Reverse Total shoulder arthroplasty (RTSA) was initially introduced to treat rotator cuff arthropathy. With proven successful long-term outcomes, it has gained a noteworthy surge in popularity with its indications consequently being extended to treating various traumatic glenohumeral diseases. Several countries holding national registries remain a guide to the use the prosthesis, however a notable lack of epidemiological data still exists. More so in South Africa where the spectrum of joint disease related to communicable diseases such as HIV and tuberculosis may influence indications and patient demographics. By analysing the epidemiology of patients who underwent RTSA at our institution, we aimed to outline the local disease spectrum, the patients afflicted and indications for surgery. A retrospective review of all patients operated within the sports unit between 1 January 2019 and 31 December 2022 was conducted. An analysis of the epidemiological data pertaining to patient demographics, diagnosis, indications for surgery and complications were recorded. Included in the review were 58 patients who underwent primary RTSA over the 4-year period. There were 41 females and 17 male patients, age <55 years (n= 14) >55 years (n=44). The indications included 23 rotator cuff arthropathy (40%), 12 primary glenohumeral osteoarthritis (OA) (20%), 10 avascular necrosis (AVN) humeral head (17%), 7 inflammatory OA (12%), 4 chronic shoulder dislocation (7%) and 2 sequalae of proximal humerus fractures (4%). The study revealed RTSA being performed in patients older than 55 years of age, the main pathologies included rotator cuff arthropathy and primary OA, however AVN and shoulder dislocations secondary to trauma contributed significantly to the total tally of surgeries undertaken. This highlights the disease burden of developing countries contributing to patients presenting for RTSA

Aim. Reveal the rate of surgical site infection (SSI) after primary hip and knee arthroplasty in patients with inflammatory joint disease and analyse if the infection rate was correlated to the given anti-rheumatic treatment. The background is that since 2006 patients operated at the orthopaedic department at Skåne University hospital, Lund, Sweden, have continued treatment with TNF-alpha inhibitors during the perioperative period. Method. During 2006 to 2015 494 planned primary hip and knee arthroplasties were performed on 395 patients (236 hip arthroplasties and 239 knee arthroplasties). Data on age, sex, diagnosis, BMI, operation time, ASA-classification, treatment with cDMARDs (conventional disease modifying anti-rheumatic drugs) and bDMARDs (biological disease modifying antirheumatic drugs) and use of prednisolone was collected. The primary outcome variable was prosthetic joint infection (PJI) within 1 year from surgery with a secondary outcome variable being superficial SSI. Results. In 32% (n=159) of the cases the patient was treated with a TNF-alpha inhibitor. The rate of PJI was 1.4% (n=7). The overall rate of infection, including superficial infections, was 2.4% (n=12). All the PJIs occurred after a knee arthroplasty and only 1 patient was treated with a TNF-alpha inhibitor (etanercept). Conclusions. We could not find that continuing treatment with TNF-inhibitors perioperatively led to a higher incidence of PJI or SSI than generally would be expected in a group of patients with an inflammatory joint disease. Based on these results there is no need to discontinue treatment with TNF-inhibitors when performing arthroplasty surgery

Dynamic 2D sonography of the infant hip is a commonly used clinical procedure for developmental dysplasia of the hip (DDH) screening. It however has been found to be unreliable with some studies reporting associated misdiagnosis rates of up to 29%. In a recent systematic review, Charlton et al. examined dynamic ultrasound (US) screening for hip instability in the first six weeks after birth and found current best practices for such early screening techniques to be divergent between international institutions in terms of clinical scanning protocols. Such protocols include: the appropriate scanning plane and US probe position (e.g. coronal, transverse, lateral, anterior), DDH diagnostic metrics (e.g. femoral head coverage, alpha angle), appropriate patient age when scanning, and follow up procedures. To improve reliability of diagnosis and to help in standardizing diagnosis across different raters and health-centers, we propose an automated method for dynamically assessing hip instability using 3D US. 38 infant hips from 19 patients were scanned with B-mode 3D US by a paediatric orthopaedic surgeon and two technologists from the radiology department at a paediatric tertiary care centre. To quantify hip assessment, we proposed the use of femoral head coverage variability (ΔFHC3D) within 3D US volumes collected during a sequence of US scans (one at rest, and another with posterior stress applied to the joint as maneuvered during a dynamic assessment). We used phase symmetry image features to localize the ilium's vertical cortex and a random forest classifier to identify the location of the femoral head. The proposed ΔFHC3D provided good repeatability with an average test-retest ICC measure of 0.70 (95% confidence interval: 0.35 to 0.87, F(21,21) = 7.738, p<.001). The mean difference of ΔFHC3D measurements was 0.61% with a SD of 4.05%. Since the observed changes in ΔFHC3D start near 0% and range up to about 18% from stable to mildly unstable hips in this cohort, the mean difference and standard deviation of ΔFHC3D measurements observed suggest that the proposed metric and technique likely have sufficient resolution and repeatability to quantify differences in hip laxity. The long-term significance of this approach to evaluating dynamic assessments may lie in increasing early diagnostic accuracy in order to prevent dysplasia remaining undetected prior to manifesting itself in early adulthood joint disease

