Altered Joint Biomechanics Research Articles

TOTAL HIP ARTHROPLASTY IN PAGET'S DISEASE: COMPARISON OF OUTCOMES AFTER CEMENTED VERSUS UNCEMENTED ARTHROPLASTY. A SYSTEMATIC REVIEW AND META-ANALYSIS

Paget's disease of bone (PDB) is characterised by increased bone resorption and development of an erratic bone structure that is highly fragile and susceptible to fracture. In addition, altered joint biomechanics lead to arthritis, more often in the hip and pelvis, resulting in disability and a Total hip Arthroplasty (THA) may be required. THA in PDB is associated with more complications compared to normal population. There is no consensus on the type of arthroplasty that performs better in people with PDB. To our knowledge, there is no meta-analysis in literature on this rare problem.We undertook a systematic review and meta-analysis to compare the effectiveness of cemented versus cementless THA in patients with PDB. PRISMA guidelines were followed. Search strings were generated based on Boolean operators for identification of the reference articles.31 studies were included overall. Revision rate was lower in the cementless group compared to the cemented group (chi square=4.36, p=0.04), aseptic loosening was lesser in the cementless group compared to the cemented group (chi square=4.13, p=0.04). The type of the arthroplasty did not affect the infection rate (chi square=2.51, p=0.11), pre and post op Harris Hip Score showed statistically significant difference, but there was no difference between types of arthroplastyWe conclude that THA with uncemented components is better and provided lower revision and aseptic loosening when compared to cemented groups in patients with PDB.

A minireview of four-dimensional CT and joint biomechanics

Since its introduction, four dimensional computed tomography (4D CT) has improved the precision of a variety of diagnostic challenges such as radiation therapy in oncology and has also been expanded into cardiovascular assessments as well. Its use in musculoskeletal imaging marks a breakthrough in peripheral joint imaging, enabling detailed analysis of joint biomechanics and stability across various joints such as the knee, wrist, shoulder, and ankle. Studies employing 4D CT have offered new insights into normative and altered joint biomechanics, contributing to the diagnosis of joint pathologies and aiding in surgical planning. Looking ahead, artificial intelligence and photon-counting CT systems are poised to further refine 4D CT's capabilities, potentially leading to personalized diagnostic and therapeutic approaches based on individualized biomechanical characteristics. This review delves into the transformative role of four-dimensional computed tomography in musculoskeletal imaging, particularly its applications in understanding joint biomechanics.

Quadriceps Muscle Action and Association With Knee Joint Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction.

Insufficient quadriceps force production and altered knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) may contribute to a heightened risk of osteoarthritis. Quadriceps muscle lengthening dynamics affect force production and knee joint loading; however, no study to our knowledge has quantified in vivo quadriceps dynamics during walking in individuals with ACLR or examined correlations with joint biomechanics. Our purpose was to quantify bilateral vastus lateralis (VL) fascicle length change and the association thereof with gait biomechanics during weight acceptance in individuals with ACLR. The authors hypothesized that ACLR limbs would exhibit more fascicle lengthening than contralateral limbs. The authors also hypothesized that ACLR limbs would exhibit positive correlations between VL fascicle lengthening and knee joint biomechanics during weight acceptance in walking. The authors quantified VL contractile dynamics via cine B-mode ultrasound imaging in 18 individuals with ACLR walking on an instrumented treadmill. In partial support of our hypothesis, ACLR limb VL fascicles activated without length change on average during weight acceptance while fascicle length on the contralateral limb decreased on average. The authors found a positive association between fascicle lengthening and increase in knee extensor moments in both limbs. Our results suggest that examining quadriceps muscle dynamics may elucidate underlying mechanisms relevant to osteoarthritis.

Biomechanical compensations during a stand-to-sit maneuver using transfemoral osseointegrated prostheses: A case series

