Comparison of Fixation Techniques in Oblique and Biplanar Chevron Medial Malleolar Osteotomies; a Finite Element Analysis

Comparison of two versus three-screw fixation for biplanar chevron medial malleolar osteotomy

PURPOSE

This study was designed to compare the clinical outcomes and complications of using two versus three screws to fix the biplanar chevron medial malleolar osteotomy (MMO).

PATIENTS AND METHODS

A retrospective review was conducted on 43 patients (46 ankles) who underwent biplanar chevron MMO to treat talus osteochondral lesions. Of these, MMO was fixed with two parallel screws placed perpendicular to the osteotomy plane in 16 ankles, while in the remaining 30 ankles, MMO was secured with two parallel screws plus an additional third screw inserted parallel to the tibial plafond. Patients were divided into two groups based on the fixation method and clinical outcomes, union and malunion rates, and complications were compared.

RESULTS

Demographic and clinical characteristics such as age (p: 0.411), gender distribution (p: 0.119), affected side (p: 0.126), lesion grades (p: 0.056), and lesion sizes (p: 0.310), immobilization (p: 0.119) and weight-bearing periods (p: 0.252) were statistically similar across both groups. Initial malreduction were observed in five cases within the three-screw group and one case in the two-screw group (p: 0.307). However, neither group exhibited any progressive step-off or gap in the follow-up radiographs, and osteotomy union was achieved in all patients. Delayed union was observed in one patient from the three-screw group. Significant improvements in American Orthopedic Foot and Ankle Society scores were observed in both groups, with no functional discrepancies evident at the final follow-up (p: 0.488).

CONCLUSIONS

The study found no significant differences in union rates, complications, or clinical outcomes between two and three-screw fixation methods for medial malleolar osteotomies (MMO). Both methods allowed for effective MMO fixation without loss or displacement post-surgery, suggesting their safety and efficacy.

LEVEL OF EVIDENCE

Level III, retrospective comparison.

To wedge or not to wedge; A cadaveric comparison study of two medial malleolar osteotomy modalities

OBJECTIVE

To quantify the surface area of the talus accessible with a uniplanar and a biplanar medial malleolus osteotomy. Our secondary purpose study is to quantify the amount of weightbearing area that each osteotomy effects on the tibial articular surface.

PATIENTS AND METHODS

Eight ankle joint specimens were dissected for this study. The uniplanar osteotomy was performed first. A K-wire marked the limits of access at two different angles: 90° and 30°. The boundaries were marked with a skin marker. Wedges were then created on the tibia plafond, and the osteotomy was converted into a biplanar one. Measurements were repeated again for this osteotomy. The talus, the tibial plafond, and the medial malleolus were then excised. Images were taken and then electronically calibrated for two-dimensional digital measurement of accessible areas. Areas of perpendicular and 30-degree access were recorded for both osteotomies. The articular surface of the tibia was also measured, and an area analysis was performed to calculate the amount of weightbearing cartilage removed by each osteotomy.

RESULTS

Almost the entire sagittal plane was accessible with both osteotomies. At a 30° angle, bone purchase was achieved for 67.7 % of the talar articular surface with the uniplanar osteotomy and for 74.8 % with the biplanar osteotomy. At a 90° angle, uniplanar osteotomy provided access to 32.7 % of the talar articular area, whereas the biplanar osteotomy achieved an average coverage of 52.8 %. The difference was statistically significant. On average, 25.3 % of the weightbearing area of the tibial plafond is affected when a biplanar osteotomy is performed.

CONCLUSION

Medial malleolar osteotomy provides varying degrees of access to the talar dome depending on how it is performed. A wedge-shaped biplanar osteotomy provides greater access and is therefore more suitable for defects located deeper on the talar dome. Despite providing wider access, it results in greater disruption of the weightbearing cartilage of the tibial plafond.

LEVEL OF EVIDENCE

Level V.

Medial oblique malleolar osteotomy for approach of medial osteochondral lesion of the talus

PURPOSE

The medial malleolar osteotomy is commonly performed to gain access to the medial talar dome for treatment of osteochondral lesions of the talus. The primary aim of this study was to assess osseous healing based on postoperative radiographs to determine consolidation, non-union and malreduction rates.

METHODS

Sixty-seven cases were reviewed where an oblique uniplanar medial malleolar osteotomy was performed to gain access to the medial talar dome for addressing an osteochondral lesion. Two, respectively three fully threaded 3.5 mm corticalis screws were used to fixate the osteotomy. Postoperative radiographs were reviewed to assess consolidation, non-union, malreduction and dislocation of the osteotomy.

RESULTS

Out of 67 patients, 66 patients had a consolidation of the osteotomy. 23.9% of the cases showed malreduction of the osteotomy. One patient suffered a non-union, which required a revision surgery. No significant difference was shown between two and three screws used for fixation in terms of malreduction and consolidation of the osteotomy. Eighty-four percent of the patients underwent hardware removal due to pain or medial impingement.

CONCLUSION

The oblique medial malleolar osteotomy is a safe and relatively simple procedure with a high consolidation rate and low revision providing excellent exposure of the talus. The moderately high malreduction rate and required hardware removal surgery by most of the patients are relevant factors which should be considered before performing this surgery.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.