H. Bäthis

Alignment in total knee arthroplasty A COMPARISON OF COMPUTER-ASSISTED SURGERY WITH THE CONVENTIONAL TECHNIQUE

Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA. In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films. The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within +/- 3 degrees varus/valgus) compared with the conventional group (78%, within +/- 3 degrees varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group. Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.

Imageless navigation for insertion of the acetabular component in total hip arthroplasty: IS IT AS ACCURATE AS CT-BASED NAVIGATION?

In a prospective randomised clinical study acetabular components were implanted either freehand (n = 30) or using CT-based (n = 30) or imageless navigation (n = 30). The position of the component was determined post-operatively on CT scans of the pelvis. Following conventional freehand placement of the acetabular component, only 14 of the 30 were within the safe zone as defined by Lewinnek et al (40 degrees inclination sd 10 degrees ; 15 degrees anteversion sd 10 degrees ). After computer-assisted navigation 25 of 30 acetabular components (CT-based) and 28 of 30 components (imageless) were positioned within this limit (overall p < 0.001). No significant differences were observed between CT-based and imageless navigation (p = 0.23); both showed a significant reduction in variation of the position of the acetabular component compared with conventional freehand arthroplasty (p < 0.001). The duration of the operation was increased by eight minutes with imageless and by 17 minutes with CT-based navigation. Imageless navigation proved as reliable as that using CT in positioning the acetabular component.

Radiological results of image-based and non-image-based computer-assisted total knee arthroplasty

Restoration of the mechanical limb axis and accurate component orientation are two major factors affecting the long-term results after total knee replacement (TKR). Different navigation systems are available to improve the outcome. Image-based systems require pre-operative CT scans, while non-image-based systems gain all necessary information intra-operatively during a registration process. We studied 130 patients who received a TKR either using the CT-based (Knee 1.1) or the CT-free module (CT-free Knee 1.0) of the BrainLAB Vector-Vision Navigation System. Post-operative leg alignment and component orientation was determined on long-leg coronal and lateral X-rays. Sixty of 65 patients in the CT-based group and 63/65 patients in the CT-free group had a post-operative leg axis between 3° varus/valgus. No significant differences were found for varus/valgus orientation of the femoral and tibial components.RésuméLa restauration de l’axe mécanique du membre inférieur et l’orientation exacte des implants sont deux facteurs majeurs qui affectent les résultats à longue échéance après arthroplastie totale du genou total (PTG). Différents systèmes de navigation sont disponibles pour améliorer ces paramètres. Certains systèmes de navigation exigent une tomodensitométrie (TDM) préopératoire, tandis que d’autres acquièrent les informations nécessaires pendant l’intervention. Nous avons étudié 130 malades qui ont reçu un PTG soit avec une TDM préopératoire (Genou 1.1) soit avec le système sans TDM (BrainLAB Vecteur Vision® Navigation System), genou 1.0. L’alignement postopératoire du membre inférieur et l’orientation des composants a été déterminé sur des grands clichées coronaux et latéraux de membre inférieur. 60/65 malades dans le groupe TDM préopératoire et 63/65 malades dans le groupe sans TDM avaient un axe de membre inférieur postopératoire entre 0 et 3° de varus/valgus. Aucune différence notable n’a été trouvée concernant l’orientation des composants en varus/valgus.

Intraoperative cutting errors in total knee arthroplasty

IntroductionPrecise reconstruction of leg alignment offers the best opportunity for achieving good long-term results in total knee arthroplasty (TKA). It was the aim of this study to evaluate the bone-cutting process as a potential source of inaccuracy in TKA.Materials and methodsIn a consecutive series of 50 computer-assisted TKAs, cutting errors, which were defined as a difference between the cutting block position before sawing and the achieved resection plane afterwards, were measured for the distal femur and proximal tibia resection. Measurements were performed using a CT-based navigation system.ResultsFor the distal femoral cut, there was a mean varus/valgus deviation of 0.6° (SD±0.5°) and a mean flexion/extension deviation of 1.4° (SD±1.3°). For the proximal tibia, varus/valgus alignment showed a mean deviation of 0.5° (SD±0.5°). The mean sagittal variability was 1.0° (SD±0.9°). Differences between the frontal and the sagittal plane were significant.ConclusionTo minimize cutting errors, techniques and instruments are needed which enable a more stable fixation of the cutting blocks or even more appropriate preparation instruments. Using a computer-assisted technique, the surgeon is aware of cutting errors occurring at each point of the operation and will therefore be able to correct these errors during surgery, while he is not aware of those errors with the conventional TKA technique.

