SOFTEC OSTEOARTHRITIC KNEE BRACE
The SofTec [Bauerfeind] OA knee brace is manufactured by Bauerfeind and is a multifunctional orthosis for medial OA of the knee. It can also be used after an injury of the menisci. The knee brace is advertised to stabilize and relieve pressure on the affected area, while permitting muscle activation. The orthosis consists of a Bauerfeind’s patented SofTec knit-and-strap system with contoured shells, pressure cushioned pads, and an air bladder system that can be filled or emptied to unload the medial compartment of the knee as needed to decrease pain.
In a study performed by Gaasbeek et al.,67 15 patients were fitted with a SofTec OA brace with medial compartment OA. The knee brace was worn 7 days a week for 6 weeks. After 6 weeks, statistically significant improvements were found on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for function and the visual analog scale (VAS) for pain during walking. The mean ± sd score on the WOMAC was 50.1 ± 17.6 without the orthosis and 63.0 ± 18.4 with the SofTec orthosis, which provided a medial force to offload the medial compartment of the knee. The mean ± sd score on the VAS pain scale was 6.8 ± 2.5 without the orthosis and 4.7 ± 3.0 with the orthosis.67 These findings were consistent with the results presented in a previous study by Van Heerwaarden et al.68 with 15 subjects in 2005.
THRUSTER 2/DYNAMIC UNLOADING OSTEOARTHRITIS KNEE BRACE
The “Thruster 2” by Bledsoe is no longer available and has been replaced by the DUO brace. The designs of the DUO and the Thruster 2 are similar (refer to Table 3 for DUO picture). Like the Thruster 2, the DUO is the only double-upright “dynamic” OA brace on the market that creates a load across the joint when the knee is straight and reduces the load when the knee is flexed. The brace is popular because it can be used all day and is indicated for low activity levels such as golf and bowling as well as for patients with redundant tissue.
Dennis et al.69 performed two investigations using the Thruster 2 brace. The first investigation fitted 45 individuals with a Thruster 2 brace with symptomatic medial unicompartment OA. Forty of the subjects were fitted with a Thruster 2 brace according to the guidelines provided by the manufacturer, and the other five subjects were simply given a Thruster 2 brace and not instructed in how to offload the degenerated compartment. Successive fluoroscopic images were performed on each individual in stance phase on a treadmill with and without their brace. The results of the first study revealed the following: 1) 85% of the subjects (34/40) with the properly applied Thruster 2 brace experienced reduced knee pain, and fluoroscopic images demonstrated medial condylar compartment separation, and 2) 15% of those (6/40) who did not have a properly fitted brace reported a lack of pain relief and did not demonstrate any increase in condylar separation magnitude or angle. The lack of pain relief within the six participants was explained as caused by a loosely applied brace that did not cause condylar separation, and in one case, the participant was obese and the brace did not fit properly.69
In the second investigation, Dennis et al.69 once again used five subjects with symptomatic medial unicompartment OA. Each subject was fluoroscoped while performing normal gait on a treadmill wearing five different offloading braces to analyze the effectiveness of each brace. The five offloading braces were the Bledsoe Thruster 2, Donjoy OA Adjuster, Őssur OAsys, Őssur Generation II, and an anterior cruciate ligament brace. The results of the second investigation identified the following information: 1) the ACL brace revealed no medial compartment separation during the stance phase of gait; 2) all five offloading braces experienced the greatest medial condylar separation at heelstrike compared with the midstance and toe-off phases of gait; 3) the Bledsoe Thruster 2 and the Donjoy OA Adjuster provided the greatest amount of condylar separation at heelstrike compared with the other three braces; 4) the Bledsoe Thruster 2 was the only brace that produced the greatest condylar separation at midstance and toe-off; 5) the Donjoy OAdjuster had the second best condylar separation with toe-off; and 6) overall, the Bledsoe Thruster 2 and Donjoy OAdjuster braces provided the greatest amount of condylar separation during all five analyzed gait phases.69
Another article written by Hewett et al.51 collected information on 18 patients who were fitted with the Bledsoe’s Thruster 2 for a period of 1 year. The subjects had been instructed to wear the brace for as many hours and days of the week as possible. At the end of 1 year, the authors found that 1) the walking time while wearing the Thruster 2 doubled from 51 to 138 minutes without medication after 9 weeks of wear to 107 minutes after 1 year of wear; 2) 83% (15 subjects) benefited from a reduction in pain symptoms while wearing their brace; 3) the brace had little impact on returning a patient back to his/her sports activities; 4) the brace had little effect on returning a patient back to work, who was originally considered as having a disability because of the knee pain; 5) patients tended to wear the brace for a mean time of 7 hours each day, 5 days a week; 6) thirteen patients or 72% continued to wear the brace after 1 year; 7) there were no significant improvements in stair climbing; 8) there was no observed decrease in the adduction moment of the involved knee when wearing the brace; 9) there were no readily apparent gait adaptions after brace application; 10) the peak force during stance and gait velocity were not altered with brace wear; and 11) there were no differences between the adduction moment at the hip, the flexion or the extension moment at the knee, or the inversion/eversion moments at the ankle with brace wear.
