KATHARINA MARIA IMHOLT THERAPIEERGEBNISSE NACH TPLO
KATHARINA MARIA IMHOLT PLATEAU LEVELING OSTEOTOMY (TPLO) UNTER BESONDERER BERÜCKSICHTIGUNG DER OSTEOARTHROSEENTWICKLUNG
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Ermittlung der Therapieergebnisse nach operativer Behandlung des vorderen Kreuzbandrisses bei Hunden mittels Tibial Plateau Leveling Osteotomy (TPLO) unter besonderer Berücksichtigung der Osteoarthroseentwicklung
INAUGURAL – DISSERTATION
zur Erlangung des Grades einer Doktorin der Veterinärmedizin
- Doctor medicinae veterinariae - ( Dr. med. vet. )
vorgelegt von
Katharina Maria Imholt
Bad Kissingen
Hannover 2011
1. Gutachterin: Univ.-Prof. Dr. med. vet. Andrea Meyer-Lindenberg Klinik für Kleintiere
2. Gutachter: Apl.-Prof. Dr. med. vet. Carsten Staszyk Anatomisches Institut
Tag der mündlichen Prüfung: 24.11.2011
Finanzielle Unterstützung: Promotionsstipendium der Studienstiftung des deutschen Volkes
Meiner Familie und Dirk
Ergebnisse dieser Dissertation wurden in international anerkannten Fachzeitschriften mit Gutachtersystem (peer review) zur Veröffentlichung angenommen/eingereicht:
• Tierärztliche Praxis Kleintiere
ISSN: 1434-1239; Ausgabe 2011; Heft 5 2011, Seiten 323-335
Lahmheits- und Osteoarthroseentwicklung nach Tibial Plateau Leveling Osteotomy (TPLO) und potenzielle prognostische Einflussfaktoren Eine retrospektive Langzeitstudie
K. M. Imholt, S. Möller, M. Fehr, A. Meyer-Lindenberg
• Veterinary Surgery (eingereicht am 16.09.2011)
Clinical outcome following Tibial Plateau Leveling Osteotomy (TPLO) using a conventional and an angle-stable locking TPLO plate system – a prospective clinical study in 39 stifle joints
K. M. Imholt, S. Möller, M. Fehr, A. Meyer-Lindenberg
Teilergebnisse dieser Dissertation wurden auf folgenden Fachkongressen präsentiert:
• 2. Tagung der DVG-Fachgruppe “Chirurgie”, Düsseldorf, 22.10.2010 (56. Jahreskongress der Deutschen Gesellschaft für Kleintiermedizin, 2010)
Klinische Ergebnisse, Lahmheits- und Osteoarthroseentwicklung nach Tibial Plateau Leveling Osteotomy (TPLO) - Eine retrospektive Studie
K. M. Imholt, M. Fehr, A. Meyer-Lindenberg
• 3. Tagung der DVG-Fachgruppe “Chirurgie”, Berlin, 11.11.2011
(57. Jahreskongress der Deutschen Gesellschaft für Kleintiermedizin, 2011) Vergleichende Betrachtung zweier TPLO-Plattensysteme bezüglich assoziierter Komplikationen und postoperativem Lahmheitsergebnis K. M. Imholt, M. Fehr, A. Meyer-Lindenberg!!
Inhaltsverzeichnis
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Die Ruptur des Ligamentum cruciatum craniale stellt eine der häufigsten orthopädischen Erkrankungen der Hintergliedmaße bei Hunden dar (J. A. JOHNSON et al. 1994). Die Vielzahl unterschiedlicher chirurgischer Verfahren zur Versorgung dieser Erkrankung und die bis heute intensive Forschungsarbeit auf diesem Gebiet zeigen, dass ein therapeutischer Goldstandard derzeit noch nicht gefunden wurde. Seit der Einführung durch SLOCUM und SLOCUM (1993), ist die Tibial Plateau Leveling Osteotomy (TPLO) insbesondere bei großen und athletischen Hunden eine der am häufigsten durchgeführten Operationsverfahren zur Behandlung eines vorderen Kreuzbandrisses (BARONI et al. 2003; SHAHAR u. MILGRAM 2006). Dies unterstreichen die im Vergleich zu konventionellen Operationsverfahren besseren Ergebnisse bezüglich postoperativer Lahmheitsentwicklung (KLOENE 2005; BÖDDEKER 2010). Das Fortschreiten der Arthrose in den betroffenen Gelenken sollte nach einer TPLO, gemäß den Ergebnissen der ursprünglichen Untersuchung (SLOCUM u. SLOCUM 1993), vollständig oder nahezu vollständig (MATIS et al. 2004; COOK et al. 2010) zum Stillstand kommen. Im Rahmen anderer Untersuchungen (RAYWARD et al. 2004; LAZAR et al. 2005;
LINEBERGER et al. 2005; BOYD et al. 2007; HURLEY et al. 2007; AU et al. 2010) mit Untersuchungszeiträumen zwischen acht Wochen (HURLEY et al. 2007) und 24 Monaten (AU et al. 2010) nach TPLO, wurde dagegen eine geringe, aber dennoch statistisch signifikante Progression der Arthrose beobachtet. Trotz der bereits mehrjährigen Erfahrung und der insgesamt guten klinischen Ergebnisse ist die Komplikationsrate nach TPLO vergleichsweise hoch und beträgt zwischen 14,8 % (FITZPATRICK u. SOLANO 2010) und 28% (PACCHIANA et al. 2003).
Da sich viele Studien bezüglich Lahmheits- und Arthroseentwicklung nach TPLO auf relativ kurze Untersuchungszeiträume beziehen, sollten diese im Rahmen des ersten Teils dieser Dissertation im Zuge einer retrospektiven Langzeituntersuchung, bis fünf Jahre nach der Operation, ermittelt werden. Ein weiteres Ziel der retrospektiven Untersuchung war es, zu untersuchen, ob die präoperative Lahmheitsdauer, bereits zuvor am betroffenen Knie durchgeführte Operationen, intraoperativ diagnostizierte Befunde an Meniskus und Kreuzband, etwaige postoperative Komplikationen sowie die seit der Operation vergangene Zeitspanne einen möglichen Einfluss auf das langfristige Lahmheits- und Arthroseergebnis besaßen. Es sollte damit geprüft werden, ob prognostisch relevante Zusammenhänge zu
erkennen sind, die schließlich in die individuelle Beratung der Patientenbesitzer und die Prognosestellung im Vorfeld einer Operation mit einfließen können.
Für die TPLO stehen verschiedene Osteosyntheseplatten zur Fixation des Tibiaplateaus zur Verfügung. Während sich diese verschiedenen Implantate durch besondere Merkmale auszeichnen, wird die Stabilität am Platten-Knochen-Berührungspunkt meist durch die Reibungskraft zwischen Platte und Knochen erzeugt (GARDNER et al. 2006). Die Platten müssen deshalb zur korrekten Platzierung in ihrer Form so gut wie möglich an die individuelle äußere Form des Knochens anmodelliert werden. Um eine absolute Stabilität der Osteotomiestelle zu gewährleisten, wird der feste Kontakt zwischen Platte und Knochen schließlich durch das Anziehen der Schrauben erzeugt (WAGNER 2003; GREIWE u.
