Different Degrees Of Flexion Research Articles

Measured distance from posterior tibia to popliteal artery increases with flexion and subluxation of the knee.

Popliteal artery laceration is a devastating complication in total knee arthroplasty (TKA). Its anatomic position relative to the tibia has been studied using ultrasound or magnetic resonance imaging. This is the first study performed in a laboratory using radiographic measurements to determine if increased flexion and subluxation of the knee increase the distance between the tibia and popliteal artery. The femoral artery was infused with radiopaque dye in six cadavers. The knee was placed in two different degrees of flexion and three of subluxation. The radiographic distance between standardized markers in the posterior tibia and popliteal artery was measured. The average distance from the tibial peg to the popliteal artery at 90° of flexion increased from 0% to 50% to 100% subluxation. The increase was statistically significant (Friedman test p = 0.016). The contrast between neutral and 100% subluxation was statistically significant (Sign test p = 0.031). At 115° flexion, average distance from the peg to popliteal artery significantly increased as subluxation increased (Friedman test p = 0.05). In three specimens, at 115° of flexion and 100% subluxation, a line perpendicular to the axis of the tibia, failed to intersect the popliteal artery. The measured distance increased from 90° to 115° of flexion at a given degree of subluxation, but this difference did not reach statistical significance. Increasing flexion and subluxation of the tibia results in increasing distance between the cut plane of the tibial plateau and popliteal artery and decreases risk of laceration. Not applicable.

Description of the Anterior Cruciate Ligament Reconstruction Technique with Mini-Lemaire Type Anterolateral Tenodesis through a Single Femoral Tunnel.

The anterior cruciate ligament (ACL) injury causes anteroposterior and rotational instability in the knee. Intra-articular reconstructions often fail to achieve satisfactory rotational control, leading to persistent complaints of instability and subjecting the neo-ligament to increased stress. Young patients with high athletic demands and grade 2 or 3 pivot-shift often have a higher risk of re-rupture after isolated ACL reconstruction. Over the years, various techniques have been developed to address such situations. Among the described techniques, one of the most commonly used is the modified or "mini-Lemaire" lateral extra-articular tenodesis. Biomechanical studies demonstrate the versatility of the technique due to its relatively isometric behavior in flexion angles of 0-60° when the graft is introduced deeply to the lateral collateral ligament. It offers the possibility of fixation at different anatomical positions on the lateral femoral condyle and at different degrees of flexion. The objective of this study is to describe an accessible, reproducible technique that relies on materials widely available in our environment.

MRI sequences at different degrees of flexion to investigate knee popping: an unusual way to diagnose an isolated pigmented villonodular synovitis lesion.

Knee popping is a frequent symptom among knee disorders which requires further investigation in case of a recent evolution of the symptom or pathological associated ones. This article reports a rare presentation of pigmented villonodular synovitis (PVNS), identified as the cause of knee popping symptoms, by performing MRI sequences at various degrees of knee flexion for a patient complaining from a gradual onset of knee popping, occurring when bending the knee over 120° of flexion. MRI sequences were performed just before the popping occurs (flexion 90°) and right after it had occurred (flexion 120°). The latter confirmed the origin of the symptom as the lesion moved forward, passing brutally through the interstice between the PCL and the ACL at 120° of flexion, explaining the popping. Treatment decision was to perform an arthroscopic resection of the lesion. Diagnosis of isolated PVNS was confirmed after anatomopathological analysis.

Transosseous Fixation with Suspensory Fixation System on Medial Meniscus Root Tears

Medial meniscal root injury is known to cause an increase in the tibiofemoral contact pressure and results in early osteoarthritis. Several techniques have been described for transosseous suture repair. Typically, the sutures are passed through the meniscus, pulled out through a transtibial tunnel, and tied over a bone bridge, a suture button, or a screw at the anterior tibial cortex. Desired meniscus root tension may not be achieved in transosseous fixation with a suture button. The suspensory fixation technique is aimed to prevent secondary looseness in the knot attached to the button implant in the tibia and to provide the desired tension in the fixation of the button implant in different degrees of flexion of the knee.

