Cotton OsteotomyYes in Flatfoot Reconstruction: a Retrospective Review of Consecutive Cases Troy Boffeli DPM, FACFAS, DPM, Katherine Schnell, DPM Regions Hospital / HealthPartners Institute for Education and Research - Saint Paul, MN

STATEMENT OF PURPOSE Figure 1. Preop and Postop Meary’s Angle Measurement Table 1. Results (N=37 Feet) RESULTS The Cotton osteotomy or opening wedge medial cuneiform osteotomy is a useful adjunctive Thirty-two patients (37 feet) were included in the present study (10 males and 22 females). No flatfoot reconstructive procedure that is commonly performed but rarely reported which is in part Mean Age (yrs) 42 (9–77) patient was excluded and all cases were consecutive. The average age was 42 (range 9 to 77). Meary’s angle was due to the adjunctive nature of the procedure. The Cotton procedure is relatively quick to assessed on (a) Gender (M:F) 10M:22F Fixation was used in 16/37(43%) feet. Threaded 0.062” k-wires were used in 12 cases and plate perform and is intended to correct forefoot varus deformity after rearfoot fusion or osteotomy to Preop preoperative and (b) 10 fixation was used in 4 cases. The average follow-up was 18 months (range 2.5 to 96 months). All achieve a rectus forefoot to rearfoot relationship. Proper patient selection is critical since but one patient demonstrated clinical and radiographic healing at the 10 week postoperative visit. week postoperative Laterality (R:L) 13R:24L preoperative findings of medial column joint instability, concomitant hallux valgus deformity, or Mearys line improved in all feet, with an average change of -17.2° pre-operatively to 0.5° post- DJD of the medial column may be better treated with arthrodesis of the naviculocuneiform or first weight bearing lateral Mean Preop Meary’s Angle (°) -17.24 (-35 to -7) operatively (Table 1). Incorporation of the bone graft was seen in 36/37 feet, with no evidence of tarsometatarsal joints. Procedure indications also include elevatus of the first ray which can be a xrays. The Cotton displacement or subsidence in all 37 feet. No patients required removal of the graft or repeat primary deformity in hallux limitus or iatrogenic deformity following base wedge osteotomy for osteotomy is particularly Mean Postop Meary’s Angle (°) 0.51 (-12 to +5) surgery due to displacement of the graft (Table 2). 1/37 had a delayed union of the graft with hallux valgus. The present retrospective series highlights our experience with the use of the a continued pain 4 months after surgery. A CT confirmed no osseous bridge and a bone stimulator useful to correct Mean Change in Meary’s Angle (°) 17.76 Cotton osteotomy as an adjunctive procedure when used in flatfoot reconstructive surgery. abnormal Meary’s angle was prescribed. Two months after using the bone stimulator, pain had resolved (Figure 5). She was Follow-up Time (months) 18.12 (2.5-96) seen at 1 year post-op with no further problems of the surgical foot. There was no fixation used in Postop although correction of this case and no displacement of the graft was noted. The patient was a not a smoker and did not METHODOLOGY deformity may be limited No Fixation (# feet) 21 have Vitamin D deficiency. The other post-operative complication involved 2 patients with After institutional review board approval, we performed a retrospective analysis of consecutive in cases involving neuritis, one which resolved within 1 year after surgery and the other that did not resolve within patients treated with Cotton osteotomy as part of flatfoot reconstruction from April 2001 to instability of the medial Fixation Used (# feet) 16 (4 Plate, 12 K-wires) 4 months after surgery. Both patients with neuritis had plate fixation of the osteotomy but did not December 2015. All osteotomies were performed by one surgeon (TJB) as an adjunctive require hardware removal or revision surgery. Adjunctive procedures included gastrocnemius column joints. Adjunctive Active Smokers(# patients) 5 procedure in correction of pes valgus deformity and PTTD. Inclusion criteria included a clinic procedures also lengthening (21), STJ fusion (13), Koutsogiannis (22), Evans (12), PT tendon repair (15), FDL tendon follow-up at 10 weeks with appropriate preoperative radiographs with no joint proximal joint transfer (6), tarsal coalition resection (6), hardware removal (HWR) from previous distal bunion b contribute to correction Histroy of