The Journal of Foot & Ankle Surgery xxx (2016) 1–4

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The Journal of Foot & Ankle Surgery

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Original Research Quality of Early Union After First Metatarsophalangeal Joint Arthrodesis

Florian Wanivenhaus, MD 1, Norman Espinosa, MD 1, Philippe M. Tscholl, MD 1, Fabian Krause, MD 2, Stephan H. Wirth, MD 1

1 Surgeon, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich,€ Switzerland 2 Surgeon, Department of Orthopaedics, University Hospital Bern, Bern, Switzerland article info abstract

Level of Clinical Evidence: 3 The aim of the present retrospective cohort study was to assess the quality of union and the clinical outcomes in patients who had undergone first metatarsophalangeal joint (MTPJ) fusion using a dorsal plate and plantar Keywords: arthrodesis lag screw. From March 2011 to December 2012, the clinical and radiographic data of 39 patients (41 feet) who fi first metatarsophalangeal joint (MTPJ) had undergone rst MTPJ fusion using a compressive locking plate were retrospectively reviewed. All patients fixation had undergone postoperative computed tomography at 6 weeks postoperatively to assess union. The average hallux rigidus metatarsophalangeal angles improved from 23 16 preoperatively to 14 5 postoperatively. The dorsi- osteoarthritis flexion of the hallux at the preoperative assessment averaged 17 11 and 23 5 postoperatively. At plate fixation 6 weeks postoperatively, the computed tomography scans demonstrated 3 complete fusions (7.3 %) and 38 partial unions (92.7%). Also at 6 weeks, the mean standard deviation joint bridging was 54% 14.6%. The forefoot American Orthopaedic Foot and Ankle Society scale score had improved significantly from 50 13 preoperatively to 80 7at>1 year of follow-up (p ¼ .001). Hardware removal was performed in 8 cases because of pain in 7 and infection in 1. Revision arthrodesis was required in 2 cases because of nonunion. At 6 weeks postoperatively, partial bony joint bridging could be observed in most cases after arthrodesis of the first MTPJ with the dorsal fusion plate. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.

Arthrodesis has remained the reference standard procedure for the best of our knowledge, all studies regarding first MTPJ fusion assessed treatment of end-stage osteoarthritis of the first metatarsophalangeal the quality of bony consolidation using conventional radiography joint (MTPJ). It also serves as an effective salvage procedure of pre- alone. The ability to accurately determine the state of fusion on viously failed first MTPJ arthroplasty or hallux valgus surgery (1,2). standard radiographs has been questioned. More recently, computed The fixation methods vary widely and include parallel or crossed tomography (CT) has been proposed to allow a more precise assess- screws or wires, Steinman pins, staples, cerclage wires, bioabsorbable ment of the fusion (14). devices, dorsal plates, and external fixators. MTPJ- specific locking The most common postoperative recommendation when plates have been developed to ensure better fixation and earlier performing lower extremity arthrodesis has been to keep patients weightbearing and reduce hardware disturbances. However, many of non-weightbearing for a minimum of 6 weeks (15). Although, these plates cannot provide appropriate compression at the fusion empirically, osseous healing generally occurs within 6 weeks, the site (3). Ideally, an implant will enable reproducible anatomic posi- published data lack adequate support for this recommendation (15). tioning of the fused joint, promote adequate fusion, and prevent The aims of the present retrospective cohort study were to complications. Biomechanical analyses of various fixation methods determine the fusion rate of first MTPJ arthrodesis using a dorsal have shown that the combination of a lag screw and dorsal plate fusion plate combined with a plantar lag screw 6 weeks after surgery represents the most stable construct (4–7). using CT scans; to assess restoration of the transversal and sagittal The fusion rates reported in published data range from 77% to alignment of the first ray; and to evaluate the clinical outcomes and 100%, regardless of the underlying pathologic entity (8–13). To the complication rates after a minimum of 1 year of follow-up.

