Factors associated with physical activity following total knee arthroplasty for knee osteoarthritis: a longitudinal study.

BACKGROUND: After total knee arthroplasty (TKA), patients' physical activity (PA) levels at 6 months are lower than those of healthy subjects. Few studies have investigated the factors associated with PA at 6 months after TKA by objectively measuring preoperative and postoperative PA intensity using an accelerometer and knee function using a goniometer and dynamometer. The purpose of this study was to determine the factors associated with PA levels at 6 months after TKA based on objective data. METHODS: Eighty-two patients (mean [SD] age 74.5 [6.4] years) with moderate-to-severe knee osteoarthritis (OA) who were scheduled for TKA at the Nagoya Orthopaedic and Joint Replacement Clinic from July 2018 to July 2019 were enrolled in this longitudinal study. All patients underwent evaluations of knee function, including range-of-motion and knee-extension muscle strength; knee pain; performance in the timed up-and-go test; and accelerometer-measured PA both preoperatively and 6 months postoperatively. Factors associated with PA at 6 months after TKA were assessed using a hierarchical multiple linear regression analysis adjusted for age, sex, body mass index, and presence of diabetes mellitus. RESULTS: A higher average daily step count at 6 months after TKA was significantly associated with greater preoperative knee-extension muscle strength on the operated side (ß = 0.155, p = 0.028) as well as a higher preoperative average daily step count (ß = 0.834, p < 0.001). Furthermore, average daily time spent in moderate-to-vigorous-intensity PA postoperatively was significantly associated only with time spent in moderate-to-vigorous-intensity PA preoperatively (ß = 0.723, p < 0.001). CONCLUSION: These findings indicate that a higher preoperative daily step count and greater preoperative knee-extension muscle strength on the operated side may be associated with a higher daily step count at 6 months after TKA. Factors associated with PA differed by the PA intensity level. Rehabilitation and interventions for psychosocial factors before TKA beginning when mild knee OA first occurs are expected to lead to increased PA in TKA patients.

Sex-based differences and relationship with the restricted knee flexion angle due to aging: a comparative study.

BACKGROUND: The relationship between inferior patellar mobility (IPM) and knee flexion angle has yet to be elucidated. This study aimed to develop quantitative IPM measurement methods and clarify the relationship between IPM and knee flexion angle in community-dwelling older females. METHODS: This was a cross-sectional study. Overall, 128 healthy older women (age 65-79 years) were recruited from the community to evaluate the relationship between IPM and knee flexion angle. This study was performed between May 2015 and December 2017. The reference value of and sex differences in IPM were evaluated in 205 healthy young adults aged between 19 and 21 years. IPM was compared between healthy older and young women and was objectively measured using our specially designed patellofemoral arthrometer (PFA). Patellar mobility was calculated by normalization to body height. IPM reliability was assessed before all measurements. RESULTS: Intraclass correlation coefficients for intratester and intertester reliabilities varied from 0.87 to 0.99. The normal range based on two standard deviations of inferior patellar displacement/body height was 5.9-13.5% (young men), 5.1-14.3% (young women), and 1.2-8.8% (older women). IPM was significantly lower in older than young women (P < 0.001). There was a significant positive correlation (r = 0.72 and P < 0.01) between IPM and knee flexion angle in healthy older women unable to flex the knee joint fully. CONCLUSIONS: Our PFA has good intratester and intertester reliability. The results suggest that IPM decreases with aging in women. IPM and knee flexion angle are correlated among older women unable to flex the knee joint fully. CLINICAL TRIAL REGISTRATION: Not applicable.

A Computationally Efficient Lower Limb Finite Element Musculoskeletal Framework Directly Driven Solely by Inertial Measurement Unit Sensors.

