Static Weight Bearing Research Articles

The efficacy of vitamin E in preventing arthrofibrosis after joint replacement.

Arthrofibrosis is a joint disorder characterized by excessive scar formation in the joint tissues. Vitamin E is an antioxidant with potential anti-fibroblastic effect. The aim of this study was to establish an arthrofibrosis rat model after joint replacement and assess the effects of vitamin E supplementation on joint fibrosis. We simulated knee replacement in 16 male Sprague-Dawley rats. We immobilized the surgical leg with a suture in full flexion. The control groups were killed at 2 and 12 weeks (n = 5 per group), and the test group was supplemented daily with vitamin E (0.2 mg/mL) in their drinking water for 12 weeks (n = 6). We performed histological staining to investigate the presence and severity of arthrofibrosis. Immunofluorescent staining and α2-macroglobulin (α2M) enzyme-linked immunosorbent assay (ELISA) were used to assess local and systemic inflammation. Static weight bearing (total internal reflection) and range of motion (ROM) were collected for functional assessment. The ROM and weight-bearing symmetry decreased after the procedure and recovered slowly with still significant deficit at the end of the study for both groups. Histological analysis confirmed fibrosis in both lateral and posterior periarticular tissue. Vitamin E supplementation showed a moderate anti-inflammatory effect on the local and systemic levels. The vitamin E group exhibited significant improvement in ROM and weight-bearing symmetry at day 84 compared to the control group. This model is viable for simulating arthrofibrosis after joint replacement. Vitamin E may benefit postsurgical arthrofibrosis, and further studies are needed for dosing requirements.

The BMP7-Derived Peptide p[63-82] Reduces Cartilage Degeneration in the Rat ACLT-pMMx Model for Posttraumatic Osteoarthritis.

Osteoarthritis (OA) is characterized by articular cartilage erosion, pathological subchondral bone changes, and signs of synovial inflammation and pain. We previously identified p[63-82], a bone morphogenetic protein 7 (BMP7)-derived bioactive peptide that attenuates structural cartilage degeneration in the rat medial meniscal tear-model for posttraumatic OA. This study aimed to evaluate the cartilage erosion-attenuating activity of p[63-82] in a different preclinical model for OA (anterior cruciate ligament transection-partial medial meniscectomy [anterior cruciate ligament transection (ACLT)-pMMx]). The disease-modifying action of the p[63-82] was followed-up in this model for 5 and 10 weeks. Skeletally mature male Lewis rats underwent ACLT-pMMx surgery. Rats received weekly intra-articular injections with either saline or 500 ng p[63-82]. Five and 10 weeks postsurgery, rats were sacrificed, and subchondral bone characteristics were determined using microcomputed tomography (µCT). Histopathological evaluation of cartilage degradation and Osteoarthritis Research Society International (OARSI)-scoring was performed following Safranin-O/Fast Green staining. Pain-related behavior was measured by incapacitance testing and footprint analysis. Histopathological evaluation at 5 and 10 weeks postsurgery showed reduced cartilage degeneration and a significantly reduced OARSI score, whereas no significant changes in subchondral bone characteristics were found in the p[63-82]-treated rats compared to the saline-treated rats. ACLT-pMMx-induced imbalance of static weightbearing capacity in the p[63-82] group was significantly improved compared to the saline-treated rats at weeks 5 postsurgery. Footprint analysis scores in the p[63-82]-treated rats demonstrated improvement at week 10 postsurgery. Weekly intra-articular injections of p[63-82] in the rat ACLT-pMMx posttraumatic OA model resulted in reduced degenerative cartilage changes and induced functional improvement in static weightbearing capacity during follow-up.

