Wolf Petersen

Publications of Wolf Petersen

• Reconstruction of the Posterior Oblique Ligament and the Posterior Cruciate Ligament in Knees With Posteromedial Instability.

  Authors: Andre Weimann, Imke Schatka, Mirco Herbort, Andrea Achtnich, Thore Zantop, Michael Raschke, Wolf Petersen

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 04/2012;

  PURPOSE: Posterior cruciate ligament (PCL) injuries are often associated with injuries of the posteromedial structures of the knee. The motivation for this study was the attempt to test differentPURPOSE: Posterior cruciate ligament (PCL) injuries are often associated with injuries of the posteromedial structures of the knee. The motivation for this study was the attempt to test different reconstruction techniques for the structures of the posteromedial corner in a biomechanical experiment. METHODS: Kinematic studies were carried out on 10 cadaveric knees exposed to a 134-N posterior tibial load, 10-Nm valgus torque, and 5-Nm internal torque at 0°, 30°, 60°, and 90° of flexion. The resulting posterior tibial translation (PTT) was determined using a robotic/universal force-moment sensor testing system for (1) intact knees, (2) PCL-deficient knees, (3) knees with deficiency of the PCL and the posteromedial structures, (4) knees with only the PCL reconstructed, (5) knees with the PCL and posterior oblique ligament (POL) reconstructed, and (6) knees with the PCL, medial collateral ligament (MCL), and POL reconstructed. Kinematic data were analyzed by a 2-factor repeated analysis of variance. RESULTS: When both the PCL and the posteromedial structures were cut, PTT increased significantly at all flexion grades under a posterior tibial load (P < .05). Reconstruction of only the PCL could not restore PTT at 0°, 30°, 60°, and 90° of flexion under loading conditions in a knee with combined injury of the PCL and the posteromedial structures (P > .05). Additional reconstruction of the POL improved PTT at all flexion angles in comparison with only the PCL-reconstructed knee. Reconstruction of the MCL had no significant effect on PTT. CONCLUSIONS: This study shows that reconstruction of the POL contributes significantly to the normalization of coupled PTT in knees with combined injury of the PCL and the posteromedial structures under valgus or internal rotational moment. The supplementary reconstruction of the MCL did not provide significant improvement in knee kinematics. CLINICAL RELEVANCE: The POL should be addressed in the patient with combined injuries of the PCL and the posteromedial structures.

• Accidental Perforation of the Lateral Femoral Cortex in ACL Reconstruction: An Investigation of Mechanical Properties of Different Fixation Techniques.

  Authors: Mirco Herbort, Sebastian Heletta, Michael J Raschke, Benedikt Schliemann, Nani Osada, Wolf Petersen, Thore Zantop

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 03/2012; 28(3):382-9.

  The aim of this study was to evaluate the mechanical properties of anterior cruciate ligament (ACL) reconstruction using the medial portal technique with cortical fixation and hybrid fixation afterThe aim of this study was to evaluate the mechanical properties of anterior cruciate ligament (ACL) reconstruction using the medial portal technique with cortical fixation and hybrid fixation after penetration of the lateral cortex by use of different drill sizes. In this biomechanical study a porcine in vitro model was used. The testing protocol consisted of a cyclic loading protocol (1,000 cycles, 50 and 250 N) and subsequent ultimate failure testing. Number of cyclic loadings survived, stiffness, yield load, maximum load, and graft elongation, as well as failure mode, were analyzed after ACL reconstruction with 5- to 9-mm soft-tissue grafts. In the control group, conventional penetration of the lateral cortex with a 4.5-mm drill and cortical fixation were performed. In the tested groups, the lateral cortex was penetrated with a drill matching the graft size. In the first part of the study, we used cortical fixation. In the second part, we used hybrid fixation with an interference screw. In the first part of the study, ACL reconstruction with 5- to 6-mm perforation of the lateral cortex showed no significant differences in ultimate failure load after cyclic loading compared with the control group (P > .05). Specimens with reconstruction with 7- to 9-mm perforation of the lateral cortex and cortical fixation did not survive the cyclic loading protocol. In the second part of the study, with a hybrid fixation technique, ultimate failure testing after cyclic loading of specimens with 7- to 9-mm penetration showed no significant differences in tested parameters compared with the control group (P > .05). After penetration of the lateral cortex with a drill size of more than 6 mm, cortical ACL fixation results in poor mechanical properties. Hybrid fixation increases the mechanical properties significantly after penetration with a 7- to 9-mm drill. We advise caution to avoid penetration of the lateral femoral cortex when using cortical flip-button fixation. In case of accidental perforation of the lateral cortex with a diameter greater than 6 mm, we recommend performing hybrid fixation.

• Arthroscopic fixation of matrix-associated autologous chondrocyte implantation: importance of fixation pin angle on joint compression forces.

  Authors: Mirco Herbort, Sandra Zelle, Dieter Rosenbaum, Nani Osada, Michael Raschke, Wolf Petersen, Thore Zantop

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 06/2011; 27(6):809-16.

