Proprioception after anterior cruciate ligament reconstruction with and without bracing

In this investigation we evaluated the effect of ACL reconstruction and functional knee bracing on knee proprioception. Twenty subjects who experienced acute ACL disruption and underwent reconstruction with a bone-patellar tendon-bone graft participated in a controlled rehabilitation program and were studied at a mean follow-up of 2 years. A control group of ten subjects were also studied. In both groups proprioception was evaluated by measuring the threshold to detection of passive motion (TDPM) with the knee at 15 degrees of flexion with and without a functional knee brace applied. The Knee Osteoarthritis Outcome Score, Cincinnati knee score, and two functional knee tests were also used as outcome measurements. Anterior-posterior displacement of the tibia relative to the femur was evaluated with the KT-1000 arthrometer. There were no significant differences in TDPM between the ACL-reconstructed and contralateral knees, or between the ACL reconstructed group and the healthy control group. Bracing did not produce a significant change in the TDPM for the ACL-reconstructed group or for the control group. There were low to moderate correlations between TDPM and the other outcome measurements. This study indicates that there is no significant differences in proprioception between the ACL-reconstructed knee and the contralateral uninvolved knee 1 year or more after surgery. Functional knee bracing does not seem to improve proprioception in patients who have undergone ACL reconstruction and been followed up on average 2 years after surgery.     

Dynamic stability in the anterior cruciate ligament deficient knee

Some individuals can stabilize their knees following anterior cruciate ligament rupture even during activities involving cutting and pivoting (copers), others have instability with daily activities (non-copers). Movement and muscle activation patterns of 11 copers, ten non-copers and ten uninjured subjects were studied during walking and jogging. Results indicate that distinct gait adaptations appeared primarily in the non-copers. Copers used joint ranges of motion, moments and muscle activation patterns similar to uninjured subjects. Non-copers reduced their knee motion, and external knee flexion moments that correlated well with quadriceps strength. Non-copers also achieved peak hamstring activity later in the weight acceptance phase and used a strategy involving more generalized co-contraction. Both copers and non-copers had high levels of quadriceps femoris muscle activity. The reduced knee moment in the involved limbs of the non-copers did not represent "quadriceps avoidance" but rather represented a strategy of general co-contraction with a greater relative contribution from the hamstring muscles.     

Principles of bracing for the anterior cruciate ligament-deficient knee

The preceding discussion has profiled the three different types of knee braces available on today's market. It has attempted to discuss the controversies surrounding these braces and to analyze the scientific data presented to date. Prophylactic braces have been shown to be ineffective in preventing knee injuries in their present-day design. Evidence has also shown that their use may even lead to increased knee injuries. On the other hand, rehabilitative braces do serve a useful purpose in regard to the operative and nonoperative treatment of ligamentous knee injuries. With their use in the application and control of joint motion, they are an important addition to the surgeon's armamentarium. One must keep in mind, however, that these braces provide little static anterior/posterior control and the hinge settings may not actually reflect true joint motion. Functional knee braces may play a role in the treatment of patients with pathologic laxity owing to an injury of the ACL. Combined with an adequate rehabilitation program and activity modification, these braces do limit excessive anterior tibial translation under low-loading conditions. However, under conditions of high loading these braces provide little or no resistance to anterior translation. Therefore, in most sporting activities, their efficacy is questionable. Knee bracing continues to be a complex and controversial topic in the field of orthopaedic surgery. The answers for the design of the "ideal" brace are being continually worked out and the need for more detailed, well-controlled studies continues to be great.(ABSTRACT TRUNCATED AT 250 WORDS)     

External stabilization of the anterior cruciate ligament deficient knee during rehabilitation

