The lesser trochanter as a cause of hip impingement: pathophysiology and treatment options

Impingement of the lesser trochanter on the ischium or the posterior acetabular rim is not a frequent pathology, but has recently received increased recognition. We have seen 14 cases over a period of 14 years, but concentrate on eight hips showing complex deformities revealing similar characteristics. All eight hips had a residual Perthes or a Perthes-like disease with an elliptically deformed femoral head, but a congurent joint a short or absent femoral neck, a high riding greater trochanter, and a reduced vertical distance between the head and the lesser trochanter. Impingement took place between the lesser trochanter and the ischium or the posteroinferior acetabular border, but was hardly recognisable due to the predominant intraarticular impingement of the nonspherical femoral head and the extraarticular impingement of the greater trochanter. In three cases the impingement showed reproducible subluxation of the hip. While in our hips, excision was the preferred treatment for impingement due to an oversized lesser trochanter, distal advancement was used in the hips with the Perthes morphology; the surgical time was not longer. The overall clinical results in this group however were dominated by a substantial increase in the range of motion (ROM), dependent mainly on the achieved contour of the femoral head and the relative lengthening of the neck. Strength of active hip flexion was normal. Recurrent subluxation disappeared and no complications were recorded.

Molecular Determinants Defining the Triggering Range of Prefusion F Complexes of Canine Distemper Virus

The morbillivirus cell entry machinery consists of a fusion (F) protein trimer that refolds to mediate membrane fusion following receptor-induced conformational changes in its binding partner, the tetrameric attachment (H) protein. To identify molecular determinants that control F refolding, we generated F chimeras between measles virus (MeV) and canine distemper virus (CDV). We located a central pocket in the globular head domain of CDV F that regulates the stability of the metastable, prefusion conformational state of the F trimer. Most mutations introduced into this "pocket'" appeared to mediate a destabilizing effect, a phenotype associated with enhanced membrane fusion activity. Strikingly, under specific triggering conditions (i.e., variation of receptor type and H protein origin), some F mutants also exhibited resistance to a potent morbillivirus entry inhibitor, which is known to block F triggering by enhancing the stability of prefusion F trimers. Our data reveal that the molecular nature of the F stimulus and the intrinsic stability of metastable prefusion F both regulate the efficiency of F refolding and escape from small-molecule refolding blockers. IMPORTANCE: With the aim to better characterize the thermodynamic basis of morbillivirus membrane fusion for cell entry and spread, we report here that the activation energy barrier of prefusion F trimers together with the molecular nature of the triggering "stimulus" (attachment protein and receptor types) define a "triggering range," which governs the initiation of the membrane fusion process. A central "pocket" microdomain in the globular F head contributes substantially to the regulation of the conformational stability of the prefusion complexes. The triggering range also defines the mechanism of viral escape from entry inhibitors and describes how the cellular environment can affect membrane fusion efficiency.

Comfort of two shoulder actuation mechanisms for arm therapy exoskeletons: a comparative study in healthy subjects

Robotic exoskeletons can be used to study and treat patients with neurological impairments. They can guide and support the human limb over a large range of motion, which requires that the movement trajectory of the exoskeleton coincide with the one of the human arm. This is straightforward to achieve for rather simple joints like the elbow, but very challenging for complex joints like the human shoulder, which is comprised by several bones and can exhibit a movement with multiple rotational and translational degrees of freedom. Thus, several research groups have developed different shoulder actuation mechanism. However, there are no experimental studies that directly compare the comfort of two different shoulder actuation mechanisms. In this study, the comfort and the naturalness of the new shoulder actuation mechanism of the ARMin III exoskeleton are compared to a ball-and-socket-type shoulder actuation. The study was conducted in 20 healthy subjects using questionnaires and 3D-motion records to assess comfort and naturalness. The results indicate that the new shoulder actuation is slightly better than a ball-and-socket-type actuation. However, the differences are small, and under the tested conditions, the comfort and the naturalness of the two tested shoulder actuations do not differ a lot.

