N.P. Südkamp

Cartilage repair approach and treatment characteristics across the knee joint: a European survey

IntroductionTo describe indication, approach and treatment modalities for the management of knee cartilage lesions among a selected European population.MethodsAn electronic questionnaire covering general and specific items concerning cartilage repair at the knee joint was designed and disposed to survey cartilage treatment characteristics among a defined population of trained and accredited musculoskeletal surgeons.ResultsA total of 242 (80.13%) interviewees returned the questionnaire. Two-thirds of the respondents considered patient age to not limit (33.1%) or considered the age of 50 as the upper limit (32.2%) for interventional cartilage surgery. There was no consensus on when to correct mechanical axis deformation. Irrespective of lesion size, surgical debridement and microfracture are the techniques most frequently used. Surgical approach to full-thickness cartilage defects is commenced when the lesion size exceeds 1xa0cm2 in 75.6% of respondents; mainly utilizing microfracture or debridement for defects smaller than 1, 2 and 3xa0cm2. Controversy exists for treatment of lesions exceeding 3xa0cm2, where autologous chondrocyte transplantation is utilized in the majority of cases (33.5%), while as well microfracture (19.0%) and with lesser frequency osteochondral plug (9.5%) transplantation are recommended. Debridement was indicated to be used in combination with other techniques, while microfracture, chondrocyte or osteochondral plug transplantation are applied as individual techniques.ConclusionsMicrofracture with debridement are the two most frequently used operations in lesions up to 3xa0cm2. There remains disagreement when indicating cartilage repair when age, mechanical axis deviation or treatment of lesions over 3xa0cm2 are concerned.

Injury severity and localisations seen in polytraumatised children compared to adults and the relevance for emergency room management

PURPOSEnThe treatment of paediatric polytrauma patients in the emergency room is not common. The knowledge of specific injuries in consideration of the age-specific characteristics is of particular importance for precise diagnostics and therapy. The goal of this study is the aquisition of the frequency, the localisation and the severity of paediatric polytrauma (age: 0-16 years) in comparison with adults.nnnPATIENTS AND METHODSnIn the period 7 / 01 to 5 / 04 the localisation and injury severity of 23 paediatric polytrauma patients (age: 2-16 years) were compared retrospectivly with those of 324 adults (age: 17-88 years). In the paediatric group (ISS: 31) the lethality was 17 % and so much higher than that in the grown-up population (ISS: 33) with 10 % at comparable injury severity. The cause of accident and the injury severity of the affected body region were analysed. The severity of the diffferent body regions were classified by the Abbreviated Injury Severity Score (AIS). The results were discussed with regard to the current literature.nnnRESULTSnWith 65 %, more than every second child suffered from severe head injuries (AIS > 2), whereas only 37 % of the adults were affected in this way. The different types of intracranial bleedings were analysed and compared. Heavy injuries of the thorax (AIS > 2) were the result of an accident in 61 % of the children and in 54 % of the adults. The incidence of children with injuries to the abdomen was 30 % compared to 31 % in the grown-up collective. Lesions of the spleen and liver had a frequency of 13 to 16 %. Injuries of the spine could be only found in 4 % of the children compared to 40 % of the adult group. The frequencies of pelvic injuries were similar at 22 % for children and 28 % for adults. With 13 % for the upper extremities and 17 % for the lower extremities, children were much less injured in these body regions. In the group of adults 43 % had injuries to the upper extremities and 33 % injuries to the lower extremities.nnnCONCLUSIONSnTaking the results into account with consdieration of the literature data, the authors recommend that the emergency room management for adults and, especially, the radiolgical diagnostic chain with CT scans should also be applied to polytraumatised children. The main reasons for this are the extremely high incidence of intracranial injuries and the high sensitivity of CT scans also for abdominal trauma and pelvic injuries.Purpose: The treatment of paediatric polytrauma patients in the emergency room is not common. The knowledge of specific injuries in considera- tion of the age-specific characteristics is of par- ticular importance for precise diagnostics and therapy. The goal of this study is the aquisition of the frequency, the localisation and the severi- ty of paediatric polytrauma (age: 0-16years) in comparison with adults. Patients and Methods:In the period 7/01 to 5/04 the localisation and injury severity of 23paediat- ric polytrauma patients (age: 2-16years) were compared retrospectivly with those of 324adults (age: 17-88years). In the paediatric group (ISS: 31) the lethality was 17% and so much higher than that in the grown-up population (ISS: 33) with 10% at comparable injury severity. The cause of accident and the injury severity of the affected body region were analysed. The severity of the diffferent body regions were classified by the Abbreviated Injury Severity Score (AIS). The results were discussed with regard to the current literature. Results: With 65%, more than every second child suffered from severe head injuries (AIS >2), whereas only 37% of the adults were affected in this way. The different types of intracranial blee- dings were analysed and compared. Heavy inju- ries of the thorax (AIS >2) were the result of an accident in 61% of the children and in 54% of the adults. The incidence of children with injuries to the abdomen was 30% compared to 31% in the grown-up collective. Lesions of the spleen and liver had a frequency of 13 to 16%. Injuries of the spine could be only found in 4% of the children compared to 40% of the adult group. The fre- quencies of pelvic injuries were similar at 22% for children and 28% for adults. With 13% for the upper extremities and 17% for the lower extremi- ties, children were much less injured in these