Location of the radial nerve along the humeral shaft between the prone and lateral decubitus positions at different elbow positions

Identification of the radial nerve is important during the posterior approach to a humerus fracture. During this procedure, the patient can be placed in the prone or lateral decubitus position depending on the surgeon’s preference. The distance from the radial nerve to the osseous structures will be different in each position. The purpose of this study was to identify the safety zones in various patient and elbow flexion positions. The distances from the olecranon to the center of the radial groove and intermuscular septum and lateral epicondyle to the lateral intermuscular septum were measured using a digital Vernier caliper. The measurements were performed with cadavers in the lateral decubitus and prone positions at different elbow flexion angles. The distance from where the radial nerve crossed the posterior aspect of the humerus measured from the upper part of the olecranon to the center of the radial nerve in both positions at different elbow flexion angles varied from a mean maximum distance of 130.00 mm with the elbow in full extension in the prone position to a minimum distance of 121.01 mm with the elbow in flexion at 120° in the lateral decubitus position. The mean distance of the radial nerve from the upper olecranon to the lateral intermuscular septum varied from 107.13 to 102.22 mm. The distance from the lateral epicondyle to the lateral edge of the radial nerve varied from 119.92 to 125.38 mm. There was not significant contrast in the position of the radial nerve with osseous landmarks concerning different degrees of flexion, except for 120°, which is not significant, as this flexion angle is rarely used.

Biomechanical analysis of distraction forces on the posterior meniscal roots to optimize early rehabilitation protocols

Introduction:The aim of this study was to investigate the distraction forces of the medial and lateral posterior meniscal roots after repair (PMMR, PLMR) at different degrees of flexion and axial load.Hypotheses:It was hypothesized that with increasing axial load and flexion angle, the distraction forces on the meniscal roots increase continuously.Methods:Eight fresh-frozen human cadaveric knees were axially loaded in a custom made kinematics rigs with 0 N, 200 N and 400 N throughout a continuous flexion-extension cycle (0°-90°). The distraction forces acting on the PMMR and PLMR were determined in three scenarios: 1) native knee joint, 2) after bilateral detachment of the posterior meniscal roots and following root repair, 3) after resection of the anterior cruciate ligament (ACL). To measure the distraction forces, the FiberWire No. 2 (Arthrex, Inc.) sutures used for the root repairs were shuttled transtibially through a 2.4 mm bone tunnel and tied over a force sensor mounted on the anterior tibia with a pretension of 2 N.Statistical analysis was performed using a repeated- measures ANOVA with a post-hoc Bonferroni correction (p < 0.05).Results:Overall, the different investigated knee states as well as the degree of flexion showed a significant effect on the distraction forces on the posterior meniscal roots (p <0.01). An axial load of 200 N and 400 N resulted in a significant increase of the distraction forces on both menisci over the entire range of motion compared to an unloaded state (p < 0.01).When no axial load was applied, the distraction forces after PMMR and PLMR refixation were not significantly affected by the degree of flexion (p > 0.05). With axial loading of 200 N and 400 N, the distraction forces on the PLMR were significantly higher at flexion angles between 15° and 90° compared to full extension (p <0.01). In contrast, the distraction forces on the PMMR were highest close to extension (0° -30°) and decreased significantly towards 90° of flexion when the knees were loaded with 200 N and 400 N (p <0.01).When the ACL was removed, a significant increase of the distraction forces at the posterior meniscal roots was observed (p < 0.001).Conclusion:Axial loading significantly increases the distraction forces after posterior meniscal root repair. Therefore, axial loading should be avoided in the early postoperative phase. Furthermore, data of this study shows that passive exercise between 0° and 90° flexion can be performed without significantly affecting the forces acting on the menisci.

