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1.

Background

Analysis of dynamic knee loading during gait is essential to prevent mechanical failures following total knee arthroplasty. External knee adduction moment during gait is the primary factor producing medial joint reaction force, and an increase in the moment is directly related to an increase in the medial compartment load on the knee.

Methods

Knee adduction moment during gait in 39 knees of 32 female patients following a posterior stabilized knee replacement with a single surgeon was evaluated at 1.3 months following surgery. A cut-off moment was determined as mean + 1 standard deviation (SD) of the moment from 10 healthy subjects, and patients' knees were divided into high- and normal-moment groups. Significant differences in clinical assessments and gait parameters between the two groups were assessed.

Results

Based on the cut-off moment, 23 knees were grouped into normal knees and 16 knees were grouped into high-moment knees. High-moment knees showed identical femorotibial angles and knee society scores but had greater toe-out angles and medially directed ground reaction forces compared to normal-moment knees. High-moment knees showed strong correlations between peak moment and knee adduction angle, and frontal plain moment arm.

Conclusions

The clinical significance of a high knee adduction moment following total knee arthroplasty remains unclear, but dynamic frontal alignment during gait is one of the key factors for residual high-moment knees following surgery.  相似文献   

2.

Background

Clinical effectiveness of lateral wedges for knee osteoarthritis is inconsistent across studies. One explanation is that knee loading is not fully described by the peak frontal-plane knee moment. The purpose of this study was to propose a 3D resultant approach to describing moments at the knee and evaluate how this moment changes in response to lateral wedges.

Methods

Walking gait analysis was performed on 20 individuals with knee osteoarthritis, in their own shoes, with and without a six millimeter lateral wedge insole. Frontal-plane and 3D resultant moments were calculated for each participant and footwear condition. Paired t-tests identified differences between footwear conditions, correlations identified relationships between frontal-plane and 3D resultant moments, and regressions assessed relationships between moments and pain.

Results

Significant reductions to peak frontal-plane moments (p = 0.001) and 3D resultant moments at the same time point (p = 0.042) were observed with lateral wedges. While an overall significant correlation was observed between change in frontal-plane moments and change in 3D resultant moments with a lateral wedge (r = 0.68, p = 0.001), 5/20 participants experienced disparate results where the frontal-plane moment was reduced yet the 3D moment increased.

Conclusions

While lateral wedges alter frontal-plane moment magnitude, the direction of change does not always correspond to the direction of change observed in the 3D resultant moment. Thus resultant knee load may sometimes increase with lateral wedges.

Clinical relevance

Future prospective studies should evaluate if changes in 3D resultant moments, and thus total knee load, offer an explanation as to why some participants do not experience clinical benefit from lateral wedges.  相似文献   

3.

Background

The knee adduction moment (KAM) is often elevated in medial knee osteoarthritis (KOA). The aim of this study was to evaluate effects on KAM and patient-reported outcomes of a six-week gait training program.

Methods

Twenty-one patients (61?±?6 years) with KOA participated in a six-week biofeedback training program to encourage increased toe-in (all patients) and increased step-width (five patients). Patients received real-time visual feedback while walking on an instrumented treadmill. We analysed the effect of the gait modification(s) on peak KAM in week six and three and six months post-training. We also evaluated the effect on pain and functional ability.

Results

Of 21 patients starting the program, 16 completed it with high attendance (15 and 16 respectively) at the three and six month follow-ups. First peak KAM was significantly reduced by up to 14.0% in week six with non-significant reductions of 8.2% and 5.5% at the follow-ups. Functional ability (assessed using the WOMAC questionnaire) improved significantly after the training (eight point reduction, p?=?0.04 in week six and nine point reduction, p?=?0.04 at six-month follow-up). There was also a trend towards reduction in WOMAC pain (p?=?0.06) at follow-up.

Conclusions

Biofeedback training to encourage gait modifications is feasible and leads to short-term benefits. However, at follow-up, reductions in KAM were less pronounced in some participants suggesting that to influence progression of KOA in the longer term, a permanent regime to reinforce the effects of the training program is needed.Trial number: ISRCTN14687588.  相似文献   

4.

Background

Computer-assisted navigation in total knee arthroplasty (TKA) reduces variability and may improve accuracy in the postoperative static alignment. The effect of navigation on alignment and biomechanics during more dynamic movements has not been investigated.

Methods

This study compared knee biomechanics during level walking of 121 participants: 39 with conventional TKA, 42 with computer-assisted navigation TKA and 40 unimpaired control participants.

