To protect the anterior cruciate ligament (ACL), even healthy subjects are dependent on muscular stabilization of the knee joint (17-20). The quadriceps, hamstrings, and the gastrocnemius muscles are important knee stabilizers, and a carefully tuned activation pattern of these muscles can provide stability to normal subjects as well as to ACL-deficient patients (20). Several studies have shown that patients after ACL rupture display decreased proprioception (1,4,9), and to some extent this remains even after reconstruction (2,26). It has also been shown that patient satisfaction does not correlate well with knee joint stability following ACL reconstruction but rather with the residual level of proprioception (2,26). This suggests that the ability to provide functional knee joint stability through neuromuscular control is an important factor after ACL reconstruction. A simple elastic bandage was shown to improve joint position sense in patients with osteoarthritis (3,25). An objective assessment of the effects of a bandage on the total integration of afferent and efferent pathways is lacking in the literature.
Proprioception can be defined as the cumulative neural input provided to the CNS by sensory receptors in muscles, tendons, joints, and skin. Recent studies showed that proprioception is also important for the control of limb posture (23) and balance (8) as well as learning of new movements (7), suggesting that not only afferent but also efferent pathways such as muscle coordination must be included into the definition (4). There have been several reports on the afferent aspects of proprioception such as awareness of position and movement (1-3,10,16,25). Until now, only few attempts exist to measure the efferent part of proprioception. Beard et al. (4) measured the latency of reflex hamstrings contraction and found a significant correlation between the hamstrings reflex latency and the functional score of ACL deficient patients. Another study could not confirm their results and concluded that the reflex hamstrings latency was not a reliable test (15). EMG analysis during cutting maneuvers (6) or during anterior tibial translation (28) have also been used to measure the effects of a brace on the muscle coordination and dynamic stabilization of the knee joint. Most tests did not gain wide application. The one-legged stance test on a force-platform evaluating the postural control system and muscle coordination was shown to be a reliable testing procedure (12,13). It further allows the healthy leg to act as a control (12,13,26), making statistical analysis more reliable. This test has successfully been applied to the evaluation of ankle injuries (14), ACL ruptures (26), and ACL reconstruction (26) as well as ankle supports (5,11). The present study used the one-legged stance test to evaluate the enhancement of muscle control and coordination afforded by the use of an elastic compression sleeve after ACL reconstruction. It also included a one-legged drop jump to further stress the balance control system.
Subjects. Thirty-six subjects (24 males and 12 females) who had undergone unilateral ACL reconstructions using a patella tendon graft were studied. In all cases, it was at least 1 yr since the subject's surgery, and many had returned to full physical activity. The physical characteristics of the subjects, together with indices of their functional ability (Lysholm score) are summarized in Table 1. The testing protocol was approved by the hospital's review board and informed consent was obtained from each subject before testing.
Task. They were required to perform a standing drop jump from a 10-cm-high platform onto a force plate (Model 9286, Kistler Instrumente, Winterthur, Switzerland) landing on one leg and thereafter maintain a one-legged balance for 25 s. This task was repeated on the previously injured leg three times without and three times with an elastic compression sleeve. Eighteen subjects performed first the trials without compression sleeve, while the others were tested in a reversed order. The task was repeated if a subject failed to land on one leg.
Measures. Force-plate signals were captured using Kistler's BIOWARE software running on an IBM-PC computer with an analog-to-digital sampling rate of 100 Hz and a sampling time of 25 s following landing. These data were then analyzed using an interactive time series analysis package (TSA, Data Analysis, Perth, Western Australia). For analysis purposes, the task was partitioned into three control phases, namely a landing phase that was delimited to the first 150 ms, and two subsequent periods each of 10-s duration designated the adjusting and balancing phases, respectively. A typical set of data is shown in Figure 1, together with the force measurement convention adopted for reporting purposes (29).
Measures of peak impact loading (maximum Fx, Fy, Fz) were obtained for the landing phase. Force-time integrals (intFx, intFy, intFz), path length (PL), root mean square error of the force components (rmsFx, rmsFy, rmsFz), and center of pressure (rmsAx, rmsAz) were extracted from the force platform data during the adjusting and balancing phase.
