In vivo loading on the hip joint in patients with total hip replacement performing gymnastics and aerobics exercises

Evaluation of an early-stage prototype polyurethane femoral head implant for hip arthroplasty

Introduction

Thi study evalautes a new bone-preserving femoral head cover that mimics the articular cartilage of the femoral head.

Methods

A specially developed polyurethane (PU) was evaluated in biocompatibility (cytotoxicity test) and mechanical response to tensile loading. In the cytotoxicity test, steam sterilized (SS) and ethylene oxide sterilized (EtO) PU samples were incubated separately in a cell culture medium. The seeded cell line MG-63 was then added to these sample-incubated cell culture mediums. One negative control group and one positive control group were also evaluated. The cells in each group were cultured for seven days before being quantified using the alamarBlue assay. In the mechanical test, the femoral head cover implants were separated into three groups of three samples. Each group represented a different implant insertion idea: direct insertion (uc sample) and another two insertion modes (is and ss samples) representing implants with enclosure mechanisms. The test consisted of distance-controlled cyclic tensile loadings followed by a failure test.

Results

The cytotoxicity test results show no significant difference in fluorescence intensity between the negative control, the three SS groups, and one EtO group (P > 0.05). However, the other two EtO groups exhibit significantly lower fluorescence intensity compared with the negative control (P < 0.05). In the mechanical test, the is samples have the highest cyclic loading force at 559.50 ± 51.41 N, while the uc samples exhibit the highest force in the failure test at 632.16 ± 50.55 N. There are no significant differences (P > 0.05) among the uc, is, and ss groups in terms of stiffness.

Conclusion

The cytotoxicity test and the mechanical experiment provide initial assessments of the proposed PU femoral head cover implant. The evaluation outcomes of this study could serve as a foundation for developing more functional design and testing methods, utilizing numerical simulations, and developing animal/clinical trials in the future.

A novel primary stability test method for artificial acetabular shells considering vertical load during level walking and shell position

Uncemented acetabular shell primary stability is essential for optimal clinical outcomes. Push-out testing, rotation testing, and lever-out testing are major evaluation methods of primary stability between the shell and bone. However, these test methods do not consider shell loads during daily activity and shell installation angle. This study proposes a novel evaluation method of acetabular shell primary stability considering load during level walking and acetabular installation angles such as inclination and anteversion. To achieve this, a novel primary stability test apparatus was designed with a shell position of 40° acetabular inclination and 20° anteversion. The vertical load, corresponding to walking load, was set to 3 kN according to ISO 14242-1, which is the wear test standard for artificial hip joints. The vertical load was applied by an air cylinder controlled by a pressure-type electro-pneumatic proportional valve, with the vertical load value monitored by a load cell. Torque was measured when angular displacement was applied in the direction of extension during the application of vertical load. For comparison, we also measured torque using the traditional lever-out test. The novel primary stability test yielded significantly higher primary stabilities; 5.4 times greater than the lever-out test results. The novel primary stability test failure mode was more similar to the clinical failure than the traditional lever-out test. It is suggested that this novel primary stability test method, applying physiological walking loads and extension motions to the acetabular shell, better reflects in vivo primary stability than the traditional lever-out test.

Lower-limb internal loading and potential consequences for fracture healing

Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success. Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach. Results: Mean peak forces differed with femoral compression (1,330-1,936 N at mid-shaft) amounting to about half of tibial compression (2,299-5,224 N). Mean peak bending moments in the frontal plane were greater in the femur (71-130 Nm) than in the tibia (from 26 to 43 Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (-38 to 43 Nm) reaching substantially higher values in the tibia (-63 to -175 Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (-13 to -40 Nm) versus tibia (15-48 Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up (p < 0.001) compared to tibial fractures. Specifically, compression (r = 0.304), sagittal bending (r = 0.259), and frontal bending (r = -0.318) showed strong associations (p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone. Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level.

Differences in hip musculoskeletal loads between limbs during daily activities in patients with 3D-printed hemipelvic reconstructions following tumor surgery

BACKGROUND

Anatomical custom-made prostheses, thanks to computer-aided design and 3D-printing technology, help improve osseointegration and reduce mechanical complications in bone reconstructions following bone tumors. A recent quantitative analysis of long-term recovery in patients with 3D-printed reconstructions following pelvic tumor surgery showed asymmetries in ground reaction forces between limbs during different motor activities, while standing very good motor performance and quality of life.

RESEARCH QUESTION

We analyzed hip contact forces and muscle forces in that cohort of six patients with an innovative custom-made reconstruction of the hemipelvis, and we tested the hypothesis that asymmetries in ground reaction forces would result in more marked differences in musculoskeletal forces.

METHODS

State-of-the-art musculoskeletal modeling in an optimization-based inverse-dynamics workflow was used to calculate hip contact forces and muscle forces during five motor activities, and the differences between limbs were statistically evaluated across the motor activity cycles and on the force peaks.

