Katja Tecklenburg

Bony and cartilaginous anatomy of the patellofemoral joint

The patella as the largest sesamoid bone of the human body forms the patellofemoral joint with the patellar groove of the femur. The patellofemoral joint is a complex articulation with high functional and biomechanical requirements. Several anatomical variants of both patella and the trochlea exist. Multiple clinical problems of the knee may be caused by anatomical and physiological abnormalities of this joint. Exact knowledge about the anatomy, the biomechanics and the function of the patellofemoral joint is therefore required to understand its wide range of pathology.

Suspensory Fixation of Grafts in Anterior Cruciate Ligament Reconstruction: A Biomechanical Comparison of 3 Implants

PURPOSE Our purpose was to evaluate the biomechanical difference between 2 new soft-tissue anterior cruciate ligament (ACL) fixation devices (RetroButton [Arthrex, Naples, FL] and ToggleLoc [Biomet, Warsaw, IN]) and a clinically established implant (EndoButton CL; Smith & Nephew, Andover, MA). METHODS In test session 1 biomechanical testing was performed by use of 48 porcine femora fixed to a material testing machine. In session 2 the implants were tested alone. Cyclic loading was carried out for 1,000 cycles, followed by a load-to-failure test. The tested devices were as follows: EndoButton CL, 20-mm and 40-mm loops; RetroButton, 12/20-mm and 12/40-mm loops; and ToggleLoc, 20-mm and 40-mm loops. RESULTS In test session 1 the EndoButton CL showed higher motion per cycle (0.30 +/- 0.09 mm for 20-mm loop and 0.43 +/- 0.03 mm for 40-mm loop) but lower plastic displacement values (0.66 +/- 0.19 mm for 20-mm loop and 0.50 +/- 0.13 mm for 40-mm loop) than the objects of comparison. The RetroButton devices were the stiffest (331.47 +/- 133.92 N/mm for 12/20-mm loop and 265.66 +/- 103.97 N/mm for 12/40-mm loop). The highest ultimate failure load, however, was shown by the EndoButton CL devices. In test session 2 the EndoButton CL oscillated the most. The ToggleLoc devices elongated more than the objects of comparison (0.66 +/- 0.12 mm for 20-mm loop and 0.76 +/- 0.06 mm for 40-mm loop). The RetroButton devices were both the stiffest among the respective implants (542.7 +/- 148.0 N/mm for 12/20-mm loop and 379.0 +/- 40.1 N/mm for 12/40-mm loop). The EndoButton CL showed the highest values for displacement to failure (3.6 +/- 0.4 mm for 20-mm loop and 6.4 +/- 0.4 mm for 40-mm loop). The ToggleLoc devices failed the latest on load-to-failure testing. CONCLUSIONS All tested implants could provide adequate fixation strength. Despite advantages in the design of the EndoButton CL regarding its handling, the 2 newly released products showed superior material properties. CLINICAL RELEVANCE Suspensory fixation of hamstring grafts in ACL reconstruction is frequently associated with bone tunnel enlargement. Material properties and implant design may limit graft-tunnel motion and result in enlargement of the femoral bone tunnel. With improved implant design, suspensory graft fixation may still be an attractive fixation technique in primary and revision ACL reconstruction.

Single-Bundle Anterior Cruciate Ligament Reconstruction: A Biomechanical Cadaveric Study of a Rectangular Quadriceps and Bone–Patellar Tendon–Bone Graft Configuration Versus a Round Hamstring Graft

