Distal First Metatarsal Displacement Osteotomy

Distal First Metatarsal Displacement Osteotomy ITS PLACE IN THE SCHEMA OF BUNION SURGERY* From the Section of Orthopedic Surgerv, The Mason Clinic. Seattle ABSTRACT: In a review of 401 operations for symptomatic bunion, it was found that 101 Mitchell procedures gave satisfactory results in 90 per cent of feet in which it was used. About the same percentage of satisfactory results ensued after use of the Keller or Silver procedure, but the Mitchell procedure was limited in its indications to younger patients without rheumatoid arthritis but with moderate deformity. The other operations were used when other indications were present, such as in elderly patients and in those with mild or more severe deformity. Late complications (residual deformity, metatarsalgia, and others) were largely responsible for unsatisfactory results. More than eighty different types of surgical operations have been described for the correction of symptomatic bunion. Each surgeon must rely upon his own somewhat limited repertory of bunion procedures to fit the patient at hand. To improve the skill of the surgeon in selecting the appropriate reconstructive foot surgery, I have reviewed my experience with bunion surgery at The Mason Clinic over the period from 1957 to 1970. A minimum of three years of follow-up was required for the detection of late complications. The purpose of this study was twofold: first, to aid the surgeon in selecting a type of bunionectomy appropriate to any given patient, and secondly, to show that with careful patient selection the results of distal first metatarsal osteotomy (the Mitchell procedure) and of the Keller and Silver procedures are good in most instances. I have utilized the Mitchell operation in a selective fashion since its description by Hawkins, Mitchell, and Hedrick in 1945, and have been gratified by the results obtained, as were Carr and Boyd and others '. During the period from 1945 to 1957, I concluded that the Mitchell osteotomy-bunionectomy was a good middle-of-the-road procedure for many patients with symptomatic bunion, but was by no means a universal procedure. Slow healing of the osteotomy site and resultant loss of position with recurrent deformity occurred all too frequently. It became evident that certain middle-aged and elderly patients were better served by less radical procedures. I therefore decided that distal first metatarsal displacement osteotomy for bunion correction would serve as the procedure of choice for bunion surgery in our Clinic, and that the Keller or Silver procedures would also be used where appropriate. The Mitchell procedure was modified to some degree and extended very occasionally by combining it with the Keller principle of osteotomy of the base of the proximal phalanx of the big toe. This combined procedure was developed because of inability to obtain complete bunion correction by the Mitchell procedure alone in severe primary deformities, as well as in recurrent deformities after standard procedures. Keller-Mitchell bunionectomy, as will be stressed, had a very limited use. Careful selec- * Read at the Annual Meeting of the Western Orthopedic Association, Houston, Texas. November 2, 1972. t 1 1 18 Ninth Avenue. Seattle, Washington 98101. VOL. %-A, NO. 5. JULY 1974 923

924 J. W. MILLER tion of the patients for surgery, close adherence to good operative technique, and good postoperative management were the three elements upon which success depended. Our patients with rheumatoid arthritis were not subjected to distal first metatarsal osteotomy - they were better served by Clayton's modification of the Hoffman procedure and were never candidates for osteotomy-bunionectomy. We have had no experience with the oblique displacement osteotomy as described by Wilson. Methods and Materials Of the 273 patients included in the study, 257 were evaluated by either questionnaire (eighty-eight patients) or return examination alone. There were sixteen patients who at first thought they could not return for examination but later found it possible to come in for re-evaluation. These sixteen patients and those who brought their answered questionnaires with them showed that the data obtained by questionnaire usually correlated closely with the examination evaluation. During the thirteen-year period of this study, 52 1 bunionectomies were carried out on 361 patients in The Mason Clinic. Eighty-four patients, with 120 bunionectomies, returned inadequately answered questionnaires or were lost to follow-up, and were not included in the evaluation. Therefore, approximately 75 per cent of the patients operated on in the thirteen-year period responded, making available a total of 401 feet for the statistical analysis as shown in Table I. It should be particularly noted that Keller's operation is used in nearly 68 per cent of all patients with symptomatic bunions. Osteotomy-bunionectomy is carried out in 25 per cent of all bunion operation candidates in our clinic. Selection of Patients The schema of over-all criteria for the different operative procedures used at our clinic depended on the age of the patient and the degree of deformity. The patients with minimum deformity ordinarily have an intermetatarsal angle of 14 degrees or less. Those with moderate deformity have an angle of 14 to 23 degrees. A deviation of the first metatarsal above 23 degrees is considered severe. We adhered rather closely to these criteria of deformity and age and our patients were divided into four operative groups, as follows: 1. Silver operation - for elderly patients with minimum deformity; 2. Mitchell operation - for patients between fifteen and fifty-five years old with moderate deformity; 3. Keller operation - for patients over fifty-five years old with moderately severe deformity. Rarely, a patient with a very long big toe had a Keller procedure, no matter what his age was; 4. Combined Mitchell-Keller operation - for patients either with severe deformity or with recurrence. Age Range The age range in general was from fifteen to fifty-five years for osteotomybunionectomy. Both ends of this age scale were violated upon occasion. Two twelveyear-old children with bilateral bunion had a distal first metatarsal osteotomy with good results. Our policy was that a patient might undergo any of the types of surgery at an earlier age than fifteen years if the deformity, along with the resultant symptoms and shoe problems, seemed to warrant it. The bone of the foot should, of course, be approaching skeletal maturity. By the same token, an individual over fifty-five years old with severe deformity, good pulses, and no evidence of skin or subcutaneous atrophy might be a candidate for osteotomy-bunionectomy. This author and Mitchell e early and independently recognized the problems of delayed union with associated loss of position at the osteotomy site in the older patient. Both Mitchell and I, therefore, used fifty-five years of THE JOURNAL OF BONE AND JOINT SURGERY

