bracing for acl injuries

Evidence behind bracing after acl injury


Knee braces are commonly prescribed for many reasons after anterior cruciate ligament (ACL) reconstruction or injury. Documented use of knee braces to treat ligament injury and instability goes back to as early as the 1960s, most notably the use of the Lenox Hill brace by American football quarterback Joe Namath following multiple knee surgeries, which was developed by Castiglia and Nicholas [18]. The results of the existing literature on functional brace use are mixed. 

Ruptures of the anterior cruciate ligament (ACL) are the most common ligament injury in the knee.  Approximately 200,000 ACL injuries occur each year in the United States and most of these are non-contact injuries.  Females show a higher injury rate than males and all of these have been established in the literature [1]. The highest injury rates are seen in sports which include stop-and-go actions, jumps, rotations and fast changes of velocity or direction such as football, handball, basketball, volleyball, skiing and tennis [1].

Residual instability, neuromuscular deficits, and altered lower extremity biomechanics following ACL injury and reconstruction can result in overcompensation and altered biomechanics in the contralateral leg and an increased risk of secondary injury in both the injured and contralateral knees [14].  Anatomic reconstructions have attempted to restore stability to the intact state with improved tunnel placement, but elongation of the ACL graft during the healing process remains unrestrained [14]. Additionally, graft failure rates following anatomic reconstruction have been reported to be as high as 13 % [15].

Braces as a simple and cost-effective aid are often used in order to immobilize the knee joint, to prevent excessive joint movements and to improve stability during activity and thus to prevent secondary injuries. There are several different brace concepts. Traditional knee braces are designed as rigid shells with a hinge joint and straps to mechanically guide and support the knee joint during motion.  These are many times called functional braces.

Image 1: Previous concepts and methods of ACL taping  Adopted from [26].

Functional brace use has been reported for many reasons.  First, they are used for postoperative stabilization to theoretically allow normal tibiofemoral kinematics while preventing excessive strain and elongation of the healing ACL graft.  Second, they are used for non-operative treatment for chronic ACL deficiency to prevent subsequent injury and reduce functional deficits.  Third, for ACL injuries in skeletally immature individuals to prevent subsequent injury until maturity is reached and reconstruction can be performed without damaging the epiphyseal growth plates.  Lastly, they have been reported to be used for pre-operative stabilization of the knee joint to prevent subsequent meniscal and chondral injuries until surgery can be performed [14].

According to a survey of the American Orthopaedic Society for Sports Medicine (AOSSM), only 13 % of surgeons never prescribe functional brace use to their ACL reconstruction patients and only 3 % never brace their ACL-deficient patients [16]. A separate survey of the AOSSM reported 63 % of surgeons prescribe functional brace use for their ACL reconstruction patients, 71 % of which prescribe brace use for up to 1 year [17].  As a result, numerous functional braces have been developed to treat ACL deficiency and to improve patient outcomes following ACL reconstructions [14].  With an average cost of $592 USD, functional bracing of ACL injuries is placing a significant financial burden on the healthcare system. 

Previous studies investigating the mechanical effects of rigid braces showed conflicting results. On the one hand, a reduction of anteroposterior laxity in the knee was observed for low-load conditions [2,3]. On the other hand, no positive effects of braces on knee stability could be found in more complex conditions or in sports with higher loads [3,4].  Multiple clinical studies have reported that long-term patient outcomes following ACL reconstruction are not measurably improved through the use of a functional brace [19-20].   However, decreased subsequent injury rates in professional skiers while skiing have been reported [21-22].

Figure 3.  Types of functional braces.  Adopted from [14].

One hundred volunteers from US service academies were randomized between braced and unbraced groups following ACL reconstruction with BPTB grafts and evaluated on prone heel height differences, side to side differences in anterior tibial translation (ATT), Lachman’s test scores, pivot shift examination scores, Lysholm scores, single leg hop test, IKDC scores, range of motion, and isokinetic strength after a minimum of 2 years postoperatively [20]. Braced patients were prescribed an off-the-shelf functional knee brace to be worn daily for 6 months and for all rigorous activities for at least 1 year. At 2-year follow-up, no significant differences were observed between the braced and unbraced groups [20].