Komistek et al.53 had 15 subjects with medial unicompartmental OA fitted with a Bledsoe Thruster 2 and asked their subjects to walk on level ground and rated the effectiveness of the brace to alleviate pain in their affected knee. The subjects were then asked to perform normal gait on a treadmill while wearing the brace. Fluoroscopic images of each patient’s knee were taken walking on level ground and on the treadmill before and at stance phase with and without the brace. Twelve subjects, or 80%, judged the brace as being effective in reducing knee pain, whereas three of the subjects, or 20%, were unable to detect a change in knee pain. The three subjects who exhibited minimal benefits in knee pain were rated as below average candidates because of poor fixation due to obesity. In addition, the 12 subjects who had reduced knee pain while wearing their knee brace also had significant separation of the medial condyle from the tibial plateau. These findings were similar to those of Hewett et al.51
Nadaud et al.70 used five subjects with substantial unicompartmental OA and analyzed whether five off-the-shelf OA braces provided separation of the femoral condyle from the tibial plateau with the use of a video fluoroscopy. They hypothesized that if excessive loads on the degenerative compartment were relieved, the pain associated with compartmental pressure would also be relieved. To achieve this goal, each subject was fitted with five off-the-shelf OA braces and asked to perform normal gait while under fluoroscopic surveillance. The five off-the-shelf OA braces were the Bledsoe Thruster 2, the Donjoy OA Adjuster, the Breg Tradition X2K, Őssur’s OAsys, and Őssur’s Unloader Spirit.53
The findings from the study of Nadaud et al.70 indicated a noticeable variability between the five braces, with the Bledsoe Thruster 2 producing the best results followed by the Donjoy OA Adjuster brace. The other three braces demonstrated more variables and less optimal results. The Thruster 2 and OA Adjuster braces were also effective in offloading the knee at heelstrike and least effective at midstance. In conclusion, the study concluded that OA bracing, specifically the Bledsoe Thruster 2 and the Donjoy OAdjuster brace, was an effective mode of treating unicompartmental degeneration, especially in younger patients.
LEGACY THRUSTER OSTEOARTHRITIS
The Legacy Thruster OA is made by Bledsoe and is advertised as the “next generation of the OA Thruster brace.” This brace is a smaller, lighter single-upright model that has its hinge on the affected side of the knee. Relief on the affected side of the knee is achieved by pulling the brace’s straps to open the joint space versus pushing it against the opposite side of the knee. This particular design is for OA only and not associated with ligament instability.
One evidence-based article was found on this brace. This article was written by Hillstrom et al.25 and compared the OA Thruster valgus knee brace with a neutral-position foot orthotics to determine which orthosis relieved knee pain secondary to OA. The results from the study indicated that both orthoses significantly improve lower-limb biomechanics during gait, ADLs, and pain assessments in varus knee OA patients.
FUSION OSTEOARTHRITIC KNEE BRACE
Made by Breg, the Fusion OA knee brace has double uprights and features a user-friendly thumbwheel dial hinge that makes it easy to adjust the level of offloading for optimal medial or lateral support without using a tool.71
In a study by Smith et al.,72 “at-risk” OA patients who were prescribed a Fusion OA knee brace for 3 years were assessed, and it was found that all participants using the brace had a very high compliance rate. From the study’s results, it was concluded that the Fusion OA knee brace had proven to be cost-effective and had resulted in retarding the progressive degenerative changes over the long-term while restoring the functional capabilities of the patient.
The Defiance OA is manufactured by Donjoy. This brace is indicated for an individual with unicompartmental OA and has a “4-Points-of-Leverage System” that also offers ligament stability. To achieve this, the brace’s telescoping condyle pad shifts compressive knee joint forces from the degenerative area to the healthy compartment, and a Universal OA key enables the patient to make control load adjustments to meet his/her daily needs. Because of its “perfect fit,” this brace is ideally suited for active patients.76
As mentioned previously, the study performed by Draganich et al.64 found that patients who wore the custom Defiance OA had increased function over the off-the-shelf OA Adjuster knee brace. The increased function was attributed to the Defiance OA having a better fit, which resulted in decreased pain within the OA knee.
