Intraoperative evaluation of the effects of femoral component offset and head size on joint stability in total hip arthroplasty.

PURPOSE: To evaluate intraoperatively the effects of femoral offset and head size on stability of the hip joints in total hip arthroplasty (THA) via posterior approach. METHODS: Thirty cementless THAs were included in this study. After acetabular shell and femoral broach fixation, trial reduction was repeated using a femoral neck (5- to 8-mm higher or standard offset) and a head (26 mm or 32 mm). To evaluate joint stability, range of internal rotation (IR) in hip flexion prior to posterior subluxation and range of external rotation (ER) in hip extension were measured. RESULTS: The high-offset neck provided significantly (approximately 10°) greater range of IR to subluxation than the standard-offset neck. No hips ended in anterior subluxation by ER. The head size did not have significant effects on the stability. CONCLUSION: Results suggest that the 5- to 8-mm greater femoral offset might be effective in preventing instability in primary THA.

Hip, knee, and ankle kinematics during activities of daily living: a cross-sectional study.

BACKGROUND: Joint angle data from healthy subjects are necessary as baseline information. OBJECTIVE: To analyze the problems of patients who struggle with activities of daily living (ADL) due to restricted range of motion and to provide ADL guidance based on objective data. METHOD: An electromagnetic three-dimensional tracking system (FASTRAK) was used to quantify the hip, knee, and ankle angles of the dominant leg of 26 healthy adults as they performed 22 ADLs related to dressing, using the toilet, bathing, picking up objects, and crouching. For each ADL, the maximum angle was averaged across the 26 subjects. Mean angles of adduction/abduction and internal/external rotation during maximum hip flexion were also measured. RESULTS: The largest mean maximum angle was 101° for hip flexion (trunk rotation during crouching), 17° for hip adduction (putting on shoes), and 149° for knee flexion (trunk rotation during crouching). Analysis of adduction/abduction and internal/external rotation angles during maximum hip flexion showed the largest angle of adduction when putting on shoes, and the largest angle of internal rotation with trunk rotation during crouching. CONCLUSIONS: ADLs such as crouching and putting on pants showed larger joint angles than walking, climbing stairs, and standing up. Results obtained from this study can provide important objective data for ADL guidance for total hip arthroplasty and femoroacetabular impingement patients.

Effects of perioperative factors and hip geometry on hip abductor muscle strength during the first 6 months after anterolateral total hip arthroplasty.

[Purpose] The importance and effect of hip joint geometry on hip abductor muscle strength are well known. In addition, other perioperative factors are also known to affect hip abductor muscle strength. This study examined the relative importance of factors affecting hip abductor muscle strength after total hip arthroplasty. [Subjects and Methods] The subjects were 97 females with osteoarthritis scheduled for primary unilateral THA. The following variables were assessed preoperatively and 2 and 6 months after surgery: isometric hip abductor strength, radiographic analysis (Crowe class, postoperative femoral offset (FO)), Frenchay Activities Index, compliance rate with home exercise, Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), and demographic data. Factors related to isometric hip abductor muscle strength 2 and 6 months after surgery were examined. [Results] Significant factors related to isometric hip abductor muscle strength at 2 and 6 months after surgery were, in extraction order: 1. isometric hip abductor muscle strength in the preoperative period; 2. BMI; and 3. the JHEQ mental score at 2 and 6 months after surgery. [Conclusion] Preoperative factors and postoperative mental status were related to postoperative isometric hip abductor strength. FO was not extracted as a significant factor related to postoperative isomeric hip abductor strength.

Effect of Changing the Joint Kinematics of Knees With a Ruptured Anterior Cruciate Ligament on the Molecular Biological Responses and Spontaneous Healing in a Rat Model.