Using cadaveric specimens, we studied the effect of ACL deficiency upon anterior tibial translation during extension of the knee joint. Five knees were loaded via the quadriceps mechanism until flexion angles of 10 degrees, 25 degrees, 40 degrees, and 60 degrees were attained. At each angle, the anterior-posterior position of the tibia was documented with biplane radiography, both before and after division of the ACL. In every specimen, anterior tibial translation increased with loss of the ACL and was greatest at 25 degrees of flexion, where an average displacement of 3.3 mm was observed. Subluxation was not significant at flexion angles exceeding 60 degrees, regardless of ACL deficiency. We also examined the effect of an external restraining force on tibial subluxation in the ACL deficient knee. Posteriorly directed forces of 0 N, 45 N (10 pounds), 90 N (20 pounds), 135 N (30 pounds), and 225 N (50 pounds) were applied to the tibia at the level of the tibial tubercle. Anterior subluxation was eliminated through application of forces ranging from a maximum of 106 N (23.6 pounds) at 10 degrees to only 13 N (2.9 pounds) at 60 degrees.     

Rehabilitation of the anterior cruciate deficient knee

Progressive rehabilitation of the anterior cruciate deficient knee requires attention to the signs of recovery or lack of it, so that the rehabilitation program can be adjusted. A close monitoring program by the physician or therapist, or both, is more effective than the introduction of complicated equipment. By dividing the rehabilitation program into segments with specific goals and responsibilities, an informed rehabilitation team (physician, therapist, patient) can progress from injury to complete neuro-musculo-skeletal re-education.     

Three-dimensional dynamic motion analysis of the anterior cruciate ligament deficient knee joint

Dynamic three-dimensional motion analyses of 15 fresh human knee joints subjected to combinations of flexion velocity and moment, internal and external femoral torque, and horizontal shear before and after sectioning the ACL were performed. ACL deficient specimens demonstrated marked anterior instability without rotational instability. The pivot shift phenomenon occurred with an isolated ACL deficiency and was the result of anterior instability. The pivot shift was accentuated by external femoral torque, decreased by internal femoral torque, and was present in the absence of any applied torque. The pivot shift produced a sudden directional change in the motion of both femoral condyles and may be responsible for the meniscal degeneration that accompanies chronic ACL deficiency.     

The effect of anterior cruciate ligament trauma and bracing on knee proprioception

We studied the effect that chronic anterior cruciate ligament disruption, functional bracing, and a neoprene sleeve have on knee proprioception by measuring the threshold to detection of passive knee motion in all three conditions. The threshold to detection of passive knee motion was worse in knees with chronic anterior cruciate ligament insufficiency when compared with uninjured knees. This difference was small, on average an additional 0.28 degree of flexion-extension rotation was required for the anterior cruciate ligament-deficient knee before the subject detected motion, and of questionable significance from a clinical and functional perspective. Wearing a functional brace or neoprene sleeve on the anterior cruciate ligament-deficient knee did not significantly change the threshold to detection of passive motion in comparison with the same knee without a brace, although improvements were observed. There was no relationship between the most common clinical means of characterizing altered biomechanics of the anterior cruciate ligament-deficient knee (that is, the magnitude of anterior-posterior knee laxity and the grade of pivot shift) and the threshold to detection of passive knee motion.     

Impact biomechanics of lateral knee bracing. The anterior cruciate ligament

We evaluated the effects of six different prophylactic braces on ACL ligament strain under dynamic valgus loads using a mechanical surrogate limb validated against human cadaveric specimens. Medical collateral ligament and anterior cruciate ligament peak forces, medial collateral ligament and anterior cruciate ligament tension initiation times, and impact safety factors were calculated for both braced and unbraced conditions. These tests were conducted to determine whether or not application of a prophylactic brace might provide protection to the anterior cruciate ligament under valgus loading conditions. The results of this study indicate that those braces that increased impact duration appear to differentially protect the anterior cruciate ligament more than the medial collateral ligament, and that most of the braces tested appear to provide some degree of protection to the anterior cruciate ligament under direct lateral impacts. These findings should be confirmed clinically.     