Giori77 also used the Defiance OA in his study that performed a follow-up investigation after 2½ years on 33 patients who were fitted with a Defiance OA knee brace and 7 patients who were fitted with a Bauerfeind MOS Genu Brace. The results of this study found that the patients fitted with a Defiance OA knee brace were still using their brace and continued to experience pain relief and functional improvement 3 years later. The survival of this load-shifting brace was 76% at 1 year and 69% at 3 years after delivery of the brace. Survival of brace use was believed to be associated with the age of the patient, in that the younger patients had a higher likelihood than the older patients of longer brace use.
In addition to the increased survival rate of the Defiance OA knee brace, it was also noted that among the 46 patients reviewed, 2 had experienced potential life-threatening complications of venous thrombosis and/or thromboembolism. Both patients had these complications 10 days to 2 weeks after receiving their braces. The patients were older in age, 82 and 84 years. It was believed that tight bracing of the knee could have caused venous stasis in the limb and deep vein thrombosis and pulmonary embolus. On the basis of this information, the authors recommended that patients should be counseled regarding these potentially serious complications.78
The OA Adjuster is manufactured by Donjoy and has a biaxial hinge that allows for a double-upright design to contour the leg, provide a comfortable fit, and prevent migration. This brace includes a new “Lock and off-Load Technology” that shifts compressive knee joint forces from the degenerative area to the healthy compartment as well as a Universal OA key that enables the patient to control the load adjustment to meet his/her daily needs.73
Dennis et al.69 published their findings in the Journal of Arthroplasty in 2006 and found that 34 of 40 of the participants within this study, or 85%, experienced pain relief from the OA Adjuster and from a second offload OA knee brace, the Thruster 2 (DUO) made by Bledsoe.69 The study also found that the Donjoy OA Adjuster and the Bledsoe Thruster provided the greatest amount of condylar separation during all five analyzed gait phases, but there was no statistical analysis performed to determine whether there was a significant association between the patient’s subjective pain relief and condylar separation.
Within the investigative report published by Draganich et al.,64 10 patients were randomly evaluated in the OA Adjuster and Defiance OA knee braces made by Donjoy. The OA Adjuster was an off-the-shelf OA knee brace and the OA Defiance was a custom OA knee brace. Both braces were similar in structural design with thigh and leg straps, a double-upright strap, and frame style with rigid thigh and calf support members that were connected to polycentric hinges located on the medial and lateral sides. In addition, both braces allowed the wearer to adjust the amount of valgus loading applied by the brace to the knee with an OA key. Pain and function were assessed using the WOMAC, which measures pain, stiffness, and physical function.74 Measurements were taken before application of the orthoses as well as 4–5 weeks after. Pain was significantly reduced from a mean baseline of 197–120 mm with the OA Adjuster and to a mean of 71 mm with the Defiance OA. There was also a significant difference in function between the two braces. Function increased significantly with the custom Defiance OA. The authors attributed the success of the Defiance OA to the better fit and concluded that an intimate fit is necessary for improved results and increased pain relief.64
Finger and Paulos75 took 23 participants and assessed their pain before being fitted with an OA Adjuster knee brace and at 3 months using a 10-point pain scale. At 3 months, the mean resting pain decreased from 4.2 to 1.9, pain with activity decreased from 7.2 to 3.9, and night pain decreased from 3.9 to 2.4. No statistical analysis was performed on these numbers to determine whether the changes were significant.
Donjoy Global, Inc, introduced the OA Nano on July 9, 2012. This new OA brace had the same key features as those of the OA Adjuster, which were tested by Dennis et al., Draganich et al., and Finger et al.49,64,75 The key features include the double-upright frame, the system that has four points of leverage for ligament stability, and the Lock and off-Load Technology, which shift the compressive knee joint forces from the degenerative compartment to the healthy side.64,69,75 The major distinctive difference of the OA Nano and the OA Adjuster is the OA Nano’s construction, made of a revolutionary new metal “nanoMAG TTMP,” which is light as magnesium with the strength of aircraft-grade aluminum. Because of the brace’s light weight of 14.2 oz, the brace is especially popular with the person who is active and likes to move freely. Because of its ease in donning/doffing and comfort, the Arthritis Foundation has also granted the OA Nano the “Ease of Use” commendation.78
The Unloader ADJ [adjustable dynamic joint] is designed for OA patients who have excessive soft tissue because of being overweight, elderly, or both. Made by Őssur, the Unloader ADJ is based on the same principles as those of the Unloader Select, with a more flexible shell and elastic straps that are wider to contain excess tissue.