PURPOSE The purposes of this study were to investigate anterior tibial translation under loading conditions after single-bundle (SB) anterior cruciate ligament (ACL) reconstruction using a rectangular tunnel placement strategy with quadriceps and bone--patellar tendon--bone (BPTB) graft and to compare these data with a SB hamstring reconstruction with a round tunnel design. METHODS In 9 human cadaveric knees, the knee kinematics were examined with robotic/universal force-moment sensor testing. Within the same specimen, the knee kinematics under simulated pivot-shift and KT-1000 arthrometer (MEDmetric, San Diego, CA) testing were determined at 0°, 15°, 30°, 60°, and 90° of flexion under different conditions: intact knee, ACL-deficient knee, and SB ACL-reconstructed knee. For the SB ACL-reconstructed knee, 3 different SB reconstruction techniques were used: a rectangular tunnel strategy (9 × 5 mm) with quadriceps graft, a rectangular tunnel strategy with BPTB graft, and a round tunnel strategy (7 mm) with hamstring graft. RESULTS In a simulated Lachman test, a statistically significant difference was found at 0° and 15° of knee flexion between the rectangular reconstruction with quadriceps graft (5.1 ± 1.2 mm and 8.3 ± 2 mm, respectively) or BPTB graft (5.3 ± 1.5 mm and 8 ± 1.9 mm, respectively) and the reconstruction using hamstring graft (7.2 ± 1.4 mm and 12 ± 1.8 mm, respectively) (P = .032 and P = .033, respectively, at 0°; P = .023 and P = .02, respectively, at 15°). On the simulated pivot-shift test at 0° and 15°, rectangular ACL reconstruction with quadriceps graft (3.9 ± 2.1 mm and 6.5 ± 1.7 mm, respectively) or BPTB graft (4.2 ± 1.8 mm and 6.7 ± 1.7 mm, respectively) showed a significantly lower anterior tibial translation when compared with round tunnel reconstruction (5.5 ± 2.1 mm and 7.9 ± 1.9 mm, respectively) (P = .03 and P = .041, respectively, at 0°; P = .042 and P = .046, respectively, at 15°). CONCLUSIONS Under simulated Lachman testing and pivot-shift testing, a reconstruction technique using a rectangular tunnel results in significantly lower anterior tibial translation at 0° and 15° of flexion in comparison to knees reconstructed with a hamstring SB graft using a round tunnel strategy. CLINICAL RELEVANCE ACL reconstruction with a rectangular tunnel and BPTB and quadriceps tendon might result in better anterior knee stability at low flexion angles than ACL reconstruction with hamstring SB graft and a round tunnel in the clinical setting.

Anterior cruciate ligament injury with simultaneous locked bucket-handle tears of both medial and lateral meniscus in a 19-year-old female professional ski racer: a case report

Acute anterior cruciate ligament deficiency combined with simultaneous locked bucket-handle tears of both medial and lateral menisci have rarely been observed. This case report describes the first case of such a combined knee injury in an athlete including injury mechanism, clinical symptoms, specific signs on MRI, and treatment options.

Factors associated with self-reported failure of binding release among ACL injured male and female recreational skiers: a catalyst to change ISO binding standards?

Background Female recreational skiers have twice the rate of knee injuries and three time the rate of ACL injuries compared with their male counterparts. Female skiers suffering from a knee injury reported a significantly higher proportion of failure of binding release than knee injured male skiers. Purpose To evaluate factors associated with failure of binding release among ACL injured male and female recreational skiers. Study design Cohort study. Methods Among a cohort of 498 recreational skiers (68% females) suffering from an ACL injury (complete rupture or partial rupture), age, sex, height, weight, self-reported skill level and self-reported risk taking behaviour, gear origin, ski length, date of last binding adjustment, perceived speed at the moment of injury, type of fall, and failure of binding release of the ski of the injured knee, were collected by questionnaire. Results Failure of binding release was reported within 78% of cases and was significantly higher for females compared to males (83 vs 66%, p<0.001) with an adjusted OR of 2.7 (95% CI 1.7 to 4.4). A higher perceived speed at the moment of injury was significantly associated with a decreasing proportion of failure of binding release. A slow perceived speed was independently associated with failure of binding release (adjusted OR 2.0; 95% CI 1.2 to 3.5). There was a significantly higher proportion of failure of binding release during backward falling compared to forward falling (87 vs 72%, p=0.002); similarly, a higher proportion of failure of binding release occurred in cases of complete rupture compared with a partial tear of the ACL (81 vs 64%, p=0.001), respectively. Conclusions Among this cohort of ACL-injured skiers, failure of binding release was significantly associated with female sex, a slow perceived speed at the moment of injury and complete rupture of the ACL.

