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Background: Handball is one of the most popular team sports in Germany, as well as one of the most dangerous ones. Injury rates in Germany are higher amongst handball professionals than in soccer, with the knee being the most commonly injured joint. To prevent injuries, a functional inert stability is necessary, but definitions and objective measures are lacking., Objectives: Establishing valid reference data of functional knee stability in amateur handball players with use of an established test battery giving objective measures METHODS: 261 athletes (f:130; m:131), mean age 25.1 ± 5.8 y were screened during the preseason. The test battery consisted of double and single-leg counter movement jumps, balance tests, agility, parkour, quick feet test and plyometric jumps., Results: Significant differences between males and females were noted in regard to balance scores (favour for females p ≤ 0.001), as well as jump height, agility and speed tests (favour for males [p ≤ 0.002-0.001])., Conclusion: The noted differences once again bring focus to the interindividual presence of risk factors, because female and male handball athletes have gender-specific ground levels. These attributes have to be considered in further screening and prevention programs, as well as in the context of the return-to-sports decision after injury. The given data may serve as objective reference measures.

Anterior cruciate ligament ruptures represent serious injuries for athletes which are often associated with accompanying injuries and lead to relevant kinematic alterations in the femorotibial roll-glide mechanism of the knee joint. Instability resulting in recurrent giving way events, as well as instability-related meniscal and cartilage lesions can cause functional long-term impairment that may limit the athlete's career. Anterior cruciate ligament replacement is therefore considered to be the gold standard for recovery of physical performance and to prevent secondary meniscal and cartilage damage. Continuous changes in the reconstruction of the anterior cruciate ligament have led to a variety of different methods, including graft choice, fixation devices and surgical techniques, which support the consideration of individual requirements of the athlete as well as sport-specific aspects. One of the main factors for restoring stability and the physiological kinematic roll-glide mechanism of the knee is an anatomical tunnel placement as well as a stable graft fixation in the tibia and femur. By achieving of these fundamental technical requirements an early functional rehabilitation and accelerated recovery of neuromuscular skills, strength and coordination can be achieved, so that an early return to sport activities is possible.

Background: In the context of acute knee dislocations, suture repair of ruptured cruciate ligaments leads to good clinical results in 80% of cases. Disadvantages are low primary stability and subsequently secondary elongation of the sutured ligaments. In the present study, we compared primary stability of suture repair, reinforced by different suture augments, to cruciate ligament reconstruction., Objective: The concept of ligament bracing with transosseous suture repair of the cruciate ligaments and additional suture augmentation is biomechanically superior to cruciate ligament reconstruction., Material and Methods: A total of 42 porcine knee joints divided into seven groups were examined. The stability of four different suture/augmentation combinations were compared to cruciate ligament reconstruction with human hamstring tendons. The investigational setup consisted of testing 1000 cycles with 20 N to 154 N load in a.-p. translation and 60° flexion. Elongation and load to failure were measured., Results: Neither reconstruction (3.13 ± 1.65 mm; 362 ± 51 N) nor augmented suture repair (1.89-2.5 mm; 464-624 N) achieved the primary stability of the intact cruciate ligament (0.63 ± 0.34 mm, 1012 ± 91 N). In comparison to ligament reconstruction, all four augmented suture repairs showed minor elongation in the cyclic test and a higher load to failure. The isolated suture repair showed poor results (6.79 ± 4.86 mm, 177 ± 73 N)., Conclusion: Augmented suture repair provides significantly higher stability compared with isolated suture repair and reconstruction with hamstring tendons. The concept of ligament bracing could be a promising future treatment option in acute knee dislocations. Clinical results remain to be seen.

Background: Press-fit fixation of hamstring tendon autografts for anterior cruciate ligament reconstruction is an interesting technique because no hardware is necessary. This study compares the biomechanical properties of press-fit fixations to an interference screw fixation., Methods: Twenty-eight human cadaveric knees were used for hamstring tendon explantation. An additional bone block was harvested from the tibia. We used 28 porcine femora for graft fixation. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclic loading were investigated., Results: The maximum load to failure was 970±83 N for the press-fit tape fixation (T), 572±151 N for the bone bridge fixation (TS), 544±109 N for the interference screw fixation (I), 402±77 N for the press-fit suture fixation (S) and 290±74 N for the bone block fixation technique (F). The T fixation had a significantly better maximum load to failure compared to all other techniques (p<0.001)., Conclusion: This study demonstrates that a tibial press-fit technique which uses an additional bone block has better maximum load to failure results compared to a simple interference screw fixation.

An injury of cruciate ligament is one the most common knee injuries. This accident happens mostly without external impact and towards the end of training and competition sessions. Women, especially athletes playing team sports ball games such as soccer or disciplines such as tennis, are affected 2 to 8 times more often than men. Anatomic, biomechanical and endocrinological differences are currently discussed as potential risk factors. In terms of prevention, biomechanical impact is of greatest importance given its influenceability through various training opportunities. Training programs including endurance aspects, strengthening knee musculature, balance as well as plyometric trainings were most effective. Further studies should focus more on concomitants of course of injuries., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Problems related to the use of interference screws for fixation of bone-patellar tendon-bone grafts for anterior cruciate ligament (ACL) replacement have led to increasing interest in press-fit techniques. Most of the described techniques use press-fit fixation on either the femoral or tibial side. Therefore an arthroscopic technique was developed which achieves bone-patellar tendon-bone graft fixation by press-fit on both sides without the need for supplemental fixation material., Methods: The first consecutive 40 patients were examined clinically with a KT-1000 arthrometer and radiologically after a mean of 28.7 months (range 20-40 months) postoperatively., Results: The mean difference in side-to-side laxity was 1.3 mm (SD 2.2 mm) and the results according to the International Knee Documentation Committee (IKDC) score were as follows: 7 A, 28 B, 5 C, 0 D., Conclusions: The presented press-fit technique avoids all complications related to the use of interference screws. It achieves primary stable fixation of the bone-patellar tendon-bone graft thereby allowing early functional rehabilitation. However, fixation strength depends on bone quality and the arthroscopic procedure is demanding. The results showed reliable stabilization of the operated knees.