Functional knee bracing with a functional brace seems to impact the gait pattern and confidence [5]. The subjective perception of comfort differed among patients: while some patients reported discomfort using rigid braces [6,7], other patients reported benefits such as a higher sense of stability or increased performance.  Cook et al. reported the effect of functional bracing during running and cutting in ACL-deficient subjects. Bracing improved running and cutting performance, but did not prevent abnormal anterior tibial translation (ATT). Subjects reported fewer incidents of subluxation while wearing the brace during testing [23].

Knee Sleeve

Knee Brace

Hinged Knee Brace

Patella Brace

Patella Strap Brace

Knee Ice Pack

Kinesiology Tape

Due to the conflicting results regarding the effectiveness of rigid braces, alternative brace concepts have also been explored.  Bandages were previously shown to improve sensorimotor control by increasing the proprioception of the muscles surrounding the knee [2,8,9].  The disadvantage of bandages seems to be an insufficient mechanical stabilization compared to rigid braces [10].  Therefore, an alternative to both bandages and rigid braces are soft braces.

Previous studies comparing rigid and soft braces for the treatment of ACL-deficient subjects show conflicting results. Strutzenberger et al. found a higher rate of force development in counter-movement jumps and a reduced sway path length during single leg stance on an unstable, laterally perturbed platform with a soft compared to a rigid brace [11]. Beynnon et al. compared two rigid braces and one soft brace and found a significant reduction in anteroposterior laxity during tests with the Vermont Knee Laxity Device for all three braces. However, positive effects were only found during weight-bearing and non-weight-bearing postures and not for the load acceptance phase [3].  Another study compared a rigid brace, a soft brace and a bandage and found no significant differences in jump distance, peak torque and power between the three conditions during functional (cross-over hop and single leg vertical jump) and isokinetic tests [13].

Previously mentioned studies quantified brace effects mostly using the performance in functional or strength tests and did not provide joint kinematics of the lower extremities. Kinematic data is needed to understand the mode of action of different brace concepts, how they affect gait patterns and to evaluate whether one brace concept provides better knee stabilization effects.

A 2020 study attempted to provide kinematic data and compare soft and rigid braces.  This study showed that both braces induced changes in knee joint kinematics during walking and cutting when compared to an unbraced control condition [1].   It was shown that during walking tasks with frontal disturbance bracing may decrease peak abduction and external rotation in the knee joint, meaning braces could provide additional stability when patients return to sports after ACL ruptures. Secondly, it revealed that both rigid and soft braces had similar effects on joint angles in the frontal and transverse planes. The rigid brace showed a stronger reduction of the external rotation compared to the soft brace in the walking condition [1]. 

Whether ultrasound can be used as a primary screening tool is currently under debate [18]. It has been suggested that ultrasound only provides additional value under special circumstances, like the pre-hospital environment, disaster areas, developing countries, suspicion of occult fracture in poorly ossified bones, pregnant patients and to reduce exposure to serial direct radiographs in fracture reduction [19]. An important feature in this debate is the actual diagnostic accuracy of ultrasound for detecting forearm fractures.  The systematic review concluded that using ultrasound for the diagnosis of distal forearm fractures in children using the 6-view method is a reliable method that equals conventional x-ray in diagnostic accuracy with a sensitivity of 97% and specificity of 95%.  [17]. 

Image 3: Soft brace withiout metal hinges  Adopted from [27].

There have been more attempts recently to change the functional braces made thus far and to try other methods to improve outcomes.  The ideal functional brace to treat ACL injuries should replicate the constraint of the native ACL on the knee joint [14]. Specifically, the brace should apply a posterior-directed force to the anterior proximal tibia that varies with flexion angle. 

