Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: A guideline by the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU).

BACKGROUND: Autologous chondrocyte implantation (ACI) is an established and well-accepted procedure for the treatment of localised full-thickness cartilage defects of the knee. METHODS: The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning therapeutic consequences of primary cartilage lesions and the suitable indication for ACI. RESULTS: Based on best available scientific evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than three to four square centimetres; in the case of young and active sports patients at 2.5cm(2), while advanced degenerative joint disease needs to be considered as the most important contraindication. CONCLUSION: The present review gives a concise overview on important scientific background and the results of clinical studies and discusses the advantages and disadvantages of ACI. LEVEL OF EVIDENCE: Non-systematic Review.

[Periprosthetic knee fractures]. / Periprothetische Frakturen des Kniegelenkes.

BACKGROUND: The cumulative incidence of periprosthetic fractures around the knee is increasing further because of an extended indication for knee replacement, previous revision arthroplasty, rising life expectancy and comorbidities. AIM OF THE WORK: The relevance of local parameters such as malalignment, osseous defects, neighbouring implants, aseptic loosening and low-grade infections may sometimes be hidden behind the manifestation of a traumatic fracture. A differentiated diagnostic approach before the treatment of a periprosthetic fracture is of paramount importance, while the physician in-charge should also have particular expertise in fracture treatment and in advanced techniques of revision endoprosthetics. The following work gives an overview of this topic. RESULTS: Valid classifications are available for categorising periprosthetic fractures of the femur, the tibia and the patella respectively, which are helpful for the selection of treatment. CONCLUSIONS: With the wide-ranging modern treatment portfolio bearing in mind the substantial rate of complications and the heterogeneous functional outcome, the adequate analysis of fracture aetiology and the corresponding transformation into an individualised treatment concept offer the chance of an acceptable functional restoration of the patient at early full weight-bearing and prolonged implant survival. The management of complications is crucial to the final outcome.

[Post-treatment rehabilitation after autologous chondrocyte implantation: State of the art and recommendations of the Clinical Tissue Regeneration Study Group of the German Society for Accident Surgery and the German Society for Orthopedics and Orthopedic Surgery]. / Nachbehandlung bei der autologen Chondrozytentransplantation: Eine Bestandsaufnahme und Empfehlung der AG Klinische Geweberegeneration der DGU/DGOOC.

BACKGROUND: Over the course of the past two decades autologous chondrocyte implantation (ACI) has become an important surgical technique for treating large cartilage defects. The original method using a periostal flap has been improved by using cell-seeded scaffolds for implantation, the matrix-based autologous chondrocyte implantation (mb-ACI) procedure. MATERIAL AND METHODS: Uniform nationwide guidelines for post-ACI rehabilitation do not exist. A survey was conducted among the members of the clinical tissue regeneration study group concerning the current rehabilitation protocols and the members of the study group published recommendations for postoperative rehabilitation and treatment after ACI based on the results of this survey. RESULTS: There was agreement on fundamentals concerning a location-specific rehabilitation protocol (femoral condyle vs. patellofemoral joint). With regard to weight bearing and range of motion a variety of different protocols exist. Similar to this total agreement on the role of magnetic resonance imaging (MRI) for postsurgical care was found but again a great variety of different protocols exist. CONCLUSIONS: This manuscript summarizes the recommendations of the members of the German clinical tissue regeneration study group on postsurgical rehabilitation and MRI assessment after ACI (level IVb/EBM).

[Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: a guideline by the working group "Tissue Regeneration" of the German Society of Orthopaedic Surgery and Traumatology (DGOU)]. / Stellenwert der autologen Chondrozytentransplantation (ACT) in der Behandlung von Knorpelschäden des Kniegelenks - Empfehlungen der AG Klinische Geweberegeneration der DGOU.

Autologous chondrocyte transplantation/implantation (ACT/ACI) is an established and recognised procedure for the treatment of localised full-thickness cartilage defects of the knee. The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning potential consequences of primary cartilage lesions and the suitable indication for ACI. Based on current evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than 3-4 cm2; in the case of young and active sports patients at 2.5 cm2. Advanced degenerative joint disease is the single most important contraindication. The review gives a concise overview on important scientific background, the results of clinical studies and discusses advantages and disadvantages of ACI.

