Are Kinematics an Indicator of Outcome After Total Knee Arthroplasty?

BACKGROUND: A proportion of total knee arthroplasty (TKA) patients are dissatisfied postoperatively, particularly with their ability to perform higher-demand activities including deep-kneeling and step-up where kinematic parameters are more demanding. The purpose of this study was to examine the relationship between knee kinematics of step-up and deep-kneeling and patient-reported outcome measures following TKA. METHODS: Sixty-four patients were included at minimum 1-year follow-up. Participants performed a step-up and deep-kneeling task which was imaged via single-plane fluoroscopy. 3-dimensional prosthesis computer-aided design models were registered to the fluoroscopy, yielding in-vivo kinematic data. Associations between kinematics and patient-reported outcome measures, including Oxford Knee Score, American Knee Society Score, surgical satisfaction, and pain were assessed using log-transformed step-wise linear regressions. RESULTS: A higher total Oxford Knee Score was associated with more external rotation and more adduction at maximal flexion during kneeling and more external rotation and minimum flexion during step-up. Improved American Knee Society Score was associated with increased internal-external rotation during step-up. Improved surgical satisfaction was associated with greater maximum flexion and more external rotation at maximal flexion during deep-kneeling and more femoral internal rotation at terminal extension during step-up. An improved pain score was associated with greater maximum flexion and more femoral external rotation during deep-kneeling, as well as greater internal femoral rotation during step-up. CONCLUSION: The ability to move through full flexion/extension range and end-of-range rotation is important kinematic parameters that influence patient-reported outcome measures. Implant designs and postoperative rehabilitation should continue to focus on achieving these kinematic targets for enhanced outcomes after TKA.

The Influence of Platelet-Rich Fibrin on the Healing of Bone Defects after Harvesting Bone-Patellar Tendon-Bone Grafts.

Background and Objectives: A bone-patellar tendon-bone (BTB) autograft in anterior cruciate ligament reconstruction (ACLR) is still considered the gold standard among many orthopedic surgeons, despite anterior knee pain and kneeling pain being associated with bone defects at the harvest site. Bioregenerative products could be used to treat these defects, perhaps improving both the postoperative discomfort and the overall reconstruction. Materials and methods: During a year-long period, 40 patients were enrolled in a pilot study and divided into a study group, in which bone defects were filled with Vivostat® PRF (platelet-rich fibrin), and a standard group, in which bone defects were not filled. The main outcome was a decrease in the height and width of the bone defects, as determined by magnetic resonance imaging on the control exams during the one-year follow-up. The secondary outcomes included an evaluation of kneeling pain, measured with a visual analog scale (VAS), and an evaluation of the subjective knee scores. Results: The application of Vivostat® PRF resulted in a more statistically significant reduction in the width of the defect compared with that of the standard group, especially at 8 and 12 months post operation (p < 0.05). Eight months following the surgery, the study group's anterior knee pain intensity during kneeling was statistically considerably lower than that of the standard group (p < 0.05), and the statistical difference was even more obvious (p < 0.01) at the last follow-up. Each control examination saw a significant decrease in pain intensity in both the groups, with the values at each exam being lower than those from the prior exam (p < 0.01). A comparison of subjective functional test results 12 months post operation with the preoperative ones did not prove a statistically significant difference between the groups. Conclusions: The use of Vivostat® PRF reduces kneeling pain and accelerates the narrowing of bone defects after ACLR with a BTB graft, but without confirmation of its influence on the subjective knee score.

Anatomic versus Low Tibial Tunnel in Double-Bundle Posterior Cruciate Ligament Reconstruction: Clinical and Radiologic Outcomes with a Minimum 2-Year Follow-Up.

There is currently no consensus on the optimal placement of the tibial tunnel for double-bundle posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare the clinical and radiologic outcomes of double-bundle PCL reconstruction utilizing anatomic versus low tibial tunnels. We conducted a retrospective cohort study involving patients who underwent double-bundle PCL reconstruction between Jan 2019 and Jan 2022, with a minimum follow-up of 2 years (n = 36). Based on the tibial tunnel position on postoperative computed tomography, patients were categorized into two groups: anatomic placement (group A; n = 18) and low tunnel placement (group L; n = 18). We compared the range of motion, stability test, complications, and side-to-side differences in tibial posterior translation using kneeling stress radiography between the two groups. There were no significant differences between the groups regarding clinical outcomes or complication rates. No significant differences in the posterior drawer test and side-to-side difference on kneeling stress radiography (2.5 ± 1.2 mm in group A vs. 3.7 ± 2.0 mm in group L; p = 0.346). In conclusion, the main findings of this study indicate that both anatomic tunnel and low tibial tunnel placements in double-bundle PCL reconstruction demonstrated comparable and satisfactory clinical and radiologic outcomes, with similar overall complication rates at the 2-year follow-up.

