Experience of the T2 supracondylar nail in distal femoral fractures

Comparison of the biomechanical stability of transverse and oblique screw trajectories in retrograde intramedullary nailing of supracondylar femur fractures

BACKGROUND

The goal was to determine the effect of addition of oblique trajectory distal interlock screws to a retrograde intramedullary femoral nail on implant stability (stiffness), cycles to failure and mode of failure. The hypothesis was that addition of oblique screws would increase implant stability and number of loading cycles to failure.

METHODS

Eight matched pairs were tested; one femur implanted with a femoral nail with only transverse distal interlock screws and the other with transverse and oblique interlock screws. Axial compressive load was applied to the femoral head and the gluteal tendon was tensioned vertically to simulate standing or at 45° to the sagittal plane to simulate stair climbing. Loads were cycled to increasing amplitude until failure of fixation (10 mm displacement or 10° rotation).

FINDINGS

In simulated standing, oblique screw specimen had greater sagittal bending (bowing) than transverse only specimen. Transverse (axial) plane motion was higher in simulated stair climbing in oblique screw specimen. Oblique screw specimen had higher sagittal plane translation at 600 N of load. At 300 N, oblique screw specimen had lower internal-external rotation than transverse only specimen. A larger number of cycles to failure were observed in four oblique screw of seven paired specimen. Failure (10 mm or 10 degrees of motion) was only achieved during simulated stair climbing.

INTERPRETATION

Our hypothesis that adding oblique screws improves fixation was rejected. Activities of daily living other than standing may constitute a challenge to fracture fixation; fixation failure occurred at lower loads in simulated stair climbing than standing.

[The role of the retrograde nailing in distal femur fractures: about 7 cases]

We report a series of seven cases of fractures of the distal end of the femur treated by retrograde centro-medullary nailing in the Orthopedic-Trauma Department at the Hospital Ibn Sina over the period 30/05/2010 - 30/04/2015. The average age of patients was 54 years, with a slight male predominance (57,1%). Road traffic accidents were the main cause of these fractures (71.4%) and they mostly affected the right side of body (57,1%). From a surgical point of view, the mean time between symptom onset and treatment initiation was 2 days. Spinal anesthesia was performed in five cases. The average length of stay in hospital was 5 days. The mean time of consolidation was 4 months in all patients, there was only one case of delayed consolidation (6 months). Patients had good functional outcomes with mean knee flexion 120°, with only one case of limited flexion 90°. There was one case of consolidation delay and one case of pseudarthrosis. No deaths, or superficial or deep sepsis, or thromboembolic complications or fat embolism were registered. In general we had satisfactory outcomes. Our study highlights that retrograde femoral nailing is an essential osteosynthesis technique for the surgical treatment of the distal femur fractures.

Retrograde nailing for distal femur fractures in the elderly

Introduction: We report the results of treating a series of 56 fractures in 54 elderly patients with a distal femur fracture with a retrograde femoral nail.

Methods: Fifty-four of the nails were inserted percutaneously with a closed reduction. After surgery all patients were allowed to weight bear as tolerated. Four fractures were supported in a temporary external splint.

Results: The mean age of patients was 80.6 years (range 51–103 years), 52/54 (96%) were females. There were no cases of nail related complications and no re-operations were required. One patient was lost to follow up. The 30-day mortality was 5/54 (9.3%) and the one year mortality was 17/54 (31.5%).

Conclusions: Distal femoral nail fixation provides a good method of fixation allowing immediate mobilisation for this group of patients.

Retrograde intramedullary nails with distal screws locked to the nail have higher fatigue strength than locking plates in the treatment of supracondylar femoral fractures

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125 000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75 800 cycles (sd 33 900) vs 12 800 cycles (sd 6100); p = 0.007) and mean axial stiffness (220 N/mm (sd 80) vs 70 N/mm (sd 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (sd 0.9) vs 5.1 Nm/° (sd 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78 900 cycles (sd 25 600) vs 52 400 cycles (sd 22 500); p = 0.04).

The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients.

Cite this article: Bone Joint J 2014;96-B:114–21.

Retrograde nailing and compression bolts in the treatment of type C distal femoral fractures

INTRODUCTION

This is a prospective study that verifies the usefulness of retrograde intramedullary nailing (IMN) combined with 'independent' compression bolts in the management of type C (AO/OTA classification) fractures of the distal femur.

PATIENTS AND METHODS

Within a period of 4 years, 17 patients (mean age of 54 years) with intra-articular fractures of the distal femur (type C according to AO/OTA classification) were treated with retrograde IMN and compression condylar bolts. The patients followed an early mobilisation and weight-bearing protocol.

RESULTS

All fractures healed in a mean time of 14.78 weeks with no incidences of malunion, nonunion or infections. No secondary failure of fixation occurred. Partial weight bearing was initiated in average 6.35 weeks postoperatively whilst full weight bearing in 14.6 weeks. The patients regained full extension and 117.22° of mean flexion of the knee joint while the mean New Oxford knee score was 42.05.

CONCLUSIONS

In the treatment of type C fractures of the distal femur, the combination of retrograde nailing and 'independent' compression condylar bolt (inserted prior to the nailing) provided a strong fixation that facilitated uncomplicated outcomes and uneventful early mobilisation.