Is valgus unloader bracing effective in normally aligned individuals: implications for post-surgical protocols following cartilage restoration procedures

Advances in active knee brace technology: A review of gait analysis, actuation, and control applications

This article discusses the significance of knee joint mechanics and the consequences of knee dysfunctions on an individual's quality of life. The utilization of active knee braces, which incorporate concepts of mechatronics systems, is investigated here as a potential treatment option. The complexity of the construction of the knee joint, which has six degrees of motion and is more prone to injury since it bears weight, is emphasized in this article. By wearing braces and using other support devices, one's knee can increase stability and mobility. In addition, the paper discusses various technologies that can be used to measure the knee adduction moment and supply spatial information on gait. Actuators for active knee braces must be compact, lightweight, and capable of producing a significant amount of torque; as a result, electric, hydraulic, and pneumatic actuators are the most common types. Creating control mechanisms, such as position control techniques and force/torque control approaches, is essential to knee exoskeleton research and development. These methods might make knee joint rehabilitation and assistive technology safer and more effective.

Unloader bracing in osteoarthritis of the knee - Is there a direct effect on the damaged cartilage?

BACKGROUND

Unloading knee braces represent a conservative treatment option for non-pharmalogical management of unicompartmental osteoarthritis of the knee. Though there is consensus on the clinical effectiveness of unloading, the effect mechanism of bracing remains part of a debate. Our study was designed to assess the effect of unloader bracing on damaged cartilage via MRI cartilage mappings.

METHODS

Fourteen patients (7 female, 7 male, mean age 43.1 ± 9.4 years) with unicompartmental cartilage wear in knees with varus or valgus malalignment were enrolled. Clinical scores, radiographs and MR-graphic properties (T2/T2* mapping, T1 Delayed Gadolinium Enhanced MRI of the cartilage (dGEMRIC) mapping, high-resolution PDw sequences) of knee cartilage were recorded before and three months after brace use.

RESULTS

Bracing the knees for a mean of 14.4 ± 2.0 weeks (range 11 to 18 weeks) resulted in significant pain reduction (VAS changed from 5.9 ± 2.0 to 2.0 ± 1.3, p < 0.001) and improvement in knee function (KOOS increased from 42.1 ± 22.7 to 64.8 ± 18.7, p < 0.001). In the affected cartilage regions T2 relaxation times significantly decreased from 56.1 ± 11.4 ms to 46.5 ± 11.2 ms (p < 0.05). No changes in T1-dGEMRIC and T2* relaxation times, thickness or the extent of the damaged cartilage area could be detected.

CONCLUSIONS

Our results suggest, that unloader bracing improves the biochemical properties of the damaged cartilage by increasing collagen and proteoglycan concentration as well as decreasing the cartilage edema.

Comparison of the Healing Outcomes of Conservative Treatment for Stable Juvenile Osteochondritis Dissecans of the Lateral Femoral Condyle With Normal Lateral Meniscus and Incomplete Discoid Lateral Meniscus

BACKGROUND

This study aimed to compare the healing outcomes of conservative treatment for osteochondritis dissecans (OCD) of the lateral femoral condyle with normal lateral meniscus and incomplete discoid lateral meniscus (DLM).

METHODS

Forty-four knees in 37 juvenile patients (mean age 9.9 y) with stable OCD and whose lateral meniscus shape was normal or incomplete DLM were enrolled. All patients underwent conservative treatment with physical activities prohibited. For each lateral meniscus group, patient demographics including pretreatment Tegner activity scale, OCD stage, and Lysholm score, radiographic healing status; complete or incomplete healing at 3 months, 6 months, and 1 year, time to complete healing and post-treatment clinical scores were evaluated.

RESULTS

There were 21 (47.8%) and 23 (52.3%) knees with normal menisci and incomplete DLM, respectively. At 3 months, 6 months, and 1 year after conservative treatment, healed OCD status was noted in 3 (14.3%), 12 (57.1%), and 19 (90.5%) knees of the normal type and in 3 (13.0%), 12 (52.2%), and 20 (86.9%) knees of the incomplete DLM type, respectively (P>0.05). The mean time to healing in each group was 198 and 181 days, respectively. No significant differences in terms of OCD healing rate at each time, time to healing, and post-treatment clinical scores were found between the groups.

