It has been suggested that minimal incision surgery for hip arthroplasty allows earlier mobilisation and reduces hospital stay. Intensive post-op physiotherapy may also have the same effect. This study aimed to assess which was the more important factor.

The study compared 45 patients (26 NHS and 19 private) undergoing primary total hip arthroplasty using a standard posterior approach to 51 patients (29 NHS and 22 private) with a minimal incision of 10cm or less. Physiotherapy involved once daily weekday sessions with the NHS patients (five sessions per week) versus twice daily with the private patients (14 per week). We compared demographics, incision length, post-operative stay, complication rates and Oxford Hip Scores between the four groups.

Results showed no significant difference in age, sex and BMI between the groups. There was a significant difference (p = 0.0002) in mean scar length between the mini and standard incision groups (15.3 vs. 8.3 cm). There was no significant difference in post-op stay between the mini and standard incision NHS patients or the mini and standard incision private patients. There was a significant difference (p = 0.003) in stay between NHS and private patients (11.4 vs. 7.9 days) regardless of the incision used. There were four (4%) early dislocations, three in the mini incision group. Eleven patients received prophylactic antibiotics compared to five in the standard groups for prolonged wound ooze (> 5 days); only one patient had a proven superficial infection. There was no significant difference in the change in the Oxford Hip Scores between any of the groups.

This study suggests that intensive physiotherapy can significantly reduce in-patient stay but minimal incision surgery itself does not. The higher dislocation rate in the mini incision group demonstrates the learning curve for this technique.

Background Elevated plasma levels of D-dimer have been found to be a useful screening tool in the diagnosis of deep venous thrombosis (DVT) in the general population. In the postoperative setting however their role is less clear.

In approximately 73% of NHS trusts D-dimer is a prerequisite test prior to radiological imaging to diagnose DVT.

This study evaluates the effectiveness of D-dimer as a screening tool for DVT in the postoperative period following total hip and knee arthroplasty.

Method Plasma D-dimer levels were measured pre operatively and on post-operative days 1, 3, 5, and 7 in 78 patients undergoing primary total hip or knee arthroplasty. On day 7 patients underwent bilateral duplex ultrasound scanning in order to confirm the absence of DVT.

All patients wore pneumatic foot pumps for DVT prophylaxis. Chemical thromboprophylaxis was not used. All patients were under the care of one surgeon with the same postoperative regimen.

Results D-dimer levels in the post-operative period were characterized by a double peak, on days 1 and 7. Mean day 1 value 3.63 (sd=2.72, range 0.60–14.34), mean day 7 value 2.83 (sd=1.58, range 1.10–10.30). Mean values on days 3 and 5 were 2.52 (sd=2.26, range 0.50–11.85) and 2.45 (sd=1.41, range 0.91–5.05)

Comparing D-dimer levels between hip and knee arthroplasty we found that both groups displayed the same trend in post-operative D-dimer levels (i.e. peaks at days 1 and 7); however levels were significantly higher following knee replacement (At day 7 p< 0.005)

We compared D-dimer levels of these patients with a second group of 43 patients who had a confirmed DVT following hip or knee arthroplasty. The mean D-dimer level in this group was 2.20 (sd=0.98 or range 0.80 – 4.46). This group was subdivided into two groups, those with D-dimer samples before (and including) day 7 and those after. We found a significant difference between the groups (p=0.01). Mean ≤ day 7 = 2.70. Mean > day 7 = 1.97.

The group of patients with Confirmed DVT on or before day 7 were compared with those free of clot. There was no significant difference found between the D-dimer levels of the two groups. (p=0.37)

Conclusion The D-dimer level is never normal (< 0.4mg/l), in the week following total hip or knee replacement and so cannot exclude a DVT. The level it rises to is indistinguishable form that seen in the population with a DVT and so cannot identify those patients in whom further investigation is warranted. Requesting a D-dimer test in this population wastes time and resources and is of no benefit.