BACKGROUND: The poor healing capacity of a completely ruptured anterior cruciate ligament (ACL) has been attributed to an insufficient vascular supply, cellular metabolism, and deficient premature scaffold formation because of the unique intra-articular environment. However, previous studies have focused on intra-articular factors without considering extra-articular factors, including the biomechanical aspects of ACL-deficient knees. HYPOTHESIS: Changing the joint kinematics of an ACL-ruptured knee will improve cellular biological responses and lead to spontaneous healing through the mechanotransduction mechanism. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 66 skeletally mature Wistar rats were randomly assigned to a sham-operated group (SO), ACL-transection group (ACL-T), controlled abnormal movement group (CAM), and an intact group (IN). The ACL was completely transected at the midportion in the ACL-T and CAM groups, and the CAM group underwent extra-articular braking to control for abnormal tibial translation. The SO group underwent skin and joint capsule incisions and tibial drilling, without ACL transection and extra-articular braking. The animals were allowed full cage activity until sacrifice at 1, 2, 4, 6, and 8 weeks postoperatively for histological, molecular biological, and biomechanical assessment. RESULTS: All injured ACLs in the ACL-T group were not healed, but those in the CAM group healed spontaneously, showing a typical ligament healing response. Regarding the molecular biological response, there was an upregulation of anabolic factors (ie, transforming growth factor-ß) and downregulation of catabolic factors (ie, matrix metalloproteinase). Examination of the mechanical properties at 8 weeks after injury showed that >50% of the strength of the intact ACL had returned. CONCLUSION: Our results suggest that changing the joint kinematics of knees with a ruptured ACL alters the molecular biological responses and leads to spontaneous healing. These data support our hypothesis that the mechanotransduction mechanism mediates molecular responses and determines whether the ACL will heal. CLINICAL RELEVANCE: Elucidating the relationship between the mechanotransduction mechanism and healing responses in knees with completely ruptured ACLs may result in the development of novel nonsurgical treatment that enables the ACL to spontaneously heal in patients who are not suitable for reconstruction.

Bone Defect Regeneration by a Combination of a ß-Tricalcium Phosphate Scaffold and Bone Marrow Stromal Cells in a Non-Human Primate Model.

BACKGROUND: Reconstruction of large bone defects is a great challenge in orthopedic research. In the present study, we prepared composites of bone marrow-derived stromal cells (BMSCs) and ß-tricalcium phosphate (ß-TCP) with three novel aspects: proliferation of BMSCs with continuous dexamethasone treatment, cell loading under low pressure, and use of autologous plasma as the cell loading medium. The effectiveness of the resulting composite for large bone-defect reconstruction was tested in a non-human primate model, and the bone union capability of the regenerated bones was examined. MATERIALS AND METHODS: Primary surgery: Bone defects (5 cm long) were created in the left femurs of nine cynomolgus monkeys with resection of the periosteum (five cases) or without resection (four cases), and porous ß-TCP blocks were transplanted into the defects. Secondary surgery: Bone marrow aspirates harvested from seven of the nine monkeys were cultured with dexamethasone, and BMSCs were obtained. BMSCs were suspended in autologous plasma and introduced into a porous ß-TCP block under low-pressure conditions. The BMSC/ß-TCP composites were transplanted into bone defects created at the same sites as the primary surgery. Bone union evaluation: Five regenerated femurs were shortened by osteotomy surgery 8 to 15 months after transplantation of the ß-TCP/BMSC composites, and bone union was evaluated radiographically. RESULTS: After the primary surgery and treatment with ß-TCP alone, one of the five periosteum-resected monkeys and two of the four periosteum-preserved monkeys exhibited successful bone reconstruction. In contrast, five of the seven cases treated with the ß-TCP/MSC composite showed successful bone regeneration. In four of the five osteotomy cases, bone union was confirmed. CONCLUSION: We validated the effectiveness of a novel ß-TCP/BMSC composite for large bone defect regeneration and confirmed the bone union capability of the regenerated bone.

Effects and feasibility of exercise therapy combined with branched-chain amino acid supplementation on muscle strengthening in frail and pre-frail elderly people requiring long-term care: a crossover trial.