ARCHDEACON 2007).
Auf der einen Seite bietet theoretisch die große Kontaktfläche eine gute Stabilität. Durch den von der Platte auf den Knochen ausgeübten Druck wird jedoch die Blutzufuhr des Knochens beeinträchtigt, was zu Knochennekrosen führen und sich negativ bzw.
verlangsamend auf die Knochenheilung auswirken kann (RHINELANDER 1965; JACOBS et al. 1981; ALEXANDER et al. 1983; PERREN et al. 1988; MATTER u. BURCH 1990;
GAUTIER et al. 1995; VAN HAASNOOT et al. 1995). Beeinträchtigte Knochenvitalität aufgrund von Malperfusion reduziert die lokale Immunkompetenz (ANDRIOLE u. LYTTON 1965; GRISTINA 1994), mit den möglichen Komplikationen Infektion, Sequestrierung der nekrotischen Knochenareale und Pseudarthrose (PERREN et al. 1988; GAUTIER u.
PERREN 1992; MELCHER et al. 1994).
Auf der anderen Seite ist allerdings aufgrund der Zielsetzung einer TPLO, nämlich der Veränderung des Tibiaplateauwinkels, die optimale anatomische Positionierung der Fragmente in Ausgangsposition, wie es das Ziel bei Frakturversorgungen ist, nicht möglich.
Die Anwesenheit eines Spaltes sowohl zwischen Platte und Knochen, als auch zwischen den beiden Knochenfragmenten kann zu einer verminderten Stabilität des Konstrukts führen.
Instabilere Konstruktionen können dann wiederum zu Implantatversagen, verspäteter Knochendurchbauung oder gar fehlender Durchbauung führen (KLOC et al. 2009).
Derartige Überlegungen führten zur Entwicklung neuer Plattentypen, wie zum Beispiel der Limited Contact-Dynamic Compression Plate (LC-DCP) (PERREN et al. 1990), die durch Aussparungen auf der Plattenunterseite die Platte-Knochen-Kontaktfläche verringert, und der
Locking Compression Plate (LCP)(FRIGG 2001), die durch eine verriegelnde Verbindung zwischen Platte und Schraube in diesem Bereich nicht mehr durch die Schraube am Knochen
„festgezogen“ werden muss, um die gewünschte Stabilität zu erzeugen.
Die erst kürzlich entwickelte winkelstabile Synthes® TPLO-Platte (Synthes® Vet, Oberdorf, Schweiz) kombiniert die Eigenschaften einer LCP und einer LC-DCP.
Die Blutversorgung des Knochens wird durch die verringerte Auflagefläche einer LC- DCP weniger beeinträchtigt (PERREN 1991) und somit die Heilung gefördert. Zudem ist gut vaskularisiertes Gewebe durch die Präsenz der lokalen Abwehr weniger anfällig für Infektionen (ANDRIOLE u. LYTTON 1965; PERREN et al. 1988; GAUTIER u. PERREN 1992; GRISTINA 1994; MELCHER et al. 1994).
In vitro wurden bereits Studien durchgeführt, die eine sehr gute und überlegene Stabilität von Verriegelungsplatten, insbesondere bezüglich Biegefestigkeit und zyklischer Belastbarkeit (BORDELON et al. 2009; KLOC et al. 2009), selbst bei der Verwendung in osteoporotischen humanen Oberarmknochen (GARDNER et al. 2006), gegenüber den konventionellen Plattensystemen bestätigen. Beim Aufbringen der Platte im Rahmen einer TPLO kann bei Verwendung eines winkelstabilen Plattensystems die Position des Tibiaplateaus zudem besser beibehalten werden, wohingegen es bei der Verwendung von Kortikalisschrauben in Verriegelungsplatten eher zu einem Abkippen des Tibiaplateaus während der Plattenapplikation kommt (LEITNER et al. 2008). Um den Einfluss von Verriegelungsschrauben und Kortikalisschrauben auf den postoperativen Tibiaplateauwinkel, die Knochenheilung sowie die Komplikationsrate vergleichen zu können, wurden in einer prospektiven klinischen Studie von CONKLING et al. (2010) an 118 Kniegelenken Unity Cruciate Platten (UCP) zur Stabilisierung der Osteotomie verwendet. Diese können sowohl unter Verwendung von konventionellen Schrauben, als auch von Verriegelungsschrauben aufgebracht werden. Zum Kontrollzeitpunkt acht Wochen post operationem konnten eine signifikant bessere Knochenheilung, eine signifikant geringere Veränderung des postoperativen Tibiaplateauwinkels, sowie eine geringere Komplikationsrate (14,3% vs.
23,6%) in der mit Verriegelungsschrauben versorgten Patientengruppe nachgewiesen werden.
(CONKLING et al. 2010).
Die beschriebenen Eigenschaften der Synthes® TPLO Platte und die Ergebnisse der bisherigen in vitro Untersuchungen, lassen auf eine Reduktion der Komplikationen und eine
positive Beeinflussung der klinischen Heilung im Zusammenhang mit der Verwendung der Synthes® TPLO Platte hoffen. In der Veterinärmedizin fehlen diesbezüglich jedoch bislang klinische Studien.
Deshalb war es ein weiteres Ziel dieser Dissertation im Rahmen einer prospektiven Vergleichsstudie über sechs Monate zu untersuchen, ob durch die Verwendung des winkelstabilen Synthes® TPLO Plattensystems gegenüber der herkömmlichen SECUROS TPLO Platten die postoperative Lahmheits- und Arthroseentwicklung beeinflusst sowie die intra- und postoperative Komplikationsrate gesenkt werden können.
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Lameness and osteoarthritis following Tibial Plateau Leveling Osteotomy (TPLO) and potential prognostic predictors. A long-term retrospective study
Katharina Maria Imholt, Sonja Möller, Michael Fehr, Andrea Meyer-Lindenberg
Tierärztliche Praxis Kleintiere ISSN: 1434-1239 Ausgabe 2011: Heft 5 2011
Seiten 323-335
akzeptiert nach Revision am 21.06.2011
Zusammenfassung
"
Gegenstand: Untersuchung von Lahmheits- und Arthroseentwicklung nach Tibial Plateau Leveling Osteotomy (TPLO) bei Hunden und Evaluierung potenzieller prognostischer Einflussfaktoren.
Material und Methoden: Es erfolgte eine retrospektive Auswertung der Patientenakten von 119 Hunden (135 Kniegelenken) mit Erfassung von Röntgen- und Operationsbefunden, Operationsverlauf und Komplikationen. Das Therapieergebnis wurde anhand der klinischen und röntgenologischen Befunde einer Kontrolluntersuchung sowie durch einen vom Besitzer ausgefüllten Fragebogen ausgewertet, und zwar für beide Gruppen kombiniert als auch getrennt. Bei den nachuntersuchten Hunden erfolgte ferner eine Bestimmung von Arthrosegrad, Arthroseentwicklung sowie aktuellem Lahmheitsstatus.