Septic arthritis is a medical emergency that can lead to significant morbidity and mortality arising from irreversible joint destruction and overwhelming sepsis. The purpose of this prospective study is to present epidemiological, clinical and laboratory findings in adult patients with septic arthritis. Adult patients treated for septic arthritis at the Department of Infectious Diseases, University Medical Centre Ljubljana, Slovenia, from January 2012 to December 2014, qualified for the present report. The following data were analyzed: age, sex, underlying diseases, previous joint procedure, microbiological diagnostic examinations, causative agents, complications and therapy. During the study period of three years 94 episodes of septic arthritis were diagnosed. There were 49 (52.1%) females and 45 (47.9%) males, aged 64.5 (18 to 97) years. At the first visit elevated concentration of C-reactive protein was found in 93 (98.9%) patients. The most common affected joint was knee (48.9%), followed by shoulder (20.2%), wrist (12.8%), ankle (7.4%) and others. In 8 (8.5%) patients more than one joint was affected. Risk factors were found in 63 (67%) of study patients. The underlying joint disease (e.g. osteoarthritis, rheumatoid arthritis, gout) was found in 50.8% patients, following by malignancy and immunosuppressive therapy in 28.6%, diabetes mellitus in 14.9%, recent trauma in 12.8%, and prior joint procedure in 9.6% patients. In 65/94 (69.1%) patients the causative pathogen was demonstrated by blood culture in 35.6%, by synovial fluid culture in 48.8%, and by both methods in 13.8% patients. In patients with proven aetiology Staphylococcus aureus was the most frequent (44.6%) isolated pathogen (only one methicillin resistant), followed by gram-negative bacteria in 30.8%, and Streptococcus spp. in 23.1% patients. In 4/65 (6.2%) patients more than one pathogen was isolated. The patients were treated with antibiotics according to isolated pathogen. In 17 (70.8%) out of 24 patients with complications synovectomia was performed, and adjacent osteomyelitis was found in 9 (37.5%) patients. Our results show that the foremost risk factor in adult patients with septic arthritis is pre-existing joint disease, knee is the principal target of infection, and the most common isolated pathogen is S. aureus. It was established that prompt recognition, early appropriate antimicrobial and surgical treatment in these patients are critical to ensuring a good prognosis

Osteoarthritis (OA) is a debilitating disease and the most common joint disorder worldwide. Although the development of OA is considered multifactorial, the mechanisms underlying its initiation and progression remain unclear. A prominent feature in OA is cartilage degradation typified by the progressive loss of extracellular matrix components - aggrecan and type II collagen (Col II). Cartilage homeostasis is maintained by the anabolic and catabolic activities of chondrocytes. Prolonged exposure to stressors such as mechanical loading and inflammatory cytokines can alter the phonotype of chondrocytes favoring cartilage catabolism, and occurs through decreased matrix protein synthesis and upregulation of catabolic enzymes such as aggrecanases (ADAMTS-) 4 and 5 and matrix metalloproteinases (MMPs). More recently, the endoplasmic reticulum (ER) stress response has been implicated in OA. The ER-stress response protects the cell from misfolded proteins however, excessive activation of this system can lead to chondrocyte apoptosis. Acute exposure of chondrocytes to IL-1β has been demonstrated to upregulate ER-stress markers (GADD153 and GRP78), however, it is unclear whether the ER-stress response plays a role on chronic IL-1β exposure. The purpose of this study was to determine whether modulating the ER stress response with tauroursodeoxycholic acid (TUDCA) in human OA chondrocytes during prolonged IL-1β exposure can alter its catabolic effects. Articular cartilage was isolated from donors undergoing total hip or knee replacement. Chondrocytes were recovered from the cartilage of each femoral head or knee by sequential digestion with Pronase followed by Collagenase, and expanded in DMEM-low glucose supplemented with 10% FBS. Chondrocytes were expanded in flasks for one passage before being prepared for micropellet culture. Chondrocyte pellets were cultured in regular growth medium (Control), medium supplemented with IL-1β [10 ng/mL], TUDCA [100 uM] or IL-1β + TUDCA for 12 days. Medium was replaced every three days. Cartilage explants were prepared from the donors undergoing knee replacement, and included cartilage with the cortical bone approximately 1 cm2 in dimension. Explants were cultured in the above mentioned media, however, the incubation period was extended to 21 days. RNA was extracted using Geneaid RNA Mini Kit for Tissue followed by cDNA synthesis. QPCR was performed using Cyber Green mastermix and primers for the following genes: ACAN (aggreacan), COL1A1, COL2A1, COL10A1, ADAMTS-4, ADAMTS-5, MMP-3, and MMP-13, on an ABI 7500 fast qPCR system. Although IL-1β did not significantly decrease the expression of matrix proteins, it did increase the expression of ADAMTS-4, −5, and MMP3 and −13 when compared to controls (Kruskal-Wallis, p < 0 .05, n=3). TUDCA treatment alone did not significantly increase the expression of catabolic enzymes but it did increase the expression of collagen type II. When IL-1β was coincubated with TUDCA, the expression of ADAMTS-4, ADAMTS-5, and MMP-13 significantly decreased by ∼40-fold, ∼10-fold, and ∼3-fold, respectfully. We provide evidence that the catabolic activities of IL-1β on human cartilage can be abrogated through modulation of the ER stress response

