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Osteochondrosis (OC) is a focal disturbance of endochondral ossification due to a failure of blood supply to the epiphyseal growth cartilage. In dogs, OC most commonly affects the shoulder joint, followed by the elbow, tarsal, and stifle joints. The condition is associated with clinical signs such as lameness and pain and the prognosis varies depending on the affected joint. Most epidemiologic studies of OC in dogs were performed over 20 years ago, and updated estimates of disease incidence are lacking. Therefore, the objectives of this study were to provide population-based estimates of the incidence rate, cause-specific mortality rate, and age at diagnosis of appendicular OC (AOC, including OC of the shoulder, elbow, stifle, and tarsal joints) and stifle and tarsal OC separately, using data from Agria Djurförsäkring in Sweden (2011–2016). Further, the study aimed to evaluate the risk of OC in subgroups divided by breed and sex and describe previous, concurrent, and subsequent diagnoses of the affected joint in dogs with stifle or tarsal joint OC. The study population included just over 600,000 dogs, of which 685 were affected by AOC. Stifle joint OC (n = 113) was more common than tarsal joint OC (n = 80). The incidence rate of AOC was 3.77 (95% confidence interval (CI): 3.49–4.07) cases per 10,000 dog-years at risk, while the incidence rate of stifle and joint tarsal OC was 0.64 (95% CI: 0.53–0.77) and 0.43 (95% CI: 0.34–0.54) cases per 10,000 dog-years at risk, respectively. All breeds at increased risk of AOC were large or giant, and male dogs had an increased risk of AOC compared to female dogs (RR 1.76, 95% CI: 1.50–2.07, p < 0.001). The median age at first diagnosis during the study period was 0.74 (0.32–11.5) years for AOC, 2.62 (0.45–8.82) years for stifle joint OC, and 0.73 (0.35–7.35) years for tarsal joint OC. Of the dogs with stifle or tarsal joint OC, 30.2% and 15.0% had a previous diagnosis of stifle/tarsal joint pain or other unspecific clinical signs, respectively, and 13.8% of the dogs with stifle joint OC suffered subsequent cruciate ligament rupture. Osteochondrosis was the most common reason for euthanasia in the affected dogs. In total, 77 dogs were euthanised due to AOC during the study period. • There were 685 cases of appendicular osteochondrosis (AOC) in the study population. • Stifle joint OC was more common than tarsal joint OC. • All breeds at increased risk of AOC were large or giant. • The median age at first diagnosis of AOC was 0.74 years. • The risk of OC-related euthanasia varied with breed. [ABSTRACT FROM AUTHOR]

Osteoarthritis is one of the most common diseases in veterinary medicine. There are various causes for joints developing OA, with some of them being well investigated, while others are still a matter of speculation. In this retrospective study we examined the prevalence of OA in the shoulder, elbow, hip and stifle joints in a clinic population of dogs older than 8 years, which were presented mostly due to orthopaedic complaints. Dogs were included in the study if one or more of the aforementioned joints was included in the radiographs. Radiographs were reviewed by three different observers and graded by severity. Prevalence of OA was 39.2%, 57.4%, 35.9% and 36.4% for the shoulder, elbow, hip and stifle, respectively. There was no correlation between higher grades of OA and weight as well as age, but significantly higher prevalence of OA in heavier groups when grouped for weight. Sex and castration status did not affect presence of OA. As most of the examined joints were free of OA, radiographic findings suggestive of OA should not be considered normal in senescent dogs. • Most examined joints were free of osteoarthritis (OA). • Most examined elbows showed radiographic signs of OA. • Heavier dogs showed more and higher grades of OA than lighter ones. • Of 126 examined joints in Dachshunds, 119 (91.3%) were found to be free of OA. • There was no difference in prevalence of OA for gender and castration status. [ABSTRACT FROM AUTHOR]

Partial anterior cruciate ligament (p-ACL) rupture is a common injury, but the impact of a p-ACL injury on in vivo joint kinematics has yet to be determined in an animal model. The in vivo kinematics of the ovine stifle joint were assessed during 'normal' gait, and at 20 and 40 weeks after p-ACL transection (Tx). Gross morphological scoring of the knee was conducted. p-ACL Tx creates significant progressive post-traumatic osteoarthritis (PTOA)-like damage by 40 weeks. Statistically significant increases for flexion angles at hoof-strike (HS) and mid-stance (MST) were seen at 20 weeks post p-ACL Tx and the HS and hoof-off (HO) points at 40 weeks post p-ACL-Tx, therefore increased flexion angles occurred during stance phase. Statistically significant increases in posterior tibial shift at the mid-flexion (MF) and mid-extension (ME) points were seen during the swing phase of the gait cycle at 40 weeks post p-ACL Tx. Correlation analysis showed a strong and significant correlation between kinematic changes (instabilities) and gross morphological score in the inferior-superior direction at 40 weeks post p-ACL Tx at MST, HO, and MF. Further, there was a significant correlation between change in gross morphological combined score (ΔGCS) and the change in location of the helical axis in the anterior direction (ΔsAP) after p-ACL Tx for all points analyzed through the gait cycle. This study quantified in vivo joint kinematics before and after p-ACL Tx knee injury during gait, and demonstrated that a p-ACL knee injury leads to both PTOA-like damage and kinematic changes. [ABSTRACT FROM AUTHOR]

Subchondral lucency (SCL), also referred to as subchondral bone cysts, can cause clinical problems in horses and humans. In humans, SCLs occur in youths and adolescents [1] due to mechanical factors (often related to athletics) and in skeletally mature individuals secondary to osteoarthritis (OA). In horses, SCL most commonly occurs in the medial femoral condyle (MFC) of growing horses (without OA), and causes lameness. The cause of equine SCL is debated, but bone trauma due to overload is the likely mechanism. Investigating the biomechanics of the healthy and cystic MFC is important to understand cyst growth and to provide a foundation for new treatment strategies. We hypothesize that SCL alters the mechanical environment of surrounding bone, which in the presence of continued loading, may lead to enlargement of the SCL. In this study, we developed and validated a finite element model of an equine stifle joint and investigated the stresses associated with varying sizes of SCL. We found substantial differences in tensile and shear stress at various stages of SCL development that suggest further bone damage leading to SCL enlargement. These data provide a first step in understanding of the altered mechanics of subchondral bone surrounding a SCL. Additional studies may provide the basis for improved treatment strategies for SCL in young horses, and may improve the understanding of SCL in humans. [ABSTRACT FROM AUTHOR]

There is as yet no clear design method for a rational reinforcement arrangement in a beam-column knee joint with mechanical anchorages because internal stresses, internal cracks, and the failure process have not been well understood. Previous experiments have shown that local reinforcement along the anchorages or the placing of an additional concrete block on the top surface of the joint can prevent anchorage failure due to local stresses from the anchorage plates. In this study, a meso-scale discrete analysis using 3D rigid body spring model (RBSM) is conducted to investigate the failure process and to investigate the effect of these measures. By studying the internal stresses and cracks in a beam-column joint with mechanical anchorages, the failure process is revealed: with bonding along the development length of the anchorages, diagonal cracks begin to occur and these cracks propagate to the top surface of the beam-column joint where they open at the surface, and finally, the opening of diagonal cracks takes place. Local reinforcement placed along the anchorages is shown to have two effects: to increase bond performance along the development length of the anchorages and to restrict the opening of the diagonal cracks. An additional concrete block placed on the top surface of the beam-column joint also has two effects: to increase bond performance along the development length of the anchorages and to restrict crack penetration to the top surface of the joint. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effects of arthroscopic irrigation on cartilage superficial zone lubricin and surface friction. Arthroscopic partial meniscectomy is one of the most commonly performed orthopedic surgeries in the United States, but rates of osteoarthritis progression following this procedure are high. The effect of arthroscopic irrigation on articular surface lubrication has not been previously considered as a contributing factor in outcomes after arthroscopy. Fourteen bovine stifle joints were randomized to receive arthroscopic irrigation ( n =7) or no treatment ( n =7). Full-thickness osteochondral explants from these joints underwent friction testing to measure static and dynamic coefficients of friction. Following mechanical testing, samples were fixed and stained for lubricin. Percent integrated density, a measure of the amount of lubricin in the superficial zone (0–100 µm depth), was determined. Static and dynamic coefficients of friction were found to be significantly greater in arthroscopy specimens compared to controls ( p =0.02 and p <0.001, respectively). Percent integrated density of lubricin in the superficial zone was significantly lower in arthroscopy specimens compared to controls ( p <0.001). [ABSTRACT FROM AUTHOR]

