The effect of functional knee-braces on strain on the anterior cruciate ligament in vivo.

Functional knee-braces are widely used to protect injured or reconstructed anterior cruciate ligaments, despite the fact that few scientific data support their efficacy. We studied seven functional braces, representative of both the typical custom-fit and off-the-shelf designs. The braces were tested on subjects who had a normal anterior cruciate ligament and were scheduled for arthroscopic meniscectomy or exploration of the knee under local anesthesia. After the operative procedure, a Hall-effect strain-transducer was applied to the anterior cruciate ligament. Under low anterior shear loads, two braces provided some protective strain-shielding effect compared with no brace, but this strain-shielding effect did not occur at the higher anterior shear loads expected during the high-stress activities common to athletic events. The DonJoy, Townsend, C.Ti., and Lenox Hill braces demonstrated a strain-shielding effect on the anterior cruciate ligament with an internal torque of five newton-meters applied to the tibia. None of the braces had any effect on strain on the anterior cruciate ligament during active range of motion of the knee from 10 to 120 degrees or during isometric contraction of the quadriceps. Wearing of a brace did not produce an increase in the value for strain on the anterior cruciate ligament. For the activities that were evaluated in this study, none of the braces produced adverse effects on the anterior cruciate ligament, and there were no significant differences in the strain on the anterior cruciate ligament between the use of a custom-fit or an off-the-shelf brace design. There were no apparent advantages of the more expensive custom-made braces compared with the off-the-shelf designs.     

Three-month efficacy of three knee braces in the treatment of medial knee osteoarthritis in a randomized crossover trial

Immediate biomechanical and functional effects of knee braces are often reported, however, the duration and type of knee brace treatment for knee osteoarthritis (KOA) remain unclear. The objective was to evaluate usage, comfort, pain, and knee adduction moment (KAM) of three knee braces each worn 3 months by patients. Twenty-four patients with KOA were assigned in a randomized crossover trial a valgus three-point bending system brace (V3P-brace), an unloader brace with valgus and external rotation functions (VER-brace) and a stabilizing brace used after ligament injuries (ACL-brace). Functional questionnaires and gait assessment were carried out before and after each brace wear period of 3 months. A Friedman test was applied between brace wear diary recordings. Repeated measures analyses of variance contrasted the factors brace type (ACL, V3P, and VER), time (pre and post) and wear (without and with) on comfort, pain, function, and KAM. Brace usage was similar, but the V3P-brace was slightly less worn. Discomfort was significantly lowered with the VER-brace. All knee braces relieved pain and symptoms from 10% to 40%. KAM angular impulse was reduced with the three braces, but the VER-brace obtained the lowest relative reduction of 9%. The interaction between time and wear indicated that part of the KAM reduction with brace wear was maintained post treatment. All three knee braces have great benefits for pain and function among the medial KOA population. The VER-brace offers additional advantages on daily use, comfort and KAM, which could improve compliance to brace treatment.     

Knee Bracing

The authors present an overview of the design and functional features of knee braces and their relationship to knee biomechanics. Four types of knee braces-prophylactic, rehabilitative, functional, and patellofemoral-have been developed to cover the wide variety of indications in patients who have suffered knee injuries or hope to prevent them. Important considerations when choosing specific brace types are discussed, and summaries of relevant research are presented. Clinical criteria for brace selection are offered to help physicians and sports medicine professionals in choosing the right brace for each patient.     

A viscoelastic knee brace for anterior cruciate ligament deficient patients

A biomechanical review of the anterior cruciate ligament deficient knee shows that the unbraced knee undergoes instability once its angular velocity exceeds normal cadence rate. It also shows that various braces that utilize extension limits for purposes of preventing subluxation and tibial rotation introduce abnormal gait and posture responses, which may impose on the patient's activities. A speed-regulated, viscoelastic knee brace has been designed, fabricated, and tested on two patients. The brace allows full range of knee motion and reduces the angular velocity of the tibia from near-full extension to neutral at normal, non-unstabilizing walking speeds. Capability is incorporated for adjusting the terminal angular velocity for each individual patient as well as for the same patient during the recovery period.     

