Rupert Meller

Collagen type I hydrogel allows migration, proliferation, and osteogenic differentiation of rat bone marrow stromal cells

Hydrogels are potentially useful for many purposes in regenerative medicine including drug and growth factor delivery, as single scaffold for bone repair or as a filler of pores of another biomaterial in which host mesenchymal progenitor cells can migrate in and differentiate into matrix-producing osteoblasts. Collagen type I is of special interest as it is a very important and abundant natural matrix component. The purpose of this study was to investigate whether rat bone marrow stromal cells (rBMSCs) are able to adhere to, to survive, to proliferate and to migrate in collagen type I hydrogels and whether they can adopt an osteoblastic fate. rBMSCs were obtained from rat femora and plated on collagen type I hydrogels. Before harvest by day 7, 14, and 21, hydrogels were fluorescently labeled, cryo-cut and analyzed by fluorescent-based and laser scanning confocal microscopy to determine cell proliferation, migration, and viability. Osteogenic differentiation was determined by alkaline phosphatase activity. Collagen type I hydrogels allowed the attachment of rBMSCs to the hydrogel, their proliferation, and migration towards the inner part of the gel. rBMSCs started to differentiate into osteoblasts as determined by an increase in alkaline phosphatase activity after two weeks in culture. This study therefore suggests that collagen type I hydrogels could be useful for musculoskeletal regenerative therapies.

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.

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.

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.

Prognostic value of procalcitonin (PCT) and/or interleukin-6 (IL-6) plasma levels after multiple trauma for the development of multi organ dysfunction syndrome (MODS) or sepsis

UNLABELLED Despite recent advances in treatment of severe injured patients, e.g. due to damage control orthopaedics, multi organ dysfunction syndrome (MODS) and sepsis are major complications in daily practice. During one year 94 patients were prospectively collected. INCLUSION CRITERIA ISS 16, age 18-60 y, primary admission to our level-1 trauma center, survival > 48 hours after trauma. The development of MODS and sepsis were observed and different groups were formed (+/-). Demographic data revealed no significant differences between the subgroups. Comparing groups +MODS and -MODS significant differences on admission day were observed, when PCT showed first on day 2 after trauma differences. Regarding the development of sepsis PCT was advantageous to IL-6 showing significant higher plasma levels in group +sepsis from the first day after trauma. Serum levels of IL-6 and PCT could be useful in early identification of high risk patients to develop posttraumatic MODS. For sepsis PCT is the better prognostic factor.

Postnatal maturation of tendon, cruciate ligament, meniscus and articular cartilage: a histological study in sheep.

Orthopaedic basic science data on immature skeletons are rare in the literature. Since the number of knee injuries in young humans is steadily increasing, studies on immature animals such as sheep, which can be used as model systems are becoming more and more important. However, no baseline data are available on physiologic and morphologic changes during growth in the relevant tissues. In the present study, histomorphometric changes in the tendon of the musculus flexor digitalis superficialis, the cranial cruciate ligament, the medial meniscus and the articular cartilage of the medial femoral condyle were identified in sheep between the ages of 1 and 40 weeks postnatally. Profound changes in tissue composition during growth could be observed. A high cellularity in the early postnatal period decreases to a constant lower level after 18 weeks. Similar changes during postnatal growth could be observed for blood vessel density. Also, staining of alpha-smooth muscle actin (SMA) and vascular endothelial growth factor (VEGF) steadily decreased. In contrast, the number of components of extracellular matrix steadily increased in all tissues. The age of 18 weeks seems to be a threshold after which the tissue composition of the observed structures remains constant in this species.

Histologic and biomechanical analysis of anterior cruciate ligament graft to bone healing in skeletally immature sheep.

PURPOSE It was our aim to establish an animal model and to investigate the tendon graft-to-bone and physis healing process in skeletally immature sheep after reconstruction of the anterior cruciate ligament (ACL). METHODS Thirty-two immature sheep aged 4 months underwent a fully transphyseal ACL reconstruction by use of a soft-tissue graft. The animals were subsequently killed after 3, 6, 12, and 24 weeks and analyzed histologically and biomechanically. RESULTS There was a transient hypertrophy of the physis tissue at the passing site of the graft. Anchoring Sharpey-like fibers evolved as early as 3 weeks after surgery. A strong expression of collagen III messenger ribonucleic acid within the first 6 weeks preceded this anchoring process. The maximum load to failure of the tendon graft in the reconstructed knees initially decreased to 37.8 +/- 17.8 N after 3 weeks and was restored to 522.9 +/- 113 N after 24 weeks. Tendon graft stiffness was restored to 86% when compared with the control knees. CONCLUSIONS The early anchoring by Sharpey fibers was found at 3 weeks with continued maturation to 24 weeks. This development of anchoring fibers corresponded to that of biomechanical strength, starting with 5% of the normal knee at 3 weeks and then 15.2% at 6 weeks, 41.2% at 12 weeks, and 69% at 24 weeks. Tendon graft-to-bone and physis healing in skeletally immature sheep is further characterized by a transient hypertrophy of the physis cartilage. The physis recovers well from the trauma of drilling and placement of a soft-tissue graft. The early development of Sharpey-like fibers results in a solid integration of the graft into bone in a timely manner. CLINICAL RELEVANCE ACL reconstruction in skeletally immature individuals is still controversial. This study describes in detail the histologic and biomechanical stages of tendon graft healing to the bone and physis. These data enrich the existing knowledge of previous studies in adult sheep and may provide a basis for further research in the controversial field of ACL reconstruction during growth.