BackgroundPatients with transfemoral amputation and socket prostheses are at a heightened risk of developing musculoskeletal overuse injuries, commonly due to altered joint biomechanics. Osseointegrated prostheses, which involve direct anchorage of the prosthesis to the residual limb through a bone anchored prosthesis, are a novel alternative to sockets yet their biomechanical effect is largely unknown. MethodsFour patients scheduled to undergo unilateral transfemoral prosthesis osseointegration completed two data collections (baseline with socket prosthesis and 12-months after prosthesis osseointegration) in which whole-body kinematics and ground reaction forces were collected during stand-to-sit tasks. Trunk, pelvis, and hip kinematics, and the surrounding muscle forces, were calculated using subject-specific musculoskeletal models developed in OpenSim. Peak joint angles and muscle forces were compared between timepoints using Cohen's d effect sizes. FindingsCompared to baseline with socket prostheses, patients with osseointegrated prostheses demonstrated reduced lateral trunk bending (d = 1.46), pelvic obliquity (d = 1.09), and rotation (d = 1.77) toward the amputated limb during the stand to sit task. This was accompanied by increased amputated limb hip flexor, abductor, and rotator muscle forces (d> > 0.8). InterpretationImproved lumbopelvic movement patterns and stabilizing muscle forces when using an osseointegrated prosthesis indicate that this novel prosthesis type likely reduces the risk of the development and/or progression of overuse injuries, such as low back pain and osteoarthritis. We attribute the increased muscle hip muscle forces to the increased load transmission between the osseointegrated prosthesis and residual limb, which allows a greater eccentric ability of the amputated limb to control lowering during the stand-to-sit task.

Are Outcomes of Acute Meniscus Root Tear Repair Better Than Debridement or Nonoperative Management? A Systematic Review

Background: Meniscus root tears (MRTs) are defined as radial tears within 1 cm of the meniscus root insertion or an avulsion of the meniscus root itself. They lead to altered joint loading because of the failure to convert axial (compressive) loads into hoop stresses. Untreated MRTs can result in altered joint biomechanics and accelerated articular cartilage degeneration and the development of osteoarthritis (OA), yet optimal management remains unclear. Purpose: To review treatment outcomes after acute MRTs by surgical repair, debridement, meniscectomy, or nonoperative treatment. Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the evidence from human clinical studies was conducted with electronic searches of the PUBMED, Medline, EMBASE, and the Cochrane Library databases. One reviewer extracted the data and 2 reviewers assessed the risk of bias and performed synthesis of the evidence. Results: Eleven studies of low to moderate methodological quality were identified. All treatment options improved functional scores after >12 months. Arthroscopic repair may be associated with better functional outcomes when compared with partial meniscectomy and nonoperative management at 12-month follow-up. Radiographic progression of OA occurred in all treatment groups; there was some evidence that this was delayed after repair when compared with other treatments. Baseline severity of meniscal extrusion, varus malalignment, and pretreatment degeneration were predictors of poor functional outcomes. Age was not found to be an independent predictor of functional outcome. Conclusion: The current level 3 and 4 evidence suggests that arthroscopic repair may result in slower progression of radiological deterioration compared with meniscectomy and nonoperative management. The current literature does not support the exclusion of patients from MRT repair on the basis of age. Patients undergoing acute MRT treatments (repair, debridement, or nonoperative) can be expected to experience improvement in functional outcomes after >12 months. The strength of conclusions are limited because of the paucity of high-quality studies on this subject. Further studies, preferably randomized sham controlled trials with function-oriented rehabilitation programs, are needed to compare treatment strategies and stratification of care based on the risk of meniscal extrusion. Registration: CRD42018085092 (PROSPERO).

Maximizing Muscle Function in Cuff-Deficient Shoulders: A Rehabilitation Proposal for Reverse Arthroplasty.

PurposeThe purpose of this review is to describe the role of altered joint biomechanics in reverse shoulder arthroplasty and to propose a rehabilitation protocol for a cuff-deficient glenohumeral joint based on the current evidence.Methods and Materials: The proposed rehabilitation incorporates the principles of pertinent muscle loading while considering risk factors and surgical complications.ResultsIn light of altered function of shoulder muscles in reverse arthroplasty, scapular plane abduction should be more often utilized as it better activates deltoid, teres minor, upper trapezius, and serratus anterior. Given the absence of supraspinatus and infraspinatus and reduction of external rotation moment arm of the deltoid in reverse arthroplasty, significant recovery of external rotation may not occur, although an intact teres minor may assist external rotation in the elevated position.ConclusionImproving the efficiency of deltoid function before and after reverse shoulder arthroplasty is a key factor in the rehabilitation of the cuff deficient shoulders. Performing exercises in scapular plane and higher abduction angles activates deltoid and other important muscles more efficiently and optimizes surgical outcomes.

