SLR - December 2020 - Pedro Aldape

Minimally Invasive Plate Osteosynthesis (Mipo) Versus Open Reduction and Internal Fixation (Orif) in the Treatment of Distal Fibula Danis-Weber Types B and C Fractures

Reference: Marazzi C, Wittauer M, Hirschmann MT, Testa EA. Minimally invasive plate osteosynthesis (MIPO) versus open reduction and internal fixation (ORIF) in the treatment of distal fibula Danis-Weber types B and C fractures. J Orthop Surg Res. 2020 Oct 22;15(1):491. doi: 10.1186/s13018-020-02018-5. PMID: 33092616.

Level of Evidence: 3 Retrospective comparative case series

Scientific Literature Review

Reviewed By: Pedro Aldape, DPM
Residency Program:
Chino Valley Medical Center - Chino, CA 

Podiatric Relevance: The standard approach for open reduction with internal fixation (ORIF) of the fibula is associated with wound complications due to the thin, soft tissue layer around the lateral malleolus, especially in high risk populations. In the past decade, minimally invasive plate osteosynthesis (MIPO) has emerged as an alternative to traditional ORIF to lower wound complications while maintaining good reduction and fusion of the fracture site. The authors sought to compare the two different approaches to improve on the evidence in support of MIPO for ankle fracture fixation. 

Methods: This retrospective study compared a total of 70 patients divided into two equal groups. Group A underwent a traditional ORIF and group B underwent a MIPO approach. Patients included had a Danis Weber B or C ankle fracture and were excluded if the trauma involved a complex pilon fracture, Maisonneuve fracture, bilateral leg fractures, or had previous surgery for the same ankle. Surgical technique involved a standard approach for the ORIF group with a 1/3 tubular plate, 1/3 tubular locking compression plate (LCP), or sidewinder plate per surgeon preference. The MIPO group underwent a 2 centimeter curvilinear incision centered at the tip of the lateral malleolus where a LCP 1/3 tubular plate was inserted subcutaneously using a locking guide as a grip. The proximal end of the plate was identified, and a second 2 centimeter incision was made to center the plate over the fibula with another locking guide to use as a grip. An interfragmentary screw was inserted percutaneously and then the plate was set with locking screws. The outcomes measured were VAS pain scores, complications such as nonunion or other wound complications, operative time, and radiological outcomes for a 12 month follow up.

Results: The overall complication rate was significantly smaller in the MIPO group (14 percent vs 27 percent). Skin necrosis, nonunion, infections, wound healing disorders and post-operative pain were also higher in the ORIF group but did not reach significance. Radiologically, the tibio-fibular overlap was significantly lower in the ORIF group (2.7 millimeters vs 3.3 millimeters). The talar tilt, talocrural angles, medial and lateral clear spaces were found to be equivalent.

Conclusions: The MIPO technique significantly improved on complication rates for Weber B and C fractures. Along with improved wound complication rates, there was an increase in union rate and no difference in the radiological outcomes. The current literature on MIPO for ankle fractures is scarce and limited to a few case studies and this study adds to the promising outcomes for the MIPO technique. However, it is limited in its small sample size and short follow up. Although the authors found the OR time to be improved with MIPO (66 minutes vs 83 minutes), it could be argued that a surgeon with less experience in minimally invasive approaches may take longer to perform this technique. The study also lacks functional outcomes which would demonstrate the effectiveness of the technique. A prospective comparative study with a larger sample size and longer follow-up period which will allow for functional outcomes would provide important information for foot and ankle surgeons. Further, assessment of superficial personal nerve injury would prove to be helpful in determining if MIPO is preferred over traditional ORIF. Additionally, stratification of patient by host factors would be a prudent point of discussion. 

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