Stefan Hankemeier

Influence of perfusion and cyclic compression on proliferation and differentiation of bone marrow stromal cells in 3-dimensional culture

Until now, there has been no in vitro model that duplicates the environment of bone marrow. The purpose of this study was to analyze proliferation and differentiation of human bone marrow stromal cells (hBMSC) under the influence of continuous perfusion and cyclic mechanical loading. hBMSC of seven individuals were harvested, grown in vitro, and combined. 10(6) hBMSC were seeded on a bovine spongiosa disc and incubated in a bioreactor system. Cell culture was continued using three different conditions: Continuous perfusion (group A), 10% cyclic compression at 0.5Hz (group B) and static controls (group C). After 24h, 1, 2, and 3 weeks, we determined cell proliferation (MTS-assay) and osteogenic differentiation (osteocalcin ELISA, Runx2 mRNA). Tenascin-C mRNA was quantified to exclude fibroblastic differentiation. In groups A and B, proliferation was enhanced after 2 weeks (48.6+/-19.6x10(3) (A) and 44.6+/-14.3 x 10(3) cells (B)) and after 3 weeks (46.6+/-15.1 x 10(3) (A) and 44.8+/-10.2 x 10(3) cells (B)) compared with controls (26.3+/-10.8 x 10(3) (2 weeks) and 17.1+/-6.5 x 10(3) cells (3 weeks), p<0.03). Runx2 mRNA was upregulated in both stimulated groups after 1, 2, and 3 weeks compared to control (group A, 1 week: 5.2+/-0.7-fold; p<0.01, 2 weeks: 4.4+/-1.9-fold; p<0.01, 3 weeks: 3.8+/-1.7-fold; p=0.013; group B, 1 week: 3.6+/-1.1-fold, p<0.01, 2 weeks: 4.2+/-2.2-fold, p<0.01; 3 weeks: 5.3+/-2.7-fold, p<0.01). hBMSC stimulated by cyclic compression expressed the highest amount of osteocalcin at all time points (1 week: 294.5+/-88.4 mg/g protein, 2 weeks: 294.4+/-73.3mg/g protein, 3 weeks: 293.1+/-83.6 mg/g protein, p0.03). The main stimulus for cell proliferation in a 3-dimensional culture of hBMSC is continuous perfusion whereas mechanical stimulation fosters osteogenic commitment of hBMSC. This study thereby contributes to the understanding of physical stimuli that influence hBMSC in a 3-dimensional cell culture system.

Computer-assisted analysis of lower limb geometry: higher intraobserver reliability compared to conventional method

Exact radiographic evaluation of lower limb alignment, joint orientation and leg length is crucial for preoperative planning and successful treatment of deformities, fractures and osteoarthritis. Improvement of the accuracy of radiographic measurements is highly desirable. To determine the intraobserver reliability of conventional analysis of lower extremity geometry, 59 long leg radiographs were randomly analyzed 5 times by a single surgeon. The measurements revealed a standard deviation between 0.36° and 1.17° for the angles mLPFA, mLDFA, MPTA, LDTA, JLCA and AMA (nomenclature according to Paley), and 0.94 mm and 0.90 mm for the MAD and leg length, respectively. Computer-assisted analysis with a special software significantly reduced the standard deviation of the mLDFA, MPTA, LDTA, JLCA (each p < 0.001), AMA (p = 0.032) and MAD (p = 0.023) by 0.05–0.36° and 0.14 mm, respectively. Measuring time was reduced by 44% to 6:34 ± 0:45 min (p < 0.001). Digital calibration by the software revealed an average magnification of conventional long leg radiographs of 4.6 ± 1.8% (range: 2.7–11.9%). Computer-assisted analysis increases the intraobserver reliability and reduces the time needed for the analysis. Another major benefit is the ease of storage and transfer of digitized images. Due to the varying magnification factors on long leg radiographs, the use of magnification markers for calibration is recommended.

