A mechanism for rotation restraints in the knee joint

Mapping of contributions from collateral ligaments to overall knee joint constraint: an experimental cadaveric study

Understanding the contribution of the soft-tissues to total joint constraint (TJC) is important for predicting joint kinematics, developing surgical procedures, and increasing accuracy of computational models. Previous studies on the collateral ligaments have focused on quantifying strain and tension properties under discrete loads or kinematic paths; however, there has been little work to quantify collateral ligament contribution over a broad range of applied loads and range of motion (ROM) in passive constraint. To accomplish this, passive envelopes were collected from nine cadaveric knees instrumented with implantable pressure transducers (IPT) in the collateral ligaments. The contributions from medial and lateral collateral ligaments (LCL) were quantified by the relative contribution of each structure at various flexion angles (0-120 deg) and compound external loads (±10 N m valgus, ±8 N m external, and ±40 N anterior). Average medial collateral ligament (MCL) contributions were highest under external and valgus torques from 60 deg to 120 deg flexion. The MCL showed significant contributions to TJC under external torques throughout the flexion range. Average LCL contributions were highest from 0 deg to 60 deg flexion under external and varus torques, as well as internal torques from 60 deg to 110 deg flexion. Similarly, these regions were found to have statistically significant LCL contributions. Anterior and posterior loads generally reduced collateral contribution to TJC; however, posterior loads further reduced MCL contribution, while anterior loads further reduced LCL contribution. These results provide insight to the functional role of the collaterals over a broad range of passive constraint. Developing a map of collateral ligament contribution to TJC may be used to identify the effects of injury or surgical intervention on soft-tissue, and how collateral ligament contributions to constraint correlate with activities of daily living.

Comparison Between Sexes of Bone Contusions and Meniscal Tear Patterns in Noncontact Anterior Cruciate Ligament Injuries

BACKGROUND

Valgus load has been linked to female predominance and mechanism for noncontact anterior cruciate ligament (ACL) injuries. Magnetic resonance imaging (MRI) studies reporting frequent medial contusions in noncontact ACL injuries suggest anterior translation rather than a valgus mechanism.

HYPOTHESIS

Bone contusion and meniscal tear patterns differ between sexes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study included a review of clinic notes, operative reports, and MRI of patients younger than 20 years who underwent acute primary ACL reconstruction for a noncontact injury between January 1, 2005, and January 1, 2010. A blinded musculoskeletal MRI radiologist reported the incidence of medial and lateral femoral and tibial bone contusions on MRI, as well as the severity of medial versus lateral tibial contusions. The location of the bone contusions and meniscal tears and the maximal tibial contusion severity were compared through chi-square analysis (statistical significance, P < .05).

RESULTS

A total of 73 patients met inclusion criteria: 28 males, 45 females; mean age, 16.1 ± 1.7 years (males), 16.5 ± 1.7 years (females). No significant differences were noted between sexes for location of tibial contusions (P = .32), femoral contusions (P = .44), or meniscal tears (P = .715). The most common tibial contusion pattern was to have both medial and lateral tibial contusions, in both male (57%) and female (60%) patients. The most common femoral contusion pattern was lateral only in females (62%) and both medial and lateral in males (50%). The percentage of female (29%) and male (29%) patients with isolated medial meniscal tears was nearly identical. More males (29%) than females (18%) had isolated lateral meniscal tears (P = .72). No significant difference in the relative severity of the tibial contusions was noted (P = .246). The lateral tibial contusion was rated as being more severe than the medial in the majority of females (64%) and males (57%).

CONCLUSION

No significant differences were detected between sexes with noncontact ACL injuries for location of tibial or femoral contusions or meniscal tears or for severity of medial versus lateral tibial contusions. The MRI data were not consistent with the valgus collapse mechanism of injury.

Knee rotation in healthy individuals related to age and gender

An external device ("the Rottometer") was especially designed to measure passive knee rotation in vivo. The device had earlier been evaluated with respect to it's validity and reliability. In the present study, we evaluated knee rotation in knee-healthy individuals and studied possible age and gender related differences. Measurements of total internal-external rotation were made at 90°, 60°, and 30° of flexion using 6 and 9 N m torques, as well as the examiner's apprehension of end-feel as displacing forces. The study group constituted of 120 healthy subjects (60 females and 60 males) with no prior or present knee disorders. The sample was divided into four age groups (15-30, 31-45, 46-60, and >60 years). The results showed no differences in knee rotation between the right and left knees or between the different flexion angles. The females showed 10-20% (p < 0.01) larger knee rotation than the males at all the three flexion angles and at all the three applied torques in all age-matched groups. In all age groups in both genders, the internal rotation accounted for 40-44% and the external for 56-60% of the total internal-external knee rotation.