Despite having a fully functional knee and hip in both legs, asymmetries in joint moments of the knee and hip are often seen in gait of persons with a unilateral transtibial amputation (TTA), possibly resulting in excessive joint loading. We hypothesize that persons with a TTA can walk with more symmetric joint moments at the cost of increased effort or abnormal kinematics. The hypothesis was tested using predictive simulations of gait. Open loop controls of one gait cycle were found by solving an optimization problem that minimizes a combination of walking effort and tracking error in joint angles, ground reaction force and gait cycle duration. A second objective was added to penalize joint moment asymmetry, creating a multi-objective optimization problem. A Pareto front was constructed by changing the weights of the objectives and three solutions were analyzed to study the effect of increasing joint moment symmetry. When the optimization placed more weight on moment symmetry, walking effort increased and kinematics became less normal, confirming the hypothesis. TTA gait improved with a moderate increase in joint moment symmetry. At a small cost of effort and abnormal kinematics, the peak hip extension moment in the intact leg was decreased significantly, and so was the joint contact force in the knee and hip. Additional symmetry required a significant increase in walking effort and the joint contact forces in both hips became significantly higher than in able-bodied gait. [ABSTRACT FROM AUTHOR]

Lateral wedge insoles (LWIs) reduce the peak external knee adduction moment (KAM). However, the efficacy of LWIs is limited in certain individuals for whom they fail to decrease KAM. Possible explanations for a lack of desired LWI response are variations in foot alignments. The purpose of this study was to evaluate whether the immediate biomechanical effects of LWIs depend on individual foot alignments during gait. Fifteen healthy adults participated in this study. Their feet were categorized as normal, pronated, and supinated using the foot posture index. All subjects were subsequently requested to perform a normal gait under barefoot and LWI conditions. A three-dimensional motion analysis system was used to record the kinematic and kinetic data, included peak KAM, KAM impulse (KAAI), center of pressure displacement, and knee-ground reaction force lever arm (KLA). Furthermore, lower limb frontal plane kinematic parameters at the rear foot, ankle, knee, and hip were evaluated. Among all feet, there was no significant difference in the peak KAM and KAAI between the conditions. In contrast, the peak KAM was significantly reduced under the LWI condition relative to the barefoot condition in the normal foot group. Reductions in the peak KAM were correlated with a more lateral center of pressure and reduced KLA. In addition, a reduced KLA was correlated with decreased hip adduction. LWIs significantly reduced the peak KAM in normal feet, indicating that biomechanical effects of LWIs vary between individual foot alignments. Our findings suggest that it is helpful to assess individual foot alignment to ensure adequate insole treatment for patients with knee osteoarthritis. [ABSTRACT FROM AUTHOR]

Lateral trunk lean (LTL) is a proposed intervention for knee osteoarthritis but increased muscular demands have not been considered. The objective was to compare lower extremity and trunk muscle activation and joint mechanics between normal and increased LTL gait in healthy adults. Participants (n=20, mean age 22 years) were examined under two gait conditions: normal and increased LTL. A motion capture system and force plates sampled at 100 and 2000Hz respectively were used to determine joint angles and external moments including LTL angle and external knee adduction moment (KAM). Surface electromyography, sampled at 2000Hz, measured activation of six trunk/hip muscles bilaterally. Peak LTL angle, peak KAM, gait speed, and mean values from electromyography waveforms were compared between normal and LTL conditions using paired t-tests or 2-way analysis of variance. There was a significant (p<0.05) increase in peak LTL angle, decrease in first but not second peak KAM, and decrease in gait speed during LTL gait. There were significant (p<0.01) increases in external oblique and iliocostalis muscle activation during LTL gait. There was no change in activation for internal oblique, rectus abdominis, longissimus, and gluteus medius. LTL gait decreased early/mid-stance KAM demonstrating its ability to decrease medial compartment knee loading. Increases in external oblique and iliocostalis activation were present but small to moderate in size and unlikely to lead to short term injury. Longitudinal studies should evaluate the effectiveness of increased LTL for knee osteoarthritis and if the increase in muscular demands leads to negative long term side effects. [ABSTRACT FROM AUTHOR]

Objective To compare the quality of anesthesia and analgesia from femoral and sciatic nerve blocks ( FS) with bupivacaine and dexmedetomidine with that from an epidural injection ( EPI) with bupivacaine and buprenorphine in dogs undergoing unilateral stifle arthroplasty. Study design Prospective, blinded, randomized, clinical comparison. Animals Twenty-six dogs weighing 36 ± 10 kg and aged 5 (1-11) years. Methods Dogs were randomly assigned to either FS [ n = 13; bupivacaine 0.5% (0.5 mg kg−1) plus dexmedetomidine (0.1 μg kg−1) for each nerve] or EPI [ n = 13; bupivacaine 0.5% (1 mg kg−1) plus buprenorphine (4 μg kg−1)]. Data collected included intraoperative cardiopulmonary variables and postoperative pain scores (Glasgow Composite Pain Scale), sedation scores, opioid consumption, time to urination and time to return of various behaviors. Rescue analgesia (hydromorphone 0.05 mg kg−1) was administered intravenously whenever pain scores were ≥ 6/24. Subsequent data from rescued dogs were excluded from further analysis. Results No differences were found for any of the variables evaluated during and after anesthesia. Over 60% (nine dogs in FS, eight dogs in EPI) of patients from either group did not need additional analgesia within the 24 hour observational period. Three and four patients in FS and EPI, respectively, that required rescue analgesia did so within the first 30 minutes after extubation; only one patient in EPI required supplemental analgesia more than 4 hours after extubation. One patient in each group did not urinate spontaneously for 24 hours. Conclusions and clinical relevance Both techniques have the potential to provide sufficient analgesia for up to 24 hours in approximately two-thirds of dogs. Careful observation for signs of pain and preparedness to intervene is still recommended. The incidence of urinary retention was low in both groups. These techniques show promise for providing high-quality analgesia for stifle arthroplasty. [ABSTRACT FROM AUTHOR]

Purpose The purposes of this study were to (1) correlate the ultrashort echo time (TE) signal intensity of the pointwise encoding time reduction with radial acquisition (PETRA) sequence with that of the ultrashort echo (UTE) sequence using in vivo meniscal ultrashort TE imaging of the knee with a 3-Tesla (3 T) clinical magnetic resonance imaging (MRI) scanner and (2) compare the two ultrashort TE sequences in three groups of patients with normal, degenerated, and torn knee menisci. Materials and methods Following institutional review board approval, we analyzed 47 knee MRIs of 46 patients who presented with knee pain and underwent knee MRIs, including both the prototype 3D PETRA sequence knee MRI (TE: 70 μs) and the prototype 3D UTE sequence (TE: 70 μs) using a 3 T MRI scanner (MAGNETOM Trio, Siemens, Erlangen, Germany). The study group was classified into three subgroups: (1) normal meniscus on conventional MRI, with no positive meniscus-related physical examination on medical records; (2) meniscal degeneration; and (3) meniscal tear. For quantitative assessment, the mean signal intensities inside user-drawn regions of interest (ROIs) for each image set were drawn on the medical menisci as well as on the bone marrow of medical femoral condyle. For statistical analyses, the Pearson correlation test was used for correlation of the ultrashort TE signal intensity on the UTE and the PETRA sequences, and one-way ANOVA with post-hoc analysis using the Scheffe test was conducted to compare groups. Results The correlation test showed moderate correlation between the mean signal intensity values of the two ultrashort TE sequences (Pearson's coefficient: 0.4817; P < 0.05; 95% CI: 0.3113–0.6221). The normalized mean signal intensity values were lower for patients with meniscal degeneration and tear on both the PETRA and the UTE images. The PETRA images showed the significantly difference between normal and tear groups and between degeneration and normal groups (P < 0.05) whereas the UTE images showed significantly difference between normal and tear groups (P < 0.05). Conclusion Both the PETRA sequence and the UTE sequence can visualize the short T2 tissue. We demonstrated that there was significantly lower signal intensity on the ultrashort TE UTE and the PETRA images of patients with meniscal tear. [ABSTRACT FROM AUTHOR]

