The relationships between instrumented measurements of ankle and knee ligamentous laxity and generalized joint laxity

AIM: The purpose of this study was to evaluate whether lower extremity joint laxity is a function of a particular joint and/or a generalizable characteristic (trait) of the person. Validated instrumented measurements of ankle and knee joint-specific laxity in the same individual were correlated to determine whether a relationship exists. In addition, ankle and knee joint-specific laxity were correlated with generalized joint laxity using the modified Beighton mobility index. METHODS: Fifty-seven male and female athletes were studied. We examined dominant ankle laxity using an ankle arthrometer and dominate knee anterior laxity using the KT 2000. The dominant ankle was loaded in anteroposterior (AP) drawer and inversion-eversion (I-E) rotation. Laxity was measured as total AP displacement (millimeters) after +/-125 N of applied force and total I-E rotation (degrees) was measured after +/-4 N x m of applied torque. The dominant knee was loaded with an anterior drawer and laxity (millimeters) was measured after manual maximum displacement. RESULTS: Non-significant correlations were observed among the test variables for generalized joint laxity (0.21 to 0.37; P>0.05) and instrumented ankle and knee joint laxity (0.19 to 0.21; P>0.05). When examined by gender, no statistically significant correlations (0.05 to 0.40; P>0.05) were found for either generalized laxity or instrumented ankle and knee joint laxity. CONCLUSIONS: These results imply that ankle and knee joint laxity are joint-specific and not generalizable.     

Exercise-related knee joint laxity

Knee injuries are the topic of increasingly sophisticated research because of the importance in professional athletics as well as increasing participation in recreational sports. The role of conditioning and fatigue in these injuries remains controversial. Ligaments have high collagen content, and a viscoelastic response to stress would be expected. Because of the postulated relationship between laxity and knee ligament injuries, an experiment was designed using highly motivated athletes to test the hypothesis that exercise to the point of muscular fatigue may cause laxity of the knee and thereby place athletes at risk for ligamentous injury to the knee when fatigued. An exercise protocol was designed to produce muscle fatigue in the hamstring and quadriceps muscle groups. Knee ligament laxity was tested prior to and subsequent to the exercise protocol. To document muscle fatigue, isokinetic testing of right knee flexion and extension power was used several times during the exercise protocol. A knee arthrometer (KT-1000) was used to quantitatively document ligamentous laxity before and after exercise. The results indicated a significant lengthening in knee joint laxity between preexercise and postexercise in the left knee as measured at 15 and 20 pounds of passive displacement force (P less than 0.05). Maximum manual displacement also demonstrated a significant increase in joint laxity (P = 0.02). The right knee, which had undergone isokinetic testing, demonstrated a similar tendency but without a statistically significant difference before and after exercise. There was no significant preexercise side to side difference, but postexercise measurements demonstrated a left-right difference at 15 pounds, 20 pounds, and maximum manual displacement of statistical significance (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of exercise on anterior-posterior knee laxity

A commercial knee laxity testing device was used to quantitate anterior and posterior laxity before and after exercise. Measurements were made at 20 degrees of knee flexion and with a displacement force of 133 N (30 pounds). In sedentary controls no significant change in laxity was noted over 2 hours. Squat power lifters sustained no significant change in laxity after a series of squats (0.4 to 0.7 cm) using 1.6 times body weight. However, 18% to 20% increases in mean anterior and posterior laxity were noted in college basketball players after 90 minutes of practice and in recreational runners after a 10 km race. The role of muscle relaxation in such tests was also evaluated by measuring laxity in normal knees before and during general anesthesia. Negligible laxity change was noted. Thus, functionally "complete" muscle relaxation can be obtained during testing in the cooperative individual. In conclusion, basketball players and distance runners experienced a transient increase in anterior and posterior laxity during exercise. Power lifters doing squats did not demonstrate a significant change in laxity. It appears that repetitive physiologic stresses at a high strain rate produce significant ligamentous laxity, while a relatively few large stresses at a low strain rate do not.     