Relationship between ankle–foot-complex mobility during static loading and frontal moment impulses of knee and hip joints during the stance phase

BackgroundAnkle–foot-complex mobility impairments, which can be assessed by the difference between the sitting and standing positions, are related to an increase in the load on the knee and hip joints during the stance phase of the gait. Research questionWhat is the relationship between the ankle–foot-complex mobility during static weight bearing and the mechanical stresses on the knee and hip joints throughout the stance phase? MethodsAnkle–foot-complex mobility and gait data were collected from 26 healthy adults. The complex mobility was established by comparing the foot indices, measured using a three-dimensional foot scanner, in sitting and standing positions. The gait data were acquired using eight cameras (recording at 100 Hz) and three force plates (recording at 1000 Hz). Stance phase data were collected via ground reaction forces. The stance phase was dissected into shock absorption and propulsion phases, during which the external knee and hip adduction moment impulses (KAMi, HAMi) were recorded. The correlation between the ankle–foot-complex mobility during static weight bearing and KAMi and HAMi during the stance phase was examined using Pearson's product–moment correlation coefficients. ResultsThis study revealed that KAMi correlated with medial malleolus mobility (r = −0.44) throughout the stance phase. Furthermore, in the propulsive phase, KAMi correlated with calcaneus (r = 0.51) and navicular (r = −0.50) mobilities, whereas HAMi correlated with calcaneus mobility (r = −0.40). SignificanceThe study provides insights into the relationship between the static mobility of the ankle–foot complex in healthy individuals and mechanical stress during the stance phase. Calcaneus and navicular mobilities were related to efficient push-off in the propulsive phase. Medial malleolus mobility was related to the control of the lateral tilt of the lower limb and ankle dorsiflexion motion throughout the stance phase.

High frequency alternating current neurostimulation decreases nocifensive behavior in a disc herniation model of lumbar radiculopathy

BackgroundThe purpose of this study was to evaluate if kilohertz frequency alternating current (KHFAC) stimulation of peripheral nerve could serve as a treatment for lumbar radiculopathy. Prior work shows that KHFAC stimulation can treat sciatica resulting from chronic sciatic nerve constriction. Here, we evaluate if KHFAC stimulation is also beneficial in a more physiologic model of low back pain which mimics nucleus pulposus (NP) impingement of a lumbar dorsal root ganglion (DRG).MethodsTo mimic a lumbar radiculopathy, autologous tail NP was harvested and placed upon the right L5 nerve root and DRG. During the same surgery, a cuff electrode was implanted around the sciatic nerve with wires routed to a headcap for delivery of KHFAC stimulation. Male Lewis rats (3 mo., n = 18) were separated into 3 groups: NP injury + KHFAC stimulation (n = 7), NP injury + sham cuff (n = 6), and sham injury + sham cuff (n = 5). Prior to surgery and for 2 weeks following surgery, animal tactile sensitivity, gait, and static weight bearing were evaluated.ResultsKHFAC stimulation of the sciatic nerve decreased behavioral evidence of pain and disability. Without KHFAC stimulation, injured animals had heightened tactile sensitivity compared to baseline (p < 0.05), with tactile allodynia reversed during KHFAC stimulation (p < 0.01). Midfoot flexion during locomotion was decreased after injury but improved with KHFAC stimulation (p < 0.05). Animals also placed more weight on their injured limb when KHFAC stimulation was applied (p < 0.05). Electrophysiology measurements at end point showed decreased, but not blocked, compound nerve action potentials with KHFAC stimulation (p < 0.05).ConclusionsKHFAC stimulation decreases hypersensitivity but does not cause additional gait compensations. This supports the idea that KHFAC stimulation applied to a peripheral nerve may be able to treat chronic pain resulting from sciatic nerve root inflammation.

Macromolecular Dexamethasone Prodrug Ameliorates Neuroinflammation and Prevents Bone Loss Associated with Traumatic Brain Injury (S28.001)

