Background Total hip arthroplasty (THA) is an effective procedure for patients with end-stage hip osteoarthritis. However, whether or not pre-operatively existing functional deficits are persisting several years post-surgery in the affected limb has not been thoroughly researched. Therefore, the primary aim of this preliminary study was to include patients four to five years after undergoing THA and to investigate potential differences between the operated and non-operated leg in hip strength, range of motion (ROM), balance, and gait. The secondary aim was to compare these values from the operated leg of the patients to those of the legs of healthy subjects. Methods Sixteen patients (age: 65.20 ± 5.32 years) following unilateral THA (post-operation time: 4.7 ± 0.7 years) and ten, healthy, age-matched control subjects (age: 60.85 ± 7.57 years) were examined for maximum isometric hip muscle strength, active ROM of the hip joint, balance and gait on both limbs. Paired t-tests were used to assess the inter-limb differences in the THA group. Analyses of covariance (ANCOVA) were performed to compare groups, using age as a covariate. Results The analysis of inter-limb differences in patients following THA revealed significant deficits on the operated side for hip abduction strength (p = 0.02), for hip flexion ROM (p < 0.01) and for balance in terms of the length of center of pressure (COP) (p = 0.04). Compared to values of the control subjects, the patients demonstrated significantly reduced hip strength in flexion, extension and abduction (p < 0.05) on the operated leg as well as reduced ROM measures in hip flexion, extension and abduction (p < 0.05). Conclusions The first results of this explorative study indicated that inter-limb differences as well as reduced hip strength and hip ROM compared with control subjects were still present four to five years after THA. These persisting asymmetries and deficits in patients following THA may be one explanation for the decrease in health-related quality of life (HRQoL) seen in patients over the years after surgery. Further studies are required to replicate these findings with a larger sample size. Trial registration DRKS, DRKS00016945. Registered 12 March 2019 – Retrospectively registered,

Tensiomyography (TMG) is a non-invasive method to determine contractile parameters of skeletal muscles. Several methodological factors, however, might affect TMG results. The aim of this study was to investigate the effect of specific sensor position shifts on tensiomyographic parameters. 14 healthy males (age: 22.6 ± 1.2 years) participated in the study. TMG measurements were performed for rectus femoris (RF), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) on five sensor positions. The original sensor position (OP) was the recommended position on the muscle belly while for the shifted positions, the sensor was displaced one centimetre medially, laterally, proximally, and distally. TMG parameters measured were maximum radial displacement (Dm) and contraction time (Tc). To investigate the effect of sensor position shift, repeated-measures ANOVAs were performed. The ANOVAs revealed significant differences across the five sensor positions for RF and GM. Posthoc analysis showed significant reductions in Dm by 10 % (p = .03) and in Tc by 12 % (p = .008) in the laterally shifted sensor position for RF. For GM, Dm was significantly reduced by 20 % (p = .038) in the medially displaced sensor position. The results suggest that incorrect sensor positioning has an impact on TMG parameters, especially when incorrectly positioned in the medial-lateral direction.

Background/Purpose Several methods are used to evaluate the outcome of total hip arthroplasty (THA), however, their relationship at different time points after surgery is unclear. The purpose of this exploratory study was to investigate correlations between self-report function, performance-based tests (PBTs) and biomechanical parameters in patients 12 months after THA. Methods Eleven patients were included in this preliminary cross-sectional study. Hip disability and Osteoarthritis Outcome Score (HOOS) was completed for self-reported function. As PBTs, the Timed-up-and-Go test (TUG) and 30-Second-Chair-Stand test (30CST) were used. Biomechanical parameters were derived from analyses of hip strength, gait and balance. Potential correlations were calculated using Spearman correlation coefficient r. Results HOOS scores and parameters of PBTs showed moderate to strong correlations (0.3 < r < 0.7). Correlation analysis between HOOS scores and biomechanical parameters revealed moderate to strong correlations for hip strength whereas correlations with gait parameters and balance were rather weak (r < 0.3). Moderate to strong correlations were also found between parameters of hip strength and 30CST. Conclusion For THA outcome assessment 12 months after surgery, our first results indicate that self-report measures or PBTs could be used. Analysis of hip strength also appears to be reflected in HOOS and PBT parameters and may be considered as an adjunct. Given the weak correlations with gait and balance parameters, we suggest that gait analysis and balance testing should be performed in addition to PROMs and PBTs as they may provide supplementary information, especially for THA patients that are at risk for falls.

