Orthopedic Teaching Cases 2023, Jan, 18 | 12:00 am

Foot and Ankle cases 36

A 58-year-old woman comes to clinic reporting that her previous surgeon has performed two procedures on her foot and that she is quite unhappy. She brings with

her radiographs taken after her first operation (Fig. 5–72). You note a prior medial eminence resection and a recurrent hallux valgus deformity.

 

 

 

Figure 5–72 AP weight-bearing radiograph of the foot.

 

Which of the following is not associated with recurrent hallux valgus?

  1. Incomplete sesamoid reduction

  2. Inadequate correction of the IMA

  3. Fibular sesamoid excision

  4. Premature weight bearing

  5. Juvenile/adolescent patient

Discussion

The correct answer is (C). Fibular sesamoid excision, as described by McBride, is associated with the development of hallux varus and should be avoided. The remaining options are associated with recurrence. Optimally, the sesamoids will be positioned plantar to the crista as the valgus and pronation is corrected. The intermetatarsal angle (IMA) should be corrected to minimize the return of deforming forces across the first metatarsophalangeal joint (MTPJ). Premature weight bearing has been shown to increase the risk of recurrence. Hallux valgus correction in the young patient is notorious for its association with recurrence, with a rate of over 50% in some series.

You obtain new radiographs that show an opening wedge proximal first metatarsal osteotomy with now a hallux varus deformity (Fig. 5–73).

 

 

 

Figure 5–73 Weight-bearing AP radiograph of the foot.

 

What technical error is not associated with postoperative hallux varus?

  1. Excessive dorsiflexion at the osteotomy site

  2. Excessive plication of the medial capsule

  3. Fibular sesamoid excision

  4. Excessive medial eminence resection

  5. Lateral flexor hallucis brevis transection

 

Discussion

The correct answer is (A). Excessive dorsiflexion at the osteotomy site is associated with transfer metatarsalgia, not postoperative hallux varus. As the first ray is dorsiflexed, the distal lesser toes are exposed to increased postoperative pressure. The medial capsule should be provisionally imbricated with assessment prior to completion of the case. Excessive tightening of the medial capsule will result in varus. Fibular sesamoid excision has largely been abandoned due to its association with hallux varus. Medial eminence resection should be performed with a distal starting point medial to the sagittal sulcus. The cut should be completed in line with the medial cortex of the first metatarsal, taking care to avoid notching (Fig. 5–74).

 

 

 

Figure 5–74 AP weight-bearing radiograph of the foot with appropriate path of saw blade for medial eminence resection (line) with relationship to the sagittal sulcus (arrow).

 

Objectives: Did you learn...?

 

Assess the causes for postoperative recurrence and hallux varus after hallux valgus procedures?

 

CASE                               35                               

Dr. Thomas Dowd

A 40-year-old woman reports pain in her forefoot, especially when wearing dress shoes. She notes a shooting, electrical quality to the pain. Her pain improves with rest and unshod feet. You suspect that she has a Morton’s neuroma.

What physical examination finding best supports your suspicion?

  1. Positive drawer test at the second metatarsophalangeal joint (MTPJ)

  2. Pain with passive dorsiflexion at the first MTPJ

  3. Decreased sensation at the lateral second toe and medial third toe

  4. Pain and click with a plantarly applied, dorsally directed force at the third web space with simultaneous forefoot compression

Discussion

The correct answer is (D), which describes the Mulder’s click test (Fig. 5–75). Classically, a Morton’s neuroma occurs in the third web space, as branches from the medial and lateral plantar nerves join to form the interdigital nerve and are compressed between the surrounding metatarsals and the transverse metatarsal ligament (Fig. 5–76). A Morton’s neuroma may arise in the second web space or both the second and third web spaces. Reproduction of pain with Mulder’s click suggests a diagnosis of Morton’s neuroma. Drawer testing of the second MTPJ is important for assessing instability that is more commonly associated with plantar plate injury and MTPJ synovitis.

 

 

 

Figure 5–75 Photograph demonstrating the Mulder’s click test. This test involves compression of the metatarsals with a dorsally directed force between the third and fourth metatarsals.

 

 

 

Figure 5–76 Note the area of concern (gray circle) depicting compression of nerve (white lines) between the metatarsal heads just distal to the transverse metatarsal ligament (black lines).

 

Your patient states that she cannot tolerate this condition any longer and desires surgical intervention. She has not tried changing her footwear or trying any inserts. She is concerned with the location of her scar.

What initial treatment do you recommend?

  1. Neurolysis via a dorsal approach

  2. Neurectomy via a dorsal approach

  3. Shoewear modification and the use of a metatarsal pad

  4. Metatarsal osteotomy to decompress the neuroma

  5. Neurectomy via a plantar approach

 

Discussion

The correct answer is (C). Treatment of a Morton’s neuroma is initially nonoperative. Conservative treatment consists of shoewear modification, metatarsal pad placement, and NSAID use. Diagnostic and therapeutic injections may also be performed in the region of the affected nerve. If the aforementioned measures fail, primary surgical treatment of this disorder typically consists of release of the transverse metatarsal ligament with neurectomy via a dorsal approach. Some reports have demonstrated promising results with neurolysis. Plantar approaches are typically reserved for recurrent or refractory cases that have failed intervention employing a dorsal incision. The nerve is subcutaneous relative to the plantar skin and is more readily accessed through a plantar approach. In cases with involvement of adjacent nerves, a transverse plantar approach may be advantageous.

Despite the use of a metatarsal pad and shoewear modifications, your patient has persistent pain and undergoes a neurectomy via a dorsal approach. You send the excised tissue to the pathologist for histologic evaluation.

What is the characteristic finding associated with Morton’s neuroma?

  1. Proliferative synovitis

  2. Reed Sternberg cells

  3. Demyelinated nerve

  4. Perineural fibrosis

  5. Angiofibroblastic hyperplasia

 

Discussion

The correct answer is (D). This would suggest that the term “neuroma” is a misnomer. Nevertheless, use of the term continues for ease of communication. Proliferative synovitis is associated with several diagnoses, including rheumatoid arthritis, pigmented villonodular synovitis, and giant cell tumor of tendon sheath. Demyelinated nerve is seen peripherally with conditions such as Charcot–Marie–Tooth and Guillain–Barré syndrome. Angiofibroblastic hyperplasia was coined by Nirschl to describe pathologic changes associated with lateral epicondylitis (tennis elbow).

 

Objectives: Did you learn...?

 

 

Describe anatomic considerations that contribute to location of pathology? Identify histologic finding classically seen with Morton’s neuroma?

 

Describe nonsurgical treatment options and recommendations?

 

Discuss options for surgical intervention and when to consider plantar and dorsal approaches?