Our ongoing aim is to assess the clinical outcome of joint replacement surgery; we wish to contrast the functional outcome of primary and revision patients, and examine what factors may influence this.

Method: Patient data was collected prospectively between Jan 1998 and April 2006. The assessment scores include, the Harris Hip Score, Knee Society Score, SF 36 Health Survey and WOMAC. We compare the pain and function parts of the Knee Society Score for Primary and Revision TKR and the Harris Hip Score for Primary and Revision THR.

Results: The Harris Hip Score improves significantly up to one-year post surgery, with the largest increase occurring at three months. Post surgery improvement then plateaus between one and two years and between two and five years. Revision hip replacement patients display a significant improvement in the Harris Hip Score at three months post surgery, but improvement plateaus after this up to two years. These results are presented graphically.

The Knee Society Score in primary total knee replacement patients improves significantly over time up to one-year post surgery for all components of the score, with the largest increase occurring at three months. Post surgery improvement then plateaus between 1 and 2 years. At 5 years post op both the total score and the function score significantly decrease while there is no change in the knee score component. All components of the Knee Society Score measured in revision knee replacement patients significantly improve at three months post surgery, after which time no further significant improvement is noted.

Discussion: Primary THR patients consistently had higher hip scores than revision patients at all time frames, indicating a better outcome for these patients. When stratified for reason for revision we postulate that a number of well functioning patients are significantly worse following revision surgery. This effect is not seen in the revision TKR group. The decrease in Knee Society Score to five years probably reflects the age of the patients at the time of surgery, which is older than hip replacement patients.

Femoral component malrotation is a major cause of patello-femoral complications in total knee arthroplasty. In addition, it can affect varus/valgus stability during flexion which can lead to increased tibiofemoral wear.

Debate exists on where exactly to rotate the femoral component. The three principal methods utilise different anatomical landmarks: the posterior condylar axis, the transepicondylar axis and the antero-posterior axis (Whiteside’s line).

A prospective randomised controlled trial was undertaken. Sixty consecutive patients undergoing total knee arthroplasty by a single surgeon (LML) at the Royal Perth Hospital were randomised into 3 groups based on the intra-operative method for measuring femoral rotation using the PFC sigma prosthesis (Depuy) with computer navigation (Depuy/Brainlab). All patients received the usual post-operative treatment, rehabilitation and JRAC (Joint Replacement Assessment Clinic) follow up. All underwent a CT scan according to the Perth CT protocol designed specifically to accurately measure component alignment and rotation.

No significant difference in femoral rotation was found between the three groups using a one-way analysis of variance (p=0.67). However, Whiteside’s line had a significantly greater variability than the posterior condylar or transepicondylar axis using the F Test for variances (p=0.02, p=0.03). In conclusion, whilst there was no significant difference in femoral rotation, Whiteside’s line did show greater variability (−6° to 3°), and therefore we recommend the use of either the transepicondylar or posterior condylar axis in Total Knee Replacement.

The technique of bone transport with a conventional Ilizarov external fixator is the current standard means of dealing with segmental bone defects not amenable to bone grafting. Problems with control of the distraction of regenerate bone frequently compromises treatment resulting in secondary deformity. Accurate docking of the defect bone ends is also complex to manage with the Ilizarov apparatus, corrections being possible in only one plane at a time (serial processing).

The Taylor Spatial external fixator (TSF), (Smith and Nephew, Memphis, Tennessee), is a modified Ilizarov fixator with six telescopic struts that are free to rotate at their connection points to the proximal and distal rings. This combination forms a Stewart Gough platform similar to that used in aircraft simulators. By adjusting only strut lengths, and applying Chasles theorem, one ring can be repositioned with respect to the other. Therefore with the aid of computer software, six axis deformities can be corrected simultaneously (parallel processing). We have used this device over the past 2 years in patients with segmental bone defects of the tibia in a stacked mode of application – a three ring construct with six struts between each pair of rings – to allow simultaneous accurately controlled distraction osteogenesis in one segment and independently controlled closure and compression at the docking site.

We present the results of 19 stacked Taylor Spatial frames in 19 patients treated with bone transport in the tibia. The diagnosis was bone resection for infected non union in fourteen, tumour resection in three and acute non infected bone loss secondary to trauma in two. The average age was 34.9 years, (range 10 to 69). Transport ranged from 4 to 12 cm. We used a distraction rate of 0.75mm/day and a comparable compression rate for closure of the defect. At the distraction site, angulation was controlled to within 1degree in any plane and translation to within 1mm in any direction, including length, allowing perfect alignment of the regenerate in all 19 cases. Regenerate quality was uniformly excellent. Superior control of the docking site compared with the Ilizarov fixator was consistently possible and the union rate was 100%. We observed no major complications of treatment. Minor complications included pin and wire infection and breakage all of which were treatable by simple measures with no long term sequelae.

In summary our experience with the stacked TSF for bone transport has shown it to be a highly reliable tool. We have achieved perfect control of regenerate bone in all axes and improved clinical outcomes for these complex problems.