The course of radiographic loosening, pain and functional outcome around the first revision of a total hip arthroplasty

Background: The published data on pain and physical function before and after revision of total hip arthroplasty (THA) is scarce. The study reports the course and interrelationships of radiographic loosening, pain and physical function 5 year before and after a first revision THA. Methods: The study was based on the IDES-THA database. All patients with their first THA revision for aseptic loosening and a documented index surgery on the same side and at least one pre-revision and one post-revision follow-up were selected. Only patients with an intact contralateral hip joint (Charnley class-A) were included. Follow-ups within ±5.5 years around the revision time point were analyzed. Annual prevalences of radiographic component loosening and the non-desired outcomes (moderate/severe/intolerable pain, walking <30 minutes, hip flexion range <90°) were calculated. Results: Signs of radiographic component loosening started to increase about 4 years before revision surgery. Two years later, a sharp increase of painful hips from 15% to 80% in the revision year was observed. In the year after revision surgery, this rate dropped back to below 10%. Walking capacity started to noticeably deteriorate 3 years before revision and in the revision year about 65% of patients could not walk longer than 30 minutes. As opposed to pain, walking capacity did not recover to pre-revision levels and the best outcome was only reached two years post-revision. Hip flexion range had the slowest and least extent of deterioration (≈45% flexed <70° in the revision year) but with the best outcomes at only three years after revision surgery it took the longest to recover. Conclusion: Prevalence of radiological loosening signs and/or pain intensity follow an almost parallel course around the first revision of a THA for aseptic component loosening. This process begins about 4 years (radiographic loosening) before the actual revision surgery and intensifies about 2 years later (pain). It also involves walking capacity and hip range of motion. While pain levels go back to levels similar to those after primary surgery, range of motion and even more walking capacity remain moderately compromised.

Short-term Functional and Patient Outcome of the Bi-cruciate Stabilized Total Knee Replacement: Prospective Consecutive Case-series

Background: Total knee replacement is the gold standard treatment for patients suffering from advanced symptomatic knee osteoarthritis. The main goals of knee prosthetics are pain reduction and restoration of knee motion. The new prostheses on the market such as the bi-cruciate stabilized Journey knee implant, promise a reconstruction of total physiological function of the knee with physiological range of motion and therefore high patient satisfaction. Purpose: The aim of this study was to analyze the patient-based Knee Injury and Osteoarthritis Outcome Score (KOOS) outcome after total knee replacement with new physiological bi-cruciate stabilized Journey knee prosthesis. Study Design: Prospective, consecutive case-series. Patients: Ninety nine patients, who received bi-cruciate stabilized Journey total knee prosthesis between January 1st 2006 and May 31st 2012, were included in the study. A single surgeon operated all patients. There were 61.1% females and the overall average age was 68 years (range 41-83 years). Left knee was replaced in 55.6%. Methods: The patients filled in KOO’s questionnaire pre- and 1 year postoperative. Range of motion (ROM) was studied preoperatively and at 1-year follow-ups. The pre- and postoperative KOOS subscores and ROM were compared using the Wilcoxon signed rank test. Results: There are significant improvements of all KOOS subscores. Ninety percent of patients have reached the minimum clinically relevant 10 points in symptoms, 94.5% in pain, 94.5% in activities of daily living, 84.9% in sport and recreation, and 90% in knee related quality of life. Postoperative, the average passive ROM was 131° (range 110-145°) and the average active ROM 122° (range 105-135°). The highest correlation coefficients ROM and the KOOS were observed for the activity and pain subscores. Very low or no correlation was seen for the sport subscore. Conclusions: Bi-cruciate stabilized knee prosthetic offers a solid outcome 1 year postoperative based on the results measured with the KOOS evaluation questionnaire. The Patients showed a generalized improvement in all domains measured in the KOOS of minimally 35, and up to over 52 points, what can be described as statistically significant. Patients described the level of functionality close to double compared to the preoperative status.

Perceptual learning of motion discrimination by mental imagery.

Perceptual learning can occur when stimuli are only imagined, i.e., without proper stimulus presentation. For example, perceptual learning improved bisection discrimination when only the two outer lines of the bisection stimulus were presented and the central line had to be imagined. Performance improved also with other static stimuli. In non-learning imagery experiments, imagining static stimuli is different from imagining motion stimuli. We hypothesized that those differences also affect imagery perceptual learning. Here, we show that imagery training also improves motion direction discrimination. Learning occurs when no stimulus at all is presented during training, whereas no learning occurs when only noise is presented. The interference between noise and mental imagery possibly hinders learning. For static bisection stimuli, the pattern is just the opposite. Learning occurs when presented with the two outer lines of the bisection stimulus, i.e., with only a part of the visual stimulus, while no learning occurs when no stimulus at all is presented.

