Tibiofemoral Rotation Research Articles

Rotational profile alterations after anatomic posterolateral corner reconstructions in multiligament injured knees

Injuries of the posterolateral corner (PLC) are rare and severe knee injuries, resulting in posterolateral rotatory instability and an increase in external rotation. Surgical reconstruction techniques reproducing the normal anatomy showed promising results. In vivo evaluations of static rotational knee laxity at 30° of knee flexion have not been reported so far. The purpose of this study was to evaluate static rotational knee laxity after anatomic PLC reconstructions. This is a retrospective clinical cohort study. Twenty patients with PLC reconstructions with an average follow-up time of 39 ± 22 months and no history of knee trauma or surgery of the contralateral knee were included in the study. They underwent a routine clinical examination and static rotational laxity measurements at 30° of knee flexion in the prone position. Side-to-side differences were recorded and compared to a group of matched controls. The postoperative IKDC score was graded A for 8 patients, B for 16, C for 6 and D for one patient. The primary goal of the surgical procedure which consists in reducing excessive external tibiofemoral rotation could be reached in 18 of the 20 patients (90%). Anatomic PLC reconstructions yielded a comparable rotational profile in operated and healthy knees in 7 patients (35%). Thirteen patients (65%) presented a significantly altered rotational profile in comparison with a healthy control group. Unexpected increases in internal rotation were found in 8 patients (40%). Anatomic PLC reconstructions reduced excessive external tibiofemoral rotation in a vast majority of patients. Static rotational laxity measurements allowed for a determination of the patients' individual rotational profile after PLC reconstructions. This profile was normalised in only one-third of the patients. The understanding of this finding needs further investigation as well as the clinical impact of rotational profile alterations on knee function. Diagnostic studies, Level III.

The Role of the Indirect Femoral Insertion of the Anterior Cruciate Ligament in Restraining Tibial Translation and Rotation: Implications for Anatomic Femoral Tunnel Placement

Objectives:Despite a trend toward lowering the femoral tunnel and thus positioning ACL grafts partially within the indirect insertion of the ACL attachment, the biomechanical role of the indirect insertion has not been described. The purpose of this study was to determine the effect of debridement of the indirect femoral ACL insertion on tibiofemoral translation and rotation. It was hypothesized that debridement would have a negligible affect on tibiofemoral kinematics.Methods:Knee kinematics in six degrees of freedom were measured on a robotic device in nine cadaveric knees. Measurements were made with the ACL intact, following debridement of the indirect insertion, and following complete sectioning of the ACL. Three loading conditions were used: (1) a 134 N anterior tibial load, (2) a combined 10 Nm valgus and 5 Nm internal rotation torque, and (3) a simulated, robotic pivot shift. Debridement involved exposing 5-6 mm of bone from the central, inferior aspect of the direct ACL attachment to the inferior cartilage margin. Anterior tibial translation (ATT) was recorded in response to an anterior tibial load and combined rotatory loads at 0°, 15°, 30°, 45°, 60°, and 90° of knee flexion. Additionally, posterior tibial translation and external tibial rotation were recorded during a simulated, robotic pivot shift. Based on pilot data, it was estimated that 9 specimens would be required to detect a 1.4 mm difference in ATT between different experimental conditions with 80% power at an alpha level of 0.05. Data were analyzed using repeated measures ANOVA.Results:For the anterior tibial loading condition, debridement of the indirect insertion increased tibial translation by 0.37±0.24 mm at 0º (P<.01) and by 0.16±0.19 mm at 15º (P<.05; increases were < 1 mm in all specimens). ACL deficiency increased ATT in response to an anterior tibial load (P<.0001) with maximum effect at 15º (11.26±1.15 mm vs. ACL intact; 11.04±1.08 mm vs. indirect insertion debridement). For the combined rotatory loading condition, debridement increased tibial translation by 0.17±0.11 mm at 0º (P<.01; increases were < 0.3 mm in all specimens) with no effect at other flexion angles. ACL deficiency increased ATT in response to a combined rotatory load (P<.01) with maximum effect at 15º (4.45±0.85 mm vs. ACL intact; 4.44±0.84 mm vs. indirect insertion debridement). The contribution of the indirect insertion to restraining ATT in response to an anterior tibial load or a combined rotatory load was ≤ 5.5% in all specimens, at all flexion angles. During the simulated pivot shift, posterior tibial translation (12.79±3.22 mm) and external tibial rotation (17.60±4.30º) were greater in the ACL deficient condition (P<.0001) compared with the ACL intact (1.29±1.34 mm and 1.54±1.61º) and indirect insertion debridement conditions (1.28±1.34 mm and 1.54±1.47º). Posterior translation and external tibial rotation were not significantly different between the ACL intact and debridement conditions (P=.68, P=.99).Conclusion:Debridement of the indirect insertion resulted in a less than 1 mm increase in tibial translation and a less than 0.5º increase in tibial rotation in all specimens and testing conditions. Thus, the indirect femoral insertion of the ACL contributed minimally to restraint of tibial translation and rotation. These results support placement of the soft tissue aspect of a BPTB graft within the area of the direct insertion of the ACL and superior to the biomechanically insignificant indirect insertion.

