Angular stable locking in a novel intramedullary nail improves construct stability in a distal tibia fracture model.

INTRODUCTION: Intramedullary nails are frequently used for treatment of unstable distal tibia fractures. However, insufficient fixation of the distal fragment could result in delayed healing, malunion or nonunion. Recently, a novel concept for angular stable nailing was developed that maintains the principle of relative stability and introduces improvements expected to reduce nail toggling, screw migration and secondary loss of reduction. The aim of this study was to investigate the biomechanical competence of the novel angular stable intramedullary nail concept for treatment of unstable distal tibia fractures, compared to a conventional nail locking in a human cadaveric model under dynamic loading. MATERIALS AND METHODS: Ten pairs of fresh-frozen human cadaveric tibiae with a simulated AO/OTA 42-A3.1 fracture were assigned to 2 groups for reamed intramedullary nailing using either a conventional (non-angular stable) Expert Tibia Nail (ETN) with 3 distal screws or the novel Tibia Nail Advanced (TNA) system with 2 distal angular stable locking low-profile retaining screws. The specimens were biomechanically tested under conditions including initial quasi-static loading, followed by progressively increasing combined cyclic axial and torsional loading in internal rotation until failure of the bone-implant construct. Both tests were monitored by means of motion tracking. RESULTS: Initial nail toggling of the distal tibia fragment in varus and flexion under axial loading was lower for TNA compared to ETN, being significant in flexion, P = 0.91 and P = 0.03. After 5000 cycles, interfragmentary movements in terms of varus, flexion, internal rotation, axial displacement, and shear displacement at the fracture site were all lower for TNA compared to ETN, with flexion and shear displacement being significant, P = 0.14, P = 0.04, P = 0.25, P = 0.11 and P = 0.04, respectively. Cycles to failure until both interfragmentary 5° varus and 5° flexion were significantly higher for TNA compared to ETN, P = 0.04. CONCLUSION: From a biomechanical perspective, the novel angular stable intramedullary nail concept provides increased construct stability and maintains it over time while reducing the number of required locking screws without impeding the flexibility of the nail itself and resists better towards loss of reduction under dynamic loading, compared to conventional locking in intramedullary nailed unstable distal tibia fractures.

[Antegrade and retrograde nailing of humeral shaft fractures]. / Antegrade und retrograde Nagelung von Humerusschaftfrakturen.

OBJECTIVE: Restoring humeral shaft alignment using direct or indirect reduction techniques with subsequent intramedullary stabilisation with an antegrade or retrograde inserted humeral nail. Achieving osseous union and restoration of painfree upper arm function. INDICATIONS: Antegrade: Humerus shaft fractures located in the proximal 2/3 of the humerus. Combined fractures of the ipsilateral proximal humerus and humerus shaft. Segmental fractures of the humerus shaft. Pathological fractures or osteolysis (palliative indication). Retrograde: Humerus shaft fractures located in the middle and distal part of the humerus diaphysis. CONTRAINDICATIONS: Acute infection in the area of the surgical approach; polytrauma with acute life-threatening haemodynamic instability. SURGICAL TECHNIQUE: In the antegrade technique: anterolateral acromial approach. Determination of the correct nail entry point on the humeral head. Incision of the rotator cuff with longitudinal split of the fibres. Closed or semi-open fracture reduction. Insertion of an intramedullary nail with an appropriate length and diameter. Interfragmentary compression when required. Proximal and distal static interlocking with at least 2 bolts on each side. In the retrograde technique, the nail is inserted after opening of the medullary cavity directly proximal to the olecranon fossa. POSTOPERATIVE MANAGEMENT: Functional aftertreatment with passive and active-assisted exercises during the first 3 weeks. Subsequent active exercises avoiding forced rotation of the arm. Sports activities and severe stress are avoided for 3 months. Postoperative radiographs as well as after 2, 6 and 12 weeks. RESULTS: Very good healing results with excellent clinical and radiological healing are achieved in more than 90% of cases after both antegrade and retrograde nailing. Intraoperative problems that have been reported in up to 40% of cases occurred mainly with former generation nails or were attributable to technical errors. Correspondingly, with the closed reduction technique postoperative infections are rare (< 3%). Undesirable distraction at the fracture site is successfully corrected by intraoperative interfragmentary compression. Success and complication rates after intramedullary nailing and plate fixation are not significantly different. Functional shoulder-related problems may occur after antegrade nailing, whereas elbow problems may occur after retrograde nailing.