Reoperative characteristics after microfracture of knee cartilage lesions in 454 patients

PurposeThere is only limited information on those patients who fail following microfracture treatment at the knee joint. Evaluation was made of factors associated with treatment failure and clinical outcome assessment among this collective.MethodsThe study included a total of 560 patients who had previously undergone microfracture for the treatment of symptomatic knee joint cartilage lesions. For the remainder of this study, inclusion criteria were patients that underwent reoperation at the initially operated knee joint (index knee) due to symptoms related to the primary site of microfracture intervention (failure patients) with a minimum postoperative follow-up of 2xa0years. The remaining cohort of patients served as internal control (non-failure patients). Chart reviews were performed to identify patient and defect characteristics. Patients were evaluated for postoperative Lysholm knee scores, Tegner activity scale, as well as preoperative and postoperative numeric analogue scales (NAS) for function and pain (10xa0=xa0highest possible function, no pain).ResultsA total of 454/560 (81.1xa0%) subjects were completely evaluated. Overall, 123/454 patients (26.9xa0%) (age at operation 43.9xa0±xa014.1xa0years, 56 female, BMI 25.8xa0±xa03.6, 30 smokers, 61.1xa0±xa068.3xa0month symptom duration, postoperative follow-up 5.0xa0±xa02.1) met the inclusion criteria. The postoperative Lysholm score was 63.0xa0±xa024.6 and the Tegner score was 4.0; NAS function improved from 2.8xa0±xa01.8 to 4.8xa0±xa02.2 (Pxa0<xa00.001), and NAS pain improved from 3.2xa0±xa02.1 to 5.0xa0±xa02.4 (Pxa0<xa00.001). Exclusively, the overall defect size/knee joint was smaller (Pxa0=xa00.006), postoperative follow-up was longer (Pxa0=xa00.002), and existense of previous surgery (77.2 vs. 51.6xa0%, Pxa0<xa00.001) was more frequent in failure subjects when comparing to non-failure patients (nxa0=xa0331). The overall clinical outcome among failure subjects was significantly worse when comparing to non-failure subjects. Regression analysis identified that lower preoperative NAS values, being a smoker, and patello-femoral lesions were associated with a higher probability of reoperation.ConclusionWithin the collective presented here, microfracturing was associated with a high frequency of reoperation. Clinical outcome is worse when compared with that of patients without reoperation. Specific parameters can be identified that increase the eventuality of failure following microfracture treatment.Level of evidenceIV.

