Prepping the knee in maximal flexion: getting into every nook, cranny, and fold.
Ontology highlight
ABSTRACT:
SUBMITTER: Knoll PA
PROVIDER: S-EPMC5484976 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Nordic hamstring exercise is performed to prevent knee flexor muscle strain injuries and used to assess their injury risks. However, what exactly Nordic hamstring strength indicates is not clear. We investigated the relationship between Nordic hamstring strength and maximal voluntary contraction (MVC) torque of the knee flexors measured by an isokinetic dynamometer. Sixteen healthy young men who had not experienced hamstring strain injuries participated in the study. In Nordic hamstring, each participant was instructed to lean forward as far as possible in 3 s (approximately 30°/s), and force at the ankle joint of the dominant leg was measured during the movement. The force was multiplied by lower leg length and converted into torque. MVC torque of the knee flexors was measured isometrically at 30°, 45°, 60°, and 90° knee flexion joint angles, and concentrically and eccentrically at 30°/s and 60°/s in 10°-90° knee flexion for the dominant leg in a prone position. Correlations among the dependent variables were assessed using Pearson's correlation coefficients. Peak Nordic hamstring torque ranged 96.8-163.5 Nm, and peak MVC eccentric torque ranged 50.7-109.4 Nm at 30°/s and 59.2-121.2 Nm at 60°/s. No significant correlations were evident between the peak Nordic hamstring torque and peak eccentric knee flexion torque (r = 0.24-0.3, p = 0.26-0.4). This was also the case for the Nordic hamstring torque and MVC torque of isometric (r = -0.03-0.1, p = 0.71-0.92) and concentric contractions (r = 0.28-0.49, p = 0.053-0.29). These results show that Nordic hamstring strength is not associated with the knee flexor torque measured by an isokinetic dynamometer. It may be that other factors than static and dynamic hamstring strengths affect Nordic hamstring strength.
| S-EPMC8880649 | biostudies-literature
Project description:BackgroundThe application of new techniques and materials in total knee arthroplasty (TKA) continue to be a primary focus in orthopedic surgery. The primary aim of the present study is to evaluate post TKA total range of motion (ROM) among a group of patients who received a gender specific high-flexion design modification implant compared to a control group of patients who received non-gender specific implants.Methods and resultsThe control group was comprised of 39 TKAs that were recruited pre-operatively and received the non-gender specific implant while the study group consisted of 39 TKAs who received gender specific implants. The study group yielded an improvement in mean post-operative ROM of 21° at 12 months, whereas the mean improvement in ROM among the control group was 11°. Thus, the study group had a 10° increased ROM improvement (91%) over the control group (p = 0.00060). In addition, 100% of the subjects with gender specific high-flexion implants achieved greater or equal ROM post-operatively compared to 82% for the control cohort. Lastly, women who exhibited greater pre-operative ROM and lower body mass index (BMI) were found to benefit the most with the gender specific prosthesis.ConclusionOur study demonstrates that among subjects with a normal BMI, the gender specific high-flexion knee implant is associated with increased ROM as compared to the non-gender specific non-high-flexion implant designs.
| S-EPMC3478993 | biostudies-literature
Project description:Flexion instability after total knee arthroplasty (TKA) is caused by an increased flexion gap compared with extension gap. Patients present with recurrent effusions, subjective instability (especially going downstairs), quadriceps weakness, and diffuse periretinacular pain. Manual testing for laxity in flexion is commonly done to confirm a diagnosis, although testing positions and laxity grades are inconsistent. Nonsurgical treatment includes quadriceps strengthening and bracing treatment. The mainstays to surgical management of femoral instability involve increasing the posterior condylar offset, decreasing the tibial slope, raising the joint line in combination with a thicker polyethylene insert, and ensuring appropriate rotation of implants. Patient outcomes after revision TKA for flexion instability show the least amount of improvement when compared with revisions for other TKA failure etiologies. Future work is needed to unify reproducible diagnostic criteria. Advancements in biomechanical analysis with motion detection, isokinetic quadriceps strength testing, and computational modeling are needed to advance the collective understanding of this underappreciated failure mechanism.