Chronic Pain (# patients) 3 fault or midfoot DJD or hallux valgus. Postoperative weight bearing (WB) radiographs were taken surgery (3), Kidner procedure (3), bone spur removal (6). Other various procedures that were not at 10 weeks. Patients who did not have WB radiographs at 10 weeks or were lost to follow-up of Meary’s angle. Diabetes (# patients) 1 as common included hammertoe repair, cheilectomy, 1st metatarsal phalangeal joint fusion, and prior to their 10 week post-operative appointment were excluded. Both investigators evaluated TN fusion (Table 3). postoperative radiographs to determine interval to radiographic incorporation of the allograft, Vitamin D Deficiency (# patients) 2 which was defined as bridging of the interface between the graft and native bone by bone callus Figure 2. Surgical Technique Pearls for Cotton Osteotomy or trabeculae at 3 out of 4 cortices and obliteration of the graft interface as previously described ANALYSIS AND DISCUSSION

(1). Graft displacement and subsidence were also evaluated. Meary’s angle was also measured on Table 2. Complications The Cotton Osteotomy is a common and well-accepted adjunctive procedure for correction of preoperative and 10 week postoperative digital lateral WB radiographs (Figure 1). Clinical healing flatfoot deformity with or without posterior tibial tendon dysfunction. In his original article, was determined by absence of pain at the surgical site with palpation and weightbearing. Other Postoperative 0 Cotton stated that “the operation is simple, not painful, and… in the short review of cases done data collected included age, gender, tobacco use at the time of procedure, and chronic medical Infection since I have devised this operation, there has been no trouble in any” (4). The procedure is comorbidities including diabetes, Vitamin D deficiency, and chronic pain. Type of fixation and generally thought to be safe and effective. adjunctive procedures were recorded. Complications including need for revision surgery, non- Hardware Removal 0 A search of medical literature identified few reports of outcomes regarding the Cotton osteotomy. union or delayed union, and neuritis or nerve symptoms related to the Cotton osteotomy were d In a review of 16 patients, Hirose and Johnson used a 4.0 or 3.5 screw to fixate the cotton also assessed. Graft Subsidence 0 osteotomy when performed in conjunction with adjunctive flatfoot procedures. They found a union rate of 100% which is greater than the 77% reported for midfoot arthrodesis and concluded Nonunion 0 SURGICAL TECHNIQUE that an advantage over fusion is more predictable union and preservation of first ray mobility (5). e a b c Malunion 0 Luts and Myerson reported on 101 medial cuneiform osteotomies performed in conjunction with A consistent surgical technique was used in all cases regarding medial cuneiform osteotomy and comprehensive flatfoot reconstruction procedures. They did not report nonunions which supports bone grafting although use and type of fixation was variable. Surgery was performed with the Delayed Union 1 No fixation used, resolved with the theory that the Cotton osteotomy heals predictably (8). Our union rate was very similar, with a patient in the supine position under general anesthesia with a popliteal block. A thigh tourniquet 2 months of bone stimulation delayed union noted in one patient at four months that resolved with the use of a bone stimulator is preferable due to adjunctive procedures. The medial dorsal cutaneous nerve (MDCN), extensor after two months. This patient did not have internal fixation of the graft but there was no shift of hallucis longus (EHL), and tibialis anterior (TA) tendon were marked out pre-operatively and a Plate fixation both cases, Sensory neuritis 2 the osteotomy. This patient was assessed for bone healing risk factors and did not have vitamin D longitudinal dorsal incision was made medial to the EHL tendon which was centered over the 1/2 was resolved at 1 year postop deficiency, or history of tobacco use. medial cuneiform (Figure 2a). The MDCN was carefully freed and protected as needed and the 0/2 required hardware removal incision was carried down to bone. The periosteum was reflected along the dorsal and medial Hirose and Johnson reported one postoperative complication in which a painful screw had to be removed due to screw head prominence. (Hirose & Johnson). We report an