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In total knee arthroplasty the femoral posterior condylar offset (PCO) may serve as a potential branch for correct femoral component positioning. The technique of adjusting the sagittal magnetic resonance imaging (MRI)-scan on which it is measured has not been investigated in previous literature, but may be subject to variances due to knee joint positioning or axial localizer scan angulation. The purpose of this study was to investigate the effect of simulated femur rotation on the accuracy of PCO measurement. Ten asymptomatic knee joints underwent MRI investigations. A sagittal plane perpendicular to the transepicondylar axis was defined as the true-sagittal plane (tsP). Sagittal images were reformatted in the tsP and angulated by 5° and − 5° in medial and lateral direction. In total each knee received three scans in 0°, 5° and − 5° axial localizer scan angulation. Medial and lateral PCO measurement was performed in each MRI-scan angulation. Simulated external rotation decreased medial PCO size by 1.7 mm (95% CI 0.5994–3.127) (p = 0.012), and simulated internal rotation increased medial PCO size by 2.1 mm (95% CI 1.142–2.994) (p = 0.001). Lateral PCO size increased by 1.9 mm (95% CI 0.5660–3.412) and decreased by 2.1 mm (95% CI 1.142–2.994) with simulated external and internal rotation, respectively (p = 0.011; p = 0.0007). This study shows the high sensitivity of medial and lateral PCO measurements to small changes of MRI axial localizer scan angulations simulating minor degrees of internal or external femur rotation. Thus, absolute PCO values should be interpreted with caution if the sagittal image acquisition is not standardized.

Durch die Zulassungsbeschrankungen zum Medizinstudium, sich andernde Anspruche an die „Work-Life-Balance“ und eingeschrankte langfristige berufliche Perspektiven kampfen insbesondere chirurgische Facher mit einem Nachwuchsmangel. Ziele der chirurgischen Abteilungen in der studentischen Ausbildung an den Universitatskliniken sind einerseits die konkrete Wissensvermittlung von fachlichen Zusammenhangen und andererseits das Wecken des Interesses fur die Chirurgie. Ziel der vorliegenden Studie war es, die Etablierung eines studentischen unfallchirurgischen Rufdienstes (RD-Stud) zu evaluieren und den Nutzen wissenschaftlich auszuwerten. In der vorliegenden Studie wurde der RD-Stud durch eine Pra-/Postevaluation anhand von Fragebogen mit der unterstutzenden Projektion von Rontgenbildern im Rahmen eines Lehrmoduls vergleichend mit Studierenden des 4. Fachsemesters und PJ-Studierenden untersucht. Die Rufdienststudierenden wiesen dabei sowohl vor der Lehreinheit als auch danach bessere Testergebnisse auf als die beiden anderen Gruppen. Durch die Etablierung eines RD-Stud zur Assistenz im Schockraum und bei operativen Notfalleingriffen konnen die Studierenden das Verstandnis fur chirurgische Diagnosestellung und Therapiekonzepte verbessern. Gleichzeitig erlernen sie eine zunehmende Sicherheit bei fachlichen Entscheidungen. Bei einem nur geringen Zusatzlehraufwand wird hierdurch eine erfolgreiche Nachwuchsforderung realisiert. Durch den RD-Stud konnte die Arbeitsbelastung der arztlichen Kollegen reduziert werden. Aufgrund einer geminderten Inanspruchnahme des arztlichen Rufdienstes konnten Personalkosten in Hohe von 23.659,86 Euro jahrlich eingespart werden. Es zeigt sich in der vorliegenden Analyse eine hervorragende Aufwand-Nutzen-Bilanz dieses Modells, das sich an der Universitatsmedizin Gottingen in mehreren chirurgischen Kliniken inzwischen erfolgreich etabliert hat. Es kommt neben der praxisorientierten Vermittlung von chirurgischen Lehrinhalten zu einer erfolgreichen Nachwuchsforderung sowie Ressourceneinsparung der arztlichen Rufdienste.

The femoral posterior condylar offset (PCO) has been viewed with increased significance for knee joint movement patterns and has been discussed for its possible implication for femoral component rotation in total knee arthroplasty (TKA). However, a great inter-individual variability in medial and lateral PCO size has also been demonstrated. Though the medial and lateral PCO seem closely related to the functional flexion axis (fFA), determined by the radius curvature of the medial and lateral femoral condyle, the relationship of both parameters considering their impact on the accuracy of established reference axes for determining femoral component rotation in TKA remains unknown. The objective of this paper was, therefore, to compare the individual fFA with the anatomical and surgical transepicondylar axis (aTEA; sTEA) and with the posterior condylar axis (PCA) considering the medial and lateral PCO size. It was hypothesized that the disparity of the PCO influences the accuracy of the sTEA, aTEA, and PCA for determination of femoral component rotation in TKA. MRI investigations of 56 consecutive non-arthritic knee joints (male/female 28/28; mean age 22.8 years; range 16-59 years) were used for this study. Coronal, sagittal and transverse MRI images were used to measure the medial and lateral PCO and to determine the fFA, aTEA, sTEA, and PCA for each subject as described previously. A paired two-tailed t-test was used to test for differences between the medial and lateral PCO sizes. Deviation of the aTEA, sTEA and PCA from the fFA were analyzed with a one-sample t-test. Correlation analysis (Pearson r) was used to determine the relationship between the PCO ratio (medial-to-lateral PCO) and the deviation of the aTEA, sTEA and PCA from the fFA in each subject. The level of significance was set at 0.05. The mean medial PCO was 34.0 mm (90%CI 28.72-30.55 mm; range 26.3 to 44.7 mm) and the lateral PCO averaged 29.64 mm (90%CI 30.3-31.4 mm; range 14.3 to 39.1 mm) (p Differences of the medial and lateral PCO size are a common finding. The PCA had the best match with the fFA, regardless of medial-to-lateral PCO disparity. Only the sTEA was influenced to a small extent by variation of the PCO-ratio.