Knee rotational laxity: an investigation of bilateral asymmetry for comparison with the contralateral uninjured knee

BACKGROUND

Instability associated with anterior cruciate ligament injury is commonly evaluated against the patient's contralateral knee. The objectives of this study were, therefore, to assess symmetry of rotational knee laxity in vivo under passive torsional loading in uninjured subjects, and to compare mean rotation of this control group with the contralateral, intact knees of anterior cruciate ligament deficient patients.

METHODS

Axial knee rotation was measured in 29 patients with unilateral anterior cruciate ligament injury and 15 uninjured age and gender-matched control subjects using an imaging-compatible torsional loading device. Side-to-side differences in internal, external, and range of knee rotation were assessed in the control group and mean bilateral knee rotation was compared to the patients' contralateral knee data at both full extension and 30° of flexion.

FINDINGS

Statistically significant differences in symmetry were found in three of the six measures of transverse plane rotation in the uninjured knees; a mean side-to-side difference of 2.2° in range of rotation was detected in the flexed position. No significant differences were observed between the mean values of the healthy control group and the contralateral knees of the anterior cruciate ligament deficient patients.

INTERPRETATION

Bilateral asymmetry of rotational laxity occurs in healthy individuals. Nevertheless, comparability of rotational knee laxity between the contralateral limbs of patients and the uninjured population was evidence that rotational laxity was not inherent or developed in the contralateral knees of the anterior cruciate ligament deficient participants.

Measurements of knee rotation-reliability of an external device in vivo

BACKGROUND

Knee rotation plays an important part in knee kinematics during weight-bearing activities. An external device for measuring knee rotation (the Rottometer) has previously been evaluated for validity by simultaneous measurements of skeletal movements with Roentgen Stereometric Analysis (RSA). The aim of this study was to investigate the reliability of the device.

METHOD

The within-day and test-retest reliability as well as intertester reliability of the device in vivo was calculated. Torques of 3, 6 and 9 Nm and the examiner's apprehension of end-feel were used at 90°, 60° and 30° of knee flexion. Intraclass Correlation Coefficient 2,1 (ICC 2,1), 95% confidence interval (CI) of ICC and 95% CI between test trials and examiners were used as statistical tests.

RESULT

ICC2,1 ranged from 0.50 to 0.94 at all three flexion angles at 6 and 9 Nm as well as end-feel, and from 0.22 to 0.75 at 3 Nm applied torque.

CONCLUSION

The Rottometer was a reliable measurement instrument concerning knee rotation at the three different flexion angles (90°, 60° and 30°) with 6 and 9 Nm applied torques as well as the examiner's apprehension of end-feel. Three Nm was not a reliable torque. The most reliable measurements were made at 9 Nm applied torque.

Double-bundle ACL surgery demonstrates superior rotational kinematics to single-bundle technique during dynamic task

BACKGROUND

While traditional surgical repair of the anterior cruciate ligament is able to restore anterior-posterior knee stability, laxity in the transverse plane remains. Double-bundle reconstruction has demonstrated greater rotational restraint than the single-bundle technique under passive loading conditions; however, no comparison has been made under physiological weight-bearing conditions. The purpose of this study was to determine differences in rotational knee kinematics during a dynamic task in patients who had received either a single- or double-bundle reconstruction.

METHODS

Twenty-two patients exhibiting isolated anterior cruciate ligament rupture were randomly allocated either a single or double-bundle reconstruction. Three-dimensional knee kinematics were measured during a dynamic cutting activity prior to and following surgery. Functional range of rotation was compared between groups pre- and post-operatively and kinematics were assessed against uninjured control subjects.

FINDINGS

No difference in overall range of rotation was found under physiological loading conditions. However, a significant interaction of the midpoint of the range of movement was observed; a greater external rotational shift in the single-bundle group followed reconstruction, while the kinematics of the double-bundle patient group shifted closer to those of the control group.

INTERPRETATION

The double-bundle reconstruction demonstrated superior outcome in rotational kinematics to the single-bundle technique.

Case report of atypical bilateral posteromedial knee instability in a male recreational runner

The posteromedial corner of the knee has intricate anatomical and biomechanical relationships critical to the function of the tibiofemoral joint. Missed or late diagnosis of pathomechanical disorders of the region, such as anteromedial rotary instability, in individuals with knee pain, may result in long-term decreased functional mobility and predisposition for degenerative disorders. This case report describes the chronological history and experience of a 35-year-old male with late diagnosis of anteromedial rotary instability and the subsequent surgical reconstruction and rehabilitation. Difficulties with clinical recognition of the underlying pathology and the postoperative course of rehabilitation are also discussed.