<h3>Objective:</h3> We hypothesized that systemically administered N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based dexamethasone (Dex) prodrugs (P-Dex) will target the brain trauma injury sites, substantially enhance the Glucocorticoid therapy efficacy, and improve its systemic safety. <h3>Background:</h3> Traumatic brain injury is (TBI) a leading cause of morbidity and mortality in children and adults. The pathology of TBI is heterogeneous, resulting from both primary and secondary injury mechanisms, the latter being attributed to the inflammatory response. Use of conventional glucocorticoid formulations (free DEX) leads to limited distribution to the brain, pulsatile brain tissue concentration and systemic side effects, with controversial benefit in being neuroprotective. Dex and prodrugs (P-Dex) passively target inflammation through the leaky vasculature associated with the underlying pathologies. Given the compromised blood brain barrier (BBB) and brain inflammation in the secondary injury phase of the TBI patients, we hypothesized that the systemically administrated P-Dex will passively target the brain trauma injury sites and reduce inflammation with least systemic side effects. <h3>Design/Methods:</h3> 30 mice were randomly assigned into 2 groups: TBI (Cortical impact model) and healthy mice. All mice received Saline, P-Dex or free Dex. They underwent optical imaging, Neurological severity score, Static weight bearing, Immunohistochemistry and Mico-CT analysis. <h3>Results:</h3> We found that P-Dex passively targeted the traumatic brain tissue and had sustained accumulation at the inflamed tissue for over 14 days. Histological evidence demonstrates the P-Dex’s therapeutic effect on the amelioration of neuroinflammation and prevention of neurodegeneration. Behaviorally, the P-Dex treated animals showed better recovery of the imbalance and better neurological severity score post-TBI. Higher bone mineral density and better bone microarchitecture was found in the skeletal tissues from P-Dex treated animals, comparing to the free Dex, and Saline treated animals, confirming the P-Dex bone protection effect. <h3>Conclusions:</h3> P-Dex can be a potential therapy targeting neuro-inflammation and preserving the neurons from death, avoiding bone loss post-TBI. <b>Disclosure:</b> Dr. Wei has nothing to disclose. Dr. Zhao has nothing to disclose. Jia Zhenshan has nothing to disclose. Zhao Zhifeng has nothing to disclose. Dr. Chen has nothing to disclose. Miss Sun has nothing to disclose. Dr. Kelso has received personal compensation for serving as an employee of Agilent Technologies. Dr. Kelso has stock in Agilent Technologies. Dr. Rathore has nothing to disclose. Dr. Wang has nothing to disclose.

Limited roles of Piezo mechanosensing channels in articular cartilage development and osteoarthritis progression

To investigate the role of Piezo1 and Piezo2 in surgically induced osteoarthritis (OA) in mice. Male conditional knockout (cKO) mice missing Piezo1 and Piezo2 in the joint using Gdf5-Cre transgenic mice were induced with post-traumatic OAby destabilization of the medial meniscus (DMM) of the right knee joint at 12 weeks of age. The severity of OA was histologically assessed at 24 weeks of age. OA-associated pain was evaluated by static weight bearing analysis. Additionally, articular chondrocytes isolated from cKO mice were exposed to fluid flow shear stress (FFSS) to evaluate the expression of OA-associated genes. Mice with conditional deletion of Piezo1 and Piezo2 showed normal joint development with no overt histological changes in the knee joint at 12 weeks and 24 weeks. DMM surgery induced moderate to severe OA in both control and cKO mice (median OARSI score: control, 4.67; cKO, 4.23, P=0.3082), although a few cKO mice showed milder OA. Pain assessment by static weight-bearing analysis suggested Piezo ablation in the joint has no beneficial effects on pain. FFSS increased the expression of OA-related genes both in control and cKO mice to similar extents. Piezo1 and Piezo2 are not essential for normal joint development. Genetic ablation of Piezo channels did not confer evident protective effects on OA progression in mice. In vitro data suggests that different mechanotransducers other than Piezo channels mediate FFSS in mechanical stress-induced gene expression.

Effectiveness of losartan on infrapatellar fat pad/synovial fibrosis and pain behavior in the monoiodoacetate-induced rat model of osteoarthritis pain

Infrapatellar fat pad (IFP)/ synovial fibrosis is closely associated with the clinical symptoms of joint pain and stiffness, which contribute to locomotor restriction in osteoarthritis (OA) patients. Hence, this study was designed to gain insight on whether losartan, a selective angiotensin II type 1 receptor (AT1R) antagonist, has therapeutic benefit to reverse IFP/synovial fibrosis and secondarily to attenuate pain behavior. In male Wistar rats with monoiodoacetic acid (MIA)-induced IFP/synovial fibrosis, a possible role for increased AT1R expression in the pathogenesis of IFP/synovial fibrosis was assessed over an 8-week period. Pain behavior comprised static weight bearing and von Frey paw withdrawal thresholds (PWTs), which were assessed once or twice weekly, respectively. Groups of MIA-rats received oral losartan (30-mg/kg; n = 8 or 100-mg/kg; n = 9) or vehicle (n = 9) for 28-days according to a prevention protocol. Animals were euthanized on day 28 and various tissues (IFP/synovium, cartilage and lumbar dorsal root ganglia (DRGs)) were collected for histological, immunohistochemical and western blot analyses. Administration of once-daily losartan for 28-days dose-dependently attenuated the development of static weight bearing. This was accompanied by reduced IFP/synovial fibrosis and suppression of TGF-β1 expression. Chronic treatment of MIA-rats with losartan had an anti-fibrotic effect and it attenuated pain behavior in this animal model.