The conservative treatment of the anterior cruciate deficient knee

Seventy-nine recreational athletes (average age, 26 years) with complete ACL tears were treated with nonligamentous arthroscopic surgery, monitored rehabilitation, functional bracing, and activity modification. The average followup was 52 months (range, 36 to 102 months). Six (8%) patients ultimately underwent ligament reconstruction and were considered failures of nonreconstructive treatment. The remaining 73 patients were the subject of detailed analysis. There were 9 (11%) excellent, 25 (32%) good, 17 (22%) fair, and 28 (35%) poor results. Although 71 patients (97%) were satisfied with their knee for activities of daily living, only 36 (49%) were satisfied with their knee for sports. Twenty-nine (40%) had significantly modified their athletic activities. Age, sex, interval from injury to treatment, associated meniscal tears (49 or 67%), and articular cartilage damage (21 or 29%) had no apparent effect on the outcome. Poor results were noted in 29 (40%) patients with significant pivot shifts. Multiple repeat injuries, repeat arthroscopy, isokinetic deficits, and increased length of followup were also associated with poor results.     

A biomechanical evaluation of tibiofemoral rotation in anterior cruciate deficient knees during walking and running

ACL injury has been associated with increased instability of the knee in both in vitro and in vivo studies using passively applied forces. This study assessed tibiofemoral rotation after ACL injury during the functional activity of treadmill ambulation using a triaxial electrogoniometer. Isometric and isokinetic peak torques of the quadriceps and hamstrings were obtained using the Cybex II isokinetic dynamometer. Significant increases in tibiofemoral rotation were noted with increased running speed in the injured and normal knees. The degree of rotation in the injured limb did not significantly exceed that of the normal limb. Isokinetic strength of the quadriceps and hamstrings correlates significantly with the observed extent of rotation.     

Electromyographic and kinematic analysis of cutting maneuvers. Implications for anterior cruciate ligament injury

The objective of this study was to qualitatively characterize quadriceps and hamstring muscle activation as well as to determine knee flexion angle during the eccentric motion of sidestep cutting, cross-cutting, stopping, and landing. Fifteen healthy collegiate and recreational athletes performed the four movements while knee angle and electromyographic activity (surface electrodes) of the vastus lateralis, vastus medialis obliquus, rectus femoris, biceps femoris, and medial hamstring (semimembranosus/semitendinosus) muscles were recorded. The results indicated that there is high-level quadriceps muscle activation beginning just before foot strike and peaking in mid-eccentric motion. In these maneuvers, the level of quadriceps muscle activation exceeded that seen in a maximum isometric contraction. Hamstring muscle activation was submaximal at and after foot strike. The maximum quadriceps muscle activation for all maneuvers was 161% maximum voluntary contraction, while minimum hamstring muscle activity was 14%. Foot strike occurred at an average of 22 degrees of knee flexion for all maneuvers. This low level of hamstring muscle activity and low angle of knee flexion at foot strike and during eccentric contraction, coupled with forces generated by the quadriceps muscles at the knee, could produce significant anterior displacement of the tibia, which may play a role in anterior cruciate ligament injury.     

Effects of knee bracing on the sensorimotor function of subjects with anterior cruciate ligament reconstruction

The sensorimotor performance of the knee joint in 31 subjects who had undergone unilateral anterior cruciate ligament reconstruction at least 5 months previously was tested under three bracing conditions, 1) the DonJoy Legend brace, 2) a mechanical placebo brace, and 3) no brace, in random order. The accuracy of the subjects' ability to reproduce specified knee joint angles was tested as well as the isokinetic performance of their knee muscles at 60 and 180 deg/sec. The results showed that subjects with the brace or placebo brace performed similarly in reproducing the knee joint positions, but both groups performed better than the subjects without a brace. Isokinetic tests revealed no difference among the three groups in extensor and flexor peak torque production at 60 deg/sec or total work done by the extensors and flexors at 60 and 180 deg/sec. These results suggest that knee bracing can improve the static proprioception of the knee joint, but not the muscle contractile function, in subjects with anterior cruciate ligament reconstruction under isokinetic testing conditions. The finding of similar performances for joint angle reproduction in the brace and placebo brace groups suggests that the apparent improvement in proprioception with knee bracing was not due to the mechanical restraining action of the brace.     