Ergebnisse: 58 Hunde (66 Kniegelenke) konnten klinisch und röntgenologisch und 61 Hunde (69 Kniegelenke) nur anhand eines Fragebogens kontrolliert werden. Sechs Monate bis 6,8 Jahre nach der TPLO war das Lahmheitsergebnis in 90,4% der Fälle „sehr gut“
(n = 84) oder „gut“ (n = 38). Langfristig kam es zu einem moderaten, aber signifikanten Fortschreiten der Arthrose. Patienten mit Totalruptur des vorderen Kreuzbandes wiesen signifikant häufiger einen Meniskusschaden auf als Patienten mit Teilruptur. Patienten, bei denen eine Teilmeniskektomie erfolgte, zeigten signifikant häufiger „sehr gute“
Langzeitergebnisse und seltener ein Fortschreiten der Arthrose als Hunde, deren Meniskus belassen oder bei denen ein Release durchgeführt wurde. Die Komplikationsrate lag bei 22,2% (n = 30), wobei sich die Art der Komplikation nicht auf das Ergebnis auswirkte.
Schlussfolgerung und klinische Relevanz: Die Langzeitergebnisse bezüglich Lahmheit nach TPLO sind sehr zufriedenstellend. Die Wahrscheinlichkeit des Arthrosefortschreitens lässt sich durch frühzeitige chirurgische Versorgung verringern. Eine mediale Teilmeniskektomie kann helfen, spätere Operationen wegen eines sekundären Meniskusschadens zu verhindern, ohne das langfristige Lahmheitsergebnis oder die Arthroseentwicklung negativ zu beeinflussen. Durch eine vorangegangene Operation oder postoperative Komplikationen verschlechtert sich weder das langfristige Lahmheitsergebnis noch beschleunigt sich das Fortschreiten der Arthrose.
Summary
Objective: Evaluation of lameness and progression of osteoarthritis following Tibial Plateau Leveling Osteotomy (TPLO) in dogs with naturally occurring rupture of the cranial cruciate ligament (CrCL) and investigation of factors with potential influence on long-term outcome.
Material and methods: In a long-term retrospective clinical study medical records of 119 client-owned dogs (135 operated stifle joints) and corresponding client-questionnaires were reviewed collecting data on radiologic and surgery results, course of surgery and complications. In a check-up orthopaedic examination as well as stifle radiographs were performed to assess status quo of osteoarthritis (OA) and lameness as well as progression of OA. Statistical analysis was done separately for dogs with current orthopaedic and radiologic findings and those whose clinical outcome could only be assessed based on a client- questionnaire.
Results: 58 dogs (66 stifle joints) could be examined clinically and radiologically, whereas 61 dogs (69 stifle joints) were re-checked by client-questionnaire only. Up to 6.8 years after TPLO surgery, in 90.4% of all cases lameness results were judged „excellent“ (n = 84) or
„good“ (n = 38). In the long run, there was a moderate but significant progression of OA following TPLO surgery. Patients with totally ruptured CrCL were significantly more likely to have meniscal injury than dogs with partially ruptured CrCL. Dogs with partial meniscectomy had a significantly higher rate of „excellent“ long-term clinical results and less frequently showed progression of OA compared to those having the meniscus released or left untouched. The overall complication rate was 22.2% (n = 30), with nine minor and 21 major complications, with the type of complication having no influence on the long-term clinical outcome.
Conclusions and clinical relevance: Concerning lameness, the long-term outcome following TPLO surgery is very satisfying. Early surgical treatment of cranial cruciate ligament rupture using TPLO can help to decrease the likelihood of OA progression. Partial medial meniscectomy may help to avoid repeated surgery due to subsequent meniscal injury without having a negative impact on long-term functional outcome or the progression of OA in the affected joint. Neither long-term clinical results especially regarding lameness, nor OA
are impaired by previous surgery prior to TPLO or the occurrence of complications associated with TPLO surgery.
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Katharina Maria Imholt, Sonja Möller, Michael Fehr, Andrea Meyer-Lindenberg
Das Folgende Manuskript wurde am 16. 09. 2011 im Journal „Veterinary Surgery“
eingereicht.
Abstract
OBJECTIVE: To compare the use of SECUROS and Synthes TPLO plates regarding clinical outcome, progression of osteoarthritis and occurrence of intra- and post-operative complications.
STUDY DESIGN: Prospective clinical study.
ANIMALS: 37 dogs (39 joints) with cranial cruciate ligament rupture (CrCLR).
METHODS: Dogs were randomly assigned to one treatment group (Synthes group n=19 stifles, SECUROS group n=20 stifles) and treated with TPLO using the respective osteotomy plate. Complications were documented. Lameness, osteoarthritis and osteotomy healing were assessed pre-operatively, at three and six month follow-up. A multiple-choice based questionnaire was used for owner assessment at three and six months. On this basis, clinical outcome regarding lameness was evaluated on a 0 to 3 score. Owners reported weekly the direct effect of surgery (lameness compared to pre-operatively) and whether or not the dog had reached the activity level he had before onset of CrCLR. Owner satisfaction was documented. Chi2-analysis, Fisher’s Exact test, non-parametric Mann–Whitney U-test and Wilcoxon signed rank test were used for statistical analysis, significance was set at P!.05.
RESULTS: For none of the parameters under study statistically significant differences were found between groups. There was evidence of a trend towards fewer implant/technique- related intra-operative complications that affected the joint and a lower frequency of post- operative complications in the Synthes group. Furthermore, normal activity level was achieved in a shorter period of time.
CONCLUSIONS: Use of both plates results in good to excellent results.
CLINICAL RELEVANCE: Synthes plates provide for comfortable and safe handling and are a suitable alternative to SECUROS plates.
Introduction
Cranial cruciate ligament deficiency is one of the most common orthopaedic diseases causing hind-limb lameness in dogs1, but a gold standard for treatment has not been found yet.
Introduced by Slocum and Slocum2, the Tibial Plateau Leveling Osteotomy (TPLO) has become one of the most popular surgical techniques for the treatment of cranial cruciate ligament rupture, especially in active and large dog breeds3,4. Today, many different osteotomy plates specially designed for TPLO surgery are available. These are for example the original Slocum TPLO plate (Slocum Enterprises Inc., Eugene, Oregon, USA), the Cadmus plate (Veterinary Instrumentation Limited, Sheffield, UK) or the Securos® TPLO plate (Securos Europe, Neuhausen ob Eck, Germany). Although all these implants are unique in their design and thus hold individual design-related features they all depend on the friction generated on the bone-implant contact area by screw tightening to maintain construct and interfragmentary stability5,6. By this means these conventional plates are intended to create an environment for primary bone healing to occur. On the one hand the large bone-implant contact area along the smooth undersurface of the plate may theoretically provide good stability, but on the other hand the pressure on the bone surface induced by the tightened osteotomy plate may impair vascularity of the underlying bone and soft tissue if not removed.
