**1. Introduction**

Patients with diabetic neuropathy develop foot problems, some of which can improve with surgery. Tendon balancing is one of the procedures used to treat diabetic foot problems. Tendon lengthening, such as gastrocnemius-soleus recession (GSR), has fewer complications than bony procedures in the foot [1–6].

Tendon lengthening should be performed before bony procedures in high-risk patients such as diabetics, patients with foot ulcers, infection, smokers and without pedal pulses [1–6]. Imbalance of tendons, especially Achilles tightness, can aggravated or cause or many foot problems [1–7]. Tendon lengthening can be used as part of treatment for many foot problems [2, 7–12].

A large number of patients have diabetes and the number is increasing [13]. Foot ulcers are common in patients with diabetes mellitus [14, 15]. Foot ulcers can lead to infection and amputation. Amputation can result from infection from foot ulcers [15, 16]. Over 80% of amputations in diabetic patients have foot ulcers [15, 16].

The most common chronic wounds in industrialized countries are foot ulcers [17, 18]. The average excess cost of a foot ulcer over a two-year period is over \$25,000 [19].

The most common reason for diabetic patient to be admitted to the hospital is foot infection [20]. Up to 50% (62/133) amputation and 20% (26/133) major amputation can occur in patients admitted for foot ulcer or foot infection [16]. Over 80,000

amputations have occurred in diabetic patients in the U.S in one year [21]. If foot ulcers could be cured, most amputations in diabetics could potentially be prevented [15, 16].

The most common cause of neuropathy is diabetes mellitus [22, 23]. Neuropathy causes decreased protective sensation and motor neuropathy causes tendon tightness [24–26]. Tightness of tendon, especially the Achilles, causes increased forces in the foot [27]. Increased forces in the forefoot can cause a callus followed by a forefoot ulcer [14, 27]. Increased forces in the foot can also cause Charcot foot, including foot arthritis, arch collapse, midfoot bony prominence and then midfoot ulcer [10, 28]. Foot ulcers can also result from other causes of neuropathy besides diabetes and can be treated in the same way [24, 26, 29].