Revision total knee arthroplasty: a comparison of postoperative leg alignment after computer-assisted implantation versus the conventional technique

Accurate reconstruction of leg alignment is one important factor for long-term survival in total knee arthroplasty (TKA). Recent developments in computer-assisted surgery focused on systems improving TKA. The aim of the study is to compare the results of computer-assisted revision TKA with the conventional technique. We hypothize that a significantly better leg alignment and component orientation is achieved when using a navigation system for revision TKA. In a prospective study, two groups of 25 revision TKAs each were operated on using either a CT-free navigation system or the classical surgeon-controlled technique. The postoperative leg alignment was analysed on long-leg coronal and lateral X-rays. The mechanical limb axis was significantly better in the navigation-based group. Twenty-three patients (92%) in the computer-assisted group had a postoperative leg axis between 3° varus/valgus deviation, while 19 patients (76%) in the conventional group had a comparable result (p<0.05). Further, significant differences were seen for the coronal orientation of the femoral component. Computer-assisted revision TKA leads to a superior restoration of leg alignment compared with the conventional technique. Particularly the real-time presentation of the actual leg axis and the flexion and extension gaps is useful in revision TKA. Potential benefits in long-term outcome and functional improvement require additional investigation.

Sports Activity After Total Hip Resurfacing

Background: Little is known about sports activity after total hip resurfacing. Hypothesis: Patients undergoing total hip resurfacing can have a high level of sports activity. Study Design: Case series; Level of evidence, 4. Methods: The authors evaluated the level of sports activities with a standardized questionnaire in 138 consecutive patients (152 hips) 2 years after total hip resurfacing. Range of motion, Harris hip score, and Oxford score were assessed, and radiological analysis was performed. Results: Preoperatively, 98% of all patients participated in sports activities. Two years postoperatively, 98% of the patients participated in at least 1 sports activity. The level of sports activity decreased after surgery. The number of sports activities per patient decreased from 3.6 preoperatively to 3.2 postoperatively. Intermediate- and high-impact sports, especially tennis, soccer, jogging, squash, and volleyball, showed a significant decrease while the low-impact sports (stationary cycling, Nordic walking, and fitness/weight training) showed a significant increase. Physical activity level at the time of follow-up as measured by the Grimby scale was significantly higher than in the year before surgery. Duration of sports participation per week increased significantly after surgery. Men had a significantly higher sport level than women before and after surgery. Eighty-two percent felt no restriction while performing sports. One-third missed certain sports activities such as jogging, soccer, tennis, and downhill skiing. The Harris hip and Oxford scores showed a significant increase postoperatively. Conclusion: The results of this short-term follow-up study show that sports activity after total hip resurfacing surgery is still possible. Physical activity level increased with a shift toward low-impact sports. Duration of sports participation increased. High-impact sports activities decreased. These findings can be important for the decision-making process for hip surgery and should be communicated to the patient.

Constant-Score und Neer-Score : Ein Vergleich von Scoreergebnis und subjektiver Patientenzufriedenheit