Objectives To compare the effects of regional anaesthesia and opioid administration on adrenocortical and glycaemic responses, postoperative pain and recovery quality in dogs undergoing stifle surgery. Study design Prospective, blinded clinical study. Animals Forty-five dogs anaesthetized for tibial tuberosity advancement or tibial plateau levelling osteotomy, and 15 healthy dogs undergoing noninvasive orthopaedic diagnostic procedures. Methods The baseline behaviour of each dog was classified on a descriptive scale before anaesthesia. Dogs were anaesthetized using a standard protocol. Those undergoing surgery were randomly assigned to one of three intraoperative analgesia protocols: 1) peripheral (femoral and sciatic) nerve block (bupivacaine 0.5%; 0.15 mL kg -1 in each nerve; group PNB); 2) spinal anaesthesia (isobaric bupivacaine 0.5%; 0.05 mL kg -1; group SPI); and 3) intravenous fentanyl variable rate infusion and postoperative methadone (0.2 mg kg -1; group FEN). Blood samples were collected for measurement of cortisol and glucose concentrations on arrival (TAR), at induction (TIND), at tracheal extubation (TEXT), and 1 hour post-extubation (TPEX). After extubation, a researcher unaware of the dog's group assignment evaluated pain and recovery quality using the Glasgow Composite Measure Pain Scale (Short- Form) and a descriptive scale, respectively. Results Median recovery quality was significantly worse in group FEN (p < 0.0001) compared with all other groups. Postoperative pain scores were lower in group PNB compared with groups SPI and FEN. Cortisol and glucose concentrations increased significantly from TAR at TEXT and TPEX (p < 0.0001) in group FEN, and were unchanged from TAR in the other groups. Conclusions and clinical relevance Analgesia with a peripheral nerve block or spinal anaesthesia prevented the glycaemic and cortisol responses to surgery, promoted better recovery quality, and decreased postoperative pain scores compared with FEN. In the present study, the regional anaesthesia techniques used were found to be excellent alternatives to fentanyl administration. [ABSTRACT FROM AUTHOR]

The objective of the present study was to establish a protocol for arthroscopic exploration of the bovine stifle joint using craniomedial, caudolateral and caudomedial approaches. An anatomic and arthroscopic study using 26 cadaveric limbs from 13 non-lame adult dairy cows was performed. The craniomedial approach was created between the middle and medial patellar ligaments to investigate the cranial pouches of the stifle joint. The inter-condylar eminence, the proximal aspect of the medial femoral trochlear ridge and the lateral aspect of the lateral femoral condyle were used as starting points for systematic examination of the medial femorotibial, the femoropatellar and the lateral femorotibial joints, respectively. The observed structures were: the suprapatellar pouch, articular surfaces of the patella, femoral trochlear ridges, cruciate ligaments, menisci, and the meniscotibial ligaments. The arthroscopic portal for the caudomedial femorotibial pouch was about 6–8 cm caudal to the medial collateral ligament. The proximal and distal caudolateral femorotibial pouches were explored 3 cm and 1.5 cm caudal to the ipsilateral collateral ligament, respectively. The observed structures were the caudal aspect of femoral condyles, menisci, caudal cruciate ligament, popliteal tendon and the meniscofemoral ligament. Restricted joint size and risk of common peroneal nerve damage were the major limitations for exploration of the caudal femorotibial compartments. The study described the arthroscopic portals and normal intra-articular anatomy of the bovine stifle joint but further investigations are warranted to validate these techniques in clinical cases. [ABSTRACT FROM AUTHOR]

Osteonecrosis of the femoral head is a serious orthopedic problem. Moderate loads with knee loading promote bone formation, but their effects on osteonecrosis have not been investigated. Using a rat model, we examined a hypothesis that knee loading enhances vessel remodeling and bone healing through the modulation of the fate of bone marrow-derived cells. In this study, osteonecrosis was induced by transecting the ligamentum teres followed by a tight ligature around the femoral neck. For knee loading, 5 N loads were laterally applied to the knee at 15 Hz for 5 min/day for 5 weeks. Changes in bone mineral density (BMD) and bone mineral content (BMC) of the femur were measured by pDEXA, and ink infusion was performed to evaluate vessel remodeling. Femoral heads were harvested for histomorphometry, and bone marrow-derived cells were isolated to examine osteoclast development and osteoblast differentiation. The results showed that osteonecrosis significantly induced bone loss, and knee loading stimulated both vessel remodeling and bone healing. The osteonecrosis group exhibited the lowest trabecular BV/TV ( p < 0.001) in the femoral head, and lowest femoral BMD and BMC (both p < 0.01). However, knee loading increased trabecular BV/TV ( p < 0.05) as well as BMD ( p < 0.05) and BMC ( p < 0.01). Osteonecrosis decreased the vessel volume ( p < 0.001), vessel number ( p < 0.001) and VEGF expression ( p < 0.01), and knee loading increased them ( p < 0.001, p < 0.001 and p < 0.01). Osteonecrosis activated osteoclast development, and knee loading reduced its formation, migration, adhesion and the level of “pit” formation ( p < 0.001, p < 0.01, p < 0.001 and p < 0.001). Furthermore, knee loading significantly increased osteoblast differentiation and CFU-F (both p < 0.001). A significantly positive correlation was observed between vessel remodeling and bone healing (both p < 0.01). These results indicate that knee loading could be effective in repair osteonecrosis of the femoral head in a rat model. This effect might be attributed to promoting vessel remodeling, suppressing osteoclast development, and increasing osteoblast and fibroblast differentiation. In summary, the current study suggests that knee loading might potentially be employed as a non-invasive therapy for osteonecrosis of the femoral head. [ABSTRACT FROM AUTHOR]

Background: Locomotion training in a home visit-type preventive-care program has been reported elsewhere. However, continuation of appropriate exercises in a home setting is difficult, and few reports are available on locomotion training in a home setting. The objective of this study was to evaluate the effectiveness of locomotion training over 3 months in a home visit-type preventive-care program for improvement of motor function among elderly people.Methods: Nine hundred and fifty-eight elderly people in Tendo City in Japan who were not currently attending any preventive-care program were invited to participate in the study, and 87 were enrolled. In the pre-intervention and post-intervention assessments, we administered an interview survey (the Kihon Checklist), the timed one-leg standing test with eyes open and the sit-to-stand test, at the participants' homes. The intervention involved one set of training exercises with the participants standing on each leg for 1 min and squatting five or six times. The participants were asked to repeat one set of the exercises three times a day at home. In addition, the participants were regularly asked over the telephone about their performance of the exercises.Results: Physical strength, cognitive function, and total scores of the Kihon Checklist were significantly lower after the intervention than before. In addition, the one-leg standing test time was significantly longer after the intervention (mean ± SD, 23.9 ± 35.4) than before (15.7 ± 20.5), and the sit-to-stand test time was significantly shorter after the intervention (13.0 ± 6.2) than before (14.8 ± 8.3).Conclusion: Locomotion training in a home-visit preventive-care program with telephone support effectively improved the motor function of elderly people who were not currently attending any preventive-care program organized by the long-term care insurance system. [ABSTRACT FROM AUTHOR]

Background: According to guidelines, initiation of pharmacological thromboprophylaxis after total knee or hip replacement is recommended and associated with improved patient outcomes. However, data on how these recommendations are followed in clinical practice are sparse.Methods: All patients undergoing first-time total knee or hip replacement in Denmark 2008-2011 were identified. By cross-referencing Danish nationwide registries, quantitative use of anticoagulants administered orally and subcutaneously post-discharge was assessed by number of claimed prescriptions after surgery. Logistic regression analysis was used to identify factors associated with initiation of prophylaxis.Results: A total of 50,389 patients were included in the study (median age 69, inter-quartile range 62-76). Novel oral anticoagulants were initiated in 14.7 % of the patients and heparins/fondaparinux in 2.3 % of the patients. The use of anticoagulants increased from 6.3 % in 2008 to 30.0 % of patients in 2011. Among patients initiating prophylaxis with a novel oral anticoagulant post-discharge, almost all were treated according to guidelines in terms of treatment duration. Factors significantly associated with an increased chance of prophylaxis among total hip replacement patients were: age (per 10-year increments) and female gender.Conclusions: Use of pharmacological thromboprophylaxis after total knee or hip replacement was low, but increasing during the study period. This is probably due to increased availability of novel oral anticoagulants. Further initiatives to increase guideline recommended use of prophylactic anticoagulation after orthopaedic surgery are warranted. [ABSTRACT FROM AUTHOR]