Modelling osteoarthritis in mice via surgical destabilization of the medial meniscus with or without a stereomicroscope.

AimsTo evaluate inducing osteoarthritis (OA) by surgical destabilization of the medial meniscus (DMM) in mice with and without a stereomicroscope.MethodsBased on sample size calculation, 70 male C57BL/6 mice were randomly assigned to three surgery groups: DMM aided by a stereomicroscope; DMM by naked eye; or sham surgery. The group information was blinded to researchers. Mice underwent static weightbearing, von Frey test, and gait analysis at two-week intervals from eight to 16 weeks after surgery. Histological grade of OA was determined with the Osteoarthritis Research Society International (OARSI) scoring system.ResultsSurgical DMM with or without stereomicroscope led to decrease in the mean of weightbearing percentages (-20.64% vs -21.44%, p = 0.792) and paw withdrawal response thresholds (-21.35% vs -24.65%, p = 0.327) of the hind limbs. However, the coefficient of variation (CV) of weight-bearing percentages and paw withdrawal response thresholds in naked-eye group were significantly greater than that in the microscope group (19.82% vs 6.94%, p < 0.001; 21.85% vs 9.86%, p < 0.001). The gait analysis showed a similar pattern. Cartilage degeneration was observed in both DMM-surgery groups, evidenced by increased OARSI scores (summed score: 11.23 vs 11.43, p = 0.842), but the microscope group showed less variation in OARSI score than the naked-eye group (CV: 21.03% vs 32.44%; p = 0.032).ConclusionAlthough surgical DMM aided by stereomicroscope is technically difficult, it produces a relatively more homogeneous OA model in terms of the discrete degree of pain behaviours and histopathological grading when compared with surgical DMM without stereomicroscope.Cite this article: Bone Joint Res 2022;11(8):518–527.

Maresin 2 is an analgesic specialized pro-resolution lipid mediator in mice by inhibiting neutrophil and monocyte recruitment, nociceptor neuron TRPV1 and TRPA1 activation, and CGRP release

Maresin-2 (MaR2) is a specialized pro-resolution lipid mediator (SPM) that reduces neutrophil recruitment in zymosan peritonitis. Here, we investigated the analgesic effect of MaR2 and its mechanisms in different mouse models of pain. For that, we used the lipopolysaccharide (LPS)-induced mechanical hyperalgesia (electronic version of the von Frey filaments), thermal hyperalgesia (hot plate test) and weight distribution (static weight bearing), as well as the spontaneous pain models induced by capsaicin (TRPV1 agonist) or AITC (TRPA1 agonist). Immune cell recruitment was determined by immunofluorescence and flow cytometry while changes in the pro-inflammatory mediator landscape were determined using a proteome profiler kit and ELISA after LPS injection. MaR2 treatment was also performed in cultured DRG neurons stimulated with capsaicin or AITC in the presence or absence of LPS. The effect of MaR2 on TRVP1- and TRPA1-dependent CGRP release by cultured DRG neurons was determined by EIA. MaR2 inhibited LPS-induced inflammatory pain and changes in the cytokine landscape as per cytokine array assay. MaR2 also inhibited TRPV1 and TRPA1 activation as observed by a reduction in calcium influx in cultured DRG neurons, and the number of flinches and time spent licking the paw induced by capsaicin or AITC. In corroboration, MaR2 reduced capsaicin- and AITC-induced CGRP release by cultured DRG neurons and immune cell recruitment to the paw skin close the CGRP+ fibers. In conclusion, we show that MaR2 is an analgesic SPM that acts by targeting leukocyte recruitment, nociceptor TRPV1 and TRPA1 activation, and CGRP release in mice.

Effect of Femoral Head and Neck Osteotomy on Canines' Functional Pelvic Position and Locomotion.

