Axial rotation and mediolateral translation of the fibula during passive plantarflexion

BACKGROUND: Since the fibula is linked to the ankle as well as the knee joint, its importance for knee and ankle disabilities should be investigated. This study evaluates its movement during range of motion of the ankle. MATERIALS AND METHODS: An instrument, together with the experimental protocol, was devised to determine the relative motion of the fibula in reference to the tibia with motion of the ankle joint on 20 paired lower extremity cadaver specimens. RESULTS: It was demonstrated in all specimens that the fibula had a relative rotation around its longitudinal axis and mediolateral translation with reference to the tibia with ankle motion. The distal end of the fibula rotates more compared to the proximal end. The mediolateral translation of the proximal end of the fibula is rather close to that of the distal end. Although there was no consistent pattern for rotation, dorsiflexion caused lateral translation and plantarflexion caused medial displacement for most of the specimens. CONCLUSION: A novel, invasive but relatively simple test setup was devised. Movement of the fibula which is important for the kinematics and kinetics of the knee and ankle joints was evaluated by this new device. CLINICAL RELEVANCE: Evaluation of the fibula movement in normal lower extremities may lead to better understanding of its dynamic function which could have treatment implications for pathological conditions.     

Standardized biomechanical measurement for varus-valgus stiffness and rotation in normal knees

Seventeen female and 24 male subjects had varus and valgus and apparent rotations measured using a standardized mechanical testing device that cyclically applied a 20-Nm moment in each direction. Five parameters--apparent varus rotation, apparent valgus rotation, apparent overall rotation, varus stiffness, and valgus stiffness showed intersubject variations approaching 40%. Right-left variations in the same subject averaged 12%, with no significant right-left differences overall. Female knees rotated 66% more than male knees and were 35% less stiff. The ratio of apparent valgus rotation to apparent varus rotation averaged 0.775, and the ratio of valgus stiffness to varus stiffness averaged 1.23 for all knees. Stiffness and rotation parameters were highly correlated for both genders in the valgus phase of testing. Results suggest that although magnitudes of measured parameters vary considerably from subject to subject, common relationships between parameters from the same normal knee exist.     

The effects of tibial rotation on posterior translation in knees in which the posterior cruciate ligament has been cut

BACKGROUND: One of the most useful clinical tests for diagnosing an isolated injury of the posterior cruciate ligament is the posterior drawer maneuver performed with the knee in 90 degrees of flexion. Previously, it was thought that internally rotating the tibia during posterior drawer testing would decrease posterior laxity in a knee with an isolated posterior cruciate ligament injury. In this study, we evaluated the effects of internal and external tibial rotation on posterior laxity with the knee held in varying degrees of flexion after the posterior cruciate and meniscofemoral ligaments had been cut. MATERIALS AND METHODS: Twenty cadaveric knees were used. Each knee was mounted in a fixture with six degrees of freedom, and anterior and posterior forces of 150 N were applied. The testing was conducted with the knee in 90 degrees, 60 degrees, 30 degrees, and 0 degrees of flexion with the tibia in neutral, internal, and external rotation. All knees were tested with the posterior cruciate and meniscofemoral ligaments intact and transected. Repeated-measures analysis of variance was used for statistical analysis. RESULTS: At 30 degrees, 60 degrees, and 90 degrees of flexion, there was a significant increase in posterior laxity following transection of the posterior cruciate and meniscofemoral ligaments. At 60 degrees and 90 degrees of flexion, there was significantly less posterior laxity when the tibia was held in internal compared with external rotation. At 0 degrees and 30 degrees of flexion, there was no significant difference in posterior laxity when the tibia was held in internal compared with external rotation. CONCLUSIONS: After the posterior cruciate and meniscofemoral ligaments had been cut, posterior laxity was significantly decreased by both internal and external rotation of the tibia. Internal tibial rotation resulted in significantly less laxity than external tibial rotation did at 60 degrees and 90 degrees of knee flexion.     