Unlabelled: Hamstring and patella tendons are usually used for anterior cruciate ligament (ACL) reconstruction and fixed with foreign material, partially executed far from the original point of insertion. Besides the biomechanical questions bone defects are a severe problem in cases of revision. We developed a biological method with diamond cutting instruments for graft fixation with bone dowels near the native insertion. The graft is tensioned and fixed in 120 degrees knee flexion and is self-adapting in extension. The technique has been used in a large number of cases during a prospective study with a follow-up of 10 years for patella tendon and 4 years for hamstring tendon grafts. In this investigation 124 patients with bone-patellar tendon-bone (BPTB) grafts showed an International Knee Documentation Committee (IKDC) score A/B in 87% after a mean follow-up of 9.6 years, a Lachman test (maximum side-to-side difference) of 1.38+/-0.93 mm and a negative pivot shift test in 91% of the cases. Of the 147 patients with hamstring tendon grafts 89% had an IKDC score A/B after a mean follow-up of 4.3 years, a Lachman test of 1.14+/-0.76 mm and no pivot shift in 90% of the cases. The Tegner activity score decreased by -1.8 in both groups., Conclusion: This method allows a reliable biological press-fit fixation for every kind of graft near the original point of insertion, preventing bone defects, allowing early intensive rehabilitation and low costs.

Background: Reconstruction of the anterior cruciate ligament (ACL) is a widely used procedure, but up to now no results have been published on an implant-free technique using a quadriceps tendon autograft and press-fit fixation., Methods: A total of 112 patients with primary rupture of the anterior cruciate ligament were included in a prospective case control study and 106 patients could be evaluated postoperatively after a mean of 12.4 months (range 12-14 months)., Results: The patients showed good to excellent results according to the Lysholm score in 81% and the International Knee Documentation Committee (IKDC) score in 86% of cases. Furthermore the anterior-posterior translation was less than 3 mm in 83% of the patients by testing with the KT-1000 arthrometer. Neither tunnel widening nor an increase of radiological joint degeneration was recorded by radiological examination., Conclusion: Reconstruction of the ACL with an autologous quadriceps tendon and an implant-free technique yielded good results compared to established operative methods in the short-term and should be consistently followed-up for long-term confirmation.

Press-fit fixation of anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. A total of 168 cadaveric human patellar, quadriceps and hamstring tendons (average age 49.2 +/- 18.5 years) were used and 15 different fixation methods were tested. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were compared. Some techniques showed comparable biomechanical qualities to interference screw fixation. All investigated double bundle fixation techniques were equal in terms of maximum load to failure, stiffness and elongation. All techniques exhibited greater elongation during initial cyclical loading. Some of the press-fit fixation techniques investigated exhibited comparable biomechanical properties and preconditioning of the constructs is critical. Press-fit fixation enhances tendon to bone contact at the entry of the bone tunnel to the joint.

Aim: ACL rupture is more common in females than in males. The injury can result in chondral and meniscal damage or chronic instability. Most often ACL rupture occurs during landing after throwing and jumping in ball sports. Many studies have reported on incidence, mechanism of injury and predisposing factors in professional athletes. In contrast, we have investigated the impact of mass sports on predisposing factors for the female ACL rupture., Method: In an empirical analytical study leg-axis dynamics, proprioception and foot load of 44 women participating either in regular mass sports or in no sports were investigated by video analysis and on the Biodex-Stability Platform., Results: Our study demonstrates that mass sports improves proprioception of the knee joint. Non-sportive subjects had an increased valgus leg axis during landing in comparison with mass sport participants., Conclusion: Here, we show to the best of our knowledge for the first time that moderate sports activity has a positive effect on predisposing factors of the female ACL rupture. We conclude that prevention programmes focussed on jumping and proprioception can lower the incidence of female ACL ruptures.

Disturbed kinematics of the knee plays an important role in early failure of a unicondylar knee prosthesis (UNI). Recent studies on kinematics have shown that an intact anterior cruciate ligament (ACL) is important for a successful UNI. In this study, in vivo fluoroscopic analysis of knee kinematics was performed for 30 patients with a successful medial UNI implanted with the use of minimally invasive technique. The three-dimensional data of the CAD model were used for evaluating the sagittal translation as well as the axial rotation during deep knee bending and one gait cycle. The anteroposterior translation for flexion was, on average, -5.3 mm (-15.7-3.3; standard deviation 5.3). In most cases, the contact point was more posterior compared with the normal knee. During gait, the average anteroposterior translation was 0.8 mm, which is comparable to that of the normal knee. Axial rotation for deep knee bending was, on average, 8 degrees (-1.3-22.0; standard deviation 5.7), whereas 28 of the 30 knees showed normal axial rotation. During gait, an average axial rotation of 0.94 degrees was observed. The kinematic pattern of each of the subjects did not replicate the average pattern in most of the patients. An insufficient ACL may be suspected as the cause of the pathological kinematic pattern observed in some of these patients.