This can result in bone or tissue necrosis, negatively influenced or delayed bone-healing7-12. Affected bone vitality due to malperfusion reduces cellular and humeral host defence mechanisms with the possible complications of infection, sequestration of necrotic bone and pseudarthrosis11,13,14.
With this in mind, the limited contact dynamic compression plate (LC-DCP) was developed15. Plates of this type provide crescent notches along the undersurface, which reduce the contact area between bone and implant. Thereby bone vascularity is better preserved and healing conditions are optimised16 resulting in more rapid fracture healing17,18.
A further problem, which is not solved by using LC-DCP is that perfect anatomic reduction, the aim of fracture treatment, is impossible to achieve in TPLO surgery, since that is used for corrective osteotomy. As the presence of a gap, between the plate and the bone or between the bone fragments, may result in a less stable plate-bone construct, this consequently may lead to implant failures, delayed unions or even non-unions19. This in turn, led to the development of locking plates. TPLO plates providing locking features are for
example the Synthes® TPLO plate (Synthes® Vet, Oberdorf, Switzerland) or the string-of- pearls TPLO plate (Orthomed Technology GmbH, Kaltenkirchen, Germany). The locking plate-screw junction generates fixed-angle stability, transforming the axial load into a compression force on the osteotomy site. In that way tension of the fracture gap is reduced and bone formation is supported without relying on direct plate-bone contact or fragment compression6,17,20. Precise anatomical contouring of the plate is no longer necessary thanks to the locking plate-screw junction and because the plate does not need to be pressed onto the bone to achieve stability5,21.
In vitro studies already proved the excellent and superior bending stability and resistance to cyclic loading of locking plates compared to conventional plate systems19,22 even when used in human osteoporotic humeral fractures5. Tibial plateau position was significantly better maintained during TPLO locking plate application using a locking plate-screws system than using conventional screws with locking plates23. Fracture healing was faster when locking screws, instead of cortex or cancellous bone screws were used in conventional plates18.
Regarding TPLO surgery, we can look back on many years of experience and good long- term clinical results. But the associated complication rate is still between 14,8%24 and 28%25 and include, inter alia, tuberositas tibiae avulsion, fibular fracture, intra articular screw placement, implant failure, implant loosening, bone or wound healing disorders and bacterial infection24-30. Complications lead to unnecessary pain and stress for the dogs, long, laborious and intensive in-patient care, prolonged convalescence and additional cost for the owners26.
Based on the previously described features of locking plates and the results of recent studies we hypothesise that clinically relevant complications associated with TPLO surgery and related consequences could be minimised using a locking TPLO plate system. There is no controlled clinical study regarding this topic to date.
The aim of this prospective clinical study was, therefore, to investigate whether using locking TPLO plates (Synthes® TPLO plate) in comparison to widely used conventional TPLO plates (SECUROS TPLO plate), can minimise intra- and post-operative complications and affect the clinical outcome or the progression of osteoarthritis during a six months period.
Materials and Methods Animals
37 client-owned dogs (39 stifle joints) (Synthes group: 18 dogs, 19 stifle joints; SECUROS group: 19 dogs, 20 stifle joints) with naturally occurring cranial cruciate ligament (CrCL) rupture presented from July 2009 through October 2010 and owners willing to participate in the clinical study were enrolled. CrCL rupture was diagnosed based on history, orthopaedic and radiologic findings. After complete healing, there were two dogs developing CrCL rupture on the other side during the study. The second joint was then operated using the respective other treatment. Each performed TPLO procedure (i.e. each joint) was taken as individual case for statistical analysis. Breed, sex, age, body weight, body condition score (Scale 1-9, ‘Body Condition System’, Nestlé Purina Pet Care Center, ST. Louis, MO), onset of lameness, history of trauma and pre-treatment were recorded. 21 breeds were presented in this study, mixed breed dogs (n=11; 29,7%) being most common whereas other breeds were represented with a maximum of two dogs each. Neither Synthes® Vet nor Securos Europe GmbH were involved in any part of the study.
Surgical procedure
The joints were randomly assigned to one of two treatment groups. In one group (SECUROS group; n=20) TPLO was performed using SECUROS TPLO plates (001129 3.5mm TPLO Plate-left and 001130 3.5mm TPLO Plate-right, 000776 3.5mm TPLO plate-left broad and 000775 3.5mm TPLO plate-right broad, SECUROS Europe GmbH, Neuhausen ob Eck, Germany), in the other group (Synthes group; n=19) using locking Synthes® TPLO plates (VP4402.L4 3.5mm broad TPLO plate left, 4 holes; VP4402.R4 3.5mm broad TPLO plate right, 4 holes; VP4401.L3-3.5mm TPLO plate left, 3 holes; VP4401.R3-3.5mm PLO plate right, 3 holes, Synthes® Vet, Oberdorf, Switzerland). Plate size (3.5mm standard or 3.5mm broad) was chosen depending on the dogs’ size and body condition. Otherwise treatment did not differ. All TPLO procedures were performed by two surgeons with several years of experience with TPLO surgery, but at the beginning of the study no experience with the Synthes® TPLO plate system. All dogs were pre-medicated with acepromazine (Vetranquil® 1
%, Albrecht GmbH, Aulendorf, Germany)(0,05mg/kg intramuscularly) 15-30 minutes prior to induction of anaesthesia with levomethadon (L-Polamivet®, Intervet Deutschland GmbH,
Unterschleißheim, Germany)(0,6mg/kg intravenously) and propofol (Narcofol® 10mg/ml, CP-Pharma Handelsgesellschaft GmbH, Burgdorf, Germany)(1-2mg/kg intravenously).
Anaesthesia was maintained with isoflurane (Isofluran CP, CP-Pharma Handelsgesellschaft mbH, Burgdorf, Germany) in oxygen. Morphine (Morphine® 10mg/ml, Hexal AG, Holzkirchen, Germany)(0,1mg/kg) and bupivacaine (Bupivacain-RPR-actavis® 0,5 %, Actavis Deutschland GmbH & Co. KG, Langenfeld, Germany)(0,5mg/kg) were administered epidurally. Cefazolin (Cefazolin® 2g/ml, Hexal AG, Holzkirchen, Germany)(22mg/kg intravenously) was given 20 minutes before skin incision and 90 minutes later during surgery.