The diarthrodial, knee joint is a remarkably efficient bearing system; articulating cartilage surfaces provide nearly frictionless performance with minimal wear. The low friction properties of the cartilage surfaces are due in part to the boundary lubricant, superficial zone protein (SZP); also known as lubricin or proteoglycan 4 (PRG4). In previous work, SZP localization and cartilage friction were examined across the femoral condyles. Studies in the literature have also individually investigated the other tissues that comprise the human knee and four-legged animal stifle joint, such as the meniscus or patella. However, comparisons between individual studies are limited due to the variable testing conditions employed. Friction is a system property that is dependent on the opposing articulating surface, entraining speed, and loading. A cross-comparison of the frictional properties and SZP localization across the knee/stifle joint tissues utilizing a common testing configuration is therefore needed. The objective of this investigation was to determine the friction coefficient and SZP localization of the tissues comprising the three compartments of the bovine stifle joint: patella, patellofemoral groove, femoral condyles, meniscus, tibial plateau, and anterior cruciate ligament. The boundary mode coefficient of friction was greater in tissues of the patellofemoral compartment than the lateral and medial tibiofemoral compartments. SZP immunolocalization followed this trend with reduced depth of staining and intensity in the patella and patellofemoral groove compared to the femoral condyles and tibial plateau. These results illustrate the important role of SZP in reducing friction in the tissues and compartments of the knee/stifle joint. [ABSTRACT FROM AUTHOR]

Cranial cruciate ligament (CrCL) deficiency is the leading cause of lameness of the canine stifle. Application of tension in the quadriceps muscle could trigger cranial tibial translation in case of CrCL rupture. We replaced the quadriceps muscle and the gastrocnemius muscle by load cells and turn-buckles. First, eight canine limbs were placed in a servo-hydraulic testing machine, which applied 50% of body weight (BW). In a second phase, the CrCL was transected, and the limbs were tested in a similar manner. In a third phase, a quadriceps pretension of 15% BW was applied and limbs were again tested in a similar manner. Cranial tibial translation was significantly decreased in CrCL deficient stifles (p < 0.05) when quadriceps pretension was applied. These findings indicate that quadriceps pretension could play a role in the stability of a CrCL deficient stifle and should then be considered in rehabilitation programs and conservative treatment of CrCL rupture in dogs. [ABSTRACT FROM AUTHOR]

The primary aim of this study was to assess the potential of force plate analysis for describing the stride cycle of the cat. The secondary aim was to define differences in feline and canine locomotion based on force plate characteristics. Ground reaction forces of 24 healthy cats were measured and compared with ground reaction forces of 24 healthy dogs. Force-time waveforms in cats generated by force plate analysis were consistent, as reflected by intra-class correlation coefficients for peak vertical force, peak propulsive force and peak braking force (0.94-0.95, 0.85-0.89 and 0.89-0.90, respectively). Compared with dogs, cats had a higher peak vertical force during the propulsion phase (cat, 3.89 ± 0.19 N/kg; dog, 3.03 ± 0.16 N/kg), and a higher hindlimb propulsive force (cat, -1.08 ± 0.13 N/kg; dog, (-0.87 ± 0.13 N/kg) and hindlimb impulse (cat, -0.18 ± 0.03 N/kg; dog, -0.14 ± 0.02 N/kg). Force plate analysis is a valuable tool for the assessment of locomotion in cats, because it can be applied in the clinical setting and provides a non-invasive and objective measurement of locomotion characteristics with high repeatability in cats, as well as information about kinetic characteristics. Differences in force-time waveforms between cats and dogs can be explained by the more crouched position of cats during stance and their more compliant gait compared with dogs. Feline waveforms of the medio-lateral ground reaction forces also differ between cats and dogs and this can be explained by differences in paw supination-pronation. [ABSTRACT FROM AUTHOR]

Background: The patterns and magnitudes of axial femorotibial rotation are variable due to the prosthesis design, ligamentous balancing, and surgical procedures. We aimed to investigate the effects of the weight bearing (WB) condition on the kinematics of mobile-bearing total knee arthroplasty (TKA). Methods: We examined 12 patients (19 knees) implanted with a low contact stress (LCS) mobile-bearing TKA system using a two-dimensional to three-dimensional registration technique. The in vivo kinematics of dynamic deep knee flexion under WB and non-WB (NWB) conditions were compared. We evaluated the knee range of motion, femoral axial rotation relative to the tibial component, anteroposterior translation, and kinematic pathway of the femorotibial contact point for both the medial and lateral sides. Results: Under the WB condition, the mean range of motion was 117.8° ± 16.7°. Under the NWB condition, the mean range of motion was 111.0° ± 4.4°. The mean range of axial rotation from full extension to maximum flexion was 3.0° ± 1.5° under the WB condition and 2.2° ± 1.0° under the NWB condition. With regard to the anteroposterior translation, the LCS mobile-bearing TKA system showed the same kinematic patterns under both conditions, except for axial rotation at 0°, 10°, and 110°. From hyperextension to maximum flexion, the kinematic pattern reflected a central pivot under both conditions. Conclusions: In conclusion, this study demonstrated that, in an LCS mobile-bearing TKA system, knee kinematics showed the same patterns under NWB and WB conditions, except for axial rotation at the early phase. Further understanding of knee kinematics could provide us with useful information for future design concepts of TKA implants. [ABSTRACT FROM AUTHOR]

• Mycoplasma bovis induced swelling of joint, increases in synovial fluid, fibrin deposition, and cartilage thinning in calves. • M. bovis induced mRNA and protein expression of inflammatory cytokines in joint tissues. • M. bovis could invade bovine cells in joint tissues. Mycoplasma arthritis that caused by Mycoplasma bovis exhibit severe lameness. This disease is difficult to cure with antibiotics, but the detailed pathological mechanisms have not been fully clarified. In this study, we examined the effects of intra-articular inoculation with M. bovis on immunological responses in calf joints. We inoculated three calves each with M. bovis or phosphate buffer saline (control) into the right stifle joint and dissected them at 15 days postinoculation. Mycoplasma bovis– inoculated calves exhibited swelling of the stifle joint, increases in synovial fluid, fibrin deposition, and cartilage thinning. Intracellular M. bovis was detected in synovial tissues analyzed by immunohistochemistry and transmission electron microscopy. Messenger RNA expressions of interleukin (IL)-1β, IL-6, IL-8, IL-12p40, and IL-17A in synovial fluid cells and synovial tissues from M. bovis– inoculated calves were significantly higher than those from control calves. Protein levels of these cytokines in synovial fluid from M. bovis– inoculated calves were markedly higher than those from control calves. Our study clarified that inoculation with M. bovis into the stifle joint induced the production of inflammatory cytokines by synovial fluid cells and synovial tissues, causing a severe inflammatory response in joints. Additionally, M. bovis could invade cells in synovial tissues, which may have aided it in evading antibiotics and host immune surveillance. [ABSTRACT FROM AUTHOR]

Abstract: Introduction and aim: Tibial plateau fractures (TPFs) are an independent, non-modifiable risk factor for surgical site infections (SSIs). Current antero-lateral approaches to the knee dissect through the anterior tibial angiosome (ATA), which may contribute to a higher rate of SSIs. The aim of this study was to develop an angiosome-sparing antero-lateral approach to allow reduction and fixation of lateral TPFs and to investigate its feasibility in a consecutive cohort. Methods: Twenty cadaveric knees were dissected to define the position of the vessels supplying the ATA from the lateral tibial condyle to the skin perforators. Based on these results, an angiosome-sparing surgical approach to treat lateral TPFs was developed. Fifteen consecutive patients were subsequently treated through this approach. Clinical outcomes included assessment of SSI and Lysholm score. Fracture healing and stability were assessed using the Rasmussen score and radiostereometric analysis (RSA). Results: At the latest follow-up between 1 and 4 years, there was no report of SSI. Nine patients (60%) had good or excellent Lysholm scores. The mean Rasmussen score at final follow-up was 17 (median 18, range 14–18) with 10 patients (66%) graded as excellent. Fracture fragment migration measured using RSA was below 2mm in all cases. Discussion: This study has demonstrated that an angiosome-sparing antero-lateral approach to the lateral tibial plateau is feasible. Adequate stability of these fracture types was achieved by positioning a buttress plate away from the bone and superficial to the regional fascial layer as an ‘internal–external fixator’. Conclusion: The angiosome-sparing approach developed was able to be used in a prospective cohort and the clinical results to date are encouraging. Future clinical studies need to investigate the potential benefits of this surgical approach when compared with the previously described antero-lateral approaches. [Copyright &y& Elsevier]