Two ankle joint laxity testers: reliability and validity

Two test devices were manufactured to objectively measure ankle joint laxity: the dynamic anterior ankle tester (DAAT) and the quasi-static anterior ankle tester (QAAT). The primary aim was to analyse the reliability of both testers; The secondary aim was to assess validity in correlation with TELOS stress test and manual anterior drawer test. Twenty-four normal subjects and 14 patients 1 year after acute lateral ankle ligament injury were included. Both ankles were tested with the DAAT and QAAT by two different observers; one experienced orthopaedic surgeon performed the manual test; the TELOS stress X-rays were evaluated by one observer. Intra observer reliability for the DAAT varied between 0.81 and 0.94; for the QAAT between 0.71 and 0.94. Inter observer reliability for the DAAT varied between 0.84 and 0.94; for the QAAT between 0.76 and 0.82. Concurrent validity showed fair correlation between DAAT and QAAT for the first couple observers (0.71); however, a poor correlation was observed for the second couple (0.42). No significant correlations were found between neither DAAT and the TELOS and the manual test, nor QAAT and the TELOS and the manual test. In conclusion, reliability of both testers is high. Validity of the testers needs further investigation.     

The effect of joint velocity on the contribution of the antagonist musculature to knee stiffness and laxity

The electromyographic (EMG) coactivation patterns of the knee flexors and extensors when acting as antagonists were studied as a function of limb velocity to assess their contribution to joint stiffness and laxity. Normalized antagonist coactivation patterns developed from surface EMG recordings from the hamstrings and quadriceps during maximal effort isokinetic extension and flexion, respectively, demonstrated characteristic variations as the joint velocity increased from 15 deg/sec up to 240 deg/sec. The two-tailed t-test (P less than 0.01) was performed on the data obtained from eight normal knees. The results indicate that both hamstrings and quadriceps demonstrate a significant increase (greater than 100%) in their antagonist coactivation pattern during the final 40 degrees of fast extension and flexion movements, respectively, as limb velocity increases. A minor decrease in antagonist activity of the hamstrings (24%) and quadriceps (8%) was evident during the initial phase of the extension and flexion movements, respectively, as joint velocity increased. We concluded that as limb velocity is increased, there is a substantial reflexive (unintentional) increase in the contribution of the antagonist musculature to joint stiffness and reduction of laxity. The results also suggest that strength training of the hamstrings (rather than quadriceps) should be considered as a modality for conservative treatment of ACL deficiencies, as well as an adjunct to surgical reconstruction. Such training can also reduce the risk of high performance athletes in a reflexive manner by increasing joint stiffness.     

Exercise-induced knee joint laxity in distance runners.

The objectives of this study were to evaluate the effect of exercise on knee joint laxity. If exercise induced laxity is physiological, incorporation of this quality into a ligament replacement material would be indicated. Twenty recreational long distance runners average age 41 (range 24 to 50 yr) were tested before and immediately after 30 minutes of running. Using a computerized goniometer type instrument (Acufex KSS), knee flexion, axial tibial rotation and anterior-posterior tibial displacement were simultaneously recorded, while the runners underwent tests of static as well as dynamic knee joint laxity. At 30 degrees of knee flexion, a maximum increase of 16 per cent in mean total anterior-posterior laxity post-exercise was found. At the examination 30 minutes post-exercise, laxity at 30 degrees of knee flexion was still increased. However, laxity at 90 degrees of knee flexion had decreased to pre-exercise levels or below. Anterior tibial displacement, recorded during eccentric quadriceps activity (0 to 90 degrees of knee flexion) with weights attached to the foot, showed a maximum of 18 per cent increase in total anterior-posterior laxity post-exercise. It is suggested that the laxity increase is caused in part by a true ligamentous laxity increase, and in part by a decreased resting tone of the fatigued muscles.     

The impact of generalized joint laxity on clinical outcomes of total knee arthroplasty

Purpose

The aim of this study was to investigate whether the severity of generalized joint laxity influences preoperative and postoperative clinical outcomes and if patients with severe generalized joint laxity would require a thicker polyethylene (PE) liner during total knee arthroplasty (TKA).

Methods

A total of 338 female patients undergoing TKA were divided into two groups according to generalized joint laxity. Preoperative and postoperative (at 3 years) patellofemoral scale, AKS, WOMAC, ROM, and satisfaction VAS were compared between the two groups. Additionally, PE liner thickness was compared.

Results

Preoperatively, flexion contracture and WOMAC stiffness scores in the severe laxity group were significantly lower than those in the no to moderate laxity group (p?<?0.001 for both). There was no significant difference in postoperative clinical outcomes of patellofemoral scale, AKS, WOMAC, or ROM or in satisfaction VAS between the two groups. There was a significant difference in PE liner thickness between the two groups (10.3?±?1.3 versus 11.4?±?1.2, p?=?0.043).