incidence of 0/16 for aspect of the medial cuneiform using a periosteal elevator. Care was taken to preserve the g h f ligaments. An osteotomy guide wire was placed centrally within the cuneiform along the lateral hardware removals when using k-wire or plate fixation. Although previous studies did not compare fixation to no fixation groups, there appears to be no difference in union rate between cortex from dorsal to plantar. The pin was placed parallel to the first TMT joint from dorsal to (a) The traditional Cotton incision (dashed line) is centered dorsally over the Figure 5. Delayed Union Case planar rather than perpendicular to the weight bearing surface which was confirmed on lateral those that used fixation and those that did not. In our study, union rates and complication profiles imaging. The osteotomy was made from dorsal to plantar using an oscillating saw. The plantar medial cuneiform. (b,c) Distraction assists with graft placement. (d,e) Tricortical between the groups with fixation (16/37) and without fixation (21/37) were similar. 2/16 patients cortex was preserved to serve as a hinge along with the plantar soft tissues. An osteotome was iliac crest allograft was used in all patients undergoing Cotton osteotomy. The with fixation developed neuritis, one of which resolved in less than 1 year post-operatively. The other patient, who was a smoker, still had neuritis at her 4 month follow-up. Both patients with used as a lever to break the lateral cortex and greenstick fracture the plantar cortex. A tricortical dorsal thickness of the wedge was 5 to 7mm and wedge depth was wedge was then cut from an iliac crest allograft on the back table. The base of the wedge was 5-7 approximately 2.5 to 3cm. (f) The allograft is large enough to provide two neuritis had plate fixation. One of the 21 patients without fixation had a delayed union. mm thick and 2.5 cm from dorsal to plantar which tapered down to 0 mm (Figure 2d-f). A wedge grafts when performing combined Evans / Cotton osteotomy procedures. A recent study by Aiyer determined that the Cotton osteotomy even without fixation is stable, as noted on post-op radiographs (7). He commented on Meary’s angle and concluded that the distractor was used to open the osteotomy and the allogenic wedge was press fit by hand (g,h) Intraoperative simulated WB lateral imaging is shown here before and followed by gentle tamping to seat the graft (Figure 2b, c). Graft placement was confirmed with Cotton osteotomy did provide correction of medial arch sag but did not improve Meary’s angle intra-operative fluoroscopy (Figure 2g, h). Internal fixation is generally not necessary but k-wires after graft placement. (g) Note how the distractor can be used to assess optimal compared to matched controls who did not have a Cotton osteotomy. Our study shows an a b or spanning plate fixation can be used depending on bone quality and intra-operative stability of graft size with (h) confirmation of correction of Meary’s angle. improvement in Meary’s angle for all patients. Myerson also reported an improvement of the graft (Figure 3). Standard layered closure was then performed and the patient was placed in a Meary’s angle from -23 preoperatively to -1 postoperatively and Hirose et al. reported an average improvement of Meary’s angle of 14 degrees (5, 8). We had similar improvement of Meary’s removable splint or below knee fracture boot. All patients were kept non-weightbearing (NWB) (a) 1/37 patients had delayed union of the Cotton osteotomy with localized pain for 6 weeks followed by progressive WB in a fracture boot for an additional 4 weeks followed by Figure 3. Fixation Options for Cotton Osteotomy persisting at 4 months postop. (b) CT confirmed minimal bridging at the angle with an average of 18 degrees of improvement. transitioning back to full WB in shoes. Variable fixation techniques osteotomy site with interposed bone graft. Solid osseous bridging was seen at This retrospective assessment was undertaken to assess outcome and complications associated with the Cotton osteotomy when used as an adjunctive procedure in flatfoot reconstructive were utilized in this the calcaneal osteotomy site. pain at the graft site. Complete resolution of pain LITERATURE REVIEW surgery. Limitations of this study include the relatively small number of patients in the study, retrospective review including was noted at