Johannes Dominik Bastian

Hypoxic expansion promotes the chondrogenic potential of articular chondrocytes.

For cell‐based cartilage repair strategies, an ex vivo expansion phase is required to obtain sufficient numbers of cells needed for therapy. Although recent reports demonstrated the central role of oxygen for the function and differentiation of chondrocytes, a beneficial effect of low oxygen concentrations during the expansion of the cells to further improve their chondrogenic capacity has not been investigated. Therefore, freshly harvested bovine articular chondrocytes were grown in two‐dimensional monolayer cultures at 1.5% and 21% O2 and redifferentiation was subsequently induced in three‐dimensional micromass cultures at 1.5%, 5%, and 21% O2. Cells expanded at 1.5% O2 were characterized by low citrate synthase (aerobic energy metabolism)—and high LDH (anaerobic energy metabolism)—activities, suggesting an anaerobic energy metabolism. Collagen type II mRNA was twofold higher in cells expanded at 1.5% as compared to expansion at 21% O2. Micromass cultures grown at 21% O2 showed up to a twofold increase in the tissue content of glycosaminoglycans when formed with cells expanded at 1.5% instead of 21% O2. However, no differences in the levels of transcripts and in the staining for collagen type II protein were observed in these micromass cultures. Hypoxia (1.5% and 5% O2) applied during micromass cultures gave rise to tissues with low contents of glycosaminoglycans only. In vivo, the chondrocytes are adapted to a hypoxic environment. Taking this into account, by applying 1.5% O2 in the expansion phase in the course of cell‐based cartilage repair strategies, may result in a repair tissue with higher quality by increasing the content of glycosaminoglycans.

Less invasive lumbopelvic stabilization of posterior pelvic ring instability: technique and preliminary results

BACKGROUND Lumbopelvic distraction stabilization with (triangular osteosynthesis) or without additional iliosacral screw allows anatomic reduction of the posterior pelvic ring after severely displaced sacral fractures, correction or resection osteotomies of malunions, respectively, septic sacroiliitis and permits early weight bearing. However, this technique is complicated by wound necrosis or infection in up to 20% to 30%. We describe our experience with a less invasive technique. METHODS The presented technique was performed in a consecutive series (December 2006 to October 2009) of 10 patients (mean age: 47 years, 23-85 years; 5 men). Posterior pelvic ring instability was due to severely displaced vertical shear injuries of type C1/3.3 (6/10), delayed union 2 months after bilateral C 3.3 (1/10) fractures, and malunion 6 months after unilateral vertical shear injuries C 1.3 (1/10), occurred after resection of the iliosacral joint for treatment of spinal tuberculosis (1/10) or was related to a early loss of reduction of a type C 1.3 pelvic ring injury (1/10). Patients were prospectively evaluated for the occurrence of wound-healing disorders with a median follow-up of 9 months (range, 5-33). RESULTS The median duration of the hospital stay was 35 days (range, 16-57). One 85-year-old patient died 1 year after lumbopelvic stabilization for reasons unrelated to the surgical treatment. In the postoperative course, no wound-healing disorders or infections were observed, and in all cases, the soft tissues and the bone healed. Five of 10 removal of the lumbopelvic fixation was performed at a median of 8 months (range, 8-20) after stabilization to prevent sacroiliac arthrodesis or to mobilize the lumbar spine after the unilateral lumbopelvic stabilization. The indication for hardware removal was not related to wound disorders. CONCLUSION The presented technique respects the lumbar anatomy and provides the access required for lumbopelvic stabilization, while having the potential to decrease or even prevent postoperative wound disorders if combined with a polyaxial low-profile system. The low number of cases presented may, however, limit the relevance of the conclusions in cases of severe Morell-Lavallé lesions with skin disorders.

Computer-Assisted Femoral Head-Neck Osteochondroplasty Using a Surgical Milling Device An In Vitro Accuracy Study

Surgical navigation might increase the safety of osteochondroplasty procedures in patients with femoroacetabular impingement. Feasibility and accuracy of navigation of a surgical reaming device were assessed. Three-dimensional models of 18 identical sawbone femora and 5 cadaver hips were created. Custom software was used to plan and perform repeated computer-assisted osteochondroplasty procedures using a navigated burr. Postoperative 3-dimensional models were created and compared with the preoperative models. A Bland-Altmann analysis assessing α angle and offset ratio accuracy showed even distribution along the zero line with narrow confidence intervals. No differences in α angle and offset ratio accuracy (P = 0.486 and P = 0.2) were detected between both observers. Planning and conduction of navigated osteochondroplasty using a surgical reaming device is feasible and accurate.