  The aim of the study was to investigate the effect of pin fixation perpendicular and 30° tilted to the matrix surface on the joint compression forces. In a porcine knee model, joint compressionThe aim of the study was to investigate the effect of pin fixation perpendicular and 30° tilted to the matrix surface on the joint compression forces. In a porcine knee model, joint compression forces were recorded with a digital pressure sensor above the medial meniscus and with axial compression of 100 N by use of a material testing machine. The forces were recorded for an intact femoral condyle, as well as a standardized cartilage defect of 25 × 20 mm, after matrix-associated autologous chondrocyte implantation (m-ACI) (BioSeed C; Biotissue Technologies, Freiburg, Germany), fixed by use of a conventional suture technique and pin fixation with a biodegradable pin perpendicular and 30° tilted to the matrix surface. In knees with cartilage defects, the peak compression forces (mean, 824 kPa) were significantly increased compared with the intact knee joint (564 kPa). After m-ACI implantation with a chondral suture (581.3 kPa) and perpendicular pin fixation, the joint compression forces of the cartilage defect were significantly decreased (630.7 kPa). There were no significant differences compared with the intact knee. After 30° tilted pin insertion, mean joint compression forces were significantly increased (1,740 kPa). This study shows that after chondral suture and perpendicular pin fixation, there are no increased compression forces in the knee joint in comparison to an intact knee. Thirty degree tilted pin insertion contributes to increased joint compression forces. A tilted insertion during pin fixation in m-ACI should be avoided because it may lead to increased joint compression forces, especially after cartilage defect lesions on the tibial side.

• Biomechanical effectiveness of an arthroscopic posterior bankart repair versus an open bone block procedure for posterior shoulder instability.

  Authors: Mathias Wellmann, Evgenij Bobrowitsch, Nicklas Khan, Thilo Patzer, Henning Windhagen, Wolf Petersen, Michael Bohnsack

  The American journal of sports medicine. 12/2010; 39(4):796-803.

  The most effective surgical treatment for traumatic posterior shoulder instability remains unclear. An arthroscopic posterior Bankart repair is as effective as an open posterior boneThe most effective surgical treatment for traumatic posterior shoulder instability remains unclear. An arthroscopic posterior Bankart repair is as effective as an open posterior bone block-capsulorrhaphy procedure regarding the restoration of humeral displacement with posterior and inferior forces. Controlled laboratory study. Biomechanical testing of 16 human shoulders was performed in 3 testing conditions: after ventilation (intact joint), after creation of a posteroinferior Bankart lesion with an additional cut of the posterior band of the inferior glenohumeral ligament, and after surgical shoulder stabilization. The shoulder stabilization was performed either by an open posterior bone block procedure and glenoid-based T-capsulorrhaphy or by an arthroscopic Bankart repair. Testing was performed in 2 positions-the sulcus test position and the jerk test position-with a passive humerus load of 50 N applied in the posterior, posteroinferior, and inferior directions. After the arthroscopic repair, there was no significant difference between the translation and the intact state for all tested directions. The bone block repair-capsulorrhaphy caused a significant decrease of posterior translation (sulcus test and jerk test positions) and posteroinferior translation (jerk test position). But the resulting posterior and posteroinferior translation was even significantly lower than the translation measured for the intact joints. However, the reduction of inferior translation, compared with that of the defect condition, was not significant after the bone block repair (sulcus test and jerk test positions). Compared with that of the intact joint, inferior translation after the bone block repair was significantly higher. The posterior bone block repair-capsulorrhaphy overcorrects posterior translation and does not effectively restore inferior stability, whereas the arthroscopic posterior Bankart repair restores posterior and inferior laxity of the intact joint. An arthroscopic posterior capsulolabral repair more precisely restores posterior and inferior glenohumeral joint laxity and is therefore recommended as the first choice of treatment.

• Local treatment of meniscal lesions with vascular endothelial growth factor.

  Authors: Sebastian Kopf, Falk Birkenfeld, Roland Becker, Wolf Petersen, Christian Stärke, Christoph Jan Wruck, Mersedeh Tohidnezhad, Deike Varoga, Thomas Pufe

  The Journal of bone and joint surgery. American volume. 11/2010; 92(16):2682-91.

  The healing potential in the avascular regions of the meniscus is very limited, and improving the vascularity might be a reasonable way to improve healing. Vascular endothelial growth factor (VEGF)The healing potential in the avascular regions of the meniscus is very limited, and improving the vascularity might be a reasonable way to improve healing. Vascular endothelial growth factor (VEGF) is one of the most potent proangiogenetic factors. We hypothesized that the local application of VEGF(165) would (1) improve the healing of a lesion in the avascular region of the meniscus, (2) induce angiogenesis in both the avascular and vascular regions, and (3) increase the amounts of VEGF mRNA and VEGF. In eighteen sheep, the medial menisci were cut longitudinally in the avascular region and were sutured. Three groups were established depending on the suture material: (1) uncoated Ethibond, (2) Ethibond coated with VEGF(165) and its carrier Poly(D,L-Lactide) (PDLLA), and (3) Ethibond coated with PDLLA. The contralateral medial menisci served as a control group. Each of the three suture type groups included six animals. After eight weeks, the sheep were killed, and the menisci were examined macroscopically. Immunohistochemistry of Factor VIII and VEGF and real-time reverse-transcription polymerase chain reaction (RT-PCR) of VEGF mRNA were performed. Additionally, the VEGF release kinetics from the VEGF/PDLLA-coated suture were evaluated in vitro. In this model, VEGF did not improve meniscal healing. It did not increase angiogenesis in the avascular or vascular region, the VEGF concentration, or the amount of VEGF mRNA. VEGF release from the coated suture peaked on Day 3 and was nearly zero on Day 9. The local application of VEGF(165) as eluted from suture did not increase meniscal angiogenesis or improve meniscal healing. In addition, there was no effect on the amount of VEGF mRNA and VEGF. The VEGF carrier (PDLLA) may have been inadequate because of the short duration of VEGF supply.