Navigated intraoperative analysis of lower limb alignment

Introduction: Accurate intraoperative assessment of lower limb alignment is crucial for the treatment of long bone fractures, implantation of knee arthroplasties and correction of deformities. During orthopaedic surgery, exact real time control of the mechanical axis is strongly desirable. The aim of this study was to compare conventional intraoperative analysis of the mechanical axis by the cable method with continuous, 3-dimensional imaging with a navigation system. Materials and methods: Twenty legs of fresh human cadaver were randomly assigned to conventional analysis with the cable method (n=10) or navigated analysis with a fluoroscopy based navigation system (n=10). The intersection of the mechanical axis with the tibia plateau was presented as percentage of the tibia plateau (beginning with 0% at the medial border and ending with 100% laterally). CT-scans were performed for all legs and the CT-values of the mechanical axis were compared to the measurements after cable method and navigation. Furthermore, the radiation time and dose area product of both groups for single analysis of the mechanical axis was compared. Results: Conventional evaluation of the mechanical axis by the cable method showed 6.0±3.1% difference compared to the analysis by CT. In the navigated group the difference was 2.6±1.8% (P=0.008). Radiation time and dose area product were highly significantly lower after conventional measurement. Conclusions: Navigated intraoperative evaluation of the mechanical axis offers increased accuracy compared to conventional intraoperative analysis. Furthermore, navigation provides continuous control not only of the mechanical axis, but also of the sagittal and transverse plane. Using the cable method, radiation exposure depends on the number of measurements and is lower compared to the navigation system for single intraoperative analysis of the mechanical axis, but may be higher in case of repeated intraoperative measurements.

Leg lengthening using intramedullay skeletal kinetic distractor: Results of 57 consecutive applications

BACKGROUND Mechanically activated intramedullary lengthening nails are advantageous over external fixator. However, difficulties with the control of the distraction rate are the main drawbacks, which may in turn cause insufficient bone regenerate. PATIENTS AND METHODS A total of 57 lengthening procedures were performed using intramedullary skeletal kinetic distractor (ISKD) nail in 53 patients (femoral = 45 and tibial = 12). Average length gain was 4.3 ± 1.6 cm. The cause of shortening was post-traumatic (n = 33), congenital (n = 20), post-tumour resection (n = 1), cosmetic femoral lengthening (n = 2) and post-correction of distal femoral varus deformity (n = 1). RESULTS The desired lengthening was achieved in all patients. The mean follow-up period was 23 ± 12 months. The healing index for patients with normal bone healing was 1.2 ± 0.32 months/cm. Complications in femoral lengthening were superficial wound infection (n = 1), premature consolidation (n = 4) and insufficient bone regenerate (n = 11), while in the tibial lengthening, two developed equinus contractures,one had compartment syndrome following implantation of the nail and one insufficient bone regenerate.Furthermore, nine runaway nails and three non-distracting nails were present in the femoral lengthening.One non-distracting nail responded to manipulation under anaesthesia, one required exchange nailing and accidental acute lengthening of 3 cm took place while manipulating the third nail. Patients with femoral lengthening and those with insufficient regenerate had significantly higher distraction rates (P = 0.006 and 0.003, respectively). Six out of the nine runaway nails developed insufficient bone regenerate. In addition,10.7-mm tibial ISKD nails were found to have lower rates of runaway nails compared with other used diameters. CONCLUSION We emphasise the rule of distraction rates above 1.5 mm/day in the development of insufficient bone regenerate. Distraction problems with these nails are mostly due to dysfunction within the ratcheting mechanism, which may be related to the diameter of the nail. New designs for mechanically activated nails with a better control mechanism for the distraction rate are required.

Bone marrow stromal cells in a liquid fibrin matrix improve the healing process of patellar tendon window defects.