Finite element musculoskeletal (FEMS) approaches using concurrent musculoskeletal (MS) and finite element (FE) models driven by motion data such as marker-based motion trajectory can provide insight into the interactions between the knee joint secondary kinematics, contact mechanics, and muscle forces in subject-specific biomechanical investigations. However, these data-driven FEMS systems have two major disadvantages that make them challenging to apply in clinical environments: they are computationally expensive and they require expensive and inconvenient equipment for data acquisition. In this study, we developed an FEMS model of the lower limb, driven solely by inertial measurement unit (IMU) sensors, that includes the tissue geometries of the intact knee joint and combines muscle modeling and elastic foundation (EF) theory-based contact analysis of a knee into a single framework. The model requires only the angular velocities and accelerations measured by the sensors as input, and the target outputs (knee contact mechanics, secondary kinematics, and muscle forces) are predicted from the convergence results of iterative calculations of muscle force optimization and knee contact mechanics. To evaluate its accuracy, the model was compared with in vivo experimental data during gait. The maximum contact pressure (12.6 MPa) in the rigid body contact analysis occurred on the medial side of the cartilage at the maximum loading response. The proposed computationally efficient framework drastically reduced the computational time (97.5% reduction) in comparison with the conventional deformable FE analysis. The developed framework combines measurement convenience and computational efficiency and shows promise for clinical applications aimed at understanding subject-specific interactions between the knee joint secondary kinematics, contact mechanics, and muscle forces.

Effects of walking with a "draw-in maneuver" on the knee adduction moment and hip muscle activity.

[Purpose] To investigate the effect of performing a draw-in maneuver (DI) on knee adduction moment (KAM) and hip and trunk muscle activities while walking. [Participants and Methods] We included 30 healthy young adults (21.5 ± 0.6 years, 16 males and 14 females) in this study. We measured the KAM and lever arm while participants walked with either a normal gait or a DI gait. We also performed surface electromyography (EMG) of the hip and trunk muscles (i.e., internal oblique abdominal muscle [IO], external oblique abdominal muscle [EO], multifidus muscle [MF], and gluteus medius muscle [GM]). [Results] The 1st peak of the KAM was significantly lower when walking with a DI gait compared to when walking with a normal gait. The integrated EMG activity of the IO, EO, and GM during the 1st half of the stance phase, and of the IO and EO during the 2nd half of the stance phase was significantly higher during the DI than during normal gait. [Conclusion] Compared with a normal gait, a DI gait leads to a decrease in the 1st peak of the KAM as a result of the shorter lever arm, and an increase in the muscular activity of the GM, IO, and EO.

Enhancement of walking ability using a custom-made hinged knee brace in patients who experienced ambient stroke and are in the acute phase.

[Purpose] In this study, we investigated the immediate effect on walking using a custom-made hinged knee brace with adjustable knee flexion and extension support (support brace) in patients in the acute phase of stroke. [Participants and Methods] Thirteen patients (56.8 ± 6.8 years) who experienced stroke and who were able to walk independently participated in the study. The walking speed and mean knee extension strength were evaluated under three conditions: no brace, general brace, and support brace. [Results] The walking speed of patients while using the support brace was significantly faster (0.60 ± 0.11 m/s) than that without brace (0.45 ± 0.16 m/s) and with general brace (0.52 ± 0.14 m/s). The fastest walking speed among all 8 patterns (no brace, general brace, and the support brace with six different patterns of support) was with the support brace. The mean knee extension strength while wearing a support brace (1.01 ± 0.24 Nm/kg) was significantly greater than that without wearing a brace (0.82 ± 0.28 Nm/kg). [Conclusion] The support brace, which allows for customizable adjustment of the flexion and extension strength, enhanced the walking ability of patients who experienced ambient stroke and were in the acute phase.

Custom-made hinged knee braces with extension support can improve dynamic balance.