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is an established operative procedure for patients with recurrent episodes of lateral patellar instability. However, recent articles have reported remarkable complication rates, with nonanatomic femoral tunnel positioning in up to 64% of patients. Purpose: To evaluate the sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view using established radiographic landmarks. Study Design: Controlled laboratory study. Methods: Six human cadaveric femora were used for this study. A 6-mm radiopaque eyelet was used to mark the native femoral insertion of the MPFL according to previously described radiographic landmarks. Radiographic landmarks were also applied with the femur positioned in 2.5° and 5° of internal and external rotation, respectively, and with the femur in 2.5° and 5° of hip abduction and adduction, respectively. The distance between the center of the 6-mm eyelet to the center of the native femoral MPFL insertion, as established in the true-lateral view, was measured and determined as the degree of shift in each position. Results: Hip adduction, abduction, and internal and external rotations of 2.5° resulted in a shift from the native femoral MPFL insertion point to a more distal (adduction), proximal (abduction), anterior (internal rotation), and posterior location (external rotation) of 2.7 ± 0.7, 2.0 ± 0.7, 2.7 ± 1.1, and 3.0 ± 1.3 mm, respectively (all P < .05). Malpositioning increased to a distance of 5.0 ± 0.7 mm distally, 3.6 ± 1.0 mm proximally, 5.2 ± 0.8 mm anteriorly, and 6.2 ± 0.6 mm posteriorly to the native insertion point when the attachment was marked with 5° of divergence from the true-lateral view (all P < .05). Conclusion: The results of this study indicate the high sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view. Clinical Relevance: The study highlights the importance of an exact lateral view when fluoroscopic guidance is used for femoral tunnel positioning in the daily practice of MPFL reconstruction, and a possible explanation for the high incidence of nonanatomic tunnel placement is suggested.

Purpose The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint has gained increased significance. However, no quantitative data are available regarding the inclination of the medial and lateral tibial slope in patients with patellar instability. It was therefore the purpose of this study to evaluate tibial slope characteristics in patients with patellar dislocations and to assess the biomechanical effect of medial-to-lateral tibial slope asymmetry on lateral patellar instability. Methods Medial and lateral tibial slope was measured on knee magnetic resonance images in 107 patients and in 83 controls. The medial-to-lateral tibial slope asymmetry was assessed as the intra-individual difference between the medial and lateral tibial plateau inclination considering severity of trochlear dysplasia. The effect of tibial slope asymmetry on femoral rotation was calculated by means of radian measure. Results Severity of trochlear dysplasia was significantly associated with an asymmetric inclination of the tibial plateau. Whereas the medial tibial slope showed identical values between controls and study patients (n.s.), lateral tibial plateau inclination becomes flatter with increasing severity of trochlear dysplasia (p

Aim The diagnosis and treatment of patellar dislocation is very complex. The aim of this study is to give an overview of the biomechanics of the patellofemoral joint and to point out the latest developments in diagnosis and treatment of patellar dislocation. Method The authors electronically searched Medline, Cochrane and Embase for studies on the biomechanics of the patellofemoral joint and for conservative and surgical treatments after patellar dislocation. We extracted baseline demographics, biomechanical, conservation and surgical details. Results Understanding the biomechanics of the patellofemoral joint is necessary to understand the pathology of patellar dislocation. The patellofemoral joint consists of a complex system of static, active and passive stabilising factors. Patellar instability can result from osseous and soft-tissue abnormalities, such as trochlear dysplasia, patella alta, a high tibial tuberosity trochlear groove (TTTG) distance, weaknesses of the vastus medialis obliquus or a lesion of the medial retinaculum. Recent studies have focused on the medial patellofemoral ligament (MPFL) and have shown that the MPFL is the most significant passive stabiliser of the patella. Following patellar dislocation, an MRI should be standard practice to detect an MPFL rupture, osteochondral lesions or other risk factors for redislocation. An acute first-time patellar dislocation without osteochondral lesions and without severe risk factors for a redislocation should follow a conservative treatment plan. If surgical treatment is required, the best postoperative results occur when the MPFL is reconstructed, leading to a redislocation rate of 5%, this includes cases that have a dysplastic trochlea. Duplication of the medial retinaculum show very inconsistent results in the literature, possibly due to the fact that the essential pathomorphology of patellar dislocation is not addressed. Addressing the exact location of the rupture of the MPFL with a suture is possibly more convenient, especially after first-time dislocation with associated risk factors for a redislocation. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Indications for lateral release include persistent patellar instability or pain reduction in an older arthritic subject. For correcting a patellofemoral malalignment, the TTTG distance should be measured and a medial transposition of the anterior tibial tubercle hinged on a distal periosteal attachment should be considered. Cartilage lesions on the medial facet of the patella are a contra-indication for medial tubercle transposition. For cartilage lesions of the lateral facet, antero-medialization of the tibial tubercle can be successful. A tubercle osteotomy can be efficiently combined with MPFL reconstruction. We believe that patients with open epiphyseal plates should be treated with duplication of the medial retinaculum. In the presence of patellar maltracking, an additional subperiostal soft tissue release with medialisation of the distal part of the patellar tendon can be performed. Conclusion It seems that the predominating factors for patellar dislocation are heterogenic morphology in combination with individual predisposition. Non-surgical treatment is typically recommended for primary patellar dislocation without any osteochondral lesions and in the absence of significant risk factors for redislocation. If surgical treatment is deemed necessary, addressing the essential pathomorphology has become the primary focus.

AIM Refixation of osteochondral fractures with resorbable implants is a common surgical treatment. There are almost no studies that prove good clinical outcomes. Hence, the aim of the study was to evaluate the mid-term results after refixation of osteochondral fractures. METHODS The results of 12 patients were recorded 6.5 (±1) years after refixation of osteochondral fractures measuring 3.4 cm (2) (±2.5) of the knee (8 ×) or the ankle joint (4 ×) with resorbable inplants. Clinical scores and a modified MRI score based on that of Henderson et al. were used. RESULTS The clinical scores showed good to excellent results after 6.5 (±1) years (VAS pain: 1.9 [±2.4], Tegner: 5.0 [±1.7], Lysholm: 84.8 [±14.3], McDermott: 91.3 [±7.9], Knee Society: 189.4 [±12.1]). MRI showed with one exception good integration of the fractures. In 3 cases subchondral cysts could be found. In 7 cases changes in the chondral outline occurred. The effect of this was a modified Henderson score of 12.6 (±3.7). The MRI results did not correlate with the clinical outcome. CONCLUSION Because of its good clinical results the refixation with resorbable implants can be recommended to treat osteochondral fractures.

