Treating Metatarsus Adductus Deformity In A Patient With Uncontrolled Diabetic Neuropathy

Comparing open versus minimally invasive procedures, these authors discuss whether reconstructing a non-compensating metatarsus adductus deformity is appropriate in a 52-year-old patient with a history of neuropathic ulcerations.

A 52-year-old female presented with a history of neurotrophic ulceration in the sub-hallux area, secondary to an underlying severe metatarsus adductus deformity with focally increased pressure in the hallux. She has tried custom-made shoes without success in relieving the pressure. A patellar tendon bearing brace or indefinite immobilization was not practical due to her age and activity level.

The patient’s medical history consists of uncontrolled type 2 diabetes with peripheral neuropathy, chronic pain syndrome, hypertension and hyperlipidemia. Her medications include hydrocodone, meloxicam (Mobic, Boehringer Ingelheim), glipizide (Glucotrol, Pfizer), lisinopril (Prinivil, Merck), gabapentin (Neurontin, Pfizer), cholecalciferol and amitriptyline (Elavil). She is allergic to metformin and wears a transdermal nicotine patch. She has been smoking a few cigarettes per day for the last 20 years but does not drink alcohol or use recreational drugs. Her past surgical history is only significant for a breast biopsy. The patient's parents had diabetes and hypertension as well as a metatarsus adductus deformity. She is 5 feet, 7 inches and weighs 247 pounds with a body mass index (BMI) of 39 kg/m². Her chronic pain is in the feet and back.

A physical examination reveals a 1 cm-diameter neurotrophic, full-thickness ulceration in the plantar aspect of both halluces. The ulcers do not probe to the tendon or bone. The border of the ulcers is hyperkeratotic and the base is granular. Pedal pulses are palpable but protective sensation is absent up to the midfoot, as evidenced by testing with the 10-gram monofilament. The deformity is not reducible although the first metatarsophalangeal joint’s (MPJ) range of motion is within normal limits (65 degrees of dorsiflexion and 20 s of plantarflexion). The metatarsus adductus deformity has minimal to no compensation at the midfoot. No equinus deformity is present.

The gait examination shows a slightly increased angle of gait (18 degrees abducted). The peak plantar pressure goes lateral during the stance phase but returns back all the way to the medial aspect of the foot before passing through the hallux during toe-off. In static stance, there is a disproportional increase in pressure in the hindfoot. Plain radiographs show deformities that are consistent with the clinical examination. There are multiple metatarsal fractures in rays three to five and dorsal osteophytes are present at the tarsometatarsal joint level.

Comparing Techniques And Outcomes Of Open And Minimally Invasive Procedures For The Patient

We treated the patient with conservative measures and local wound care for a few months. However, she was admitted to the hospital for cellulitis in the right hallux from the chronic open wound. At this point, we decided that the current conservative measures were not necessarily safer than the surgical options. We both agreed to be more aggressive in treating these neurotrophic ulcers. After the cellulitis resolved, the patient stopped smoking and her diabetes became more manageable. At this time, we discussed and scheduled reconstruction of the deformity.

We performed an open correction of the metatarsus adductus deformity in the right foot via pan metatarsal osteotomies through two longitudinal incisions of approximately 15 cm. The patient subsequently developed post-surgical wounds on both dorsal incisions. With local wound care, the dorsal wounds healed six months after surgery. The bone healing took even longer: Radiographic healing did not occur until eight months after the surgery. During these months, the patient was non-weightbearing and she filed for short-term disability.

At the one-year follow-up, the patient was completely recovered and the ulcer resolved. The patient was satisfied with the result and requested the same procedure for the contralateral side.

For the left foot, we took a different approach. Instead of making two long dorsal incisions, we used a minimally invasive approach. We created a stab incision over each metatarsal shaft and performed an oblique osteotomy using a skinny, sagittal saw from dorsal distal to plantar proximal, exiting distal to the tarsometatarsal joint. After performing osteotomies of all the metatarsals, we abducted the forefoot to achieve a clinically acceptable alignment and employed temporary fixation with K-wires.

After correcting the deformity, we slid a locking plate with a tapered leading edge over the shaft of each metatarsal over the periosteum. In order to avoid compression of the periosteum and a large skin incision, we inserted locking screws through stab incisions, similar to the technique surgeons often use with minimally invasive percutaneous/plate osteosynthesis in the treatment of malleolar fractures. We reapproximated the stab incisions with 3-0 Prolene (Ethicon) without deep stitches.

This time, the patient did not have any postoperative wound healing or bone healing complications. The patient also benefited from less edema and pain postoperatively. She was back in regular shoegear (non-custom-made) in four months.

Assessing The Advantages Of Minimally Invasive Percutaneous Plate Osteosynthesis

Minimally invasive percutaneous plate osteosynthesis is mainly in use in fracture management, especially in higher-risk patients to minimize operative trauma. It improves all aspects of AO principles. The technique allows reduction with stability and without significant disruption of the blood supply, hence allowing earlier mobilization or weightbearing.

