Unilateral Knee Injury Research Articles

Decreased sagittal slope of the medial tibial spine and deep concavity of the lateral tibial spine are risk factors for noncontact anterior cruciate ligament injury.

This study aimed to assess the relationship between the geometric features of tibial eminence and susceptibility to noncontact anterior cruciate ligament (ACL) injuries. Patients with unilateral noncontact knee injuries between 2015 and 2021 were consecutively enroled in this study. Based on knee magnetic resonance imaging (MRI) and arthroscopic visualisation, patients were categorised into the case group (ACL rupture) and control group (ACL intact). Using MRI, the geometric features of tibial eminence were characterised by measuring the sagittal slopes, depth of concavityand coronal slopes of the inclined surfaces of the tibial spines. Univariate and multivariate logistic regressions were conducted to explore independent associations between quantified geometric indices of tibial eminence and the risk of noncontact ACL injuries. This study included 187 cases and 199 controls. A decreased sagittal slope of the medial tibial spine (MTSSS) (combined group: odds ratio [OR]: 0.87 [0.82, 0.92], p < 0.001; females: OR: 0.88 [0.80, 0.98], p = 0.020; males: OR: 0.87 [0.81, 0.93], p < 0.001) and an increased depth of concavity in the lateral tibial spine (LTSD)(combined group: OR: 1.51 [1.24, 1.85], p < 0.001; females: OR: 1.65 [1.12, 2.43], p = 0.012; males: OR: 1.44 [1.11, 1.89], p = 0.007) were independent risk factors for noncontact ACL injuries. Moreover, a steeper coronal slope of the inclined surface of the medial tibial spine was a significant predictor of noncontact ACL injuries for males (MTSCS: OR: 1.04 [1.01, 1.08], p = 0.015) but not for females. Geometric features of tibial eminence, particularly a decreased MTSSS and an increased LTSD, were identified as independent risk factors for noncontact ACL injuries. These findings will help clinicians identify individuals at high risk of ACL injury and facilitate the development of targeted prevention strategies. Level III.

Role of MRI to Determine Impact on Contralateral ACL/Meniscal Damage Secondary to Unilateral Traumatic Knee Injury in Adults

Background: Knee injuries are one of the most common sports injuries and may cause chronic functional impairment. During a study in emergency department approximately 50% of injuries are caused by sports activities, with majority of the cases comprising of knee soft tissue injuries. The most common modality to diagnose musculoskeletal injury is magnetic resonance imaging nowadays. Knee injuries are one of the most frequently overlooked injuries and cause long term functional impairment. MRI provides the most effective and comprehensive imaging assessment of the knee joint and adjacent structures. Objective: To determine the significance of Magnetic resonance imaging (MRI) of contralateral uninjured knee in suspected meniscal/ACL injury of traumatic patients. Study Design: Prospective study. Settings: Radiology Department of Jinnah Postgraduate Medical Center (JPMC), Karachi Pakistan. Duration: January 2018 to December 2021. Methods: Patients aged 18 years or older who presented with a unilateral traumatic knee injury requiring medical evaluation and treatment and who underwent MRI evaluations for both the injured knee (ipsilateral) and the contralateral knee (opposite side) as part of their medical assessment were included. After taking informed consent, all patients underwent magnetic resonance imaging (MRI) examinations of both their affected (ipsilateral) and non-affected (contralateral) knee joints. These MRI findings were subjected to rigorous statistical analysis, which included comparisons between the affected and non-affected knees. Self-made proforma was used for the data collection. Results: According to our inclusion criteria, we identified 45 patients to participate in the study. Amongst these 82% of the patients were male and 17% were females, ratio between the male and female is 4.6:1. Mean age of the participants was found to be 38.64±14.4 years. Upon analysis, 62.2% of the patients had meniscal injury associated with ACL/PCL damage. While MRI findings were compared with contralateral normal side and found meniscal injury in 17(37.8%) cases, followed ACL/PCL injury 7(15.6%) and ACL/PCL injury associated meniscal injury ± effusion 7(15.6%) was (p = 0.004). Conclusion: MRI has proven to be a valuable imaging modality for identifying ligament tears and meniscal injuries of the knee joint in patients suspected of having meniscal/ACL injuries due to trauma. It not only assists in diagnosis but also provides valuable insights into the complexity of knee trauma.