Knee braces

The preceding discussion has profiled the three different types of knee braces which are available on today's market. It also has attempted to discuss the controversies surrounding these braces and to analyze the scientific data presented to date. Prophylactic braces have been shown to be ineffective in preventing knee injuries in its present day design. Evidence also has shown that their use may even lead to increased knee injuries. Rehabilitative braces, on the other hand, do serve a useful purpose in regard to the operative and non-operative treatment of ligamentous knee injuries. With their ease of application and control of joint motion, they are an important addition to the surgeon's armamentarium. One must keep in mind, however, that these braces provide little static anterior/posterior control and the hinge settings may not actually affect true joint motion. Functional knee braces may play a role in the treatment of patients with pathological laxity due to an injury of the anterior cruciate ligament. Combined with an adequate rehabilitation program and activity modification, these braces do limit excessive anterior tibial translation under low loading conditions. However, under conditions of high loading these braces provide little or no resistance to anterior translation. Therefore, in most sporting activities, their efficacy is questionable. Knee bracing continues to be a complex and controversial topic in the field of orthopedic surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

"Custom-fit" versus "off-the-shelf" ACL functional braces

Many sports medicine practitioners believe "custom-fit" functional braces are superior in performance to "off-the-shelf" braces for anterior cruciate ligament (ACL)-deficient knees. However, this is not well substantiated. This study compares a Donjoy custom-fit ACL brace (CE 2000), Donjoy off-the-shelf brace (Goldpoint), and an athletic taping technique to determine their role in our clinical practice. Five patients (3 men and 2 women) with isolated, unilateral, chronic ACL tears with an average age of 27 years (range: 19-35 years) were used to evaluate these three restraint systems. Anterior tibial laxity, quadriceps and hamstrings strength, endurance, standing long jump, brace migration with exercise, and pattern of muscle response to forced anterior tibial displacement were studied. Each patient was tested without a brace and then in each of the three test conditions (custom brace, off-the-shelf brace, and tape), with the order of testing randomized. The Donjoy custom-fit ACL functional brace did not reduce anterior laxity or improve standing long jump, muscle strength, endurance, or muscle response times significantly more than the off-the-shelf ACL brace. Both braces improved anterior stability over knee taping when the knee muscles were contracted under the low forces used in this study. After 1 hour of exercise, brace migration was significantly greater (P=.03) for the CE-2000 custom brace (18.6 mm) than for the Goldpoint off-the-shelf brace (4.5 mm). There appears to be no advantage to the more expensive custom-fit knee brace over the off-the-shelf brace.     

Prophylactic knee braces and injury to the lower extremity

Five hundred and eighty high-school football players were studied over a period of two seasons to determine the effect of so-called prophylactic knee braces on the lower extremity. Two hundred and forty-seven athletes who wore single-hinged braces and eighty-three who wore double-hinged braces were paired for the same season of play with 250 athletes who were similar in height, weight, and playing position but who did not wear braces. The fifty-three injuries of the knee that occurred were significantly more frequent (p less than 0.001) in the group that wore single-hinged braces than in the matched, non-braced group. While there were more injuries of the knee in the participants who were double-hinged braces than in the matched controls, who did not wear braces, the increase in the number of injuries was not significant. There was also a dramatic increase (p less than 0.01) in the number of injuries of the ankle and foot in the athletes who wore braces. Our results question the efficacy of the braces that were studied and call attention to the potentially adverse effect of the braces on adjacent joints in the ipsilateral limb.     

Biomechanics of the tibiofemoral joint and knee braces

We investigated whether the kinematics of modern knee braces reflect the natural movement of the knee, especially with regard to the roll-glide ratio. Seven commercially available modern knee braces were analyzed in a new measuring unit with a 6-D positional registration system, which had been developed for this study. The results were compared to the theoretically postulated joint movements.All knee braces produced a roll-glide ratio different from the natural movement of the knee. Only the Townsend brace protected the anterior cruciate ligament at the beginning of the movement.Biomechanically, none of the knee braces tested provided efficient protection for the knee movement. We propose a new functional external joint, which allows restoration of the natural roll-glide mechanism of the articulating surfaces.     

The effectiveness of self-adjustable custom and off-the-shelf bracing in the treatment of varus gonarthrosis

BACKGROUND: A recent development in valgus-producing knee braces has been the adjustable "unloader" brace. The purpose of this study was to compare the effectiveness of off-the-shelf and custom-made patient-adjustable, valgus-producing knee unloader braces in relieving pain, reducing stiffness, and improving function and in reducing varus angulation and the peak adduction moments about the knee during gait and stair-stepping in patients with painful varus gonarthrosis of the knee. METHODS: Ten adult patients served as their own controls for the measurement of baseline values and then wore each of the two braces, one after the other, for four to five weeks in a random order. Pain, stiffness, and function were assessed with the Western Ontario and McMaster Universities Osteoarthritis Index. Gait and stair-stepping were evaluated with a three-dimensional motion analysis system and multicomponent force platform. Full-length (hip, knee, and ankle) standing anteroposterior radiographs were used to determine alignment of the knee. RESULTS: Both braces significantly reduced pain and stiffness (p<0.05), with the custom brace reducing stiffness significantly more than the off-the-shelf brace (p=0.030). The custom brace significantly improved function (p=0.010) and reduced the peak knee adduction moments during gait (p=0.033) and stair-stepping (p=0.002) compared with baseline values and compared with the off-the-shelf brace (p=0.029 and p=0.027, respectively). The custom brace significantly reduced varus angulation of the knee by 1.5 degrees compared with baseline (p=0.001) and by 1.3 degrees compared with the off-the-shelf brace (p=0.009). The off-the-shelf brace did not significantly reduce the varus angle. CONCLUSIONS: We investigated only the short-term effects of custom and off-the-shelf patient-adjustable valgus-producing knee "unloader" braces and found that patients with varus gonarthrosis of the knee may benefit significantly with respect to pain relief and reduced stiffness from use of either brace. However, such patients may experience additional significant benefit in improved function and reduced stiffness, varus angulation, and medial compartment loading of the knee from use of the custom-made patient-adjustable brace.     

