Search

Estimation of the knee joint strength by maximum voluntary isometric contraction (MVIC) is a common practice to assess strength, coordination, safety to return to work or engage in sports after an injury, and to evaluate the efficacy of treatment modalities and rehabilitation strategies. In this study, we utilize a previously validated coupled finite element‐musculoskeletal model of the lower extremity to explore the sensitivity of output measures (posterior cruciate ligament [PCL]/muscle/contact forces and passive moments) in knee MVIC flexion exercises at seated position. To do so, at three knee flexion angles (KFA), input measures (resistance moment and contribution moments of quadriceps and gastrocnemii) were varied at four levels each using the Taguchi design of experiment. Our findings reveal significant increases in PCL forces with KFA (p < 0.01), net MVIC moment (p < 0.01), and resistance moment of quadriceps (p < 0.01). In contrast, they drop at larger activity in gastrocnemii (p < 0.01). Tibiofemoral (TF) contact forces increase with the net MVIC moment (p < 0.01). The passive knee flexion moment, while highly dependent on the location at which computed, also increases with the net MVIC moment (p < 0.01). Changes in KFA, MVIC moment, and proportions thereof carried by quadriceps and/or gastrocnemii substantially affect biomechanics of the joint. Compared with level walking and stair ascent, slightly larger contact forces/stresses and much greater PCL forces are computed. This study improves our understanding of the knee joint behavior during MVIC in effective evaluation and rehabilitation interventions. Besides, it emphasizes the importance of positioning the joint center in model studies. [ABSTRACT FROM AUTHOR]

Background: Changes in graft length according to knee flexion and the ideal knee flexion angle at the time of graft fixation for posterolateral corner (PLC) reconstruction have yet to be clearly defined. Purposes: To investigate graft length changes according to knee flexion and determine the optimal graft fixation angle for knee flexion in PLC reconstruction. Study Design: Descriptive laboratory study. Methods: Ten healthy male volunteers underwent computed tomography at varying knee flexion angles (0°, 30°, 45°, 60°, and 90°). The Larson, LaPrade, Arciero, and Kim techniques were performed on 3-dimensional knee models reconstructed from the computed tomography scans. The lengths of each theoretically reconstructed graft were recorded and compared according to knee flexion angle changes. Results: In the Larson technique, the lengths of both arms of the sling were the longest at 30° of knee flexion but were not significantly different between 45° and 60° of knee flexion. In the LaPrade, Arciero, and Kim techniques, the length of the lateral collateral ligament arm at 30° of knee flexion was significantly longer than that at other knee flexion angles (P <.05), except at 0° of knee flexion. The length of the popliteus tendon arm in the LaPrade and Kim techniques, and the length of the popliteofibular ligament arm in the Arciero technique, increased with knee flexion and became the longest at 60° of knee flexion (P <.05). Conclusion: In the LaPrade, Arciero, and Kim techniques, the lengths of the lateral collateral ligament and popliteus complex component arms were greatest at 30° and 60° of knee flexion, respectively. In the Larson technique, the lengths of the anterior and posterior arms were greatest at 30° of knee flexion. The authors recommend securing each arm of the graft at the point of its greatest length. Clinical Relevance: This study presents in vivo data regarding graft length changes according to knee flexion and offers an optimal graft fixation angle for PLC reconstructions through various techniques. [ABSTRACT FROM AUTHOR]

In Older to study the influence of knee flexion angle and fabric elasticity on the knee deformation of trousers, nine subjects with similar stature were selected, and three kinds of knitted denim fabrics with similar basic physical properties but different elasticity were selected to make sample trousers. The three-dimensional scanner was used to obtain the knee marker area point cloud data of the subjects under different knee flexion angles and different lower limb wear (bare leg and wearing different elastic trousers), and the knee surface deformation rate was extracted. The analysis shows that there is a significant positive correlation between the knee deformation rate and the knee flexion angle when wearing different lower limbs, and there is a negative correlation between the knee deformation rate and the longitudinal elastic modulus of the fabric. The obtained regression models of knee skin deformation rate and knee flexion angle, knee pants deformation rate and knee flexion angle, and fabric elasticity can be used to guide the study of pants comfort and the selection of knee elastic fabrics. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL) injuries are common in sports involving jumping and rapid direction changes, often occurring in non-contact situations. The risk of ACL injury is evaluated by knee flexion and valgus angles; a small knee flexion angle combined with a large valgus angle increases the risk. Monitoring these angles during activities can help athletes recognize their ACL injury risk and adjust their movements. Traditional 3D motion analysis, used for measuring knee angles, is costly and impractical for daily practice. This study proposes a knee supporter with stretch sensors to estimate knee flexion and valgus angles in practice settings, evaluating ACL injury risk and notifying athletes of high-risk movements. The proposed device wirelessly transmits data from three stretch sensors placed on the device to a PC and uses machine learning to estimate the knee angles. The results of the evaluation experiments, conducted with data from five healthy male and female participants in their twenties, indicate that the estimation accuracy for the knee flexion angle, achieved by a model trained using a Random Forest Regressor (RFR) with data from individuals other than the target user, resulted in a Mean Absolute Error (MAE) of 8.86 degrees. For the knee valgus angle, a model trained with the user's own data using the RFR achieved a MAE of 0.81 degrees. [ABSTRACT FROM AUTHOR]

Background: The sagittal imbalance (SI) of spine triggers compensatory mechanisms (CMs) of lower extremity (LE) to restore trunk balance. These CMs can cause long‐period stress on the femur and may possibly alter the femoral morphology. This cross‐sectional observational study aimed to answer the following questions: (a) Do SI subjects exhibit greater femoral bowing compared to subjects with sagittal balance? (b) Are there associations between femoral bowing and CMs of LE in SI subjects? Methods: Subjects who underwent biplanar full body radiographs with the EOS imaging system between January 2016 and September 2021 were recruited. Sagittal parameters included T1‐pelvic angle (TPA), pelvic incidence (PI), pelvic tilt (PT), sacral slope, lumbar lordosis (LL), PI‐LL, and PT/PI ratio. LE parameters were femoral obliquity angle (FOA), knee flexion angle (KA), and ankle dorsiflexion angle. Femoral bowing was quantified as 3D radius of femoral curvature (RFC). Associations between 3D RFC and the radiographic parameters were analyzed. Results: A total of 105 subjects were included, classified into balance group (TPA < 14°, n = 40), SI group (TPA ≥ 14° and KA <5°, n = 30), and SI with knee flexion group (TPA ≥ 14° and KA ≥ 5°, n = 35). 3D RFC was significantly lower in SI with knee flexion group compared to the other two groups (both p < 0.001). Stepwise linear regression showed that age, SI and knee flexion, femoral length (FL), FOA, and KA were independent predictors for 3D RFC. Conclusion: Greater femoral bowing is observed in subjects with SI and knee flexion compared to the balanced population. CM parameters, including KA and FOA, are associated with 3D RFC. Further longitudinal study is needed to investigate the cause‐and‐effect relationship between SI, CMs of LE, and femoral bowing. [ABSTRACT FROM AUTHOR]

