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18-08-2011 | Surgery | Article

MTP-1 joint replacement surgery corrects gait, relieves pain


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MedWire News: Preliminary results suggest that total replacement of the first metatarsophalangeal (MTP-1) joint can help achieve a normal gait and significant reduction in pain.

The research, published in the journal Foot and Ankle Surgery, describes the outcome of 12 patients with unilateral hallux rigidus and osteoarthritis of the MTP-1 joint who received a Roto-Glide1 prosthesis (Implants International, UK) and were followed-up for at least 12 months.

Eva Wetke (Frederiksberg Hospital, Denmark) and co-workers hypothesized that the prosthesis would alter the patients' gait, causing medialization of the ground reaction force (GRF) of the foot. In turn, this would cause bone mineral density (BMD) to increase in the medial metatarsal bones but decrease in the lateral metastarsal bones.

The researchers examined BMD and pedobarography for the heel bone and metatarsal heads at least 12 months before and after the procedure.

Patients reported a significant decrease in pain after surgery, with their mean visual analog scores falling from 7.9 to 2.1 on a 10-point scale.

The GRF under the lateral column decreased by a significant 43% in the operated feet but there was no significant change in medial and central forefeet.

Before surgery, patients had significantly lower BMD in the second metatarsal head in the affected foot than their healthy foot, but postoperative examination revealed no significant difference between the feet.

Noting there was no significant increase in BMD of the second metatarsal head, the researchers say this decline may be due to age-related bone loss.

BMD significantly decreased in the fifth metatarsal of the operated foot, which Wetke et al say supports the hypothesis of reduced load on the lateral column of the operated foot.

But as bone loss was significantly below 5% in the heel of both affected and non-affected feet and the non-affected fifth metatarsal, the team suggests that BMD may have been preserved in the patients due to increased load.

In particular, patients may have increased GFR on both heels after surgery due to improved pain on walking. Bone loss on the lateral side of the affected foot and preservation on the non-affected fifth metatarsal indicates that the patients' gait may have normalized, say the researchers.

"The achieved pain reduction and normalization of GRFs is in favor of the Roto-Glide1 prosthesis as a possible solution for severe MTP-1 osteoarthritis," Wetke et al conclude.

Nevertheless, they caution: "Long-term clinical results, however, must be awaited."

By Lynda Williams

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