Abstract: This paper proposes a novel leg orthosis for lower limb rehabilitation robots of the sitting/lying type. It consists of three joint mechanisms: hip, knee and ankle, and two sets of links: thigh and crus. Each driving motor is located close to the associated joint and the rotational axis of each joint mechanism is unique and stable. These features make it outperform the similar mechanisms in stability and dynamic performance. Different forms of eccentric slider-crank mechanisms are applied in the three joint mechanisms, respectively, such that they can be optimized independently. The optimization problems for the hip and knee joint mechanisms, characterized as strongly nonlinear, are developed respectively. Then, a particle swarm optimization algorithm is used to obtain the optimal solutions, which are subsequently validated by comprehensive comparisons. Moreover, the kinematics necessary for motion control and trajectory tracking are investigated, which denote the relationships between the displacements and velocities of the joint mechanisms, lead screws and the end effector. Finally, this paper illustrates the feasibility of the application of the leg orthosis to actual rehabilitation exercises by a simulation example. [Copyright &y& Elsevier]

Background: Cartilage debridement and staged reimplantation are the most common treatments for infected total knee arthroplasty (TKA). Very few studies have focused on the management of primarily non-resurfaced patellae in infected TKA. The purpose of this study was to compare the outcomes of patellar resurfacing and non-resurfacing in two-stage revision of infected TKA. Methods: This study involved a retrospective comparison of the reinfection rate and clinical outcomes of revision TKA patients managed with patellar resurfacing (22 patients, 23 knees) and patients managed without patellar resurfacing (26 patients) at a minimum two-year follow-up. The mean age in the resurfacing group was 69.4 years old, and the mean age in the non-resurfacing group was 67.3 years old. Three scales were used in the assessment: the Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis Index, and the Anterior Knee Pain Scale. Results: Three knees had recurrent infections. All infections occurred in patients who had received patellar resurfacing. There were no significant differences between groups in clinical results and on the Anterior Knee Pain Scale. A lack of patellar resurfacing did not increase recurrence of infection and did not result in significant clinical differences compared to patellar resurfacing. Conclusions: This study indicates that preservation of the original patellar bone is a feasible option for patellar management in revision of septic TKA. Level of evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the likelihood of unicompartmental knee arthroplasty (UKA) in patients with chondrosis in the patellofemoral joint. We evaluated the pain and functional changes in the patellofemoral joint of 62 patients who underwent medial UKA for medial compartmental osteoarthritis with symptoms in the patellofemoral joint. They were analyzed by the patellofemoral score of Lonner at postoperative 3 months, 6 months, 1 year, and 2 years prospectively. Preoperatively, the grade by total score was poor in all 62 cases, but it was improved to 36 excellent (58%), 16 good (26%), and 10 fair (16%), and there were no poor cases at 2 years. The last follow-up showed satisfactory results in pain score, function score, and total score (p < 0.05). Regarding this result, we believe chondrosis in the patellofemoral joint is not a contraindication to UKA, even in patients with patellofemoral joint symptoms. [ABSTRACT FROM AUTHOR]

Background: There is evidence that anterior laxity may be affected by knee extensor open kinetic chain (OKC) exercise with responses being load-dependent. The aim of this study is to evaluate the immediate and short-term changes in passive knee anterior laxity following a single session of OKC knee extensor exercise. Methods: Thirty two participants were randomly allocated to perform either high load (20 sets of 2 repetitions) or low load (2 sets of 20 repetitions) knee extensor OKC exercise with knee anterior laxity assessed before exercise, immediately after exercise and 45 and 90 min after exercise with a KT-2000 arthrometer using a 133 N force. Results: A significant effect of time was observed on knee laxity (pb0.001). However, a significant interaction of time and group was not found (p = 0.54) and so the results presented here are for the combined (low and high load) group mean ± standard deviation knee anterior laxity (mm) in the exercised leg: 7.2±2.2 (baseline), 8.2±2.3 (immediate post exercise, 14% change from baseline), 8.1 ±2.3 (45 min post exercise, 12% change from baseline), and 7.7 ±2.2/0.29 (6.9) (90 min post exercise, 7% change from baseline). Conclusion: OKC knee extensor exercise at high loads and low loads causes an immediate increase in knee laxity that begins to decrease within 90 min. [ABSTRACT FROM AUTHOR]

Background aims. Mesenchymal stromal cells (MSCs) have been extensively studied as a cellular therapeutic for various pathologic conditions. However, there remains a paucity of data regarding regional and systemic safety of MSC transplantations, particularly with multiple deliveries of allogeneic cells. The purpose of this study was to investigate the safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs into the region of the lacrimal gland, the gland of the third eyelid and the knee joint in dogs. Methods. Allogeneic adipose tissue-derived canine MSCs were delivered to the regions of the lacrimal gland and the third eyelid gland as well as in the knee joints of six healthy laboratory beagles as follows: six times with 1-week intervals for delivery to the lacrimal gland and the third eyelid gland regions and three to four times with 1- to 2-week intervals for intra-articular transplantations. Dogs were sequentially evaluated by clinical examination. At the conclusion of the study, dogs were humanely euthanized, and a complete gross and histopathologic examination of all organ systems was performed. Mixed leukocyte reactions were also performed before the first transplantation and after the final transplantation. Results. Clinical and pathologic examinations found no severe consequences after repeated MSC transplantations. Results of mixed leukocyte reactions demonstrated suppression of T-cell proliferation after MSC transplantations. Conclusions. This is the first study to demonstrate regional and systemic safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs in vivo. [ABSTRACT FROM AUTHOR]

Background: Fast-track programs have been developed for different surgical procedures leading to higher patient satisfaction and lower morbidity. This concept has been extended to knee arthroplasty in recent years. The purpose of this narrative review was to discuss the different aspects of fast-track knee arthroplasty. Method: Both authors searched the contemporary literature on minimally invasive knee arthroplasty and review articles on fast-track surgery aiming to summarize recent developments. Results: Length of stay after knee arthroplasty is influenced by preoperative risk factors, anaesthetic and surgical techniques, pain, orthostatic intolerance, cognitive function, sleep disturbances, bleeding and anaemia and finally muscle function and rehabilitation. Conclusions: Fast-track surgery reduces the length of stay and the morbidity after knee arthroplasty. Clinical relevance: Optimisation of pre-, per- and postoperative pathway for knee arthroplasty reduces morbidity after this type of surgery and results in shorter length of stay. [ABSTRACT FROM AUTHOR]

Component malalignment remains a concern in total knee arthroplasty (TKA); therefore, a series of technologies have been developed to improve alignment. The authors conducted a systematic review to compare computer-assisted navigation with conventional instrumentation, and assess the current evidence for patient-matched instrumentation and robot-assisted implantation. An extensive search of the PubMed database for relevant meta-analyses, systematic reviews and original articles was performed, with each study scrutinised by two reviewers. Data on study characteristics and outcomes were extracted from each study and compared. In total 30 studies were included: 10 meta-analyses comparing computer-assisted navigation and conventional instrumentation, 13 studies examining patient-matched instrumentation, and seven investigating robot-assisted implantation. Computer-assisted navigation showed significant and reproducible improvements in mechanical alignment over conventional instrumentation. Patient-matched instrumentation appeared to achieve a high degree of mechanical alignment, although the majority of studies were of poor quality. The data for robot-assisted surgery was less indicative. Computer-assisted navigation improves alignment during TKA over conventional instrumentation. For patient-matched instrumentation and robot-assisted implantation, alignment benefits have not been reliably demonstrated. For all three technologies, clinical benefits cannot currently be assumed, and further studies are required. Although current technologies to improve alignment during TKA appear to result in intra-operative benefits, their clinical impact remains unclear, and surgeons should take this into account when considering their adoption. [ABSTRACT FROM AUTHOR]

• Joint disorders are commonly observed in canine visceral leishmaniasis (CanVL). • In most of the dogs, joint lesions are subclinical. • Joint lesions are usually bilateral and symmetric. • Joint lesions can be erosive, proliferative, or mixed. • Computed tomography is more precise than radiography to identify joint lesions in CanVL. This study aimed to evaluate the joint involvement in dogs with visceral leishmaniasis by means of orthopedic physical examination, radiographic and computed tomographic (CT) findings. Of the 46 evaluated dogs, an overall of 91.3 % presented joint (carpal, tarsal, elbows, and stifle) abnormalities, observed on physical examination, radiography and/or CT. In 67.3 % of the dogs orthopedic examination showed no abnormalities. Among the 31 dogs with normal orthopedic examination, 61.3 % showed radiographic and CT findings suggestive of osteoarthritis, 25.8 % presented normal radiographs with abnormalities evidenced only on CT, while 12.9 % presented normal radiographs and CT imaging. From the 15 dogs with abnormal orthopedic examination, 80 % had abnormal radiographic and CT findings suggestive of osteoarthritis, while 20 % presented normal radiographs with abnormalities evidenced only in their CT. Radiographic and CT findings included evident trabecular pattern, subchondral bone sclerosis, osteolysis, mixed bone lesions (osteolytic–proliferative lesions), soft tissue swelling around the joint (edema), joint space narrowing, bone proliferation, osteophytes, bone cyst and cartilage flap. Based on CT results the most affected joints, among those assessed, were the tarsal (80.9 %), followed by stifle (78.5 %), carpal (64.2 %), and elbows (54.7 %). Except by one dog that presented only one stifle joint compromised, the other three joints presented bilateral abnormalities in all dogs. [ABSTRACT FROM AUTHOR]