Conclusions

There was no significant difference of clinical outcomes between the patients with and without severe generalized joint laxity after 3 years of follow-up after TKA, even though preoperative clinical outcomes indicated that the patients with severe generalized joint laxity showed significantly smaller flexion contraction and better WOMAC stiffness score. Since patients with generalized joint laxity require a thicker PE liner, care should be taken to avoid cutting too much bone from patients with severe generalized joint laxity.

Level of evidence

Retrospective comparative study, Level III.

     

Effects of menstrual-cycle hormone fluctuations on musculotendinous stiffness and knee joint laxity

The high risk of anterior cruciate ligament (ACL) injuries in female athletes may be related to hormonal fluctuations resulting in an increased laxity of ligaments and muscles. This study examined changes in lower limb musculotendinous stiffness (MTS) and knee laxity over the course of the menstrual cycle and investigated the interaction of warm-up on MTS. Eleven female netball players aged 16–18 years who were not using hormonal contraceptives and demonstrated regular menstrual cycles participated in this study. Test-sessions were conducted at onset of menses, mid-follicular phase, ovulation and mid-luteal phase. ACL laxity was determined at each test-session using a KT2000™ knee arthrometer. MTS was assessed prior to, and following a standardised warm-up. Repeated measures ANOVA revealed significant (P < 0.05) main effects of test-session and warm-up on MTS. MTS was found to significantly decrease by 4.2% following the warm-up intervention. MTS was significantly lower at week 3 (ovulatory phase) in contrast to weeks 1 and 2 (8.7 and 4.5%, respectively). For knee laxity measures, repeated measures ANOVA revealed no significant (P < 0.05) differences across the menstrual cycle. A reduction in MTS results in greater reliance on reflexive response from the contractile components of the muscle due to a decreased contribution from passive elastic structures and will also increase electromechanical delay. Given that extreme loads are applied to the knee joint within milliseconds, the contractile components cannot respond quickly enough to counteract these sudden and potentially damaging forces. These effects are augmented following a moderate warm-up. Oestrogen fluctuations had no significant effect on anterior knee laxity, however, the effects on MTS over the 28-day cycle were considerable. Future studies should use matched subjects who are using the monophasic oral contraceptive pill to investigate the effects of oestrogen supplementation on lower limb MTS.     

The influence of ankle joint movement on knee joint kinesthesia at various movement velocities

The purpose of this study was to determine if gastrocnemius elongation or shortening and direction and velocity of knee movement influenced knee kinesthesia. Healthy volunteers sat with their knee flexed (20°) and was then passively rotated (flexion or extension) at three velocities (0.5, 2, or 10°/s) while the ankle was either fixed or rotated (dorsiflexed or plantar flexed at 0.17, 0.65, or 3.3°/s) creating gastrocnemius elongation or shortening. Subjects activated a thumb switch, stopping motion once they detected onset and direction of the motion. Detection of passive movement sense (DPMS) was the angular movement before activation of a thumb‐switch. Significant differences (P=0.003) in the rate of change in DPMS across a variety of movement velocities was observed but shortening or elongation of the gastrocnemius did not affect DPMS. Gastrocnemius elongation/shortening did not affect knee DPMS, simple reaction time plays an important role in testing kinesthesia especially at faster movements. While feedback from the gastrocnemius muscle plays a limited role in healthy subjects, differences in testing velocities may incorporate higher levels of central nervous system processing. Clinical measures of kinesthesia can be affected by both movement direction and movement velocity that are speed dependent.     

Three-dimensional bone kinematics in an anterior laxity test of the ankle joint

Questions addressed in this in-vitro study are (1) what are the actual three-dimensional kinematics of talus and calcaneus during an anterior drawer test as performed with the quasi-static anterior ankle tester (QAAT) (2) does laxity measurement with the QAAT represent the true anterior translation of talus relative to the tibia?. Simultaneous measurements were made with the QAAT and a three-dimensional kinematics analysis system in five specimens. The three-dimensional translations and rotations on three axes were analysed at 25, 50 and 100 N of applied anterior load, with increased ligament damage. For four out of five remaining specimens, anterior translation values of talus and calcaneus and values as measured with the QAAT show a significant increase with growing ligament damage and with higher loads. Skeletal motions of talus and calcaneus show great similarity in three different motion axes, with increased ligament damage and at any given load. Skeletal translations and rotations of talus and calcaneus show great similarity during an anterior drawer movement of the ankle joint. Anterior skeletal translation of the talus and calcaneus show fair correlation with the anterior displacements measurements of the QAAT. These QAAT measurements show an overestimation of the laxity value by more than 200% irrespective of the load applied.     