Financial Disclosure: None reported. Patients and Methods Conflict of Interest: None reported. Address correspondence to: Florian Wanivenhaus, MD, Department of Orthopae- We performed a retrospective analysis of all patients who had undergone primary dics, Balgrist University Hospital, University of Zurich, 340 Forchstrasse, Zurich€ 8008, arthrodesis of the first MTPJ from March 1, 2011 to December 31, 2012 at 1 institution. Switzerland. Data were retrieved from the electronic hospital database and by inviting the patients E-mail address: fl[email protected] (F. Wanivenhaus). for a clinical and radiographic assessment. All patients gave informed consent, and the

1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.09.001 2 F. Wanivenhaus et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–4 local ethical committee approved the present study (cantonal ethical committee no. Results 2014-0663). The inclusion criteria were the presence of arthrodesis of the first MTPJ with a Patient Demographics dorsal fusion plate (2.7-mm VAR Synthes MP fusion plate; Synthes, Oberdorf, Switzerland) and the use of a plantar lag screw; the availability of a 6-week post- operative CT scan; and a minimum of 1 year of follow-up (FU). The collected data A total of 39 patients (13 [33.3%] males, 26 [66.6%] females) who included the following demographic factors: sex, age, body mass index, surgical in- had undergone 41 first MTPJ fusions with a mean FU period of dications (hallux rigidus, severe hallux valgus, rheumatoid arthritis), and previous 22.8 (range 12.4 to 55.3) months met the inclusion criteria. Their hallux surgery. The hallux metatarsophalangealinterphalangeal scale score of the American Orthopaedic Foot and Ankle Society was recorded preoperatively and at the mean age was 63 (range 44 to 83) years. Their mean body mass index 2 last FU visit. The pain score (none, mild and occasional, moderate daily, severe, and was 26.7 (range 18.5 to 38.2) kg/m . The indications for fusion were almost always present) was recorded preoperatively and postoperatively. Patients hallux rigidus with symptomatic arthrosis in 36 (92.3%) feet and se- were also asked to rank their satisfaction with the postoperative outcome at the final vere hallux valgus deformity (>35) in 5 (12.8%). Three (7.7%) patients FU visit. presented after previous hallux valgus surgery and 4 (10.3%) after The radiographic assessment encompassed standard dorsoplantar weightbearing radiographs performed preoperatively and postoperatively to determine the hallux previous cheilectomy. Of the 39 patients, 4 (10.3%) had rheumatoid valgus angle, intermetatarsal 1-2 angle, intermetatarsal 1-5 angle, and dorsiflexion arthritis, 1 (2.6%) had a fracture of the first metatarsal head, 1 angle of the hallux. The hallux valgus angle was defined as the intersection of the (2.6%) had Parkinson’s disease, and 1 (2.6%) had gout. longitudinal bisection of the first metatarsal and first proximal phalanx. The inter- metatarsal 1-2 angle and intermetatarsal 1-5 angle were defined as the intersection of the longitudinal bisection of the first metatarsal and the second or fifth metatarsal Clinical Outcomes shaft, respectively. The dorsiflexion angle, with reference points placed at the midpoint of the proximal and distal aspects of the diaphyses of the proximal phalanx and the first metatarsal, was measured on lateral radiographs. The mean forefoot American Orthopaedic Foot and Ankle Society The quality of the fusion was determined on 6-week postoperative CT scans by 1 scale score improved significantly from 50 13 preoperatively to observer (F.W.). Fusion of the first MTPJ was then categorized as partial or total. Partial 80 7 at the final FU appointment (p ¼ .001). The changes in pain fusion was classified according to the location of the bony bridging. The joint space was level from preoperatively to several points postoperatively are listed divided into 3 horizontal areas (dorsal, central, and plantar), which were further in Table 1. At the last FU appointment, the patients were asked to rate divided into 3 vertical areas (medial, central, and lateral). Bony bridging of the joint space was rated for each of these 9 locations individually, and the amount of their level of satisfaction with their postoperative outcome. In all, 15 joint bridging was manually calculated for partial fusion (20% to 90%). Overall, <20% patients (37%) were perfectly satisfied, 4 (10%) were very satisfied, 16 joint bridging was rated as no fusion and >90% as total fusion. All surgical procedures (39%) were satisfied, and 2 (5%) were not satisfied (n ¼ 37). Two pa- was performed by or under the direct supervision of a fellowship-trained foot and ankle tients did no respond to this question. No patient responded that the surgeon (N.E., S.H.W.). discomfort was worse than before surgery.