Following injury, ligaments and tendons do not regain their normal biological and biomechanical status. This study analyzed whether an injection of human bone marrow stromal cells (BMSC) or human fibroblast in a liquid fibrin matrix influences the histological results, ultrastructural morphology, mRNA expression of essential extracellular matrix proteins, and material properties of the healing tissue. Standardized full-thickness, full-length defects of the central portion of patellar tendons were created in 96 immunodeficient rats, and filled with human BMSC in a fibrin matrix (BMSC group), human fibroblasts in a fibrin matrix (fibroblast group), or fibrin matrix only (matrix group), or left untreated (defect group). Histological sections revealed more mature tissue formation with more regular patterns of cell distribution in the BMSC group, without signs of ectopic tissue formation into bone or cartilage. Mean collagen fibril diameter and relative area covered by collagen fibrils were significantly higher at 10 and 20 days postoperatively in the BMSC group compared to the defect and matrix groups, and comparable to normal tendon tissue. Further, collagen I mRNA expression, collagen I/collagen III mRNA ratio, and Youngs modulus were significantly increased at 20 days postoperatively in comparison to the defect and matrix groups. In the fibroblast group, only mean collagen fibril diameter was significantly higher compared to the defect group, whereas the other biological and biomechanical parameters were not significantly improved. This study reveals that an injection of BMSC in a liquid fibrin matrix stimulates histological, ultrastructural, molecular biologic, and biomechanical parameters of patellar tendon healing, whereas injection of fibroblasts in fibrin matrix had only minor effects on the stimulation of tendon healing.

Femoral nail removal should be restricted in asymptomatic Patients

Femoral nail removal has been suggested as a routine procedure for symptomatic and asymptomatic patients. The aim of this study was to evaluate whether asymptomatic patients have long-term complaints after femoral nail removal. Additionally, factors that might extend operation time and effect soft tissue healing negatively were analyzed. A retrospective study on the removal of 164 femoral nails after fracture consolidation was done. A review of the patient charts and radiographs was done. Neither the interval between nail implantation and nail removal or the use of an end-cap significantly influenced the operation time. The surgeon’s qualification and nail depth were the only variables that influenced operation time. Neither operation time, nail depth, surgeon’s qualification, nor the grade of heterotopic ossification significantly influenced the incidence of wound healing problems. One hundred nine patients (73%) were available for the followup interview. Preoperatively, 58 patients (53%) had local complaints. Of these 58 patients, 78% reported improvement and 7% reported an aggravation of their local complaints. Of the 51 patients who were asymptomatic before surgery, 20% reported long-term complaints at followup. Only symptomatic patients should be considered for femoral nail removal.

Hindlimb Growth After a Transphyseal Reconstruction of the Anterior Cruciate Ligament: A Study in Skeletally Immature Sheep With Wide-Open Physes

Background There is a lot of controversy in the recent literature with regard to the optimal treatment of anterior cruciate ligament (ACL) injuries during growth. Iatrogenic growth disturbance due to physeal damage is a potential complication, forcing many orthopaedic surgeons to treat these injuries conservatively. Hypothesis It is possible to perform a fully transphyseal ACL reconstruction in an ovine model with wide-open physes without creating growth disturbances. Study Design Descriptive laboratory study. Materials and Methods Four-month-old skeletally immature sheep underwent a transphyseal ACL reconstruction of the right knee. The surgical technique followed the criteria known to be essential to avoid growth disturbances in humans; the tibial tuberosity was spared to prevent a genu recurvatum, thermal damage to the growth plates was avoided, the physes were perforated with a small-diameter drill in the center of the growth plate, a soft tissue graft was used, graft fixation was achieved far away from the growth plates, the perforated growth plates were filled by the soft tissue graft, and the graft was moderately pretensioned before fixation. The left knee served as a control. A computer-assisted evaluation of long radiographs (frontal and sagittal plane) of the exarticulated hindlimbs was performed to exactly evaluate the limb alignment, joint orientation, and leg length. The animals were sacrificed in groups of 6 after 3, 6, 12, and 24 weeks. Results No angular deformities or leg-length discrepancies occurred after this transphyseal ACL reconstruction procedure throughout the remaining growth. Conclusion This large-animal study supports the clinical observation that it is possible to perform an ACL reconstruction without creating growth disturbances as long as a number of key principles are followed. Clinical Relevance Previous animal studies argued against ACL reconstruction in skeletally immature patients. This large-animal study provides support for early operative treatment of ACL ruptures even in young patients with open physes.

Limb lengthening with the Intramedullary Skeletal Kinetic Distractor (ISKD).

