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Treatment of distal tibia shaft fractures using intramedullary nailing requires stable fixation of the distal fragment to prevent malunion. Angular stable locking for intramedullary nails pledge to provide increased mechanical stability. This study tested the hypothesis that intramedullary nails with angular stable interlocking screws would have increased construct stiffness, reduced fracture gap movement and enhanced fatigue failure compared to nails with conventional locking having the same diameter. Biomechanical experiments were performed on 24 human cadaveric tibiae which obtained a distal fracture and were fixed by three different techniques: conventional locking with 8- and 10-mm-diameter nails and angular stable locking with 8-mm nails. Stiffness of the implant-bone construct and movement of the fragments were tested under axial loading and torsion. The constructs were tested to failure under cyclic fatigue loading. Analysis of variance and Kaplan-Meier survival analysis were used for statistical assessment. Axial stiffness of the 10-mm nail was about 50% larger compared to both 8-mm nail constructs independent of the type of locking mode (p < 0.01). No differences were found in axial performance between angular stable and conventional locking neither under static nor under cyclic testing conditions (p > 0.5). Angular stability significantly decreased the clearance under torsional load by more than 50% compared to both conventionally locked constructs (p = 0.03). However, due to the larger nail diameter, the total interfragmentary motion was still smallest for the 10-mm nail construct (p < 0.01). Although the 10-mm nail constructs survived slightly longer, differences between groups were minor and not statistically significant (p = 0.4). Our hypothesis that angular stable interlocking of intramedullary nails would improve mechanical performance of distal tibia fracture fixation was not confirmed in a physiologically realistic loading scenario. Whether minor mechanical advantages provided by angular stability of the locking screws would improve biological tissue response cannot be concluded from this biomechanical study.

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OBJECTIVES: Intramedullary nails with special lag screw designs may provide improved mechanical performance and alleviate clinical problems. We hypothesize that the proximal design of trochanteric nails affects mechanical performance. METHODS: Ten pairs of human cadaveric femora were implanted with 2 different short intramedullary nails without (Gamma3) and with an interlocking lag screw (Intertan). An unstable, multifragmentary, pertrochanteric fracture was created. Bones were tested in a cyclic testing protocol with increasing loads until failure simulating 1 leg stance. Stiffness, failure load, cycles to failure, and fracture gap movements were measured. RESULTS: Initially stiffness of the interlocking lag screw nail was almost 40% larger (P = 0.005) compared with the noninterlocking nail. During the test, the difference in stiffness gradually decreased. Failure load (13%, P = 0.02) and cycles to failure (18%, P = 0.02) were larger for the interlocking nail construct. Rotation and varus collapse of the head were initially up to 84% lower (P = 0.013) for the interlocking technique. During the test, the rate of rotational instability gradually increased for both techniques. CONCLUSIONS: The interlocking lag screw design reduced movement of the femoral head and relative movement between fracture fragments. Beyond that the trapezoidal nail design of the Intertan reduced toggling within the trochanteric area and prolonged survival. Although this study showed a decrease in the retention of stability over time, failure did not occur until the equivalent of 2-3 months of reduced physical activity in which healing may have occurred under normal clinical conditions.

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BACKGROUND:: The periarticular medial clavicle fracture is a rare injury and can be treated conservatively in the majority of cases. However, up to 8% of the patients develop symptomatic nonunion, and fracture dislocation correlates with the number of poor functional results. Operative treatment may be beneficial in these cases. Studies with large series of operated patients are still missing. METHODS:: We investigated 10 patients with operative treatment of periarticular medial clavicle fractures. Preoperative X-ray or computed tomography scan was obtained, and follow-up assessment was performed at determined intervals, including physical examination and X-ray evaluation of bone healing. Finally, functional assessment was carried out from September 2009 to July 2010 using the Disabilities of the Arm, Shoulder and Hand score. RESULTS:: All operated patients had displaced periarticular medial clavicle fractures. A direct surgical approach was performed, and denudation of the bone fragments was avoided. In 8 of 10 cases, we used locking plates, preferentially the T-locking plate. In 6 of 10 patients, three screws were placed in the medial fragment or the sternum. The arm was immobilized in a sling for 2 weeks to 3 weeks, followed by careful passive and increasing active motion exercises. In 9 of 10 operated patients, we observed fracture healing and good functional results. Two patients with paraplegia/tetraplegia were excluded from final assessment but demonstrated fracture healing. In one case, we observed early material loosening caused by misused locking system and wound infection. CONCLUSIONS:: Operative treatment can be considered for periarticular, dislocated medial-end clavicle fractures. Computed tomography scan can be useful for operative planning and is mostly performed in patients with multiple injuries. Locking plates, such as the T-locking plate or the pilon reconstruction plate, are preferred devices. For rigid fixation, at least three locking screws should be placed in the medial bone fragment. The plate can be removed 18 months after osteosynthesis.