Abstract: Background: It has been suggested that platelet-rich plasma (PRP) might enhance bone formation. The aim of this study was to quantify the effect of PRP administered in the early phases of distraction osteogenesis in an ovine femur model. Methods: Twenty sheep aged 4months underwent osteotomy of the femoral diaphysis followed by distraction osteogenesis. The sheep were divided into two groups of 10. One group received three injections of PRP on days 0, 10, and 20 of the procedure (PRP group) and the other received no additional treatment (control group). The results were evaluated by computed tomography (CT) and histology on completion of distraction osteogenesis (day 40). CT evaluation included measurement of the callus and bone density. Femur size was also measured proximally and distally. Histological evaluation was used to quantify osteoblasts, osteoclasts, vascular lumens, and trabecular maturity by zones and to calculate trabecular bone, fibrous tissue, and cartilage ratios. Results: Radiological and histological evaluation of the regenerate bone showed no significant differences between the PRP group and the control group for any of the variables analysed. The only significant difference detected was a wider femur (increased diaphyseal thickness) at the proximal and distal levels in the PRP group. Conclusion: We found no radiological or histological evidence that the administration of PRP in the early phases of distraction osteogenesis enhances bone formation. [Copyright &y& Elsevier]

Purpose: This study used magnetic resonance imaging (MRI) to evaluate in vivo preoperative changes in the length of the patellar tendon (LPT) in patients undergoing total knee arthroplasty (TKA). We sought to answer two questions: first, does the LPT change with flexion? Second, does the LPT show a gender-specific pattern? Methods: Eighty-five knees in 76 consecutive osteoarthritic patients were evaluated. The age range was 56-90 years (mean 70). The study included 62 females and 14 males. MRI was performed at full extension and at 30°, 60°, 90°, and full flexion. Results: There were significantly different patterns between genders ( p < 0.001). The main shortenings occurred earlier, at 30°, in females and later, at 60°, in males. In females, LPT values in full extension were significantly longer than those measured at other flexion angles. In male subjects, significant differences in LPT values were found between full extension versus 90° ( p < 0.001) and full flexion ( p < 0.001), and between 60° versus 90°( p = 0.030) and full flexion ( p = 0.030). Conclusion: These differences might influence the gender-specific complications related to the extensor mechanism after TKA. These data provide useful information for surgeons attempting to achieve a satisfactory balance between joint gaps in the patellar reduced position intraoperatively. [ABSTRACT FROM AUTHOR]

Abstract: The normalization of EMG signals to those recorded during a maximal voluntary contraction provides a valid construct for comparisons of relative muscle activity. However, the length dependence of muscle activation and purported, substantial, muscle translocation and changes in muscle architecture during dynamic movements presents a need for joint angle-dependent normalization processes. The purposes of the present study were to: (1) quantify variations in muscle activity across a large ROM, (2) determine the accuracy with which fitted EMG-joint angle curves accurately characterized these variations, and (3) compare peak (EMG-P) and average (EMG-A) EMG amplitudes obtained during a countermovement leg extension when normalized to both absolute peak and joint angle-specific muscle activity. Fifteen subjects performed a large ROM (110°) isokinetic (30°s−1) leg extension from which EMG-joint angle relationships were derived using polynomial fitting of different complexities. Ten subjects also performed loaded countermovement leg extensions from which EMG signals were normalized using peak muscle activity and EMG-angle curves. EMG amplitude varied significantly over the ROM and the use of EMG-angle curves for signal normalization resulted in significantly greater EMG-P and EMG-A than those normalized using the absolute peak EMG. Higher-order polynomial fitting better matched the filtered EMG amplitudes. Thus, there is a strong rationale for using EMG-angle polynomial fits to normalize EMG signals for large ROM movements. [Copyright &y& Elsevier]

Abstract: Aim of the present study was to identify the different modalities of activation of rectus femoris (RF) during gait at self-selected speed, by a statistical analysis of surface electromyographic signal from a large number (hundreds) of strides per subject. The analysis of ten healthy adults showed that RF is characterized by different activation modalities within different strides of the same walk. RF most recurrent modality (observed in 53±6% of total strides) consists of three activations, at the beginning of gait cycle, around foot-off and in the terminal swing. Further two modalities of RF activation differ from the most recurrent one because of the lack of activity around foot-off (26±6%) or the splitting into two (or three) small activations around stance-to-swing transition (17±2%). Despite the large variability, our statistical analysis allowed to identify two patterns of activation that characterize completely the behavior of rectus femoris during gait. The first pattern, around stance-to-swing transition, can be monophasic, biphasic or triphasic and is necessary to control knee extension and hip flexion from pre-swing to initial swing. The second pattern, from terminal swing to following mid-stance, is likely due to the contribution of low-level RF activity and cross-talk from surrounding vastii. [Copyright &y& Elsevier]

Abstract: Background: In patients with anterior knee pain and patellar instability, a specific training of the quadriceps muscle – especially the vastus medialis – is often recommended, although the practicability is discussed controversially and the proof of a measurable clinical effect is difficult. Therefore, this in vitro study investigates the influence of asymmetric muscle loading on the motion of the human patella. Methods: Seven human knee specimens were tested in a specially developed knee simulator. During simulated weight-bearing knee flexion, the kinematics of tibia, femur and patella were measured using an ultrasound motion capture system. The quadriceps forces were controlled to achieve a constant ankle force over the whole flexion range which is assumed to represent almost physiological loading. Three different force distributions of the quadriceps were tested — a central, equally distributed load as well as mainly lateral and medial loads. Results: A significant influence of different quadriceps force distributions was found for patellar tilt around a proximodistal axis (up to 1.7°) and patellar rotation around an anteroposterior axis (up to 3.8°) with respect to the femur. Interestingly, the patellar mediolateral shift was influenced only marginally (<1.5mm). Conclusions: Specific muscle training might help patients with patellofemoral pain and cartilage damage by a slight modification of the kinematics, but we could show that even highly asymmetric quadriceps loads only led to a small alteration of the mediolateral shift in case of a physiologic anatomy of the trochlear groove. [Copyright &y& Elsevier]

Abstract: Introduction: The ovine stifle joint is an ideal preclinical model to test the ability of double-bundle reconstruction techniques in providing superior joint stability and less osteoarthritis (OA) compared with single-bundle techniques. However, knowledge of the normal ovine ACL and more specifically the load sharing and physical interaction between the two main bundles of the ovine ACL is currently limited. Methods: Six ovine stifle joints were tested using a robotic testing system. Each joint was cyclically loaded to 200N in the anterior tibial direction between 30° and 90° flexion and the force-displacement data were recorded for both the intact ACL, and when the anteromedial (AM, n=3) or the posterolateral bundle (PL, n=3) was transected. Results: The load shared by the AM bundle increased from 30° to 75° of flexion at all loading levels (25–200N); whereas, the load shared by the PL bundle decreased between full extension and mid flexion (60°) and then increased again. The load borne by the AM bundle did not change in response to increasing Anterior Tibial Loads (ATL) at each flexion angle, in contrast to the PL bundle (P=0.004). Physical interaction between bundles was greatest at 60° and under 50N ATL. Conclusion: These data will help create double-bundle ACL reconstructions in sheep which are functionally similar to intact native ACL. In turn, this model can be used to examine the success of anatomically accurate double-bundle reconstructions to prevent the development of OA. Level of evidence: III. [Copyright &y& Elsevier]

