ACL Bracing Clinical Evidence Brochure

Clinically-proven ACL protection & Injury prevention

CLINICAL RESEARCH ACL Functional Knee Bracing

ACL Protection & Injury Prevention

ACL INJURY: FACTS & FIGURES

Incidence

Risk of ACL injury to contralateral knee is 2 TIMES that of the reconstructed knee.

• Over two million ACL injuries occur worldwide annually. 1 • 50% of ACL injuries occur in 15-25 year olds 2 • 60-80% of ACL injuries are non-contact related 3 • Women are 2-10x more likely to injure ACL 4

Re-injury

• The re-injury rate for the ACL reconstructed knee is 5%-10% 5 • Risk of ACL injury to the contralateral knee is double that of the reconstructed knee 5 • Only 1/3 of reconstructed athletes attempt to play competitive sports at their pre-injury level within one year following reconstruction 6 • 1 in 5 active reconstructive athletes develop new injuries 6 • Fear of re-injury prevented competitive college and high school football players from returning to play 7

Biology of graft healing

Final ACL graft strength is 67% of a normal ACL

100 %

Collagen mature

Avascular necrosis

Remodeling & Proliferation

Revascularization

50 %

Disorganization of collagen

Use of a brace until 24 weeks post-op is recommended

2 4 6 8 101214 1618 2022 24 262830 32 3436

capillarization begins

revascularization completed

Weeks Postoperative

Fig. 1: Revascularisation of an ACL graft

• Immediately following ACL surgery the graft is at its strongest, graft strength quickly declines due to avascular necrosis. • Graft healing research indicates that the graft is most vulnerable to injury around 6 to 8 weeks postop. Between the third and the 20th week after operation the revascularisation process takes place. Proliferation and remodelling of collagen only occurs as from 12 weeks post-operative. • Protection of the ACL graft with a brace is recommended until 24 weeks post-op to ensure maximum healing. 8,9,10,11,12,13

ACL GRAFT PROTECTION DURING HEALING

PROTECT the ACL graft and avoid reinjury

DonJoy’s 4-Point-of- Leverage brace will decrease ACL strain BY AT LEAST 50%.

WEAR a DONJOY 4-point-of-leverage brace

• Decreases ACL strain by 50% for anteriorly directed loads during weight bearing and non-weight bearing activities 14,15,16,17 • Improves proprioception and neuromuscular control 18,19 and increases patient confidence after ACL reconstruction 20 • Improves bilateral gait symmetry 21

THE EVIDENCE In-vivo ACL strain study - with and without brace

STANDING AT ° FLEX & UNBRACED

STANDING AT ° FLEX & BRACED

* Decreases ACL Strain by 50% for anteriorly directed loads during weightbearing and non-weightbearing

SEATED AT ° FLEX & UNBRACED

SEATED AT ° FLEX & BRACED

ANTERIOR LOAD APPLIED TO TIBIA (N)

Fig. 2: This graphic shows the mean ACL strain values produced by anterior shear loads applied to the tibia of the unbraced and braced knee with the subjects in standing (weightbearing) and seated (nonweightbearing) positions. In both loading situations, the subject’s knee was flexed at 30°. ACL strain was measured through transducers implanted into the ACL. Calculation of ACL strain was referenced to the slack-taut transition point of the ligament.

The DonJoy 4-point-of-leverage technology effectively reduces ACL strain which could be particularly important during rehabilitation while the graft is remodeling 14,15,16,17

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The DonJoy Brace Design

4-POINT-OF-LEVERAGE ™ How the DonJoy 4-Point Brace Protects the ACL Deficient Knee

ROTATION COMPONENT**

ANTEROLATERAL INSTABILITY

• Patients with an ACL deficient knee have an anterolateral instability. • A brace can help to stabilize the knee and prevent further injury but controlling rotation instability in a direct way is very difficult. • By avoiding an anterior tibial translation*, the subsequent rotation component (**) can be reduced or potentially completely avoided. • The DonJoy® biomechanical 4-point design is clinically proven to be the most effective way to prevent anterior translation of the tibia and will provide a high level of stability for the ACL deficient knee.

ANT.

ACL RUPTURE

ACL

PCL

MED.

LAT.

ANTERIOR COMPONENT*

POST.