Assessment of a Medial Pivot Total Knee Arthroplasty Design in a Cadaveric Knee Extension Test Model

A total knee has been designed to mimic less-compliant medial and more-compliant lateral behavior. In vivo testing compared open-kinematic chain behaviors of cadaver knees in their normal state and after implantation of the knee prosthesis. Specimen's limbs were computed tomography scanned, and infrared arrays on tibia and femur were registered to bone markers. Motion of the joint and quadriceps force were reported from 90° flexion to full extension. Less medial and more lateral anterior-posterior motion was seen in both the intact and the implanted knees. Tibiofemoral rotation and translation were similar in direction but were reduced in magnitude for the prosthetic knees. Quadriceps force, defined as that applied force required to extend the knee, required after implantation was variable between specimens but not statistically different from the intact condition. The prosthesis tested exhibits kinematic behavior similar to that in their normal state, with no difference in quadriceps force required for extension.

Intraoperative Computer Navigation Parameters Are Poor Predictors of Function 1 Year After Total Knee Arthroplasty

Intraoperative navigation data were collected prospectively for 134 knees undergoing cemented, posterior-stabilized total knee arthroplasty. Partial least squares regression analysis was used to test the association between patient demographics and intraoperative data collected with a computer-assisted navigation system (coronal alignment, ligament balance, range of motion, external tibiofemoral rotation) with 1-year outcomes (36-item Short-Form Health Survey, Oxford Knee Score, range of motion). Age at surgery displayed the largest coefficients of any other predictor. In contrast, navigation coefficients were variable in the strength and direction of their association with the outcome variables. Static knee alignment data obtained intraoperatively have limited capacity to explain the variance in functional outcome at 1 year. Although alignment and component position can be precisely measured intraoperatively, intrinsic patient factors remain dominant in determining the outcome.

Tibiofemoral and patellofemoral mechanics are altered at small knee flexion angles in people with patellofemoral pain

