Improved weight bearing during gait at 6 weeks post-surgery with an angle stable locking system after distal tibial fracture.

BACKGROUND: Functional recovery after intramedullary nailing of distal tibial fractures can be monitored using ipsilateral vertical ground reaction forces (vGRF), giving insight into recovery of patients' gait symmetry. Previous work compared patient cohorts to healthy controls, but it remains unclear if these metrics can identify treatment-based differences in return to function post-surgery. RESEARCH QUESTION: Is treatment of a distal tibial fracture with intramedullary nailing with an angle stable locking system (ASLS) associated with higher ipsilateral vGRF and improved symmetry compared to conventional intramedullary nailing at an early time point? METHODS: Thirty-nine patients treated with ASLS intramedullary nailing were retrospectively compared to thirty-nine patients with conventional locking. vGRFs were collected at 1, 6, 12, 26, and 52 weeks post-surgery during standing and gait. Discrete metrics of ipsilateral vGRF (maximal force, impulse) and asymmetry were compared between treatments at each time point. Time-scale comparisons of ipsilateral vGRF and lower limb asymmetry were additionally performed for gait trials. Mann-Whitney Test or a two-way analysis of variance tested discrete comparisons; statistical non-parametric mapping tested time-scale data between treatment groups. RESULTS: During gait, ASLS-treated patients applied more load on the operated limb (17-38% stance, p = 0.015) and consequently loaded limbs more symmetrically (8-37% stance, p = 0.008) during the loading response at 6 weeks post-surgery compared to conventional IM treatment. Discrete measures of symmetry at the same time point identified treatment-based differences in maximal force (p = 0.039) and impulse (p = 0.012), with ASLS-treated patients exhibiting more symmetry. No differences were identified in gait trials at later time points nor from all standing trials. SIGNIFICANCE: During the initial loading response of gait, increased ipsilateral vGRF and improved weightbearing symmetry were identified in ASLS patients at 6 weeks post-surgery compared to conventional IM nailing. Early and objective metrics of dynamic movement are suggested to identify treatment-based differences in functional recovery.

[Titanium or steel as osteosynthesis material : Systematic literature search for clinical evidence]. / Titan oder Stahl als Osteosynthesematerial : Systematische Literaturrecherche über die klinische Evidenz.

BACKGROUND: The selection of the appropriate implant material, stainless steel or titanium, is still the decision of the surgeon and/or the affiliated institution. Additionally, remarkable international differences can be found between the different markets, which cannot really be explained. OBJECTIVE: A systematic literature search was performed to verify whether there is clinical evidence for the preference of one material over the other. MATERIAL AND METHODS: The systematic literature search was performed utilizing the internet databases PubMed, Cochrane and Web of Science. Comparative studies were included that reported on adult patients with osteosynthesis of extremities after trauma using either stainless steel or titanium implants. Information was extracted about infection rates, incidence of clinically relevant allergies, problems with implant removal and other complications. RESULTS: A total of 18 publications were identified to be eligible and 2 referenced articles were added. In summary, there is insufficient clinical evidence that the use of titanium or steel implants has a positive or negative effect on fracture healing, shows different rates of allergies, different rates of infections or mechanical failure. No supporting evidence could be identified for the difficulties with removal of titanium implants reported by surgeons. CONCLUSION: This systematic literature search did not provide any clinical evidence for material-related differences between titanium or stainless steel implants for fracture fixation. Based on the current clinical evidence both titanium and steel implants can be considered to be of equal value. The reported difficulties with implant removal are not reflected in the published literature.

Evaluation of the effectiveness of the angular stable locking system in patients with distal tibial fractures treated with intramedullary nailing: a multicenter randomized controlled trial.

BACKGROUND: Angular stable locking of intramedullary nails has been shown to enhance fixation stability of tibial fractures in biomechanical and animal studies. The aim of our study was to assess whether use of the angular stable locking system or conventional locking resulted in earlier full weight-bearing with minimum pain for patients with a distal tibial fracture treated with an intramedullary nail. METHODS: A prospective multicenter, randomized, patient-blinded trial was conducted with adults who had a distal tibial fracture. Patients' fractures were managed with an intramedullary nail locked with either an angular stable locking system or conventional locking screws. Outcomes were evaluated at six weeks, twelve weeks, six months, and one year after surgery. Time to full weight-bearing with minimum pain was calculated with use of daily entries from patient diaries. Secondary outcomes included pain at the fracture site under load, quality of life, gait analysis, mobility, radiographic findings, and adverse events. RESULTS: One hundred and forty-two patients were randomly allocated to two treatment groups: seventy-five to the group receiving intramedullary nailing with the angular stable locking system and sixty-seven to the group receiving conventional intramedullary nailing. No clinically important differences were found for either the primary or secondary outcome parameters between the groups during the entire follow-up period. CONCLUSIONS: Use of an angular stable locking system with intramedullary nailing did not improve the outcome compared with conventional locking screws in the treatment of distal tibial fractures.

Mechanical behavior of fixation components for periprosthetic fracture surgery.