The DONJOY 4-point-brace = the best brace to control rotation instability by limiting anterior tibia translation

The 4-Point-of-Leverage ™ Design Explained

Point of Leverage #1 The rigid calf cuff is secured at the bottom of the calf providing the distal anchor point to the leverage system. Point of Leverage #2 The rigid thigh cuff is secured at the top of the anterior thigh providing the proximal anchor point to the leverage system. Point of Leverage #3 The strap across the back of the lower thigh pushes the femur anteriorly. Point of Leverage #4 The strap placed on the anterior tibia applies an active constant load to prevent anterior tibial translation.

Loads the tibia

• The ground reaction forces (GRF) acting during functional activities play an important role in ACL loading. • The horizontal component of the GRF imposes an anterior translation on the tibia which causes strain to the ACL. • The DONJOY 4-Point braces with OPPOSING rigid cuffs are designed to reduce the ACL strain. • An anteriorly directed force on the femur (3) and a posteriorly directed force on the tibia (4), both close to the knee, are biomechanically the best system to control the anterior tibial translation. • In order to make these two dynamic forces work, two additional static anchor points are needed (1) (2). • The combination of these two dynamic “strap” forces and two static “rigid cuff” forces produce the ‘4-Point-of-Leverage system’. • The 4-Point-of-Leverage system requires a correct configuration of the straps and a brace design with opposing cuffs.

FOURCEPOINT ™ HINGE How the FourcePoint ™ Hinge keeps the knee out of the “at risk” position Aggressive eccentric contractions of the quadriceps produce significant anterior tibial translation and can injure the ACL or permanently stretch out an ACL graft 22 . Quadriceps-intensive activities should be avoided at joint angles where strains are at a maximum, particularly the last 30 degrees of extension. DJO has developed a hinge to address maximising ACL and ACL graft protection in these “at risk” positions. Small knee flexion angles at initial contact during landing tasks may contribute to ACL injuries. The FourcePoint Hinge can be used to control joint range-of-motion by increasing the knee flexion angle during landing, resulting in a decrease of anterior shear force on the ACL by 9-13% 23 .

Flexion

Extension

The DonJoy FourcePoint™ utilises a leaf spring mechanism in the hinge to apply gradually increasing resistance during knee extension. The resistance engages in the last 25 degrees of extension (relative to the extension stop). The hinge has three levels of resistance with the option to turn off resistance if appropriate.

The DonJoy Fourcepoint ™ utilises a leaf spring system in the hinge

The resistance serves three critical roles: • First, it reduces the time spent near full extension or in the “at risk” position. • Second, it gradually adds posterior load to the tibia complementing the 4-Point-of-Leverage in preventing anterior tibial translation. • Third, it eliminates the extension shock felt when a patient extends into a 10 degree standard rigid stop.

FourcePoint Hinge Technology works to enhance DonJoy’s 4-Point-of-Leverage design by damping knee joint extension, which improves the mechanical performance of the brace and reduces shear forces at the knee.

The FourcePoint hinge combined with the 4-Point-of-Leverage cuff and strapping design provides a more comfortable brace that reduces anterior shear forces at the knee, providing protection to the healing graft in ACL reconstructed patients, stability to an unstable knee in ACL deficient persons, and prophylaxis during sports activities.

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Fourcepoint ™ Hinge Research

ACL (GRAFT) PROTECTION Reducing the risk of ACL reinjury to the reconstructed knee

FourcePoint hinge decreases posterior ground reaction forces 24,25,26

FourcePoint hinge increases knee flexion angles 23,24,25,26

FOURCEPOINT STUDY : KNEE FLEXION ANGLE AT LANDING

The patellar tendon-tibial shaft (PTTS) angle is the angle between the patellar tendon and the longitudinal axis of the tibia and is a linear function of knee flexion. 27

PGRF generates a knee flexion moment that must be resisted by a knee extension moment generated by the quadriceps muscles through the patellar tendon. 24

No Brace With Brace

Male

Female

Increasing the knee flexion angle decreases the PTTS angle. Decreasing PTTS angle decreases the quadriceps and patellar tendon forces. 24,27

Decreasing the PGRF decreases the required internal knee extension moment, thus decreasing the quadriceps and patellar tendon forces. 24

Wearing a fourcepoint brace significantly increased knee flexion angle at landing in a stop-jump task with an average of 5.1° in males and 5.3° in females.