This study examined the effects and feasibility of a twice-weekly combined therapy of branched-chain amino acids (BCAAs) and exercise on physical function improvement in frail and pre-frail elderly people requiring long-term care. We used a crossover design in which the combination of exercise and nutritional interventions was carried out twice a week during cycles A (3 months) and B (3 months) and the exercise intervention alone was performed during the washout period. The exercise intervention entailed the following 5 training sets: 3 sets of muscle training at 30% of maximum voluntary contraction, 1 set of aerobic exercise, and 1 set of balance training. For the nutritional intervention, 6 g of BCAAs or 6 g of maltodextrin was consumed 10 min before starting the exercise. We determined upper and lower limb isometric strength, performance on the Functional Reach Test (FRT) and the Timed Up and Go test, and activity level. In the comparison between the BCAA group and the control group after crossover, the improvement rates in gross lower limb muscle strength (leg press, knee extension) and FRT performance were significantly greater (by approximately 10%) in the BCAA group. In the comparison between different orders of BCAA administration, significant effects were shown for the leg press in both groups only when BCAAs were given. The combination of BCAA intake and exercise therapy yielded significant improvements in gross lower limb muscle strength and dynamic balance ability.

Biomechanical evaluation of the rabbit tibia after implantation of porous hydroxyapatite/collagen in a rabbit model.

PURPOSE: Porous hydroxyapatite/collagen composite (HAp/Col) is an artificial bone substitute with excellent osteoconduction and sponge-like elasticity. However, the porosity of porous HAp/Col is as high as 95% and its mechanical strength is very poor. The aim of this study was to biomechanically analyze sites implanted with porous HAp/Col. METHODS: Rectangular cortical bone defects (3 × 8 mm) were made in the tibia of rabbits and filled with porous HAp/Col or porous ß-tricalcium phosphate or left vacant. The tibia was harvested at 4 or 12 weeks after surgery. The harvested specimens were analyzed using a micro-CT system, and the mechanical strength of the specimens was examined by torsion testing. RESULTS: Quantitative micro-CT analysis of the regenerated bone revealed that both bone substitutes equally facilitated bone regeneration. Biomechanical testing demonstrated that the torsional strength of HAp/Col-implanted sites was higher than that of the control (vs control: p = 0.030 and vs ß-TCP: p = 0.056). CONCLUSIONS: The results indicate that porous HAp/Col implantation is an effective strategy for recovery of the mechanical strength of bone defects.

Incidence of floating toe and its association with the physique and foot morphology of Japanese children.

[Purpose] Physical development, foot morphology, and toe contact of children aged 3 to 5 years were assessed in order to investigate the relationships between body and foot morphology and the incidence of the condition known as "floating toe". [Subjects] A total of 198 children, aged 3 to 5 years old, participated in this study. [Methods] Height and weight were measured for body morphology, and foot length and width were measured for foot morphology. Footprint images were taken to calculate the number of floating toes. Information about the children's height and weight at birth, and the time of starting to walk was obtained from their guardians. [Results] At least one floating toe was observed in 87.7-98.7% of the children depending on their ages. The fifth toe was most commonly affected, occurring in 74.2% of the study population. Among the body and foot morphology parameters, only weight at birth showed a significant but very weak correlation with the number of floating toes. [Conclusion] There was a high incidence of floating toe among the children, with the fifth toe most commonly affected. Floating toe weakly but significantly correlated with weight at birth, but did not correlated with other measures of physique at birth, physical development, or the time of starting to walk.

Pivotal role of Sirt6 in the crosstalk among ageing, metabolic syndrome and osteoarthritis.

Osteoarthritis (OA) is a chronic degenerative joint disorder commonly associated with metabolic syndrome. As ageing and obesity has a great impact on the initiation/severity of OA, herein we sought to investigate the involvement of Sirt6 in the crosstalk between ageing and metabolic syndrome/OA. Sirt6 haploinsufficiency in mice promoted the expression of inflammatory cytokines in the IPFP. Enhanced inflammation of the IPFP in the aged Sirt6 ± HFD group was paralleled with accelerated OA change, including osteophyte growth and chondrocyte hypertrophy. Conversely, mesenchyme-specific Sirt6-deficient mice revealed both attenuated chondrocyte hypertrophy and proteoglycan synthesis, although chondrocyte senescence was enhanced as shown in the aged WT mice. Thus Sirt6 has key roles in the relationship among ageing, metabolic syndrome, and OA.