ZusammenfassungOperationszielKallusdistraktion von Femur oder Tibia durch ein intramedulläres Implantat, welches sich mechanisch durch alternierende Rotationsbewegungen von mindestens 3° verlängert.IndikationenBeinverkürzungen des Femurs oder der Tibia zwischen 20 und 80 mm.Gleichzeitige Korrektur von Achsendeformitäten im Bereich der Osteotomie möglich.KontraindikationenOffene Wachstumsfugen.Unzureichender Markrauminnendurchmesser (nach Aufbohrung des Femurs < 14,5 mm, der Tibia < 12,5 mm).Mangelnde Mitarbeit des Patienten.Ausgeprägte Fehlstellungen.Osteitis.Weichteilinfekte.OperationstechnikRückenlagerung. Am Femur im proximalen oder mittleren Schaftdrittel Osteotomie nach fächerförmigen queren Anbohrungen, unter Rotationskontrolle mit zwei 3,0-mm-Kirschner-Drähten. An der Tibia quere Osteotomie mit einer Gigli-Säge. Korrektur von Achsen- oder Rotationsfehlstellungen. Antegrades Aufbohren der Markhöhle am Femur 2,0 mm, an der Tibia 1,5 mm über den geplanten Nageldurchmesser. Einführen des Intramedullary Skeletal Kinetic Distractor (ISKD) in den Markraum, distale Verriegelung in Freihandtechnik, Kontrolle der Rotation sowie des Osteotomiespalts und proximale Verriegelung mit einem Zielgerät. Intraoperative Kontrolle der Distraktion des ISKD über einen externen Monitor. Am Femur 3 Tage und an der Tibia 5 Tage postoperativ Beginn zunehmender Mobilisation, um eine tägliche Distraktion von etwa 1 mm zu erreichen. Bei unzureichender Verlängerung führt der Patient gezielte Rotationsbewegungen durch, bis die erwünsche Verlängerung erreicht ist.ErgebnisseVier Patienten mit einem mittleren Alter von 29 Jahren (18–36 Jahre) wurde ein ISKD implantiert. Neben drei posttraumatischen Femurverkürzungen wurde eine kongenitale Tibiaverkürzung behandelt. Zwei Femora wiesen präoperativ komplexe Fehlstellungen auf. Die durchschnittliche Verlängerung betrug 31 mm (26–40 mm).Der intraoperative Blutverlust betrug 230 ml (100–320 ml), die durchschnittliche Operationszeit 108 min (90–145 min). Die tägliche Distraktionsstrecke belief sich im Durchschnitt auf 1,2 mm (0,9–1,8 mm). Vollbelastung wurde nach 10 Wochen (7–14 Wochen) gestattet, Arbeitsfähigkeit bestand nach 11 Wochen (7–16 Wochen).Bei der Nachuntersuchung durchschnittlich 2,3 Jahre postoperativ bestanden keine Einschränkungen der Kniegelenkbeweglichkeit. Das Kallusregenerat war 80 Tage (51–111 Tage) nach der Operation knöchern durchbaut bei einem mittleren Heilungsindex von 2,9 Tagen/mm (1,8–4,1 Tage/mm). Innerhalb des Beobachtungszeitraums waren keine Komplikationen aufgetreten. Gemäß dem Paley-Score erreichten alle Patienten ein exzellentes Ergebnis.AbstractObjectiveCallus distraction of the femur or tibia with an intramedullary distractor, which lengthens mechanically through alternating rotations of at least 3°.IndicationsFemoral or tibial shortening between 20 and 80 mm.Angular and rotational deformities can be corrected at the osteotomy site.ContraindicationsOpen epiphyses.Small medullary canal (after intramedullary reaming femoral diameter < 14.5 mm, tibial diameter < 12.5 mm).Severe deformities.Insufficient compliance.Osteitis.Soft-tissue infections.Surgical TechniqueSupine position. Femoral shaft osteotomy at the proximal or middle third by multiple drill holes completed with a chisel. For lengthening of the tibia, osteotomy with a Gigli saw is preferred. Control of the rotation by two parallel 3.0-mm Kirschner wires. Correction of angular or rotational deformities. Via stab incision reaming of the medullary canal with a flexible reamer. The femur is overreamed 2.0 mm and the tibia 1.5 mm above the desired implant diameter. Insertion of the Intramedullary Skeletal Kinetic Distractor (ISKD) into the medullary canal and distal locking in freehand technique. Control of the rotation and of the osteotomy gap. Proximal locking