Nitric oxide metabolite production in the cranial cruciate ligament, synovial membrane, and articular cartilage of dogs with cranial cruciate ligament rupture

OBJECTIVE To measure concentrations of nitric oxide metabolites (nitrite-nitrate [NOt]) in cartilage, synovial membrane, and cranial cruciate ligament (CCL) in dogs and evaluate associations with osteoarthritis in dogs with CCL rupture. ANIMALS 46 dogs with CCL rupture and 54 control dogs without joint disease. PROCEDURE Tissue specimens for histologic examination and explant culture were harvested during surgery in the CCL group or immediately after euthanasia in the control group; NOt concentrations were measured in supernatant of explant cultures and compared among dogs with various degrees of osteoarthritis and between dogs with and without CCL rupture. RESULTS Osteoarthritic cartilage had significantly higher NOt concentration (1,171.6 nmol/g) than did healthy cartilage (491.0 nmol/g); NOt concentration was associated with severity of macroscopic and microscopic lesions. Synovial membrane NOt concentration did not differ between dogs with and without CCL rupture. Ruptured CCL produced less NOt than did intact ligaments. In control dogs, NOt concentrations were similar for intact ligaments (568.1 nmol/g) and articular cartilage (491.0 nmol/g). Synthesis of NOt was inhibited substantially by coincubation with inhibitors. CONCLUSIONS AND CLINICAL RELEVANCE Results suggest that NOt in canine joint tissues originates from the inducible nitric oxide synthase pathway. Nitric oxide metabolite production in cartilage was greater in dogs with osteoarthritis than in healthy dogs and was associated with lesion severity, suggesting that nitric oxide inhibitors may be considered as a treatment for osteoarthritis. The CCL produces substantial concentrations of NOt; the importance of this finding is unknown.

Head Reduction Osteotomy With Additional Containment Surgery Improves Sphericity and Containment and Reduces Pain in Legg-Calvé-Perthes Disease.

BACKGROUND Severe femoral head deformities in the frontal plane such as hips with Legg-Calvé-Perthes disease (LCPD) are not contained by the acetabulum and result in hinged abduction and impingement. These rare deformities cannot be addressed by resection, which would endanger head vascularity. Femoral head reduction osteotomy allows for reshaping of the femoral head with the goal of improving head sphericity, containment, and hip function. QUESTIONS/PURPOSES Among hips with severe asphericity of the femoral head, does femoral head reduction osteotomy result in (1) improved head sphericity and containment; (2) pain relief and improved hip function; and (3) subsequent reoperations or complications? METHODS Over a 10-year period, we performed femoral head reduction osteotomies in 11 patients (11 hips) with severe head asphericities resulting from LCPD (10 hips) or disturbance of epiphyseal perfusion after conservative treatment of developmental dysplasia (one hip). Five of 11 hips had concomitant acetabular containment surgery including two triple osteotomies, two periacetabular osteotomies (PAOs), and one Colonna procedure. Patients were reviewed at a mean of 5 years (range, 1-10 years), and none was lost to followup. Mean patient age at the time of head reduction osteotomy was 13 years (range, 7-23 years). We obtained the sphericity index (defined as the ratio of the minor to the major axis of the ellipse drawn to best fit the femoral head articular surface on conventional anteroposterior pelvic radiographs) to assess head sphericity. Containment was assessed evaluating the proportion of patients with an intact Shenton's line, the extrusion index, and the lateral center-edge (LCE) angle. Merle d'Aubigné-Postel score and range of motion (flexion, internal/external rotation in 90° of flexion) were assessed to measure pain and function. Complications and reoperations were identified by chart review. RESULTS At latest followup, femoral head sphericity (72%; range, 64%-81% preoperatively versus 85%; range, 73%-96% postoperatively; p = 0.004), extrusion index (47%; range, 25%-60% versus 20%; range, 3%-58%; p = 0.006), and LCE angle (1°; range, -10° to 16° versus 26°; range, 4°-40°; p = 0.0064) were improved compared with preoperatively. With the limited number of hips available, the proportion of an intact Shenton's line (64% versus 100%; p = 0.087) and the overall Merle d'Aubigné-Postel score (14.5; range, 12-16 versus 15.7; range, 12-18; p = 0.072) remained unchanged at latest followup. The Merle d'Aubigné-Postel pain subscore improved (3.5; range, 1-5 versus 5.0; range, 3-6; p = 0.026). Range of motion was not observed to have improved with the numbers available (p ranging from 0.513 to 0.778). In addition to hardware removal in two hips, subsequent surgery was performed in five of 11 hips to improve containment after a mean interval of 2.3 years (range, 0.2-7.5 years). Of those, two hips had triple osteotomy, one hip a combined triple and valgus intertrochanteric osteotomy, one hip an intertrochanteric varus osteotomy, and one hip a PAO with a separate valgus intertrochanteric osteotomy. No avascular necrosis of the femoral head occurred. CONCLUSIONS Femoral head reduction osteotomy can improve femoral head sphericity. Improved head containment in these hips with an often dysplastic acetabulum requires additional acetabular containment surgery, ideally performed concomitantly. This can result in reduced pain and avascular necrosis seems to be rare. With the number of patients available, function did not improve. Therefore, future studies should use more precise instruments to evaluate clinical outcome and include longer followup to confirm joint preservation. LEVEL OF EVIDENCE Level IV, therapeutic study.

