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How dynamic-force bracing supports PCL recovery


Inadequate treatment and rehabilitation of posterior cruciate ligament (PCL) injuries can result in functional impairment and disability due to an increase in posterior laxity of the knee, as well as osteoarthritis and arthrosis in the patello-femoral joint (PFJ). Recommended treatment protocols including dynamic force bracing may mitigate these issues.1,2,3

A consensus statement developed at a 2017 medical congress in Reykjavik, Iceland, supports bracing as an integral component of both surgical and nonsurgical treatment of injuries involving the PCL.4 A variety of braces are available, but many were designed for injuries to the anterior cruciate ligament (ACL), which differ from PCL injuries, and until recently, few had undergone rigorous testing.1,5

Össur's Rebound PCL brace uses dynamic force to replicate the biomechanics of the endogenous PCL, and Rebound PCL is recommended as part of surgical and nonsurgical care.4 A study that examined outcomes associated with a static-force brace and Össur's dynamic-force Rebound PCL brace found that the Össur device more closely mirrors the loading profile of the native PCL.1 By improving knee kinematics, a dynamic brace helps normalize medial and PFJ pressures and potentially reduces the incidence of knee arthrosis.1,3

Bracing in Post-Injury Rehabilitation

Multiligament knee injuries are challenging to rehabilitate due to extensive soft tissue damage and variation in injury patterns. Up to 37% of acute, traumatic knee injuries involve PCL tears, and few PCL tears happen in isolation.5 Many PCL injuries are associated with peroneal nerve and vascular injuries as well as posterolateral corner (PLC) injuries.2,3

Posterior tibial translation (PTT) often does not normalize after surgical or nonsurgical treatment of PCL injuries because the ligament or graft heals in an elongated position, resulting in long-term instability and disability.1 Increased PTT while in motion and while supine may contribute to elongation.1

Counteracting PTT in PCL-disrupted knees with anterior-directed force on the proximal tibia has been shown to improve posterior knee laxity.1 Rehabilitation after multiligament reconstruction should include a dynamic PCL brace to protect the graft and restore patellar mobility, as well as knee function, motion and strength.2,5,6

Biomechanics of Bracing

In a knee with an injured PCL or PLC deficiency, the tibia translates posteriorly and externally rotates with the application of a load, leading to lateralization of the patella and high compression between the lateral facet of the patella and lateral trochlea.7,8

Welch et al. found that peak pressures in PCL/PLC-deficient knees are consistently isolated to the lateral facet, particularly at higher degrees of flexion.3 Total force is lowest at 30 degrees of flexion, increases at 60 degrees, and levels off at 60 to 120 degrees. 3

A PCL brace should apply appropriate joint forces and allow that force to vary according to the angle of knee flexion. It should also be adjustable to accommodate a variety of activities.5 The Össur Rebound PCL brace is designed to impart increasing anterior force on the tibia as the degree of knee flexion increases.

Össur's Rebound dynamic PCL brace significantly reduced force, total pressure and peak pressure in the patellofemoral joint in PCL- and PLC-deficient knees, especially at higher degrees of flexion.3 Moreover, the dynamic brace significantly reduced total pressure within the PFJ across all angles tested and significantly reduced peak pressure at all flexion angles.3

Kneeling stress radiographs showed a 15 mm change in posterior tibial translation after surgical reconstruction and rehabilitation with the Rebound PCL, and the rehabilitated knee had 0.6 mm less PTT than the uninjured knee.9

Comparison of Dynamic to Static Brace

In seated unloaded knee flexion, squatting and stair descent, LaPrade et al. demonstrated that a dynamic brace applies force to the posterior proximal tibia, increasing as the flexion angle increases.1 The dynamic brace applies significantly larger forces than a static brace at higher flexion angles, where the PCL endures larger in situ forces.1

Comparison of the posterior tibial load provided by a static PCL brace and the dynamic force of the Rebound PCL brace. Graph adapted from LaPrade et al.1

During unloaded flexion at the lowest setting, the force applied by the dynamic brace increased as a function of flexion angle.1 Force applied by the static brace did not significantly change as a function of flexion angle.1

During stair descent, average force at toe-off was significantly higher with the dynamic brace than the static brace. Similar results were demonstrated for squatting and for the higher force level settings.1

A different brace that claims to be dynamic in nature did not restore posterior sag of the tibia to intact levels after non-operative treatment of a PCL injury.10


A PCL brace should direct correct anatomic joint forces that vary with the flexion angle of the knee, and it should be adjustable to accommodate a variety of activities.5 The Össur Rebound PCL brace meets these requirements and is recommended as part of conservative and surgical treatment.4

The Össur Rebound PCL brace closely replicates the biomechanics of the PCL, improving posterior knee laxity after PCL injury.1 Protecting the PCL from elongation as it heals potentially reduces the risk of osteoarthritis, arthrosis, deficiency and disability.1,2,3

Literature cited

  1. LaPrade, R.F., Smith, S.D., Wilson, K.J., Wijdicks, C.A. 2015. Quantification of functional brace forces for posterior cruciate ligament injuries of the knee joint: an in vivo investigation. Knee Surgery, Sports Traumatology, Arthroscopy. 23:3070-3076.
  2. Moatshe, G., Chahla, J., LaPrade, R.F., Engebretsen, L. 2017. Diagnosis and treatment of multiligament knee injury: state of the art. Journal of ISAKOS. 2:1-10.
  3. Welch, T., Keller, T., Maldonado, R., Metzger, M., Mohr, K., Kvitne, R. 2017. The effect of a dynamic PCL brace on patellofemoral compartment pressures in PCL-and PCL/PLC-deficient knee. Journal of Experimental Orthopaedics. 4:10.
  4. 2017 Medical Congress, Reykjavik, Iceland. Recommended use of Rebound PCL in the rehabilitation of isolated and combined PCL injuries.
  5. Jansson, K.S., Costello, K.E., O'Brien, L., Wijdicks, C.A., and LaPrade, R.F. 2012. A historical perspective of PCL bracing. Knee Surgery, Sports Traumatology, Arthroscopy. 21:1064-1070.
  6. Dean, C.S., Fernandes, O., Cinque, M.E., Chahla, J., LaPrade, R.F. 2017. Paraskiing crash and knee dislocation with multiligament reconstruction and iliotibial band repair. American Journal of Orthopedics. 46:e301-e307.
  7. Gill, T.J., DeFrate, L.E., Wang, C., Carey, C.T., Zayontz, S., Zarins, B., Li, G. 2003a The biomechanical effect of posterior cruciate ligament reconstruction on knee joint function: kinematic response to simulated muscle loads. American Journal of Sports Medicine. 31(4):530-536.
  8. Kwak, S.D., Ahmad, C.S., Gardner, T.R., Grelsamer, R.P., Henry, J.H., Blankevoort, L., Ateshian, G.A., Mow, V.C. 2000. Hamstrings and iliotibial band forces affect knee kinematics and contact pattern. Journal of Orthopaedic Research. 18(1):101-8.
  9. Godin, J.A., Cinque, M.E., Pogorzelski, J., Moatshe, G., Chahla, J., LaPrade, R.F. Multiligament knee injuries in older adolescents: A 2-year minimum follow-up study. Orthopaedic Journal of Sports Medicine. Sept 2017.
  10. Jacobi, M., Reischl, N., Wahl, P., Gautier, E., Jakob, R.P. 2010. Acute isolated injury of the posterior cruciate ligament treated by dynamic anterior drawer brace: a preliminary report. The Bone & Joint Journal. Sept. 2010.