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BACKGROUND: After reamed nailing in long bones, there is a negligible amount of reaming debris at the fracture gap of A2 and A3 fractures. The aim of this study was to show whether there are differences between reamed nailing and reamed nailing with controlled intramedullary application of reaming debris at the fracture gap with an intramedullary application device. METHODS: In this trial, 12 human femur specimens were used. On the medullary isthmus, 12 A3 fractures were artificially produced. Afterward, reduction was done by a monocortical external fixator, and closure of the fracture gap was done with a latex finger tip. Intramedullary reaming was performed for up to 10% of the bone cortex. In six femurs, the reaming procedure alone was performed, and in six human femurs, additional controlled application of reaming debris was done. For fixation, an intramedullary plastic implant was used. The region of interest was scanned with the µ-CT 80, and the fracture gap was contoured with digital imaging software. The threshold for the reaming debris was set at 365.6 mgHA/cm³. The analysis of the bone debris located at the fracture gap was measured by percent of debris volume to gap volume. For statistical analysis, the Wilcoxon test was used and a level of significance of p < 0.05 was chosen. RESULTS: The fracture gap volume ranged from 7 mm³ to 29 mm³ without differences in both the groups. In the group without controlled intramedullary application, there was a median bone volume of 0.37 mm³ found at the fracture gap. In the group with controlled intramedullary application, a median of 2.2 mm³ of bone debris was found. The degree of filling of the fracture gap with bone debris was 2% without additional application and 13% with additional application, using the newly developed application device. CONCLUSIONS: The results show that reaming debris at the fracture gap without additional application is negligible. When using an intramedullary application device, the amount of reaming debris at the fracture gap can be increased significantly.

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BACKGROUND: Currently, little information is available on functional outcome of periprosthetic humeral fractures after shoulder arthroplasty. This investigation aimed to evaluate functional and radiological outcome and patients' satisfaction following this type of injury treated by open reduction and internal fixation. METHODS: Retrospective chart analysis of patients treated at two level-I trauma centers. Patients were examined clinically and radiologically. Additionally, functional outcome was assessed using the established DASH-questionnaire and standardized examination for calculation of the Constant score. RESULTS: Five out of six patients showed complete fracture consolidation with satisfying functional results (mean follow up time 62 weeks). One patient showed major complications with poor outcome. DASH and Constant scores were comparable to those described after primary shoulder arthroplasty. CONCLUSIONS: Periprosthetic humeral fractures after shoulder arthroplasty can be treated by angular stable plating with low complication rates and acceptable results.

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BACKGROUND: The aim of this study was to visualize the intramedullary bone debris after reamed nailing of long bones. To date, there is no protocol to quantify bone debris in the fracture gap. The hypothesis was to show if there are differences between A2 and A3 fractures. METHODS: In this trial 17 sheep tibiae were used. On the medullary isthmus eight A2 und nine A3 fractures were produced. Afterwards, reposition, closure of the soft tissue and reaming procedure up to 10% of the bonecortex were done. For internal fixation, a plastic implant was used. The region of interest was scanned with the Micro-CT 80 and the fracture gap was contoured from a special software (SCANCO Medical AG, Switzerland). The threshold for the reaming debris was set at 549.9 mgHA/cm(3). The analysis of the bone debris located at the fracture gap was measured by percent of debris volume to gap volume. For statistical analysis the Wilcoxon test was used and a level of significance of p < 0.05 was chosen. RESULTS: The fracture gap width ranged from 0.3 to 1.7 mm in both groups. Comparing A2 and A3 fractures there was no significant difference concerning the percentage of reaming debris at the fracture gap. The Median of A2 fractures was 20.5 and 21% for A3 fractures. CONCLUSIONS: The results show reaming produces intramedullary bonegrafting. Despite different fracture planes of A2 and A3 fractures, no significant differences in the amount of reaming debris located at the fracture gap could be found. However the percental rate of reaming debris at the fracture gap of plain fractures is negligible. This research shows that there is potential for reaming debris to be applied effectively as a prophylactic and osteogenetic autograft. Together with the high stability of the intramedullary nail an all embracing concept of osteosynthesis could be established.