Simple SummaryRemoval of the femoral head and neck is a common surgical procedure used to provide pain relief in dogs with severe hip-related diseases. We investigated the chronic effect of the surgery on movement and position of the pelvis. Dog owners completed a questionnaire regarding their dog’s rehabilitation. An orthopaedic examination, anatomical measurements, and pressure-sensitive walkway analysis were conducted on all of the dogs. According to the questionnaire results, nine of ten dogs had returned to normal physical activity level, and the owners of the dogs considered the outcome of the surgery to be good or excellent. However, the dogs had less muscle mass, less hip extension, and less weight bearing on the operated limb when standing. The trot of the dogs was unaffected; no differences emerged between the operated and non-operated limb regarding length of stance or swing time of step or weight bearing during step. Pelvic position did not change in a specific way; i.e., the pelvis did not tilt towards or away from the surgically treated limb.The long-term effect of femoral head and neck osteotomy (FHO) on the locomotory system of dogs was evaluated. The study comprised an owner questionnaire and an orthopaedic examination, anatomical measurements, and pressure-sensitive walkway analysis for dogs. Linear mixed effect models were used for statistical analysis. Ten dogs with a median of 2.5 years since their unilateral FHO were included. According to the questionnaire results, nine dogs had returned to a normal physical activity level. Muscle atrophy (p = 0.005), less extension in the coxofemoral joint (p = 0.003), and less static weight bearing on the FHO limb (p = 0.003) were observed. No consistent pattern regarding tilt or position of the pelvis was noted when measuring height of the tuber ischii (p = 0.39). Five of the dogs tilted away from, and five towards the FHO side when measured from the tuber sacrale with a Myrin goniometer. No differences regarding stance time, swing time, or peak pressure between the FHO and non-FHO limb were seen in trot (p = 0.70, p = 0.26, and p = 0.91, respectively). Over the long term, the FHO limb has muscle atrophy, decreased coxofemoral extension, and decreased static weight bearing. However, this does not seem to affect the trot of the dogs. Dog owners considered the outcome of surgery to be good or excellent.

Estrogenic impregnation alters pain expression: analysis through functional neuropeptidomics in a surgical rat model of osteoarthritis.

Several observational studies suggest that estrogens could bias pain perception. To evaluate the influence of estrogenic impregnation on pain expression, a prospective, randomized, controlled, blinded study was conducted in a Sprague-Dawley rat model of surgically induced osteoarthritis (OA). Female rats were ovariectomized and pre-emptive 17β-estradiol (0.025mg, 90-day release time) or placebo pellets were installed subcutaneously during the OVX procedures. Thirty-five days after, OA was surgically induced on both 17β-estradiol (OA-E) and placebo (OA-P) groups. Mechanical hypersensitivity was assessed by static weight-bearing (SWB) and paw withdrawal threshold (PWT) tests. Mass spectrometry coupled with high-performance liquid chromatography (HPLC-MS) was performed to quantify the spinal pronociceptive neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), bradykinin (BK), somatostatin (SST), and dynorphin-A (Dyn-A). Compared to control, ovariectomized rats presented higher SP (P = 0.009) and CGRP (P = 0.017) concentrations. OA induction increased the spinal level of SP (+ 33%, P < 0.020) and decreased the release of BK (- 20%, (P < 0.037)). The OA-E rats at functional assessment put more % body weight on the affected hind limb than OA-P rats at D7 (P = 0.027) and D56 (P = 0.033), and showed higher PWT at D56 (P = 0.009), suggesting an analgesic and anti-allodynic effect of 17β-estradiol. Interestingly, the 17β-estradiol treatment counteracted the increase of spinal concentration of Dyn-A (P < 0.016) and CGRP (P < 0.018). These results clearly indicate that 17β-estradiol interfers with the development of central sensitization and confirm that gender dimorphism should be considered when looking at pain evaluation.

Does Femoral Head Translation Vary by Sex and Side in Asymptomatic Hips During a Weightbearing Apprehension Test?