Surgical hip dislocation for osteochondral transplantation as a salvage procedure for a femoral head impaction fracture.

Obturator anterior hip dislocation is very rare. Poor results are described in patients with additional large transchondral fractures and treatment of these injuries remains challenging. Appropriate treatment recommendations are missing in the literature. This case report introduces surgical hip dislocation for osteochondral autograft transplantation with graft harvest from the nonweightbearing area of the head-neck junction as a salvage procedure in a large femoral head defect. We report the treatment and outcome of a 48-year-old man who sustained an anterior dislocation of the left hip after a motorcycle accident. After initial closed reduction in the emergency room, imaging analysis revealed a large osteochondral defect of the femoral head within the weightbearing area (10 × 20 mm, depth: 5 mm). The hip was exposed with a surgical hip dislocation using a trochanteric osteotomy. An osteochondral autograft was harvested from a nonweightbearing area of the femoral head and transferred into the defect. The patient was prospectively examined clinically and radiologically. Two years postoperatively, the patient was free of pain and complaints. The function of the injured hip was comparable to that of the contralateral, healthy hip and showed satisfying radiologic results. Surgical hip dislocation with a trochanteric flip osteotomy is a simple, one-step technique that allows full inspection of the hip to treat osteochondral femoral defects by osteochondral transplantation. The presented technique, used as a salvage procedure in a large femoral head defect, yielded good clinical and satisfying radiologic outcomes at the midterm.

Rationales for the Bernese approaches in acetabular surgery

PurposeTo present two new approaches to acetabular surgery that were established in Berne, and which aim at enhanced visualization and anatomical reconstruction of acetabular fractures.MethodThe trochanteric flip osteotomy allows for surgical hip dislocation, and was introduced as a posterior approach for acetabular fracture management involving the posterior column and wall. For acetabular fractures predominantly involving the anterior column and the quadrilateral plate, the Pararectus approach is described.ResultsFull exposure of the hip joint, as provided by the trochanteric flip osteotomy, facilitates anatomical reduction of acetabular or femoral head fractures and safe positioning of the anterior column screw in transverse or T-shaped fractures. Additionally, the approach enables osteochondral transplantation as a salvage procedure for severe chondral femoral head damage and osteoplasty of an associated inadequate offset at the femoral head–neck junction. The Pararectus approach allows anatomical restoration with minimal access morbidity, and combines advantages of the ilioinguinal and modified Stoppa approaches.ConclusionsUtilization of the trochanteric flip osteotomy eases visualization of the superior aspect of the acetabulum, and enables the evaluation and treatment of chondral lesions of the femoral head or acetabulum and labral tears. Displaced fractures of the anterior column with a medialized quadrilateral plate can be addressed successfully through the Pararectus approach, in which surgical access is associated with minimal morbidity. However, long-term results following the two presented Bernese approaches are needed to confirm that in the treatment of complex acetabular fractures the rate of poor results in almost one-third of all cases (as currently yielded using traditional approaches) might be reduced by the utilization of the presented novel approaches.