Craniocaudal and mediolateral measuring radiographs of the affected stifle joint were taken, the tibial plateau angle was measured and the corresponding millimetres of rotation of the proximal tibial segment were calculated. The limb was clipped and scrubbed surgically. The dogs were positioned in lateral recumbency with the affected limb laid flat on the operating table. The proximal tibia was approached medially2 elevating the insertions of the gracilis, semitedinosus, and caudal belly of the sartorius muscle from the proximal medial tibia. Care was taken to leave the medial collateral ligament intact. By minimal caudomedial arthrotomy the medial meniscus was assessed. The caudal pole of the medial meniscus was partially excised in all dogs regardless of meniscal status31 followed by thorough joint lavage with sterile saline and closure of the joint capsule. TPLO surgery was performed as described by Slocum and Slocum2 but without using a jig. For soft tissue protection, the lateral aspect of the proximal tibia was temporarily padded with moist sterile cotton gauze pads when the cylindrical osteotomy was created in the proximal tibia by use of a biradial saw blade.
Copious cold irrigation fluid was applied to minimize saw induced thermal bone and tissue damage. The proximal fragment was rotated using a 2.0mm K-wire as a ‘handle’ and then temporarily secured with a 1.0mm or 1.2mm K-wire. Plate application was followed by thorough layer-wise wound closure. Skin sutures were covered with sterile Betaisodona® gauze (Betaisodona® Wundgaze, Mundipharma Vertriebsgesellschaft mbH, Limburg/Lahn, Germany) and sterile band-aid (Cosmopor® steril 20x8cm, Paul Harmann AG, Heidenheim, Germany) for the first 24 hours.
Post-operatively, appropriate screw and implant placement were controlled radiographically in two planes. The post-operative tibial plateau angle was not measured.
SECUROS plate
Intra-operatively, the SECUROS TPLO plates (henceforward referred to as SECUROS plate) were individually adjusted using bending pliers (002063 medium bending pliers-premium, SECUROS Europe GmbH, Neuhausen ob Eck, Germany), a table-top bending press (002065 table-top bending press, SECUROS Europe GmbH, Neuhausen ob Eck, Germany) or plate benders (001142 plate benders, SECUROS Europe GmbH, Neuhausen ob Eck, Germany).
Standard 3,5mm stainless steel cortical bone screws (3.5mm non self-tapping cortical bone screws, SECUROS Europe GmbH, Neuhausen ob Eck, Germany) were used in all six or eight plate holes respectively. Numbering the holes consecutively beginning with the most proximal (#1) to the most distal (#6/#8), the screws were placed in the following order: 5, 3, 2, 4, 6 and 119 or 7, 4, 2, 6, 5, 8, 1 and 3. Before inserting and tightening the screws each hole was drilled, measured and tapped.
Synthes® TPLO plate
The Synthes® TPLO plate (henceforward referred to as Synthes plate) combines the features of a locking plate in its plate head and a LC-DCP in its plate shaft. In its head the Synthes plate provides threaded plate holes, which mate with the threads on the head of the locking head screws and are angled away from the articular surface and the osteotomy facilitating safe and optimal screw placement32. The lower surface of the plate shaft with its notches reduces the plate-bone contact area.
As only 3.5mm self-tapping locking screws (VS303.010-VS303.070 3.5mm locking screws, self-tapping with StarDrive recess, Synthes® Vet, Oberdorf, Switzerland)were used in the plate head, individual plate contouring during surgery was not carried out. Numbering the plate holes beginning with the most proximal (#1) to the most distal (#6/#8), screws were inserted in the following order32: #4 (proximal DCP shaft hole), #2 (most cranial head hole),
#1 (most proximal head hole), #6 (most distal DCP shaft hole), #3 (most caudal head hole) and #5 (midshaft Combi hole) or #5 (proximal DCP shaft hole), #1 (most proximal head hole), #2 (most cranial head hole), #8 (most distal DCP shaft hole), #3 (most caudal head hole), #4 (central head hole), #6 (proximal shaft Combi hole) and #7 (distal shaft Combi hole). Before a plate head hole was filled, the screw hole was drilled with a 2.8mm drill bit (310.288 2.8mm Drill Bit, quick coupling, Synthes® Vet, Oberdorf, Switzerland) through a
2.8mm threaded drill guide (312.648 2.8mm threaded Drill Guide, Synthes® Vet, Oberdorf, Switzerland) to ensure proper direction of the drill bit permitting correct alignment of the threads in the plate hole with the locking threads of the screw head. A power drill with a 1.5 Nm torque-limiting attachment (511.773 Torque Limiting Attachment, quick coupling, 1.5 Nm, Synthes® Vet, Oberdorf, Switzerland) was used for locking screw tightening to prevent cold-weld induced by over-tightening. In the plate shaft only 3.5mm stainless steel cortical bone screws were used with the proximal and the distal screw in compression position.
Post-operative management
Post-operatively carprofen (Rimadyl® palatable tablets, Pfizer GmbH, Berlin, Germany)(4,4mg/kg SID orally) and cefixim (CEFIXIM-ratiopharm 200mg filmcoated tablets, ratiopharm GmbH, Ulm, Germany)(10mg/kg BID orally) were administered for 10 and five days respectively. Cold compression therapy was performed in all patients applying ice packs every four to six hours for 10-15 minutes starting when recovering from anaesthesia until 48 hours after surgery33,34. The dogs were hospitalized for three days. All owners were given detailed oral and written discharge instructions for post-operative confinement in a cage or small room, recommending only short leash-walks up to six times daily with a maximum of 10 minutes per walk, no playing, jumping or stair climbing for six weeks followed by slow and gradual extension of leash-walks over the following four weeks.
Complications
Complications were documented during hospitalisation and in the following reported by owners.
All intra-operative technique- or implant-related complications were instantly addressed in the same anaesthetic period. Intra-operative bleeding was treated ligaturing the bleeding vessel and applying Lyostypt® absorbable compress (169128 Lyostypt® collagen compress 3cm x 5cm, B Braun Melsungen AG, Melsungen, Germany). Broken K-wires not exceeding the caudal border of the proximal segment were left in situ. Intra-articular screws were replaced.
Post-operative complications were divided in major and minor complications due to severity and clinical relevance25. Major complications were infection, screw/plate loosening, fibular fracture, implant breakage and osteomyelitis. Microbiological testing for diagnosis of infection was performed in all patients in which wound drainage or more than three of the following signs - redness, swelling, signs of pain, heat, deep wound dehiscence - were evident simultaneously. In the absence of bacterial growth the diagnosis was inflammation. Infections were treated medically according to the antibiogram24. Non-infective wound discharge alone was taken as a minor complication. Bone or implant related major complications such as screw loosening, fibular fracture, implant breakage or osteomyelitis were diagnosed radiographically. Loosened screws or broken implants were treated surgically, fibular fractures with activity restriction and osteomyelitis with antibiotic/anti-inflammatory medication. Minor complications such as wound exudation, seroma, inflammation and superficial suture dehiscence e.g. due to licking were treated topically when indicated.
Radiographic evaluation
For assessment of osteoarthritis (OA) mediolateral and craniocaudal radiographs of the affected joint were taken pre-operatively, at three and six month follow-up. Radiographic signs of OA were graded by three experienced surgeons using a modified 0 to 3 scoring system35 (Tab. 1). Post-operative osteotomy healing was subjectively graded by evaluation of osseous bridging of the osteotomy site as a percentage of complete bridging36. Each investigator evaluated all radiographs in a randomized order with different orders for pre- operative, three and six months post-operative radiographs. Due to the uniquely shaped implants it was not possible to blind the radiologic examination.