Bioimpedance Measurement of Knee Injuries Using Bipolar Electrode Configuration.

Currently, there is no suitable solution for the point-of-care diagnosis of knee injuries. A potential portable and low-cost technique for accessing and monitoring knee injuries is bioimpedance measurement. This study validated the feasibility of the bipolar electrode configuration for knee bioimpedance measurement with two electrodes placed on a fixed pair of knee acupuncture locations called Xiyan. Then, the study collected 76 valid samples to investigate the relationship between bioimpedance and knee injuries, among whom 39 patients have unilateral knee injuries, and 37 individuals have healthy knees. The self-contrast results indicated that knee injuries caused a reduction of bioimpedance of the knee by about 5% on average, which was detectable at around 100 kHz (p ≈ 0.001). Furthermore, the results analyzed by principal component analysis and support vector machines show that the detection sensitivity can reach 87.18% using the leave-one-out cross-validation. We also proposed a low-cost and portable bioimpedance measurement device that meets the needs for measuring knee joint bioimpedance.

UDP-glucose dehydrogenase (UGDH) activity is suppressed by peroxide and promoted by PDGF in fibroblast-like synoviocytes: Evidence of a redox control mechanism.

UDP-glucose dehydrogenase (UGDH) generates essential precursors of hyaluronic acid (HA) synthesis, however mechanisms regulating its activity are unclear. We used enzyme histostaining and quantitative image analysis to test whether cytokines that stimulate HA synthesis upregulate UGDH activity. Fibroblast-like synoviocytes (FLS, from N = 6 human donors with knee pain) were cultured, freeze-thawed, and incubated for 1 hour with UDP-glucose, NAD+ and nitroblue tetrazolium (NBT) which allows UGDH to generate NADH, and NADH to reduce NBT to a blue stain. Compared to serum-free medium, FLS treated with PDGF showed 3-fold higher UGDH activity and 6-fold higher HA release, but IL-1beta/TGF-beta1 induced 27-fold higher HA release without enhancing UGDH activity. In selected proliferating cells, UGDH activity was lost in the cytosol, but preserved in the nucleus. Cell-free assays led us to discover that diaphorase, a cytosolic enzyme, or glutathione reductase, a nuclear enzyme, was necessary and sufficient for NADH to reduce NBT to a blue formazan dye in a 1-hour timeframe. Primary synovial fibroblasts and transformed A549 fibroblasts showed constitutive diaphorase/GR staining activity that varied according to supplied NADH levels, with relatively stronger UGDH and diaphorase activity in A549 cells. Unilateral knee injury in New Zealand White rabbits (N = 3) stimulated a coordinated increase in synovial membrane UGDH and diaphorase activity, but higher synovial fluid HA in only 2 out of 3 injured joints. UGDH activity (but not diaphorase) was abolished by N-ethyl maleimide, and inhibited by peroxide or UDP-xylose. Our results do not support the hypothesis that UGDH is a rate-liming enzyme for HA synthesis under catabolic inflammatory conditions that can oxidize and inactivate the UGDH active site cysteine. Our novel data suggest a model where UGDH activity is controlled by a redox switch, where intracellular peroxide inactivates, and high glutathione and diaphorase promote UGDH activity by maintaining the active site cysteine in a reduced state, and by recycling NAD+ from NADH.

Reactive Strength as a Metric for Informing Return-to-Sport Decisions: A Case-Control Study.