Draper et al.82 used objective measurements of function to determine whether the use of a valgus brace did significantly outperform a neoprene sleeve for OA knee patients. Each patient was fitted with a custom-made valgus brace, the Unloader ADJ, with two semirigid plastic shells for the thigh and the calf and a polyaxial medial hinge set that linked them at 4° of valgus. An adjustable tension strap crossed the lateral aspect of the knee from below, posterolaterally to above, and anteromedially, from the calf to the thigh shells. The subjects were instructed to walk on a treadmill that housed two independent force plates, which were positioned on the left and the right of the treadmill bed. Four walking tests were performed, one immediately before and one immediately after the initial fitting of the brace, and the other two were performed consecutively, and within minutes of each other, with and without the brace, after 3 months. Each test lasted for 1 minute, during which time 20 and 60 steps were recorded.
In addition, 30 patients were assessed clinically using VAS pain scores for resting, standing, walking, and climbing stairs. A modified Hospital for Special Surgery (HSS) knee score was also recorded. From the results compiled, Draper et al.79 concluded that patients with unicompartmental OA of the knee were helped by the use of the valgus Unloader ADJ. The objective outcome measurements made in this study showed that the improvement of function began as soon as the brace was worn. Although the study proved that the valgus OA brace was effective, it did not shed any light on the mechanism.
The final evidence-based article that investigated the Unloader ADJ was that of Richards et al.24 Within this study, the kinematic and kinetic effects of a valgus brace, Őssur’s Unloaded ADJ brace, were compared with a simple off-the-shelf hinged brace in a crossover design study for a period of 6 months. The findings from this study indicated a significant reduction in pain while resting, walking, and stair climbing with the Unloader ADJ brace. These results supported the belief that the increased load did not cause the pain in the knee but instead was reduced by support from the brace. Unfortunately, the valgus brace had a functional drawback by causing a significant reduction of flexion during the swing phase, which resulted in reduced foot clearance and a shorter stride. The simple hinged brace did not have such a restriction. Possible causes of these restrictions were the valgus brace being too large and, with only a single hinge, being prone to torsional misalignment.24
OAsys was initially manufactured by Innovation Sports but, in 2006, was bought by Őssur. This brace has a unique Aculign adjustable unloading system that combined with the traditional dual-hinge brace supports, helps to relieve OA symptoms, and supports ligamentous instabilities often associated with the OA knee.
Brouwer et al.80 conducted a study with 117 patients who either were fitted with an OAsys knee brace or were in a control group that was not treated with any type of orthosis but instead continued with standard treatment. The patients were assessed using both the VAS scale and the HSS OA form. As compared with the control group, pain severities on the VAS scale were less in the orthosis group at each of the three assessment points as well as overall during the 12-month follow-up. At 12 months, the difference was borderline significant, but in both instances, significant pain reduction versus the control group was not found.80
In the study performed by Dennis et al.,69 the OAsys knee brace rated fourth of six braces for maximum separation value of the medial condyles at heelstrike, fifth at midstance, and tied for last with the ACL brace for toe-off. On the whole, there was a noticeable variability in performance among the five OA braces tested. The OAsys offloading brace had less optimal results.
The Unloader Express is a cost-effective, easy-to-fit unloader option for the less active person. The brace uses the proven “3-Point Leverage System” that combines an “Adjustable Dynamic Joint with a Dynamic Force Strap” to unload the affected compartment, reducing pain.