Radiological aspects of injuries of avalanche victims

OBJECTIVE Increasing numbers of avalanche victims with polytrauma have highlighted their need for radiological injury characterisation, which this study examines. METHODS People in Tirol injured by avalanche during 1994-2005 and admitted to the Innsbruck Medical University Hospital were included. Data for this retrospective study were obtained from the Austrian avalanche register and local electronic patient files archive. RESULTS During the observation period 94 avalanche victims in Tirol were admitted to our hospital, and a mean of 1.5 radiological methods were used per person at presentation. A mean of three diagnoses per victim were recorded, of which one was eligible for radiological examination only. Most victims (56%) were diagnosed with hypothermia, followed by unspecific contusion (54%), injuries of ligaments, tendons or muscles (26%) and fracture (23%); 21 victims died in hospital. CONCLUSIONS Emergency radiological examination can discover injuries otherwise not immediately apparent. However, initial use of radiological assessments such as computed tomography for people admitted under cardiopulmonary resuscitation does not always ensure an optimal outcome.

[Impact of Self-Reported Fatigue on ACL Injuries in Alpine Skiing: A Sex Comparison].

INTRODUCTION In recreational alpine skiing, about one third of all injuries affect the knee joint, and the most common diagnosis in adult male and female skiers is a tear of the anterior cruciate ligament (ACL), which makes up 15 - 21 % of all injuries. General preventive recommendations to reduce the incidence of ski injuries include avoiding fatigue. However, it seems unclear to what extent ACL injuries in male and female recreational skiers are related to perceived fatigue. METHODS This study was conducted as a prospective questionnaire-based investigation in two Austrian ski injury clinics during the five winter seasons between 2009/2010 and 2013/2014. In total, 588 skiers (67.9 % females) with a mean age of 42.1 ± 10.9 years were interviewed about demographics, skiing ability, skiing behaviour, fitness, day and time of accident, skiing duration and perceived fatigue at the moment of accident. RESULTS ACL injured males reported a significantly higher skiing ability and fitness level as well as a more risky behaviour on ski slopes compared to females. About one third of males and females injured their ACL within the first day of the ski trip and about 57 % within the first two days, with no sex differences. However, a significantly higher number of female skiers sustained an ACL injury during the first hour of skiing (28 vs. 17 %) as well as during the first two hours of skiing compared to males (52 vs. 44 %). About 81 % of males and females felt no fatigue or just a trace of fatigue in their legs at the time of accident, with no sex differences. CONCLUSION Based on the findings of this study, fatigue does not seem to be a major risk factor for an ACL injury among male and female recreational skiers.

Impact of lowering ski binding settings on the outcome of the self-release test of ski bindings among female recreational skiers

Background and purpose The ability to successfully self-release the ski binding can prevent skiing-related injuries of the lower extremities. Failure of binding release associated with a knee injury is significantly higher among females compared to males. The International Standards Organization ISO 11088 standard for binding setting values allows a lowering by 15% upon request of the skier. Thus, the aim of this study was to evaluate the impact of lowered ski binding settings by 15% on the outcome of the self-release test among female recreational skiers. Materials and methods In this randomized single-blinded study, a cohort of 20 females (24.5±2.7 years) performed the self-release test in the laboratory thrice with each leg under two conditions: 1) with an actual ISO 11088 setting and 2) with a setting lowered by 15%. For each attempt, torques calculated via the force plate were normalized to torques measured by a binding adjustment system (relative release torque, RRT). Results Among 240 trials in total, more females were significantly able to self-release their ski bindings with lowered binding settings when compared to their actual ISO settings (53% vs 9%, p<0.001). Thirteen females (65%) were able to release their bindings at least once with both legs with lowered binding settings compared to only three females (15%) with their actual binding settings (p<0.001). Mean RRT of all failure of binding release trials significantly differed between lowered and actual binding settings (58.6%±22.2% vs 50.5%±20.4%, p=0.003). Conclusion Four times more females were able to self-release their ski bindings at least once with both legs with a 15% lowered binding setting compared to their normal ISO 11088 setting. The fact that the ISO standard accepts a lowering by 15% upon request of the skier could represent an important measure to prevent knee injuries, especially for female recreational skiers.