Hip microinstability is an increasingly recognized source of pain and dysfunction but has no agreed upon diagnostic criteria and the pathophysiology remains unclear. It has been suggested that pain associated with microinstability is caused by excess translation of the femoral head. Recent research indicates that single-plane femoral head translation can be reliably measured using dynamic ultrasonography during a supine clinical examination; however, the overall accuracy of that technique has not been established, and the range of femoral head translation values that are found in individuals with no history of surgery or symptomatic pathology is unknown. (1) How much femoral head translation is present in native, uninjured hips during a weightbearing apprehension position for females and males? (2) How large is the side-to-side difference in hip translation and rotation within the same individual in females and males with no history of surgery or pain during the weightbearing apprehension position? (3) What differences exist in femoral head translation and rotation when comparing females to males? Twenty-two young adults (11 males, 11 females; mean age 22 ± 2 years; BMI 22 ± 5 kg/m2) with no history of hip pain, no known hip injury, and who never had hip surgery participated in this study. High-resolution CT images of the femur and pelvis were acquired for each participant, and the bone tissue was segmented from the CT volume. Synchronized biplane radiographs were collected during a neutral standing trial and during a static weightbearing apprehension position in which the participant extended, externally rotated, and abducted at their back hip while standing with their feet split in the AP direction. A validated volumetric model-based tracking technique was used to match the patient-specific bone models to the biplane radiographs with an accuracy of 0.3 mm for translation and 0.8° for rotation. Translation of the center of the femoral head relative to the center of the acetabulum and rotation of the femur relative to the pelvis from neutral to the weightbearing apprehension position were calculated. Sex-based differences in hip kinematics were assessed by bivariate linear regression. The median (range) translation during the weightbearing apprehension position in females was 0.9 mm (0.2 to 2.7 mm), which was less than in the 1.3 mm (0.2 to 2.6 mm) translation found in males (median difference of 0.5 mm; p = 0.04). The median absolute side-to-side difference in translation during the pivot was 1.4 mm (0.1 to 3.8 mm) in females and 1.3 mm (0.1 to 4.4 mm) in males. These findings demonstrate that the femoral head translates the same under bodyweight loading as previously observed during supine exam, showing the inherent stability of the hip with no history of surgery or symptomatic pathology. This study also provides normal values for comparison with individuals who have suspected microinstability. Future directions for research include directly comparing biplane radiography to alternative imaging techniques, such as dynamic ultrasound, for identifying hip microinstability and identifying threshold values for symptomatic hip microinstability. Level III, prognostic study.

Immediate effect of prefabricated and UCBL foot orthoses on alignment of midfoot and forefoot in young people with symptomatic flexible flatfoot: A radiographic evaluation.

Radiographic imaging has been considered the gold standard in evaluating the skeletal alignment of the foot in static weightbearing. The effects of foot orthoses on the alignment of foot bones have been mostly evaluated using lateral view x-rays. The posterior-anterior view has not been investigated extensively. To investigate the effects of 2 foot orthoses: University of California Biomechanics Laboratory Orthosis (UCBL) and a prefabricated orthosis (P-FFO) on the alignment of foot bones on anterior-posterior x-rays in young people with symptomatic flexible flatfoot (SFF). This is a randomized, crossover study. Fifteen participants (mean [SD], 23.67 ± 2 years) with SFF were randomly imaged in 3 different conditions: shoes only, shoes + P-FFO, and shoes + UCBL. The talonavicular coverage, the first and the second talometatarsal angles, the intermetatarsal angle, and the cuboid abduction angle (CAA) were measured on weightbearing, anterior-posterior x-ray images for each condition. Both orthotic designs demonstrated a significant reduction in the talonavicular coverage, the first and the second talometatarsal angles, and the CAA compared with the shoe-only condition (P < .001). The talonavicular coverage angle reduced by ∼11% using P-FFO compared with UCBL (P < .005). No significant differences were observed for other angles between the 2 orthotic conditions. Both orthotic conditions improved the talonavicular coverage, first and the second talometatarsal angle, and CAA in young people with SFF. The walls of the UCBL orthosis did not result in further correction of the talonavicular coverage angle compared with the prefabricated FFO design.

Pain highly correlates to collagenase-induced oa-like damage in female mice but not in males.

Pain highly correlates to collagenase-induced oa-like damage in female mice but not in males.