[Variability of the screw position after 3D-navigated sacroiliac screw fixation. Influence of the surgeon's experience with the navigation technique].

ZusammenfassungHintergrundDurch den Einsatz navigierter Verfahren kann bei der perkutanen transiliosakralen Verschraubung eine höhere Präzision erreicht werden. Zielsetzung dieser Studie war es, den Einfluss der Navigationserfahrung des Operateurs auf die Schraubenlage 3D-navigiert implantierter SI-Schrauben zu evaluieren.Patienten und MethodeIm Zeitraum 12/05 bis 02/08 wurden sämtliche in unserer Klinik navigiert eingebrachten SI-Schrauben prospektiv erfasst. Die Schraubenlage wurde postoperativ mittels eines Becken-CTs nach den Kriterien von Smith evaluiert und in Abhängigkeit von der Navigationserfahrung des Operateurs ausgewertet.ErgebnisseVon insgesamt 7 Operateuren wurden 37 SI-Schrauben bei 33xa0Patienten implantiert. In der Gruppe der Operateure mit geringer Navigationserfahrung zeigte sich trotz 3D-Navigation eine intraforaminale und eine intraspinale Schraubenlage, während bei Anwesenheit eines navigationserfahrenen Operateurs keine revisionspflichtigen Schraubenfehllagen zu verzeichnen waren. Bezüglich der Fehlplatzierungsrate zeigte sich kein signifikanter Unterschied zwischen den Gruppen.SchlussfolgerungIm klinischen Alltag kann es auch bei 3D-Navigation zu einer Fehlpositionierung von SI-Schrauben kommen. Als mögliche Ursache einer Schraubenfehlplatzierung muss eine geringe Navigationserfahrung des Operateurs in Kombination mit einer geringen Erfahrung in der konventionellen Technik diskutiert werden. Auch bei dreidimensionaler Darstellung der operativen Schritte kommt der persönlichen Erfahrung des Operateurs eine große Bedeutung zu. Die Schraubenlage sollte nach navigierter Implantation intraoperativ mittels 3D-Bildwandler überprüft werden.AbstractBackgroundThe precision of sacroiliac screw placement can be improved with the use of navigation techniques. The purpose of this study was to evaluate the accuracy of 3D-navigated sacroiliac screw positioning in relation to the surgeon’s experience with the navigation technique.Patients and methodsA consecutive series of 3D-navigated sacroiliac screw placements were prospectively evaluated between December 2005 and February 2008. Postoperatively the precision of screw placement was analyzed in relation to the surgeon’s navigation experience with a CT-scan using the criteria of Smith.ResultsA total of 37 screws were implanted by 7 surgeons in 33 patients. In the group of surgeons with less experience in navigation techniques two cases of malpositioning led to revision of the screws. No screws which were implanted or assisted by surgeons experienced in navigation needed to be revised. There was no significant difference in the malposition rate.ConclusionIn the clinical setup a malpositioning of sacroiliac screws is possible even with the use of 3D navigation. One reason may be a low level of navigation experience of the surgeon in combination with low experience in the conventional technique. Therefore even in navigation-based placement of sacroiliac screws the malpositioning rate is dependent on the surgeon’s experience with the navigation technique. The correct placement of the screws should be controlled intraoperatively using the 3D image intensifier.BACKGROUNDnThe precision of sacroiliac screw placement can be improved with the use of navigation techniques. The purpose of this study was to evaluate the accuracy of 3D-navigated sacroiliac screw positioning in relation to the surgeons experience with the navigation technique.nnnPATIENTS AND METHODSnA consecutive series of 3D-navigated sacroiliac screw placements were prospectively evaluated between December 2005 and February 2008. Postoperatively the precision of screw placement was analyzed in relation to the surgeons navigation experience with a CT-scan using the criteria of Smith.nnnRESULTSnA total of 37 screws were implanted by 7 surgeons in 33 patients. In the group of surgeons with less experience in navigation techniques two cases of malpositioning led to revision of the screws. No screws which were implanted or assisted by surgeons experienced in navigation needed to be revised. There was no significant difference in the malposition rate.nnnCONCLUSIONnIn the clinical setup a malpositioning of sacroiliac screws is possible even with the use of 3D navigation. One reason may be a low level of navigation experience of the surgeon in combination with low experience in the conventional technique. Therefore even in navigation-based placement of sacroiliac screws the malpositioning rate is dependent on the surgeons experience with the navigation technique. The correct placement of the screws should be controlled intraoperatively using the 3D image intensifier.

