Aim. Septic arthritis (SA) is considered a medical emergency. The most common etiological agents are glucose consuming bacteria, so we evaluated the clinical utility of synovial fluid (SF) glucose levels and other biochemical parameters for supporting the diagnosis of the disease and their association with a positive bacteria culture and joint destruction. Methods. Adult patients with SA diagnose were enrolled prospectively between July 2018 and October 2019. As control group, adults with knee osteoarthritis, meniscus and/or knee ligaments lesions were enrolled. SF samples were obtained from the joints by arthrocentesis/arthrotomy. Microbiological analyses of SF were performed using Brucella broth blood culture flasks, samples were incubated at 37°C with 5% CO. 2. for 24 hours. Gram stain, chocolate and blood agar were used for the identification and growth of the bacteria. SF glucose levels, pH and leukocyte esterase were measured as biochemical parameters using a glucometer and colorimetric test strips. The Outerbridge classification was used for grading the osteochondral injury. Furthermore, blood samples were collected from patients and control subjects for determining glucose levels. Results. We included 8 subjects with knee ligaments lesions, 6 with meniscus lesions and 5 with osteoarthritis as control group, as well as 20 patients with SA diagnose. The mean age of the patients was 57.8 years with a 65% of male predominance. The most common affected joint was the knee (85%). SF culture was positive in 60% of the cases and the most common etiological agent was Staphylococcus aureus (58.3%). SF glucose levels from patients were lower than the controls (P=0.0018) and showed the lowest concentration in patients with a positive culture (P=0.0004). There was also a difference between blood and SF glucose concentration from the positive culture patients (P<0.0001). Leucocyte esterase presented the highest values in positive culture patients (P=<0.0001) and a more acidic pH was found compared to the control group (P<0.0001). Regarding the osteochondral injury, the lowest concentrations of SF glucose were found in patients with a higher grade in the classification (P = 0.0046). Conclusions. SF glucose and leukocyte esterase concentrations might be a quick and cheap useful parameter for the physician for distinguishing between bacterial infection and not infected joint. In addition, the lowest SF glucose levels might give information about the joint damage due to the disease

Purpose. Operative treatment of Lisfranc joint injuries typically includes reduction and stabilization of the medial and middle columns of the midfoot. Mobility of the lateral column is preserved where possible, such that indications for lateral column stabilization rely upon the surgeons assessment of instability. In this case series, the indication for lateral column stabilization was defined by the results of an intra-operative stress test. The purpose of this study was to determine whether an intra-operative fluoroscopic stress test of the lateral column was sufficient to determine the need for internal fixation of the lateral column in Lisfranc joint injuries. Method. 35 adult patients with Lisfranc injuries operated in our centre by a single surgeon from 2005–2009 were reviewed. All patients had unstable midfoot fracture dislocations, treated by reduction and internal fixation including an intra-operative stress examination to determine the need for lateral column fixation. Patients were contacted for clinical and radiographic review at a mean of 31 months post injury. Functional outcome was assessed using general and joint-specific outcome tools (AOFAS midfoot score and LEM). Radiographic review included analysis of joint displacement and arthritic changes in preoperative, postoperative, and most recent radiographs. Results. Pre-operative imaging demonstrated displacement of the lateral column in 25 / 35 patients. Nineteen of these 25 had a stable reduction of the lateral column following medial and middle column fixation, based upon an intra-operative stress examination. Only 6 patients had persistent instability; these were treated with lateral column stabilization. Reduction of the lateral column was maintained at final follow up in 100 percent of 35 patients. Lateral midfoot pain was present in 5/6 patients requiring lateral fixation, compared to 1/(19) patient who did not require lateral fixation. AOFAS midfoot scores (mean) were 80 15. in patients with no evidence of lateral column instability, 79 15. in patients with preoperative displacement but a negative stress examination, and 77 18 in patients requiring lateral fixation (p>0.05). Post-traumatic arthrosis was present in 3/10 patients with no evidence of lateral column instability, 4/19 patients with preoperative displacement but a negative stress examination, and 4/6 in patients requiring lateral fixation (p>0.05). Conclusion. The decision to stabilize the lateral column during surgery on Lisfranc injuries was aided by an intra-operative fluoroscopic stress examination. Based upon the stress examination, 19 / 25 patients who had a displaced lateral column at the time of presentation avoided lateral fixation. None of these 19 patients treated without lateral fixation lost reduction in the follow up period. A fluoroscopic intra operative stress test safely reduced the need for lateral column fixation in displaced Lisfranc joint injuries