Current return-to-sport decisions are primarily based on elapsed time since surgery or injury and strength measures. Given data that show rates of successful return to competitive sport at around 55%, there is strong rationale for adopting tools that will better inform return to sport decisions. The authors' objective was to assess reactive strength as a metric for informing return-to-sport decisions. Case-control design. Fifteen elite athletes from national sports teams (23 [6.0]y) in the final phase of their return-to-sport protocol following a unilateral knee injury and 16 age-matched control athletes (22 [4.6]y) performed a unilateral isometric strength test and 24-cm drop jump test. Pairwise comparisons were used to determine differences between legs within groups and differences in interleg asymmetry between groups. Strength measures did not distinguish the control from the rehabilitation group; however, clear differences in the degree of asymmetry were apparent between the control and rehabilitation groups for contact time (Cohen d = 0.56; -0.14 to 1.27; 8.2%; P = .113), flight time (d = 1.10; 0.44 to 1.76; 16.0%; P = .002), and reactive strength index (d = 1.27; 0.50 to 2.04; 22.4%; P = .002). Reactive strength data provide insight into functional deficits that persist into the final phase of a return-to-sport protocol. The authors' findings support the use of dynamic assessment tools to inform return-to-sport decisions to limit potential for reinjury.

Instrumented triple single-leg hop test: A validated method for ambulatory measurement of ankle and knee angles using inertial sensors

BackgroundHop tests are commonly used in clinical environments to measure function after sport-related knee injuries. Joint angle measurement during hopping is feasible in research-based environments equipped with motion-capture systems. Employing these systems in clinical research settings is inefficient, given the associated cost, preparation time, and expertise required to administer and interpret the findings. Therefore, this study aimed to introduce a wearable system comprising three inertial measurement units for 3D joint angular measurement during horizontal hop tests, validate the joint angles against a camera-based system, and evaluate its applicability in clinical research environments. MethodsTen able-bodied participants were outfitted with three inertial measurement units during triple single-leg hop trials. 3D knee and ankle angles were calculated using the strap-down integration method, and results were compared with camera-based joint angles. Additionally, knee and ankle range of motions (RoMs) during bilateral triple single-leg hop trials were compared for 22 participants with unilateral sport-related knee injuries and 10 uninjured participants. FindingsEstimated angles had root-mean-square and RoM error medians of less than 2.3 and 3.2 degrees for both joints, and correlation coefficients of above 0.92 when compared with the camera-based system, for all hop phases. Injured participants had smaller sagittal ankle RoM (P = .008) on their injured side, during the third hop. Concurrently, they demonstrated smaller knee RoM symmetry indices (P = .017) and injured knee sagittal RoMs (P = .009) compared to uninjured participants. InterpretationThe introduced system had appropriate accuracy to highlight post-injury modifications in hopping kinematics and reveal noteworthy differences in RoM of clinical samples.

Correlation between ACL injury and involvement of the anterolateral ligament: A retrospective study

Background: Clinical testing has demonstrated the role of the anterolateral ligament (ALL) in controlling anterolateral laxity and knee instability at high angles of flexion. Few studies have discussed the association between an anterior cruciate ligament (ACL) injury and ALL injury, specifically after residual internal rotation and a post-ACL reconstruction positive pivot-shift that could be attributed to ALL injury. The goal of this study was to assess the correlation between ALL injury and ALL injury with concomitant ACL injury using MRI. Material and Methods: This was a retrospective study of 246 patients with unilateral ACL knee injuries from a database that was reexamined to identify whether ALL injuries occurred in association with ACL injuries. We excluded the postoperative reconstructed cases. The charts were reviewed on the basis of the presence or absence of diagnosed ACL injury with no regard for age or sex. Results: Of the 246 patients with ACL injury, there were 165 (67.1%) patients with complete tears, 55 (22.4%) with partial tears, and 26 (10.6%) with sprains. There were 176 (71.5%) patients with ALL and associated ACL injuries, whereas 70 (28.5%) did not have associated ACL injuries. There was a significant statistical relationship between ACL and ALL injuries (P&lt;0.0001). Conclusions: There is high incidence of ALL tears associated with ACL injuries. Clinicians should be aware of this injury and consider the possibility of simultaneous ALL and ACL repair to prevent further knee instability. Level of Evidence: Level IV.