Aim: This neurophysiological study is intended to investigate the sensomotor potential of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) which may provide joint stabilization via a ligamentomuscular reflex arch. In addition, the role of ligamentous injury on the sensomotor potential has been investigated., Method: The sensomotor potential was investigated using 24 knee joints in a sheep model under in-vivo conditions. The cruciate ligaments were mechanically loaded and the muscular activities of the hamstrings and the quadriceps were recorded simultaneously via electromyography. Injury to the ligaments was simulated by defined mechanical elongation of the ACL and PCL to failure., Results: The results confirm the hypothesis of the existence of a ligamentomuscular reflex loop between ligamentary mechanoreceptors and the joint-stabilizing muscles. Mechanical loading of the ACL triggered mainly the activity of the hamstrings, whereas loading of the PCL led to the activation of the quadriceps. The rate of elongation which caused disturbances to the sensomotor potential was significantly smaller as compared to the elongation to failure., Conclusion: The cruciate ligaments provide dynamic joint stabilization via a ligamentomuscular reflex arch. It was demonstrated that the sensomotor potential of both structures is significantly more susceptible to ligament injury than the biomechanical potential.

Purpose: The purpose of this study was to investigate press fit femoral fixation of hamstring tendons and to compare the mechanical properties with press fit patellar tendon bone (PTB) fixation., Methods: The PTB and hamstring tendons of 30 human cadavers (age: 55.8+/-18.0 years) were used as grafts. An outside-in press fit fixation with a knot in the semitendinosus and gracilis graft (SG-K) and an inside-out (SG-BI) and an outside-in fixation (SG-BO) with the tendons looped over a bone block were compared with a bone-patellar tendon (PT) press fit fixation in 30 bovine femora. The angle between the direction of force and bone tunnel was 60 degrees. The constructs underwent 20 cycles of loading between 60 and 260 N. Constructs were loaded until failure at a speed of 1 mm/sec. Graft fixation was analyzed in terms of maximum load to failure, stiffness and elongation during cyclic stretching. A video analysis of length changes was investigated., Results: There was a significant difference in the maximum load to failure. The SG-BI fixation was inferior to the other three techniques (Mann-WhitneyU-test, P<0.01). There was no difference in stiffness between the techniques. Length changes of PT-fixation from the first to the fifth loading cycle were significantly smaller compared with all other groups (0.73+/-0.58 mm). There was no significant difference between the groups from the 15th to the 20th cycle of cyclic loading., Conclusions: Press fit fixation of hamstring grafts is technically challenging. However, pull-out forces for SG-O and SG-K were equivalent to BPT-graft fixation. Adequate preconditioning for all hamstring tendon press fit techniques is crucial.

Various graft choices have evolved over the past few decades for the primary reconstruction of the anterior cruciate ligament (ACL). Three predominant autologous graft choices exist today: patellar, hamstring, and quadriceps tendons. Clinical studies have as yet failed to demonstrate significant differences in clinical outcome among these grafts, irrespective of their varying fixation techniques. Therefore, other factors such as graft harvest morbidity have become more important when comparing different grafts. These factors can differ substantially between the grafts, depending on the type of patients' activities, the injury pattern, and the associated injuries of the knee joint. A basic knowledge of these factors and the parameters that affect the mechanical and biological behavior of the reconstructed ACL can help to find the appropriate graft choice for each individual patient. Factors such as harvest site morbidity, fixation techniques, osseous integration, and tunnel widening are discussed based on current clinical and basic science studies. Finally, an outlook is given for future alternatives with evolving techniques for tissue-engineered grafts, allografts, or the transplantation of xenogeneic donor tissue.

The "Frankfurt rehabilitation regimen" following anterior cruciate ligament reconstruction is presented. ACL rehabilitation is discussed in the light of knowledge on knee biomechanics and proprioception as well as clinical results of reconstruction. Special emphasis is given to exercise therapy.

This experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws. We used 15 porcine tibia specimens for the study. In the BPTB group, the 10 x 25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7 x 25-mm titanium interference screw (n = 5) or a biodegradable screw (n = 5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7 x 25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA. Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492 +/- 30 N) than BPTB grafts (658 +/- 98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403 +/- 141 N/mm vs 3500 +/- 1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82 +/- 35 N load in the hamstring group and at 428 +/- 135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36 +/- 0.25 mm in the BPTB and 2.58 +/- 1.08 mm in the hamstring group. The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.

The aim of the study was, to assess the influence of a knee brace on the development of anterior instability after anterior cruciate ligament rupture and to test aptitude for physical strain. 46 subjects with arthroscopically proven anterior cruciate ligament rupture were divided equally in a randomised order into two groups. Both groups carried out a standardized physical therapy program, while one group (0) received additional stabilization by means of a functional knee brace (SofTec, Bauerfeind). In addition, important features of the brace (stabilization capacity, safety perception and physical performance) were tested and compared to the non-braced contralateral leg among 23 healthy physical education students by means of a standardized scaled questionnaire (observational study). 0 showed lower (p < 0.05) development of the anterior instability by 46 % and lower (p < 0.05) reduction in circumference of the femur muscles by 25 %. Increasing the time interval between accident and beginning of the brace treatment, increased the difference of the therapeutical effect of the brace. In the observational study, the brace received a better evaluation regarding all test parameters. The reduction of developing anterior instability by means of a brace should facilitate - apart from an individual operation-time-arrangement - especially a conservative approach within the framework of anterior instability and physical activity. Aside from the improvement of the mechanical stabilization, indications for suitability in strain situations could be detected for the tested brace.