CONCLUSION

No significant differences in the OCD healing rate or time to healing were found between the normal and incomplete DLM type. Therefore, treatment strategy for OCD with stable and asymptomatic incomplete DLM should be the same as that for those occurring with a normal meniscus.

High rate of return-to-play following meniscal allograft transplantation

PURPOSE

In recent years, meniscal allograft transplantation (MAT) has been established as an effective option for young patients with symptomatic meniscus insufficiency with goals of functional improvement and joint preservation. Currently, there is little available information on return-to-play among patients in this cohort. The purpose of this study is to systematically review the literature and to evaluate the reported rehabilitation protocols, return-to-play guidelines, and subsequent rates of return-to-play following MAT.

METHODS

MEDLINE, EMBASE and the Cochrane Library were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to find studies on MAT. Studies were included if they reported return-to-play data or rehabilitation protocols. The rate and timing of return-to-play was assessed. The rehabilitation protocols were recorded, including time to start range of motion (ROM), full ROM, partial weight bearing (WB), and full WB.

RESULTS

Overall, 67 studies met the inclusion criteria. Eleven studies, including 624 patients, reported 483 out of 624 patients (77.4%) returning to play, with 326 out of a reported 475 patients (68.6%) returning to the same/higher level, at a mean time to return of 9.0 months. There was significant variability in the reported rehabilitation protocols, but the most commonly reported time to begin ROM exercises was within the first week by 42 out of 60 studies (70.0%) and full ROM at 8 weeks by 18 out of 46 studies (39.1%). Partial weight bearing was most commonly begun in the fourth week by 20 out of 46 studies (43.5%), and for full WB the sixth week by 43 out of 65 studies (66.1%). Time elapsed following surgery was the most commonly reported criteria for return-to-play by 44 out of 48 studies (91.6%), with 6 months being the most common time point utilized by 17 out of 45 studies (37.8%). A small proportion of studies, 16 out of 48 (33.3%), advised against returning to competitive/collision sports altogether following MAT.

CONCLUSIONS

In conclusion, there is a high rate of return-to-play following MAT, with the majority of patients returning to the same level of play. However, there is significant variability in reported rehabilitation protocols, and poor-quality reporting in return-to-play criteria in the literature indicates a need for further study and the development of an evidence-based consensus statement for this patient population. The results from this study can be used to better inform patients on their expected outcomes and provide a more informed consent process.

LEVEL OF EVIDENCE

IV.

Immediate effects of valgus bracing on knee joint moments during walking in knee-healthy individuals: Potential modifying effects of body height

BACKGROUND

The goal of valgus knee brace treatment is to reduce medial knee joint loading during walking, often indicated by external knee adduction moment (KAM) measures. However, existing healthy-subjects studies have been equivocal in demonstrating KAM reduction with valgus knee bracing.

RESEARCH QUESTION

What are the immediate effects of valgus bracing at different tension levels on KAM during walking at a controlled speed and does body height modify the brace-KAM associations?

METHODS

Data from 32 knee-healthy participants were analysed in this randomized crossover trial. Participants performed walking trials at controlled speed (1.3 ± 0.065 m/s) both with and without an Ossür Unloader One® brace. During the bracing condition, valgus tension was incrementally increased, from zero tension to normal tension and to maximum tolerable tension.

RESULTS

Valgus bracing minimally increased knee flexion at heel-strike (P < 0.001) in a dose-dependent manner and minimally reduced gait velocity (∼0.015m/s) across all tension levels. Valgus bracing, overall, did not significantly reduce the various KAM measures. However, brace use at maximal tension was associated with a 0.04Nm/kg (9.2 %) increase in first peak KAM amongst participants with a body height of 1.75 m and a 0.03Nm/kg (7.6 %) decrease in first peak KAM amongst participants with a body height of 1.55 m.