Evaluation of the reduction, tightening and gripping performance of an innovative set screw technology for instrumented posterior lumbar fusion: A biomechanical study.

BACKGROUND: Instrumented posterior lumbar fusion with top-loading pedicle screw systems (PSS) requires fully tightened set screws to achieve a secure fixation and symmetric load condition. This assumes a complete reduction of the rod by 90°, which is not always attainable in situ, especially under constraint. The objective of this work is to compare the mechanical performance of different innovative set screw technologies, which should improve the tightening process. HYPOTHESIS: The hypotheses of the study are that modifications to the screw and screwdriver unit can (1) improve the quality of set screw tightening and (2) increase the axial gripping capacity of the construct. MATERIALS AND METHODS: The four set screw technologies under investigation include a standard set screw with a flat surface (F-S; control group), a set screw with a convex surface (C-S) and a shaft tip method screwdriver used in combination with both flat (F-STM) and convex set screws (C-STM). The quality of set screw tightening is categorized as follows: failed=the rod is not completely reduced; reduced=the rod is successfully reduced but the set screw is not correctly fixed; good=remaining cases. An axial gripping capacity test is performed by a universal testing machine (Instron®) with a force capacity of 5kN. RESULTS: Regarding the quality of set screw tightening, comparisons between F-S vs. F-STM, F-S vs. C-STM and between C-S vs. C-STM show statistically significant differences (p<0.001). The axial gripping capacity test shows mean gripping forces of 1223N (STD 331) in the F-STM group and of 1724N (STD 168) in the C-STM group with statistically significant differences between both groups (p=0.003). DISCUSSION: Several biomechanical and clinical case studies have identified possible effects of misaligned rod-screw interfaces such as screw pull-out during rod reduction, screw loosening, screw or rod breakage, misalignment, adjacent segment degeneration and worsening of the clinical outcome. C-STM-technology thus supports controlled fixation in the sense of applying appropriate forces for correction or fixation during PSS assembly as well as friction-reduced final alignment and tightening with the aim to reduce implant loosening, hardware failure and reoperations, while respecting anatomical and biomechanical balance.

Safety and efficacy of 2D-fluoroscopy-based iliosacral screw osteosynthesis: results of a retrospective monocentric study.

INTRODUCTION: Iliosacral screw osteosynthesis is a well-accepted procedure for stabilization of sacral fractures and iliosacral (fracture) dislocations. MATERIALS AND METHODS: In this monocentric study, safety and efficacy of conventional 2D-fluoroscopic-guided iliosacral screw insertion were evaluated. RESULTS: During a 10-year period (2005-2014), 98 patients between the age of 18 and 65 years received 207 iliosacral screws in 101 procedures. Average patient age was 43.2 years. There were 46 Type B and 40 Type C injuries in the AO/OTA classification, nine patients had a fragility fracture of the pelvis. In three patients, primary radiological data were missing. The indication for surgical treatment was a sacral fracture in 97 patients, a pure iliosacral dislocation in 37 patients and a fracture-dislocation in 31 patients. 70 procedures were performed with the patient in supine position, 31 with the patient in prone position. Surgery was done in a minimal-invasive technique in 76 patients, in 22 patients an open reduction was necessary before screw insertion. 81 patients received a unilateral, 17 patients a bilateral screw osteosynthesis. 199 screws were inserted in S1, only eight screws in S2. 65 patients received two screws unilaterally, ten patients two screws bilaterally. There were no vascular or neurologic complications. During in-hospital stay, there were seven complications, which needed 12 operative revisions: three wound infections, two hematomas, one screw malalignment and one early screw loosening. In 28 patients with 56 iliosacral screws, a pelvic CT-scan was performed during follow-up. A penetration of a cortical layer was diagnosed in 20 of these screws. All penetrations were seen in double screw osteosynthesis of S1. In none of the patients, complaints could be explained by the malalignment of these screws. Five operative revisions were performed during follow-up: two for screw loosening, two for fracture healing problems and one for screw malalignment. Metal removal was performed in 39 patients with 75 screws. 2D-fluoroscopic-guided iliosacral screw osteosynthesis is a safe and efficient procedure in clinical practice. DISCUSSION: A thorough preoperative evaluation of the morphology of the upper sacrum and careful operative procedure are indispensable. Fluoroscopic views in AP, lateral, inlet and outlet must allow recognition of all anatomical landmarks. The indication for double screw osteosynthesis in S1 should be taken with caution. Screw malalignments do not inevitably correlate with complaints.

