[Biomechanical comparison of six different fixation techniques for treatment of metacarpal neck fractures]. / Biomechanischer Vergleich sechs verschiedener Fixationstechniken zur Versorgung von Halsfrakturen der Metakarpale.

PURPOSE: The purpose of this study was to evaluate the primary stability of commonly used fixation techniques for metacarpal neck fractures and to compare it with that of an innovative osteosynthesis device: IlluminOss™, the photodynamic bone stabilization system™. MATERIAL AND METHODS: Metacarpal neck fractures were created on the second to fifth metacarpal bones of 24 freshly frozen human cadavers using a band saw. Specimens were randomly assigned to one of six groups and treated with (1) K-wire fixation, (2) dorsal plating, (3) external fixation, (4) cross-threaded K­wire fixation, (5) IlluminOss™ and (6) locked IlluminOss™. In each group 16 specimens each underwent either monocyclic or polycyclic loading protocols. RESULTS: During monocyclic loading none of the specimens failed prior to a maximum deformation of 3 mm. With intramedullary K­wire fixation the mean loads were significantly lower than those of the other techniques. Mean loads causing 2 mm deformation with external fixation were significantly lower than those with dorsal plate osteosynthesis. The mean linear stiffness of the K­wire osteosynthesis was significantly lower than for the other fixation techniques and all methods of external fixation were significantly lower than dorsal plates. There were no significant differences with respect to the linear stiffness between the groups with dorsal plates, fragment fixation system (FFS), IlluminOss™ and locked IlluminOss™. During polycyclic testing the loss of resistance in dorsal plate osteosynthesis was significantly lower than with K­wire and IlluminOss™ fixation. No significant differences in loss of resistance could be shown between dorsal plate osteosynthesis, external fixation, FFS and locked IlluminOss™. CONCLUSION: In summary, IlluminOss™ can be used as an intramedullary stabilization system for treatment of metacarpal neck fractures. In combination with locking screws the biomechanical characteristics of IlluminOss™ are comparable to the other fixation techniques.

[Injuries during Equestrian Vaulting]. / Sportverletzungen beim Voltigieren.

Background: Vaulting is the least studied equestrian sports regarding the occurrence of injuries. As its sequences of motion do not compare to riding, vaulting must be assessed separately. Material and Methods: This retrospective, questionnaire-aided survey was aimed to gain insight into the overall frequency of injuries among equestrian vaulters. The second part of the study looked into the knee injuries that occurred. Survey forms were sent to 60 vaulting and equestrian clubs all over Germany, making for a response rate of 63 %. Results: 95 % of 624 responding athletes were female. The pool of participants consisted of both amateur and professional level vaulters with a mean age of 15 years. The survey showed a mean number of 4.1 injuries sustained during the observation period, i. e. the entire time an athlete had been active in the sport up to the data collection. The lower extremities were the most commonly injured area with a total proportion of 45 %, followed by injuries to the spine and the head with 30 %, and the upper extremities with 25 %. Contusions accounted for the highest number of reported injuries. Other frequently reported injuries included muscle strain to the head and spine, fractures to the upper extremity and ligament damage to the lower extremity. 14 % of the participants experienced at least one knee injury. The medial collateral ligament (27 %) was found to be most prone to lesions, followed by the anterior cruciate ligament (23 %) and the medial meniscus (22 %). Half of all knee injuries occurred during dismounts, especially when swing-offs or flanks led to faulty landings. Conclusions: The results show that the lower extremity is the most commonly affected area. The ligamentous injuries affecting the lower extremity mainly result from dismounts. A specific training aimed at improving landing techniques might therefore prove beneficial in preventing injuries. The frequency of contusions and fractures to the upper extremity suggests that these injuries are related to falls.

[Should we use hip-ankle radiographs to assess the coronal alignment after total knee arthroplasty?]. / Ist die postoperative Ganzbeinaufnahme nach Knie-TEP-Implantation notwendig?