Background A trend toward young women being at greatest risk for primary and recurrent dislocation of the patella is evident in the current literature. However, a causative factor is missing, and differences in the anatomical risk factors between men and women are less defined. Purpose To identify differences between the sexes in the anatomy of lateral patellar instability. Study Design Case control study; Level of evidence, 3. Methods Knee magnetic resonance images were collected from 100 patients treated for lateral patellar instability. Images were obtained from 157 patients without patellar instability who served as controls. Using 2-way analyses of variance, the influence of patellar dislocation, gender, and their interaction were analyzed with regard to sulcus angle, trochlear depth, trochlear asymmetry, patellar height, and the tibial tubercle—trochlear groove (TT-TG) distance. Mechanisms of injury of first-time dislocations were divided into high-risk, low-risk, and no-risk pivoting activities and direct hits. Results For all response variables, a significant effect was observed for the incidence of patellar dislocation (all P < .01). In addition, sulcus angle, trochlear asymmetry, and trochlear depth depended significantly on gender (all P < .01) but patellar height did not (P = .13). A significant interaction between patellar dislocation and gender was observed for the TT-TG distance (P = .02). The mean difference in TT-TG distance between study and control groups was 4.1 mm for women (P < .01) and 1.6 mm for men (P = .05). Low-risk and no-risk pivoting injuries were most common in women, whereas first-time dislocations in men occurred mostly during high-risk pivoting activities (P < .01). Conclusion The data from this study indicate that trochlear dysplasia and the TT-TG distance is more prominent in women who dislocate the patella. Both factors might contribute to an increased risk of lateral patellar instability in the female patient as illustrated by the fact that dislocations occurred most often during low-risk or no-risk pivoting activities in women.

The selection of a surgical approach for the treatment of tibia plateau fractures is an important decision. Approximately 7% of all tibia plateau fractures affect the posterolateral corner. Displaced posterolateral tibia plateau fractures require anatomic articular reduction and buttress plate fixation on the posterior aspect. These aims are difficult to reach through a lateral or anterolateral approach. The standard posterolateral approach with fibula osteotomy and release of the posterolateral corner is a traumatic procedure, which includes the risk of fragment denudation. Isolated posterior approaches do not allow sufficient visual control of fracture reduction, especially if the fracture is complex. Therefore, the aim of this work was to present a surgical approach for posterolateral tibial plateau fractures that both protects the soft tissue and allows for good visual control of fracture reduction. The approach involves a lateral arthrotomy for visualizing the joint surface and a posterolateral approach for the fracture reduction and plate fixation, which are both achieved through one posterolateral skin incision. Using this approach, we achieved reduction of the articular surface and stable fixation in six of seven patients at the final follow-up visit. No complications and no loss of reduction were observed. Additionally, the new posterolateral approach permits direct visual exposure and facilitates the application of a buttress plate. Our approach does not require fibular osteotomy, and fragments of the posterolateral corner do not have to be detached from the soft tissue network.

Purpose The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. Methods Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity–trochlear groove (TT-TG) distance. Results Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. Conclusions The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. Level of Evidence Level IV, diagnostic case-control study.

Dauerhafte Wiederherstellung der Gelenkflache durch Transplantation autologer osteochondraler Zylinder. Entnahme der Zylinder aus der dorsalen medialen Femurkondyle uber einen minimalinvasiven Zugang. Dritt- und viertgradige Knorpelschaden (nach ICRS [International Cartilage Repair Society]), osteochondrale Lasionen oder Osteochondrosis dissecans. Zweit- oder hohergradige Knorpelschaden an der dorsalen medialen Femurkondyle, Infekt, Achsabweichungen von mehr als 5° in der Frontalebene, fortgeschrittene Gonarthrose. Entnahme der Zylinder zunachst an der Empfangerstelle, Festlegen von Anzahl und Durchmesser der zu entnehmenden Zylinder. Anschliesend Bauchlage, Hautschnitt uber der dorsalen medialen Femurkondyle. Nach Durchtrennung der oberflachlichen Faszie Weghalten der Semitendinosussehne und des medialen Gastroknemiuskopfs nach lateral, Arthrotomie, Einsetzen von zwei Hohmann- Haken medial und lateral der Femurkondyle und Entnahme der Spenderzylinder mit einer Hohlstanze oder -frase. Vorteile des beschriebenen Zugangs: Weichteilschonend, einfache Operationstechnik, zusatzliche Entnahmemoglichkeit fur osteochondrale Zylinder neben Trochlea femoris und interkondylarer Notch, geringe Entnahmemorbiditat. Teilbelastung von 10–20 kg fur 4–6 Wochen. Limitierung der Kniebeugung auf 90° fur 6 Wochen. Von 01/2006 bis 04/2007 wurde bei 16 Patienten die dorsale mediale Femurkondyle als Spenderregion fur die Transplantation autologer osteochondraler Zylinder verwendet. Sowohl praoperativ als auch zur Nachuntersuchung wurde der Knee Society Score (KSS), der Western Ontario and McMaster Universities (WOMAC) Score, der Tegner-Score sowie die visuelle Analogskala (VAS) Schmerz erhoben. Alle Patienten konnten nach durchschnittlich 13,9 (±4,3) Monaten nachuntersucht werden. Die durchschnittliche Defektflache betrug 4,6 (±2,2) cm2. Die verwendeten Scores zeigten beim Vergleich der praoperativen Werte mit denen bei der Nachuntersuchung deutliche Besserungen: KSS 123,1 (±41,5) versus 171,3 (±16,9) Punkte (p < 0,05), Tegner-Score 2,8 (±0,9) versus 3,4 (±0,6) Punkte (p < 0,05) und WOMAC-Score 73,3 (±50,2) versus 26,1 (±17,6) Punkte (p < 0,05). Die VAS Schmerz reduzierte sich von 5,3 (±2,7) auf 2,4 (±1,8) Punkte (p < 0,05). Ein Patient mit einem Defekt von 8 cm2 an der medialen Kondyle (Morbus Ahlback) klagte bei tiefer Kniebeuge 1 Jahr postoperativ noch uber Beschwerden. Die dorsale mediale Femurkondyle ist als Donorregion fur die Transplantation autologer osteochondraler Zylinder geeignet. Insbesondere hat sich der minimalinvasive Zugang als sicher und komplikationsarm bewahrt.