Anterior cruciate ligament injury induced by internal tibial torsion or tibiofemoral compression

The knee is one of the most frequently injured joints in the human body. Approximately 91% of ACL injuries occur during sporting activities, usually from a non-contact event. The most common kinetic scenarios related with ACL injuries are internal twisting of the tibia relative to the femur or combined torque and compression during a hard landing. The hypothesis of this study was that the magnitudes and types of motion observed after ACL rupture would significantly change from the relative joint displacements present just before ACL injury. Compression or torsion experiments were conducted on 7 pairs of knee joints with repetitive tests at increasing intensity until catastrophic failure. ACL injury was documented in all cases at 5.4+/-2kN of TF compression or 33+/-13Nm of internal tibial torque. The femur displaced posteriorly relative to the tibia in pre-failure and with a higher magnitude in failure tests under both loading conditions. In compression experiments there was internal rotation of the tibia in pre-failure tests, but external rotation of the tibia after the ACL failed. In torsion experiments, failure occurred at 58+/-19 degrees of internal tibial rotation, and valgus rotation of the femur increased significantly after ACL injury. These new data show that the joint motions can vary in magnitude and direction before and after failure of the ACL. Video-based studies consistently document external rotation of the tibia combined with valgus knee bending as the mechanism of ACL injury although these motions could be occurring after ACL rupture.

Knee rotation during a weightbearing activity: influence of turning

Kinematic studies, in which mobile- and fixed-bearing total knee arthroplasty (TKA) were compared, showed controversial results with respect to axial femorotibial rotation. However, all studies focused only on straight ahead tasks, which may underestimate possible differences in freedom of rotation. The purpose of this study was to investigate the influence of turning on normal axial knee rotation. If large differences across tasks were to be found, this would support the use of this task in the evaluation of in-vivo TKA kinematics. In 15 healthy persons, crossover and sidestep turns were added to a standardized chair rise. Three-dimensional knee angles were recorded using an optoelectronic motion analysis system, and a noninvasive epicondylar frame was developed to track the femur. Compared to knee rotation during the straight ahead task, average peak tibial internal rotation increased during a crossover turn (p<0.001), as did peak external tibia rotation during a sidestep turn (p<0.001). The combined range of axial rotation for both turning tasks together was 20.9 degrees , versus 13.5 degrees for the straight ahead task (p<0.001). The turning maneuvers in this study induced a large range of axial knee rotation, so they could be important in studies comparing freedom of rotation in mobile- and fixed-bearing TKA.

Torsional stability of intramedullary compression nails: tibial osteotomy model

BACKGROUND

Studies comparing intramedullary compression nailing to conventional dynamized intramedullary nailing contend that better clinical outcomes of intramedullary compression techniques result from greater rotational stability of fracture or osteotomy sites. However, there appears to be no experimental evidence that rotational stability is improved with intramedullary nail compression. This study evaluated the effect of intramedullary nail compression on cadaveric and composite tibial fragment rotation above and below a mid-tibial transverse osteotomy.

METHODS

Twelve composite and four matched pairs of human cadaveric tibiae were randomized into either a compression group or a non-compressed dynamized group. A bi-axial servo-hydraulic testing machine applied 5Nm of internal and external torque (2Nm/s) under constant axial loads of 375N and 750N. Rotation along each tibia and at the osteotomy site was recorded from the trajectories of infrared emitting diodes rigidly attached along the tibial shaft.

FINDINGS

In comparison to dynamized nails, intramedullary nail compression significantly reduced the rotation at the osteotomy site in both human (8.9 degrees reduction; P=0.007) and composite tibiae (2.5 degrees reduction; P=0.039) under 750N of axial load. A similar result was noted for simulated half-body weight loads (375N) for both composite (3.0 degrees reduction; P=0.009) and human tibiae (10.5 degrees reduction; P=0.003).

INTERPRETATION

Intramedullary nail compression more effectively reduced tibial fragment rotation about a mid-tibial osteotomy than conventional dynamized intramedullary nails because intramedullary nails created more osteotomy site compression than the application of body weight to tibiae instrumented with dynamized intramedullary nails.