BACKGROUND: There is no consensus on whether hip-ankle radiographs or rather standardized a­p knee-radiographs should be used to assess implant position and coronal alignment after total knee arthroplasty (TKA). This study investigates whether implant position and alignment after TKA can reproducibly be assessed using a­p knee-radiographs rather than hip-ankle radiographs. MATERIALS AND METHODS: This study was performed on 100 weight-bearing hip-ankle radiographs after conventional primary TKA. The true mechanical and anatomical femorotibial angle as well as coronal implant position was assessed on hip-ankle radiographs. The radiographs were then cropped to 80, 60 and 40 % of the leg-length and tibial coronal implant position, and the anatomical axis and a surrogate mechanical axis were obtained. The difference in the alignment parameters between the hip-ankle radiographs were statistically compared with the cropped radiographs and the inter-observer correlation coefficient (ICC) was calculated. RESULTS: The ICC for measurement of the mechanical femorotibial angle was higher in hip-ankle radiographs (0.95) when compared with a radiograph cropped to 40 % (0.61). There was a significant difference in the mechanical femorotibial angle between hip-ankle radiographs and any cropped radiograph. However, there were no significant differences in coronal implant position and the anatomical femorotibial angle between hip-ankle radiographs and any cropped radiograph. CONCLUSIONS: We conclude that standard a­p knee-radiographs are insufficient to assess the mechanical alignment following TKA. However, standard a­p knee-radiographs are appropriate to assess the implant position when referenced against the anatomical axes. Weight-bearing hip-ankle radiographs should be questioned as a routine after TKA.

Functional anatomy of the lateral collateral ligament of the elbow.

INTRODUCTION: The aim of this study was to analyze the functional anatomy of the lateral collateral ligament complex (LCLC) and the surrounding forearm extensors. MATERIALS AND METHODS: Using 81 human cadaveric upper extremities, the anatomy of the forearm extensors-especially the anconeus, supinator and extensor carpi ulnaris (ECU)-was analyzed. After removal of aforementioned extensors the functional anatomy of the LCLC was analyzed. The origin of the LCLC was evaluated for isometry. The insertion types of the lateral ulnar collateral ligament (LUCL) were analyzed and classified. RESULTS: The ECU runs parallel to the RCL to dynamically preserve varus stability. The supinator and anconeus muscle fibers coalesce with the LCLC and lengthen during pronation. The anconeus fibers run parallel to the LUCL in full flexion. The LCLC consists of the annular ligament (AL) and the isometric radial collateral ligament (RCL). During elbow flexion, its posterior branches (LUCL) tighten while the anterior branches loosen. When performing a pivot shift test, the loosened LUCL fibers do not fully tighten in full extension. The LUCL inserts along with the AL at the supinator crest. Three different insertion types could be observed. CONCLUSIONS: The LUCL represents the posterior branch of the RCL rather than a distinct ligament. It is non-isometric and lengthens during elbow flexion. The RCL was found to be of vital importance for neutralization of posterolateral rotatory forces. Pronation of the forearm actively stabilizes the elbow joint as the supinator, anconeus and biceps muscle work in unison to increase posterolateral rotatory stability.

[Bilateral Ischiofemoral Impingement: A Case Report]. / Bilaterales ischiofemorales Impingement: ein Fallbericht.

Ischiofemoral impingement (IFI) is a rare cause of hip pain and was first described in 1977. While it can be related to trauma, it may also be idiopathic. We report a case of IFI in a 22-year old female, who was successfully treated by resection of the lesser trochanter. However, 8 months later, symptoms recurred on the contralateral side. Surgical intervention was required to alleviate the patient's symptoms. This case report discusses the clinical, diagnostic and therapeutic features of IFI.

Influence of hip replacement on sagittal alignment of the lumbar spine: An EOS study.