Background/Objective: We investigated whether custom-made hinged knee braces can facilitate knee extensor and flexor strength and influence functional performance as compared with other knee braces. METHODS: We enrolled 28 healthy young participants with no history of physical activity or brace use. The participants executed functional performance tests under the following 5 conditions: 1) without a knee brace, 2) wearing a knee sleeve, 3) wearing a hinged knee brace without assistance, 4) wearing a knee brace with extension support (KBE), and 5) wearing a knee brace with flexion support (KBF). The KBE and KBF were custom-made hinged knee braces equipped with rubber tubes. The functional performance tests performed assessed maximal isokinetic strength, single-leg jumping height/distance, anterior and posterior reach distance on a single leg, and dynamic balance ability. RESULTS: The benefit of the custom-made hinged knee brace was observed only during the anterior reach distance on a single leg. The KBE allowed a significantly greater single-leg anterior reach distance when compared to that in the no brace condition. There was a significant relationship between the improvement in the single leg anterior reach distance with KBE and the changes in isokinetic knee extension with KBE compared to the no brace condition. With regard to other parameters, there were no differences compared with the use of other knee braces and thus no apparent benefit. CONCLUSION: Our findings suggest that using a KBE enhances performance during dynamic balance activity in individuals who benefit from improved knee extension strength.

Relationship between patellar mobility and patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction.

Patellofemoral cartilage degeneration is a potential complication of anterior cruciate ligament reconstruction (ACLR) surgery. Hypomobility of the patella in the coronal plane is often observed after ACLR. Few studies, however, have examined the relationship between cartilage degeneration in the patellofemoral joint and mobility after ACLR. The present study investigated 1) the coronal mobility of the patella after ACLR, 2) the relationship between patellar mobility and cartilage degeneration of the patellofemoral joint, and 3) the relationship between patellar mobility and knee joint function after ACLR. Forty patients who underwent medial hamstring-based ACLR participated in the study. Lateral and medial patellar displacements were assessed with a modified patellofemoral arthrometer, and the absolute values of the displacements were normalized to patient height. The International Cartilage Repair Society (ICRS) cartilage injury classification of the patellar and femoral (trochlear) surfaces, and the Lysholm Knee Scoring Scale were used to evaluate knee function. Lateral and medial patellar displacements were reduced compared with the non-operated knee at the second-look arthroscopy and bone staple extraction operation (second operation; 24.4 ± 7.9 months after ACLR, P<0.01). The ICRS grades of the patellofemoral joint (patella and trochlea) were significantly worse than those pre-ACLR. Neither lateral nor medial patellar mobility, however, were significantly correlated with the ICRS grade or the Lysholm score. Although patellar mobility at approximately 2 years after ACLR was decreased compared to the non-operated knee, small displacement of the patella was not related to cartilage degeneration or knee joint function at the time of the second operation.

Does the Q - H index show a stronger relationship than the H:Q ratio in regard to knee pain during daily activities in patients with knee osteoarthritis?

[Purpose] The purpose of this study was to elucidate the relationship between knee muscle strength and knee pain in activities of daily living, based on consideration of the difference between extension and flexion strength (Q - H) and the hamstring:quadriceps (H:Q) ratio in patients with knee osteoarthritis. [Subjects and Methods] The participants were 78 females with knee osteoarthritis, and a total of 133 knees that had not been treated surgically were the targets of this research. The legs were divided according to dominance. Isometric knee extension and flexion muscle strength and knee pain during activities of daily living were measured. The H:Q ratio (flexion/extension muscle strength) and the difference between extension and flexion strength, (extension muscle strength/weight) minus (flexion muscle strength/weight), that is, Q - H, were calculated. The correlation between these indices and the knee pain score during activities of daily living was investigated. [Results] Greater knee pain during activities of daily living was related to lower knee extension muscle strength and Q - H in both the dominant and nondominant legs. Knee flexion muscle strength and the H:Q ratio were not significantly correlated with knee pain during any activities of daily living. [Conclusion] Knee extension muscle strength and Q - H were found to be significantly correlated with knee pain during activities of daily living, whereas the H:Q ratio was not.

Preliminary study of optimal measurement location on vibroarthrography for classification of patients with knee osteoarthritis.

