Effect of an ankle-foot orthosis on knee joint mechanics: a novel conservative treatment for knee osteoarthritis

The impact of ankle-foot orthosis's plantarflexion resistance on knee adduction moment in people with chronic stroke

BACKGROUND

An ankle-foot orthosis (AFO) is used to assist gait of people with chronic stroke. It is widely accepted that AFO's plantarflexion resistance affects sagittal knee moments during their gait. However, its effect on the coronal knee moment remains unclear. This study aimed to examine the effects of varying articulated AFO's plantarflexion resistance on knee adduction moment in people with chronic stroke.

METHODS

Ten people with chronic stroke participated in this study. Gait performance was measured using a Vicon 3-dimensional motion capture system and a Bertec split-belt instrumented treadmill. The participants walked on the treadmill wearing an articulated AFO whose plantarflexion resistance could be systematically adjusted. The ankle joints were set to four distinct levels of plantarflexion resistance (S1 < S2 < S3 < S4). The coronal ankle and knee joint moment, center of pressure, and ground reaction force were analyzed using Visual3D.

RESULTS

The external knee adduction moment increased significantly ( P < .001) and the position of the center of pressure trajectory shifted significantly ( P = .003) in the medial direction as the plantarflexion resistance of the AFO was increased from the least resistive condition (S1) to the most resistive condition (S4). The maximum knee adduction moment (median [interquartile range]) was S1: 0.097 (-0.012 to 0.265) Nm/kg; S2: 0.136 (0.040 to 0.287) Nm/kg; S3: 0.160 (0.465 to 0.289) Nm/kg; and S4: 0.192 (0.080 to 0.288) Nm/kg.

CONCLUSIONS

This study demonstrated that varying AFO's plantarflexion resistance altered the knee adduction moment, likely by altering the center of pressure trajectory while walking, in people with chronic stroke.

A comparison of the biomechanical and clinical effects of a biaxial ankle-foot orthosis and lateral wedge insole in individuals with medial knee osteoarthritis

PURPOSE

This study aimed to compare a biaxial ankle-foot orthosis (AFO) with a lateral wedge insole in terms of the biomechanical and clinical outcomes in individuals with knee osteoarthritis.

MATERIALS AND METHODS

A cross-over randomized design was used where 31 individuals (25 females and six males, mean age of 52.19 ± 4.12 years) with knee osteoarthritis wore each intervention for two weeks with two weeks washout period. Three-dimensional kinematic and kinetic data and clinical outcomes were collected to evaluate the effects of each intervention on knee adduction moment (KAM), pain, stiffness, and function.

RESULTS

Both orthoses significantly improved pain by 17 and 22%, function by 11 and 14%, the first peak KAM by 15.7 and 19.2%, the second peak KAM by 10.4 and 16.7%, and KAM impulse by 14.8 and 22.2%, respectively. However, the biaxial AFO significantly reduced the KAM and improved function compared to the lateral wedge insole (p < 0.01).

CONCLUSIONS

The results of this study have shown that both orthoses have a potential role in the conservative management of medial knee osteoarthritis. The biaxial AFO proved statistically better at improving function and KAM; though these differences do not seem to be clinically significant.IMPLICATION FOR REHABILITATIONOrthotic interventions have been reported to be effective in the management of medial knee osteoarthritis.Lateral wedge insole and biaxial ankle-foot orthosis (AFO) are effective in the improvement of pain, function, and knee adduction moment (KAM) in people with medial knee osteoarthritis.The biaxial AFO, compared with lateral wedge insole, contributes to statistically more improvement of function and KAM. However, these differences do not seem to be clinically significant.

A comparison between laterally wedged insoles and ankle-foot orthoses for the treatment of medial osteoarthritis of the knee: A randomized cross-over trial

Objective:

To compare biomechanical and clinical outcome of laterally wedged insoles (LWI) and an ankle-foot orthosis (AFO) in patients with medial knee osteoarthritis.

Design:

Single-centre, block-randomized, cross-over controlled trial.

Setting:

Outpatient clinic.

Subjects:

About 39 patients with symptomatic medial knee osteoarthritis.

Interventions:

Patients started with either LWI or AFO, determined randomly, and six weeks later changed to the alternative.

Main measures:

Change in the 1st maximum of external knee adduction moment (eKAM) was assessed with gait analysis. Additional outcomes were other kinetic and kinematic changes and the patient-reported outcomes EQ-5D-5L, Oxford Knee Score (OKS), American Knee Society Clinical Rating System (AKSS), Hannover Functional Ability Questionnaire – Osteoarthritis and knee pain.