Osteoarthritis (OA) is a multifactorial debilitating disease that affects over four million Canadians. Although the mechanism(s) of OA onset is unclear, the biological outcome is cartilage degradation. Cartilage degradation is typified by the progressive loss of extracellular matrix components - aggrecan and type II collagen (Col II) – partly due to the up-regulation of catabolic enzymes - aggrecanases a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS-) 4 and 5 and matrix metalloproteinases (MMPs). There is currently no treatment that will prevent or repair joint damage, and current medications are aimed mostly at pain management. When pain becomes unmanageable arthroplastic surgery is often performed. Interest has developed over the presence of calcium crystals in the synovial fluid of OA patients, as they have been shown to activate synovial fibroblasts inducing the expression of catabolic agents. We recently discovered elevated levels of free calcium in the synovial fluid of OA patients and raised the question on its role in cartilage degeneration. Articular cartilage was isolated from 5 donors undergoing total hip 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 supplemented with 10% heat-inactivated FBS. OA and normal human articular chondrocytes (PromoCell, Heidelberg, Germany) were transferred to 6-well plates in culture medium containing various concentrations of calcium (0.5, 1, 2.5, and 5 mM CaCl2), and IL-1β. Cartilage explants were prepared from the same donors and included cartilage with the cortical bone approximately 1 cm2 in dimension. Bovine articular cartilage explants (10 months) were used as a control. Explants were cultured in the above mentioned media, however, the incubation period was extended to 21 days. Immunohistochemistry was performed on cartilage explants to measure expression of Col X, MMP-13, and alkaline phosphatase. The sulfated glycosaminoglycan (GAG, predominantly aggrecan) content of cartilage was analyzed using the 1,9-dimethylmethylene blue (DMMB) dye-binding assay, and aggregan fragmentation was determined by Western blotting using antibody targeted to its G1 domain. Western blotting was also performed on cell lysate from both OA and normal chondrocytes to measure aggrecan, Col II, MMP-3 and −13, ADAMTS-4 and −5. Ca2+ significantly decreased the proteoglycan content of the cartilage explants as determined by the DMMB assay. The presence of aggrecan and Col II also decreased as a function of calcium, in both the human OA and bovine cartilage explants. When normal and OA chondrocytes were cultured in medium supplemented with increasing concentrations of calcium (0.5–5 mM Ca2+), aggrecan and Col II expression decreased dose-dependently. Surprisingly, increasing Ca2+ did not induce the release of MMP-3, and −13, or ADAMTS-4 and-5 in conditioned media from OA and normal chondrocytes. Interestingly, inhibition of the extracellular calcium-sensing receptor CaSR) reversed the effects of calcium on matrix protein synthesis. We provide evidence that Ca2+ may play a direct role in cartilage degradation by regulating the expression of aggrecan and Col II through activation of CaSR

