S. Märdian

Working length of locking plates determines interfragmentary movement in distal femur fractures under physiological loading

BACKGROUND This study aimed to investigate the influence of the screw location and plate working length of a locking plate construct at the distal femur on interfragmentary movement under physiological loading. METHODS To quantitatively analyse the influence of plate working length on interfragmentary movements in a locking plate construct bridging a distal femur fracture, a finite element model based on CT (computed tomography) data was physiologically loaded and fracture gap conditions were calculated. Four working lengths with eight screw variations each were systemically analysed. FINDINGS Interfragmentary movements for axial (12-19%, p<0.001) and shear movements (-7.4-545%, p<0.001) at all tested nodes increased significantly with longer plate working length, whereas screw variations within the groups revealed no significant influence. The working length (defined by screw location) dominates the biomechanical fracture gap conditions. INTERPRETATION The current finite element analysis demonstrates that plate working length significantly influences interfragmentary movements, thereby affecting the biomechanical consequences of fracture healing.

Periprosthetic Fractures in Total Ankle Replacement: Classification System and Treatment Algorithm

BACKGROUND Despite progress in implant design and surgical technique, the reported number of periprosthetic ankle fractures following total ankle joint replacement continues to increase. A treatment-oriented classification of these fractures has not yet been reported. The purpose of this study was to evaluate the prevalence, cause, and location of periprosthetic fractures and the stability of the associated prosthetic components after total ankle replacement and to develop a method of classification. METHODS Data regarding 503 total ankle replacements with a mean follow-up of 14.7 months were reviewed. The prevalence, location, and possible cause of the fractures as well as prosthesis stability were analyzed and a systematic method of classification based on these factors was developed. RESULTS Twenty-one patients (4.2%) with a periprosthetic fracture were identified. The fracture was intraoperative (Type 1) in eleven patients (2.2%) and postoperative in the remaining ten (2.0%). Two of the latter fractures were traumatic (Type 2) and eight were stress fractures (Type 3). Two-thirds (fourteen) of the twenty-one fractures occurred in the medial malleolus. CONCLUSIONS The prevalence of periprosthetic fractures following primary total ankle replacement was relatively low. We propose a classification system for these fractures that is based on more than 500 cases. We believe that this classification can facilitate therapeutic decision-making, as it allows for differential analysis of the cause and guides the choice among operative and nonoperative treatment options.

Influence of wound drainage in primary total knee arthroplasty without tourniquet

PurposeAlthough it remains the golden standard, several authors have questioned the role of pneumatic tourniquets in primary knee arthroplasty in recent studies. An intra-articular wound drainage is widely used in the field of total knee arthroplasty although the benefit of postoperative wound drainage is controversial in the literature. This study questioned whether the use of an intra-articular drain is an advance over the lack of a drain in total knee arthroplasty which is performed without a tourniquet.MethodsWe documented the ROM, the knee circumference at the upper patellar pole pre-operatively and on days two, four and six postoperatively. The blood volume and loss was calculated. As surrogate parameter for wound healing we counted the number of days until no residual secretion was observed via the wound/drainage site.ResultsThe results of our investigation showed a significantly better wound healing without the use of a drain. All other parameters revealed no significant differences.ConclusionThe data of this study demonstrate a faster wound healing without the use of a postoperative wound drain in primary total knee arthroplasty which is performed without a tourniquet. Other parameters could not show any significant differences thus indicating that a postoperative wound drain has no significant advantage and the risk of a retrograde bacterial colonisation is well documented. Based on these data we recommend performing a primary total knee arthroplasty without a postoperative drain if the procedure is done without a tourniquet.

Current concepts review: Fractures of the patella

Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration. For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined – due to its biomechanical superiority – with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment.

Fixation of acetabular fractures via the ilioinguinal versus pararectus approach: a direct comparison.