Anterior approaches to the acetabulum

Since the 1960s the ilioinguinal approach by Letournel with the three anatomic windows has been successfully established for the treatment of acetabular fractures involving predominantly the anterior column. The previous standard approach, the iliofemoral approach by Smith-Petersen, is still used for the therapy of anterior wall or isolated femoral head fractures. The increase in acetabular fractures in the elderly with lateral compression fractures after lateral falls, characterized by medial displacement of the quadrilateral plate and superomedial dome impaction, led to the use of the intrapelvic modified Stoppa approach with or without the first window of the ilioinguinal approach in the 1990s. To combine the advantages of the second and third windows of the ilioinguinal approach and the medial view of the modified Stoppa approach the Berne research group recently introduced the pararectus approach in acetabular surgery, which can be used as a less invasive acetabular surgical (LIAS) technique especially in the elderly.ZusammenfassungSeit den 1960er Jahren hat sich zur Versorgung von Acetabulumfrakturen mit der Hauptdislokation im vorderen Pfeiler der ilioinguinale Zugang nach Letournel mit den drei anatomischen Fenstern bewährt. Der frühere Standardzugang, der iliofemorale Zugang nach Smith-Petersen, hat seine Bedeutung noch bei Vorderwandfrakturen oder isolierten Femurkopffrakturen. Durch den Anstieg von Acetabulumfrakturen im Alter mit lateralen Kompressionsfrakturen nach seitlichem Sturz, gekennzeichnet durch die mediale Dislokation der quadrilateralen Fläche und die superomediale Domimpression, hat sich in den 1990er Jahren der intrapelvine modifizierte Stoppa-Zugang mit oder ohne Eröffnung des 1. Fensters des ilioinguinalen Zugangs etabliert. Um die Vorteile der 2. und 3. Fenster des ilioinguinalen und die mediale Sicht beim modifizierten Stoppa-Zugang zu kombinieren, hat die Berner Arbeitsgruppe kürzlich den Pararectus-Zugang für die Acetabulumchirurgie eingeführt, der als weniger invasiver Zugang mit kleinen Inzisionen speziell bei alten Patienten einsetzbar ist.AbstractSince the 1960s the ilioinguinal approach by Letournel with the three anatomic windows has been successfully established for the treatment of acetabular fractures involving predominantly the anterior column. The previous standard approach, the iliofemoral approach by Smith-Petersen, is still used for the therapy of anterior wall or isolated femoral head fractures. The increase in acetabular fractures in the elderly with lateral compression fractures after lateral falls, characterized by medial displacement of the quadrilateral plate and superomedial dome impaction, led to the use of the intrapelvic modified Stoppa approach with or without the first window of the ilioinguinal approach in the 1990s. To combine the advantages of the second and third windows of the ilioinguinal approach and the medial view of the modified Stoppa approach the Berne research group recently introduced the pararectus approach in acetabular surgery, which can be used as a less invasive acetabular surgical (LIAS) technique especially in the elderly.

Surgical exposures and options for instrumentation in acetabular fracture fixation: Pararectus approach versus the modified Stoppa

BACKGROUND As an alternative to the modified Stoppa approach, the Pararectus approach is used clinically for treatment of acetabular fractures involving the anterior column. The current study assessed the surgical exposure and the options for instrumentation using both of these approaches. METHODS Surgical dissections were conducted on five human cadavers (all male, mean age 88 years (82-97)) using the modified Stoppa and the Pararectus approach, with the same skin incision length (10cm). Distal boundaries of the exposed bony surfaces were marked using a chisel. After removal of all soft-tissues, distances from the boundaries in the false and true pelvis were measured with reference to the pelvic brim. The exposed bone was coloured and calibrated digital images of each inner hemipelvis were taken. The amount of exposed surface using both approaches was assessed and represented as a percentage of the total bony surface of each hemipelvis. For instrumentation, a suprapectineal quadrilateral buttress plate was used. Screw lengths were documented, and three-dimensional CT reconstructions were performed to assess screw trajectories qualitatively. Wilcoxons signed rank test for paired groups was used (level of significance: p<0.05). RESULTS After utilization of the Pararectus approach, the distances from the farthest boundaries of exposed bone towards the pelvic brim were significantly higher in the false but not the true pelvis, compared to the modified Stoppa approach. The percentage (mean±SD) of exposed bone accessible after utilizing the Pararectus approach was 42±8%, compared to 29±6% using the modified Stoppa (p=0.011). In cadavers exposed by the Pararectus approach, screws placed for posterior fixation and as a posterior column screw were longer by factor 1.8 and 2.1, respectively (p<0.05), and screws could be placed more posteromedial towards the posterior inferior iliac spine or in line with the posterior column directed towards the ischial tuberosity. CONCLUSION Compared to the modified Stoppa, the Pararectus approach facilitates a greater surgical access in the false pelvis, provides versatility for fracture fixation in the posterior pelvic ring and allows for the option to extend the approach without a new incision.