Ossäre und chondrale Anatomie des patellofemoralen Gelenks

ZusammenfassungChronische Schmerzen im vorderen Kniegelenkbereich sowie Instabilitäten des patellofemoralen Gelenks sind im klinischen Alltag häufig beobachtete Probleme. Morphologische Besonderheiten wie eine Dysplasie der Trochlea femoris oder Form- und Positionsabweichungen der Kniescheibe beeinträchtigen dabei die Funktion des patellofemoralen Gelenks als integralen Bestandteil des Kniegelenks.Die Patella bildet in ihrer Funktion als Sesambein einerseits einen wichtigen Hebelarm für die Kraftübertragung der Quadrizepsmuskulatur bei der Streckung im Kniegelenk, andererseits muss das Gelenk zwischen Trochlea und Patella großen Druck- und Zugkräften widerstehen.In dieser Arbeit versuchen wir sowohl einen Überblick über die knöcherne Anatomie des Patellofemoralgelenks zu geben als auch unter Berücksichtigung des Knorpelaufbaus die Eigenschaften des patellofemoralen Gleitlagers zu erläutern.AbstractChronic anterior knee pain due to arthritic changes of the patellofemoral joint as well as instability of the patella are well-known problems for the clinician. Pathologic changes of the patellofemoral joint such as trochlear dysplasia or abnormality in form and position of the patella can cause severe impairment of knee joint function.The patella as the largest sesamoid bone of our body serves as a biomechanical lever arm of the quadriceps muscle. However, the joint between the patella and its counterpart, the trochlea, also has to withstand large tension forces as well as compression forces as an integral part of the knee joint.A good knowledge base of bony anatomy and chondral morphology — influencing patellar tracking during knee flexion as well as patellar stability — is necessary for successful treatment of patellofemoral problems.

Möglichkeiten der Bildgebung in der präoperativen Planung von Revisionseingriffen nach vorderer Kreuzbandrekonstruktion

ZusammenfassungTrotz verbesserter Operationsmethoden bei einer vorderen Kreuzbandplastik kommt es immer noch zum Versagen der Primäroperation, wodurch Revisionseingriffe notwendig werden. Eine exakte präoperative Analyse, warum es zum Versagen der Primäroperation kam, sowie die genaue Planung des Revisionseingriffs sind wesentliche Voraussetzungen für einen Behandlungserfolg.Vor allem die Beurteilung von Knochendefekten (durch Kanalerweiterung, resorbierbare Materialien etc.) ist wesentlich. Eine erweiterte bildgebende Diagnostik ist deshalb unbedingt angezeigt, sollte die alleinige Röntgendiagnostik Zweifel offen lassen.Die MRT bietet eine ideale Ergänzung bzgl. intraartikulärer Pathologie, während die CT bzgl. der Darstellung der Tunnelmorphologie (Platzierung und Ausdehnung) Vorteile bietet. Im Einzelfall müssen Vor- und Nachteile deshalb abgewogen werden. Gelegentlich kann eine Operationsplanung die Verwendung aller diagnostischen Möglichkeiten notwendig machen.AbstractFailures of ACL reconstruction still occur despite improved arthroscopic methods. The reasons for failures must be evaluated carefully prior to revision surgery. Therefore imaging of tunnel placement and bone defects is essential for successful clinical outcome. Plain radiographs may be sufficient in some revision cases, but MRI and CT scans are important if tunnel morphology or bone loss cannot be adequately recognized. MRI has an advantage for imaging of intrarticular pathology, whereas CT is preferable to evaluate bony architecture. In selected cases preoperative planning of revision ACL surgery has to include all three diagnostic modalities.