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OBJECTIVES/SPECIFIC AIMS: Upper-extremity (UE) impairment affects 88% of stroke survivors due to dysfunctional shoulder-hand coordination. Patients may be able to grasp with the arm at rest, but unable to grasp in a functional context (eg, from a high shelf) because shoulder use elicits involuntary hand muscle activity. Further, much rehabilitation research is directed at unsuccessful stroke recovery (patients with persistent UE impairment) but very little towards patients who show successful clinical recovery (such as those with mild UE impairment) even though these patients have attained the desired rehabilitation outcome. We examined the neurophysiological trajectory of successful compared to unsuccessful post-stroke recovery in the context of functional UE movements to clearly identify what factors are necessary for successful recovery of functional UE movements after stroke. METHODS/STUDY POPULATION: We studied 3 populations: (1) mildly-impaired patients, early (at &lt;17 d, 30 d, 90 d, and 180 d) after stroke as a model of successful post-stroke recovery, (2) moderately-impaired, chronic patients (&gt;6-months post stroke) with persistent hand function impairment, as a model of incomplete post-stroke recovery (unsuccessful recovery), and (3) Healthy age-range matched controls. We used transcranial magnetic stimulation (TMS) in all 3 groups at the given time points to measure corticomotor excitability (motor evoked potentials, recruitment curve), corticomotor inhibition (short-interval intracortical inhibition, long-interval intracortical inhibition), and intracortical facilitation of hand muscles with the shoulder positioned in different degrees of flexion or abduction (these shoulder positions are known to elicit involuntary, undesired hand muscle activation, which leads to UE dysfunction and impairment in individuals with stroke). RESULTS/ANTICIPATED RESULTS: Data collection are in process and will be presented. Preliminary data from controls shows that corticomotor excitability of selected hand muscles is affected by changes in shoulder position. Preliminary findings in controls are consistent with clinical findings in stroke that certain shoulder positions elicit involuntary and undesired hand muscle activation, leading to UE dysfunction and disability. Findings from the stroke groups will be presented. DISCUSSION/SIGNIFICANCE OF IMPACT: We hypothesize that this centrally-facilitated coupling between shoulder and hand muscles is disrupted after stroke, which may play a central role in the inability of patients to perform functional UE movements. By comparing the TMS metrics in mildly-impaired Versus moderately-impaired chronic patients, we will be able to identify the longitudinal change in neurophysiology underlying shoulder-hand coordination that is associated with successful or unsuccessful clinical recovery of UE function after stroke. Thus, these findings will help us distinguish between the neurophysiology underlying successful from unsuccessful UE recovery leading to more mechanism-based interventions for UE dysfunction post stroke in the future.

Hamstring Autograft for Foot and Ankle Applications

Category: Ankle, Sports Introduction/Purpose: Hamstring tendon autografts (gracilis and/or semitendinosus) may be used as an alternative to allograft or local tendon grafts in foot and ankle surgery, primarily for tendon or ligament repairs in which direct repair has failed or is not possible. Advantages of hamstring autografts include avoiding the expense and lower healing potential of allografts, as well as the morbidity associated with local tendon grafts. While hamstring harvest has been abundantly studied in the setting of concomitant knee surgeries, few authors have investigated its effects when used specifically for foot and ankle applications. We studied a cohort of patients who underwent hamstring harvest for foot and ankle applications, hypothesizing that morbidity to the knee would be limited and foot and ankle outcome scores would be good. Methods: All patients who underwent hamstring autograft for foot or ankle applications by a fellowship-trained sports surgeon since 2011 were screened for inclusion. Patients were eligible if they were over the age of 18, had no history of knee pathology, and were at least one year from surgery. 23 patients were enrolled an average of 23 months post-operatively (range, 12-59 months). The average age was 51 ± 18 (range, 18-77) and 50% were women. Isokinetic testing was performed using a Biodex dynamometer, with the administering physical therapist blinded to side of surgery. Peak flexion and extension torque as well as flexion and extension torque at 30, 70, and 90 degrees of flexion were collected at two different testing speeds, 180 and 300 degrees/second. Pre- and post-operative questionnaire scores—the Foot and Ankle Outcome Score (FAOS) and Short Form (SF)- 12—were retrospectively reviewed. T-tests were used for all comparisons. Results: Of the 23 patients enrolled, gracilis was harvested in 14, semitendinosus in six, and both tendons in three to reconstruct the lateral ankle ligaments (eight patients), tibialis anterior (six), Achilles (five), and peroneus brevis (four). At follow-up, 19 patients (83%) reported no pain at the harvest site; the remaining four patients reported mild to moderate symptoms. There were no significant differences between relative flexion strength at different degrees of flexion or between relative flexion and extension strength, with strength considered as a percentage of that of the non-operated leg (Table). All five FAOS subscales and the SF-12 physical component subscale improved significantly (p=0.01 for all). No patients were dissatisfied and all would recommend the surgery to someone else. Conclusion: When used for foot and ankle surgery, hamstring autografts result in good functional outcomes and high patient satisfaction, with few patients experiencing symptoms from the harvest site at follow-up. Although our study was limited by its small number of patients and lack of preoperative isokinetic testing for comparison, effects on knee flexion strength do not appear to be clinically significant. Further work with larger numbers of patients will be required to identify small effects on knee flexion strength and to delineate differences between harvesting gracilis and semitendinosus.