BackgroundːTotal hip arthroplasty (THA) is a successful method to reduce pain in end-stage hip osteoarthritis (OA) patients. If the pre-operatively existing deficits in the affected limb are persisting years after THA has not been thoroughly researched. Therefore, the aim of the study was to investigate potential side-to-side differences in long-time THA patients.MethodsːSixteen patients (age: 65.20 ± 5.32 years), who had undergone unilateral THA four to five years ago and ten, healthy, age-matched controls (age = 60.85 ± 7.57 years) were examined for maximum isometric hip muscle strength, range of motion (ROM) of the hip joint, balance and gait on both limbs. Paired t-testes were used to assess the inter-limb differences in THA patients and controls and unpaired t-tests were applied to investigate differences between the two groups.ResultsːIn THA patients, significant deficits on the operated side were found for the center of pressure (COP) length, hip abduction torque and ROM of hip extension with small to medium effects. Compared to the controls, THA patients demonstrated highly significantly reduced hip strength in flexion, extension, abduction and adduction as well as limited ROM in hip flexion and abduction.ConclusionsːA few side-to-side difference were present in THA patients four to five years after the surgery, although the general hip muscle weakness and restricted hip ROM compared to the controls was more severe. Postoperative training focusing on strengthening hip muscles should be continued months and years after the surgery in order to compensate persisting deficits.Trial registrationːDRKS, DRKS00016945. Registered 12 March 2019 – Retrospectively registered, http://www.drks.de/DRKS00016945

Backgroundː Total hip arthroplasty (THA) is an effective procedure for patients with end-stage hip osteoarthritis. However, whether or not pre-operatively existing functional deficits are persisting several years post-surgery in the affected limb has not been thoroughly researched. Therefore, the primary aim of the study was to investigate differences between the operated and non-operated leg in hip strength, range of motion (ROM), balance, and gait in patients four to five years after undergoing THA. The secondary aim was to compare these values from the operated leg of the patients to those of the legs of healthy subjects. Methodsː Sixteen patients (age: 65.20±5.32 years) following unilateral THA (post-operation time: 4.7±0.7 years) and ten, healthy, age-matched control subjects (age: 60.85±7.57 years) were examined for maximum isometric hip muscle strength, active ROM of the hip joint, balance and gait on both limbs. Paired t-tests were used to assess the inter-limb differences in the THA group. Analyses of covariance (ANCOVA) were performed to compare groups, using age as a covariate. Results: The analysis of inter-limb differences in patients following THA revealed significant deficits on the operated side for hip abduction strength (p=0.02), for hip flexion ROM (p<0.01) and for balance in terms of the length of center of pressure (COP) (p=0.04). Compared to values of the control subjects, the patients demonstrated significantly reduced hip strength in flexion, extension and abduction (p<0.05) on the operated leg as well as reduced ROM measures in hip flexion, extension and abduction (p<0.05). Conclusions: Inter-limb differences as well as reduced hip strength and hip ROM compared with control subjects were still present four to five years after THA. These persisting asymmetries and deficits in patients following THA may be one explanation for the decrease in health-related quality of life (HRQoL) seen in patients over the years after surgery. Postoperative training focusing on strengthening hip muscles should be continued months and years after hip replacement in order to compensate persisting deficits and asymmetries. Trial registration: DRKS, DRKS00016945. Registered 12 March 2019 – Retrospectively registered, http://www.drks.de/DRKS00016945