The impact of bone graft type used to fill bone defects in patients undergoing ACL reconstruction with bone-patellar tendon-bone (BPTB) autograft on kneeling, anterior knee pain and knee functional outcomes.

PURPOSE: Multiple different materials are used for filling bone defects following bone-patellar tendon-bone (BPTB) graft ACL reconstruction surgery. The theoretical objective being to minimize kneeling pain, improve clinical outcomes and reduce anterior knee pain following surgery. The impact of these materials is assessed in this study. METHODS: A prospective monocentric cohort study was conducted from January 2018 to March 2020. There were 128 skeletally mature athletic patients who underwent ACL reconstruction using the same arthroscopic-assisted BPTB technique, with a minimum follow-up of two years identified in our database. After obtaining approval from the local ethics committee, 102 patients were included in the study. Patients were divided into three groups based on type of bone substitute. The Bioactive glass 45S5 ceramic Glassbone™ (GB), collagen and hydroxyapatite bone void filler in sponge form Collapat® II (CP), and treated human bone graft Osteopure®(OP) bone substitutes were used according to availability. Clinical evaluation of patients at follow-up was performed using the WebSurvey software. A questionnaire completed in the 2nd post-operative year included three items: The ability to kneel, the presence of donor site pain, and the palpation of a defect. Another assessment tool included the IKDC subjective score and Lysholm score. These two tools were completed by patients preoperatively, and postoperatively on three occasions (6 months, 1 year, and 2 years). RESULTS: A total of 102 patients were included in this study. In terms of Kneeling pain, the percentage of GB and CP patients' who kneel with ease were much higher than that of OP patients (77.78%, 76.5% vs 65.6%, respectively). All three groups experienced an important increase in IKDC and Lysholm scores. There was no difference in anterior knee pain between the groups. CONCLUSION: The use of Glassbone® and Collapat II® bone substitutes reduced the incidence of kneeling pain compared to Osteopure®. There was no influence of the bone substitute type on the functional outcome of the knee or on the anterior knee pain at two years of follow.

In Vivo three-dimensional kinematics of normal knees during sitting sideways on the floor.

BACKGROUND: The normal knee kinematics during asymmetrical kneeling such as the sitting sideways remains unknown. This study aimed to clarify in vivo kinematics during sitting sideways of normal knees. METHODS: Twelve knees from six volunteers were examined. Under fluoroscopy, each volunteer performed a sitting sideways. A two-dimensional/three-dimensional registration technique was used. The rotation angle, varus-valgus angle, anteroposterior translation of the medial and lateral sides of the femur relative to the tibia, and kinematic pathway in each flexion angle was evaluated. RESULTS: Bilateral knees during sitting sideways showed a femoral external rotation relative to the tibia with flexion (ipsilateral: 13.7 ± 3.5°, contralateral: 5.8 ± 6.8°). Whereas the ipsilateral knees showed valgus movement of 4.6 ± 2.5° from 130° to 150° of flexion, and the contralateral knees showed varus movement of -3.1 ± 4.4° from 110° to 150° of flexion. The medial side of the contralateral knees was more posteriorly located than that of the ipsilateral knees beyond 110° of flexion. The lateral side of the contralateral knees was more anteriorly located than that of the ipsilateral knees from 120° to 150° of flexion. In the ipsilateral knees, a medial pivot pattern followed by a bicondylar rollback was observed. In the contralateral knees, no significant movement followed by a bicondylar rollback was observed. CONCLUSION: Even though the asymmetrical kneeling such as sitting sideways, the knees did not display asymmetrical movement.

Correlation of patient-reported numbness around surgical scars with patient-reported outcome measures and joint awareness after knee replacement: a cohort study.