ZusammenfassungEinleitung. Der Constant- und Neer-Score sind 2 weitverbreitete Scores zur Beurteilung der Schulterfunktion nach verschiedenartigen Erkrankungen oder Verletzungen.Ziel der vorliegenden Arbeit ist ein Vergleich von subjektiver und Score-basierter Bewertung der Schulterfunktion unter der Hypothese einer deutlichen Diskrepanz zwischen Scoreergebnis und subjektiver Patienteneinschätzung insbesondere für selektionierte Patientenkollektive. Methodik. Die Schulterfunktion von 51 Patienten wurde, 1–6 Jahre nach operativ versorgter proximaler Humerusfraktur, unter Verwendung des Neer- und Constant-Score analysiert. Gleichzeitig erfolgte eine subjektive Bewertung durch die Patienten in den Kategorien “sehr gut” bis “schlecht”. Ergebnisse. Beide Scoresysteme zeigten eine gute Übereinstimmung mit einer linearen Korrelation von r=97. In der subjektiven Bewertung beurteilten 57% der Patienten ihre Schulterfunktion als “sehr gut” oder “gut”, in der Score-basierten Bewertung erreichen nur 37% (Constant) bzw. 43% (Neer) der Patienten ein entsprechendes Ergebnis. Bezogen auf die Einteilung in Ergebnisgruppen (sehr gut/gut/befriedigend/schlecht) stimmen die Ergebnisse von Neer-Score und subjektiver Einschätzung in 20 Fällen und von Constant-Score und subjektiver Einschätzung in 15 Fällen überein. Die Spearman-Rangkorrelation zwischen der subjektiven und der Score-basierten Einschätzung ist mit 0,50 (Constant) und 0,55 (Neer) nur mäßig. Bei älteren Patienten (>60 Jahre) war die subjektive Beurteilung insgesamt positiver als die Score-Bewertung. Von 20 älteren Patienten kamen 14 (Neer-Score) bzw. 16 (Constant-Score) subjektiv zu einer besseren Einschätzung ihrer Funktion als der Score. Schlussfolgerungen. Die aufgestellte Hypothese einer Diskrepanz zwischen subjektiver und Score-basierter Einschätzung wird durch unsere Ergebnisse insbesondere für ältere Patienten bestätigt. Für die Klinik bedeutet dieses, dass das “Outcome” des Patienten nicht zwangsläufig mit seinem Scoreergebnis korrelieren muss. Therapieempfehlungen und Aussagen wissenschaftlicher Arbeiten, die ausschließlich auf einer Scorebewertung basieren, können deshalb für bestimmte Patientenkollektive nicht uneingeschränkt übernommen werden.AbstractIntroduction. The Constant- and the Neer-Score are widely used to assess shoulder function after trauma or shoulder diseases.The objective of this study was to compare the correlation of score result with the patient subjective assessment. We hypothesized that there is a clinically relevant difference between the score result and the patient assessment, especially for highly selective patient groups. Methods. 51 patients were followed up after the surgical treatment of a proximal humeral fracture. For each patient the Constant- and the Neer-Score was calculated. Further, the patients were asked for a subjective assessment of their shoulder function (“excellent”, “good”, “fair”, “poor”). Results. For both score-systems a good linear correlation (r=0,97) is shown. 57% of the patients assessed their shoulder function as “excellent” or “good”, but only 37% (Constant) vs. 43% (Neer) of the patients were classified as “excellent” or “good” based on their score results. The Spearman correlation of subjective and score-based assessment was just fair with r=0,50 (Constant) and r=0,55 (Neer). When comparing the score results with the patient subjective assessment for the groups: “excellent”, “good”, “fair” and “poor”, there was a positive correlation for the Neer-Score in 20 cases and for the Constant-Score in 15 cases. Of all elderly patients (>60 years, n=20), 14 (Neer-Score) vs. 16 (Constant-Score) assessed their shoulder function as better than the score did. Conclusion. The hypothesis of a clinically relevant difference between the subjective and the score-based assessment of shoulder function can be confirmed. Our results suggest that for clinical practice, statements and therapy strategies recommended in the literature, that are just based on score results might not be valid for all patient-groups (e.g. elderly patients).

Stand der Therapie der Schultereckgelenkverletzung Ergebnisse einer Umfrage an Unfallchirurgischen Kliniken in Deutschland

ZusammenfassungDie Therapie der Schultereckgelenkverletzung, insbesondere der Typ-III-Verletzung nach Rockwood/Tossy wird kontrovers diskutiert. In der Literatur werden gute Ergebnisse für verschiedene operative Behandlungsmethoden sowie für eine rein konservative Therapie beschrieben. Das Ziel der vorliegenden Erhebung ist es, die reale Praxis der Versorgung von Schultereckgelenkverletzungen in deutschen unfallchirurgischen Kliniken darzustellen und zu analysieren.In einer anonymen schriftlichen Umfrage wurden 210 unfallchirurgische Abteilungen in Deutschland nach ihrem diagnostischen und therapeutischen Vorgehen bei Schultereckgelenkverletzungen befragt. Entsprechend einer Rücklaufquote von 49% konnten 104 Bögen ausgewertet werden.Für eine Tossy-I/II-Verletzung gaben 99 bzw. 87% der Klinken eine konservative Therapie an. Die überwiegende Mehrheit (84%) der befragten Kliniken sprachen sich für eine operative Therapie bei der Verletzung Typ Tossy III aus. Nahezu alle befürworten ein operatives Vorgehen bei Überkopfarbeitern und Leistungssportlern. Die hochgradigen Verletzungen (Rockwood IV–VI) werden fast ausschließlich operativ stabilisiert.Als operative Methode bevorzugen 37% eine temporäre Kirschner-Drahtfixierung und 32% eine coraco-claviculäre Cerclage, die in 73% der Fälle mit resorbierbaren Materialien durchgeführt wird. Übrige Operationsverfahren zeigen einen niedrigeren Stellenwert.AbstractThe therapy of acromioclavicular dislocations remains controversial. In particular, for injuries classified as Rockwood/Tossy Type III good results have been reported with different operative techniques as well as with conservative treatment. The objective of this study was to obtain data about the current treatment for Rockwood/Tossy III injuries in German trauma departments.In a countrywide anonymous survey 210 German trauma departments were asked about their diagnostic procedures and their treatment strategies for acromioclavicular injuries. 104 questionaires (49%) were returned and evaluated.In Rockwood/Tossy I/II injuries most clinics recommend conservative treatment (Rockwood/Tossy I/II: 99% / 87%). On the other hand, 84% of the clinics would operate on Type III acromioclavicular injuries – especially in athletes or overhead workers. Although 38 percent of the clinics believe that conservative treatment is equal or better than operative treatment, only 13 percent manage Type III injuries conservatively. For more severe acromioclavicular injuries (Rockwood IV to VI) all clinics recommend an operative treatment.The operative techniques of choice for acromioclavicular injuries are K-wire fixation (37%) or a coraco-clavicular cerclage (32%). Of the latter, 73% use a resorbable material, while the remainder use wires.