Sattari and Ashraf33 conducted a study to compare the effect of lateral wedges and a 3-point knee support in treatment of medial compartment knee OA. The 3-point knee support used was the Unloader Express. The study was a randomized controlled trial held in three outpatient departments of physical medicine and rehabilitation. Its participants consisted of 60 patients, 20 patients in a group, and each complained of knee pain and had genu varum based on radiographic evidence. The 60 patients were divided into three groups. The first group received conservative treatment along with an Unloader Express brace, which was fitted for each patient by an orthotist. The second group received conservative treatment along with quarter-inch lateral wedge insoles. The third group was the control group and received only conservative management that was similar to the other two groups.33
The results of Sattari and Ashraf’s study suggested that both lateral wedge insoles and the 3-point knee brace had a significant effect on pain reduction, with the knee brace having a more profound effect. The Unloader Express seemed to have a significant effect in widening of the medial compartment space especially in patients with severe degenerative joint disease of the medial compartment. On the basis of the findings of the study, the authors believed that the 3-point knee brace was superior in the management of patients with moderate to severe medial compartment DJD and could even halt or reverse the process of compartment narrowing.33
The Unloader One is manufactured by Őssur and is the most investigated of all offloading OA knee braces currently on the market. As a result of 20 years of clinical studies and user feedback, Őssur completely redesigned the legendary Unloader One brace, incorporating new technologies. The present Unloader One knee brace has 30% to 50% more unloading power than the original Unloader, with only half the weight. In addition, the new Unloader One has two “Dynamic Force Straps” (DFSs) that work in conjunction with an easy-to-adjust control system to allow the patient to manage his/her knee pain. The new brace also has color-coded quick-fit buckles with leverage arms that enable easy application and removal without the need for cumbersome strap adjustments, which are ideal for the elderly population.
Birmingham et al.81 fitted 14 males and 6 females with the Unloader One valgus brace to evaluate the effects of a valgus brace on measures of knee proprioception and lateral control. Upon the study’s conclusion, the authors suggested that although braces such as the Unloader One provide subtle knee proprioceptive cues, the contribution is only minor compared with somatosensory information already available during weightbearing tasks. In addition, postural control involves the integration of visual and vestibular systems along with somatosensory input, and small changes in knee proprioception may have little effect on the control of standing balance.81 Therefore, the results suggest that the control of single-limb standing balance characterized by additional sensory input is not improved, and the mechanisms underlying the use of a valgus brace probably involve minor neuromuscular effects working in combination with more substantial mechanical effects.81
Hillstrom et al.,83 Horlick and Loomer,82 and Pollo and Jackson84 have shown in their quantitative investigations that symptomatic relief can be provided by the Unloader One OA brace. Pollo et al.84 also found a significant reduction in the mean medial compartment load for the normal mode of use condition compared with the unbraced condition. Increasing the brace valgus angulation from 4° to 8° also had a significant effect on reducing the medial compartment load. House85 also evaluated the effectiveness of valgus bracing for medial compartment knee OA using the Unloader One in patients with medial knee joint OA. To do this, the author used the Lysholm Knee Rating Scale as a functional outcome measure for support of orthotic treatment of knee OA. Upon completion of his investigation, he reported that although seven of nine subjects reported improvement in pain and functional ability after treatment, there was no significant difference in functional knee scale scores obtained after orthotic treatment compared with those reported before orthotic management.
Ingvarsson et al.86 performed a study similar to those of Hillstrom et al.,83 Horlick and Loomer,62 and Pollo and Jackson84 and found that a valgus knee brace did decrease pain and improve function, as shown by significant improvement in the WOMAC score for pain, stiffness, and function. They also concluded that a valgus brace is a treatment alternative in moderate and severe unicompartmental knee OA.
The study of Kirkley et al.3 compared the results of a prospective, randomized clinical trial using three types of treatment: medical treatment only, a neoprene sleeve, and the Unloader One valgus brace. Their results indicated that patients who had OA of the medial compartment benefited significantly from the use of the Unloader One brace in addition to standard medical treatment. In addition, the group with the Unloader One braces had, on average, significantly better outcome scores than that with neoprene sleeves.3
Matsumo et al.87 used a modified knee scoring system developed by the Japanese Orthopaedic Association to evaluate 20 participants before the application of the Unloader One and each month thereafter for 1 year. The modified knee scoring scale used in the study considered pain during walking and stair climbing. Nineteen of the 20 patients, or 95%, reported decreased pain during activities. All scores significantly improved with the application of the Unloader One knee brace and continued to improve throughout the observation period.
Toriyama et al.88 used the Unloader One within their study to determine whether the involved external knee adduction moment would reduce during the stance phase when wearing an unloading knee brace, thus increasing the ipsilateral hip abduction moment together with the adduction angle. In addition, it was hypothesized that 1) the hip abduction angle in the contralateral lower limb would increase at the initial stance phase of the contralateral limb and the contralateral hip abduction moment would increase and 2) the flexion angle and extension moment of the involved knee would also increase during the stance phase because of the brace structure. The results of the study of Toriyama et al.88 1) suggested that patients who wore the Unloader One knee brace showed a higher-walking speed and cadence than those without bracing; 2) suggested that those patients had adverse effects on other joints by wearing unloading knee braces for medial knee OA and that treatment in these patients should consider these effects; 3) supported Lindenfeld et al.54 and Gaasbeek et al.67 that the external knee adduction moment reduced with the use of an unloading brace; 4) demonstrated that there was a positive correlation between external knee adduction moment and the mechanical axis of the lower limb; 5) showed no significant change in the involved knee angle pattern during stance phase, whereas the ipsilateral hip abduction angle was reduced; 6) showed induced compensation of trunk leaning; and 7) suggested that although bracing reduced stress in the medial compartment of the involved knee, it might lead to low back pain or hip joint OA in the future because of weakening hip abductors from the lack of demand on the associated abductor muscle.