In the lateral malleolar reduction, one can make an incision distal to the lateral malleolus, creating a tunnel over the periosteum that is lateral to the lateral malleolus along the fibular shaft. Then slip a plate into the tunnel and fixate it to the distal fragment. After fixating the plate onto the lateral malleolus by inserting screws through the stab incisions, reduce the lateral malleolus to the anatomical alignment and fixate the plate onto the proximal fragment via locking screws, also through stab incisions. Utilize locking screws to avoid compression of the plate on the periosteum and achieve angular stability.

We applied a similar minimally invasive percutaneous plate osteosynthesis technique for this metatarsus adductus correction, treating each metatarsal as a surgeon-induced fracture. This allowed us to preserve blood supply, resulting in better wound and bone healing. With quicker bone healing and no wound complications, the patient was able to bear weight and go back to regular activity without significant deconditioning.

What The Literature Reveals

In 2010, Collinge and Protzman presented 38 cases of distal fibular fracture treated with the minimally invasive percutaneous plate osteosynthesis technique.¹ They found acceptable reduction in all but one patient, and all received good to excellent outcomes with the Olerud and Molander Ankle Scoring System, the SF-36 and the AOFAS Ankle-Hindfoot Score after at least two years of follow-up. The revision rate was 5 percent.

Iacobellis and colleagues compared 18 open reduction and internal fixations (ORIF) with 18 minimally invasive percutaneous plate osteosynthesis on Weber B ankle fractures.² They found wound healing complications in five ORIFs versus none in the minimally invasive percutaneous plate osteosynthesis group. The mean Olerud and Molander Ankle Score was also better in the minimally invasive group (96 points) versus the ORIF group (87 points) postoperatively. Even though this was not a randomized clinical trial, the selection bias should be against the minimally invasive group since the surgeons would more likely opt for minimally invasive percutaneous/plate osteosynthesis on higher risk patients.

Reviewing Other Pertinent Considerations With Minimally Invasive Percutaneous/Plate Osteosynthesis

A disadvantage to this technique, when one applies it to the metatarsal osteotomy, is that the procedure is technically more difficult. It can take longer to perform if a surgeon is not familiar with this technique from malleolar fractures.

Also bear in mind that this technique requires the locking plate-screw construct to avoid periosteal compression or disruption of the blood supply. Therefore, the cost is significantly higher than using conventional screws or screws with a plate. However, in high-risk patients, avoiding postoperative complications should justify the cost. To our knowledge, there is no study evaluating the cost-benefit of this technique versus the conventional technique in literature.

Finally, avoiding extensor tendons can be difficult. Since one places the plate over the periosteum, the fixation can be directly under the long extensor tendons. One can “cheat” plate placement medially or laterally to avoid gliding of the tendons right over the plate. Though this is clinically stable, it may not appear as pleasant radiographically when those plates are not directly over the middle of the metatarsal shafts.

In Conclusion

Postoperative complications can occur in high-risk patients due to underlying medical conditions, such as diabetes, neuropathy and vasculopathy. Bone and wound healing can be significantly compromised in patients with diabetes, especially those with neuropathy.^3,4 However, conservative, non-surgical measures are not necessarily safer in some situations since the risk of infection from a chronic open wound is also high. To avoid postoperative complications in elective surgeries, it is imperative to optimize modifiable underlying medical risk factors and minimize operative trauma.

For this case, smoking cessation and diabetes control occurred prior to the minimally invasive pan metatarsal osteotomy procedure. The patient did significantly better in many aspects in the second surgery than the first when we used a traditional open technique.

Dr. Shibuya is an Associate Professor of Surgery at the Texas A&M Health Science Center College of Medicine. He is the Chief of the Podiatry Section, Surgical Services with the Central Texas VA Health Care System. He is also on the staff at Baylor Scott and White Healthcare System.

Dr. Plemmons is a third-year resident with the Scott and White Healthcare System/Texas A&M Health Science Center.

References

1.      Collinge C, Protzman R. Outcomes of minimally invasive plate osteosynthesis for metaphyseal distal tibia fractures. J Orthoped Trauma. 2010;24(1):24-9.

2.      Iacobellis C, Chemello C, Zornetta A, Aldegheri R. Minimally invasive plate osteosynthesis in type B fibular fractures versus open surgery. Musculoskel Surg. 2013;97(3):229-35.

3.      Shibuya N, Humphers JM, Fluhman BL, Jupiter DC. Factors associated with nonunion, delayed union, and malunion in foot and ankle surgery in diabetic patients. J Foot Ankle Surg. 2013;52(2):207-11.

4.      Humphers JM, Shibuya N, Fluhman BL, Jupiter D. The impact of glycosylated hemoglobin and diabetes mellitus on wound-healing complications and infection after foot and ankle surgery. J Am Podiatr Med Assoc. 2014;104(4):320-9.