The anterolateral ligament: Anatomic implications for its reconstruction

BackgroundThe purpose of this study was to define the best anatomic parameters with which to perform an accurate anterolateral ligament (ALL) reconstruction. These parameters were anatomical insertions, allowing favorable isometry, length variation during flexion, and anthropometric predictors of ALL lengths. MethodsA total of 84 fresh-frozen cadaver knees were dissected to analyze the ALL, focusing on its femoral insertion. The ALL length was measured in different degrees of flexion (extension, 30°, 60°, and 90° of flexion) and rotation (neutral, internal or external rotation). The ALL width and thickness were measured. A correlation between ALL length, the general knee size and individual characteristics was investigated. ResultsThe ALL was present in 80 specimens (95%). The femoral footprint was always posterior (5.52±0.93 mm, range 3.83–6.94) and slightly proximal (1.51±0.75mm, range 0.63–2.37) to the lateral femoral epicondyle. The mean ALL length increased with internal rotation and decreased with external rotation (P<0.05). The maximum ALL length was found at 30° of flexion, and the minimum at 90°. There was a significant correlation between the ALL length and height, sex, and proximal femur dimensions. ConclusionIn order to get an anatomical reconstruction with favorable isometry, it is recommended that the ALL femoral graft is implanted posterior and slightly proximal to the epicondyle. It is also suggested that the tension be adjusted by fixing the graft between 0 and 30° of flexion, being tighter near extension. This will allow good rotational stability without implying any stiffness.

Evaluation of I-Gel™ size 2 airway in different degrees of neck flexion in anesthetized children - a prospective, self-controlled trial.

A previous study by our group demonstrated an increase in oropharyngeal leak pressures and a deterioration of ventilation in maximum neck flexion with the I-Gel™ . To ascertain the optimal degree of neck flexion which increases OPLP without compromising ventilation we conducted a prospective self-controlled trial with the I-Gel™ in different degrees of neck flexion in anesthetized paralyzed children. The I-gel™ was inserted in 60 children undergoing inhalation induction with muscle paralysis for routine general anesthesia. Recordings of peak inspiratory pressures (PIP) at flexion of 15°, 30°, and 45° were taken as the primary outcome. Expired tidal volume, ventilation scoring, fiberoptic gradings, and OPLP in different degrees of flexion were recorded as secondary outcomes. There was a significant increase in mean PIP in cm H2 O at flexion 30° [13.3 (95% CI 12.8-13.8) cm H2 O, P<0.001] and 45° flexion (16.5 [15.9-17.1] cm H2 O, P<0.001) compared to neutral. A decrease in the expired tidal volume was seen at flexion of 30° (7.6 [7.3-7.8] cm H2 O, P=0.00) and 45° (7.6 [7.3-7.8] cm H2 O, P=0.00). There was deterioration of ventilation score, mean[range] at 30° flexion 2[0-3], and 45° flexion 1[0-3] compared to the neutral 3[2-3]. There was a significant increase in OPLP with an increase in degree of flexion. We conclude that 15° neck flexion can safely be applied without compromising ventilation with the I-Gel™ in anesthetized paralyzed children. However, Flexion of 30° or more warrants caution or the use of alternative devices like an endotracheal tube due to increase in PIP and worsening of ventilation score.

