Knee arthrodesis using a compression clamp and a single-plane external fixator to treat infection.

BACKGROUND

In patients with knee infection, arthrodesis by external fixation is a limb-salvage procedure appropriate in highly selected patients. No hardware that might lead to infection is left in situ. However, the fusion rate is limited. Use of a device that applies compression in the coronal plane has been suggested in combination with sagittal external fixation to increase the fusion rate but has not been the focus of published studies. The objectives of this retrospective study were to determine: 1) the fusion rate and, 2) the rate of infection eradication.

HYPOTHESIS: Knee arthrodesis using an external fixator and a compression clamp provides higher fusion rates compared to reports of external fixation without compression.

MATERIAL AND

METHODS

We retrospectively studied 30 patients who underwent knee arthrodesis using external fixation and a compression clamp. The reason for arthrodesis was recurrent infection after total knee arthroplasty in 18 patients and septic arthritis in 12 patients. There were 16 females and 14 males with a mean age of 66.0±11.6 years (range, 30-83 years). Mean follow-up was 42.5±23.6 months (range, 24-106 months).

RESULTS

Fusion was achieved in 25 (83%) patients, after a mean of 7.5 months (range, 6-12 months). Of the 8 patients with severe bone loss (≤25% bone contact), 4 experienced non-union, compared to 1 of the 22 patients whose bone loss was moderate or mild (50% and >50% bone contact, respectively) (p=0.01). After at least 2 years of follow-up, the infection was eradicated in 28 (93%) patients. Complications occurred in 9 patients and consisted of pin-site infection managed by lavage (n=3), recurrent infection requiring revision surgery for debridement and lavage combined with material exchange and antibiotic therapy (n=2), and femoral shaft fracture (n=3) or traumatic fracture of the arthrodesis (n=1) treated by changing the clamp and fixator assembly.

DISCUSSION: The fusion rate achieved using this combined technique is high and better than obtained with external fixation alone. Our results confirm that infection eradication is obtained more often than with nailing. This one-stage, simple, reproducible procedure does not leave any foreign material in situ.

LEVEL OF EVIDENCE: IV, retrospective observational cohort study.