Salvage procedures for trochanteric femoral fractures after internal fixation failure: biomechanical comparison of a plate fixator and the dynamic condylar screw.

The aim of this study was the biomechanical evaluation of the reversed less invasive stabilization system (LISS) internal fixation as a joint-preserving salvage procedure for trochanteric fractures. Five LISS plates and five dynamic condylar screws (DCS) were tested using synthetic femora (Sawbones®) with an osteotomy model similar to a type-A2.3 pertrochanteric fracture. The constructs were subjected to axial loading up to 1000u2009N for five cycles. Then, the force was continuously increased until fixation failure. For the evaluation of the biomechanical behaviour, the stiffness levels were recorded and the osteotomy gap displacement was mapped three-dimensionally. The average stiffness for the constructs with LISS plates was 412u2009N/mm (with a standard deviation (SD) of 103N/mm) and 572u2009N/mm (SD of 116u2009N/mm) for the DCS constructs (pu2009=u20090.051). Local displacement at the osteotomy gap did not yield any significant differences. The LISS constructs failed at a mean axial compression of 2103u2009N (SD of 519u2009N) and the DCS constructs at a mean of 2572u2009N (SD of 372u2009N) (pu2009=u20090.14). It is concluded that the LISS plate offers a reliable fixation alternative for salvage procedures.

[Polytrauma in cyclists. Incidence, etiology, and injury patterns].

ZusammenfassungHintergrundIn der Region Freiburg nimmt in den letzten Jahren die Zahl der Fahrradfahrer und damit auch der Fahrradunfälle stetig zu. Ein nicht unbeachtlicher Teil unserer polytraumatisierten Patienten sind mit dem Fahrrad verunfallt. Wir haben eine retrospektive Auswertung der polytraumatisierten Fahrradfahrer des letzten Jahres durchgeführt.Material und MethodenIm Zeitraum von 05/2003 bis 06/2004 wurden Akten aller Polytraumatisierten nach Fahrradunfällen durchsucht und diese analysiert. Von insgesamt 153 Polytraumatisierten waren 32 Fahrradfahrer (21%). Das Alter war im Median 42 (7–82) Jahre, das Geschlechterverhältnis war 1:1.ErgebnisseDer „injury severity score“ (ISS) betrug im Median 24 (18–41), der Polytraumascore (PTS) war im Median bei 23 (14–51) und der „Glasgow coma scale“ (GCS) an der Unfallstelle im Median 8 (3–15). Die Verletzungsmuster wurden ausgewertet. 30xa0Patienten (94%) hatten als Diagnose ein Schädel-Hirn-Trauma (SHT), bei 28xa0Patienten (88%) war dies die führende Verletzung. Der AIS-Schädel war im Median bei 4 (1–5). Der AIS-Thorax lag im Median bei 3 (2–4). Der AIS-Extremitäten lag bei 3 (2–5). Unsere Zahlen wurden mit der Unfallstatistik der Polizeidirektion sowie der aktuellen Literatur verglichen.SchlussfolgerungAls häufigste und auch schwerste Verletzung wurde das SHT festgestellt, wobei unsere Ergebnisse mit der Literatur übereinstimmen. 30 der 32 polytraumatisierten Fahrradfahrer hatten keinen Helm getragen. Durch das regelhafte Tragen eines Fahrradhelms könnte möglicherweise die Verletzungsschwere bei Fahrradunfällen deutlich gesenkt werden.AbstractBackgroundIn our region we have noticed an increasing number of cyclists and consequently a rise in bicycle-related accidents in recent years. A large number of our polytraumatized patients are victims of bicycle-related accidents.Material and methodsRetrospectively we analyzed the data of our polytraumatized patients recorded between May 2003 and June 2004 for bicycle-related injuries. Of 153 polytraumatized patients treated in our emergency room 32 were cyclists (21%). The average age of our polytraumatized cyclist was 42xa0years, and the male-to-female ratio was 1:1.ResultsThe median score on the Glasgow Coma Scale (GCS) after the accident was 8 (min. 3, max. 15), the median Injury Severity Score (ISS) was 24 (min. 18, max. 41), and the median Polytrauma Score (PTS) was 23 (min. 14, max. 51). A total of 30 patients (94%) suffered a head injury; in 28 patients (88%) the head injury was the leading diagnosis. The median score on the Abbreviated Injury Scale (AIS) Head was 4 (min. 1, max. 5), the AIS Thorax 3 (min. 2, max. 4), and the AIS Extremities 3 (min, 2, max. 5). Our data were also compared with the official injury statistics of the region and the current literature.ConclusionThe most frequent and most severe injury was the head injury (94%). Of the 32 polytraumatized cyclists 30 did not wear a helmet. Successful prevention could possibly be practiced if all cyclists wear helmets.