Sirt6 regulates postnatal growth plate differentiation and proliferation via Ihh signaling.

Sirtuin 6 (Sirt6) is a mammalian homologue of NAD⁺-dependent histone deacetylase Sir2. Although Sirt6⁻/⁻ mice exhibit growth retardation, the role of Sirt6 in cartilage metabolism is unclear. The aim of this study was to investigate the Sirt6 signaling pathway in cartilage metabolism. Immunohistological evaluation of the tibial growth plate in Sirt6⁻/⁻ mice exhibited impaired proliferation and differentiation of chondrocytes, reduced expression of Indian hedgehog (Ihh), and a senescent phenotype. When Sirt6 was knocked down in chondrocytes in vitro, expression of Ihh and its downstream genes were reduced. Impaired differentiation by Sirt6 silencing was completely rescued by administration of a Hh signal agonist. When sirtuins were activated, chondrocyte differentiation was enhanced together with activation of Ihh signal, and these effects were abrogated by Sirt6 silencing. ChIP assay revealed the affinity of ATF4 to the Ihh promoter was markedly decreased by Sirt6 knockdown. These data indicate Sirt6 directly controls proliferation and differentiation of chondrocytes.

Ranges of active joint motion for the shoulder, elbow, and wrist in healthy adults.

PURPOSE: The aim of this study was to show highly reliable normal values and three-dimensional characteristics for final range of motion during active movements of the upper extremity joints, and to develop a database from healthy participants, with the advantage of this database lying in the methods of defining shoulder axial rotation angle and of compensating for soft tissue artifacts. METHODS: We used an electromagnetic tracking system (FASTRAK) to measure three-dimensional motions of the shoulder (thoracohumeral), elbow/forearm, and wrist in 20 healthy adults (age range: 18-34 years) during active joint motion tasks of the upper extremity. RESULTS: Joint angles of the upper extremity at the final position of joint motion tasks were determined. Highly reliable data for shoulder axial rotation angle were obtained, using a new definition of joint angle and regression analysis to compensate for estimation errors. CONCLUSIONS: These results should be useful in setting goals for the treatment of upper extremity joint functions in the fields of rehabilitation, orthopedics, and sports medicine.

Comparison of different distal designs of femoral components and their effects on bone remodeling in 1-stage bilateral total hip arthroplasty.

To evaluate the effects of distal design of a proximally coated femoral component on periprosthetic bone remodeling, we prospectively performed 21 one-stage bilateral total hip arthroplasties using a distally tapered and a distally cylindrical stem with the same proximal design, randomized to side. All hips showed good outcomes clinically and radiographically at the final follow-up, average of 7 years postoperatively. Cancellous condensation was always found in Gruen's zones 2 and 6 around the cylindrical stem and in regions between zones 2 and 3 and between zones 6 and 5 around the tapered stem. Bone mineral density of Gruen's zones 2 and 6 was significantly lower around the tapered stem. These results suggested more distal loading in hips with the tapered stem than in those with the cylindrical stem.

The effect of mastication on reaction latency to unanticipated external disturbances in the standing position.

Previous research has shown that mastication reduces shifts in the center of gravity of persons standing still. The present research was conducted to determine whether mastication improves reactive balance in the standing position in response to unanticipated external disturbances. The subjects were 32 healthy male adults (mean age 21.1 years, standard deviation (SD) 0.7 years). Latency data determined with the Motor Control Test of Computerized Dynamic Posturography (CDP) were compared for the three conditions of mastication status, the direction of translation, and the magnitude of translation, using three-way repeated measures ANOVA and lower-order ANOVA with the three conditions separated. Latency was significantly shorter with mastication than with the lower jaw relaxed (P < 0.00001). Mastication alone, however, cannot be considered significant because of the complex interactions involved among the three conditions. Mastication increases not only static balance but also reactive balance in response to unanticipated external disturbances. Gum chewing may therefore reduce falls among elderly persons with impaired balance.

Three-dimensional motion of the upper extremity joints during various activities of daily living.

