Enrico Kahl

Autologous Chondrocyte Transplantation for Treating Cartilage Defects of the Talus

BACKGROUND Despite its highly specialized nature, articular cartilage has a poor reparative capability. Treatment of symptomatic osteochondral defects of the talus has been especially difficult until now. METHODS We performed autologous chondrocyte transplantation in twelve patients with a focal deep cartilage lesion of the talus. There were seven female and five male patients with a mean age of 29.7 years. The mean size of the lesion was 2.3 cm(2). All patients were studied prospectively. Evaluation was performed with use of the Hannover ankle rating score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a visual analogue scale for pain, and magnetic resonance imaging. RESULTS All patients were available for follow-up at a mean of sixty-three months. There was a significant improvement in the Hannover score, from 40.4 points preoperatively to 85.5 points at the follow-up examination, with seven excellent results, four good results, and one satisfactory result. The AOFAS mean score was 88.4 points compared with 43.5 points preoperatively. Magnetic resonance imaging showed a nearly congruent joint surface in seven patients, discrete irregularities in four, and an incongruent surface in one. The patients who had been involved in competitive sports were able to return to their full activity level. CONCLUSIONS The promising clinical results of this study suggest that autologous chondrocyte transplantation is an effective and safe way to treat symptomatic osteochondral defects of the talus in appropriately selected patients.

The surgical technique of autologous chondrocyte transplantation of the talus with use of a periosteal graft. Surgical technique.

BACKGROUND Despite its highly specialized nature, articular cartilage has a poor reparative capability. Treatment of symptomatic osteochondral defects of the talus has been especially difficult until now. METHODS We performed autologous chondrocyte transplantation in twelve patients with a focal deep cartilage lesion of the talus. There were seven female and five male patients with a mean age of 29.7 years. The mean size of the lesion was 2.3 cm(2). All patients were studied prospectively. Evaluation was performed with use of the Hannover ankle rating score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a visual analog scale for pain, and magnetic resonance imaging. RESULTS All patients were available for follow-up at a mean of sixty-three months. There was a significant improvement in the Hannover score, from 40.4 points preoperatively to 85.5 points at the follow-up examination, with seven excellent results, four good results, and one satisfactory result. The AOFAS mean score was 88.4 points compared with 43.5 points preoperatively. Magnetic resonance imaging showed a nearly congruent joint surface in seven patients, discrete irregularities in four, and an incongruent surface in one. The patients who had been involved in competitive sports were able to return to their full activity level. CONCLUSIONS The promising clinical results of this study suggest that autologous chondrocyte transplantation is an effective and safe way to treat symptomatic osteochondral defects of the talus in appropriately selected patients.

Cell biological and biomechanical evaluation of two different fixation techniques for rotator cuff repair.

Our objective was to evaluate the cell biology and biomechanical aspects of the healing process after two different techniques in open rotator cuff surgery – double‐loaded bio‐absorbable suture anchors combined with so‐called arthroscopic Mason–Allen stitches (AAMA) and a trans‐osseous suture technique combined with traditional modified Mason–Allen stitches (SMMA). Thirty‐six mature sheep were randomized into two repair groups. After 6, 12, or 26 weeks, evaluation of the reinsertion site of the infraspinatus tendon was performed. The mechanical load‐to‐failure and stiffness results did not indicate a significant difference between the two groups. After 26 weeks, fibrocartilage was sparse in the AAMA group, whereas the SMMA group showed the most pronounced amount of fibrocartilage. We found no ultrastructural differences in collagen fiber organization between the two groups. The relative expression of collagen type II mRNA in the normal group was 1.11. For the AAMA group, 6 weeks after surgery, the relative expression was 55.47, whereas for the SMMA group it was 1.90. This in vivo study showed that the AAMA group exhibited a tendon‐to‐bone healing process more favorable in its cell biology than that of the traditional SMMA technique. Therefore, the AAMA technique might also be more appropriate for arthroscopic repair.

Mechanical behavior of intact and low-grade degenerated cartilage.

Abstract Youngs modulus, elastic and plastic deformation, mechanical hardness and load at failure were determined for low-grade degenerated hyaline cartilage in a porcine model. Osteochondral plugs from the medial condyle of 30 female pigs were used. Cartilage defects were classified using the International Cartilage Repair Society (ICRS) protocol. Mechanical hardness was measured using a Shore A testing device. Total stiffness and plastic deformation was evaluated in the range 50–200 N using a 5-mm indenter. The load at failure was then determined. ICRS grade I specimens showed significantly lower stiffness than grade 0 specimens. ICRS grade 0 specimen showed no significant plastic deformation within the load range 25–100 N. In degenerated cartilage, plastic deformation started at a significantly lower load (50 N). The Youngs modulus at 25 N in ICRS grade 0 specimens (18.8 MPa) was significantly higher than in grade I (11.1 MPa) or grade II (10.5 MPa) specimens. Intact cartilage showed significantly higher tension at failure and mechanical Shore A hardness. Youngs modulus and tension at failure showed strong correlation. Cartilage degeneration is associated with a significant loss of elasticity and mechanical stress resistance. Shore hardness measurement is an adequate method for rapid biomechanical evaluation of cartilage specimens. Zusammenfassung Ziel der Untersuchung war es, das Elastizitätsmodul (E-Modul), die elastische und plastische Deformierung, die mechanische Härte und die Versagenslast in intaktem und niedriggradig geschädigtem hyalinem Schweinegelenkknorpel zu bestimmen. Unmittelbar nach Tötung der 30 weiblichen Schlachtschweine wurden osteochondrale Plugs aus dem medialen Femurkondyl entnommen. Die Klassifikation der Knorpelschäden erfolgte entsprechend den Richtlinien der International Cartilage Repair Society (ICRS). Die mechanische Härte wurde mit einem Shore A-Tester bestimmt. Anschließend wurden die Knorpelflächen mit einem 5 mm-Intender zwischen 50 und 200 N belastet, um die Steifigkeit und die plastische Deformation zu bestimmen. Abschließend wurden die Proben bis zur chondralen Fraktur belastet. Bei Knorpelschaden mit einem ICRS Grad I fand sich eine im Vergleich zum gesunden Knorpel signifikant verminderte Steifigkeit. Gesunder Knorpel zeigte bis zu einer Belastung von 100 N kaum eine plastische Deformation, während ICRS Grad I Knorpel bereits bei einer Belastung von 50 N deutlich plastisch deformiert wurde. Das E-Modul für gesunden Knorpel betrug 18,8 MPa und war signifikant höher als bei ICRS Grad I (11,1 MPa) und ICRS Grad II (10,5 MPa). Gesunder Knorpel hatte eine signifikant höhere mechanische Härte (Shore A) und eine signifikant höhere Versagenslast als degenerierter Knorpel. Dabei korrelierte die Verminderung der Versagenslast signifikant mit der Verminderung des E-Moduls. Die Untersuchungen bestätigen, dass bereits die frühe Knorpeldegeneration mit einer signifikanten Verminderung von Elastizität und Bruchfestigkeit einhergeht. Dabei ist die Shore-Härte-Messung ein geeignetes Verfahren, diese biomechanischen Veränderungen in Knorpelpräparaten schnell zu erfassen.