Surgical Technique Radiographic Assessment

The patient was placed in the supine position on the operating table, with a tour- niquet placed on the lower thigh. The tourniquet was adjusted to 280 to 300 mm Hg, The mean preoperative and postoperative values for the parame- depending on the patient’s systolic blood pressure. At 10 to 30 minutes preoperatively, ters measured on standard radiographs with the patient in the dor- all patients received a third-generation cephalosporin antibiotic. The first MTPJ was soplantar weightbearing condition were as follows: hallux valgus approached through a dorsolateral skin incision. The lateral extensor hoods were angle, 23 16 and 14 6; intermetatarsal 1-2 angle, 11 4 and incised, and the tendon of the extensor hallucis longus was retracted medially. The joint capsule was incised to expose the future fusion zone. At times, it was necessary to 9 3 ; intermetatarsal 1-5 angle, 28 5 and 26 5 ; and dor- release the lateral and medial collateral ligaments and the plantar plate to allow full siflexion angle, 17 11 and 23.0 5.2 , respectively. exposure of the joint. Once the first MTPJ was mobile, the greater toe was brought into All cases underwent CT analysis at 6 weeks postoperatively, with 3 fl maximum plantar exion. This maneuver allowed the metatarsal head and the base of (7.3%) showing complete fusion and 38 (92.7%) partial fusion (Fig). the proximal phalanx to be fully exposed. The fusion areas are listed in Table 2. Also, the 6-week postoperative A Kirschner wire (K-wire) was inserted into the center of the first metatarsal, in line with the midline axis of the shaft. A concave reamer was then used to debride the first CT scans revealed a mean joint bridging of 54.0% 4.6%. metatarsal head from the cartilaginous remnants. Another K-wire was then inserted Of 38 feet, dorsoplantar radiography at 6 weeks postoperatively into the base of the proximal phalanx, and a convex reamer was used to remove the showed that 10 (26.3%) had achieved complete union, 25 (65.8%) partial cartilage. The subchondral bone was then perforated using a K-wire. The first MTPJ was fi union, and 3 (7.9%) no signs of union. CTanalysis showed that the 3 cases brought into neutral position and temporarily xed with a 2.0-mm K-wire. The position of the first ray was checked using the metallic cover of the instrument box. Thus, we with no signs of bone union had a mean joint bridging of 27.0% 5.8%. were able to simulate weightbearing on the future fusion construct. The 25 cases of partial union shown on standard radiography demon- Clinically, all first MTPJ fusions were placed in a neutral position in the sagittal strated a mean joint bridging of 59.0% 16.6% on CT analysis. The 10 plane such that the dorsal cortices of the base and the first metatarsal shaft came into cases of complete union shown by standard radiography demonstrated line and slightly valgus in the transversal plane (range 5 to 10). In all cases, a plantar a mean joint bridging of 62.0% 19.9% on CT analysis. At the last FU 2.7-mm cortical lag screw was inserted in a distal to proximal direction. The appropriate size dorsal fusion plate (2.7-mm VAR Synthes MP fusion plate; Synthes) was selected. It was preliminarily fixed with 2 compression wires (1.6 mm, threaded with a spherical stop). The first was drilled into the distal compression wire Table 1 ¼ hole and the second at the most proximal position in the compression wire slot. Area of fusion 6 weeks postoperatively (N 41 feet in 39 patients) Compression of the fusion zone was achieved by applying a specific compression device * Fusion Area n (%) at the previously placed compression wires. Locking of the 2.7-mm plate was started distally and completed proximally. The wound was closed with monofilament sutures Dorsal/medial 31 (75.6) (Maxon 3-0 and Maxon 4-0; Covidien, Miami, FL; Prolene 4-0; Ethicon, Somerville, NJ). Dorsal/central 35 (85.4) The patients were allowed to ambulate in a stiff-soled postoperative shoe under full Dorsal/lateral 18 (43.9) weightbearing. Central/medial 28 (68.3) Central/central 33 (80.5) Central/lateral 12 (29.3) Statistical Analysis Plantar/medial 17 (41.5) Plantar/central 21 (51.2) Plantar/lateral 12 (29.3) Statistical analysis was performed with SPSS Statistics, version 20.0 (IBM Corp., Armonk, NY). Wilcoxon’s signed rank test was performed. Statistical significance was * Area of osseous joint bridging at 6 weeks postoperatively observed on computed defined as p < .01 for all hypotheses. tomography scans. F. Wanivenhaus et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–4 3