[Localisation of TGF-beta and PDGF and their relevance for the pathogenesis of arthrofibrosis]. / Lokalisation von TGF-beta und PDGF und deren Bedeutung für die Pathogenese der Arthrofibrose.

Arthrofibrosis is a disabling complication after knee trauma and surgery and is characterised clinically by joint stiffness. Due to an immune response, the proliferation of fibroblasts and synthesis of extracellular matrix proteins are increased. The cytokines transforming growth factor beta (TGF-beta) and platelet-derived growth factor (PDGF) are critical players in tissue fibrosis, stimulating cell proliferation and the production of various extracellular matrix proteins. Tissue samples from the infrapatellar fat pad and intercondylar synovia of seven patients (age 18-49 years) suffering from arthrofibrosis were taken at surgery. The mean interval between trauma and arthrolysis was 14.3 months. All samples were stained with haematoxylin and eosin, and monoclonal and polyclonal antibodies were applied for immunohistological localisation of TGF-beta and PDGF. The percentage of both cytokines was then analysed using an image analysis system. Tissue samples with no macroscopic pathology of the synovial tissue from eight patients for anterior cruciate ligament replacement served as controls. Immunostaining for TGF-beta and PDGF was found to be increased in arthrofibrotic tissue. Both cytokines could be detected subsynovially around inflammatory cells. The profibrotic cytokines TGF-beta and PDGF play an important role in the pathogenesis of arthrofibrosis. Both cytokines are key mediators of tissue fibrosis.

Joint position awareness and sports activity after capsulolabral reconstruction in the overhead athlete.

A total of 24 overhead athletes with posttraumatic, chronic anterior shoulder instability underwent surgery. Twenty-two patients were examined after an average follow-up of 2.8 +/- 0.7 years. On average, a Constant-Score and Constant-Murley-Score of 93.7 +/- 5.3 points and an ASES-Score of 95.0 +/- 5.1 points were achieved. The redislocation rate was 9 %. The study demonstrated, that despite the good clinical results, only 12 out of 22 (55 %) of patients were able to return to their previous sports activity level. This relevant problem is in agreement with other similar studies [ ], so it was further addressed by determination of joint position awareness (JPA) and electromyographic muscle activity. Postoperatively, a persisting deficit of JPA, as well as an altered EMG pattern, was found with a significant reduction in activity of the deltoideus muscle on the operated side. The analysis of the data of each patient showed that there was a significant relation between the restitution of JPA and ability to return to the previous sports activity level. In contrast, the relation between EMG pattern and full recovery to completely unrestricted shoulder function was not significant. The anterior capsulolabral reconstruction enables a reliable restoration of shoulder stability and a low rate of complications. The problem that a relatively high percentage of overhead athletes can not return to their previous performance level is based on an impaired joint position awareness.

Femoral avulsion fracture of the posterior cruciate ligament in association with a rupture of the popliteal artery in a 9-year-old boy: a case report.

Ruptures of the posterior cruciate ligament (PCL) and especially proximal bony avulsion fractures in children are very rare. This in combination with a rupture of the popliteal artery is extremely rare. Thus, an exact incidence is not available from the literature. Overall, these injuries are severe and often lead to chronic knee instability. We report a case of a 9-year-old boy who suffered a traumatic displacement of the left knee with a rupture of the popliteal artery. Prior to transfer to our department, he was treated by a saphenous vein bypass graft and by a transfixation of the knee using two oblique percutaneous pins. We performed magnetic resonance imaging (MRI) scan of the knee which revealed a femoral avulsion fracture of the PCL. Other ligaments and menisci were intact. A transosseous femoral fixation using non-absorbable stitches was carried out. A 1-year follow-up after surgery demonstrates intact peripheral perfusion and sensation, straight axes of both legs and a physiological gait. Minimal differences of the length and circumference of both legs could be measured. The posterior laxity (Lachman-test) was about 5/8 mm (right/left knee) and 2/5 mm (right/left knee) in 90 degrees flexion. The range of motion (extension/flexion) was 5/0/140 degrees -/5/100 degrees (right-left knee). Intact cruciate ligaments were confirmed by MRI. Minimal experience exists in treatment of combined injuries to the PCL and the popliteal artery in children.