INTRODUCTION: Changes in pelvic position can influence the sagittal alignment of the lumbar spine. The restoration of hip kinematics by hip replacement thus appears to offer the possibility of correcting sagittal alignment. This preliminary retrospective study used EOS imaging to investigate the influence of total hip arthroplasty on pelvic parameters in patients with normal preoperative pelvic parameters. METHODS: Twenty patients with hip osteoarthritis undergoing total hip arthroplasty (THA) between 2011 and 2012 received unilateral THA. To evaluate the preoperative and postoperative changes of the pelvic parameters, we analyzed EOS imaging of the patients to determine pelvic incidence, sacral slope, sacral tilt, pelvic tilt, anterior pelvic plane inclination and pelvic axial rotation. Additionally, anteversion and inclination of the acetabular cup position were determined. RESULTS: No statistically significant difference was found between the preoperative and postoperative measurements of pelvic parameters, although the change in pelvic tilt approached significance. Postoperatively, respective average values of 42.6° and 22.7° were measured for inclination and anteversion of the acetabular cup position. CONCLUSION: THA did not influence pelvic position and sagittal alignment in patients with normal preoperative pelvic parameters. A subsequent study will investigate whether corrections of pelvic parameters outside the norm in patients with OA are possible with THA.

Tibia segment deformation in response to simulated muscle forces: a cadaveric study with a novel optical segment tracking (OST) approach.

OBJECTIVES: A novel optical segment tracking (OST) approach reliant upon motion capturing was previously proposed to assess human tibia segment deformation. The purposes of the present study were to validate the OST approach and assess the contribution of muscular forces to the bone deformation in a well-defined ex vivo human model. METHODS: A custom-made Lower Extremity Loading Device (LELD) was developed to simulate physiological muscle contractions in six human cadaveric lower extremities. Tibia segment deformation was measured by tracking the relative movement between two marker clusters which were affixed into the proximal and distal tibia, respectively. RESULTS: Compared to the physiological norms, the simulated muscle forces remained at a low level. When quadriceps muscle was loaded with forces from 198 N to 505 N, posterior bending (0.12°-0.25°) and lateral bending (0.06°-0.21°) of the tibia segment were found. Large tibia bending angles were found when simulating the co-contraction of upper leg muscles and plantar flexors, and of all leg muscles, respectively. The standard deviations of the deformation angles between the repetitions remained at a low level. CONCLUSIONS: We conclude that the OST approach has the potential to be applied in vivo and quantify muscle-induced bone deformations.

The interference of distal humeral plating with the medial and lateral collateral ligaments of the elbow.

INTRODUCTION: The aim of the present study was to determine the anatomical relationship and evaluate the potential interference of today's common distal humerus plates with the medial and lateral collateral ligaments of the elbow. MATERIALS AND METHODS: The elbow joints of 23 embalmed upper extremities were dissected. Three different brands of distal humerus double-plating systems were applied in a standardized fashion. We used a caliper to measure the amount of absolute overlap of the plates on the corresponding collateral ligaments. RESULTS: The data show contact and overlap with the medial and lateral collateral ligaments in all tested medial and lateral plates. The posterolateral and posteromedial plates showed no contact with the ligaments, yet they did contact the posterior joint capsules. The medial plates showed less contact/overlap when compared with the lateral and extended medial plates. CONCLUSION: Based on the present data, we conclude that distal humerus plating using the perpendicular technique with standard-sized medial plates shows the least amount of overlap over the medial and lateral collateral ligaments. The extent of the overlap of the ligaments by the humeral plates is clearly shown in the present study.

[Conversion of elbow arthrodesis to total elbow arthroplasty]. / Konvertierung einer Ellenbogenarthrodese zur Ellenbogenprothese.

A 44-year-old patient was treated with elbow arthrodesis at a position of 90° due to primary osteoarthritis. Seven years later he was introduced to us due to progressive pain of both elbows. Although the arthrodesis had consolidated uneventfully, the patient felt massive restrictions due to eliminated extension/flexion and persistent pain. The right elbow developed primary osteoarthritis likewise. We performed arthroscopic debridement and arthrolysis of the right elbow. After a recovery phase of 2 months we converted the arthrodesis of the left elbow to total elbow arthroplasty. Three months later he achieved active flexion/extension of 0-30-100°, had no pain and was able to perform most activities of daily living again with his left elbow. Movement against resistance was possible, whereas strength was limited compared to the right side. After 9 months the flexion-extension arc was 0-25-110°. This case shows that conversion of arthrodesis to arthroplasty is possible at the elbow. Despite the long arthrodesis period of 7 years the patient was able to activate the elbow extensors and flexors.