Offene Reposition und Osteosynthese posterolateraler Tibiakopffrakturen. Tibiakopffrakturen, die den posterolateralen Quadranten betreffen. Kritische Weichteilverhaltnisse. Tibiakopffrakturen, die sich auserhalb des posterolateralen Quadranten befinden. Seitenlagerung, gerader posterolateraler Hautschnitt uber dem Fibulakopfchen, Darstellung des Nervus peroneus, laterale Arthrotomie und Darstellung der lateralen Gelenkflache, Praparation in die Kniekehle zwischen lateralem Musculus gastrocnemius und Musculus soleus. Identifikation des Gefas-Nerven-Bundels (Arteria und Vena popliteae, Nervus tibialis). Stumpfe Praparation zwischen Musculus popliteus und Musculus soleus. Scharfes Ablosen des Musculus soleus von Tibia und Fibula bis knapp oberhalb des Eintritts des Nervus peroneus in die Peronealmuskulatur. Erhalt der Innervation des Musculus soleus. Darstellung des posterolateralen Tibiakopfes. Die dorsale Gelenkkapsel sowie die Popliteusecke werden geschont. Optische Kontrolle der Frakturreposition uber die laterale Arthrotomie. Reposition der Fraktur von dorsal, Anmodellieren und Fixieren einer zu einer L-Platte umfunktionierten 3,5-mm-Radius-T-Platte ebenfalls von dorsal. Teilbelastung von 10 kg fur 6–8 Wochen, je nach radiologischer Heilung. Limitierung der Kniebeugung auf 90° fur 6 Wochen. In 2 Jahren wurden sieben Patienten uber den modifizierten posterolateralen Zugang operiert. Alle sieben Patienten konnten nach 12–24 Monaten nachuntersucht werden. Sechs Patienten waren beschwerdefrei. Radiologisch zeigte sich sechsmal eine stufenlose Wiederherstellung der Gelenkflache, einmal fand sich bei einer mehrfragmentaren posterolateralen Luxationsfraktur ein verbleibender Defekt mit geringer Stufenbildung. Komplikationen durch den Zugang wurden nicht beobachtet.

The purpose of this study was to analyze the impact of monopolar radiofrequency energy treatment on subchondral bone viability. The femoral grooves of six chinchilla bastard rabbits were exposed bilaterally to monopolar radiofrequency energy for 2, 4 and 8 s, creating a total of 36 defects. An intravital fluorescence bone-labeling technique characterized the process of subchondral bone mineralization within the 3 months following exposure to radiofrequency energy and was analyzed by widefield epifluorescence optical sectioning microscopy using an ApoTome. After 2 s of radiofrequency energy exposure, regular fluorescence staining of the subchondral bone was evident in all samples when compared to untreated areas. The depth of osteonecrosis after 4 and 8 s of radiofrequency energy treatment averaged 126 and 942 µm at 22 days (P

Rehabilitation and patient satisfaction following a modified anterolateral approach for implantation of a total hip replacement (THR) were reviewed following 72 consecutive cases. The Harris Hip and merle d'Aubigné Scores were recorded at 6 and 12 weeks postoperatively. The patient's satisfaction with regard to the surgical result and the need for analgesia for mobilization were recorded. Rehabilitation was assessed by postoperative crutch use. Significant improvements of the Harris Hip and merle d'Aubigné scores were demonstrated. All patients thought their surgical outcome was good or better. 2 patients needed pain medicine on an irregular basis and 4 patients used crutches at 12 weeks. This study demonstrates patient satisfaction and satisfactory rehabilitation following a modified anterolateral approach for minimally-invasive implantation of THR.

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro™ interference screw (Mitek, Norderstedt, Germany). The Milagro™ interference screw is made of 30% ß-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro™ screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (±7.9%) and 82.6% (±17.2%, P < 0.05), respectively. The femoral screws showed volume losses of 2.5% (±2.1%), 31.3% (±21.6%) and 92.02% (±6.3%, P < 0.05), respectively. The femoral tunnel enlargement was 47.4% (±43.8%) of the original bone tunnel volume after 12 months, and the mean tunnel volume of the tibial tunnel was −9.5% (±58.1%) compared to the original tunnel. Bone ingrowth was observed in all the patients. In conclusion, the resorption behaviour of the Milagro™ screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro™ screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months. peerReviewed

BACKGROUND: A review of recent reports concerning the functional outcome after treatment for Cyclops syndrome can produce contradictory results. Therefore, the purpose of this study was to evaluate the functional outcome of our patients treated for Cyclops syndrome after anterior cruciate ligament reconstruction. METHODS: Between 1998 and 2006 ten patients were followed for the occurrence of a Cyclops syndrome. The Lysholm score, Marshall score and Tegner activity score was used for clinical evaluation at final follow up; in addition, a subjective assessment of knee function and knee pain on a visual analogue scale was registered. Knee stability was measured using the KT-1000 arthrometer. Results were compared with a control group of 24 uneventful ACL reconstructions. RESULTS: Revision arthroscopy for symptomatic extension block was performed after a mean of 6.8 months. After a mean follow-up of 23 months after second surgery all patients’ regained full range of motion. The mean Lysholm score and Marshall score was 85 and 41 after Cyclops syndrome and 92 and 46 for the control group. After Cyclops syndrome patients experienced a significantly increased ACL transplant laxity but no significant difference was found concerning patient’s subjective rating of knee function and knee pain. CONCLUSION: Although patients subjective rating of knee function and knee pain was nearly identical in both groups objective knee scores disclosed impaired knee function in our patients treated for Cyclops syndrome.