Influence of cyclic mechanical strain and heat of human tendon fibroblasts on HSP-72.

Heat shock protein 72 (HSP-72) is a member of a superfamily of different proteins that are synthesized as a cytoprotective response following cellular stress. Mechanical strain is an important component in ligament and tendon healing. Up to the present point of time, the influence of mechanical strain on the expression of HSP-72 is unknown. Tendon fibroblasts from the patellar tendons of nine individuals were isolated and amplified in vitro. First, the effect of 15 or 60 min of heat exposition was studied immunohistochemically and by Western blotting. In a second experiment, the effects of 15 and 60 min of cyclic longitudinal stretching were investigated. Samples were taken after 2, 4 and 8 h. The heat exposition experiments indicate that HSP-72 accumulates in the nucleus and that there is a transient upregulation. This effect is more prominent after 60 min of heat exposure. The same reaction was found after stretching stimulation, however, to a lesser extent. There was a transient up regulation of HSP-72 after short-term stretching and a biphasic increase after 60 min of stretching. Upregulation of HSP-72 by heat and mechanical stress is a response in human fibroblasts which involves a nuclear translocation. The response differs with regard to the time points beyond 2 h after the application of either stress.

[Sensorimotor deficit after capsulolabral reconstruction in chronic instability of the shoulder. A clinical experimental study]. / Sensomotorik nach Kapsellabrumrekonstruktion bei chronischer Schulterinstabilität. Eine klinisch-experimentelle Studie.

The anterior capsulolabral reconstruction technique described by Jobe is a modified Bankart repair. The capsular shift is performed in a horizontal direction via a subscapularis split approach avoiding any incision of the muscle. Of 43 patients with posttraumatic anterior shoulder instability treated by anterior capsulolabral reconstruction, 35 were examined after 3.7+/-1.4 years, and of these, 29 (82.9%) had no pain; the external rotation deficit was 4.1+/-2.9 degrees . The average Constant-Murley score was 92.4+/-7.1 and the average ASES score was 93.3+/-8.4. The reluxation rate was 7.7%. This technique was shown to provide good clinical results, but only 69% of the patients were able to return to their prior sporting activity level. This particular problem was addressed by investigating the joint proprioception and the activity of the periarticular muscles. The results confirmed a persistent deficit of proprioception as well as a pathologic EMG pattern after anterior capsulolabral reconstruction, which may explain the problem of incomplete restoration of the function of the shoulder joint.

[Stage-based treatment by partial meniscectomy, meniscal refixation and transplantation]. / Stadiengerechte Therapie durch Meniskusresektion, -naht und -ersatz.

Clinical and experimental studies have demonstrated that the meniscus is important for normal knee function. Loss of meniscus results in abnormal load transmission across the knee and may lead to degenerative joint disease. Preservation of meniscal tissue is therefore important. About 10 % of all meniscal tears are repairable. The most successful repairs occur in younger patients who have an acute, vertical tear in the vascular portion of the meniscus. Currently, arthroscopic meniscal repair procedures include the inside-out, the outside-in and the all-inside technique. Vertical suture techniques are superior to horizontally placed sutures. From a biomechanical point of view, 2-0 to 1 sutures are recommended for suture repair. Various meniscus implants are also available for meniscal repair. The initial fixation strength of the implants is lower compared to vertical sutures. A combination of suture techniques and implants might be a treatment option in posterior meniscal lesions. The collagen meniscus implant has been designed to support tissue ingrowth after segmental medial meniscectomy. Although fibrocartilage matrix formation has been shown, long-term clinical follow-ups are still required. Meniscal allograft transplantation may be indicated in limited situations. Younger patients with meniscal deficiency due to previous meniscectomy who have only early arthrosis, normal axial alignment, and a stable knee may currently considered appropriate candidates for meniscal transplantation.

[Capacity for sport and the sensorimotor system after stabilization of the shoulder in overhead athletes]. / Sportfähigkeit und Sensomotorik nach Schulterstabilisierung beim Uberkopfathleten.