[Treatment of proximal humerus fractures: relative position of different locking plates to the axillary nerve]. / Versorgung von Humeruskopffrakturen: Lagebeziehung proximaler Verriegelungsplatten zum N. axillaris.

OBJECTIVES: Placement of a proximal humerus locking plate through a percutaneous transdeltoid approach bears the advantages of a minimally invasive approach but may compromise the anterior branches of the axillary nerve. This anatomic study aimed to develop a risk profile for 6 types of modern proximal humerus locking plates as to their interference with the axillary nerve. MATERIALS AND METHODS: In this study six different implants (Arthrex®, DePuy®, Königsee®, Smith & Nephew®, Stryker® and Synthes®) were placed on the intact proximal humerus of 33 embalmed cadaveric upper extremities and the relative positioning between the axillary nerve and the screw holes was determined. RESULTS: All locking plates displayed an area of risk which concerned 3 out of 7 (Arthrex®), 4 out of 10 (DePuy®), 2 out of 9 (Königsee®), 3 out of 11 (Smith & Nephew®), 3 out of 11 (Stryker®) and 6 out of 12 (Synthes®) screw holes of the plate. CONCLUSIONS: Using the anterolateral percutaneous deltoid splitting approach the relative position of the axillary nerve to the holes of a specific implant is of relevance for avoidance of iatrogenic lesions to the nerve.

The Essex-Lopresti lesion.

The Essex-Lopresti lesion represents a severe injury of the forearm unit. In the 1940s, it's pathology and consequences have already been mentioned by several authors. Over the course of time, the pathophysiology of the lesion was displayed in more detail. Therefore, an intensive analysis of the involved anatomic structures was done. The interosseous membrane was shown to play a major role in stabilising the forearm unit, in the situation of a fractured radial head, which is the primary stabiliser of the longitudinal forearm stability. Moreover, biomechanical analyses showed a relevant attribution of the distal radio-ulnar joint to the forearm stability. If, in the case of a full-blown Essex-Lopresti lesion, the radial head, the interosseous membrane and the distal radio-ulnar joint are injured, proximalisation of the radius will take place and will come along with secondary symptoms at the elbow joint and the wrist. According to actual studies, the lesion seems to occur more often than realised up to now. Thus, to avoid missing the complex injury, subtle clinical diagnosis combined with adequate imaging has to be undertaken. If the lesion is confirmed, several operative treatment options are available, yet not proofed to be sufficient.

Treatment of radial head and neck fractures: in favor of anatomical reconstruction.

Radial head fractures represent the most common elbow fractures. Undisplaced fractures usually occur in isolation and can be treated nonsurgically. Displaced fractures should be treated surgically. Simple two-part fractures can easily be handled by osteosynthesis, but comminuted fractures pose a major problem for reconstruction. As the radial head is an important stabilizer of the elbow joint-especially in the context of concomitant ligamentous injuries-its resection may lead to pain, limited range of motion, and instability. Therefore, radial head resection is not recommended for the acute situation and open reduction internal fixation (ORIF) or prosthetic replacement should be aimed for. Complications such as secondary loss of fixation, radial head necrosis, and nonunion due to insufficient stability of the osteosynthesis have often been described. Therefore, prosthetic replacement is recommended if stable reconstruction is impossible. With the development of new locking plates especially designed for the maintenance of radial head fractures, the indications for osteosynthesis may be extended. As radial head fractures are complicated by a high percentage of ligamentous injuries and concomitant elbow fractures such as the coronoid, capitellum, and proximal ulna, these additional injuries have to be taken into account. The current treatment concepts are discussed within this paper.

[Classification and treatment of patella fractures]. / Einteilung und Therapie der Patellafraktur.