The electromyographic activity characteristics of the gluteus medius muscle before and after total hip arthroplasty

The clinical outcomes of total hip arthroplasty are influenced by the correct muscle function that determines good, longterm and proper function of the artificial joint. The aim of the study was to analyze the electromyographic activity of the gluteus medius muscle in patients with hip osteoarthritis and after arthroplasty in various static weight bearing conditions, both on the affected and contralateral side. The prospective study involved 70 patients qualified for hip replacement. Patients underwent a surface electromyography of the gluteus medius muscle which involved the Trendelenburg test. The normalized results were obtained for both hips, preoperatively and 6 months after arthroplasty. The only muscle activity differences were found at a full load condition of lower limb. In the preoperative assessment, the activity of the gluteus medius muscle was greater on the side qualified for surgery. After arthroplasty and the rehabilitation period, the muscle activity on the operated side decreased and significantly increased on the contralateral side. Detailed analysis of the contralateral side revealed relationship with osteoarthritis. Previous hip arthroplasty of that side resulted in lower muscle activity, similar to fully functional joints. The activity characteristics of the gluteus medius muscle vary depending on the condition of the joint, and the characteristics change as a result of the surgical procedure performed on both the operated and contralateral sides. These dependencies should be taken into account in the rehabilitation process, especially at the side opposite to the operated one.

Pain and Activity Measurements.

Musculoskeletal pain contributes significantly to chronic pain experienced by adults and to health care use. This chapter details several methods to evaluate pain and physical activity in mice that can be applied to preclinical orthopedic models. These methods include the von Frey filament assay that measures mechanical allodynia, open-field activity assays for evaluation of ambulation, and incapacitance measurements to determine static weight bearing.

IL-33 enhances macrophage release of IL-1β and promotes pain and inflammation in gouty arthritis.

To investigate the role of IL-33 in gouty arthritis. 174 Balb/c (wild-type) and 54 ST2-/- mice were used in this study. In vitro experiments were conducted in bone marrow-derived macrophages (BMDMs). Synovial fluid samples from gouty arthritis (n = 7) and osteoarthritis (n = 8) hospital patients were used to measure IL-33 and sST2 levels. Gout was induced by injection of monosodium urate (MSU) crystals in the knee joint of mice. Pain was determined using the electronic von Frey and static weight bearing. Neutrophil recruitment was determined by H&E staining, Rosenfeld staining slides, and MPO activity. ELISA was used for cytokine and sST2 measurement. The priming effect of IL-33 was determined in BMDM. Synovial fluid of gout patients showed higher IL-33 levels and neutrophil counts than osteoarthritis patients. In mice, the absence of ST2 prevented mechanical pain, knee joint edema, neutrophil recruitment to the knee joint, and lowered IL-1β and superoxide anion levels. In macrophages, IL-33 enhanced the release of IL-1β and TNF-α, and BMDMs from ST2-/- showed reduced levels of these cytokines after stimulus with MSU crystals. IL-33 mediates gout pain and inflammation by boosting macrophages production of cytokines upon MSU crystals stimulus.

Weightbearing Radiography and MRI Findings in Ankle Fractures.

Background. Static weightbearing radiography can be used to assess stability in ankle fractures by measuring lateral talar shift (medial clear space; MCS). However, the correlation of a stable ankle joint under weightbearing load and the structural integrity of the deltoid ligament has not been shown. In this study, we assessed deltoid ligament integrity on magnetic resonance imaging (MRI) and correlated that with weightbearing and gravity stress test radiography. Methods. Thirty-four patients with supination external rotation II-IV (SER) fractures underwent MRI, weightbearing radiography, and gravity stress test. On MRI, the deep anterior and posterior tibiotalar deltoid, tibionavicular and tibiocalcaneal ligaments, as well as the syndesmosis were assessed as intact, partial rupture, or complete rupture. The MCS was measured as the distance between the lateral border of the medial malleolus and the medial border of the talus at the level of the talar dome on the mortise view. Results. Twenty-three patients suffered a deep anterior tibiotalar ligament rupture (16 partial; 7 complete) and 2 a deep posterior tibiotalar ligament tear (1 partial; 1 complete). For MCS on weightbearing radiography, no statistically significant differences were identified between any of the individual groups. With gravity stress radiography, only a complete tear of the tibiocalcaneal ligament showed a significantly higher MCS than a partial tear or intact tibiocalcaneal ligament (P < .005). No other ligament disruption showed a significant difference between the complete rupture versus intact or partial tear. Conclusion. Weightbearing radiography does not show much variation in terms of MCS even with ligamentous disruption and fibula fracture. The talus often centers itself underneath the tibia with weightbearing radiography.Levels of Evidence: Level III: Retrospective cohort study.