Differences in peak knee valgus angles between individuals with high and low Q-angles during a single limb squat

BACKGROUND

Differences in anatomical alignment between genders have been suggested as causes of the disparity in anterior cruciate ligament injury rates. A larger Q-angle may be associated with increased knee valgus during movement resulting in anterior cruciate ligament strain. This study investigated whether healthy college-aged subjects with a large Q-angle display greater peak knee valgus during a single limb squat compared to those with a small Q-angle. The study also determined whether the high and low Q-angle groups displayed differences in other select anatomical variables, and whether these anatomical variables were related to knee valgus.

METHODS

Twenty subjects, categorized as having a "high Q-angle" (> or = 17 degrees) or a "low Q-angle" (< or = 8 degrees) were videotaped during the performance of a single leg squat. The peak valgus angles for the right knee were calculated. One-tailed independent measures t-tests were used to determine whether individuals with a large Q-angle exhibit (1) significantly greater peak knee valgus during a single leg squat compared to those with a small Q-angle and, (2) greater pelvic width to femoral length ratios and greater static knee valgus than subjects with a small Q-angle. The Pearson product-moment correlation was used to establish the relationships between pelvic width to femoral length ratios and static knee valgus, pelvic width to femoral length ratios and dynamic knee valgus, and static knee valgus and dynamic knee valgus.

FINDINGS

Peak knee valgus during the single leg squat, and static knee valgus were not significant greater in the high Q-angle group compared to the low Q-angle group (P=0.09; P=0.31). Subjects with a larger Q-angle, however, had a significantly greater pelvic width to femoral length ratios (P=0.015) compared to subjects with a small Q-angle. Pelvic width to femoral length ratios was related to both static and dynamic knee valgus (r=0.47, P=0.02; r=0.48, P=0.02), but static knee valgus was not related to dynamic knee valgus.

INTERPRETATION

The findings suggest that pelvic width to femoral length ratios, rather than Q-angle, may be a better structural predictor of knee valgus during dynamic movement.

Factors for the presence of anteromedial rotatory instability of the knee

Anteromedial rotatory instability (AMRI) of the knee joint was investigated with an instrument newly designed to simulate the manual AMRI test and to quantify its magnitude. Thirty healthy subjects, 20 patients with anterior cruciate ligament (ACL) injury, and 10 with both ACL and medial collateral ligament (MCL) injuries were examined. Using the instrument, 100 N of anterior force was applied to the proximal part of the tibia with the foot in neutral rotation, 30 degrees of internal rotation, and 30 degrees of external rotation, and the magnitude of anterior displacement was recorded. The measurement was carried out at 20 degrees and 90 degrees of flexion. A significant increase in anterior laxity was observed in all three rotation positions in the injured patients. However, the magnitude of laxity in external rotation was less than that in neutral rotation in the ACL injured patients, whereas it was the greatest in external rotation in ACL + MCL injured patients. Thus, we conclude that an injury involving both the ACL and MCL causes AMRI.

Therapeutic low energy laser improves the mechanical strength of repairing medial collateral ligament

BACKGROUND AND OBJECTIVES

Low energy laser therapy has been shown to enhance collagen production but its effect on tissue strength is not well reported. We tested the effects of therapeutic laser on the strength of healing medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-four rats received surgical transection to their right MCL and eight received sham operation. After surgery, 16 received a single dose of gallium aluminum arsenide laser to their transected MCL for 7.5 minutes (n = 8) or 15 minutes (n = 8) and eight served as control with placebo laser, while the sham group didn't receive any treatment. The MCLs were biomechanically tested at either 3 or 6 weeks post-operation.

RESULTS

The normalized ultimate tensile strength (UTS) and stiffness of laser and sham groups were larger than control (P < 0.001). The UTS of laser and sham groups were comparable. Laser and sham groups had improved in stiffness from 3 to 6 weeks (P < 0.001).

CONCLUSIONS

A single dose of low energy laser therapy improves the UTS and stiffness of repairing MCL at 3 and 6 weeks after injury.

Giving way event during a combined stepping and crossover cutting task in an individual with anterior cruciate ligament deficiency

STUDY DESIGN

Case study.

OBJECTIVE

To compare knee kinematics and moments of nongiving way trials to a giving way trial during a combined stepping and crossover cutting activity.

BACKGROUND

The knee kinematics and moments associated with giving way episodes suggest motor control strategies that lead to instability and recovery of stability during movement.

METHODS AND MEASURES

A 27-year-old woman with anterior cruciate ligament deficiency reported giving way while performing a combined stepping and crossover cutting activity. A motion analysis system recorded motion of the pelvis, femur, tibia, and foot using 3 infrared emitting diodes placed on each segment at 60 Hz. Force plate recordings at 300 Hz were combined with limb inertial properties and position data to estimate net knee joint moments. The stance time, foot progression angle, and cutting angle were also included to evaluate performance between trials.