with an aiming device. For femoral lengthening 3 days and for tibial lengthening 5 days postoperatively the distraction is begun by increasing mobilization with partial weight bearing, to achieve daily distraction of 1 mm. In case of insufficient distraction, additional rotations are performed by the patient while checking the external monitor that displays the daily and total distraction length.ResultsIntramedullary lengthening with the ISKD was performed in four patients having an average age of 29 years (18–36 years). Two femoral shortenings were combined with complex rotational and angular deformities. The average lengthening of three femora and one tibia was 31 mm (26–40 mm).The average intraoperative blood loss was 230 ml (110–320 ml), the mean surgical time 108 min (90–145 min). The average daily distraction amounted to 1.2 mm (0.9–1.8 mm). Full weight bearing was permitted after 10 weeks (7–14 weeks), return to regular work after 11 weeks (7–16 weeks).At follow-up examination of an average of 2.3 years postoperatively the knee range of motion was full. Consolidation was noted 80 days (51–111 days) postoperatively with an average consolidation index of 2.9 days/mm (1.8–4.1 days/mm). No complications were observed. According to the Paley Score all patients had an excellent outcome.OBJECTIVE Callus distraction of the femur or tibia with an intramedullary distractor, which lengthens mechanically through alternating rotations of at least 3 degrees. INDICATIONS Femoral or tibial shortening between 20 and 80 mm. Angular and rotational deformities can be corrected at the osteotomy site. CONTRAINDICATIONS Open epiphyses. Small medullary canal (after intramedullary reaming femoral diameter < 14.5 mm, tibial diameter < 12.5 mm). Severe deformities. Insufficient compliance. Osteitis. Soft-tissue infections. SURGICAL TECHNIQUE Supine position. Femoral shaft osteotomy at the proximal or middle third by multiple drill holes completed with a chisel. For lengthening of the tibia, osteotomy with a Gigli saw is preferred. Control of the rotation by two parallel 3.0-mm Kirschner wires. Correction of angular or rotational deformities. Via stab incision reaming of the medullary canal with a flexible reamer. The femur is overreamed 2.0 mm and the tibia 1.5 mm above the desired implant diameter. Insertion of the Intramedullary Skeletal Kinetic Distractor (ISKD) into the medullary canal and distal locking in freehand technique. Control of the rotation and of the osteotomy gap. Proximal locking with an aiming device. For femoral lengthening 3 days and for tibial lengthening 5 days postoperatively the distraction is begun by increasing mobilization with partial weight bearing, to achieve daily distraction of 1 mm. In case of insufficient distraction, additional rotations are performed by the patient while checking the external monitor that displays the daily and total distraction length. RESULTS Intramedullary lengthening with the ISKD was performed in four patients having an average age of 29 years (18-36 years). Two femoral shortenings were combined with complex rotational and angular deformities. The average lengthening of three femora and one tibia was 31 mm (26-40 mm). The average intraoperative blood loss was 230 ml (110-320 ml), the mean surgical time 108 min (90-145 min). The average daily distraction amounted to 1.2 mm (0.9-1.8 mm). Full weight bearing was permitted after 10 weeks (7-14 weeks), return to regular work after 11 weeks (7-16 weeks). At follow-up examination of an average of 2.3 years postoperatively the knee range of motion was full. Consolidation was noted 80 days (51-111 days) postoperatively with an average consolidation index of 2.9 days/mm (1.8-4.1 days/mm). No complications were observed. According to the Paley Score all patients had an excellent outcome.