Arthroscopic Arthrolysis for Recalcitrant Frozen Shoulder: A Lateral Approach

PURPOSE The purpose of this study was to evaluate a new all-arthroscopic technique in the management of recalcitrant globally stiff frozen shoulders. This adopts an initial extra-articular approach followed by intra-articular entry to perform a 360° capsular release. METHODS Ten patients with global adhesive capsulitis were prospectively evaluated. All patients had not improved after undergoing a minimum of 6 months of physiotherapy, and 5 received intra-articular injections of steroids. The mean age was 47 years (range, 33 to 56 years). Patients were examined preoperatively and postoperatively for range of motion. A Constant score and visual analog scale score for pain were recorded. We described an all-arthroscopic technique by entering the subacromial space laterally and opening the rotator interval from the outside in, followed by a complete 360° capsular release and biceps tenotomy. RESULTS The mean follow-up was 42 months (range, 18 to 90 months), and the mean Constant score improved from 21 to 72 (P < .01). Preoperative abduction improved from a mean of 40° to 165°, elevation improved from 55° to 175°, and external rotation improved from 6° to 58°. The visual analog scale pain score improved from 7 to 1.6, and all patients reported an excellent outcome after surgery. There were no complications particularly regarding axillary nerve injury, fracture, or infection. CONCLUSIONS This study shows a combined extra-articular and intra-articular approach that is controlled and anatomic and achieves excellent results that were maintained at the midterm. The technique permits anatomic debridement of the rotator interval, enabling excellent intra-articular access, a circumferential capsular release, and biceps tenotomy. There were no complications, and no manipulations were required, which pose a risk of creating soft-tissue lesions, fractures, or dislocations. We recommend this 360° capsular release technique for releasing globally stiff shoulders where the surgeon is experienced in arthroscopy.

Tunnel Widening After Anterior Cruciate Ligament Reconstruction: An Experimental Study in Sheep

Background A common clinical concern after anterior cruciate ligament reconstruction is the expansion of the bone tunnels as seen radiographically. The etiology and clinical relevance of this phenomenon remain unclear. Hypothesis Tunnel widening results in an increased anteroposterior translation, and there are specific histologic changes due to osteoclastic bone resorption associated with this phenomenon. Study Design Controlled laboratory study. Methods Thirty sheep (age, 4 months) underwent an anterior cruciate ligament reconstruction using a soft tissue graft. Graft fixation was achieved using the EndoButton and Suture Washer. Six animals each were sacrificed at 0, 3, 6, 12, and 24 weeks after surgery. Each anterior cruciate ligament–reconstructed knee was examined by computed tomography. Anteroposterior translation was determined using a universal force-moment sensor robot. The bone surrounding the tunnel was evaluated histologically. Results The prevalence of tunnel enlargement on the femoral side was 77.3%. Animals with tunnel widening did not demonstrate increased anteroposterior translation. Widening of the femoral tunnel was significantly associated with a higher stiffness of the graft (P <. 05) and hypertrophy of the graft throughout the remodeling process. The histologic evaluation of the bone tunnel walls demonstrated an increase of bone volume in animals with tunnel enlargement. No statistically significant correlation could be found between the number of osteoclasts and the presence of tunnel widening. Conclusion In this large animal model of anterior cruciate ligament reconstruction, animals with significant tunnel widening did not suffer increased anteroposterior translation. Tunnel widening was associated with a high stiffness of the graft, graft hypertrophy, and an increase in bone volume of the tunnel wall. Clinical Relevance The present data correspond to the current opinion in humans that tunnel widening is not associated with knee instability. Further research is needed to understand the role of graft stiffness, graft hypertrophy, and the increase in bone volume in this phenomenon.

Superior Achilles Tendon Microcirculation in Tendinopathy Among Symptomatic Female Versus Male Patients

Background Higher estrogen levels in women seem to play a role regarding an increased ligament and tendon injury rate among women. However, gender differences of tendon microcirculation have not yet been reported. Hypothesis Female patients suffering Achilles tendinopathy have worse tendon and paratendon microcirculation than symptomatic male patients. Study Design Cross-sectional study; Level of evidence, 2. Methods A total of 139 Achilles tendinopathy patients (58 women, 81 men) were analyzed according to their gender for tendon and paratendon microcirculation by mapping at 12 positions (4 tendons, 8 paratendons) in each limb. Tendon and paratendon capillary blood flow, oxygen saturation, and postcapillary venous filling pressures were measured at 2-mm and 8-mm tissue depths. Results Symptomatic women had similarly elevated tendon capillary blood flow as men at 4 Achilles tendon positions. However, distal medial (83 ± 40 vs 105 ± 74, P < .05) and lateral (98 ± 49 vs 121 ± 74) paratendon capillary blood flow were significantly lower among men. Symptomatic female patients had superior tendon and paratendon oxygen saturation at 11 of 12 positions (P < .05) as well as reduced postcapillary venous filling pressures at the proximal midportion tendon (55 ± 17 vs 63 ± 20, P < .05) and paratendon (69 ± 19 vs 77 ± 26) location. Pain level was not different between female (5.3 ± 2.2) and male patients (5.4 ± 2, P = .864). Female patients had significantly higher Foot and Ankle Outcome Sports Scores (71 ± 22 vs 64 ± 23 in the men, P = .041), while 4 out of 5 other Foot and Ankle Outcome Score items were not different. Conclusion Symptomatic female patients have similarly elevated tendon capillary blood flow compared with symptomatic male patients suffering Achilles tendinopathy, but superior tendon and paratendon oxygen saturations and reduced postcapillary venous filling pressures indicate better tendon and paratendon Achilles tendon microcirculation in women.