BACKGROUND: Knee replacement is a very effective and indispensable treatment option for end-stage knee arthritis, and the number of cases has been increasing worldwide. A replaced knee joint without patient joint awareness is thought to be the ultimate goal of artificial knees. Joint awareness reportedly correlates with patient satisfaction. Although numbness around a replaced knee is a minor but common problem, its effect on postoperative outcome is controversial. Joint awareness also is sensitive to subtle abnormalities of the joint, so it must be negatively affected by numbness. Although numbness is minor, it cannot be ignored to further improve knee replacement outcomes. This study investigated the relationship between patient-reported numbness and other patient-reported outcome measures (PROMs), including joint awareness, and kneeling. We developed a numbness score based on a 5-point Likert scale on frequency of numbness, with an intraclass correlation coefficient of 0.76 and higher scores indicating less numbness. METHODS: The numbness score, New Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score-12 (FJS-12), and other clinical and radiological data from 311 patients (394 primary knee replacements) were analyzed. Kneeling ability was evaluated by using kneeling-specific items in the KSS (KSS-Kneeling). RESULTS: No numbness was found in 170 knees (43.1%), and some degree of numbness was found in the remaining 224 knees (56.9%). The numbness score showed weak-to-moderate correlations with KSS-Symptoms (r = 0.44), KSS-Satisfaction (r = 0.41), KSS-Activities (r = 0.29), and all KOOS subscales (r = 0.23-0.44), and FJS-12 (r = 0.42). Multiple regression analyses suggested that midline incision positively affected the numbness score over the anteromedial incision (p = 0.04) and that a better numbness score (p = 0.001), male sex (p < 0.0001), and better postoperative knee flexion angle (0.04) positively affected kneeling. CONCLUSIONS: The numbness score positively correlated with PROMs and positively affected kneeling. Knee replacements performed via an anteromedial incision may be at higher risk for numbness.

Quantifying high flexion postures in occupational childcare as they relate to the potential for increased risk of knee osteoarthritis.

High knee flexion postures, despite their association with increased incidences of osteoarthritis, are frequently adopted in occupational childcare. This study sought to define and quantify high flexion postures typically adopted in childcare to evaluate any increased likelihood of knee osteoarthritis development. Through video analysis of eighteen childcare workers caring for infant, toddler, and preschool-aged children, eight high knee flexion postures were identified and quantified by duration and frequency. An analysis of postural adoption by task was subsequently performed to determine which might pose the greatest risk for cumulative joint trauma. Childcare workers caring for children of all ages were found to adopt kneeling and seated postures for extended durations and at elevated frequencies, exceeding proposed thresholds for incidences of knee osteoarthritis development. Structured activities, playing, and feeding tasks demanded the greatest adoption of high flexion postures and should be evaluated to minimise the potential childcare-related risks of osteoarthritis. Practitioner summary: High knee flexion postures (kneeling, squatting, etc.) have been associated with increased incidences of knee injury yet are commonly adopted in childcare. Childcare workers' postures were examined through video analysis revealing that proposed adoption thresholds for knee health are commonly exceeded when caring for children of all ages. Abbreviations: OA: osteoarthritis; WSIB: workplace safety insurance board; CAD: Canadian Dollar; DK: dorsiflexed kneeling; PK: plantarflexed kneeling; SAK: single arm supported kneeling; DAK: double arm supported kneeling; FS: flatfoot squatting; HS: heels up squatting; FLRS: floor sitting; SS: side sitting or leaning; STLS: stool sitting; BR: bending and reaching.

Influence of component design on in vivo tibiofemoral contact patterns during kneeling after total knee arthroplasty: a systematic review and meta-analysis.

PURPOSE: Modern TKR prostheses are designed to restore healthy kinematics including high flexion. Kneeling is a demanding high-flexion activity. There have been many studies of kneeling kinematics using a plethora of implant designs but no comprehensive comparisons. Visualisation of contact patterns allows for quantification and comparison of knee kinematics. The aim of this systematic review was to determine whether there are any differences in the kinematics of kneeling as a function of TKR design. METHODS: A search of the published literature identified 26 articles which were assessed for methodologic quality using the MINORS instrument. Contact patterns for different implant designs were compared at 90° and maximal flexion using quality-effects meta-analysis models. RESULTS: Twenty-five different implants using six designs were reported. Most of the included studies had small-sample sizes, were non-consecutive, and did not have a direct comparison group. Only posterior-stabilised fixed-bearing and cruciate-retaining fixed-bearing designs had data for more than 200 participants. Meta-analyses revealed that bicruciate-stabilised fixed-bearing designs appeared to achieve more flexion and the cruciate-retaining rotating-platform design achieved the least, but both included single studies only. All designs demonstrated posterior-femoral translation and external rotation in kneeling, but posterior-stabilised designs were more posterior at maximal flexion when compared to cruciate retaining. However, the heterogeneity of the mean estimates was substantial, and therefore, firm conclusions about relative behaviour cannot be drawn. CONCLUSION: The high heterogeneity may be due to a combination of variability in the kneeling activity and variations in implant geometry within each design category. There remains a need for a high-quality prospective comparative studies to directly compare designs using a common method. LEVEL OF EVIDENCE: Systematic review and meta-analysis Level IV.