* Significant: p = 0.001

Reducing the anterior shear forces applied on the tibia by the quadriceps & patellar tendon decreases ACL (graft) loading

FourcePoint hinge protects patients after ACL reconstruction from excessive ACL loading and reduces the reinjury risk

Using a brace with FourcePoint ™ hinge technology in conjunction with a 4-Point-of-Leverage ™ frame design:

• Significantly increases knee flexion angle by up to 9° at landing in a stop-jump task in healthy subjects 23,25,26 and at initial foot contact during walking, jogging and stair descent in ACL reconstructed patients 24 , when compared to standard braced and non-braced condition. • Significantly reduces the anterior shear force applied on the tibia during landing in a stop-jump task, by an average of 9% for females and 13% for males. 23 • Significantly decreases peak posterior ground reaction force (PPGRF) during walking, stop jump task landing and side-cutting activities 24,25,26 • Does not impede performance 23,25

ACL INJURY PREVENTION Training effect of the FourcePoint hinge

Improved lower leg biomechanics are retained for 4 weeks, suggesting a positive transfer in protective movement patterns

The evidence: Controlled laboratory study on 24 athletes 26

No Brace

With Brace

Group A

Wk 1

Wk 2

Wk 3

Wk 4

Wk 5

Wk 6

Wk 7

Wk 8

Pre-training test without wearing brace

Post-training test 1 without wearing brace

Post-training test 2 without wearing brace

Randomisation

Wk 1

Wk 2

Wk 3

Wk 4

Wk 5

Wk 6

Wk 7

Wk 8

Group B

With Brace

No Brace

Fig. 1 : Study design. Group A trained without brace from week 1 to week 4, and with brace from week 5 to week 8. Group B trained with brace from week 1 to week 4, and without brace from week 5 to week 8. Braces were worn for a minimum of two hours per week on both legs. Tests were performed without braces.

• Training with a FourcePoint brace significantly improves motion patterns during ACL challenging tasks. Figure 2 shows increased knee flexion angles during landing after 4 weeks of training with a FourcePoint brace. • About 50% of the training effects were retained 4 weeks after the end of the training using the brace (figure 2, group B), suggesting a positive transfer in the skill learning related to increased knee flexion. • The authors suggest 4-week FourcePoint brace training should reduce the risk for noncontact ACL injuries at least during the 4 weeks immediately after the training.

50°

Group A

Group B

40°

†

30°

†

20°

10°

0°

Stop Jump

Side Cutting

Stop Jump

Side Cutting

Fig. 2: Knee flexion angles at peak posterior ground reaction force during stop-jump and side-cutting tasks, measured pre-training (baseline), after 4 weeks of training (post-training test 1) and after 8 weeks of training (post-training test 2). † About 50% of the training effect is retained