Biodegradable Screw Versus a Press-Fit Bone Plug Fixation for Hamstring Anterior Cruciate Ligament Reconstruction A Prospective Randomized Study

Background Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing. Hypothesis Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation. Study Design Randomized controlled trial; Level of evidence, 1. Methods Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years. Results The bone tunnel enlargement determined by CT was 106.9% ± 10.9% for group P and 121.9% ± 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% ± 15.2% versus 121.5% ± 10.1% in the coronal plane (P < .01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 ± 1.4 mm vs 1.8 ± 1.5 mm; P = .08). Conclusion Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.

10-Jahres-Ergebnisse knochenmarkstimulierender Therapie der Osteochondrosis dissecans tali

ZusammenfassungDie optimale Therapie der Osteochondrosis dissecans tali (ODT) wird aktuell sehr kontrovers diskutiert. Neben knochenmarkstimulierenden, faserknorpelinduzierenden Verfahren wie der Abrasionsplastik, Herdanbohrung und Mikrofrakturierung werden in zunehmendem Ausmaß die autologe osteochondrale Transplantation und autologe Chondrozytentransplantation eingesetzt. 10,4 Jahre nach knochenmarkstimulierender Therapie wurden 45 Sprunggelenke von 44 Patienten mit einer ODT im Stadium 3 und 4 nach Berndt und Harty nachuntersucht und die Ergebnisse mit dem AOFAS-Score, Mazur-Score sowie der radiologischen Klassifikation von van Dijk analysiert. An allen Sprunggelenken war das Dissekat entfernt und eine Abrasion des subchondralen Knochens durchgeführt worden sowie in 67% eine zusätzliche antegrade Herdanbohrung erfolgt. Die maximale Ausdehnung der Läsion betrug präoperativ durchschnittlich 1,1 cm. Ein exzellentes funktionelles Resultat wurde im Score von Mazur bei 28 Patienten (62%) beobachtet, bei 12 Patienten (27%) ein gutes und bei 5 (11%) ein mäßiges oder schlechtes Resultat. Der durchschnittliche AOFAS-Score betrug 91 Punkte (66–100 Punkte). An 8 Gelenken (18%) waren innerhalb des Beobachtungszeitraumes weitere operative Eingriffe erforderlich. Progressive osteoarthrotische Veränderungen gemäß der Klassifikation von van Dijk wurden an 7 Sprunggelenken (16%) nachgewiesen. Patienten über 40 Jahre, mit Adipositas sowie vorbestehenden osteoarthrotischen Veränderungen erreichten signifikant schlechtere Ergebnisse im AOFAS- und Mazur-Score. Die knochenmarkstimulierende Therapie der ODT im Spätstadium ist ein günstiges,wenig invasives Verfahren und stellt zumindest bei kleineren ODT-Läsionen eine gute Behandlungsoption dar. Neuere Verfahren wie die autologe osteochondrale Transplantation und autologe Chondrozytentransplantation führen zu überwiegend guten und sehr guten 2- bis 4-Jahres-Ergebnissen, haben jedoch ihre Überlegenheit im Langzeitverlauf noch nachzuweisen.AbstractThe optimal operative therapy for the treatment of osteochondritis dissecans tali is still controversial. Beside bone marrow-stimulating techniques like abrasion arthroplasty, drilling and microfracturing,new techniques like autologous osteochondral transplantation and autologous chondrocyte transplantation are increasingly used. This study reviewed the clinical, radiological and subjective long-term outcome of bone marrowstimulating therapy for 45 ankles with an osteochondritis dissecans tali stage 3 or 4 according to the classification by Berndt and Harty. All ankles were treated by the removal of the dissecate and abrasion of the subchondral bone. In 67%, an additional antegrade drilling of the defect was performed. The average maximum size of the lesion was 1.1 cm. At follow-up examination, 10.4 years (7.1–13.5 years) postoperatively, the average AOFAS-score was 91 points (66–100 points). Using the score of Mazur, the outcome of 28 ankles (62%) was rated excellent, 12 ankles (27%) were rated good and five ankles (11%) fair or poor. Progressive osteoarthritic changes, according to the classification of van Dijk,were seen in seven ankles (16%). Reoperations were necessary in eight cases (18%). Obesity, age older than 40 years and preoperative osteoarthritic changes had a significant negative impact on the clinical outcome. Bone marrow stimulating therapy is an inexpensive, low invasive therapy and a good therapeutic option at least for small Berndt/Harty stage 3 and 4 ODT lesions. Autologous chondrocyte transplantation and osteochondral autografts yield encouraging 2- and 4-year results, but still have to prove their superiority in long-term follow-up studies.