Abstract PR243

Background & Objectives: Previous study by our group showed that maximum flexion of head and neck results in increase in oropharangeal leak pressures (OPLP) and deterioration of ventilation with I-gel™. However the degree of neck flexion which increases OPLP without compromising ventilation is still not known. So we conducted a prospective self controlled trial evaluating the ventilation and oropharangeal leak pressures with I-Gel in mild, moderate and maximum degree of neck flexion in anaesthetized paralysed children. Materials & Methods: Anesthesia was induced with sevoflurane in oxygen. Atracurium intravenously was administered to facilitate neuromuscular relaxation. I-gel™ was inserted in 60 anaesthetised children. Recordings of Peak Inspiratory Pressures in flexion at 15°, 30° and 45° were compared with neutral and taken as primary outcome. Expired tidal volume, Ventilation scoring, Fiberoptic gradings and OPLP was also measured in different degrees of flexion as secondary outcomes. Results: Significant change in the mean difference of PIP (95%CI) cmH2O was seen at flexion 30° [2.4 (-2.9 to -1.9) cm H20, p<0.001] and flexion 45° [-5.6 (-6.1 to -5.0) cm H20, p <0.001] from neutral. There was significant decrease in the expired tidal volume with flexion 30° (p<0.001) and 45° (p<0.001) and increase in the OPLP at neck flexion of 15° (p<0.001), 30° (p<0.001) and 45° (p<0.001) compared with neutral position. Significant deterioration of ventilation score, mean [range] was seen with flexion of 30°, 2[0-3], p<0.05 and 45°, 1[0-3], p<0.05 compared to the neutral 3[2-3]. Conclusion: Although a consistent increase in OPLP is seen with flexion, caution is warranted with flexion of 30° and more due to deterioration of ventilation parameters.

A dynamic study of the anterior cruciate ligament of the knee using an open MRI

Recent anatomical and radiological studies of the anterior cruciate ligament (ACL) suggest the ACL length and orientation change during knee flexion, and an open MRI sequencing during knee flexion enables a dynamic ACL analysis. This study's goal is to describe a normal ACL using a 1T open MRI and, in particular, variations in length and insertion angles at different degrees of flexion. Twenty-one volunteers with clinically healthy knees received a dynamic MRI with their knees in hyperextension, neutral position, and flexed at 45° and 90° angles. For each position, two radiologists measured the ACL lengths and angles of the proximal insertion between the ACL's anterior edge and the roof of the inter-condylar notch. Additionally, we measured the ACL's and the tibial plateau's distal angle insertion between their anterior edges and then compared these with the nonparametric Wilcoxon test. The ACL had a significant extension between the 90° flexion and all other positions (hyperextension: 31.75±2.5mm, neutral position: 32.5±2.6mm, 45°: 35.6±1.6mm, 90°: 35.6±1.6mm). There was also a significant increase of the angle insertion between the proximal 90° flexion and all other positions, as well as between hyperextension and bending to 45° (hyperextension: 2.45°±3.7°, neutral: 13.4°±9.7°, 45°: 33 25±9.3, 90: 51.85°±9.3°). Additionally, there is a significant increase in the distal angle insertion for all positions (hyperextension: 133.2°±5.4°, neutral position: 134.95°±4.4°, 45°: 138.35°±5.9°, 90°: 149.15°±8.6°). Our study is the first to exhibit that a dynamic MRI has a significant ACL extension in vivo during bending. This concept opens the way for further studies to improve the diagnosis of traumatic ACL injuries using a dynamic MRI.

Upright weight-bearing CT of the knee during flexion: changes of the patellofemoral and tibiofemoral articulations between 0° and 120°.