ObjectivesTo test the hypothesis that, at 0° and 20° of knee flexion, patellofemoral contact area would be lower, while tibiofemoral rotation and patellofemoral malalignment would be higher in participants with patellofemoral pain (PFP) compared to pain-free participants. We hypothesized that no differences would be detected at 40° due to increasing patellar stability. DesignCross-sectional, descriptive study. MethodsTwenty-seven people with PFP and 29 pain-free people participated. Participants underwent magnetic resonance imaging at 0°, 20°, and 40° knee flexion with the limb in a simulated weight-bearing position. Patellofemoral contact area, tibiofemoral rotation angle, patellofemoral alignment (bisect offset index and patellar tilt angle) were quantified and compared between groups at each angle using Student's t-tests. An a-posteriori comparison was made between the pain-free group and a subgroup of 15 participants with patellofemoral pain who demonstrated a faulty lower limb movement pattern (“medial collapse”). ResultsIn the patellofemoral pain group, contact area was lower at 0° (203.8±45.5mm2 vs. 224.1±46.6mm2, p=0.05) and 20° (276.8±56.2mm2 vs. 316.7±82.8mm2, p=0.02), bisect offset index (BOS) and patellar tilt angle (PTA) were higher at 0° (bisect offset index: 0.69±0.13 vs. 0.64±0.09, p=0.04; patellar tilt angle: 12.5±7.6° vs. 9.2±5.8°, p=0.04). In the patellofemoral pain subgroup, tibiofemoral rotation was higher at 0° compared to pain-free participants (6.4±5.9° vs. 4.0±4.6°, p=0.07). ConclusionsWhile contact area and patellofemoral alignment were altered in people with patellofemoral pain, tibiofemoral rotation was altered in a subgroup of people who demonstrated medial collapse. Subgroup classification may help identify mechanisms of pain and assist in developing targeted interventions.

The Pathophysiology of Osteoarthritis: A Mechanical Perspective on the Knee Joint

Osteoarthritis (OA) is the most frequent cause of disability in the United States, with the medial compartment of the knee being most commonly affected. The initiation and progression of knee OA is influenced by many factors, including kinematics. In response to loading during weight-bearing activity, cartilage in healthy knees demonstrates spatial adaptations in morphology and mechanical properties. These adaptations allow certain regions of the cartilage to respond to loading; other regions are less well suited to accommodate loading. Alterations in normal knee kinematics shift loading from cartilage regions adapted for loading to regions less well suited for loading, which leads to the initiation and progression of degenerative processes consistent with knee OA. Kinematic variables that are associated with the development, progression, and severity of knee OA are the adduction moment and tibiofemoral rotation. Because of its strong correlation with disease progression and pain, the peak adduction moment during gait has been identified as a target for treatment design. Gait modification offers a noninvasive option for seeking significant reductions. Gait modification has the potential to reduce pain and slow the progression of medial compartment knee OA.

In Vivo Analysis of the Isolated Posterior Cruciate Ligament–Deficient Knee During Functional Activities

Background: Most patients with isolated posterior cruciate ligament (PCL) injuries have minimal symptoms, and nonoperative treatment is recommended. However, over time, these patients can develop significant degenerative changes in their knees. Historically, PCL laxity is graded by nonweightbearing anteroposterior measuring techniques that do not reproduce the true, dynamic weightbearing conditions in the injured knee. The purpose of this study was to determine the patholaxity in patients with isolated PCL deficiency during functional weightbearing activities (running, walking, and stair ascent). Hypothesis: Patients with unilateral, isolated PCL deficiency will demonstrate dynamic anteroposterior and rotational instability in their affected knees during functional activities of level running and stair ascent compared with their unaffected, contralateral knees. Study Design: Controlled laboratory study. Methods: Nine asymptomatic patients with isolated grade II PCL injury underwent Dynamic Stereo X-Ray (DSX) of both knees during level running and stair ascent. Three-dimensional reconstructions of the patients’ bilateral distal femurs and proximal tibias were created from high-resolution computed tomography (CT) scans. Three-dimensional joint kinematics were determined using a model-based tracking approach to align the radiographic images with CT-derived bone models. The resulting tibiofemoral rotations and translations for the PCL-deficient and PCL-intact knees were then compared. Results: During level running, the tibia of the PCL-deficient knee was approximately 2 mm posteriorly subluxated and had an anterior velocity relative to the femur approximately 40 mm/s greater than the contralateral, uninjured knee; however, this was only during the swing phase. No significant differences were found during the stance phase of running. During stair ascent, the tibia of the PCL-deficient knee was approximately 4 mm posteriorly subluxated compared with the intact limb during the terminal swing phase and early stance phase. Between foot strike and the time of peak ground-reaction force (GRF), the tibia of the PCL-deficient knee translated anteriorly relative to the femur with velocities 3 to 4 times greater than in the intact limb. Level walking was also evaluated in 3 patients, but no differences were seen, and it was not tested in the remaining 6 patients. Conclusion: Changes in knee kinematics due to isolated PCL injuries were highly activity dependent. During running, small differences were identified only during the swing phase when the knee was unloaded. However, during stair ascent, significant differences extended from the late swing into early stance phase. During the swing phase of stair ascent, the tibia in the PCL-deficient joint subluxated posteriorly. Then, as load was transferred to the ascending limb, the tibia reduced anteriorly with high velocity relative to the femur. The resulting shear motion may expose the loaded joint to abnormal and potentially damaging forces. Clinical Relevance: During functional activities, patients with isolated PCL injuries experience significant knee instability that cannot be identified by standard nonweightbearing static laxity measurements. The finding that different activities create different degrees of instability may have important implications for rehabilitation and activity limitations for PCL-deficient individuals.