Highly reliable information on the range of motion (ROM) required to perform activities of daily living (ADL) is important to allow rehabilitation professionals to make appropriate clinical judgments of patients with limited ROM of the upper extremity joints. There are, however, no data available that take full account of corrections for gimbal-lock and soft tissue artifacts, which affect estimation errors for joint angles. We used an electromagnetic three-dimensional tracking system (FASTRAK) to measure the three-dimensional ROM of the upper extremity joints of healthy adults (N=20, age range 18-34) during 16 ADL movement tasks. The ROM required for the performance of each movement was shown in terms of the joint angle at the completion of the task, using a new definition of joint angle and regression analysis to compensate for estimation errors. The results of this study may be useful in setting goals for the treatment of upper extremity joint function.

Evaluation of the age-related changes in movement smoothness in the lower extremity joints during lifting.

The purpose of this study was to analyze age-related movement smoothness changes in the lower extremity joints during load lifting. A total of 10 young and 13 elderly subjects participated in the study. Infrared reflective markers were attached to body landmarks in each subject. While the subjects stood on force plates and lifted a box, the marker displacements and ground reaction forces were measured using a 3D motion analysis system. The jerk square mean value (JSM) was defined as the lower extremity joint movement smoothness index during lifting. JSM represented the average of the square of the joint angle third derivative value, according to the jerk third derivative of the position data. Each subject's JSM values were calculated for the hip, knee and ankle joints. Movement smoothness appeared to decrease as JSM increased. Multiple regression analyses were performed for dependent variables (hip, knee and ankle joint JSM values) and independent variables (age, hand grip strength, sex difference and lifting duration). The level of significance was set at p<0.05. For the hip joint JSM, the regression coefficient for age was significantly positive and that for lifting duration was significantly negative. For the knee joint JSM, the regression coefficient for lifting duration was significantly negative. For the ankle joint JSM, the regression coefficients for age and hand grip strength were significantly positive and that for lifting duration was significantly negative. These results suggest that movement smoothness in the hip and ankle joints during lifting decreases with advancing age.

The effect of preoperative lateral flexibility of the lumbar spine on perceived leg length discrepancy after total hip arthroplasty.

BACKGROUND: Leg length discrepancy (LLD) after total hip arthroplasty (THA) is a significant factor of patient dissatisfaction. Patients with dissociation between preoperative radiographic LLD and perceived LLD sometimes feel LLD postoperatively even if bilateral leg lengths are equal. There is no publication describing how to decide the amount of leg lengthening in such cases. PURPOSE: By examining the influence of preoperative lumbar lateral flexibility on postoperative perceived LLD, this study aims at creating a guideline for the optimal planning of leg lengthening in THA. METHODS: In 59 cases undergoing primary unilateral THA, radiographic LLD, perceived LLD, pelvic tilting and lumbar lateral flexibility were measured preoperatively. The amount of leg lengthening and the sequential change of the perceived LLD were measured postoperatively. RESULTS: Twelve cases (20%) felt the perceived LLD at two years after surgery. All these cases felt the operative side longer than the non-operative side. In 32 cases with preoperative pelvic inclination to the affected side, postoperative perceived LLD was significantly greater if lumbar spine was rigid. In eight cases with pelvic tilting and rigid lumber spine, the amount of leg lengthening that exceeded preoperative perceived LLD affected the postoperative perceived LLD. CONCLUSIONS: In cases with preoperative pelvic inclination downward to the affected side and with rigid lumbar spine, amount of leg lengthening should not be excessively greater than preoperative perceived LLD. In other cases, lengthening the leg to the same length as the contralateral side rarely results in postoperative perceived LLD.

Postoperative hip motion and functional recovery after simultaneous bilateral total hip arthroplasty for bilateral osteoarthritis.