RESULTS

The musculoskeletal loads were found to be not symmetric, as hip loads were generally higher in the contralateral limb. We found significant differences in considerable portions of the motor activities cycles except squat, load symmetry indices indicating a load increase (median up to 25%) on the contralateral limb, especially during stair descent and chair rise/sit, and significantly higher values in the contralateral limb at force peaks.

SIGNIFICANCE

We confirmed the hypothesis that residual asymmetries found in ground reaction forces were amplified when hip musculoskeletal loads were investigated, reflecting a shift of the loads toward the intact limb. Despite the general trend of higher loads found in the contralateral hip, this cannot be considered a risk of overloading, as both hips supported loads in a physiological range or lower, indicating a likely optimal recovery.

EFFECTS OF BODY POSTURE TRAINING ON AEROBIC PERFORMANCE

ABSTRACT Introduction: The intensity of daily training increases with the development of aerobics, presenting a series of requirements for students’ body posture and sports performance. Objective: Study the effect of postural training on the performance of university students practicing aerobics. Methods: The experiment lasted nine weeks, performed three times a week. The control group was trained according to traditional aerobics teaching, while the experimental group was introduced to practice dance movements based on aerobics training to strengthen postural teaching. Results: The total performance score of the experimental group before the experiment was 70.32 points, which rose to 80.19 points, representing an increase of 12.30%; the initial performance score of the control group was 68.13 points, rising to 75.32 points, an increase of 9.54%. Conclusion: Body posture training can optimize students’ physical fitness and flexibility, improving their artistic expression skills and aerobic expression scores, and should be promoted. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Effects of Incontro, Alleanza, Responsabilita, Autonomia Intervention Model Combined with Orem Self-Care Model and the Use of Smart Wearable Devices on Perceived Stress and Self-Efficacy in Patients after Total Hip Arthroplasty

Objective

To explore the effects of Incontro, Alleanza, Responsabilita, Autonomia (IARA) combined with Orem self-care model and the use of smart wearable devices on perceived stress and self-efficacy in patients after total hip arthroplasty (THA).

Methods

A total of 60 patients after THA in our hospital were enrolled. Patients were randomly divided into control group (IARA intervention model combined with Orem self-care model) and study group (intelligent wearable device combined conference-IARA and Orem self-care model). Harris hip function score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, functional independence measure (FIM) score, social support level, perceived stress, and self-efficacy were compared between the two groups.

Results

Harris hip function score, WOMAC score, FIM score, and the level of social support of the study group were higher compared with the control group after operation (P < 0.05). Additionally, the perceptual pressure in the study group was lower compared with the control group after intervention (P < 0.05). The self-efficacy of the two groups was compared, and the self-efficacy of the study group was higher than that of the control group at 4, 6, 8, and 12 weeks after the intervention, and the difference was statistically significant (P < 0.05).

Conclusion

Patients after THA utilize an intelligent wearable device combined with IARA model and Orem self-care model, which can effectively reduce awareness pressure, improve self-efficacy, and facilitate the improvement of the hip fracture.

Effect of Rehabilitation Nursing under the Guidance of the Health Action Process Approach Model on Perioperative Nursing Effect of Artificial Hip Arthroplasty: Effect on Promoting Quality of Life and Postoperative Rehabilitation

Objective

To explore the influence of rehabilitation nursing under the guidance of Health Action Process Approach (HAPA) model on the perioperative nursing effect of artificial hip replacement and to analyze the effect of this nursing model on the quality of life and postoperative rehabilitation of patients undergoing artificial hip replacement.

Methods

A total of 200 patients with hip arthroplasty treated in our hospital from January 2019 to July 2021 were enrolled. The patients were randomly assigned into the control group and study group. The former received routine nursing, and the latter received rehabilitation nursing under the guidance of the HAPA model. Nursing satisfaction, pain score, Harris hip function score, timed stand-up-walk test, MBI score, and quality of life score were compared.

Results

First of all, we compared the nursing satisfaction. In the study group, 86 cases were very satisfied, 8 cases were satisfied, and 6 cases were general; the satisfaction rate was 100%. In the control group, 48 cases were very satisfied, 22 cases were satisfied, 12 cases were general, and 18 cases were dissatisfied; the satisfaction rate was 82.0%. The nursing satisfaction in the study group was higher compared to that in the control group (P < 0.05). Secondly, we compared the pain scores. Before nursing, there exhibited no significant difference (P > 0.05). After nursing, the pain score of the two groups increased. Moreover, the pain score of the study group at discharge and 1 month, 3 months, and 6 months after operation was lower compared to that of the control group (P < 0.05). Before nursing, there exhibited no significant difference in the Harris hip joint function score (P > 0.05). After nursing, the Harris hip function score increased. Furthermore, the Harris hip function score of the study group at discharge and 1 month, 3 months, and 6 months after operation was higher compared to that of the control group (P < 0.05). In terms of the timed stand-up-walking test, there exhibited no significant difference before nursing (P > 0.05). After nursing, the time of the timed stand-up-walk test in both groups decreased. And the timed stand-up-walk test at discharge and 1 month, 3 months, and 6 months after operation in the study group was lower compared to that in the control group (P < 0.05). Compared with the MBI scores, there exhibited no significant difference before nursing (P > 0.05). After nursing, the MBI scores increased. Of note, the MBI scores of the study group at discharge and 1 month, 3 months, and 6 months after operation were higher compared to those of the control group (P < 0.05). Finally, we compared the scores of life quality. Before nursing, there exhibited no significant difference (P > 0.05). After nursing, the scores of life quality decreased. The scores of physiological function, psychological function, social function, and health self-cognition in the study group were lower compared to those in the control group (P < 0.05).