SIGNIFICANCE

Valgus bracing did not reduce the various KAM measures during walking; however, body height may play a moderating role. Given knee brace sizes vary more in circumference than length, this result may be due to the ratio between effective moment arm length relative to limb length. A deeper understanding of the potential neuro-biomechanical effects of valgus knee bracing and how these effects are potentially modified by body height may be critical to the design of effective knee braces.

Effects of a knee valgus unloader brace on medial femoral articular cartilage deformation following walking in varus-aligned individuals

BACKGROUND

Knee varus alignment may increase loading in the medial tibiofemoral compartment, which can increase strain on the articular cartilage. Knee valgus unloader braces seek to reduce loading through the medial femoral compartment, but their effects on cartilage characteristics during dynamic tasks have not been evaluated.

OBJECTIVE

To determine the effects of a knee valgus unloader brace on medial femoral articular cartilage deformation following a single 5000-step walking protocol in individuals with varus-knee alignment.

METHODS

Twenty-four healthy individuals (63% female, BMI = 22 ± 3 kg/m², age = 21 ± 3 years) completed two testing sessions (braced and unbraced) separated by one week. During both sessions, femoral cartilage ultrasound images were acquired prior to and following a 5000-step treadmill walking protocol at self-selected speed. Percent change scores in medial cartilage cross-sectional area (MCCA) were calculated and used as the primary outcome, and compared between the braced and unbraced conditions.

RESULTS

There was no difference in percent change of MCCA between conditions (braced = -2.77%, unbraced = -3.15%, p = 0.699). Individuals whose cartilage deformed more than a previously established minimal detectable change (MDC ≥ 1.58 mm²) deformed less during the braced condition (braced = -2.94%, unbraced = -6.34%, p = 0.028), compared to individuals who did not deform greater than the MDC (n = 15, braced = -2.67%, unbraced = -1.23%, p = 0.210).

CONCLUSIONS

There was no significant difference in MCCA percent change between the braced and unbraced conditions across the entire cohort; yet a valgus unloader braces may serve as a potential intervention strategy for reducing articular cartilage deformation in certain varus-aligned individuals who normally undergo measurable deformation during walking.

Contributions of muscles and external forces to medial knee load reduction due to osteoarthritis braces

BACKGROUND

Braces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads.

METHODS

In this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions.

RESULTS

Across all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads.

CONCLUSIONS

Knee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.

Temporary postoperative treatment with compartment-unloading knee braces or wedge insoles does not improve clinical outcome after partial meniscectomy

PURPOSE

To investigate whether temporary postoperative compartment-unloading therapy after arthroscopic partial meniscectomy (APM)-with either knee braces or wedge insoles-leads to superior clinical outcome as compared to controls. This difference in clinical outcome was tested in the form of two knee scores, physical activity and general health outcome over the first postoperative year.

METHODS

Sixty-three patients who underwent arthroscopic partial meniscectomy (APM) were randomized to one of the following three groups: 12 weeks postoperative knee compartment-unloading therapy with either a knee brace (brace group) or wedge insoles (insole group) or no specific postoperative therapy (control group). Patient-reported outcome was assessed with the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC Score), the Knee Injury and Osteoarthritis Outcome Score (KOOS), the MARX score (physical activity) and the SF-12 (general health).

RESULTS

Sixty-three patients were available for analysis. Except for the SF-12 mental score, all other scores showed significant improvement over time. With regard to the hypotheses proposed, no significant group * time interactions were observed for any of the outcome parameters. This means that the group (i.e. the type of postoperative treatment) was not related to the degree of improvement of any of the scores.

CONCLUSIONS

It was concluded that 12 weeks of compartment-unloading therapy-with either a knee brace or wedge insoles-is ineffective with regard to clinical outcome after APM. This applies to the knee score outcome, physical activity and general health outcome over the first year following APM.

LEVEL OF EVIDENCE

Randomized controlled trial, Level I.