Is bracing after anterior cruciate ligament reconstruction necessary? A 2-year follow-up of 78 consecutive patients rehabilitated with or without a brace

The aim of this study was to evaluate the effect of a standard postoperative rehabilitation knee brace on function, stability and postoperative complications at the 2-year follow-up after anterior cruciate ligament (ACL) reconstructive surgery. Seventy-eight consecutive patients with a unilateral chronic ACL rupture reconstructed by the same surgeon using the endoscopic “all-inside” technique, patellar tendon autograft and interference screw fixation were included in the study. The rehabilitation followed a standard protocol. Group A included 39 patients who were supplied postoperatively with a knee brace for 4 (range 3–6) weeks. Group B included 39 patients for whom a brace was not used. The median age was 27 (range 16–48) years in group A and 26 (range 14–51) years in group B. The median time period between the injury and the index operation was 24 (range 3–150) months in group A and 18 (range 3–360) months in group B. All 78 patients were re-examined by two independent observers after a median follow-up period of 25 (range 23–28) months in group A and 24 (range 22– 27) months in group B. The median KT-1000 total side-to-side difference between the reconstructed and the uninjured knees at 89 N was 3 (range –5.5–11) mm in group A and 3 (range –7–10) mm in group B (NS). When the anterior translation was tested separately at 89 N, the corresponding values were 3 (range –4–13) mm in group A and 3 (range –5–10) mm in group B (NS). The median one-leg hop quotient was 95% (range 50%–167%) of the uninjured leg in group A and 92% (range 64%–119%) in group B (NS). The median Lysholm score was 89 (range 39–100) points in group A and 85 (range 37–100) points in group B (NS). In group A, 27/39 (69%) patients and in group B 21/39 (54%) patients were classified as excellent or good (NS). The median Tegner activity level was 7 (range 3–9) in group A and 6 (range 3–9) in group B (NS). Using the IKDC scale, 27/39 (69%) in group A and 24/39 (62%) in group B were classified as normal or nearly normal (NS). The median sick leave in group A was 62 (range 0–357) days and 59 (range 0–243) days in group B (NS). No serious complications occurred during the first 6 postoperative weeks. Two serious complications were, however, registered after the 6th postoperative week. One patient in group A sustained a rupture of the reconstructed ACL 8 weeks postoperatively (3 weeks after removing the brace), and one patient in group B sustained an undislocated patellar fracture during the 7th postoperative week after a fall. This study indicates that the use of a postoperative rehabilitation brace after an arthroscopic ACL reconstruction did not appear to influence either objective stability or subjective function by the 2-year follow-up. Received: 23 December 1996 Accepted: 15 April 1997     

No benefit of bracing on the early outcome after anterior cruciate ligament reconstruction

Forty patients were prospectively investigated to evaluate the effects of bandaging after reconstructive surgery of the anterior cruciate ligament (ACL). For the 6 weeks of the postoperative course, the operated knee was bandaged in 20 patients (group A) and braced in the other 20 patients (group B). The isokinetic torque for extension and flexion (Cybex) and the range of motion (ROM) were investigated after 6, 12, 24 and 52 weeks postoperatively. At 24 weeks and 1 year postoperatively the stability of the knee joint (KT-1000) as well as the clinical outcome (‘Orthopädische Arbeitsgemeinschaft Knie’) were evaluated. No statistically significant differences between the two groups were found for the extension and flexion strengths. Free ROM was achieved significantly earlier in group A than in group B. No statistically significant differences regarding the stability of the operated knee joint nor the early outcome were found between the two groups. This study demonstrated that the renunciation of using a brace had no adverse effect on the early outcome with respect to stability and function. On the contrary, bracing seems not to be mandatory after ACL reconstruction when the central third of the patellar tendon is used.     