Background: Detailed knowledge of the anatomic course of the common peroneal nerve (CPN) is crucial for the surgical treatment of the posterolateral corner (PLC) of the knee. Purpose: To investigate the relationship of the CPN to the PLC of the knee at different flexion angles. Study Design: Descriptive laboratory study. Methods: Ten healthy volunteers were recruited to undergo magnetic resonance imaging (MRI) of the knee joint at knee flexion angles of 0°, 30°, 60°, 90°, and 120°. MRI scans at 3 levels (joint line, tibial cut, and fibular tip) were evaluated to determine (1) the distance from the CPN to the PLC and (2) the distances between the CPN and the anterior-posterior and medial-lateral tibial axes. A 3-dimensional model of the knee joint created from MRI scans of a single participant was used to simulate the creation of a fibular tunnel for PLC reconstruction and investigate the relationship between the CPN, fibular tunnel, and guide pin. Results: The CPN moved posteromedially with increased knee flexion angles. As the flexion angle increased, the distances from the CPN to the anterior-posterior axis and the PLC increased significantly, while the distance to the medial-lateral axis decreased significantly at all 3 measurement levels. The distances between the CPN and anterior-posterior and medial-lateral axes were significantly different among the different knee flexion angles at the different measurement levels. There were no significant differences in the mean distance from the CPN to the posterolateral border of the tibial plateau between 0° and 30° of flexion at the fibular tip level (P =.953). There were statistically significant differences in the distance from the CPN to the PLC of the tibial plateau at the different measurement levels. The 3-dimensional model demonstrated that the position of the CPN relative to the guide pin and the bone tunnel undergoes changes during knee flexion. Conclusion: Changes in the knee flexion angle produced corresponding changes in the course of the CPN on the posterolateral aspect of the knee joint. The CPN moved posteromedially with increased knee flexion angles. Clinical Relevance: Increasing the knee flexion angle during PLC reconstruction can effectively avoid direct injury of the CPN. [ABSTRACT FROM AUTHOR]

Abstract Background The sagittal imbalance (SI) of spine triggers compensatory mechanisms (CMs) of lower extremity (LE) to restore trunk balance. These CMs can cause long‐period stress on the femur and may possibly alter the femoral morphology. This cross‐sectional observational study aimed to answer the following questions: (a) Do SI subjects exhibit greater femoral bowing compared to subjects with sagittal balance? (b) Are there associations between femoral bowing and CMs of LE in SI subjects? Methods Subjects who underwent biplanar full body radiographs with the EOS imaging system between January 2016 and September 2021 were recruited. Sagittal parameters included T1‐pelvic angle (TPA), pelvic incidence (PI), pelvic tilt (PT), sacral slope, lumbar lordosis (LL), PI‐LL, and PT/PI ratio. LE parameters were femoral obliquity angle (FOA), knee flexion angle (KA), and ankle dorsiflexion angle. Femoral bowing was quantified as 3D radius of femoral curvature (RFC). Associations between 3D RFC and the radiographic parameters were analyzed. Results A total of 105 subjects were included, classified into balance group (TPA

Purpose: Restricted kinematically aligned total knee arthroplasty (rKA‐TKA) may not restore the constitutional varus alignment in most patients with knee osteoarthritis. This study aimed to investigate (1) the extent to which constitutional lower limb alignment can be restored by rKA‐TKA using an anatomically designed implant and (2) which lower limb alignment parameters are associated with patient‐reported outcome measures (PROMs). Methods: This study included 60 patients who underwent rKA‐TKA using an anatomically designed implant. Radiographic alignment parameters, including mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), coronal hip–knee–ankle angle (HKA), coronal joint line obliquity (JLO), posterior tibial slope (PTS), single‐leg standing knee flexion angle (KFA), sagittal JLO, and arithmetic HKA (aHKA), were evaluated preoperatively and postoperatively. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) was used for clinical evaluation. Results: The mLDFA, MPTA, and aHKA showed no significant differences before and after surgery. Coronal HKA and PTS have significantly changed from 8.1 ± 8.7° and 9.9 ± 8.6° preoperatively to 3.5 ± 3.1° and 2.5 ± 2.0° postoperatively, respectively (p < 0.001 for each comparison). The postoperative WOMAC total score was significantly correlated with the KFA (r = 0.4063, p = 0.0034) and sagittal JLO (r = −0.3435, p = 0.0157). Postoperative KFA is a causal factor for the increased postoperative WOMAC total score (r = 1.416, 95% confidence interval: 0.491–2.342, p = 0.003). Conclusion: rKA‐TKA using an anatomically designed implant can restore constitutional coronal lower limb alignment, while postoperative KFA and sagittal JLO were associated with poor PROMs. Care should be taken for the postoperative KFA because it is a risk factor for poor PROMs. Level of Evidence: Level III, case–control study. [ABSTRACT FROM AUTHOR]

PURPOSE OF THE STUDY Postoperative pain after total knee arthroplasty (TKA) is severe because of bone and soft tissue trauma during the surgery and is difficult to control with oral analgesics. The primary aim of the study was to investigate the effects of the local infiltration anesthesia (LIA) method on postoperative analgesia quality and opioid consumption in patients undergoing TKA. The secondary aims were to evaluate knee flexion angle, side effects, and patient satisfaction. MATERIAL AND METHODS Total 40 patients, who underwent unilateral TKA surgery under spinal anesthesia were included in the prospective randomized study. Patients who underwent patient-controlled intravenous analgesia (PCA) (Group A) or LIA + PCA (Group B), were divided into two groups, randomly. For LIA application, 0.25% bupivacaine solution 150 mg in 60 ml volume was used. The postoperative pain was evaluated in 48th hour after the recovery of motor block, and during exercise at 24, 36, and 48 hours by using the visual analogue scale (VAS). An additional morphine was administered with the PCA device when VAS ≥ 4. The total amount of morphine consumption and the side effects were recorded. The knee flexion joint angles at the 48th hour and the patients’ satisfaction was recorded. RESULTS Resting VAS values were lower in Group B in the first 24 hours (p<0.05). However, the 36th and 48th hour measurements were not different in groups. The exercises VAS values and the total morphine consumption were significantly higher in Group A at 24, 36 and 48 hours. The knee flexion joint angles in Group B were higher than Group A in terms of 48th hour. The incidence of side effects was not different in the two groups. Patients’ satisfaction was higher in the PCA+ILA group (p<0.05). DISCUSSION In many studies the periarticular injection with multimodal drugs has been shown to reduce the requirements for analgesia, with no apparent risks, following TKA, similar to our results. LIA reduced postoperative opioid use and increased exercise tolerance. CONCLUSIONS In our study, we found that LIA reduced pain scores and opioid consumption during rest and exercise after TKA operation. For TKA patients where post-operative exercise is particularly important, we recommend the easy-to-use LIA method for a pain-free and unrestricted postoperative period. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL) injuries are common in sports involving jumping and rapid direction changes, often occurring in non-contact situations. The risk of ACL injury is evaluated by knee flexion and valgus angles; a small knee flexion angle combined with a large valgus angle increases the risk. Monitoring these angles during activities can help athletes recognize their ACL injury risk and adjust their movements. Traditional 3D motion analysis, used for measuring knee angles, is costly and impractical for daily practice. This study proposes a knee supporter with stretch sensors to estimate knee flexion and valgus angles in practice settings, evaluating ACL injury risk and notifying athletes of high-risk movements. The proposed device wirelessly transmits data from three stretch sensors placed on the device to a PC and uses machine learning to estimate the knee angles. The results of the evaluation experiments, conducted with data from five healthy male and female participants in their twenties, indicate that the estimation accuracy for the knee flexion angle, achieved by a model trained using a Random Forest Regressor (RFR) with data from individuals other than the target user, resulted in a Mean Absolute Error (MAE) of 8.86 degrees. For the knee valgus angle, a model trained with the user’s own data using the RFR achieved a MAE of 0.81 degrees.