Computer-assisted femoral head reduction osteotomies: an approach for anatomic reconstruction of severely deformed Legg-Calv\xe9-Perthes hips. A pilot study of six patients

BackgroundLegg–Calvé–Perthes (LCP) is a common orthopedic childhood disease that causes a deformity of the femoral head and to an adaptive deformity of the acetabulum. The altered joint biomechanics can result in early joint degeneration that requires total hip arthroplasty. In 2002, Ganz et al. introduced the femoral head reduction osteotomy (FHRO) as a direct joint-preserving treatment. The procedure remains one of the most challenging in hip surgery. Computer-based 3D preoperative planning and patient-specific navigation instruments have been successfully used to reduce technical complexity in other anatomies. The purpose of this study was to report the first results in the treatment of 6 patients to investigate whether our approach is feasible and safe.MethodsIn this retrospective pilot study, 6 LCP patients were treated with FHRO in multiple centers between May 2017 and June 2019. Based on patient-specific 3D-models of the hips, the surgeries were simulated in a step-wise fashion. Patient-specific instruments tailored for FHRO were designed, 3D-printed and used in the surgeries for navigating the osteotomies. The results were assessed radiographically [diameter index, sphericity index, Stulberg classification, extrusion index, LCE-, Tönnis-, CCD-angle and Shenton line] and the time and costs were recorded. Radiologic values were tested for normal distribution using the Shapiro–Wilk test and for significance using Wilcoxon signed-rank test.ResultsThe sphericity index improved postoperatively by 20% (p = 0.028). The postoperative diameter of the femoral head differed by only 1.8% (p = 0.043) from the contralateral side and Stulberg grading improved from poor coxarthrosis outcome to good outcome (p = 0.026). All patients underwent acetabular reorientation by periacetabular osteotomy. The average time (in minutes) for preliminary analysis, computer simulation and patient-specific instrument design was 63 (±48), 156 (±64) and 105 (±68.5), respectively.ConclusionThe clinical feasibility of our approach to FHRO has been demonstrated. The results showed significant improvement compared to the preoperative situation. All operations were performed by experienced surgeons; nevertheless, three complications occurred, showing that FHRO remains one of the most complex hip surgeries even with computer assistance. However, none of the complications were directly related to the simulation or the navigation technique.

Metabolic Bone Diseases and Total Hip Arthroplasty: Preventing Complications.

Metabolic bone diseases are a diverse group of conditions characterized by abnormalities in calcium metabolism and/or bone cell physiology. These unbalanced processes can eventually lead to bony deformities and altered joint biomechanics, resulting in degenerative joint disease. Not infrequently, patients with metabolic bone diseases have restricting hip joint pain that ultimately necessitates hip arthroplasty. To minimize complications, the surgeon must consider the particular characteristics of these patients. The surgical and medical management of patients with metabolic bone diseases undergoing hip arthroplasty requires appropriate preoperative diagnosis, careful attention to the technical challenges of surgery, and strategies to maximize the long-term results of the surgical intervention, such as the use of bone anabolic and anticatabolic agents.

Knee Biomechanics During Jogging After Arthroscopic Partial Meniscectomy: A Longitudinal Study

Background: Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population. Purpose: To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up. Study Design: Controlled laboratory study. Methods: Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg. Results: At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg (P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P > .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg (P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline (P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg (P < .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs (P > .05). Conclusion: Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance. Clinical Relevance: These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM.

Reliability of Zebris Motion Analysis System in Healthy Athletes and Athletes with Anterior Cruciate Ligament Reconstruction

Background: Reconstruction surgery is one of the treatment methods after an anterior cruciate ligament (ACL) injury especially in athletes. Reconstructed ACL is associated with altered joint biomechanics, abnormal muscle strength, gait disorder and decreased athletic performance. Abnormal walking pattern has been shown to be one of the functional consequences of ACL reconstruction. Objectives: The aim of this study was to investigate the reliability of kinematic and spatiotemporal gait parameters after ACL reconstruction using Zebris ultrasound movement analysis system. Methods: A sample of convenience including 20 healthy athletes and 20 athletes 4 to 6 months after ACL reconstruction participated. Subjects walked on a treadmill for one minute at preferred, high and low speeds and kinematic and spatio - temporal parameters including stride time, stride length, maximum knee flexion, maximum knee flexion velocity and maximum knee extension velocity are calculated. Results: In the patient group, relative reliability measures for almost all parameters were high at low (ICC: 0.7 - 0.97), preferred and high speeds (ICC: 0.75 - 0.97). This was also true for the control group, were reliability for all parameters was high at low, preferred (ICC: 0.74 - 0.99) and high (ICC: 0.83 - 0.99) speeds, except for stride time of the left leg which showed moderate reliability. Additionally, at high speed, all parameters revealed very high reliability. Conclusions: Zebris movement analysis system is a highly reliable instrument for the measurement of gait parameters at different speeds in healthy athletes and those after ACL reconstruction surgery. This implies its use in the assessment and treatment process of gait deficits in such a clinically important population.