procedure for previously failed MTPJ arthroplasty or failed hallux valgus surgery (1,2). The reported interval to union for first MTPJ arthrodesis averages 64 days, with a 5.4% nonunion rate, regardless of the fixation technique used, primarily for nonrheumatoid and non- revision pathologic features (16). In a review, Mirmiran et al (15) noted that the reported nonunion rate ranged from 2% to 23% for first MTPJ arthrodesis and that the interval to union has been estimated to be 8 to 12 weeks. However, few studies have reported the interval required for union. Patients want to know the time until union and when they can start to wean out from the postoperative shoe or boot. It is understandable that the “earlier the union, the sooner the return to normal life.” The empirical period until bony union averages 6 weeks. Therefore, we chose a short interval before obtaining a postoperative CT scan to assess whether proper fusion had occurred. This allowed us to analyze whether 6 weeks of protected weightbearing in a hard-soled shoe was suffi- cient to promote osseous healing. Specific scientific reasons and interests exist for using CT scans to assess fusion. The ability to determine fusion on standard radiographs has been questioned, and CT scans have been proposed to allow a more accurate diagnosis of fusion (14). Some studies have focused on the importance of crossing osseous trabeculae running over the arthrod- esis site on radiographs as a criterion for fusion (17–20). Coughlin et al (14) compared standard radiographs and CT scans after arthrodesis of the hindfoot. They found poor agreement between the 2 methods and stated that fusion cannot be determined accurately from standard radiographs. They also suggested that joint bridging of 50% is suffi- Fig. Sagittal computed tomography scans showing fusion (n ¼ 41 feet in 39 patients) at cient to constitute joint fusion. They reported that fused joints in the 6 weeks postoperatively: (A) total fusion, (B) partial fusion at the dorsal aspect of the fused hindfoot with a partial fusion of 20% to 35% were clinically asymp- joint, and (C) no fusion. tomatic (14). Hill et al (21) introduced the term “spot weld,” referring to fusion of triple arthrodesis in their series, explaining that partial appointment, 31 patients underwent standard dorsoplantar radiog- fusion of the joint arthrodesis might be sufficient. raphy. In all, 28 (90.3%) were rated as having a completely fused joint The present study has demonstrated that 93% of cases demon- and 3 (9.7%) as having a partially fused joint. For the 3 cases rated as strated partial consolidation and 7% complete fusion of the first MTPJ partially fused, the patients reported no pain and demonstrated a mean at 6 weeks postoperatively. Joint bridging occurred over a mean 54% joint bridging of 40% 10% at 6 weeks postoperatively. of the area and was predominantly located in the dorsal to central, dorsal to medial, and central to central areas of the fused joint. This Complications distribution might relate to the areas at which the greatest amount of compression is experienced after application of the compression Hardware was removed in 7 cases because it was painful. In 1 clamp in the implant we used. The least amount of joint bridging was patient, revision arthrodesis was performed because of nonunion. The observed in the plantar to lateral and central to lateral aspects of the patient had Parkinson’s disease. One patient developed an ulcer fused joint. The locked plate construct can be considered a load- dorsal to the plate. This patient was taking immunosuppressant drugs sharing device, decreasing the motion and rotation across the first for rheumatoid arthritis and developed an infected nonunion. The MTPJ that cannot be accommodated by the interfragmentary hardware was removed. One patient demonstrated delayed union and compression screw (3). underwent revision arthrodesis. The patient was not compliant and The prevalence of nonunion after first MTPJ fusion has been had decided to mobilize in normal footwear instead the postoperative reported to range from 1% to 14% (9,12,22–24). In our series, the shoe provided. nonunion rate was 7%. Three patients required revision fusion to treat symptomatic nonunion. Two of these patients had a concomitant Discussion disease (Parkinson’s disease in 1 and rheumatoid arthritis treated with immunosuppressant drugs in 1) that could be a risk factor for Arthrodesis of the first MTPJ represents a reasonable treatment nonunion. The third patient had not been compliant with the rec- option for alleviating arthritis pain and can also be used as a salvage ommended postoperative regimen. Secondary arthrosis of the interphalangeal joint can result from Table 2 malpositioned first MTPJ fusion. Coughlin (25) reported that a dorsi- Patient reported pain level (N ¼ 41 feet in 39 patients) flexion angle of 20 for the fused first MTPJ was associated with a Pain Preoperatively Follow-up point greater prevalence of interphalangeal joint arthritis compared with an (N ¼ 41) angle of >20 . In our series, the mean postoperative dorsiflexion of 6wk(n¼ 40) 3 mo (n ¼ 35) >1yr(n¼ 37) the hallux was 23. We believe that with the prefabricated angulated None 0 (0) 23 (56) 21 (51) 28 (68) fi Mild occasional 1 (2) 15 (37) 12 (29) 8 (20) dorsal locking plates, the risk of rst MTPJ fusion malposition and Moderate daily 32 (78) 2 (5) 2 (5) 1 (2) concomitant rate of required revision operations is lower than that Severe, almost 8 (20) 0 (0) 0 (0) 0 (0) with other fusion devices. always present The present study had certain weaknesses and limitations. 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