The purpose of this study was to examine the relationship between the amount of change in medial longitudinal arch height of the foot (MLA) on static weight bearing and the amount of change in knee flexion angle during single-leg landing. The subjects were 22 healthy adults comprising 11 males and 11 females. In evaluation of the foot alignment, distance from the floor to the most prominent part of the navicular tuberosity was measured in the sitting and standing positions, and the difference in the distance between the two positions was defined as amount of change in MLA. In the kinematic analysis of landing, markers were attached to the bony landmarks in the lower limbs, single-leg landing from a 30-cm-high platform. And then, knee flexion angle was measured on the video image. The analysis of the obtained results showed a significant negative correlation between the amount of change in MLA and change in knee flexion angle during single-leg landing. Although there have been studies reporting the effect of MLA on knee valgus angle during landing, the results of this study suggest that MLA also relates to the amount of change in the knee flexion angle in landing. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of different knee flexion angles at lithotomy position on deep venous blood flow of lower limb in patients undergoing radical cervical cancer resection. Methods A total of 120 patients undergoing radical cervical cancer resection in this hospital from May to December 2022 were selected and divided into the observation group and the control group by random number table method, with 60 cases in each group. Lithotomy position was adopted in all cases. The knee flexion angle of the control group was 110°, and the knee flexion Angle of the observation group was 130°. The changes of blood flow velocity difference between femoral vein and popliteal vein, vascular diameter and coagulation index were observed before and after surgery in the two groups. Results The blood flow velocity difference of left and right femoral vein and popliteal vein in the observation group before and after surgery was smaller than that of the control group, and the vascular diameter was larger than that of the control group, the differences were statistically significant (P <0. 001). The activated partial thromboplastin time (APTT) and prothrombin time (PT) 24 h after operation in the observation group were higher than those in the control group, and the D-dimer (D-D) value was lower than that in the control group, with all statistical significance (P <0. 001). Conclusion In the postural nursing of patients undergoing radical cervical cancer resection, knee flexion at lithotomy position of 130° shows smaller changes in vascular diameter, more stable hemodynamic, and smaller changes in D-D values, compared with 110°, which is worthy of promotion and application [ABSTRACT FROM AUTHOR]

Toe-out gait has been proposed as a conservative treatment to reduce medial tibiofemoral joint loading. However, patellofemoral joint loading during toe-out gait is not yet understood. Does the toe-out gait modification affect patellofemoral joint loading? Sixteen healthy adults were enrolled in this study. The natural gait and toe-out gait were measured using a three-dimensional motion analysis and a force plate. The knee flexion angle and external knee flexion moment during the stance phase were calculated. Thus, dynamic knee joint stiffness, a proxy of patellofemoral joint loading, was defined as a linear regression of the knee flexion moment and knee flexion angle during the early stance. Additionally, the peak patellofemoral compressive force during the early stance was calculated using a musculoskeletal simulation. A paired t -test was used to compare these biomechanical parameters during the natural gait and toe-out gait. The toe-out gait significantly increased the peak patellofemoral compressive force (mean difference = 0.37 BW, P = 0.017) and dynamic knee joint stiffness (mean difference = 0.07%BW*Ht/°, P = 0.001). The 1st peak of the knee flexion moment also significantly increased in the toe-out gait (mean difference = 1.01%BW*Ht, P = 0.003); however, the knee flexion angle did not change significantly (initial contact: mean difference = 1.7°, P = 0.078; peak: mean difference = 1.3°, P = 0.224). Toe-out gait increased the patellofemoral compressive force and dynamic knee joint stiffness because of increasing knee flexion moment, but not the knee flexion angle. When the toe-out gait is adapted, clinicians should pay attention to an increase in the patellofemoral joint loading. • Toe-out gait increased patellofemoral compressive force compared with natural gait. • Toe-out gait increased dynamic knee joint stiffness compared with natural gait. • Toe-out gait increased the knee flexion moment, but not the knee flexion angle. • Clinicians should pay attention to increases in patellofemoral joint loading. [ABSTRACT FROM AUTHOR]

Context: This study compared landing impact between 3 landing heights on 3 landing surfaces by quantifying vertical ground reaction force (vGRF) profile and knee joint angle., Design: Crossover., Methods: Nineteen healthy male college Taekwondo (TKD) Gyeokpa players (age: 20.7 [2.6] y, height: 1.73 [0.05] m, mass: 65.5 [7.1] kg, and athletic careers: 5.9 [3.2] y) performed 2-leg landings from 3 different heights (0.45, 0.90, and 1.35 m) on 3 different surfaces (uncovered force plates on the ground, a 2-cm thick TKD or a 14-cm thick sponge mat over the force plates). Peak vGRF, time to peak vGRF, and knee joint angle in the dominant leg were analyzed using analysis of variance and functional data analysis (α = .05)., Results: There was a height by surface interaction in peak vGRF (F4,144 = 2.54, P = .04) and time to peak vGRF (F4,144 = 7.62, P < .0001), but not for knee joint angle (F4,144 = 0.51, P = .73). Increased peak vGRF and shortened time to peak vGRF were observed as landing height increased on each landing surface (P < .0001 for all tests). Functional data analysis revealed that landing on the TKD mat increased vGRF by 0.4× body weight (P < .0001) at a landing height of 0.90 m or higher, whereas landing on the sponge mat reduced vGRF (<0.9× body weight), delayed time to reach peak vGRF (<30 ms, P < .0001), and maintained knee flexion angle (<10.3°, P < .01), compared with landing on the ground., Conclusions: The TKD mat was ineffective in reducing the landing impact as similar landing biomechanics were observed between landing on the ground and the TKD mat. We recommend the use of the sponge mat to reduce landing impact as it attenuated vGRF, delayed time to reach peak vGRF, and maintained sagittal plane landing posture, as compared with landing on the ground and the TKD mat.

Objective To confirm whether a novel sagittal patellar angle linear equation used for evaluating patellar height by calculating expected sagittal patellar angle (SPA) at any degree of knee flexion angle is suitable for patients older than 17 years and its reliability compared with other commonly used methods. Methods From September 2016 to September 2019, a total number of 202 consecutive outpatients' knee lateral X‐ray radiographs were retrospectively measured and evaluated using a recently proposed linear equation Y = 1.94 + 0.74 × knee flexion(KF) angle. Patients were divided by ages into ayounger group, whose ages were between 17–49 years, and an older group, whose ages were older than 49 years, which has not been validated in the original study. Parameters such as KF, SPA, patella and patella tendon length and so on were measured on computer with picture archiving and communication system by two independent observers at an interval of 1 month. Insall‐Salvati (IS) index, Caton‐Deschamps (CD) index and Y value, correlation coefficients were calculated and compared using SPSS 22.0 software. Results In the younger group, 143 patients (165 knees) were included, ages were 17–49 (31.62 ± 11.38) years, males/females were 70 (48.95%)/73 (51.05%), left knees/right knees were 83 (50.30%)/82 (49.70%), mean value of Y was 31.50° ± 10.07°, and SPA was 34.38° ± 12.38°, mean value of IS was 1.06 ± 0.17, mean value of CD was 1.04 ± 0.18. While in older group, 59 patients (78 knees) were included, ages were 50–60 (mean 54.61 ± 2.99) years, there were 32 males (54.24%) and 27 females (45.76%), 42 knees were left (53.85%) and 36 knees were right (46.15%), mean values of Y and SPA were 25.90° ± 11.55° and 29.36° ± 14.22°, mean IS index in older group was 1.06 ± 0.18, mean CD index was 1.00 ± 0.16. Intra‐ and inter‐observer reliabilities of Y in younger and older groups were 0.999, 0.999, 1.000 and 0.999, meaning high reliability and reproducibility, but low Pearson's correlation coefficients with IS and CD index were showed as −0.213 and − 0.216 in younger group and − 0.113 and − 0.316 in older group. Conclusions In patients older than 17 years, the linear equation Y = 1.94 + 0.74 × KF is a reliable and practical method to evaluate SPA regardless of age and knee flexion angle, but has weak correlation coefficients with the IS and CD index.