ACL reconstruction with patellar tendon autograft is a standard procedure which can be performed arthroscopically with a femoral half tunnel drilled from the joint or using the two-tunnel technique with medial miniarthrotomy and additional femoral approach. The arthroscopic procedure with single incision was supposed to increase stability and to improve proprioception by earlier rehabilitation. 29 patients with ACL deficiency were included in the study. 15 patients were treated endoscopically, 14 patients by using the two-tunnel technique. Proprioception, Lysholm and Tegner scores as well as stability (KT-1000) were assessed preoperatively, 3 and 6 months postoperatively. A deficit of proprioception was assessed in either group preoperatively, which could be improved after 3 months only in the arthroscopic group. 6 months postoperatively, either group showed a restitution of proprioception near full extension and full flexion of the knee. In the mid range position, the proprioception could not be restored. There were no differences in stability and the Lysholm and Tegner scores between the groups after 6 months postoperatively. The comparison between the patients with acute and chronic instability shows a better proprioception in the acute group in the mid range position 6 months after the reconstruction.

The purpose of the study is to establish data on the stability of an ACL replacement. In 40 human cadaver knees, either a mid patellar ligament third with a trapezoid bone block on one side was fixed on the femoral side in a 2-diameter drill hole, or a conventional interference screw fixation was applied. Average primary stability amounted to 570 N (+/- 100 N) for the bone-blocking technique, and to 402 N ( +/- 79 N) for the interference screw fixation. When statistically tested by variance analysis, stability was significantly higher for the bone blocking technique than with interference screw fixation (p < 0.05). Thus, when using a mid-patellar ligament third for ACL reconstruction, the new implant-free technique described here appears to be a practical and reliable method for femoral graft fixation.

Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to the original ACL insertion sites increases anterior knee stability and graft isometry. Hamstring tendon fixation techniques using interference screws offer this possibility. To reduce the risk of graft laceration, a round threaded titanium interference screw (RCI) was developed. To improve initial fixation strength, fixation techniques for hamstring tendons with separate or attached tibial bone plugs were introduced. However, data on fixation strength do not yet exist. With respect to the proposed advantages of biodegradable implants, like undistorted magnetic resonance imaging, uncompromised revision surgery and a decreased potential of graft laceration during screw insertion, we performed pullout tests of round threaded biodegradable and round threaded titanium interference screw fixation of semitendinosus (ST) grafts with and without distally attached tibial bone plugs. Data were compared with bone-tendon-bone (BTB) graft fixation using biodegradable and conventional titanium interference screws. We used 56 proximal calf tibiae to compare maximum pullout force, screw insertion torque, and stiffness of fixation for biodegradable direct ST tendon and bone plug fixation (group I: without bone plug, group II: with bone plug) versus titanium interference screw fixation (group III: without bone plug, group IV: with bone plug). A round threaded biodegradable poly-(D, L-lactide) (Sysorb) and a round threaded titanium interference screw (RCI) were used. As a control calf bone-tendon-bone (BTB) grafts fixed with either poly-(D, L-lactide) (group V) or conventional titanium (group VI) interference screws were used. ST tendons were harvested either with or without their distally attached tibial bone plugs from human cadavers and were folded to a three-stranded graft. Specimen were loaded in a material testing machine with the applied load parallel to the long axis of the bone tunnel. Maximum pullout force of ST bone plug (group III: 717 N +/- 90, group IV: 602 N +/- 117) fixation was significantly higher than that of direct tendon (group I: 507 N +/- 93, group III: 419 N +/- 77) fixation. Maximum pullout force of biodegradable screw ST fixation was higher than that of titanium screw fixation in both settings. There was no significant difference in pullout force between biodegradable (713 N +/- 210) and titanium (822 N +/- 130) BTB graft fixation or between ST fixation with bone plug and biodegradable screw with BTB fixation. Pullout force of hamstring tendon interference screw fixation can be improved by using a biodegradable implant. In addition, initial pullout force can be greatly improved by harvesting the hamstring tendon graft with its distally attached tibial bone plug. This may be important, especially in improving tibial graft fixation. This study encourages further research in tendon-bone healing with direct interference screw fixation to confirm the potential of this advanced method.

The purpose of the present study is to evaluate the rehabilitation of different treatments of ACL ruptured knees by means of gait parameters. The gait analysis results in two surgically treated patient groups (patellar tendon autograft reconstructions (n = 35) and augmented repairs (n = 15) and one non-surgically treated patient group (n = 19) are evaluated by means of gait parameters of normal controls (n = 30). The technical equipment included an optoelectronic system for recording the kinematics of gait (Primas, NL) and two force plates for measuring the ground reaction forces (Kistler, CH). The moments acting on joints can be determined experimentally with both systems. It can be shown from special gait tests that the derived quantitative evaluation parameters are independent from the gait analysis conditions. One year after surgery, both the patellar tendon autograft reconstruction group and the augmented repair group show clear deficiencies in gait parameters compared with the controls. In particular this concerns the midstance extension motion of the knee (p < = 0.01) and the extension moments acting on the knee joint during the stance phase (sagittal plane, p < = 0.01). The deficiencies of both surgically treated groups are approximately the same. However, one year after occurrence of the disruption the non-surgically treated group cannot be distinguished from the controls. From this and from additional pre-surgical measurements, it can be concluded, that operating has an important influence on gait parameters. The role of the gait analysis results has been discussed.