Results:

Mean age (SD) of the study population was 58 (8) years, mean BMI 30 (5). Both aids significantly improved OKS (LWI P = 0.003, AFO P = 0.001), AKSS Knee Score (LWI P = 0.01, AFO P = 0.004) and EQ-5D-5L Index (LWI P = 0.001, AFO P = 0.002). AFO reduced the 1st maximum of eKAM by 18% (P < 0.001). The LWI reduced both maxima by 6% (P = 0.02, P = 0.03). Both AFO and LWI reduced the knee adduction angular impulse (KAAI) by 11% (P < 0.001) and 5% (P = 0.05) respectively. The eKAM (1st maximum) and KAAI reduction was significantly larger with AFO than with LWI (P = 0.001, P = 0.004).

Conclusions:

AFO reduces medial knee load more than LWI. Nevertheless, no clinical superiority of either of the two aids could be shown.

[Insoles, knee braces and ankle-foot orthoses in the treatment of medial gonarthrosis : A literature review]

BACKGROUND

Osteoarthritis is the most common joint disease worldwide and mostly affects the knee joint (gonarthrosis). In treatment algorithms, technical aids in the form of laterally wedged insoles, valgizing knee braces and ankle-foot orthoses have an importance in the treatment of medial unicompartmental knee joint disease. However, national and international guidelines differ in their recommendations.

INSOLES

Taking into account a great amount of scientific work, the measurable effect of laterally wedged insoles appears to be low, so that a justifying indication only exists at low gonarthrosis levels.

KNEE BRACES

Valgizing knee braces have shown stronger biomechanical and clinical effects, but with a slightly increased complication potential and low compliance. Low to medium-grade arthrosis can be treated.

ANKLE-FOOT ORTHOSES

Ankle-foot arthroses have not yet been conclusively examined. Initial work indicates biomechanical and clinical efficacy. The overall effects and indications appear comparable to knee braces, probably with less complication potential.

Effect of Tai Chi Training on Plantar Loads during Walking in Individuals with Knee Osteoarthritis

Tai Chi is an available method for the treatment of knee osteoarthritis (KOA). The impacts of Tai Chi on plantar loads of individuals with KOA are not fully understood. 46 participants with knee osteoarthritis were randomly assigned into the Tai Chi group (n = 23) or the control group (n = 23). The Tai Chi group attended a 6-month Tai Chi program, and the control group participated in a wellness education program. Novel Pedar-X system was used to collect the peak pressure (PP) and maximum force (MF) during walking before and 6 months after the intervention. Significant higher peak pressure and maximum force were observed in the 4th and 5th metatarsophalangeal joints in the Tai Chi group. However, there were significant declines in the peak pressure of the whole foot and the 2nd and 3rd metatarsophalangeal joints and maximum force of the heel in the control group. These results suggested that individuals with KOA might change the pattern of plantar loads during walking through Tai Chi, and plantar loads would be useful as a parameter to assess the effect of Tai Chi on knee osteoarthritis. This trial is registered with Clinical Trials: CHiCTR-TRC-13003264.

Non-operative treatment of unicompartmental osteoarthritis of the knee: a prospective randomized trial with two different braces-ankle-foot orthosis versus knee unloader brace

BACKGROUND

The use of an unloader brace is a non-surgical treatment option for patients with medial osteoarthritis (OA). However, many patients do not adhere to brace treatment, because of skin irritation due to the pads at the level of the joint space and bad fit. A new concept to unload the medial compartment of the knee is a foot ankle brace with a lever arm pressing the thigh in valgus. The aim of this prospective randomized trial was to examine the outcomes of patients with medial OA after treatment with a conventional knee unloader brace (Unloader One^®) and the new foot ankle orthosis (Agilium FreeStep^®).

METHODS

For this multicenter trial, 160 patients (> 35 years) with medial OA were randomly allocated to treatment with a conventional knee unloader brace (Unloader One^®) or treatment with the new knee OA ankle brace (Agilium FreeStep^®). The primary outcome measure was pain (numerical analog scale) at baseline (T0), 8 weeks (T1), and 6 months (T2). Secondary outcome measures were knee function (Knee Injury and Osteoarthritis Outcome Score, KOOS), side effects, additional interventions, and compliance.

RESULTS

In both groups, walking pain improved between T0 and T1 and also between T0 and T2 without a significant group difference. For pain at sports, both groups showed a significant improvement between T0 and T2 without a significant group difference. The KOOS subscales symptoms, pain, activity, sport, and quality of life increased significantly in both treatment groups without any significant group differences at T 0, T1, and T2. There was also no significant group difference in additional interventions and weekly or daily brace use. In the Agilium FreeStep^® group (23.5%), significantly less patients reported bruises in contrast to the Unloader One^® group (66.7%).

