Secondary Patellar Resurfacing in TKA: A Combined Analysis of Registry Data and Biomechanical Testing

The German Arthroplasty registry (EPRD) has shown that different prosthesis systems have different rates of secondary patellar resurfacing: four years after implantation, the posterior-stabilized (PS) Vega prosthesis has a 3.2% risk of secondary patellar resurfacing compared to the cruciate-retaining (CR) Columbus prosthesis at 1.0% (both Aesculap AG, Tuttlingen, Germany). We hypothesized that PS implants have increased retropatellar pressure and a decreased retropatellar contact area compared to a CR design, which may lead to an increased likelihood of secondary patellar resurfacing. Eight fresh frozen specimens (cohort 1) were tested with an established knee rig. In addition, a possible influence of the registry-based patient collective (cohort 2) was investigated. No significant differences were found in patient data–cohort 2-(sex, age). A generally lower number of PS system cases is noteworthy. No significant increased patella pressure could be detected with the PS design, but a lower contact area was observed (cohort 1). Lower quadriceps force (100°–130° flexion), increased anterior movement of the tibia (rollback), greater external tilt of the patella, and increasing facet pressure in the Vega PS design indicate a multifactorial cause for a higher rate of secondary resurfacing which was found in the EPRD patient cohort and might be related to the PS’ principle function.

Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty

Background Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee joint. However, patellofemoral joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study was to evaluate the biomechanical effect of medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses on the patellofemoral joint. Methods A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in contact stress on the patellofemoral joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition. Results At an early flexion angle, the results of contact stress showed no significant difference between the FB and MB medial UKA models compared with the intact model. However, at high flexion angles, we observed a significant increase in contact stress with the FB models compared with the intact model. On the contrary, in the case of the MB models, we found no statistically significant increment compared with the intact model. A larger quadriceps force was needed to produce an identical flexion angle for both the FB and MB UKA designs than for the intact model. At high flexion angles, a significant increase quadriceps force whit the FB model compared with the intact model. Conclusions Our results indicate that with medial UKA, the contact stress increased and greater quadriceps force was applied to the patellofemoral joint. However, performing UKA on a patellofemoral joint with osteoarthritis should not be difficult, unless anterior knee pain is present, because the increase in contact stress is negligible.

Association of lower extremity function with nutritional status and number of drugs in patients with chronic heart failure

Objective This study was performed to investigate the physical performance parameters, including lower extremity function parameters, that may be risk factors for falls in patients with chronic heart failure. Methods Seventy patients with stable chronic heart failure were included in this retrospective cross-sectional study. The five-repetition sit-to-stand test (5STS) time, Controlling Nutritional Status (CONUT) score, and number of drugs were assessed. Results Simple linear regression analysis revealed that the 5STS time was positively correlated with age, the CONUT score, and the number of drugs but was negatively associated with the handgrip force, quadriceps force, and quadriceps muscle thickness. Multiple linear regression analysis showed a significant association between the 5STS time and the CONUT score, quadriceps force, and number of drugs. Conclusion The muscle strength, nutritional status, and number of drugs should be evaluated to prevent lower extremity weakness in patients with stable chronic heart failure.

Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty

Background Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee joint. However, patellofemoral joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study was to evaluate the biomechanical effect of medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses on the patellofemoral joint.Methods A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in contact stress on the patellofemoral joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition.Results At an early flexion angle, the results of contact stress showed no significant difference between the FB and MB medial UKA models and the intact model. However, at large flexion angles, we observed a significant increase in contact stress with the FB models. On the contrary, in the case of the MB models, we found no statistically significant increment compared with the intact model. Our results indicate that with medial UKA, the contact stress increased and greater quadriceps force was applied to the patellofemoral joint. However, performing UKA on a patellofemoral joint with osteoarthritis should not be difficult, unless anterior knee pain is present, because the increase in contact stress is negligible.Conclusions Our results show no significant difference in contact stress on the patellofemoral joint between the medial UKA and intact knee joint models. Such a mechanism was easily found in MB medial UKA. Therefore, this study biomechanically showed that degenerative changes in the patellofemoral joint should not be considered an absolute contraindication to treatment with medial UKA.

Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty

Background Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee joint. However, patellofemoral joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study was to evaluate the biomechanical effect of medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses on the patellofemoral joint. Methods A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in contact stress on the patellofemoral joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition.Results At an early flexion angle, the results of contact stress showed no significant difference between the FB and MB medial UKA models and the intact model. However, at large flexion angles, we observed a significant increase in contact stress with the FB models. On the contrary, in the case of the MB models, we found no statistically significant increment compared with the intact model. Our results indicate that with medial UKA, the contact stress increased and greater quadriceps force was applied to the patellofemoral joint. However, performing UKA on a patellofemoral joint with osteoarthritis should not be difficult, unless anterior knee pain is present, because the increase in contact stress is negligible. Conclusions Our results show no significant difference in contact stress on the patellofemoral joint between the medial UKA and intact knee joint models. Such a mechanism was easily found in MB medial UKA. Therefore, this study biomechanically showed that degenerative changes in the patellofemoral joint should not be considered an absolute contraindication to treatment with medial UKA.

Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty

Background Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis (OA) of the knee joint. However, patellofemoral (PF) joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study is to evaluate the biomechanical effect on the PF joint in medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses. Methods A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in the contact stress on the PF joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition. Results At an early flexion angle, the results of the contact stress were showed that there was no significant difference between the FB and MB medial UKA models compared with the intact model. However, at a large flexion angle, we observed a significant increase in the contact stress of FB models. On the contrary, in the case of the MB models, there was no statistically significant increment compared to the intact model. Our results indicate that with medial UKA, the contact stress increased, and a greater quadriceps force was applied to the PF joint. However, there should be no difficulty in performing UKA on a PF joint with OA, unless there is anterior knee pain. This is because the increase in the contact stress is negligible. Conclusions Our results showed that there was no significant difference in contact stress on the PF joint between medial UKA and intact knee joints. In particular, such a mechanism was easily found in mobile-bearing medial UKA. Therefore, this study biomechanically showed that degenerative changes in the PF joint should not be considered an absolute contraindication for treatment with medial UKA.

Patellofemoral Joint Stress during Running with Added Load in Females

Patellofemoral joint (PFJ) pain syndrome is a commonly reported form of pain in female runners and military personnel. Increased PFJ stress may be a contributing factor. Few studies have examined PFJ stress running with added load. Our purpose was to analyze PFJ stress, PFJ reaction force, quadriceps force, knee flexion angle, and other kinematic and temporospatial variables running with and without a 9 kg load. Nineteen females ran across a force platform with no added load and 9.0 kg weight vest. Kinematic data were collected using 3D motion capture and kinetic data with a force platform. Muscle forces were estimated using a musculoskeletal model, and peak PFJ loading variables were calculated during stance. Multivariate analyses were run on PFJ loading variables and on cadence, step length and foot strike index. Differences were shown in PFJ stress, PFJ reaction force, peak knee flexion angle and quadriceps force. Joint specific kinetic variables increased between 5–16% with added load. PFJ loading variables increased with 9 kg of added load without changes in cadence, step length, or foot strike index compared to no load. Added load appears to increase the PFJ loading variables associated with PFJ pain in running.

Associations between the measures of physical function, risk of falls and the quality of life in haemodialysis patients: a cross-sectional study

Background Impaired physical function due to muscle weakness and exercise intolerance reduces the ability to perform activities of daily living in patients with end-stage kidney disease, and by consequence, Health-Related Quality of Life (HRQoL). Furthermore, the risk of falls is an aggregate of physical function and, therefore, could be associated with HRQoL as well. The present study examined the associations between objective and subjective measures of physical function, risk of falls and HRQoL in haemodialysis patients. Methods This cross-sectional multicentre study included patients on maintenance haemodialysis. Physical function (quadriceps force, handgrip force, Sit-to-Stand, and six-minute walking test), the risk of falls (Tinetti, FICSIT-4, and dialysis fall index) and HRQoL (PROMIS-29 and EQ-5D-3 L) were measured and analysed descriptively, by general linear models and logistic regression. Results Of the 113 haemodialysis patients (mean age 67.5 ± 16.1, 57.5% male) enrolled, a majority had impaired quadriceps force (86.7%) and six-minute walking test (92%), and an increased risk of falls (73.5%). Whereas muscle strength and exercise capacity were associated with global HRQoL (R2 = 0.32) and the risk of falls, the risk of falls itself was related to psycho-social domains (R2 = 0.11) such as depression and social participation, rather than to the physical domains of HRQoL. Objective measures of physical function were not associated with subjective fatigue, nor with subjective appreciation of health status. Conclusions More than muscle strength, lack of coordination and balance as witnessed by the risk of falls contribute to social isolation and HRQoL of haemodialysis patients. Mental fatigue was less common than expected, whereas, subjective and objective physical function were decreased.

Effect of sagittal femoral component alignment on biomechanics after mobile-bearing total knee arthroplasty

Background Recently, there has been increasing interest in mobile-bearing total knee arthroplasty (TKA). However, changes in biomechanics with respect to femoral component alignment in mobile-bearing TKA have not been explored in depth. This study aims to evaluate the biomechanical effect of sagittal alignment of the femoral component in mobile-bearing TKA. Methods We developed femoral sagittal alignment models with − 3°, 0°, 3°, 5°, and 7°. We also examined the kinematics of the tibiofemoral (TF) joint, contact point on the TF joint, contact stress on the patellofemoral (PF) joint, collateral ligament force, and quadriceps force using a validated computational model under a deep-knee-bend condition. Results Posterior kinematics of the TF joint increased as the femoral component flexed. In addition, contact stress on the PF joint, collateral ligament force, and quadriceps force decreased as the femoral component flexed. The results of this study can assist surgeons in assessing risk factors associated with femoral component sagittal alignment for mobile-bearing TKA. Conclusions Our results showed that slight flexion implantation may be an effective alternative technique because of its advantageous biomechanical effect. However, excessive flexion should be avoided because of potential loosening of the TF joint.