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0 No visible signs of OA
1 Mild OA, e.g. periarticular osteophytosis
2 Moderate OA, e.g. periarticular osteophytosis and bone sclerosis
3 Severe OA, e.g. periarticular and intraarticular osteophytosis, bone sclerosis and subchondral bone lysis
Lameness
Lameness was assessed by a veterinarian at the clinic and by the owner in the home environment.
Veterinary lameness assessment at the clinic
Lameness was scored at walk and trot by the same examiner at time of admission, at three and six months follow-up using a modified 0-4 lameness scoring system37 (Tab. 2).
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0 no clinical lameness 1 slight lameness
2 moderately lame at all gaits, bears majority of weight on affected limb with each step
3 severely lame at all gaits, bears some weight on the affected limb 4 complete non-weight bearing on the affected limb
Owner assessment in home environment
A multiple-choice based questionnaire was used for owner assessment of lameness at three months and six months post-operatively. On the basis of these results, clinical outcome regarding lameness was evaluated on a 0 to 3 score38 (Table 3).
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0 ‚excellent’ = without any lameness, even after rest or intense activity no signs of discomfort
1 ‚good’ = slight intermittent lameness occurring after rest or activity, but most of the time without any lameness
2 ‚acceptable’ = moderate intermittent lameness occurring after rest or activity, but most of the time without any lameness or slight intermittent lameness occurring about half of the time
3 ‚unsatisfactory’ = persistent lameness of any degree
Direct effect of surgery
Was reported weekly by owners grading the lameness in comparison to the status prior to surgery (worse, unchanged, improved).
Normal activity level
Clients reported weekly whether or not the dog had reached the activity level he had before the onset of CrCL disease regarding willingness to jump and play and duration of walks taken without any problems.
Owner satisfaction
Whether or not owners were satisfied with the outcome of TPLO surgery was reported at the end of the study in the client-questionnaire.
Statistical analysis
All statistical analyses were performed using SPSS Student Version™ 15.0 und SPSS Version™ 17 (© 2007 SPSS Inc., Chicago, USA). Descriptive statistics were used to evaluate basic properties of the data, including mean values and standard deviations. Combinations of qualitative data were analysed using a 2-tailed Pearson Chi2-analysis or a Fisher’s Exact Test to test for relationships between independent variables and outcome. For quantitative data non-parametric Mann–Whitney U-tests were performed to test for differences between treatment groups and the Wilcoxon signed rank test for repeated measures. A P-value ! 0.05 was considered significant. Data are reported as mean±SD unless otherwise stated.
Results
There was no significant difference between the Synthes and the SECUROS group in age (range: one to eleven years; Synthes group: 5.2±2.8 years; SECUROS group: 4.6±2,4 years), body weight (range: 22 to 72.5kg; Synthes group: 42.0±14kg; SECUROS group:
40.8±10.8kg), BCS (range: two to nine; Synthes group: 5.4±1.5; SECUROS group: 5.7±1.7), gender (males: 10=intact, 7=neutered; females: 9=intact, 11=spayed), duration of lameness prior to surgery 2.9±2.5 months (range: three days to one year), history of trauma, medical pre-treatment and time intervals to first (Synthes: 13.0±2.7 weeks; SECUROS: 12.7±2.7 weeks, p=0.84) and second follow-up (Synthes: 26.1±3.4 weeks; SECUROS: 25.8±2.9 weeks, p=0.72).
Surgery
At time of surgery 31/39 joints (79,5%) (Synthes: 15/19; SECUROS: 16/20) were diagnosed with complete and 8/39 (20.5%) (Synthes: 4/19; SECUROS: 4/20) joints with partial rupture of the CrCL. Meniscal injury was identified in 21 cases (53.8%) (Synthes: 9/19; SECUROS:
12/20), in 18 cases (46.2%) (Synthes: 10/19; SECUROS: 8/20) the meniscus was macroscopically intact.
Complications
Intra-operative complications occurred in seven cases (Synthes group n=5; SECUROS group n=2) with no statistically significant difference between treatment groups (p=0.5). These were in the Synthes group breakage of a K-wire after being struck by a screw or drill bit (n=2) (Figure 1) and intra-operative bleeding (n=3) and in the SECUROS group intra-articular screw placement in two cases, one of them combined with intra-operative bleeding. Post- operative radiographs revealed screw placement close to the articular surface (n=3) in the SECUROS group not requiring screw replacement and therefore not included for calculation of complication rate.
The occurrence of post-operative complications in general was 35% in the SECUROS group and 10.5% in the Synthes group. This difference was not statistically significant (p=0.127)(Tab. 4). The overall post-operative complication rate was 23.1% (9/39) with a minor complication rate of 15.4% (6/39) and major complication rate of 7.7% (3/39). All
documented major post-operative complications occurred in the SECUROS group (3/20, 15%) and were in part combined with minor complications. The numerical differences between treatment groups regarding the occurrence of minor or major complications were not statistically significant (p=0.391 and p=0.103).
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Post-operative complications (% within treatment group)
Treatment group none minor major Total (%) Synthes 17 (89.5) 2 (10.5) - (0) 19 (48.7) SECUROS 13 (65) 4 (20) 3 (15) 20 (51.3) Total (%) 30 (76.9) 6 (15.4) 3 (7.7) 39 (100)
Minor complications were superficial suture dehiscence (Synthes group), inflammation, wound discharge and seroma formation occurring individually in one case each and inflammation with wound discharge in one case of each treatment group.
Major complications were in the first case fibular fracture, wound discharge, seroma formation and superficial suture dehiscence, in the second case infection with mild wound discharge and in the third case severe infection with excessive infectious discharge, deep suture dehiscence and osteomyelitis in consequence of screw/plate loosening, implant breakage and fibular fracture. The latter was a two year-old female Doberman pinscher. The SECUROS plate broke 14 days after TPLO surgery, presumably due to uncontrolled activity.
Revision surgery was performed. Complete wound healing was not achieved until implants were removed twelve weeks after initial TPLO surgery. Throughout this time, the dog showed almost no lameness and lameness completely resolved almost immediately after implant removal. There were no major post-operative complications in the Synthes group.
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Radiographic evaluation
OA scores did not significantly differ between groups pre-operatively (p=0.42), three months (p=0.54) and six months (p=0.25) post-operatively. There was a slight but significant increase in OA score between three and six months post-operatively (p=0.014). The increase of OA did not significantly differ between groups at any time point. The initial OA score in comparison to the six months post-operative OA score compared between treatment groups is shown in Table 5 and its respective increase in Table 6. Osseous bridging at three and six months did not differ significantly between groups (p=0.12 and p=0.15).