• Strategies for repair of radial tears close to the meniscal rim--biomechanical analysis with a cyclic loading protocol.

  Authors: Mirco Herbort, Sami Siam, Simon Lenschow, Wolf Petersen, Thore Zantop

  The American journal of sports medicine. 10/2010; 38(11):2281-7.

  Lateral meniscectomy contributes to early-onset osteoarthritis. Biomechanical properties of sutures repairs for complete radial meniscal tears remain unknown. Double horizontal suture techniques forLateral meniscectomy contributes to early-onset osteoarthritis. Biomechanical properties of sutures repairs for complete radial meniscal tears remain unknown. Double horizontal suture techniques for repair of radial meniscal tears with a shorter distance from the meniscal rim provide significantly higher structural properties than do comparable single-suture techniques with a wider distance from the meniscal rim. Controlled laboratory study. In 55 fresh-frozen porcine menisci, standardized complete radial meniscal tears were repaired with different distances from the meniscal rim and tear edges and with different numbers of sutures. In group A, the suture was 4 mm from the tear and 8 mm from the meniscal rim; group B, 2 mm from tear; group C, 2 mm from tear, 12 mm from rim; group D, double-loop technique, 2 mm from tear, 5 mm and 10 mm from rim; group E, longitudinal tear sutured with 1 loop, 8 mm from rim, and 4 mm between stitches. The specimens were cyclically loaded 1000 times between 5 and 20 N and loaded to failure. All repaired constructs survived the cyclic loading protocol. Compared with the single-loop techniques, the double-loop technique (group D) showed a significantly higher maximum load and yield load and significantly lower displacement after 1000 cycles. Compared with group B, group C had a higher displacement after 1000 cycles (P < .05), and its stiffness showed a descriptive negative trend (P = .09). Displacement after cycling testing in group C was higher than in groups B and D (P < .05). Repair of radial meniscal tears with a second suture and shorter distance from the meniscal rim has a positive influence on primary stability. Different distances from tear edges apparently have no influence on structural properties. Horizontal sutures for repair of radial meniscal tears provide high stability and can be enhanced with a second horizontal suture and shorter distance from the meniscal rim.

• [Arthroscopic reconstruction of the anterolateral bundle of the posterior cruciate ligament in single-bundle technique with autologous hamstring grafts].

  Authors: Wolf Petersen, Thore Zantop

  Operative Orthopädie und Traumatologie. 10/2010; 22(4):354-72.

  Restoration of the function of the posterior cruciate ligament (PCL). Chronic posterior instability with posterior tibial translation of >10 mm. Fixed posterior drawer, local infections at the kneeRestoration of the function of the posterior cruciate ligament (PCL). Chronic posterior instability with posterior tibial translation of >10 mm. Fixed posterior drawer, local infections at the knee joint, local soft-tissue damage, poor compliance of the patient. Surgery starts with arthroscopic examination of the knee joint and therapy of associated injuries (meniscus and cartilage injuries). Harvesting of the semitendinosus and gracilis tendons is performed via a 3 cm long skin incision 1 cm distally and medially of the tibial tuberosity. The tendons are folded to a four- or five-stranded graft with a minimum length of 10 cm. The femoral tunnel for the graft is drilled via a deep anterolateral portal under arthroscopic control. For drilling of the tibial tunnel, a posteromedial portal is needed. The tibial insertion of the PCL is debrided with a shaver and a specific raspatory. For tibial tunnel placement, a specific closed aimer is used and a Kirschner wire is placed in the center of the tibial insertion. This Kirschner wire is overdrilled using a cannulated drill with a diameter according to the graft size. After femoral fixation, the graft is tensioned in 90° flexion with 80 N. At the femoral and tibial side, a hybrid fixation is performed with a button (flipp tack) and a resorbable interference screw. If there are any signs of posterolateral instability, a posterolateral corner reconstruction is performed before tensioning and fixation of the PCL graft. For 6 weeks, the knee is immobilized in extension with a posterior tibial support (PTS) brace (Medi, Bayreuth, Germany). Passive range of motion exercises should be performed in prone position (first 2 weeks 0-0-30°, 3rd to 4th week 0-0-60°, 5th to 6th week 0-0-90°). After the first 6 weeks, a movable brace is needed at daytime. At nighttime, the patient has to wear the PTS brace. Between 2003 and 2006, a PCL reconstruction in singlebundle technique was performed in 58 patients. In 42 cases, a simultaneous reconstruction of the posterolateral corner was done. The Lysholm Score improved from 62.2 to 88.4 points, the Tegner Activity Score from 3.3 to 5.4 points.

• [Modified Larson technique for posterolateral corner reconstruction of the knee].