To prospectively compare patellofemoral and tibiofemoral articulations in the upright weight-bearing position with different degrees of flexion using CT in order to gain a more thorough understanding of the development of diseases of the knee joint in a physiological position. CT scans of the knee in 0°, 30°, 60° flexion in the upright weight-bearing position and in 120° flexion upright without weight-bearing were obtained of 10 volunteers (mean age 33.7±6.1years; range 24-41) using a cone-beam extremity-CT. Two independent readers quantified tibiofemoral and patellofemoral rotation, tibial tuberosity-trochlear groove distance (TTTG) and patellofemoral distance. Tibiofemoral contact points were assessed in relation to the anteroposterior distance of the tibial plateau. Significant differences between degrees of flexion were sought using Wilcoxon signed-rank test (P<0.05). With higher degrees of flexion, internal tibiofemoral rotation increased (0°/120° flexion; mean, 0.5°±4.5/22.4°±7.6); external patellofemoral rotation decreased (10.6°±7.6/1.6°±4.2); TTTG decreased (11.1mm ±3.7/-2.4mm ±6.4) and patellofemoral distance decreased (38.7mm ±3.0/21.0mm ±7.0). The CP shifted posterior, more pronounced laterally. Significant differences were found for all measurements at all degrees of flexion (P=0.005-0.037), except between 30° and 60°. ICC was almost perfect (0.80-0.99), except for the assessment of the CP (0.20-0.96). Knee joint articulations change significantly during flexion using upright weight-bearing CT. Progressive internal tibiofemoral rotation leads to a decrease in the TTTG and a posterior shift of the contact points in higher degrees of flexion. This elucidates patellar malalignment predominantly close to extension and meniscal tears commonly affecting the posterior horns.

Estudo anatômico e funcional do complexo ligamentar colateral medial do cotovelo

OBJECTIVE: To carry out an anatomical study of the medial collateral ligament, an important elbow stabilizer in different degrees of elbow flexion-extension. METHODS: Forty elbows were dissected in order to analyze the functional behavior of the anterior, posterior and transverse ligament bands during valgus stress maneuvers of the elbow in different degrees of flexion and extension. Two groups were determined; in the group GPA the posterior band of the ligament was sectioned initially, then the articular capsule and finally the anterior band; in group GAP this order was reversed. RESULTS: Instability was observed in GPA only in the third stage, when there was a greater mean elbow's opening during the flexion (between 50° and 70°); in GAP, the instability was present since the first stage; the degrees of flexion with greater instability were the same as in group GPA. CONCLUSION: The anterior band of the medial collateral ligament of the elbow is the most important stabilizer of the elbow valgus instability, and its principal action occurs between 50° and 70° of elbow flexion. Level of Evidence III, Diagnostic Studies - Investigating a diagnostic test.

Arthroscopic ACL reconstruction with reverse “Y”-plasty grafts and fixation in the femur with either a bioabsorbable interference screw or an Endobutton