[Purpose] The aims of the present study were to investigate the most suitable location for vibroarthrography measurements of the knee joint to distinguish a healthy knee from knee osteoarthritis using Wavelet transform analysis. [Subjects and Methods] Participants were 16 healthy females and 17 females with severe knee osteoarthritis. Vibroarthrography signals were measured on the medial and lateral epicondyles, mid-patella, and tibia using stethoscopes with a microphone while subjects stood up from a seated position. Frequency and knee flexion angles at the peak wavelet coefficient were obtained. [Results] Peak wavelet coefficients at the lateral condyle and tibia were significantly higher in patients with knee osteoarthritis than in the control group. Knee joint angles at the peak wavelet coefficient were smaller (more extension) in the osteoarthritis group compared to the control group. The area under the receiver operating characteristic curve on tibia assessment with the frequency and knee flexion angles was higher than at the other measurement locations (both area under the curve: 0.86). [Conclusion] The tibia is the most suitable location for classifying knee osteoarthritis based on vibroarthrography signals.

Effects of a custom-made hinged knee brace with knee flexion support for patients with knee osteoarthritis:a preliminary study.

A knee brace for medial knee osteoarthritis (OA) is required to restrict knee adduction moment (KAM), but must not restrict knee flexion during swing phase. There is no report of a knee brace with both functions. The purpose of this study is to investigate the effect of the custom-made hinged knee brace for patients with knee OA compared to the hinged knee brace generally used, and to assess the KAM and knee flexion angle during swing phase. Fifteen patients (average age: 71.6 ± 7.8 years old) with medial knee OA participated. Gait analysis was performed using a 3-D motion analysis system to measure two conditions: hinged knee brace (KB), and a custom-made hinged knee brace with knee-flexion support- equipped rubber tubes at the posterior of the lateral and medial side poles (KBF). The peak KAM with KBF was significantly smaller than those with the KB (P=0.004, the difference between these conditions of KAM: 0.06 Nm/kg). The peak knee flexion angles during swing phase with KBF were also significantly larger than those with the KB (P=0.004, the difference between these conditions of knee flexion angle: 1.5 degrees). The custom-made brace with one type of tube actuator in the present study could decrease KAM and make for a small increase of knee flexion angle as opposed to the hinged knee brace.

Does decrease of the thoracic kyphosis influence decrease knee adduction moment during gait? A preliminary study of a healthy population.

[Purpose] The purpose of this study was to investigate the influence of a decrease in thoracic kyphosis angle on the knee adduction moment during gait in healthy young individuals. [Subjects and Methods] Twenty-nine healthy adults, consisting of 15 males and 14 females (21.6 ± 1.1 years old), participated. The draw-in maneuver was used to decrease thoracic kyphosis, and thoracic kyphosis was measured using a SpinalMouse during normal standing and standing with the draw-in maneuver. The participants were required to maintain the draw-in maneuver during gait. A 3-D motion analysis system and a force plate were used to obtain knee adduction moment. [Results] Thoracic kyphosis angles during the draw-in maneuver (41.0 ± 7.4 degrees) were significantly decreased compared with the angles during normal standing (43.0 ± 7.9 degrees). Although the knee adduction moment during gait with the draw-in maneuver was not significantly decreased compared with that during level gait, in the 20 subjects who had decreased kyphosis due to the draw-in maneuver, the 1st peak knee adduction moment (55.7 ± 24.3 × 10(-3)) with the draw-in maneuver was significantly decreased compared with the knee adduction moment (57.0 ± 16.3 × 10(-3)) during level gait. [Conclusion] Knee adduction moment in the case of a decreased thoracic kyphosis angle due to the draw-in maneuver was decreased compared with that during level gait.

Preoperative Loss of Knee Extension Affects Knee Extension Deficit in Patients After Anterior Cruciate Ligament Reconstruction.