Chondrocytes within Osteochondral Grafts Are More Resistant than Osteoblasts to Tissue Culture at 37°C

ABSTRACT It is proposed that an ideal osteochondral allograft for cartilage repair consists of a devitalized bone but functional cartilage. The different modes of nutrient supply in vivo for bone (vascular support) and cartilage (diffusion) suggest that a modulation of storage conditions could differentially affect the respective cells, resulting in the proposed allograft. For this purpose, osteochondral tissues from porcine humeral heads were either cultured at 37°C for up to 24 hr or stored at 4°C for 24 hr, the temperature at which osteochondral allografts are routinely stored. Functionality of the cells was assessed by in situ hybridization for transcripts encoding collagen types I and II. At 37°C, a time-dependent significant reduction of the bone surface covered with functional cells was observed with only 5% ± 5% coverage left at 24 hr compared with 41% ± 10% at 0 hr. Similarly, cartilage area containing functional cells was significantly reduced from 84% ± 7% at 0 hr to 70% ± 3% after 24 hr. After 24 hr at 4°C, a significantly reduced amount of functional cells covering bone surfaces was observed (27% ± 5%) but not of cells within the cartilage (79% ± 8%). In the applied experimental setup, bone cells were more affected by tissue culture at 37°C than cartilage cells. Even though chondrocytes appear to be more sensitive to 37°C than to 4°C, the substantially reduced amount of functional bone cells at 37°C warrants further investigation of whether a preincubation of osteochondral allografts at 37°C—prior to regular storage at 4°C—might result in an optimized osteochondral allograft with devitalized bone but viable cartilage.

Surgical dislocation of the hip for a locked traumatic posterior dislocation with associated femoral neck and acetabular fractures

Traumatic posterior dislocation of the hip associated with a fracture of the posterior acetabular wall and of the neck of the femur is a rare injury. A 29-year-old man presented at a level 1 trauma centre with a locked posterior dislocation of the right hip, with fractures of the femoral neck and the posterior wall of the acetabulum after a bicycle accident. An attempted closed reduction had failed. This case report describes in detail the surgical management and the clinical and radiological outcome. Open reduction and fixation with preservation of the intact retinaculum was undertaken within five hours of injury with surgical dislocation of the hip and a trochanteric osteotomy. Two years after operation the function of the injured hip was good. Plain radiographs and MR scans showed early signs of osteoarthritis with some loss of joint space but no evidence of avascular necrosis. The patient had begun skiing and hiking again. The combination of fractures of the neck of the femur and of the posterior wall of the acetabulum hampers closed reduction of a posterior dislocation of the hip. Surgical dislocation of the hip with trochanteric flip osteotomy allows controlled open reduction of the fractures, with inspection of the hip joint and preservation of the vascular supply.

Differential response of porcine osteoblasts and chondrocytes in cell or tissue culture after 5-aminolevulinic acid-based photodynamic therapy

OBJECTIVE Outcome in osteochondral allografting is limited by the immunological incompatibility of the grafted tissue. Based on a resistance of chondrocytes to photodynamic therapy in cell culture it is proposed that 5-aminolevulinic acid-based photodynamic therapy (5-ALA-PDT) might be used to inactivate bone while maintaining viability of chondrocytes and thus immunomodulate bone selectively. METHODS Chondrocytes and osteoblasts from porcine humeral heads were either isolated (cell culture) or treated in situ (tissue culture). To quantify cytotoxic effects of 5-ALA-PDT (0-20 J/cm(2), 100 mW/cm(2)) an (3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide) (MTT)-assay was used in cell culture and in situ hybridization in tissue culture to assess metabolic active cells (functional osteoblasts: col alpha(1)(I) mRNA, functional chondrocytes: col alpha(1)(II) mRNA). RESULTS In cell culture, survival after 5-ALA-PDT was significantly higher for chondrocytes (5 J/cm(2): 87+/-12% compared to untreated cells) than for osteoblasts (5J/cm(2): 12+/-11%). In tissue culture, the percentage of functional chondrocytes in cartilage showed a decrease after 5-ALA-PDT (direct fixation: 92+/-2%, 20 J/cm(2): 35+/-15%; P<0.0001). A significant decrease in the percentage of bone surfaces covered by functional osteoblasts was observed in freshly harvested (31+/-3%) compared to untreated tissues maintained in culture (11+/-4%, P<0.0001), with no further decrease after 5-ALA-PDT. CONCLUSION Chondrocytes were more resistant to 5-ALA-PDT than osteoblasts in cell culture, while in tissue culture a loss of functional chondrocytes was observed after 5-ALA-PDT. Since osteoblasts - but not chondrocytes - were sensitive to the tissue culture conditions, devitalized bone with functional cartilage might already be achieved by applying specific tissue culture conditions even without 5-ALA-PDT.