The effect of radiofrequency thermal capsulorrhaphy on glenohumeral translation, rotation, and volume

The purpose of this study is to evaluate the effects of radiofrequency (RF) thermal capsulorrhaphy on the kinematic properties of the glenohumeral joint as determined by changes in resistance to multidirectional translational forces, alteration in the range of internal and external rotation, and changes in glenohumeral joint volume. Nonablative RF thermal energy was used to contract the glenohumeral joint capsule in 6 cadaveric shoulders. Measurements of translation were made after application of a 30-N load in anterior, posterior, and inferior directions. The maximum arc of internal and external rotation after application of a 1-N-m moment was also determined for vented specimens before and after thermal capsulorrhaphy. The percent reduction in glenohumeral capsular volume was measured by use of a saline solution injection-aspiration technique. Capsular shrinkage resulted in reductions in anterior, posterior, and inferior translation. The largest percent reductions in anterior translation were seen in external rotation at 45 degrees (48%, P <.05) and 90 degrees (41%, P <.05) abduction. For inferior translation, the largest percent reductions were seen in internal rotation at 45 degrees (40%, P <.05) and 90 degrees (45%, P <.05) abduction. Reductions in posterior translation were noted in internal rotation at 45 degrees (27%, P <.05) and 90 degrees (26%, P <.05) abduction. Other changes in translation were observed but were not statistically significant. The maximum arc of humeral rotation was reduced by a mean of 14 degrees at 45 degrees abduction and 9 degrees at 90 degrees abduction. The mean percent reduction in capsular volume for all shoulders was 37% (range, 8%-50%). This could not be correlated with percent reductions in translation and rotation. This study demonstrated the significant effect of RF thermal capsulorrhaphy in reducing glenohumeral multidirectional translation and volume with only a small loss of rotation in cadaveric shoulders.     

胫骨平台切模的固定方法对胫骨平台截骨在内外翻和前后倾方面影响的研究

目的探讨胫骨平台切模的固定方法对胫骨平台截骨在内外翻和前后倾方面的影响,比较不同数目、不同位置钉子固定的平台切模在相同外力下发生的内外翻和前后倾的差异。方法以12根左侧下肢假骨和一个左侧半骨盆假骨为标本,连接红外线计算机导航系统,固定标本,固定股骨及胫骨发射器,输入数据,分别以不同数目及位置的钉固定平台切模于假骨,通过切模槽内用锯片予以相同外力,记录后倾角度、内外翻角度的变化。结果用2根钉固定胫骨平台切模前后倾角度摆幅平均超过3°,最高超过5°,内外翻角度摆幅平均超过1°,最高超过3°,3根钉固定平台不论在前后倾还是内外翻方面的稳定性都非常明显好于2根钉固定。4根钉固定在前后倾方面稳定性好于3根钉固定,内外翻方面的稳定性无明显差异。结论胫骨平台切模的固定方法对胫骨平台截骨在内外翻和前后倾方面有明显影响,3根钉固定稳定性较好且易于操作,推荐采用3根钉固定。     

The effects of hamstring lengthening on hip rotation

The purpose of this study is to determine the effect on hip rotation of hamstring lengthening as measured by preoperative and postoperative motion analysis. Thirty-eight patients/76 hips in children with cerebral palsy spastic diplegia were retrospectively reviewed using presurgical and postsurgical gait analysis. Physical examination and gait analysis showed an increase in knee extension and decreased popliteal angles postoperatively. Kinematic analysis showed an increase in knee extension and decreased hip internal rotation throughout the gait cycle postoperatively as well. No difference was seen between those with internal and external rotation pattern at the hip preoperatively. As a group, the patients did not improve enough to change from internal to external rotation at the hip, suggesting that children with cerebral palsy spastic diplegia with significant internal rotation gait should have other surgical options besides hamstring lengthening when internal rotation gait of the hip is to be treated.     

