Fixation of first metatarsal basal osteotomy using Acutrak screw

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1 Available online at Foot and Ankle Surgery 14 (2008) Fixation of first metatarsal basal osteotomy using Acutrak screw G.E. Fadel MD FRCS Tr & Orth*, S.M. Hussain FRCS, S. Sripada FRCS Tr & Orth, A.S. Jain FRCS Department of Orthopaedics & Trauma, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK Received 20 March 2007; received in revised form 23 August 2007; accepted 25 September 2007 Abstract Background: The purpose of this study is to determine clinical and radiological outcome following the internal fixation of first metatarsal basal osteotomy using Acutrak screw. Methods: Between May 1999 and December 2003, 37 feet undergoing basal closing wedge osteotomy were stabilised using Acutrak screw. The minimum follow-up period was 18 months. The position and fate of the screw, complications, hallux valgus, intermetatarsal and metatarsal declination angles, and time for bony union were assessed postoperatively and at the final follow-up. Results: Seventy-nine percent of the corrected feet had achieved excellent or good AOFAS score, 13% fair, and 8% poor score. The average preoperative intermetatarsal, hallux valgus and first metatarsal declination angles were (12 208), 388 (17 538) and (16 308), respectively. These were reduced to (0 168), (9 268) and (16 268) following surgery and (0 188), (12 228) and (16 238), respectively, at the final follow-up. Clinical and radiological union has been achieved in all cases. Conclusion: Our technique provides stable fixation with minimal loss of position at the osteotomy site. # 2007 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. Keywords: Screw; Basal osteotomy; Hallux valgus; Internal fixation 1. Introduction Osteotomy of the first metatarsal was advocated by Reverdin [1]. The combination of distal soft tissue correction and proximal metatarsal osteotomy is primarily indicated for correction of moderate to severe hallux valgus deformity [2,3]. The advantage of basal over distal osteotomy techniques is that the bone is cancellous in this region, with more area of contact. Furthermore, it has a greater corrective effect due to the longer axis of rotation; hence it helps to correct severe deformities. The major technical difficulties in basal osteotomy are intra-operative control of the tiny proximal segment and its inability to resist the ground reaction force postoperatively. Shortening and dorsal angulation of the distal segment are common problems encountered in proximal osteotomies. The resulting malunion causes more weight to be transferred * Corresponding author. Tel.: ; fax: address: GFadel@nhs.net (G.E. Fadel). laterally, leading to secondary metatarsalgia [4]. Therefore stability of the osteotomy site is an important factor that would determine the outcome of the procedure. This has led many surgeons to attempt a variety of fixation techniques to counteract this instability, including AO screws, and K-wires [5,6]. We modified the proximal closing wedge osteotomy technique and used Acutrak 1 (Acumed, Alton, UK) compression screw in order to add stability to the osteotomy [7]. The purpose of this study is to analyse the outcome of the technique. 2. Materials and methods Between May 1999 and December 2003, 32 patients (40 feet) underwent hallux valgus deformity correction surgery using this technique by the senior author (ASJ). The average age of patients in the study group was 51 years (23 58 years), the average follow-up period is months with a minimum /$ see front matter # 2007 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. doi: /j.fas

2 22 G.E. Fadel et al. / Foot and Ankle Surgery 14 (2008) of 18 months (18 50 months). Out of 32 patients only 2 were males. Mitchell s osteotomy had been done in one patient previously for juvenile hallux valgus deformity. The clinical data and operative details of all patients were collected from hospital records while 30 patients reported for a final review. The clinical assessment was done using the American Orthopaedic Foot and Ankle Society (AOFAS) 100 points score for the hallux MTP/IP joint, which allocates 40 points for pain, 45 points for function and 15 points for alignment [8]. The result was rated excellent if it was between 100 and 93 points, good (between 92 and 83 points), fair (between 82 and 66 points) and poor (65 points or less) [9,10]. Weight-bearing radiographs at the final review were compared with the pre operative weight bearing and postoperative X-rays. The radiological indices taken into consideration were hallux valgus (HV), inter-metatarsal (IM) and metatarsal declination (MD) angles [Fig. 1] [12]. Status of the screw was also given special attention. Union was defined as no visible line at the osteotomy site. Complications, patient satisfaction with the procedure, the period of convalescence from the time of surgery to return to housework and then to full employment were noted Surgical procedure A longitudinal incision is made on the dorsomedial aspect of the first metatarsal. The distal part of the incision is used Fig. 2. The surgical technique. for soft tissue correction which involves releasing the lateral collateral ligament of the MTP joint and the insertion of adductor hallucis, and the joint capsule is reefed medially. Through the proximal part of the incision a transverse wedge with its apex facing medially is subsequently removed and osteotomy closed down until the lateral spur rests on the lateral cortex of the proximal fragment [Fig. 2]. A guide pin is passed in oblique direction from the dorsolateral surface of the distal fragment to the proximal fragment then a measuring cannulated drill reamer is used to make the screw hole. The appropriate sized Acutrak cannulated screw, which is self-tapping, is then inserted over the guide pin that is subsequently removed [Fig. 3]. A Plaster of Paris slab support is advised for first two weeks until suture removal and this was later supplemented with fibreglass boot cast, which is continued for a period of four weeks during which the patient can start full weight bearing Acutrak screw Acutrak screw is a cannulated headless screw system which was used originally for scaphoid fixation. It is a fully Fig. 1. Measurement of hallux valgus angle (HV), intermetatarsal angle (IM) and metatarsal declination (MD) angles, adopted from Gentili et al. [12]. Fig. 3. Insertion of the Acutrak screw across the osteotomy site.