pp.- DISTAL FlRST METATARSAL OSTEOTOMY TABLE I BUNIONECTOMIES PERFORMED AT THE MASON CLINIC FROM 1957 TO 1970 Type of Procedure Age Range No. of Patients* Significant Residual Deformity No. Satisfactory Total No. of Procedures Percentage Satisfactory (Yrs.) Silver 14-71 19 (3) 2 20 22 90 Keller 17-80 181 (89) 10 250 270 92 Mitchell 12-63 68 (33) 7 91 101 90 Mitchell-Keller 45-58 5 (3) 0 8 8 100 Total 273 19 369 40 1 * Bilateral procedures in parentheses. age as an arbitrary cut-off point for distal first metatarsal osteotomy. Three patients in this series (five osteotomy-bunionectomies) had results that were unsatisfactory and were over fifty-five years old. Three other patients over fifty-five (five procedures) also had satisfactory results. Therefore, roughly 15 per cent of patients of the group that had the Mitchell procedure fell outside of the advocated age range. Keller procedures were performed on two patients well below the prescribed age range, seventeen and twenty-seven years old, respectively. These patients both had bilateral bunion and long big toes. The results in both patients were good. Additionally, the Keller operation was done in six patients (ten feet) in the fourth decade of life, eight patients (thirteen feet) in the fifth decade, and four patients in their early fifties (seven feet). Thus, roughly 10 per cent of patients who had a Keller bunionectomy were less than fiftyfive years old. In general, individuals who were sixty-five years old or older were not candidates for distal first metatarsal displacement osteotomy. They were, for the most part, well served by the Keller procedure. The elderly patient with minimum deformity usually had a Silver procedure. Degenerative Arthritis Degenerative arthritis was graded in our patients on a basis of I to 111. Those patients with less than a 10-degree loss of dorsiflexion of the first rnetatarsophalangeal joint or a 10-degree loss of plantar flexion (total loss of range of motion less than 20 degrees), and without roentgenographic evidence of degenerative change, were designated as having The postoperative dressings and the special shoes. The top of the shoe is canvas, the fasteners are Velcro, and the sole is wood covered with rubber (made by the Viking Shoe Company, P.O. Box 495, Santa Cruz, California). VOL. SCA, NO. 5, JULY 1974