Osteoarthritis (OA) is one of the most prevalent joint diseases involving progressive and degenerative changes to cartilage resulting from a variety of etiologies including post-traumatic incident or aging. OA lesions can be treated at its early stages through cell-based tissue engineering therapies using Mesenchymal Stem Cells (MSCs). In vivo models for evaluating these strategies, have described both chondral (impaction) and osteochondral (biopsy punch) defects. The aim of the investigation was to develop a compact and reproducible defect inducing post-traumatic degenerative changes mimicking early OA. Additionally, a pilot study to evaluate the efficacy of MSC-hydrogel treatment was also assessed. Surgery was performed on New Zealand white rabbits (male, 5–8 months old) with defects created on medial femoral condyle. For developing an appropriate defect, three approaches were used for evaluation: a biopsy punch (n = three at six and twelve weeks), an impaction device1 (n = three at six and twelve weeks) and a dental drill model (n = six at six and twelve weeks). At stated time points, condyles were harvested and decalcified in 10% EDTA, then embedded in Tissue-Tek and sectioned using a cryostat. Upon identification of region of interest, sections were stained with Safranin-O/Fast green and scored using OARSI scoring system by two blinded observers2. For the pilot study, autologous bone marrow was harvested from rabbits and used to isolate and expand MSCs. The Dental drill model was applied to both knee condyles, left untreated for six weeks at which stage, PKH26 fluorescently labelled MSCs were seeded into a hyaluronic acid hydrogel (TETEC). Repair tissue was removed from both condyles and MSC-hydrogel was injected into the left knee, whilst right knee was left empty. Rabbits were sacrificed at one (n = 1), six (n = 3) and twelve (n = 3) weeks post-treatment, processed as previously described and cartilage regeneration evaluated using Sellers score3. Impacted condyles exhibited no observed changes histologically (Mean OARSI score = 1 + 1), whereas biopsy punched and dental drilled defects demonstrated equal signs of cartilage erosion (OARSI score = 3 + 1) at assessed time points. However, biopsy punched condyles formed a diffusive defect, whereas dental drilled condyles showed a more defined, compact and reproducible defect. In the pilot study, PKH-labelled MSCs were observed at one and six weeks post-implantation within the defect space where hydrogel was injected. Tissue regeneration assessment indicated no difference between empty (Mean Sellers score = 14 + 2) and MSC treated defects (Sellers score = 16 + 5) at six weeks post-injection. At twelve weeks, MSC treated defects showed improved tissue regeneration with substantial subchondral bone restoration and good integration of regenerative cartilage with surrounding intact tissue (Sellers score = 10 + 1), whereas untreated defects showed no change in regeneration compared to six weeks (Sellers score = 16 + 2). Dental drill model was found to be the appropriate strategy for investigating early OA progression and treatment. Application of MSCs in defects showed good cartilage regeneration after twelve weeks application, indicating their promise in the treatment of early OA defects

Introduction. Osteoarthritis (OA), a painful, debilitating joint disease, often caused by excessive joint stress, is a leading cause of disability (World Health Organisation, 2003) and increases with age and obesity. A 5° varus malalignment increases loading in the medial knee compartment from 70% to 90% (Tetsworth and Paley, 1994). Internal unloading implants, placed subcutaneously upon the medial aspect of the knee joint, are designed to offload the medial compartment of the knee without violating natural joint tissues. The aim of this study is to investigate the effect of an unloading implant, such as the Atlas™ knee system, on stress within the tibiofemoral joint with different grades of cartilage defects. Methods. To simulate surgical treatment of medial knee OA, a three-dimensional computer-aided design of an Atlas™ knee system was virtually fixed to the medial aspect of a validated finite element knee model (Mootanah, 2014), using CATIA v5 software (Dassault Systèmes, Velizy Villacoublay, France). The construct was meshed and assigned material properties and boundary conditions, using Abaqus finite element software (Dassault Systèmes, Velizy Villacoublay, France). A cartilage defect was simulated by removing elements corresponding to 4.7 mm. 2. The international cartilage repair society (ICRS) Grade II and III damage were simulated by normalized defect depth of 33% and 67%, respectively. The femur was mechanically grounded and the tibia was subjected to loading conditions corresponding to the stance phase of walking of a healthy 50-year-old 68-Kg male with anthropometrics that matched those of the cadaver. Finite element analyses were run for peak shear and von Mises stress in the medial and lateral tibiofemoral compartments. Results. Von Mises stress distribution in the tibial cartilage, with ICRS Grade II and III defects, without the unloading implant, at the end of weight acceptance (15% of the gait cycle) were analysed. The internal unloading implant reduces peak von Mises stress by 40% and 43% for Grade II and Grade III cartilage defects, respectively. The corresponding reductions in shear stress are 36% and 40%. Consistent reduction in peak von Mises stress values in the medial cartilage-cartilage and cartilage-meniscus contact areas were predicted throughout the stance phase of the gait cycle for ICRS Grade II defect. Similar results were obtained for Grade III defect and for peak shear stress values. There were no overall increases in peak von Mises stress values in the lateral tibial cartilage. Discussion and Conclusions. The internal unloading implant is capable of reducing von Mises and shear stress values in the medial tibial cartilage with ICRS Grade II and III defects at the cartilage-cartilage and cartilage-meniscus interfaces throughout the stance phase of the gait cycle. This did not result in increased stress values in the lateral tibial cartilage. Our model did not account for the viscoelastic effects of the cartilage and meniscus. Results of this study are based on only one knee specimen. The internal unloading implant may protect the cartilage in individuals with medial knee osteoarthritis, thereby delaying the need for knee replacements