Analysis. Criterion measures were statistically analyzed for differences between bandaged and unbandaged performances during landing, adjusting, and balancing. Student t-tests for correlated samples were conducted for the purpose of statistical comparison, but significant differences were interpreted conservatively given the erosion of statistical probability with multiple comparisons, and only highly significant results (P < 0.001) were considered to be of practical importance.
Mean values together with standard deviation for all criterion measures are presented in Table 2.
Several significant benefits from the wearing of an elastic compression sleeve were identified. During the landing phase a 10% increase of peak ground contact forces was seen in both the vertical and anteroposterior direction (Fy and Fx maximums) when the bandage was worn. During the adjusting and balancing phase, all criterion measures in the anteroposterior direction showed a significant reduction with the bandage: 5% for the force measures (rmsFx, intFx) and more than 20% for the center of pressure (rmsAx). There was also a significant reduction in the path length of the center of pressure, indicating an improved steadiness in the patients' one-legged standing.
An important finding of the present study was that all significant effects occurred in the sagittal plane, indicating that the knee joint becomes a substantial factor for one-legged balance control in the anteroposterior direction. Mediolateral control was seen to occur at the ankle joint, a finding that is supported by Goldie (14) who found an impaired postural steadiness in the mediolateral direction after inversion injuries of the ankle joint. The one-legged control strategy stands, therefore, in contrast to the two-legged stance, in which mediolateral instability is controlled at the hip joint and the ankle joint adjusts for postural disturbances in the anteroposterior direction while the knee joint has no effect on the postural control (27). Thus, for pathologies of the knee joint the one legged stance test is recommended.
Most patients after ACL rupture or reconstruction show some loss of proprioception (2,4,9), which is known to produce deficits in interjoint coordination (24). Indeed, Shiraishi et al. (26) found that the one legged stance showed a lack of muscle coordination in ACL deficient patients and in patients after ACL reconstruction. Lorentzon et al (21). found a significantly lower mechanical output in ACL deficient legs, and suggested that the observed decreases in isokinetic performance of the quadriceps muscles can best be explained by nonoptimal activation of normally functioning muscle fibers due to the deficient sensory feedback from the mechanoreceptors of the torn ACL. This loss of proprioception and muscle activation may disturb the dynamic stabilization of the knee joint and endanger a graft after ACL reconstruction. Because it is known that the anterior and posterior cruciate ligaments can actively be protected by coactivation of the hamstrings, quadriceps, and gastrocnemius muscles (22), an improved muscle activity pattern seems to be an adequate safeguard against excessive knee joint movements (20). It has been found that an elastic bandage improved joint position sense in patients with disturbed proprioception (3,25). The present study further revealed that an elastic compression sleeve reduced the sway in the anteroposterior direction during balance by as much as 20%, and the force requirements for the postural adjustments were reduced by 5%, indicating that the integration of afferent and efferent pathways, e.g., interjoint and muscle coordination was significantly refined.
A compression sleeve seems capable of compensating for the loss of proprioception and muscle coordination after ACL rupture or reconstruction by the compression of skin, muscles, and tendons as well as the knee joint capsule. This may enhance the awareness of the different mechanoreceptors and improve muscle coordination and joint stability. The bandage not only improved muscle coordination in single limb support movements of the ACL reconstructed patients but also increased the patients confidence in vertical loadings on the knee joint and tolerance of translational shear forces. The increase in maximal forces in the vertical and anteroposterior direction observed during landing when the subjects were wearing the bandage supports this contention.
1. Barrack, R. L., H. B. Skinner, and S. L. Buckley. Proprioception in the anterior cruciate deficient knee. Am. J. Sports Med.
2. Barrett, D. S. Proprioception and function after anterior cruciate reconstruction. J. Bone Joint Surg.
3. Barrett, D. S., A. G. Cobb, and G. Bentley. Joint proprioception in normal, osteoarthritic and replaced knees. J. Bone Joint Surg.
4. Beard, D. J., P. J. Kyberd, C. M. Fergusson, and C. A. F. Dodd. Proprioception after rupture of the anterior cruciate ligament. An objective indication of the need for surgery? J. Bone Joint Surg.
5. Bennell, K. L., and P. A. Goldie. The differential effects of external ankle support on postural control. J. Orthop. Sports Phys. Ther.