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Pre-operative OA score Treatment
group none slight moderate severe Total (%)
none 3 - - - 3 (15.8)
slight 1 1 - - 2 (10.6)
moderate 1 - 6 - 7(36.8)
Post-
operative OA score (six
months) severe 0 - 3 4 7(36.8)
Synthes
Total (%) 5 (26.3) 1 (5.3) 9 (47.4) 4 (21) 19 (100)
none 1 - - - 1 (5)
slight 2 7 - - 9 (45)
moderate - 1 5 - 6 (30)
Post-
operative OA score (six
months) severe - - 1 3 4 (20)
SECUROS
Total (%) 3 (15) 8 (40) 6 (30) 3 (15) 20 (100)
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Increase of OA six months post- operatively
Treatment
group
no increase
by 1 degree
by 2
degrees Total (%)
none 3 1 1 5 (26.3)
slight 1 - - 1 (5.3)
moderate 6 3 - 9 (47.4)
pre- operative OA score
severe 4 - - 4 (21)
Synthes
Total (%) 14 (73.7) 4 (21) 1 (5.3) 19 (100)
none 1 2 - 3 (15)
slight 7 1 - 8 (40)
moderate 5 1 - 6 (30)
Pre- operative OA score
severe 3 - - 3 (15)
SECUROS
Total (%) 16 (80) 4 (20) - 20 (100)
Lameness
Veterinary lameness assessment at the clinic
At the six months follow-up, lameness had decreased in all 39 joints with no lameness seen in 82.1% (32/39) of joints (Synthes group 84.2%, 16/19, SECUROS group 80%, 16/20) and slight lameness in 17.9% (7/39) (Synthes group 15.8%, 3/19; SECUROS 20%, 4/20)(Tab. 7).
There was no moderate or severe lameness. In both groups lameness had already significantly improved between pre-operatively and three months follow-up (Synthes group: p<0.001;
SECUROS group p<0.001) and again between three and six months follow-up (Synthes group p=0.023; SECUROS group p=0.004). There were no significant differences in lameness between treatment groups at any time point.
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Pre-operative lameness Treatment
group 1 2 3 4 Total (%)
0 1 8 7 - 16 (84.2)
1 - 2 1 - 3 (15.8)
Post- operative lameness (six months)
2 - 4 - - - - - (0)
Synthes
Total (%) 1 (5.3) 10 (52.6) 8 (42.1) - (0) 19 (100)
0 5 2 9 - 16 (80)
1 - 1 2 1 4 (20)
Post- operative lameness
(six months) 2 - 4 - - - - - (0)
SECUROS
Total (%) 5 (25) 3 (15) 11 (55) 1 (5) 20 (100)
Owner assessment in home environment
In both treatment groups, there was a significant improvement in owner-assessed lameness between three and six months, but there were no statistically significant differences in owner- assessed lameness between treatment groups at any time point. At six months post-operatively lameness was judged as follows: ‘excellent’ in 79.5% (31/39) of cases (Synthes group: 79%, 15/19; SECUROS group: 80%, 16/20)(Figures 2 and 3), ‘good’ in 17.95% (7/39) of cases (Synthes group: 15.8%, 3/19 SECUROS group: 20%, 4/20) and ‘acceptable’ in one case (2.6%) (Synthes group). The latter dog was a 6.5 year-old Great Dane with already severe OA in the affected stifle at admission showing a slight intermittent lameness occurring about half of the day. Owners were totally satisfied with the outcome and their dog having almost regained his normal level of activity. In seven of nine patients who had suffered from post- operative complications the outcome was judged ‘excellent’ (Synthes group n=1, SECUROS group n=6) and ‘good’ in the remaining two patients (one of each treatment group). The differences between groups were not significant.
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Direct effect of surgery
Pre-operative lameness status was reached after a mean of 4.48±2.44 weeks (Synthes group 4.3±2.2 weeks; SECUROS group 4.6±2.7 weeks), followed by continuous improvement in all dogs beginning at an average of 6.10±5.12 weeks post-operatively (Synthes group 6.16±5.56 weeks; SECUROS group 6.05±4.82 weeks). There were no significant differences regarding these parameters between treatment groups.
Normal activity level
76.9% (30/39) of the dogs regained their normal activity level within the 24 weeks after surgery (Synthes group: 79%, 15/19, 10.7±6.2 weeks; SECUROS group 75%, 15/20, 13.1±5.9 weeks). The remaining nine dogs (23.1%) did not regain their normal activity level within 24 weeks, but showed marked improvement. Seven of nine patients who suffered from post-operative complications (Synthes group n=1; SECUROS group n=6) regained their normal activity level 13.7±5.7 weeks after surgery. The remaining two dogs (Synthes group n=1; SECUROS group n=1) showed markedly improved lameness compared to pre-operative status.
Owner satisfaction
Owner satisfaction with the clinical outcome was high (94.9%, 37/39) without significant differences between groups (Synthes group: 94.7%, 18/19; SECUROS group 95%, 19/20;
p=0.97) and regardless of the performing surgeon (p=0.283) or the occurrence of post- operative complications (p=0.43).
Discussion
This study focused on the comparison of TPLO surgery using conventional SECUROS versus locking Synthes TPLO plates with respect to clinical outcome, complication rate and progression of OA over a six months period. In none of the parameters under study statistically significant differences were found between treatment groups. However, within this small sample of patients, there was still evidence of a trend towards fewer intra-operative complications that were implant/technique related and affected the joint and a lower frequency of post-operative complications in the Synthes group. Although our surgeons used the Synthes TPLO plate system for the first time at the beginning of this study and, consequently, were less experienced than with the SECUROS plate, the normal activity level in this group was achieved in a shorter period of time.
As to its objectivity, computer-assisted gait analysis was recommended for assessment of lameness in dogs39,40. However, the existence of a physiological gait pattern while walking on a treadmill is not proven yet for dogs and is also controversially discussed in human medicine41,42. Therefore, and since some dogs completely refuse to walk on a treadmill, visual assessment of lameness was performed in this study, which recently was shown to be highly repeatable and hence adequate 37. Lameness assessment performed by a veterinarian is very useful but also has some limitations as the results may be biased by temperament and patient anxiety in unusual surroundings, as well as time and duration of examination35. For this reason, and as owner assessment of outcome following cranial cruciate ligament surgery was shown the be acceptable and reliable43, clinical outcome regarding lameness was evaluated separately based on owner assessement in home environment.
So far, results of dogs treated with TPLO surgery have been encouraging. The results reported in the original study by Slocum and Slocum2 are similar to the results obtained in this study with excellent clinical outcome in 79.5% of cases. This is also confirmed by the study of Barnhart44 in which, based on owner evaluation, even dogs treated with single- session bilateral TPLO were reported to have good or excellent results in the majority of cases. Freedom of lameness in 100% of cases, however, as reported by Boyd et al.45 at least one year after TPLO was not achieved in this study. But, due to different follow-up periods, direct comparison is difficult.