Suprapatellar nailing of fractures of the tibia.

OBJECTIVE: Intramedullary nailing of tibia fractures via a suprapatellar, transarticular approach with the knee joint in 20-30° of flexion and the use of specific protection tubes to preserve intra-articular structures. INDICATIONS: Extra-articular fractures of the proximal tibia; simple and comminuted fractures of the tibia diaphysis; segmental diaphyseal fractures of the tibia; extra-articular fractures of the distal tibia and fractures with simple intra-articular distal extension; floating knee injuries. CONTRAINDICATIONS: Gustilo grade 3C open fractures of the tibia; severe soft tissue laceration, contamination or infection in the suprapatellar area; ipsilateral knee joint prosthesis; knee arthrodesis; implants blocking the nail entry point. SURGICAL TECHNIQUE: Via a suprapatellar, transarticular approach an intramedullary tibia nail is inserted after anatomical reposition of the tibial fracture with the knee joint in 20-30° of flexion. Use of specific protection tubes to preserve intra-articular structures. The proximal and distal locking configuration depends upon the specific fracture characteristics. RESULTS: In all, 61 patients underwent suprapatellar tibia nailing and were under follow-up at least until fracture union. Twelve patients suffered from an open fracture. A total of 17 patients had a distal third fracture, 8 sustained a proximal third fracture and 36 had a shaft fracture. Follow-up focused on patients with distal fractures; 6/17 patients sustained open fractures. Average time to union was 9 weeks. One fracture did not heal and required exchange nailing. Two patients complained about anterior knee pain. Functionally, full range of motion was regained in all patients.

Stabilization of fatigue fractures of the dorsal pelvis with a trans-sacral bar. Operative technique and outcome.

INTRODUCTION: Due to ageing of our population the number of fatigue fractures of the pelvic ring is steadily growing. These fractures are often treated with bed rest but may result in a disabling immobility with severe pain. An operative treatment is an option in these cases. The aim of operative treatment is bony healing obtained by stable fixation giving back to the patient's previous mobility. Optimal surgical treatment is currently under debate. Sacroiliac screw fixation and sacroplasty are used for stabilization of the dorsal pelvis. Due to the technique and the low density of spongious sacral bone, no or only low compression in the fracture site is obtained, which may inhibit bony healing. The trans-sacral bar compression osteosynthesis is presented as an alternative procedure. We present the outcome of 11 patients, who were treated with this method. METHODS: The patient is placed in prone position on the operation table. Under image intensifier control, a 5mm threaded sacral bar is inserted through the body of S1 from the left to the right dorsal ilium. Nuts are placed over the bar achieving fracture compression. When anterior pelvic instability is present, an anterior osteosynthesis is also performed. Clinical and radiological outcome were evaluated one year after index surgery with different scoring systems. RESULTS: Eleven patients (9 F and 2 M) were treated between 2005 and 2010. The mean age of the patients was 73 years at time of operation. There were no mechanical complications. Postoperatively there was a temporary nerve palsy of L5 in one case. The mean follow-up was 14 months. In all patients, a bony healing of the dorsal pelvic ring was achieved. Seven patients showed a major clinical improvement, in four patients a moderate. CONCLUSIONS: Trans-sacral bar osteosynthesis is a promising method for stabilization of fatigue fractures of the pelvic ring. Only with this method, a high interfragmentary compression is achieved, independent of the quality of the spongious bone of the sacral body.