The anatomy of the ACL and its importance in ACL reconstruction

The anterior cruciate ligament (ACL) anatomy is very significant if a reconstruction is attempted after its rupture. An anatomic study should have to address, its biomechanical properties, its kinematics, its position and anatomic correlation and its functional properties. In this review, an attempt is made to summarize the most recent and authoritative tendencies as far as the anatomy of the ACL, and its surgical application in its reconstruction are concerned. Also, it is significant to take into account the anatomy as far as the rehabilitation protocol is concerned. Separate placement in the femoral side is known to give better results from transtibial approach. The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in anatomic ACL reconstruction. The anatomic centrum of the ACL femoral footprint is 43 % of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin. Some important factors affecting the surgical outcome of ACL reconstruction include graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing. The rehabilitation protocol should come in phases in order to increase range of motion, muscle strength and leg balance, it should protect the graft and weightbearing should come in stages. The cornerstones of such a protocol remain bracing, controlling edema, pain and range of motion. This should be useful and valuable information in achieving full range of motion and stability of the knee postoperatively. In the end, all these advancements will contribute to better patient outcome. Recommendations point toward further experimental work with in vivo and in vitro studies, in order to assist in the development of new surgical procedures that could possibly replicate more closely the natural ACL anatomy and prevent future knee pathology.     

Motion of a mobile bearing knee allowing translation and rotation.

The kinematics of a mobile bearing knee, which allowed +/-20 degrees of rotation and 4.5 mm of anteroposterior translation, was measured for ascending and descending a step, deep-knee bend, normal walking, and twisting. A fluoroscopic technique was used, analyzed by 2 different methods. The rotations and displacements during the activities were similar to those of moderate-to-high constrained fixed bearing knees. The motion patterns were variable among test subjects and in general did not reproduce normal knee motion. Because of the freedom of anteroposterior translation and rotation in the design, however, each knee could determine its own neutral position and its own axis of internal-external rotation, depending on the activity.     

Influence of anticipation on movement patterns in subjects with ACL deficiency classified as noncopers

STUDY DESIGN: Two-factor, mixed experimental design. OBJECTIVES: To compare movement patterns of subjects who are anterior cruciate ligament (ACL) deficient and classified as noncopers to controls during early stance of anticipated and unanticipated straight and cutting tasks. BACKGROUND: Altered neuromuscular control of subjects that are ACL deficient and noncoper theoretically influences movement patterns during unanticipated tasks. METHODS AND MEASURES: The study included 16 subjects who are ACL deficient, classified as noncopers, and 20 healthy controls. Data were collected using an Optotrak Motion Analysis System and force plate integrated with Motion Monitor Software to generate knee joint angles, moments, and power. Each testing session included anticipated tasks, straight walking task (ST), and 45 degrees side-step cutting tasks (SSC), followed by a set of unexpected straight walking (STU) and unexpected sidestep cutting (SSCU) tasks in a random order. For all tasks speed was maintained at 2 m/s. Peak knee angle, moment, and power variables during early stance were compared using 2-way mixed-effects ANOVA models. RESULTS: For both the straight and sidestep tasks, the noncoper group did not show a dependence on whether the task was anticipated or unanticipated (group-by-condition interaction) for the knee angle (straight, P = .067; side-step cutting, P = .103), moment (straight, P = .079; side-step cutting, P = .996), and powers (straight, P = .181; side-step cutting, P = .183) during the loading response phase. However, during both straight and side-step cutting tasks, the subjects in the noncoper group used significantly lower knee flexion angles (straight, P = .002; side-step cutting, P = .019), knee moments (straight, P = .005; side-step cutting, P < .001), and knee powers (straight, P = .013; side-step cutting, P <.001). CONCLUSIONS: This study suggests subjects that are ACL deficient and classified as noncopers use a common abnormal movement pattern of lower knee extensor loading even during unanticipated tasks.     