Abstract Background Diagnosing patellofemoral instability disorders correctly, weight-bearing MRI (WB-MRI) has become an option. Aiming for a best possible accuracy in displaying potentially underlying causes, the named MRI modalities were sporadically even investigated in different knee flexion angles. However, despite confirmed MRI-outcome-differences between WB-MRI and non-WB-MRI, none of the described MRI modalities have so far established themselves. Mainly this is due to an unfeasibility in daily clinical routine in regard to time and economic aspects. Thus, we intended to evaluate an additional but reduced patellofemoral MR-imaging solely in a relevant 20° of knee flexion under WB- and non-WB-MRI conditions. Methods Seventy-three subjects with and without patellofemoral instability were investigated under supine as well as under WB-MRI conditions in a 20° of knee flexion angle. Patellofemoral risk indices in the sagittal plane (Insall-Salvati-Index, Caton-Deschamps-Index, Patellotrochlear Index) and the axial plane (Patella tilt of Fulkerson and Sasaki) were detected and compared between the different MRI conditions. Significance, reliability and Cohen’s effect size was calculated. Results Nearly all assessed indices showed significant differences between patients and controls in the different MRI positions. Comparing pairwise, all measured indices failed to show significant differences between the two MRI positions. However, patella tilt angles of the patient group showed an elevation from supine to WB-MRI (14.00 ± 7.54° to 15.97 ± 9.10° and 16.34 ± 7.84° to 18.54 ± 9.43°). Here, Cohen’s d showed small to medium effects between supine and WB-MRI. Conclusion In comparison to standard MRI in supine position, axial risk indices seem to be accentuated under WB-MRI and a knee flexion angle of 20°. In particular, symptomatic cases with inconspicuous conventional MRI imaging, additional MRI imaging only in the axial plane in a 20° of knee flexion could be beneficious and useful in clinical daily routine.

Abstract Background This study aims to elucidate and compare the relationship between the knee flexion angle and patient-reported outcome measures (PROM) in both non-weight-bearing (NWB) and weight-bearing (WB) conditions. Methods This retrospective cohort study included 61 knees (47 patients) who underwent total knee arthroplasty. The knee flexion angle was measured by three conditions: NWB in manual goniometer, NWB in fluoroscopic three-dimensional (3D) analysis and WB in the fluoroscopic 3D analysis. The PROM was evaluated by postoperative 2011 Knee Society Score (2011 KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Correlations between the knee flexion angle and PROM was analyzed using Spearman’s correlation coefficient. Additionally, whether the angular difference between NWB and WB correlated with the PROM or not was evaluated. Results The NWB knee flexion angle in a goniometer, NWB in 3D analysis, and WB in 3D analysis were 124.6° ± 8.4°, 118.0° ± 10.5°, and 109.5° ± 13.3°, respectively. The angular difference was 8.5° ± 12.8°. No PROM correlation existed in NWB using a goniometer. Moreover, significant positive correlations in 2011 KSS symptoms (r = 0.35) and 2011 KSS functional activities (r = 0.27) were noted in NWB using 3D analysis. Significant positive correlations existed in 2011 KSS symptoms (r = 0.32), 2011 KSS functional activities (r = 0.57), KOOS pain (r = 0.37), KOOS activity of daily living (ADL; r = 0.45), KOOS sports (r = 0.42), and KOOS quality of life (r = 0.36) in WB using 3D analysis. Significant negative correlations were noted in 2011 KSS functional activities (r = − 0.45), KOOS ADL (r = − 0.30), and KOOS sports (r = − 0.38) in angular difference. Conclusions The WB knee flexion angle better correlated with PROM compared with NWB by evaluation of 3D analysis. The larger the angular difference existed between NWB and WB, the lower the PROM score.

Background: Anterior cruciate ligament (ACL) injury cause great disability for athlete. Recent focus of ACL injury management is on prevention by identifying the risk factors. Most of basketball injury mechanism is non-contact, related to landing process with small knee flexion angle. Muscle activation and its ratio, which control movement pattern in sagittal plane, are said to play a role in dynamic movement such as landing. Aims: The purpose of this study is to analyze the correlation between muscles activation and their activation ratio of quadriceps, hamstring, tibialis anterior and gastrocnemius with knee flexion angle of basketball athlete while performing double-leg landing task. Material and methods: This study was an observational analytic, cross sectional study. Study subjects was basketball athletes age 16 – 25 years in Surabaya. Measurements of knee flexion angle done with digital measurements of reflective marker, and muscle activation was measured with sEMG while performing double-leg landing task. Result: There was no significant correlation between maximum knee flexion angle and muscle activation of quadriceps (p=0,562), hamstring (p=0,918), tibialis anterior (p=0,394) and gastrocnemius (p=0,419). There was also no significant correlation between maximum knee flexion angle and the muscle activation ratio of quadriceps-hamstring (p=0,347), quadriceps-tibialis (p=0,139), quadriceps-gastrocnemius (p=0,626), hamstring-tibialis anterior (p=0,365), hamstring-gastrocnemius (p=0,867), and tibialis anterior-gastrocnemius (p=0,109). Conclusions: There was no correlation between muscle activation and muscle activation ratio of quadriceps, hamstring, tibialis anterior and gastrocnemius with maximum knee flexion angle in basketball athlete while performing double-leg landing task.

Background: Patient-reported satisfaction following total knee arthroplasty (TKA) can be affected by various factors. This study aimed to assess patient satisfaction rates and identify factors related to patients, surgery, and postoperative knee motion associated with satisfaction in posterior-stabilized TKA among Asian patients., Methods: A retrospective cross-sectional study was conducted in patients with primary osteoarthritis who underwent TKA and had a follow-up period of over 2 years. Patient satisfaction was measured using a 5-point Likert scale, and the patients were divided into satisfied and dissatisfied groups. The factors potentially affecting satisfaction were collected, including demographics, comorbidities, surgical options, and knee motion. Univariate and multivariate regression analyses were performed., Results: Of the 858 patients included, 784 (91.4%) were satisfied and 74 (8.6%) were dissatisfied. Fixed-bearing implants and higher postoperative knee flexion angles were associated with satisfaction (odds ratio [OR], 2.366; p = 0.001 and OR, 1.045; p < 0.001, respectively), whereas cerebrovascular disease was related to dissatisfaction (OR, 0.403; p = 0.005). The regression model demonstrated moderate predictability ( R 2 = 0.112)., Conclusions: Fixed-bearing implants and higher postoperative knee flexion angles were associated with patient satisfaction following TKA, whereas cerebrovascular disease was associated with dissatisfaction. The identification of these factors could help improve surgical outcomes and patient satisfaction following TKA., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2024 by The Korean Orthopaedic Association.)