Although ovine stifle models are commonly used to study osteoarthritis, meniscal pathology and cruciate ligament injuries and repair, there is little information about the anatomy of the joint or techniques for synovial injections. The objectives of this study were to improve anatomical knowledge of the synovial cavities of the ovine knee and to compare intra-articular injection techniques. Synovial cavities of 24 cadaver hind limbs from 12 adult sheep were investigated by intra-articular resin, positive-contrast arthrography, computed tomography (CT) arthrography and gross anatomical dissection. Communication between femoro-patellar, medial femoro-tibial and lateral femoro-tibial compartments occurred in all cases. The knee joint should be considered as one synovial structure with three communicating compartments. Several unreported features were observed, including a communication between the medial femoro-tibial and lateral femoro-tibial compartments and a latero-caudal recess of the lateral femoro-tibial compartment. No intermeniscal ligament was identified. CT was able to define many anatomical features of the stifle, including the anatomy of the tendinous synovial recess on the lateral aspect of the proximal tibia under the combined tendon of the peroneus tertius, extensor longus digitorum and extensor digiti III proprius. An approach for intra-articular injection into this recess (the subtendinous technique) was assessed and compared with the retropatellar and paraligamentous techniques. All three injection procedures were equally successful, but the subtendinous technique appeared to be most appropriate for synoviocentesis and for injections in therapeutic research protocols with less risk of damaging the articular cartilage. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the capacity of albumin-grafted biomaterials as tissue engineering scaffolds to regenerate cartilaginous components. Porcine knee chondrocytes were seeded and cultivated in porous ternary matrix consisting of polyethylene oxide, chitin, and chitosan with surface albumin. The results revealed that the quantity of albumin did not affect the viability of porcine knee chondrocytes in the constructs. However, a high grafting concentration of albumin favored the adhesion of porcine knee chondrocytes on the scaffolding pore surface. After cultivation over 4 weeks, an increase in the concentration of albumin enhanced the quantities of porcine knee chondrocytes, glycosaminoglycans, and collagen in the constructs. The histological staining of porcine knee chondrocytes showed an active chondrocytic growth in the albumin-grafted constructs. In addition, the safranin-O staining indicated that the surface albumin could stabilize the secretion of glycosaminoglycans. Moreover, the immunochemical staining against type II collagen exhibited a regular production of collagen by phenotypic porcine knee chondrocytes in the constructs. Albumin-grafted polyethylene oxide/chitin/chitosan scaffolds can be a promising biomimetic substrate in neocartilage formation. [Copyright &y& Elsevier]

Abstract: To examine the region specificity within the rectus femoris (RF) for knee extension and hip flexion force directions, three force components around the ankle were measured during intramuscular electrical stimulation applied to six parts of the RF: a proximal and medial part, a proximal and lateral part, a middle and medial part, a middle and lateral part, a distal and medial part, and a distal and lateral part. As a result, the exerted force directions in all of the subjects were variable in all regions, and the proximal region of the RF was the dominant contributor to the hip flexion moment. In addition, the force in the lateral region of the RF, rather than that in the medial region, denoted the lateral direction. These results suggest that divergent regions of muscle fibers within the RF are responsible for different functions in determining the force direction. [Copyright &y& Elsevier]

To evaluate the peri-operative analgesic efficacy of intra-articular bupivacaine administered before or after stifle arthrotomy. Prospective, randomized, blind, placebo-controlled experimental trial. Thirty-nine healthy goats. The goats were allocated randomly to one of three intra-articular treatment groups: group PRE (bupivacaine before and saline after surgery), group POST (saline before and bupivacaine after surgery) and group CON (saline before and after surgery). Anaesthesia was maintained with a constant end-tidal sevoflurane of 2.5%. Intra-operatively heart rate (HR), respiratory rate and mean arterial blood pressure (MAP) after critical surgical events (CSE) were recorded and compared with pre-incision values. Propofol requirements to maintain surgical anaesthesia were recorded. Flunixin was administered for 5 days. Post-operative pain assessment at 20 minutes, 2 hours, 4 hours after recovery and on day 2 and 3 included a multidimensional pain score (MPS), a lameness score and mechanical nociceptive threshold (MNT) testing. Rescue analgesia consisted of systemic opioids. Data were analysed using Kruskal-Wallis, Mann-Whitney, Friedman or chi-square tests as appropriate. Intra-operatively, group PRE had lower HR and MAP at several CSEs than groups POST/CON and required less propofol [0 mg kg (0-0 mg kg)] than group POST/CON [0.3 mg kg (0-0.6 mg kg)]. Post-operatively, group POST had significantly higher peri-articular MNTs than groups PRE and CON up to 4 hours after recovery. No treatment effect was detected for MPS, lameness scores and rescue analgesic consumption at any time point. Pre-operative intra-articular bupivacaine provided notable intra-operative analgesia in goats undergoing stifle arthrotomy but did not reduce post-operative pain. Post-operative intra-articular bupivacaine provided a short lasting reduction of peri-articular hyperalgesia without affecting the requirements for systemic analgesia. Multimodal perioperative pain therapy is recommended to provide adequate analgesia for stifle arthrotomy in goats. [ABSTRACT FROM AUTHOR]

Abstract: The extent to which therapeutic, exercise or robotic devices can maximize gait function is a major unresolved issue in neurorehabilitation. Several factors may influence gait outcomes such as similarity of the task to overground walking, degree of coordination within and across limbs, and cycle-to-cycle variability in each device. Our objective was to compare lower extremity kinematics, coordination and variability during four locomotor tasks: overground walking, treadmill walking, elliptical training and stationary cycling in 10 non-disabled adults (6 male; mean age 22.7±2.9 yrs, range 20–29). All first performed four overground walking trials at self-selected speed with mean temporal–spatial data used to pace the other conditions. Joint positions, excursions, and the Gait Deviation Index (GDI) were compared across conditions to evaluate kinematic similarity. Time-series data were correlated within and across limbs to evaluate intralimb and interlimb coordination, respectively. Variability in cadence was quantified to assess how constrained the locomotor rhythm was compared to overground walking. Treadmill walking most closely resembled overground with GDI values nearly overlapping, reinforcing its appropriateness for gait training. Cycling showed the largest GDI difference from overground, with elliptical closer but still a significant distance from all three. Cycling showed greater hip reciprocation Cycling and elliptical showed stronger intralimb synergism at the hip and knee than the other two. Based on kinematics, results suggest that elliptical training may have greater transfer to overground walking than cycling and cycling may be more useful for enhancing reciprocal coordination. Further evaluation of these devices in neurological gait disorders is needed. [Copyright &y& Elsevier]

Abstract: Many patients respond positively to treatments for crouch gait, yet surgical outcomes are inconsistent and unpredictable. In this study, we developed a multivariable regression model to determine if biomechanical variables and other subject characteristics measured during a physical exam and gait analysis can predict which subjects with crouch gait will demonstrate improved knee kinematics on a follow-up gait analysis. We formulated the model and tested its performance by retrospectively analyzing 353 limbs of subjects who walked with crouch gait. The regression model was able to predict which subjects would demonstrate ‘Improved’ and ‘Unimproved’ knee kinematics with over 70% accuracy, and was able to explain approximately 49% of the variance in subjects’ change in knee flexion between gait analyses. We found that improvement in stance phase knee flexion was positively associated with three variables that were drawn from knowledge about the biomechanical contributors to crouch gait: (i) adequate hamstrings lengths and velocities, possibly achieved via hamstrings lengthening surgery, (ii) normal tibial torsion, possibly achieved via tibial derotation osteotomy, and (iii) sufficient muscle strength. [Copyright &y& Elsevier]

Abstract: Functional tissue engineering (FTE) approaches have shown promise in healing an injured anterior cruciate ligament (ACL) of the knee. Nevertheless, additional mechanical augmentation is needed to maintain joint stability and appropriate loading of the joint while the ACL heals. The objective of this study was to quantitatively evaluate how mechanical augmentation using sutures restores the joint kinematics as well as the distribution of loading among the ACL, medial collateral ligament, and medial meniscus (MM) in response to externally applied loads. Eight goat stifle joints were tested on a robotic/universal force–moment sensor testing system under two loading conditions: (1) a 67N anterior tibial load (ATL) and (2) a 67N ATL with 100N axial compression. For each joint, four experimental conditions were tested at 30°, 60°, and 90° of flexion: the (1) intact and (2) ACL-deficient joint, as well as following (3) suture repair of the transected ACL, and (4) augmentation using sutures passed from the femur to the tibia. Under the 67N ATL, suture augmentation could restore the anterior tibial translation (ATT) to within 3mm of the intact joint (p>0.05), representing a 54–76% improvement over suture repair (p<0.05). With the additional axial compression, the ATT and in-situ forces of the sutures following suture augmentation remained 2–3 times closer to normal (p<0.05). Also, the in-situ forces in the MM were 58–73% lower (p<0.05). Thus, suture augmentation may be helpful in combination with FTE approaches for ACL healing by providing the needed initial joint stability while lowering the loads on the MM. [Copyright &y& Elsevier]

