Biomechanical in vitro - stability testing on human specimens of a locking plate system against conventional screw fixation of a proximal first metatarsal lateral displacement osteotomy

Locking plate versus retrograde intramedullary nail fixation for tibiotalocalcaneal arthrodesis: A retrospective analysis

BACKGROUND

Tibiotalocalcaneal arthrodesis (TTCA) surgery is indicated for the end-stage disease of the tibiotalar and subtalar joints. Although different fixation technique of TTCA has been proposed to achieve high fusion rate and low complication rate, there is still no consensus upon this point. The purpose of this study is to compare the clinical efficacy of retrograde intramedullary nail fixation (RINF) and locking plate fixation (LPF) for TTCA.

MATERIALS AND METHODS

Fifty four patients who underwent TTCA through the lateral approach with lateral fibular osteotomy using RINF (32 patients, 18 male/14 female, mean age: 48) or LPF (22 patients, 12 male/10 female, mean age: 51) between January 2007 and January 2010 were retrospectively analyzed. Demographic and clinical characteristics, surgery (operation time, blood loss) outcomes (postoperative fusion rates, visual analog scale and foot and ankle surgery score and complications) were compared.

RESULTS

The LPF group had a shorter operation time (72.3 ± 9.2 vs. 102.8 ± 11.1 min, P < 0.001), less blood loss (75.9 ± 20.2 vs. 140.0 ± 23.8 ml, P < 0.001) and less intraoperative fluoroscopy sessions (3.6 ± 0.9 vs. 8.4 ± 1.3, P < 0.001) than the RINF group. Patients were followed up for 12-24 months (mean of 16.2 months). Both groups had similar postoperative fusion rates (90.6% and 95.4%) and the LPF group showed a nonsignificant lower complication rate (18.2% vs. 28.1% respectively). Patients at higher risk on nonunion due to rheumatoid diseases may have a lower nonunion rate with LPF than RINF (one out of eight vs. three out of nine, P < 0.001).

CONCLUSIONS

The LPF for TTCA was simpler to perform compared with RINF, but with similar postoperative outcomes and complication rates.

Biomechanical analysis of two fixation methods for proximal chevron osteotomy of the first metatarsal

PURPOSE

The proximal chevron osteotomy provides high correctional power. However, relatively high rates of dorsiflexion malunion of up to 17 % are reported for this procedure. This leads to insufficient weight bearing of the first ray and therefore to metatarsalgia. Recent biomechanical and clinical studies pointed out the importance of rigid fixation of proximal metatarsal osteotomies. Therefore, the aim of the present study was to compare biomechanical properties of fixation of proximal chevron osteotomies with variable locking plate and cancellous screw respectively.

METHODS

Ten matched pairs of human fresh frozen cadaveric first metatarsals underwent proximal chevron osteotomy with either variable locking plate or cancellous screw fixation after obtaining bone mineral density. Biomechanical testing included repetitive plantar to dorsal loading from 0 to 31 N with the 858 Mini Bionix(®) (MTS(®) Systems Corporation, Eden Prairie, MN, USA). Dorsal angulation of the distal fragment was recorded.

RESULTS

The variable locking plate construct reveals statistically superior results in terms of bending stiffness and dorsal angulation compared to the cancellous screw construct. There was a statistically significant correlation between bone mineral density and maximum tolerated load until construct failure occurred for the screw construct (r = 0.640, p = 0.406).

CONCLUSION

The results of the present study indicate that variable locking plate fixation shows superior biomechanical results to cancellous screw fixation for proximal chevron osteotomy. Additionally, screw construct failure was related to levels of low bone mineral density. Based on the results of the present study we recommend variable locking plate fixation for proximal chevron osteotomy, especially in osteoporotic bone.