The effect of exercise on anterior knee laxity in female basketball players.

To study the effect of physical activities on the anterior laxity of the knee joint, the anterior knee laxity of female semi-professional basketball players was measured during a typical day. The participants worked in the office in the morning, and practiced in the afternoon, which included a 60 minute warm-up, followed by a 150 minute game style practice. The laxity was measured six times in one day at different activity levels. The anterior knee laxity did not change during sedentary work in the morning, but increased significantly with game style practice. After 1 1/2 hours the increased anterior knee laxity had not recovered completely. However, after five hours it had recovered completely.     

The effect of thigh muscle activity on anterior knee laxity in the uninjured and anterior cruciate ligament-injured knee

Purpose

The main purpose of this study was to describe the nature of the relationship between hamstring muscle activity and anterior knee laxity.

Methods

This was a cross-sectional study. Anterior knee laxity was measured at 133N and manual maximal forces using the KT2000 knee arthrometer, in 8 ACL-injured and 13 uninjured individuals. Electromyographic activity of the lateral hamstrings was measured during laxity testing. Subjects contracted the hamstrings during anterior knee laxity testing at eight predetermined levels of maximal voluntary isometric contraction.

Results

Volitional contraction of the lateral hamstrings reduced anterior knee laxity logarithmically for both the 133N and manual maximal tests in both the ACL-injured and uninjured knees. A simple linear regression model, with the log of percentage of maximum lateral hamstrings activity as the sole predictor, explained approximately 70–80 % of the variation in anterior knee laxity. Both ACL-injured and uninjured subjects reduced anterior knee laxity at the same rate with increases in muscle activity. However, initial lateral hamstrings muscle activity had a greater effect on percentage anterior knee laxity scores in the ACL-injured as compared to the uninjured knee.

Conclusions

Lateral hamstrings activity reduces anterior knee laxity in a nonlinear manner, whereby the initial lower level of activation produces the greatest change in anterior knee laxity. Therefore, hamstrings muscle activity must be monitored during anterior knee laxity testing.     

DOMS-associated changes in ankle and knee joint dynamics during running

PURPOSE: The purpose of this study was to determine whether leg mechanics change due to DOMS by examining ankle and knee joint kinematics and stiffness before and after a down hill run. METHODS: Sagittal plane kinematics were recorded with high-speed (120 Hz) video at a speed representing 75% of VO2peak of nine well-trained male runners before (RE1) and 48 h after (RE2) a 30-min downhill run. From the recorded video, 10-12 consecutive strides were digitized, and the following variables were calculated for each stride: ankle and knee range of motion (ROM), ankle and knee peak angular velocity, ankle and knee stiffness, and leg vertical stiffness. A repeated measures ANOVA was calculated for each variable (alpha = 0.05). RESULTS: Both knee and ankle ROM during stance decreased with DOMS, but otherwise there were few changes in ankle mechanics with DOMS. Knee stiffness tended to increase during the early portion of stance (from initial stance to maximum angular velocity of flexion) with DOMS, immediately followed by a decrease (to maximum knee flexion) in stiffness. Changes in knee stiffness caused vertical leg stiffness to increase for the initial portion of stance with DOMS. CONCLUSION: Knee mechanics changed such that the knee stiffness increased at initial stance, resulting in an increase in vertical leg stiffness. This change in knee stiffness possibly serves as a protective mechanism to prevent further damage or pain in the knee extensor musculature.     