Diagnosis and treatment of the cruciate ligament injury of knee joint

During 1959 to 1986, 62 Cases with cruciate ligament injury of the knee joint were treated in our hospital. Thirty of these cases were anterior cruciate ligament injuries and 32 cases were posterior The diagnosis of the cruciate ligament injuries was made by stability tests of the cruciate ligament. When the knee was greatly swollen with multiple ligament injuries, a series of X-ray films should be taken to test the knee stability under local or nerve block anesthesia. Fresh tear of the cruciate ligament (33 cases) was treated with immediate surgical repair except in one. Old ligament injuries (28 cases) were treated by conservative method (10 cases) or surgical reconstruction (18 cases). All patients were followed for 2 to 18 years (mean 6 years). The results showed that the fresh tear of the cruciate ligament treated surgically had excellent and good rates in 87.9% (29/33). In the conservative treatment group, only 27.3% (3/11) obtained good result, and most of them were complicated with meniscal lesions and osteoarthritis. Eighteen cases treated by ligament reconstruction gave 34.5% (8/18) good result.     

How to treat knee ligament injuries?

Indications for conservative treatment of knee ligament injuries can be established for all grade I or II sprains (partial tears), as well as isolated grade III sprains (complete tears) of the posterior cruciate ligament (PCL) and medial collateral ligament (MCL). These injuries should be treated with immediate mobilization. Only in isolated partial anterior cruciate ligament (ACL) tears without a positive pivot shift phenomenon is conservative treatment justified. However, many of these injuries may require operative reconstruction later. In complete ACL tears the surgical treatment consists of primary reconstruction or augmented primary repair. Today, the middle third of the patella tendon with the bone blocks is regarded as the "gold standard" for augmented repairs and late reconstructions. For the present, there is no place for synthetic prostheses in the treatment of an acute ACL rupture. Allograft replacement of the ACL must now be considered an experimental procedure. In the reconstruction of the PCL the above mentioned patella tendon graft is also preferable. Lateral collateral ligament (LCL) tears, especially if they are combined with ruptures of posterolateral ligament complex, should be repaired immediately after the injury. In these injuries late reconstructions are difficult and the results are poor. Conservative treatment of partial tears and postoperative treatment of reconstructed ligaments is twofold: on the one hand, the healing tissue should be protected and on the other hand, atrophy and wasting of uninjured tissue should be avoided. Overload and stretching of the injured ligaments should be eliminated with the aid of a suitable knee brace, but early range of motion exercises of the knee are allowed immediately.(ABSTRACT TRUNCATED AT 250 WORDS)     

"Wandering resident" surgical exposure for 1- or 2-stage revision arthroplasty in stiff aseptic and septic knee arthroplasty

A retrospective study was performed on 18 patients who had undergone revision total knee arthroplasty (TKA) between 1992 and 2000 with stiff knee (average, 50 degrees range of motion). The so-called "wandering resident" surgical exposure was used. This procedure was used twice in 5 cases with low-grade infection in a 2-stage revision of their septic prosthesis. Follow-up was from 1 to 8 years (average, 3.5 years). All patients had good clinical results, with an 86 degrees average range of motion. The Knee Society Score preoperatively ranged from 35 to 52 (average, 40) and improved to 72 to 89 (average, 84). Postoperative rehabilitation was slower, requiring the use of a knee brace in extension for 6 weeks for support while the patient ambulated and without this support for daily physiotherapy and continuous passive motion at 0 degrees to 70 degrees. Full range of motion with no brace was started after 6 weeks.     

Bracing the anterior cruciate ligament deficient knee using the Lenox Hill derotation brace

The Lenox Hill derotation brace fashioned by Castiglia and his staff at the Lenox Hill Hospital Brace Shop (New York, New York) under the direction of Nicholas during the 1960s has been worn successfully by thousands of patients with unstable knees, including elderly arthritic patients, adolescents with congenital instability, and professional athletes. Nearly 9000 braces were worn by patients in the United States during the period from 1976 to 1980. The brace, with its sliding axis of motion, corresponds to the axis of movement in the knee. The combination Lenox Hill brace includes not only the sliding axis of motion, but also a second below-knee leg pad, second derotation strap, and hyper-extension stop. It is designed to resist the combination anteromedial-rotatory, anterolateral-rotatory, and anteromediolateral-rotatory instabilities. More than 70% of the braces prescribed during the last five years have been the combination type. The derotation brace is a significant advance in brace designs for supporting chronic unstable and surgically reconstructed knees. It can function effectively even when the wearer is actively participating in sports.     