The anterior capsulolaboral reconstruction according to Jobe is a modification of the Bankart operation, performing the capsular shift via a subscapularis-split approach avoiding any incision into the musculature. A total of 24 overhead athletes with posttraumatic, chronic anterior shoulder instability underwent surgery. Twenty-two patients were examined after an average follow-up of 2.8 +/- 0.7 years. On average, a Constant-Murley-Score of 93.7 +/- 5.3 points and an ASES-Score of 95.0 +/- 5.1 points were achieved. The relaxation rate was 9 %. The study demonstrated, that despite the good clinical results, only 12 out of 22 (55 %) of patients were able to return to their previous sports activity level. This relevant problem is in agreement with other similar studies so that it was further addressed by determination of proprioception and electromyographic muscle activity. Postoperatively, a persisting proprioceptive deficit as well as an altered EMG pattern was found with a significant reduction in activity of the deltoideus muscle on the operated side. The analysis of the data of each patient showed that there was a significant relation between the restitution of proprioception and ability to return to the previous sports activity level. In contrast, the relation between EMG pattern and full recovery to completely unrestricted shoulder function was not significant.

[The development and biomechanical testing of a femoral press fit fixation for hamstring tendons]. / Entwicklung und biomechanische Testung einer femoralen Press-fit-Fixierung für Semitendinosus-/Gracilissehnen.

PURPOSE: The purpose of this study was to investigate press fit femoral fixation of hamstring tendons and to compare the mechanical properties with press fit patellar tendon bone (PTB) fixation. METHODS: The PTB and hamstring tendons of 30 human cadavers (age: 55.8+/-18.0 years) were used as grafts. An outside-in press fit fixation with a knot in the semitendinosus and gracilis graft (SG-K) and an inside-out (SG-BI) and an outside-in fixation (SG-BO) with the tendons looped over a bone block were compared with a bone-patellar tendon (PT) press fit fixation in 30 bovine femora. The angle between the direction of force and bone tunnel was 60 degrees. The constructs underwent 20 cycles of loading between 60 and 260 N. Constructs were loaded until failure at a speed of 1 mm/sec. Graft fixation was analyzed in terms of maximum load to failure, stiffness and elongation during cyclic stretching. A video analysis of length changes was investigated. RESULTS: There was a significant difference in the maximum load to failure. The SG-BI fixation was inferior to the other three techniques (Mann-WhitneyU-test, P<0.01). There was no difference in stiffness between the techniques. Length changes of PT-fixation from the first to the fifth loading cycle were significantly smaller compared with all other groups (0.73+/-0.58 mm). There was no significant difference between the groups from the 15th to the 20th cycle of cyclic loading. CONCLUSIONS: Press fit fixation of hamstring grafts is technically challenging. However, pull-out forces for SG-O and SG-K were equivalent to BPT-graft fixation. Adequate preconditioning for all hamstring tendon press fit techniques is crucial.

Analysis of forces of ACL reconstructions at the tunnel entrance: is tunnel enlargement a biomechanical problem?

Bone tunnel enlargement is a common phenomenon following reconstruction of the anterior cruciate ligament (ACL). Biomechanical and biological factors have been reported as potential causes of this problem. However, there is no analysis of forces between the graft and bone, as the graft changes direction at the bone tunnel entrance. The purpose of this study was to study these 'redirecting forces'. Magnetic resonance images of 10 patients with an ACL reconstruction (age: 26+/-6.8 years) were used to determine the angle between graft and drill holes. Vector analysis was used to calculate the direction and magnitude of the perpendicular component of the force between the bone tunnel and the graft at the entrance of the bone tunnel. Force components were projected into the radiographically important sagittal and coronal planes. Tension of ACL reconstructions was recorded during passive knee motion in 10 cadaveric knee experiments (age: 28.9+/-10.6 years) and the tension multiplied with the force component for each plane. Results are reported for the coronal and sagittal planes, respectively: For -10 degrees of extension, the percentages of graft tension were determined to be 17+/-7 (max: 26; min: 7%) and 26+/-9 (max: 39; min: 16%) for the tibia. They were 59+/-6 (max: 66; min: 48%) and 99+/-1 (max: 1.00; min: 99%) for the femur. Force components were 14.68+/-6.54 and 25.73+/-12.96 N for the tibial tunnel. For the femoral tunnel, they were 52.48+/-19.03 and 90.77+/-32.06 N. Percentages of graft tension and force components were significantly higher for the femoral tunnel compared with the tibial tunnel. Moreover, in the sagittal direction, force components for the femoral tunnel were significantly higher compared with the coronal plane (Wilcoxon test, p < 0.01). The differences in force components calculated in this study corresponds with the amount of tunnel enlargement in the radiographic planes in the literature providing evidence that biomechanical forces play a key role in postoperative tunnel expansion.