The effects of rotation on radiographic evaluation of the tibiofibular syndesmosis

Radiographs of 12 normal cadaveric lower extremities were prepared with each extremity in seven increments of axial rotation, ranging from 5 degrees of external rotation to 25 degrees of internal rotation. The tibiofibular clear space, the tibiofibular overlap, the width of the tibia and fibula, and the medial clear space were measured on each film. The width of the tibiofibular clear space (syndesmosis A) averaged 3.9+/-0.9 mm (range, 2 to 5.5 mm), but did not change significantly with rotation. Its size was independent of the size of tibia and fibula. All other measurements changed dramatically with rotation. In our specimens, a true mortise view of the ankle joint was obtained by internally rotating the extremity an average of 13.6+/-0.7 degrees (range, 12.0 degrees to 17.0 degrees). Based on our results the width of the tibiofibular clear space on the anterior-posterior view is the most reliable parameter for detecting widening of the syndesmosis on plain radiographs. However, due to its variability among different individuals, comparison views of the contralateral extremity are warranted for confirmation of clinical suspicion of syndesmosis disruption.     

The short-term outcome of surgical treatment for painful varus arthritis in association with chronic ACL deficiency

A review of patients with anterior cruciate ligament (ACL) insufficiency, symptomatic medial compartment osteoarthritis, and varus malalignment of the knee was performed. Twenty-six patients met the inclusion criteria. Twelve patients were treated with a valgus closing-wedge high tibial osteotomy (group 1). Fourteen patients were treated with a valgus closing-wedge high tibial osteotomy combined with arthroscopic ACL reconstruction (group 2). Twenty-five patients were available for follow-up at a minimum of 2 years. For group 1 patients, high tibial osteotomy alone had no effect on the Lachman test or pivot shift phenomena. For group 2 patients, combined high tibial osteotomy/ACL reconstruction resulted in a grade 1 Lachman test in 11 of 13 patients, and a negative pivot shift in 12 of 13 patients. No deficits in range of motion were noted in either group. Prior to surgery, 14 (56%) patients participated in recreational sports; 23 (92%) patients were able to participate in recreational sports at follow-up. Radiographs demonstrated osteoarthritic progression in group 1 and 2 patients (P<.05). The results of this study suggest that high tibial osteotomy alone and combined high tibial osteotomy/ACL reconstructions are effective in the surgical treatment of varus, ACL-deficient knees with symptomatic medial compartment arthritis; however, good or excellent results were more often seen after the combined procedure.     

Characteristics of anterior tibial translation with active and isokinetic knee extension exercise before and after ACL reconstruction

 The aim of this study was to investigate the biomechanical characteristics of anterior tibial translation (ATT) in anterior cruciate ligament (ACL)-deficient or -reconstructed knees with active and isokinetic knee extension exercise. Forty-nine patients with unilateral isolated ACL-deficient knees were enrolled. Follow-up examinations were carried out at a mean of 24 months postoperatively. An electrogoniometer system was applied to compare the amount of ATT in ACL-deficient and -reconstructed knees. For both active and isokinetic knee extension, the mean ATT of ACL-deficient knees was considerably greater than that for the normal side, within a range of flexion 0°–70° and 0°–60°, respectively. In contrast, no mean ATT differences were seen during both active and isokinetic exercise from 90° to 0° at follow-up. Within a range of flexion between 50° and 70°, the side-to-side difference in ATT with active knee extension was significantly greater than that with isokinetic extension in ACL-reconstructed knees. These results suggest that the amount of ATT is significantly improved with both active and isokinetic exercise, postoperatively. However, postoperative ATT with isokinetic extension is smaller than that with active knee extension from 50° to 70°. Received: October 17, 2001 / Accepted: December 26, 2001     

The influence of mediolateral deformity,tibial torsion,and foot position on femorotibial load