Introduction. Version abnormalities of the femur, either retroversion or excessive anteversion, cause pain and hip joint damage due to impingement or instability respectively. A retrospective clinical review was conducted on patients undergoing a subtrochanteric derotation osteotomy for either excessive anteversion or retroversion of the femur. Methods. A total of 49 derotation osteotomies were performed in 39 patients. There were 32 females and 7 males. Average age was 29 years (range 14 to 59 years). Osteotomies were performed closed with an intramedullary saw (Figure 1). Fixation was performed with a variety of intramedullary nails. Patients requiring a varus or valgus intertrochanteric osteotomy were excluded. Pure rotational corrections only were performed. Twenty-four percent of patients had a retroversion deformity (average −8° retroversion, range +1 to −23°), 76% had excessive anteversion of the femur (average +36° anteversion, range +22° to +53°). Etiology was post-traumatic in 5 (10%), diplegic cerebral palsy in 4 (8%), fibrous dysplasia in 2 (4%), Prader-Willi Syndrome in 1 (2%) and idiopathic in 37 (76%). Previous surgery had been performed in 51% of hips. Fifty-seven percent underwent concomitant surgery with the index femoral derotation osteotomy, including hip arthroscopy in 39% (labral debridement alone or with femoral neck osteochondroplasty), a tibial derotation osteotomy in 12% and periacetabular osteotomy in 6%. Concomitant tibial osteotomies were performed to correct a compensatory excessive external tibial torsion that would be exacerbated in the correction of excessive femoral anteversion. The modified Harris Hip Score was used to assess the results in patients with a minimum of 24 months follow-up. Results. There were no non-unions. Average time to union was 3.3 months. One late infection occurred 10 months after surgery, treated successfully with hardware removal and antibiotics. Two patients, one with Prader-Willi syndrome and one with Ehlers-Danlos syndrome, were converted to total hip replacement. At an average follow-up of 6.1 years (range 2 to 19.1 years), the modified Harris Hip Score improved by 26 points (p< 0.001, Wilcoxon signed-ranks test). The results were rated as excellent in 71%, good in 22%, fair in 5% and poor in 3%. Subsequent surgery was required in 73%, 93% of which were hardware removals. Discussion and Conclusion. A closed, subtrochanteric derotation osteotomy of the femur is a safe and effective procedure to treat either femoral retroversion or excessive anteversion. Excellent or good results were obtained in 93%, despite the need for subsequent hardware removal in more than two-thirds of the patients. For figures/tables, please contact authors directly.

Acute septic arthritis of the knee can lead to joint damage or sepsis, if early diagnosis and treatment fail to occur, which includes drainage of the joint, adequate antibiotic coverage and resting of the knee. Classically, drainage of the knee was performed either with multiple aspirations or open arhtrotomy. The arthroscopic approach has becoming widely accepted, as it allows adequate drainage of the pus and debridement with partial or total sinovectomy of the joint. The aim of this study was to evaluate the differences between arthroscopy and open arthrotomy in the clinical outcomes and rate of recurrence in patients with septic arthritis of the knee joint. We reviewed patients with acute septic arthritis of the knee admitted in our center between January 2010 and December 2014. The criteria for diagnosis was report of purulent material when arhtrotomy or arthroscopy was performed or a positive culture of the joint fluid. Patients with recent surgery or documented osteomyelitis of the femur or tíbia were excluded. We used the Oxford Knee Score (OKS) to classify the clinical outcomes in the end of follow-up, and registered the rate of recurrence in each group. The statistical evaluation of the results was performed using Student's t-test. 65 patients were treated during this period, 37 by an open arthrotomy through a lateral supra-patellar aproach, and 28 by arthroscopy through 2 standard anterior portals. All the patients were imobilized with a cast or orthosis in the immediate post-operation period for a mean period of 13 days in the arthrotomy group (8–15) and 9 days in the arthroscopy group (6–12) and received endovenous antibiotics for at least 10 days, followed by oral antibiotics for a mean total of 36 days in the the arthrotomy group (30–48) and 32 days in the arthroscopy group (22–36). The mean follow-up was 22 months in the arthrotomy group (8–28 months) and 18 months in the arthroscopy group (14–24). The mean OKS was 31 in the the arthrotomy group (21–39) and 35 in the arthroscopy group (25–44). There was 1 recurrence in the arthrotomy group and 1 recurrence in the arthroscopic group, both managed by knee arthrotomy. Drainage is a key step in treatment of knee pyoarthrosis, either through an open or an arthroscopic approach. Both seem to be equally effective, with no significant statistical difference in terms of recurrence. The functional results tend to favour the arthroscopic approach, but with no statistical significance