Short-term functional versus patient-reported outcome of the bicruciate stabilized total knee arthroplasty: prospective consecutive case series

BACKGROUND The main goals of the standard treatment for advanced symptomatic knee osteoarthritis, total knee arthroplasty (TKA), are pain reduction and restoration of knee motion.The aim of this study was to analyse the outcome of the patient-based Knee Injury and Osteoarthritis Outcome Score (KOOS), and the surgeon-based Knee Society Score (KSS) and its Knee Score (KS) and Knee Functional Score (KFS) components after (TKA) using the Journey knee prosthesis, and to assess the correlation of these scores with range of motion (ROM). METHODS In a prospective case series study between August 1st 2008 and May 31st 2011, 99 patients, all operated by a single surgeon, received Journey bicruciate stabilized total knee prostheses. The female/male ratio was 53/34, the mean patient age at surgery was 68 years (range 41-83 years), and the left/right knee ratio was 55/44. The KOOS, range of motion, and KS and KFS were obtained preoperatively and at 1-year follow-up. The pre- and postoperative levels of the outcome measures were compared using the Wilcoxon signed-rank test. Correlation between ROM and patient outcomes was analysed with the Spearman coefficient. RESULTS All KOOS subscores improved significantly. Ninety percent of patients improved by at least the minimum clinically relevant difference of 10 points in stiffness and other symptoms, 94.5% in pain, 94.5% in activities of daily living, 84.9% in sports and recreation, and 90% in knee-related quality of life. The mean passive and active ROM improved from 122.4° (range 90-145°) and 120.4° (range 80-145°) preoperatively to 129.4° (range 90-145°) and 127.1° (range 100-145°) postoperatively. The highest correlation coefficients for ROM and KOOS were observed for the activity and pain subscores. Very low or no correlation was seen for the sport subscore.There was a significant and clinically relevant improvement of KSS (preop/postop 112.2/174.5 points), and its KS (preop/postop 45.6/86.8 points) and KFS (preop/postop 66.6/87.8 points) components. CONCLUSIONS The Journey bicruciate stabilized knee prosthesis showed good 1-year postoperative results in terms of both functional and patient-based outcome. However, higher knee ROM correlates only moderately with patient-based outcome, implying that functionality afforded by the Journey bicruciate TKA is not equivalent to patient satisfaction.

Five-year results of lumbar disc prostheses in the SWISSspine registry

PURPOSE The Swiss Federal Office of Public Health demanded a nationwide HTA registry for lumbar total disc arthroplasty (TDA), to decide about its reimbursement. The goal of the SWISS spine registry is to generate evidence about the safety and efficiency of lumbar TDA. METHODS Two hundred forty-eight cases treated between 3-2005 and 6-2006, who were eligible for the 5-year follow-up were included in the study. Follow-up rates for 3-6 months, 1, 2 and 5 years were 85.9, 77.0, 44.0 and 51.2 %, respectively. Outcome measures were back and leg pain, medication consumption, quality of life, intraoperative and postoperative complication and revision rates. Additionally, segmental mobility, ossification, adjacent and distant segment degeneration were analysed at the 5-year follow-up. RESULTS There was a significant, clinically relevant and lasting reduction of back (preop/postop 73/29 VAS points) and leg pain (preop/postop VAS 55/22) and a consequently decreased analgesics consumption and quality of life improvement (preop/postop 0.30/0.76 EQ-5D score points) until 5 years after surgery. The rates for intraoperative and early postoperative complications were 4.4 and 3.2 %, respectively. The overall complication rate during five postoperative years was 23.4 %, and the adjacent segment degeneration rate was 10.7 %. In 4.4 % of patients, a revision surgery was performed. Cumulative survivorship probability for a revision/re-intervention-free 5-year postoperative course was 90.4 %. At the 5-year follow-up, the average range of motion of the mobile segments (86.8 %) was 9.7°. In 43.9 % of patients, osteophytes at least potentially affecting the range of motion were seen. CONCLUSIONS Lumbar TDA appeared as efficient in long-term pain alleviation, consequent reduction of pain medication consumption and improvement of quality of life. The procedure also appeared sufficiently safe, but surgeons have to be aware of a list of potential adverse events. The outcome is stable over the 5-year postoperative period. The vast majority of treated segments remained mobile after 5 years, although almost half of patients showed osteophytes.

