Varus Ankle Arthritis: A Modified Operation with a Novel Osteotomy and Lateral Hinge Plate Fixation Technique
Ankle arthritis is a debilitating condition characterized by the degeneration of articular cartilage, often accompanied by pain, decreased mobility, and varus deformity. Supramalleolar osteotomy has emerged as a reliable surgical technique for treating ankle arthritis, particularly in cases where varus deformity is present. This procedure aims to correct deformities at the distal tibia, normalize the load-bearing axis, reduce abnormal compression on the articular cartilage, alleviate pain, and improve overall functionality. However, traditional supramalleolar osteotomy techniques have several limitations, including the need for frequent intra-operative fluoroscopy, restrictions on early exercise or weight-bearing, and the risk of contralateral cortical bone separation during the distraction of the tibia after osteotomy.
The separation of the lateral cortex during osteotomy can lead to significant complications. Studies have shown that fractures or disruptions of the lateral cortex can result in instability at the osteotomy site, loss of angular correction, implant failure, delayed union, and even non-union of the osteotomy. To address these shortcomings, a modified osteotomy technique has been developed, incorporating a pre-shaped plate and a novel osteotomy approach. This technique aims to enhance the stability of the osteotomy, reduce the risk of complications, and improve patient outcomes.
Patient Selection and Evaluation
The study retrospectively reviewed patients admitted to the hospital for varus ankle arthritis over a four-year period. Sixteen patients, with an average age of 57.7 years, met the selection criteria and were included in the study. The average follow-up period was 23 months. Ankle function was evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, while the degree of deformity was assessed using the tibial articular surface angle (TAS). The correction of deformity was calculated based on the height of the wedge (H), which was determined by the desired degree of correction (a) and the diameter of the distal tibia (W).
Surgical Technique
All patients underwent the modified osteotomy procedure under general anesthesia in a supine position. The surgical technique involved the following steps:
Step 1: Anterolateral Incision and Joint Debridement
A 4 cm longitudinal incision was made at the anterolateral aspect of the ankle. The lateral part of the ankle joint was exposed, and the anterior and lateral osteophytes and synovium within the articular cavity were cleaned. This step aimed to reduce bone and soft tissue impingement, thereby increasing the range of motion.
Step 2: Placement of the Pre-Shaped Plate and Osteotomy Planning
A three-hole plate, pre-shaped to match the desired degree of correction, was placed close to the syndesmosis. The screws were semi-tightened to secure the plate. The osteotomy plane was then determined by positioning a Kirschner wire from the central hole of the plate, oriented 4.5 cm proximal to the medial malleolar tip. Based on the Kirschner wire, an 8 cm medial tibia skin incision was made longitudinally, and the periosteum was gradually separated. The medial part of the ankle was exposed, and the articular cavity was cleaned.
Step 3: Osteotomy and Wedge Insertion
The osteotomy was performed using a wide swing saw along the Kirschner wire. The osteotomy was stopped when the saw was approximately 5 mm from the lateral cortex, which was directly observed through the anterolateral incision. The Kirschner wire was then removed, and the patient’s leg was adjusted to the appropriate angle. After the osteotomy was opened, a wedge-shaped graft, harvested from the iliac crest, was inserted into the space. The screws of the lateral plate were tightened for preliminary fixation. The alignment of the ankle was checked and adjusted to the desired position using fluoroscopy. Finally, the medial tibia was stabilized with a locking plate.
Advantages of the Modified Technique
Compared to traditional osteotomy techniques, the modified approach offers several advantages. The use of a lateral hinge plate effectively prevents the separation of the lateral cortex, while the dual-plate structure provides better initial stability against separating and revolving movements. This reduces the risk of complications such as non-union and delayed union. Additionally, the osteotomy position is determined from the lateral side to the medial side, allowing for accurate observation of the osteotomy position and depth through the anterolateral incision without the need for frequent X-ray fluoroscopy.
The modified osteotomy technique does not require additional incisions, as the anterolateral incision is sufficient for joint debridement and exposure of the lateral plate. The lateral plate is set under direct vision, and the osteotomy plane is determined innovatively from the lateral to the medial tibia, ensuring accurate location and reducing the use of fluoroscopy. The dual-plate osteosynthesis provides better initial stability, further minimizing complications. Moreover, the lateral plate used in this modified operation is an ordinary plate, making it accessible for most hospitals.
Clinical Outcomes
The follow-up results demonstrated that patients undergoing the modified osteotomy had significant improvements in pain relief, functional enhancement, and restoration of proper weight-bearing alignment. The modified osteotomy technique achieved excellent results in the early follow-up period, suggesting its potential for broader application in the treatment of varus ankle arthritis.
Conclusion
The modified osteotomy technique with a pre-shaped plate and lateral hinge plate fixation offers a promising approach to the treatment of varus ankle arthritis. By addressing the limitations of traditional supramalleolar osteotomy, this technique enhances the stability of the osteotomy, reduces the risk of complications, and improves patient outcomes. The use of an ordinary lateral plate makes this technique accessible to a wide range of hospitals, further supporting its potential for broader adoption. The positive early follow-up results underscore the effectiveness of this modified approach, making it a valuable option for patients with varus ankle arthritis.
doi.org/10.1097/CM9.0000000000000558
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