J. W. MILLER minimum or Grade-I degenerative changes. Patients with a loss of dorsiflexion and plantar flexion of 10 degrees each or more (total loss greater than 20 degrees) usually had a palpable dorsal first metatarsal head ridge or spur with associated degenerative changes seen on roentgenograms, and were placed in Grade I1 of degenerative change, the moderate category. The patient with only a few degrees of total motion of the bunion joint and severe roentgenographic changes (hallux rigidus) was placed in the severe, or Grade 111, category. Patients in Grade I had their operation selected without regard to the mild loss of motion. Patients with Grades I1 and I11 were felt to have significant changes and were with one exception selected for the Keller procedure. Eleven patients (nineteen feet) who had a Keller bunionectomy and who were less than fifty-five years old had significant Grade-I1 or Grade-I11 changes. This represented roughly 50 per cent of the patients under fifty-five years old who had a Keller operation. The degenerative changes were the prime reason for selecting this type of surgery for these patients. By the same token, one patient (one foot) who was over fifty-five years old and had significant degenerative changes had a Mitchell procedure. The final result in this patient was poor and the preoperative arthritic changes probably were a significant factor. The degree of deformity and the patient's age were the main determining factors in the selection of the type of operation that was performed. The Osteotomy If osteotomy-bunionectomy was decided on, the direction of the cuts and the width of the lateral spur that would be left on the proximal portion of the distal first metatarsal fragment were devised on the basis of the intermetatarsal angle. This was determined by two intersecting lines, the first line drawn from the center of the first metatarsal head through the center of the base of the first metatarsal, and the second drawn through the center of the second metatarsal head parallel to the long axis of the foot (Figs. 2-A and 2-B). This technique differs slightly from the method advocated by Mitchell and associates? They drew the second line through the axis of the second metatarsal. The Figure. 2-A: Reoperative weight-bearing anteroposterior roentgenograms showing an intermetatarsal angle of 20 degrees in the left. symptomatic foot. The right foot has a mild IS-degree deformity and is asymptomatic. Figure. 2-B: Postoperative weight-bearing roentgenograms showing a 6-degree correction in the earlier 20-degree deformity of the left foot. The routine horizontal osteotomy was done and the result was satisfactory. However, the trapezoid cut would have produced angulation of the distal fragment and greater correction had this been deemed advisable. THE JOURNAL OF BONE AND JOINT SURGERY

DISTAL FIRST METATARSAL OSTEOTOMY D Further Modification of E. Canbind Modifii Mikhdl- F. k t Opwotiva Slotus Mitchell Bunioncctomy Kellu Buniamctarq FIG. 3 Diagrammatic representation of the over-all development, modifications, and extensions of the osteotomybunionectomy. A, Silver bunionectomy. B. Mitchell's method. with the osteotomy cut perpendicular to the first metatarsal shaft. C, Author's modification, making the osteotomy perpendicular to the long axis of the foot. D, Hammond's trapezoid cut, decreasing the intermetatarsal angle to better advantage. E, The combined Mitchell-Keller procedure, used in certain recurrent and also severe primary deformities. F, the postoperative status in either instance after the combined Mitchell-Keller procedure. intermetatarsal angle before operation without exception measured 13 degrees or more in all patients who had a distal first metatarsal osteotomy. The average preoperative intermetatarsal angle for the osteotomy-bunionectomy group was 20.2 degrees. We usually made the osteotomy perpendicular to the long axis of the foot rather than perpendicular to the first metatarsal shaft, as advocated by Mitchell (Fig. 4). The width of the lateral spur was directly proportional to the intermetatarsal angle: if the angle was 13 to 19 degrees, an osteotomy in which two parallel cuts were made (Figs. 3, C and 4) was chosen. A trapezoid cut as advocated by Harnmond was made if the angle was in the 20 to 30-degree range (Figs. 3, D and 4). If the patient had metatarsalgia, we attempted to relieve the symptoms beneath the second and third metatarsal heads by doing the osteotomy so that the head would be directed very slightly downward. This was accomplished by making the saw cuts slightly farther apart on the ventral than on the dorsal surface. Following the displacement of the proximal fragment, the head then tilted plantarward when the osteotomy site was closed. The combined Mitchell-Keller procedure was utilized for a few severe deformities, that is, if the intermetatarsal angle exceeded 23 degrees. It was also used in those patients requiring secondary procedures following inadequate or unsuccessful surgery (Fig. 5). Operative Technique and Postoperative Care for Osteotomy-Bunionectomy The usual dorsomedial incision was made on the inner surface of the foot under tourniquet control. After undermining the skin and subcutaneous tissue, the abductor hallucis tendon, the joint capsule, and the periosteum were dissected as one tongue-shaped VOL. 56-A, NO. 5. JULY 1974