Objective measurement devices to assess static rotational knee laxity: focus on the Rotameter

The present article summarizes the development of a simple, objective, and non-invasive measurement device for tibiofemoral rotation to assess static rotational knee laxity. The device is based on the dial test with the patient lying prone and the knee flexed to 30°. From measurements of 30 healthy participants, the device achieved high inter- and intra-observer reliability and showed a high correlation of the measured results with the contralateral knees of the participants. Measurements of the device were also performed in a human cadaver study and revealed highly correlated results when compared to the simultaneous measurements of a knee navigation system, which was used as an invasive standard method to assess tibial rotation. In human cadaver specimens, it was shown that a simulated tear of the posterolateral bundle as well as a complete ACL tear led to a significant increase in isolated tibiofemoral rotation compared to the intact ACL. A retrospective case series investigated the clinical results as well as knee laxity measurements after ACL surgery in vivo. Rotational, as well as anteroposterior (AP), knee laxity was objectively assessed in 52 patients at a mean postoperative follow-up of 27months by comparing the measured results with the results of the contralateral unaffected knee in each patient. The clinical results were comparable to the results reported in the literature. Moreover, rotational laxity was successfully restored after ACL reconstruction, whereas AP laxity showed significant differences compared to the contralateral knees although they were defined as clinically successful according to the IKDC classification. A non-invasive and objective knee rotational measurement device has been developed, which offers good potential for objective quality control in knee ligament injuries and their treatment. Review article, Level IV.

Neuromuscular Changes After Aerobic Exercise in People with Anterior Cruciate Ligament– Reconstructed Knees

Anterior cruciate ligament (ACL) reconstructions are common, especially in young, active people. The lower extremity neuromuscular adaptations seen after aerobic exercise provide information about how previously injured patients perform and highlight deficits and, hence, areas for focused treatment. Little information is available about neuromuscular performance after aerobic exercise in people with ACL reconstructions. To compare dynamic balance, gluteus medius muscle activation, vertical jump height, and hip muscle strength after aerobic exercise in people with ACL-reconstructed knees. Case-control study. Research laboratory. Of 34 recreationally active volunteers, 17 had a unilateral primary ACL reconstruction at least 2 years earlier and 17 were matched controls. All participants performed 20 minutes of aerobic exercise on a treadmill. We recorded dynamic, single-legged balance electromyographic gluteus medius muscle activation, single-legged vertical jump height, and maximum isometric strength for hip abduction, extension, and external rotation preexercise and postexercise. Participants with ACL reconstructions exhibited shorter reach distances during dynamic balance tasks, indicating poorer dynamic balance, and less gluteus medius muscle electromyographic activation. Reductions in hip abduction and extension strength after exercise were noted in all participants; however, those with ACL reconstructions displayed greater hip extensor strength loss after aerobic exercise than did the control group. Neuromuscular changes after aerobic exercise exist in both patients with ACL reconstructions and controls. The former group may experience greater deficits in hip extensor strength after aerobic exercise. Reduced reach distances in people with ACL reconstructions may represent a protective mechanism against excessive tibiofemoral rotation during dynamic balance. Clinicians should identify weaknesses in the resting state and after aerobic exercise in recreationally active patients and those with ACL reconstructions.

Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays

In clinical routine, lower limb analysis relies on conventional X-ray (2D view) or computerised tomography (CT) Scan (lying position). However, these methods do not allow 3D analysis in standing position. The aim of this study is to propose a fast and accurate 3D-reconstruction-method based on parametric models and statistical inferences from biplanar X-rays with clinical measurements' (CM) assessment in standing position for a clinical routine use. For the reproducibility study, the 95% CI was under 2.7° for all lower limbs' angular measurements except for tibial torsion, femoral torsion and tibiofemoral rotation ( < 5°). The 95% CI were under 2.5 mm for lower limbs' lengths and 1.5 to 3° for the pelvis' CM. Comparisons between X-rays and CT-scan based 3D shapes in vitro showed mean differences of 1.0 mm (95% CI = 2.4 mm). Comparisons of 2D lower limbs' and 3D pelvis' CM between standing ‘Shifted-Feet’ and ‘Non-Shifted-Feet’ position showed means differences of 0.0 to 1.4°. Significant differences were found only for pelvic obliquity and rotation. The reconstruction time was about 5 min.

Measurements of Tibiofemoral Kinematics during Soft and Stiff Drop Landings Using Biplane Fluoroscopy

Background Previous laboratory studies of landing have defined landing techniques in terms of soft or stiff landings according to the degree of maximal knee flexion angle attained during the landing phase and the relative magnitude of the ground-reaction force. Current anterior cruciate ligament injury prevention programs are instructing athletes to land softly to avoid excessive strain on the anterior cruciate ligament. Purpose This study was undertaken to measure, describe, and compare tibiofemoral rotations and translations of soft and stiff landings in healthy individuals using biplane fluoroscopy. Study Design Controlled laboratory study. Methods The in vivo, lower extremity, 3-dimensional knee kinematics of 16 healthy adults (6 male and 10 female) instructed to land softly and stiffly in different trials were collected in biplane fluoroscopy as they performed the landing from a height of 40 cm. Results Average and maximum relative anterior tibial translation (average, 2.8 ± 1.2 mm vs 3.0 ± 1.4 mm; maximum, 4.7 ± 1.6 mm vs 4.4 ± 0.8 mm), internal/external rotation (average, 3.7° ± 5.1° vs 2.7° ± 4.3°; maximum, 5.6° ± 5.5° vs 4.9° ± 4.7°), and varus/valgus (average, 0.2° ± 1.2° vs 0.2° ± 1.0°; maximum, 1.7° ± 1.2° vs 1.6° ± 0.9°) were all similar between soft and stiff landings, respectively. The peak vertical ground-reaction force was significantly larger for stiff landings than for soft landings (2.60 ± 1.32 body weight vs 1.63 ± 0.73; P < .001). The knee flexion angle total range of motion from the minimum angle at contact to the maximum angle at peak knee flexion was significantly greater for soft landings than for stiff (55.4° ± 8.8° vs 36.8° ± 11.1°; P < .01). Conclusion Stiff landings, as defined by significantly lower knee flexion angles and significantly greater peak ground-reaction forces, do not result in larger amounts of anterior tibial translation or knee rotation in either varus/valgus or internal/external rotation in healthy individuals. Clinical Relevance In healthy knees, the musculature and soft tissues of the knee are able to maintain translations and rotations within a small, safe range during controlled landing tasks of differing demand. The knee kinematics of this healthy population will serve as a comparison for injured knees in future studies. It should be stressed that because the authors did not compare how the loads were distributed over the soft tissues of the knee between the 2 landing styles, the larger ground-reaction forces and more extended knee position observed during stiff landings should still be considered dangerous to the anterior cruciate ligament and other structures of the lower extremities, particularly in competitive settings where movements are often unanticipated.

