateral tibial plateau, the femur and the patella equaled respectively 0.32 mm (range 0.14–0.48), 0.35 mm (range 0.16–0.53), 0.39 mm (range 0.15–0.80) and 0.75 mm (range 0.16–1.11). Similarly, the RMSE equaled respectively 1.16 mm (range 0.99–1.59), 0.91 mm (0.75–1.33), 2.93 mm (range 1.85–4.66) and 2.04 mm (1.88–3.29), calculated over the course of the anterior cruciate ligament, posterior cruciate ligament, the medial and the lateral meniscus.

Conclusion: A methodological workflow is presented for patient-specific, morphological knee joint modeling that avoids laborious segmentation. By allowing to accurately predict personalized geometry this method has the potential for generating large (virtual) sample sizes applicable for biomechanical research and improving personalized, computer-assisted medicine.

Wear patterns in knee OA correlate with native limb geometry

Background: To date, the amount of cartilage loss is graded by means of discrete scoring systems on artificially divided regions of interest (ROI). However, optimal statistical comparison between and within populations requires anatomically standardized cartilage thickness assessment. Providing anatomical standardization relying on non-rigid registration, we aim to compare morphotypes of a healthy control cohort and virtual reconstructed twins of end-stage knee OA subjects to assess the shape-related knee OA risk and to evaluate possible correlations between phenotype and location of cartilage loss.

Methods: Out of an anonymized dataset provided by the Medacta company (Medacta International SA, Castel S. Pietro, CH), 798 end-stage knee OA cases were extracted. Cartilage wear patterns were observed by computing joint space width. The three-dimensional joint space width data was translated into a two-dimensional pixel image, which served as the input for a principal polynomial autoencoder developed for non-linear encoding of wear patterns. Virtual healthy twin reconstruction enabled the investigation of the morphology-related risk for OA requiring joint arthroplasty.

Results: The polynomial autoencoder revealed 4 dominant, orthogonal components, accounting for 94% of variance in the latent feature space. This could be interpreted as medial (54.8%), bicompartmental (25.2%) and lateral (9.1%) wear. Medial wear was subdivided into anteromedial (11.3%) and posteromedial (10.4%) wear. Pre-diseased limb geometry had a positive predictive value of 0.80 in the prediction of OA incidence (r 0.58, p < 0.001).

Conclusion: An innovative methodological workflow is presented to correlate cartilage wear patterns with knee joint phenotype and to assess the distinct knee OA risk based on pre-diseased lower limb morphology. Confirming previous research, both alignment and joint geometry are of importance in knee OA disease onset and progression.

Prefrontal feature representations drive memory recall

Memory formation involves binding of contextual features into a unitary representation1-4, whereas memory recall can occur using partial combinations of these contextual features. The neural basis underlying the relationship between a contextual memory and its constituent features is not well understood; in particular, where features are represented in the brain and how they drive recall. Here, to gain insight into this question, we developed a behavioural task in which mice use features to recall an associated contextual memory. We performed longitudinal imaging in hippocampus as mice performed this task and identified robust representations of global context but not of individual features. To identify putative brain regions that provide feature inputs to hippocampus, we inhibited cortical afferents while imaging hippocampus during behaviour. We found that whereas inhibition of entorhinal cortex led to broad silencing of hippocampus, inhibition of prefrontal anterior cingulate led to a highly specific silencing of context neurons and deficits in feature-based recall. We next developed a preparation for simultaneous imaging of anterior cingulate and hippocampus during behaviour, which revealed robust population-level representation of features in anterior cingulate, that lag hippocampus context representations during training but dynamically reorganize to lead and target recruitment of context ensembles in hippocampus during recall. Together, we provide the first mechanistic insights into where contextual features are represented in the brain, how they emerge, and how they access long-range episodic representations to drive memory recall.

Prolonged Unconsciousness is Common in COVID-19 and Associated with Hypoxemia

OBJECTIVE

The purpose of this study was to estimate the time to recovery of command-following and associations between hypoxemia with time to recovery of command-following.

METHODS

In this multicenter, retrospective, cohort study during the initial surge of the United States' pandemic (March-July 2020) we estimate the time from intubation to recovery of command-following, using Kaplan Meier cumulative-incidence curves and Cox proportional hazard models. Patients were included if they were admitted to 1 of 3 hospitals because of severe coronavirus disease 2019 (COVID-19), required endotracheal intubation for at least 7 days, and experienced impairment of consciousness (Glasgow Coma Scale motor score <6).