one year postop. although all were consecutive which decreases exclusion bias. Also, all procedures were In 1908, both Riedl and then Young described a closing wedge osteotomy of the medial cuneiform (a) no fixation, (b) crossing performed by a single surgeon, which could also be seen as a benefit, because this removes the for hallux valgus correction (2,3). Cotton originally described his signature procedure in 1936 for inter-surgeon variability with patient selection and procedure technique. We also had a relatively threaded 0.062” k-wire pedal deformities of the first metatarsal head where the metatarsal head could not carry any short follow-up period, with the average follow up being 18 months; however this was sufficient weight. He described the function of the procedure as restoring the “triangle of support.” a fixation, and (c,d) plate Table 3. Adjunctive Procedures (Total of 112) fixation. to assess graft incorporation, nerve complications, hardware issues, and correction of medial arch Additionally, he believed that the procedure could be used to correct flatfoot deformity if it was Koutsogiannis 22 (20%) deformity. Another limitation is that patient satisfaction scores were not available for review. reinforced with muscular training and exercise (4, 5). Finally, with the variety of procedure combinations performed, it is difficult to determine the Contemporary indications for the Cotton osteotomy include forefoot supinatus without hallux Gastrocnemius Lengthening 21 (19%) degree to which the Cotton osteotomy contributed to arch alignment. In conclusion, the present valgus or medial column joint fault, rigid forefoot varus, and hallux limitus with elevatus of the retrospective study of consecutive patients demonstrates that the Cotton osteotomy has a low medial column. The procedure is especially useful to realign the forefoot after correction of b c d PT Tendon Repair 15 (14%) complication rate including graft incorporation, reliably corrects medial column deformity, and is rearfoot deformity in the treatment of posterior tibial tendon dysfunction (PTTD) and acquired not prone to graft displacement without fixation when used as an adjunctive procedure for flatfoot deformity (6). Subtalar Joint Fusion 13 (12%) correction of flatfoot deformity. The first peer reported outcome of the Cotton osteotomy included 15 flatfoot cases where the b Evans Osteotomy 12 (11%) REFERENCES Cotton osteotomy was used as an adjunctive procedures. No nonunions or malunions were 1. Shibuya N, Holloway BK, Jupiter DC. A Comparative Study of Incorporation Rates between Non-xenograft and Bovine-based Structural Bone reported and there was a statistically significant improvement of radiographic parameters Other (bunionectomy, cheilectomy) 11 (11%) Graft in Foot and Ankle Surgery. Journal Foot Ankle Surg. Jan-Feb; 51 (1): 164-167, 2014. including lateral talo-first metatarsal angle (Meary’s angle), calcaneal pitch, and medial cuneiform 2. Riedl A. Osteotomie des Keilbeines bei Hallux Valgus. Arch Klin Chir 88:565, 1909. Tarsal Coalition Resection 6 (5%) 3. Young JD. A new operation for adolescent hallux valgus. Univ Pa Med Bull 23: 459, 1910. to floor distance. Hilrose and Johnson concluded that the Cotton osteotomy was superior to first 4. Cotton FJ. Foot statistics and surgery. N Engl J Med 214: 353-32, 1936. st tarsometatarsal arthrodesis due to preservation of 1 ray mobility and ease of correction (5). Flexor Digitorum Longus Transfer 6 (5%) 5. Hirose CB, Johnson JE. Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed forefoot varus associated with flatfoot In recent study, Aiyer demonstrated that the Cotton osteotomy even without fixation was deformity. Foot Ankle Int 25: 568-574, 2004. 6. Yarmel D, Mote G, Treaster A. The Cotton osteotomy: a technical guide. J Foot Ankle Surg 48:506-12, 2009. radiographicaly stable on follow-up. They also showed that the Cotton osteotomy provided Hardware Removal 3 (3%) 7. Aiyer A, Dall GF, Shub S, Myerson MS. graphic Correction Following Reconstruction of Adult Acquired Flat Foot Deformity Using the Cotton correction of medial arch sag but that it did not improve Meary’s angle (7). c d Medial Cuneiform Osteotomy. Foot Ankle Int. Dec; 37 (5): 508-513, 2015. Kidner 3 (3%) 8. Lutz M, Myerson M. Radiographic Analysis of an Opening Wedge Osteotomy of the Medial Cuneiform. Foot Ankle Int. Mar; 32 (3): 278-87, 2011.