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)]. / Indikations- und Durchführungsempfehlungen der Arbeitsgemeinschaft "Geweberegeneration und Gewebeersatz" zur Autologen Chondrozyten-Transplantation (ACT).

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

[Induction of bone tissue on different matrices: an in vitro and a in vivo pilot study in the SCID mouse]. / Induktion von Knochengewebe auf unterschiedlichen Matrizes: Eine In-vitro- und In-vivo-Pilotstudie in der SCID Maus.

AIM: Three resorbable biomaterials were evaluated regarding proliferation and osteogenic differentiation of human bone marrow stromal cells (BMSC) in vitro. In a second step, the new biomaterial, calcium-deficient hydroxyapatite (CDHA), was tested in a pilot in vivo study by subcutaneous implantation in the severe combined immunodeficiency (SCID) mouse. METHODS: CDHA, beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSC and cultured in osteogenic supplements for 3 weeks. In the pilot in vivo study, CDHA was seeded with BMSC and kept in osteogenic media for 2 weeks (group A) before subcutaneous implantation in 8 SCID mice for 3 and 8 weeks. In addition, CDHA seeded with BMSC without prior osteogenic induction (group B) and empty ceramics were implanted in each mouse. RESULTS: Total protein content and the values for specific alkaline phosphatase (ALP) increased significantly in vitro on all matrices, but no significant difference between the groups was noted. In the pilot in vivo study all ceramics were well penetrated by cells. After 8 weeks 2 of 4 samples in group B and 1 of 4 samples in group A revealed cells resembling hypertrophic chondrocytes. Specific ALP was higher in the group B (p = 0.012, Z = - 2.5) compared to empty ceramics. There were no significant differences between groups A and B. Differences between group A and the empty control did not become significant (p = 0.069, Z = - 1.8). CONCLUSION: All three matrices promoted BMSC proliferation and differentiation to osteogenic cells in vitro. Human BMSC on CDHA showed signs of osteogenic differentiation after subcutaneous implantation into SCID mice.

Effects of cyclic longitudinal mechanical strain and dexamethasone on osteogenic differentiation of human bone marrow stromal cells.

The aim of the study was to investigate the effect of cyclic mechanical strain on differentiation markers in the presence or absence of dexamethasone. Human bone marrow stromal cells (BMSC) from seven donors (32.5+/-6.2 years) were cultivated with (D+) or without (D-) dexamethasone. A cyclic mechanical strain with an elongation of 2% (D+2; D-2) or 8% (D+8; D-8) was applied for three days with a stimulation time of three times two hours each day. Levels of alkaline phosphatase (ALP) and osteocalcin (OC) were compared after time intervals of four and seven days. mRNA expression of Collagen I, III and Cbfa1 was investigated after one, four, and seven days. ALP levels were significantly increased in the D+8 group after four and seven days (147.1+/-6.3%; p<0.05 and 168.6+/-6,5%; p<0.03) and in the D-8 group after 7 days (197.4+/-10.4; p<0.04). Cyclic strain had a significant influence on ALP-secretion (F=7.5; p<0.01). In the D-8 group there was a significant increase in OC secretion after 4 days (140.9+/-12.5%; p<0.05).; p<0.01). The effect of stretching was significantly stronger than that of dexamethasone (F=17.2 vs. 1.8). Collagen I (Col I) expression was upregulated in D+8 cultures after 4 days (215.0+/-53.3 p<0.04) and after seven days (166.7+/-55.7; p<0.04). Collagen III (Col III) expression was upregulated in D+2 and D+8 cultures after 4 days (200.7+/-16.3 and 185.9+/-12.7; p<0.04) and after seven days (154.4+/-10.1 and 118.8+/-16.4; p<0.04). There was a significant increase of Cbfa1 expression in D+8 cultures at all investigated time intervals (day 1: 105.5+/-3.7%; day 4: 104.7+/-3.0%; day 7: 104.4+/-2.1%; p<0.03). Stretching (F=20.0; p<0.01) was a stronger contributor to Cbfa-1 expression than dexamethasone (F=12.1; p<0.01). Cyclical mechanical stimulation with 8% elongation increases ALP and OC levels and upregulates Col I and III synthesis and Cbfa1 expression. In the short term, cyclical stretching is a stronger differentiation factor than dexamethasone. Cyclical stretching and dexamethasone both enhance the osteogenic commitment of hBMSC.