Septic arthritis is a therapeutic emergency with a high mortality rate (about 11%)(1). Inadequate treatment can cause permanent joint damage. Management of the septic arthritis includes prompt antibiotic treatment as well as joint-decompression and removal of purulent material(2). It is still discussed controversially and there is little evidence which surgical concept is preferable: arthroscopy with lavage and debridement or open arthrotomy with synovectomy(3,4). The aim of the study was to compare efficacy of arthroscopy and arthrotomy in patients with septic gonarthritis. We evaluated 70 consecutive patients who underwent arthroscopy or arthrotomy at our clinic, because of a bacterial monarthritis of the knee between 2002 and 2010. Our primary outcome was the early recurrence of infection (> 3 months after surgery), which made a second surgery necessary. We compared patients who suffered reinfection and those who did not, in regard to the surgery type as well as potential confounders like comorbidity (measured by Charlson comorbidity index), age, body mass index (BMI), Gächter's -, Kellgren and Lawrence - and Outerbridge classification, duration of symptoms and inflammatory parameters. Furthermore we evaluated differences of the confounders between the surgery groups. From the 70 patients 41 were treated arthroscopic and 29 with arthrotomy. In total eight patients (11.4%) had to undergo a second surgery because of early reinfection. The rate was significantly higher in patients treated with arthrotomy (n=6; 20.7%) compared to those treated with arthroscopy (n=2; 4.9%) (p=0.041). Whereas we found no significant influence of potential confounders between the reinfection group and the group where primary eradication was achieved. Patients who underwent arthrotomy were significantly older, had more comorbidities (both p<0.001) and higher grades of osteoarthritis according to Kellgren and Lawrence classification (p=0.023). In order to adjust the study population towards confounders we performed a subgroup analysis on patients of the second and third age percentile. When we repeated our analysis we still found a significant higher reinfection rate in the arthrotomy group (p=0.036). At the same time there were no differences in prevalence of confounders, neither between the two surgery groups, nor between the reinfection and the primary eradication group. Patients with bacterial monarthritis of the knee who were treated with arthroscopy had a significantly lower reinfection rate than those treated with arthrotomy. As arthroscopy is the less invasive and more sufficient method it should be considered the routine treatment according to our data

Osteoarticular loss in a major weightbearing joint is one of the many consequences of military conflict. While minor in terms of life and limb salvage, when rehabilitation is being planned, a small amount of joint damage can make a large impact on the level of long term disability. Reconstruction methods include allograft, massive replacement, arthrodesis and amputation. We have been developing a suite of technologies that contribute to the reconstruction of such injuries including assessment of disability in a fully instrumented gait lab, modelling of the injury using low dose CT, analysis of the extent of loss and creation of stereolithograph files of the bones, planning of the surgical procedure including implants as needed, custom manufacture of osteotomy guides and prostheses if required and technology assisted surgery, including active constraint robots. We report 3 cases of soldiers who have suffered osteoarticular loss to part of the knee, two from high velocity rounds and one from an IED. All 3 have received custom partial knee replacements preserving their cruciates, the other compartment and the patella-femoral joint. No major technical issues have been encountered. The surgery is quick and recovery simple, with the prospect of normal painfree pedestrian life. Exchange of the bearing will be necessary. It is expected and planned for once a decade as a day case procedure. While the surgery is expensive, it is highly cost-effective, as it restores near normal gait. It does not appear to be particularly risky, as the volume of tissue being excised is small, and highly constrained. The same approach is now being developed for deployment in civilian life for post traumatic osteoarthritis