Medial Unloader Braces and Lateral Heel Wedges Do not Alter Gait Biomechanics in Healthy Young Adults

Context: Orthotic devices such as medial unloader knee braces and lateral heel wedges may limit cartilage loading following trauma or surgical repair. However, little is known regarding their effects on gait biomechanics in young, healthy individuals who are at risk of cartilage injury during physical activity due to greater athletic exposure compared with older adults. Objective: Determine the effect of medial unloader braces and lateral heel wedges on lower-extremity kinematics and kinetics in healthy, young adults. Design: Cross-sectional crossover design. Setting: Laboratory setting. Patients: Healthy, young adults who were recreationally active (30 min/d for 3 d/wk) between 18 and 35 years of age, who were free from orthopedic injury for at least 6 months, and with no history of lower-extremity orthopedic surgery. Interventions: All subjects completed normal over ground walking with a medial unloader brace at 2 different tension settings and a lateral heel wedge for a total of 4 separate walking conditions. Main Outcome Measures: Frontal plane knee angle at heel strike, peak varus angle, peak internal knee valgus moment, and frontal plane angular impulse were compared across conditions. Results: The medial unloader brace at 50% (-2.04° [3.53°]) and 100% (-1.80° [3.63°]) maximum load placed the knee in a significantly more valgus orientation at heel strike compared with the lateral heel wedge condition (-0.05° [2.85°]). However, this difference has minimal clinical relevance. Neither of the orthotic devices altered knee kinematics or kinetics relative to the control condition. Conclusions: Although effective in older adults and individuals with varus knee alignment, medial unloader braces and lateral heel wedges do not influence gait biomechanics in young, healthy individuals.

Delayed Rehabilitation After Lateral Meniscal Allograft Transplantation Can Reduce Graft Extrusion Compared With Standard Rehabilitation

BACKGROUND

Meniscal extrusion prevention would be important for restoring normal knee kinematics, even though the effect of graft extrusion after meniscal allograft transplantation (MAT) has not been clearly identified.

HYPOTHESIS

When compared with standard rehabilitation protocols, delayed rehabilitation after lateral MAT could reduce graft extrusion.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 53 patients who underwent lateral MAT with the keyhole technique from June 2011 to March 2015 were included. Graft extrusion and lateral compartment articular cartilage loss on magnetic resonance imaging, joint space width (JSW) on weightbearing radiographs, and clinical outcomes (including subjective scores and functional tests) of 25 patients who underwent standard rehabilitation (group S) after lateral MAT were compared with those of 28 patients who underwent delayed rehabilitation (group D), which included immobilization during the first 3 weeks and use of unloading braces for 9 weeks.

RESULTS

Mean ± SD follow-up times for groups S and D were 25.7 ± 6.4 and 24.5 ± 7.1 months, respectively. Although the postoperative clinical outcomes did not differ between the groups, graft extrusion (3.2 ± 1.5 mm vs 1.8 ± 1.6 mm) and relative percentage of extrusion (32.2% ± 14.6% vs 17.3% ± 16.6%) were greater in group S than in group D ( P < .001 for both). The percentage of patients with graft extrusion (≥3 mm) was 52% in group S and 21.4% in group D. JSWs on Rosenberg view decreased by 0.1 mm in group S but increased by 0.3 mm in group D ( P = .035). Kellgren-Lawrence grade and modified Outerbridge grade progressed by 44% and 44% among patients in group S and by 17.9% and 21.4% among patients in group D, respectively. There were significant correlations between the coronal graft extrusion and postoperative JSWs on full extension (-0.452) and Rosenberg (-0.410) views, Kellgren-Lawrence grade (0.727), and modified Outerbridge grade (0.732) on magnetic resonance imaging ( P < .001 for all).

CONCLUSION

Compared with standard rehabilitation, delayed rehabilitation showed less coronal graft extrusion and joint space narrowing on weightbearing and reduced the progression of arthrosis, although the rehabilitation protocols showed no differences in clinical outcomes.