Background: Loss of knee extension (LOE) after anterior cruciate ligament reconstruction (ACLR) is associated with limited knee joint function and increased risk for knee osteoarthritis. Hypothesis: Preoperative LOE will affect postoperative LOE for up to 12 months after ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: Included were patients who underwent anatomic ACLR between June 2014 and December 2018. In all patients, the postoperative rehabilitation protocol was the same. A heel height difference (HHD) ≥2 cm between the affected and the contralateral leg was used as a measure of LOE. Based on preoperative HHD, patients were divided into LOE and no-LOE groups. The HHD was reevaluated at 1, 3, 4, 6, 9, and 12 months postoperatively. Proportional hazards analysis was used, with the dependent variable being whether a postoperative HHD <2 cm was achieved; the independent variables being the presence or absence of preoperative LOE; and the adjusted variables being age, sex, time to surgery, and presence of meniscal sutures. Results: A total of 389 patients (208 female, 181 male; median age, 21.0 years) were included in the study. There were 55 patients in the LOE group and 334 patients in the no-LOE group. The incidence of LOE at 12 months after ACLR was 13.8% in the no-LOE group and 38.2% in the LOE group (P < .001), with an absolute risk difference of 24.4%. The hazard ratio for achieving postoperative HHD <2 cm was 2.79 for the LOE group versus the no-LOE group (P < .001). Conclusion: Patients with preoperative LOE were nearly 3 times more likely than those without LOE to have LOE at 12 months after ACLR.

[The Metaverse: A New Frontier for Healthcare].

We discuss leveraging a cutting-edge technology known as the Metaverse to tackle healthcare challenges, with a particular focus on enhancing patient satisfaction and improving working conditions for medical professionals. We plan to achieve this by improving real-digital collaboration and utilizing the advantages of the Metaverse, such as novel communication and experiences and increased work efficiency and quality. This article showcases several concrete examples of Metaverse services in the medical field, as demonstrated by the "Medical Metaverse Joint Research Course" established through a collaboration between IBM and Juntendo University, and also highlights possible future prospects.

Effect of diabetes mellitus on physical activity in patients with knee osteoarthritis: A cross-sectional study.

PURPOSE: Knee osteoarthritis (OA) may be comorbid with diabetes mellitus (DM), and physical activity is a recommended lifestyle strategy for both diseases. The present study investigated the physical activity differences by intensity between knee OA patients with or without DM, and evaluated if physical activity was associated with the presence of DM in knee OA patients. METHODS: A total of 183 patients (mean age 74.9 ± 6.4 years) with moderate-to-severe knee OA underwent evaluation of knee function (i.e., knee flexion/extension range-of-motion, knee-extension muscle strength, and knee pain), the timed up-and-go (TUG) test, and physical activity measurement using an accelerometer. Physical activity by intensity was compared between knee OA patients with and without DM. The association between physical activity, including knee function and the TUG test time, and DM was assessed. RESULTS: The 2 groups (with or without DM) did not differ significantly in knee OA severity or age. Compared to knee OA patients without DM, knee OA patients with DM had a significantly lower average daily step count (p < 0.001), and significantly shorter times spent performing light-intensity physical activity (LPA; p < 0.001) and moderate-to-vigorous-intensity physical activity (MVPA; p = 0.006). After adjusting for age, sex, and body mass index, we found that a lower average daily step count and shorter LPA time significantly correlated with DM (ß = -0.200, p = 0.006; ß = -0.216, p = 0.004, respectively) and a longer TUG test time (ß = -0.196, p = 0.014; ß = -0.208, p = 0.011, respectively). A shorter MVPA time significantly correlated with lower contralateral knee-extension muscle strength (ß = 0.187, p = 0.032). CONCLUSION: Knee OA patients with DM had significantly lower physical activity levels than those without DM. Furthermore, the presence of DM correlated with a lower step count and a shorter LPA time in knee OA patients.

Lower limb muscle quality and phase angle contribute to the reduced walking speed among older adults.

AIM: This cross-sectional study aimed to determine the predictors of a walking speed <1 m/s. Factors associated with the health of muscle cells, including the phase angle analyzed using bioimpedance analysis, answers to the mini-nutritional assessment-short form, albumin levels, leg muscle quality and vitamin D levels, were assessed. METHODS: The study participants were outpatients from the Locomotor Frailty Outpatient Clinic which was established at our center in 2016 (231 women, 76.5 ± 7.6 years; 137 men, 78.0 ± 6.3 years). Participants were classified into two groups, with 1 m/s walking speed as the cutoff value. Binominal logistic regression analysis was performed with walking speed as the dependent variable, and age, leg muscle quality, mini-nutritional assessment-short form answers, albumin levels, vitamin D levels and the phase angle as explanatory variables. Leg muscle quality was defined as the mean value of both lower limbs' isometric knee extensor strength, divided by the mean value of both lower limbs' muscle mass through bioimpedance analysis. RESULTS: The explanatory variables associated with decreased walking speed among women were leg muscle quality (P = 0.004, odds ratio: 0.57) and phase angle (P = 0.017, odds ratio: 0.42). Men were also more likely to have leg muscle quality (P = 0.004, odds ratio: 0.43). CONCLUSIONS: Leg muscle quality and the phase angle of lower extremities were independently associated with low walking speeds (<1 m/s) among older outpatients. Geriatr Gerontol Int 2022; 22: 603-609.