Summary The influence of mediolateral deformity, tibial torsion, and different centers of foot support was studied with a three-dimensional computer model that incorporates the significant muscles of the lower extremities needed for quasi-static walking. This theoretical method avoids the variability in gait pattern from the pain and discomfort associated with deformity in patients. The study illustrates the possible importance of the muscle force on the load across the knee and ankle. High strains in the medial gastrocnemius and the medial hamstring created particularly high loads in the medial compartment of the knee. Internal torsion and varus deformity were associated with the highest loads in the medial compartment of the knee, although the peak load for each deformity occurred in different phases of the gait cycle. Both external torsion and valgus deformity generally decreased the load in the medial compartment, but early in the gait cycle external torsion increased the loads on the medial side. In addition, when the center of support of the body was in the forefoot, the loads through the knee were lower than when foot support was at the heel. As expected, if the center of support was on the lateral foot line, the lateral compartment was subjected to more load and, conversely, when the center of support was on the medial part of the foot the medial compartment of the knee was more loaded. Although the predicted forces agree well with those found with other methods, we think that the model is best used to measure the direction of influence of specific factors.     

Influence of T-shift capsulorrhaphy on rotation and translation of the glenohumeral joint: An experimental study

To evaluate changes in the response of capsuloligamentous restraints to translatory forces and rotation torques caused by experimental capsulorrhaphy (T-shift modification of Bankart repair), eight cadaveric shoulders were tested. Measurements were taken in intact and vented specimens, after severance of the anterior capsule at the glenoid rim (creating an artificial Bankart lesion), T-shaped incision of the anterior capsule, and refixation of the capsule (with a standard Bankart procedure) combined with tightening by T-shift. Rotation torques and translatory forces were applied in different positions of abduction with a specifically designed mounting apparatus that had four degrees of freedom. Dynamic and static measurements were performed with a tracking sysem that had six degrees of freedom. T-shift capsulorrhaphy restored the resistance of the capsuloligamentous restraints to translatory forces in all directions. This restoration was confirmed when we compared these results with data obtained from intact joints. No significant alteration of the centering mechanism resulting from rotation torques was observed, although the extent of external and internal rotation was remarkably decreased. This T-shift modification seems to produce a symmetric reduction of the volume of the capsule without significant displacement of the humeral head.     

关节镜下前交叉韧带重建的远期疗效

目的观察关节镜下重建双股半腱肌腱重建膝前交叉韧带(ACL)的远期疗效。方法回顾分析1990年4月-1997年6月间收治并且得到随访的21例ACL损伤后采用关节镜下双股半腱肌腱重建ACL的患者。对其术前和近期的症状、体征及Lysholm膝关节评分的情况进行分析。结果随访98-168个月,平均127．7个月。21例术前弹响、交锁和打软腿的症状均消失,浮髌试验均为阴性,均无过伸痛。关节轻度疼痛11例,Lachman征阳性3例,前抽屉试验阳性8例,但均无关节不稳。无取腱造成的其它并发症。Lysholm膝关节评分由术前(47．4±10．2)分提高到随访时的(76．7±13．7)分。结论采用双股半腱肌腱重建ACL的手术方式是可行的,长期观察疗效肯定。但随着时间的延长,移植肌腱的强度也会有所下降。     

A geometrical model of vertical translation and alar ligament tension in atlanto-axial rotation

Introduction

While allowing the greatest range of axial rotation of the entire spine with 40° to each side, gradual restraint at the extremes of motion by the alar ligaments is of vital importance. In order for the ligaments to facilitate a gradual transition from the neutral to the elastic zone, a complex interaction of axial rotation and vertical translation via the biconvex articular surfaces is essential. The aim of this investigation is to establish a geometrical model of the intricate interaction of the alar ligaments and vertical translatory motion of C1/C2 in axial rotation.

Methods

Bilateral alar ligaments including the odontoid process and condylar bony entheses were removed from six adult cadavers aged 65–89 years within 48 h of death. All specimens were judged to be free of abnormalities with the exception of non-specific degenerative changes. Dimensions of the odontoid process and alar ligaments were measured. Graphical multiplanar reconstruction of atlanto-axial rotation was done in the transverse and frontal planes for the neutral position and for rotation to 40° with vertical translation of 3 mm. The necessary fibre elongation of the alar ligaments in the setting with and without vertical translation of the atlas was calculated.