We propose a new reverse “Y”-plasty graft for use in anterior cruciate ligament (ACL) reconstruction that involves double tibial tunnels and a single femoral tunnel. With this technique, the hamstrings were used as autografts and fixed separately with bioabsorbable interference screws (group A) or Endobuttons (group B) in femurs. A prospective series of 63 patients underwent primary reconstruction of the ACL; all procedures were performed by the same surgeon. Group A included 35 patients (22 male, 13 female), with a mean age of 25.5 (17–40) years, who were followed up for 28.5 (12–48) months. Group B included 28 patients (17 male, 11 female), with a mean age of 24.3 (18–38) years, who were followed up for 29.5 (12–46) months. Lysholm, International Knee Documentation Committee (IKDC) and Larson scoring were used to compare the therapeutic effects experienced at the knee. Lysholm scores were 93.26±2.67 (group A) and 93.81±2.42 (group B); Larson scores were 91.91±2.29 (group A) and 92.81±2.39 (group B); IKDC scores were 93.89±1.88 (group A) and 94.15±1.77 (group B). None of the scoring differences between groups were statistically significant (T1=0.849, P1=0.399, T2=1.506, P2=0.137, T3=0.560, P3=0.578). The Lachman test was negative in 46 patients (90.2%) and 51 knees, including 25 (89.3%) of the 28 knees in group A and 21 (91.3%) of the 23 knees in group B. Negative Pivot shift was present postoperatively in 49 knees of 51 patients (96.1%), including 27 (96.4%) of the 28 knees in group A and 22 (95.7%) of the 23 knees in group B. All of the patients in both groups achieved full extension and at least 135° of knee flexion. This novel technique involves the creation of double tibial tunnels and a single femoral tunnel. In the tibia, there was a bone bridge, ranging from 2 to 3mm, between the two bundles, which are tensioned at different degrees of flexion to maintain the stability of the knee. In the femur, the grafts were fixed with bioabsorbable interference screws or Endobuttons. The outcomes show that normal function and joint stability were achieved in both groups, as compared with preoperative measurements. Although the outcomes in group A (grafts fixed with the bioabsorbable interference screws in the femur) was better than those observed in group B (grafts fixed with Endobuttons), there was no statistical difference between the groups.

Double-Bundle Anterior Cruciate Ligament Reconstruction

Background Single-bundle anterior cruciate ligament reconstruction seems to be insufficient to control a combined rotatory load of internal and valgus torque, whereas anatomical double-bundle reconstruction might produce a better biomechanical outcome, especially during rotatory loads. Hypothesis The addition of the posterolateral bundle to the anteromedial bundle, in an in vivo double-bundle computer-assisted anterior cruciate ligament reconstruction, is able to reduce the internal rotation of the tibia at different degrees of flexion. Study Design Controlled laboratory study. Methods Ten consecutive anterior cruciate ligament reconstruction procedures were performed in male patients using double-bundle gracilis and semitendinosus tendon graft with the 2.0 OrthoPilot anterior cruciate ligament navigation system. Anteroposterior displacement at 30°, 60°, and 90° as well as internal and external rotation at 0°, 15°, 30°, 45°, 60°, and 90° of knee flexion were evaluated before reconstruction, after fixation of the anteromedial bundle, and then after fixation of the posterolateral bundle. Results Fixation of the anteromedial bundle significantly (P <. 05) reduced the anteroposterior displacement at 30°, 60°, and 90° of knee flexion; the internal rotation at 15°, 30°, 45°, and 60°; and the external rotation at 0°, 30°, 60°, and 90°. The addition of the posterolateral bundle to the anteromedial bundle did not significantly reduce internal and external rotation of the tibia at degrees of flexion measured (P >. 05). Conclusion The hypothesis that the addition of the posterolateral bundle to the anteromedial bundle is able to reduce internal rotation of the tibia, minimizing the pivot-shift phenomenon, was not confirmed. Clinical Relevance The effective role of the anatomical double-bundle procedure in better restoring knee kinematics and allowing better clinical outcomes should be questioned in an in vivo model of anterior cruciate ligament reconstruction using doubled semitendinosus and gracilis graft.

Anatomic Factors Related to the Cause of Tennis Elbow

The pathogenesis of lateral epicondylitis remains unclear. Our purpose was to study the anatomy of the lateral aspect of the elbow under static and dynamic conditions in order to identify bone-to-tendon and tendon-to-tendon contact or rubbing that might cause abrasion of the tissues. Eighty-five cadaveric elbows were examined to determine details related to the bone structure and musculotendinous origins. We identified the relative positions of the musculotendinous units and the underlying bone when the elbow was in different degrees of flexion. We also recorded the contact between the extensor carpi radialis brevis and the lateral edge of the capitellum as elbow motion occurred, and we sought to identify the areas of the capitellum and extensor carpi radialis brevis where contact occurs. The average site of origin of the extensor carpi radialis brevis on the humerus lay slightly medial and superior to the outer edge of the capitellum. As the elbow was extended, the undersurface of the extensor carpi radialis brevis rubbed against the lateral edge of the capitellum while the extensor carpi radialis longus compressed the brevis against the underlying bone. The extensor carpi radialis brevis tendon has a unique anatomic location that makes its undersurface vulnerable to contact and abrasion against the lateral edge of the capitellum during elbow motion.