A significant body of literature has shown that accelerated rehabilitation—defined as early-unrestricted motion, immediate weight-bearing and eliminating the use of immobilizing braces—is appropriate after ACL reconstruction with patellar tendon grafts.  Another recent study showed this was also effective for hamstring tendon grafts also [24,25].

Biomechanical literature demonstrates that functional bracing does not strain shield the ACL or reduce ATT in response to anterior forces and internal torques greater than 140 N and 8 Nm, or during functional activities. Clinical literature demonstrates that use of a functional brace postoperatively following ACL reconstruction does not affect long-term patient outcomes [14].  Patient compliance with prescribed functional brace use has been limited by brace discomfort, slippage, fit, and inhibition of athletic performance.

Figure 10.  Recent reviews of bracing after ACLR.  Adopted from [28].


In conclusion, no existing functional ACL brace has been successfully validated in the literature to restore normal anterior stability to the ACL-deficient knee and improve long term patient outcomes following reconstruction.   Attempts are being made to eliminate the use of braces for many patients or to change the current methods of bracing.

– More about ACL injuries on Wiki Sports Medicine



  1. Focke, Anne, et al. “Effect of different knee braces in ACL-deficient patients.” Frontiers in bioengineering and biotechnology 8 (2020): 964.
  2. Wojtys, E. M., Kothari, S. U., and Huston, L. J. (1996). Anterior cruciate ligament functional brace use in sports. Am. J. Sports Med. 24, 539–546. doi: 10.1177/036354659602400421
  3. Beynnon, B. D., Fleming, B. C., Churchill, D. L., and Brown, D. (2003). The effect of anterior cruciate ligament deficiency and functional bracing on translation of the tibia relative to the femur during nonweightbearing and weightbearing. Am. J. Sports Med. 31, 99–105. doi: 10.1177/03635465030310012801
  4. Ramsey, D. K., Lamontagne, M., Wretenberg, P. F., Valentin, A., Engström, B., and Németh, G. (2001). Assessment of functional knee bracing: an in vivo three-dimensional kinematic analysis of the anterior cruciate deficient knee. Clin. Biomech. 16, 61–70. doi: 10.1016/s0268-0033(00)00065-6
  5. DeVita, P., Lassiter, T., Hortobagyi, T., and Torry, M. (1998). Functional knee brace effects during walking in patients with anterior cruciate ligament reconstruction. Am. J. Sports Med. 26, 778–784. doi: 10.1177/03635465980260060701
  6. Risberg, M. A., Holm, I., Steen, H., Eriksson, J., and Ekeland, A. (1999). The effect of knee bracing after anterior cruciate ligament reconstruction. A prospective, randomized study with two years’ follow-up. Am. J. Sports Med. 27, 76–83.
  7. Singer, J. C., and Lamontagne, M. (2008). The effect of functional knee brace design and hinge misalignment on lower limb joint mechanics. Clin. Biomech. 23, 52–59. doi: 10.1016/j.clinbiomech.2007.08.013
  8. Baltaci, G., Aktas, G., Camci, E., Oksuz, S., Yildiz, S., and Kalaycioglu, T. (2011). The effect of prophylactic knee bracing on performance: balance, proprioception, coordination, and muscular power. Knee Surg. Sports Traumatol. Arthrosc. 19, 1722–1728. doi: 10.1007/s00167-011-1491-3
  9. Bodendorfer, B. M., Arnold, N. R., Shu, H. T., Leary, E. V., Cook, J. L., Gray, A. D., et al. (2019). Do neoprene sleeves and prophylactic knee braces affect neuromuscular control and cutting agility? Phys. Ther. Sport 39, 23–31. doi: 10.1016/j.ptsp.2019.05.007