Grenzen der Rekonstruktion – Prothesen

ZusammenfassungDie Humeruskopffraktur ist eine häufige Verletzung, insbesondere des älteren weiblichen Patienten. Im Rahmen der Osteosynthese lassen sich in der Regel gute klinische Ergebnisse erzielen. Probleme werden jedoch weiterhin bei den die varisch dislozierten Humeruskopffrakturen, insbesondere wenn die mediale Säule zerstört ist, beobachtet. Hier sind eine anatomische Reposition des Kalottenfragments sowie ein medialer Knochenkontakt für ein gutes Operationsergebnis unentbehrlich. Ansonsten lässt sich ein sekundärer Varuskollaps und/oder ein Implantatversagen vorhersehen. Weitere Herausforderungen bilden die intraartikulären Frakturformen sowie die initial ischämen Humeruskopffrakturen. Die Indikation zur Frakturprothese ist immer dann gegeben, wenn keine stabile Osteosynthese in adäquater Reposition erzielt werden kann. Inverse Frakturprothesen stellen eine zunehmend verbreitete Therapieoption dar. Sie sollten jedoch den älteren Patienten >75xa0Jahren vorbehalten bleiben.AbstractFractures of the proximal humerus are common, particularly seen in elderly, female patients. Using open reduction and internal fixation good clinical results can be achieved in general. But even today not every problem has been solved in the treatment of proximal humeral fractures. Varus displaced fractures are particularly challenging, especially when the medial column is destroyed. Anatomical reduction of the humeral head and medial bone contact are crucial for a good surgical outcome. Otherwise a secondary varus collapse and/or an implant failure are predictable. Further challenges are the intra-articular fracture patterns, as well as fractures with an initial ischemic humeral head. The indications for prosthetic replacement are always present if an initially stable internal fixation could not be achieved. The reverse fracture prostheses represent an increasingly common treatment option; however, the indication should be reserved for the elderly over 75 years.Fractures of the proximal humerus are common, particularly seen in elderly, female patients. Using open reduction and internal fixation good clinical results can be achieved in general. But even today not every problem has been solved in the treatment of proximal humeral fractures. Varus displaced fractures are particularly challenging, especially when the medial column is destroyed. Anatomical reduction of the humeral head and medial bone contact are crucial for a good surgical outcome. Otherwise a secondary varus collapse and/or an implant failure are predictable. Further challenges are the intra-articular fracture patterns, as well as fractures with an initial ischemic humeral head. The indications for prosthetic replacement are always present if an initially stable internal fixation could not be achieved. The reverse fracture prostheses represent an increasingly common treatment option; however, the indication should be reserved for the elderly over 75 years.