Abstract: It has been proposed that small quantities of microbial material within synovial joints may act as a trigger for development of synovitis. We have previously identified an association between intra-articular bacteria and development of inflammatory stifle arthritis and cranial cruciate ligament rupture (CCLR) in dogs, and now wished to quantify bacterial load and markers of synovitis in dogs with and without stifle arthritis and CCLR. Joint tissues were collected from dogs with CCLR (n =51) and healthy dogs with normal stifles (n =9). Arthritis was assessed radiographically in CCLR dogs. Bacterial load was assessed using qPCR and broad-ranging 16S rRNA primers. qRT-PCR was used to estimate expression of the T lymphocyte antigen receptor (TCR Vβ), CD3ɛ, tartrate-resistant acid phosphatase (TRAP), IL-4, IL-17, and TNF-α genes. Severity of synovitis was assessed histologically. Bacterial load was increased in arthritic stifles, when compared with healthy stifles. Histologic synovitis in arthritic stifles was mononuclear and was significantly correlated with bacterial load (1 of 2 primer sets) (S R =0.49, p <0.001). In arthritic stifles, expression of TRAP in synovium was increased relative to healthy stifles. Expression of pro-inflammatory genes was not correlated with bacterial load, histologic inflammation, or radiographic arthritis. Translocation of bacterial material to the canine stifle is related to the presence of joint inflammation. The lack of a strong positive correlation suggests that bacterial load is unlikely to be a primary pro-inflammatory factor. However, dysregulation of immune responses within synovial tissues may be dependent upon an environmental microbial trigger. [Copyright &y& Elsevier]

Abstract: The ovine stifle has been increasingly used as a large animal model for the human knee. Still, comparative anatomical measurements of the knee in sheep and humans are missing. Thus, the purpose of this study was to describe and measure the osseous anatomy of the ovine stifle in comparison to the human knee. Twenty-four stifles of skeletal-mature merino-sheep and 24 human cadaver knees were obtained and distances between selected anatomical structures of the distal femur, the proximal tibia, and the patella were measured digitally and documented. Based on these, intercondylar ratio, tibial aspect ratio, patella aspect ratio and the cortical index were calculated. Regarding epicondylar width, lateral condylar width, medial condylar width and the tibial dimensions, the ovine stifle can be considered as a human knee scaled down by one third. However, sheep have a smaller trochlear width and a narrower femoral intercondylar notch than humans resulting in lower relative values for intercondylar width and intercondylar height. The distal femur''s cortical index is the same in both species. In contrast, sheep have a massive bone stock below their tibial plateau and a proximal tibial shaft with remarkably thick cortical bone. The ovine stifle can be regarded as a useful model for the human knee. However, future studies should consider the differences in the femoral intercondylar notch width, the patellofemoral joint''s biomechanics and the proximal tibia''s cortical bone stock. [Copyright &y& Elsevier]

Abstract: Primary fibroblast cultures of canine cranial (CCL) and caudal (CaCL) cruciate ligaments were stimulated with different apoptosis inducers with or without preincubation of the pancaspase inhibitor zVAD.fmk. In contrast to CaCL fibroblasts, fibroblasts from CCL were significantly more susceptible to apoptosis inducers of the intrinsic pathway like doxorubicin, cisplatin and nitric oxide (NO)-donors and to Fas ligand (FasL), an apoptosis inducer of the death receptor pathway. Apoptotic response to staurosporine and the peroxynitrite donor GEA was similar in both ligament fibroblasts. Stimulation with dexamethasone or TNFα could not induce apoptosis in CCL and CaCL fibroblasts, in spite of present TNFR1 and TNFR2 receptors. zVAD.fmk was able to prevent apoptosis in up to 66% of CCL cells when treated with FasL, cisplatin or doxorubicin but it had no effect on NO or peroxynitrite induced apoptosis. In conclusion, differential susceptibility to apoptotic triggers like FasL or NO between cranial and caudal cruciate ligament fibroblasts in vitro may be a reflection of the different susceptibilities to degenerative rupture of the ligament. These findings indicate that a general caspase inhibition does not completely protect canine CCL cells from apoptosis. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to establish the modulation pattern of the soleus H-reflex and excitability changes of interneurones mediating presynaptic inhibition from tibialis anterior to soleus Ia afferents when the right foot approached and withdrew from a step in standing humans. The task was conducted at 40 beats per minute, and this tempo corresponded to the rhythm of a half full movement cycle. Each subject was instructed not to load and not to move forward. Soleus H-reflexes were elicited once in every full movement cycle that lasted approximately 3s. The ipsilateral knee joint angle and activity of leg muscles were recorded through a twin-axis goniometer and surface EMG, respectively. In all subjects, the soleus H-reflex was modulated in a phase-dependent pattern. The H-reflex was significantly depressed during the approach phase of the motor task and when the foot was on the step, and facilitated during the withdrawal phase and when the foot was on the ground. The soleus H-reflex conditioned by common peroneal nerve stimulation at tibialis anterior motor threshold at a long conditioning test interval was increased during the withdrawal phase or while the foot was on the ground suggesting that presynaptic inhibition was decreased. In most subjects, knee extensor activity was small, while ankle flexors and extensors were active in a reciprocal pattern. This study provides evidence that the soleus H-reflex is modulated in a phasic pattern during one-legged foot reaching and withdrawal by changes occurring at a premotoneuronal level. [ABSTRACT FROM AUTHOR]

Abstract: The aims of this study are to compare quantitatively the gait strategy of the right and left hemiplegic children with Cerebral Palsy (CP) using gait analysis. The gait strategy of 28 right hemiparetic CP (RHG) and 23 left hemiparetic CP (LHG) was compared using gait analysis (spatio-temporal and kinematic parameters) and considering the hemiplegic classification based on four gait strategies. Our results demonstrated that velocity was a significant parameter to differentiate RHG and LHG: all hemiplegic types revealed in fact that RHG walked with higher velocity than LHG. The ankle strategy displayed an increased number of differences between RHG and LHG from hemiplegia of Type I to Type III. In all the comparison, the LHG showed the less physiological gait pattern. As for knee kinematics, differences between right and left hemiplegic gait pattern were evidenced only in children with hemiplegia Type II: the LHG walked with a more flexed knee at initial contact, marked hyperextension in midstance and reduced knee flexion ability in the swing phase. The hip strategy was quite normal in both groups in hemiplegia Type I. In the other two types, LHG showed a limited extension ability in midstance in comparison to RHG. In conclusion, our data revealed that RHG and LHG were in general characterised by different gait patterns, evidencing a general a progression of involvement in the different types of hemiplegia; in particular in all the hemiplegic types the LHG patients revealed a more severe involvement than the RHG individuals and the differences were more evident at the distal joints, especially at the ankle joint. [ABSTRACT FROM AUTHOR]

Abstract: In-vivo quantification of loads in the constitutive structures of the osteoarthritic knee can provide clinical insight, particularly when planning a surgery like the opening-wedge high tibial osteotomy (HTO). A computational knee model was created to estimate internal kinetics during walking gait. An optimization approach partitioned loads between the muscles, ligaments, medial and lateral contact surfaces of the tibial–femoral joint. Three kinetic measures were examined in 30 HTO patients: external knee adduction moment (EKAM), medial compartment load (ML) and the medial-to-lateral compartment loads ratio (MLR). Three time points were compared: immediately pre-HTO, 6 and 12 months post-HTO. Three hypotheses were tested: (1) HTO reduces an EKAM, an ML and an MLR, (2) these measures are not significantly different at 6 and 12 months post-HTO, and (3) the change in the impulse of EKAM due to a HTO is well-correlated with the impulse of an MLR. The three hypotheses were confirmed. First peak of an EKAM during stance phase was reduced significantly by 1.70% BW-ht. ML and MLR at the same instance were reduced significantly by 0.56%BW and 1.0, respectively. These measures were not significantly different between 6 and 12 months post-HTO. Changes in impulse of an EKAM and an MLR were moderately well-correlated between the pre-HTO and 6 months post-HTO time points (R 2=0.5485). Therefore, the external measure EKAM-impulse is a good proxy of the internal kinetic measure of an MLR-impulse, explaining about 55% of the variance in the change due to a HTO intervention. [ABSTRACT FROM AUTHOR]

The article describes a case of lipoma arborescence of the knee in a 13-year-old boy who experienced pain, swelling and restricted movement around his left knee joint in November 2004. The medical history of the boy revealed a trivial trauma and a few episodes of the knee locking. Details of the results of the clinical and physical examinations conducted on the patient are provided.