Change in ground reaction force parameters according to the frailty level of older women in the Timed Up and Go test.

As older people become frail, they tend to fall more easily. Moreover, women have a higher rate of falls than men. However, effective strategies to avoid elderly women falling are lacking. The Timed Up and Go test is a well-known indicator of falling tendency. This study clarifies the motor elements related to the Timed Up and Go test according to the degree of weakness in older outpatients to specify exercise intervention to improve weakness and prevent falls. Participants were 145 female outpatients who visited the Locomo-Frail outpatient clinic, classified into three groups (robust, prefrail, and frail, according to the definition of the Japanese Cardiovascular Health Study. Vertical ground reaction force parameters were measured for all participants when they stood up from a chair, walking speed, and the Timed Up and Go test. Results showed that walking speed is related to the Timed Up and Go test in the robust group; balance ability is related to the Timed Up and Go test in the prefrail group; and instantaneous force is related to the Timed Up and Go test in the frail group. These results suggest that weakness can be improved by performing exercise interventions of balance and instantaneous force elements in the prefrail and frail groups, respectively.

The influence of knee varus and valgus on quadriceps muscle activity changes induced by stretching and kneeling.

This study aimed to determine the influence of knee varus (VARUS) and valgus (VALGUS) on the differences in individual quadriceps muscle (QM) activity during knee extension maximum voluntary isometric contractions (MVICs) and sit/stand transitions and on the changes in individual QM activity during sit/stand transitions after QM stretching and kneeling. Ten young healthy males each with VARUS and VALGUS were included. The electromyography signals of the vastus medialis (VM), vastus lateralis, and rectus femoris were recorded during sit/stand transitions before and after rest, stretching, and kneeling and during knee extension MVICs after rest. The individual muscle-to-total muscle activity ratio was assessed. The VARUS group exhibited a significantly higher VM muscle activity ratio in the sit-to-stand and stand-to-sit tasks than in knee extension MVICs (p = 0.004 and p = 0.044, respectively) and a tendency that the VM muscle activity ratio increased in the sit-to-stand task after stretching (p = 0.051), whereas the VALGUS group exhibited no significance. Individuals with VARUS required high VM muscle activity ratios during sit/stand transitions. Future studies should be conducted to determine whether habitual sit-to-stand exercises after QM stretching are effective in preventing knee medial osteoarthritis development in individuals with VARUS.

Predictors of frontal plane knee excursion during a drop land in young female soccer players.

STUDY DESIGN: Controlled laboratory study using a cross-sectional, single testing session. OBJECTIVE: To determine the association between frontal plane knee excursion during a drop land task and measures of hip strength, and ankle and hip range of motion. BACKGROUND: Assessment of frontal plane knee excursion during a drop land task has been advocated as a means to screen for potentially injurious lower extremity movement patterns. Accordingly, an understanding of the physical characteristics associated with the magnitude of frontal plane knee excursion could assist clinicians in developing interventions and prevention strategies to minimize injury risk. METHODS AND MEASURES: Thirty-nine female high school soccer players (mean +/- SD age, 15.5 +/- 1.0 years; height, 162.2 +/- 5.3 cm; body mass, 56.8 +/- 6.7 kg) participated. Isometric hip muscle strength as well as ankle and hip range of motion measurements were obtained using standard clinical procedures and a handheld dynamometer. Frontal plane knee excursion was assessed using a 6-camera motion analysis system during a drop land task. Using 3-dimensional coordinate data, maximum frontal plane knee excursion was defined as the difference between the distances of right and left lateral knee markers at initial contact and maximum knee flexion during the deceleration phase of landing. Independent variables found to be significantly correlated with frontal plane knee excursion were then entered into a stepwise multiple regression procedure to determine the best set of predictors of this motion. RESULTS: Hip external rotation range of motion and ankle dorsiflexion range of motion were found to be negatively correlated with frontal plane knee excursion (r=-0.40, P=.005 and r=-0.27, P=.05, respectively). Together they accounted for 27% of the variance in frontal plane knee excursion (r=0.52, P=.03). No relationships between measures of hip strength and frontal plane knee excursion were found. CONCLUSIONS: Frontal plane knee excursion during a drop land task was partially attributed to available range of motion at the hip and ankle. These results suggest that range of motion of the joints proximal and distal to the knee should be considered when evaluating individuals who present with excessive frontal plane knee excursion during this task. Given that the relationship between range of motion and frontal plane knee excursion was small, other factors, including learned motor patterns, should be considered.