Sensomotory function after ACL-reconstruction was tested prior and after a proprioceptive rehabilitation program with the Kinesthetic Ability Trainer (KAT 2000) which documented the static balance index (SBI). A control group consisting of healthy subjects was also tested two times with a time interval of six weeks. The results showed an adaptation effect to the testing device in the control group with an 17.12% increase of the SBI. There were no differences between the dominant and non dominant extremity. The active sensomotory function in the healthy knee of the operated patients showed no difference to the control group. Proprioceptive capabilities of the acl-reconstructed knee joints was significant reduced 6.42 weeks after surgery. A special proprioceptive rehabilitation program for six weeks significantly reduced this deficit. In the patient group sensomotory function of both knee joints could be increased to a level higher than in the control group. In the operated extremity the static balance index increased 27.75% and in the non injured extremity the SBI increased 16.88%.

In 15 male healthy volunteers and 10 male patients with ACL-deficiency sports specific capabilities were evaluated with a 9-3-6-3-9-run and a single-leg jumping test. Each subject was tested with and without different knee bandages. We evaluated the Patelladyn-, the Kasseler-, the Super-Genuplus-, and the Genuhit-bandage. Additionally a subjective assessment of each bandage was performed by the volunteers. There were no significant difference performing the 9-3-6-3-9-run between all of the bandages in the control-group. Comparing the injured group with the control there were significant differences. All bandages led to improvement without reaching the running time, which was used by the controls. Performing the single leg jumping test there were also no differences with the different bandages in the healthy control group. However, after applying a bandage in the injured subjects, the time improved significantly. In the subjective assessment the Patelladyn-bandage scored best.

This retrospective study shows the results in 30 patients of revision surgery on their reruptured ACL. The follow-up time was 30 months on average (range 10-54 months). The follow-up examination included subjective (Lysholm score, Tegner activity level rating score), clinical and radiological criteria and also instrumental laxity testing with the KT-1000 arthrometer. The overall evaluation was done according to the IKDC score. The follow up showed subjective and objective results almost equal to those after primary surgery on ACL. The IKDC score revealed certain abnormal and highly abnormal results, which demonstrated that revision ACL surgery gives poorer results than primary surgery. Nevertheless, we recommend reconstruction of a torn ACL even in a revision case to restore the knee function and prevent further menisceal and chondral damage and degeneration.

In 30 healthy volunteers with clinically inconspicuous knee joints the proprioception of the knee joint was evaluated by an angle reproduction test. With the same set-up we documented the effect of an elastic knee bandage. We could not document any differences between the left and the right knee joint or between men and women, but at the mid-range of motion, proprioception was worse compared to the end range of motion. The applied elastic knee bandage significantly improved the position sense. Additionally 25 patients with an isolated rupture of the anterior cruciate ligament were evaluated. Fourteen patients were examined preoperatively 11 after operative ACL reconstruction. Preoperatively proprioception was significantly poorer than in the control group. We were able to show a positive influence of a knee bandage on the proprioception of the injured knee as well. Patients after ACL reconstruction showed no significantly better proprioception than the preoperative group.

In acute anterior cruciate ligament (ACL) lesions with effusion of the knee joint it is often difficult to realize a positive Lachman sign. It was suggested that the tension of the joint capsule may reduce tibial displacement although the ACL is completely disrupted. In 10 cadaver knee joints the ACL was dissected and the capsule was closed again. By a canula the knee joints were filled with isotonic saline solution in steps of 20 ml up to 100 ml. Before and after dissection of the ACL and during filling the joint we measured the anterior tibial displacement by use of the MEDmetric KT 1000 arthrometer. In a second series we examined 5 patients with acute effusion of the knee joint before and after puncture of the effusion. We detected the electromyographic activity of the quadriceps muscle end and the hamstrings during the KT 1000 test and patellar reflex. In the cadaver tests we found no reduction of the anterior tibial translation while filling the joint with saline solution. The electromyographic examinations showed a reflectory action in the quadriceps muscle and in the hamstrings when the Lachman test was performed. In the quadriceps muscle the electromyographic amplitude was reduced after puncture; the hamstrings showed a drastically reduced amplitude and duration of the signal. When patellar reflex was performed we recorded an electromyographic action in both muscle groups, too. Puncture could only reduce the signals of the hamstrings. Our results suggest that the reduction of the anterior drawer and the Lachman test in acute effusion is caused not mechanically by the tension of the capsule but by a reflectory muscle action of the hamstrings.

In a prospective clinical study conducted on 50 patients with isolated insufficiency of the anterior cruciate ligament (ACL), we investigated the triggering of pivot shift as a function of the position of the hip joint and the rotational position of lower leg; the results were compared with those yielded by the Lachman test. The pivot shift phenomenon was found to be more readily triggered when the hip was abducted, and especially when the investigator had specified external rotation of the lower leg at the same time. Our results show that this modification of the classic pivot shift test can fill a diagnostic gap in the clinical investigation. The pivot shift test with hip abduction and external rotation of the lower leg is a valuable alternative test for the diagnosis of ACL insufficiency.