Introduction. Lisfranc joint injuries account for only 0.2% of all fractures but early diagnosis improves the chances of a better outcom]. Radiographic signs, such as diastasis (>2mm) of the 1–2 interspace, are subtle and. often missed, leading to a poorer outcome. We present a new radiographic sign, less likely to result in missed diagnoses. Null nypothesis: The intermetarsal angle remains unchanged in Lisfranc injuries. Method. A series of radiographs demonstrating Lisfranc injury were interspersed with normal and postoperative cases. Evidence of fixation was obscured. A selection of Foundation and Core Trainee medical staff measured the intermetatarsal angle (IMA) on two separate occasions. The measuring technique was demonstrated with no explanation for the reason behind the measurement. Results. The intra-class correlation (ICC) between observers was 0.96 and a mean 0.86 (range 0.69–0.96) for individual observers. IMA on comparative weight bearing AP views of injured and normal side, using Wilcoxon-signed rank test demonstrated a P< 0.0001 with mean values of 6.6 degrees (normal) versus 4.85 degrees (injured) and standard deviation of 1.97 & 1.91 degrees respectively. Conclusion. The high ICC value suggests that this radiographic sign is easily taught, reliable and reproducible. Analysis of individual angles suggests that there is a significant difference between the normal and pathological IMA. We therefore reject our null hypothesis. The data supports our proposition that that the IMA becomes more parallel in Lisfranc injuries and that this is an easily recognised sign, which could help reduce the incidence of missed injuries. Elucidation of the exact anatomical pathology responsible is the basis for further, anatomical, studies

Purpose of the Study:. Spontaneous intraarticular haemorrhages are the most frequent bleeding episodes encountered in the haemophiliac population, causing pain, joint deformity and arthropathy. Chronic haemophiliac arthropathy is characterised by persistent joint swelling, proliferative synovitis, and damage to or loss of articular cartilage. Elimination of the synovitis is the key to prevention of recurrent intraarticular haemorrhages and joint damage. The purpose of the study was to investigate the indications for, and outcome of, radioactive synoviorthesis for haemophiliac arthropathy. Methods:. A retrospective study was done to assess the results of 12 intra-articular injections of radioactive Yttrium-90 colloid, performed in 10 patients from November 1993 to December 2006. Patients were referred by the Haematology Unit if they had a target joint, as defined as >2 bleeds into the same joint in the preceding 6 months. Follow up was conducted at 6 monthly intervals, assessing clinical and radiological outcomes. The radiological involvement of the target joint, the pre- and post-treatment range of movement, presence of synovitis and bleeding events were compared from presentation to that at follow up. Range of movement of each target joint was assessed and compared to that at follow-up. Results:. The average age at time of injection was 10.6 years (range 6–15). The duration of follow-up was 35 months (range 6 to 60 months). The involved joints had an average of 2 bleeds each in the 6 months preceding the injection (24 events). Following Yttrium injection only 1 out of 12 joints had a bleed in the subsequent 6 months (1 event). Synovitis of the target joint resolved in 11 of 12 joints. Nine target joints (75%) showed a favourable improvement in range of movement. Those with a favourable radiological score had a better clinical outcome, but even those with a poor score showed improvement. Conclusion:. In this study, intra-articular injection of radioactive Yttrium-90 colloid was shown to:. –. Significantly reduce bleeding events in a Haemophiliac cohort. –. Resolve synovitis in 11 out of 12 joints with haemophiliac arthropathy. –. Improve range of movement in the majority of patients. –. This was best in those with a better radiological appearance at presentation. –. Those with a poorer radiological grade also showed some improvement suggesting that while results are less certain, patients may still benefit from the intervention

Knowledge of joint kinematics in the lower limb is important for understanding joint injuries and diseases and evaluating treatment outcomes. However, limited information is available about the joint kinematics required for high flexion activities necessary for floor sitting life style. In this study, the hip and knee joint kinematics of ten healthy male and ten healthy female subjects were investigated using an electromagnetic motion tracking system. We measured the hip and knee joints' functions moving into 1) kneeling on knees with legs parallel without using arms, 2) kneeling on knees with legs parallel with using arms, 3) kneeling on knees with one foot forward without using arms, 4) cross-legged sitting, 5) kneeling with legs to the side, 6) sitting with legs stretched out, and 7) deep squatting, and moving out of the above seven conditions. Conditions 1) through 3) were Japanese seiza style. On conditions 4) through 7), arms were not used. We further measured the functions of putting on and taking off a sock under such conditions as 8) with standing position and 9) sitting position (Fig 1). Here special attention was paid for flexion and extension motion. The data were used to produce the pattern of joint angulation against the percentage of the cycle for each individual conducting each activity. The kinematic curves were split into 3 phases: moving into the rest position, the rest position and out of the rest position. It should be noted that the moving into and the rest phases were split at the moment when the peak value was determined during the moving into phase. Thus the initiation of the rest phase on the curve was not coinciding with the moment the subject reached at the rest position. This was necessary in order not for the mean kinematic curve to become too dull in shape. Same was true when the end of rest phase was determined. The maximum hip and knee joint angles during the cycle were determined. Further a relationship between the hip and knee joint excursions were investigated. The results indicated condition 8) requires the maximum flexion angles to the hip among all conditions, 157.5 ± 20.4° and condition 3) to the knee joint, 157.1 ± 10.0° respectively (Fig 2). The results also indicated in many activities, the maximum joint angles were recorded not during the rest phase but during the moving into or out of phase. In any conditions even including donning on and off a sock, a strong relationship was found between the hip and knee joints motion (Fig 3), indicating the bi-articular muscles' co-contraction during the sit to stand activities. The data presented in this study will increase the knowledge of high-flexion needs especially in non-Western cultures and provide an initial characterization of the prosthesis kinematics in high flexion