3 G.E. Fadel et al. / Foot and Ankle Surgery 14 (2008) Table 1 Radiological indices before and after surgery Preoperative Postoperative Final review IM angle (12 208) (0 168) (0 188) HV angle 388 (17 538) (9 268) (12 228) MD angle (16 308) (16 268) (16 238) threaded, cannulated, self-tapping, tapered screw with varying thread pitch in which both the diameter and pitch are gradually increasing towards the trailing end. The screw does not require routine removal after bone healing. All these features add to the advantage of the screw. 3. Results 3.1. AOFAS score The AOFAS score could be assigned only to 30 patients (37 feet). The two patients who had not reported for followup were contacted by telephone and were satisfied with the outcome of the procedure. Excellent to good score was achieved in 29 feet (79%), fair in 5 feet (13%) and poor in 3 feet (8%). Those patients with score 65 or less had transfer metatarsalgia Footwear Before surgery, all patients used some modification in their footwear; 16 patients used insoles and pads, 10 used footwear with wide toe box, and a split shoe size was needed for 1 patient. Postoperatively all patients were able to use conventional flat usual size shoes; and 15 of them were able to use high heeled shoes if they wished. Three patients continued to use pads and insoles Duration of convalescence Following surgery the patients who had one foot operated upon, were able to return to housework in two to five days. All six bilateral foot corrections returned to housework within three weeks. The average duration to return to full employment was 7.6 (6 16) weeks Radiographic results The average IM angle before surgery was (12 208), which had been reduced postoperatively to (0 168) and was found to be (0 188) at the final follow-up. The average preoperative HV angle was 388 (17 538). This was reduced to (9 268) following surgery and was (12 228) at the final follow-up. The average first MD angle was (16 308) preoperatively which was less at (16 268) postoperatively and (16 238) at the final follow-up [Table 1]. There was one screw failure although union was achieved in all cases [Fig. 4] Complications Superficial wound infection occurred in one patient, which needed oral antibiotic therapy. Three patients (8%) developed transfer metatarsalgia and had pain towards the end of the day. In one of the three patients who developed metatarsalgia, the screw was loose, became prominent and as a result was removed nine weeks following insertion. The MD angle for this case was reduced from 208 preoperatively to 148 postoperatively. In the other two patients the MD Fig. 4. Radiographs of left foot with hallux valgus corrected using the modified closing wedge technique; preoperatively, postoperatively and at 26 months following surgery.

4 24 G.E. Fadel et al. / Foot and Ankle Surgery 14 (2008) angle was 208 and 218 before and 168 and 188 after the operation, respectively Overall satisfaction Twenty-nine patients (37 feet) were satisfied while three (3 feet) were unsatisfied and would not undergo the procedure again. 4. Discussion Basal metatarsal osteotomy has been used for correction of moderate to severe hallux valgus deformity. The surgery went into disrepute because it was technically demanding with high incidence of transfer metatarsalgia. The key reason for the metatarsalgia is inability to maintain the corrected position, which leads to dorsal malunion and excessive load transfer to the lateral metatarsals. Trnka et al. reported dorsal malalignment in 15 feet and metatarsalgia in 14 out of 60 feet using basal closing wedge osteotomy [11]. Other studies have emphasised the need for internal fixation of the osteotomy to reduce the incidence of metatarsalgia postoperatively [12]. Prior et al. reported metatarsalgia in 16% of the cases after Mitchell s osteotomy [13] while Resch et al. reported metatarsalgia in 28% of their patients after proximal osteotomy [14]. The incidence of metatarsalgia in our group was 11%. Torkkie et al. studied results of Chevron osteotomy using the AOFAS score reporting excellent or good outcome in 56%, fair in 27% and poor in 16% of the cases with a mean AOFAS score of 81 after six years follow-up [9]. The average AOFAS score in our study was 87.10, which was excellent or good in 79%, good in 13% and poor in 8% of feet. With respect to footwear, Resch et al. found that, 91% of the patients were able to use improved footwear following surgery [15]. All patients in our study used some modification to their footwear before surgery while after correction all were able to use conventional shoes, 47% were able to use high-heeled shoes occasionally and 8% needed insoles. Compression of the osteotomy site is one of the important considerations whilst selecting appropriate hardware as it provides stability and resists rotation which in turn promotes bony healing. In the current series the average IM angle correction was 78 postoperatively and 6.18 at final follow-up. Furthermore, there was only a small change of the average MD angle of 0.38, between the postoperative and the final follow-up reviews. These confirm the stability of fixation achieved with Acutrak screw. The type of the internal fixation device used can affect the outcome of the procedure. Wheeler and McLoughlin compared the biomechanical aspects of cortical screws, Hebert screws and Acutrak screws noting that the Acutrak screw had similar or greater compression to the AO and the Hebert screws respectively but maintained the compression significantly better than either screw after cyclic loading [16]. In addition, about 15% of the screws may need removal [17]. All patients in our series achieved union and only one screw was removed due to loosening at nine weeks following insertion. We attribute this to a technical failure at insertion as over tightening the screw may have damaged the near cortex of the bone leading to loosening. Although the osteotomy eventually united, this patient developed transfer metatarsalgia as the MD angle was reduced during healing. 5. Conclusion The current technique offers several advantages. The bone cuts add stability while the screw adds compression at the osteotomy site and the headless design minimises soft tissue complications. The result of current series suggests that using Acutrak compression screw in this situation results in biomechanically sound fixation leading to solid bony union and removal of the screw is only required in rare occasions. References [1] Reverdin J. De la deviation en dehors du gros orteil (halux valgus, vulg, oignon, bunions, Ballen ) et de son traitement chirurgical. 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