Conclusion

The perioperative rehabilitation nursing program of artificial hip replacement for the elderly based on the HAPA model is feasible, which can effectively enhance the functional recovery of hip joint, promote the ability of self-care of daily life, relieve pain and anxiety, and help to achieve dynamic balance and gait stability in the early stage. The rehabilitation program is better than routine nursing. As a new social cognitive model, the HAPA model is applied to the rehabilitation nursing environment of hip replacement from the aspect of social cognitive behavior, which can help to enhance the rehabilitation behavior of elderly patients, playing an important role in the rehabilitation effect of perioperative nursing.

Is Training With Gym Machines Safe After Hip Arthroplasty?—An In Vivo Load Investigation

Background: Training with gym machines is one of the most popular physical activities after total hip arthroplasty (THA). However, to date, there are no evidence-based recommendations for physical activity after THA, worldwide. The aim of the study is to evaluate the in vivo hip joint loads during exercises on four widely used gym machines in order to provide a source for an evidence-based patient counselling for arthroplasty surgeons.

Methods: The in vivo hip joint loads in seven patients (59.6 ± 6.4 years, 28.6 ± 2.1 kg/m²) with instrumented hip implants were assessed. The resulting force (F_res), bending moment (M_bend), and torsional moment (M_tors) were evaluated during the training on leg curl/leg extension machines (loads: 20, 30, and 40 kg), leg press machine [backrest: 10°, 30°, and 60°; load: 50, 75, and 100%BW (bodyweight)], and a rope pull machine (abduction/adduction/flexion/extension; each ipsi- and contralateral; load 10 kg). These loads were compared with the loads during walking on treadmill at 4 km/h (median peak values: F_res 303%BW, M_bend 4.25%BWm, and M_tors 2.70%BWm).

Results: In each of the four performed exercises with a total of 23 different load conditions or exercise modes analyzed, a significantly lower or not different load was detected with respect to F_res, M_bend, and M_tors measured while walking with 4 km/h. Nevertheless, F_res and M_bend demonstrated a trend to increased loading during the ipsilateral monopod standing rope pull exercises hip flexion, extension, and abduction.

Conclusion: Based on our investigation, we assume that the investigated gym machines and external loads can be considered mainly as low-impact sports (with some exceptions) and thus as safe physical activity after THA. Due to the fact that the examinations were conducted in the mean 17.4 months after THA, the applicability of the results to the immediate postoperative period is limited.

Overstretching Expectations May Endanger the Success of the “Millennium Surgery”

Total hip arthroplasty (THA) is an extremely successful treatment strategy. Patient expectations, however, have increased; if not properly guided by surgeons, at present, patients expect next to pain-free restoration of the joint and a fast return to work and sports. While the revision rates after THA also increased in younger patients, knowledge on musculoskeletal loads still remains sparse, and the current recommendations on postoperative rehabilitation are based on expert opinions only. The aim of this study was to unravel biomechanical contact conditions in “working age” (&lt;60 years, 53.5 ± 3.0 years) and “retirement age” (&gt;60 years, 67.7 ± 8.6 years) patients during activities recommended post-THA. We hypothesized that working age patients would show substantially increased hip contact loads compared to older patients. The in vivo joint contact force (Fres) and torsion torque (Mtors), reflecting the main contact load situation, experienced during activities of daily living and sports activities were measured in a unique group of 16 patients with instrumented THA. We summarized patient activities and sports recommendations after THA mentioned within the literature using PubMed (without claim of completeness). The measurements showed that younger working age patients experienced significant (p = 0.050) increased Mtors (21.52 ± 9.11 Nm) than older retirement age patients (13.99 ± 7.89 Nm) by walking. Bowling, as a recommended low-impact sport, was associated with Fres of up to 5436 N and Mtors of up to 108 Nm in the working age group, which were higher than the Fres (5276 N) and Mtors (71 Nm) during high-impact soccer. Based on our results, age was proven to be a discriminator in joint loading, with working age patients presenting with increased loads compared to retirement age patients, already during daily activities. The current patient recommendations have led to further increased joint loadings. If THA cannot be delayed in a patient, we propose counselling patients on a carefully considered return to sports, focusing on low-impact activities, as indicated hereby. The findings from this work illustrate the need to provide critical feedback to patient expectations when returning to work and sports activities. Patients returning to more intensive sports activities should be carefully monitored and advised to avoid as much overloading as possible.