SLR - December 2019 - Tyler R. Tewilliager
Reference: Stodle AH, Molund M, Nilsen F, Hellund JC, Hvaal K. Tibial Nerve Palsy After Lateralizing Calcaneal Osteotomy. Foot and Ankle Specialist. 2019 Oct; 12(5):426-431Scientific Literature Review
Reviewed By: Tyler R. Tewilliager, DPM
Residency Program: Grant Medical Center – Columbus, OH
Podiatric Relevance: Lateralizing calcaneal osteotomies (LCOs) are common procedures utilized in cavus reconstructions. There are many well-known complications including over- or undercorrection, sural nerve injury, and risk to the medial structures with completion of the osteotomy. There is a lack of literature evaluating tibial nerve palsy after LCOs and may be more common than previously reported. Better understanding of how the tibial nerve and the tarsal tunnel are affected after LCO will help shape post-operative expectations for patient education.
Methods: Fifteen patients (18 feet) who previously underwent LCO were evaluated retrospectively. None of the patients included had previous hindfoot arthrodesis or known Charcot Marie Tooth Disease. A typical lateral approach was performed with lateral translation of the posterior tuber of the calcaneus without a closing wedge on all 18 feet. All patients post-operatively underwent clinical exams via monofilament, Tinel sign and dorsiflexion-eversion test as well as a CT scan to evaluate tarsal tunnel volume. To calculate the tarsal tunnel volume, the authors also post-operatively evaluated the non-operative limb in comparison to the operative limb.
Results: Of the 18 feet, which underwent LCO, at a mean follow up of 51 months, three (17 percent) had reduced sensation in the plantar foot and four (22 percent) feet demonstrated a positive Tinel sign. Of the patients who had symptoms of tibial nerve palsy, the average shift was 5.8 millimeters. In the asymptomatic patients, the average lateralizing shift was 5.6 millimeters. All patients undergoing LCO did have a reduction in tarsal tunnel volume compared to the non-operative limb by a mean of 10.2 percent overall. In the group without deficit, a 10.5 percent volume reduction was noted in comparison to a 9 percent volume reduction in neurologically intact patients.
Conclusions: The authors of this study found a moderately high risk of tibial nerve palsy following LCO but were not able to show the association with decreased tarsal tunnel volume as the greatest reduction was actually seen in the asymptomatic cohort. Also, there was no correlation between the amount of shift or location of the osteotomy from the posterior STJ to the development of tibial nerve palsy. The authors noted a number of factors that could contribute to tibial nerve palsy when performing a LCO such as saw blade or osteotome injury, traction and compression by the shift itself. However, it is still unclear what the main mechanism is. It is important to understand and convey to patients that there is a moderate risk in having some form of tibial nerve palsy following an LCO, which will help them make an informed decision on undergoing this operation. Some of the weaknesses of this study are a small patient population and lack of objective nerve studies in the diagnosis of tibial nerve palsies. Further investigation into the direct cause of these injuries is warranted.