  Authors: Thore Zantop, Wolf Petersen

  Operative Orthopädie und Traumatologie. 10/2010; 22(4):373-86.

  Posterolateral soft-tissue reconstruction to restore knee kinematics in isolated or combined posterolateral instabilities. Isolated or multiligament knee injuries with posterolateral insufficiencyPosterolateral soft-tissue reconstruction to restore knee kinematics in isolated or combined posterolateral instabilities. Isolated or multiligament knee injuries with posterolateral insufficiency (popliteus tendon, lateral collateral ligament [LCL], popliteofibular ligament). Arthrofibrosis. Severe varus deformity. Fixed posterior drawer. Doubts about compliance. Graft harvest of semitendinosus tendon. In cases with multiligament reconstruction or associated posterior cruciate ligament (PCL) reconstruction contralateral graft harvest. Suture at 24 cm with baseball stitches using biodegradable material. Two-incision technique: one over the fibular head, one over the lateral epicondyle. Dissection along the biceps femoris to identify and free the peroneal nerve. Kirschner wire-guided creation of a 4.5-mm tunnel through the fibular head. Longitudinal incision of tensor fasciae latae and Kirschner wire drilling at the insertion of the LCL and the politeus tendon. Isometric testing. Overdrilling with an appropriately sized drill (6-7 mm, depth 40 mm). Graft passage through the fibular head and underneath biceps muscle and tensor fasciae latae into the femoral tunnel. Fixation with a biodegradable interference screw at 70° knee flexion in slight internal rotation. Defensive rehabilitation due to associated PCL reconstruction using a Posterior Tibial Support (PTS) brace for 6 weeks (day and night). PCL brace with limited range of motion for the next 6 weeks and PTS brace at night. Rehabilitation in a prone position. 42 patients (10/2003-10/2006) with posterolateral reconstruction according to Larson. All patients received combined PCL and posterolateral reconstruction. No intraoperative complications, one patient with hematoma in the popliteal fossa (conservative treatment), two patients with hematoma following contralateral graft harvest. At followup after 2.6 years, 40 patients were enrolled showing high improvement according to IKDC (International Knee Documentation Committee) and Lysholm Scores.

• ACL mismatch reconstructions: influence of different tunnel placement strategies in single-bundle ACL reconstructions on the knee kinematics.

  Authors: Mirco Herbort, Simon Lenschow, Freddie H Fu, Wolf Petersen, Thore Zantop

  Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 05/2010; 18(11):1551-8.

  To evaluate the influence of tibial and femoral tunnel position in ACL reconstruction on knee kinematics, we compared ACL reconstruction with a tibial and femoral tunnel in anteromedial (AM-AMTo evaluate the influence of tibial and femoral tunnel position in ACL reconstruction on knee kinematics, we compared ACL reconstruction with a tibial and femoral tunnel in anteromedial (AM-AM reconstruction) and in posterolateral footprint (PL-PL reconstruction) with a reconstruction technique with tibial posterolateral and femoral anteromedial tunnel placement (PL-AM reconstruction). In 9 fresh-frozen human cadaveric knees, the knee kinematics under simulated Lachman (134 N anterior tibial load) and a simulated pivot shift test (10 N/m valgus and 4 N/m internal tibial torque) were determined at 0°, 30°, 60°, and 90° of flexion. Kinematics were recorded for intact, ACL-deficient, and single-bundle ACL reconstructed knees using three different reconstruction strategies in randomized order: (1) PL-AM, (2) AM-AM and (3) PL-PL reconstructions. Under simulated Lachman test, single-bundle PL-AM reconstruction and PL-PL reconstructions both showed significantly increased anterior tibial translation (ATT) at 60° and 90° when compared to the intact knee. At all flexion angles, AM-AM reconstruction did not show any statistical significant differences in ATT compared to the intact knee. Under simulated pivot shift, PL-AM reconstruction resulted in significantly higher ATT at 0°, 30°, and 60° knee flexion and AM-AM reconstructions showed significantly higher ATT at 30° compared to the intact knee. PL-PL reconstructions did not show any significant differences to the intact knee. AM-AM reconstructions restore the intact knee kinematics more closely when compared to a PL-AM technique resembling a transtibial approach. PL-PL reconstructions showed increased ATT at higher flexion angles, however, secured the rotational stability at all flexion angles. Due to the independent tibial and femoral tunnel location, a medial portal technique may be superior to a transtibial approach.

• Double-bundle reconstruction cannot restore intact knee kinematics in the ACL/LCL-deficient knee.

  Authors: Thore Zantop, Tobias Schumacher, Steffen Schanz, Michael J Raschke, Wolf Petersen

  Archives of orthopaedic and trauma surgery. 03/2010; 130(8):1019-26.