Coronal tibial slope is associated with accelerated knee osteoarthritis: data from the Osteoarthritis Initiative.

BackgroundAccelerated knee osteoarthritis may be a unique subset of knee osteoarthritis, which is associated with greater knee pain and disability. Identifying risk factors for accelerated knee osteoarthritis is vital to recognizing people who will develop accelerated knee osteoarthritis and initiating early interventions. The geometry of an articular surface (e.g., coronal tibial slope), which is a determinant of altered joint biomechanics, may be an important risk factor for incident accelerated knee osteoarthritis. We aimed to determine if baseline coronal tibial slope is associated with incident accelerated knee osteoarthritis or common knee osteoarthritis.MethodsWe conducted a case–control study using data and images from baseline and the first 4 years of follow-up in the Osteoarthritis Initiative. We included three groups: 1) individuals with incident accelerated knee osteoarthritis, 2) individuals with common knee osteoarthritis progression, and 3) a control group with no knee osteoarthritis at any time. We did 1:1:1 matching for the 3 groups based on sex. Weight-bearing, fixed flexion posterior-anterior knee radiographs were obtained at each visit. One reader manually measured baseline coronal tibial slope on the radiographs. Baseline femorotibial angle was measured on the radiographs using a semi-automated program. To assess the relationship between slope (predictor) and incident accelerated knee osteoarthritis or common knee osteoarthritis (outcomes) compared with no knee osteoarthritis (reference outcome), we performed multinomial logistic regression analyses adjusted for sex.ResultsThe mean baseline slope for incident accelerated knee osteoarthritis, common knee osteoarthritis, and no knee osteoarthritis were 3.1(2.0), 2.7(2.1), and 2.6(1.9); respectively. A greater slope was associated with an increased risk of incident accelerated knee osteoarthritis (OR = 1.15 per degree, 95 % CI = 1.01 to 1.32) but not common knee osteoarthritis (OR = 1.04, 95 % CI = 0.91 to 1.19). These findings were similar when adjusted for recent injury. Among knees with varus malalignment a greater slope increases the odds of incident accelerated knee osteoarthritis; there is no significant relationship between slope and incident accelerated knee osteoarthritis among knees with normal alignment.ConclusionsCoronal tibial slope, particularly among knees with malalignment, may be an important risk factor for incident accelerated knee osteoarthritis.

Does meniscal pathology alter gait knee biomechanics and strength post-ACL reconstruction?

Individuals following anterior cruciate ligament reconstruction (ACLR) with concomitant meniscal pathology have a higher risk of developing knee osteoarthritis (OA) compared to those with isolated ACLR. Knee extensor weakness and altered dynamic knee joint biomechanics have been suggested to play a role in the development of knee OA following ACLR. This study investigated whether these factors differ in people following ACLR who have concomitant meniscal pathology compared to patients with isolated ACLR. Thirty-three patients with isolated ACLR and 34 patients with ACLR and meniscal pathology underwent strength and gait assessment 12-24months post-operatively. Primary measures were peak isometric knee extensor torque and knee adduction moment (peak and impulse). Secondary measures included peak knee flexion moment and knee kinematics (sagittal and transverse). There were no between-group differences in knee extensor strength [mean difference (95% CI) 0.09 (-0.23 to 0.42)Nm/kg, n.s.], peak knee adduction moment [-0.02 (-0.54 to 0.49)Nm/(BW×HT)%, n.s.] or knee adduction moment impulse [0.01 (-0.15 to 0.17)Nm/(BW×HT)%, p=n.s.]. No between-group differences were found for any secondary measures. No evidence was found to suggest that the higher prevalence of OA in patients with ACLR and meniscal pathology compared to patients with isolated ACLR is attributed to reduced knee muscle strength or altered knee joint biomechanics assessed 1-2years post-surgery. Given that there is a higher incidence of knee OA in patients with concomitant meniscal pathology and ACLR, further investigation is needed so that population-specific rehabilitation protocols can be developed. III.