Effects of knee pain on postural control excluding the musculature of the craniomandibular system

Knee pain can influence postural control in addition to changes in the anatomical structure of the knee joints. Because the influence of imbalances in the craniomandibular system has been proven multiple times, it is the aim of the present work to investigate the influence of various knee diagnoses on postural control excluding occlusal information by means of symmetrical packing using cotton rolls. One hundred and fifteen patients (74male/41female) aged 18-75years with an average BMI of 25.13 ± 3.66 kg/m2 took part in the study, among them 34patients (26male/8female) with cruciate ligament injury, 26(16male/10female) with meniscal lesions, 24(13male/11female) with arthrosis, 21(11male/10female) with patellar pain, and 10(8male/2female) with other painful knee complaints. Postural control was increased using a force platform, the degree of severity of the disorder was recorded using the "Knee Injury and Osteoarthritis Outcome" questionnaire, and the occlusion packed on both sides with cotton rolls in the premolar area. With increasing age, patients with knee arthrosis are more likely to stand on the hindfoot. In those with patellar disorder, increased weight-bearing on the forefoot correlates with increasing BMI. An increase in weight-bearing on the forefoot on the side of the uninjured knee in people with patellar disorder results not only in a reduction in quality of life but also level of daily activity. The percentage weight-bearing on the zones of the feet differs in unilateral knee injuries (in particular, comparison of the side with the knee injury and the uninjured side). Age, BMI or gender are influencing factors. Because various correlations and/or effects in the subgroups of knee injuries are generated, an injury-specific analysis should be carried out. These effects are also identifiable in the subjective assessment of quality of life.

Isokinetic moment curve abnormalities are associated with articular knee lesions.

The aim of this study was to test whether lesions of the medial meniscus (MM) and of the anterior cruciate ligament (ACL) are associated with specific abnormalities of isokinetic moment curves (IMCs). Fifty-four young adults (20 active healthy people, and 34 patients with unilateral knee injuries) were assessed through knee extensor and flexor isokinetic tests at 60°/s. Qualitative IMC analysis was performed using a novel classification system which identified three distinct abnormal shapes. The chi-squared (χ2) test was used to determine the inter-individual and intra-individual differences between the groups. Quantitative IMC inter-group comparisons were performed by a one-way analysis of variance (ANOVA). Knees with MM and ACL lesions were consistently associated with IMC shape irregularities (p<0.001) and with abnormal quantitative scores (p<0.001). More specifically, knees with isolated ACL lesions and knees with combined ACL and MM lesions presented similar distribution of knee extensor and flexor IMC irregularities, which was not present in knees with isolated MM lesions. A possible association between specific knee pathologies and IMC irregularities was identified (all p<0.05). In conclusion, different knee pathologies may be associated with different qualitative IMCs, which could be used as an additional presentation tool in clinical settings.

Acoustical Emission Analysis by Unsupervised Graph Mining: A Novel Biomarker of Knee Health Status.

To study knee acoustical emission patterns in subjects with acute knee injury immediately following injury and several months after surgery and rehabilitation. We employed an unsupervised graph mining algorithm to visualize heterogeneity of the high-dimensional acoustical emission data, and then to derive a quantitative metric capturing this heterogeneity-the graph community factor (GCF). A total of 42 subjects participated in the studies. Measurements were taken once each from 33 healthy subjects with no known previous knee injury, and twice each from 9 subjects with unilateral knee injury: first, within seven days of the injury, and second, 4-6 months after surgery when the subjects were determined to start functional activities. Acoustical signals were processed to extract time and frequency domain features from multiple time windows of the recordings from both knees, and k-nearest neighbor graphs were then constructed based on these features. The GCF calculated from these graphs was found to be 18.5 ± 3.5 for healthy subjects, 24.8 ± 4.4 (p = 0.01) for recently injured, and 16.5 ± 4.7 (p = 0.01) at 4-6 months recovery from surgery. The objective GCF scores changes were consistent with a medical professional's subjective evaluations and subjective functional scores of knee recovery. Unsupervised graph mining to extract GCF from knee acoustical emissions provides a novel, objective, and quantitative biomarker of knee injury and recovery that can be incorporated with a wearable joint health system for use outside of clinical settings, and austere/under resourced conditions, to aid treatment/therapy.