Radiation exposure in whole-body computed tomography of multiple trauma patients: bearing devices and patient positioning.

BACKGROUND: Whole-body computed tomography (WBCT) plays an important role in the management of severely injured patients. We evaluated the radiation exposure of WBCT scans using different positioning boards and arm positions. METHODS: In this retrospective study, the radiation exposure of WBCT using a 16-slice multislice computed tomography scanner was evaluated. Individual effective doses (E, mSV) was calculated. Patients were assigned to two groups according to placement on a plastic transfer mat (PTM, group 1) or on the Trauma Transfer™-Board (TTB, group 2). Data were collected for each group with arm placement on the abdomen (a) or in raising position (b), respectively. The maximum ventro-dorsal diameter [VDD] at the trunk was measured. RESULTS: 100 patients with potentially life-threatening injuries were analysed. Patient demographics and VDD did not differ in the two groups. Radiation exposure in term of E did not reveal any significant differences between the two positioning boards using same arm position [group 1a (n=26) vs. 2a (n=24) (mSV): 16.7±4.7 vs. 17.1±4.4, group 1b (n=26) vs. 2b (n=24) (mSV): 13.1±3.9 vs. 14.3±1.5]. The arm raising positioning showed a significant reduction in E in comparison to the placement on abdomen position [group 1b vs. 1a (mSV): 13.1±3.9 vs. 16.7±4.7, p<0.05, group 2b vs. 2a (mSV): 14.3±1.5 vs. 17.1±4.4, p<0.05]. CONCLUSIONS: Patient arm positioning for WBCT has an important influence on radiation exposure. Effective dose was 16-22% lower when arms were raised. An individual placement algorithm may lead to a relevant reduction of radiation exposure of severely injured patients.

Radiological analysis, operative management and functional outcome of open book pelvic lesions: a 13-year cohort study.

UNLABELLED: We present the clinical and radiological outcome of a 13-year cohort study of 38 open book pelvic lesions. All patients were treated in one Level I Trauma centre. In the posterior pelvis, sacro-iliac diastasis was seen in 31 patients, sacral fracture in 7. In all patients with sacro-iliac diastasis, the pubic bone was inferiorly displaced on the primary ap pelvic overview on the side of injury. All but one patient was treated with open reduction and internal fixation of the symphysis pubis. Additional stabilization of the posterior pelvis was done in 9 patients. 32 patients were seen after a median follow up of 84 months. Majeed score and SF-36 questionnaire were used. Functional outcome was excellent with a mean Majeed score of 95.7. Comparing our data with the SF-36 score of the normal German population, the mean value of the 'role-physical' and the 'physical function' categories was significantly lower for patients treated with an open book lesion. There was a tendency towards a better outcome in open book lesions with sacral fracture. There was a tendency towards worse outcome for the patients with additional dorsal stabilization. Male impotence was the single most important lesion of neurological origin which persisted two years after open book lesion. CONCLUSION: Functional outcome after surgical treatment of open book pelvic lesions is good. External rotation and accompanying inferior displacement of the ipsilateral hemipelvis may be a sign of partial lesion of the posterior sacroiliac complex. Identification of patients who need additional posterior stabilization remains difficult.

Mid- to long-term results after bipolar radial head arthroplasty.