  10. Luber, M., Binder, E., and Schaff, P. (1998). Stabilisierungseigenschaften von hartrahmenorthesen und bandagen mit gelenkschienen gegen vordere schublade – erste ergebnisse. Orthopädie Technik 5, 350–354.
  11. Strutzenberger, G., Braig, M., Sell, S., Boes, K., and Schwameder, H. (2012). Effect of brace design on patients with ACL-ruptures. Int. J. Sports Med. 33, 934–939. doi: 10.1055/s-0032-1304634
  12. Mortaza, N., Abu Osman, N. A., Jamshidi, A. A., and Razjouyan, J. (2013). Influence of functional knee bracing on the isokinetic and functional tests of anterior cruciate ligament deficient patients. PLoS One 8:e64308. doi: 10.1371/journal.pone.0064308
  13. Mortaza, N., Abu Osman, N. A., Jamshidi, A. A., and Razjouyan, J. (2013). Influence of functional knee bracing on the isokinetic and functional tests of anterior cruciate ligament deficient patients. PLoS One 8:e64308. doi: 10.1371/journal.pone.0064308
  14. Smith, Sean D., et al. “Functional bracing of ACL injuries: current state and future directions.” Knee Surgery, Sports Traumatology, Arthroscopy 22 (2014): 1131-1141.
  15. van Eck CF, Schkrohowsky JG, Working ZM, Irrgang JJ, Fu FH (2012) Prospective analysis of failure rate and predictors of failure after anatomic anterior cruciate ligament reconstruction with allograft. Am J Sports Med 40(4):800–807
  16. Decoster LC, Vailas JC (2003) Functional anterior cruciate ligament bracing: a survey of current brace prescription patterns. Orthopedics 26(7):701–706
  17. Delay BS, Smolinski RJ, Wind WM, Bowman DS (2001) Current practices and opinions in ACL reconstruction and rehabilitation: results of a survey of the American Orthopaedic Society for Sports Medicine. Am J Knee Surg 14(2):85–92
  18. Nicholas JA (1983) Bracing the anterior cruciate ligament deficient knee using the Lenox Hill derotation brace. Clin Orthop Relat Res 172:137–142.
  19. Birmingham TB, Bryant DM, Giffin JR, Litchfield RB, Kramer JF, Donner A, Fowler PJ (2008) A randomized controlled trial comparing the effectiveness of functional knee brace and neoprene sleeve use after anterior cruciate ligament reconstruction. Am J Sports Med 36(4):648–655
  20. McDevitt ER, Taylor DC, Miller MD, Gerber JP, Ziemke G, Hinkin D, Uhorchak JM, Arciero RA, Pierre PS (2004) Functional bracing after anterior cruciate ligament reconstruction: a prospective, randomized, multicenter study. Am J Sports Med 32(8):1887–1892
  21. Kocher MS, Sterett WI, Briggs KK, Zurakowski D, Steadman JR (2003) Effect of functional bracing on subsequent knee injury in ACL-deficient professional skiers. J Knee Surg 16(2):87–92
  22. Sterett WI, Briggs KK, Farley T, Steadman JR (2006) Effect of functional bracing on knee injury in skiers with anterior cruciate ligament reconstruction: a prospective cohort study. Am J Sports Med 34(10):1581–1585
  23. Cook FF, Tibone JE, Redfern FC (1989) A dynamic analysis of a functional brace for anterior cruciate ligament insufficiency. Am J Sports Med 17(4):519–524
  24. Janssen, Rob PA, et al. “ACL reconstruction with hamstring tendon autograft and accelerated brace-free rehabilitation: a systematic review of clinical outcomes.” BMJ open sport & exercise medicine 4.1 (2018): e000301.
  25. Shelbourne KD, Vanadurongwan B, Gray T. Primary anterior cruciate ligament reconstruction using contralateral patellar tendon autograft. Clin Sports Med 2007;26:549–65.
  26. Wojtys, Edward M., and Laura J. Huston. “” Custom-Fit” Versus” Off-the-Shelf” ACL Functional Braces.” American Journal of Knee Surgery 14.3 (2001): 157-162.
  28. Marois, Bianca, et al. “Can a Knee Brace Prevent ACL Reinjury: A Systematic Review.” International Journal of Environmental Research and Public Health 18.14 (2021): 7611.