Comparison of patellar mobility in female adults with and without patellofemoral pain.

STUDY DESIGN: Case control study. OBJECTIVE: To compare the patellar mobility of female adult subjects with and without patellofemoral pain (PFP). BACKGROUND: Although abnormal patellar mobility is believed to be one of the causes of PFP, there is currently no published evidence to support this contention. In part, this lack of evidence is because a reliable clinical measurement method to measure patellar mobility and objective criteria to define abnormal patellar mobility have not been established. METHODS AND MEASURES: The study sample was comprised of 22 females with PFP (PFP group) and 22 females who had no knee pain (control group), matched by age, height, and body mass index to the subjects with PFP. Patellar mobility was measured objectively using a specially designed apparatus. Measurements of lateral and medial patellar displacement, patellar mobility balance (lateral minus medial patellar displacement), lateral patellar mobility index (lateral patellar displacement divided by patellar width), and medial patellar mobility index (medial patellar displacement divided by patellar width) were used. RESULTS: Lateral and medial patellar mobility values were not significantly different between the individuals in the PFP and control groups. When normal patellar mobility was arbitrarily defined as the average mobility +/- 2 SDs, based on the data from the control group, normal lateral patellar displacement was within a range of 7.2 to 17.6 mm and normal medial patellar displacement was within a range of 6.8 to 14.0 mm. The intraclass correlation coefficient for intratester and intertester reliability of lateral and medial patellar displacement measurements varied from 0.80 to 0.97. CONCLUSION: Although there were no significant differences in patellar mobility between females with and without PFP, these measurements give reference information about normal patellar mobility for this group. LEVEL OF EVIDENCE: Diagnosis, level 5.

Sex differences in passive lateral and medial patellar mobility in healthy young adults.

BACKGROUND: Sex differences in passive patellar mobility have not been quantitatively evaluated. OBJECTIVE: The present study aimed to: 1) investigate sex differences in absolute and normalized patellar mobility, and 2) verify the relationship between patellar mobility and knee joint laxity. METHODS: Two hundred and five pain-free individuals (205 knees, 103 men, 102 women) participated. Passive lateral and medial patellar displacement was measured using a modified patellofemoral arthrometer and manual pushing method at 0∘ and 30∘ knee flexion angles. The absolute values of lateral and medial patellar displacement (LPD and MPD, respectively), and values normalized to patellar width (PW) and body height (HT) were used in the final analysis. RESULTS: At a 30∘ knee flexion angle, LPD/PW and LPD/HT were greater in women than in men (LPD/PW: 27.0 ± 6.7% vs. 22.6 ± 6.7%, LPD/HT: 0.81 ± 0.19% vs. 0.70 ± 0.15%, respectively, P< 0.001, effect size > 0.50). Absolute and normalized lateral and medial patellar mobility correlated positively with the range of the knee extension angle. CONCLUSIONS: Sex differences in LPD/PW and LPD/HT at a 30∘ knee flexion were detected in healthy subjects. Although the knee extension angle related to both the lateral and medial direction of the patellar mobility, the relations were only fairly correlated in asymptomatic young subjects.