The Evans osteotomy is a surgical procedure aimed at correcting flatfoot deformities. It is especially useful in treating adult cases of pes planus, which is the medical term for flat feet. This surgery involves making an incision in the heel bone, specifically the calcaneus, to lengthen the lateral column of the foot. This procedure restores the proper alignment of the foot, improving both function and comfort for those suffering from this condition.
Understanding Flatfoot Deformity
Flatfoot deformity, commonly referred to as pes planus, can be caused by a variety of factors, such as genetics, injuries, or disease. The most noticeable sign of flatfoot is the collapse of the arch of the foot, which can result in pain and difficulty in walking or standing for extended periods. In some cases, this deformity leads to other complications such as misalignment of the ankle and knee, leading to further joint issues.
What is the Evans Osteotomy?
Originally described by Dr. Dillwyn Evans in 1975, the Evans osteotomy was designed to treat pediatric flatfoot. However, over time, it has evolved into a key surgical procedure for addressing flatfoot in adults as well. The surgery involves creating an “opening wedge” in the calcaneus bone to lengthen the lateral column of the foot. By doing so, it effectively corrects the misalignment of the foot, restores a functional arch, and helps to alleviate pain caused by the deformity.
Why the Evans Osteotomy is Important
In cases of adult flatfoot, traditional treatments such as shoe modifications, orthotics, and physical therapy may not provide sufficient relief. In such instances, the Evans osteotomy offers a more permanent solution. It directly addresses the structural causes of the deformity by altering the shape of the heel bone. This is particularly beneficial in adults who have not responded to conservative treatments.
Moreover, the procedure can be used to correct flatfoot deformities caused by other factors, such as tendon dysfunction or trauma. By addressing the underlying structural issues, the surgery improves overall foot function, mobility, and reduces discomfort.
Key Surgical Considerations
The Evans osteotomy is a relatively safe procedure, but as with all surgeries, it comes with certain risks. The success of the surgery depends significantly on the patient’s individual anatomy, the severity of the deformity, and the surgeon’s experience. Preoperative assessment is critical to determine if the procedure is appropriate.
The foot must exhibit flexibility for the procedure to be effective. Any rigidity in the foot can significantly reduce the amount of correction achieved. Additionally, patients need to be examined for other underlying conditions such as tarsal coalitions or hindfoot arthritis, which may contraindicate the surgery.
The Evans procedure is particularly effective when performed on patients with flexible flatfoot deformities, characterized by a misalignment of the heel bone (calcaneal valgus), forefoot abduction, and peritalar subluxation (partial dislocation of the joints in the foot).
The Surgical Procedure
The surgery is performed through a carefully planned incision, typically starting 1 cm distal to the lateral malleolus (the bony prominence on the outside of the ankle). The surgeon then accesses the calcaneus and makes a cut, or osteotomy, at the base of the anterior superior process of the calcaneus. This cut is made to lengthen the lateral column of the foot, which realigns the foot and helps to restore its natural arch.
During the procedure, care is taken to protect the surrounding soft tissues, including the peroneal tendons and sural nerve, which are at risk during the osteotomy. To ensure proper alignment and prevent complications such as nonunion (failure of the bone to heal), the surgeon may use bone grafts to stabilize the osteotomy site. Autografts (grafts from the patient’s own body) or allografts (donor bone) can be used depending on the patient’s needs.
Postoperative Care and Recovery
Following the procedure, the patient is placed in a non-weight-bearing cast to protect the surgical site and allow for proper healing. The patient will initially be kept off their foot for several weeks to ensure that the bone graft integrates and the osteotomy site heals effectively.
After the initial period, the patient gradually increases weight-bearing and is eventually transitioned to wearing regular shoes, though high-impact activities should be avoided for up to six months to ensure full recovery.
Complications and Risks
While the Evans osteotomy has a relatively low complication rate, there are still risks associated with the procedure. Some of the most common complications include:
Delayed union or nonunion: The bone may take longer to heal than expected, or it may not heal properly.
Avascular necrosis: Insufficient blood supply to the calcaneus can result in bone death.
Nerve injury: Damage to the surrounding nerves, such as the sural nerve, can cause sensory issues.
Subluxation: The distal fragment of the calcaneus may shift out of place during the healing process, requiring further intervention.
Stress fractures: In some cases, a stress fracture may develop in the fifth metatarsal during recovery.
However, with careful planning, precise surgical technique, and diligent postoperative care, these complications can be minimized.
Conclusion: Why Consider the Evans Osteotomy?
For adults suffering from flexible flatfoot deformities, the Evans osteotomy presents an effective and long-term solution. By addressing the root cause of the condition—structural misalignment—it provides relief from pain, improves mobility, and helps patients regain a functional and comfortable foot. While the procedure carries some risks, these can be minimized with proper patient selection and skilled surgical technique.
As one of the most proven methods for treating adult flatfoot, the Evans osteotomy remains an invaluable tool for orthopedic surgeons and podiatrists alike. With its relatively low complication rate and ability to significantly improve foot function, it continues to be an essential procedure for those who have not found relief through conservative treatments.