Hip Adductors are Stronger in Persons with Bilateral Compared to Unilateral Knee Injury

Hip Adductors are Stronger in Persons with Bilateral Compared to Unilateral Knee Injury

Validity and reliability of a novel instrumented one-legged hop test in patients with knee injuries

BackgroundConventional one-legged hop tests simply evaluate the total hop distance, thus neglecting important temporal and spatial parameters related to the strategy of execution, such as foot contact time. AimTo examine the validity and reliability of an instrumented one-legged hop test, the “four hops, three contacts” (4H3C) test, in patients with knee injuries. MethodsThe 4H3C test consists of four consecutive one-legged hops, of which individual hop distance and foot contact time are recorded by a validated floor-based photocell system. We examined the test–retest reliability, discriminant validity (involved vs. uninvolved side) and convergent validity (relation with maximal voluntary strength) of consecutive hop distance and foot contact time parameters in 50 patients with unilateral knee injuries. ResultsTest–retest reliability was very high for hop distance (intraclass correlation coefficients: 0.91 to 0.97) and high for contact time variables (intraclass correlation coefficients: 0.75 to 0.88). The difference between the involved and the uninvolved side was significant for all hop distance and contact time parameters (p<0.05). Maximal voluntary strength was correlated to both hop distance (r=0.67; p<0.001) and contact time (r=−0.42; p<0.01) variables. ConclusionThe 4H3C is a valid and reliable test for the evaluation of single hops in patients with knee injuries and may be useful in sport and clinical settings. The interpretation of foot contact time data requires however some caution.

A Robust System for Longitudinal Knee Joint Edema and Blood Flow Assessment Based on Vector Bioimpedance Measurements.

We present a robust vector bioimpedance measurement system for longitudinal knee joint health assessment, capable of acquiring high resolution static (slowly varying over the course of hours to days) and dynamic (rapidly varying on the order of milli-seconds) bioresistance and bioreactance signals. Occupying an area of 78×90 mm(2) and consuming 0.25 W when supplied with ±5 V, the front-end achieves a dynamic range of 345 Ω and noise floor of 0.018 mΩrms (resistive) and 0.055 mΩrms (reactive) within a bandwidth of 0.1-20 Hz. A microcontroller allows real-time calibration to minimize errors due to environmental variability (e.g., temperature) that can be experienced outside of lab environments, and enables data storage on a micro secure digital card. The acquired signals are then processed using customized physiology-driven algorithms to extract musculoskeletal (edema) and cardiovascular (local blood volume pulse) features from the knee joint. In a feasibility study, we found statistically significant differences between the injured and contralateral static knee impedance measures for two subjects with recent unilateral knee injury compared to seven controls. Specifically, the impedance was lower for the injured knees, supporting the physiological expectations for increased edema and damaged cell membranes. In a second feasibility study, we demonstrate the sensitivity of the dynamic impedance measures with a cold-pressor test, with a 20 mΩ decrease in the pulsatile resistance associated with increased downstream peripheral vascular resistance. The proposed system will serve as a foundation for future efforts aimed at quantifying joint health status continuously during normal daily life.

Use of dual-energy CT and virtual non-calcium techniques to evaluate post-traumatic bone bruises in knees in the subacute setting.

The purpose of this study was to determine the ability of dual-energy computed tomography (DECT) and virtual non-calcium (VNCa) imaging to detect magnetic resonance imaging (MRI)-demonstrated bone bruises several weeks after unilateral knee injury. Patients with unilateral knee injury and MRI-confirmed bone bruises who had undergone a DECT scan of both knees were retrospectively identified. Two radiologists evaluated VNCa images for bruises in four regions per knee without knowing the MRI results. The mean CT numbers were calculated for the lesion-positive and lesion-negative regions of the injured knee, and the contralateral knee. Fourteen patients with a total of 36 regions positive for bone bruises on MRI were identified. The median delay between injury and DECT was 37days (range, 11-99 days). The mean CT numbers in VNCa images for lesion-positive and lesion-negative regions were -7.6 ± 24.9 HU and -58.2 ± 19.5 HU, respectively. There were no significant differences in mean CT number between the lesion-negative regions in the injured knee and the contralateral knee. No resolution of bruising was seen before week 5, and bone bruising was still identifiable in one out of the two patients scanned at 10weeks following injury. DECT and VNCa images can identify bone bruising for at least 10weeks after injury.