Introduction:. The sealing function of the acetabular labrum is central to the stability of the hip and the health of the joint. Disruption of the labrum has been shown to reduce intra-articular pressure and increase the rate of cartilage consolidation during static loading. Functional activities require movement of the hip through wide ranges of joint motion which disrupt joint congruency, and thus may alter the seal. This study was performed to test the hypothesis that the sealing function of the labrum varies with the position of the hip during functional activities. Methods:. Six fresh cadaveric hip joint specimens were obtained from donors of average age 45.5 ± 16.1 years (range 25–63 years). Each specimen was dissected free of soft tissue, leaving the capsule and labrum intact, potted in mounting fixtures, and placed in a loading apparatus. Catheters were inserted into the central and peripheral compartments of each hip to allow infusion of fluid and monitoring of compartment pressures via miniature transducers (OMEGA Engineering, Inc). After application of a joint load of 0.50 BW, fluid was introduced into the central compartment at a constant rate until transport was indicated by a rise in pressure within the peripheral compartment. These measurements were performed with each hip placed in 10 functional positions ranging from −5 to 105 degrees of flexion, −5 to 13 degrees of abduction, and −25 to 35 degrees of external rotation simulating the sequential stages of gait, stooping, and pivoting. Motion analysis was performed via reflective marker arrays attached to the femur and pelvis to allow computer visualization of the position of the pelvis and femur using CT reconstructions. In each hip position, we measured the peak pressure (kPA) developed within the central compartment prior to fluid transfer to the peripheral compartment. Results:. The sealing capacity of the labrum varied wit hip joint position (p = 0.003). Peak pressures were greatest during pivoting (average peak central compartment pressure: 33.9 ± 5.0 kPa; p = 0.001), compared to both gait (22.5 ± 4.1 kPa; p = 0.047) and stoop (9.6 ± 3.6 kPa; p = 0.004). During the pivoting maneuver, peak pressures increased in a linear fashion with increasing hip extension and external rotation. Conversely, the sealing capacity of the labrum was reduced during stooping once hip flexion exceeded 70° and internal rotation was greater than 15°. The positions simulating gait consisted of minimal to no joint rotation, and peak pressures varied little between the four positions. Discussion:. The sealing ability of the labral seal increases with external rotation of the hip joint, and decreases with increased flexion combined with internal rotation. Changes in joint congruency that occur when the hip is placed in high flexion and internal rotation may be responsible for the loss of sealing function of the labrum during stooping. Our results reveal the importance of joint position during functional activities on the ability of the labrum to seal the central compartment of the hip. Future research will further assess the relationship between these positions and joint injury