RESULTS

Five hundred seventy-one patients of the 795 patients recovered command-following. The median time to recovery of command-following was 30 days (95% confidence interval [CI] = 27-32 days). Median time to recovery of command-following increased by 16 days for patients with at least one episode of an arterial partial pressure of oxygen (PaO2 ) value ≤55 mmHg (p < 0.001), and 25% recovered ≥10 days after cessation of mechanical ventilation. The time to recovery of command-following  was associated with hypoxemia (PaO2  ≤55 mmHg hazard ratio [HR] = 0.56, 95% CI = 0.46-0.68; PaO2  ≤70 HR = 0.88, 95% CI = 0.85-0.91), and each additional day of hypoxemia decreased the likelihood of recovery, accounting for confounders including sedation. These findings were confirmed among patients without any imagining evidence of structural brain injury (n = 199), and in a non-overlapping second surge cohort (N = 427, October 2020 to April 2021).

INTERPRETATION

Survivors of severe COVID-19 commonly recover consciousness weeks after cessation of mechanical ventilation. Long recovery periods are associated with more severe hypoxemia. This relationship is not explained by sedation or brain injury identified on clinical imaging and should inform decisions about life-sustaining therapies. ANN NEUROL 2022;91:740-755.

Personalised statistical modelling of soft tissue structures in the ankle

BACKGROUND AND OBJECTIVE

Revealing the complexity behind subject-specific ankle joint mechanics requires simultaneous analysis of three-dimensional bony and soft-tissue structures. 3D musculoskeletal models have become pivotal in orthopedic treatment planning and biomechanical research. Since manual segmentation of these models is time-consuming and subject to manual errors, (semi-) automatic methods could improve the accuracy and enlarge the sample size of personalised 'in silico' biomechanical experiments and computer-assisted treatment planning. Therefore, our aim was to automatically predict ligament paths, cartilage topography and thickness in the ankle joint based on statistical shape modelling.

METHODS

A personalised cartilage and ligamentous prediction algorithm was established using geometric morphometrics, based on an 'in-house' generated lower limb skeletal model (N = 542), tibiotalar cartilage (N = 60) and ankle ligament segmentations (N = 10). For cartilage, a population-averaged thickness map was determined by use of partial least-squares regression. Ligaments were wrapped around bony contours based on iterative shortest path calculation. Accuracy of ligament path and cartilage thickness prediction was quantified using leave-one-out experiments. The novel personalised thickness prediction was compared with a constant cartilage thickness of 1.50 mm by use of a paired sample T-test.

RESULTS

Mean distance error of cartilage and ligament prediction was 0.12 mm (SD 0.04 mm) and 0.54 mm (SD 0.05 mm), respectively. No significant differences were found between the personalised thickness cartilage and segmented cartilage of the tibia (p = 0.73, CI [-1.60 .10^-17, 1.13 .10^-17]) and talus (p = 0.95, CI[ -1.35 .10^-17, 1.28 .10^-17]). For the constant thickness cartilage, a statistically significant difference was found in 89% and 92% of the tibial (p < 0.001, CI [0.51, 0.58]) and talar (p < 0.001, CI [0.33, 0.40]) cartilage area.

CONCLUSIONS

In this study, we described a personalised prediction algorithm of cartilage and ligaments in the ankle joint. We were able to predict cartilage and main ankle ligaments with submillimeter accuracy. The proposed method has a high potential for generating large (virtual) sample sizes in biomechanical research and mitigates technological advances in computer-assisted orthopaedic surgery.

The Nodovenous Shunt and Reduction Surgery for Post-Filarial Lymphedema-Surgical Technique and Clinical Outcomes

Background  Most of the patients in our Indian setting present with grade 4 lymphedema in which no other surgical option is available and in these debilitating cases the nodovenous shunt followed by reduction surgery provides acceptable outcomes. We would like to describe the surgical technique used for the nodovenous shunt procedure and debulking surgery done in post-filarial lymphedema and share our experience with clinical outcomes.