Although physical and ultrasound (US)-based screening for congenital deformities of the hip (developmental dysplasia of the hip, or DDH) is routinely performed in most countries, one of the most commonly performed manoeuvres done under ultrasound observation - dynamic assessment - has been shown to be relatively unreliable and is associated with significant misdiagnosis rates, on the order of 29%. Our overall research objective is to develop a quantitative method of assessing hip instability, which we hope will standardise diagnosis across different raters and health-centres, and may perhaps improve reliability of diagnosis. To quantify dynamic assessment, we propose to use the variability in femoral head coverage (FHC) measurements within multiple US scans collected during a dynamic assessment. In every US scan, we use our recently-developed automatic FHC measuring tool which leverages phase symmetry features to approximate vertical cortex of ilium and a random forest classifier to identify approximate location of the femoral head. Having estimated FHC in each scan, we estimate the change in FHC across all the US scans during a dynamic assessment and compare this change with variability of FHC found in previous studies. Our findings - in a dynamic assessment on an infant done by an orthopaedic surgeon, the femoral centre moved by up to 19% of its diameter during distraction, from 55% FHC to 74% FHC. This variability is similar to the variability of FHC in static US scans reported in previous studies, so the variability in FHC readings we found are not indicative of any subluxation or dislocation of the infant's femoral head. Our clinician's qualitative assessment concluded the hip to be normal and not indicative of instability. This suggests that our technique likely has sufficient resolution and repeatability to quantify differences in laxity between stable and unstable hips, although this presumption will have to be confirmed in a subsequent study with additional subjects. The long-term significance of this approach to evaluating dynamic assessments may lie in increasing early diagnostic sensitivity in order to prevent dysplasia remaining undetected prior to manifesting itself in early adulthood joint disease

Objective. This study shows the radiographic results of total hip arthroplasty (THA) using the Revelation hip system. ®. for hip joint disease. Methods. We performed THA for hip disease using the Revelation Hip System. ®. From July 2007 to May 2009, 30cases (35 hips) were available for this study. Radiographic evaluation was performed at the last follow-up. Evaluation items included the presence or absence of subsidence, spot welds, demarcation line, cortical hypertrophy and stress shielding. The stem was designed to be implanted without cement and to be combined to the femur bone at the proximal portion to avoid stress shielding. Zone of Gruen zone 1 was divided into 1A or 1B, above and below the outermost tip of the lateral flare of the stem. Results. In total, 35 hips had spot welds at zones 1B and 7, and many hips had demarcation lines in zone 4 or 5, but not in zones 1B or 7. Cortical hypertrophy was detected in 6 cases in zone 3, the lateral edge of the stem. Stress shielding was first degree or second degree in 29 hips; however, no cases were identified with more than third-degree stress shielding. Discussion. At the proximal portion of the stem, spot welds were detected but demarcation lines were not, suggesting that bone ingrowth to the stem and combination of the stem and femur may have been completed in this area. Loading at the medial proximal end may not have occurred with a collarless cementless stem. First-degree stress shielding was thus considered a natural phenomenon that should not be seen as usual stress shielding. Cortical hypertrophy was detected in 17.1% of hips. Although no complaints such as thigh pain were identified, Revelation microMax. ®. , in which the unnecessary distal portion of the stem was shortened, was designed to address this problem

Total knee arthroplasty (TKA) is widely accepted as a successful treatment option for the pain and limitation of function associated with severe joint disease. The ideal knee arthroplasty implant should provide reliable pain relief and normal levels of functional strength and range of motion. However, there are still a number of implant-specific problems following knee arthroplasty, such as irregular kinematics, polyethylene wear and poor range of motion. MRI and cadaveric studies have highlighted important kinematics during movement of the native knee. In particular, flexion of the joint results in a phenomenon referred to as “roll back and slide”. This essentially describes posterior translation of the femur on the tibia which in turn has a two-fold biomechanical function: to increase the lever arm of the quadriceps and allow clearance of the femur from the tibia in deep flexion. During extension of the joint, the femur rolls forward increasing the lever arm of the hamstrings to act as a brake on hyperextension. Additional rotation of the joint arises in the axial plane. This is attributed to the concave tibial plateau and relatively fixed meniscus on the medial compartment of the joint in comparison to a lateral convex plateau with a mobile meniscus. This asymmetry allows axial rotation of the lateral compartment over the medial compartment by up to 30 degrees. Subsequently, from extension to full flexion the tibia rotates internally on the femur and vice versa. The external rotation of the tibia on the femur that occurs during the terminal degrees of knee extension is often referred to as the “screw home mechanism” and results in tightening of both the cruciate ligaments locking the knee such that the tibia is in a position of maximum stability on the femur. Numerous studies over the past two decades have characterised the in-vivo motions of knee replacements. Major conclusions from these studies are that the motion after knee arthroplasty generally does not replicate normal knee motions. In particular, many kinematic studies of unconstrained devices have demonstrated the femur sliding forwards rather than backwards with flexion. This paradoxical movement is also seen in many posterior cruciate retaining knees. This in turn has a negative outcome in range of movement, particularly in light of fluoroscopic studies highlighting strong positive correlations in weight-bearing flexion with femoral roll back. In contrast knee arthroplasties that retain both cruciate ligaments come closest to replicating normal knee motion and furthermore, provide greater stair climbing stability. It may therefore be presumed that this excessive AP motion in a well-designed prosthesis is attributed to a loss in the natural intrinsic stabilizing structures. A number of studies to date have also highlighted close correlation between knee kinematics and functional strength. Generally, patients with knee replacement exhibit a significant loss of strength compared to normal. The common experimental findings is that knees with the highest intrinsic stability, whether provided by retained ligaments, conforming articular surfaces or post-cam substitution, exhibit the greatest functional strength in high-demand activities in TKA patients. On the basis of this knowledge, it would be intuitive to choose a TKA design that attempts to restore natural knee joint stability. The medially conforming ‘ball and socket’ articulation of the medial tibio-femoral compartment is a design concept thought to provide stability through the complete arc of knee flexion. Clinical and biomechanical data from a number of centers suggests that this has been a successful evolution in TKA that will continue to benefit patients

