Distal tibial oblique osteotomy for reconstruction of ankle joint congruity and stability

Biomechanical Effect of Distal Tibial Oblique Osteotomy: A Preliminary Finite-Element Analysis

BACKGROUND

The biomechanical effect of distal tibial oblique osteotomy (DTOO) on osteoarthritic ankles has not been investigated. Using finite element (FE) models, we aimed to elucidate the effect of DTOO on the ankle contact pressure (CP) distribution.

METHODS

This study included two patients with ankle osteoarthritis who underwent DTOO and one asymptomatic control. Patient-specific FE models were reconstructed by matching standing radiographs with supine computed tomography scans. The joint contact area (CA) and maximum CP on the articular surface of the talus were calculated before and after DTOO and compared with those of the control.

RESULTS

In the control, the CA was 584 mm2 and the maximum CP was 2.6 MPa. In case 1, the CA increased by 125% from 166 mm2 preoperatively to 375 mm2 postoperatively, accompanied by a 36% decrease in the maximum CP from 9.8 MPa to 6.3 MPa. Similarly, in case 2, the CA increased by 46% from 301 mm2 to 439 mm2, accompanied by a 27% decrease in the maximum CP from 6.7 MPa to 4.9 MPa.

CONCLUSIONS

This study suggests DTOO improves the biomechanics of the ankle, but not sufficiently compared to the control. This analytical approach may enhance understanding of ankle pathophysiology and assist in the design of the ideal corrective osteotomy.

Supramalleolar osteotomies for ankle arthritis: a systematic review

INTRODUCTION

We investigated the mid-term outcomes of supramalleolar osteotomies regarding "survivorship" [before ankle arthrodesis (AA) or total ankle replacement (TAR)], complication rate and adjuvant procedures required.

MATERIAL AND METHODS

PubMed, Cochrane and Trip Medical Database were searched from January 01, 2000. Studies reporting on SMOs for ankle arthritis, in minimum of 20 patients aged 17 or older, followed for a minimum of two years, were included. Quality assessment was performed with the Modified Coleman Methodology Score (MCMS). A subgroup analysis of varus/valgus ankles was performed.

RESULTS

Sixteen studies met the inclusion criteria, with 866 SMOs in 851 patients. Mean age of patients was 53.6 (range 17-79) years, and mean follow-up was 49.1 (range 8-168) months. Of the arthritic ankles (646 ankles), 11.1% were classified as Takakura stage I, 24.0% as stage II, 59.9% as stage III and 5.0% as stage IV. The overall MCMS was 55.2 ± 9.6 (fair). Eleven studies (657 SMOs) reported on "survivorship" of SMO, before arthrodesis (2.7%), or total ankle replacement (TAR) (5.8%) was required. Patients required AA after an average of 44.6 (range 7-156) months, and TAR after 36.71 (range 7-152) months. Hardware removal was required in 1.9% and revision in 4.4% of 777 SMOs. Mean AOFAS score was 51.8 preoperatively, improving to 79.1 postoperatively. Mean VAS was 6.5 preoperatively and improved to 2.1 postoperatively. Complications were reported in 5.7% (44 out of 777 SMOs). Soft tissue procedures were performed in 41.0% (310 out of 756 SMOs), whereas concomitant osseous procedures were performed in 59.0% (446 out of 756 SMOs). SMOs performed for valgus ankles failed in 11.1% of patients, vs 5.6% in varus ankles (p < 0.05), with disparity between the different studies.

CONCLUSIONS

SMOs combined with adjuvant, osseous and soft tissue, procedures, were performed mostly for arthritic ankles of stage II and III, according to the Takakura classification and offered functional improvement with low complication rate. Approximately, 10% of SMOs failed and patients required AA or TAR, after an average of just over 4 years (50.5 months) after the index surgery. It is debatable whether varus and valgus ankles treated with SMO reveal different success rates.