Maximum Plantarflexion Lateral Ankle Radiograph for Pre-Operative Planning for the Arthroscopic Treatment of Osteochondral Lesions of the Talus
Authors: Brohard Justin N. , Chin Kenneth M. 
Published: November 2022

Category:

Arthroscopy; Ankle; Sports; Trauma

Introduction/Purpose:

Osteochondral Lesions of the Talus (OLT) are now a commonly encountered pathology resulting in ankle pain and disability. Because of growing interest and support for arthroscopic management, it has become increasingly important to develop pre-operative evaluation methods to determine which lesions are amenable to standard arthroscopic evaluation and treatment versus the use of alternative strategies including posterior ankle arthroscopy, open arthrotomy, or malleolar osteotomy. Recently a CT scan protocol has been developed with the maximum ankle plantarflexion to estimate which lesions are accessible by standard anterior ankle arthroscopy based on the location of the lesion relative to the anterior tibial plafond. We present a simplified alternative method using a clinic-based lateral ankle radiograph with maximal plantarflexion to attain similar information for surgical planning.

Methods:

A 25-year-old female presented to clinic approximately 3 years after an initial injury to the left ankle sustained while skiing, with prior conservative treatment. After examination and review of available imaging, discussion was held with the patient regarding continued conservative management of her left ankle OLT versus surgical intervention with ankle arthroscopy, OLT debridement, and microfracture due to the lesion size of less than 150 mm2 based on previously described treatment algorithms. To determine the best approach for ankle arthroscopy, anterior versus posterior, a left ankle non-weight-bearing maximal plantar flexion radiograph was performed in the clinic. This showed that with plantarflexion, the anterior margin of the medial based OLT was adjacent to the anterior lip of the tibial plafond. Based on the clinical experience of the treating surgeon, this serves as an indication that the lesion can be adequately accessed using standard anterior ankle arthroscopy with plantarflexion and/or non- invasive distraction.

Results:

The patient underwent standard ankle anterior tibiotalar arthroscopy with non-invasive distraction. Following diagnostic arthroscopy and limited debridement, with the ankle manually plantarflexed by an assistant, the OLT leading edge was easily identified. The remaining joint was intact without cartilage injury. There was moderate synovitis noted anterior and medial. An arthroscopic shaver and curette was used to debride the unstable articular cartilage back to sharp, stable borders, and all loose cartilage fragments were removed from the joint. This left approximately 8 x 15 mm of exposed subchondral bone. The subchondral plate was intact without bone loss or evidence of collapse. Using an arthroscopic microfracture awl, several microfracture holes were created through the subchondral plate and into the underlying metaphyseal bone until marrow fat was identified. Postoperatively, she was non weight bearing for six weeks with range of motion as tolerated, and advanced to full activity at three months without residual symptoms.

Conclusion:

In the management of OLTs, the limits of anterior arthroscopy have been pushed with time, due to the added complexity and possible morbidity associated with posterior arthroscopy and medial malleolus osteotomies for an open approach. Many factors have an impact on the intraarticular access using anterior ankle arthroscopy, with the posterior talus being the most challenging site to access. As seen in this case presentation, this simple and cost-effective radiographic technique can be employed by the clinician, among other clinical and imaging tools, to help guide appropriate surgical technique for lesions in the posterior half of the talar body.