Yutaka Kuroda

Effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in individuals with hip osteoarthritis: a randomized controlled trial

Objective: To investigate the effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in patients with hip osteoarthritis by comparison with those of low-velocity resistance training. Design: Single-blind randomized controlled trial. Setting: Home-based exercise programmes. Subjects: A total of 46 women with hip osteoarthritis were randomly assigned to the high-velocity (n = 23) or low-velocity (n = 23) training group. Interventions: Both groups underwent an eight-week daily home-based resistance training programme using an elastic band. Exercises involved hip abduction, extension, and flexion and knee extension. Participants in the high-velocity group performed the concentric phase of each repetition as rapidly as possible and returned to the initial position eccentrically in 3 s. Participants in the low-velocity group performed both the concentric and eccentric phases in 3 s. Main measures: The following outcome measures were evaluated: isometric muscle strength, muscle power, muscle thickness, muscle echo intensity, maximum walking speed, Timed Up and Go test, 3-minute walking test, Harris Hip Score, and hip pain. Results: Decreases in the time for performing the Timed Up and Go test (mean changes: high-velocity group −0.46 s, low-velocity group −0.23 s) and echo intensity of the gluteus maximus (mean changes: high-velocity group −6.8, low-velocity group −1.0) were significantly greater in the high-velocity group than in the low-velocity group. No significant difference was observed in changes of other outcome measures between the groups. Conclusion: This study revealed that high-velocity training for patients with hip osteoarthritis has partially a greater effect on muscle properties and physical performance than low-velocity training.

Muscle Mass and Composition of the Hip, Thigh and Abdominal Muscles in Women With and Without Hip Osteoarthritis

The objective of this study was to compare muscle mass and composition between individuals with and without hip osteoarthritis. Twenty-four women with hip osteoarthritis (OA group) and 16 healthy women (healthy group) participated in this study. Muscle thickness (MT) and echo intensity (EI) were measured as indices of muscle mass and composition, respectively, using ultrasound imaging. Seven muscles were examined: gluteus maximus, gluteus medius, quadriceps femoris, rectus abdominis, external oblique, internal oblique and transversus abdominis. MT of only quadriceps femoris in the OA group was significantly thinner than that in the healthy group. EIs of gluteus medius, quadriceps femoris and rectus abdominis were significantly higher in the OA group than those in the healthy group. Thus, actual contractile tissue of gluteus medius and rectus abdominis substantially decreased, although muscle mass was similar, whereas both quantitative and qualitative changes occurred in quadriceps femoris in patients with hip OA.

Effect of titania-based surface modification of polyethylene terephthalate on bone–implant bonding and peri-implant tissue reaction

Organic polymers can be uniformly surface-modified with bioactive TiO(2) by using a sol-gel method. Titania-based surface-modified polyethylene terephthalate (TiPET) plates and fabric have shown apatite-forming ability in simulated body fluid. Here, we first investigated the bone-bonding ability and mechanical bonding strength between the surface-modified layer and the base material (PET) of TiPET plates in vivo. For clinical applicability, we also examined the bone-bonding ability of TiPET fabric and the effect of titania-based surface modification on peri-implant tissue reactions (e.g. connective tissue capsule formation) in bone in vivo. Solid PET plates and PET fabric were prepared. Test plates and fabric were surface-modified with titania solution by using a sol-gel method. Histological examinations of the plates implanted into rabbit tibiae revealed direct contact between the TiPET plate and the bone. After the detaching test, a considerable amount of bone residue was observed on the surface of the TiPET plate. This result suggests that the mechanical bond strength between surface-modified layer and the base material is stronger than that between newly generated bone and tibia, and indirectly ensures the mechanical stability of the surface-modified layer. Pulling tests and histological examinations of the TiPET fabric revealed its excellent bone-bonding ability and micro-computed tomographic images showed excellent osteoconductive ability of TiPET fabric. The connective tissue capsule was much thinner, with less inflammatory tissue around the TiPET implants than around the control samples. These results indicate that TiPET fabric possesses a mechanically stable surface-modified layer, excellent bone-bonding ability, osteoconductive ability, and biocompatibility in bone.