Materials and Methods  This was a descriptive study. The study period was from 2010 to 2019. Patient records were reviewed retrospectively, and the data was analyzed. All patients with post-filarial lymphedema, operated by two surgeons, were studied. The surgical technique was described.

Results  In the study period, 16 patients with lymphedema were treated surgically. The number of procedures done was 32. In 14 of them nodovenous shunt followed by debulking surgery was done. Two of the patients with post-filarial lymphedema had multiple nodules following secondary skin changes and in them sculpting surgery was done following the nodovenous shunt. Most of the patients presented with grade 4 lymphedema. In all the patients there was significant (>5 cm) reduction in limb circumference postoperatively.

Conclusion  Nodovenous shunt followed by reduction surgery for lymphedema is a reliable surgical option to reduce disease morbidity in patients with post-filarial lymphedema.

Can robot-assisted total knee arthroplasty be a cost-effective procedure? A Markov decision analysis

BACKGROUND

Total knee arthroplasty (TKA) is a frequently and increasingly performed surgery in the treatment of disabling knee osteoarthritis. The rising number of procedures and related revisions pose an increasing economic burden on health care systems. In an attempt to lower the revision rate due to component malalignment and soft tissue imbalance in TKA, robotic assistance (RA) has been introduced in the operating theatre. The primary objective of this study is to provide the results of a theoretical, preliminary cost-effectiveness analysis of RA TKA.

METHODS

A Markov state-transition model was designed to model the health status of sixty-seven-year-old patients in need of TKA due to primary osteoarthritis over a twenty-year period following their knee joint replacement. Transitional probabilities and independent variables were extracted from existing literature.

RESULTS

The value attributed to the utility both for primary and revision surgery has the biggest impact on the ICER, followed by the rate of successful primary surgery and the cost of RA-technology. Only 2.18% of the samples yielded from the probabilistic sensitivity analysis proved to be cost-effective (threshold set at $50000/QALY). A calculated surgical volume of at least 253 cases per robot per year is needed to prove cost-effective taking the predetermined parameter values into account.

CONCLUSION

Based upon transitional probabilities and independent variables derived from existing studies, RA TKA may be cost-effective at a surgical volume of 253 cases per robot per year when compared to conventional TKA.

Second Metacarpal Base Avulsion Fracture Due to the Extensor Carpi Radialis Longus Tendon: A Case Report

Fracture avulsion injuries of the extensors of the wrist are not common. The most common mode of injury is forced flexion of the hand and wrist with Extensor Carpi Radialis Longus (ECRL) contraction at the same time. These fractures are generally managed by Open Reduction and Internal Fixation (ORIF) along with repair of the ECRL tendon. This modality of management is associated with less chance of complications, makes the joint more stable and has an overall positive result.

Knee joint laxity is restored in a bi-cruciate retaining TKA-design

PURPOSE

The goal is to evaluate the passive stability of a bicruciate retaining, cruciate retaining and bicruciate substituting TKA design in relation to the native knee stability in terms of the laxity envelope. A bicruciate retaining knee prosthesis was hypothesized to offer a closer to normal knee stability in vitro.

METHODS

Fourteen cadaveric knee specimens have been tested under passive conditions with and without external loads, involving a varus/valgus and an external/internal rotational torque, distraction/compression force and an anteroposterior shear force. Subsequently, the native knee, bicruciate retaining, cruciate retaining and finally a bicruciate substituting total knee arthroplasty were tested.

RESULTS

Through the range of motion, the width of the varus/valgus and internal/external laxity envelope for the native knee and the bicruciate retaining knee were almost equivalent, whereas the cruciate retaining and the bicruciate substituting knee displayed less laxity and more joint distraction. In all prosthetic knees, an equal anteroposterior laxity was seen for the lateral and medial side whereas in the native knee, a difference in laxity was seen between the stable medial side and the more mobile lateral side.

CONCLUSION

Bicruciate retaining knee prostheses can restore normal laxity and thus have the potential to offer more normal knee function. Restoration of natural peri-articular soft-tissue tension is clinically important because of its obvious effects on joint stability and range of motion. Furthermore, the results of this study could help to establish the ideal ligament tension and laxity in more conventional implants by approaching the normal values for passive knee evaluation as presented here.