928 J. W. MILLER MITCHELL MILLER HAMMOND Diagrammatic representation of slight increase in correction and decrease in intermetatarsal angle by altering the cuts without changing appreciably the width of the lateral spur on the distal fragment. flap, with the base attached distally to the proximal phalanx. This was done very carefully so that an intact substantial structure was developed and remained intact for the suture which served for internal fixation. Dissection was then carried out laterally and kept to a minimum. At that point two drill holes were made in the metatarsal, slightly offset one to the other, the first slightly distal to the osteotomy site and the second two centimeters proximal to it. The exostosis was removed with a straight osteotome. A 0 or 1 chromic catgut suture was placed through the holes in such a fashion that it would not become entangled in the power saw, yet could later be easily tied. The osteotomy was carried out in a fashion predetermined by the intermetatarsal angle. The lateral displacement of the distal fragment was done easily. The suture was then tightened and tied; fixation was usually excellent. The medial part of the end of the distal fragment of the first metatarsal could be smoothed off with rongeurs, but this was not routinely necessary. The toe was held in a slightly overcorrected abducted position while the tongue-shaped flap was advanced a few millimeters in a proximal direction and carefully sutured in place. Skin closure was done with mattress silk sutures. Kirschner-wire fixation, as advocated by Szaboky and Raghaven, was not ordinarily necessary. A dry dressing was applied to the wound. A small folded dressing was placed under all toes for their support. This was held in place by two or three layers of sterile soft roller gauze. A 7.6-centimeter gauze bandage was then applied so that the big toe was held in the overcorrected position, and the entire dressing was reinforced with 2.5-centimeter tape. This dressing was ordinarily not disturbed until the skin sutures were removed, after an interval of ten to twelve days. A snug supportive dressing was then reapplied and changed at ten-day intervals, until approximately six to eight weeks had elapsed. The patient was allowed to walk by the second or third postoperative day. This was facilitated by the use of a special wooden-sole shoe (Fig. 1). Crutches were seldom necessary. The shoe was used until there was sufficient union at the osteotomy site to allow the patient to transfer to more conventional footwear. This could usually be done six or eight weeks after the operation. A toe-spreader was usually worn for an additional month. Casts have not been necessary since the introduction of the special shoe. Keller Bunionectomy The Keller operation was carried out with two slight, but extremely important, modifications from the standard procedure. Following routine removal of the bunion, the resection of the base of the proximal phalanx of the big toe was carried out conservatively, THE JOURNAL OF BONE AND JOINT SURGERY

DISTAL FIRST METATARSAL OSTEOTOMY Prior Surgery / I Severe Deformity Combined Modified Mitchell- Kel ler Bunionectomy FIG. 5 Diagrammatic representation of the two ways that the combined Mitchell-Keller bunionectomy may be performed. If a prior Silver procedure has been canied out and hallux valgus remains severe, with the articulating surface of the first metatarsal head continuing to point laterally, the procedure pictured on the left is performed. In the patient with severe primary deformity, who has the head articulation at right angles to the direction of the first metatarsal shaft, the procedure shown on the right is selected. with only two to three millimeters of bone removed. This prevented unsightly shortening of the big toe as well as obviating a lax digit. Finally, the abductor-capsular structures were closed with a figure-of-eight chromic 0 catgut stitch that caught some of the periosteum of the stump of the proximal phalanx of the big toe. As this "master stitch" was tied, the toe was held in the corrected position by an assistant. The postoperative care was the same as for osteotomy-bunionectomy. The convalescence, however, was usually one to two weeks shorter. Results Table I shows that the over-all results for all procedures were satisfactory or excellent in 90 per cent of the patients. The results were classified on the basis of the evaluation by the patient and the surgeon. If the symptoms were relieved and the deformity improved, ordinarily the patient was satisfied. The patient's evaluation usually agreed with that of the physician. When the two were not in accord, and especially when a second procedure was necessary, the result was tabulated as unsatisfactory. It became evident as the study progressed that late complications were largely responsible for unsatisfactory results. Significant residual deformity was the leading cause of a poor result. Significant residual bunion deformity occurred in two of twenty-two Silver procedures, seven of 101 Mitchell operations, and ten of 270 Keller procedures. The patients with significant residual deformity all had had severe deformity prior to surgery. None of the patients who had the combined procedure had significant residual deformity. We have continued the use of the combined Mitchell-Keller procedure since 1970 for those patients with severe deformity with continued good results. Significant residual deformity, present in ten of the patients who had the Keller procedure, could largely have been prevented by electing to carry out osteotomy-bunionectomy or the combined procedure. In the seven cases of significant residual deformity in the patients who had the Mitchell operation, either the fashioning of a wider lateral spur on the distal fragment at the time of surgery or the use of the combined operation might have lessened the incidence of residual deformity. VOL. %-A, NO. 5. JULY 1974