BACKGROUND: Reliable periprosthetic fracture treatment needs detailed knowledge on the mechanical behavior of the fixation components used. The holding capacity of three conventional fixation components for periprosthetic fracture treatment was systematically investigated under different loading directions. METHODS: Locking compression plates were fixed to a 7 cm long part of diaphyseal fresh frozen human femur with either a single 1.7 mm cerclage cable, a 5.0mm monocortical or a bicortical locking screw (n=5 per group). Constructs were loaded in lateral, torsional and axial direction with respect to the bone axis in a load-to-failure test. Corresponding stress distribution around the screw holes was analyzed by finite element modeling. FINDINGS: Both screw fixations revealed significantly higher stiffness and ultimate strength in axial compression and torsion compared to the cerclage (all P<0.01). Ultimate strength in lateral loading and torsion was significantly higher for bicortical screws (mean 3968 N SD 657; mean 28.8 Nm SD 5.9) compared to monocortical screws (mean 2748 N SD 585; mean 14.4 Nm SD 5.7 Nm) and cerclages (mean 3001N SD 252; mean 3.2 Nm SD 2.0) (P≤0.04). Stress distribution around the screw hole varied according to the screw type and load direction. INTERPRETATION: Fixation components may be combined according to their individual advantages to achieve an optimal periprosthetic fracture fixation.

Underneath the cerclage: an ex vivo study on the cerclage-bone interface mechanics.

INTRODUCTION: Cerclages regain interest due to a rising number of periprosthetic fractures. The contact distribution at the circumferential cerclage-bone interface is still unknown. Local interface pressure depends on the amount of contact area. Cortical damage at the interface would provoke cerclage loosening. Therefore, the contact area, the bone pressure along the interface and the cortical resistance underneath loaded cerclages were determined in an ex vivo model. MATERIALS AND METHODS: Human diaphyseal femoral bone was used with differing cross-sectional geometry. Bone contact points of fixed 1.5 mm wire and 1.7 mm cable cerclages were identified from axial radiographs. Pressure distribution at the cerclage-bone interface was recorded with a pressure-measuring film using a distraction setup with two cortical half shells. Bone shells with installed cerclages were separated with up to 400 N force and were subsequently analyzed histologically to detect cortical damage. RESULTS: Both cerclage types exhibited a point contact fixation with non-loaded spanned zones in-between. Cables cover larger contact areas. Both cerclages exhibited an inhomogeneous interface pressure distribution depending on the bone surface geometry. Histology revealed intact cortical bone without cortical affection after loading of both cerclage types. CONCLUSION: Point contact fixation of the cerclages installs non-loaded, spanned zones where the periosteum is not compressed, rendering a strangulation of the blood supply unlikely. Cortical bone withstands static concentric pressure produced by the cerclage. Cortical groove formation is attributed to instability under functional load and not to weakness of the cortex itself.

Use of the less invasive stabilization system (LISS) in patients with distal femoral (AO33) fractures: a prospective multicenter study.

INTRODUCTION: The Less Invasive Stabilization System (LISS) is an internal fixator that can be inserted percutaneously by means of a minimally invasive surgical approach. This paper presents the use of this system exclusively in patients with AO33 distal femoral fractures, a group in which fracture management is often complicated by multiple trauma and soft-tissue damage. MATERIALS AND METHODS: A series of 62 patients (mean age 52 years) with 66 AO33A or C fractures received the LISS implant and were followed prospectively for 12 months. Assessments included the radiographic evaluation of implant placement and healing, measurement of valgus/varus and sagittal joint malalignment, and the assessment of weight-bearing capacity and range of motion. RESULTS: The mean duration of surgery was 85 min (range 40-135 min) for 33A fractures and 149 min (range 50-300 min) for 33C fractures. Postoperative radiographic assessments showed that the LISS implant was positioned correctly in 59 cases (89%). Assessment of valgus/varus alignment showed correct axial alignment in 49 cases (74%), a deviation of 5-10 degrees in 13 cases, and a 10-20 degrees deviation in 1 case. Correct sagittal alignment was observed in 56 cases (85%), 5-10 degrees malalignment in 5 cases, and 10-20 degrees in 2 cases. During the course of the 1-year follow-up, 8 patients (9 fractures) died; 2 other patients were not available for follow-up. Complete fracture healing was achieved in 85% of the followed-up patients. Forty-eight patients were capable of full weight-bearing. After fracture healing, maximum flexion of the injured limb was on average 80% of the range of the uninjured limb. An extension deficit of more than 5 degrees was measured in 3 cases. Of the 62 patients, 14 underwent further operations during the course of follow-up. Of these, 6 required bone grafting and 3 refixation of the implant due to implant loosening. Deep infections requiring several debridements occurred in 2 patients. No complications relating solely to the implant were observed. CONCLUSION: The LISS showed good overall results in the treatment of these difficult fractures. It is a good alternative to conventional extramedullary and intramedullary stabilizing techniques, especially in more complex fracture situations.