  The aim of this study was to evaluate the effect of single-bundle (SB) and anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction on the resulting knee kinematics in a simulatedThe aim of this study was to evaluate the effect of single-bundle (SB) and anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction on the resulting knee kinematics in a simulated clinical setting with ACL rupture and associated extra-articular damage to the lateral structures. It was hypothesized that anatomic DB ACL reconstruction restores the intact knee kinematics in ACL/LCL-deficient knees, whereas SB ACL reconstruction fails to restore the intact knee kinematics. Ten fresh-frozen human cadaver knees were subjected to anterior tibial load of 134 N (simulated KT 1000) and combined rotatory load of 10-Nm valgus and 4-Nm internal tibial torque (simulated pivot shift) using a robotic/UFS testing system. The resulting knee kinematics was determined for intact, ACL/LCL-deficient, SB ACL-reconstructed/LCL-deficient, and DB ACL-reconstructed/LCL-deficient knee. Statistical analysis was performed using a two-way ANOVA test with the level of significance set at P < 0.05. Under a simulated KT 1000 test, anterior tibial translation (ATT) following SB ACL reconstruction was statistically significant at 0 degrees , 30 degrees and 60 degrees of knee flexion when compared to the intact knee. ATT after DB ACL reconstruction showed no statistically significant difference from the intact knee; however, there was a significant difference in SB reconstruction at 0 degrees and 30 degrees of knee flexion. Under a simulated pivot shift test, both SB and DB ACL reconstruction failed to restore the intact knee kinematics. The results of the study did not support our initial hypothesis. Though DB reconstructions were significantly superior to SB reconstruction under simulated KT 1000 test, SB as well as DB reconstruction failed to restore the intact kinematics under simulated pivot shift loads. The clinical relevance of this study is that caution and precise preoperative diagnostics are needed to avoid failure of intra-articular ACL reconstruction if the extra-articular stabilizers are torn.

• [Minimally Invasive Acromioclavicular Joint Reconstruction (MINAR)].

  Authors: Wolf Petersen, Mathias Wellmann, Steffen Rosslenbroich, Thore Zantop

  Operative Orthopädie und Traumatologie. 03/2010; 22(1):52-61.

  Reduction and retention of an acromioclavicular (AC) joint dislocation with a button/suture augmentation cerclage (Flip tack, Karl Storz, Tuttlingen, Germany). Dislocation of the AC joint (RockwoodReduction and retention of an acromioclavicular (AC) joint dislocation with a button/suture augmentation cerclage (Flip tack, Karl Storz, Tuttlingen, Germany). Dislocation of the AC joint (Rockwood III and V). Chronic instabilities in combination with autogenous replacement of the coracoclavicular ligaments. Lateral clavicular fracture with rupture of the coracoclavicular ligaments. Patients in poor general condition. Local soft-tissue infection. Low-degree dislocation of AC joint (Rockwood I und II). Fracture of the clavicular shaft. Chronic instabilities without ligament replacement. The coracoid process is exposed by a 3 cm long skin incision. A hole is drilled through the coracoid process with the help of a specific aiming device. The suture cerclage is connected to two buttons. One of the buttons is then pushed through the coracoid process. The button is flipped and the suture thereby fixed to the coracoid process. The other anchor is pulled through a hole in the clavicle and the cerclage is secured with a surgical knot after reduction of the AC joint. Application of an abduction splint for 4 weeks (15 degrees). 23 patients with an acute luxation of the AC joint were operated with a minimally invasive coracoclavicular cerclage (five patients with Rockwood type III and 18 patients with Rockwood type V). Mean operative time was 28.6 min. Perior postoperative complications such as nerve and vascular injuries, thoracic injuries, infection, thrombosis, and embolism did not occur. The mean Constant Score was 94.1 points (73-100 points) after a mean of 23.3 months (18-28 months). In two cases, a slight loss of reposition of less than half of the clavicle width in comparison with the contralateral side was observed.

• Arthroscopic implantation of a matrix to cover large chondral defect during microfracture.

  Authors: Thore Zantop, Wolf Petersen

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 11/2009; 25(11):1354-60.

  Microfracturing techniques have been reported to be successful cartilage-restoring treatment options in defects of smaller sizes. The success may be limited by the size of the defect and the shoulderMicrofracturing techniques have been reported to be successful cartilage-restoring treatment options in defects of smaller sizes. The success may be limited by the size of the defect and the shoulder of the intact surrounding cartilage. We report a new technique using a 3-dimensional matrix to cover large cartilage defects during microfracture healing. In contrast to autologous chondrocyte implantation techniques, this technique is a 1-stage procedure. The defect cover consists of a resorbable polymer felt and sodium hyaluronan to induce hemostasis and to protect the underlying tissue. After conventional microfracture, the defect size is determined with an intra-articular measuring device, and the matrix is sized and introduced with an arthroscopic grasp. Depending on the size of the defect, the 3-dimensional matrix is fixed with 1 or 2 biodegradable pins perpendicular to the surface. The combination of the common microfracture technique with the implantation of the matrix leads to complete defect filling with cartilaginous repair tissue and therefore improves cartilage regeneration in the defect. We conclude that the introduced technique may be helpful in large cartilage defects combining the benefit of microfracturing and avoidance of the increased morbidity of matrix-associated autologous chondrocyte implantation.

• Meniscal repair.

  Authors: Christian Stärke, Sebastian Kopf, Wolf Petersen, Roland Becker

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 10/2009; 25(9):1033-44.