Two-year follow-up on joint stability and muscular function comparing rotating versus fixed bearing TKR

Mobile and fixed bearing in total knee replacement are still discussed controversially. In a retrospective, matched-pair study, we investigated 40 patients with computer-assisted (BrainLAB®) primary total knee replacement (PFC Sigma®, DePuy®) performed two years before. Twenty patients each received a mobile bearing and a fixed bearing. We compared Womac Score, Knee Society Score, postoperative ROM, fluoroscopic measurement of knee stability in flexion and extension and isokinetic muscle strength using a BiodexTM-3 dynamometer. Both groups showed similar results concerning WOMAC Score (total rotating bearing: 23.05; fixed bearing: 22.57), KSS (rotating bearing: 174.89; fixed bearing: 176.1). Isokinetic muscle force demonstrated statistically significant superior results for knee flexion in the rotating bearing group. Medio-lateral stability revealed statistically significant superior results for the rotating bearing compared to fixed bearing in extension (P>0.05). In flexion only lateral stability was superior (P>0.05). Two-year clinical follow-up after computer-assisted total knee replacement resulted in good clinical outcome with high patient satisfaction. Statistically significant better values for the rotating platform group were found for the medio-lateral stability in extension and the peak flexion torque.

Flexion gap configuration in total knee arthroplasty following high tibial osteotomy

Previous reports have described the potentially compromising effect of a high tibial osteotomy (HTO) on the results of a subsequent total knee arthroplasty (TKA). Although the reasons are not clear, some authors reported problems in soft-tissue balancing. In a prospective study, 22 patients with an average interval of 5.8 years after closed-wedge HTO were operated for TKA. All operations were performed with a CT-free navigation system, and measurements of the extension and flexion gap were assessed. The intraoperative data were compared to a control group of 100 consecutive computer-assisted TKA without previous osteotomy. In the study group, a highly significant shift towards a medial opening of the flexion gap between the posterior condylar line and the tibial resection (study group 0.4±4.7° medial opening versus control group 3.4±3.3° lateral opening, p<0.001) was observed. In the study group, 10/22 showed a medial opening of the flexion gap compared to 11/100 in the control group. Surgeons should be aware of difficulties in soft-tissue balance in TKA following HTO, especially for the flexion gap configuration and the axial rotation of the femoral component.RésuméPlusieurs rapports ont décrit l’effet potentiellement défavorable d’une ostéotomie tibiale supérieure sur les résultats d’une arthroplastie totale du genou secondaire. Bien que les raisons ne soient pas claires, quelques auteurs ont rapporté des problèmes dans l’équilibre des parties molles. Dans une étude prospective 22 malades ont eu une arthroplastie totale du genou avec un intervalle moyen de 5,8 ans après une ostéotomie tibiale. Toutes les opérations ont été exécutées avec un système de navigation sans scanner et l’intervalle en flexion et en extension a été mesuré. Les données intraopératoires ont été comparées à un groupe témoin de 100 arthroplasties totales du genou consécutives, sous contrôle informatique, sans ostéotomie préalable. Dans le groupe d’étude a été constaté une modification très importante vers une ouverture médiale de l’intervalle en flexion entre la ligne condylienne postérieure et la résection tibiale (groupe d’étude 0,4±4,7° d’ouverture médiale contre, dans le groupe témoin, 3,4±3,3° d’ouverture latérale, p<0.001). Dans le groupe d’étude 10/22 ont montré une ouverture médiale de l’intervalle en flexion comparée à 11/100 dans le groupe témoin. Les chirurgiens doivent être conscients de la difficulté d’équilibrer les parties molles dans l’arthroplastie du genou aprés ostéotomie tibiale, surtout pour la configuration de l’intervalle en flexion et l’orientation axiale du composant fémoral.