In vivo length change of ligaments of normal knees during dynamic high flexion.

BACKGROUND: Few studies compared the length change of ligaments of normal knees during dynamic activities of daily living. The aim of this study was to investigate in vivo length change of ligaments of the normal knees during high flexion. METHODS: Eight normal knees were investigated. Each volunteer performed squatting, kneeling, and cross-leg motions. Each sequential motion was performed under fluoroscopic surveillance in the sagittal plane. The femoral, tibial, and fibular attachment areas of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), deep medial collateral ligament (dMCL), superficial medial collateral ligament (sMCL), and lateral collateral ligament (LCL) were determined according to osseous landmarks. After 2D/3D registration, the direct distance from the femoral attachment to the tibial or fibular attachment was measured as the ligament length. RESULTS: From 20° to 90° with flexion, the ACL was significantly shorter during cross-leg motion than during squatting. For the PCL, dMCL, sMCL, and LCL, there were no significant differences among the 3 motions. CONCLUSION: The ACL was shorter during cross-leg motion than during squatting in mid-flexion. This suggests that the ACL is looser during cross-leg motion than during squatting. On the other hand, the length change of the PCL, MCL, and LCL did not change even though the high flexion motions were different.

Percutaneous Nephrolithotomy under Local Infiltration Anesthesia in Kneeling Prone Position for a Patient with Spinal Deformity.

Urolithiasis, a common condition in patients with spinal deformity, poses a challenge to surgical procedures and anesthetic management. A 51-year-old Chinese male presented with bilateral complex renal calculi. He was also affected by severe kyphosis deformity and spinal stiffness due to ankylosing spondylitis. Dr. Li performed the percutaneous nephrolithotomy under local infiltration anesthesia with the patient in a kneeling prone position, achieving satisfactory stone clearance with no severe complications. We found this protocol safe and effective to manage kidney stones in patients with spinal deformity. Local infiltration anesthesia may benefit patients for whom epidural anesthesia and intubation anesthesia are difficult.

Kneeling difficulty is common following anterior cruciate ligament reconstruction with hamstring autograft and correlates with outcome measures.

INTRODUCTION: Patients frequently have discomfort or difficulty with kneeling following anterior cruciate ligament reconstruction (ACLR). This study aimed to report the prevalence of, and reasons for, kneeling difficulty after ACLR with a hamstring autograft; and to investigate the association between the degree of kneeling difficulty, presence of concurrent meniscal surgery, and clinical outcomes, including patient-reported outcome measures (PROMs) and functional tests. MATERIALS AND METHODS: A total of 104 patients undergoing ACLR with ipsilateral hamstring autograft were enrolled. Participants completed a kneeling difficulty questionnaire and other PROMs including the International Knee Documentation Committee (IKDC) questionnaire, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Cincinnati Knee Rating System (CKRS), the Lysholm Knee Scoring Scale (LKS), the Tegner Activity Scale (TAS), the 36-Item Short Form Health Survey (SF-36), and the Knee Outcome Survey (KOS). Patients were also assessed objectively via peak isokinetic knee extensor and flexor strength, range of movement (ROM), and functional hop tests. RESULTS: The prevalence of kneeling difficulty on the operated knee was 77% and 54% at 1 and 2 years after ACLR, respectively. Strong associations were observed between kneeling difficulty and PROMs, ranging from CKRS at 1 year of r = 0.403 (95% CI 0.228-0.553, p < 0.001) to KOS at 2 years of r = 0.724 (95% CI 0.618, 0.804, p < 0.001). No associations were observed with age, body mass index, or knee ROM measures. Weak-to-moderate associations were demonstrated with functional hop tests. The degree of kneeling difficulty did not differ with concurrent meniscal surgery. CONCLUSIONS: Kneeling difficulty occurs in as much as 77% of patients following ACLR with hamstring grafts at 1 year, and 54% at 2 years. This has a moderate-to-very strong association with patient-reported assessment of knee pain, symptoms, sport and recreation, and knee-related quality of life. There appears to be no association with patient age, BMI, time from injury to surgery, knee ROM, or concurrent meniscal surgery. LEVEL OF EVIDENCE: IV.