Comparison of human bone marrow stromal cells seeded on calcium-deficient hydroxyapatite, beta-tricalcium phosphate and demineralized bone matrix.

The aim of this study was to compare three resorbable biomaterials regarding seeding efficacy with human bone marrow stromal cells (BMSCs), cell penetration into the matrix, cell proliferation and osteogenic differentiation. Calcium-deficient hydroxyapatite (CDHA), beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSCs and kept in human serum and osteogenic supplements for 3 weeks. Morphologic and biochemical evaluations were performed on day 1, 7, 14 and 21. The allograft DBM and CDHA exhibited both an excellent seeding efficacy while the performance of beta-TCP was lower when compared. The total protein content and the values for specific alkaline phosphatase (ALP) increased on all matrices and no significant difference was found for these two markers. BMSCs in monolayer had a significant increase of protein, but not of ALP. Osteocalcin (OC) values increased significantly higher for BMSC in cultures on DBM when compared to CDHA and beta-TCP. The OC levels decreased significantly in the BMSC monolayer culture. BMSCs were found inconsistently within the synthetic materials, whereas in DBM they were found more homogeneously distributed throughout the matrix. All three matrices promoted BMSC proliferation and differentiation to osteogenic cells. DBM allografts seem to be more favorable with respect to cell ingrowth tested by histology, and osteogenic differentiation ascertained by an increase of OC. CDHA with its high specific surface area showed more favorable properties than beta-TCP regarding reproducibility of the seeding efficacy.

[Femoral hemicallotasis with a half-segment for the reconstruction of a long partial bone defect]. / Die Hemikallotasis durch Halbschalensegmenttransport zur Rekonstruktion eines langstreckigen Femurschaftteildefekts.

The reconstruction of long bone defects is surgically demanding. This report describes the femoral hemicallotasis with a half-segment for the reconstruction of a 6-cm partial cortical defect which resulted from a posttraumatic osteitis. The indications for this modified Ilizarov method, advantages, potential problems as well as alternative methods are discussed.

Impingement pressure and tension forces of the anterior cruciate ligament.

This study examined the impingement behavior of the uninjured ACL and the impingement pressure and tension forces of the ACL to draw conclusions for ACL reconstructions. A miniature pressure sensor was inserted between the ACL and the intercondylar roof of 15 knees of human cadavers before and after a 3-mm notch roof resection (thickness of the sensor); tension of the ACL was measured after attaching the tibial insertion to a load cell. A long-arm goniometer was used to determine corresponding extension angles. The beginning of contact of the ACL with the notch roof was between -1 and -2 degrees of knee extension. Pressure for full passive extension was 855.6+/-279.1 and 346.4+/-287.7 kPa, and ACL tension averaged 101.9+/-38.4 N. Tension forces in passive hyperextension were higher than those detected when a 200-N Lachman test was performed (83.5+/-25.1 N). There was a significant correlation between extension capability and impingement pressure. Impingement of the ACL was detected in all knees. Full passive extension exerts biomechanical pressure and tension on the ACL. Tension forces of the ACL are higher in passive hyperextension than during a Lachman test with 200 N. The impingement behavior found for the uninjured ACL is simulated in an ACL reconstruction when the center tibial tunnel position is used.