Effect of intraoperative weight-bearing simulation on the mechanical axis in total knee arthroplasty.

PURPOSE: Successful outcome after total knee arthroplasty (TKA) requires precise realignment of the mechanical axis. The intraoperative assessment of the mechanical axis is difficult. Intraoperatively, the effect of weight bearing on the lower limb mechanical axis is ignored. We developed a custom-made mechanical loading device to simulate weight-bearing conditions intraoperatively and analysed its effect on the mechanical axis during TKA. METHODS: Measurements of the mechanical axis were obtained during 30 consecutive primary TKAs in osteoarthritic patients using image-free knee navigation system. Half body weight was applied intraoperatively using our device to quantify the effect of intraoperative load application on the mechanical axis, thus receiving indirect information about soft tissue balancing. Furthermore, the intraobserver and interobserver reliability of navigated mechanical axis measurement with and without load was determined. RESULTS: Before TKA, mean mechanical axis was 4.0° ± 4.9° without load. Under loading conditions, the mean change of the mechanical axis was 2.1° ± 2.8°. Repetitive measurements of the senior surgeon and junior surgeon revealed a high intraobserver (ICC 0.997) and interobserver reliability (ICC 0.998). The registration of the mechanical axis without and with application of intraoperative loading demonstrated no significant differences during insertion of the trial components (SD 0.29 ± 0.29) and after the definitive component cementation (SD 0.63 ± 0.44). CONCLUSIONS: Intraoperative quantification and analysis of the mechanical lower limb axis applying defined axial loading by our custom-made loading apparatus is reliable. Ligament stability was unbalanced before TKA and balanced after TKA. For TKA, intraoperative simulation of weight bearing may be helpful to quantify, control and correct knee stability and its influence of mechanical axis.

[Reconstruction of an iatrogenic acromial pseudarthrosis: a case report]. / Rekonstruktion einer iatrogenen Akromionpseudarthrose: Ein Fallbericht.

Acromial fractures are rare but severe complications which can occur during subacromial decompression. We report a case of acromial pseudarthrosis which was discovered belatedly due to persistent pain after several operations. The pseudarthrosis was successfully treated by osteosynthesis with a distal radius plate and implantation of a monocortical bone graft from the iliac crest. Two years after surgery, the fracture has healed and the patient's pain improved significantly. In the constant score the patient achieved postoperatively 58 points compared to 25 points before surgery and 65 points compared to 25 points preoperatively in the subjective shoulder rating system (SSRS). Postoperatively, the patient had a better range of motion with active abduction/adduction of 50/0/25º (30/0/20° preoperatively), outward rotation/inward rotation of 35/0/45º (30/0/30° preoperatively) and anteversion/retroversion of 60/0/35° (35/0/20° preoperatively).

Unstable paediatric pelvic injuries: the patho-anatomical patterns of pelvic ring failure and the role of avulsion of the iliac apophysis.

Unstable pelvic injuries in young children with an immature pelvis have different modes of failure from those in adolescents and adults. We describe the pathoanatomy of unstable pelvic injuries in these children, and the incidence of associated avulsion of the iliac apophysis and fracture of the ipsilateral fifth lumbar transverse process (L5-TP). We retrospectively reviewed the medical records of 33 children with Tile types B and C pelvic injuries admitted between 2007 and 2014; their mean age was 12.6 years (2 to 18) and 12 had an immature pelvis. Those with an immature pelvis commonly sustained symphyseal injuries anteriorly with diastasis, rather than the fractures of the pubic rami seen in adolescents. Posteriorly, transsacral fractures were more commonly encountered in mature children, whereas sacroiliac dislocations and fracture-dislocations were seen in both age groups. Avulsion of the iliac apophysis was identified in eight children, all of whom had an immature pelvis with an intact ipsilateral L5-TP. Young children with an immature pelvis are more susceptible to pubic symphysis and sacroiliac diastasis, whereas bony failures are more common in adolescents. Unstable pelvic injuries in young children are commonly associated with avulsion of the iliac apophysis, particularly with displaced SI joint dislocation and an intact ipsilateral L5-TP.

The axis-board: an alternative to the cable technique for intraoperative assessment of lower limb alignment.

INTRODUCTION: Accurate intraoperative assessment of lower limb alignment is crucial for the treatment of long bone fractures, implantation of knee arthroplasties and correction of deformities. PURPOSE: The aim of this study is to present a new technique for the intraoperative analysis of the mechanical axis. METHODS: The axis board is placed under the patient's lower limb. With the centre of the ankle and hip lying on the reference line we can assess the mechanical axis of the lower limb. This technique was used in 38 cases (19 high tibial osteotomies, 13 femoral fractures and 6 tibial fractures). RESULTS: Comparing the intraoperative tibiofemoral angles and Mechanical Axis Deviations (MAD) with the results of the postoperative long standing radiographs we showed an accuracy of 1 +/- 0.9 degrees and 2.9 +/- 2.6 mm respectively. CONCLUSION: The method is a simple and convenient option for intraoperative evaluation of the mechanical axis. However, for complex corrections we still recommend the use of navigation systems.

Medial transport of the fibula using the Ilizarov device for reconstruction of a massive defect of the tibia in two children.

We present two children with massive defects of the tibia and an associated active infection who were treated by medial transport of the fibula using the Ilizarov device. The first child had chronic discharging osteomyelitis which affected the whole tibial shaft. The second had sustained bilateral grade-IIIB open tibial fractures in a motor-car accident. The first child was followed up for three years and the second for two years. Both achieved solid union between the proximal and distal stumps of the tibia and the fibula, with hypertrophy of the fibula. The first child had a normal range of movement at the knee, ankle and foot but there was shortening of 1.5 cm. The second had persistent anterior angulation at the proximal tibiofibular junction and the ankle was stiff in equinus.