This study compared the quality of reduction and complication rate when using a standard ilioinguinal approach and the new pararectus approach when treating acetabular fractures surgically. All acetabular fractures that underwent fixation using either approach between February 2005 and September 2014 were retrospectively reviewed and the demographics of the patients, the surgical details and complications were recorded. A total of 100 patients (69 men, 31 women; mean age 57 years, 18 to 93) who were consecutively treated were included for analysis. The quality of reduction was assessed using standardised measurement of the gaps and steps in the articular surface on pre- and post-operative CT-scans. There were no significant differences in the demographics of the patients, the surgical details or the complications between the two approaches. A significantly better reduction of the gap, however, was achieved with the pararectus approach (axial: p = 0.025, coronal: p = 0.013, sagittal: p = 0.001). These data suggest that the pararectus approach is at least equal to, or in the case of reduction of the articular gap, superior to the ilioinguinal approach. This approach allows direct buttressing of the dome of the acetabulum and the quadrilateral plate, which is particularly favourable in geriatric fracture patterns.

Sinus pilonidalis in patients of German military hospitals: a review.

Pilonidal sinus disease (PSD) most commonly presents in young men when hair follicles enter through damaged epithelium and cause an inflammatory reaction. This results in the formation of fistular tracts. We reviewed studies based on a shared cohort of patients who presented at German military hospitals with PSD. The effect of the morphology of the sinus, perioperative protocol, and aftercare of the surgical treatment on the recurrence of PSD were evaluated. The drainage of acute abscesses before surgery, the application of methylene blue during surgery and open wound treatment were generally found to reduce the recurrence rate. A positive family history, postoperative epilation and primary suture as the healing method were found to elevate the recurrence rate. Long-term follow up of over 15 years was found to be a vital component of patient care as only 60% of the overall recurrences recorded had taken place by year 5 postoperatively.

Complete major amputation of the upper extremity: Early results and initial treatment algorithm.

BACKGROUND Traumatic major amputations of the upper extremity are devastating injuries. These injuries have a profound impact on patient’s quality of life and pose a burden on social economy. The aims of the current study were to report about the initial management of isolated traumatic major upper limb amputation from the time of admission to definitive soft tissue closure and to establish a distinct initial management algorithm. METHODS We recorded data concerning the initial management of the patient and the amputated body part in the emergency department (ED) (time from admission to the operation, Injury Severity Score [ISS], cold ischemia time from injury to ED, and total cold ischemia time). The duration, amount of surgical procedures, the time to definitive soft tissue coverage, and the choice of flap were part of the documentation. All intraoperative and postoperative complications were recorded. RESULTS All patients were successfully replanted (time from injury to ED, 59 ± 4 minutes; ISS16; time from admission to operating room 57 ± 10 minutes; total cold ischemia time 203 ± 20 minutes; total number of procedures 7.3 ± 2.5); definitive soft tissue coverage could be achieved 23 ± 14 days after injury. Two thromboembolic complications occurred, which could be treated by embolectomy during revision surgery, and we saw one early infection, which could be successfully managed by serial debridements in our series. CONCLUSION The management of complete major amputations of the upper extremity should be reserved for large trauma centers with enough resources concerning technical, structural, and personnel infrastructure to meet the demands of surgical reconstruction as well as the postoperative care. Following a distinct treatment algorithm is mandatory to increase the rate of successful major replantations, thus laying the foundation for promising secondary functional reconstructive efforts. LEVEL OF EVIDENCE Therapeutic study, level V.