The overall complication rate in the present study is comparable to other studies24,25,29,30
whereas complications and especially major complications were less frequent in the Synthes group. When the Synthes plate was used the first and second time in this study, the K-wire
‘stick-pin’ was struck by the 2.8mm drill or a self-taping screw and consecutively broke when it should be removed. This may be ascribed to the new implant with its unique screw angulation and was easily avoided thereafter with improving of surgeons’ skills. Despite several years of experience, misdirected screws or intra-articular screw placement have been reported to occur with TPLO surgery24,25,30,46. In the present study, intra-articular screw placement and screw placement close to the articular surface were seen in the SECUROS group only, indicating that with this plate a certain risk of intra-articular screw placement remains even for experienced surgeons. Although owners’ assessment of outcome in these patients did not significantly differ from other patients30, this complication should be avoided, for example by use of the Synthes plate.
Post-operative infection rates in dogs for clean surgical procedures range from 1.6%- 2.5%47, whereas following TPLO surgery the rate of infection has been reported at 3%- 8.4%24-26,29,30,48,49. Suggested explanations for increased infection rates associated with tibial plateau surgery include, inter alia, implant characteristics49,50 and application of plates of large surface area to relatively small bone segments in tight periosteal apposition at a superficial site24. In the Synthes group, there were no post-operative infections. But whether this was truly due to the features related to the Synthes plate or a result of the small sample needs to be investigated in further clinical studies.
In contrast to the initially stated completely2 or almost stopped51,52 progression of OA following TPLO surgery but in agreement with other studies45,53-57, we found a slight, but nonetheless significant deterioration of osteoarthritic changes in the affected stifle joints at six months follow-up in both groups. Even by use of Synthes plates, progression of OA could not be stopped.
In accordance with Priddy et al.30 owners were satisfied with the outcome of TPLO surgery in more than 90% of cases.
In conclusion, especially for surgeons less trained in performing TPLO surgery, the Synthes plate provides for very comfortable and safe handling and with regards to the advantages mentioned above, the Synthes plate is a suitable alternative to the SECUROS
plate. Although clinical outcome did not significantly differ between groups, there was evidence of a trend towards fewer intra-operative complications that were implant/technique related and affected the joint and a lower frequency of post-operative complications in the Synthes group.
Owing to the small number of dogs, it would be interesting to determine whether the results of the present study would be supported in a larger prospective study.
Acknowledgement
We would like to thank the team of clinicians and technicians at the clinic for small animals, university of veterinary medicine Hannover, foundation for looking after the dogs in the time of hospitalisation and owners for participation.
References
1. Johnson JA, Austin C, Breur GJ: Incidence of canine appendicular musculoskeletal disorders in 16 veterinary teaching hospitals from 1980 through 1989. Vet Comp Orthop Traumatol 7:56-69, 1994.
2. Slocum B, Slocum TD: Tibial plateau leveling osteotomy for repair of cranial cruciate ligament rupture in the canine. Vet Clin North Am Small Anim Pract 23:777-795, 1993.
3. Shahar R, Milgram J: Biomechanics of tibial plateau leveling of the canine cruciate- deficient stifle joint: a theoretical model. Vet Surg 35:144-149, 2006.
4. Baroni E, Matthias RR, Marcellin-Little DJ, et al: Comparison of radiographic assessments of the tibial plateau slope in dogs. Am J Vet Res 64:586-589, 2003.
5. Gardner MJ, Griffith MH, Demetrakopoulos D, et al: Hybrid locked plating of
osteoporotic fractures of the humerus. J Bone Joint Surg Am 88:1962-1967, 2006.
6. Greiwe RM, Archdeacon MT: Locking plate technology: current concepts. J Knee Surg 20:50-55, 2007.
7. Alexander AH, Cabaud HE, Johnston JO, et al: Compression plate position.
Extraperiosteal or subperiosteal? Clin Orthop Relat Res:280-285, 1983.
8. Gautier E, Rahn BA, Perren SM: Vascular remodelling. Injury 26 Suppl 2:B11-B19, 1995.
9. Jacobs RR, Rahn BA, Perren SM: Effects of plates on cortical bone perfusion. J Trauma 21:91-95, 1981.
10. Matter P, Burch HB: Clinical experience with titanium implants, especially with the limited contact dynamic compression plate system. Arch Orthop Trauma Surg 109:311-313, 1990.
11. Perren SM, Cordey J, Rahn BA, et al: Early temporary porosis of bone induced by internal fixation implants. A reaction to necrosis, not to stress protection? Clin Orthop Relat Res:139-151, 1988.
12. Van Haasnoot FE, Münch WH, Matter P, et al: Radiological sequences of healing in internal plates and splints of different surface to bone (DCP, LC-DCP and PC-Fix).
Injury 26 Suppl 2:B28-B36, 1995.
13. Gautier E, Perren SM: [Limited Contact Dynamic Compression Plate (LC-DCP)-- biomechanical research as basis to new plate design]. Orthopade 21:11-23, 1992.
14. Melcher GA, Claudi B, Schlegel U, et al: Influence of type of medullary nail on the development of local infection. An experimental study of solid and slotted nails in rabbits. J Bone Joint Surg Br 76:955-959, 1994.
15. Perren SM, Klaue K, Pohler O, et al: The limited contact dynamic compression plate (LC-DCP). Arch Orthop Trauma Surg 109:304-310, 1990.
16. Perren SM: The concept of biological plating using the limited contact-dynamic
compression plate (LC-DCP). Scientific background, design and application. Injury 22 Suppl 1:1-41, 1991.
17. Wagner M: General principles for the clinical use of the LCP. Injury 34 Suppl 2:B31-42, 2003.
18. Conkling AL, Fagin B, Daye RM: Comparison of tibial plateau angle changes after tibial plateau leveling osteotomy fixation with conventional or locking screw technology.
Vet Surg 39:475-481, 2010.
19. Kloc PA, 2nd, Kowaleski MP, Litsky AS, et al: Biomechanical comparison of two alternative tibial plateau leveling osteotomy plates with the original standard in an axially loaded gap model: an in vitro study. Vet Surg 38:40-48, 2009.
20. Egol KA, Kubiak EN, Fulkerson E, et al: Biomechanics of locked plates and screws. J Orthop Trauma 18:488-493, 2004.
21. Frigg R: Locking Compression Plate (LCP). An osteosynthesis plate based on the Dynamic Compression Plate and the Point Contact Fixator (PC-Fix). Injury 32 Suppl 2:63-66, 2001.
22. Bordelon J, Coker D, Payton M, et al: An in vitro mechanical comparison of tibial plateau levelling osteotomy plates. Vet Comp Orthop Traumatol 22:467-472, 2009.
23. Leitner M, Pearce SG, Windolf M, et al: Comparison of locking and conventional screws for maintenance of tibial plateau positioning and biomechanical stability after locking tibial plateau leveling osteotomy plate fixation. Vet Surg 37:357-365, 2008.
24. Fitzpatrick N, Solano MA: Predictive variables for complications after TPLO with stifle inspection by arthrotomy in 1000 consecutive dogs. Vet Surg 39:460-474, 2010.