RESULTS

Knee internal rotation during the giving way trial increased 3.2 degrees at 54% of stance relative to the nongiving way trials. Knee flexion during the giving way trial increased to 33.1 degrees at 66% of stance, and the knee moment switched from a nominal flexor moment to a knee extensor moment at 64% of stance. The knee abductor moment and external rotation moment during the giving way trial deviated in early stance.

CONCLUSIONS

The observed response to the giving way event suggests that increasing knee flexion may enhance knee stability for this subject. The transverse and frontal plane moments appear important in contributing to the giving way event. Further research that assists clinicians in understanding how interventions can impact control of movements in these planes is necessary.

Arthroscopic decompressive medial release of the varus arthritic knee: Expanding the functional envelope

We present the rationale and technique for treating medial knee osteoarthritis by dynamically unloading the medial compartment of the knee. Recent advances in kinematic studies indicate a dynamic linkage between differing degrees of freedom in the knee joint. Both the adduction moment and the foot progression angle are important determinants of medial compartment loading. The medially osteoarthritic knee has progressive compromise of free motion in more than 1 plane. Arthroscopic decompressive medial release unloads the medial compartment by release of the medial capsule and medial collateral ligament in the presence of intact cruciate ligaments, which may allow a decreased adduction moment and decrease of the external rotation restraint in extension found in more severely osteoarthritic knees. A case series of 38 patients with medial gonarthrosis was treated by this technique at the Hermanos Ameijeiras Hospital in Havana, Cuba. All patients had good results without postoperative valgus instability or significant complications. We feel that this technique warrants further clinical and biomechanical study for its use in isolation or in combination with high tibial osteotomy or minimally invasive selective osteotomy for the treatment of medial gonarthrosis of the knee. A minimally invasive, selective approach to biomechanical factors in osteoarthritis may be combined with other modulating techniques in efforts to forestall or prevent the need for total joint replacement.

Effects of stress shielding on the transverse mechanical properties of rabbit patellar tendons

With the aim of studying mechanisms of the remodeling of tendons and ligaments, the effects of stress shielding on the rabbit patellar tendon were studied by performing tensile and stress relaxation tests in the transverse direction. The tangent modulus, tensile strength, and strain at failure of non-treated, control patellar tendons in the transverse direction were 1272 kPa, 370 kPa, and 40.5 percent, respectively, whereas those of the tendons stress-shielded for 1 week were 299 kPa, 108 kPa, and 40.4 percent, respectively. Stress shielding markedly decreased tangent modulus and tensile strength in the transverse direction, and the decreases were larger than those in the longitudinal direction, which were determined in our previous study. For example, tensile strength in the transverse and longitudinal direction decreased to 29 and 50 percent of each control value, respectively, after 1 week stress shielding. In addition, the stress relaxation in the transverse direction of stress-shielded patellar tendons was much larger than that of nontreated, control ones. In contrast to longitudinal tensile tests for the behavior of collagen, transverse tests reflect the contributions of ground substances such as proteoglycans and mechanical interactions between collagen fibers. Ground substances provide lubrication and spacing between fibers, and also confer viscoelastic properties. Therefore, the results obtained from the present study suggest that ground substance matrix, and interfiber and fiber-matrix interactions have important roles in the remodeling response of tendons to stress.

A validated three-dimensional computational model of a human knee joint

This paper presents a three-dimensional finite element tibio-femoral joint model of a human knee that was validated using experimental data. The geometry of the joint model was obtained from magnetic resonance (MR) images of a cadaveric knee specimen. The same specimen was biomechanically tested using a robotic/universal force-moment sensor (UFS) system and knee kinematic data under anterior-posterior tibial loads (up to 100 N) were obtained. In the finite element model (FEM), cartilage was modeled as an elastic material, ligaments were represented as nonlinear elastic springs, and menisci were simulated by equivalent-resistance springs. Reference lengths (zero-load lengths) of the ligaments and stiffness of the meniscus springs were estimated using an optimization procedure that involved the minimization of the differences between the kinematics predicted by the model and those obtained experimentally. The joint kinematics and in-situ forces in the ligaments in response to axial tibial moments of up to 10 Nm were calculated using the model and were compared with published experimental data on knee specimens. It was also demonstrated that the equivalent-resistance springs representing the menisci are important for accurate calculation of knee kinematics. Thus, the methodology developed in this study can be a valuable tool for further analysis of knee joint function and could serve as a step toward the development of more advanced computational knee models.