Aims

Computer hexapod assisted orthopaedic surgery (CHAOS), is a method to achieve the intra-operative correction of long bone deformities using a hexapod external fixator before definitive internal fixation with minimally invasive stabilisation techniques.

The aims of this study were to determine the reliability of this method in a consecutive case series of patients undergoing femoral deformity correction, with a minimum six-month follow-up, to assess the complications and to define the ideal group of patients for whom this treatment is appropriate.

Percutaneous grafting of non-union using bone marrow concentrates has shown promising results, we present our experience and outcomes following the use of microdrilling and marrowstim in long bone non-unions.

We retrospectively reviewed all patients undergoing a marrowstim procedure for non-union in 2011–12. Casenotes and radiographs were reviewed for all. Details of injury, previous surgery and non-union interventions together with additional procedures performed after marrowstim were recorded for all patients. The time to clinical and radiological union were noted.

We identified 32 patients, in sixteen the tibia was involved in 15 the femur and in one the humerus. Ten of the 32 had undergone intervention for non-union prior to marrowstim including 4 exchange nailings, 2 nail dynamisations, 3 caption graftings, 2 compression in circular frame and 1 revision of internal fixation. Three underwent adjunctive procedures at the time of marroswstim. In 18 further procedures were required following marrowstim. In 4 this involved frame adjustment, 5 underwent exchange nailing, 4 revision internal fixation, 2 additional marrowstim, 2 autologous bone grafting and 3 a course of exogen treatment.

In total 27 achieved radiological and clinical union at a mean of 9.6 months, of these ten achieved union without requiring additional intervention following marrowstim, at a mean of 5.4 months. There were no complications relating to marrowstim harvest or application.

Marrowstim appears to be a safe and relatively cheap addition to the armamentarium for treatment of non-union. However many patients require further procedures in addition to marrowstim to achieve union. Furthermore given the range of procedures this cohort of patients have undergone before and after marrowstim intervention it is difficult to draw conclusions regarding it efficacy.

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction.

Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylized as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (θ) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction.

We examined the utility and reproducibility of the new method using 100 normal femora. θ = 81 ± sd 2.5°. As expected, θ correlated with femoral length (r=0.74). P (expressed as the percentage of the distance from the lateral edge of the joint block to the intersection) = 61% ± sd 8%. P was not correlated with θ.

Intra-and inter-observer errors for these measurements are within acceptable limits and observations of 30-paired normal femora demonstrate similar values for θ and p on the two sides.

We have found this technique to be universally applicable and reliable in a variety of distal femoral deformities.

Treatment of syndesmotic injuries is a subject of ongoing controversy. Locking plates have been shown to provide both angular and axial stability and therefore could potentially control both shear forces and resist widening of the syndesmosis. The aim of this study is to determine whether a two-hole locking plate has biomechanical advantages over conventional screw stabilisation of the syndesmosis in this pattern of injury. Six pairs of fresh-frozen human cadaver lower legs were prepared to simulate an unstable Maisonneuve fracture. The limbs were then mounted on a servo-hydraulic testing rig and axially loaded to a peak load of 800N for 12000 cycles. Each limb was compared with its pair; one receiving stabilisation of the syndesmosis with two 4.5mm quadricortical cortical screws, the other a two-hole locking plate with 3.2mm locking screws (Smith and Nephew). Each limb was then externally rotated until failure occurred. Failure was defined as fracture of bone or metalwork, syndesmotic widening or axial migration >2mm. Both constructs effectively stabilised the syndesmosis during the cyclical loading within 1mm of movement. However the locking plate group demonstrated superior resistance to torque compared to quadricortical screw fixation (40.6Nm vs 21.2Nm respectively, p value <0.03).

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the deformities. However, distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We describe a novel technique which accurately determines the CORA and extent of distal femoral deformity.

Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylised as a block. A line bisecting the anatomical axis of the proximal femur is then extended distally to intersect the joint. The angle (?) between the joint and the proximal femoral axis, and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of deformity, permitting accurate correction.

We examined the utility and reproducibility of the new method using 100 normal femora. We found this technique to be universally robust in a variety of distal femoral deformities.

Introduction

The optimal management of intra-articular tibial plateau fractures with metaphyseal-diaphyseal dissociation remains challenging and controversial. We report results using the technique of limited open reduction with external fixation using a fine wire circular frame.

Aims

To compare a randomised group of patients undergoing UKA to investigate the advantages of the minimal invasive approach in the early post-operative stage.