Background: The primary aim of this study was to investigate the association between the posterior longitudinal overhang in the femoral condyle (PLOF) in medial-pivot total knee arthroplasty (TKA) and a change in knee flexion angle (change in flexion)., Methods: This retrospective cohort study included 148 knees undergoing medial-pivot TKA for medial knee osteoarthritis. The primary outcome was the change in flexion (c-flexion) preoperatively and 1-year postoperatively. The component positions were evaluated using 3-dimensional measurements, where the PLOF was measured for each medial and lateral femoral condyle. The secondary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index scores taken preoperatively and 2 years postoperatively. A multivariate regression analysis was performed to determine predictors of c-flexion and risk factors for negative c-flexion (less than 0°). Furthermore, a receiver operating characteristic curve was utilized to determine the threshold for negative c-flexion., Results: The mean c-flexion was -3.2° ± 8.7, and lateral PLOF was significantly associated with c-flexion (β = -0.52; P < 0.001). Larger preoperative flexion angles (odds ratio, 1.10; P < 0.001) and larger lateral PLOF (odds ratio, 1.69; P = 0.001) were risk factors for negative c-flexion, with thresholds of 129° and 1.1 mm, respectively (sensitivity, 0.79; specificity, 0.72). Additionally, patients who had negative c-flexion (n = 91) demonstrated less improvement in preoperative and 2-year postoperative Western Ontario and McMaster Universities Osteoarthritis Index stiffness subscores than patients who had positive c-flexion (0° or more; n = 57) (P = 0.01)., Conclusions: A larger lateral PLOF was associated with decreased and negative c-flexion after medial-pivot TKA. Patients who had negative c-flexion demonstrated less improvement in knee stiffness. Surgical strategies aimed at minimizing lateral PLOF may enhance postoperative knee flexion and overall patient outcomes in medial-pivot TKA., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: To confirm whether a novel sagittal patellar angle linear equation used for evaluating patellar height by calculating expected sagittal patellar angle (SPA) at any degree of knee flexion angle is suitable for patients older than 17 years and its reliability compared with other commonly used methods. Methods: From September 2016 to September 2019, a total number of 202 consecutive outpatients' knee lateral X‐ray radiographs were retrospectively measured and evaluated using a recently proposed linear equation Y = 1.94 + 0.74 × knee flexion(KF) angle. Patients were divided by ages into ayounger group, whose ages were between 17–49 years, and an older group, whose ages were older than 49 years, which has not been validated in the original study. Parameters such as KF, SPA, patella and patella tendon length and so on were measured on computer with picture archiving and communication system by two independent observers at an interval of 1 month. Insall‐Salvati (IS) index, Caton‐Deschamps (CD) index and Y value, correlation coefficients were calculated and compared using SPSS 22.0 software. Results: In the younger group, 143 patients (165 knees) were included, ages were 17–49 (31.62 ± 11.38) years, males/females were 70 (48.95%)/73 (51.05%), left knees/right knees were 83 (50.30%)/82 (49.70%), mean value of Y was 31.50° ± 10.07°, and SPA was 34.38° ± 12.38°, mean value of IS was 1.06 ± 0.17, mean value of CD was 1.04 ± 0.18. While in older group, 59 patients (78 knees) were included, ages were 50–60 (mean 54.61 ± 2.99) years, there were 32 males (54.24%) and 27 females (45.76%), 42 knees were left (53.85%) and 36 knees were right (46.15%), mean values of Y and SPA were 25.90° ± 11.55° and 29.36° ± 14.22°, mean IS index in older group was 1.06 ± 0.18, mean CD index was 1.00 ± 0.16. Intra‐ and inter‐observer reliabilities of Y in younger and older groups were 0.999, 0.999, 1.000 and 0.999, meaning high reliability and reproducibility, but low Pearson's correlation coefficients with IS and CD index were showed as −0.213 and − 0.216 in younger group and − 0.113 and − 0.316 in older group. Conclusions: In patients older than 17 years, the linear equation Y = 1.94 + 0.74 × KF is a reliable and practical method to evaluate SPA regardless of age and knee flexion angle, but has weak correlation coefficients with the IS and CD index. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of countermovement depth on the magnitude of the countermovement jump (CMJ) derived reactive strength index modified (RSImod), and to compare the RSImod between the CMJ performed with a self-preferred knee flexion angle (CMJpref) and the CMJ performed from a pre-determined knee flexion angle (CMJrefer) with the countermovement depth more similar to the CMJpref. Sixteen subjects (11 males and 5 females; age 25.1 ± 6.3 years, body mass 69.7 ± 10.2 kg, body height 172.9 ± 8.1 m) randomly performed in a single session the CMJpref and CMJs from five pre-determined knee flexion angles (60°, 75°, 90°, 105°, and 120°). Our results showed that lower knee flexion angles were generally associated with greater RSImod values with the CMJ performed at 60° showing the greatest RSImod (P ≤ 0.049; effect size [ES] range = 0.19–0.63). The greatest RSImod for the CMJ performed at 60° was caused by the proportionally lower values of the time to take-off (ES range = 0.65–1.91) compared to the decrease observed in jump height (ES range = 0.11–0.25). The RSImod was higher for the CMJpref compared to the CMJrefer (P < 0.001; ES = 0.34) due to a higher jump height (P = 0.021; ES = 0.14) and reduced time to take-off (P < 0.001; ES = 0.85). These results indicate that practitioners should be careful when interpreting an individual's changes in RSImod when the countermovement depth is not similar across the testing sessions. However, since the use of pre-determined knee flexion angles negatively impacts the RSImod, we encourage practitioners to use the CMJpref but only compare the RSImod when CMJs are performed using consistent countermovement depths. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to investigate the effect of diabetes mellitus (DM) on knee extension/flexion angle and its early clinical course after total knee arthroplasty (TKA). Methods: Patients who received TKA were retrospectively divided into two groups based on haemoglobinA1c level; the DM group (23 knees) and the control group (23 knees matched for baseline characteristics). The passive knee extension/flexion angle, gait speed and Japanese Orthopaedic Association (JOA) score were evaluated preoperatively and at 1, 6 and 12 months post-operatively. Results: There was no significant difference in the passive knee flexion angle at 1 and 6 months postoperatively between the groups (p=.302, p=.160, respectively). The passive knee flexion angle was significantly lower at 12 months postoperatively in the DM group than the control group (p=.014). In the DM group, the passive knee flexion angle at 6 and 12 months significantly decreased compared with that at 1 month postoperatively (p=.021, p<.001, respectively). There were no significant differences in the knee extension angle, gait speed and JOA score between the groups. Conclusion: Patients with DM are likely to experience passive knee flexion angle exacerbating from 1 to 6 months after TKA. [ABSTRACT FROM AUTHOR]