Three-dimensional displacement after a medializing calcaneal osteotomy in relation to the osteotomy angle and hindfoot alignment

BACKGROUND

A medializing calcaneal osteotomy is frequently performed to correct adult-acquired flatfoot deformities, but there is lack of data on the associated three-dimensional variables defining the final correction. The aim of this study was to assess the correlation between the pre-operative hindfoot valgus deformity and calcaneal osteotomy angles and the post-operative calcaneal displacement.

METHODS

Weight-bearing CT scans obtained pre- and post-operatively were retrospectively analyzed for sixteen patients. Corresponding three-dimensional bone models were used to measure valgus deformity pre- and post-operatively, inclination of the osteotomy and displacement of the calcaneus. Linear regression was conducted to assess the relationship between these measurements.

RESULTS

On average, the hindfoot valgus changed from 13.1° (±4.6) pre-operatively to 5.7° (±4.3) post-operatively. A mean inferior displacement of 3.2mm (±1.3) was observed along the osteotomy with a mean inclination of 54.6° (±5.6), 80.5° (±10.7), -13.7° (±15.7) in the axial, sagittal and coronal planes, respectively. A statistically significant positive relationship (p<.05, R²=0.6) was found between the pre-operative valgus, the axial osteotomy inclination, and the inferior displacement.

CONCLUSIONS

This study shows that the degree of pre-operative hindfoot valgus and the axial osteotomy angle are predictive factors for the amount of post-operative inferior displacement of the calcaneus. These findings demonstrate the added value of a computer-based pre-operative planning in clinical practice. Level of evidence II Prospective comparative study.

[Retrospective analysis of anti-TIF1gamma, anti-NXP2 and anti-SAE1/2 antibodies carriers at Bordeaux university hospital from November 2014 to February 2017]

INTRODUCTION

Dermatomyositis are rare autoimmune diseases. The discovery of specific antibodies such as the anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies has been associated with specific clinical phenotypes. The recent development of standardized kits based on immunodot method is a progress in dermatomyositis diagnosis. Here, we report the clinical characteristics of patients carrying these antibodies with or without clinical setting of dermatomyositis.

METHODS

This single-center french retrospective study was conducted from November 2014 to February 2017 at Bordeaux university hospital. Patients carrying anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies, detected by immunodot, were included.

RESULTS

Among the 58 patients included, only 10 were finally diagnosed with dermatomyositis. Some form of cancer was found in all anti-TIF1γ antibodies positive patients associated with dermatomyositis. Among the 48 anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies positive patients without clinical phenotype of dermatomyositis, 30 had autoimmune or inflammatory condition and 39 patients presented a significant biological autoimmunity. None of them developed dermatomyositis during the follow-up.

CONCLUSION

The immunodot kit allowed the diagnosis of 10 dermatomyositis. A high number of autoantibody positive patients without dermatomyositis raises the issue of the immunodot's performances in the context of biological autoimmunity.

Weightbearing CT in normal hindfoot alignment - Presence of a constitutional valgus?

BACKGROUND

The normal hindfoot angle is estimated between 2° and 6° of valgus in the general population. These results are solely based on clinical findings and plain radiographs. The purpose of this study is to assess the hindfoot alignment using weightbear CT.

METHODS

Forty-eight patients, mean age of 39.6±13.2 years, with clinical and radiological absence of hindfoot pathology were included. A weightbear CT was obtained and allowed to measure the anatomical tibia axis (TAx) and the hindfoot alignment (HA). The HA was firstly determined using the inferior point of the calcaneus (HA_IC). A density measurement of this area was subsequently performed to analyze if this point concurred with an increased ossification, indicating a higher load exposure. Secondly the HA was determined by dividing the calcaneus in the long axial view (HALA) and compared to the (HA_IC) to point out any possible differences attributed to the measurement method. Reliability was assessed using an intra class correlation coefficient (ICC).

RESULTS

The mean HA_IC equaled 0.79° of valgus±3.2 (ICC_{HA IC}=0.73) with a mean TAx of 2.7° varus±2.1 (ICCTA=0.76). The HALA equaled 9.1° of valgus±4.8 (ICCHA LA=0.71) and differed significantly by a P<0.001 from the HA_IC, which showed a more neutral alignment. Correlation between both was shown to be good by a Spearman's correlation coefficient of 0.74. The mean density of the inferior calcaneal area equaled 271.3±84.1 and was significantly higher than the regional calcaneal area (P<0.001).