Decreased Knee Joint Loading Associated With Early Knee Osteoarthritis After Anterior Cruciate Ligament Injury

Background: Anterior cruciate ligament (ACL) injury predisposes individuals to early-onset knee joint osteoarthritis (OA). Abnormal joint loading is apparent after ACL injury and reconstruction. The relationship between altered joint biomechanics and the development of knee OA is unknown. Hypothesis: Altered knee joint kinetics and medial compartment contact forces initially after injury and reconstruction are associated with radiographic knee OA 5 years after reconstruction. Study Design: Case-control study; Level of evidence, 3. Methods: Individuals with acute, unilateral ACL injury completed gait analysis before (baseline) and after (posttraining) preoperative rehabilitation and at 6 months, 1 year, and 2 years after reconstruction. Surface electromyographic and knee biomechanical data served as inputs to an electromyographically driven musculoskeletal model to estimate knee joint contact forces. Patients completed radiographic testing 5 years after reconstruction. Differences in knee joint kinetics and contact forces were compared between patients with and those without radiographic knee OA. Results: Patients with OA walked with greater frontal plane interlimb differences than those without OA (nonOA) at baseline (peak knee adduction moment difference: 0.00 ± 0.08 N·m/kg·m [nonOA] vs −0.15 ± 0.09 N·m/kg·m [OA], P = .014; peak knee adduction moment impulse difference: −0.001 ± 0.032 N·m·s/kg·m [nonOA] vs −0.048 ± 0.031 N·m·s/kg·m [OA], P = .042). The involved limb knee adduction moment impulse of the group with osteoarthritis was also lower than that of the group without osteoarthritis at baseline (0.087 ± 0.023 N·m·s/kg·m [nonOA] vs 0.049 ± 0.018 N·m·s/kg·m [OA], P = .023). Significant group differences were absent at posttraining but reemerged 6 months after reconstruction (peak knee adduction moment difference: 0.02 ± 0.04 N·m/kg·m [nonOA] vs −0.06 ± 0.11 N·m/kg·m [OA], P = .043). In addition, the OA group walked with lower peak medial compartment contact forces of the involved limb than did the group without OA at 6 months (2.89 ± 0.52 body weight [nonOA] vs 2.10 ± 0.69 body weight [OA], P = .036). Conclusion: Patients who had radiographic knee OA 5 years after ACL reconstruction walked with lower knee adduction moments and medial compartment joint contact forces than did those patients without OA early after injury and reconstruction.

Vertical Tears of the Lateral Meniscus: Effects on In Vitro Tibiofemoral Joint Mechanics.

Background:Lateral meniscal tears are often seen with acute anterior cruciate ligament (ACL) injury and may be left in situ, repaired, or treated with meniscectomy. Clinical studies have shown good outcomes with vertical tears left in situ and poor outcomes following meniscectomy. However, clinically relevant studies are needed to establish a biomechanical foundation for treatment of these tears, particularly regarding the effects of meniscectomy.Purpose:To compare tibiofemoral joint mechanics following vertical lateral meniscal tears and meniscectomies. We hypothesized that a peripheral vertical tear of the lateral meniscus would alter joint mechanics, increasing contact pressure and area, and that more drastic effects would be seen following meniscectomy, at higher knee flexion angles, and with increased loads.Study Design:Controlled laboratory study.Methods:Ten fresh-frozen cadaveric knees (average age, 55 ± 12 years) were tested with 5 lateral meniscus states: intact, short vertical tear, extended vertical tear, posterior horn partial meniscectomy (rim intact), and posterior horn subtotal meniscectomy (rim excised). The specimens were loaded axially at knee flexion angles of 0°, 30°, and 60°, and musculotendinous forces were applied, simulating a 2-legged squat. Intra-articular contact pressures were measured using pressure-sensitive Fuji film. Kinematic data were acquired through digitization of fiducial markers.Results:Vertical tears did not cause a significant change in contact pressure or area. Partial meniscectomy increased maximum contact pressures in the lateral compartment at 30° and 60° from 5.3 MPa to 7.2 MPa and 7.6 MPa, respectively (P = .02, P = .007). Subtotal meniscectomy (8.4 MPa) significantly increased contact pressure compared with partial meniscectomy (7.6 MPa) at 60° (P = .04). Both meniscectomy states significantly increased contact pressures with increasing flexion from 0° to 60° (P < .001, P < .001).Conclusion:Vertical tears of the lateral meniscus during a simulated 2-legged squat did not significantly change contact pressures and areas compared with an intact meniscus. However, treating these tears with partial and complete meniscectomy significantly increased maximum contact pressures.Clinical Relevance:Biomechanical evidence supports treating vertical lateral meniscus tears with meniscal-sparing techniques as opposed to meniscectomy, which may lead to progressive degenerative joint disease from altered joint biomechanics.