Development of a Full Flexion 3D Musculoskeletal Model of the Knee Considering Intersegmental Contact During High Knee Flexion Movements.

A musculoskeletal model of the right lower limb was developed to estimate 3D tibial contact forces in high knee flexion postures. This model determined the effect of intersegmental contact between thigh-calf and heel-gluteal structures on tibial contact forces. This model includes direct tracking and 3D orientation of intersegmental contact force, femoral translations from in vivo studies, wrapping of knee extensor musculature, and a novel optimization constraint for multielement muscle groups. Model verification consisted of calculating the error between estimated tibial compressive forces and direct measurements from the Grand Knee Challenge during movements to ∼120° of knee flexion as no high knee flexion data are available. Tibial compression estimates strongly fit implant data during walking (R2 = .83) and squatting (R2 = .93) with a root mean squared difference of .47 and .16 body weight, respectively. Incorporating intersegmental contact significantly reduced model estimates of peak tibial anterior-posterior shear and increased peak medial-lateral shear during the static phase of high knee flexion movements by an average of .33 and .07 body weight, respectively. This model supports prior work in that intersegmental contact is a critical parameter when estimating tibial contact forces in high knee flexion movements across a range of culturally and occupationally relevant postures.

Kneeling trunk kinematics during simulated sloped roof shingle installation.

Trunk musculoskeletal disorders are common among residential roofers. Addressing this problem requires a better understanding of the movements required to complete working tasks, such as affixing shingles on a sloped residential roof. We analyzed the extent to which the trunk kinematics during a shingling process are altered due to different angles of roof slope. Eight male subjects completed a kneeling shingle installation process on three differently sloped roof surfaces. The magnitude of the trunk kinematics was significantly influenced by both slope and task phase of the shingling process, depending on the metric. The results unequivocally point to roof slope and task phase as significant factors altering trunk kinematics. However, extension of the results to roofing workers should be done carefully, depending on the degree to which the study protocol represents the natural setting. Future studies on shingle installation in residential roofing should absolutely consider capturing a wider array of shingling procedures in order to encapsulate all the possible methods that are used due to the lack of a standardized procedure.

Knee osteoarthritis among airport baggage handlers: A prospective cohort study.

BACKGROUND: Knee osteoarthritis is a common and often disabling disorder, which has been related to knee-straining work. However, exposure response relations are uncertain and there are few prospective studies. We studied prospectively if incident knee osteoarthritis is associated with cumulative exposure as an airport baggage handler, lifting on average 5000 kg/d. METHODS: The study is based on the Copenhagen Airport Cohort, a historical cohort of male baggage handlers and a reference group of unskilled men from the greater Copenhagen area, followed from 1990 to 2012. Cumulative years of employment as a baggage handler was based on information from company employment and union registers. Outcome was first hospital admission with a discharge diagnosis of knee osteoarthritis and/or knee replacement, ascertained from the Danish National Patient Register. RESULTS: The cohort contained 3442 baggage handlers and 65 511 workers in the reference group. The unadjusted incidence rate ratio (IRR) of knee osteoarthritis increased steeply with cumulative years as a baggage handler. Although the exposure-response pattern became weaker and statistically nonsignificant (P ≈ .10) when adjusting for age, the risk of knee osteoarthritis was still increased in baggage handlers at the highest exposure level. Additional analyses showed that the association between age and osteoarthritis was stronger for baggage handlers (IRR = 2.09; 95% CI: 1.68-2.60) than for referents (IRR = 1.58; 95% CI: 1.53-1.63), indicating that knee osteoarthritis occurred at a younger age among baggage handlers than in the reference group. CONCLUSIONS: The results of this prospective cohort study support that long-term heavy lifting increases the risk of knee osteoarthritis.

Most Patients Can Kneel After Total Knee Arthroplasty.