DISCUSSION

The results of this clinical trial show that the foot ankle brace is as effective as a conventional knee unloader brace for the treatment of medial knee OA with regard to clinical outcome. The rate of side effects such as bruises was significantly lower in the Agilium FreeStep^® group.

TRIAL REGISTRATION

DRKS00009215, 13.8.2015.

Acute effects of different orthotic interventions on knee loading parameters in knee osteoarthritis patients with varus malalignment

BACKGROUND

Knee osteoarthritis (KOA) is the most common form of arthritis with an estimated lifetime prevalence of 45%. The use of orthotic devices is a generally accepted conservative therapy in KOA. A new conservative treatment is an ankle-foot orthosis (AFO); however, studies on the biomechanical effects are limited. The aim of this study was to examine the acute effects of different orthotic devices (AFO, knee brace and wedged shoes) on (un)loading parameters in subjects with KOA.

METHODS

Fifty-two medial KOA patients (mean age 59 (standard deviation (SD) 10) years and mean body mass index 27.5 (SD 4.9) kg/m²) were recruited. Three-dimensional gait analysis was undertaken with different interventions in a randomized order: control (own shoes), new AFO, conventional unloader brace and laterally wedged shoes (six degrees).

RESULTS

Significant decreases of 27% and nine percent in first peak knee adduction moment (KAM) were observed for the AFO and wedged shoes, respectively, in comparison with the control. Significant decreases of 21%, seven percent and 18% in the KAM impulse were observed for the AFO, brace and wedged shoes, respectively, compared to the control. The knee flexion moment (KFM) increased compared to the control for all conditions, but only significantly while using the AFO, showing an increase of 26% as compared to the control.

CONCLUSIONS

The AFO and wedged shoes were more effective in unloading the medial compartment of the knee compared to the unloader brace. However, the effect of an increased KFM on KOA remains unclear and requires further investigation.

On the biomechanical relationship between applied hip, knee and ankle joint moments and the internal knee compressive forces

Mechanical devices are common treating methods for knee osteoarthritis. It has the purpose of reducing the internal joint forces and unloading the damaged structure. The reduction is often achieved by alterations in the frontal plan, shifting the contact force from one compartment to the other, leaving the total compressive force unchanged. The aim of this study was to investigate how internal knee joint forces depend on applied external moments during gait. Musculoskeletal models of the gait of 10 healthy subjects were developed in the AnyBody Modelling System and used to simulate applied joint moments about different axes (load cases), each with the magnitude to compensate the net moment about the respective axis by a specified percentage. For each load case, the total, medial and lateral knee compressive force were computed and compared with a baseline case with no external moments applied. Among the investigated moments, hip flexion-extension, knee flexion-extension and ankle plantarflexion-dorsiflexion moment compensations have the most positive impact on the total knee joint compressive force, and combining the 3, each with a 40% compensation of the muscle moments, reduced the first peak by 23.6%, the second by 30.6% and the impulse by 28.6% with respect to no applied moments.

Acute and mid-term (six-week) effects of an ankle-foot-orthosis on biomechanical parameters, clinical outcomes and physical activity in knee osteoarthritis patients with varus malalignment

BACKGROUND

Knee osteoarthritis (KOA) is a painful disease commonly caused by high loads on the articular cartilage. Orthotic interventions aim to reduce mechanical loading, thereby alleviating pain. Traditional orthotics appear effective, but high drop-out rates have been reported over prolonged periods.

RESEARCH QUESTION

The aim of this study was to examine the effect of a novel ankle-foot orthosis (AFO) on gait parameters, physical function and activity of KOA patients.

METHODS

29 clinically diagnosed KOA patients with varus malalignment wore an AFO for 6 weeks. Prior to and after the intervention period, 3D gait analysis, physical function tests and the KOOS questionnaire were administered. Physical activity was objectively assessed with accelerometers.

RESULTS

The AFO immediately reduced the first peak of the knee adduction moment (KAM) and the KAM impulse by 41% and 19%. The knee flexion moment (KFM) was increased by 48%. After six weeks, the first KAM peak and KAM impulse were decreased by 27% and 19% while using the AFO. The KFM was increased by 71%. Furthermore, patients completed the functional tests faster (1.4-2.6%). The KOOS scores decreased significantly. No significant differences were found in physical activity parameters.

SIGNIFICANCE

The six-week AFO application significantly reduced the KAM. The patients' physical function appeared improved; yet these improvements were only minor and therefore arguably clinically irrelevant. The KFM appeared to be negatively affected after six weeks, as were the scores on the KOOS subscales. In summary, even though the AFO reduced the KAM and improved physical function, the clinical benefit for KOA patients with varus malalignment after the 6-week AFO application is debatable.