The Unloader Select uses Őssur’s 3-Point Leverage System that combines an “Adjustable Dynamic Joint with a diagonal Dynamic Force Strap.” As a result, this system is the most widely used OA knee brace in world. The Unloader Select is unique in its design because it can fit those with disproportionate thigh-to-calf girth, abnormal limb contour, thin skin, minimal muscle mass, and/or mild cognitive deficiency.
Ramsey et al.89 used 16 participants with medial compartment OA referred by a local orthopedic practice for participation in this study. Baseline measurements were taken, and each participant was fitted with an Unloader Select unloading orthosis with an initial setting of 0° of correction. The participants were instructed to wear the Unloader Select knee brace for 2 weeks, and measurements would be taken again. The orthosis was removed for 2 weeks and then reapplied with 4° of valgus added. There were no significant results noted between the two bracing conditions in relation to pain and the participant’s ADLs. The only change noted was the symptoms in the patient’s knee, with OA being worse in 4° of valgus than the initial setting of 0°. The authors attributed this change in the muscle action at the knee, which was also measured in this study. They concluded that although the use of an orthosis was a cost-effective way to relieve pain, the OA unloading orthosis should not be used in all cases.89
The Generation II Spirit was manufactured by Generation II until it was bought by Őssur, and the name of the OA knee brace was changed to the Unloader Spirit. The Unloader Spirit has a single-upright “Adjustable Dynamic Joint” on the same side as the affected arthritic compartment and a DFS that applies a counteracting force to the adduction moment, as well as thigh and tibial shells that control soft tissue.
Within both studies conducted by Dennis et al.69 and Nadaud et al.,70 the Unloader Spirit achieved minimal or no separation for those subjects wearing the unloading brace and proved effective only in offloading the knee at heelstrike and least effective at midstance.
GENU ARTHRO (MODEL 28K20/21)
The Genu Arthro Brace is made by Ottobock, and its design is based on the classic 3-point principle, the “longer the lever arm, the smaller the force required to achieve load reduction and significant pain relief at the knee.” The Genu Arthro Brace is unique in that it uses long lever arms to ensure an ideal distribution of force and a gentle buildup of pressure, which results in a reduction of the valgus and/or the varus moment, which lessens the rubbing of bone on bone with the knee joint.
The aim of Kutzner et al.34 was to investigate the ability of valgus braces to reduce the medial compartment load by taking measurements directly in the knee joint. The Genu Arthro and the MOS Genu were used for their monocentric joints and because one had a unilateral brace (Genu Arthro) and the MOS Genu had a bilateral frame. Initially, the braces were adjusted to the leg in a neutral position to examine whether the brace itself had influence on the joint loading. After performing activities with the brace in neutral, an additional valgus angle of 4° was adjusted in the MOS Genu as well as 8° in the MOS Genu and Genu Arthro braces.34
The results of the study performed by Kutzner et al.34 confirmed previous findings by Hsu et al.,17 Johnson et al.,18 Morrison,19 Shelburne et al.,20 and Zhao et al.99 that the total axial force is predominantly transferred through the medial compartment during the stance phase of gait by 59% to 91% during walking and 50% to 72% when going up and down stairs. In addition, the walking speed increased or decreased by 5% at maximum for those patients with braces.17–20,34,90
The Genu Arthro brace was also the same brace used in the study by Pagani et al.20 in which a reduction of the external peak adduction moment of approximately 19% in the 8° valgus setting was reported compared with walking without the brace. This moment reduction was approximately two to three times higher than the reduction of medial forces measured directly in the knee joint, which meant that a one-to-one conclusion could not be made from external moment reductions on internal compartment force reductions.