930 J. W. MILLER The other relatively common reason for unsatisfactory results (eight cases) was metatarsalgia under the second metatarsal. At times this was present preoperatively and was considered an indication for osteotomy-bunionectomy. This complication, present in six patients in the Keller group, might have been prevented by osteotomy-bunionectomy with the cuts fashioned to direct the first metatarsal head downward. In the patients with the Mitchell operation, the two patients in whom metatarsalgia caused the result to be unsatisfactory might have had this complication prevented had more attention been directed to tilting the first metatarsal head downward at the time of the surgical procedure. Any patient with a callosity that remained beneath the second or third metatarsal head, who had complaints referable to this area, was regarded as having residual metatarsalgia. The incidence of residual metatarsalgia was not great in the osteotomy-bunionectomy group and was managed in all patients by the use of metatarsal pads or bars. There was spur formation on the dorsal aspect of the first metatarsal head in four patients, three with Keller procedures and one with a Mitchell procedure. These complications and one other, a ganglion in one patient who had a Keller procedure, probably were not preventable. There were no patients with non-union, osteomyelitis, or avascular necrosis of the first metatarsal head. Early Complications There were eight patients in whom a superficial infection developed, and two with deep infections. They required longer hospital stays and out-patient dressings for six and thirteen weeks, respectively, before wound healing occurred. No second surgical procedure was required in any patient because of an infection. Delayed wound healing occurred in three patients and a flare-up of gout, in one. Stress fractures occurred in three patients in the over-all series, manifested by increased pain and swelling with inability to bear weight on a previously comfortable extremity. These stress fractures occurred between four and eight months after operation and seemingly involved the patients who had had difficulty in resuming activity. The fractures occurred either in the second or third metatarsals. They were treated by use of felt longitudinal arch pads with snug foot strappings, and healed without residual disability. Discussion We used the degree of deformity and the patient's age as the most important criteria in selection of the appropriate bunion surgery. The elderly or middle-aged individual with minimum deformity is a clear-cut candidate for the Silver procedure. The young patient with mild deformity has such a wide choice of footgear that symptoms are seldom sufficiently severe to warrant corrective surgery. The patient with moderate deformity and symptoms, who is fifty-five years old or younger, is usually the best candidate for osteotomy-bunionectomy. However, if the metatarsal angle is not greatly increased (14 to17 degrees), and if the patient's age approaches the upper limit (fifty-five years), a Keller procedure may be preferable because the morbidity is less than with the Mitchell operation. The patient with severe primary deformity and the individual with a significant residual bunion after inadequate surgery deserve special attention. The weight-bearing anteroposterior roentgenogram in either case must be carefully evaluated, not on1 y as to the degree of the intermetatarsal angle but also as to the direction of the residual articulating surface of the first metatarsal head. If this surface is pointed laterally and if the intermetatarsal angle is 24 degrees or more, a trapezoid cut should be made in the first metatarsal, with its widest portion medially. If the articular surface remains more or less perpendicular to the metatarsal shaft, the widest portion of the trapezoid should be directed laterally (Fig. 5). The base of the proximal phalanx in either case is removed in a conservative fashion, combining the Mitchell operation with the Keller procedure to yield the THE JOURNAL OF BONE AND JOINT SURGERY

DISTAL FIRST METATARSAL OSTEOTOMY 93 1 Mitchell-Keller bunionectomy. This combined procedure can decrease the intermetatarsal angle by as much as 15 degrees, but the procedure should be limited to those patients with the specific indications detailed previously. References 1. CARR, C. R., and BOYD, B. M.: Correctional Osteotomy for Metatarsus Primus Varus and Hallux Valgus. J. Bone and Joint Surg.. 50-A: 1353-1367, Oct. 1968. 2. CLAYTON, M. L.: Surgery of the Lower Exeemity in Rheumatoid Arthritis. 1. Bone and Joint Surg., 45-A: 1517-1536, Oct. 1963. 3. HAMMOND, G.: Personal communication. 4. HAWKINS, F. B.; MITCHELL, C. L.; and HEDRICK, D. W.: Correction of Hallux Valgus by Metatarsal Osteotomy. J. Bone and Joint Surg., 27: 387-394, July 1945. 5. MITCHELL. C. L.; FLEMING, J. L.; ALLEN, RICHARD; GLENNEY, CHRISTOPHER; and SANFORD, G. A,: Osteotomy-Bunionectomy for Hallux Valgus. J. Bone and Joint Surg., 4bA: 41-60, Jan. 1958. 6. MITCHELL, C. L.: Personal communication. 7. SZABOKY. G. T., and RAGHAVEN, V. C.: Modification of Mitchell's Lateral Displacement Angulation Osteotomy. J. Bone and Joint Surg., 51-A: 1430-1431, Oct. 1969. 8. WILSON, J. N.: Oblique Displacement Osteotomy for Hallux Valgus. J. Bone and Joint Surg., 45-8: 552-556, Aug. 1%3. VOL. %A, NO. 5. JULY 1974