Background and Objectives: Leg extension angle is important for increasing the propulsion force during gait and is a meaningful indicator for evaluating gait quality in stroke patients. Although leg extension angle during late stance might potentially also affect lower limb kinematics during the swing phase, the relationship between these two remains unclear. This study aimed to investigate the relationship between leg extension angle and knee flexion angle during pre-swing and swing phase in post-stroke gait. Materials and Methods: Twenty-nine stroke patients walked along a 16 m walkway at a self-selected speed. Tilt angles and acceleration of pelvis and paretic lower limb segments were measured using inertial measurement units. Leg extension angle, consisting of a line connecting the hip joint with the ankle joint, hip and knee angles, and increments of velocity during pre-swing and swing phase were calculated. Correlation analysis was conducted to examine the relationships between these parameters. Partial correlation analysis adjusted by the Fugl-Meyer assessment-lower limb (FMA-LL) was also performed. Results: On the paretic side, leg extension angle was positively correlated with knee flexion angle during the swing phase (r = 0.721, p < 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.740–0.846, p < 0.001). Partial correlation analysis adjusted by the FMA-LL showed significant correlation between leg extension angle and knee flexion angle during the swing phase (r = 0.602, p = 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.655–0.886, p < 0.001). Conclusions: Leg extension angle affected kinematics during the swing phase in post-stroke gait regardless of the severity of paralysis, and was similar during the pre-swing phase. These results would guide the development of effective gait training programs that enable a safe and efficient gait for stroke patients. [ABSTRACT FROM AUTHOR]

Background: Diagnosing patellofemoral instability disorders correctly, weight-bearing MRI (WB-MRI) has become an option. Aiming for a best possible accuracy in displaying potentially underlying causes, the named MRI modalities were sporadically even investigated in different knee flexion angles. However, despite confirmed MRI-outcome-differences between WB-MRI and non-WB-MRI, none of the described MRI modalities have so far established themselves. Mainly this is due to an unfeasibility in daily clinical routine in regard to time and economic aspects. Thus, we intended to evaluate an additional but reduced patellofemoral MR-imaging solely in a relevant 20° of knee flexion under WB- and non-WB-MRI conditions.Methods: Seventy-three subjects with and without patellofemoral instability were investigated under supine as well as under WB-MRI conditions in a 20° of knee flexion angle. Patellofemoral risk indices in the sagittal plane (Insall-Salvati-Index, Caton-Deschamps-Index, Patellotrochlear Index) and the axial plane (Patella tilt of Fulkerson and Sasaki) were detected and compared between the different MRI conditions. Significance, reliability and Cohen's effect size was calculated.Results: Nearly all assessed indices showed significant differences between patients and controls in the different MRI positions. Comparing pairwise, all measured indices failed to show significant differences between the two MRI positions. However, patella tilt angles of the patient group showed an elevation from supine to WB-MRI (14.00 ± 7.54° to 15.97 ± 9.10° and 16.34 ± 7.84° to 18.54 ± 9.43°). Here, Cohen's d showed small to medium effects between supine and WB-MRI.Conclusion: In comparison to standard MRI in supine position, axial risk indices seem to be accentuated under WB-MRI and a knee flexion angle of 20°. In particular, symptomatic cases with inconspicuous conventional MRI imaging, additional MRI imaging only in the axial plane in a 20° of knee flexion could be beneficious and useful in clinical daily routine. [ABSTRACT FROM AUTHOR]

BACKGROUND: The patellar and quadriceps tendons are responsible for the extension mechanism of the knee joint and frequently become inflamed during sports. Diagnosis and determination of when an athlete can return to sports following these injuries are usually performed by assessing morphological features and functional outcomes. Nevertheless, mechanical properties are not being assessed. OBJECTIVE: To describe the stiffness characteristics of these two tendons over the range of knee flexion and to test the feasibility of using strain ultrasound elastography (SE). METHODS: SE with an acoustic coupler as the reference was performed for nine healthy males. Relative stiffness measurements were obtained using the strain ratio (SR = target tissue strain/reference strain) by placing the knee in five different flexion angles. Lower SR indicates higher relative stiffness. RESULTS: This study showed reliable measurement with good intra- and inter-rater agreement for SR at 30°. SR of the quadriceps tendon decreases as knee flexion increases, indicating increased relative stiffness. In the patellar tendon, no significant difference was observed between 30° and 60°. Beyond 60°, relative stiffness increased constantly. CONCLUSIONS: SE is a reproducible and feasible tool to monitor relative stiffness of the patellar and quadriceps tendons in routine clinical settings. [ABSTRACT FROM AUTHOR]

Background: This study aims to elucidate and compare the relationship between the knee flexion angle and patient-reported outcome measures (PROM) in both non-weight-bearing (NWB) and weight-bearing (WB) conditions.Methods: This retrospective cohort study included 61 knees (47 patients) who underwent total knee arthroplasty. The knee flexion angle was measured by three conditions: NWB in manual goniometer, NWB in fluoroscopic three-dimensional (3D) analysis and WB in the fluoroscopic 3D analysis. The PROM was evaluated by postoperative 2011 Knee Society Score (2011 KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Correlations between the knee flexion angle and PROM was analyzed using Spearman's correlation coefficient. Additionally, whether the angular difference between NWB and WB correlated with the PROM or not was evaluated.Results: The NWB knee flexion angle in a goniometer, NWB in 3D analysis, and WB in 3D analysis were 124.6° ± 8.4°, 118.0° ± 10.5°, and 109.5° ± 13.3°, respectively. The angular difference was 8.5° ± 12.8°. No PROM correlation existed in NWB using a goniometer. Moreover, significant positive correlations in 2011 KSS symptoms (r = 0.35) and 2011 KSS functional activities (r = 0.27) were noted in NWB using 3D analysis. Significant positive correlations existed in 2011 KSS symptoms (r = 0.32), 2011 KSS functional activities (r = 0.57), KOOS pain (r = 0.37), KOOS activity of daily living (ADL; r = 0.45), KOOS sports (r = 0.42), and KOOS quality of life (r = 0.36) in WB using 3D analysis. Significant negative correlations were noted in 2011 KSS functional activities (r = - 0.45), KOOS ADL (r = - 0.30), and KOOS sports (r = - 0.38) in angular difference.Conclusions: The WB knee flexion angle better correlated with PROM compared with NWB by evaluation of 3D analysis. The larger the angular difference existed between NWB and WB, the lower the PROM score. [ABSTRACT FROM AUTHOR]

Background: Many factors have been reported to affect postoperative range of knee flexion after total knee arthroplasty (TKA); however, no study has reported the impact of preoperative range of motion of the hip to the postoperative flexion angle of the knee thus far. Methods: Of 38 consecutive patients who underwent posterior-stabilized TKA, we assessed 21 patients after excluding 17 patients who met exclusion criteria. The range of motion of the knee and the hip, age, body-mass index, serum albumin level, HbA1c, Kellgren–Lawrence grade, knee extension strength and radiological femorotibial angle as well as postoperative knee flexion angle at three months were evaluated. The preoperative data and the knee flexion angle at three months after TKA were compared using Spearman's rank correlation coefficient. Results: Knee flexion angle at three months after TKA was positively correlated with preoperative flexion (ρ = 0.616, p = 0.007) and external rotation angle (ρ = 0.576, p = 0.012) of the hip as well as preoperative knee flexion angle (ρ = 0.797, p = 0.001). There were no correlations between postoperative knee flexion angle and other preoperative data. Conclusions: Patients with restricted flexion and/or external rotation of the hip may have contractures of Gluteus maximus, Gluteus medius and Tensor fasciae latae, which can cause hypertension of iliotibial tract. It may cause decreased internal rotation of the tibia when the knee is flexed, which affects postoperative knee flexion angle, thus limited flexion and/or external rotation of the hip might restrict knee flexion angle following TKA. [ABSTRACT FROM AUTHOR]