| S-EPMC6938456 | biostudies-literature
Project description:We examined the effect of increased anterior subject positioning toward the dynamometer's footplate during maximal voluntary isometric contractions (MVCs) on the joint moment, rotation and rate of torque development (RTD). Fourteen subjects, with their hip flexed (110°) and knee fully extended (180°), underwent ramp maximal and rapid voluntary isometric plantar flexion contractions at 4 different positions (0, 3, 6 and 8 cm; randomized). At position "0 cm", the foot was in full contact with the footplate; at the additional positions, the chair was moved forward. Body kinematics (VICON) and kinetics (HUMAC Norm, PEDAR) were captured synchronously during MVCs and RTDs. The results showed that the maximal exerted joint moment was significantly (p<0.01) increased by >32% from the 0-cm to 8-cm position (126 and 172 Nm, respectively); however, at the "6 cm" and "8 cm" positions, no significant difference was found. The joint rotation was significantly (p<0.01) reduced by >50% (from 15.5 to 7.1°; 0-8 cm). The maxRTD was only significantly higher at "6 cm" compared with the "0 cm" position. The time to reach maxRTD showed shorter tendencies for the "8 cm" position than for all other positions. The results indicate an underestimation of the plantar flexor maximal force potential with the current measuring technique. This could be critical in pre-post study designs where a 2-cm alteration in the chair position can induce an error of ~9% in the joint moment. The joint rotation could be reduced but not completely eliminated. For position standardization purposes, a pressure >220 kPa under the subject's foot is needed to achieve the maximal joint moment. We discussed the possible origins (fascicle length, neural drive) of the increased joint moment.
| S-EPMC6645493 | biostudies-literature
Project description:Knee flexion contracture is a clinically important complication that can be observed after trauma, after knee surgery, or as a result of osteoarthritis. When it is left untreated, knee shearing forces increase not only in the affected joint but also in the contralateral knee, leading to mechanical overload in both limbs. Conservative management is a first-line treatment option for extension deficits, but when it fails, surgical treatment is necessary. Open as well as arthroscopic techniques focus mainly on an anterior arthrolysis and a posterior capsular release. Until now, posterior capsulotomy involved either a medial posterior capsular release or medial and lateral posterior capsular releases. Our aim is to present the technique of arthroscopic complete posterior capsulotomy for knee flexion contractures.
| S-EPMC6262078 | biostudies-literature
Project description:A conventional 4-bar polycentric knee and solid ankle cushion heel foot (SACH foot) have been commonly used in developing countries. However, they cannot perform stance-phase knee flexion, which makes a person with an amputation walk unnaturally and with less stability. This research proposes a novel design of a 4-bar polycentric knee with stance-phase knee flexion ability (4BSF), which can perform both stance and swing-phase knee flexion, like able-bodied gait. In the proposed conceptual design, the instantaneous center of rotation (ICR) path is repositioned during the stance phase. The ICR was placed in front of the ground reaction force (GRF) to initiate knee flexion during the loading response. The prototype was validated by a single-subject pilot study at the Gait analysis laboratory. The results showed that a person with an amputation walks with stance-phase knee flexion using the proposed 4BSF. The maximum knee flexion angle is more than 10° during the stance phase. Furthermore, when the 4BSF was used with a SACH foot, the amount of time to achieve the foot flat was shorter, and the foot flat duration time was twice as long as the conventional 4-bar polycentric knee.
| S-EPMC10739707 | biostudies-literature
Project description:The objective of this study was to investigate biomechanics of TKA patients during high flexion. Six patients (seven knees) with a posterior-substituting TKA and weight-bearing flexion >130 degrees were included in the study. The six degree-of-freedom kinematics, tibiofemoral contact, and cam-post contact were measured during a deep knee bend using dual-plane fluoroscopy. The patients achieved average weight-bearing flexion of 139.5 +/- 4.5 degrees. Posterior femoral translation and internal tibial rotation increased steadily beyond 90 degrees flexion, and a sharp increase in varus rotation was noted at maximum flexion. Initial cam-post engagement was observed at 100.3 +/- 6.7 degrees flexion. Five knees had cam-post disengagement before maximum flexion. Lateral femoral condylar lift-off was found in five out of seven knees at maximum flexion, and medial condylar lift-off was found in one knee. Future studies should investigate if the kinematic characteristics of posterior-substituting TKA knees noted in this study are causative factors of high knee flexion.
