Cath Lab Digest

   The bunion deformity is one of the most common deformities that podiatric foot and ankle surgeons treat. As with other conditions, the conservative and surgical measures vary based on the patient’s expectations and the surgeon’s experience. Although there are limited conservative options available such as shoe modifications and prescription orthoses, most podiatric physicians would agree that surgical correction is often necessary for a symptomatic bunion deformity.

   While there are several considerations in choosing the appropriate surgical procedure, one should ultimately focus on achieving the greatest correction for the longest period of time. Although numerous types of procedures are at the surgeon’s disposal, factors such as patient compliance, health and occupation can all influence how one corrects the deformity. In addition, the more severe the deformity is, the greater the challenge of correction. Accordingly, let us review some key points on preoperative evaluation and surgical intervention for severe hallux valgus deformities.

   Multiple articles and texts have addressed the causes of bunion deformities. Over the past century, there seems to have been a shift from a focus on external causes such as shoe gear and activities to more intrinsic factors such as genetics and biomechanics of the lower extremity. In my training, I once heard that to be a good surgeon, one must also have a strong knowledge of biomechanics.

   In a sense, this is very true. Failure to address concurrent or contributing factors can doom a well-executed surgical intervention. Specific examples include metatarsus adductus, first ray hypermobility and a flexible pes planus deformity. Any of these conditions and numerous others may require more intervention than simply correcting the first ray and associated soft tissue structures.

   Accordingly, one should never underestimate biomechanics associated with bunion deformities. Ankle, subtalar, midtarsal and first ray range of motion directly affect the outcome of this type of surgery. In severe cases, ankle equinus may require concurrent correction via a gastroc recession or Achilles tendon lengthening. One may need to address abnormal pronation with an orthotic or possibly correct it with a separate surgery. In cases like these, the most difficult task is not the procedure itself but attempting to explain to the patient how the biomechanical issues directly affect the outcome of the bunion surgery and why the ancillary procedure(s) is necessary.

Essential Diagnostic Pointers

   Clinicians typically take radiographs with patients standing in their normal angle and base of gait. In many cases, the patient may alter his or stance due to pain from the bunion itself or pain from other causes such as subluxation of the second metatarsophalangeal joint. Be aware that even a slight adjustment on the part of the patient can alter the structural alignment on the radiograph.

   The anterior-posterior (AP) view enables the podiatric surgeon to evaluate the intermetatarsal angle, which is increased in cases of severe hallux valgus. When measuring this angle, one should also assess any concurrent metatarsus adductus. Adductus will clinically increase the intermetatarsal angle and can affect the procedure(s) required. The AP view also shows the position of the tibial sesamoid. The larger the deformity is, the greater lateral displacement of this sesamoid. In cases of a severe deformity, a lateral release may be insufficient and complete removal of the sesamoid may be required. The sesamoid-metatarsal complex may also be arthritic and surgical anatomic realignment may be impossible. This can also require sesamoid removal.