Background: We hypothesized that early postoperative administration of celecoxib would reduce pain scores and improve sleep quality and active range of motion after total knee arthroplasty (TKA) under general anesthesia.Methods: Patients in the celecoxib group received 400 mg of celecoxib 2 hours after TKA, followed 6 hours later by 200 mg of celecoxib. Patients in the control group received 400 mg of celecoxib the second day after surgery. Patients in both group had access to patient-controlled analgesia fentanyl. The primary outcome measure was the patient-reported visual analog scale (VAS) pain score the second day after TKA. The secondary outcome measure was sleep quality (days 1, 2, and 7 postoperatively). Active knee joint range of motion was assessed on days 2 and 7 postoperatively, and VAS pain scores were evaluated on postoperative days 1 to 7. Total fentanyl consumption was also assessed.Results: Compared to the control group, the celecoxib group had significantly lower median VAS pain scores on postoperative days 1 and 2, significantly less nocturnal awakening (in minutes) and frequency of body motion, and better sleep efficacy on postoperative day 1. The celecoxib group also had a significantly better median flexion angle (°) on postoperative days 2 and 7, and lower cumulative fentanyl consumption.Conclusion: Early administration of celecoxib after TKA was associated with significantly reduced early VAS pain scores and improved sleep quality and active knee flexion angles. Thus, the early administration of celecoxib after TKA under general anesthesia may reduce pain and improve sleep quality and functional recovery.Levels Of Evidence: Level II, therapeutic study.Trial Registration: UMIN-CTR 000014624 (July 23, 2014). [ABSTRACT FROM AUTHOR]

Background: Osgood-Schlatter disease (OSD) is a type of osteochondrosis and traction apophysitis that results from repeated contractions of the quadriceps femoris muscle on the tibial tuberosity. Its prevention, early diagnosis, and treatment are crucial because it causes chronic knee pain and surgical approaches are required if left untreated. Three-dimensional motion analysis is a useful approach for elucidating the pathological factors of OSD; however, it requires advanced cameras, sophisticated facilities, and expensive software. Conversely, the advent of technology has provided affordable video recording devices, and smartphone/tablet-based applications have enabled two-dimensional (2D) motion analysis. This emerging tool and artificial intelligence technology were used to analyze the pivot leg from videos recorded on a tablet device during the instep kicks of adolescent soccer players. Therefore, in this study, we aimed to determine whether the pathological factors for OSD occurring in the pivot foot can be identified through a simple 2D motion analysis using a tablet device., Methods: In total, 94 knees of 47 soccer players (aged 14.1±0.8 years, all male) who belong to a single soccer club were evaluated. OSD was diagnosed using ultrasonography and physical examination (a positive bone fragment on ultrasonography or tenderness at the tibial tuberosity). Lower limb muscle tightness was evaluated using the finger-floor distance, straight leg raising test, heel-buttock distance, Thomas test, and ankle range of motion using a goniometer. We then performed motion analysis, and the instep kicking motion was recorded using a video camera on a tablet device. The joint angles of the hip, knee, and ankle were measured using a real-time human-pose detection system. Data were compared between the OSD and non-OSD groups., Results: Overall, six of the 47 players (12.8%) were diagnosed with OSD. No correlation was found between lower limb tightness and the occurrence of OSD in all indices. However, the 2D motion analysis revealed that the knee flexion angle at the time of plantar placement during the instep kick movement was significantly larger in the OSD group than in the non-OSD group (OSD group: 42.0±7.2˚, non-OSD group: 33.5±6.6˚, *p=0.013)., Conclusion:  A video motion analysis revealed that the knee flexion angle during the instep kicking motion was significantly greater in athletes with OSD of the supporting foot., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Committee of the Faculty of Medicine, Kagawa University Hospital issued approval 2023-156. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Fukuoka et al.)

Background: The direct relationship between clinical outcomes and femoral component positioning relative to a tibial insert remains unknown. We determined whether the femoral component position relative to the tibial insert could affect clinical outcomes after fixed-bearing unicompartmental knee arthroplasty (UKA).Methods: The femoral component position relative to the tibial insert of 66 patients with anteromedial osteoarthritis and osteonecrosis of the knee who underwent fixed-bearing UKA was assessed at 2 weeks postoperatively. We classified patients according to the contact point of the femoral component with the tibial component: group M (medial), 18 knees; group C (central), 30 knees; and group L (lateral), 18 knees. Patient-derived clinical scores using the 2011 Knee Society Score were also assessed preoperatively and at 2 years postoperatively and compared among the 3 groups using the analysis of variance.Results: The average 2-year postoperative "symptom" and "patient satisfaction" scores based on the 2011 Knee Society Score were significantly higher in group C than in group M or group L.Conclusion: Central implantation of the femoral component relative to the tibial insert plays an important role in decreasing pain and could result in better patient satisfaction after fixed-bearing UKA at 2 years postoperatively. Surgeons should set the femoral component at the center relative to the tibial insert for better patient satisfaction and higher active knee flexion after fixed-bearing UKA. [ABSTRACT FROM AUTHOR]

Bicycle saddle height configurations have been shown to affect knee joint biomechanics. Research suggests that an excessively low saddle height may lead to Patellofemoral Pain Syndrome, which is thought to be caused by the knee adduction moment during cycling. However, how saddle heights affect frontal plane knee biomechanics was not clear. We aimed to compare different saddle heights on frontal plane knee biomechanics during cycling. Twenty healthy young recreational cyclists (23.4 ± 0.5 years) performed 3 min of cycling at four different saddle heights (Medium [25° knee flexion angle], Preferred [a height chosen by cyclists], Low [Preferred + 15°], High [Preferred - 15°] measured at the bottom-dead-center). Cycling workload and cadence were set at 60 w and 60 RPM, respectively, since our project was focused on rehabilitation. A motion analysis system and a custom instrumented pedal were used to collect three-dimensional kinematics d (200 Hz) and pedal reaction force (1000 Hz). Results showed that, compared with other saddle heights, Low saddle height produced greater adduction knee moments (11.9 ± 1.9 Nm, P < 0.05), a longer duration (0.15 ± 0.01 s, P < 0.05), larger knee flexion (58.5 ± 2.6°, P < 0.05) and larger abduction angles (−4.5 ± 0.8°, P < 0.05). We showed that Low saddle height resulted in increased knee adduction moments with longer duration. In contrast, High saddle height reduced both knee moments and time duration. The results suggest that increased saddle heights may provide a safe and efficient cycling strategy for healthy young recreational cyclists. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: To compare gait biomechanics throughout stance phase 6 and 12 months after unilateral anterior cruciate ligament reconstruction (ACLR) between ACLR and contralateral limbs and compared with controls. Methods: Vertical ground reaction force (vGRF), knee flexion angle (KFA), and internal knee extension moment (KEM) were collected bilaterally 6 and 12 months post-ACLR in 30 individuals (50% female, 22 ± 3 yr, body mass index = 23.8 ± 2.2 kg·m−2) and at a single time point in 30 matched uninjured controls (50% female, 22 ± 4 yr, body mass index = 23.6 ± 2.1 kg·m−2). Functional analyses of variance were used to evaluate the effects of limb (ACLR, contralateral, and control) and time (6 and 12 months) on biomechanical outcomes throughout stance. Results: Compared with the uninjured controls, the ACLR group demonstrated bilaterally lesser vGRF (ACLR, 9% body weight [BW]; contralateral, 4%BW) during early stance and greater vGRF during midstance (ACLR, 5%BW; contralateral, 4%BW) 6 months post-ACLR. Compared to the uninjured controls, the ACLR group demonstrated bilaterally lesser vGRF (ACLR, 10%BW; contralateral, 8%BW) during early stance and greater vGRF during midstance (ACLR, 5%BW; contralateral, 5%BW) 12 months post-ACLR. Compared with controls, the ACLR limb demonstrated lesser KFA during early stance at 6 (2.3°) and 12 months post-ACLR (2.0°), and the contralateral limb demonstrated lesser KFA during early stance at 12 months post-ACLR (2.8°). Compared with controls, the ACLR limb demonstrated lesser KEM during early stance at both 6 months (0.011BW × height) and 12 months (0.007BW × height) post-ACLR, and the contralateral limb demonstrated lesser KEM during early stance only at 12 months (0.006BW × height). Conclusions: Walking biomechanics are altered bilaterally after ACLR. During the first 12 months post-ACLR, both the ACLR and contralateral limbs demonstrate biomechanical differences compared with control limbs. Differences between the contralateral and control limbs increase from 6 to 12 months post-ACLR. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lower limb compensation for spinal sagittal malalignment and its impact on quality of life (QOL) and low back pain (LBP) have not been well studied. OBJECTIVE: To clarify postural compensation and the impact of spinal and lower limb sagittal alignment and muscle strength on QOL and LBP in persons > 50 years old. METHODS: In this cross-sectional study, 122 rural community-dwelling, healthy adults (56 males, 66 females; average age 71.1 years; age range, 52–88 years) underwent assessments of QOL (36-Item Short-Form Health Survey; SF-36), LBP (Roland-Morris Disability Questionnaire; RDQ), thoracic kyphosis (TK), lumbar lordosis (LL), sacral inclination (SI), grip strength, lower limb strength, and back extensor strength (BES). On univariate and multivariate analyses, variables that correlated with QOL and the RDQ were identified. RESULTS: LL was moderately correlated with SI and weakly correlated with the knee flexion angle (KFA). LL, KFA, C7-L5D, and BES were correlated with SF-36 subscales and the RDQ. KFA contributed to the physical component summary of the SF-36. Female sex and BES contributed to the RDQ. CONCLUSIONS: Knee flexion compensated for lumbar kyphosis, but affected physical QOL scores negatively; BES was the most reliable contributor to QOL and the RDQ. [ABSTRACT FROM AUTHOR]