Altered tibiofemoral joint contact mechanics and kinematics in patients with knee osteoarthritis and episodic complaints of joint instability

BackgroundTo evaluate knee joint contact mechanics and kinematics during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability. MethodsForty-three subjects, 11 with medial compartment knee osteoarthritis and self-reported instability (unstable), 7 with medial compartment knee osteoarthritis but no reports of instability (stable), and 25 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a downhill gait task on a treadmill. FindingsThe medial compartment contact point excursions were longer in the unstable group compared to the stable (P=0.046) and the control groups (P=0.016). The peak medial compartment contact point velocity was also greater for the unstable group compared to the stable (P=0.047) and control groups (P=0.022). Additionally, the unstable group demonstrated a coupled movement pattern of knee extension and external rotation after heel contact which was different than the coupled motion of knee flexion and internal rotation demonstrated by stable and control groups. InterpretationOur findings suggest that knee joint contact mechanics and kinematics are altered during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability. The observed longer medial compartment contact point excursions and higher velocities represent objective signs of mechanical instability that may place the arthritic knee joint at increased risk for disease progression. Further research is indicated to explore the clinical relevance of altered contact mechanics and kinematics during other common daily activities and to assess the efficacy of rehabilitation programs to improve altered joint biomechanics in knee osteoarthritis patients with self-reported instability.

The effects of exercise therapy on knee joint biomechanics during walking in patients with knee osteoarthritis: secondary outcome analyses from a randomized controlled trial