Proteome-wide screening of the European porcine reproductive and respiratory syndrome virus reveals a broad range of T cell antigen reactivity.

The porcine reproductive and respiratory syndrome virus (PRRSV) is a rapidly evolving and diversifying pathogen necessitating the development of improved vaccines. Immunity to PRRSV is not well understood although there are data suggesting that virus-specific T cell IFN-γ responses play an important role. We therefore aimed to better characterise the T cell response to genotype 1 (European) PRRSV by utilising a synthetic peptide library spanning the entire proteome and a small cohort of pigs rendered immune to PRRSV-1 Olot/91 by repeated experimental infection. Using an IFN-γ ELISpot assay as a read-out, we were able to identify 9 antigenic regions on 5 of the viral proteins and determine the corresponding responder T cell phenotype. The diversity of the IFN-γ response to PRRSV proteins suggests that antigenic regions are scattered throughout the proteome and no one single antigen dominates the T cell response. To address the identification of well-conserved T cell antigens, we subsequently screened groups of pigs infected with a closely related avirulent PRRSV-1 strain (Lelystad) and a divergent virulent subtype 3 strain (SU1-Bel). Whilst T cell responses from both groups were observed against many of the antigens identified in the first study, animals infected with the SU1-Bel strain showed the greatest response against peptides representing the non-structural protein 5. The proteome-wide peptide library screening method used here, as well as the antigens identified, warrant further evaluation in the context of next generation vaccine development.

The block numerical range of analytic operator functions

We introduce the block numerical range Wn(L) of an operator function L with respect to a decomposition H = H1⊕. . .⊕Hn of the underlying Hilbert space. Our main results include the spectral inclusion property and estimates of the norm of the resolvent for analytic L . They generalise, and improve, the corresponding results for the numerical range (which is the case n = 1) since the block numerical range is contained in, and may be much smaller than, the usual numerical range. We show that refinements of the decomposition entail inclusions between the corresponding block numerical ranges and that the block numerical range of the operator matrix function L contains those of its principal subminors. For the special case of operator polynomials, we investigate the boundedness of Wn(L) and we prove a Perron-Frobenius type result for the block numerical radius of monic operator polynomials with coefficients that are positive in Hilbert lattice sense.

Biomechanical Evaluation of the Stabilizing Function of Three Atlantoaxial Implants Under Shear Loading: A Canine Cadaveric Study

OBJECTIVE: To compare the biomechanical properties of a ventral transarticular lag screw fixation technique, a new dorsal atlantoaxial instability (AAI) clamp, and a new ventral AAI hook plate under sagittal shear loading after transection of the ligaments of the atlantoaxial joint. STUDY DESIGN: Cadaveric biomechanical study. ANIMALS: Canine cadavers (n = 10). MATERIALS AND METHODS: The occipitoatlantoaxial region of Beagles euthanatized for reasons unrelated to the study was prepared leaving only ligamentous structures and the joint capsules between the first 2 cervical vertebrae (C1 and C2). The atlanto-occipital joints were stabilized with 2 transarticular diverging positive threaded K-wires. The occipital bone and the caudal end of C2 were embedded in polymethylmethacrylate and loaded in shear to a force of 50 Newtons. The range of motion (ROM) and neutral zone (NZ) of the atlantoaxial joint were determined after 3 loading cycles with atlantoaxial ligaments intact, after ligament transection, and after fixation with each implant. The testing order of implants was randomly assigned. The implants tested last were subjected to failure testing. RESULTS: All stabilization procedures decreased the ROM and NZ of the atlantoaxial joint compared to transected ligament specimens. Only stabilization with transarticular lag screws and ventral plates produced a significant reduction of ROM compare to intact specimens. CONCLUSION: Fixation with transarticular lag screws and a ventral hook plate was biomechanically similar and provided more rigidity compared to dorsal clamp fixation. Further load cycling to failure tests and clinical studies are required before making clinical recommendations.