CONCLUSIONS

These results show a more neutral alignment of the hindfoot in this group of non-symptomatic feet as opposed to the generally accepted constitutional valgus. This could have repercussion on hindfoot position during fusion or in quantifying the correction of a malalignment. The inferior calcaneus point in this can be used during pre-operative planning of a hindfoot correction as an anatomical landmark due to its shown influence on load transfer.

Flap cover in a patient with severe haemophilia type A

Haemophilia A is a rare haematological disorder due to deficiency of Factor VIII, causing an abnormal coagulation response to injury. In severe haemophilia A, Factor VIII level is < 1%, often manifesting with spontaneous bleeding into joints. Judicious use of recombinant Factor VIII therapy to maintain adequate levels in the intraoperative, immediate and late post-operative periods, together with adjuvant pro-coagulants, can ensure a safe outcome following surgery. We describe the successful management of one such patient suffering from Marjolin's ulcer of the right gluteal region, who needed wide local excision followed by flap cover. A protocol for management of such patients is also suggested. This is the first such case report from the Indian subcontinent, with only a few such published reports from the West.

Clinical outcome in MPFL reconstruction with and without tuberositas transposition

PURPOSE

There are several surgical options for recurrent patella dislocations. As the reconstruction of the medial patellofemoral ligament (MPFL) has been proven to restore stability, it has become more accepted. Aim of this study was to investigate the clinical outcome after MPFL reconstruction as an isolated procedure or in association with a transposition of the tibial tubercle (in case of patella alta or an excessive TT-TG) in a large prospective cohort study. Additionally, the effect on patellar height was analysed radiographically using the Caton-Deschamps index.

METHODS

In a large prospective cohort study of 129 knees in 124 patients (81 females, 48 males, mean age 22.8 ± 7.7 years), 91 knees received primary MPFL reconstruction (group 1) and 38 were a combination with a transposition of the tibial tubercle (group 2). The clinical follow-up was evaluated using KOOS and Kujala scores preoperatively and 1 year postoperatively. Patient satisfaction, complications and revision surgery were recorded.

RESULTS

Overall, Kujala improved significantly from 53.5 (SD 22.7) preoperatively to 74.7 (SD 20.5) postoperatively (p < 0.01). All KOOS subdomains improved significantly (p < 0.01). No significant difference for Kujala score between groups was noticed. Revision rate was (5/129) 3.9 %. Reconstruction was supplemented with a transfer of the tibial tuberosity in (38/129) 29.4 % of the cases and shows a comparable outcome.

CONCLUSION

MPFL reconstruction is a viable treatment option for episodic patellar dislocation. A concomitant tuberositas transposition is useful in selected patients.

LEVEL OF EVIDENCE

I.

External rotation of the femoral component increases asymmetry of the posterior condyles

AIMS

The morphometry of the distal femur was largely studied to improve bone-implant fit in total knee arthroplasty (TKA), but little is known about the asymmetry of the posterior condyles. This study aimed to investigate the dimensions of the posterior condyles and the influence of externally rotating the femoral component on potential prosthetic overhang or under-coverage.

PATIENTS AND METHODS

We analysed the shape of 110 arthritic knees at the time of primary TKA using pre-operative CT scans. The height and width of each condyle were measured at the posterior femoral cut in neutral position, and in 3º and 5º of external rotation, using both central and medial referencing systems. We compared the morphological characteristics with those of 14 TKA models.

RESULTS

In the neutral position, the dimensions of the condyles were nearly equal. Externally rotating the femoral cut by 3º and 5º with 'central referencing' induced width asymmetry > 3 mm in 23 (21%) and 33 (30%) knees respectively, while with 'medial referencing' it induced width asymmetry > 3 mm in 43 (39%) and 75 (68%) knees respectively. The asymmetries induced by rotations were not associated with gender, aetiology or varus-valgus alignment.

CONCLUSION

External rotation may amplify the asymmetry between the medial and lateral condyles, and exacerbate prosthetic overhang, particularly in the superolateral zone. 'Central referencing' guides result in less potential prosthetic overhang than 'medial referencing' guides. Cite this article: Bone Joint J 2017;99-B:894-903.