Minimum 10-Year Wear Analysis of Highly Cross-Linked Polyethylene in Cementless Total Hip Arthroplasty

Fifty-four patients (64 hips) underwent cementless total hip arthroplasty between 2000 and 2003 with a 22-mm zirconia ceramic bearing on highly cross-linked polyethylene, and were evaluated with a mean 11.9-year postoperative follow-up (range, 10-14 years). Linear wear was measured on the anteroposterior radiograph of the hip. No evidence of osteolysis and loosening was found on the final radiograph in any of the cases, and the steady-state linear wear rate was 0.017±0.018 mm/year. No significant correlation was found between the linear wear rate and age, body weight, cup inclination angle, or polyethylene thickness. Highly cross-linked polyethylene showed excellent wear resistance for >10 years when used in combination with 22-mm zirconia heads.

Pelvic instability and trunk and hip muscle recruitment patterns in patients with total hip arthroplasty.

Hip and lumbar spine disorders often coexist in patients with total hip arthroplasty (THA). The current study aimed to reveal pelvic motion pathology and altered trunk and hip muscle recruitment patterns relating to pelvic motion in patients with THA. Twenty-one women who underwent THA and 12 age-matched healthy women were recruited. Pelvic kinematics and muscle recruitment patterns (i.e., amplitude, activity balance, and onset timing) of the gluteus maximus, semitendinosus, multifidus, and erector spinae were collected during prone hip extension. Compared with healthy subjects, the patients showed increased pelvic motion, especially ventral rotation, decreased multifidus muscle activity relative to the hip extensors, and delayed onset of multifidus activity, despite reaction times and speeds of leg motion not being significantly different between the groups. Furthermore, while contributing factors associated with ventral pelvic rotation were not found, delayed onset of multifidus activity was detected as a factor related to the increased anterior tilt of the pelvis (r = 0.47, p < 0.05) in patients with THA. These results suggest that patients with THA have dysfunction of the stabilizer muscles of the lumbopelvic region along with increased pelvic motion.

Compensatory turning strategies while walking in patients with hip osteoarthritis

The ability to change directions while walking is an integral component of adaptive locomotor behavior. Patients with hip osteoarthritis (OA) experience prolonged hip dysfunction. Gait compensation adopted by the patients with hip OA may become more pronounced while they turn. The purposes of this study were to identify the turning strategy while walking in patients with hip OA, and to examine the relationship between the turning strategy and the patients functional level. Fourteen patients with hip OA and 13 age-matched healthy controls were recruited. The hip, knee, and ankle joint angles and moments, and the foot progression angle were measured under three walking conditions (straight walking, 45° step turn, and 45° crossover turn), and the gait variables for each walking condition were compared between the 2 groups. The relationship between the increasing rate of knee and ankle joint moments in the turning to the straight walking and the functional point in the Harris hip score (HHS) was examined. The OA group showed decreased hip flexion, extension, and abduction angles, and hip flexion moment during the step turn, and decreased hip flexion, extension, and adduction angles, and hip abduction moment during the crossover turn. Furthermore, the ankle plantarflexion moment and the change in the foot angle during the stance phase were significantly increased during the crossover turn in the OA group. The increasing rate of the ankle plantarflexion moment correlated significantly with the functional point in the HHS. Patients with hip OA rely primarily on the ankle plantarflexors to compensate for the hip dysfunction while changing the walking direction.

Hip external rotator exercise contributes to improving physical functions in the early stage after total hip arthroplasty using an anterolateral approach: a randomized controlled trial

Abstract Purpose: The purpose of this study was to investigate the effects of an exercise program focusing on hip external rotator muscle on physical recovery in the early post-operative period of total hip arthroplasty (THA). Methods: Patients who underwent THA were randomized to an exercise group (n = 14) or a control group (n = 14). In exercise group, the hip external rotator exercise program was performed 5 times per week for four weeks. Outcome measures were hip pain, hip range of motion, muscle strength of lower extremity and Timed Up and Go (TUG) test. Results: Both the hip abductor strength (effect size = 0.60) and TUG test (effect size= −0.53) in the exercise group improved significantly after the intervention. Conclusions: The results of the present study demonstrated that exercise program focusing on hip external rotator muscle was an effective intervention, especially in improving both hip abductor strength and walking ability in the acute post-THA stage. Implication for Rehabilitation After THA, in order to safely progress patients back to their desired activity level, there is a need to develop rehabilitation strategies to expedite and promote the recovery during the acute postoperative period. Exercise program focusing on hip external rotator muscle may lead to significant improvement of hip abductor muscle strength and gait ability in the acute post-THA stage.