The Effects of Disinhibitory Transcutaneous Electrical Nerve Stimulation on Contralateral Quadriceps Activation in Osteoarthritic Patients

Bilateral quadriceps activation failure has been reported following unilateral knee injuries, suggesting that muscle inhibition may be modulated by central nervous system processes. Transcutaneous electrical nerve stimulation (TENS) applied to the injured knee has been reported to disinhibit ipsilateral quadriceps of patients with tibiofemoral osteoarthritis (TFOA), yet no data exists regarding how the contralateral or uninjured quadriceps are affected. PURPOSE: To determine the effects of disinhibitory TENS and therapeutic exercise applied to the injured knee on the uninjured quadriceps central activation ratio (CAR). METHODS: Thirty-six participants with TFOA were stratified by Kellgren-Lawrence Score and baseline CAR, and randomized into 3 groups (control: 5M, 7F; 58.3 ± 11.8yrs, 28.6± 5.6 BMI,), placebo TENS (4M, 8F; 60.3 ± 12.9yrs, 29.5±9.8 BMI) and TENS groups (6 M,6F; 61 ± 10.9yrs, 28.6± 4.8 BMI). The involved leg was determined as the knee that had the most radiographic evidence of TFOA. All groups participated in 12 supervised, unilateral lower extremity exercise sessions over 4 weeks. TENS and placebo TENS groups wore the intervention on the injured leg during all exercise sessions and for at least 8 hours daily for 4 weeks. Quadriceps CAR was tested on the uninvolved quadriceps prior to the intervention and at 2 and 4 weeks following baseline. A 3x3 repeated measures ANOVA was used to detect differences in CAR and standardized effect sizes calculated to assess effect magnitude. RESULTS: No significant differences were found in CAR score between groups at baseline (TENS 86±10, placebo 84±15, control 84±12), 2 weeks (93±4, 84±13, 86±11) or 4 weeks (94±.07, 82±16, 81±17), yet strong to moderate effect sizes were found at 2 weeks (d =.92; 95% confidence interval.05, 1.73) and 4 weeks (.58; -.26, 1.37) in the TENS group. Weak effect sizes were calculated for both the placebo (0; -.8, 8: -.13; -.93,.68) and the control group (.17; -.63,.97: -.2; -1,.61) at 2 and 4 weeks, respectively. CONCLUSION: Although there were no statistically significant differences between groups in the uninvolved leg following 4 weeks of disinhibitory TENS treatment, effect sizes were strong, suggesting a clinically significant increase in uninvolved quadriceps CAR.

Pharmacological modulation of movement-evoked pain in a rat model of osteoarthritis

This study was conducted to characterize movement-induced pain in a rat model of knee joint osteoarthritis and validate this behavioral assessment by evaluating the effects of clinically used analgesic compounds. Unilateral intra-articular administration of a chondrocyte glycolytic inhibitor monoiodoacetate, was used to induce knee joint osteoarthritis in Sprague–Dawley rats. In this osteoarthritis model, histologically erosive disintegration of the articular surfaces of the ipsilateral joint are observed which closely mimic the clinical picture of osteoarthritis. Movement-induced pain behavior was measured using hind limb compressive grip force evaluation. The animals exhibited pain behaviors epitomized by a long-lasting decrement in bilateral compressive hind limb grip force following unilateral knee injury. The effects of clinically used reference analgesics were evaluated 20 days following i.a. injection of monoiodoacetate. Full analgesic activity was observed for tramadol, celecoxib and diclofenac; moderate effects for indomethacin, duloxetine and gabapentin but weak or no effects for acetaminophen, ibuprofen and lamotrigine. As morphine reduced grip force in naïve rats, its analgesic effects could not be accurately evaluated in this model. Finally, the effects of celecoxib were maintained following chronic dosing. The results indicate that this in vivo model utilizing a movement-induced pain behavior spawned by knee joint osteoarthritis may provide a valuable tool in examining the role of potential analgesic targets in osteoarthritic pain. As the model is clinically relevant, it will further enhance the mechanistic understanding of chronic arthritic joint pain and help in developing newer and better therapeutic strategies to manage osteoarthritis pain.

