The Effect of Functional Knee Bracing on the Anterior Cruciate Ligament in the Weightbearing and Nonweightbearing Knee

Abstract

We investigated the effect of functional bracing on anterior cruciate ligament strain in humans by arthroscopic implantation of a differential variable reluctance transducer on the ligament and measurement of its strain behavior. Strains were measured while "injury mechanism" loads were applied to the weightbearing and nonweightbearing knees for both braced and unbraced conditions. For the unbraced knee, there was a significant increase in ligament strain values when subjects went from a seated position (minimal shear and compressive loads across the knee) to a standing posture (substantial shear and compressive loads across the knee). Similar strain values were found between these same seated and standing postures when a 140-N anterior-directed load was applied to the tibia. This indicates that the ligament is strained during weightbearing and demonstrates that the compressive load across the knee produced during weightbearing does not significantly reduce ligament strain values in comparison with the unweighted joint with relaxed muscles for the 140-N load limit of our anterior shear test. Bracing produced a protective effect on the ligament by significantly reducing the strain values for anterior-directed loading of the tibia up to 140 N with the knee in both weightbearing and nonweightbearing conditions. Likewise, bracing produced a protective effect on the ligament by significantly reducing strain values in response to internal-external torque of the tibia up to 6 N-m with the knee nonweightbearing. The brace strap that contacts the tibia just distal to the insertion of the patellar tendon was instrumented with a load sensor, allowing us to measure the posterior-directed loads applied by the brace to the tibia. Adjustment of strap tension between low and high settings did not modulate the protective effect of the brace on the ligament.

Seismic Performance for Steel Frames with Different Layouts of Knee Brace

“…Modal analysis had conducted on four different layouts of knee brace in steel frame [7][8][9]. The five lowest order on natural vibration period of each scheme (T) was presented in Tab.1,and five lowest order on natural vibration period of each scheme was shown in Tab.…”

The Biomechanics of the Anterior Cruciate Ligament and Its Reconstruction

“…In contrast, Torzilli et al (1994) found anterior translation of the tibia in response to a joint compressive load (up to 444N), as did Oh et al (2011), who found translation coupled with internal rotation with a compressive load of 800N. These findings were corroborated in vivo: Beynnon et al (1997) and Fleming et al (2001) found an increase in ACL strain with the simple change from non-weight-bearing to weight-bearing. Weightbearing may increase ACL loading due to the posteroinferior slope of the proximal tibial surface (Hashemi et al, 2008) inducing an anterior shift on tibiofemoral compression (Fleming et al, 2001;Torzilli et al, 1994).…”

“…Ligament strain (Ahmed et al, 1987;Bach & Hull, 1998;Berns et al, 1992;Beynnon et al, 1992;Beynnon et al, 1997;Fleming et al, 2001;Gabriel et al, 2004;Sakane et al, 1997;Takai et al, 1993;Torzilli et al, 1994) or load Markolf et al, 1995) increases with an anterior force on the tibia. When the ACL is cut anterior translation increases (Diermann et al, 2009;Fukubayashi et al, 1982;Hsieh & Walker, 1976;Markolf et al, 1976;Oh et al, 2011;Reuben et al, 1989;Wroble et al, 1993;Yoo et al, 2005;Zantop et al, 2007), or a given translation is resisted by a lesser force (Butler et al, 1980;Li et al, 1999;Lo et al, 2008;.…”

Suggestions From the Field for Return-to-Sport Rehabilitation Following Anterior Cruciate Ligament Reconstruction: Alpine Skiing

“…6,19,30 Improved mechanical stability, decreased shear stresses, and protection against injury mechanisms have also been shown. 4,8,28 In addition to the protective function a brace can offer, neuromuscular and proprioceptive benefits have been observed in cutting activities, 6 gait, 11 and running. 43 Though early bracing has not demonstrated the long-term benefit commonly associated with a successful outcome, 8,28 protecting the knee against a catastrophic fall is intuitive and the development of position sense and neuromuscular control is a factor that contributes to the overall success of rehabilitation.…”