BACKGROUND: Radial head arthroplasty is considered the treatment of choice for unreconstructable radial head fractures in the acute fracture situation. Although short-term results in the current literature are promising, replacement of the radial head remains controversial as long-term results are still missing. We report our 8.8-year results after treatment with a bipolar radial head prosthesis by Judet. MATERIALS AND METHODS: In our department, 19 patients were treated with bipolar radial head arthroplasty between 1997 and 2001. Seventeen of these patients-14 men and 3 women-were examined retrospectively after 106 months (range, 78-139). Of these, 9 patients were treated primarily, 7 patients secondarily, and 1 because of a tumor. RESULTS: On the Mayo Elbow Performance Score, 6 patients achieved excellent results, 10 good, and one fair. The mean DASH score was 9.8 (range, 0-34). No differences were seen between primary and secondary implantation. Flexion averaged 124° (range, 110-150°), the extension deficit was 21° (range, 0-40°), pronation 64° (range, 30-90°), and supination 64° (range, 30-90°). The following complications were seen: 2 dislocations and 8 cases of degenerative changes of the capitellum, 1 with severe erosion. Signs of ulnohumeral arthrosis were found in 12 patients. No evidence of loosening, radiolucencies, or proximal bone resorption was detected. CONCLUSION: Despite major primary complications and high incidence of radiographic signs of degenerative changes after 8.8 years, mainly good clinical results were achieved with Judet's bipolar prosthesis.

Management of Acute Hemorrhage in Pelvic Trauma: An Overview.

Pelvic disruption is a combination of fractures or dislocations of the pelvic ring with trauma of the soft tissues on the inside and outside of this ring. Hemodynamic instability is the result of blood loss out of the fracture fragments, the posterior venous plexus, ruptured pelvic organs, or arterial lesions. In the resuscitation phase, different measures are possible to reduce the volume of the disrupted pelvis and to restore mechanical stability. They are not competitive but complementary. Pelvic binders should be used in the prehospital phase before and during transport. Application of a pelvic C-clamp is restricted to inhospital patients with C-type pelvic ring lesions and with severe and ongoing hemodynamic instability. External fixation is most useful in B-type but also has limited value in C-type injuries. The prerequisite for pelvic packing is the restoration of mechanical stability by pelvic C-clamping or external fixation. It is effective in severe venous bleeding in the small pelvis. Pelvic angiography and selective embolization is performed in patients with active arterial bleeding. These patients can be identified by a convincing clinical picture, by early multislice computed tomography (CT) with contrast- enhanced angiographic technique, or by the persistent need for volume replacement after C-clamping, external fixation, or pelvic packing.

Outcome in Pelvic Ring Fractures.

Pelvic ring fractures represent a negative prognostic factor for what concerns morbidity and mortality of a polytraumatized patient. The subjective and functional prognosis of a pelvic ring fracture is dependent upon its degree of instability. Associated severe peripelvic soft tissue injuries and neurovascular lesions (complex pelvic trauma) affect outcome negatively. Although high rates of anatomic reduction and stable fixation have been achieved in recent years, only 60% of patients have an excellent or good clinical result. Sequelae of neurologic lesions and genitorurinary injuries are typically associated with considerable rates of persistent functional impairment. Chronic pain and disability are often very difficult to treat. Health-related quality of life and life satisfaction after pelvic ring fractures caused by high-energy trauma is substantially lower when compared to a reference population.

[Reconstruction of fractures of the anterior wall and the anterior column of the acetabulum using an ilioinguinal approach]. / Osteosynthese der Frakturen der Vorderwand und des vorderen Pfeilers des Azetabulums über einen ilioinguinalen Zugang.