Traumatische Verletzungen des Sternoklavikulargelenks

ZusammenfassungTraumatische Verletzungen des Sternoklavikulargelenks sind selten und entstehen überwiegend indirekt im Rahmen eines Hochrasanztraumas. Während die anteriore Luxation des Sternoklavikulargelenks wesentlich häufiger auftritt, können posteriore Luxationen mit vital bedrohlichen Begleitverletzungen vergesellschaftet sein. Die Computertomographie ist die Diagnostik der Wahl zur Beurteilung der Gelenkstellung und Abklärung von Begleitverletzungen. Anteriore und posteriore Luxationen werden frühzeitig geschlossen reponiert und bei stabilen Gelenkverhältnissen primär konservativ therapiert. Bei Reluxation nach Reposition einer anterioren Luxation empfiehlt sich die primäre Gelenkrekonstruktion auf der Basis einer individuellen Therapieentscheidung. Die Reposition der posterioren Sternoklavikulargelenkluxation gelingt häufig nicht geschlossen. Dann erfolgt eine offene Reposition, primäre Gelenkrekonstruktion und Stabilisierung. Die operative Versorgung chronischer Luxationen ist bei persistierender Beschwerdesymptomatik und Funktionseinschränkung indiziert. Die mediale Klavikularesektion stellt bei posttraumatischer Arthrose eine gute Therapieoption dar, sofern der kostoklavikuläre Bandapparat stabil ist oder gleichzeitig rekonstruiert wird. Eine Verletzung der medialen Klavikulaepiphyse kann bis zu einem Alter von ca. 25xa0Jahren vorliegen. Bei dislozierten Epiphysenverletzungen führt nach geschlossener Reposition die konservative Therapie zu überwiegend guten klinischen Ergebnissen. Posterior dislozierte Epiphysenverletzungen sind der geschlossenen Reposition häufig nicht zugänglich. Hier lässt die offene Reposition und Fixation eine gute Funktion erwarten.AbstractTraumatic injuries of the sternoclavicular joint occur rarely and are mainly caused by an indirect trauma mechanism with high kinetic energy. Anterior dislocation is much more common than posterior dislocation, which may be associated with life-threatening injuries. The CT scan is the diagnostic tool of choice for accurate assessment of the injury and coexisting pathologies. The primary goal in anterior and posterior dislocations is an early closed reduction. In cases of redislocation after closed reduction of an anterior dislocation we recommend primary joint reconstruction on the basis of an individual therapeutic concept. Posterior dislocations often cannot be reduced by closed means. Then open reconstruction and stabilization are performed. Chronic instabilities should only be addressed surgically in cases of persistent pain and/or functional deficit. Resection of the medial clavicula represents an effective treatment option in post-traumatic sternoclavicular joint arthritis provided that the costoclavicular ligaments are intact or will be reconstructed during surgery. Physeal injuries of the medial clavicle can occur until an approximate age of 25. Closed reduction of dislocated physeal injuries is attempted. After reposition non-operative treatment in general leads to a good functional outcome. Posteriorly dislocated physeal injuries often cannot be reduced by closed means. In these cases good function can be expected after open stabilization.

[Limitations of reconstruction - prostheses].