The rupture of the anterior cruciate ligament (ACL) near its femoral origin is a common injury of the knee and can lead to lesions of the meniscus due to instability and to early gonarthrosis. One procedure applied in current orthopaedic practice to prevent such impairment of knee joint function is ACL repair reinforced with a synthetic intraarticular ligament. In this study we used twelve knees of cadavers and after sectioning the ACL in each repaired it according the Marshall technique with USP 1 PDS II sutures. We augmented the repair in each case with a 3-mm PET (Trevira hochfest) band inserted by the through-the-condyle (TTC) procedure and attached without preload to the femoral and tibial condyle with a 4-mm staple. We then measured the length of the ACL, the length of the Marshall sutures-ACL complex, the partial lengths, and the deviation angles and adherence-friction force of the 3-mm PET augmentation device, and applied the law of Hooke to calculate the load-sharing between the USP 1 PDS II sutures-ACL complex and the 3-mm PET band and between the ACL and the 3-mm PET band, respectively. We also evaluated the load on the femoral and the tibial fixation of the augmentation device. The results showed that the 3-mm PET band took over 60% of an externally applied load on the knee during the hypothetic period of ACL healing and 27% of the force acting on the knee thereafter. It was calculated that a maximum of 75% of the load taken over by the augmentation device was at the tibial staple and only up to 45% of the force at the femoral one. With due consideration for the requirement for absolute protection ("stress shielding") of the healing ACL but also for the aim of early postoperative accelerated functional rehabilitation without casts, splints or other restrictions of joint movement, we believe that a pretensioned 3-mm PET band is the best choice, since augmentation without preload cannot fulfil these requirements.

Introduction: Stäubli postulated a clinical significance of lesions to the popliteus system because of a 95% incidence in acute and 85.7% in chronic ruptures of the cruciate ligaments. The sparse clinical literature on this topic favours conservative or operative treatment as well., Objective of the Study: What is the significance of isolated lesions of the popliteus tendon on translational stability of the knee joint?, Material and Methods: The popliteus tendon was severed in six sheep. One year postop. the knee joints were evaluated by means of x-ray, biomechanical testing, computed tomography osteoabsorptiometry (CTOAM) and micromorphology., Results: There were no pathological findings on x-ray. The simulation of the trauma situation ex vivo showed no instability whereas increased translation and progressive loosening of secondary stabilizers was found after one year (posterior and total aptranslation, compliance index p < 0.05). The position of the density maxima of the subchondral mineralization are about the same on the operated and the non-operated knee joint. All tendons healed macroscopically, but micromorphology exhibited a persisting increase of cross-sectional areas, a low differentiated ultrastructure of the tendon and an increased cellularity (p < 0.01)., Experimental: 1. intraarticular, extrasynovial tendons heal spontaneously even within the synovial environment; 2. healing is defective even one year postop.; 3. the postulate of the significance of the popliteus system for the stability of the knee is proven. Clinical: 1. (isolated) lesions of the popliteus go undetected with clinical and instrumented examination; 2. conservative treatment eventually results in increased posterior translational instability; 3. this will increase strain and load on the menisci and ACL- reconstructions.

For the investigation of the boot-induced anterior cruciate ligament injury and experimental case study with a prototype ski boot was performed. The back spoiler of this boot was designed to yield by only some degrees with a certain level of backward moment. A mechanical switch allowed to activate or to block this mechanism. Ten jumps over a prepared hill with activated and ten jumps with blocked spoiler mechanism were performed in randomised order. During the jump and landing the EMG of eight lower extremity muscles were recorded and synchronised to two S-VHS cameras suitable for 2D-analysis of the angle kinematics. The aim of these experiments was to quantify the muscular and kinematic effects caused by the new spoiler characteristics and also to establish a method for their judgement. For the quantification of the muscular effects an activity quotient was defined and for the analysis of the kinematics the time history of three body angles and their variation between the trials were found to be appropriate. The results of this case study showed an increase of the activity quotient for all observed muscles and a higher accuracy of motion with the activated spoiler mechanism. These findings an be taken as an indication for better muscular joint guiding in the knee and justify a randomised field study using the proposed methods.

Regeneration of ligaments and tendons is a slow process, compared with the healing of other connective tissues (e.g., bone). Healing starts from the surrounding soft tissues ("extrinsic healing"), but also from the ligament or tendon itself ("intrinsic healing"). Regeneration is poor when there is little surrounding soft tissue available, as is the case in the anterior cruciate ligament. Regeneration of the medial collateral ligament of the knee is examined best. Mechanical and ultrastructural properties are not completely normal even 1 year after dissection of the ligament irrespective of whether it was sutured or not. Our own experiments on rabbit anterior cruciate ligaments showed that there is no regeneration after complete transection of the ligament. After incomplete transection there is regeneration, but maximum load of the ligament reaches only about 3/4 of the values of the sham-operated contralateral side. An additional experiment showed that regeneration is significantly better with the application of continuous passive motion, and elongation of the ligament can be avoided. If the healing tissue is not loaded, regeneration results in unstructured scar tissue. Under functional load, the collagen fibers are oriented in a longitudinal direction and the mechanical properties are optimized. There are no fundamental differences in the healing process between tendons and ligaments.

In a long-term follow-up of 88 patients with complex ligament knee injuries we examined 70 of these who were operated upon between 1.4. 1988 and 31.3. 1990. We specifically looked at local complications, clinical results and knee stability, using subjective and arthrometrical (KT-1000) results 1 or 2 years after operation. The only parameters with a good correlation with stability were the clinical examination (Lachman-test) and the results with the arthrometer in the anterior-posterior translation. Stability after ACL-reconstruction with augmentation with a polydiaxonaon (PDS) augmentation band was physiological (2 mm under 89 N anterior-posterior traction) in 77% of all knees but only in 57% under maximal anterior-posterior manual stress. Neither the subjective outcome of Lysholm-Score correlated with arthrometry and clinical examination.