Baseline Post Wk 4 Post Wk 8

* Significant: p = 0.001

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Supporting Studies

1. Renström PA. Eight clinical conundrums relating to anterior cruciate ligament (ACL) injury in sport: recent evidence and a personal reflection. Br J Sports Med. 2013;47(6):367-72. 2. Griffin LY, Albohm MJ, Arendt, EA, et al. Understanding and Preventing Noncontact Anterior Cruciate Ligament Injuries: A Review of the Hunt Valley II Meeting, January 2005. Am J Sports Med 2006;34(9):1512-32. 3. Arendt EA, Agel J, Dick R. Anterior cruciate ligament injury patterns among collegiate men and women. J Athl Train 1999;34(2):86-92. 4. Silvers HJ, Mandelbaum BR. Prevention of anterior cruciate ligament injury in the female athlete. Br J Sports Med. 2007; 41(Suppl I):i52-i59. 5. Wright RW, Magnussen RA, Dunn WR, Spindler KP. Ipsilateral Graft and Contralateral ACL Rupture at Five Years or More Following ACL Reconstruction. J Bone Joint Surg, Am. 2011;93:1159-1165. 6. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to pre-injury level of competitive sports after anterior cruciate ligament reconstruction surgery: Two-thirds of patients have not returned by 12months after surgery. Am J Sports Med 2011; 39(3):538-5438. 7. Spindler KP et al. Return to high school and college level football following ACL reconstruction. 2012ACL Study Group Meeting. Jackson Hole, WY. 8. Blickenstaff KR, Grana WA, Egle D. Analysis of a semitendinous autograft in a rabbit model. Am J Sports Med. 1997;25(4):554-559. 9. Butler DL, Good ES, Noyes FR, Olmstead ML, et al. Mechanical properties of primate vascularized patellar tendon grafts; changes over time. J Orthop Res.1989;7:68-79. 10. Clancy WG, Narechania RG, Rosenberg TD, Gmeiner JG, Wisnefske DD, Lange TA. Anterior and posterior anterior cruciate ligament reconstruction in rhesus monkeys. J Bone Joint Surg. 1981;63A(8):1270-1284. 11. Curtis RJ, Delee JC, Drez DJ. Reconstruction of the anterior cruciate ligament with freeze dried fascia lata allografts in dogs: A preliminary report. Am J Sports Med.1985;13(6);408-414. 12. McFarland EG, Morrey BF, An KN, Wood MB. The relationship of vascularity and water content to tensile strength in a patellar tendon replacement of the anterior cruciate in dogs. Am J Sports Med. 1986; 14(6): 436-448. 13. Noyes FR, Butler DL, Grood ES, Zernicke RF, Hefzy MS. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg. 1984; 66A(3):344-352. 14. Beynnon BD, Pope MH, Wertheimer CM, Johnson RJ, Fleming BC, Nichols CE, Howe JG. The effect of functional knee-braces on strain on the anterior cruciate ligament in vivo.J Bone Joint Surg Am 1992;74(9):1298-312. 15. Beynnon BD, Fleming BC, Peura G, Johnson RJ, Renstrom PA, Nichols CE, Pope MH. An In-Vivo Investigation of Anterior Cruciate Ligament Strain: The Effect of Functional Knee Bracing and Attachment Strap Tension. 1995. 41st Annual Orthopedics Research Society Meeting. 16. Beynnon BD, Johnson RJ, Fleming BC, Peura GD, Renstrom PA, Nichols CE, Pope MH. The Effect of Functional Knee Bracing on the Anterior Cruciate Ligament in the Weightbearing and Nonweightbearing knee. Am J Sports Med 1997;25(3):353-9. 17. Fleming BC, Renstrom PA, Beynnon BD, Engstrom B, Peura G. The influence of functional knee bracing on the anterior cruciate ligament strain biomechanics in weightbearing and nonweightbearing knees. Am J Sports Med 2000;28(6):815-24. 18. Théoret D, Lamontagne M. Study on three-dimensional kinematics and electromyography of ACL deficient knee participants wearing a functional knee brace during running. Knee Surg Sports Traumatol Arthrosc 2006;14(6):555-63. 19. Wu GK, Ng GY, Mak AF. Effects of knee bracing on the sensorimotor function of subjects with anterior cruciate ligament reconstruction. Am J Sports Med 2001;29(5):641-5. 20. Németh G, Lamontagne M, Tho KS, Eriksson E.Electromyographic activity in expert downhill skiers using functional knee braces after anterior cruciate ligament injuries. Am J Sports Med 1997;25(5):635-41. 21. Lu TW, Lin HC, Hsu HC. Influence of functional bracing on the kinetics of anterior cruciate ligament-injured knees during level walking. Clin Biomech (Bristol, Avon). 2006Jun;21(5):517-24. 22. DeMorat G, Weinhold P, Blackburn T, Chudik S, Garrett W. Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury. Am J Sports Med 2004;32(2):477-83. 23. Yu B, Herman D, Preston J, Lu W, Kirkendall DT, Garrett WE. Immediate effects of a knee brace with a constraint to knee extension on knee kinematics and ground reaction forces in a stop-jump task. Am J Sports Med 2004;32(5):1136-43. 24. Stanley CJ, Creighton RA, Gross MT, Garrett WE, Yu B. Effects of a Knee Extension Constraint Brace on Lower Extremity Movements after ACL Reconstruction. Clin Orthop Relat Res 2011;469(6):1774-80. 25. Lin CF, Liu H, Garrett WE, Yu B. Effects of a knee extension constraint brace on selected lower extremity motion patterns during a stop-jump task. J Appl Biomech 2008;24(2):158-65. 26. Liu H, Wu W, Yao W, Spang JT, Creighton RA, Garrett WE, Yu B. Effects of Knee Extension Constraint Training on Knee Flexion Angle and Peak Impact Ground-Reaction Force. Am J Sports Med. 2014 Feb 14. [Epub ahead of print] 27. Nunley RM, Wright DW, Renner JB, Yu B, Garrett WE. Gender Comparison of Patella-Tendon Tibial Shift Angle with Weight-Bearing. Res Sports Med 2003;11(3):173-185.

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