The effect of proprioceptive knee bracing on knee stability after anterior cruciate ligament reconstruction

BackgroundInjury to the anterior cruciate ligament (ACL) is common among young athletes and can impact knee stability and control. Wearing proprioceptive knee braces can improve knee control and may reduce the risk factors associated with injury and re-injury, although the effect of such braces after ACL reconstruction (ACLR) is unclear.Research questionThis study aimed to determine the effect of proprioceptive knee bracing on knee control and subjective rating of participants post ACLR during three dynamic tasks.MethodsFifteen participants 2–10 years post ACLR performed a slow step down, single leg drop jump, and pivot turn jump with and without a proprioceptive knee brace. Knee kinematics in the sagittal (flexion – extension), coronal (abduction – adduction), and transverse (internal – external rotation) planes were collected using a 3D infrared system. Paired t-tests were performed to explore differences in knee angles and angular velocities between the no brace and brace conditions during the three tasks. After each task, subjective ratings regarding ease of the task were recorded.ResultsThe brace reduced the peak knee external rotation angle and range of motion in the transverse plane during the pivot turn jump task, and significantly increased the maximum knee flexion angular velocity during the single leg drop jump task. The majority of participants reported that tasks were easier to perform with the proprioceptive brace than without.SignificanceThis study confirms that proprioceptive knee braces can significantly influence knee kinematics during dynamic tasks post ACLR. The observed effects were clinically relevant.     

Associations of knee angles,moments and function among subjects that are healthy and anterior cruciate ligament deficient (ACLD) during straight ahead and crossover cutting activities

The objective of this study was to compare knee angles and moments of healthy subjects (n=20) and subjects that were anterior cruciate ligament deficient (ACLD) (n=16) during stepping and crossover cutting activities. Subjects that were ACLD were separated into high (n=7) and low (n=9) functioning groups based on knee functional ratings. Knee angles and moments were estimated using three dimensional motion tracking and force plate data. The results suggest that knee angle and moment data were associated with level of functioning of ACLD subjects. Primarily knee frontal and transverse plane moments distinguished the stepping and crossover cut activities. Only some of the findings for the ACLD group were attributed to increasing knee stability.     

EMG power spectra of intercollegiate athletes and anterior cruciate ligament injury risk in females

PURPOSE: Females have a disproportionately high incidence of anterior cruciate ligament (ACL) injuries compared with males in analogous sports. Although the pathogenesis of this higher frequency has not been elucidated, gender differences in neuromuscular control of the knee may play an important role. This study evaluates EMG power spectra of the quadriceps and hamstring muscles during dynamic, fatiguing exercise to examine differences between male and female intercollegiate athletes. METHODS: Fifty-one collegiate basketball and soccer players (25 female, 26 male) were studied. Maximum voluntary contraction (MVC) was determined for knee flexion and extension. Three consecutive 2-min bouts of isokinetic knee flexion and extension exercise were performed at 40% MVC. EMG activity in the biceps femoris and vastus medialis obliquus was recorded using bipolar surface electrodes. RESULTS: MVC normalized to body weight was significantly greater in males than in females for the quadriceps (P< 0.01). Quadriceps coactivation ratios were significantly higher in females than in males during knee flexion exercises (P< 0.01). CONCLUSIONS: This study demonstrates differences in the EMG power spectra for females when compared with a matched group of males. Increased quadriceps coactivation in females may increase anterior tibial loads under dynamic conditions, thus placing the ACL at higher risk for injury in the female athlete.     

Altered timing of hamstring muscle action in anterior cruciate ligament deficient patients

Recent studies indicate that the hamstrings are essential antagonists in ACL deficient patients. In order to evaluate muscle coordination under physiologic conditions, nine patients with arthroscopically verified total ACL ruptures were compared with nine control volunteers. This comparison was made from electromyograms of the thigh muscles and heel contact recordings made while walking on a treadmill. While walking on a horizontal level, the patient's muscle activity did not differ from controls, but when the knee load was increased by walking uphill, the hamstring muscles in patients were activated significantly earlier than among controls. It is proposed that an altered muscle coordination is probably essential in ACL deficient patients to secure knee stability. This study suggests a new approach to investigate the coordination of muscles under physiologic conditions in ACL deficient patients, and may guide rehabilitation programs in the future.