Patella fractures are rare and account for approximately 1% of all fractures. They are classified regarding their localization (proximal, distal) and appearance. The aim of any treatment is reconstruction of the extensor mechanism and joint surface. If dislocation and cartilage steps are less than 2 mm, conservative treatment may be indicated. Operative treatment is only necessary if a dislocation is more than 2 mm or when the extensor mechanism is unstable. Depending on the shape of the fracture, tension band wiring, interfragmentary screw fixation and combinations are the main techniques. Because patellectomy has functionally the worst result it should be avoided. Sleeve fractures (children) need exact reconstruction of the joint surface. In elderly patients conservative treatment or surgical patella-enclosing wiring techniques for stabilization are the best options due to low bone quality.

Acute injuries in Taekwondo.

Although Taekwondo is becoming an increasingly popular sport, there is a lack of reliable epidemiologic data on Taekwondo injuries. To perform an epidemiologic study on the variety of types of injury in professional and amateur Taekwondo athletes and to find a relation between Taekwondo style, skill level, weight-class and warm-up routine and the occurrence of injuries, we analysed the injury data using a 7-page questionnaire from a total of 356 Taekwondo athletes who were randomly selected. Overall, we registered a total of 2,164 injuries in 356 athletes. Most traumas were contusions and sprains in the lower extremities. Professional Taekwondo athletes have an increased risk of injury in comparison to recreational athletes. Taekwondo style, weight class and tournament frequency have an influence on the athlete's injury profile. Warm-up routines were found to have a positive effect on injury rates. Overall, Taekwondo may be considered a rather benign activity, if injuries during Taekwondo tournaments can be avoided. If not, Taekwondo can result in serious musculoskeletal problems.

[External fixation with motion capacity in acute dislocations and fracture dislocations of the elbow. Fixation with motion capacity]. / Die Behandlung der akuten Luxation und Luxationsfraktur des Ellenbogens. Bewegungsfixateur.

Dislocations and fracture dislocations with their typical fracture patterns may substantially affect the complex anatomy and integrity of the elbow joint. The more components of the joint are injured, the more technically demanding is the therapy. Standardized diagnostic and therapeutic algorithms help to avoid misinterpretations regarding the severity of the injury and the subsequent complications. In elbow dislocations and fracture dislocations with persistent instability the hinged external fixator is an excellent device to improve joint stability and allows physiotherapeutic assistance at an early stage.

An anatomical study of the proximal hamstring muscle complex to elucidate muscle strains in this region.

Muscle strain injuries are common in sports, and a high incidence is reported for the hamstring muscles, especially in the proximal region, where the long head of the biceps femoris muscle is most frequently affected. To look for some architectural peculiarities, which would make this muscle vulnerable, 101 legs of embalmed human cadavers were dissected and descriptively examined, morphometric data were obtained in the proximal region, and slices of plastinated specimens were microscopically examined. The 3 muscles composing the proximal hamstring complex are partly twisted around each other and possess common fibrous adhesions. Biceps femoris (BF) and semitendinosus (ST) muscles form a common head, to which the ST contributes the majority of fascicles extending 9 cm down from the ischiac tuberosity, thereby attaching to the common tendon at a remarkable pennation angle. The first BF fascicles origin from the common tendon only at 6 cm distance from the ischiac tuberosity. It is concluded that the high incidence of proximal BF strains may be a misinterpretation due to insufficient imaging and the complex architecture. It is suggested that the pennation angle at which the ST inserts to the common tendon makes this muscle especially vulnerable for strains during forced eccentric contractions.

The present role of vertebroplasty and kyphoplasty in the treatment of fresh vertebral compression fractures.