  The meniscus plays an important role in preventing osteoarthritis of the knee. Repair of a meniscal lesion should be strongly considered if the tear is peripheral and longitudinal, with concurrentThe meniscus plays an important role in preventing osteoarthritis of the knee. Repair of a meniscal lesion should be strongly considered if the tear is peripheral and longitudinal, with concurrent anterior cruciate ligament reconstruction, and in younger patients. The probability of healing is decreased in complex or degenerative tears, central tears, and tears in unstable knees. Age or extension of the tear into the avascular area are not exclusion criteria. Numerous repair techniques are available, and suture repair seems to provide superior biomechanical stability. However, the clinical success rate does not correlate well with the mechanical strength of the repair technique. Biologic factors might be of greater importance to the success of meniscal repair than the surgical technique. Therefore, the decision on the most appropriate repair technique should not rely on biomechanical parameters alone. Contemporary all-inside repair systems have decreased the operating time and the level of surgical skill required. Despite the ease of use, there is a potential for complications because of the close proximity of vessels, nerves, and tendons, of which the surgeon should be aware. There is no clear consensus on postoperative rehabilitation. Weight bearing in extension would most likely not be crucial in typical longitudinal lesions. However, higher degrees of flexion, particularly with weight bearing, give rise to large excursions of the menisci and to shear motions, and should therefore be advised carefully. Long-term studies show a decline in success rates with time. Further studies are needed to clarify the factors relevant to the healing of the menisci. Tissue engineering techniques to enhance the healing in situ are promising but have not yet evolved to a practicable level.

• Biomechanical evaluation of a single-row versus double-row repair for complete subscapularis tears.

  Authors: Mathias Wellmann, Philipp Wiebringhaus, Ina Lodde, Hazibullah Waizy, Christoph Becher, Michael Raschke, Wolf Petersen

  Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 09/2009;

  The purpose of the study was to compare a single-row repair and a double-row repair technique for the specific characteristics of a complete subscapularis lesion. Ten pairs of human cadavericThe purpose of the study was to compare a single-row repair and a double-row repair technique for the specific characteristics of a complete subscapularis lesion. Ten pairs of human cadaveric shoulder human shoulder specimens were tested for stiffness and ultimate tensile strength of the intact tendons in a load to failure protocol. After a complete subscapularis tear was provoked, the specimens were assigned to two treatment groups: single-row repair (1) and a double-row repair using a "suture bridge" technique (2). After repair cyclic loading a subsequent load to failure protocol was performed to determine the ultimate tensile load, the stiffness and the elongation behaviour of the reconstructions. The intact subscapularis tendons had a mean stiffness of 115 N/mm and a mean ultimate load of 720 N. The predominant failure mode of the intact tendons was a tear at the humeral insertion site (65%). The double-row technique restored 48% of the ultimate load of the intact tendons (332 N), while the single-row technique revealed a significantly lower ultimate load of 244 N (P = 0.001). In terms of the stiffness, the double-row technique showed a mean stiffness of 81 N/mm which is significantly higher compared to the stiffness of the single-row repairs of 55 N/mm (P = 0.001). The double-row technique has been shown to be stronger and stiffer when compared to a conventional single-row repair. Therefore, this technique is recommended from a biomechanical point of view irrespectively if performed by an open or arthroscopic approach.

• Femoral bridge stability in double-bundle ACL reconstruction: impact of bridge width and different fixation techniques on the structural properties of the graft/femur complex.

  Authors: Ann-Kristin Lehmann, Nani Osada, Thore Zantop, Michael Raschke, Wolf Petersen

  Archives of orthopaedic and trauma surgery. 05/2009;

  BACKGROUND: The aim of this study was to evaluate the impact of different widths of the bony bridge between the femoral AM and PL bundle tunnel and different fixation techniques on the structuralBACKGROUND: The aim of this study was to evaluate the impact of different widths of the bony bridge between the femoral AM and PL bundle tunnel and different fixation techniques on the structural properties of the graft/femur complex in double-bundle ACL reconstructions. HYPOTHESIS: Double-bundle ACL reconstruction with a bony bridge between AM and PL bundle tunnel of 1 mm results in significantly lower structural properties of the graft/femur complex when compared to a bridge of 2 and 3 mm. Interference screw fixation significantly lowers the structural properties when compared to cortical fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Double-bundle ACL reconstructions using different bridge widths (1 mm, 2 mm, and 3 mm bridge) were loaded to failure after a cyclic loading protocol (1,000 cycles 0-200 N) and the structural properties were compared to a single-bundle ACL reconstruction group (n = 10 in each group). The structural properties of using a cortical button fixation were then compared to interference screw fixation (2 mm bridge). Statistical analyses were performed using a Mann-Whitney test (P < 0.05). RESULTS: Double-bundle reconstructions with cortical button fixation (1, 2, and 3 mm bridge) showed significantly higher ultimate failure loads and stiffness and significantly lower elongation compared to single-bundle reconstructions. Double-bundle ACL reconstructions with a 1 mm bridge showed significantly reduced structural properties of the graft/femur complex compared to a 2 or 3 mm bridge. Aperture fixation led to significantly lower ultimate loads when compared to cortical fixation. CONCLUSION: The bony bridge between the two femoral tunnels in double-bundle ACL reconstructions influences the stability of the graft/femur complex. Aperture fixation using interference screws shows inferior results when compared to cortical fixation. CLINICAL RELEVANCE: The results suggest that the indication for anatomical ACL reconstruction may include the size of the lateral femoral condyle. In small knees, a second femoral tunnel may be difficult to locate with a minimum bridge width of 2 mm.