Intro. Across much of medicine, activity levels predict life expectancy, with low levels of activity being associated with increased mortality, and higher levels of activity being associated with longer healthier lives. Resurfacing is a technically demanding procedure that has suffered significant fallout from the failure of a couple of poorly performing designs. However strong evidence associates resurfacing with improved life expectancy in both the short and longer term following surgery. We wondered if there was any relationship between the function of hips following surgery and the extent of that surgery. Could a longer stem inside the femur be the reason for a slightly reduced step length? We proposed the nul hypothesis that there was no clinically relevant difference between stem length and gait. Method. After informed consent each subject was allowed a 5 minute acclimatisation period at 4km/hr on the instrumented treadmill (Kistler Gaitway, Amherst, NY). Their gait performance on an increasing incline at 5, 10 and 15%. At all 0.5km incremental intervals of speed, the vertical component of the ground reaction forces, center of pressure and temporal measurements were collected for both limbs with a sampling frequency of 100Hz over 10sec. They were also asked to log onto our JointPRO website and report their function using Oxford, EQ5D, and Imperial scores. Owing to current restrictions in indications, the patient groups selected were not comparable. However, from our database of over 800 patients who have been through the gait lab. 82 subjects were tested from 2 diagnostic groups (29 conventional THR, 27 hip resurfacing) and compared with a slightly younger group of 26 healthy controls. Patients were excluded if less than 12 months postop, or with any other documented joint disease or medical comorbidities which might affect gait performance. Body weight scaling was also applied to the outputted mechanical data to correct for mass differences. All variables for each subject group were compared to each other using an analysis of variance (ANOVA) with Tukey post hoc test with significance set at α=0.05. Results. The experimental groups were reasonably matched for sex, height and BMI, although the controls were rather younger, and the hip replacements rather older (young hip resurfacings were excluded for lack of good controls). Any differences did not reach significance. Oxford hip scores and EQ5D were almost identical for the two experimental groups. The THR group walked 10% slower than control (1.8 (±0.2)m/sec vs 2.0 (±0.1)m/sec). while the HRA group walked 5% faster (2.1(±0.2)m/sec). The difference between THR and control was significant (p<0.05). (See Figure 1). Discussion. This data records a 15% difference in top walking speed between THR and HRA, far exceeding the 5% threshold of clinical relevance. We therefore consider this improved functional outcome to be clinically relevant, and report with increasing confidence that hip resurfacings is an effective intervention in the treatment of hip disease with clinically relevant superiority over THR, even in a group with an average age of 60

Introduction. Financial and human cost effectiveness is an increasing evident outcome measure of surgical innovation. Considering the human element, the aim is to restore the individual to their “normal” state by sparing anatomy without compromising implant performance. Gait lab studies have shown differences between different implants at top walking speed, but none to our knowledge have analysed differing total hip replacement patients through the entire range of gait speed and incline to show differences. The purpose of this gait study was to 1) determine if a new short stem femoral implant would return patients back to normal 2) compare its performance to established hip resurfacing and long stem total hip replacement (THR) implants. Method. 110 subjects were tested on an instrumented treadmill (Kistler Gaitway), 4 groups (short-stem THR, long-stem THR, hip resurfacing and healthy controls) of 28, 29, 27, and 26 respectively. The new short femoral stem patients (Furlong Evolution, JRI) were taken from the ongoing Evolution Hip trial that have been tested on the treadmill minimum 12months postop. The long stem total hip replacements and hip resurfacing groups were identified from our 800+ patient treadmill database, and only included with tests minimum 12 months postop and had no other joint disease or medical comorbidities which would affect gait performance. All subjects were tested through their entire range of gait speeds and incline after having a 5 minute habituation period. Speed were increased 0.5kmh until maximum walking speed achieved and inclines at 4kmh for 5,10,15%. At all incremental intervals of speed 10seconds ere collected, including vertical ground reaction forces (normalized to body mass), center of pressure and temporal measurements were for both limbs (fs=100Hz). Symmetry Index(SI) were calculated on a range of features comparing leg with implanted hip to the contralateral normal hip. Group means for each feature for each subject group were compared using an analysis of variance (ANOVA) with Tukey post-hoc test with significance set at α=0.05. Results. The four groups were reasonably matched for demographics and the implant groups for subjective outcome measures (Oxford Score & EQ5D). Hip resurfacing group had a clear top walking speed advantage, but when assessing SI on all speeds and incline, no groups were significantly different (Figure 1-3). Push-off and step length was statistically less favorable for the short/long stemmed THR group (p=0.005–0.05) depending on speed/incline comparing only implanted side. Discussion. The primary aim of this study was to determine if implant design affected gait symmetry and performance. Interestingly, irrespective of implant design, symmetry with regards to weight acceptance, impulse, push-off and step length was returned to normal when comparing to healthy controls. However individual implant performance on the flat and incline, showed inferior (p<0.05) push-off force and step length in the short stem and long stem THR groups when compared to controls. Age and gender may have played a part for the short stem group. It appears that the early gait outcomes for the short stem device are promising. Assessment at the 3-year mark should be conclusive