Radiographic findings have an association with weight bearing and locomotion in English bulldogs

BackgroundEnglish bulldogs are known to be prone to skeletal problems, but knowledge is lacking of the effect of these problems on locomotion and function. This study was undertaken to report the conformational, orthopaedic and radiographic findings in a cohort of English bulldogs in Finland and to evaluate how these findings affect weight bearing and locomotion of the dogs. Twenty-eight English bulldogs were prospectively recruited to this cross-sectional study. An orthopaedic examination, measurements of conformation, static and dynamic weight bearing, and radiographic examinations of elbow, hip, stifle joints and spine were done.ResultsThe English bulldogs carried a mean of 67.3% and 62.1% of their body weight in front limbs while standing and trotting, respectively. Front and hind limb lameness was seen in 20.8% (5/24) and 12.5% (3/24) of dogs, respectively. At orthopaedic examination, abnormal palpation findings (i.e. pain response, crepitation, swelling or subjectively decreased range of motion) were observed in a median of one joint (range 0–5) in each dog. Medial patellar luxation was diagnosed in 33.0% (8/24) of the evaluated dogs. At radiographic examination, elbow dysplasia was diagnosed in 48.2% (27/56) of elbow joints and severe hip dysplasia in 55.4% (31/56) of hip joints. The grade of elbow dysplasia was negatively associated with the ratio of static weight bearing between the front and hind limbs (slope estimate − 1.46, 95% CI − 2.75 to − 0.16, P = 0.03) and in dynamic weight bearing the ratio of total pressure index between the front and hind limbs (slope estimate − 0.088, 95% CI − 0.164 to 0.025, P = 0.03). The severity of hip dysplasia or hip osteoarthritis was not associated with the amount of static or dynamic weight bearing, but all except one dog were diagnosed with Fédération Cynologique Internationale grade C, D or E hips (dysplastic). In the spine, 78.6% (22/28) of the dogs had at least one malformed vertebra.ConclusionsOrthopaedic diseases and abnormal radiographic findings were common in the English bulldogs studied. The static weight bearing of the dogs was heavily distributed to the front limbs. With increasing severity of elbow dysplasia, the static and dynamic weight bearing shifted from dysplastic elbows to hind limbs.

Load response of an osseointegrated implant used in the treatment of unilateral transfemoral amputation: An early implant loosening case study

BackgroundOsseointegrated implants for transfemoral amputees facilitate direct load transfer between the prosthetic limb and femur; however, implant loosening is a common complication, and the associated implant-bone loads remain poorly understood. This case study aimed to use patient-specific computational modeling to evaluate bone-implant interface loading during standing and walking in a transfemoral amputee with an osseointegrated implant prior to prosthesis loosening and revision surgery. MethodsOne male transfemoral amputee with an osseointegrated implant was recruited (age: 59-yrs, weight: 83 kg) and computed tomography (CT) performed on the residual limb approximately 3 months prior to implant failure. Gait analyses were performed, and the CT images used to develop a finite element model of the patient's implant and surrounding bone. Simulations of static weight bearing, and over-ground walking were then performed. FindingsDuring standing, maximum and minimum principal strains in trabecular bone adjacent to the implant were 0.26% and −0.30%, respectively. Strains generated at the instant of contralateral toe-off and contralateral heel strike during walking were substantially higher and resulted in local trabecular bone yielding. Specifically, the maximum and minimum principal strains in the thin layer of trabecular bone surrounding the distal end of the implant were 1.15% and −0.98%, respectively. InterpretationLocalised yielding of trabecular bone at the interface between the femur and implant in transfemoral amputee osseointegrated prosthesis recipients may present a risk of implant loosening due to periprosthetic bone fracture during walking. Rehabilitation exercises should aim to produce implant-bone loading that stimulates bone remodelling to provide effective bone conditioning prior to ambulation.