Adjustable bracing technique for the prevention of knee flexion contracture during tibial lengthening

The authors present a simple thigh-knee brace that prevents flexion contracture during tibial lengthening. The brace is strapped to the thigh and connected to the Ilizarov frame via two simple hinges. While in the brace the knee can be mobilized for physiotherapy and locked in extension during rest.     

Nonoperative management of isolated grade III collateral ligament injury in high school football players

In a prospective study, 24 high school football players with isolated Grade III injuries of the medial collateral ligament (MCL) of the knee were treated by conservative management. This included an active rehabilitation program, progressing from immobilization and controlled motion in an orthotic rehabilitation knee brace, to muscle strengthening and agility exercise. A stable knee was achieved in 22 cases; the average recovery time was 29 days. The athletes returned to competitive sports at a mean time of 34 days. These results confirm previous reports of successful nonoperative management of isolated Grade III MCL injuries.     

Isolated avulsion fracture of the tibial attachment of the posterior cruciate ligament

Summary Avulsion injuries of the posterior cruciate ligament of the knee are relatively infrequent. Most authors recommend primary operative repair, but there have been only a few series with documented results.Twenty-three patients with an isolated avulsion type injury of the PCL were operated on in our department during the last 15 years.The diagnosis was made by clinical examination and imaging studies (X-ray, MRI). The aim of this retrospective study was to determine the difficulty or ease of the posterior open exposure for the general surgeon as well as to reaffirm the value of surgical repair and rigid fixation of the avulsed PCL     

Using real‐time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion

Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight‐bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real‐time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain‐free controls, 23 patellofemoral pain) were acquired during weight‐bearing knee extension. Pain subjects were also imaged while wearing a patellar‐stabilizing brace and a patellar sleeve. We measured axial‐plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0°and 50° (p = 0.03), and increased lateral tilt for knee flexion angles between 0° and 20° (p = 0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p = 0.006). The brace reduced patellar tilt near full extension (p = 0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight‐bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects. Published by Wiley Periodicals, Inc. J Orthop Res 27: 571–577, 2009     

Custom-fit versus premanufactured braces

Custom-made and off-the-shelf functional knee orthoses from four manufacturers were evaluated. Anterior tibial translation testing was performed using a pneumatic mechanical surrogated knee. The mechanical surrogate was interfaced with a servohydraulic materials testing system, which applied all anterior/posterior displacements to an ultimate anterior load of 400 N. Comparison of the individual custom versus premanufactured braces showed that the custom braces demonstrated a statistically significant difference for restraining anterior displacement (P=.0001 to P=.0005). Pooled data from all tests showed that the custom brace measurements as a group restrained anterior displacement better than the premanufactured brace group by a mean difference of 0.84 mm (P=.0001). The authors question whether such small, sub-millimeter findings between custom and off-the-shelf functional derotation braces represent any clinically significant differences.     

Evaluation of the use of braces to prevent injury to the knee in collegiate football players

Data were collected in 1984 from seventy-one schools that were members of Division I of the National College Athletic Association and in 1985 from sixty-one of these schools to assess whether the use of so-called preventive braces for the knee was associated with a decrease in either the severity or the incidence (or both) of injuries to the knee in collegiate football players. Over-all, players who wore braces on the knees had significantly more injuries to the knee than players who did not. The severity of the injuries was no different in the two groups. Based on these findings, we cannot recommend the use of these braces in an attempt to prevent injury to collegiate football players.     

Primary reconstruction of injuries of the capsular ligament of the knee joint

Whether operative or conservative treatment is indicated for acute knee ligament injuries depends on the lesions of the cruciate ligaments: complex instability with rupture of one or both cruciate ligaments and injuries to the lateral or medial ligamentous structures should be treated by operation. Surgical treatment of an isolated rupture of the anterior cruciate ligament is recommended only for the young active patient. Surgery is performed by way of a single anterolateral incision with standard medial and if necessary, lateral arthrotomies. Ruptures of the cruciate ligaments are reconstructed with absorbable sutures, which are passed through bone channels. Augmentation with an absorbable allograft is used in most reconstructions of the cruciate ligaments. A knee brace with limited range of motion is used for postoperative rehabilitation. Our long-term results after operative reconstruction of acute instabilities of the knee joint show that ligamentous stability was achieved in most cases, but the functional results were impaired by pain and limited range of motion.