BACKGROUND: Simultaneous bilateral total hip arthroplasty (THA) can offer a potential benefit of greater postoperative hip motion without the negative influence of contralateral hip disabilities, compared to two-stage THA. However, postoperative changes in hip motion after simultaneous bilateral THA have rarely been reported. The purpose of this study was to clarify the efficacy of simultaneous procedures on postoperative hip motion and functional recovery. METHODS: We retrospectively compared hip motion in 27 patients treated with simultaneous bilateral THA to those in 11 patients with two-stage bilateral THA, 35 patients with unilateral THA for unilateral disease, and 15 patients with unilateral THA for bilateral disease. We also evaluated the clinical manifestations according to the Japanese Orthopaedic Association (JOA) hip scores and compared the outcomes among the groups. All of the THA surgeries were primarily performed through a posterolateral approach using cement-less prostheses. The diagnosis at surgery was dysplastic osteoarthritis in all patients, and the patients were followed up for at least 4 years. RESULTS: The postoperative improvement of motion in hip flexion was significantly greater in patients treated with simultaneous procedures compared to patients with two-stage THA and unilateral THA for bilateral disease. The differences in improvement of motion in hip abduction were less marked than the improvement in hip flexion among the groups. Although there were no significant differences in pain scores among the groups, the values for activity of daily living were significantly greater in patients treated with simultaneous bilateral THA and patients with unilateral THA for unilateral disease than in patients with unilateral and two-stage bilateral THA for bilateral disease. CONCLUSIONS: The simultaneous procedure was considered to be more effective in patients with bilateral hip osteoarthritis and demonstrated a substantial improvement in hip motion and functional recovery after THA.

A proposal for a new definition of the axial rotation angle of the shoulder joint.

The Euler/Cardan angles are commonly used to define the motions of the upper arm with respect to the trunk. This definition, however, has a problem in that the angles of both the horizontal flexion/extension and the axial rotation of the shoulder joint become unstable at the gimbal-lock positions. In this paper, a new definition of the axial rotation angle was proposed. The proposed angle was stable over the entire range of the shoulder motion. With the new definition, the neutral position of the axial rotation agreed with that in the conventional anatomy. The advantage of the new definition was demonstrated by measuring actual complex motions of the shoulder with a three-dimensional motion capture system.

Development of new bone cement utilizing low toxicity monomers.

Acrylic bone cement is self-curing cement comprising of liquid and powder component of methyl methacrylate (MMA). It has been used extensively in orthopedics; however, adverse effects were associated with its use. Hence we investigated in this paper the possibility of new cement utilizing methacrylates with lower toxicity than MMA. LD50s of candidate monomers were determined with administration to the medullary cavity of the rat's femur. 2-Ethylhexyl methacrylate (EHMA) and trimethylolpropane trimethacrylate (TMP) demonstrated greater LD50 values of 187 mg/kg and 380 mg/kg, respectively, than MMA (108 mg/kg); they were selected as the liquid components of the new cement. The copolymer of EHMA and cyclohexyl methacrylate was then selected as the powder component. With this combination, we developed the new cement (EHMA cement).Temperature rise during polymerization of EHMA cement was 9 degrees C-13 degrees C, which was significantly lower than that of conventional cement. The compression strength of the polymerized EHMA cement was 57 MPa without TMP, and 67 MPa with TMP (15 wt%). Thus we concluded that new EHMA cement was slightly inferior in the compression strength than the conventional cement. However, it was characterized by the low toxicity of utilized monomers and the low temperature rise during polymerization.

Range of motion measurement of an artificial hip joint using CT images.

Total hip arthroplasty (THA) is one of the most effective treatments for osteoarthritis and rheumatoid arthritis. Dislocation of the femoral head from the acetabular socket is a major problem of THA. To prevent dislocation, it is important to know the range of motion (ROM) after THA. Although various studies on the ROM were carried out, there exist only a few reports on ROM evaluation in individual patients. This is because in clinical cases, bone-to-bone and bone-to-component contacts must be considered besides the impingement of components. In this study, a new method for evaluating ROM of internal/external rotation, which takes into account all combinations of contacts between the bones and components, was proposed. A computer simulation demonstrated that the RMS error of the proposed method was approximately 3 degrees . The method was applied to 33 THAs under various conditions of flexion and adduction angles. The method was able to detect any type of impingement. The evaluated ROM was in good agreement with that measured during the THA operation (correlation coefficient = 0.91).