6. Branch, T. P., R. Hunter, and M. Donath. Dynamic EMG analysis of anterior cruciate deficient legs with and without bracing during cutting. Am. J. Sports Med.
7. Cole, J. D., and E. M. Sedgwick. The perceptions of force and of movement in a man without large myelinated sensory afferents below the neck. J. Physiol. (Lond.)
8. Cordo, P., L. Carlton, L. Bevan, M. Carlton, and G. K. Kerr. Proprioceptive coordination of movement sequences: role of velocity and position information. J. Neurophysiol.
9. Corrigan, J. P., W. F. Cashman, and M. P. Brady. Proprioception in the cruciate deficient knee. J. Bone Joint Surg.
10. Friden, T., D. Roberts, and R. Zätterström. Proprioception in the nearly extended knee: measurements of position and movement in healthy individuals and in symptomatic anterior cruciate ligament injured patients. Knee Surg. Sports Traumatol. Arthroscopy
11. Friden, T., R. Zätterström, A. Lindstrand, and U. Moritz. A stabilometric technique for evaluation of lower limb instabilities. Am. J. Sports Med.
12. Goldie, P. A., M. Bach, and O. M. Evans. Force platform measures for evaluating postural control: reliability and validity. Arch. Phys. Med. Rehabil.
13. Goldie, P. A., O. M. Evans, and T. M. Bach. Steadiness in one-legged stance: Development of a reliable force-platform testing procedure. Arch. Phys. Med. Rehabil.
14. Goldie, P. A., O. M. Evans, and T. M. Bach. Postural control following inversion injuries of the ankle. Arch. Phys. Med. Rehabil.
15. Jennings, A. G., and B. B. Seedhom. Proprioception in the knee and reflex hamstring contraction latency. J. Bone Joint Surg.
16. Jerosch, J., M. Prymka, and W. H. Castro. Proprioception of knee joints with a lesion of the medial meniscus. Acta Orthopaed. Belg.
17. Johansson, H., P. Sjölander, and P. Sojka. A sensory role for the cruciate ligaments. Clin. Orthop.
18. Johansson, H., P. Sjölander, and P. Sojka. Receptors in the knee joint ligaments and their role in the biomechanics of the joint. Biomed. Engl.
19. Kuster, M., G. A. Wood, S. Sakurai, and G. Blatter. Downhill walking: a stressful task for the anterior cruciate ligament? Knee Surg. Sports Traumatol. Arthroscopy
20. Kuster, M., S. Sakurai, and G. A. Wood. The anterior cruciate ligament-deficient knee: compensatory mechanisms during downhill walking. The Knee
21. Lorentzon, R., L. G. Elmqvist, M. Sjöström, M. Fagerlund, and A. R. Fuglmeyer. Thigh musculature in relation to chronic anterior cruciate ligament tear: muscle size, morphology, and mechanical output before reconstruction. Am. J. Sports Med.
22. O'Connor, J. J. Can muscle co-contraction protect knee ligaments after injury or repair. J. Bone Joint Surg.
23. Rothwell, J. C., M. M. Traub, and B. L. Day, J. A. Obeso, P. K. Thomas, and C. D. Marsden. Manual motor performance in deafferented man. Brain
24. Sainburg, R. L., H. Poizner, and C. Ghez. Loss of proprioception produces deficits in interjoint coordination. J. Neurophysiol.
25. Sell, S., J. Zacher, and S. Lack. disorders of proprioception of arthrotic knee joint. Z. Rheumatol.
26. Shirashi, M., H. Mizuta, K. Kubota, Y. Otsuka, N. Nagamoto, and K. Takagi. Stabilometric assessment in the anterior cruciate ligament reconstructed knee. Clin. J. Sports Med.
27. Winter, D. A. A.B.C. of Balance during Standing and Walking.
Waterloo, Canada: Waterloo Biomechanics, 1995, pp. 5-24.
28. Wojtys, E. M., S. U. Kothari, and L. J. Huston. Anterior cruciate ligament functional brace use in sports. Am. J. Sports Med.
29. Wu, G., and P. R. Cavanaugh. ISB Proposal. J. Biomech.