Objectives:. Experimental disruption of the labrum has been shown to compromise its sealing function and alter cartilage lubrication. However, it is not known whether pathological changes to the labrum secondary to femoro-acetabular impingement (FAI) have a similar impact on labral function. This study was performed to determine the effect of natural labral damage secondary to abnormal femoral morphology on the labral seal. Methods:. Ten intact hip specimens were obtained from male donors (47.8 ± 1.5 yrs) for use in this study. CT reconstructions demonstrated that 6 specimens were of normal morphology, while 4 displayed morphology typical of cam-FAI. Specimens were dissected free of the overlying soft tissue, leaving the capsule and labrum intact. Each specimen was potted and placed in a loading apparatus (0.5 BW). Pressures developed within the central and peripheral compartments were monitored with miniature pressure transducers. The sealing capacity of the labrum was measured by introducing fluid into the central compartment at a constant rate until transport was detected from the central to the peripheral compartment. These measurements were performed in 10 functional positions simulating sequential stages of gait, stooping, and pivoting. During testing, the 3D motion of the femoral head in the acetabulum was measured with motion analysis combined with computer visualization. Peak pressures were compared between specimens with and without labral damage for each of the three activities (p < 0.05). Results:. Visual observation following testing showed that each specimen with CAM morphology exhibited secondary damage of the labrum and the adjacent chondral surface, while specimens of normal morphology were undamaged. Average peak central compartment pressure was affected by the presence of labral damage secondary to impingement. The specimens with labral damage exhibited reduced peak central compartment pressure during pivot (15.2 ± 2.6 vs. 42.3 ± 7.7 kPa; p = 0.007) when compared to intact specimens. Conversely, no differences in peak pressure were detected between specimens with and without labral damage during simulated gait (21.1 ± 6.0 vs. 22.0 ± 4.2 kPA; p = 0.9) and stooping (8.6 ± 2.4 vs. 7.5 ± 2.6 kPa; p = 0.78). Conclusions:. The acetabular seal, quantified by intra-articular pressure, was affected by the presence of labral damage secondary to impingement. The reduction in ultimate pressure occurred during pivoting; however, the seal was maintained during gait and stooping. These results are in contrast to previous studies which reported a complete negation of the seal in response to experimentally-created labral disruption. As degeneration is progressive with repetitive impingement, loss of the seal starts to be seen during pivoting and may progress from there, but at this time point (50 years), the seal remains intact during gait and stooping. Our study highlights the importance of using clinically relevant joint injury models to study labral function

Objectives

Salubrinal is a synthetic agent that elevates phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) and alleviates stress to the endoplasmic reticulum. Previously, we reported that in chondrocytes, Salubrinal attenuates expression and activity of matrix metalloproteinase 13 (MMP13) through downregulating nuclear factor kappa B (NFκB) signalling. We herein examine whether Salubrinal prevents the degradation of articular cartilage in a mouse model of osteoarthritis (OA).

Construction of a functional skeleton is accomplished through co-ordination of the developmental processes of chondrogenesis, osteogenesis, and synovial joint formation. Infants whose movement in utero is reduced or restricted and who subsequently suffer from joint dysplasia (including joint contractures) and thin hypo-mineralised bones, demonstrate that embryonic movement is crucial for appropriate skeletogenesis. This has been confirmed in mouse, chick, and zebrafish animal models, where reduced or eliminated movement consistently yields similar malformations and which provide the possibility of experimentation to uncover the precise disturbances and the mechanisms by which movement impacts molecular regulation. Molecular genetic studies have shown the important roles played by cell communication signalling pathways, namely Wnt, Hedgehog, and transforming growth factor-beta/bone morphogenetic protein. These pathways regulate cell behaviours such as proliferation and differentiation to control maturation of the skeletal elements, and are affected when movement is altered. Cell contacts to the extra-cellular matrix as well as the cytoskeleton offer a means of mechanotransduction which could integrate mechanical cues with genetic regulation. Indeed, expression of cytoskeletal genes has been shown to be affected by immobilisation. In addition to furthering our understanding of a fundamental aspect of cell control and differentiation during development, research in this area is applicable to the engineering of stable skeletal tissues from stem cells, which relies on an understanding of developmental mechanisms including genetic and physical criteria. A deeper understanding of how movement affects skeletogenesis therefore has broader implications for regenerative therapeutics for injury or disease, as well as for optimisation of physical therapy regimes for individuals affected by skeletal abnormalities.

Cite this article: Bone Joint Res 2015;4:105–116