Introduction. Early hip OA may be attributed to smaller coverage of the femoral head leading to higher loads per unit area. We hypothesize that tight hamstrings may contribute to increased loads per unit area on the femoral head during gait. When a patient has tight hamstrings they cannot flex their pelvis in a normal fashion which may result in smaller coverage of the femoral head (Figure 1). This study aimed to determine if subjects with tight hamstrings can improve femoral head coverage during gait after a stretching intervention. Methods. Nine healthy subjects with tight hamstrings (popliteal angle>25°) were recruited and consented for this IRB approved study. Gait analysis with 58 reflective markers were placed by palpation on anatomical landmarks of the torso and lower extremities. Ten optoelectronic cameras (Qualisys, Gothenburg, Sweden) and three force plates (AMTI, Watertown, MA) were used to track marker position and measure foot strike forces. Subjects walked at a self-selected speed across the force plates until ten clean trials were performed and then were scanned with the reflective markers on the spine using an EOS (EOS Imaging, France) bi-planar x-ray system. Following testing participants completed a six week stretching program to increase hamstring length. Pelvic tilt (PT) was measured at heel strike for each trial and averaged. Using EOS scans the femoral head radius was measured using three points that best fit the load bearing surface on the sagittal view from the anterior acetabular rim to a point on the posterior acetabulum 45 degrees from vertical. The radius of femoral head and angle of acetabular coverage were used to calculate the load bearing surface area of femoral head. Load on the femur was calculated using an Anybody lower body model (Anybody Technology, Aalborg, Denmark) and load per unit area change was compared. Results. Nine participants completed the stretching program and post intervention testing. PA increased in all subjects (mean ± SD) 18.8° ± 11° (p<.01). Eight of nine subjects had an increase in anterior PT at heel strike resulting in a mean change of 2.1° ± 2.9° (p<.05). The change in PT resulted in a mean surface area change of 0.63cm. 2. ± 0.77 cm. 2. (p<.05), which resulted in a mean pressure change of −57.9MPa ± 55.7MPa. Removing the one subject who decreased in anterior pelvic tilt resulted in a mean change in PT of 2.9° ± 1.2°, a mean change in surface area of 0.85cm. 2. ± 0.46 cm. 2. , and a mean pressure change of −74.4 MPa ± 27.2 MPa. (Table 1). Discussion/Conclusion. This study verified the hypothesis that functional PT is influenced significantly by tight hamstrings. Using a stretching intervention program small changes in functional PT can be elicited that may significantly decrease the force per unit area on the femoral head and possibly the risk for developing degeneration joint disease. Although our study is limited by the small number of participants it does lend one significant benefit to intervene in patients who have chronically tight hamstrings. For figures/tables, please contact authors directly.

Introduction. Total hip replacement is an established surgical procedure done to alleviate hip pain due to joint diseases. However, this procedure is avoided in yonger patients with higher functional demands due to the potential for early failure. An ideal prosthesis will have have a high endurance against impact loading, with minimal micromotion at the bone cement interface, and a reduced risk of fatigue failure, with a favourable stress distribution pattern in the femur. We study the effect of varying the material properties and design element in a standard cemented total hip using Finite Element Analysis. Methods. A patient-specific 3D model of femur will be constructed from CT scan data, while a Summit® Cemented Hip System (DePuy Orthopedic) will be used to as a control for comparative evaluation. We vary the material stiffness of different parts of the prosthesis(see Fig.1) to formulate a design concept for a new total hip prosthesis design; and use Finite Element Method to predict the micromotion of the hip prosthesis at the bone cement interface, as well as the stress distribution in the the femur. Result. Validation of computational protocol was being done by comparing the principal maximum strain of the femoral cortex along the diaphysis, and the amount of deflection, with published literature, similarly, contact modelling validation was also done. Model 1–4 induced lower peak Von Mises stress in the cement, which takes a much lower value than any of the cement mechanical limits postulated. Therefore, the risk of cement failure is greatly reduced in Model 1–4. However, the effect of varying stiffness in different regions is not significant in terms of load transmission to the cement. Micromotion at the bone-cement interface was studied via two approaches: Peak micromotion at the bone cement interface; and the micromotion data at 12 Regions of Interest (ROI)s. Both results showed that model 2 and 3 are capable of reducing micromotion at bone-cement interface, in comparison with the Summit® Cemented Hip System. By comparing the Von Mises Stress distribution in the proximal femur; model 1 is found to result in a significantly reduced stress shielding effect, while model 2–4 are also favourable in comparison to the standard Summit® prosthesis in terms of stress distribution in the femur. Figure 2 shows the effects of the performance of model 1–4, presented as percentage difference from the Summit® prosthesis. Model 1 is unfavourable, despite its favourable stress distribution, because its peak and overall micromotion at the bone-cement interface is greatly increased. Conclusion. Model 2 and 3 have favourable design elements. They both have reduced micromotion at the bone-cement interface; and a favourable stress distribution in the femur. Further refining and testing of model 2 and 3 should done, as these models may provide information which may be useful in improving the performance of the current range of total hip replacement prostheses