The patellar tendon graft replacing the anterior cruciate ligament undergoes histomorphological and biomechanical changes. From literature we can estimate a force of 200 N to be a critical limit of graft load after ACL-plasty in humans. The comparison with the graft loads under various conditions provided the following conclusions: Unlimited passive motion of the knee joint can be done without risk. Early weight bearing is possible. Active extension exercise against gravity could damage the graft in the range of 0 to 20 degrees of flexion in some patients. A rehabilitation protocol has to regard these biomechanical principles. In a prospective study 74 patients underwent rehabilitation according to the protocol described. An extension contracture of more than 10 degrees was seen in 9 patients. In all cases it was due to a notch-impingement or a cyclops. One year after operation 57 patients had a follow up. The side to side-difference in anterior drawer measured with a KT-1000-arthrometer was less than 2 mm in 45 patients. Six patients had difference between 2 and 4 mm. In six patients the difference was more than 4 mm.

In a prospective study, 153 MRI examinations were performed on 74 patients following reconstruction of a ruptured anterior cruciate ligament with a semitendinosus graft. MRI examinations were performed at three defined intervals (3 months, 4 to 12 months, and 1 to 2 years postoperatively), and the findings were compared to simultaneous clinical tests to define stability criteria. This permitted reliable assessment of the integrity of the ligament graft; in three cases we correctly diagnosed a ruptured graft. A well-defined tendon graft with recognizable fibrous structures correlated with a clinically stable ligament in 98% of the cases. Due to physiological transformation occurring from three months to one year postoperatively, that graft temporarily appears less distinct. Complete integration of the graft with full stability of the knee is visualized in the MRI scan as a tendon with low signal intensity. Postoperative complications and the desire to participate in sports activities are indications for MRI examination.

The KT-1000 arthrometer was used to measure anterior tibial displacement in patients with acute unilateral anterior cruciate ligament (ACL) disruptions. Measurement revealed 11.5 mm absolute displacement on the injured side and 3.6 mm side-to-side difference with the 89 N test, 15.2 mm absolute displacement and 6.1 mm side-to-side difference with the manual maximum displacement test, and 8.5 mm displacement and 2.0 mm side-to-side difference with the active quadriceps test. Chronic anterior instabilities measured 13.0 mm absolute displacement on the involved side and 5.4 mm side-to-side difference with the 89N test, 17.7 mm displacement and 8.6 mm side-to-side difference with the manual maximum displacement test, 10.8 mm displacement and 4.4 mm side-to-side difference with the active quadriceps test. Testing technique, measurements in control subjects without previous knee injuries, and displacement measurements of other authors and other instrumented testing devices are described.

Unlabelled: We tested 4 functional braces for anterior cruciate ligament insufficiency (CTI, Lennox Hill, Ultratech, Proshifter) in vitro and in vivo. In vitro all braces limited the anterior drawer. The maximal anterior drawer was 3.08 mm (CTI), 5.16 mm (Ultratech), 6.25 mm (Lennox-Hill), 7.33 mm (Proshifter). In vivo anterior drawer was controlled at low shear loads (67 N). With high shear loads the anterior drawer was significantly reduced but the tibiofemoral translation was significantly reduced but the tibiofemoral translation was higher than in the uninjured knee. Without brace: 16.25 mm; CTI: 10.15 mm; Ultratech: 12.10 mm; Lennox-Hill: 9.80 mm; Proshifter: 12.75 mm;, Control: 8.05 mm. The active anterior drawer was reduced but not normalized by all braces. Without brace: 8.75 mm; CTI: 5.35 mm; Ultratech: 5.6 mm; Lennox-Hill: 5.45 mm; Proshifter: 6.75 mm;, Control: 4.25 mm. None of the braces tested could control the rotation efficiently.

Ruptures of the anterior cruciate ligament are among the most frequent injuries of the joints. There is no longer any doubt regarding the necessity for surgical intervention. Several clinical and experimental studies suggest that the instability of the knee joint results in an accelerated degeneration of the menisci and cartilage. There are differences of opinion regarding the type of surgical procedures to stabilize the knee-joint. Although there are many different surgical procedures described in various publications, only one technique emerges as the preferred one. This paper will demonstrate different therapeutic concepts, based on the biomechanical background for the treatment of the anterior knee instability. It will consider the morphology of injuries, the demands of the patient and the full range of rehabilitative possibilities. Described herein are the indications and techniques of augmentation, protection and prosthetic replacement.

Anterior cruciate ligament (ACL) injuries are considered of high prevalence in sports medicine and are of socio-economical relevance. Indications for operative treatment and the ability for physical activity after ACL injuries are discussed controversially. Although it is known that the ACL has neurosensory functions, no test system has been developed which takes this biological function into account. The first goal of this study was to determine the neurosensory function after ACL reconstruction, and the second goal was to develop predictive markers for functional results after surgery. 20 healthy athletes (10 male, 10 female) (control group) and twenty ACL deficient patients (10 male, 10 female) (study group) were included in a prospective, controlled study. Electromyograms (EMG) were performed under defined load conditions of the knee. Important results of our study are: 1. Previously described parameters can be reproduced with EMG techniques. Their validity was proved. Typical contraction patterns (m. quadriceps, hamstrings, m. gastrocnemius) for defined load conditions can be recorded. 2. Statistically significant differences can be shown between the control group and the study group as well as between the two legs (injured/noninjured) of the same patient in the study group. 3. The results suggest that the diminished innervation of the m. biceps femoris and m. gastrocnemius in down-ramp-running as an important parameter for ACL deficiency. 4. Distinct differences of innervation patterns of the muscles, which stabilise the knee in downramp walking suggest that despite a subjective stability, altered load conditions may result. Innervation patterns seem to vary from individual to individual. 5. Concluding from our findings, we suggest that clinical methods should be developed to allow a patient-specific assessment of physical activity.