Wear Rate in a Series of Retrieved RP Knee Bearings

Abstract Rotating platform mobile bearing knees are an appealing approach to the problems of tibial loosening and rotational mal-alignment that are of concern with fixed bearing knees. A potential disadvantage of rotating platform (RP) bearings is ultra-high molecular weight polyethylene (UHMWPE) wear debris from the large additional backside articular surface that accommodates tibio-femoral rotation. The investigation of a series of 76 rotating platform knees (Sigma® RP, DePuy/J&amp;J, Warsaw, IN) indicates that UHMWPE bearing wear, as measured by change in through-thickness dimension, increases monotonically with time in vivo. Total wear penetration rate is 0.023 mm/year and shows a decreasing trend, though this trend is not statistically significant. The current study results are consistent with the decreasing wear rate previously reported in a series of LCS® RP (DePuy/J&amp;J, Warsaw, IN) knee. This decreasing wear rate stands in contrast to an increasing backside-only wear rate reported in fixed bearing knees. An important contribution of the current study is that it provides a conservative measurement of total wear penetration and penetration rate in one mobile bearing design over time out to&amp;gt;8 years.

Damage and Wear: An Important Distinction in Rotating Platform Knee Bearings

Abstract Rotating platform mobile bearing knees are an appealing approach to the problems of tibial loosening and rotational malignment in fixed bearing knees. A potential disadvantage is the additional large articular surface that accommodates tibio-femoral rotation. Accurately assessing the tribological performance of this additional articular surface is important to understanding how mobile bearings perform in terms of generating polyethylene wear debris and associated osteolysis. A series of 76 retrieved Sigma Rotating Platform bearings were assessed for damage rating according to conventional protocol and through-thickness wear measurements were taken. The results show that the rotation surface of these bearings is very commonly subject to moderate and severe damage and that damage can occur early following implantation. The decrease of the through-thickness dimension is strongly correlated with time in vivo. The rotation surface damage rating shows a weak though statistically significant correlation to through-thickness wear. Three dimensional surface profilometry on the bearings illuminates phenomena that can explain the paradoxical observations that severely damaged bearings may not be worn and worn bearing areas are smoother and show less damage than unworn areas. This study finds that bearing damage is distinct from bearing wear and the two terms are not interchangeable in the context of assessing material loss from artificial knee bearings. While both processes are important in the tribology of knee devices, it is not accurate to use damage on ultrahigh molecular weight polyethylene as a proxy for wear.

Extensor malalignment arising from femoral component malrotation in knee arthroplasty: Effect of rotating–bearing

Background Many patellofemoral complications such as anterior knee pain, subluxation, fracture, wear, and aseptic loosening after total knee arthroplasty are attributed to malrotation of the femoral component. Rotating-platform mobile bearings can reduce malrotation between the tibial and femoral components and may also improve patellofemoral maltracking. Methods A computer model (LifeMOD/KneeSIM) of a weight-bearing deep knee bend was validated using cadaver knees tested in an Oxford-type knee rig. Changes in knee kinematics and patellofemoral forces were measured after femoral component malrotation of ± 3°. The effect of a rotating–bearing on these kinematics and forces was determined. Findings In a fixed-bearing arthroplasty femoral component internal malrotation increased tibiofemoral internal rotation by 3.4°, and external malrotation increased tibiofemoral external rotation by 4°. Femoral component malrotation affected patellofemoral lateral shift by up to 2.5 mm, and patellofemoral lateral shear by up to 19 N. When the malrotated femoral component was tested against a rotating–bearing the change in tibiofemoral rotation and patellofemoral lateral shift was less than 1° and 1 mm respectively. The rotating–bearing reduced peak lateral shear by 7 N and peak medial shear by 17 N. Increasing the conformity of the rotating–bearing reduced changes in tibiofemoral rotation due to femoral malrotation and increased the net rotation of the bearing (by approximately 5°) during flexion. Interpretation Our results are consistent with one randomized clinical outcome study and emphasize the value of computational modeling for preclinical design evaluation. It is important to continue to improve existing methodologies for accurate femoral component alignment especially in rotation.