ZusammenfassungDie Humeruskopffraktur ist eine häufige Verletzung, insbesondere des älteren weiblichen Patienten. Im Rahmen der Osteosynthese lassen sich in der Regel gute klinische Ergebnisse erzielen. Probleme werden jedoch weiterhin bei den die varisch dislozierten Humeruskopffrakturen, insbesondere wenn die mediale Säule zerstört ist, beobachtet. Hier sind eine anatomische Reposition des Kalottenfragments sowie ein medialer Knochenkontakt für ein gutes Operationsergebnis unentbehrlich. Ansonsten lässt sich ein sekundärer Varuskollaps und/oder ein Implantatversagen vorhersehen. Weitere Herausforderungen bilden die intraartikulären Frakturformen sowie die initial ischämen Humeruskopffrakturen. Die Indikation zur Frakturprothese ist immer dann gegeben, wenn keine stabile Osteosynthese in adäquater Reposition erzielt werden kann. Inverse Frakturprothesen stellen eine zunehmend verbreitete Therapieoption dar. Sie sollten jedoch den älteren Patienten >75xa0Jahren vorbehalten bleiben.AbstractFractures of the proximal humerus are common, particularly seen in elderly, female patients. Using open reduction and internal fixation good clinical results can be achieved in general. But even today not every problem has been solved in the treatment of proximal humeral fractures. Varus displaced fractures are particularly challenging, especially when the medial column is destroyed. Anatomical reduction of the humeral head and medial bone contact are crucial for a good surgical outcome. Otherwise a secondary varus collapse and/or an implant failure are predictable. Further challenges are the intra-articular fracture patterns, as well as fractures with an initial ischemic humeral head. The indications for prosthetic replacement are always present if an initially stable internal fixation could not be achieved. The reverse fracture prostheses represent an increasingly common treatment option; however, the indication should be reserved for the elderly over 75 years.Fractures of the proximal humerus are common, particularly seen in elderly, female patients. Using open reduction and internal fixation good clinical results can be achieved in general. But even today not every problem has been solved in the treatment of proximal humeral fractures. Varus displaced fractures are particularly challenging, especially when the medial column is destroyed. Anatomical reduction of the humeral head and medial bone contact are crucial for a good surgical outcome. Otherwise a secondary varus collapse and/or an implant failure are predictable. Further challenges are the intra-articular fracture patterns, as well as fractures with an initial ischemic humeral head. The indications for prosthetic replacement are always present if an initially stable internal fixation could not be achieved. The reverse fracture prostheses represent an increasingly common treatment option; however, the indication should be reserved for the elderly over 75 years.

Biomechanical investigation of a minimally invasive posterior spine stabilization system in comparison to the Universal Spinal System (USS)

BackgroundAlthough minimally invasive posterior spine implant systems have been introduced, clinical studies reported on reduced quality of spinal column realignment due to correction loss. The aim of this study was to compare biomechanically two minimally invasive spine stabilization systems versus the Universal Spine Stabilization system (USS).MethodsThree groups with 5 specimens each and 2 foam bars per specimen were instrumented with USS (Group 1) or a minimally invasive posterior spine stabilization system with either polyaxial (Group 2) or monoaxial (Group 3) screws.Mechanical testing was performed under quasi-static ramp loading in axial compression and torsion, followed by destructive cyclic loading run under axial compression at constant amplitude and then with progressively increasing amplitude until construct failure.Bending construct stiffness, torsional stiffness and cycles to failure were investigated.ResultsInitial bending stiffness was highest in Group 3, followed by Group 2 and Group 1, without any significant differences between the groups.A significant increase in bending stiffness after 20’000xa0cycles was observed in Group 1 (pu2009=u20090.002) and Group 2 (pu2009=u20090.001), but not in Group 3, though the secondary bending stiffness showed no significant differences between the groups.Initial and secondary torsional stiffness was highest in Group 1, followed by Group 3 and Group 2, with significant differences between all groups (pu2009≤u20090.047). A significant increase in initial torsional stiffness after 20’000xa0cycles was observed in Group 2 (pu2009=u20090.017) and 3 (pu2009=u20090.013), but not in Group 1.The highest number of cycles to failure was detected in Group 1, followed by Group 3 and Group 2. This parameter was significantly different between Group 1 and Group 2 (pu2009=u20090.001), between Group 2 and Group 3 (pu2009=u20090.002), but not between Group 1 and Group 3.ConclusionsThese findings quantify the correction loss for minimally invasive spine implant systems and imply that unstable spine fractures might benefit from stabilization with conventional implants like the USS.