Artificial joints have been increasingly used in the treatment of physically disabled people who suffer from joint diseases such as osteoarthritis and rheumatoid arthritis. Ultra high molecular weight polyethylene (UHMWPE) is commonly used in hard-on-polymer joints as an impact-absorbing material for artificial hip joints because of its very low friction coefficient, high wear resistance, impact strength, and biocompatibility. However, particles generated by excessive wear and fatigue can cause osteolysis, which may lead to loosening. This has led to recent interest in metal-on-metal joints, which can provide better wear properties than hard-on-polymer joints, leading to reduced osteolysis. However, during gait, metal-on-metal joints are exposed to greater impacts than hard-on-polymer joints. These impacts can cause severe pain in patients who have undergone hip replacement arthroplasty. In previous work, we proposed a double-shell metal-on-metal artificial hip joint in which a single garter spring was inserted between the inner and outer acetabular shell of an impact relief device[1]. A garter spring is usually used by loading a compression stress from the outside to the center axis. The acetabular shell is composed of two layers as shown in Fig.1. In the current work, the performance of single and dual garter springs was investigated using static compression and free-fall type impact tests. Static compression tests were conducted on a conventional vise to examine the deformation of various kinds of garter springs under uniaxial loading. Free-fall impact tests, on the other hand, were conducted on a free-fall type impact test machine as shown in Fig. 2. The impact relief ability of the garter springs under impact loading was examined, and the maximum impact load and maximum impact load arriving-time were estimated[2]. The relief ability was also investigated for smaller and larger diameter garter springs with a three-pitch angle, and the maximum applied load was determined by taking into account the applied load on actual hip joints. Static compression test results indicated that some kinds of garter spring could withstand vertical loads of over 6000N, which is estimated to be equal to maximum vertical load during jumping. The pitch angle increased with an increase in the compression load and the shape of the coil ring deformed from a circular to ellipsoidal shape as the compression load increased, which may lead to a reduction in impact load and an increase in impact relief time. The impact test results for a single spring indicated that the maximum impact load decreased in reverse proportion to the maximum impact load arriving-time. A smaller diameter garter spring provided less maximum impact load and longer arriving maximum load time. In the case of dual garter springs, which have smaller and larger diameter garter springs, the springs offered a lower maximum impact load and a longer impact load arriving-time than a single spring

This study shows the radiographic results of total hip arthroplasty (THA) using Revelation stem ® (Djo surgical USA) for hip joint disease. We removed cases which we couldn't follow up, the remaining of the patients who had undergone a primary THA July 2007 to December 2009 in our institution using Revelation hip stem® and 58 cases-65 hips (14 men and 44 women) were possible for progress observation on this study, and radiographic evaluation was done at the time of the last observation. The preoperative diagnosis of the hip included osteoarthritis (OA) in 40 patients, idiopatic, necrosis of the hip in 13 patients, Rheumatoid arthritis (RA) in 4 patients, and femoral head fracture in 1 patient. Three patients had undergone femoral head replacement (FHA) and 55 patients had undergone THA. At the time of the last evaluation, spot welds were detected in 63 hips (97%) in zone1 and 7. Demarcation lines, which indicates movement of the stem, were detected in zone3,4,5, but not in the proximal of the stem. Stress shielding were observed in 32 joints, according to Engh's classification, first degree were 27 joints and second degree were 5 joints. Cortical hypertrophy were detected in 13 joints. The revelation stem features a lateral overhang structure (lateral flare) and the stem has an expanded proximal geometry allowing the device to rest on both medial and lateral cortices at the metaphyseal level. Above all the stem has anterior overhand structure (trapezoidal structure). The medullary cavity occupation rate is made to increase by these structures. Above all, the stability of the stem is increased by a proximal portion by three point support. The distal stem is tapered and polished, which prevents the stress loading to a distal portion of the device. Stress shielding more than the third degree is not detected, and spots welds were detected in the proximal of the stem. These facts indicate that the concept of this stem, transmit loading to the femur bone, at the proximal portion of the stem, would be achieved

The gold standard for measuring knee alignment is the lower limb mechanical axis. This is traditionally assessed by weight-bearing full length lower limb X-rays (LLX). CT scanograms (CTS) are however, becoming increasingly popular in view of lower radiation exposure, speed and supine positioning. We assessed the correlation and reproducibility of knee joint coronal alignment using these two imaging modalities. LLX and CTS images were obtained in 24 knees with degenerate joint disease or failed TKR. Hip to ankle mechanical alignment were measured using the PACS software. Coronal knee alignment was assessed from the centre of the knee, measuring the valgus/varus angle relative to the mechanical axis. Measurements were made by two orthopaedic surgeons (Research Fellow and Consultant) on two separate occasions. The mean alignment angles measured by observers 1 and 2 on CTS were 180.29° (SD 6.04) and 180.71° (SD 6.13) respectively, while on LLX were 181.04° (SD7.58) and 181.04° (SD 7.72). The measurements between the two observers were highly correlated for both the CTS (r = 0.97, p < 0.001) and the LLX (r = 0.99, p < 0.001). The angles measured on CTS and LLX were highly correlated (r = 0.826, p < 0.001) with high degree of internal consistency (ICC = 0.804). Malalignment of greater than 5° was seen in 19% of the CTS and 35% of the LLX. There was good correlation between CT scanogram and weight-bearing X-ray measurements in normally-aligned knees. However, as expected, in the malaligned lower limb, the influence of weight-bearing is critical which demonstrates the significance of weight-bearing X-rays