BACKGROUND: Patients commonly report difficulty kneeling after total knee arthroplasty (TKA). The purpose of this study was to retrospectively assess patients' ability to kneel after TKA and to prospectively determine whether patients with reported difficulty can be taught to kneel. METHODS: Attempts were made to reach 307 consecutive TKAs in 255 adult patients who were 18-24 months after surgery. Patients were surveyed for their ability to kneel. Those who reported difficulty kneeling were offered participation in a kneeling protocol. At the conclusion of the protocol, participants were surveyed again for their ability to kneel. RESULTS: Of the 307 consecutive TKAs, 288 knees (94%) answered the survey. Of them, 196 knees (68%) could kneel with minor or no difficulty without any specific training. And 77 knees (27%) reported at least some difficulty kneeling and were eligible for participation in the protocol. Pain or discomfort was the most commonly reported reason for difficulty kneeling. Of these 77 knees, 43 knees (56%) participated. Thirty-six knees (84%) completed all or most of the protocol. All patients who completed all or most of the protocol were then able to kneel, and none reported significant difficulty kneeling. On average, participants improved 1.4 levels. CONCLUSION: In this cohort, 68% of knees could kneel after TKA without any specific training. Of those who had at least some difficulty kneeling, all who participated were able to kneel after a simple kneeling protocol, although 44% of eligible patients did not participate. This study suggests that kneeling should be included in postoperative TKA rehabilitation.

Cutaneous Hypesthesia and Kneeling Ability After Total Knee Arthroplasty: A Randomized Controlled Trial Comparing Anterolateral and Anteromedial Skin Incision.

BACKGROUND: Anterolateral skin incision can preserve the skin sensory of the anterior aspect of the knee and may improve kneeling ability after total knee arthroplasty (TKA). METHODS: This is a prospective, 2-arm, parallel-group, randomized, controlled trial involving patients scheduled for TKA. A total of 118 patients (162 knees) were randomly assigned to receive anterolateral skin incision or anteromedial skin incision with 1:1 treatment allocation. The surgical techniques other than skin incision were identical in both groups. The area of cutaneous hypesthesia was measured by a nonblinded assessor, and kneeling ability was evaluated by 2 blinded assessors at 12 months after surgery. RESULTS: The area of cutaneous hypesthesia was significantly smaller in the anterolateral skin incision group than the anteromedial skin incision group (3.0 ± 8.7 cm2 vs 10.6 ± 18.6 cm2; 95% confidence interval, 2.8-12.3 cm2; P = .0019). The rates of patients judged to be able to kneel were significantly higher in the anterolateral skin incision group by both assessors (81% vs 60%; P = .025 and 81% vs 59%; P = .015, respectively) with almost perfect agreement between the 2 assessors (kappa value = 0.94). There were no significant differences in terms of complication rate, including wound complications, between the 2 groups (P > .05). CONCLUSION: Compared with anteromedial skin incision, anterolateral skin incision may provide less cutaneous hypesthesia and better kneeling ability after TKA without increasing complication rate.

Effects of kneeling posture on chest compression during cardiopulmonary resuscitation in males.

AIMS AND OBJECTIVES: To study the effects of kneeling posture on chest compression during cardiopulmonary resuscitation (CPR) in males. BACKGROUND: Efficiency of chest compression during CPR affected millions of victims over the world. There are still no clear guidelines on kneeling posture that a rescuer should adopt in performing CPR. DESIGN: A self-controlled repeated-measures design was applied in this study. The efficiency of chest compression on a mannequin when three kneeling postures were adopted (farthest, self-adjusted and nearest) was analysed. METHODS: Eighteen participants with qualified first-aid certificate were recruited. Each participant had to perform three sessions of CPR, using one of the three different kneeling postures (i.e., farthest, self-adjusted and nearest) in each. They were performed in a random order chosen by drawing lots. Each session consisted of five cycles of CPR in each kneeling posture. Each cycle consisted of 30 strokes of chest compression performed within 18 s with a 4-s pause between consecutive cycles. Each session lasted for 2 min. The participants were allowed to rest for 10 min on a chair between sessions. Efficiency of chest compression was quantified by compression force, joint angle, heart rate and energy expenditure. After each session of CPR, the participants were surveyed about their rate of perceived exertion. RESULTS: Efficiency of chest compression in self-adjusted and nearest kneeling postures was significantly better than that of the farthest one. While the self-adjusted and nearest postures had the similar effect, most of the participants preferred self-adjusted kneeling posture because of lower rate of perceived exertion. CONCLUSION: The use of the self-adjusted and nearest kneeling postures during CPR in males resulted in more effective chest compression with lower perceived exertion, compared with the farthest kneeling posture. Both these positions can be objectively recommended to enhance the efficiency of chest compression and thereby increase the cardiac arrest survival rate. RELEVANCE TO CLINICAL PRACTICE: More consistent force and higher endurance could be achieved by performing CPR at self-adjusted kneeling posture.