The aim of the study was to evaluate the 5- to 10-year results (mean, 6.2 years) of a modular uncemented revision stem (Profemur-R). From a total series of 184 consecutive stem revisions, the first 73 were evaluated. The implant was fixed without bone grafting in all cases. The average Harris hip score increased from 40 to 75. A complete remodeling of bone defects could be documented radiographically in 70% of the cases and a partial restoration in 30%. Progressive subsidence appeared in 2 stems. Three rerevisions were required, including 1 septic case. The survival rate with aseptic loosening as the end point was 96% over an average of 10 years. The revision prosthesis examined in this study can be considered a viable and useful option to reconstruct femoral defects in revision hip arthroplasty.

Introduction: To reduce complications, a minimally invasive technique for the treatment of dislocated intraarticular fractures of the calcaneus was used. Therefore previously described closed reduction and internal fixation techniques were combined and modified. Materials and methods: Sixty-seven out of 92 calcaneal fractures could be retrospectively evaluated with an average follow-up time of 5.7 years (minimum 210 years follow-up). For radiographic evaluation, plain radiographs and CT scans were obtained. The Zwipp score was used for clinical evaluation. Sanders type II, III and IV fractures were diagnosed. Results: Length of surgery averaged 61 min (range 20175 min). The incidence of subtalar arthritis was correlated to the severity of fracture. Böhler’s angle was restored in 70.1% (47 of 67) of the cases. On the last follow-up evaluation the average Zwipp score was 130 points (range 48186 points). The majority (77.7%) of patients were content with their treatment result. The rate of significant complications was 6.5%. Discussion: Compared to open techniques the presented minimally invasive technique showed comparable results with a low rate of serious complications and is a viable alternative for the treatment of intraarticular, dislocated calcaneal fractures. peerReviewed

Introduction:Considering patients after hip revision arthroplasty postoperative quality controls allows an evaluation of the individual implant situation as well as the achieved postoperative quality of life. With regard to a possible loss of data reliable statements about the used implant system with special consideration to the implant survival rate could not be received. In this connection standardized self-assessment questionnaires like the Nottingham Health Profile (NHP) are in the centre of interest. The main focus of this study was to demonstrate a correlation between the Nottingham Health Profile and the Merle d’Aubigne (MDA) Score. Patients and methods: Fifty-one patients after femoral stem revision were re-examined. All patients received a written appointment for an ambulatory re-examination together with the NHP 4 weeks before. The clinical evaluation was carried out by using the MDA Score. Correlations between the NHP and the MDA were calculated. Results: Overall the data of 39 patients could be evaluated completely. Three patients (5.9%) did not appear to the ambulatory re-examination, four patients (7.8%) deceased in the meantime. With further five patients (9.8%) the NHP questionnaire could not be rated due to an incorrect treatment. The mean follow-up after revision was 5.8 years. Correlations between the category ‘Pain’ NHP/MDA as well as to the combination of the NHP-categories ‘Pain’+‘Physical Mobility’ and the total MDA-Score could be demonstrated. Conclusion: Out of our personal experiences the use of the NHP makes an individual follow-up evaluation after revision hip arthroplasty possible. Patient-referred changes can lead to direct re-examinations. Correlation coherences between the NHP and the MDA could be demonstrated equivalent to already published results. In what way a survival rate analysis of an implant by using the NHP is possible could not be answered clearly. It has to be included that wrong answered questionnaires lead to an additional drop-out rate beneath the lost to follow-up rate.

In this study, we compared the accuracy of radiography, computed tomography, and magnetic resonance imaging in assessing periacetabular osteolytic lesions. Using a previously published cadaver model, we created 87 lesions in pelves implanted with total hip replacement components. The sensitivity for detecting lesions was 51.7% for radiography, 74.7% for computed tomography, and 95.4% for magnetic resonance imaging. For all three techniques, sensitivity increased as lesion size increased. Magnetic resonance imaging emerged as the most effective tool for detecting small periacetabular osteolytic lesions (or = 3 cm). For lesions larger than 3 cm, which are of more concern clinically, computed tomography and magnetic resonance imaging were effective in identifying lesions with detection rates greater than 80%. For radiography and computed tomography, lesion detection was dependent on lesion location, whereas magnetic resonance imaging had consistently good sensitivity in all lesion locations. Although the mean volumetric errors for computed tomography and magnetic resonance imaging (0.3 cm and 0.8 cm) were small compared with mean lesion volume (6.1 cm), computed tomography was more accurate than magnetic resonance imaging at measuring lesion volume, with a lower mean absolute error. This study verifies the problems associated with radiographic detection of osteolysis while showing the effectiveness of computed tomography and magnetic resonance imaging in determining the presence of lesions and assessing their three-dimensional volume.

Medial-wall perforation secondary to pelvic osteolysis impacts planning of acetabular revision surgery and may result in pelvic fracture. We compared commonly used radiographic signs for detecting medial-wall perforation (ballooning or discontinuity of Kohler's line or the iliopubic line) to findings from computed tomography (CT) in 27 cementless total hip arthroplasty patients with pelvic osteolysis. Used alone, none of the radiographic signs examined were reliable for detecting medial-wall perforation. When assessed together, however, the development of a discontinuity of Kohler's line, the iliopubic line, or both on anteroposterior pelvic radiographs was a reliable indicator for the presence of medial-wall perforation. Thus, the authors recommend a CT scan to evaluate the integrity of the medial wall when a discontinuity of Kohler's line or the iliopubic line has occurred and a revision surgery is planned.