The effect of peroneal muscle fatigue on ankle joint position sense

ObjectivesTo analyse the effect of fatigue of the peroneal muscles on ankle joint position sense (JPS) in various angles of inversion and eversion.DesignRepeated measures design.SettingUniversity exercise laboratory.ParticipantsThirty-five subjects (male: n=10; female: n=25), age range 19–36 years with no injury to the right ankle in the past 2 years, no neurological deficits, ankle or foot orthopaedic disorders, balance disorders, or disorders of vision not correctable by glasses.Main outcome measuresJoint position sense error of active target angle before and after a fatiguing exercise programme of the peroneal muscles using an isokinetic dynamometer.ResultsFatiguing exercise of the peroneal muscles did not significantly alter JPS error at the three target angles (90° inversion: −0.3±7.6 to −2.2±7.2°; 20° inversion: 4.7±5.5 to 2.8±6.3°; 90° eversion: 0.5±3.8 to −0.2±7.2°; P<0.05).ConclusionsFatigue of the peroneal muscles did not affect ankle JPS, suggesting that either proprioception is fatigue resistant in the peroneal muscles or other structures in the ankle (e.g. ligaments, capsule) may play a significant proprioceptive role.     

Sex differences in knee joint laxity change across the female menstrual cycle

AIM: To elucidate the hormonal influences on sex differences in knee joint behavior, normal-menstruating females were compared to males on serum hormone levels and anterior knee joint laxity (displacement at 46N, 89N and 133N) and stiffness (Linear slope of deltaForce/deltaDisplacement for 46-89N and 89-133N) across the female menstrual cycle. METHODS: Twenty-two females were tested daily across one complete menstrual cycle, and 20 males were tested once per week for 4 weeks. Five days each representing the hormonal milieu for menses, the initial estrogen rise near ovulation, and the early and late luteal phases (total of 20 days) were compared to the average value obtained from males across their 4 test days. RESULTS: Sex differences in knee laxity were menstrual cycle dependent, coinciding with significant elevations in estradiol levels. Females had greater laxity than males on day 5 of menses, days 3-5 near ovulation, days 1-4 of the early luteal phase and days 1, 2, 4 and 5 of the late luteal phases. Within females, knee laxity was greater on day 5 near ovulation compared to day 3 of menses, and days 1-3 of the early luteal phase compared to all days of menses and day 1 near ovulation. On average, differences observed between sexes were greater than those within females across their cycle. There were no differences in anterior knee stiffness between sexes or within females across days of the menstrual cycle.     

Treatment of peroneal tendon dislocation and coexisting medial and lateral ligamentous laxity in the ankle joint

Purpose  

Acute dislocation of the peroneal tendon is caused by massive combined flexion-torsion trauma supported by preexisting ligamentous laxity of the ankle joint.     

Evaluation of anterior knee laxity on MRI

Purpose

Evaluation of the ACL and anterior knee laxity on MR during anterior tibial translation.

Patients and methods

Three groups were identified based on clinical and arthrometric (KT-1000) data: normal ACL (n = 12), complete tear (n = 10) and partial tear (n = 20). MRI was performed without and with anterior tibial translation (pneumatic device) with morphological and laximetric analysis: drawer tests and dynamic evaluation of ligamentous tension.

Results

Intra- and inter-observer reproducibility was excellent, correlated to arthrometric data and clinical tests (Lachman, pivot shift). The difference between the drawer signs of normal subjects and patients with ACL tear was significant for a threshold value of 1,1 mm for the anterior drawer (sensitivity: 93,33%, specificity: 91,7%) and 2,8 mm for the posterior drawer (sensitivity: 86,7%, specificity: 100%). Dynamic evaluation of ligamentous tension was also reproducible, statistically correlated to the MR drawer tests and reliable for the diagnosis of ACL lesions. In this preliminary study, the distinction between complete and partial ACL tears could not be detected.

Conclusion

Anterior cruciate ligament function can be demonstrated on MR. The predictive value of this morphological and functional association should be determined in the management of patients with partial tears.     

人工全踝关节置换术治疗踝关节骨关节炎的疗效分析

目的 观察人工全踝关节置换术治疗踝关节骨关节炎的疗效.方法 对1999年10月- 2006年10月所收治的42例患有严重踝关节骨关节炎并符合手术适应证的患者进行人工全踝关节置换术.并按照Kofoed评分标准,对患者的疼痛程度、踝关节功能、踝关节活动度进行评分;同时根据Mayo踝关节置换的评价标准对患者进行疗效评价.结果 根据Kofoed评分标准,术后患者在疼痛、功能和活动度方面都明显优于术前(P＜0.05),优良率为90％ (28/31);而根据Mayo踝关节置换的评价标准,优良率为87％ (27/31).结论 人工全踝置换术能有效缓解踝关节疼痛,改善踝关节活动度及功能,为需行踝关节融合术患者提供一种有效的方法.