• Coracoclavicular ligament reconstruction: biomechanical comparison of tendon graft repairs to a synthetic double bundle augmentation.

  Authors: Mathias Wellmann, Jan Kempka, Steffen Schanz, Thore Zantop, Hazibullah Waizy, Michael Raschke, Wolf Petersen

  Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 03/2009;

  For currently presented anatomical coracoclavicular ligament repairs issues such as autologous tendon graft versus synthetic suture augmentation and the optimum fixation strategies for both types ofFor currently presented anatomical coracoclavicular ligament repairs issues such as autologous tendon graft versus synthetic suture augmentation and the optimum fixation strategies for both types of reconstruction are not solved. The purpose of the study was to compare the biomechanical properties of different tendon graft repairs to the characteristics of a synthetic polyester augmentation. Four anatomical coracoclavicular ligament repairs were biomechanically tested: 5 mm coracoclavicular tendon loop with suture fixation, tendon loop with flip button fixation, tendon loop with interference screw fixation versus a double 1.0-mm polyester repair with flip button fixation. The biomechanical testing included cyclic superio-inferior loading and a subsequent load to failure protocol. The ultimate failure loads were significantly higher for the double polyester/flip button repair (927 N) compared to all tendon repair techniques (maximum 640 N). In contrast the stiffness level was higher for the tendon repairs compared to the polyester/flip button repair (68.7 N/mm) but strongly dependent on the fixation technique (interference screw 97.2 N/mm, flip button 84.9 N/mm, side to side suture 60.9 N/mm). A synthetic coracoclavicular augmentation using a polyester suture provides adequate structural properties compared to a tendon repair. Therefore the decision for a tendon graft should be made by the necessity of a biologic substrate rather than by the assumption of a biomechanical advantage.

• Biomechanical evaluation of an augmented coracoacromial ligament transfer for acromioclavicular joint instability.

  Authors: Mathias Wellmann, Ina Lodde, Steffen Schanz, Thore Zantop, Michael J Raschke, Wolf Petersen

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 01/2009; 24(12):1395-401.

  PURPOSE: The purpose of this study was to establish and biomechanically evaluate an augmented coracoacromial ligament (CAL) transfer technique that eliminates the biomechanical drawbacks of thePURPOSE: The purpose of this study was to establish and biomechanically evaluate an augmented coracoacromial ligament (CAL) transfer technique that eliminates the biomechanical drawbacks of the conventional Weaver-Dunn procedure and restores the intact joint kinematics. METHODS: The acromioclavicular joints of 12 human shoulder specimens were tested for anterior, posterior, and superior translation during cyclic loading as well as for stiffness and ultimate tensile strength in a subsequent load-to-failure protocol. After luxation, the specimens were randomly assigned to 2 treatment groups: CAL transfer and polyester-augmented CAL transfer. For the coracoclavicular augmentation, a strong 1-mm polyester loop was intertwined between 2 flip buttons for coracoid and clavicle fixation. Only the medial half of the CAL was transferred and fixed in a medialized position at the clavicle. RESULTS: Translational testing showed significantly higher anterior (12.1 mm), posterior (9 mm), and superior (13.4 mm) translation for the CAL transfer technique as compared with the native joint (5.4 mm, 3.3 mm, and 3.4 mm, respectively) and the modified augmented CAL transfer procedure (6.2 mm, 4.2 mm, and 3.6 mm, respectively) (P < .05). No significant differences were found between the intact acromioclavicular joint and the augmented CAL transfer regarding anterior and superior translation. Posterior translation was significantly higher for the augmented CAL transfer compared with the native joints (P = .033), but the quantitative difference was small (0.8 mm). CONCLUSIONS: The augmented CAL transfer using the medial half of the CAL and supplementing it with a strong 1-mm polyester loop intertwined between 2 flip buttons for coracoid and clavicle fixation has been shown to restore anterior and superior translation of the native acromioclavicular joint. CLINICAL RELEVANCE: The promising biomechanical in vitro results must be interpreted in the context of clinical investigations regarding the risk of bony erosion resulting from the use of permanent suture material.

• Open Shoulder Repair of Osseous Glenoid Defects: Biomechanical Effectiveness of the Latarjet Procedure Versus a Contoured Structural Bone Graft.

  Authors: Mathias Wellmann, Wolf Petersen, Thore Zantop, Mirco Herbort, Philipp Kobbe, Michael J Raschke, Christof Hurschler

  The American journal of sports medicine. 01/2009;