The 2- and 8-week effects of decompressive brace use in people with medial compartment knee osteoarthritis

BACKGROUND

Knee osteoarthritis is a prevalent disease. Unloading the affected compartment using a brace is a treatment option.

OBJECTIVES

To determine whether a decompressive knee brace alters loading in medial knee osteoarthritis following 2 and 8 weeks of use.

STUDY DESIGN

Within subjects; pre- and post-testing.

METHODS

A total of 15 individuals with medial knee osteoarthritis attended four sessions: baseline, fitting, 2 weeks after fitting (post), and 8 weeks after fitting (final). A gait analysis was performed at baseline (without knee brace), post and final. Knee adduction impulse, first and second peak knee adduction moment, knee motion, and walking velocity were calculated. Participants also recorded hours and steps taken while wearing the brace.

RESULTS

On average, the brace was worn for more than 6 h/day. Through use of repeated-measures analysis of variance, it was determined that the knee adduction impulse and second peak knee adduction moment were reduced (p < 0.05) at post and final compared to baseline (36% and 34% reduction in knee adduction impulse, 26% reduction in second peak knee adduction moment for post and final, respectively). Furthermore, participants walked faster with increased knee motion during stance.

CONCLUSION

The studied decompressive brace was effective in reducing potentially detrimental forces at the knee-knee adduction impulse and second peak knee adduction moment during the stance phase of gait.

CLINICAL RELEVANCE

The data from this study suggest that use of a medial unloading brace can reduce potentially detrimental adduction moments at the knee. Clinicians should use this evidence to advocate for use of this noninvasive treatment for people presenting with medial knee osteoarthritis.

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.

Current state of unloading braces for knee osteoarthritis

PURPOSE

Unicompartmental knee osteoarthritis (OA) is often treated with the prescription of an unloading knee brace to decrease pain and stiffness. Braces have been shown to improve the quality of life by applying an external moment to offset increased compressive tibiofemoral contact loads, but evidence regarding mechanical efficacy at the joint is controversial. Thus, the purpose of this study was to review the current state of unloading braces on knee mechanics, clinical impact, and long-term disease progression.

METHODS

A literature search was performed through the PubMed MEDLINE database for the search terms "osteoarthritis," "knee," "brace," and derivatives of the keyword "unload." Articles published since January 1, 1980 were reviewed for their relevance. Evidence for the effectiveness of unloading braces for disease management both biomechanically and clinically was considered.

RESULTS

While significant research has been done to show improvement in OA symptoms with the use of an unloading brace, current literature suggests a debate regarding the effectiveness of these braces for biomechanical change. Clinical findings reveal overall improvements in parameters such as pain, instability, and quality of life.

CONCLUSION

Although clinical evidence supports brace use to improve pain and functional ability, current biomechanical evidence suggests that unloading of the affected knee compartment does not significantly hinder disease progression.

LEVEL OF EVIDENCE

III.

Management strategies for osteochondritis dissecans of the knee in the skeletally immature athlete

SYNOPSIS

Osteochondritis dissecans (OCD) is a disorder resulting in focal breakdown of the subchondral bone, with potential disruption of the overlying articular cartilage. The femoral condyles of the knee are the most common locations for OCD, and the incidence of OCD appears to be increasing among active children. Juvenile OCD (JOCD) can be distinguished from adult OCD by the presence of open growth plates. Due to a lack of evidence on its early diagnosis, optimal treatment, and long-term course of healing, JOCD presents a unique challenge for the health care team. Approximately 50% to 67% of stable JOCD lesions heal successfully with nonoperative treatment. For unstable lesions and stable lesions that fail nonoperative treatment, a variety of surgical interventions can be utilized to stimulate bony healing and address articular cartilage lesions. It is recommended that rehabilitation of JOCD be tailored to the individual patient, based on the stage and radiographic status of the lesion and the mode of surgery employed when surgically addressed. Although there is a growing body of literature on this condition, the etiology and optimal methods for treatment, rehabilitation, and evaluating outcomes remain inconclusive due to a lack of quality evidence.

LEVEL OF EVIDENCE

Therapy, level 5.