Polyethylene wear and pelvic osteolysis are the most common late complications associated with stable cementless total hip implants. This manuscript describes the diagnostic strategies and treatment algorithm used at the senior author's (C.A.E) institution for patients with wear and pelvic osteolysis. This evolving management strategy is based on our experiences and ongoing research. We discuss patient selection, the evaluation of acetabular liner wear, the diagnosis of pelvic osteolysis, the timing of revision, and treatment strategies. According to this algorithm, we revise asymptomatic hips with pending or complete wear-through of the acetabular liner. We also recommend revision for most symptomatic patients with pelvic osteolysis and for patients with large pelvic osteolytic bone defects or a documented increase in osteolytic lesion size in an area of the cementless acetabular component in which a load transfer between the implant and the surrounding bone is likely to occur.

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r(2) = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r(2) = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.

In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young’s modulus at the suture–tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason–Allen stitch. Twenty-four infraspinatus muscles with tendons were dissected from porcine shoulders (twelve Goettingen minipigs). The preparations were randomly allocated to three groups of eight samples. Load-to-failure testing of the single-loop knot stitch, the double-loop knot stitch and the mMAS were performed using a Zwick 1446 universal testing machine (Zwick-Roell AG, Ulm, Germany). The highest ultimate load to failure for the three techniques occurred with the double-loop knot stitch with a median value of 382.2 N (range 291.8–454.2 N). These values were significantly higher than those of the single-loop knot stitch, which had a median value of 259.5 N (range 139.6–366.3 N) and the modified Mason–Allen stitch, which had a median value of 309.3 N (range 84.55–382.9 N). The values of the single-loop knot stitch and the modified Mason–Allen stitch did not differ significantly. Regarding the Young’s modulus, no significant differences were found between the double-loop knot stitch with a median value of 496.02 N/mm² (range 400.4–572.6 N/mm²) and the modified Mason–Allen stitch with 498.5 N/mm² (range 375.5–749.2 N/mm²) with respect to the stiffness of the suture–tendon complex. The median value for the Young’s modulus of the single-loop knot stitch of 392.1 N/mm² (range 285.7–510.6 N/mm²) was significantly lower than those of the double-loop knot stitch and modified Mason–Allen stitch. This in vitro animal study demonstrated that both the single-loop knot stitch and the double-loop knot stitch have excellent ultimate load-to-failure properties when used for rotator cuff repair. The introduced single-loop knot stitch and double-loop knot stitch offer an alternative to other common used stitch techniques in rotator cuff repair.

The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

The purpose of this study was to identify the risk factors for recurrent lateral patellar dislocations and to incorporate those factors into a patellar instability severity score.Sixty-one patients [male/female 35/26; median age 19 years (range 9-51 years)] formed the study group for this investigation. Within the study group, 40 patients experienced a patellar redislocation within 24 months after the primary dislocation, whereas 21 patients, who were assessed after a median follow-up of 37 months (range 24-60 months), had not experienced a subsequent episode of lateral patellar instability. In all patients, age at the time of the primary dislocation, gender, the affected body side, body mass index, bilateral instability, physical activity according to Baecke's questionnaire, the grade of trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt were assessed. The odds ratio (OR) of each factor with regard to the patellar redislocation was calculated using contingency tables. Based on these data, a "patellar instability severity score" was calculated.The patellar instability severity score has six factors: age, bilateral instability, the severity of trochlear dysplasia, patella alta, TT-TG distance, and patellar tilt; the total possible score is seven. Reapplying this score to the study population revealed a median score of 4 points (range 2-7) for those patients with an early episode of patellar redislocation and a median score of 3 points (range 1-6) for those without a redislocation (p=0.0004). The OR for recurrent dislocations was 4.88 (95% CI 1.57-15.17) for the patients who scored 4 or more points when compared with the patients who scored 3 or fewer points (p=0.0064).Based on the individual patient data, the patellar instability severity score allows an initial risk assessment for experiencing a recurrent patellar dislocation and might help differentiate between responders and non-responders to conservative treatment after primary lateral patellar instability.Case-control study, Level III.

Purpose The aim of this study was to evaluate the clinical outcome and differences in anterior–posterior laxity of ACL reconstruction using a bioabsorbable interference screw for femoral graft fixation when compared to femoral bioabsorbable cross pin fixation. Methods Clinical outcome was evaluated among 59 patients 1 year after arthroscopic ACL reconstruction with hamstrings graft in a prospective, non-randomised study. In 31 cases, femoral fixation of the graft was performed using a bioabsorbable interference screw. In 28 cases, two bioabsorbable cross pins were used for femoral fixation. Patients were evaluated using Tegner, Lysholm and Marshall scores, the visual analogue scale for pain and KT-1000 arthrometer measurement. Results No significant difference (P ≥ 0.05) was observed at follow-up for the knee scores. The average Tegner score was 5.83 points (±2.00) for the interference screw fixation and 5.83 points (±1.24) for the cross pin fixation; the average Lysholm score was 93.58 (±5.79) to 92.72 (±6.34) points; and the average Marshall score 46.72 (±2.4) to 47.30 (±2.35) points. No significant difference was found for the visual analogue scale for pain. KT-1000 arthrometer measurement revealed a significant (P

Firstly, the way of implementing approximatively the initial rollback of the natural tibiofemoral joint (TFJ) in a total knee replacement (AEQUOS G1 TKR) is discussed. By configuration of the curvatures of the medial and lateral articulating surfaces a cam gear mechanism with positive drive can be installed, which works under force closure of the femoral and tibial surfaces. Briefly the geometric design features in flexion/extension are described and construction-conditioned kinematical and functional properties that arise are discussed. Due to a positive drive of the cam gear under the force closure during the stance phase of gait the articulating surfaces predominantly roll. As a result of rolling, a sliding friction is avoided, thus the resistance to motion is reduced during the stance phase. Secondly, in vivo fluoroscopic measurements of the patella tendon angle during flexion/extension are presented. The patella tendon angle/ knee flexion angle characteristic and the kinematic profile in trend were similar to those observed in the native knee during gait (0°-60°).