Results

Standing lower-limb alignment was significantly closer to ideal in participants with navigation TKA. During gait, when differences in walking speed were accounted for, participants with conventional TKA had less knee flexion during stance and swing than controls (P < 0.01), but there were no differences between participants with navigation TKA and controls for the same variables. Both groups of participants with TKA had lower knee adduction moments than controls (P < 0.01).

Conclusions

In summary, there were fewer differences in the biomechanics of computer-assisted navigation TKA patients compared to controls than for patients with conventional TKA. Computer-assisted navigation TKA may restore biomechanics during walking that are closer to normal than conventional TKA.  相似文献   

5.

Background

There are unanswered questions about knee–ankle alignment after total knee arthroplasty (TKA) for varus and valgus osteoarthritis (OA) of the knee. The aim of this retrospective study was to assess knee–ankle alignment after TKA.

Methods

The study consisted of 149 patients who had undergone TKA due to varus and valgus knee OA. The alignment and angles in the selected knees and ankles were measured on full-length standing anteroposterior radiographs, both pre-operatively and post-operatively. The paired t-test and Pearson's correlation tests were used for statistical analysis.

Results

The results showed that ankle alignment correlated with knee alignment both pre-operatively and postoperatively (P < 0.05). The pre-operative malalignment of the knee was corrected (P < 0.05), and the ankle tilt angle was accordingly improved in the operative side after TKA (P < 0.05). In addition, TKA had little effect on knee–ankle alignment on the non-operative side (P > 0.05).

Conclusion

These findings indicated that routine TKA could correct the varus or valgus deformity of a knee, and improve the tilt of the ankle. Ankle alignment correlated with knee alignment both pre-operatively and postoperatively. Both pre-operative knee and ankle malalignment can be simultaneously corrected following TKA.

Level of evidence

Level III.  相似文献   

6.

Background

The recently reintroduced bicruciate retaining Total Knee Arthroplasty (BCR TKA) is an effort to reproduce kinematics closer to the native knee. However, there is no data on appropriate balancing with this implant. Balancing is crucial and challenging as medial and lateral polyethylene (PE) inlays are modular, which allows for placement of different thicknesses in the medial and lateral compartments. This study aimed at providing a detailed kinematic view on balancing BCR TKA.

Methods

Seven fresh frozen cadaver legs were mounted in a kinematic rig that applied squatting under application of physiologic quadriceps and hamstring forces. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests. Following testing on the native knee, a BCR TKA was implanted in each specimen and all trials were repeated. Using one millimeter increments, five inlay thicknesses were tested to simulate optimal balancing, symmetric under-, and overstuffing, valgus constellation, and varus constellation.

Results

Overall, knee kinematics following BCR TKA seem to be very close to the native knee. The changes as introduced to tibiofemoral kinematics through over- or understuffing the polyethylene inserts are affecting the system only to a minor degree and generally lack statistical significance. Reproduction of the tibial varus via PE-Inlays did not lead to kinematics much closer to the native knee.

Conclusions

The changes introduced to tibiofemoral kinematics by removal of the conforming meniscus and cartilage and replacement with a flat PE insert and femoral component are of more impact than different inlay sizes and their combinations for a BCR TKA.  相似文献   

7.

Background

To describe the prevalence of self-reported knee joint instability in patients with pre-surgery knee osteoarthritis (OA) and to explore the associations between self-reported knee joint instability and radiological features.

Methods

A cross-sectional study including patients scheduled for primary Total Knee Arthroplasty (TKA). Self-reported knee instability was examined by questionnaire. Radiological features consisted of osteophyte formation and joint space narrowing (JSN), both scored on a 0 to three scale. Scores > 1 are defined as substantial JSN or osteophyte formation. Regression analyses were provided to identify associations of radiological features with self-reported knee joint instability.

Results

Two hundred and sixty-five patients (mean age 69 years and 170 females) were included. Knee instability was reported by 192 patients (72%). Substantial osteophyte formation was present in 78 patients (41%) reporting and 33 patients (46%) not reporting knee joint instability. Substantial JSN was present in 137 (71%) and 53 patients (73%), respectively. Self-reported knee instability was not associated with JSN (relative to score 0, odds ratios (95% CI) of score 1, 2 and 3 were 0.87 (0.30–2.54), 0.98 (0.38–2.52), 0.68 (0.25–1.86), respectively) or osteophyte formation (relative to score 0, odds ratios (95% CI) of score 1, 2 and 3 were 0.77 (0.36–1.64), 0.69 (0.23–1.45), 0.89 (0.16–4.93), respectively). Stratified analysis for pain, age and BMI showed no associations between self-reported knee joint instability and radiological features.