The study by Schmaltz et al.35 fitted 16 patients diagnosed with medial knee OA with an off-the-shelf Genu Arthro knee brace with its unilateral sidebar design. Subjective evaluations of the knee brace with the exception of wearing comfort at the thigh were very favorable ranging between good and very good. It was also found that the mean walking speed significantly increased when wearing the brace and the step length of the arthritic limb increased. The results of this study did not show significant influence on the external varus moment created by the knee braces, which supported the conclusion that the effect of the brace was insufficient to significantly reduce this moment and that the main effect of an unloader brace, such as the Genu Arthro, is compensation for a portion of the external load. The consequences of this effect resulted in decreased internal moments created by muscles and ligaments with decreased forces on the medial portion of the knee joint.35
BIONICARE KNEE SYSTEM
The BioniCare Knee System consists of an “unloading” brace, a patented electrical joint stimulator, a night wrap brace, and electrodes. The unloading knee brace, recommended to be worn in conjunction with the electrical joint stimulator for everyday use, could be either the OActive or the Eagle OA knee brace, which are sold separately. The Night Wrap is used for sleeping and is included with the cost of the electrical joint stimulator and a 3-month supply of electrodes.91
The OActive knee brace may be purchased off the shelf, whereas the Eagle OA knee brace is custom made. The electrical joint stimulator consists of a battery-powered signal generator that uses a 9-V battery as a power source. The electrical stimulator received Federal Food and Drug Administration clearance in 2003 “as an adjunctive therapy for reducing the level of pain and symptoms associated with osteoarthritis of the knee for overall improvement of the knee as assessed by the physician’s global evaluation.” The impulse generated by the electrical joint stimulator is a monophasic negative spike delivered at 100 Hz (100 times per second). It weighs 4.8 oz with battery and 3.2 oz without its battery.91
One electrode is positioned over the knee and the other rests on the thigh to deliver a pulsed signal carried via wires from the signal generator. The OA or Eagle OA knee brace covers the electrodes and provides 3 points of leverage to reduce pressure within the affected knee. In order for the patient to receive the greatest relief of pain and symptoms, the BioniCare Knee Device must be used 6–10 hours a day and can be worn during the day or at night. Because wearing the device can limit some daytime activities, it is recommended that the BioniCare Knee Device be worn at night with the BioniCare Night Wrap while sleeping for maximum comfort.91
The length of time required to notice relief from pain in the affected knee varies from person to person. Clinical studies have indicated that relief can be experienced as early as the first month, but typically, it takes to 4–6 months to see improvement.92
The BioniCare Knee Device has four contraindications. These contraindications are the following: 1) the Bionicare Knee Device cannot be used with any contact element (electrode) placement that applies current to the carotid sinus located in the neck region, 2) the BioniCare Knee Device cannot be used on patients who have a demand type of cardiac pacemaker, 3) the BioniCare Knee Device cannot be used for any contact element (electrode) placement that causes current to flow transcerebrally or through the head, and 4) the BioniCare Knee Device cannot be used whenever pain syndromes are undiagnosed until the etiology is established. In addition to the contraindications listed above, the BioniCare Knee Device cannot be used during pregnancy or birth.91
Many clinical studies have been performed involving 1200 patients in 88 clinical settings. Farr et al.92 performed a study that encompassed a large-scale 2-year open-label, phase IV study with 58 centers and 288 patients who demonstrated dramatic improvement in pain within their knees after using the BioniCare Knee Device for at least 750 hours or more. This study found a significant dose-response relationship between efficacy and hours of use with the BioniCare Knee Device. According to Farr et al.,92 no other OA treatment has shown a positive dose response.
Farr et al.92 also examined the use of a PES device in the treatment of knee OA in patients who had failed nonoperative therapy. The study included 288 participants (95 men and 193 women) who used the PES device from 16 to more than 600 days. The mean was 889 hours. The results indicated that a dose-response relationship existed between effect size and hours of use that had a cumulative time of more than 750 hours. The conclusion of the study was that less than 250 hours of therapy provided relief of pain in the OA knee, but improvement increased in a dose-response manner after 750 hours of cumulative use.92
Another study performed by Fary et al.93 used a double-blind, randomized, placebo-controlled, repeated-measures trial with 70 participants with OA of the knee. Thirty-four participants were randomly provided with PES, and 36 participants were given a placebo. In 26 weeks, a change in pain score was noted and measured on a 100-mm VAS. The WOMAC was also used. The results of this study found that mild to moderate and moderate to severe radiographic OA of the knee with 26 weeks of PES were no more effective than the placebo.