OBJECTIVE: Restoration of the congruence of the hip joint. Correction of gaps or steps in the articular surface, especially in the main weight-bearing area of the acetabular dome. Correction of femoral head subluxation. Restoration of joint stability in order to enable early postoperative mobilization. INDICATIONS: Fractures of the anterior wall and/or column that are characterized by intraarticular gaps or steps of > 1 mm in the area of the main weight-bearing dome of the acetabulum. Fractures complicated by subluxation or dislocation of the femoral head. CONTRAINDICATIONS: Poor general physical condition and/or dementia. Critical soft-tissue conditions in the area near the surgical approach. Local soft-tissue infection. Preexisiting severe osteoarthritis of the hip joint. SURGICAL TECHNIQUE: Exposure of the fracture through an ilioinguinal approach. Reduction of a subluxated femoral head. Reduction of the anterior column and/or wall. Correction of articular gaps, steps and areas of joint impression. Internal fixation using small-fragment reconstruction plates, if required in combination with additional screws. POSTOPERATIVE MANAGEMENT: Postoperative radiographs for the documentation of the surgical result and implant position (exclusion of intraarticular implants). Postoperative computed tomography, if indicated. Active and passive exercises of the hip joint starting on day 1. Hip joint flexion limited to 90 degrees . Prophylaxis of thrombosis until full weight bearing, starting preoperatively. Mobilization without weight bearing or 15 kg partial weight bearing for 8-12 weeks. Progressive weight bearing over a time period of 4-6 weeks. Radiologic evaluation after 2, 6, and 12 weeks as well as after 6, 12, and 24 months. RESULTS: Excellent and good functional results are observed in 73-85% of the isolated anterior column fractures. The anterior wall fracture is a seldom injury. Functional results are worse in comparison to the other simple fracture types. Good or excellent results can only be observed in two thirds of cases. This observation is related to the fact that anterior wall fractures often occur in elderly patients with osteoporotic bone.

[Patella fracture]. / Patellafraktur.

OBJECTIVE: Reconstruction of the extensor apparatus of the knee joint. Open reduction and stable internal fixation of patella fractures. Exact reconstruction of the articular surface of the patellofemoral joint. INDICATIONS: Open and closed fractures. Fractures with an intraarticular incongruity (> 2 mm). Incapability of extension of the knee also in nondisplaced fractures of the patella. In the context of internal fixations of additional periarticular fractures of the knee joint. CONTRAINDICATIONS: Compromised general health status or associated injuries. Compromised local soft-tissue situation (contamination, poor soft-tissue cover). Relative: nondisplaced transverse fractures (no displacement in 40 degrees of flexion). Relative: nondisplaced longitudinal fractures(3). Relative: nondisplaced radiating fractures(3). Relative: nondisplaced fractures of the distal pole without involvement of the joint surface and intact extensor apparatus(3). SURGICAL TECHNIQUE: Longitudinal parapatellar incision. Tension band wiring. Lag screw osteosynthesis. Combination of tension band wiring and lag screws. Patellectomy (partial/complete). POSTOPERATIVE MANAGEMENT: Thrombosis prophylaxis. Early physiotherapy. Knee brace. RESULTS: 70% good to excellent results. 30% chronic pain and posttraumatic arthritis. Loss of motion (limited extension).

Double or triple interlocking when nailing proximal tibial fractures? A biomechanical investigation.

OBJECTIVES: To determine whether there are differences in stability between double and triple interlocked intramedullary nails used for the fixation of extraarticular proximal tibial fractures. DESIGN: Randomized in vitro biomechanical-experimental laboratory investigation. SETTING: Biomechanics laboratory of the Clinic for Trauma Surgery at the Johannes Gutenberg-University Mainz. INTERVENTION: A 10-mm defect osteotomy was performed on six paired human tibiae, and the proximal and distal ends were potted in polymethylmethacrylate cement (PMMA). Each pair of bones was randomly stabilized with an intramedullary nail (IM-nail) with two interlocking options (PTN 2s) in one tibia, and with an IM-nail with three interlocking options (PTN 3s) in the corresponding contralateral bone. A biomechanical test of the bone implant construct was then performed with an axial force of 900 N. Displacement of bone fragments was measured and depicted as a force-displacement diagram. MAIN OUTCOME MEASUREMENTS: Biomechanical construction stiffness. RESULTS: The stiffness values for PTN 3s were significantly higher than for PTN 2s. In the group of PTN 2s, two out of six implants failed biomechanically with breakage of one proximal interlocking screw. CONCLUSIONS: Given the parameters of this investigation, triple proximal interlocking provides more stability in nailed proximal tibia fractures than double proximal interlocking. Larger series with clinical follow-up after triple proximal interlocking in tibial nailing should be undertaken to further clarify these questions.