Whole-body vibration refers to an exercise that stimulates the muscles, using a vibration with an amplitude and power, however, there are few studies that have dealt with fundamental questions such as optimal frequency or body position. This study aims to compare lower limb activation, according to horizontal wholebody vibration frequency and knee flexion angle, in healthy adults. Using 18 healthy adults aged 21-30, this study measured and analysed the activities of the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GCM) muscles, for different horizontal whole-body vibration frequencies (0 Hz, 2 Hz, and 4 Hz) and knee flexion angles (0°, 30°, and 60°), using surface electromyography (sEMG). There was a statistically significant increase in lower limb muscle activation according to horizontal whole-body vibration frequency and knee flexion angle: comparing muscle activation with frequency, the muscle activation of VL, BF, TA, and GCM increased with increase in frequency (p<0.05). The muscle activation of VL and TA increased with increase in knee flexion angle (p<0.05). In this study, it was observed that for whole-body vibration provided in a horizontal direction, larger the frequency and higher the knee flexion angle, greater the lower limb activation. [ABSTRACT FROM AUTHOR]

Background/Objectives: The purpose of this study is to compare the change of thickness of serratus anterior muscle to different angles of knee flexion when knee push up plus (KPP) exercise is conducting on an unstable surface (sling). Method/Statistical Analysis: There were 30 healthy young male and female students randomly selected and divided into 3 different groups along different knee flexion angles on an unstable surface (sling). The three groups of ten did KPP exercises on the sling. The muscle was measured before and after the exercise. Findings: All three groups showed some changes in the thickness of the muscle. The group with the biggest change was the 60° knee flexion, followed by 75° and 90° groups. Improvements/Applications: Based on the results, all experimental groups showed some differences with KPP exercise conducted on an unstable surface (sling) and especially the group with the lowest angle had the most effect. Therefore, it is concerned that a lower knee flexion angle can be more effective on the KPP exercise. [ABSTRACT FROM AUTHOR]

Objective: To compare sagittal walking gait biomechanics between participants with knee osteoarthritis (KOA) who increased quadriceps strength following a lower-extremity strengthening intervention (responders) and those who did not increase strength following the same strengthening protocol (non-responders) both at baseline and following the lower extremity strengthening protocol.Design: Fifty-three participants with radiographic KOA (47% female, 62.3 ± 7.1 years, BMI = 28.5 ± 3.9 kg/m2) were enrolled in 10 sessions of lower extremity strengthening over a 28-day period. Maximum isometric quadriceps strength and walking gait biomechanics were collected on the involved limb at baseline and 4-weeks following the strengthening intervention. Responders were classified as individuals who increased quadriceps strength greater than the upper limit of the 95% confidence interval (CI) for the minimal detectable change (MDC) in quadriceps strength (29 Nm) determined in a previous study. 2 × 2 functional analyses of variance were used to evaluate the effects of group (responders and non-responders) and time (baseline and 4-weeks) on time-normalized waveforms for knee flexion angle (KFA), vertical ground reaction force (vGRF), and internal knee extension moment (KEM).Results: A significant group x time interaction for KFA demonstrated greater KFA in the first half of stance at baseline and greater knee extension in the second half of stance at 4-weeks in responders compared to non-responders. There was no significant group x time interaction for vGRF or internal KEM.Conclusions: Quadriceps strengthening may be used to stimulate small changes in KFA in individuals with KOA. [ABSTRACT FROM AUTHOR]

Background: Deficits in dynamic neuromuscular control of the knee may contribute to the higher incidence of the anterior cruciate ligament (ACL), specifically in female athletes. Little is known about the effects of preventive training programs on muscle onset time and activation during functional tasks. Purpose: The purpose of this study was to evaluate the efficacy of perturbation-enhanced neuromuscular training on hamstring and quadriceps onset time and activation, and knee flexion angle in female athletes with quadriceps dominance (QD) deficit during a tuck-jump (TJ) task. Study Design: Quasi-experimental study Methods: Thirty-one collegiate female athletes with neuromuscular quadriceps dominance deficit randomly divided into experimental (n=16) and control (n=15) group. The experimental group performed a six-week perturbation training (18 sessions). Electromyograhic (EMG) assessment of quadriceps and hamstring activation and knee flexion angles during a TJ task were completed at baseline and after six weeks. Results: A significant decrease in the preparatory(p=0.003) and reactive (p=0.013) quadriceps-hamstring (Q/H) co-activation ratio was found in the experimental group. Perturbation training markedly decreased latency in medial hamstring (MH) (p=0.001), vastus medialis (VM) (p=0.004) and lateral hamstring (LH) (p=0.031), while latency increased for rectus femoris (RF) (p=0.001) and vastus lateralis (VL) (p=0.023) during a TJ task. The experimental group had average increases of 41.1%, 40.8%, and 39.5% in initial knee flexion, peak knee flexion and knee flexion displacement angle during the TJ task, respectively. Conclusion: Increased preparatory VM and MH activities and decreased Q/H co-activation ratio, decreased VM and MH latency represent preprogrammed motor strategies learned during the perturbation training. This observed neuromuscular adaptation during TJ task could potentially reduce the risk for non-contact ACL injury. Level of evidence: 2 [ABSTRACT FROM AUTHOR]