Purpose: Exercise is recommended as a cornerstone in the non-pharmacological management of knee OA in order to improve mobility, pain, and function. Besides aiming at pain reduction, neuromuscular exercise programs for knee OA have a specific aim of optimization of the knee joint movements related to walking, while the effects on knee joint biomechanics of these exercises remain to be clarified. The objective of this analysis was to assess the effects of a neuromuscular and individualized exercise program on knee joint biomechanics during walking in patients with knee OA. Methods: This was a randomized trial with blinded outcome assessors (NCT01545258). Participants were randomly assigned (1:1) to 12 weeks of facility-based functional and individualized neuromuscular exercise therapy (ET), 3 sessions per week supervised by trained physical therapists, or a no attention control group (CG). To assess knee joint biomechanics during walking, 3-dimensional gait analyses were used, from which self-selected walking speeds, sagittal knee joint angles and internal knee joint moments were extracted. The pain subscale of the KOOS was used to assess the effects on pain. According to the protocol the analyses were based on the ‘Per-Protocol’ population, defined as participants following the protocol with complete and valid gait analyses. Analyses of covariance adjusting for the level at baseline were used to determine differences between groups (95% confidence intervals) in the changes from baseline at follow-up. Results: 60 participants were randomized to ET (n= 31) or CG (n=29). In the ET group, 1 participant had an invalid baseline gait analysis and 6 participants were lost to follow-up; in the CG 1 participant had invalid gait analysis at baseline, 4 were lost, 1 violated the protocol (exercise outside study), and 1 had invalid gait analysis at follow-up. Thus per protocol population included 46 participants (24 ET/22 CG). Summaries of baseline charateristics and KOOS pain (with changes) are given in table 1. Baseline values and changes in knee joint biomechanics during walking are presented in table 2. Besides a statistically significant group difference in the change from baseline in 2nd peak knee flexor moment (late stance), there were no group differences in the changes in knee joint biomechanics during walking (table). Conclusions: A 12-week supervised individualized neuromuscular exercise program has no effect on knee joint biomechanics during walking, except for a slight difference in the change in the knee flexor moment during late stance, indicating an increased moment in the ET. These results indicate that beneficial effects of neuromuscular exercise therapy on pain are not mediated through altered knee joint biomechanics during walking.Table 1Control group (n=22)Exercise group (n=24)-BaselineBaselineMean(SD)Mean(SD)Age, yr61.4(7.2)64.9(9.1)--Female sex, no. (%)16(73%)22(92%)--Height, m1.71(0.09)1.69(0.08)--Weight, kg83.2(15.7)83.1(14.0)--Body Mass index, kg/m228.4(4.6)29.1(4.1)-Baseline Mean (SD)Mean Change(95% CI)Baseline Mean (SD)Mean Change(95% CI)Mean difference (95%CI)PKOOS pain, 0-10059.2 (12.8)−1.1 (−4.9:2.6)63.6 (17.6)6.3 (2.7:9.9)−7.4 (−12.7:−2.2)0.006 Open table in a new tab Table 2Knee biomechanics during walkingControl group (n=22)Exercise group (n=24)Group differenceBaselineChangeBaselineChangeKnee biomechanics variableMean (SD)Mean (95% CI)Mean (SD)Mean (95% CI)Mean (95% CI)PKnee angle at heel strike, deg12.2 (5.7)1.3 (−1.3:3.9)13.8 (5.9)−0.2 (−2.8:2.3)1.5 (2.1:5.2)0.411st Knee flexion angle (early stance), deg23.1 (6.2)1.7 (−0.8:4.2)25.8 (7.6)−1.2 (−3.6:1.3)2.9 (−0.7:6.4)0.11Midstance knee extension angle, deg6.2 (6.3)1.1 (−1.6:3.7)10.1 (7.0)−1.3 (−3.8:1.3)2.3 (−1.4:6.1)0.22Swing phase peak flexion angle, deg59.5 (8.9)−0.6 (−3.8:2.7)61.4 (9.4)−1.1 (−4.2:2.1)0.5 (−4.0:5.1)0.811st peak knee extensor moment(early stance), Nm/Kg0.80 (0.25)0.04 (−0.10:0.180.65 (0.22)−0.01 (−0.15:0.12)0.05 (−0.14:0.25)0.592nd peak knee flexor moment(late stance), Nm/Kg−0.14 (0.16)0.05 (−0.02:0.11)−0.03 (0.16)−0.5 (−0.11:0.01)0.10 (0.01:0.19)0.041st peak knee adductor moment(early stance), Nm/Kg0.67 (0.25)0.05 (−0.03:0.12)0.65 (0.22)0.06 (−0.01:0.13)−0.01 (−0.11:0.09)0.842nd peak knee adductor moment(late stance), Nm/Kg0.50 (0.23)0.07 (0.01:0.014)0.44 (0.18)0.09 (0.02:0.16)−0.02 (−0.12:0.08)0.72Knee abductor angular impulse, Nm*s/kg24.7 (11.4)2.91 (−0.60:6.41)23.2 (9.4)3.09 (−0.27:6.45)−0.18 (−5.04:4.58)0.941st peak knee resultant moment (early stance), Nm/Kg1.04 (0.26)0.05 (−0.05:0.15)1.11 (0.29)0.04 (−0.06:0.14)0.01 (−0.14:0.15)0.912nd peak knee resultant moment (late stance), Nm/Kg0.58 (0.17)0.04 (−0.02:0.10)0.56 (0.12)0.06 (0.01:0.11)−0.02 (−0.10:0.06)0.59Walking speed, m/s1.36 (0.14)−0.05 (−0.14:0.04)1.35 (0.27)−0.03 (−0.12:0.06)−0.02 (−0.15:0.11)0.79 Open table in a new tab

Thoracolumbar spinal ligaments exhibit negative and transverse pre-strain

The present work represents the first reported bi-axial spinal ligament pre-strain data for the thoracic and lumbar spine. Ligament pre-strain (in-situ strain) is known to significantly alter joint biomechanics. However, there is currently a lack of comprehensive data with regards to spinal ligament pre-strain. The current work determined the pre-strain of 71 spinal ligaments (30 anterior longitudinal ligaments, 27 supraspinous ligaments and 14 interspinous ligaments). The interspinous ligament and the anterior longitudinal ligament exhibited bi-axial pre-strain distributions, demonstrating they are not uniaxial structures. The supraspinous ligament frequently exhibited large amounts of negative pre-strain or laxity suggesting it makes no mechanical contribution to spinal stability near the neutral posture. Upon implementing multi-axial pre-strain results into a finite element model of the lumbar spine, large differences in spinal biomechanics were observed. These results demonstrate the necessity of accounting for ligament pre-strain in biomechanical models. In addition, the authors present a unique experimental method for obtaining ligament pre-strain that presents a number of advantages when compared to standard techniques.