Influence of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament on External and Internal Tibiofemoral Rotation

Background The influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on tibiofemoral rotation might be of great value to detect anterior cruciate ligament injuries and investigate the postoperative restoration of rotational stability. Hypothesis The anterior cruciate ligament and especially the posterolateral bundle will have a significant influence on isolated tibiofemoral rotation. Study Design Controlled laboratory study. Methods Tibiofemoral rotation was measured in 20 human cadaveric knees using a noninvasive external measurement device (Rotameter) and a knee navigation system. The measurements of the knees with the intact anterior cruciate ligament were compared with the measurements after isolated resection of the posterolateral bundle and after a complete resection of the anterior cruciate ligament at an applied torque of 5,10, and 15 N·m. Statistical analysis was made using analysis of variance and the post hoc Scheffé test. The Pearson coefficient was used to compare both measurement techniques. Results In comparison with knees with an intact anterior cruciate ligament, the knees after isolated resection of the posterolateral bundle showed significant increase of tibiofemoral rotation at almost all applied torques (P < .05). Total resection of the anterior cruciate ligament also produced significant increases compared with the intact anterior cruciate ligament at torques of 5, 10, and 15 N·m as measured by the Rotameter (P < .05). Total resection of the anterior cruciate ligament yielded increases in rotation compared with posterolateral bundle resection alone, but these differences were not significant. The results of the knee navigation system confirmed the measured results of the Rotameter. Comparison of the 2 measurement methods revealed a high correlation at all applied torques, with Pearson correlation coefficients ranging from .85 to .95. Conclusion The anterior cruciate ligament and especially the posterolateral bundle of the anterior cruciate ligament have a significant effect on isolated tibiofemoral rotation. Therefore, the developed noninvasive device might be of great importance to investigate the status and the postoperative reconstruction of the anterior cruciate ligament in the clinical setting. Clinical Relevance Noninvasive measurement of tibiofemoral rotation might be useful to detect anterior cruciate ligament tears and to evaluate the restoration of rotational stability after anterior cruciate ligament surgery.

CSM 2010 Orthopaedic Section Platform Presentations (Abstracts OPL1-OPL67)

CSM 2010 Orthopaedic Section Platform Presentations (Abstracts OPL1-OPL67)

Patellar tendon orientation and patellar tracking in male and female knees

Knowledge of patellofemoral joint biomechanics is important for understanding sex-related dimorphism in patellofemoral pathologies and advancement of related treatments. We evaluated the hypotheses that sex differences exist in patellar tendon (PT) orientation and patellar tracking during weight-bearing knee flexion and that they relate to differences in tibiofemoral rotation. The PT orientation and patellar tracking were measured in healthy subjects (18 male, 13 female) during weight-bearing knee flexion, using magnetic resonance and dual fluoroscopic imaging. These data were analyzed for sex differences and correlation with previously reported tibiofemoral rotation data. The results indicated a significant effect of sex on PT orientation, particularly at low flexion angles. In females, the PT was oriented more anteriorly in the sagittal plane, more medially in the coronal plane, and showed greater external tilt in the transverse plane of the tibia (p < 0.05). Significant correlations between tibiofemoral rotation and PT orientation (p < 0.01) indicated that sex differences in coronal and transverse plane orientation of the PT relate to differences in tibiofemoral rotation. Patellar tracking did not show significant sex differences or correlation to tibiofemoral rotation. Further studies are warranted to determine implications for patellofemoral pathologies and treatments like total knee arthroplasty.