Good short- to medium-term results after osteochondral autograft transplantation (OAT) in middle-aged patients with focal, non-traumatic osteochondral lesions of the knee

BACKGROUND

Osteochondral autograft transplantation (OAT) offers the opportunity to repair cartilaginous defects by restoring hyaline cartilage anatomy. Encouraging results have been reported in patients suffering from acute knee trauma or osteochondritis dissecans. Patients with focal chronic, non-traumatic osteochondral (FCNO) lesions of the knee, however, have rarely been the subject of investigation. Some authors even consider higher age as contraindications to OAT.

OBJECTIVES

To assess the short- to medium-term outcomes of OAT in middle-aged patients with FCNO lesions of the knee and to identify predictors of clinical outcome.

HYPOTHESIS

Filling FCNO defects with autologous osteochondral grafts should restore the congruency of the middle-aged knee joint and thereby reduce pain and loss of function on the one hand, and increase quality of life on the other hand.

METHODS

One hundred and twelve patients (48.01±1.12yrs) with FCNO of the knee were assessed before OAT and 26.2±0.24 months after surgery. Clinical outcome was measured by WOMAC Index and the Visual Analogue Scale (VAS) for pain.

RESULTS

Pain (pre-OAT VAS vs. post-OAT VAS: 7.14±0.19 vs. 3.74±0.26, P<0.001) was reduced and quality of life (pre-OAT WOMAC vs. post-OAT WOMAC: 134.88±5.84 vs. 65.92±5.34, P<0.001) improved. Retropatellar defects were associated with poor outcome, while overall surface and number of cylinders were not.

DISCUSSION

Middle-aged patients with FCNO of the knee also profit from OAT at a short follow-up.

LEVEL OF EVIDENCE

IV. Mono-centric, prospective clinical series.

Biomechanical effect of unloader braces for medial osteoarthritis of the knee: a systematic review (CRD 42015026136)

PURPOSE

There is a lack of consensus regarding biomechanical effects of unloader braces for the treatment of medial osteoarthritis (OA) of the knee. The purpose of this study was to perform a systematic review of studies examining the biomechanical effect of unloader braces.

METHODS

A systematic search for articles about the biomechanical effect of unloader braces was performed. Primary outcome measure was the influence of the brace on the knee adduction moment. Data sources were Pubmed central and google scholar.

RESULTS

Twenty-four articles were included. Twenty articles showed that valgus unloader braces significantly decrease the knee adduction moment. Seven of those studies reported a decrease of pain in braced patients (secondary outcome measure). Positive effects on the knee adduction moment could be found for custom made braces for conventional knee braces and for a foot ankle orthosis. Four studies could not show any effect of knee unloader braces on the knee adduction moment although one of these studies found decreased pain in braced patients. One of these studies examined healthy patients with a neutral axis.

CONCLUSION

This systematic review could demonstrate evidence that unloader braces reduce the adduction moment of the knee. Foresighted, a systematic review about the clinical effect of unloader braces is required.

Effects of a novel foot-ankle orthosis in the non-operative treatment of unicompartmental knee osteoarthritis

INTRODUCTION

Unloader braces are non-surgical treatment options for patients with unicompartmental knee osteoarthritis (OA). However, many patients do not adhere to brace treatment because of complications related to discomfort and poor fit. An alternative to knee bracing is an ankle-foot orthosis (AFO) with a lever arm that presses the lower leg into valgus or varus. The aim of this study is to evaluate the clinical benefits of this AFO for patients with unicompartmental knee OA.

MATERIALS AND METHODS

Twenty-three patients with knee OA were enrolled in this observational study. The primary clinical outcome measure was the Western Ontario and McMasters Universities Arthritis Index (WOMAC) total score. Secondary outcome measures included WOMAC subscores, visual analogue pain scale, activity restriction and complication rate. Clinical scores were collected at start and 3, 6, 9, and 12 months after enrollment. Statistical evaluation was performed using the Student's t test.

RESULTS

Of the patients enrolled, 83 % suffered from medial compartment OA. Most patients had Grade II OA according to the Kellgren and Lawrence classification. WOMAC total score, both subscores and visual analogue pain scale were significantly improved over time. Patients also noted a reduction in restrictions to activities of daily living and sport-related activities while using the AFO. No patients discontinued orthosis use because of adverse effects. Two types of complications were noted: discomfort or light pressure sores around the ankle (7 patients), and wear and tear of the shoe in which the AFO was worn (14 patients).

CONCLUSIONS

This observational study suggests that this AFO is effective at significantly reducing pain and stiffness as well as improving the physical function of patients with mild to moderate unicompartmental osteoarthritis of the knee.