The Effect of the Variation in ACL Constitutive Model on Joint Kinematics and Biomechanics Under Different Loads: A Finite Element Study

The biomechanics and function of the anterior cruciate ligament (ACL) have been widely studied using both experimental and simulation methods. It is known that a constitutive model of joint tissue is a critical factor in the numerical simulation. Some different ligament constitutive models have been presented to describe the ACL material behavior. However, the effect of the variation in the ligament constitutive model on joint kinematics and biomechanics has still not been studied. In this paper, a three-dimensional finite element model of an intact tibiofemoral joint was reconstructed. Three ACL constitutive models were compared under different joint loads (such as anterior tibial force, varus tibial torque, and valgus tibial torque) to investigate the effect of the change of the ACL constitutive model. The three constitutive models corresponded to an isotropic hyperelasticity model, a transversely isotropic hyperelasticity model with neo-Hookean ground substance description, and a transversely isotropic hyperelastic model with nonlinear ground substance description. Although the material properties of these constitutive equations were fitted on the same uniaxial tension stress-strain curve, the change of the ACL material constitutive model was found to induce altered joint kinematics and biomechanics. The effect of different ACL constitutive equations on joint kinematics depended on both deformation direction and load type. The variation in the ACL constitutive models would influence the joint kinematic results greatly in both the anterior and internal directions under anterior tibial force as well as some other deformations such as the anterior and medial tibial translations under valgus tibial torque, and the medial tibial translation and internal rotation under varus torque. It was revealed that the transversely isotropic hyperelastic model with nonlinear ground substance description (FE model III) was the best representation of the realistic ACL property by a linear regression between the simulated and the experiment deformation results. But the comparison of the predicted and experiment force of ligaments showed that all the three ACL constitutive models represented similar force results. The stress value and distribution of ACL were also altered by the change in the constitutive equation. In brief, although different ACL constitutive models have been fitted using the same uniaxial tension curve and have the similar longitudinal material property, the ACL constitutive equation should still be carefully chosen to investigate joint kinematics and biomechanics due to the different transverse material behavior.

Síndrome do impacto do tornozelo na ressonância magnética: ensaio iconográfico

A síndrome do impacto do tornozelo é uma condição dolorosa causada por atrito de tecidos articulares, que é tanto causa quanto consequência de uma biomecânica alterada desta articulação. A sua principal causa são as lesões pós-traumáticas, principalmente lesões ligamentares, resultando em dor crônica no tornozelo. Do ponto de vista anatômico e clínico, estas síndromes são classificadas em: ântero-lateral, anterior, ântero-medial, póstero-medial e posterior. A ressonância magnética é um ótimo método diagnóstico para demonstrar as alterações ósseas e as partes moles dos vários tipos de impacto do tornozelo, fornecendo dados que auxiliam não só na comprovação desse diagnóstico, como na diferenciação com outras causas de dor articular. Os autores objetivam ilustrar os principais achados de ressonância magnética na síndrome do impacto do tornozelo.

Cementless total hip arthroplasty in Paget's disease of bone: a retrospective review.

Paget's disease of bone (PDB) is a localised chronic osteopathy leading to bone deformities, bone hypervascularity, structural weakness and altered joint biomechanics. The pelvis and upper femur are frequently involved, resulting in disabling hip disease, and total hip arthroplasty (THA) may be required. We performed a retrospective study on the management and the outcome of 39 uncemented hydroxyapatite fully-coated THA in patients with PDB of the hip. The follow-up averaged 79.4 months (range 24-194). Functional scores improved significantly and, using the Harris hip score, 84% of patients had an excellent clinical outcome at the latest follow-up. Despite one case of an uncemented acetabular component with probable loosening, no implant revision had been required at our latest follow-up. Signs of implant loosening were found to be significantly more frequent in patients with active disease. For this reason, we advocate the use of pre-operative medication with bisphosphonates to reduce disease activity. Another benefit of this treatment is the significant decrease of intra-operative blood loss. Provided the control of disease activity in the pre-operative period with bisphosphonates is achieved, good outcome of cementless THAs can be expected. Bisphosphonates reduced the risk of implant loosening and excessive intra-operative blood loss.