Six cases of sporadic schwannomatosis: Topographic distribution and outcomes of peripheral nerve tumors

The diagnosis of schwannomatosis is often overestimated and is based on the existence of multiple peripheral nerve tumors composed exclusively of schwannomas, in the absence of clinical signs of neurofibromatosis type 2 (NF2). Sporadic forms are much more frequent than familial forms. The objective of this study was to describe the distribution of peripheral nerve tumors and investigate the outcomes of schwannomas in the context of sporadic schwannomatosis. We conducted a retrospective study of patients who fulfilled clinical diagnostic criteria for sporadic schwannomatosis. Six patients were reviewed with a mean follow-up of 38.5months (27-60months). Patients' demographic, clinical, radiographic, and pathologic data were extracted. All patients underwent slit-lamp examination, enhanced brain magnetic resonance imaging (MRI) and a spinal MRI. Enucleation that preserved nerve continuity was performed in symptomatic patients. On average, patients were 36years of age at the time of diagnosis with no sex predominance. The topographic distribution of the peripheral nerve tumors was always unilateral and most frequently targeted the upper limb. In four cases, the tumors involved the same peripheral nerve exclusively. The average number of nerve tumors observed per patient was 4.7 (2-8). The outcome after enucleation was marked by the systematic appearance of new tumors. After enucleation, no recurrence or malignant transformation was observed at the final follow-up. There was no transition to a NF2 configuration. The absence of neurofibroma and NF2 criteria makes schwannomatosis a diagnosis of exclusion. While a good prognosis can be expected following enucleation, two risks related to neurofibromatosis type 3 (NF3) are worth monitoring: the transition to NF2, particularly in young patients, and the appearance of new tumors.

Measuring hindfoot alignment in weight bearing CT: A novel clinical relevant measurement method

BACKGROUND

A precise pre-operative measurement of hindfoot malalignment is paramount to plan and obtain an accurate surgical correction. Hindfoot alignment is currently determined on standard weightbearing radiographs. However this is hampered by the superposition of the skeletal structures. Recent technology developed weightbearing cone beam CT to overcome this problem. The objective is to introduce a clinically relevant and reproducible method to measure hindfoot alignment on weightbearing CT.

METHODS

Sixty malalignments of the hindfoot were divided in to two groups; group one containing a valgus alignment (n=30) and group two a varus alignment (n=30) of the hindfoot. Imaging techniques used were standard radiographs and a weightbearing CT (pedCAT^®). Following angles were measured by two different authors: standard long axial hindfoot angle both on standard radiographs and on CT, clinical hindfoot, novel hindfoot angle, talar shift (distance from a neutral alignment), tibial inclination angle, talar tilt and subtalar vertical angle on CT.

RESULTS

Hindfoot alignment angles showed to significantly differ from each other (P<0.001). The novel hindfoot alignment angle showed the highest correlation with the clinical measurement method. Correlation of this novel angle with the talar shift showed a Spearman's correlation coefficient=0.87. Interclass correlation coefficient of the novel hindfoot alignment angle=0.72 and was the highest among the hindfoot alignment angles.

CONCLUSION

Weightbearing CT is allows to objectively assess hindfoot alignment. The proposed novel hindfoot alignment angle showed to be both clinically relevant and reproducible as compared to previous methods. The lateral tibiocalcaneal shift, on which the angle is highly correlated to, can help the surgeon in determining how much translation is necessary to obtain a neutral alignment during a calcaneal osteotomy.

LEVEL OF EVIDENCE

Level III: retrospective cohort study.

Injuries can be prevented in contact flag football!

PURPOSE

This original prospective cohort study was conducted in an attempt to significantly reduce the incidence and the severity of injuries in an intervention cohort as compared to a two-season historical cohort, and to provide recommendations to the International Federation of Football (IFAF) pertaining to prevention measures to make the game safer.

METHODS

A total of 1,260 amateur male (mean age: 20.4 ± 3.9 years) and 244 female (mean age: 18.5 ± 1.7 years) players participated in the study. Four prevention measures were implemented: the no-pocket rule, self-fitting mouth guards, ankle braces (for those players with recurrent ankle sprains) and an injury treatment information brochure. All time-loss injuries sustained in game sessions were recorded by the off-the-field medical personnel and followed up by a more detailed phone injury surveillance questionnaire.