Extracorporeal shock wave-mediated changes in proliferation, differentiation, and gene expression of human osteoblasts.

BACKGROUND: The goal of this study was to determine whether cell proliferation, differentiation, and gene expression of primary human osteoblasts (hOB) are influenced by shock wave application (SWA). METHODS: Osteoblast cultures were isolated from cancellous bone fragments and treated with 500 impulses of energy flux densities of 0.06 mJ/mm, 0.18 mJ/mm, 0.36 mJ/mm, and 0.50 mJ/mm. Twenty-four hours and 96 hours after SWA cell proliferation, alkaline phosphatase activity, and mineralization were analyzed. The global gene expression profiling was determined 96 hours after SWA employing Affymetrix HG-U133A microarrays. RESULTS: After 24 hours, hOB showed a dose-dependent increase in cell proliferation from 68.7% (at 0.06 mJ/mm, p = 0.002) up to 81.6% (at 0.5 mJ/mm, p = 0.001), which also persisted after 96 hours. Numbers of alkaline phosphatase-positive hOB increased after SWA treatment with peak levels of response between 0.18 mJ/mm and 0.5 mJ/mm after 24 hours. Mineralization was significantly higher in all groups compared with controls. Microarray analyses revealed SWA-induced differential expression of 94 genes involved in physiologic processes, cell homeostasis, and bone formation. Most intriguing was the up-regulation of multiple genes involved in skeletal development and osteoblast differentiation (e.g., PTHrP, prostaglandin E2-receptor EP3, BMP-2 inducible kinase, chordin, cartilage oligomeric matrix protein, matrillin). CONCLUSION: We showed that shock waves have direct dose-dependent stimulatory effects on proliferation and differentiation of osteoblasts from normal human cancellous bone. We demonstrated that several genes critical for osteoblast differentiation and function are regulated after SWA. Overall, data presented herein will aid further understanding of the osteogenic effect of shock waves and, in addition, will enhance current knowledge of the SWA-mediated gene expression.

[Angle-fixed plate fixation or double-plate osteosynthesis in fractures of the proximal humerus: a biomechanical study]. / Osteosynthese am proximalen Humerus mittels winkelstabiler Platte oder Doppelplatte: eine vergleichende biomechanische Untersuchung.

Internal fixation of fractures of the proximal humerus needs a high stability of fixation to avoid secondary loss of fixation. This is especially important in osteoporotic bone. In an experimental study, the biomechanical properties of the angle-fixed Philos plate (internal fixator) and a double-plate osteosynthesis using two one-third tubular plates were assessed. The fracture model was an unstable three-part fracture (AO type B2). Eight pairs of human cadaveric humeri were submitted to axial load and torque. In the first part of the study, it was assessed to which degree the original stiffness of the humeri could be restored after the osteotomy by the osteosynthesis procedure. Subsequently, subsidence during 200 cycles of axial loading and torque was analysed. During axial loading, the Philos plate was significantly stiffer and showed less irreversible deformation. Two double-plate fixations, but none of the Philos plate osteosynthesis, failed. During torsion, there were no significant differences between the two implants. From the biomechanical point of view, the angle-fixed Philos plate represents the implant of choice for the surgical fixation of highly unstable three-part fractures of the proximal humerus, as the internal fixator system is characterised by superior biomechanical properties.

[V-y flap for restoration of the fingertip]. / Der V-Y-Lappen zur Versorgung von Fingerkuppendefekten.

OBJECTIVE: Restoration of the fingertip with a neurovascular V-Y flap. INDICATIONS: Transverse or oblique defects of the fingertip, also with exposed bone of the distal phalanx. CONTRAINDICATIONS: Larger defects of the phalanx over the proximal interphalangeal joint. Crush injury of the finger. Preexisting lesions of the fingertip. Circulatory disorder. Contamination. Infection of the finger. SURGICAL TECHNIQUE: A single volar (Tranquilli-Leali, Atasoy) or a bilateral V-Y flap (Geissendörfer, Kutler) is used for restoration of the fingertip. The incision is V-shaped and will be converted to a Y, as the flap is advanced. The subcutaneous tissue of the flap contains neurovascular structures, and provides sensibility and padding of the fingertip. A distal advancement of the flap up to 10 mm is possible with this technique. POSTOPERATIVE MANAGEMENT: Immobilization in a two-finger splint for 1 week. RESULTS: Good functional results.