Conclusion

Self-reported knee joint instability is not associated with JSN or osteophyte formation.  相似文献   

8.

Background

Aseptic loosening is a common failure mode in cemented unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). This led to the development of cementless designs but the historical outcomes were poor. Recent developments in cementless designs have improved outcomes, but the current status is unknown. Therefore, a systematic review was performed to assess recent outcomes of cementless knee arthroplasty.

Methods

A search was performed using PubMed, Embase and Cochrane systems and national registries for studies reporting outcomes since 2005. Fifty-two cohort studies and four registries reported survivorship, failure modes or functional outcomes of cementless UKA and TKA.

Results

Nine level I studies, six level II studies, three level III studies, 34 level IV studies and four registries were included. Three hundred eighteen failures in 10,309 cementless TKA procedures and 62 failures in 2218 cementless UKA procedures resulted in extrapolated five-year, 10-year and 15-year survivorship of cementless TKAs of 97.7%, 95.4% and 93.0%, respectively, and cementless UKA of 96.4%, 92.9% and 89.3%, respectively. Aseptic loosening was more common in cementless TKA (25%) when compared to UKA (13%). Functional outcomes of cementless TKA and UKA were excellent with 84.3% and 84.5% of the maximum possible scores, respectively.

Conclusions

This systematic review showed that good to excellent extrapolated survivorship and functional outcomes are seen following modern cementless UKA and TKA, with a low incidence of aseptic loosening following cementless UKA.

Level of evidence

Level IV.  相似文献   

9.

Background

Individuals with knee osteoarthritis (OA) generally demonstrate great difficulty in ascending stairs. The strategies and compensations used by these individuals in stair activities have not been fully established. The purpose of this study was to investigate the joint kinematics of the pelvis, hip, knee and ankle throughout the gait cycle, in the sagittal and frontal planes, in individuals with mild and moderate knee OA, during an ascending stairs task.

Methods

Thirty-one individuals with knee OA and 19 controls were subjected to clinical and radiographic analysis, divided into three groups: control, mild knee OA, and moderate knee OA. Participants answered a self-reported questionnaire, carried out performance-based tests, and their kinematic data were recorded during an ascending stairs task using an eight-camera Qualisys 3D-Motion analysis system.

Results

The individuals with moderate degrees of knee OA demonstrated kinematic alterations in the pelvis, hip, knee, and ankle in the sagittal plane. The individuals with mild degrees of knee OA demonstrated kinematic alterations of the hip in the frontal plane, and kinematic alterations of the ankle in the sagittal plane.

Conclusions

The ascending stairs task allowed verification of meaningful information regarding gait strategies used by individuals with mild and moderate knee OA. The strategies of these two groups of individuals are different for this task, although more pronounced in individuals with moderate knee OA. The findings should be taken into account in the development of rehabilitation programs.  相似文献   

10.

Background

With the aim of improving component alignment and outcome in total knee arthroplasty (TKA), several computer-assisted devices (CAD) have been developed.

Methods

In February 2014, the present unit started to use a new imageless navigation system with accelerometric pods within the surgical field for all primary TKAs; there was no need for optical trackers or cameras. This paper presents the results of the first 72 TKAs using this iAssist system in 71 prospectively collected and retrospectively analyzed patients. It analyzed component positioning in standard and full-length leg x-rays.

Results

The mean age of the patients was 70 years (range 52–88). The center of hip, knee and ankle (mechanical axes) deviated on average 0.5° (standard deviation (SD) of 1.8) valgus from the targeted straight alignment. Three TKAs had > 3° deviation (i.e. four degree varus, five degree and seven degree valgus). The frontal tibial tray alignment was an average of 89.9° (range 86.4–100.1°, SD ± 2.0) with the target being 90°, and the sagittal slope was as targeted at 85.0° (range 78.4–88.8°, SD ± 1.7).

Conclusions

This CAD facilitated good mechanical alignment and reproducible accuracy in component positioning. Pods clipped onto cutting jigs within the surgical field provided simple and accurate navigation, with little extra time needed for calibration and no need for optical trackers or pre-operative imaging.  相似文献   

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