Semi-rigid screws provide an auxiliary option to plate working length to control interfragmentary movement in locking plate fixation at the distal femur

BACKGROUND Extent and orientation of interfragmentary movement (IFM) are crucially affecting course and quality of fracture healing. The effect of different configurations for implant fixation on successful fracture healing remain unclear. We hypothesize that screw type and configuration of locking plate fixation profoundly influences stiffness and IFM for a given load in a distal femur fracture model. METHODS Simple analytical models are presented to elucidate the influence of fixation configuration on construct stiffness. Models were refined with a consistent single-patient-data-set to create finite-element femur models. Locking plate fixation of a distal femoral 10mm-osteotomy (comminution model) was fitted with rigid locking screws (rLS) or semi-rigid locking screws (sLS). Systematic variations of screw placements in the proximal fragment were tested. IFM was quantitatively assessed and compared for different screw placements and screw types. RESULTS Different screw allocations significantly affect IFM in a locking plate construct. LS placement of the first screw proximal to the fracture (plate working length, PWL) has a significant effect on axial IFM (p < 0.001). Replacing rLS with sLS caused an increase (p < 0.001) of IFM under the plate (cis-cortex) between +8.4% and +28.1% for the tested configurations but remained constant medially (<1.1%, trans-cortex). Resultant shear movements markedly increased at fracture level (p < 0.001) to the extent that plate working length increased. The ratio of shear/axial IFM was found to enhance for longer PWL. sLS versus rLS lead to significantly smaller ratios of shear/axial IFM at the cis-cortex for PWL of ≥ 62 mm (p ≤ 0.003). CONCLUSION Mechanical frame conditions can be significantly influenced by type and placement of the screws in locking plate osteosynthesis of the distal femur. By varying plate working length stiffness and IFM are modulated. Moderate axial and concomitantly low shear IFM could not be achieved through changes in screw placement alone. In the present transverse osteotomy model, ratio of shear/axial IFM with simultaneous moderate axial IFM is optimized by the use of appropriate plate working length of about 42-62 mm. Fixation with sLS demonstrated significantly more axial IFM underneath the plate and may further contribute to compensation of asymmetric straining.

Interfragmentary lag screw fixation in locking plate constructs increases stiffness in simple fracture patterns

BACKGROUND The aim of the current biomechanical cadaver study was to quantify the influence of an additional lag screw on construct stiffness in simple fracture models at the distal femur stabilised with a locking plate. METHODS For biomechanical testing paired fresh frozen human femora of 5 donors (mean age: 71 (SD 9) years) were chosen. Different locking plate configurations either with or without interfragmentary lag screw were tested under torsional load (2/4Nm/deg) or axial compression forces (500/1000N). FINDINGS Data show that plate constructs with interfragmentary lag screw reveal similar axial and torsional stiffness values compared to intact bone as opposed to bridging plate constructs that showed significantly lower stiffness for both loading conditions. INTERPRETATION The current biomechanical testing unveils that the insertion of a lag screw combined with a locking plate dominates over a bridging plate construct at the distal femur in terms of axial and torsional stiffness.

Benign cystic bone lesions

BACKGROUND Bone cysts are benign tumor-like lesions which often present as a fluid-containing cavity in the bone. They can occur in the skeletal bone as solitary or sometimes multiple bone lesions. OBJECTIVES This review discusses the diagnostics, radiological appearance and therapeutic strategies of the most important benign cystic bone lesions, such as simple bone cysts, aneurysmal bone cysts, intraosseous ganglia, epidermoid cysts and subchondral cysts. The differential diagnoses with respect to cystoid formations and tumors with cystic components are discussed. METHOD A selective literature search was performed taking own experiences into consideration. RESULTS These tumor-like lesions can have the radiological appearance of bone tumors but show no autonomic, stimulus-independent growth and can resolve spontaneously. In the majority of cases open biopsy is necessary to confirm the diagnosis. In some cases no surgical intervention is necessary (e.g. do not touch and leave me alone lesions), whereas in other cases the focus of treatment is on the prevention and therapy of pathological fractures as well as prevention of recurrence. CONCLUSION Cystic bone formations are among the most commonly occurring non-traumatic bone lesions. To eliminate differential diagnostic unclarity, histological investigation of biopsy material is essential. In terms of surgical intervention there exists a trend towards multimodal therapy mostly based on a meticulous curretage.