Comparison of conventional resistance training and the fly-wheel ergometer for training the quadriceps muscle group in patients with unilateral knee injury

A fly-wheel ergometer (FWE) offering resistance training of the knee extensors has been designed for space travel and found to be effective during bed rest. The possibility exists that this device is also effective in training the knee extensors after knee injury. The purpose of this study was to compare the FWE to standard knee extensor training equipment for their effects on individuals with a history of knee injury, a group who commonly suffer from weakness of the knee extensors that effects their function. Twenty-nine subjects completed the study, which included tests of knee self-assessment, knee extensor static and dynamic muscle strength, size and neural activation as well as single leg power output, standing balance and vertical jump performance. Both groups showed statistically significant (P < 0.05) improvements in these variables over the 3-month training period but no differences were noted between the groups. The FWE appears to be as effective as standard resistance training equipment for improving knee extensor muscle group size and performance after knee injury.

Do knee injuries have long-term consequences for isometric and dynamic muscle strength?

To ascertain whether decrements in knee extensor muscle strength persist years after a traumatic ligamentous or meniscal knee injury, with reference to (1) the type of muscle activity, (2) the dominance of injury, and (3) the time since injury, 36 subjects with previous unilateral knee injuries were assessed. Peak voluntary quadriceps muscle strength was measured using the KinCom 500H dynamometer during isometric, concentric (30 degrees.s-1 and 120 degrees.s-1) and eccentric contractions (30.s-1), and the findings for each type of contraction were compared. Significant differences in quadriceps muscle strength were seen between (1) the injured and uninjured limbs during maximal voluntary isometric (P = 0.0003), concentric (P < 0.0001) and eccentric (P < 0.0001) contractions, and (2) the isometric and concentric decrements (P = 0.004), and the isometric and eccentric decrements (P = 0.012) within the same injured limb. The decrements in eccentric strength were significantly greater if they affected the dominant rather than the non-dominant limb (P = 0.0186). No relationship was seen between the time since injury and the degree of isometric or dynamic decrement. Deficits in quadriceps muscle strength remained for a long time after traumatic knee injury, with exercise levels rarely returning to the previously uninjured state. The degree of decrement in muscle strength was dependent upon the type of muscle activity, with concentric and eccentric activity showing greater decrements than those seen with isometric activity. Deficits in the type of activity varied widely in the same individual, and eccentric decrements were significantly worse following dominant knee injuries. Possible explanations for these findings and the implications for rehabilitation following knee injury are discussed.

Bucket-handle tears of the meniscus: appearance at CT.

Before undergoing arthroscopy, 222 patients with acute, unilateral knee injuries and strong clinical evidence of a meniscal tear underwent axial computed tomography (CT) of the knee. In 53 patients, a bucket-handle meniscal tear was found, and it was repaired at arthroscopy. In 92.5% (49 of 53) of these knees, CT accurately depicted the type, location, and extent of the tear. CT also demonstrated the displaced meniscal fragment with its relationship to the attached remnant.

Measurement of quadriceps muscle wasting by ultrasonography.

Grey-scale ultrasonography can produce an image of the quadriceps muscle from which it is possible to measure its cross-sectional area (CSA). The between-days coefficient of variation for quadriceps CSA (at mid-thigh) in 14 legs of seven subjects each scanned on four days was reduced to 4.0% by averaging four scans on each day. Bilateral scans (at the mid-thigh level) were used to measure the severity of quadriceps wasting in 21 otherwise healthy adult patients with a difference in thigh circumference following unilateral knee immobilization or injury. Quadriceps wasting as demonstrated by the scans was consistently more severe than the disparity in whole thigh cross-sectional area at the same level or the disparity in anthropometric estimates of fat-free thigh volume. Investigations concerned with changes in quadriceps muscle bulk must therefore use a technique (such as ultrasonography) which allows measurement of the quadriceps itself.