Good short-term outcome of primary total hip arthroplasty with cementless bioactive glass ceramic bottom-coated implants: 109 hips followed for 3–9 years.

Background and purpose Cementless total hip arthroplasty is currently favored by many orthopedic surgeons. The design of the porous surface is critically important for long-term fixation. We examined the clinical and radiographic outcome of the cementless titanium hip implant with a bottom coating of apatite-wollastonite containing bioactive glass ceramic. Methods We retrospectively reviewed 109 hips (92 patients) that had undergone primary cementless total hip arthroplasty with bioactive glass ceramic bottom-coated implants. The mean follow-up period was 7 (3–9) years. Hip joint function was evaluated with the Merle d’Aubigné and Postel hip score, and radiographic changes were determined from anteroposterior radiographs. Results The mean hip score improved from 9.7 preoperatively to 17 at the final follow-up. The overall survival rate was 100% at 9 years, when radiographic loosening or revision for any reason was used as the endpoint. 3 stems in 2 patients subsided more than 3 mm vertically within 1 year after implantation. Radiographs of the interface of the stem and femur were all classified as bone ingrowth fixation. Conclusions The short-term results of this study show good outcome for cementless implants with a bottom coating of apatite-wollastonite containing bioactive glass ceramic.

Associations of radiographic degeneration and pain with daily cumulative hip loading in patients with secondary hip osteoarthritis.

The purpose of this study was to investigate the associations of radiographic and clinical variables of hip osteoarthritis (OA) with alterations in gait and joint loading in patients with secondary hip OA. Fifty females with secondary hip OA were participated. The minimum joint space width (mJSW) of the hip as a degenerative sign and Sharp and center edge (CE) angles as morphological variables were measured radiographically. Hip joint pain was assessed using a visual analog scale. As gait variables, walking speed, range of hip motion, hip moment peak, and hip moment impulse were calculated. Daily cumulative hip loading was calculated as the hip moment impulse multiplied by the mean number of steps per day. After bivariate correlation analyses between dependent (mJSW and pain) and independent variables (age, body mass index, sharp/CE angles, steps per day, and gait variables), separate forward‐backward stepwise multiple regression analyses were performed for each dependent variable. Daily cumulative hip loading in the sagittal plane (β = 0.30, p = 0.021) and age (β = −0.36, p = 0.007) were significantly associated with the mJSW. Walking speed (β = −0.36, p = 0.008) and age (β = 0.29, p = 0.031) were significantly associated with hip joint pain. Decrease in daily cumulative hip loading in the sagittal plane was associated with mJSW independently of age. Although the causal relationship was not clear, patients with hip OA reduced total exposure to hip joint loading adaptively rather than lowering the hip moment peak concerning worsening of hip degeneration.

Factors associated with restricted hip extension during gait in women after total hip arthroplasty.

Purpose A decreased peak hip extension angle in the late stance phase is a major gait abnormality in patients with THA. The purpose of this study was to determine the relationship between peak hip extension angle during gait and functional impairments such as muscle weakness and the limitation in joint range of motion and to identify the clinical factors influencing peak hip extension angle during gait. Methods 67 female volunteers with THA were examined. Biomechanical gait analysis was performed to measure peak hip extension angle during gait. Maximal isometric strength of the hip and knee, passive hip extension range of motion, leg length discrepancy, and hip pain were assessed. Results Peak hip extension angle during gait significantly correlated with passive hip extension range of motion (r = 0.259), hip pain (r = −0.264), isometric strengths of the hip musculature (r = 0.278-0.491), and knee extensor (r = 0.386). Stepwise multiple regression analysis revealed that hip abductor torque (β = 0.355, P = 0.001), hip pain (β = −0.353, P = 0.001), and passive hip extension range of motion (β = 0.258, P = 0.011) were significant contributors to peak hip extension angle during gait (R2 = 0.408). Conclusions Our findings suggest that THA rehabilitation aimed at improving gait ability should focus on strengthening the hip abductors, controlling hip pain and increasing range of motion of hip extension.