Kneeling and standing up from a chair as performance-based tests to evaluate knee function in the high-flexion range: a randomized controlled trial comparing a conventional and a high-flexion TKA design.

BACKGROUND: We compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative. In addition, the patient's daily functioning, pain and satisfaction were quantified using questionnaires. METHODS: We randomly assigned 56 patients to receive either a conventional or a high-flexion TKA. Primary outcomes were maximum flexion angle and maximum thigh-calf contact measured during kneeling at 1 year post operatively. Secondary outcomes were the angular knee velocity and ground reaction force ratio measured during sit-to-stand performance tests, and questionnaires. RESULTS: At one year post-operative, maximum knee flexion during kneeling was higher for the high-flexion TKA group (median 128.02° (range 108-146)) compared to the conventional TKA group (119.13° (range 72-135)) (p = 0.03). Maximum thigh-calf contact force was higher for the high flexion TKA group (median 17.82 N (range 2.98-114.64)) compared to the conventional TKA group (median 9.37 N (range 0.33-46.58))(p = 0.04). The sit-to-stand tests showed a significantly higher angular knee velocity in the conventional TKA group (12.12 rad/s (95%CI 0.34-23.91); p = 0.04). There were no significant differences between groups in ground reaction force ratios and patient-reported outcome scores. CONCLUSION: Although no differences were found in patient-reported outcome scores, differences in performance-based tests were clearly apparent. Standing up from a chair at 90° of knee flexion appeared to be easier for the conventional group. The kneeling test revealed significantly higher weight-bearing knee flexion for the high-flex group. Hence, if kneeling is an important activity for a patient a high-flex design may be recommendable. TRIAL REGISTRATION: The study was retrospectively registered in ClinicalTrials.gov under identifier NCT00899041 (date of registration: May 11, 2009).

Peak activation of lower limb musculature during high flexion kneeling and transitional movements.

Few studies have measured lower limb muscle activation during high knee flexion or investigated the effects of occupational safety footwear. Therefore, our understanding of injury and disease mechanisms, such as knee osteoarthritis, is limited for these high-risk postures. Peak activation was assessed in eight bilateral lower limb muscles for twelve male participants, while shod or barefoot. Transitions between standing and kneeling had peak quadriceps and tibialis anterior (TA) activations above 50% MVC. Static kneeling and simulated tasks performed when kneeling had peak TA activity above 15% MVC but below 10% MVC for remaining muscles. In three cases, peak muscle activity was significantly higher (mean 8.9% MVC) when shod. However, net compressive knee joint forces may not be significantly increased when shod. EMG should be used as a modelling input when estimating joint contact forces for these postures, considering the activation levels in the hamstrings and quadriceps muscles during transitions. Practitioner Summary: Kneeling transitional movements are used in activities of daily living and work but are linked to increased knee osteoarthritis risk. We found peak EMG activity of some lower limb muscles to be over 70% MVC during transitions and minimal influence of wearing safety footwear.

A comparison of kneeling ability after lateral or midline incisions in total knee arthroplasty.

Kneeling is often impaired following total knee replacement. There is no clinical study comparing a lateral to a midline skin incision with regard to kneeling. Patients with a well-functioning total knee replacement enrolled in the trial. The participants with a lateral skin incision were matched with those with a standard midline incision. Twenty-two patients were enrolled in the study: 10 had a lateral skin incision, and 12 had a midline incision. Those with a lateral skin incision had a significantly higher Forgotten Joint Score than with a midline skin incision (Difference of Means Lateral vs Midline = 10.9 [p value 0.0098]), and an improved ability to kneel at 110 degrees of flexion (Kneeling Ability Test; Difference of Means Lateral vs Midline = 41.7 [p value 0.020]). These results suggest that a lateral skin incision may provide reduced joint awareness and improved kneeling ability. Further investigation with a randomised controlled trial is needed.