  BACKGROUND: To address glenoid bone deficiency, 2 competing surgical approaches are currently recommended: transplantation of a structural bone graft or the coracoid transfer according to Latarjet.BACKGROUND: To address glenoid bone deficiency, 2 competing surgical approaches are currently recommended: transplantation of a structural bone graft or the coracoid transfer according to Latarjet. Nonetheless, no clear advantages for either procedure are evident. HYPOTHESIS: The Latarjet procedure will provide an equivalent beneficial effect on glenohumeral stability as the placement of an intra-articular bone graft. STUDY DESIGN: Controlled laboratory study. METHODS: Stability testing of 8 cadaveric shoulders was performed in a dynamic shoulder simulator under 4 different conditions: (1) anteroinferior capsulotomy, (2) anteroinferior glenoid defect, (3) transplantation of a contoured bone graft, and (4) Latarjet procedure. Translational movement of the humeral head in response to a load of 25 N was evaluated in the anterior and anteroinferior directions. RESULTS: The Latarjet procedure significantly reduced translation by 354% relative to the glenoid defect condition at 30 degrees of abduction and by 374% at 60 degrees of abduction. In comparison, the bone graft significantly reduced translation by 179% at 30 degrees of abduction and by 159% at 60 degrees of abduction. The effect of the bone graft was lowest in external rotation at 60 degrees of abduction where a decrease of translation of 133% was observed. Comparing both reconstruction techniques, the Latarjet procedure resulted in significantly less anterior and anteroinferior translation at 60 degrees of abduction. CONCLUSION: Biomechanically, the Latarjet procedure outperforms the bone graft in reducing translation in anteroinferior glenoid bone defects. The advantage of the Latarjet procedure is particularly evident at 60 degrees of glenohumeral abduction. CLINICAL RELEVANCE: On the basis of the results of this biomechanical study, the authors recommend the Latarjet procedure for restoring stability in shoulders with a significant glenoid bone defect.

• Effect of coracoacromial ligament resection on glenohumeral stability under active muscle loading in an in vitro model.

  Authors: Mathias Wellmann, Wolf Petersen, Thore Zantop, Steffen Schanz, Michael J Raschke, Christof Hurschler

  Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 12/2008; 24(11):1258-64.

  PURPOSE: The purpose of this study was to determine whether or not the coracoacromial ligament (CAL) has a relevant effect in stabilizing the humeral head under active rotator cuff and deltoidPURPOSE: The purpose of this study was to determine whether or not the coracoacromial ligament (CAL) has a relevant effect in stabilizing the humeral head under active rotator cuff and deltoid loading compared to passive loading conditions without muscular stabilization. METHODS: Nine human cadaver shoulders were tested in a dynamic shoulder simulator. Forces of the rotator cuff muscles and the middle deltoid muscle were applied using servohydraulic cylinders, while glenohumeral motion was imposed in closed-loop force-control by a sensor-guided robot. Translational movement was measured with the CAL intact and resected under two different testing conditions: (1) simulated physiologic muscle force loading and (2) the passive drawer test, with loads applied in anterior, anterio-inferior, and anterio-superior directions in different glenohumeral positions. RESULTS: The resection of the CAL caused a significant increase in anterior and superior translation during translational testing and muscle force loading. However, the passive testing mode revealed differences in translation from 2.4 to 4.4 mm. The differences were quantitatively minor under muscle loading conditions, ranging from 0.5 to 1.0 mm. CONCLUSIONS: CAL resection induces an increased glenohumeral translation under passive loading conditions without muscular stabilization, whereas the effect under rotator cuff and deltoid loading was defined to be quantitatively small. CLINICAL RELEVANCE: A resection of the CAL should be critically discussed in shoulders with massive rotator cuff tears. In contrast, in muscularly intact shoulders, the release of the CAL evokes a light increase of translation, the clinical relevance of which is questionable.

• Rotational instability of the knee: internal tibial rotation under a simulated pivot shift test.

  Authors: Nadine Diermann, Tobias Schumacher, Steffen Schanz, Michael Raschke, Wolf Petersen, Thore Zantop

  Archives of orthopaedic and trauma surgery. 08/2008;

  INTRODUCTION: Recently, several publications investigated the rotational instability of the human knee joint under pivot shift examinations and reported the internal tibial rotation as measurementINTRODUCTION: Recently, several publications investigated the rotational instability of the human knee joint under pivot shift examinations and reported the internal tibial rotation as measurement for instrumented knee laxity measurements. We hypothesize that ACL deficiency leads to increased internal tibial rotation under a simulated pivot shift test. Furthermore, it was hypothesized that anatomic single bundle ACL reconstruction significantly reduces the internal tibial rotation under a simulated pivot shift test when compared to the ACL-deficient knee. METHODS: In seven human cadaveric knees, the kinematics of the intact knee, ACL-deficient knee, and anatomic single bundle ACL reconstructed knee were determined in response to a 134 N anterior tibial load and a combined rotatory load of 10 N m valgus and 4 N m internal tibial rotation using a robotic/UFS testing system. Statistical analyses were performed using a two-way ANOVA test. RESULTS: Single bundle ACL reconstruction reduced the anterior tibial translation under a simulated KT-1000 test significantly compared to the ACL-deficient knee (P < 0.05). After reconstruction, there was a statistical significant difference to the intact knee at 30 degrees of knee flexion. Under a simulated pivot shift test, anatomic single bundle ACL reconstruction could restore the intact knee kinematics. Internal tibial rotation under a simulated pivot shift showed no significant difference in the ACL-intact, ACL-deficient and ACL-reconstructed knee. CONCLUSION: In conclusion, ACL deficiency does not increase the internal tibial rotation under a simulated pivot shift test. For objective measurements of the rotational instability of the knee using instrumented knee laxity devices under pivot shift mechanisms, the anterior tibial translation should be rather evaluated than the internal tibial rotation.