In Vivo Kinematics after a Cruciate-substituting TKA

Patterns of motion in the native knee show substantial variability. Guided motion prosthetic designs offer stability but may limit natural variability. To assess these limits, we therefore determined the in vivo kinematic patterns for patients having a cruciate-substituting TKA of one design and determined the intersurgeon variability associated with a guided-motion prosthetic design. Three-dimensional femorotibial contact positions were evaluated for 86 TKAs in 80 subjects from three different surgeons using fluoroscopy during a weightbearing deep knee bend. The average posterior femoral rollback of the medial and lateral condyles for all TKAs from full extension to maximum flexion was -14.0 mm and -23.0 mm, respectively. The average axial tibiofemoral rotation from full extension to maximum flexion for all TKAs was 10.8 degrees. The average weightbearing range of motion (ROM) was 109 degrees (range, 60 degrees-150 degrees; standard deviation, 18.7 degrees). Overall, the TKA showed axial rotation patterns similar to those of the normal knee, although less in magnitude. Surgeon-to-surgeon comparison revealed dissimilarities, showing the surgical technique and soft tissue handling influence kinematics in a guided-motion prosthetic design. Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Bone Bruise in Patients with Acute Patella Dislocation

We investigated the biomechanical significance of bone bruises in patients with patella dislocation. Thirty-four patients with acute dislocation of the patella were studied. Redislocations were excluded. There were 11 men and 20 women with a mean age of 18 years at the time of injury. Bone bruises were noted at the periphery of the lateral femoral condyle in 22 patients (65%) and in 10 cases (29%) at the medial patellar facet. The sulcus angle in patients with bone bruises at the lateral femoral condyle was significantly greater and tibiofemoral rotation at the knee was significantly smaller than in patients without bone bruises. In knees with small tibiofemoral rotation, a large lateral displacement force applied into the knee joint is needed to displace the patella. The flat femoral trochlea groove, however, can not reduce the force, resulting in hard impaction between the medial patella facet and the lateral femoral condyle producing bone bruises.

Diagnosis and Management of a Patient With Knee Pain Using the Movement System Impairment Classification System

Case report. Selecting the most effective conservative treatment for knee pain continues to be a challenge. An understanding of the underlying movement system impairment that is thought to contribute to the knee pain may assist in determining the most effective treatment. Our case report describes the treatment and outcomes of a patient with the proposed movement system impairment (MSI) diagnosis of tibiofemoral rotation. The patient was a 50-year-old female with a 3-month history of left anteromedial knee pain. Her knee pain was aggravated with sitting, standing, and descending stairs. A standardized clinical examination was performed and the MSI diagnosis of tibiofemoral rotation was determined. The patient consistently reported an increase in pain with activities that produced abnormal motions or alignments of the lower extremity in the frontal and transverse planes. The patient was educated to modify symptom-provoking functional activities by restricting the abnormal motions and alignments of the lower extremity. Exercises were prescribed to address impairments of muscle length, muscle strength, and motor control proposed to contribute to the tibiofemoral rotation. Tape also was applied to the knee in an attempt to restrict tibiofemoral rotation. The patient reported a cessation of pain and an improvement in her functional activities that occurred with correction of her knee alignment and movement pattern. Pain intensity was 2/10 at 1 week. At 10 weeks, pain intensity was 0/10 and the patient reported no limitations in sitting, standing, or descending stairs. The patient's score on the activities of daily living scale increased from 73% at the initial visit to 86% at 10 weeks and 96% at 1 year after therapy was discontinued. This case report presented a patient with knee pain and an MSI diagnosis of tibiofemoral rotation. Diagnosis-specific treatment resulted in a cessation of the patient's pain and an improved ability to perform functional activities.