| S-EPMC2903155 | biostudies-literature
Project description:Single-joint isometric and isokinetic knee strength assessment plays an important role in strength and conditioning, physical therapy, and rehabilitation. The literature, however, lacks absolute reference values. We systematically reviewed the available studies that assessed isometric knee strength. Two scientific databases (PubMed and PEDro) were searched for the papers that are published from the inception of the field to the end of 2019. We included studies that involved participants of both genders and different age groups, regardless of the study design, that involved isometric knee extension and/or flexion measurement. The extracted data were converted to body-mass-normalized values. Moreover, the data were grouped according to the knee angle condition (extended, mid-range, and flexed). A meta-analysis was performed on 13,893 participants from 411 studies. In adult healthy males, the pooled 95% confidence intervals (CI) for knee extension were 1.34-2.23Nm/kg for extended knee angle, 2.92-3.45Nm/kg for mid-range knee angle, and 2.50-3.06Nm/kg for flexed knee angle, while the CIs for flexion were 0.85-1.20, 1.15-1.62, and 0.96-1.54Nm/kg, respectively. Adult females consistently showed lower strength than adult male subgroups (e.g., the CIs for knee extension were 1.01-1.50, 2.08-2.74, and 2.04-2.71Nm/kg for extended, mid-range, and flexed knee angle condition). Older adults consistently showed lower values than adults (e.g., pooled CIs for mid-range knee angle were 1.74-2.16Nm/kg (male) and 1.40-1.64Nm/kg (female) for extension, and 0.69-0.89Nm/kg (male) and 0.46-0.81Nm/kg (female) for flexion). Reliable normative for athletes could not be calculated due to limited number of studies for individual sports.
| S-EPMC8554160 | biostudies-literature
Project description:BackgroundClinicians and patients lack an evidence-based framework by which to judge individual-level recovery following total knee arthroplasty (TKA) surgery, thus impeding personalized treatment approaches for this elective surgery. Our study aimed to develop and validate a reference chart for monitoring recovery of knee flexion following TKA surgery.MethodsRetrospective analysis of data collected in routine rehabilitation practice for patients following TKA surgery. Reference charts were constructed using Generalized Additive Models for Location Scale and Shape. Various models were compared using the Schwarz Bayesian Criterion, Mean Squared Error in 5-fold cross validation, and centile coverage (i.e. the percent of observed data represented below specified centiles). The performance of the reference chart was then validated against a test set of patients with later surgical dates, by examining the centile coverage and average bias (i.e. difference between observed and predicted values) in the test dataset.ResultsA total of 1173 observations from 327 patients were used to develop a reference chart for knee flexion over the first 120 days following TKA. The best fitting model utilized a non-linear time trend, with smoothing splines for median and variance parameters. Additionally, optimization of the number of knots in smoothing splines and power transformation of time improved model fit. The reference chart performed adequately in a test set of 171 patients (377 observations), with accurate centile coverage and minimal average bias (< 3 degrees).ConclusionA reference chart developed with clinically collected data offers a new approach to monitoring knee flexion following TKA.
| S-EPMC7376933 | biostudies-literature
Project description:Knee flexion contractures can arise from posterior capsule arthrofibrosis secondary to trauma, surgery, or chronic degenerative disease. This leads to limited knee extension and increased mechanical stress on the contralateral joint. Depending on the severity of the contracture, a treatment option may include surgical release of the posterior capsule. Arthroscopic posterior capsular release has been reported previously to have excellent resolution of extension deficits with minimal risk of postoperative complications. These techniques typically use an array of instruments, including shavers, biters, or scissors to perform arthrolysis of the posteromedial and posterolateral capsules. Our primary objective is to present a modified arthroscopic surgical technique for percutaneous treatment of knee flexion contracture using a spinal needle to perform a posterior capsule release.
| S-EPMC8355179 | biostudies-literature