EFFECT OF CALCANEAL LENGTHENING ON RELATIONSHIPS AMONG THE HINDFOOT, MIDFOOT, AND FOREFOOT

To better understand the bony component of pes planus and the means by which the Evans calcaneal lengthening corrects them, we studied the s tanding radiographs of seven adult patients who had undergone calcanea l lengthening to treat symptomatic pes planus. Weightbearing AP and la teral views done preoperatively and postoperatively were used for the study. For each set of films, the following parameters were measured: on the lateral view; overall length of the calcaneus, lateral talometa tarsal angle, lateral talocalcaneal angle, and the calcaneal pitch ang le; and on the dorsoplanar view, the talometatarsal and talocalcaneal angle. In addition, the relative coverage of the talus by the navicula r was described by an angular measurement based on the relationship of the center of the talus to the center of the navicular. The average i mprovements in lateral talocalcaneal angle (a reflection of hindfoot v algus) was 6.4-degrees when the long axis of the calcaneus was used an d 6.8-degrees when the inferior surface of the calcaneus was used for the measurement. The lateral talometatarsal angle improved an average 11.3-degrees (from an average of 19.7-degrees to 8.4-degrees). The dor soplantar talometatarsal angle (a measure of forefoot adduction/abduct ion) improved 15.8-degrees (preoperative average 26.8-degrees, postope rative average 11-degrees). The calcaneal pitch angle improved an aver age 10.8-degrees (preoperative average 3.2-degrees, postoperative aver age 140). The relationship between the talus and navicular was defined by an angular measurement based on the center of each articular surfa ce before and after correction using this measurement. An average impr ovement of 26-degrees occurred in the alignment of these two articular surfaces. This study confirms Evans' belief that significant correcti on can be obtained by lateral column lengthening, that the relationshi p between navicular and talus can be restored without fusion, and that the forefoot position corrects without operative intervention to the medial side of the foot. This study also provides numerical guidelines for the surgeon planning surgical correction of symptomatic pes planu s, and since bony relationships can be observed before and after corre ction, some insight may be gained into tarsal morphology of pes planus .