Introduction. Patellar stability is an important component for a correct kinematic behaviour of the knee that depends on several factors such as joint geometry, muscles strength and soft tissues actions. Patellofemoral (PF) maltracking can results in many joint disorders which can cause pain and mobility alterations. The medial patellofemoral ligament (MPFL) is an important stabilizing structure for the patellofemoral joint. The aim of this study was to analyze patellofemoral kinematics with particular attention to the contribution of MPFL on patella stability. Methods. Using a navigation system PF kinematics during passive flexion/extension movements with quadriceps loaded at 60N, was recorded on 6 cadavers in three different anatomical conditions: intact knee, MPFL cut and MPFL reconstructed with graft. Test on patella was conducted without lateral force and with applied lateral force (25N). Tilt and lateral shift was evaluated in both cases at 0°. 30°, 60°and 90° of flexion. Results. Test results without applied force showed that there is no statistical difference between intact knee and MPFL cut conditions in all ranges of flexion, both for medio-lateral shift and tilt, which have low values. In test with applied force a significative increase of patellar lateral translation at 30° (16,8 ± 13,4 mm) and 60° (18,6 ± 6,4 mm) was found. MPFL reconstructed knee behaviour was not statistically different to intact knee both for tilt and medio-lateral shift. Therefore lateral translation was widely reduced with the graft. Conclusions. Without applied stress intact knees and MPFL cut knees behave in the same way. In applied load conditions MPFL cut knees show wide lateral translation in respect to intact and reconstructed knees. MPFL reconstructed knees are similar to intact knee therefore MPFL restraint is significant only in stress conditions. This may indicate that the MPFL is a aponeurosis, with an active role under stress, but low role during neutral knee flexion

Total knee replacement (TKR) is an established treatment for end stage joint disease of the knee. Trabecular metal is one of the design experiments seeking to improve the bone-implant interface and wear patterns in order to increase the longevity of primary joint replacements and reduce the revision burden. Uncemented implants retain bone stock, reduce third body wear, and require a shorter operative time. Although only 4% of knee replacements currently being implanted are uncemented TKRs, there has been considerable recent interest in uncemented designs with a hope of improving the survival time of primary implants. National Joint Registry data has been less favourable of uncemented designs thus far. We report our experience with these comparative implants and present our functional and radiological mid-term results. Trabecular metal is made of tantalum. It has an interconnecting 3-dimensional lattice structure which is 80% porous. It closely resembles the microstructural architecture of cancellous bone. Bone grows into the porous structure creating a strong bond between bone and implant. In this design, the tibial pegs are seated in a peripheral position, in denser cancellous bone when compared with a central peg. Tantalum offers an appropriate modulus of elasticity, reducing the likelihood of component lift-off and stress shielding. Over a 4.5 year period, between April 2007 and December 2011, 132 knees in 127 patients with a diagnosis of end stage osteoarthritis, underwent TKR at a single hospital (CMH), performed by a single surgeon (JH). All surgeries were performed with a thigh tourniquet, medial parapatellar approach, antibiotic and VTE prophylaxis, patellar resurfacing, and rapid recovery rehabilitation. 86 cemented TKRs in 78 patients (mean age 76 years), and 66 uncemented TKRs in 49 patients (mean age 68 years). All components were standard NexGen (Zimmer) implants. Follow-up was a mean of 40 months (range 6–87 months). We analysed the patient postoperative routine standing and recumbent anterior-posterior and lateral radiographs using the knee society TKA scoring system. All linear measurements were made using a PACS viewing system and analysed by 2 of the authors independently. There was no significant radiological lucent lines, and no single KSS > 4. Patients completed Oxford Knee Scores and Knee Society Scoring questionnaires to evaluate their functional outcomes. The mean OKS was 41, and KSS 89. In this period there were revisions in 3 cemented prostheses and 2 uncemented prostheses. 2 revisions were for infection, 2 for peri-prosthetic fracture following trauma, and 1 for unexplained pain. The uncemented TKR performs equally as well as its cemented counterpart in our experience, both clinically and radiologically, at mid-term follow-up of up to 7 years (mean 3.3 years)

INTRODUCTION. Understanding bone morphology is essential for successful computer assisted orthopaedic surgery, where definition of normal anatomical variations and abnormal morphological patterns can assist in surgical planning and evaluation of outcomes. The proximal femur was the anatomical target of the study described here. Orthopaedic surgeons have studied femoral geometry using 2D and 3D radiographs for precise fit of bone-implant with biological fixation. METHOD. The use of a Statistical Shape Model (SSM) is a promising venue for understanding bone morphologies and for deriving generic description of normal anatomy. A SSM uses measures of statistics on geometrical descriptions over a population. Current SSM construction methods, based on Principal Component Analysis (PCA), assume that shape morphologies can be modeled by pure point translations. Complicated morphologies, such as the femoral head-neck junction that has non-rigid components, can be poorly explained by PCA. In this work, we showed that PCA was impotent for processing complex deformations of the proximal femur and propose in its place our Principal Tangent Component (PTC) analysis. The new method used the Lie algebra of affine transformation matrices to perform simple computations, in tangent spaces, that corresponded to complex deformations on the data manifold. RESULTS. Both PCA and PTC were applied to the proximal femur dataset, from which selected femurs were reconstructed using the accumulation of components. PCA was deemed to have failed to reconstruct the surfaces because it required 65 components to achieve high coverage of the dataset. An important observation was that the head-neck junction was the most difficult section in the femur, requiring more components than other anatomical regions to reconstruct. This finding is consistent with the surgical observation that deformations occur in this junction for abnormal hip morphologies. PTC was successful in recovering 100% of the medical data using the only the first 5 components. We note that the encoding of deformation in PTC accounting for the performance increase. PTC outperformed PCA on the dataset in descriptive compactness. CONCLUSION. A standard SSM construction method was not adequate for analysing proximal femur surfaces because it could not easily model the complexity of non-rigid deformations at the head-neck junction. Principal tangent components, a novel method for using exponential maps on manifolds, accurately reconstructed the anatomical surfaces with very few components. Future work may include extending these concepts to describe joint diseases based on the shape of surfaces derived from volumetric data, such as CT or MRI. In conclusion, we have shown that differential geometry may be provide new insights to computational anatomy applications