Results

The mean diameter of the odontoid process in the sagittal plane was 10.6 mm (SD 1.1). The longest fibre length was measured from the posterior border of the odontoid enthesis to the posterior border of the condylar enthesis with an average of 13.2 mm (SD 2.5) and the shortest between the lateral (anterior) border odontoid enthesis and the anterior condylar enthesis with an average of 8.2 mm (SD 2.2). In graphical multiplanar reconstruction of atlanto-axial rotation to 40° without vertical translation of C1/C2, theoretical alar fibre elongation reaches 27.1% for the longest fibres, which is incompatible with the collagenous structure of the alar ligaments. Allowing 3 mm caudal translation of C1 on C2 at 40° rotation, as facilitated by the biconvex atlanto-axial joints, reduces alar fibre elongation to 23.3%.

Conclusion

The biconvex configuration of the atlanto-axial joints is an integral feature of the functionality of upper cervical spine as it allows gradual vertical translation of the atlas against the axis during axial rotation, with gradual tensing of the alar ligaments. Vertical translation on its own, however, does not explain the tolerance of the alar ligaments towards the maximum of 40° of rotation and is most likely synergistic with the effects of the coupled motion of occipitocervical extension during rotation.     

Comparison of the ACL and ACL graft forces before and after ACL reconstruction an in-vitro robotic investigation

Background?Long-term follow-up studies have indi-cated that there is an increased incidence of arthrosis following anterior cruciate ligament (ACL) reconstruc-tion, suggesting that the reconstruction may not repro-duce intact ACL biomechanics. We studied not only the magnitude but also the orientation of the ACL and ACL graft forces

Methods?10 knee specimens were tested on a robotic testing system with the ACL intact, deficient, and recon-structed (using a bone-patella tendon-bone graft). The magnitude and orientation of the ACL and ACL graft forces were determined under an anterior tibial load of 130?N at full extension, and 15, 30, 60, and 90° of flexion. Orientation was described using elevation angle (the angle formed with the tibial plateau in the sagit-tal plane) and deviation angle (the angle formed with respect to the anteroposterior direction in the transverse plane)

Results?ACL reconstruction restored anterior tibial translation to within 2.6?mm of that of the intact knee under the 130-N anterior load. Average internal tibial rotation was reduced after ACL reconstruction at all flexion angles. The force vector of the ACL graft was significantly different from the ACL force vector. The average values of the elevation and deviation angles of the ACL graft forces were higher than that of the intact ACL at all flexion angles

Interpretation?Contemporary single bundle ACL reconstruction restores anterior tibial translation under anterior tibial load with different forces (both magni-tude and orientation) in the graft compared to the intact ACL. Such graft function might alter knee kinematics in other degrees of freedom and could overly constrain the tibial rotation. An anatomic ACL reconstruction should reproduce the magnitude and orientation of the intact ACL force vector, so that the 6-degrees-of-freedom knee kinematics and joint reaction forces can be restored.     

The effects of protein deficiency and fluoride on bone mineral content of rat tibia

Summary This study examined the effects of chronic protein deficiency and fluoride administration (10 mg/kg/day), separately or in combination, on rat tibia properties. Protein deficiency increased the bone fluoride concentration and reduced the bone mineral content (BMC) especially at the proximal or growing end which contains mainly cancellous bone. Fluoride administration also reduced BMC, but to a lesser extent, and it resulted in proximal tibia fluoride concentrations that were nearly twice those of the distal tibia. The interaction between fluoride administration and the protein content of the diet on BMC was nonsignificant, suggesting that the effects were additive, not multiplicative or synergistic. Fluoride administration, but not protein deficiency, increased bone magnesium levels. It is hypothesized that the reduction in BMC in the areas where the fluoride concentrations were the highest was due to a localized toxic effect of fluoride.