Purpose The purpose of this study was to investigate whether the femoral part of the medial patellofemoral ligament (MPFL) and its injury can be accurately assessed by standard knee arthroscopy in first-time patellar dislocations or whether preoperative MRI is required to determine injury location in patients where primary MPFL repair is attempted. Methods Twelve patients with acute first-time dislocations and MRI-based injury of the femoral MPFL and ten patients with recurrent patellar dislocations underwent knee arthroscopy with the use of a 30-degree optic and standard antero-medial and antero-lateral portals. The femoral origin was marked with a cannula under lateral fluoroscopy. Arthroscopic findings of the location of the native femoral MPFL and its injury were compared to the results of MRI and mini-open exploration. Results In acute cases, the average time from primary patellar dislocation to MRI evaluation was 3 days (1–9 days), and the average time from MRI to surgery was 8 days (3–20 days). The native femoral origin of the MPFL was not visible in any of the chronic cases during arthroscopy. In addition, in all acute cases, arthroscopy failed to directly visualize injury of the femoral MPFL (0 of 12), but mini-open exploration confirmed injury in 11 of 12 patients. This means that arthroscopy was less accurate than MRI for the diagnosis of femoral MPFL injury (P

A novel class of total knee replacement (AEQUOS G1) is introduced which features a unique design of the articular surfaces. Based on the anatomy of the human knee and differing from all other prostheses, the lateral tibial "plateau" is convexly curved and the lateral femoral condyle is posteriorly shifted in relation to the medial femoral condyle. Under compressive forces the configuration of the articular surfaces of human knees constrains the relative motion of femur and tibia in flexion/extension. This constrained motion is equivalent to that of a four-bar linkage, the virtual 4 pivots of which are given by the centres of curvature of the articulating surfaces. The dimensions of the four-bar linkage were optimized to the effect that constrained motion of the total knee replacement (TKR) follows the flexional motion of the human knee in close approximation, particularly during gait. In pilot studies lateral X-ray pictures have demonstrated that AEQUOS G1 can feature the natural rollback in vivo. Rollback relieves the load of the patello-femoral joint and minimizes retropatellar pressure. This mechanism should reduce the prevalence of anterior knee pain. The articulating surfaces roll predominantly in the stance phase. Consequently sliding friction is replaced by the lesser rolling friction under load. Producing rollback should minimize material wear due to friction and maximize the lifetime of the prosthesis. To definitely confirm these theses one has to wait for the long term results.

Femoral malrotation in total knee arthroplasty is correlated to an increased number of revisions. Anatomic landmarks such as Whiteside line, posterior condyle axis and transepicondylar axis are used for determining femoral component rotation. The femoral rotation achieved with the anatomical landmarks is compared to the femoral rotation achieved by a navigated ligament tension-based tibia-first technique. Ninety-three consecutive patients with gonarthritis were prospectively enrolled. Intraoperatively the anatomical landmarks for femoral rotation and the achieved femoral rotation using a navigated tension-based tibia-first technique were determined and stored for further comparison. A pre- and postoperative functional diagram displaying the extension and flexion and varus or valgus positions was also part of the evaluation. Using anatomical landmarks the rotational errors ranged from 12.2° of internal rotation to 15.5° of external rotation from parallel to the tibial resection surface at 90° flexion. A statistical significant improved femoral rotation was achieved using the ligament tension-based method with a rotational error ranged from 3.0° of internal rotation to 2.4° of external rotation. The functional analyses demonstrated statistical significant lower varus/valgus deviations within the flexion range and an improved maximum varus deviation at 90° flexion using the ligament tension-based method. Compared to the anatomical landmarks a balanced, almost parallel flexion gap was achieved using a navigation technique taking the ligament tension of the knee joint into account. As a result the improved femoral rotation was demonstrated by the functional evaluation. Unilateral overloading of the polyethylene inlay and unilateral instability can thus be avoided.

An uncommon case of myoclonus-induced bilateral central acetabular fracture-dislocation is presented. Although different fracture types due to forceful muscular contractions have been reported, this is an exceedingly uncommon injury pattern. Bilateral total hip arthroplasty, in combination with a reinforcement ring and autologous bone grafting, was performed after open reduction and internal fixation.

Minimally invasive hip approaches decrease soft tissue damage but reduce the view of the operating field. The combination of minimally invasive approaches with navigation techniques can resolve this conflict. A modified anterolateral approach was used for minimally invasive implantation of hip endoprostheses, in combination with a navigation technique. A newly developed femoral clamp was used in the study, which allowed a secure fixation of the navigation reference frame without compromising the visibility of the small incision. The results included short skin incisions and hip joint muscle reservation, with only a moderate increase in operating times.

Although navigation achieves better alignment results in total knee arthroplasty (TKA), it is generally assumed that navigation also needs more time and effort than conventional surgeries. After optimizing the treatment procedure of navigated TKA, the operation times needed for navigated surgeries were documented and compared with the average time of conventional surgeries, registered before the introduction of the navigation system. Sixty consecutive patients for uncemented TKAs were included in the navigated series. Results show an average of 49 minutes for the navigated surgeries, which is less than the average of the manual surgeries. For all patients, alignment was within 3° varus/valgus postoperatively, and the mean Knee Society Score improved from 25 points preoperatively to 83 points 6 weeks postoperatively.

Background: Computed tomography recently has been proposed as an accurate method for diagnosing periacetabular osteolytic lesions. Several investigators have attempted to validate the accuracy of this technique, but they employed cadaveric and animal models, which cannot replicate the adaptive changes that occur over time in vivo. This study was performed to determine the accuracy of computed tomography in identifying and measuring periacetabular osteolytic lesions in hemipelves retrieved at autopsies of individuals with a previously well-functioning total hip prosthesis. Methods: We evaluated nine hemipelves, retrieved at autopsy, that contained a cementless porous-coated acetabular component. The fresh specimens were examined with conventional radiographs and computed tomography and then were embedded and sectioned into 1.5-mm slices for evaluation with slab radiographs. Anteroposterior and iliac oblique plain radiographs as well as axial, coronal, and sagittal computed tomography scans were reviewed to determine the presence and location of any periacetabular osteolytic lesions. These results were then compared with those identified on the slab radiographs. Lesion volume was calculated from computed tomography scans with use of post-processing software. Results: A total of twenty-three periacetabular osteolytic lesions were identified on the slab radiographs of the nine hemipelves. The plain radiographs identified twelve (52%) of the twenty-three lesions, and the computed tomography scans identified twenty (87%) of the twenty-three lesions. Three medial wall perforations were identified on the computed tomography scans but were not detected on the plain radiographs. Computed tomography was accurate in measuring the volume of the osteolytic lesions (r2 = 0.997) but tended to overestimate the volumes measured on the slab radiographs. Periacetabular osteolytic lesions appeared on the computed tomography scans and slab radiographs as areas devoid of trabecular bone that were delineated by a sclerotic border and communicated with the joint space. Conclusions: In this autopsy model, computed tomography was an accurate method for detecting the location and measuring the volume of periacetabular osteolytic lesions.