Karl Fischer titration and coulometry for measurement of water content in small cartilage specimens Bestimmung des Wassergehalts in kleinen Knorpelproben durch Karl-Fischer-Titration und Coulometrie

Abstract This study evaluated the efficiency of Karl Fischer titration and coulometry for measurement of water content in small intact and defective cartilage specimens. Cartilage from the main weight-bearing zone of the medial condyle of 38 fresh sheep knees was used. Of these, 20 condyles had an intact cartilage, while defects (14 grade I and 4 grade II) were found in the rest. The mechanical hardness was determined as Shore A. Cartilage specimens of approximately 5 mg were analyzed in special devices for moisture measurement and then continuously heated up to 105°C. The actual measurement was performed in an electric cell (coulometry). An electrode was laminated with hygroscopic phosphorus pentoxide. In the electrochemical reaction, H and O are liberated from the electrode. The requirement for electric energy correlates with the amount of water in the specimen. The water content in intact cartilage was 66.9%. Grade I (72.6%) and grade II (77.8%) defects had significantly higher water content. Significantly higher and faster spontaneous evaporation was observed in cartilage defects at room temperature. The water content and spontaneous water evaporation correlated with significantly lower mechanical hardness. The experimental design (combined method of thermogravimetry, Karl Fischer titration, and coulometry) was sufficient for evaluating the water content in small cartilage specimens. It is also possible to measure the temperature-dependent water liberation from cartilage specimens.

Biomechanical investigation of uniplanar and biplanar cuts in openingwedge high tibial osteotomy

This study was aimed to determine the biomechanical properties of uniplanar tranversial (UPO) and biplanar, three-dimensional (BPO) osteotomy in medial opening wedge high tibial osteotomy (HTO) in a comparable Sawbone model. Third generation tibial Sawbones were osteotomized in a standardized manner and fixed with an angle-stable, spacer containing plate. Axial stiffness after one and twenty loading cycles (range 50 to 1000 N) was registered as well as displacement within the osteotomy gap and load at failure. After one loading cycle no differences between BPO (n=5) and UPO (n=5) specimens were evaluated. The undergoing of 20 loading cycles caused a significant loss of stiffness. After the cycles BPO specimen had a stiffness of 1755.9 ± 129.2 N/mm. The stiffness in UPO specimen was 1018.5 ± 15.5 N/mm. The difference between the groups was significant. The mean maximum load at failure in UPO specimens was 2633.1 ± 229.4 N. Specimens after BPO had a significant higher maximum load at failure of 4554.8 ± 342.8 N. In BPO specimens the failure always was caused by an infraction in the lateral cortex, whereas in UPO the failure was caused in two-times by an additional dorsal dislocation of the tibial head. This study was undertaken to evaluate the biomechanical properties of a UPO and BPO in medial wedge osteotomy. The results offer a significant advantage for the BPO regarding to axial stiffness under cyclic loading as well as resistance against load to failure. References [1] Bergenudd H,Sahlstrom A,Sanzen L. Total knee arthroplasty after failed proximal tibial valgus osteotomy. J Arthroplasty 1997; 12: 635-638. [2] Coventry MB. Osteotomy of the upper portion of the tibia for degenerative arthritis of the knee. J Bone Joint Surg Am 1965; 47: 984-990. [3] Insall JN,Joseph DM,Msika C. High tibial osteotomy for varus gonarthrosis. A long-term follow-up study. J Bone Joint Surg Am 1984; 66: 1040-1048. [4] Klinger HM,Lorenz F,Harer T. Open wedge tibial osteotomy by hemicallotasis for medial compartment osteoarthritis. Arch Orthop Trauma Surg 2001; 121: 245-247. [5] Koshino T,Murase T,Takagi T,Saito T. New bone formation around porous hydroxyapatite wedge implanted in opening wedge high tibial osteotomy in patients with osteoarthritis. ORIGINAL ARBEITEN Gunter Spahn: Biomechanical investigation of uniplanar cuts in opening-wedge high tibial osteotomy Width the dorsal osteotomy gap [mm] under a load of 1000 N After 1 cycle After 20 cycles