Mont et al.94 performed a fourth study, directed at learning more about the benefits of the BioniCare Knee System. This study took 4 years and was led by two orthopedic surgeons from Johns Hopkins University. One hundred thirteen patients with severe OA were recruited who had been recommended for a total knee arthroplasty by one or more orthopedic surgeons. At the end of 4 years, 63% of the BioniCare patients treated avoided a total knee replacement, whereas 7% of the patients in the control group did not have a total knee replacement.
A final study was performed by Zizic et al.95 to evaluate the safety and the effectiveness of PES for the treatment of knee OA. Seventy-eight patients were enrolled in the study and had OA of the knee with pain and decreased knee function. Six variables were used to assess the effectiveness of the PES. These included duration of morning stiffness, range of motion, knee tenderness, joint swelling, joint circumference, and walking time. Measurements were recorded during the 4-week treatment period. Patients treated with the active PES showed significantly greater improvement than the placebo group in all the six variables. The improvements in clinical measures for pain and function suggest that PES may be effective for treating OA of the knee.95
Approximately one in four Americans has arthritis, the leading cause of disability in middle-aged and older people, which most frequently occurs in individuals who are obese or inactive.1 In addition, a recent study by Huelle et al.96 demonstrated that visible chondral or osteochondral defects were evident in 61% or 1000 consecutive knee arthroscopies. This also means that the prevalence and the incidence of symptomatic OA of the knee are increasing rapidly as the mean age of the population of the United States increases.97,98 Not only is it the most common cause of long-term disability in the population older than 65 years, it is also a leading cause of long-term disability in the population younger than 65 years.
More than one-third of people 45 years or older now report joint symptoms varying from mild discomfort to permanent loss of motion and constant deep pain. Although primary idiopathic OA is still the most common form of OA, the prevalence of secondary OA resulting from knee trauma also seems to be rising at an alarming rate. In a 2011 monograph, Buckwalter et al.13 pointed out the effects of symptomatic OA that affect not only the quality of life of a person but also the cost to health care and economic productivity, making it imperative that nonsurgical treatments be developed. A clear implication of this is early prophylactic measures that need to be implemented after knee injury to either prevent or retard the progression of OA.
One approach that has shown great promise for symptomatic relief and mitigating the development of degenerative changes is the use of “offloading” braces.12,19,55,78,82,87,88,97 Barnes et al.14 reported that most patients had significantly less pain and significantly improved function associated with an offloading OA brace. Furthermore, although all the patients in their investigation were considered to be surgical candidates at the time of recruitment for their study, 76% of the patients who were given an offloading brace reported significant relief of symptoms and only 24% had a knee arthroplasty, with a mean interval of 1.6 years between the onset of symptoms and the time the surgical procedure was performed. Others have also demonstrated similar clinical benefits in the use of these braces in additional investigations.12,58,79
The design characteristics of all commercially produced offloading braces is a valgus or a varus directed force applied at the joint line to reduce compressive and shearing loads in the affected compartment of the knee and, in turn, provide relief of pain. If excessive compressive and shearing loads are responsible for pain in symptomatic OA, then the clinical data clearly suggest that these braces do reduce these loads. Katsaragawa et al.98 demonstrated improvements in bone mineral density associated with the use of offloading braces in symptomatic patients and correlated this improvement with reduction of force in the affected component. Otis et al.65 and Pollo et al.66 also demonstrated that this type of brace reduced compressive loading in the affected compartment of the knee during dynamic weightbearing activities.
According to the CDC, 6% of adults older than 30 years currently show evidence of OA in the knee.1 By the year 2020, the CDC estimates that more than 60 million Americans will be affected by symptomatic OA of the knee.97 The CDC also estimates that, at this same time, OA will supersede heart disease as the single biggest expense to the health care system. The disturbing factor is that the mean age of these symptomatic patients is declining. Considering the potential economic impact of these numbers, a preemptive approach to treating this disease process seems not only reasonable but also prudent.
Table 1 lists 42 OA knee braces available on the market, and yet, only 15 have quantitative evidence to support their efficacy as an alternative option to surgery. In order for physicians to choose preemptive bracing over a total knee arthroplasy (TKA), our profession must make a greater effort at performing solid evidence-based studies that support their effectiveness in 1) reducing health care cost, 2) relieving pain, 3) improving motion, and 4) retarding the progression of degenerative changes within the knee joint over the long-term while restoring the functional capabilities of the patient.
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Keywords:© 2014 by the American Academy of Orthotists and Prosthetists.
osteoarthritis knee braces; unloading knee braces; offloading knee braces; unilateral compartment knee osteoarthritis; medial compartmental knee osteoarthritis; lateral compartmental knee osteoarthritis