Two femoral fixation areas were defined in the distal iliotibial tract (ITT) system. They were named supracondylar insertion and insertion near the septum. Biomechanical studies on these insertions revealed tension peaks in the insertion near the septum with anterior translation of the knee, with varus stress and rotational movements. We conclude that the fibers inserting here are secondary restraints against anterior and lateral knee instability. 5 lateral extraarticular procedures were investigated to evaluate their biomechanical effect on knee instability. A standardized cadaver knee model was used with two basic experiments: an excentric quadriceps contraction from 0 to 90 degrees of flexion and an anterior translation with 100 N in 30 degrees of flexion. 5 knees were investigated for each procedure. Results from the excentric quadriceps contraction study imply reduced ACL strain with all extraarticular procedures except the Andrews tenodesis. The quantitative effect was related to the mechanical strength of the fixation of the ITT. All lateral procedures reduced ACL strain with anterior translation of the knee. The last part of the study included simultaneous registration of rotation and translation of the knee. We demonstrated a close relation of decreased ACL strain due to a lateral procedure and pathological external rotation of the knee. The knee no longer reached the physiological neutral rotation angle after an effective lateral tenodesis procedure. The significance of this effect is not clear at the present time.

Recent data indicate that the function of the knee joint may be the result of a complex synergy between bones, ligaments, muscles and proprioceptive receptors in these structures. Therefore, it was the aim of this study to investigate if muscular changes could be found more than 5 years following ACL-injury and if there are therapy-dependent differences. 35 patients with ACL-reconstruction and 25 conservatively treated patients were studied. The thigh circumference was measured and in 5 randomly selected patients of each group additionally MRI cross-sections of both limbs were made. Using an isokinetic dynamometer and an EMG device the relation of strength, electrical activity and muscle size were analyzed. Only minimal differences in thigh circumference as well as in muscular cross sections were found between the uninjured and injured limb of both groups; however, the isokinetic torque and iEMG values showed significant differences. It may be assumed that the major reason for these results is a modified muscle fiber utilization in the ACL-injured limb, caused by a changed joint receptor afferent inflow or a compensation of the central nervous system to primary alterations of the muscle fibers.

Using a new rating system (Innsbruck Knee-Sports Rating Scale) 75 patients 5 to 6 years after ACL-injury have been compared to their sports activity (47 patients with ACL reconstruction and 28 conservative treated patients). Under the viewpoint of knee load and especially the demand on stability sports activities have been divided into 3 categories: High Risk, Low Risk and Non Risk Pivoting Sports. Operative therapy shows an advantage in High Risk Pivoting sports (e.g. soccer, basketball) and in Low Risk Pivoting (e.g. running, hiking) sports, expressed by fewer knee related symptoms and higher participation levels. In the Non Risk Pivoting category (e.g. swimming, cycling) good results could also be achieved by conservative therapy. The careful evaluation of each patient's sports activities is therefore an important factor in the decision for the right therapy on one hand, and for comparing the results of different therapy programs or patient collectives on the other.

Following a general review of the basic principles of knee examination, the specific instability tests of the different ligaments are explained. The pathophysiology, the pathomechanic and the diagnostic evidence of these instability tests are shown. The diagnosis of meniscal and cartilaginous lesions are not discussed.

Rehabilitation of the anterior cruciate ligament (ACL) continues to be a topic of intense interest among surgeons and therapists. Numerous experimental studies have demonstrated that motion and a certain amount of stress are necessary for ligament healing. In experimental and clinical studies closed kinetic chain exercises have been proven to be safe already in the early phase of rehabilitation. Since 1987, over 2900 patients who have undergone ACL reconstruction using the central one-third of the bone patellar tendon bone graft have followed our accelerated rehabilitation protocol. Follow-up of the patients reveals early return to athletic activity and maintenance of long-term stability. Our 1987 accelerated rehabilitation program continues to be modified, with less constraints placed on the postoperative patient in our present rehabilitation protocol. Past patient non-compliance to previously established protocols still yielded excellent results that demanded further investigation. Gradually we developed a four-phase rehabilitation protocol. The initial phase encompasses the preoperative period with the goal of resolving swelling and regaining full motion. The second phase involves the initial two weeks post ACL reconstruction and focuses primarily on wound healing, full extension, control of swelling, and leg control. The third phase (two to five weeks) involves increasing flexion, developing a functional gait, and resuming activities of daily living. The fourth phase (> five weeks) identifies a safe return to competitive athletics. With this accelerated rehabilitation protocol a decreased postoperative morbidity was noted without jeopardizing the long term stability of the ACL reconstructed knee.

Trauma to the knee joint with disruption of one or both cruciate ligaments will start a biological response: inflammatory reactions, neurophysiological changes due to disruption of afferent nerve endings, and biomechanical changes which will ultimately lead to instability (functional and mechanical) as well as to early degenerative changes. Treatment, whether operative or non-operative, has to be based on a sound knowledge of biological and biomechanical principles. Cruciate ligament graft positioning, fixation, pre-tensioning, operative technique for reconstruction, and rehabilitation will all have influence on each other. All these factors therefore have to be balanced to achieve good mid- to long-term results.