A convex lateral tibial plateau for knee replacement

Unicompartmental knee replacements have not performed as well in the lateral compartment as in the medial. This may be because the tibial components have flat or slightly concave surfaces which match the medial plateau but not the convex lateral plateau. The aim of this study was to find the optimal radius for a convex lateral tibial component.Twelve normal lateral tibial plateau were retrieved at knee replacement, and their surface contour in their mid sagittal plane was determined. The optimal circle was fitted and its radius measured. A series of different shaped tibial components were superimposed. From published information about the position of the femoral condyle relative to the tibia in different degrees of flexion, the flexion gap at these angles was determined.The average radius of the lateral tibial plateau was 40 mm. However, as the surface was polyradial it was not clear if this average radius would be optimal.In full flexion, a flat tibial plateau distracted the knee by 8 mm (p<0.001). A 75 mm radius spherical tibial plateau did not alter the knee kinematics significantly and gave rise to a change in joint distraction of 1.5 mm. Spherical tibial plateau of 50 mm and 25 mm radii significantly altered knee kinematics (p<0.001) and resulted in changes in distraction of 3 mm and 4 mm respectively.The optimal shape for a unicompartmental lateral tibial plateau is likely to be a spherical dome with radius of about 75 mm. The incorporation of this shape in the lateral side of a total knee replacement might improve its flexion.

Dynamic magnetic resonance imaging

Among the devices helping with an accurate diagnosis, neither MRI nor arthroscopy is perfect; both delineate pathology in the knee joint with reasonable sensitivity and specificity. MRI, as a noninvasive and nonionizing modality, has made a significant contribution to the understanding of musculoskeletal disturbances. Static images through the patellofemoral joint in different degrees of flexion reveal only the degree of patellar tilt or subluxation, parameters that can be measured also on the axial view of conventional radiography. The accuracy of patellar position on static axial MRI is limited by the absence of muscle contraction, movement, and loading. Dynamic axial images of patellofemoral articulation can demonstrate the degree of flexion where patellar malalignment is maximal and assess whether or not it reduces. Arthroscopy, aside from its diagnostic values, provides the opportunity for treatment of intra-articular changes contributing to knee joint disturbances, but it is an invasive technique with potential risks of complications. The performed cost-effectiveness analysis of MRI is based mainly on estimation of intra-articular pathology of the acutely-injured knee [49,52,56]. There are scarce data on the cost-effectiveness of MRI of patellofemoral alignment in patellofemoral pain knees. Total examination time for active movement dynamic MRI procedure is approximately 8 to 10 minutes, thus it can be performed during routine MRI examination of the knee. In cases of suspected patellofemoral malalignment with symptoms that mimic other types of internal derangement of the knee joint, dynamic MRI can be a procedure of choice for detection of transient patellar dislocation, whereas a single clinical examination cannot differentiate from other internal knee pathologies. Dynamic MRI, although in an experimental phase, gives us a new perspective for dynamic study of the patellofemoral joint.

Computed tomography evaluation of shoulder prosthesis retroversion

Computed tomography (CT) allows calculation of anatomic and prosthetic humeral head retroversion. The purpose of this study was to demonstrate how the retroversion angle measured by CT scan varied with changes in arm position in the CT scan reference system. A trigonometric analysis shows that the measured retroversion angle decreases when the arm is in extension and increases when it is in flexion, compared with the true retroversion angle determined perioperatively. For the same degree of flexion, or extension, the error of measurement is greater when the initial true retroversion is low. A shoulder prosthesis with 20° of true head retroversion was radiologically scanned with different degrees of flexion, extension, and abduction. The results validate the theoretical analysis. Trigonometric formulas are proposed to correct the retroversion angle measured by CT scan. (J Shoulder Elbow Surg 2001;10:546-9.)