RESULTS

There was a 54 % reduction in the total number of injuries and a significant reduction in the incidence rate and incidence proportion between the intervention cohorts as compared to the historical cohort (p < 0.001). There was no statistically significant reduction in the number of injuries in any of the body parts, except for in hand/wrist injuries related to the use of pockets (p < 0.001), as well as the severity of mild-moderate injuries (p < 0.05).

CONCLUSION

This study provided evidence that hand/wrist injuries can be significantly reduced in flag football. Recommendations to the IFAF include strict enforcement of the no-pocket rule, the use of soft headgear, comfortable-fitting ankle braces and mouth guards and additionally, to change game rules concerning blocking.

LEVEL OF EVIDENCE

II.

Morphometric analysis of the distal femur in total knee arthroplasty and native knees

AIMS

Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has largely been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e. whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA.

METHODS

We analysed the shape of 114 arthritic knees at the time of primary TKA using the pre-operative CT scans. The aspect ratio and trapezoidicity ratio were quantified, and the post-operative prosthetic overhang was calculated. We compared the morphological characteristics with those of 12 TKA models.

RESULTS

There was significant variation in both the aspect ratio and trapezoidicity ratio between individuals. Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. Overhang was correlated with the aspect ratio (with a greater chance of overhang in narrow femurs), trapezoidicity ratio (with a greater chance in trapezoidal femurs), and the tibio-femoral angle (with a greater chance in valgus knees).

DISCUSSION

This study shows that rectangular/trapezoidal variability of the distal femur cannot be ignored. Most of the femoral components which were tested appeared to be excessively rectangular when compared with the bony contours of the distal femur. These findings suggest that the design of TKA should be more concerned with matching the trapezoidal/rectangular shape of the native femur.

TAKE HOME MESSAGE

The distal femur is considerably more trapezoidal than most femoral components, and therefore, care must be taken to avoid anterior prosthetic overhang in TKA

Current opinions about coronal plane alignment in total knee arthroplasty: A survey article

PURPOSE

To survey an audience of international knee surgeons about their current opinions on the analysis of coronal knee alignment and their objectives for postoperative alignment in total knee arthroplasty.

METHODS

Survey of 300 surgeons from 32 different countries with an audience response system allowing three possible answers being either a positive or negative answer or an abstention.

RESULTS

Surveyed surgeons perform rarely preoperative and postoperative full leg radiographs and evaluate radiological outcomes more with short films. The main trend in this survey was towards neutral mechanical alignment, however varus alignment is acceptable in constitutional varus patients. This residual varus should be obtained through a femoral varus cut rather than a tibial varus cut. The valgus knee can remain in slight valgus but most of the correction will be performed at the femoral level. The main objective of postoperative alignment in TKA is a joint line parallel to the floor and a central load-bearing axis through the middle of the arthroplasty. Surgeons prefer unicompartmental arthroplasty more for themselves than for their patients in case of medial bone on bone arthritis.

CONCLUSIONS

Neutral mechanical axis with a joint line parallel to the floor and a centrally running load bearing axis remains the central scope of the surveyed surgeons. Because of the literature on residual varus it becomes more acceptable for the orthopaedic community to accept this type of outlier before aiming at a surgical correction.

Treatment of osteochondral lesions in the knee using a cell-free scaffold

The treatment of osteochondral lesions is of great interest to orthopaedic surgeons because most lesions do not heal spontaneously. We present the short-term clinical outcome and MRI findings of a cell-free scaffold used for the treatment of these lesions in the knee. A total of 38 patients were prospectively evaluated clinically for two years following treatment with an osteochondral nanostructured biomimetic scaffold. There were 23 men and 15 women; the mean age of the patients was 30.5 years (15 to 64). Clinical outcome was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner activity scale and a Visual Analgue scale for pain. MRI data were analysed based on the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system at three, 12 and 24 months post-operatively. There was a continuous significant clinical improvement after surgery. In two patients, the scaffold treatment failed (5.3%) There was a statistically significant improvement in the MOCART precentage scores. The repair tissue filled most of the defect sufficiently. We found subchondral laminar changes in all patients. Intralesional osteophytes were found in two patients (5.3%). We conclude that this one-step scaffold-based technique can be used for osteochondral repair. The surgical technique is straightforward, and the clinical results are promising. The MRI aspects of the repair tissue continue to evolve during the first two years after surgery. However, the subchondral laminar and bone changes are a concern.