[Transosseous repair of patellar tendon ruptures]. / Transossäre Naht der Patellarsehnenruptur.

OBJECTIVE: Restoration of active knee extension. Restoration of active knee stabilization. Avoiding secondary patella alta. INDICATIONS: Acute rupture of the patellar tendon within 3-5 days. Chronic rupture of the patellar tendon. CONTRAINDICATIONS: Compromised general health status or associated injuries. Compromised local soft-tissue situation. SURGICAL TECHNIQUE: Exposure of the ruptured tendon. Coronal drill hole through the distal third of the patella and coronal drill hole through the tibial tuberosity. After anatomic positioning of the patella (adjusting correct height), patellotibial fixation with monofil or woven (Labitzke) cerclage wire or PDS cord. Suture repair of the patellar tendon and repair of the ruptured medial and lateral retinaculum. Drain insertion. Wound closure in layers. POSTOPERATIVE MANAGEMENT: Full load bearing in cylinder cast. Week 0-2: flexion restricted to 30 degrees , quadriceps muscle isometry. Week 2-4: flexion restricted to 60 degrees , strengthening of hip abductors and extensors. Week 4-6: flexion restricted to 90 degrees . After week 6: removal of cylinder cast. After week 12: return to sporting activities, removal of the cerclage wire. RESULTS: Good results after surgical therapy. Low rate of secondary rupture. Low rate of muscle weakness.

[The distally based sural neurocutaneous island flap for coverage of soft-tissue defects on the distal lower leg, ankle and heel]. / Die distal gestielte Arteria-suralis-Insellappenplastik zur Deckung posttraumatischer Defekte an distalem Unterschenkel, Sprunggelenk und Ferse.

OBJECTIVE: Stable coverage of soft-tissue defects in the critical regions of the distal lower leg, ankle and heel by avoidance of a microsurgically transplanted free flap. INDICATIONS: Soft-tissue defects < or = 10 cm in diameter--either by trauma or complications (skin necrosis, infection)--on the distal lower leg, ankle or heel with exposed osseous, tendinous or articular structures including high-risk patients (diabetes mellitus type 1/2 and/or arterial vascular disease including stage IIb, not capable of improvement). CONTRAINDICATIONS: Relative: diameter of defect > 10 cm. Absolute: critical ischemia (arterial vascular disease stages III and IV). SURGICAL TECHNIQUE: Outlining of the sural island flap directly over the small saphenous vein. Fasciocutaneous flap elevation proceeding in a proximal-distal direction. Lipofascial dissection of the 3 cm wide and up to 15 cm long neurovascular pedicle after longitudinal skin incision starting at the distal border of the island flap and running distally. Point of pedicle rotation 5 cm above the tip of the fibula. Flap passage into the defect through subcutaneous tunnel or after incision of the soft tissue between defect and donor site. Skin closure over region of pedicle dissection, meshed skin grafting of donor site. POSTOPERATIVE MANAGEMENT: Immobilization of the lower leg in a well-padded cast over a period of about 10 days. RESULTS: In a retrospective study, eleven out of twelve patients (including six high-risk patients) with a distally based sural neurocutaneous flap were examined on average 3.7 years postoperatively. The mean age was 54.9 years (28-80 years). A stable coverage of the defect was achieved in all twelve patients. In ten of twelve sural flaps the defect site was closed by primary wound healing, additional procedures were necessary in two cases (meshed skin grafting of flap border, excision of skin necrosis). All patients examined were satisfied with the result of the primary operative target, the stable coverage of the defect. Stated disadvantages were loss of sensation in the area of sural nerve function (four times), aesthetic impairment (twice), and pain resulting from sural nerve neuroma above donor site (once).