Vertebroplasty (VP) and kyphoplasty (KP) are minimally invasive vertebral augmentation procedures for the treatment of fresh vertebral compression fractures (VCFs) associated with osteoporosis, trauma, malignant conditions, hemangiomas, and osteonecrosis. During these procedures, bone cement (e.g., polymethylmethacrylate) is percutaneously injected into the vertebral body. Systematic reviews of both procedures have shown significantly improved back pain and quality of life compared to conservative therapy. Direct comparison between VP and KP is not possible because of the lack of prospective randomized data comparing the two procedures. Both appear to improve patient functional status in most studies, although it is difficult to pool the available data because of differing measurement scales. With increasing popularity of both techniques, particularly over the past ten years, a rising number of publications have detailed potential complications secondary to cement extravasation, from compression of neural elements to venous embolism. Overall complication rates for both procedures are low. Systematic reviews have found significantly higher rates of cement leakage after VP (40%) versus KP (8%), with 3% of VP leaks being symptomatic. The evidence for increased risk of adjacent level fracture after these procedures compared to conservative treatment is inconclusive. When performed by a well-trained practitioner in appropriately selected patients, vertebroplasty and kyphoplasty are both safe and effective treatments for fresh vertebral compression fractures. Results from ongoing randomized controlled trials will provide further detailed information about both procedures in the future.

Different mechanical loading protocols influence serum cartilage oligomeric matrix protein levels in young healthy humans.

The purpose of the study was to investigate whether a relationship between the loading mode of physical activity and serum cartilage oligomeric matrix protein (COMP) concentration exists and whether the lymphatic system contributes to COMP release into the serum. Serum COMP levels were determined in healthy male subjects before, after and at 18 further time points within 7 h at four separate experimental days with four different loading interventions. The loading intervention included high impact running exercise, slow but deep knee bends, and lymphatic drainage of 30 min duration, respectively, and a resting protocol. The serum COMP levels were measured using a commercially available quantitative enzyme-linked immunosorbent assay. An increase (p < 0.001) in serum COMP concentration was detected immediately after 30 min running exercise. Slow but deep knee bends did not cause any significant changes in serum COMP levels. Lymphatic drainage also had no effect on the serum COMP concentration. After 30 min of complete rest the serum COMP level was significantly (p = 0.008) reduced. The elevation of COMP serum concentration seems to depend on the loading mode of the physical activity and to reflect the extrusion of COMP fragments from the impact loaded articular cartilage or synovial fluid.

Biomechanical comparison of tension band- and interfragmentary screw fixation with a new implant in transverse patella fractures.

AIM: The aim of the present study was to compare the primary fixation stability and initial fixation stiffness of two established fixation techniques, the tension band wiring technique and interfragmentary screw fixation, with a mini-screw fragment fixation system in a model of transverse patella fracture. It was hypothesised that the biomechanical loading performance of the fragment fixation system would not significantly differ from the loading characteristics of the two established methods currently investigated. MATERIALS AND METHODS: Ninety-six calf patellae were used in this biomechanical model. A standardized transverse patella fracture was induced and three different fixation methods, including the modified tension band wiring technique, interfragmentary screw fixation, and the mini-screw fragment fixation system, were used for fragment fixation. Specimens were mounted to a loading rig which was secured within a material testing machine. In each fixation group, eight specimens were loaded to failure at a simulated knee angle of either 0 degrees or 45 degrees . Another eight specimens were submitted to a polycyclic loading protocol consisting of 30 cycles between 20N and 300N at a simulated knee angle of 0 degrees or 45 degrees . The residual displacement between the first and the last cycle was recorded. Differences in the biomechanical performance between the three fixation groups were evaluated. RESULTS: No significant differences between the three fixation groups were observed in the parameters maximum load to failure and linear fixation stiffness with monocyclic loading. Specimens being loaded at 45 degrees showed significantly lower maximum failure loads and linear stiffness when compared with 0 degrees . During polycyclic loading, no significant differences in the residual displacement were observed between the groups at 0 degrees loading angle, while at 45 degrees , residual displacement was significantly higher with tension band fixation when compared with interfragmentary screw fixation or the fragment fixation system. CONCLUSION: The biomechanical performance of the fragment fixation system was comparable to interfragmentary screw fixation and superior to the tension band wiring technique. Given the advantages of a system which provides interfragmentary compression and which simplifies fracture fixation after open or closed reduction, we believe the fragment fixation system to be an adequate alternative in the osteosynthesis of transverse patella fractures.