Periprosthetic osteolysis is a well recognized complication of total hip arthroplasty that leads to implant failure. The ability to accurately assess and visualize the position and volume of periacetabular bone defects is paramount for clinical observation and medical treatment, as well as pre-operative planning of revision surgery. We have developed a modified magnetic resonance imaging (MRI) protocol that is useful in detection and quantification of periacetabular bone loss. The purpose of this study is to compare MRI to plain film analysis in the assessment of periacetabular bone loss using a cadaver model. MRI was 95% sensitive in the detection of lesions. Specificity was 98%, and accuracy was 96%. Lesion detection was not statistically dependent on lesion location (p=0.27). The mean absolute error in determining lesion size was 0.8+/-2.2 cm3. There was a correlation between increasing lesion size and lesion detection (p=0.02, logistic regression). The largest lesion that was missed by MRI analysis measured 2.8 cm3, and all lesions 3.0 cm3 were correctly identified, with a relative error volume measurement of 12.4+/-25.3%. This correlated to an absolute error of 1.4+/-2.4 cm3. Using conventional radiographic analysis, the overall sensitivity of lesion detection was 52%, and the specificity was 96%. Using plain film analysis, identification of true lesions depended on the location with 83% of ilial lesions, 64% of pubic lesions, 55% of ischial lesions, and 0% of posterior wall lesions correctly identified. The modified MRI technique utilized did allow for accurate visualization of simulated osteolytic lesions, and may provide a suitable noninvasive method to provide serial assessment of clinical periacetabular osteolysis without the use of ionizing radiation.

Fragestellung Die Verwendung der Hamstringsehnen zur vorderen Kreuzbandrekonstruktion kann ein muskulares Defizit der Kniegelenksbeugung gerade bei hoheren Flexionsgraden zur Folge haben. Die vorliegende Studie soll klaren, inwieweit ein Jahr nach vorderer Kreuzbandplastik sowohl ein Defizit der Beuge- als auch der Streckmuskulatur des Kniegelenks nach Verwendung der Semitendinosussehne allein versus der Kombination aus Semitendinosus- und Gracilissehne vorliegt. Methodik In die Studie wurden 55 Patienten eingeschlossen, die prospektiv erfasst und ein Jahr nach vorderer Kreuzbandplastik untersucht wurden. Der isokinetische Krafttest wurde mit dem Biodex- Pro-3-Dynamometer® durchgefuhrt. Das Bewegungsausmas betrug 95 ° mit einer Extension von 80 ° und einer Flexion von 15 ° ausgehend vom 90 ° gebeugtem Kniegelenk. Die Kraftmessung begann unabhangig vom operierten Knie auf der rechten Seite und wurde an beiden Knien zweimal durchgefuhrt, wobei der zweite Durchgang nach einer ca. dreiminutigen Pause auf der linken Seite begann. Gemessen wurden 20 Wiederholungen bei einer Winkelgeschwindigkeit von 180 °/s und funf Wiederholungen bei 60 °/s nach 30 Sekunden Pause. Gemessen wurden das maximale Drehmoment und die Leistung beider Beine getrennt fur die Extension und Flexion. Die ermittelten Werte entsprechen den Kraftdefiziten in Prozent. Ergebnisse 26 Patienten wurden isoliert mit der Semitendinosussehne (ST), 29 Patienten wurden mit einer Kombination aus Semitendinosus und Gracilissehne (ST/G) versorgt. Bei einer Winkelgeschwindigkeit von 180 °/s fand sich ein Defizit des maximalen Drehmoments fur die Kniegelenksstreckung bei der ST-Gruppe von 7,3% (±15%) und fur die ST/G-Gruppe von 13,6% (±13,2%) jeweils im Vergleich zur gesunden Gegenseite (p=0,02). Fur die Kniegelenksbeugung fand sich bei einer Winkelgeschwindigkeit von 60 °/s ein Kraftdefizit bei der ST-Gruppe von 3,6% (±15,1%) gegenuber 7,8% (±8,7%) fur die ST/G-Gruppe (p=0,01). Das Leistungsdefizit bezuglich der Kniegelenksstreckung bei 180 °/s lag bei der ST-Gruppe bei 7,3% (±15,0%) und bei der ST/G-Gruppe bei 16,1% (±16,6%) (p=0,02). Fur die Beugung betrug das Leistungsdefizit der ST-Gruppe 6,6% (±13,1%) und 10.5% (±9,4%) fur die ST/G-Gruppe bei einer Winkelgeschwindigkeit von 60 °/s (p=0,03). Die ubrigen Werte sowie die Transplantatstabilitat, gemessen mit dem KT-1000, und das klinische Ergebnis des Lysholm-Scores zeigten fur beide Gruppen keine signifikanten Unterschiede. Schlussfolgerung Die vorliegenden Daten zeigen, dass auch ein Jahr nach vorderer Kreuzbandplastik nicht nur ein muskulares Defizit der Kniegelenksbeugung sondern auch der Kniegelenksstreckung in Bezug auf das maximale Drehmoment und die Leistung erwartet werden kann. Diese Defizite sind signifikant groser, wenn die Semitendinosus- und Gracilissehne anstatt nur der Semitendinosussehne verwendet werden.